Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1999-12-27
2002-06-25
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C427S152000, C427S214000, C428S195100, C428S207000, C428S211100, C428S331000, C428S342000
Reexamination Certificate
active
06410123
ABSTRACT:
BACKGROUND OF THE PRIOR ART
1. Technical Field
The present invention relates to ink jet recording paper and the production thereof and, more particularly, to ink jet recording paper superior in image reproducibility to such an extent that the printed paper can be used for print proofs, having a high-quality, dull-tone glossy appearance and high ink absorbency, thereby being suitable for an ink jet printer of a photo-type that usually discharges a large quantity of ink.
2. Prior Art
Ink jet recording is a method by which fine ink drops are jetted out using any kind of jetting method to form an image on a recording material. Since this method enables a recording apparatus to be operated at high speed and using generally inexpensive apparatus, the use of ink jet recording systems has been spreading rapidly. Along with this, the ink jet recording paper market has become diversified. For instance, there has been in increasing interest in preparing print proofs with an ink jet printer. Previously, these have been prepared using ink and a proof sheet.
More specifically, in the latest full-color ink jet printers, by virtue of the reduction of the ink droplets to microscopic size, the use of photo inks containing small content of dye, and etc., a printer, which can realize image qualities comparative to those of silver salt films only when a specific paper is used, has appeared in the market.
In the general art of printing, papers having different levels of glossiness are used, depending on the required appearance of the finished prints. For instance, cast coated paper (gloss type), art paper (semi-gloss type), dull-art paper (dull-tone type), coated paper, slightly coated paper, free sheet (matte type), etc. are used for various applications. Similarly, papers for use in proofreading prints must have varying levels of glossy appearance, as the printing papers do. However, conventional recording paper for use in ink jet printers is classified into either gloss types of high gloss or matte types of almost no gloss.
With regard to the conventional techniques for obtaining glossy ink jet recording papers, Japanese Tokkai Hei 7-101142/1995 (the term “Tokkai” as used herein means an “unexamined published patent application”) discloses a process for obtaining an ink jet recording paper with glossiness of not less than 25% in terms of 75 degree specular one by forming a layer of colloidal particles having a diameter of not more than 300 nm on the ink-receiving layer. Japanese Tokkai Hei 9-183265/1997 discloses forming two or more of ink-receiving layers containing colloidal silica and binder on the support. Japanese Tokkai Hei 3-215080/1991, 3-256785/1991, 7-89220/1995 and 7-117335/1995 disclose forming two or more ink-receiving layers the topmost layer of which functions as a gloss-developing layer.
These conventional techniques have a general object aimed to obtain products with a considerably high level of gloss similar to that of photographs and prints printed on art coated paper or cast coated paper. For this end, a film is usually used, a casting or transferring process which easily produces high gloss is commonly employed for finishing, or the coverage of colloidal silica is generally greatly increased.
Further, the ink jet recording paper disclosed in Japanese Tokkai Hei 9-183265, which has two or more of ink-receiving layers formed on the support, each containing colloidal silica and binder, is expensive and exhibits crazing problems because the colloidal silica layer positioned near the support contains a binder and is therefore very thick.
At all cases, in order to impart a glossy appearance, it is necessary to use small particle size pigments such as colloidal particles of silica and the like together with a binder. However, the use of spherical colloidal particles causes a drawback in that the speed at which ink is absorbed is lowered because the volume of voids formed between these particles decreases when a layer of the particles is formed. Further, colloidal silica in itself has no voids of the type that synthesized amorphous silica has. Accordingly, when using colloidal silica, a thick-coated ink-receiving layer is needed in order to attain the required ink-absorptive volume. However, forming such a thick ink-receiving layer often induces a powder-detaching phenomenon. Powder detachment can be prevented by increasing the amount of binder, but then the absorbing speed decreases, especially on the surface, causing a bleeding phenomenon. As a result, high-resolution prints cannot be obtained.
On the other hand, it is known that the sheet absorbs ink faster as the volume of the voids contained in the ink-receiving layer increases, and that a large volume of ink can be absorbed when the pigment contained in the ink-receiving layer has large specific surface area. Accordingly, pigments having large specific surface area and large particle diameter of not less than several &mgr;m such as synthetic amorphous silica prepared by agglomerating small primary particles of synthetic silica are generally used. However, an ink jet recording paper containing these pigments has almost no gloss. Accordingly, it belongs to so called “matte type”. Thus, using conventional processes, one cannot prepare an ink jet recording paper with a moderately glossy appearance, such as a light coated paper and a dull-tone ink jet recording paper, without calendar finishing.
Moreover, it is becoming increasingly common to bulletin or store papers with high quality recording images for a long period of time. As a result, there is an increasing need to improve the light resistance of the image. Ways and means for improving the light resistance of images formed with dye-containing ink have been proposed such as: adding a UV light-absorbing agent of benzophenone, benzotriazole and other types to an ink jet recording paper (see Japanese Tokkai Sho 57-87988/1982, 63-222885/1988); combining zinc oxide powder with cationic resinous additive (see Japanese Tokkai Hei 7-32725/1997); adding an alkyl- or acetyl-substituted, or unsubstituted hindered amine compound (see Japanese Tokkai Sho 61-146591); and etc. However, sufficient light resistance of images still has not been attained.
3. Problems Encountered
Therefore, an object of the present invention is to provide an ink jet recording paper having good ink absorbency so that bleeding is prevented, so that the paper is capable of producing prints having high color density and excellent color reproducibility, even when the paper is printed using the latest high-resolution photo quality ink jet printer. In addition, it is an object to provide an ink jet recording paper with a moderately glossy appearance, such as a light coated paper and a dull-tone ink jet recording paper without calendar finishing, which means the paper has a dull or moderately glossy appearance, wherein the paper is capable of producing print proofs and is capable of forming light-resistant image. It is further desirable to provide a process for making such a paper.
SUMMARY OF THE INVENTION
An essential feature of the present invention resides in an ink jet recording paper comprising a ink-receiving layer and at least two colloidal silica layers successively coated onto a support, each of said colloidal silica layers comprising chain colloidal silica as a main ingredient, wherein at least the colloidal silica layer contacting the ink-receiving layer contains no binder and has a coverage of about 1 to 3 g/m
2
, and the coverage of other colloidal silica layer is about 1 to 6 g/m
2
.
Especially, by setting the 75 degree specular gloss of the surface of the colloidal silica layers for not less than 10% and not more than about 60%, and the 20 degree specular gloss of the same surface for not more than about 10%, concurrently with incorporating cationic chain colloidal silica into at least the topmost colloidal silica layer, excellent ink jet recording paper can be obtained. An ink jet recording paper with high 75 degree specular gloss can be obtained by calendering the ink-receiving layer before applying the
Chatani Akinobu
Iimori Yoshifumi
Kondo Noboru
Kuroyama Yoshihiro
Ono Atsushi
Gary C. Cohn PLLC
Hess Bruce H.
Nippon Paper Industries Co. Ltd.
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