Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2002-02-06
2004-03-09
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031320, C106S031580, C106S031640, C106S031860
Reexamination Certificate
active
06702881
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to ink for an ink-jet printer containing a fluorescent compound which has no absorption in the visible light range, and which emits fluorescence by ultraviolet irradiation. The invention also relates to ink for ink-jet printer containing a fluorescent compound which has absorption in the visible light range, and which emits fluorescence by ultraviolet irradiation.
2. Description of Related Art
Ink-jet printing is performed in such a way that letters, graphics, and images are directly printed on recording media by ejecting ink from a fine nozzle as droplets. A drop-on-demand system and a continuous system are exemplary systems of ink-jet printing.
The drop-on-demand system is a system in which ink is ejected as needed, and ink-jet printers of this system have been used as printers for personal computers, etc. The continuous system is a system in which continuously ejected ink particles are charged in accordance with electric signals, and only needed ink particles are ejected on paper. The continuous system is superior in high-speed printing.
In common ink for an ink-jet printer, a coloring agent, which absorbs a part of visible light and generates reflected light (which has reflected light) under visible light, is contained at a concentration at which the color of print is visible to the naked eye. On the other hand, fluorescent ink containing a fluorescent compound, which has no absorption in the visible light range and which emits fluorescence (emits light in the visible light range) by ultraviolet irradiation, is disclosed in Japanese Unexamined Patent Application Publication No. 58-49765 and Japanese Unexamined Patent Application Publication No. 11-152436.
In Japanese Unexamined Patent Application Publication No. 58-49765, an ink for ink-jet printer containing a fluorescent compound, which has absorption in the visible light range and which emits fluorescence by ultraviolet irradiation at a concentration at which a recording concentration on recording paper becomes 0.1 or less on an optical density basis (that is, a content at which the color of print is not visible to the naked eye under visible light), is disclosed.
When each of the ink described in these publications and common ink for ink-jet printer are respectively ejected from a plurality of nozzles of an ink-jet head, for example, letters that are to be shown to a person, and letters which emit fluorescence by ultraviolet irradiation, can be printed at the same time with ease. That is, the print part is visually identified under the visible light, for example, sunlight, fluorescent light, and incandescent lamp, and under the light source having a predetermined spectral energy distribution with different hue, lightness, and chroma.
However, since the florescent ink disclosed in Japanese Unexamined Patent Application Publication No. 11-152436 is for an ink-jet printer of the continuous system, when this ink is used for an ink-jet printer of the drop-on-demand system, printing reliability may be reduced because of a difference in the print system.
Herein, the fluorescent ink used for the ink-jet printer, in which the printing system is the drop-on-demand system, is required to have the following characteristics.
(1) High quality images are produced on plain paper.
(2) The ink is promptly fixed and, therefore, high-speed printing can be performed.
(3) Nozzles are not clogged, and stable ejection can be performed, wherein skew in ejection (this refers to that the ink is not ejected in the precisely downward direction, but is ejected in the slanting direction) and dot dropout do not occur.
(4) The hue, lightness, and chroma of the print part are significantly changed by irradiation of light source.
In the related art, in order to address (2) above, many sorts of ink have been suggested, wherein an organic solvent or surfactant (referred to as “penetrant”) is added in the ink. Among them, in the related art, when an acetylene glycol (acetylenediol)-based surfactant is used, prints with no blur can be produced by deep permeation of the ink in the direction of the thickness of paper, while the printing speed is ensured. Japanese Unexamined Patent Application Publication No. 4-359071 discloses this feature.
In order to address (4) above, significantly changing the hue of the print part, the ink containing a plurality of fluorescent compounds which are substantially transparent with respect to visible light, and which emit fluorescence by irradiation of ultraviolet lights having different wavelengths has been known. Japanese Unexamined Patent Application Publication No. 10-251570 discloses this feature. However, in this method, a specific apparatus capable of irradiating a plurality of ultraviolet lights is required for the detection.
In order to address (4) above, significantly changing the lightness and chroma of the print part, for example, an ink composition using transparent fine solid particles having a particle diameter of 1 &mgr;m or less is disclosed in Japanese Unexamined Patent Application Publication No. 9-78022. This publication discloses that when fine particles are added, the fine particles are fixed on the surface of the paper, a fluorescent dye is adsorbed thereon and, therefore, the concentration of the fluorescent dye is increased, and the emission intensity during ultraviolet irradiation is increased. Consequently, it is believed that in this case, when the acetylenediol-based surfactant is used for the purpose of (2) above, the fluorescent compound in the fluorescent ink deeply permeates into the paper and, therefore, adequate fluorescence emission intensity is not achieved.
As described above, regarding the ink containing the fluorescent compound for an ink-jet printer of the drop-on-demand system, products capable of satisfying all points of quick-drying property of the ink after printing, print quality, and change in the hue, lightness, and chroma of the print part by irradiation of light source have been required, and, therefore, the ink disclosed in each of the aforementioned publications is susceptible to further enhancement.
SUMMARY OF THE INVENTION
Accordingly, it is a first object of the present invention to provide an ink for an ink-jet printer containing a fluorescent compound which has no absorption in the visible light range and which emits fluorescence by ultraviolet irradiation, a surfactant, and water, such that the ink can satisfy all points of quick-drying property of the ink after printing, print quality, and change in the hue, lightness, and chroma of the print part by irradiation of light source.
It is a second object of the present invention to provide an ink for an ink-jet printer containing a fluorescent compound which has absorption in the visible light range and which emits fluorescence by ultraviolet irradiation, a surfactant, and water, such that the ink can satisfy all points of quick-drying property of the ink after printing, print quality, and change in the hue, lightness, and saturation of the print part by irradiation of light source.
In order to address the aforementioned problems, the present invention provides an ink for an ink-jet printer containing a fluorescent compound which has no absorption in the visible light range and which emits fluorescence by ultraviolet irradiation, a surfactant, and water. The ink for an ink-jet printer is provided such in that the surfactant is an acetylenediol (acetylene glycol)-based surfactant represented by the following Chemical formula (1) and formed of a mixture of a first compound and a second compound where R is an isobutyl group (—CH
2
CH(CH
3
)CH
3
) and where R is an ethyl group (—CH
2
CH
3
), respectively, and where when the content of the first compound in the ink is indicated by A (% by weight) and the content of the second compound is indicated by B (% by weight), A and B are more than “0”, and the relationship between A and B is configured to satisfy the following mathematical expression 5.0≦16A+B≦6.5. This is referred to as “the fi
Hano Yoshifumi
Nakazawa Chiyoshige
Faison Veronica F.
Klemanski Helene
Oliff & Berridg,e PLC
Seiko Epson Corporation
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