Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
2000-04-06
2003-02-04
Bell, Mark L. (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031780, C106S031580, C106S031860
Reexamination Certificate
active
06514330
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink composition for ink jet recording, comprising a copper complex colorant, such as a copper complex dye or a copper phthalocyanine pigment.
2. Background Art
Ink jet recording is a printing method wherein droplets of an ink composition are ejected and deposited onto recording media, such as paper, to conduct printing. This method has a feature that images having high resolution and high quality can be printed at a high speed by means of relatively inexpensive apparatuses. Properties associated with reliability, such as freedom from the occurrence of precipitate, such as precipitate, in the ink composition, good recovery from nozzle clogging, and excellent storage stability, are required for an ink composition for ink jet recording.
In the case of ink compositions using dyes as the colorant, metal ions (such as calcium, magnesium, silicon, and iron ions) contained in the ink compositions are sometimes causative of the occurrence of precipitate or deteriorated recovery from clogging. For this reason, these metal ions should be kept in a certain amount or less. For example, how to remove calcium ions is described in Japanese Patent Laid-Open No. 5073/1993.
According to studies conducted by the present inventors, however, for ink compositions using copper complex dyes, the occurrence of precipitate in the ink compositions or poor recovery from clogging was observed even under conditions such that the metal ions were controlled in the certain amount or less.
On the other hand, in the case of ink compositions using non-water-soluble pigments as the colorant, the particle diameter of the pigments per se sometimes causes the occurrence of precipitate or deteriorated recovery from nozzle clogging. Therefore, the regulation of the particle diameter is important to pigment-based ink compositions. Even though the particle diameter of ingredients in the ink composition is regulated at the time of the preparation of the ink composition, precipitate or the like often occurs prior to use of the ink composition. According to studies conducted by the present inventors, the occurrence of precipitate was observed in ink compositions containing copper complex colorants, such as copper phthalocyanine pigments or dyes having a copper complex structure.
SUMMARY OF THE INVENTION
The present inventors have now found that the regulation of the concentration of free copper ions in ink compositions for ink jet recording, containing a copper complex colorant, such as a copper complex dye or a copper phthalocyanine pigment, can effectively prevent the occurrence of precipitate and, at the same time, can realize, on a high level, various properties required of ink compositions for ink jet recording. The present invention has been made based on such finding.
Accordingly, it is an object of the present invention to provide a precipitation-free ink composition for ink jet recording.
It is another object of the present invention to provide an ink composition for ink jet recording which can realize, on a high level, various properties required of ink compositions for ink jet recording.
According to one aspect of the present invention, there is provided an ink composition for ink jet recording, comprising a copper complex colorant, said ink composition having a free copper ion concentration of not more than 10 ppm.
DESCRIPTION OF PREFERRED EMBODIMENTS
The ink composition according to the present invention contains a copper complex colorant as a colorant. According to a preferred embodiment of the present invention, specific examples of copper complex colorants usable herein include copper complex dyes and copper phthalocyanine pigments.
Specific examples of copper complex dyes usable herein include: C.I. Direct Violet 47, 48, 90, and 91; C.I. Direct Blue 86, 87, 90, 98, 194, 195, 196, 199, 226, and 248; C.I. Direct Brown 95, 100, 112, 194, and 211; C.I. Direct Black 71, 105, 106, 107, 108, and 146; C.I. Acid Red 161; C.I. Acid orange 87, 88, and 122; C.I. Acid Red 194, 209, 211, 215, and 216; C.I. Acid Blue 151, 154, 167, 168, 170, 171, 184, 187, 199, 229, and 234; C.I. Acid Green 56, 57, 60, and 65; C.I. Acid Brown 231, 232, 294, and 296; C.I. Acid Black 58, 60, 62, 64, 107, 108, 112, 115, 118, 119, 121, 122, 131, 132, 139, 140, 155, and 156; C.I. Mordant Blue 58; C.I. Solvent Yellow 61 and 80; C.I. Solvent Orange 37, 40, and 44; C.I. Solvent Red 83, 84, and 121; C.I. Solvent Violet 21; C.I. Solvent Blue 55; C.I. Solvent Black 22 and 23; C.I. Reactive Red 6, 7, 27, 32, and 130; C.I. Reactive Violet 1, 2, 3, 4, and 5; C.I. Reactive Blue 3, 7, 9, 10, 13, 14, 15, 18, 20, 21, 25, 26, 38, 40, 41, 43, 52, 63, 71, 72, 77, 79, 80, 105, 113, 15 118, 120, 121, 122, 131, 140, 147, and 148; C.I. Reactive Brown 14, 18, and 19; C.I. Reactive Black 1, 8, 9, 13, 31, and 35; C.I. Reactive Green 5, 12, 14, and 15.
According to a preferred embodiment of the present invention, the copper phthalocyanine pigment is represented by the following formula:
wherein X represents a chlorine or bromine atom or a hydrogen atom; and n is an integer of 14 to 16.
The copper phthalocyanine pigment is more preferably selected from the group consisting of C.I. Pigment Green 7 and 36 and C.I. Pigment Blue 15: x wherein x is an integer of 1 to 6 with C.I. Pigment Blue 15: 1, C.I. Pigment Blue 15: 3, and C.I. Pigment Blue 15: 6 being preferred pigments.
The content of the copper complex colorant in the ink composition may be properly determined. The copper complex colorant, however, is preferably about 0.1 to 20% by weight, more preferably about 1 to 10% by weight. When the copper complex colorant is a copper complex dye, the content of the copper complex dye is preferably about 0.1 to 20% by weight, more preferably about 1 to 10% by weight. When the copper complex colorant is a copper phthalocyanine pigment, the content of the copper phthalocyanine pigment is preferably about 1 to 10% by weight, more preferably about 2 to 5% by weight.
According to the ink composition of the present invention, the free copper ion concentration is not more than 10 ppm, more preferably not more than 5 ppm. Methods usable for regulating the free copper ion concentration include a method wherein the degree of the purification of the colorant is enhanced, and a method wherein the free copper ion is sequestered by a sequestering agent. Examples of preferred sequestering agents include ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, hydroxyethylethylenediamine-triacetic acid, uramil diacetic acid, and metal salts (for example, sodium salt) of the above compounds.
When the free copper ion concentration falls within the above concentration range, precipitation after the production of the ink can be prevented. In addition, good storage stability, ejection stability, and clogging preventive effect can be attained.
The free copper ion concentration may be measured, for example, by ion chromatography, inductively coupled plasma mass spectroscopy (ICP-MS), or capillary electrophoresis.
When the copper complex colorant is a copper phthalocyanine pigment, the above free copper ion concentration is preferably realized by the addition of EDTA or a metal salt thereof. The amount of EDTA added may be properly determined so that precipitation can be suppressed. The content of EDTA is preferably not less than 20% by weight based on the copper phthalocyanine pigment. Since, however, the addition of EDTA in an excessive amount has a fear of the stability of the ink composition being deteriorated, the upper limit of the amount of EDTA added is preferably determined so that EDTA does not deteriorate the stability of the ink composition. Although the reason why the addition of EDTA can effectively prevent precipitation has not been fully elucidated yet, the reason is believed to reside in that the component derived from the copper phthalocyanine pigment is sequestered by EDTA. The present inventors have found that treating the copper phthalocyanine pigment with EDTA before the addition o
Kanaya Miharu
Oka Kyoichi
Watanabe Kazuaki
Bell Mark L.
Faison Veronica F.
Ladas & Parry
Seiko Epson Corporation
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