Compositions: coating or plastic – Materials or ingredients – Pigment – filler – or aggregate compositions – e.g. – stone,...
Reexamination Certificate
2002-06-27
2004-04-27
Green, Anthony J. (Department: 1755)
Compositions: coating or plastic
Materials or ingredients
Pigment, filler, or aggregate compositions, e.g., stone,...
C106S031600, C106S031750, C106S031770, C106S031780, C106S031800, C106S031900, C106S401000, C106S410000, C106S494000, C106S495000, C106S496000, C106S497000, C106S498000, C347S100000, C347S112000, C349S106000, C427S162000, C430S007000
Reexamination Certificate
active
06726762
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to finely divided pigments, and has an object thereof the provision of finely divided pigments useful for various applications, for example, as pigments for printing inks (gravure inks, offset inks, flexographic inks, etc.), plastic colorants, pigment-type textile printing agents, pigments for paints, image recording agents, and pigments for image displaying. The term “pigment” as used herein means an aggregate of fine coloring particles, whereas the term “pigment particles” as used herein means “fine coloring articles making up a pigment”. Further, the term “secondary particles” as used herein means particles formed by agglomeration of finely divided pigment particles (primary particles) and having greater particle sizes.
b) Description of the Related Art
Pigments have conventionally been used as coloring agents for paints, printing inks, plastics and the like. In each of these pigments, fine particles (primary particles) which make up the pigment have already undergone agglomeration, and the agglomerated particles (secondary particle) have particles sizes around 10 to 20 &mgr;m. A pigment formed of particles of such large particle sizes cannot be used as a coloring agent for paints or printing inks. Therefore, the pigment is used after mechanically milling or grinding it together with a paint vehicle or a printing ink varnish in a pigment dispersing machine, for example, a ball mill, sand mill, attritor, horizontal continuous disperser with tumbling medium contained therein, vertical continuous disperser with tumbling medium contained therein, kneader or three-roll mill such that particles making up the pigment are dispersed with particle sizes of from about 0.5 to 0.2 &mgr;m in the vehicle or varnish.
In applications where dyes have been employed as coloring agents to date, pigments have been finding increasing utility in recent years for their excellent lightfastness and waterproofness. These applications include, for example, inks for writing instruments, in which aqueous dyes or oil-soluble dyes have been used as coloring agents, and colorants for plastics, in which oil-soluble dyes have been used as coloring agents as transparency is required. Further, there are also increasing demands for pigments as coloring agents for LCD color filters, coloring agents for ink-jet recording inks and coloring agents for color toners.
For these applications, it is necessary to divide pigment-forming particles (pigment particles) as finely as possible (0.1 &mgr;m or smaller). As a method for finely dividing pigment particles, it is known to use a high-speed sand mill or the like. Further, to provide a colored article with transparency and vividness or sharpness, it is necessary to finely divide pigment particles and at the same time, to sift pigment particles to control their sizes (to make their particle size distribution narrower). Moreover, it is also important to evenly disperse the finely divided pigment particles in a vehicle and during storage of the dispersion, to provide the dispersion with stability such that the pigment particles remain in their finely divided form without undergoing agglomeration.
SUMMARY OF THE INVENTION
An object of the present invention is, therefore, to provide a finely divided pigment, which is usable not only as a coloring agent for paints, printing inks, plastics and the like but also as a coloring agent for LCD color filters, ink-jet recording inks, color toners and the like to obtain colored products having a transparent, vivid and sharp color hue and also properties such as excellent lightfastness, outstanding weatherability and superb heat resistance. Another object of the present invention is to provide a coloring composition comprising the finely divided pigment as a colorant.
To achieve the above-described objects, the present inventors have proceed with an extensive investigation. As a result, it has been found that irrespective of the kind of a pigment, the above-described objects can be achieved by finely dividing the pigment particles to obtain a particular particle size distribution, leading to the completion of the present invention
In one aspect of the present invention, there is thus provided a finely divided pigment formed of an aggregate of primary particles, wherein a number of primary particles of not greater than 0.1 &mgr;m in particle size is at least 95% of an entire number of the primary particles, and a number of primary particles of greater than 0.1 &mgr;m in particle size is at most 5% of the entire number of the primary particles.
In another aspect of the present invention, there is also provided a process for producing the finely divided pigment, which comprises grinding a parent pigment together with a water-soluble inorganic salt and a water-soluble organic solvent in a grinding machine at a temperature of from 30 to 90° C. for 2 to 6 hours under a load, and then removing the water-soluble inorganic salt and the water-soluble organic solvent.
In a further aspect of the present invention, there is also provided a coloring composition comprising a dispersing medium and the finely divided pigment dispersed in the dispersing medium. The coloring composition may be an image recording agent for the ink-jet recording system, an image recording agent for the electronic printing or electrostatic recording system, or a coloring agent for forming color filter pixels.
In a further aspect of the present invention, there is also provided a process for coloring an article, which comprises using the coloring composition.
In a still further aspect of the present invention, there is also provided an image recording apparatus of the ink-jet recording system or the electronic printing or electrostatic recording system, comprising the image recording agent for the ink-jet recording system or the image recording agent according for the electronic printing or electrostatic recording system mounted as an image recording agent.
In a still further aspect of the present invention, there is also provided a process for manufacturing a color filter, which comprises forming a color pattern on a color filter substrate by using the coloring agent for forming color filter pixels.
In a yet further aspect of the present invention, there is also provided a color filter manufactured by the manufacturing process.
When the finely divided pigment according to the present invention is used as a coloring agent in plastics, pigment-type textile printing agents, printing inks, paints, especially metallic paints, or the like, the finely divided pigment exhibits, on colored products or articles, excellent dispersion and superb properties such as weatherability, lightfastness and heat resistance while retaining transparency, vividness and sharpness comparable with dyes. In addition, the finely divided pigment according to the present invention is also useful as a pigment in image recording agents for the ink-jet recording system, image recording agents for the electronic printing or electrostatic recording system and coloring agents for forming pixels on color filters.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
The present invention will hereinafter be described in further detail based on certain preferred embodiments.
The finely divided pigment according to the present invention is characterized in that the number of primary particles of not greater than 0.1 &mgr;m in particle size is at least 95% of the entire number of the primary particles, and the number of primary particles of greater than 0.1 &mgr;m in particle size is at most 5% of the entire number of the primary particles. When fastness, such as heat resistance and weatherability, of the pigment is taken into consideration, the number of primary particles of not greater than 0.02 &mgr;m in particle size may preferably be at most 10% of the entire number of the primary particles. By finely dividing the pigment particles into such a particle size range, it is possible to provide a colored product with both a color
Abe Yoshio
Nakagawa Yutaka
Nakamura Michiei
Okamoto Hisao
Takami Shotoku
Dainichiseika Color & Chemicals Mfg. Co. Ltd.
Green Anthony J.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
LandOfFree
Finely divided pigments and coloring compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Finely divided pigments and coloring compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Finely divided pigments and coloring compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3261881