Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-09-05
2003-12-23
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031600, C106S401000, C106S404000, C106S436000, C106S447000
Reexamination Certificate
active
06666913
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a water-based ink composition which is outstanding in writing properties and hiding power, among other characteristics.
BACKGROUND OF THE INVENTION
A variety of water-based inks has heretofore been developed and in use for markers, ball-point pens and felt pens. Water-based inks are required to have good hiding power in addition to satisfactory writing properties. When the hiding power is low, no sufficient density can be imparted to written images. The result is that writings are not sufficiently legible. On the other hand, if an excessive colorant is incorporated for enhanced opacity power, the ink will suffer from a decrease in dispersibility, affecting writing properties adversely as a consequence.
From the above point of view, many attempts have been made to have writing properties and hiding power reconciled in the ink.
Unexamined Japanese Patent Publication H8-231916 discloses a water-based white pigment ink for ball-point pen use which contains at least a titanium dioxide having an oil absorption capacity of not less than 30 (g/100 g), a titanium dioxide having an oil absorption capacity of less than 30 (g/100 g), a binder, a viscosity-building (thickener) water-soluble resin, and water, the pH of which ink is higher than the isoelectric point of the titanium dioxide having an oil absorption capacity of not less than 30 (g/100 g) and which has a viscosity of 6000~50000 centipoises (type E viscometer, st rotor, 1 rpm, 25° C.).
Unexamined Japanese Patent Publication H6-192611 discloses a water-based pigment ink composition for writing use characterized in that it comprises at least a composite powder having a mean particle diameter of 0.2-2 &mgr;m as obtained by depositing a micronized titanium dioxide having a mean particle diameter of not greater than 0.1 &mgr;m as a colorant on the surface of a resin powder.
Unexamined Japanese Patent Publication H6-287499 discloses a water-based white pigment ink for ball-point pen use which comprises a white pigment, a tabular silicate, a water-soluble resin, a water-soluble organic solvent, and water and has a viscosity of 6000~100000 cps (type-E viscometer, at rotor, 1 rpm, 25° C.).
Unexamined Japanese Patent Publication 2000-119579 discloses a water-based ink composition for ball-point pen use which comprises at least water, a thixotropic agent and, as colorant, a pearlescent pigment comprising a mica the surface of which has been covered with titanium dioxide in a thickness of 40~60 &mgr;m.
Unexamined Japanese Patent Publication 2000-129187 discloses.
Unexamined Japanese Patent Publication 2000-265125 discloses a water-based white ink composition for ball-point use which comprises a titanium dioxide-containing microencapsulated pigment, water, and a water-soluble organic solvent as essential components.
International Publication WO 98/36033 discloses a white pigment ink for water-based ball-point pen use which comprises titanium dioxide, a complementary colorant comprising a pigment or a pseudopigment obtainable by dying emulsion resin particles with a dyestuff, a resin emulsion having a mean particle diameter of not less than 200 nm, a thickener, water, and a polar solvent.
Unexamined Japanese Patent Publication H9-10435 discloses a water-based ink composition for ball-point use which essentially comprises a pigment or a colored resin emulsion, a dispersant, a water-soluble organic solvent, and water characterized in that said composition further contains a defined phosphoric ester.
Unexamined Japanese Patent Publication H9-227820 discloses a water-based ball-point ink composition characterized in that it comprises a colorant, water, a water-soluble polar solvent, and a fatty acid amide expressing a thixotropic action (e.g. oleic diethanolamide).
SUMMARY OF THE INVENTION
However, even those water-based inks have room for improvement in the aspect of reconciling writing properties and hiding or hiding power.
It is, therefore, a primary object of the present invention to provide a water-based ink composition improved in both hiding power and writing properties.
Means for Solving the Problems
As the result of their intensive research for overcoming the above-mentioned disadvantages of the prior art, the inventor of the present invention found that the above object can be accomplished by using an ink composition containing a defined inorganic powder and have ultimately developed the present invention.
The present invention, therefore, is directed to the following water-based ink compositions.
1. A water-based ink composition comprising a water and a powder consisting of inorganic particles comprising at least one of aluminum oxide, titanium dioxide, and boron nitride.
2. The water-based ink composition according to the above paragraph 1 wherein the inorganic particles 1) comprise titanium dioxide and have a surface conversion layer 2) contain Al, Si, Zn and Zr, and 3) have an Al/(Al+Si+Zn+Zr) weight ratio of not greater than 0.5,
said composition further comprising a water-soluble polymer.
3. The water-based ink composition according to the above paragraph 2, the water-soluble polymer content of which is 0.1~3 weight %.
4. The water-based ink composition according to the above paragraph 1 wherein the inorganic particles are scaly particles of at least one kind selected from the group consisting of scaly alumina particles and scaly boron nitride particles,
said composition further comprising a water-soluble polymer.
5. The water-based ink composition according to the above paragraph 4 not containing a colorant other than the scaly particles.
6. The water-based ink composition according to the above paragraph 1 wherein the inorganic particles are scaly alumina,
said composition further comprising a colorant, a water-soluble organic solvent, and a water-soluble polymer.
7. The water-based ink composition according to the above paragraph 6 wherein the aspect ratio of the scaly alumina is not less than 5.
8. The water-based ink composition according to the above paragraph 7 wherein the colorant comprises a colored resin bead dispersion.
9. The water-based ink composition according to the above paragraph 1 wherein the inorganic particles are comprised of a white scaly pigment.
10. The water-based ink composition according to the above paragraph 9 wherein the colorant is at least one white scaly pigment selected from the group consisting of boron nitride and alumina flakes.
11. The water-based ink composition according to the above paragraph 9 further comprising a water-soluble polymer and a water-soluble organic solvent.
12. A writing instrument comprising the water-based ink composition defined in the above paragraph 1 as its ink component.
In this specification, the invention defined in the above paragraph 1 is referred to as the “basic invention”. The invention corresponding to the above paragraph 2 is referred to as the “first invention”. The invention corresponding to the paragraph 4 is referred to as the “second invention”. The invention corresponding to the paragraph 6 is referred to as the “third invention”. The invention corresponding to the paragraph 9 is referred to as the “fourth invention”.
DETAILED DESCRIPTION OF THE INVENTION
The basic invention according to the present invention relates to a water-based ink composition comprising a water and a powder consisting of inorganic particles which contain at least one of aluminum oxide, titanium dioxide, and boron nitride and water.
It is sufficient that said inorganic particles contain at least one of aluminum oxide, titanium dioxide, and boron nitride. For example, each particle may be either composed of aluminum oxide alone or composed of aluminum oxide and other ingredient or ingredients. The ingredients of such inorganic particles can be selectively used in the first through the fourth invention to be described hereinafter. Moreover, as to components other than said powder and water, the components used in known inks can be judiciously formulated according to each of the embodiments of the invention whic
Hirano Norihiro
Kurihara Norimasa
Sudo Atsushi
Yoshimura Yasuyuki
Bell Mark L.
Faison Veronica F.
Knobbe Martens Olson & Bear LLP
Sakura Color Products Corporation
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