Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-07-13
2003-04-08
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C008S625000, C008S632000, C423S327100, C423S332000
Reexamination Certificate
active
06544631
ABSTRACT:
DETAIL DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-soluble dye fixing agent which can be used in an ink jet recording medium to form a recorded image using water-color ink containing a water-soluble dye and to an ink jet recording medium comprising the same. Particularly, it relates to a dye fixing agent for ink jet recording media which is excellent in the fixability of water-color ink and the resolution, water resistance and light resistance of an image recorded on an medium and to an ink jet recording medium comprising the same.
2. Description of the Prior Art
Along with progress made in personal computers and digital cameras, displayed images have been recorded on printing paper like silver salt-based photographs. An image forming system called “ink jet recording system” is known as a system for recording such displayed images. Since this ink jet recording system has various features such as little noise, high-speed recording, easy for multi-color recording, wide adaptability of a recorded pattern and the elimination of need for development and fixing, it is used in many fields.
The principle of the ink jet recording system is that an ink solution is ejected from a nozzle by a drive source such as electric field, heat or pressure and transferred to the accepting layer of printing paper. The ink solution comprises a dye, water, polyhydric alcohol and the like and a water-soluble substantive dye or acidic dye is mainly used as the dye.
The printing paper is constructed by forming a dye accepting layer on a substrate and coated paper, glossy paper, glossy film, OHP film or the like is used as the substrate according to various needs. The accepting layer comprises a water-soluble polymer having excellent affinity for a dye, organic or inorganic filler and other auxiliary substances whose blending ratio is suitably adjusted to control the permeability of the dye and to suppress a blurred image.
Images obtained by this ink jet recording system now have high definition and as high quality as that of a silver-base photograph at a visible range thanks to recent marked progress made in the quality of the images and the improvement of dot density and the glossiness of the accepting layer.
JP-A 61-135785 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”) (JP-B 4-15747) (the term “JP-B” as used herein means an “examined Japanese patent publication”) proposes that the light resistance of a substrate is improved by using synthetic silica and a hydrotalcite consisting of only a carbonic acid ion as a divalent anion in a dye accepting layer.
PROBLEMS TO BE SOLVED BY THE INVENTION
The substantive dye or acidic dye contained in the ink solution used in the ink jet system is retained in the accepting layer by interaction such as van der Waals binding force and hydrogen bond with the constituent components of the accepting layer after it has been transferred to the accepting layer as shown by the dyeing theory of dyes. Therefore, when an image formed on the accepting layer is contacted to a solvent or resin having high affinity for the dye or when heat energy large enough to cancel the interaction is supplied, the elution or transfer of the dye is induced, thereby causing such inconvenience as a blurred image. That is, the dye transferred to the accepting layer does not show completely stable fixability like a silver salt-based photograph. The same is said of stationery using a substantive dye or acidic dye and general image forming materials used for printing and the like.
Means for Solving the Problems
To cope with this, the inventors of the present invention have conducted studies to develop a fixing agent capable of stably fixing a dye in the water-color ink accepting layer of an ink jet recording medium having a water-color ink accepting layer formed on a substrate. That is, the inventors have conducted studies to develop a fixing agent which prevents the elution or transfer of a dye even when it is contacted to a solvent or resin having high affinity for the dye or when heat is supplied to the dye after the dye is transferred to the accepting layer and fixed.
The inventors have paid attention to a hydrotalcite compound as a fixing agent, synthesized various hydrotalcite compounds and investigated the dye fixing stabilities of the compounds.
As a result, they have found that the type of a metal and the type of an anion(s) forming a hydrotalcite compound are closely related to dye fixing stability and that a hydrotalcite compound containing metal lithium and having both a silicic acid anion and a sulfuric acid ion, or a silicic acid anion as an anion(s) has extremely stable dye fixability. It has also been found that when this hydrotalcite compound is used as a fixing agent, a high-definition image recording medium can be obtained. It has further been discovered that the hydrotalcite compound containing a silicic acid anion and a sulfuric acid ion, or a silicic acid anion as an anion(s) in a predetermined amount and having specific pore characteristics has more stable fixability.
According to the present invention, there is provided a dye fixing agent for water-color ink to be contained in the water-color ink accepting layer of an ink jet recording medium having a water-color ink accepting layer formed on a substrate, which is a hydrotalcite compound represented by the following formula (I):
LiAl
2
(OH)
6
(A
1
n−
)
c
(A
2
m−
)
d
.z
H
2
O (I)
wherein A
1
n−
is a silicic acid anion having a valence of n and a sulfuric acid ion (SO
4
2−
), or a silicic acid anion having a valence of n, with the proviso that the silicic acid anion having a valence of n is an anion selected from the group consisting of SiO
3
2−
, HSiO
3
−
, Si
2
O
5
2−
and HSi
2
O
5
−
, A
2
m−
is an anion selected from the group consisting of CO
3
2−
, NO
3
−
, Cl
−
and OH
−
, z satisfies 0<z<4, and c and d satisfy 0.5<nc+md<1.1.
According to the present invention, there is further provided an ink jet recording medium which comprises a hydrotalcite compound containing the above specific anion(s) as a dye fixing agent.
The dye fixing agent for water-color ink and the ink jet recording medium comprising the same of the present invention will be described in detail hereinbelow.
The hydrotalcite compound used as the dye fixing agent for water-color ink of the present invention is characterized in that it contains metal lithium and a silicic acid anion and a sulfuric acid ion, or a silicic acid anion as an anion(s) forming the compound. More specifically, the hydrotalcite compound is more advantageously a hydrotalcite compound which contains a silicic acid anion and a sulfuric acid ion, or a silicic acid anion in an amount of 10 to 98 mol %, preferably 20 to 98 mol % based on the total of all the anions.
The silicic acid anion is SiO
3
2−
, HSiO
3
31
, Si
2
O
5
2−
or HSi
2
O
5
−
and the sulfuric acid ion is SO
4
2−
.
When the hydrotalcite compound used in the present invention contains a silicic acid anion and a sulfuric acid ion as anions, it contains the silicic acid anion in an amount of 5 to 100 mol %, preferably 10 to 100 mol %, particularly preferably 20 to 100 mol % based on the total of the silicic acid anion and the sulfuric acid ion.
It is advantageous that the hydrotalcite compound used in the present invention should have an average particle diameter measured by a laser diffraction scattering method of 0.1 to 10 &mgr;m, preferably 0.5 to 10 &mgr;m.
The hydrotalcite compound used in the present invention is represented by the following formula (I):
LiAl
2
(OH)
6
(A
1
n−
)
c
(A
2
m−
)
d
.z
H
2
O (I)
wherein A
1
n−
is a silicic acid anion having a valence of n and a sulfuric acid ion (SO
4
2−
), or a silicic acid anion having a valence of n, with the proviso that the silicic acid anion having a valence of n is an anion selected from the group consisting of SiO
Okada Akira
Tanaka Kanako
Hess Bruce H.
Kyowa Chemical Industry Co. Ltd.
Sherman & Shalloway
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