Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2001-05-21
2003-07-22
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S206000, C428S331000, C428S701000, C548S257000
Reexamination Certificate
active
06596378
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a recording medium and an aqueous ink composition which each provide an image excellent in light fastness and gas fastness and preservable for an extended period of time and, more particularly, to a recording medium and an aqueous ink composition suitable to ink jet recording.
BACKGROUND OF THE INVENTION
With the recent innovative development in ink jet recording technology, the quality of images output on a recording medium ink jet recording has been increasing, easily standing comparison with silver salt photographic images. However, dyes, which are colorants used to form high-quality images on a recording medium, are susceptible to deterioration by light, such as ultraviolet light and visible light, and oxidizing gases, such as ozone, NO
x
, SO
x
, H
2
S, etc. That is, they have poor light fastness and gas fastness. Therefore, the image recorded in ink comprising a dye as a colorant (hereinafter referred to as dye ink) exhibits, of necessity, poor fastness to light and gas and undergoes discoloration (color change and fading) with time even when kept from intense light, for example, when preserved indoors, still more when exposed to intense light. In other words, the image has poor indoor preservability and is inferior in this respect to silver salt photographs.
On the other hand, recording media for ink jet recording include a so-called swelling type which has an ink receiving layer mainly comprising a polymer, such as polyvinyl alcohol, and a so-called void type (also called absorbing type) which has an ink receiving layer mainly comprising fine porous particles of a pigment, such as amorphous silica, and a binder. Those two types differ in degree of deterioration of the dye caught in the ink receiving layer. When an image is recorded on a swelling type recording medium by ink jet recording using dye ink, the dye is buried in the polymer of the ink receiving layer so that it undergoes little discoloration due to air-mediated deterioration, for example, discoloration by air oxidation and air mediated photodeterioration (generation of single state oxygen and resultant decomposition of a dye). On the other hand, when a void type recording medium is recorded by ink jet recording in dye ink, the ink receiving layer, which has a vast number of pores, allows the dye to come into contact with air. It follows that the dye is susceptible to air-mediated deterioration and apt to undergo discoloration. Hence, the problem of air-mediated deterioration of dye is inherent to void type recording media.
It is known that preservability (indoor preservability) of an ink image formed on a recording medium can be improved by incorporating a benzotriazole ultraviolet (UV) absorber into the ink or the recording medium. However, a benzotriazole UV absorber should be added in a large quantity to manifest a sufficient effect. Besides, addition of a benzotriazole UV absorber to a recording medium tinges the recording medium with yellow and is therefore impractical.
JP-A-9-1922 proposes, incorporating a benzotriazole compound different from the above-described benzotriazole UV absorbers into an ink receiving layer. This method aims to present a solution to the problem, which is specific to a swelling type recording medium having an ink receiving layer containing gelatin as a main component, that the image is liable to get uneven in density to have reduced resolving power when allowed to stand open for a long time. There has been made no proposals as to a method for preventing air mediated dye deterioration which occurs specifically to a void type recording medium thereby to provide an image with improved preservability.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a recording medium and an aqueous recording ink composition capable of providing an image which exhibits excellent fastness to light and gas and is prevented from air-mediated dye deterioration specific to a void type recording medium, particularly capable of providing an image which can be preserved indoors for an extended period of time without substantial discoloration.
Other objects and effects of the present invention will become apparent from the following description.
As a result of extensive investigation, the inventors of the present invention found that air-mediated dye deterioration inherent to a void type recording medium can be prevented to improve indoor image preservability (i.e., light fastness and gas fastness) by incorporating a benzotriazole compound having a specific structure into an ink receiving layer of a recording medium and/or a dye ink composition used for recording.
The present invention is based on this finding.
That is, the above described objects of the present invention have been achieved by providing the following recording media, aqueous ink compositions, and ink jet recording methods.
1) A recording medium having an ink receiving layer comprising a porous pigment and a binder, wherein said ink receiving layer contains at least one benzotriazole compound represented by formula (I):
wherein R represents a hydrogen atom or an alkyl group; X represents a hydrogen atom, a sodium atom, a potassium atom or a primary, secondary or tertiary amino group.
2) The recording medium according to item 1) above, wherein said benzotriazole compound comprises at least one of benzotriazole, benzotriazole sodium salt, 4-methylbenzotriazole, 4-methylbenzotriazole sodium salt, and a benzotriazole amine salt.
3) The recording medium according to item 1) or 2) above, wherein said benzotriazole compound is present in a total amount of 0.01 to 5% by weight based on the weight of said ink receiving layer.
4) The recording medium according to any one of items 1) to 3) above, wherein said porous pigment is a silica pigment.
5) The recording medium according to any one of items 1) to 4) above, which is used for ink jet recording
6) An aqueous ink composition comprising a colorant, water, and 0.01 to 2% by weight of at least one benzotriazole compound represented by formula (I):
wherein R represents a hydrogen atom, or an alkyl group; X represents a hydrogen atom, a sodium atom, a potassium atom or a primary, secondary or tertiary amino group.
7) The aqueous ink composition according to item 6) above, wherein said benzotriazole compound comprises at least one of benzotriazole, benzotriazole sodium salt, 4-methylbenzotriazole, 4-methylbenzotriazole sodium salt, and a benzotriazole amine salt.
8) The aqueous ink composition according to item 6) or 7) above, wherein said colorant is a dye.
9) The aqueous ink composition according to item 8) above, wherein said dye is represented by formula (II):
wherein X represents anilino group substituted by at least one SO
3
M group, Y represents OH, Cl or a morpholino group, and M represents a member selected from H, Ti, Na, K, ammonium and organic amines.
10) The aqueous ink composition according to any one of items 6) to 9) above, which is used for ink jet recording.
11) The aqueous ink composition according to any one of items 6) to 10) above, which is used for forming an image on a recording medium having an ink receiving layer comprising a porous pigment and a binder.
12) An ink jet recording method comprising forming an image on a recording medium according to any one of items 1) to 5) above with an aqueous ink composition containing a dye represented by formula (II):
wherein X represents anilino group substituted by at least one SO
3
M group, Y represents OH, Cl or a morpholino group, and M represents a member selected from H, Li, Na, K, ammonium and organic amines.
13) An ink jet recording method comprising ejecting a droplet of an aqueous ink composition according to any one of items 6) to 11) above to attach the ejected droplet onto a recording medium, thereby performing printing.
DETAILED DESCRIPTION OF THE INVENTION
The recording medium according to the present invention is classified into a void type in which the ink receiving layer comprises a porous pigment and a binder. The ink receiving layer further co
Hanmura Masahiro
Hayashi Hiroko
Kanaya Miharu
Onishi Hiroyuki
Kelly Cynthia H.
Seiko Epson Corporation
Shewareged B.
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