Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-05-29
2004-02-24
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000, C347S095000, C106S031130
Reexamination Certificate
active
06695443
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink for ink jet recording and an ink set for ink jet recording to be used in a recording of information containing characters, images, symbols, and the like, particularly, on plain paper copier (PPC) paper by an ink jet recording apparatus and a method for ink jet recording using the ink for ink jet recording, an ink cartridge for ink jet recording, an ink jet recording apparatus and the recorded article.
2. Description of the Related Art
The ink jet recording is known as an excellent method of recording which do not restrict the types of recording medium being used and research and studies of recording apparatuses, recording techniques, recording material for this method has been actively pursued. However, in practice, in case of ink jet recording apparatuses which have been developed and are now commercially available, when a recording medium which has been uniquely designed for ink jet recording is not used, it is difficult to obtain an image 1) having a good fixation, 2) having a so-called good “sharpness” in characters and free of fogging and blurring (hereinafter referred to as “feathering”), and 3) having a high image density or Optical Density (OD). When recording is performed on a recording medium, for example, paper commonly used in offices and homes such as plain paper copier paper, letter paper, bond paper, post card, writing paper, envelope, report paper, etc. and transparency films (OHP film) by a conventional ink jet recording apparatus, it is impossible to satisfy all of the properties aforementioned at the same time.
If a paper designed uniquely for ink jet recording is used, an image which exhibits aforementioned properties may be achieved. However, in general, the paper designed for ink jet recording is expensive. Also, since the paper is usually a coated paper only on its one side, fixation of ink and printing quality significantly deteriorates when recording is performed on the backside of the paper where no coating is applied. Such problem is one obstacle factor to prevent the ink jet recording apparatus to become widely used.
Therefore, various attempts to achieve the foregoing properties 1) to 3) has been pursued. For example, the following techniques have been disclosed.
(1) Strong alkaline inks exhibiting pH of around 13 as described in Japanese Patent Application Laid Open No.56-57862, Japanese Patent Application Laid Open No.57-102970 and Japanese Patent Application Laid Open No.57-102971.
(2) Method for recording which utilizes an ink ejected in a molten state, in which the molten ink is obtained by heating a solid ink in a form of wax under room temperature (for example, Japanese Patent Application Laid Open No.61-159470, Japanese Patent Application Laid Open No.62-48774 and Japanese Patent Application Laid Open No.56-57862),
(3) Method for recording which utilizes an oil-soluble ink in which a non-water-soluble organic solvent is used as a liquid medium.
Also, the following techniques are disclosed to achieve excellent fixation of the aforementioned property 1).
(4) An ink containing a large amount of surfactant, as described in Japanese Patent Application Laid Open No.55-29546.
(5) An ink comprising a combination of glycerin, N-methyl-2-pyrrolidone, a direct dye and a surfactant having a low surface tension less than cmc, as described in Japanese Patent Application Laid Open No.56-49771.
(6) Inks having a high pH and containing a fluoride surfactant, as described in Japanese Patent Application Laid Open No.56-57862 and Japanese Patent Application Laid Open No.57-102971.
The ink as aforementioned in (1) is very hazardous in handling due to the high pH. It is possible to achieve a print of excellent quality and fixation on acid paper prepared by using rosin as a sizing agent. However, ink fixation considerably deteriorates when recording on neutral papers which utilize alkyl ketene dimer or anhydride stearic acid that have recently increased production amount in Japan. Further, printing quality slightly drops. Moreover, since the strong alkaline ink can penetrate into the paper, off-setting occurs and becomes very difficult to perform two-sided printing.
The techniques as aforementioned in (2) are excellent methods satisfying the foregoing 1) to 3) properties. However, they are known to have defects that printed portions swell up, and when storing print outs by putting one upon another in a pile, the printed items can be transferred to another sheet and paper sheets can stick to each other. Also, since a separate device is required for heating the ink, the entire configuration of the recording apparatus becomes complicated.
The conventional technique as aforementioned in (3) can provide a print with excellent ink fixation. However, an offensive odor of the organic solvent contained in the ink is a troublesome matter and consideration for safety is also necessary. Therefore, they are only used for industrial application such as printing of lot numbers on the bottom of containers and outside the boxes, and rarely used in offices or at home.
The conventional technique which uses the ink aforementioned in (4) is not considered as a good technique due to the printing quality as clearly disclosed in Japanese Patent Application Laid Open No.55-80477 and Japanese Patent Application Laid Open No.56-49771.
The technique which uses the ink aforementioned in (5) has a drying rate (fixation) of 8 to 15 seconds after printing as shown in Examples. Such data clearly demonstrates that the ink is excellent in fixation as compared to the conventional art. However, when the practical situation is considered in using a recording apparatus, the time 8 to 5 seconds is found very long. Also, when holding the print outs directly after being printed out from the printing apparatus, hands of operators may be stained. In some papers, significant feathering may occur. Therefore, there are demands for improvement.
The ink of (6) is, as the present inventors confirmed, excellent ink having a fixation time of less than 5 seconds. However, it has problems with the safety, fixation and printing quality on neutral paper, off-setting, as described in the aforementioned technique (1).
In general, for use in the office or at home, aqueous inks are preferred in terms of offensive odor, safety and handling. However, when using the aqueous inks, feathering tends to occur in the portions of recording medium, where stains such as fingerprints and the like stick. Also, the printing quality may significantly change between the front and the rear of the paper. Therefore, great care is required in handling recording media when placing the recording media on an ink jet recording apparatus.
Further, as is conventionally well known, when printing by an multi-nozzle ink jet recording apparatus using an aqueous ink including 1 to 5% by weight of an aqueous dye and 20 to 50% by weight of a water-soluble organic solvent such as glycols and having a surface tension of 40 to 55 mN/m, water contained in the ink may evaporate from the nozzles. Even during the printing operation, a nozzle which are not used for printing can be clogged. For example, when printing a numeral “1” after repetitively printing the “-”s for about 120 seconds, “1” may not correctly be printed, since while printing “-”s, nozzles which are not used in printing have been clogged, and thus the ink cannot be uniformly ejected from all the nozzles.
Furthermore, when leaving the recording apparatus without printing for a while (for example, during a weekend), the viscosity of the ink is increased due to water evaporation in the ink and causes frequent ejection failure. For this reason, the apparatus should always be cleaned before using and users feel reluctant and inconvenient over this operation. Such ejection failure is more frequently observed in a recording apparatus having a weak energy used to eject the ink. Thus, in a bubble jet recording apparatus which has an ejecting energy less than ink jet apparatus using a piezo element, ejection fai
Arita Hitoshi
Bannai Akiko
Gotoh Akihiko
Kaneko Tetsuya
Koyano Masayuki
Meier Stephen D.
Ricoh & Company, Ltd.
Shah Manish
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