Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-06-21
2001-04-24
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031750, C106S031770, C106S031890, C106S475000
Reexamination Certificate
active
06221141
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pigment ink, an ink-jet recording process, a recording unit, an ink cartridge and an ink-jet recording apparatus.
2. Related Background Art
With the spread of ink-jet recording systems, it has become a priority to improve the quality and fastness properties of prints. With respect to fastness properties of prints, for example, water fastness, Japanese Patent Application Laid-Open No. 4-226175 and U.S. Pat. No. 5,053,495 disclose novel black dyes and inks which can provide images having good water fastness.
Black inks using a pigment have been reported to form black images excellent in print quality and fastness properties such as water fastness and light fastness on plain paper.
For example, Japanese Patent Application Laid-Open No. 5-179183 discloses a pigment ink stabilized with a block copolymer of the AB or BAB type. Japanese Patent Application Laid-Open No. 6-136311 discloses a pigment ink which comprises a block copolymer composed of a hydrophobic polymer having a basic amine functional group and a hydrophilic polymer having nonionic and acidic functional groups, which can provide prints of excellent quality and has excellent dispersion stability. Japanese Patent Application Laid-Open No. 7-53841 has proposed a pigment ink for ink-jet, which comprises a triblock copolymer of the ABC type, has excellent dispersion stability and can provide prints of excellent quality.
On the other hand, pigment inks using, as a coloring material, the so-called self-dispersing type carbon black, which does not require the addition of any dispersing agent to the inks, have been proposed with a view toward improving the ejection stability thereof upon ink-jet recording. For example, U.S. Pat. Nos. 5,554,739 and 5,571,311 disclose a production process of self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded directly or through another atomic group. A pigment ink comprising such self-dispersing type carbon black can provide prints of excellent quality and has excellent dispersion stability without using any block copolymer.
SUMMARY OF THE INVENTION
The present inventors have carried out various investigations as to ink-jet suitability of pigment inks comprising such self-dispersing type carbon black as a coloring material. As a result, it has been found that when a silicon compound is contained in such an ink, fluctuation in the ejection efficiency of the ink can be reduced, thereby effectively preventing the ejection quantity of the ink from varying with individual heads and printing environment.
It is an object of the present invention to provide a pigment ink which can form images excellent in fastness properties, such as water fastness and light fastness, and character quality, which can be efficiently ejected when applied to ink-jet recording and moreover can be stably ejected from a recording head irrespective of recording head and printing environment.
Another object of the present invention is to provide an ink-jet recording process which permits the stable formation of images excellent in water fastness and light fastness that are of high quality.
A further object of the present invention is to provide a recording unit, ink cartridge and ink-jet recording apparatus which permit the stable provision of images excellent in water fastness and light fastness that are of high quality by ink-jet recording.
Incidentally, the ejection efficiency as used herein means a proportion of thermal energy converted into the kinetic energy of an ink.
The above objects can be achieved by the present invention described below.
According to the present invention, there is thus provided a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound.
According to the present invention, there is also provided an ink-jet recording process, comprising the step of applying energy to a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound to eject the pigment ink from an orifice toward a recording medium.
According to the present invention, there is further provided a recording unit comprising an ink container portion containing an ink, and a head portion from which the ink is ejected, wherein said ink is a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound.
According to the present invention, there is still further provided an ink cartridge comprising an ink container portion containing an ink, wherein said ink is a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound.
According to the present invention, there is yet still further provided an ink-jet recording apparatus comprising a recording unit, wherein the recording unit has an ink container portion containing a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound; and a recording head for applying energy to the ink to eject the ink from an orifice.
According to the present invention, there is yet still further provided an ink-jet recording apparatus comprising an ink cartridge equipped with an ink container portion which contains a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon compound; and a recording head for applying energy to the pigment ink to eject the ink from an orifice.
According to the present invention, there is yet still further provided a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, an aqueous medium, and a silicon atom.
By adopting such constitution, there can be brought about an effect that images excellent in fastness properties such as water fastness and light fastness that are of high quality can be stably formed in ink-jet recording.
The reason why the water-based pigment inks according to the present invention exhibit the above-described effect, and particularly, can achieve excellent ejection efficiency and can be stably ejected upon ink-jet recording is not known. However, the present inventors have already found that when a uniform film of a pigment is formed on the surface of a heater upon ejection of a pigment ink by a bubble jet system (a system where thermal energy is applied to an ink using a heater to eject the ink from an orifice), the bubbling of the ink can be stabilized to achieve high ejection efficiency, and that impurities in a pigment ink comprising self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, particularly, impurities derived from the self-dispersing type carbon black to the surface of which at least one hydrophilic group is bonded through another atomic group, aid in ejection efficiency and ejection stability. It is thus considered from these findings that the effect of the present invention is achieved by the following action. Namely, for example, in the ink-jet recording system where thermal energy is applied to an ink to eject the ink, voltage is applied to a heater to rapidly heat up the heater, whereby the ink adjacent to the surface of the heater reaches the limit of heating to generate bubbles, thereby ejecting the ink. The generation of bubbles tends to be affected by the heater surface condition, and so the ejection of the ink is greatly influenced by the condition of t
Mishina Shinya
Osumi Koichi
Sanada Mikio
Takada Yoichi
Takizawa Yoshihisa
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Klemanski Helene
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