Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-03-25
2001-03-20
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031270, C106S031430
Reexamination Certificate
active
06203604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink for ink-jet recording, a color filter of a liquid crystal color display device used in color televisions, personal computers and the like, a process for producing the color filter, and a liquid crystal panel employing the color filter.
2. Related Background Art
A color filter is one of the important parts of a liquid crystal color display device. This filter is so constituted that many pixels of three primary colors of red (R), green (G) and blue (B) are arranged repeatedly. With development of personal computers, especially portable personal computers, liquid crystal display devices, in particular liquid crystal color display devices, are increasingly in demand. For further popularization thereof, it is demanded that a cost of the liquid crystal display device, especially the relatively high cost of the color filter, should be reduced. For reducing the cost of the color filter with the required quality retained, various color filter production processes have been investigated. Typical production processes of color filters are explained below.
A first process employed most widely is a dyeing process. In this process, a water-soluble polymer for dyeing is sensitized by addition of a photosensitive material, the sensitized polymer is patterned by photolithography in a desired shape on a transparent base plate, and the obtained pattern is dyed in a dyeing bath to obtain a colored pattern. This operation is repeated three times to produce an RGB color filter.
A second process employed relatively widely is a pigment dispersion process. This process is replacing the above dyeing process. In this process, a photosensitive resin layer containing a pigment dispersed therein is formed on a base plate, and the resin layer is patterned to obtain a pattern for one color. This operation is repeated three times to form an RGB color filter.
A third process is an electrodeposition process. In this process, a transparent electrode is patterned on a base plate, and the patterned base plate is immersed in a electrodeposition solution containing a pigment, a resin, an electrolyte and so forth to deposit a first color. This operation is repeated three times to form RGB color layers and then the colored layers are calcined, thereby forming a color filter.
A fourth process is a printing process. In this process, paints containing a pigment and a thermosetting resin are applied onto a base plate for each of the three colors of R, G and B, and the colored resin layer is cured by heating to form an RGB color filter.
The above processes, however, have many unsolved problems, as described below. For example, in any of the above processes, a protection layer is generally formed on the colored layer. And what is common to these processes is that it is necessary to repeat the same operation three times for formation of R, G and B, which inevitably increases the production cost. The larger the number of steps, the lower the yield, disadvantageously. Further, the third process is not applicable to a TFT color display device owing to the limited formable pattern with the present technical level. The fourth process has the drawbacks of low resolution and poor smoothness, and thus is not suitable for fine-pitch pattern.
To offset these disadvantages, ink-jet systems are proposed for producing a color filter (see Japanese Patent Application Laid-Open Nos. 59-75205, 63-235901, 1-217302, 4-123005, etc.). In these systems, coloring liquids (hereinafter referred to as an “ink”) containing respectively a dyestuff of red (R), green (G) or blue (B) are ejected through a nozzle onto a filter base plate, and the deposited inks are dried to form pixels, thereby forming a color filter. By this system, the colored layers of R, G and B can be formed in one step, and the inks can be deposited selectively on pixel formation portions without waste of inks, so that productivity can be improved and production cost can be reduced.
The ink for color filter production by the ink-jet system desirably satisfies at a higher level the requirements for the characteristics shown below:
(a) high transparency of the pixels (colored portions) of the color filter,
(b) less areal spreading of the pixels with lapse of time (hereinafter referred to as “bleeding”),
(c) high adhesiveness of the pixels,
(d) high light-fastness of the pixels of the color filter, and
(e) high ejection stability in ink-jet recording system.
The production of a color filter by an ink-jet system is greatly different from conventional color filter production processes, for example as shown in
FIGS. 3A
to
3
E, in that an ink
24
containing a dye in a high concentration is applied selectively onto pixel portions on a base plate
1
(
FIG. 3A
) and a solvent or the dispersing medium (water, an organic solvent, etc.) is evaporated to form pixels (FIG.
3
C).
FIG. 3B
shows a state where the ink
24
is just applied and
FIG. 3D
shows a state where a pixel is normally formed. However, as shown in
FIG. 3E
, it has been found by the inventors of the present invention that the dyestuff may crystallize out from the ink
24
applied on the base plate during drying to lower the transparency of the formed pixels, or may cause bleeding of the pixels by migration of the pixel-forming dye with lapse of time owing to incomplete evaporation of the solvent. The remaining residual solvent in the pixels may lower the adhesiveness to the base plate by an interaction with the base plate, or may impair light-fastness owing to influence of active oxygen formed by thermal decomposition. Therefore, it is preferable that the ink for color filter formation preferably should satisfy the above requirements (a) to (d) at a high level. Further, it is needless to say that the ink for an ink-jet system should be ejected stably. The inventors of the present invention have investigated inks having the above characteristics. Consequently, it has been found that an ink comprising a metal complex azopyrazolone dye and a dye having a xanthene-skeleton satisfies the requirements for characteristics (a) to (e) mentioned above at a higher level as an ink-jet ink for formation of a red pixel in a color filter.
SUMMARY OF THE INVENTION
The present invention has been accomplished on the basis of the above findings.
An object of the present invention is to provide an ink satisfying the above characteristics (a) to (e) at a higher level.
Another object of the present invention is to provide a color filter having red color filter portions having high transparency, causing very little bleeding, and having excellent adhesiveness.
Still another object of the present invention is to provide a process for producing a color filter which has red filter portions having high transparency, causing less bleeding, and having high adhesiveness, at a low production cost.
A further object of the present invention is to provide a liquid crystal panel of high quality.
A still further object of the present invention is to provide a computer having an image display device of high quality.
A still further object of the present invention is to provide a process for producing a color filter which has highly transparent red filter portions, causing less bleeding, and having high adhesiveness.
The above objects can be achieved by the present invention described below.
According to a first aspect of the present invention, there is provided an ink comprising a metal complex azopyrazolone dye and a xanthene dye (a dye having a xanthene skeleton).
According to another aspect of the present invention, there is further provided a color filter comprising a light transmissive base plate and a red color pixel at prescribed positions on the base plate, wherein the colored pixel comprises a metal complex azopyrazolone dye and a xanthene dye.
According to still another aspect of the present invention, there is still further provided a liquid crystal panel comprising a color filter and a panel base plate, in which the color filter has a light transmissive b
Hirose Masashi
Kashiwazaki Akio
Nakazawa Koichiro
Shirota Katsuhiro
Yamashita Yoshihisa
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Klemanski Helene
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