Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-06-22
2004-05-25
Egwim, Kelechi C. (Department: 1713)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C347S047000, C347S100000, C427S466000, C524S500000, C524S501000
Reexamination Certificate
active
06740152
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording liquid for ink printers, a method for manufacturing such a recording liquid, and a method for image recording, and in particular relates to a recording liquid for ink printers which contains pigments and the fine particles of two or more resins, a method for manufacturing such a recording liquid, and a method for image recording using such a recording liquid.
2. Discussion of the Related Art
As an output device for information equipment such as computers, ink printer systems are attracting public attention. Such systems include an ink-jet system which is a method of image recording for recording images on recording media by discharging the droplets of a recording liquid from a head, as a system of low running costs and of easy color printing, or ink printer systems such as an acoustic ink printer system disclosed in Japanese Patent Application. Laid-Open No. 6-102378 (1994). Heretofore, as a recording liquid for such ink printers, an aqueous solution of a dye mainly containing water and a dye has mainly been used. By such a solution, however, when the recording liquid discharged from the nozzle arrives at a recording medium such as recording paper, the solution bleeds on the recording paper and produces dots significantly larger than the droplets of the recording liquid formed when discharged from the nozzle, resulting in the low density of recorded images, and thus the low image quality. Also, since the water resistance of recorded images is low, images are easily blurred or flowed by water. In addition, since the light resistance of recorded images is low, images are easily discolored by irradiation of sunlight or the like.
In order to solve these problems of aqueous dye solutions, recording liquids for ink printers that contain film-forming resin particles have been disclosed. For example, a recording liquid containing latex as resin particles is disclosed in Japanese Patent Publication No. 60-32663 (1985); a recording liquid that contains a resin having carboxyl groups and nonionic hydrophilic groups dispersed in water is disclosed in Japanese Patent Laid-Open No. 5-239392 (1993); a recording liquid that contains vinyl polymers having a non-cross-linking structure is disclosed in Japanese Patent Laid-Open No. 5-255628 (1993); a recording liquid that contains polyester particles having ionic groups is disclosed in Japanese Patent Laid-Open No. 6-340835 (1994); and a recording liquid that contains dyed resin particles is disclosed in Japanese Patent Laid-Open No. 5-255567 (1993). A process of compounding fine particles of a resin such as polyester, and a cross-linking agent, and cross-linking the resin on a recording medium is disclosed in Japanese Patent Publication No. 7-47355 (1995). Also, the inventors of the present invention disclosed a recording liquid containing pigments and fine particles of two or more resins in Japanese Patent Application Nos. 10-88045 (1998) and 10-88056 (1998). (U.S. patent application Ser. No. 08/925,391 that will be issued soon)
However, any of the recording liquids disclosed in above-mentioned Japanese Patent Publication No. 60-32663, Japanese Patent Laid-Open Nos. 5-239392, 5-255628, 6-340835, and 5-255567 (1993), and Japanese Patent Publication No. 7-47355 (1995) clogs the discharging nozzles, and cannot be stably discharged from the nozzles because a film-forming process of fine particles of resins starts following evaporation of moisture of the recording liquid due to contact with the air at the discharging nozzle of the recording head. Even if the recording liquid can be discharged initially, the bleeding of the recording liquid due to the capillary action into the fibers of recording paper cannot be completely prevented, and high-quality images cannot be obtained. Furthermore, the permeation of the recording liquid into recording paper cannot be completely prevented, and there is limitation in the formation of high-density, high-quality images. Similarly, there is limitation in water resistance. When the above-disclosed recording liquid is diluted by water in order to prevent clogging at the discharging nozzle, the content of resin particles relatively contained in the same volume of the droplets of the recording liquid, that is, the resin solid content contributing to image formation, decreases so that image density is markedly reduced, and high-quality images cannot be obtained. By the use of the above-disclosed conventional recording liquids, an increase in image density to achieve high-quality images by increasing the content of resin particles (increase in resin solid content) is incompatible with the prevention of discharging nozzle clogging. Although an increase in image density to achieve high-quality images by increasing the content of resin particles (increase in resin solid content) is compatible with the prevention of discharging nozzle clogging by the use of recording liquids disclosed in Japanese Patent Laid-Open Nos. 10-88045 and 10-88056, the stability of discharging must be improved when a large number of sheets are printed using a practically used ink printer.
The present invention has been made in view of the above circumstances and provide a recording liquid for ink printers that does not bleed on nor permeate into recording paper, can obtain water-resistant high-quality images with very high image density, and can be discharged continuously and stably without nozzle clogging, and a method for manufacturing such a recording liquid for ink printers. The present invention also provides a method for recording images by the use of such a recording liquid.
SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided a recording liquid for ink printers containing a pigment and two or more kinds of fine resin particles, wherein the dispersion polarity of the pigment is the same as the dispersion polarity of each of the two or more kinds of fine resin particles.
According to another aspect of the present invention, there is provided a method for manufacturing a recording liquid for ink printers having the step of mixing an aqueous dispersion of a pigment, and an aqueous dispersion of two or more kinds of fine resin particleseach having a polarity same as the polarity of the aqueous dispersion of the pigment.
According to another aspect of the present invention, there is provided a method for recording images on a recording medium by discharging the droplets of the recording liquid from a recording head, wherein the above described recording liquid is used as the recording liquid.
The reason why the achievement of high image density by increasing the content of resin particles (increase in resin solid content) becomes compatible with the prevention of clogging at the discharging nozzle or open mouth of the recording head by the use of the recording liquid of the present invention is considered to be as follows.
Since the recording liquid contains an aqueous dispersion of pigments and an aqueous dispersion of fine particles of two or more different resins, and all of these aqueous dispersions have the same polarity (ionicity), the probability that the fine particles of the same type of resins are present around a certain type of resin particles, i.e. the closest coordinating location decreases (coordination effect), and inter-particle repulsion (repulsive force) caused by the same ionicity is produced between the fine particles of different resins as well. In addition to inter-particle repulsion (repulsive force) between the fine particles of different resins, inter-particle repulsion (repulsive force) caused by the same ionicity is also produced between the pigments and resin particles. This produces a consistent repulsive force field in the dispersion system of resin particles and pigment particles in water, and the probability of approaching or collision of resin particles by themselves or resin particles and pigment particles decreases.
These effects prevent a series of processes causing cloggi
Egwim Kelechi C.
Fuji 'Xerox Co., Ltd.
Morgan & Lewis & Bockius, LLP
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