Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2000-02-04
2002-06-04
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000, C347S096000
Reexamination Certificate
active
06398356
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a recording liquid and an image recording method, and more particularly to a recording liquid comprising a colorant, water and fine resin particles, and an image recording method using the same.
BACKGROUND OF THE INVENTION
Recently, attentions have been paid to ink jet systems, i.e., image recording methods in which droplets of recording liquids are discharged from recording heads to record images on recording media, because the running cost thereof is low and this system can be easily applied to color image system for output devices of information instruments such as computers. As recording liquids for ink jet printers, aqueous solutions of dyes which are mainly composed of water and dyes have hitherto been used. However, there is the problem that when recording liquids jetted from nozzles adhere to recording paper, they blurred on the recording paper so that the resulting dot images become extremely larger droplets formed by jetting, or have low image density, to thereby result in low image quality. Further, there is the problem that the images are easily blurred or flow with water, because of low water resistance of the recorded images. Furthermore, there is the problem that the images are easily faded by irradiation of light such as sunlight, because of low light resistance.
As to recording liquids for ink jet printers, techniques have been proposed in which film-forming fine resin particles are added to recording liquids to solve the above described problems of the aqueous solutions of dyes. For example, JP-B-60-32663 (the term “JP-B” as used herein means an “examined Japanese patent publication”) discloses a recording liquid to which a latex is added as the fine resin particles, JP-A-5-239392 (the term “JP-A” as used herein means an “unexamined published Japanese patent application) discloses a recording liquid to which a water-dispersible resin having carboxyl and nonionic hydrophilic groups is added, JP-A-5-255628 discloses a recording liquid to which a vinyl polymer of a non-crosslinked structure, and JP-A-6-340835 discloses a recording liquid to which polyester particles having ionic groups are added. Further, JP-B-7-47355 discloses a technique which comprises adding particles of a resin such as a polyester and a crosslinking agent to a recording liquid, and crosslinking the resin on a recording medium.
However, in all of the recording liquids disclosed in the above described patents, film formation of the fine resin particles is initiated at discharge outlet sections of recording heads as water contained in the recording liquids is evaporated by contacting with air. This results in occurrence of clogging. It has been therefore impossible to stably discharge the recording liquids. Further, according to these recording liquids, it has been impossible to completely prevent the recording liquids from blurring in fibers of recording paper by capillary action, to thereby fail to provide images of high image quality. Furthermore, it has been impossible to completely prevent these recording liquids from penetrating into the inside of the recording paper, which imposes a limitation on the acquisition of images of high density and high image quality. Similarly, there is also a limitation on water resistance. Moreover, the dilution of the above described conventional recording liquids with water for avoiding the clogging at discharge outlets decreases the content of fine resin particles contained in the same volume of droplets, namely the content of resin solids contributing to image formation, as compared to that prior to the dilution, which causes a remarkable reduction in image density. It has been therefore impossible to provide images of high image quality. That is, in the conventional recording liquids, the provision of images having a high image density and high image quality by increasing the content of fine resin particles (the content of resin solids) has been incompatible with the avoidance of the clogging at discharge outlets.
SUMMARY OF THE INVENTION
The present invention has been made for solving the above described problems, and an object of the present invention is to provide a recording liquid which can provide an image having a high image density, exhibiting no blurring on recording paper and no penetration therein, and having excellent water resistance, and which is excellent in discharge stability.
Another object of the present invention is to provide an image recording method using the recording liquid.
Other objects and effects of the present invention will become apparent from the following description.
The above described objects of the present invention has been achieved by providing a recording liquid comprising a colorant, water and at least two kinds of fine resin particles.
In a first preferred embodiment, the recording liquid comprises a colorant, water and at least two kinds of fine resin particles, wherein at least one kind of the at least two kinds of fine resin particles are fine self-crosslinkable resin particles.
In a second preferred embodiment, the recording liquid comprises a colorant, water and at least three kinds of fine resin particles.
The present invention also relates to an image recording method comprising discharging droplets of the above described recording liquid from a recording head to record an image on a recording medium.
DETAILED DESCRIPTION OF THE INVENTION
The reason why the recording liquids as described above allows the attainment of high image density by increasing the content of fine resin particles (the content of resin solids) to be compatible with the avoidance of the clogging at a discharge outlet of a recording head is not fully clarified, but inferred as follows.
The inclusion of at least two different kinds of fine resin particles in the recording liquid decreases the probability that around (at proximate coordinate positions) a certain fine resin particle is present a fine resin particle of the same kind as this fine resin particle. This decreases the probability that the fine resin particles of the same kind come close to and collide with each other, which inhibits a series of processes from the approach of the fine resin particles of the same kind to each other to film formation through their collision and fusion (coordination effect), resulting in prevention of clogging.
Similarly, the inclusion of at least three different kinds of fine resin particles in the recording liquid decreases the probability that around (at proximate coordinate positions) a certain fine resin particle is present a fine resin particle of the same kind as the fine resin particle to one third or less. This decreases the probability that the fine resin particles of the same kind come close to and collide with each other, which inhibits a series of processes from the approach of the fine resin particles of the same kind to each other to film formation through their collision and fusion (coordination effect), resulting in prevention of clogging.
Further, the attraction between particles becomes more difficult to act when different kinds of fine resin particles are present in the recording liquid than when only fine resin particles of the same kind are present (the repulsion becomes easy to act). Accordingly, fine resin particles of the same kind are prevented from coming close to each other, and the probability of their collision is decreased (the effect of repulsion between particles). Similar to the above, therefore, a series of processes from the approach of the fine resin particles of the same kind to each other to film formation through their collision and fusion is inhibited, resulting in prevention of the clogging.
Furthermore, with respect to the prevention of the clogging, it is considered that the differences in particle size and form between the different kinds of fine resin particles are larger than those between the fine resin particles of the same kind. When around a certain fine resin particle is present a different kind of fine resin particle largely different the
Fukuda Yuzuru
Mikami Takeshi
Minabe Jiro
Suwabe Yasufumi
Barlow John
Fuji 'Xerox Co., Ltd.
Oliff & Berridg,e PLC
Shah Manish S.
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