Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-09-02
2001-08-21
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031520, C106S031580
Reexamination Certificate
active
06277184
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a black ink composition for ink jet recording which can realize, even on plain papers, printed images having high quality and high color density and, at the same time, having excellent lightfastness and waterfastness.
2. Background Art
Ink jet recording is a printing method wherein droplets of an ink composition are ejected and deposited onto recording media, such as paper, to conduct printing. This method has a feature that images having high resolution and high quality can be printed at a high speed by means of relatively inexpensive apparatuses. In general, the ink composition used in the ink jet recording comprises water as a main component and, incorporated therein, a dye or a pigment as a colorant. and a wetting agent, such as glycerin, for preventing clogging and other purposes.
Further, in ink jet printers, good waterfastness and lightfastness are required of printed images from the viewpoint of enhancing the general-purpose properties of the ink jet printers. In order to improve the waterfastness of the printed images, Japanese Patent Laid-Open No.140495/1993 proposes an ink composition containing pyrrolidone which is 2-pyrrolidone, N-(2-hydroxyethyl)-2-pyrrolidone, or a mixture of 2-pyrrolidone with N-(2-hydroxyethyl)-2-pyrrolidone. Further, U.S. Pat. Nos. 4,963,189 and 5,203,912 disclose dyes which can be easily dissolved in bases, but are insoluble in water. These dyes have waterfastness which has been improved to some extent. However, there is still room for improvement in waterfastness. This is true of lightfastness.
Use of pigments as the colorant for satisfying both waterfastness and lightfastness requirements is well known in the art. In general, however, as compared with dyes, the pigments are likely to have inferior color development and to provide lower optical density.
In recent years, there is an increasing demand for high-speed printing. In order to realize high-speed printing, rapid fixation of ink onto recording media is necessary. This has lead to an attempt to improve the penetration of the ink into recording media. For example, Japanese Patent Laid-Open No. 183761/1992 and U.S. Pat. Nos. 5,156,675 and 5,183,502 disclose, for example, the addition of diethylene glycol monobutyl ether and the addition of a glycol ether in combination with a nonionic acetylene glycol surfactant.
In the highly penetrable ink using the pigment, however, the pigment to be stayed on the surface of the recording medium is more likely to be penetrated into the recording medium, due to the improved penetration, and to have poor color development. In particular, for plain papers not subjected to any special surface treatment (for example, copying papers, reporting papers, bond papers, letter papers, postcards, and slip sheets, used in offices, schools, households and the like), printed images were observed to have remarkably lowered optical density.
SUMMARY OF THE INVENTION
The present inventors have now found that use, as a colorant, of carbon black in combination with a specific black dye can realize printed images having high quality and high color density and, at the same time, having excellent lightfastness and waterfastness. More specifically, they have found that a combination of carbon black and a specific black dye in a specific weight ratio can realize an ink composition which can yield, even on plain papers, images having high quality (sharp images free from feathering) and high color density and can offer rapid ink fixation and can provide prints having excellent waterfastness and lightfastness. The present invention has been made based on such finding.
Accordingly, it is an object of the present invention to provide a black ink composition for ink jet recording which can realize, even on plain papers, printed images having high quality and high color density and, in addition, having excellent lightfastness and waterfastness.
Thus, according to the present invention, there is provided a black ink composition for ink jet recording, comprising at least carbon black, a black dye, a water-soluble organic solvent, and water,
the black dye being a black dye represented by formula (I), C.I. Direct Black 154, or C.I. Direct Black 168:
wherein M represents a cation of a group selected from the group consisting of a hydrogen atom, an alkali metal, ammonia, and an organic amine; m is 1 or 2; and n is 0 or 1.
According to a preferred embodiment of the present invention, in the black ink composition for ink jet recording, the weight ratio of the carbon black to the black dye is in the range of 2.5:1 to 7:1.
Further, according to a preferred embodiment of the present invention, in the black ink composition for ink jet recording, the water-soluble organic solvent is a polyhydric alcohol lower alkyl ether or an acetylene glycol represented by formula (II):
wherein X represents CH
2
—CH
2
—O, R
1
, R
2
, R
3
, and R
4
each independently represent a C
1-6
alkyl group, and n+m is 0 to 30.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Ink Composition
According to the present invention, the black ink composition for ink jet recording basically comprises carbon black, a specific black dye, a water-soluble organic solvent, and water.
Carbon Black
Carbon blacks (C.I. Pigment Black 7) usable in the present invention include furnace black, lamp black, acetylene black, and channel black.
The content of the pigment, that is, carbon black, is preferably about 0.1 to 15% by weight, more preferably about 2 to 10% by weight, based on the ink composition.
According to a preferred embodiment of the present invention, the black pigment (carbon black) is added, to the ink, as a pigment dispersion prepared by dispersing the black pigment in an aqueous medium with the aid of a dispersant. Preferred dispersants include dispersants commonly used in the preparation of pigment dispersions, for example, polymeric dispersants and surfactants. Specific examples of polymeric dispersants usable herein include naturally occurring polymers and synthetic polymers. Among them, synthetic polymers are particularly preferred.
Representative examples of preferred synthetic polymers include: polyvinyl alcohols; polyvinyl pyrrolidones; acrylic resins, such as polyacrylic acid, acrylic acid/acrylonitrile copolymer, potassium acrylate/acrylonitrile copolymer, vinyl acetate/acrylic ester copolymer, and acrylic acid/alkyl acrylate copolymer; styrene/acrylic acid resins, such as styrene/acrylic acid copolymer, styrene/methacrylic acid copolymer, styrene/methacrylic acid/alkyl acrylate copolymer, styrene/&agr;-methylstyrene/acrylic acid copolymer, and styrene/&agr;-methylstyrene/acrylic acid/alkyl acrylate copolymer; styrene/maleic acid copolymer; styrene/maleic anhydric copolymer; vinyl naphthalene/acrylic acid copolymer; vinylnaphthalene/maleic acid copolymer; vinyl acetate copolymers, such as vinyl acetate/ethylene copolymer, vinyl acetate/fatty acid vinylethylene copolymer, vinyl acetate/maleic ester copolymer, vinyl acetate/crotonic acid copolymer, and vinyl acetate/acrylic acid copolymer; and salts of the above polymers. Among them, copolymers of monomers having a hydrophobic group with monomers having a hydrophilic group, and polymers comprising monomers having both hydrophobic and hydrophilic groups are particularly preferred. Examples of salts of the above polymers include salts of the above polymers with diethylamine, ammonia, ethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, aminomethylpropanol, morpholine or the like. The weight average molecular weight of these copolymers is preferably 3,000 to 30,000, more preferably 5,000 to 15,000. According to the present invention, among the above polymers, styrene/acrylic acid resins, such as styrene/acrylic acid copolymer, styrene/methacrylic acid copolymer, styrene/methacrylic acid/alkyl acrylate copolymer, styrene/&agr;-methylstyrene/acrylic acid copolymer, and styrene/&agr;-methylstyrene/acrylic acid/
Klemanski Helene
Ladas & Parry
Seiko Epson Corporation
LandOfFree
Black ink composition for ink jet recording does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Black ink composition for ink jet recording, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Black ink composition for ink jet recording will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2503019