Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-12-28
2003-03-11
Hess, Bruce H. (Department: 1774)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C428S195100
Reexamination Certificate
active
06531017
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming method which can provide color images that are superior in gradation reproducibility and dot reproducibility, including variable performance, color superposing property and color clearness, and that also have high recording density. The present invention also relates to a transfer sheet used in such a method.
In a conventional thermal transferring recording system using a colored ink layer that is fused by heat, ink located other than dots is also fused (or softened) by the diffusion of heat generated from a heating resistor element (dot). As a result, ink transfer occurs at portions that need not be subjected to the transferring process, which, in turn, causes problems of unstable dot shapes and irregular gradations.
In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide a color image forming method and a transfer sheet used in such a method, which can achieve color images that are superior in gradation reproducibility, dot reproducibility, color superposing property and color clearness, and also have high recording density, when used in a thermal transfer color printer.
This and other objects of the present invention will become apparent from the description hereinafter.
SUMMARY OF THE INVENTION
The present invention provides (1) a color image-forming method, comprising the steps of:
using a transfer sheet comprising a foundation, and a release layer and a colored ink layer stacked in this order on one side of the foundation wherein the release layer is capable of being fused or softened by heat at the time of a thermal transferring process and the colored ink layer is incapable of being softened by heat at the time of the thermal transferring process; and an image receiving body having at least a surface layer capable of being fused or softened by heat at the time of the thermal transferring process,
superposing the colored ink layer of the transfer sheet onto the image receiving body and heating the transfer sheet/image receiving body from the transfer sheet side to form a color image on the image receiving body,
wherein, in the case of a transferring process for a first color, the colored ink layer is transferred by allowing the image-receiving body side to be fused or softened so as to exert adhesive property; and in the case of a transferring process of a second color or a subsequent color, with respect to a monocolor portion of the second color or the subsequent color, in the same manner as the first color, the colored ink layer is transferred by allowing the image-receiving body side to be fused or softened so as to exert adhesive property, and with respect to an overlapped area on at least one of the first color, the second color and the subsequent color which have been transferred, the colored ink layer for the second color or the subsequent color is transferred by allowing a release layer component on the top of a printed image of at least one of the first color, the second color or the subsequent color to be fused or softened to exert adhesive property.
The present invention further provides (2) a transfer sheet for use in the color image forming method according to the above (1), wherein the colored ink layer incapable of being softened by heat at the time of the thermal transferring process comprises a binder and a pigment as its essential components, the binder comprising a substance incapable of being softened by heat at the time of the thermal transferring process, the pigment comprising 30 to 90% by weight of the colored ink layer, the thickness of the colored ink layer being in the range of 0.05 to 0.5 &mgr;m.
The present invention further provides (3) the transfer sheet according to the above (2), wherein the release layer capable of being fused or softened by heat at the time of the thermal transferring process comprises an organic polymer having a softening point of 50° to 170° C. and fine particles.
The present invention further provides (4) the transfer sheet according to the above (3), wherein the organic polymer and the fine particles comprise 70 to 10% by weight and 30 to 90% by weight, respectively, of the release layer and the thickness of the release layer is in the range of 0.02 to 0.5 &mgr;m.
DETAILED DESCRIPTION
The inventors of the present invention have studied intensively to achieve the above-mentioned objects and found that when a transfer sheet having a foundation on one side of which a release layer that is thermally fused or softened and a colored ink layer that is not softened by heat at the time of a thermal transferring process are stacked in this order, and an image-receiving body having at least a surface layer that is fused or softened by heat at the time of the thermal transferring process are used in a combined manner, it becomes possible to achieve a high density recording that provides superior dot reproducibility, gradation reproducibility, color superposing property and color clearness of the first color, the second color and subsequent color, thereby completing the present invention. The following description will discuss the present invention in detail.
In the thermal transfer method of the present invention, in the case of the transferring process of the first color ink layer, different from the conventional thermally fusible transfer ink layer, the first color ink layer is not fused or softened at the time of the thermal transferring process, and the image-receiving body side is allowed to be fused or softened so as to be bonded to the ink layer. Thus, the first color ink is transferred to form a first color printed image. In the case of the transferring process of the second color ink layer, with respect to a monocolor portion of the second color, in the same manner as the first color, the second color ink is transferred by allowing the image-receiving body side to be fused or softened so as to exert adhesive property, and with respect to an overlapped area on the first color printed image, the second color ink is transferred by allowing the release layer component on the top of the first color printed image to be fused or softened so as to exert adhesive property. Thus, the second color ink is transferred to form a second color printed image. In the case of the transferring process of the third color ink layer, with respect to a monocolor portion of the third color, in the same manner as the first color, the third color ink is transferred by allowing the image-receiving body side to be fused or softened so as to exert adhesive property, and with respect to an overlapped area on the first color printed image and/or the second color printed image, the third color ink is transferred by allowing the release layer component on the top of the first color printed image and/or the second color printed image to be fused or softened so as to exert adhesive property. Thus, the third color ink is transferred to form a third color printed image. In the case of the ink layer transferring process of the fourth color and subsequent color, the transferring process is carried out in the same manner as the third color. Normally, the first color, the second color and the third color are selected from yellow, magenta and cyan, and black is used as fourth color.
In this method, the colored ink layers of the respective colors are not fused so that dot shapes are stabilized, and it becomes possible to achieve high density recording that provides superior dot reproducibility and gradation reproducibility including a variable performance and color clearness, etc. Here, the variable performance refers to a performance wherein an ink can be transferred at a predetermined area in accordance with a so-called variable dot in which a heat-generation area is variable by adjusting the energy application to the heating resistor element of a thermal head.
With respect to the foundation of the transfer sheet, various known materials used as the foundation of conventional fusing transfer or sublimation transfer shee
Fukui Takuto
Suematsu Hideki
Suzuki Kyouichi
Yamane Toshiyuki
Fish & Neave
Fujicopian Co. Ltd.
Hess Bruce H.
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