Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2001-04-11
2004-10-12
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031860, C106S031890
Reexamination Certificate
active
06802893
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink for ink jet recording, a process for the preparation thereof, an ink set for ink jet recording, and an ink cartridge.
More particularly, the present invention relates to an ink for ink jet recording comprising at least a particulate pigment having a sulfur-containing dispersibility providing group chemically bonded to the surface thereof with a treatment containing sulfur, a penetrating agent, and water, characterized by the following aspects:
(a) An ink for ink jet recording wherein the sulfur content in the liquid component of the ink is kept to a predetermined level or less (hereinafter referred to as “first ink of the invention”);
(b) An ink for ink jet recording wherein the amount of the sulfur-containing dispersibility providing group is kept to a predetermined value or more (hereinafter referred to as “second ink of the invention”) and a process for the preparation thereof;
(c) An ink for ink jet recording wherein the sulfur-containing dispersibility providing group is a predetermined ion group and the cation as its counter ion is predetermined (hereinafter referred to as “third ink of the invention”) and a process for the preparation thereof;
(d) An ink for ink jet recording comprising a specific preservative incorporated therein (hereinafter referred to as “fourth ink of the invention”); and
(e) An ink for ink jet recording comprising a predetermined penetrating agent incorporated therein (hereinafter referred to as “fifth ink of the invention”).
The present invention further relates to an ink set for ink jet recording comprising the foregoing first and second inks of the invention. The present invention still relates to an ink cartridge for ink jet recording apparatus.
BACKGROUND ART
(Prior Art Concerning Ink)
As a colorant to be incorporated in an ink for ink jet recording there has heretofore been mainly used a dye. The use of a dye, which exhibits an excellent fastness, has recently been studied.
A pigment is superior to a dye in respect to fastness such as water resistance and light-resistance. However, since a pigment cannot be dissolved in water unlike a dye, it is important for pigment ink to allow the pigment to be finely dispersed in water in a stable manner. Further, when a penetrating agent is incorporated in a pigment ink for the purpose of enhancing the penetrating power of the ink, the dispersion stability of the particulate pigment is remarkably impaired, making it impossible to secure the ink with a desired storage stability.
As a method for rendering the surface of a particulate pigment wettable with water to prevent the agglomeration and precipitation of pigment particles, it has been practiced to disperse pigment particles in an aqueous solvent with a dispersant such as various surface active agents and aqueous resins. For examples, JP-A-3-157464 (The term “JP-A” as used herein means an “unexamined published Japanese patent application”) gives a study of a pigment ink comprising an acetylene glycol-based penetrating agent incorporated therein wherein as a dispersant for particulate pigment there is used a polymer dispersant and as an aqueous medium there is used water, nonvolatile organic solvent or lower alcohol to secure the dispersion stability thereof. However, when a dispersant is thus used for particulate pigment, the preparation of the ink requires more factors, making it difficult to allow desired design of ink physical properties such as viscosity. With this pigment ink, too, the foregoing problem that desired print density can be hardly secured is left unsolved.
As another method for dispersing a pigment in water there has been proposed a technique involving the introduction of sulfonic acid group onto the surface of a particulate pigment. For example, JP-A-10-110129 discloses a recording solution for ink jet recording comprising a sulfonated surface-treated organic pigment obtained by treating with a sulfonating agent an organic pigment dispersed in a solvent free of active proton. The above cited patent application discloses that the foregoing recording solution for ink jet recording has a stable dispersibility and thus can be securely ejected from the nozzle. Further, JP-A-11-49974 discloses that an organic bulk pigment which can be positively charged on the surface thereof is prepared by treating an organic bulk pigment having a sulfonic acid group introduced therein with a monovalent metal ion. The above cited patent application also discloses an aqueous ink composition which comprises a particulate pigment prepared from the surface positively chargeable organic bulk pigment, a dispersant and water and thus exhibits an excellent storage stability.
The inks comprising a surface-treated particulate pigment proposed in the foregoing two patent applications can satisfy various requirements as compared with the conventional pigment-based ink jet recording inks but leave something to be desired in storage stability because they comprise various components incorporated therein in combination to have desired print quality and dryability.
On the other hand, an ink for ink jet printer is required to meet various physical properties. In particular, it is important to secure desired storage stability and ejection stability (prevention of dot drop and clogging). Further, printing on recording paper is required to meet the following requirements (1) to (3):
(1) The printed image has little irregular bleeding;
(2) The image which has been printed can rapidly dry; and
(3) The printed image has a high print density.
In order to meet the foregoing requirements (1) to (3), various studies have long been made. For example, an approach involving the enhancement of the penetrating power of an ink for the purpose of eliminating bleeding on printed image and improving the dryability of printed image has been studied. U.S. Pat. No. 5,156,675 proposes the use of diethylene glycol monobutyl ether. U.S. Pat. No. 5,183,502 proposes the use of an acetylene glycol-based surface active agent.
However, the foregoing ink which comprises such a penetrating agent incorporated therein to have a drastically improved penetrating power is disadvantageous in that the colorant, too, penetrates deep into the recording paper, making it difficult to secure the printed image with a desired print density.
It has thus been desired to provide an ink for ink jet printer which can meet not only the foregoing requirements for physical properties, particularly storage stability and ejection stability (prevention of dot drop and clogging) but also the foregoing requirements (1) to (3).
(Prior Art Concerning Ink, Particularly Penetrating Agent)
An ink to be used in ink jet recording is required to meet requirements that the printed matter thus obtained dry fairly dry and show no bleeding, the ink can be printed uniformly on the surface of all recording media and a plurality of colors, if any, be not mixed. A particular problem that can occur is that when paper is used as a recording medium, the ink can undergo bleeding with fibers having different penetrabilities.
The most conventional inks for ink jet recording comprise glycol ether incorporated therein as a wetting agent as disclosed in JP-B-2-2907 (The term “JP-B” as used herein means an “examined Japanese patent application”), comprise a water-soluble organic solvent as disclosed in JP-B-1-15542 or comprise a dye dissolution accelerator incorporated therein as disclosed in JP-B-2-3837.
In order to enhance penetrating power, the addition of diethylene glycol monobutyl ether has been studied as disclosed in U.S. Pat. No. 5,156,675, the addition of Surfynol 465 (produced by Air Products Co., Ltd.), which is an acetylene glycol-based surface active agent, has been studied as disclosed in U.S. Pat. No. 5,183,502, and the addition of both diethylene glycol monobutyl ether and Surfynol 465 has been studied as disclosed in U.S. Pat. No. 5,196,056. Diethylene glycol mono-n-butyl ether is called “butyl carbitol” and is disclosed in, e.g., U.S. Pat. No. 3,291,580. Further, U.S. Pat. No. 2
Hayashi Hiroko
Ito Fumitsugu
Komatsu Hidehiko
Matsuzaki Makoto
Nakamura Hiroto
Bell Mark L.
Faison Veronica F.
Ladas & Parry
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