Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-04-26
2003-01-28
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S206000, C428S325000, C428S423100
Reexamination Certificate
active
06511736
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording material having a high gloss and an excellent ink jet recording property and to a process for producing the same.
2. Description of the Related Art
The recording system using an ink jet printer is advantageous in that the noise level is low, recording can be effected at a high speed, and multi-colored images can be easily formed, and thus it is widely utilized in various fields. As a recording sheet for the ink jet recording system, woodfree paper sheet having an enhanced ink absorption and coated paper sheets having a porous pigment-containing coating layer are used. Almost all of these conventional paper sheets for the ink jet recording system have a low surface gloss and thus are mat paper sheets. Thus, a new type of recording sheet, having a high gloss and a good appearance, has been demanded for the ink jet recording system.
Generally, as a paper sheet having a high gloss, a high gloss coated paper sheet which is produced by coating a surface of a substrate paper sheet with a coating layer containing a plate-crystalline pigment and optionally applying a calender treatment to the coating layer surface, or a cast-coated paper sheet which is produced by bringing a coating layer formed on a substrate paper sheet surface into contact with a specular surface of a heated casting drum while the coating layer is kept in wetted condition, pressing the wetted coating layer onto the specular surface under pressure, and drying the coating layer to cause the specular surface condition of the casting drum to be transferred to the dried coating layer surface, are known.
The cast-coated sheet exhibits a surface gloss and a surface smoothness higher than those of a conventional coated and calender-finished paper sheet, and thus an excellent printing effect can be obtained on the cast-coated sheet. Thus, the cast-coated paper sheet is mainly used for high class printings. When the conventional cast-coated sheets are utilized for the ink jet recording system, various problems occur.
The conventional cast-coated paper sheet disclosed, for example, in U.S. Pat. No. 5,275,846, has a high gloss obtained by transferring a specular surface condition from a specular surface of a cast coater drum to a coating layer comprising a pigment composition containing a film-forming material such as a binder or adhesive. In this transfer, the film-forming material plays an important role. However, the film-forming material causes the porosity of the resultant coating layer to be lost, and thus the ink absorption of the coating layer to be significantly decreased. To improve the ink absorption, it is important that the cast-coated ink fixing layer is porous and thus can easily absorb the ink. The increase in the porosity of the coating layer causes the film-forming property of the coating layer to be decreased. For this purpose, when the content of the film-forming material in the coating layer is decreased, the gloss of the resultant coating layer is decreased.
Accordingly, it is very difficult to simultaneously make the surface gloss and the ink receiving property of the cast-coated recording sheet satisfactory.
The inventors of the present invention have found, as disclosed in Japanese Unexamined Patent Publication No. 7-89,220 that a cast-coated paper sheet useful for ink jet recording and having both a high gloss and an excellent ink absorption can be produced by coating a surface of a paper sheet having a recording layer comprising as principal components, a pigment and a binder with a coating liquid comprising, as a principal component, a copolymer produced by polymerizing ethylenically unsaturated monomers and having a glass transition temperature of 40° C. or more, to form a coating layer for casting; press-contacting the coating layer for casting with a heated specular surface of a casting drum under pressure while the coating layer is kept in wetted condition; and drying the casted coating layer on the specular surface of the casting drum.
Currently, in the ink jet recording system, the recording speed has been increased, the definition and accuracy of the recorded images have been enhanced, and the full colored image printing has been improved and, thus, an ink jet recording material having a high gloss and being capable of recording thereon colored ink images, having a high clarity and a high color density, is in strong demanded. For example, the ink jet recording material is required to have high gloss and recording quality comparable to those of silver salt type photographic printing sheet. However, at the present, it is difficult to fully meet the above-mentioned requirements even when the above-mentioned technology is utilized.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink jet recording material having a high gloss and capable of recording thereon ink images with a high clarity and a high color density, and a process for producing the same.
The above-mentioned object can be attained by the ink jet recording material, and the process for producing the same, of the present invention.
The ink jet recording material of the present invention comprises a substrate material and a multi-layered ink fixing layer formed on a surface of the substrate material and composed of an outermost ink fixing layer and one or more intermediate ink fixing layers superposed on each other and each comprising a pigment comprising at least one member selected from the group consisting of silica, aluminosilicate, alumina and zeolite, and a binder, wherein
the pigment in each ink fixing layer is in the form of fine secondary particles having an average secondary particle size of 1 &mgr;m or less and each secondary particle is composed of a plurality of primary particles agglomerated with each other to form the secondary particle, and
the outermost ink fixing layer is one formed by a cast-coating procedure.
The process of the present invention for producing the ink jet recording material comprises coating a surface of a substrate material with a multi-layered ink fixing layer composed of an outermost ink fixing layer and one or more intermediate ink fixing layer superposed on each other and each comprising a pigment comprising at least one member selected from the group consisting of silica, aluminosilicate, alumina and zeolite, and a binder, wherein
the pigment for the multi-layered ink fixing layer is in the form of fine secondary particles having an average secondary particle size of 1 &mgr;m or less and each secondary particle is composed of a plurality of primary particles agglomerated with each other to form the secondary particle, and
the outermost ink fixing layer of the multi-layered ink fixing layer is formed by a cast-coating procedure wherein a layer of a coating composition for the outermost ink fixing layer is brought into contact with a heated specular surface of a casting drum under pressure, while the coating composition layer is kept in a wetted condition, and drying the coating composition layer pressed on the heated specular surface of the casting drum.
In the ink jet recording material of the present invention the pigment contained in each ink fixing layer is preferably silica.
In the ink jet recording material of the present invention, at least one undercoat layer comprising a pigment and a binder is optionally formed between the substrate material and the multi-layered ink fixing layer.
In the ink jet recording material of the present invention, a cationic compound having one or more cationic groups per molecule is optionally further contained in at least the outermost ink fixing layer of the multi-layered ink fixing layer.
In the ink jet recording material of the present invention, preferably, the cast-coating procedure for forming the outermost ink fixing layer is carried out by bringing a layer of a coating composition for the outermost ink fixing layer into contact with a heated specular surface of a casting drum under pressure, while the coating composit
Asano Shin-ichi
Mukoyoshi Shun-ichiro
Sunagawa Hirokazu
Arent Fox Kintner & Plotkin & Kahn, PLLC
Kelly Cynthia H.
Oji Paper Co. Ltd.
Shewareged B.
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