Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1996-08-29
2002-04-16
Copenheaver, Blaine (Department: 1771)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S529000, C524S530000, C260SDIG031, C106S031270
Reexamination Certificate
active
06372818
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-based ink suitable for use in ink-jet recording in which an ink is ejected and flown as droplets from an ejection opening (orifice), and these ink droplets are applied to a surface of a recoding medium, thereby conducting recording, and an ink-jet recording method and instruments using such an ink, and particularly to an ink-jet ink capable of preventing occurrences of feathering and bleeding and forming images high in color strength, and an ink-jet recording method and instruments using such an ink. According to the present invention, additional mechanisms required to enhance a recording performance of the instruments are also simplified, so that increase in cost is effectively checked, and at the same time, energy saving can be achieved.
2. Related Background Art
Water-based inks have heretofore been principally used as ink-jet recording inks from the viewpoint of safety, odor and the like. There have been known inks in which one or more of various water-soluble dyes or pigments are used as coloring materials and dissolved or dispersed in water or a mixed solvent of water and a water-soluble organic solvent, and a humectant, a dye-dissolving aid, a mildewproofing agent and/or the like are added thereto as needed. For the past few years, ink-jet recording using such inks has conspicuously spread because it has such many advantages as the inks can be ejected in a proportion of several thousand droplets per second to conduct high-speed recording with ease, noise is scarcely produced, multi-color recording can be performed with ease, high-resolution recording can be effected, and recording can be conducted on plain paper.
With the development of low-cost and high-performance personal computers and the standardization of GUI environment in recent years, even image recording by printers or the like has been required to achieve high coloring, high quality, high fastness properties, high-resolution recording, high-speed recording and the like. In response to this requirement, various technical ideas that a coloring material component is left on the surface of paper as much as possible to increase the optical density of images to be formed, edges of printed dots are made sharp, and the occurrence of feathering, bleeding and the like is lessened are also being proposed in ink-jet recording.
As a first example thereof, Japanese Patent Application Laid-Open No. 58-13675 discloses a method of controlling an absorption and spreading of recording dots in and on paper by adding polyvinyl pyrrolidone to an ink. As a second example thereof, Japanese Patent Application Laid-Open No. 3-172362 discloses a method of controlling the absorption of an ink and the spreading of dots by adding a specific microemulsion to the ink.
As a third example in which a sol-gel transition phenomenon is applied to an ink, Japanese Patent Application Laid-Open Nos. 62-181372 and 1-272623, etc. each describe an ink which is in a gel state at room temperature, but turns to a sol state by heating. It is said that according to such an ink, a penetration of the ink into paper can be controlled because recording on a recording medium is conducted in a sol state, and the ink turns to a gel state by its cooling.
As a fourth example, Japanese Patent Application Laid-Open No. 6-49399 has recently disclosed an ink, to which a compound having reversibly and thermally gelling property is added, and which has a good coloring ability and a fixing ability, causes little feathering, provides prints excellent in shelf stability, and is also excellent in reliability, and an ink-jet recording method and instruments using such an ink. The technical background thereof is based on a phenomenon that when an aqueous solution of a specific water-soluble polymer is gradually heated, its water-solubility is lowered, and so the solution becomes cloudy (a temperature at which such a phenomenon occurs is called “clouding point”).
Typical examples of the water-soluble polymer include poly(N-isopropylacrylamide), poly(vinyl methyl ether), polyethylene oxide and hydroxypropylcellulose. Since these polymers have a negative temperature coefficient as to solubility, they are in a state separated and deposited from a solution at a temperature not lower than the clouding point. In such a deposited state, hydrophobic microgel is formed, and a viscosity of the solution decreases. When recording is conducted on a recording medium in a deposited state, the viscosity of the solution returns to the initial viscosity, i.e., increases, owing to the temperature drop on the recording medium, and so the penetration of the ink can be prevented.
As a fifth example, M. Croucher et al. have indicated problems involved in the conventional homogeneous inks and moreover proposed, as a future ink for ink-jet, a heterogeneous ink making good use of a latex [M. D. Croucher and M. L. Hair; “Design Criteria and Future Directions in Inkjet Ink Technology”, Ind. Eng. Chem. Res., 28, 1712-1718 (1989)].
U.S. Pat. No. 4,246,154 discloses an ink in which fine particles of a vinyl polymer are colored with a dye and anionically stabilized. U.S. Pat. No. 4,680,332 also discloses a heterogeneous ink in which a water-insoluble polymer containing an oil-soluble dye and combined with a nonionic stabilizer is dispersed in a liquid medium. Further, in U.S. Pat. No. 5,100,471, there has been proposed a water-based ink comprising a solvent and colored particles composed of a polymer core and a silica shell to which a dye has been bonded by covalent bonding. The patent describes this ink as having such features as it produces a brighter color on paper, is stable to temperature change, and provides images high in water fastness.
On the other hand, as a sixth example, it has been proposed in Japanese Patent Application Laid-Open No. 3-240586 to use, as a nonaqueous ink, an ink in which colored particles coated with a resin which swells with a dispersion medium are dispersed in kerosene or the like. In this proposal, it is said that the ink is effective in, particularly, prevention of image feathering and of clogging at an orifice for ejecting ink droplets.
As a seventh example, further, Japanese Patent Application Laid-Open No. 63-87279 discloses, as a recording means for permitting a provision of high-quality images free of any feathering irrespective of paper, an ink-jet recording method in which an ink applied to a recording medium is heated at a temperature (80 to 140° C.) higher than room temperature in such a manner that physical property values of the ink become the desired values depending upon the combination of the recording paper and the ink.
However, the above-described first and second examples of the prior art involve a problem of the fixing ability of the ink in that since the penetration into paper is prevented, the ink does not penetrate into the paper, but remains on the paper for a long time. A problem that color mixing (bleeding) between inks of different colors also arises.
The ink based on the sol-gel transition of the third example involves a problem that running behavior may arise due to changes in storage temperature of the resulting prints, and so staining by color mixing and transfer due to running of images occurs.
The ink containing the reversibly and thermally gelling compound of the fourth example is unfit for a recording method in which one pixel is recorded at a high speed in several tens of milliseconds or shorter like ink-jet recording because it uses a water-soluble cellulose ether, and so its viscosity increase is slow. If the ink is used in ink-jet recording, such a compound must be used in a low concentration because the upper limit of viscosity upon ejection of the ink is as low as at most 20 mpa·s. It is hence difficult to sufficiently achieve a thickening effect.
On the other hand, among the fifth example group, the ink in which a coloring material has been anionically stabilized involves a problem that a pH region in which the coloring material is s
Kimura Isao
Kubota Hidemi
Maeda Hiroyuki
Shimomura Masako
Canon Kabushiki Kaisha
Copenheaver Blaine
Fitzpatrick ,Cella, Harper & Scinto
Guarriello John J.
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