Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-04-26
2004-07-06
Meier, Stephen (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S095000, C523S160000
Reexamination Certificate
active
06758559
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water-based ink for inkjet recording.
BACKGROUND ART
Inkjet recording is carried out by directly jetting ink droplets from very fine nozzles to a recording medium, and depositing the ink droplets on the recording medium, to form characters or images. As a colorant for black ink used for inkiet printing, a water-soluble black dye or an aqueous dispersion of carbon black has been used. The water-soluble black dye is excellent in jetting stability. However, there are some defects in the dye such that the dye is poor in water resistance and light fastness. Also, the aqueous dispersion of carbon black gives a high optical density. However, there are some defects in the aqueous dispersion of carbon black such that the aqueous dispersion of carbon black is poor in fixing ability on a paper surface, rubbing resistance and high-lighter fastness.
Therefore, for the purposes of improving fixing ability of the aqueous dispersion of carbon black on a paper surface, there has been proposed addition of a polymer emulsion giving film-forming ability to the aqueous dispersion of carbon black (Japanese Patent Laid-Open Nos. Hei 9-208870 and Hei 10-195355 and Hei 10-152640). When a large amount of the polymer emulsion is added, the fixing ability is improved. However, there are some defects in the polymer emulsion such that the optical density is lowered because the polymer emulsion does not act as a colorant. In addition, when the polymer emulsion is added within the range satisfying the optical density, the fixing ability is little improved.
In recent years, for the purposes of improving fixing ability and water resistance, there has been proposed an aqueous dispersion of a vinyl polymer containing an oil-soluble black dye (Japanese Patent Laid-Open No. Hei 9-241565). When this aqueous dispersion is used as an ink colorant, the fixing ability and the water resistance are surely improved, thereby exhibiting optical density like a water-soluble dye. However, the optical density would be insufficient for uses requiring a high optical density. Therefore, there are some defects in the aqueous dispersion such that the stability is lowered when the amount of an oil-soluble dye in the aqueous dispersion is increased for the purpose of improving the optical density, and that the viscosity is increased when the amount of the aqueous dispersion used is increased, thereby lowering the discharging ability.
DISCLOSURE OF INVENTION
An object of the present invention is to provide a water-based ink for inkjet recording showing high optical density, not giving distortion including crookedness to printed objects, and showing excellent water resistance, rubbing resistance and high-lighter fastness.
The present invention relates to a water-based ink for inkjet printing, comprising:
(A) an aqueous dispersion A of vinyl polymer particles prepared by including an oil-soluble black dye or carbon black in a water-insoluble vinyl polymer prepared by copolymerizing a salt-forming group-containing monomer (a) [hereinafter referred to as component (a)], a monomer (b) represented by the formula (I):
CH
2
═C(R
1
)COO(R
2
O)
p
R
3
(I)
wherein R
1
is hydrogen atom or a lower alkyl group; R
2
is a divalent hydrocarbon group which may have a hetero-atom; R
3
is a monovalent hydrocarbon group which may have a hetero-atom; p is a number of 1 to 60 [hereinafter referred to as component (b)], a macromer (c) [hereinafter referred to as component (c)], a monomer (d) copolymerizable with these monomers [hereinafter referred to as component (d)]; and
(B) an aqueous dispersion B of carbon black having the same ionicity as the aqueous dispersion A,
wherein the weight ratio of the solid content of the aqueous dispersion A to the solid content of the aqueous dispersion B (the solid content of the aqueous dispersion A/the solid content of the aqueous dispersion B) is 5/95 to 95/5.
BEST MODE FOR CARRYING OUT THE INVENTION
As the vinyl polymer used for the aqueous dispersion A, a water-insoluble vinyl polymer is used, and in order to obtain a water-based ink having both high fixing ability and high dispersion stability, there is used a water-insoluble vinyl polymer obtained by copolymerizing the component (a), the component (b), the component (c) and the component (d). or an anionic group when the group is neutralized with an acid or a base.
Representative examples of the component (a) include the cationic monomers and the anionic monomers described in page 5, column 7, line 24 to column 8, line 29 of Japanese Patent Laid-Open No. Hei 9-286939.
The cationic monomer includes tertiary amine-containing unsaturated monomers, ammonium salt-containing unsaturated monomers, and the like. Among them, N,N-dimethylaminophenyl acrylate, N,N-dimethylaminoethyl methacrylate, N-(N′,N′-dimethylaminopropyl) acrylamide, N-(N′,N′-dimethylaminopropyl) methacrylamide and vinylpyrrolidone are preferable.
The anionic monomer includes unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like. Among them, unsaturated carboxylic acid monomers, especially acrylic acid and methacrylic acid are preferable.
The component (b) exhibits excellent effects of increasing the jetting stability of the water-based ink of the present invention, and suppressing the generation of distortion even when printing is continuously carried out.
In the formula (I), R
1
is hydrogen atom or a lower alkyl group. The lower alkyl group includes linear or branched alkyl groups having 1 to 4 carbon atoms.
R
2
is a divalent hydrocarbon group which may have a hetero-atom. The hetero-atom includes, for example, nitrogen atom, oxygen atom, a halogen atom and sulfur atom.
Representative examples of R
2
include an aromatic ring having 6 to 30 carbon atoms, which may have a substituent; a heterocyclic ring having 3 to 30 carbon atoms, which may have a substituent; and an alkylene group having 1 to 30 carbon atoms, which may have a substituent. These rings or groups may be used in combination of at least two kinds. The substituent includes an aromatic ring having 6 to 29 carbon atoms; a heterocyclic ring having 3 to 29 carbon atoms; an alkyl group having 1 to 29 carbon atoms; a halogen atom; amino group, and the like.
Preferred examples of R
2
include a phenylene group which may have a substituent having 1 to 24 carbon atoms; an aliphatic alkylene group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms; an aromatic ring-containing alkylene group having 7 to 30 carbon atoms; and a heterocyclic ring-containing alkylene group having 4 to 30 carbon atoms.
In addition, preferred examples of R
2
O group include alkylene oxide groups having 2 to 7 carbon atoms such as ethylene oxide group, (iso)propylene oxide group, tetramethylene oxide group, heptamethylene oxide group, hexamethylene oxide group, and combinations of at least two kinds of these tri 15 alkylene oxide groups; and phenylene oxide group.
R
3
is a monovalent hydrocarbon group which may have a hetero-atom. The hetero-atom includes nitrogen atom, oxygen atom and sulfur atom. Representative examples of R
3
include an aromatic ring having 6 to 30 carbon atoms, which may have a substituent; a heterocyclic ring having 3 to 20 30 carbon atoms, which may have a substituent; and an alkyl group having 1 to 30 carbon atoms, which may have a substituent. The substituent includes an aromatic ring having 6 to 29 carbon atoms; a heterocyclic ring having 4 to 29 carbon atoms; a halogen atom; amino group, and the like.
Preferred examples of R
3
include phenyl group, an aliphatic alkyl group having 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms, an aromatic ring-containing alkyl group having 7 to 30 carbon atoms, and a heterocyclic ring-containing alkyl group having 4 to 30 carbon atoms.
More preferred examples of R
3
include alkyl groups having 1 to 6 carbon atoms, such as methyl group, ethyl group, (iso)propyl group, (iso)butyl group, (iso)
Nakano Yukihiro
Sawada Michitaka
Birch & Stewart Kolasch & Birch, LLP
Kao Corporation
Meier Stephen
Shah Manish
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