Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Particulate matter
Reexamination Certificate
2000-01-21
2003-12-30
Hess, B. Hamilton (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Particulate matter
C106S031010, C106S499000, C428S032340
Reexamination Certificate
active
06670037
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to inkjet-printing materials as recording mediums and coating agents therefor, more particularly a coating agent for inkjet-printing materials providing excellent reproducibility of colors and capable of forming thereon a definite, i.e., clearly defined and certain, image having a high resistance to weathering including a high resistance to water and light, and which is free of an irritating odor due to acetic acid. The present invention also relates to the inkjet-printed material made by using the coating agent and also free of the irritating odor.
2. Description of Related Art
Hitherto, as a base material for image-printing materials, there have been employed, for example, various materials made from papers, plastic, metals, glasses, ceramics, leathers and woods. Furthermore, these printed base materials are of various forms, i.e., may be various films, sheets, flat plates, articles having a curved surface or irregular surface, woven fabrics, non-woven fabrics and foams.
As inkjet-printing base materials used in an inkjet printer there have been generally employed materials having ink-receptive layers formed on the opposite sides thereof by applying thereto a treating agent containing a cationic polymer. The cationic polymer-containing treating agent should be capable of rapidly absorbing the water content of aqueous inks and firmly fixing printed inks on printing base materials, thus preventing the printing base materials treated with the treating agent from being stained with ink just after printing.
Nevertheless, however, the above-mentioned treating agent in the ink-receptive layer applied on the inkjet-printing base materials is highly soluble in water. Therefore, with the above-mentioned treating agent there is such a problem that the printed base materials become stained with ink when the images printed on the ink-receptive layers are brought into contact with water.
In order to solve this problem, some proposals have been made, i.e., it has been proposed that a porous material be added to the cationic polymer-containing treating agent applied to the printing base material forming the ink-receptive layer (see JP Patent Unexamined Application Nos. S60-245588A, H7-2430B and H3-275378A). Of these, JP S60-245588A discloses an inkjet-printing base material having at least one ink-receptive layer formed thereon, said ink-receptive layer containing a porous alumina xerogel having pores of 40 to 1,000 Å in radius. JP Patent Unexamined Application No. H7-2430B discloses a recording sheet comprising a transparent base having a porous ink-receptive layer formed thereon, said ink-receptive layer being mainly comprised of pseudo-boehmite and containing pores of 100 to 1,000 Å in radius, and the total volume of the pores in the layer being 0.1 cc/g or less.
The printing materials provided with the porous material-containing ink-receptive layers can absorb the water and solvent contents of the ink into the specified pores of the porous material. Thus, the printed materials can be prevented from being stained with the ink, thereby improving the quality, such as a color density and coloring property, of images.
However, with the printing materials provided with porous material-containing ink-receptive layers problems have often occurred due to the poor dispersibility of the porous material. That is, a coating liquid comprising the porous material and an adhesive is easily gelled, hard to apply uniformly onto the base of the printing material, the applied ink-receptive layers are easily cracked when dried, or eventually printed materials are easily stained with ink, not providing any definite images.
In order to solve these problems, JP Patent Unexamined Application No. H4-67985A proposes a coating agent comprising an alumina sol containing a monocarboxylic acid such as acetic acid and a water-soluble polymer binder added thereto, and a printing sheet comprising a polyethyleneterephthalate(PET) film having the coating agent applied thereon. However, the coating agent mentioned above has a problem of the monocarboxylic acid emitting an irritating odor. Furthermore, the printing sheet also has the same problem of emitting the irritating odor, which is uncomfortable and unpleasant to users.
In addition, JP Patent No. 2714350 proposes a printing base material provided thereon with an ink-receptive layer by a dispersion of an alumina hydrate containing 0.1 to 1.0 wt % of a nitrate group and having a pore radius distribution having maximal values within less than 100 Å and between 100 Å and 200 Å. However, the nitrate group contained in the dispersion mentioned above is only an impurity of the alumina hydrate. Therefore, use of the dispersion mentioned above does not solve the problem of the printing material provided with the porous material-containing ink-receptive layer.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a coating agent for producing an inkjet-printing material free of an irritating odor, which coating agent is good in dispersing alumina and applied to a base such as paper and plastic films.
Another object of the present invention is to provide an inkjet-printing material which is free of an irritating odor and good in reproducibility of colors, has a high resistance to water and weathering, and provides definite images thereon.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
In accordance with the present invention, the coating agent is an alumina dispersion comprising alumina dispersed in an aqueous dispersing medium, aluminium nitrate and a binder. The present invention is different from the invention disclosed in said JP Patent 2714350 on the point of view that the coating agent in the present invention contains not alumina hydrate but alumina and aluminium nitrate and ink-receptive layer contains not alumina but alumina hydrate and not contains aluminium nitrate.
In a preferred embodiment of the coating agent of the present invention, the alumina is substantially &dgr;-alumina having an average primary particle size of 5 to 100 nm, the amount of aluminium nitrate added is within the range of 0.1 to 10 parts by weight based on 100 parts by weight of alumina, particularly &dgr;-alumina.
In accordance with the present invention, an ink-receptive layer is provided on the base material by applying the coating agent mentioned above onto the base to thereby produce the inkjet-printing material.
I. COATING AGENT
The coating agent of the present invention is described below.
Each of the alumina dispersion and the binder used in the coating agent of the present invention is described below.
1-1 Alumina Dispersion
The alumina dispersion comprises an aqueous dispersing medium containing alumina dispersed therein, and aluminium nitrate.
(1) Alumina
The alumina may be anhydrous aluminum oxide or hydrous aluminum oxide.
The anhydrous aluminum oxide may be &agr;-alumina, &bgr;-alumina, &ggr;-alumina &dgr;-alumina, &thgr;-alumina or &khgr;-alumina.
The hydrous aluminum oxide may be an alumina hydrate such as boehmite, pseudboemite, gibbsite, bayerite, norstrandite, diaspore, toedite, alumina gel, which may be called “aluminum hydroxide”.
In the present invention, “aluminas” includes “anhydrous alumina” and “alumina hydrates”, if not specified.
Of the aluminas, for example, an alumina is preferably made by a vapor phase process, i.e., by hydrolyzing a gaseous metal chloride in the presence of water produced in the oxygen-hydrogen reaction at the temperature specific to the oxygen-hydrogen reaction, more specifically &dgr;-alumina.
One or more of the alumina may be used in the coating agent of the present invention.
The alumina is desirably used in a powder form. The alumina particles in powdery form have an average primary particle size of preferably 5 to 100 nm, particularly preferably 5 to 50 nm. When the average primary particle size is in this range, the dispersion of the alumina is much better. The average primary particle size
Kodera Toshihiro
Mouri Hidemasa
Okura Kousuke
Browdy and Neimark , P.L.L.C.
Hess B. Hamilton
Taiho Industries Co. Ltd.
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