Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-08-09
2004-11-30
Brooke, Michael S. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C106S031600
Reexamination Certificate
active
06824262
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink set comprising at least inks of the three colors yellow, magenta and cyan, special inks of colors other than these three colors, and a reaction liquid containing a reactant, and more particularly to a pigment ink set and an ink jet recording method using this pigment ink set.
2. Description of the Related Art
Pigment inks are generally superior to dye inks in terms of the image fastness of printed articles, and are used in various applications that utilize this characteristic, for example as inks for wide format color ink jet recording aimed at the sign and display markets. In such color ink jet recording, normally a variety of hues are rendered by using a 3-color ink set comprising water-based pigment inks of the three colors yellow (Y), magenta (M) and cyan (C), which are the three primary colors for subtractive colormixing, or else a 4-color ink set in which black (K) is added to this 3-color ink set. Moreover, as ink sets having a broader color reproduction range than such 3-color and 4-color ink sets, ink sets have been proposed that contain water-based inks of colors such as orange and green in addition to the YMCK inks.
Moreover, with regard to improving the ink jet recording method using such a conventional ink set, an ink jet recording method in which a reaction liquid containing a reactant that acts to agglomerate the inks is used, i.e. a so-called two-liquid (inks plus reaction liquid) ink jet recording method, is known (see, for example, Japanese Patent Application Laid-open No. H9-286940, Japanese Patent Application Laid-open No. H10-120956 and International Patent Application Publication No. WO 99/05230). According to this two-liquid ink jet recording method, through the reaction liquid and an ink coming into contact with one another on a recording medium, the reaction liquid breaks down the dispersed state of an ink component such as a pigment, thus agglomerating the ink component to form an agglomerate on the recording medium, and hence a high-quality printed article with high color density and little blotting or unevenness can be obtained. With this two-liquid ink jet recording method, adequate coloring can be realized with regular paper, for which conventional ink jet recording methods have been inadequate, and hence the two-liquid ink jet recording method is particularly effective in the case that regular paper is used as the recording medium.
With the two-liquid ink jet recording method used up to now, a water-based reaction liquid is fired onto the recording medium in addition to the water-based inks, and hence the amount of water-based liquid fired onto the recording medium per unit area is greater than in the case of an ink jet recording method using a regular ink set not containing the reaction liquid. However, regular paper used as the recording medium is such that if a large amount of water comes into contact therewith, then hydrogen bonds between the cellulose fibers are broken at the parts where the water contacts the paper, and hence expansion occurs at these parts, causing deformation such as wrinkling. There has thus been a problem that, in the case that regular paper is used as the recording medium, the two-liquid ink jet recording method described above causes deformation such as wrinkling of the regular paper. The wrinkling becomes worse in particular at printed parts of secondary or higher order colors (mixed color parts) where the ink firing amount is high, greatly reducing the image quality of the printed article. The problem of wrinkling can be resolved by reducing the firing amount of the inks and the reaction liquid, but if the firing amount is reduced then the coloring ability drops.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide an ink set and an ink jet recording method using the ink set, according to which a high-quality printed article can be provided for which deformation such as wrinkling does not occur, the color density is high, and there is little blotting or unevenness even if regular paper is used as the recording medium.
The present inventors carried out various studies into an ink jet recording method using an ink set comprising pigment inks of the three colors yellow, magenta and cyan and a reaction liquid containing a reactant, i.e. the so-called two-liquid ink jet recording method, and as a result discovered that if a pigment ink set is used that further comprises, in addition to the above, as special inks two pigment inks that have a hue angle ∠H° as defined in CIELAB color space on a recording medium in a specified range, then when forming mixed color parts of secondary or higher order colors, due to using the special inks, characters and/or images with high coloring can be formed without firing a large amount of the inks, which would cause wrinkling with regular paper.
The present invention is based on the above finding, and attains the above object by providing an ink set comprising at least: inks of three colors, that is a yellow ink having a hue angle ∠H° as defined in CIELAB color space on a recording medium in a range of approximately 80° to approximately 110°, a magenta ink having the above-mentioned hue angle ∠H° in a range of approximately 330° to approximately 360°, and a cyan ink having the above-mentioned hue angle ∠H° in a range of approximately 230° to approximately 260°; undermentioned ink (A) and/or undermentioned ink (B); and a reaction liquid containing a reactant.
Ink (A): An ink having the above-mentioned hue angle ∠H° in a range of approximately 0° to approximately 80°.
Ink (B): An ink having the above-mentioned hue angle ∠H° in a range of approximately 260° to approximately 330°.
[The above-mentioned hue angle ∠H° is tan
−1
(b*/a*)+180° in the case that a*<0 and tan
−1
(b*/a*)+360° in the case that a*>0. a* and b* represent the perceived chromaticity indices as defined in CIELAB color space.]
Note that in the present invention, a glossy recording medium such as PM photographic paper (made by Seiko Epson Corporation) is used as the ‘recording medium’ when ‘CIELAB color space on a recording medium’ is mentioned.
Moreover, the present invention provides an ink set comprising: a yellow ink having an absorption spectrum with an absorption area over 400 nm to 500 nm in a range of 30 abs·nm to 350 abs·nm; a magenta ink having an absorption spectrum with an absorption area over 500 nm to 600 nm in a range of 20 abs·nm to 200 abs·nm; a cyan ink having an absorption spectrum with an absorption area over 600 nm to 700 nm in a range of 50 abs·nm to 400 abs·nm; undermentioned ink (A) and/or undermentioned ink (B); and a reaction liquid containing a reactant.
Ink (A): An ink having an absorption area over 500 nm to 600 nm equal to or greater than the absorption area over 500 nm to 600 nm of the above-mentioned magenta ink.
Ink (B): An ink having an absorption area over 500 nm to 600 nm equal to or greater than the absorption area over 600 nm to 700 nm of the above-mentioned cyan ink.
Moreover, the present invention provides an ink set comprising: a yellow ink having an absorption spectrum with an absorption area over 400 nm to 500 nm in a range of 30 abs·nm to 350 abs·nm; a magenta ink having an absorption spectrum with an absorption area over 500 nm to 600 nm in a range of 20 abs·nm to 200 abs·nm; a cyan ink having an absorption spectrum with an absorption area over 600 nm to 700 nm in a range of 50 abs·nm to 400 abs·nm; undermentioned ink (A) and/or undermentioned ink (B); and a reaction liquid containing a reactant.
Ink (A): An ink such that the absorption area over 400 nm to 500 nm of ink (A) is in a range of 0.5 times to 2.0 times the absorption area over 500 nm to 600 nm of ink (A).
Ink (B): An ink such that the absorption area over 500 nm to 600 nm of ink (B) is in a range of 0.5 times to 5.0 times the absorption area over 600 nm to 700 nm of ink (B).
Moreover, the present invention attains the above object by p
Kataoka Shuichi
Kubota Kazuhide
Takemoto Kiyohiko
Brooke Michael S.
Ladas & Parry
Seiko Epson Corporation
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