Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-02-04
2004-07-27
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000, C347S095000
Reexamination Certificate
active
06767090
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink set for use in an ink jet recording method and specifically to an ink set for ink jet recording which can produce high-quality printed images on recording media such as ink jet recording exclusive papers, etc., for example, plain papers, coated papers, glazed papers, etc., and which is excellent in the storage stability. More particularly, the invention relates to (1) an ink jet recording ink set, wherein each ink comprises at least a colorant enclosing a pigment and/or a dye with a polymer, and the ink set comprises a combination of black, yellow, magenta and cyan, or a combination further combined with orange and green, and relates to (2) an ink jet recording ink set, wherein each ink comprises at least a colorant enclosing a pigment and/or a dye with a polymer, and the ink set comprises a combination of black ink, yellow ink, magenta ink and cyan ink, each ink comprising at least one kind of ink having a different concentration.
BACKGROUND ART
Ink jet recording is a method of recording letters or figures on the surface of a recording medium by ejecting an ink from a fine nozzle as droplets. As an ink jet recording system, a method wherein electric signals are converted to mechanical signals using an electrostrictive element and an ink reserved in a nozzle head section is intermittently ejected to record letters or symbols on the surface of a recording medium; and a method wherein a part of an ink reserved in a nozzle head section and very closing to the ejecting portion is rapidly heated to generate bubbles, whereby the ink is intermittently ejected by the volume expansion caused by the bubbles to record letters or symbols on the surface of a recording medium, etc., have been practically used.
The inks used for such an ink jet recording have been required to have various characteristics. For example, the characteristics such as (a) the ink does not cause bleeding upon printing on paper, which is a recording medium, (b) the ink has a good drying property, (c) the ink can be uniformly printed on the surfaces of various recording media, (d) in multi-color printing, e.g., color printing, etc., adjacent colors are not mingled, (e) the keeping quality of color images is good, etc., have been required.
For the required characteristics such as the above-described (a) to (e), dye inks and pigment inks have been investigated as inks. Since the inks using dyes are excellent in the color developing property but are inferior in the light resistance and the water resistance, pigment inks have, recently, been investigated.
In many inks using pigments, it has been investigated to restrain wetting of the surface of paper with ink by mainly restraining the permeability of ink and to ensure the printing quality by staying the ink droplets near the surface of paper, and such a technique has been put into practical use.
However, with the ink that restrains wetting to paper, there are problems that the difference in the degree of bleeding depending on the kind of paper is large and, upon printing of a multi-color system such as a color printing, adjacent colors are intermingled and further there is a problem that the scrubbing resistance becomes inferior.
For solving these problems, it has been attempted to add a penetrating agent for improving the permeability of ink to paper. For example, examples of using glycol ethers are disclosed. Specifically, Japanese Patent Laid-Open No. 147861/1981 discloses an example of using triethylene glycol monomethyl ether, and Japanese Patent Laid-Open No. 111165/1997, examples of using an ether such as ethylene glycol, diethylene glycol or triethylene glycol are disclosed. Also, U.S. Pat. No. 5,156,675 proposes the addition of diethylene glycol monobutyl ether, U.S. Pat. No. 5,183,502 proposes the addition of Surfynol 465 (manufactured by Air Products and Chemicals Inc.), which is an acetylene glycol-based surface active agent, and U.S. Pat. No. 5,196,056 proposes the use of diethylene glycol monobutyl ether and Surfynol 465 together. Moreover, U.S. Pat. No. 2,083,372 proposes to use ethers of diethylene glycol for inks.
Also, in the inks using conventional pigments, it has generally been carried out to disperse the pigment in an aqueous medium using a dispersing agent such as a surface active agent, a polymeric dispersing agent, etc. However, there is a problem that it is not easy to improve “the permeability of the ink” while ensuring the dispersion stability of the pigment.
Also, in the pigment ink wherein “a pigment dispersion having a dispersed pigment” is prepared using a dispersing agent such as a surface active agent, a polymeric dispersing agent, etc., and the permeability thereof is improved by using the pigment dispersion, since the dispersing agent is simply adsorbed to the surface of the pigment, it sometimes happens that when a strong shearing force is applied in the case of ejecting the ink through a fine nozzle, the dispersing agent adsorbed is released to reduce the dispersibility, whereby “a tendency that the ejection becomes unstable” occurs. Also, in the case of storing the pigment ink for a long period of time, the tendency that the ejection becomes unstable sometimes happens.
As the means for solving these problems, a method of increasing the addition amount of the dispersing agent may be considered but in this case, since the amount of the dispersing agent, which is dissolved in the ink without being adsorbed to the surfaces of the pigments, in the case of printing on a plain paper or a recycled paper using the ink, the phenomena that bleeding is liable to occur, the periphery of a nozzle is wetted with the ink and the ejection is liable to become unstable, etc., tend to occur.
Furthermore, in the case of printing on a plain paper, a recycled paper, etc., with the above-described pigment ink (the pigment ink wherein “a pigment dispersion having a dispersed pigment” is prepared using a dispersing agent such as a surface active agent, a polymeric dispersing agent, etc., and the permeability thereof is improved by using the pigment dispersion), there is a tendency that the pigment which is a coloring component is hard to remain on the surfaces of the paper fibers of the surface of the recording medium, whereby there are tendencies that a good printed density is not obtained and the color development is not good. Also, since there is a tendency of increasing the viscosity of the ink by the dispersing agent dissolved in the liquid without being adsorbed on the surface of the pigment from the initial stage and the dispersing agent released from the pigments, the content of the pigment is frequently limited, thereby particularly with a plain paper and a recycled paper, a sufficient printed density cannot be obtained. Accordingly, good color development cannot be obtained and it is difficult to obtain printed images of a high quality. Furthermore, when the ink is stored for a long period of time in the state of filling in a nozzle head, it sometime happens that the dispersion stability is deteriorated and the ink is hard to be ejected from the nozzle of the printer.
On the other hand, as the means of attaining the purposes of enhancing the ejection stability, the dispersion stability, the printing density, the color developing property, etc., an ink using a pigment wherein the surface is subjected to some treatment has been proposed.
As the ink using the pigment subjected to some treatment, there are proposed, for example, “the ink having pigment particles surfaces of which are subjected to an oxidation treatment” described in Japanese Patent Laid-Open No. 319444/1996, “the ink having the encapsulated fine pigment particles” described in Japanese Patent Publication No. 94634/1995 and Japanese Patent Laid-Open No. 59715/1996, and “the ink having the pigment particles surfaces of which are graft polymerized with a polymer” described in Japanese Patent Laid-Open Nos. 339516/1993, 302227/1996, 302228/1996 and 81647/1996, but the above-described purposes have not yet been sufficiently attained.
Hayashi Hiroko
Miyabayashi Toshiyuki
Yatake Masahiro
Ladas & Parry
Meier Stephen D.
Seiko Epson Corporation
Shah Manish
LandOfFree
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