Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-06-21
2004-01-13
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031470, C106S031490, C106S031580, C106S031760, C106S031770, C106S031780, C106S031860
Reexamination Certificate
active
06676735
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a high reliability aqueous ink which provides prints having an excellent light-resistance and print quality, exhibits a high storage stability and an excellent reliability in objection and doesn't clog nozzle particularly when used as an ink for ink jet recording.
The present invention also relates to an aqueous ink for ink jet recording which can provide prints having an excellent light-resistance.
The present invention further relates to a high reliability aqueous ink which provides prints having an excellent light-resistance and print quality, exhibits a high liquid stability and an excellent storage stability and doesn't clog nozzle particularly when used as an ink for ink jet recording.
The present invention further relates to an ink for ink jet recording which can form an image having an excellent light-resistance and a high quality.
DESCRIPTION OF RELATED ART
In an ink jet recording method, an ink droplet is directly ejected from a very fine nozzle onto a recording medium so that it is attached thereto to obtain letters and images. Referring to principle of operation, this recording method can be carried out by various methods such as deflection method, cavity method, thermojet method, bubble jet method and thermal ink jet method. However, in any ink jet recording method, ink droplets must be continuously and stably ejected from a fine nozzle. Therefore, the ink jet recording ink is required to prevent itself from clogging the nozzle in addition to being excellent in various properties such as storage stability, reliability in ejection and print quality similarly to ordinary inks.
In recent years, an ink jet printer has widely spread. An ink jet recording method can print a high fidelity image with a high resolution at a high speed using a relatively inexpensive apparatus. In particular, a color ink jet recording apparatus can form images with an enhanced quality and can be used also as a photographic output machine. The color ink jet recording apparatus has been used even as digital printer, plotter, CAD output device, etc. Images thus printed by the ink jet recording printer which has found wide application can be used in various ways. For example, photograph grade prints are possibly put as display in places where they can be exposed to fluorescent light or sunshine outdoor over an extended period of time. Accordingly, light-resistance is one off extremely important requirements for ink composition for use in ink jet recording. It is also desired in the art of photograph grade printing that the image thus formed has so high a quality that it has little running and a good color development.
Further, as an aqueous ink there is mainly used an aqueous dye ink from the standpoint of handleability and color reproducibility. However, such an aqueous ink comprises photosensitive optical deterioration-initiating factors incorporated in the colorant or solvent constituting the ink and thus is disadvantage in that the colorant undergoes photo-oxidation and hence so-called photo-deterioration such as discoloration. Accordingly, the prints obtained by ink jet recording with such an ink exhibit a deteriorated light-resistance and thus is disadvantageous in that they are subject to disappearance of recorded letters or discoloration of recorded images in a relatively short period of time even when posted on the wall or under any other ordinary conditions.
In order to solve the foregoing problems, it has been heretofore practiced to incorporate a light-resistance improver such as ultraviolet absorber, light-stabilizer and oxidation inhibitor in a dye ink. For example, it is disclosed in “
Dyes and Pigments
19”, 1992, pp. 235-247, that the incorporation of 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl as a hindered amino-based light-stabilizer in an aqueous solution containing a dye makes it possible to prevent photo-deterioration of the dye. JP-A-11-170686 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”), which was filed after the issue of the above cited reference (“
Dyes and Pigments
19”), discloses a technique which comprises incorporating a specific compound (2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl as mentioned above or derivative thereof) in an aqueous recording solution for ink jet recording containing a water-soluble dye to stabilize the water-soluble dye. The foregoing compound acts to capture radicals such as R. (alkyl radical) produced by optical excitation of a carbonyl compound or the like and ROO. (peroxide radical) produced by the reaction or R. with oxygen in the air to stop the progress of photo-oxidation reaction of the colorant and hence inhibit photo-deterioration thereof and thus is effective as a light-resistance improver.
Although the foregoing aqueous recording solution for ink jet recording, even if it comprises foregoing specific compound effective as a light-resistance improver, can provide prints no letter and/or images having improved properties, it is disadvantageous in that it is subject to disappearance of recorded letters or discoloration of recorded images in a long range.
The foregoing aqueous recording solution for ink jet recording also exhibits a deteriorated print quality, storage stability and reliability in ejection and a low reliability and thus can clog the nozzle particularly during ink jet recording.
The foregoing aqueous recording solution for ink jet recording also exhibits a low liquid stability and a deteriorated storage stability and thus can clog the nozzle during ink jet recording.
Since an ink jet recording printer forms droplets by applying pressure to a liquid ink, the ink ejection pressure can be absorbed by the ink, if bubbles or bubble nuclei are present therein, occasionally disabling the ink from being ejected from the nozzle.
The production of bubbles or bubble nuclei in the ink passage of the printer can be caused by the entrance of bubbles from the ink supply portion or from the nozzle portion of the printing head. In the former case, the ink is bubbled during its preparation or use to produce bubbles therein. In order to overcome this case of trouble, it is devised to deaerate the ink during preparation and then put it in a vessel having a low air permeability so that the entrance of air into the ink can be inhibited. In order to prevent the entrance of air from the connection between the ink tank and the supply inlet, the connection is sealed with a rubber packing or the like to enhance the air-tightness of the passage. In the latter case, on the other hand, the entrance of bubbles due to destruction of ink meniscus in the nozzle portion can be a main cause. The cause of destruction of ink meniscus can be impact or scanning by the printing head. In order to prevent these troubles, it can be proposed to enhance the surface tension and impact resistance of an ink. However, such an ink having an enhanced surface tension and impact resistance penetrates into the recording medium at a reduced rate, occasionally exerting fatal effects on image quality, e.g., deteriorated print quality such as blurred profile in color image. It has thus been desired to provide an aqueous ink which can be prevented from being bubbled without raising its surface tension for the purpose of giving an excellent print stability while maintaining desired print quality.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a high reliability aqueous ink which provides prints having an excellent light-resistance and print quality, exhibits a high storage stability and an excellent reliability in ejection and doesn't clog nozzle particularly when used as an ink for ink jet recording.
It is another object of the present invention to provide an aqueous ink capable of providing prints which are so excellent in light-resistance that they are not subject to disappearance of recorded letters or discoloration of recorded images for a long period of time.
It is a further object of the present invention to
Aoyama Tetsuya
Ito Yuji
Kitamura Kazuhiko
Oki Yasuhiro
Takahashi Hiroshi
Klemanski Helene
Seiko Epson Corporation
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