Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-02-16
2002-04-23
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031650, C106S031860
Reexamination Certificate
active
06375728
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink for ink jet recording for use in ink jet system recording apparatuses (e.g., printer, copying machine, facsimile, word processor, plotter), a method for producing the ink, and an ink jet recording method using the ink.
BACKGROUND OF THE INVENTION
Recording apparatuses using a so-called ink jet system in which a liquid or fused solid ink is ejected from nozzle, slit, porous film or the like to make recording on a recording material such as paper, cloth or film are advantageous in that the apparatus is compact, inexpensive and noiseless. Accordingly, various investigations are being made thereon. In recent years, a large number of products are commercially available and predominating in the field of recording apparatus, where not only black single color recording but also full color recording with good print quality can be obtained on a so-called plain paper such as report paper or copy paper.
In usual, the ink for use in ink jet recording apparatuses mainly comprises a solvent, a coloring material and additives. The ink for ink jet recording is required to have the following properties:
(1) that a high-resolution and high-density uniform image can be obtained without causing blotting or fogging on paper;
(2) that clogging of a nozzle tip due to drying of the ink does not occur and ejection responsibility and ejection stability are always kept in good condition;
(3) that the ink on paper exhibits good drying property;
(4) that the image has good fastness; and
(5) that high stability is ensured in the long-term storage.
In order to satisfy these requirements, various techniques have been proposed. For example, (3) the drying property of the ink on paper is important for achieving high-speed printing in the recording apparatus or in the case of color printing, for preventing color mixing and improvement of this drying property has been heretofore made by using a solvent having a high permeability or volatility or by adding a surfactant.
With respect to (4) the fastness of the image, a large number of inks have been disclosed where the water resistance is improved by using a pigment in place of a dye as a coloring material (see, JP-A-56-147869 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”), JP-A-2-255875, U.S. Pat. No. 5,085,698). When a pigmented ink is used, the water resistance may be improved, however, the ink is disadvantageously inferior to a dyed ink in the rub resistance. Furthermore, when a pigmented ink is used, the long-term storage stability (5) is generally deteriorated as compared with dyed inks.
In order to solve these problems with the use of a pigment, for example, U.S. Pat. No. 5,571,311 discloses a method of coupling a substituent having a water solubilization group with carbon black, JP-A-8-81646 discloses a method of polymerizing a water-soluble monomer or the like to the carbon black surface, and JP-A-8-3498 discloses a method of oxidation treating carbon black.
However, an ink for ink jet recording having good long-term storage stability and fast drying property on a plain paper and capable of giving an image having good print quality and excellent water resistance/rub resistance has not yet been found.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to solve these problems in conventional techniques and provide an ink having good long-term storage stability and fast drying property on a plain paper and capable of giving an image having good print quality and excellent water resistance/rub resistance.
The present inventors have found that when an ink for ink jet recording comprising water, a water-soluble organic solvent and a water self-dispersible pigment (i.e., a pigment that is self-dispersible-in-water) contains a water-soluble organic compound having an S.P. value of 12 or less and a surface tension at 250° C. of less than 40 mN/m in an amount of from 3.0 to 15.0 wt % based on the entire weight of the ink, the above-described object can be obtained. The present invention has been accomplished based on this finding.
More specifically, the present invention consists of:
an ink for ink jet recording comprising water, a water self-dispersible pigment and a water-soluble organic solvent, wherein the ink for ink jet recording contains a water-soluble organic compound having an S.P. value of 12 or less and a surface tension at 25° C. of less than 40 mN/m in an amount of from 3.0 to 15.0 wt % based on the entire weight of the ink;
a process for producing an ink for ink jet recording, comprising a step of dispersing a water self-dispersible pigment in water using an ultrasonic homogenizer or high-pressure homogenizer and a step of mixing the pigment dispersed with water, a water-soluble solvent and a water-soluble organic compound having an S.P. value of 12 or less and a surface tension at 25° C. of less than 40 mN/m; and
an ink jet recording method comprising ejecting the above-described ink from an orifice in response to a recording signal.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The “water self-dispersible pigment” as used in the present invention means a pigment having a large number of water solubilization groups on the surface thereof and capable of stable dispersion even in the absence of a dispersant. The “water self-dispersible pigment” of the present invention may be any pigment if the pigment satisfies the condition such that when a pigment is dispersed in water by means of a dispersing machine such as ultrasonic homogenizer, nanomizer, microfluidizer or ball mill without using a dispersant to have a concentration of water/pigment being 95 wt %/5 wt % and thereafter the dispersion solution placed in a glass bottle is allowed to stand for 1 day, the pigment concentration in a supernatant obtained is 98% or more of the initial pigment concentration measured immediately after the preparation of the dispersion solution.
The “water self-dispersible pigment” of the present invention can be usually produced by applying a surface modification treatment to a normal pigment, such as acidbase treatment, coupling agent treatment, polymer graft treatment, plasma treatment or oxidation and reduction treatment. The pigment subjected to such a surface treatment is increased in the number of water solubilization groups therein than usual and can be dispersed by itself. Preferred examples of the normal pigment subjected to the surface modification treatment include carbon black such as Raven 5250, Raven 3500, Raven 5750, Raven 1080, Regal 330R, Mogul L, Monarch 1000, Color Black FW2, Black Pearl L, Printex V, Special Bk 4A and Mitsubishi Chemical No. 25. Other examples of the pigment which can be used include cyan pigments such as C.I. Pigment Blue 1, C.I. Pigment Blue 3, C.I. Pigment Blue 15, C.I. Pigment Blue 15-3, C.I. Pigment Blue 16 and C.I. Pigment Blue 60; magenta pigments such as C.I. Pigment Red 5, C.I. Pigment Red 12, C.I. Pigment Red 48, C.I. Pigment Red 112, C.I. Pigment Red 122, C.I. Pigment Red 146, C.I. Pigment Red 168 and C.I. Pigment Red 202; and color pigments such as C.I. Pigment Yellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. Pigment Yellow 13, C.I. Pigment Yellow 16, C.I. Pigment Yellow 73, C.I. Pigment Yellow 83, C.I. Pigment Yellow 98, C.I. Pigment Yellow 114, C.I. Pigment Yellow 128 and C.I. Pigment Yellow 154.
Furthermore, a commercially available water self-dispersible pigment may be used as it is as the “water self-dispersible pigment” for use in the present invention. Examples of such a commercially available water self-dispersible include Cab-o-jet-200, Cab-o-jet-300, IJX-55 (all produced by Cabot Co.) and Microjet Black CW-1 (produced by Orient Kagaku KK).
The water solubilization group contained in the water self-dispersible pigment may be nonionic, cationic or anionic and predominantly, a sulfonic acid, a carboxylic acid, a hydroxyl group, a phosphoric acid and the like are preferably added. In the case of a sulfonic acid, a carboxylic aci
Hashimoto Ken
Inoue Hiroshi
Yamashita Yoshiro
Finnegan Henderson Farabow Garrett & Dunner LLP
Fuji 'Xerox Co., Ltd.
Klemanski Helene
LandOfFree
Ink for ink jet recording and ink jet recording method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink for ink jet recording and ink jet recording method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink for ink jet recording and ink jet recording method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2825698