Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
2002-02-01
2004-10-05
Hess, B. Hamilton (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C428S032390, C428S032510, C430S945000
Reexamination Certificate
active
06800589
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image-forming material comprising a thermal transfer sheet and an image-receiving sheet, and specifically an image-forming material and image formation process that provide high-resolution full color images with use of laser light. More specifically, the invention relates to an image-forming material and image formation process useful for the production of color proofs (DDCP, direct digital color proof) in the graphic arts field or mask images by laser recording based on digital image signals.
BACKGROUND OF THE INVENTION
In the graphic arts industry, a set of printing plates are prepared with use of a set of color separation film images made with lith films from a color original. In general, prior to the actual press operation, in order to check possible errors in color separation procedures and the necessity of color correction, color proofs are made from the color separation film images. Color proofing materials are expected to have a high resolution needed for faithful reproduction of halftone images and an out standing process stability. Further, to obtain color proofs that well simulate actual printed matters, they should preferably be made of the actual printing stock as the substrate, and pigments as the coloring agents both used for the actual press operation. Still further, color proofs should preferably be produced by a dry process with out using a developer liquid.
Various image-recording systems are being developed that can produce color proofs via a dry process directly from digital signals along with the prevalence of electronic systems in pre-press works in these days. Such electronic systems aim at the production of high-quality color proofs generally reproducing halftone images of 150 lines per inch or higher. To reproduce high-quality proof images from digital signals, a laser light is used as recording energy because of its capability of modulation by digital signals and realization of an extremely fine beam. Accordingly, the development of recording materials that exhibit a sufficiently high recording sensitivity to a laser light and a high resolution enabling a precise reproduction of minute halftone dots are demanded.
As the recording material used for image transfer processes based on a laser light, a thermally meltable transfer sheet is set forth in Japanese Patent Laid-Open No. 58045/1993 which comprises a substrate, a light-to-heat conversion layer generating heat by laser light absorption and an image-forming layer containing a pigment dispersed in a thermally meltable wax or binder, both layers being provided on the substrate in this order. In the image-forming process using such a recording material, the heat generated at the laser-irradiated area of the light-to-heat conversion layer melts the image-forming layer at the corresponding area, and the melted layer is transferred onto an image-receiving sheet superimposed on the transfer sheet to form a transferred image.
Japanese Patent Laid-Open No. 219052/1994 discloses a thermal transfer sheet comprising a light-to-heat conversion layer containing a light-to-heat conversion material, a very thin (0.03 to 0.3 &mgr;m thick) thermal stripping layer, and an image-forming layer containing a colorant, all provided on a substrate in this order. When a laser light is irradiated on this type of thermal transfer sheet, the bonding force between the image-forming layer and the light-to-heat conversion layer secured by the presence of the thermal stripping layer is reduced, and thus a high-quality image is formed on an image-receiving sheet superimposed on the thermal transfer sheet. This image formation process makes use of the so-called ‘abrasion’ phenomenon; i.e., at the area where the laser light was irradiated, the thermal stripping layer is partly vaporized by decomposition to weaken the bonding between the image-forming layer and the light-to-heat conversion layer there, thus causing the image-forming layer at the irradiated area to be transferred onto the image-receiving sheet superimposed on the thermal transfer sheet.
These image formation processes have a number of advantages including the capability of using an actual printing stock coated with an image-receiving (adhesive) layer as the image-receiving sheet material and the ease with which it can produce multi-color images by simply sequentially transferring differently colored images on a single image-receiving sheet. In particular, the abrasion-based image formation process, which has a prominent feature of readily producing high-quality images, is useful for the preparation of color proofs (DDCP: Direct Digital Color Proofs) and high-resolution mask images.
When a thermal transfer sheet for use in color image formation gives image defects, the commercial value thereof is noticeably damaged. One reason of image defect generation is the damage of the image-forming layer causing a partial lack of the layer. At such lacking areas, no image transfer takes place thus giving rise to a void in an image. The thermal transfer sheet undergoes such damages during manufacture, processing or image recording due to the rubbing of the front surface of the sheet against the rear surface thereof, for example, in an image-recording apparatus. Especially when the area of the image is large, the probability of image defect generation rises in proportion to the image area. Accordingly the more scarce defect generation is demanded for thermal transfer sheets used for the production of the larger images.
To prevent the generation of such image defects, Japanese Patent Laid-Open No. 270154/1993 discloses a method of using a specified polyester and an acrylate-styrene copolymer as the binder of the image-forming layer. Alternatively, prevention of image defect generation by providing a protective coating on the image-forming layer is also in practical use.
Although one can decrease the frequency of defect generation to some extent with these countermeasures, images of large areas are still accompanied by a practical trouble since the number of image defects is proportional to the image area. Moreover, introduction of a protective layer that can suppress the generation of image defects suffers from the drawback that a large amount of recording energy is required for thermal image transfer.
As another problem, a light-to-heat conversion layer comprising carbon black used as the light-to-heat conversion material, which is preferred as regard to the material cost and the absorption efficiency for laser lights, has a drawback that the image-forming layer provided on the light-to-heat conversion layer is susceptible to mechanical damaging because of the insufficient cohesive energy of the light-to-heat conversion layer. Though the mechanical damages caused by the use of such carbon black-based light-to-heat conversion layer may be prevented by raising the scratch resistance of the image-forming layer, there arises another problem of an insufficient reflection optical density of the transferred image.
Still another type of trouble exists as for image defects. Recently, multi-beams of a laser light are used for laser image recording for the purpose of curtailing the recording time. When a conventional thermal transfer sheet is exposed to a multi-beam laser light for image recording, various troubles associated with image defects tend to occur such as transfer of the light-to-heat conversion layer onto the image-receiving sheet or transfer of the image-forming layer at non-irradiated areas instead of transfer at irradiated areas (reversal mode transfer). Furthermore, the thermal transfer sheets must be handled with a great care so as to cause no peeling-off or damaging of the image-forming layer thereof, which has demanded a high skill for the operator.
As has been pointed out previously, the image-forming material of the invention is expected to be provided with a high process stability. For example, the material must exhibit desirable conveyance and stacking properties since multiple image-receiving sheets must be sta
Hatakeyama Akira
Sugiyama Susumu
Wachi Naotaka
Yamamoto Mitsuru
Fuji Photo Film Co. , Ltd.
Hess B. Hamilton
Sughrue & Mion, PLLC
LandOfFree
Image-forming material and image formation method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image-forming material and image formation method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image-forming material and image formation method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3309382