Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-06-11
2004-07-13
Shosho, Callie (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S504000
Reexamination Certificate
active
06762217
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-based ink. More specifically, the present invention relates to a water-based ink which can be suitably used as a water-based ink for inkjet recording and the like.
2. Discussion of the Related Art
As water-based fluorescent ink compositions, there have been proposed an ink composition prepared by dissolving a water-soluble fluorescent dye in an aqueous medium as disclosed in Japanese Patent Laid-Open No. Hei 09-249835; an ink composition prepared by dispersing a fluorescent pigment in an aqueous medium or an organic solvent with a surfactant or a dispersant as disclosed in Japanese Patent Laid-Open No Hei 10-130558; an ink composition prepared by adsorbing an oil-soluble fluorescent dye to fine solid particles as disclosed in Japanese Patent Laid-Open No. Hei 09-78012; and ink composition prepared by incorporating an oil-soluble fluorescent dye into polymer particles by emulsion polymerization as disclosed in Japanese Patent Laid-Open No. Hei 08-53640; and the like.
However, there are some defects in the ink composition prepared by simply dissolving the water-soluble fluorescent dye in the aqueous medium such that the water resistance of the printouts is insufficient, and that its fluorescent intensity is affected by the environment, especially humidity, and the like. In addition, there are some defects in the ink composition prepared by dispersing the fluorescent pigment in the aqueous medium or the organic solvent with the surfactant or the dispersant such that clogging is generated in the nozzles in the inkjet recording, and that the ink composition has deteriorated jetting stability, so that sediments are generated when the ink is stored for a long period of time.
Also, there are some defects in the ink composition prepared by adsorbing the oil-soluble fluorescent dye to the fine solid particles such that the amount of the dye which can be adsorbed is small, so that the ink composition has a low fluorescent intensity. Moreover, there are some defects in the ink composition prepared by incorporating the oil-soluble fluorescent dye into the polymer particles such that the amount of the dye which can be incorporated is small, so that printouts have a low fluorescent intensity and a low optical density.
An object of the present invention is to provide a water-based ink which gives printouts a sufficient fluorescent intensity and excellent water resistance and environmental resistance, and is excellent in storage stability for a long period of time.
Another object of the present invention is to provide a water-based ink for inkjet recording ensuring stable ink jetting property in the inkjet recording.
These and other objects of the present invention will be apparent from the following description.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a water-based ink comprising an aqueous dispersion of polymer particles comprising a polymer obtained by a solution polymerization, a bulk polymerization method or a suspension polymerization method, and a fluorescent colorant
DETAILED DESCRIPTION OF THE INVENTION
The water-based ink of the present invention comprises polymer particles comprising a polymer obtained by a solution polymerization method, a bulk polymerization method or a suspension polymerization method. Therefore, printouts obtained from the water-based ink exhibit sufficient fluorescent intensity, excellent water resistance and excellent environmental resistance, and the water-based ink is also excellent in storage stability for a long period of time. Further, stable inkjetting property is secured in inkjet recording.
When the fluorescent colorant is contained in the polymer particles, the content of the fluorescent colorant in the water-based ink can be increased. Therefore, the fluorescent intensity and optical density obtained from the water-based ink can be enhanced, and its water resistance and environmental resistance can be increased.
In addition, when an oil-soluble fluorescent dye or a fluorescent disperse dye is used as the fluorescent colorant, the water resistance of the printouts can be improved.
Further, when a vinyl-based graft copolymer (hereinafter simply referred to as “graft copolymer”) is used as the polymer, there is an advantage that a large amount of the fluorescent colorant can be stably contained in the graft copolymer.
It is preferable that the graft copolymer has at least one branched chain selected from the group consisting of styrenic polymers such as styrene-acrylonitrile copolymers, alkyl (meth)acrylate polymers (the term “(meth)acrylate” as referred to herein means “acrylate” and/or “methacrylate,” hereinafter referred to the same), alkylene oxide adduct polymers, and polysiloxanes, because a large amount of the fluorescent colorant can be stably contained in the graft copolymer, and stable inkjetting property can be exhibited in ink-jet recording.
The graft copolymer having a branched chain of a styrenic polymer can be obtained by copolymerizing a mixture comprising a styrenic macromer, a polymerizable unsaturated monomer having a salt-forming group and a monomer copolymerizable with the styrenic macromer and the polymerizable unsaturated monomer having a salt-forming group in the presence of a radical polymerization initiator.
The styrenic macromer includes a styrenic macromer comprising a styrene homopolymer having a polymerizable functional group at one end; a styrenic macromer having a polymerizable functional group at one end comprising a copolymer of styrene and a polymerizable unsaturated monomer such as acrylonitrile, the macromer; and the like.
In the styrenic macromer having a polymerizable functional group at one end, the polymerizable functional group includes, for instance, vinyl group and the like.
It is desired that the number-average molecular weight of the styrenic macromer is 500 to 30000, preferably 1000 to 10000, from the viewpoints of the content of the fluorescent colorant, storage stability and viscosity of an ink.
Representative examples of the styrenic macromer having a polymerizable functional group at one end include a styrene homopolymer having a vinyl group at one end (e.g. one commercially available from TOAGOSEI CO., LTD. under the trade name of AS-6, and the like); a styrene-acrylonitrile (molar ratio: 1/1) copolymer having a vinyl group at one end (e.g. one commercially available from TOAGOSEI CO., LTD. under the trade name of AN-6, number-average molecular weight: 6000, and the like), and the like.
Representative examples of the polymerizable unsaturated monomer having a salt-forming group include cationic monomers, anionic monomers, and the like.
Representative examples of the cationic monomer include unsaturated cyclic amines, tertiary amine-containing unsaturated monomers, ammonium salt-containing unsaturated monomers, and the like.
Concrete examples of the cationic monomer include:
monovinylpyridines such as vinylpyridine, 2-methyl-5-vinylpyridine and 2-ethyl-5-vinylpyridine;
styrenes having a dialkylamino group, such as N,N-dimethylaminostyrene and N,N-dimethylaminomethylstyrene;
acrylates or methacrylates having a dialkylamino group, such as N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl acrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylate, N,N-dimethylaminopropyl methacrylate, N,N-diethylaminopropyl acrylate and N,N-diethylaminopropyl methacrylate;
vinyl ethers having a dialkylamino group, such as 2-dimethylaminoethyl vinyl ether;
acrylamides or methacrylamides having a dialkylamino group such as N-(N′,N-dimethylaminoethyl)acrylamide, N-(N′,N′-dimethylaminoethyl)methacrylamide, N-(N′,N′-diethylaminoethyl)acrylamide, N-(N′,N′-diethylaminoethyl)methacrylamide, N-(N′,N′-dimethylaminopropyl)acrylamide, N-(N′,N′-dimethylaminopropyl)methacrylamide, N-(N′,N′-diethylaminopropyl)acrylamide, and N-(N′,N′-diethylaminopropyl)met
Nakano Yukihiro
Wakabayashi Shigemi
Kao Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shosho Callie
LandOfFree
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