Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1998-10-26
2002-10-29
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031520, C106S031650, C106S031750, C106S031860, C106S476000
Reexamination Certificate
active
06471757
ABSTRACT:
This application is based on Patent Application Nos. 312869/1997 filed on Oct. 30, 1997 in Japan, 361461/1997 filed on Dec. 26, 1997 in Japan and 361462/1997 filed on Dec. 26, 1997 in Japan, the content of which is incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to an ink, especially an ink used in the process of ink jet printing and to an ink jet printing method. The present invention also relates to an ink container, an ink set, and an ink jet printing apparatus. The present invention can be applied to all of the devices such as printers, facsimile machines, and copying machines, which are able to print on various kinds of printing mediums such as paper, fabric, leather, non-woven fabric, and plastic sheets (e.g., OHP sheet).
2. Description of the Related Art
An ink jet printing method has been used in a broad range of printers, copying machines, and so on because of its various advantages including: low noise generation, low running cost, high-speed printing, size reduction, and output in multiple colors. Each of such printing and copying machines makes a choice among different types of inks generally in terms of: ink-discharging properties, printing properties including fixation of ink, bleeding and reflection density of print image, and print qualities including color development.
By the way, it is well known that those inks can be broadly divided into two groups, i.e., dye inks and pigment inks in terms of coloring materials contained in the respective inks. The pigment inks are superior to the dye inks in water resistance, light stability, and ability to provide excellent character qualities such as sharp outline of characters.
One of the examples of pigment inks that contain a pigment dispersant (hereinafter, referred as a dispersant-containing pigment ink) is disclosed in, for example, Japanese Patent Application Laid-open Nos. 179183/1993 and 53841/1995. The former discloses a pigment ink in which a pigment is dispersed by a block polymer of “AB” or “BAB” type, and the latter discloses another pigment ink in which a pigment is dispersed by a tri-block polymer of “ABC” type.
Furthermore, a self-dispersing type pigment ink (hereinafter, referred as a dispersant-less pigment ink) which does not need to use any dispersants such as the block polymer described above to disperse the pigment is also known. For example, International patent application Nos. WO96/18695 and WO96/18696, disclose pigment inks in which carbon blacks to whose surfaces hydrophilic groups are directly bound, are dispersed.
In case of applying either types of the pigment inks, i.e. the dispersant-containing pigment ink and the dispersant-less pigment ink, onto a printing medium, pigments in the ink are agglomerated on a surface of the printing medium, and form an image dot. Thus, the coloring material, i.e. pigments, are put on the surface of the printing medium. That is to say, almost all the coloring materials in the ink tend to remained on the surface of the printing medium. Hereinafter, ink providing this kind of image dot, is called “top-loading type” ink.
On the other hand, in order to improve the printed image's color characteristics, the present inventors made an invention in which so called super-penetration type ink, i.e. an ink which penetrates into the inside of a printing medium extremely well, is employed. In the invention, the super-penetration type ink's penetration into the printing medium in its thickness direction is accelerated and the super-penetration type ink is allowed to spread in the printing medium (see European Patent Application No. EP 583096 A, or Japanese Patent Application Laid-open No. 88048/1994).
BACKGROUND OF THE INVENTION
In view of the aforementioned prior art, the present inventors focused on the dot shape including the dot density's uniformity, the outer shape of the dot, and the diameter of the dot etc., and have obtained the following findings.
FIGS. 7A
to
7
G are schematic plain views of image dots obtained by applying various types of inks to the same printing medium under same conditions.
FIG. 7A
is an image dot having a diameter of RA formed with a dispersant containing ink, and
FIG. 7B
is an image dot having a diameter of RB formed with a dispersant-less ink. The diameter RB was slightly larger than RA. Each of the image dots had unified density throughout the respective image dots. Further, substantial feathering could not be seen in both the image dots, thus any problems could not be found in the outer shapes of the respective dots. Regarding the image dot's diameter, however, the inventors found the fact that the respective image dots'diameters were slightly smaller than those expected from a shape of respective ink droplets. The reason is believed to be that the image formation by the pigment ink owes to pigments' agglomeration on the printing medium. To sum up, the pigment ink provides an image dot whose density is unified and has a good outer shape, but the ink droplet seems not to be spread easily on the printing medium. Therefore, regarding ink jet recording process with the pigment ink, the present inventors recognized that the known pigment ink should be modified in order to form an image dot having larger area-factor, i.e. a ratio of an area covered with an image dot to the unit area.
Based on the aforementioned recognition, the inventors modified the conventional pigment inks so as to have better penetration by utilizing the technology of the super-penetration type ink. As a result of the experiment, a change in pigments agglomeration could be observed, and the outer shape of an image dot was changed. As shown in
FIGS. 7C and 7D
, the diameter of RC and RD of the respective image dots became larger than the diameter of RA and RB. That is, the relation between RA, RB, RC and RD are as follows: RA<RB<RC<RD.
As shown in
FIG. 7C
, however, a modified dispersant-containing pigment ink whose penetrability was better than that of the conventional dispersant-containing pigment ink, provided an image dot having feathering
701
extending from the center of the image dot towards the outside thereof. In addition, a modified dispersant-less pigment ink having better penetrability than that of the conventional dispersant-less pigment ink, provided an image dot having a circumferential area (hazy area)
703
around the core area
704
in addition to feathering
701
. In the circumferential area
703
, fine particles of the pigment in the ink were diffused and the density of the circumferential area
703
became lower than that in the core area
704
. That is, the density in the image dot was apparently different in its circumferential area
703
and its core area
704
.
In accordance with the findings shown in
FIGS. 7C and 7D
, the present inventors conducted a further experiment regarding image dots formed with two types of further modified pigment inks, one of which was a dispersant-containing pigment ink containing a dye and having better penetrability than that of the conventional dispersant-containing ink, and the other was a dispersant-less pigment ink containing a dye and having better penetrability than that of the conventional dispersant-less pigment ink. The resultant image dots with the respective further modified pigment inks are shown in
FIGS. 7E and 7F
. The respective image dots have diameters of RE and RF both of which were much larger than RA−RD, and RF is larger than RE. As shown in
FIG. 7E
, however, the ink dot had a circumferential area
705
around a core area
706
, the circumferential area
705
having lower density than that of the core area
706
, which was not observed in the image dot shown in FIG.
7
C. The circumferential area
705
seems to be made due to separation of the dye and the pigment on the printing medium, and the separated dye's diffusion, and the core area seems to contain agglomerated pigment. Thus, the difference in density in the image dot became conspicuous.
Furthermore, as shown in
FIG. 7F
, the ink dot h
Eguchi Takeo
Koitabashi Noribumi
Kurabayashi Yutaka
Takizawa Yoshihisa
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Klemanski Helene
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