Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2003-05-05
2004-11-02
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S100000, C106S031130
Reexamination Certificate
active
06811251
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is an image recording apparatus and a recording method based on a color ink-jet scheme and an ink set, and relates to a color image recording method; more specifically, an image recording method based on a color ink-jet scheme, and an ink set for use in the ink-jet recording which can achieve the reproduction of brilliant colors with scarce color bleed and is low in blurring, when an image to be recorded is recorded on a sheet of a plain paper.
DESCRIPTION OF THE RELATED ART
In the recent ink-jet recording techniques, with the development of the manufacturing methods of the heads having a highly-integrated and high-precision nozzle, it has become possible to make high speed printing of high resolution images by discharging fine ink droplets. Particularly, with a medium provided with an ink accepting layer on the surface thereof as a quality paper special for ink-jet printing, it is possible to record an image as high in quality as a silver salt photograph. However, even with the recent techniques of ink-jet recording, the images recorded on the plain papers tend to be degraded in quality; there has not been solved the problem that on a plain paper, the color blurring and color mixing (bleeding) occur conspicuously in the boundaries between the adjacent ink dots.
Japanese Patent Laid-Open No. 6-92008 proposes the use of an ink which is 40° or smaller in the contact angle at the elapsed time of 5 seconds after dropping on a paper subjected to sizing, and contains at least acetyleneglycol; however, in the actual ink-jet recording, the ink droplet is dried very fast, so the validity of the property specification made solely on the basis of the contact angle measured at the elapsed time of 5 seconds after dropping is questionable.
Japanese Patent Laid-Open No. 10-330666 proposes an ink in which for a recording medium with a sizing degree of 10 seconds or longer, the advanced contact angle is 40° to 70° at the wetting time of 0.2 second or shorter as measured by Bristow's method; however, the wetting time based on Bristow's method refers to the irregularity of the paper surface, and hence to a macroscopic measure of the penetration of ink, so that it is different from the penetration of the ultra-fine ink droplets in the contemporary ink-jet recording, and accordingly the relation between the ink blurring and the high speed printing remains still unclear.
Japanese Patent Laid-Open No. 2000-144028 proposes a pigment ink in which the time variation of the dynamic contact angle on a plain paper is 0.5 to 3.5°/second; however, the ink cannot avoid the color mixing because the penetration of the ink is considerably slow.
As described above, there are proposed a variety of inks and methods for use in the ink-jet recording and for the purpose of suppressing the blurring and color mixing of inks, but the suppression of the blurring and color mixing on plain papers is not sufficiently satisfactory, so that the images become as a whole fuzzy when printed, and no fine images can be obtained. The state of affairs is that the recent ink-jet recording seeks for a higher quality and high speed recording, and a technique capable of the finer suppression of the blurring and color mixing is required, but it is still the case that there has not yet been developed an ink and a method which can meet these requirements.
SUMMARY OF THE INVENTION
Accordingly, the present invention takes as its object the provision of an image recording apparatus and a recording method based on a color ink-jet scheme and an ink set which can achieve the reproduction of brilliant colors with scarce color bleed and is low in blurring even in a high speed recording on plain papers when the ink set is used as the inks for use in the ink-jet recording.
As a result of diligent study for the purpose of overcoming the above described problems, the present inventors have come to perfect the present invention, by discovering that there can be obtained an ink set for use in the ink-jet recording which can achieve the reproduction of brilliant colors with scarce color bleed and is low in blurring, by regulating the dynamic contact angle variations and the dot radius variation rates of the ink A and ink B, where printing is performed first with ink A and subsequently with ink B.
More specifically, the present invention is an image recording apparatus based on a color ink-jet scheme provided with an ink set consisting of one or more than one colors of inks containing a color dye and water as the indispensable components and a black ink containing a black pigment and water as the indispensable components, and an ink-jet printing unit which makes printing with these inks on such plain papers as having a degree of flatness and smoothness of 100 seconds or less, wherein the initial contact angles &thgr;
0
of the two colors of inks, namely, at least one color ink and the black ink of the above described ink set, fall within the range from 30 to 80° on a plain paper having a degree of flatness and smoothness of 100 seconds or less; as for one of the two colors of inks, the ink A, and the other ink, the ink B, the contact angle variation Xa of the ink A as obtained by the dynamic liquid absorption measurement after the elapsed time of 1 second falls within the range −70<Xa<−10(°), the dot area ratio Ya of the ink A after the elapsed time of ta seconds falls in the range 1.5<Ya, the contact angle variation Xb of the ink B as obtained by the dynamic liquid absorption measurement after the elapsed time of 1 second falls within the range −10<Xb<0(°), and the dot area ratio Yb of the ink B after the elapsed time of tb seconds falls within the range 1.0<Yb<1.5; and the ink-jet printing unit makes printing first with the ink A and subsequently with the ink B. Here, the contact angle variation X=&thgr;−&thgr;
0
, the dot area ratio Y=r
t
2
/r
0
2
, 0.1<ta≦5 (seconds), 0<tb≦10 (seconds), &thgr; denotes the dynamic contact angle of the ink A or the ink B after the elapsed time of 1 second from the printing, and r
0
and r
t
denote respectively the radii of the dots at the time of printing with the ink A or the ink B and after the elapsed time of ta or tb seconds therefrom. Incidentally, the liquid droplet volume in the dynamic liquid absorption measurement is 2 &mgr;L.
Additionally, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, the black pigment in the black ink is a self-dispersing pigment.
Besides, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, at least one color of ink contains at least any one of a polyol or a polyol ether.
Furthermore, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein the above described polyol or polyol ether is selected from the group consisting of ethyleneglycol monoalkyl ethers, diethyleneglycol monoalkyl ethers, triethyleneglycol monoalkyl ethers, propyleneglycol monoalkyl ethers, dipropyleneglycol monoalkyl ethers, and alkoxy substituted aliphatic alcohol.
Additionally, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, at least one color of ink contains a glycol based or an acetylenegylcol based surfactant.
Besides, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, the surface tension of at least one color of ink falls within the range from 20 to 70 mN/m.
Furthermore, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, the viscosity of at least one color of ink falls within the range from 1 to 20 mPa.S.
Additionally, the present invention is an image recording apparatus based on a color ink-jet scheme, wherein in the above described ink set, at least one color of ink c
Fujii Ichiro
Kamoto Takanori
Kinomoto Masanori
Morimoto Kiyofumi
Nakatsu Hiromi
Meier Stephen D.
Nixon & Vanderhye P.C.
Sharp Kabushiki Kaisha
Tran Ly T
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