Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-08-31
2003-12-16
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C106S031130
Reexamination Certificate
active
06663237
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording method, a recording unit, an ink jet recording apparatus and the like.
2. Related Background Art
Conventionally, ink for writing implements (fountain pens, nylon-tip pens, water ball-point pens, etc.) and ink for ink jet, which use carbon black high in print density and excellent in solidness or the like as a black coloring agent for printing ink, have been reported in various compositions. Among them, in recent years, detailed research and development have been carried out on compositions and physical properties of carbon blacks themselves, compositions and physical properties of ink containing the carbon black, and the like such that recording can be made satisfactorily on plain paper such as copy paper, reporting paper, notebook paper, writing paper, bond paper and continuous slip paper that are generally used in offices.
For example, ink that uses acid carbon black and alkaline soluble polymer is described in Japanese Patent Application Laid-open No. 3-210373. In addition, ink for ink jet with which dispersion excellent in preservation stability and dischargeability in a bubble jet recording apparatus tends to be realized is described in Japanese Patent Application Laid-open No. 3-134073.
In addition, Japanese Patent Application Laid-open No. 8-3498 presents technical problems such that ink containing a dispersing agent together with carbon black is unstable in discharge as ink for ink jet and cannot realize a sufficient print density, and discloses ink using self-dispersing carbon blacks that can disperse in a solvent without using a dispersing agent as ink capable of solving the problems. International Patent Publication No. 96/18695 (Japanese Patent Application Laid-open No. 10-510862) and U.S. Pat. No. 5,746,818 (Japanese Patent Application Laid-open No. 10-95941) also disclose ink for ink jet containing self-dispersing carbon blacks and describe that high quality images can be obtained using the ink.
Moreover, in European Patent Publication No. EP943666, inventors of the present invention disclose technical means for adding salt to ink in addition to the above-mentioned self-dispersing carbon blacks for the purposes of improving paper type dependency of an image density, reducing bleeding in a boundary between black and color, and the like in using the above-mentioned self-dispersing carbon black as ink for ink jet.
Incidentally, concerning conventional pigment ink, it is known that discharge stability may be lost. More specifically, for example, when ink is discharged from a predetermined nozzle of an ink jet recording head and then the ink is discharged again from the nozzle after the discharge of the ink from the nozzle is stopped for a certain length of time (e.g., 12 hours), the re-discharge of the ink may not be stable, whereby printing is collapsed (operations for discharging ink from a predetermined nozzle and discharging the ink again from the nozzle after stopping the discharge of the ink from the nozzle for a predetermined length of time is hereinafter referred to as “intermittent discharge of ink” and a state in which re-discharge of ink is unstable is hereinafter referred to as “poor in intermittent dischargeability”).
In addition, when ink is discharged again from a nozzle after discharge of the ink from the nozzle is stopped for a long time of period (e.g., a few days or more), a recovery operation for removing ink having increased viscosity or solidified in the nozzle may be required (a state in which re-discharge of ink is unstable due to increase in viscosity or solidification of ink in a nozzle is hereinafter referred to as “locking of ink” and a state in which a recovery operation is required many times for realizing stable re-discharge is hereinafter referred to as “poor in retentivity”).
As described above, properties required of black ink for ink jet need to be extremely sophisticated in accordance with the need for images recorded by ink jet to be very high in quality in recent years. However, concerning pigment ink containing the above-mentioned self-dispersing carbon black as a coloring material, it cannot be said that technical knowledge for giving a high OD and a sharp edge and attaining excellent ink jet discharge properties such as intermittent dischargeability and retentivity is sufficiently attained. Thus, some of the characteristics of such pigment ink as ink for ink jet recording are unclear.
On the other hand, various improvements have been made on a configuration of an ink jet recording head. A configuration in which a movable member for regulating a flow of liquid (ink) and a growing direction of a bubble is provided in a bubble generation area in a liquid flow path is disclosed, for example, in Japanese Patent Application Laid-open Nos. 2000-62180, 2000-62181 and 2000-62182.
For example, the above-mentioned ink containing self-dispersing carbon blacks and salt disclosed by the inventors of the present invention is extremely effective for reducing paper type dependency of an image density and reducing bleeding in a boundary area between black and color in an image, which is an initial object. However, as a result of further study aiming at establishing a more excellent ink jet recording technology by the inventors of the present invention, large fluctuations are sometimes found in the intermittent dischargeability and the retentivity of the ink depending on a structure of a recording head used.
On the other hand, in an ink jet recording head having the configuration in which a movable member is provided in a liquid flow path, a changing rate of a changing point from growth to contraction of a bubble in the liquid flow path is stabilized and quick separation of liquid being ejected is satisfactory and stabilized, whereby the printing grade can be improved. However, with ink using self-dispersing pigment, the pigment is deposited on such a movable member due to agitation or the like of liquid by the movement of the movable member, and the initial stability in the movement of the movable member cannot be secured as the amount of deposition increases, whereby dischargeability may be changed.
SUMMARY OF THE INVENTION
Now that a structure of a recording head is expected to be diversified in accordance with wide product development of ink jet printers and expansion of areas in which ink jet recording technology is to be applied in the future, it has been recognized that development is required for ink showing a satisfactory and stable ink jet property with respect to the diversification of recording heads while making use of excellent properties of ink containing self-dispersing carbon blacks.
The present invention has been devised in view of the above-mentioned drawbacks, and it is an object of the present invention to provide an ink jet recording method, a recording unit and an ink jet recording apparatus that have excellent properties as regards the intermittent dischargeability and the retentivity of ink.
In addition, it is another object of the present invention to provide an ink jet recording method, a recording unit, an ink jet recording apparatus and the like that can steadily obtain high quality prints.
An ink jet recording method in accordance with the present invention is an ink jet recording method having steps of giving energy to ink, discharging the ink from a recording head and depositing the ink on a recording medium, which is characterized in that;
the ink is ink containing a coloring material including at least self-dispersing carbon blacks, which are formed of at least one hydrophilic group bonded to a surface of a carbon black directly or via another atom group, and an aqueous medium and further having potassium ions of 0.6% or more in a mass ratio with respect to the carbon blacks; and
the recording head includes a structural unit for discharging liquid droplets having a heating element for generating thermal energy for generating a bubble in liquid; a discharge port that is a portion for discharging the liquid
Ishinaga Hiroyuki
Mishina Shinya
Brooke Michael S
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Meier Stephen D.
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