Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2002-06-24
2004-06-29
Powers, Fiona T. (Department: 1626)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031480, C106S031500, C534S693000, C534S703000, C534S705000, C534S707000, C534S710000, C534S711000, C534S712000
Reexamination Certificate
active
06755903
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a water soluble dyestuff for inkjet recording and an aqueous inkjet recording liquid using the same. More specifically, it relates to a metal chelated dyestuff comprising a water soluble azo metal chelated compound suitable for inkjet recording and an aqueous inkjet recording liquid using the same.
BACKGROUND ART
The recording by blowing drops of recording liquid containing a water soluble dye such as a direct dye or an acid dye from a minute orifice, so-called inkjet recording method has been practically used.
With regard to the recording liquid, it is required to exhibit fast fixing to a recording paper widely used at general office work such as a paper for PPC (plain paper copier), i.e., a paper for electrophotography, fanhold paper (a continuous paper for computer, etc.), or the like, and also a good print quality of a printed matter, that is, no blotting and a clear outline. In addition, it is necessary to be excellent in stability during storage as a recording liquid. Therefore, the solvents which are possible to use are strictly limited.
With regard to the dye for the recording liquid, it is required that it has a sufficient solubility for the above limited solvents, and, in addition, is stable as a recording liquid even when it has been stored for a long period of time, and a printed image has high saturation and density, as well as the dye is excellent in water resistance, light resistance and indoor discoloring and fading property.
On the other hand, for forming a full color image in the inkjet recording method, using inks of three primary colors of yellow (Y), magenta (M) and cyan (C) or four colors wherein black (B) is additionally used, an image is formed by controlling the discharging amount of each ink through the mixing of these colors on a material to be recorded. Furthermore, at the formation of a full color image, it is necessary to express not only difference of colors but also shade of colors. The shade part is usually formed by the use of two or more inks different in concentration of dyestuff.
However, with regard to the conventional dyestuffs for inkjet, there is a problem of fading of an image caused by light irradiation, that is, a poor light resistance. In particular, it is a problem that a pale color part where an ink low in concentration of dyestuff is used exhibits a poor light resistance. Thus, it is desired to develop a dyestuff for inkjet which satisfies these many requirements at the same time.
In particular, as the magenta dyestuff to be used in the recording liquid, a metal-free direct dye (C.I. DR-227) and an acid dye (C.I. AR-249) which are commercially available dyes are hitherto employed (by the way, “C.I.” means “Color Index”, “AR” means “Acid Red”, and “DR” means “Direct Red”.).
A direct dye is unclear in color tone, but an acid dye showing a clear color tone tends to exhibit an inferior light resistance. Moreover, heretofore, a metal-containing azo dye has a good light resistance but exhibits a somber color tone and poor clearness. Therefore, it is desired to develop a dyestuff for inkjet which satisfies both of the color tone and light resistance.
Japanese Patent Laid-Open No. 42775/1982 discloses an aqueous ink for inkjet printing wherein at least one kind of 5-hydroxypyrazole azo dye having an azo group at the 4-position or complex salt dye thereof with copper, nickel or cobalt. However, the bonding position of the pyrazole ring to the azo group of the dye described therein is different from that in the general formula (1) of the invention.
Japanese Patent Laid-Open No. 259331/1998 discloses an aqueous inkjet recording liquid which contains a water soluble metal complex formed from a benzene azo compound and at least one kind of metal selected from nickel, cobalt, chromium or copper. However, the metal complex is different from the compound of the general formula (1) of the invention in view that the complex does not have a naphthalene ring.
Japanese Patent Laid-Open No. 140367/1999 discloses an ink composition containing a magenta dye ligand of 4-hydroxy-3-(2′-pyridylazo)-1-(sulfo substituted)naphthalene which coordinates to a polyvalent metal ion, and an ink vehicle. However, there is a difference in view that the compound of the general formula (1) of the invention is an azo compound having no pyridine ring.
These dyestuffs described in the known literatures not always satisfy the properties required for the dyestuff for inkjet printing such as clearness of color tone, light resistance, indoor discoloring and fading property, solubility, storage stability, and the like, sufficiently.
An object of the invention is to provide a water soluble dyestuff for inkjet printing which result in a good print quality even at printing on a plain paper and also a clear color tone with a high density, an excellent light resistance, small indoor discoloring and fading of a printed image, and exhibits a good solubility or stability during a long time storage of the dyestuff, and an aqueous inkjet printing liquid using the same.
DISCLOSURE OF THE INVENTION
The present inventors have achieved the above object by the use of a water soluble dyestuff which is an azo chelated compound of a specific azo compound with a metal element.
Namely, the gist of the invention is a metal chelated dyestuff for inkjet recording which is a water soluble azo metal chelated compound formed from an azo compound represented by the following general formula (1) and a metal element, and an aqueous ink jet recording liquid which contains at least one kind of the dyestuff selected from the metal chelated dyestuff and an aqueous medium.
(where general formula (1) represents an azo dyestuff compound having at least one or more hydrophilic group in a molecule, X
1
represents plural atoms required for forming at least one 5- to 7-membered heterocyclic ring, the heterocyclic ring containing X
1
being a heterocyclic ring other than pyridine ring. The heterocyclic ring containing X
1
may have substituent(s) on the heterocyclic ring, the substituent(s) on the heterocyclic ring may form a condensed ring through further condensation. The condensed heterocyclic ring containing X
1
may be substituted. Ar
1
represents a naphthyl group represented by the following general formulae (2)-(4). Y
1
represents a chelating group, Z
1
represents any substituent which may be different from each other, and a represents an integer of 0 to 6.)
BEST MODE FOR CARRYING OUT THE INVENTION
The following will explain the present invention in detail.
The metal chelated dyestuff of the invention is a water soluble azo metal chelated compound formed from an azo compound represented by the above general formula (1) and a metal element.
X
1
represents two or more atoms necessary for forming at least one 5- to 7-membered heterocyclic ring but the heterocyclic ring containing X
1
is a heterocyclic ring other than pyridine ring. The heterocyclic ring containing X
1
is preferably imidazole ring, pyrazole ring, isoxazole ring, thiazole ring, thiadiazole ring, pyridazine ring, pyrimidine ring, pyrazine ring, benzothiazole ring, benzoxazole ring, or benzimidazole ring. Among them, it is preferred that the heterocyclic ring containing X
1
is imidazole ring, pyrazole ring, thiazole ring, or thiadiazole ring.
The heterocyclic ring containing X
1
may have one or more subtituents on the heterocyclic ring, and the substituent(s) on the heterocyclic ring may form a condensed ring through further condensation. In that case, the substituents on the heterocylic ring each is selected independently from alkyl group which may be substituted (e.g., alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, or the like, carboxymethyl group, carboxyethyl group, trifluoroniethyl group, or the like), aryl group which may be substituted (preferably aryl group having 6 to 10 carbon atoms, e.g., phenyl group, naphthyl group, or the like), aralkyl group which may be substituted (benzyl group or the like, preferably aralkyl group having 7 to 10 carbon atoms
Chino Tomohiro
Yamada Masahiro
Yoneyama Tomio
Mitsubishi Chemical Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Powers Fiona T.
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