Radiation imagery chemistry: process – composition – or product th – Transfer procedure between image and image layer – image... – Imagewise heating – element or image receiving layers...
Reexamination Certificate
2002-02-20
2003-12-23
Schilling, Richard L. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Transfer procedure between image and image layer, image...
Imagewise heating, element or image receiving layers...
C430S200000, C430S271100
Reexamination Certificate
active
06667144
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a laser-induced thermal transfer ink sheet capable of forming transferred images employing laser exposure.
BACKGROUND OF THE INVENTION
It has been known a recording method using thermal transfer recording. This recording is carried out by face-to-face contacting a thermal transfer recording material (an ink sheet) with an image receiving material, and then a heat source such as an electrothermal head controlled by electrical signals is brought into pressure contact with the back surface of said ink sheet. The thermal transfer recording material comprises a substrate having thereon a coloring material layer comprising heat fusible or heat sublimable dyes.
Features of said thermal transfer recording include minimum noise, maintenance-free, low cost, the ease of color image formation, and the capability of digital recording. Therefore, said thermal transfer recording has been employed in many fields such as various types of printers, recorders, facsimile machines, and computer terminals.
In recent years, in the medical and printing fields, it has been demanded a recording method which exhibits high resolution, and is capable of achieving high speed recording as well as image processing, or so-called digital recording. However, in the thermal transfer recording method which utilizes a conventional thermal head or electrothermal head as a heat source, it has been difficult to achieve high image density due to the limited life of the thermal elements of said head.
In order to overcome said drawbacks, thermal transfer recording, which utilizes a laser as a heat source, is proposed in Japanese Patent Publication Open to Public Inspection Nos. 49-15437, 49-17743, 57-87399, and 59-143659. In this system, since a laser beam can be condensed to several &mgr;m, resolving power can be markedly enhanced. However, when said laser beam is employed for recording, scanning type recording is generally utilized. As a result, problems occurred in which the speed of said scanning type recording is less than overall exposure utilizing masking materials and a recording method utilizing a line head. Furthermore, in order to provide the energy necessary for transfer employing laser beam exposure, a high output laser beam source is required, whereby it has been difficult to achieve commercially viable recording speed.
However, as light sources for optical communication as well as optical disks, high output semiconductor lasers as well as small-sized YAG lasers have been increasingly developed and units which are capable of achieving commercially viable recording speed have been developed. As a result, laser-induced thermal transfer recording has been applied to the preparation of the color proofs in the field of printing plate making, utilizing its particular recording characteristics.
In the printing plate making field, proposed has been high quality DDCP (direct digital color proof) capable of achieving halftone dot reproduction. Specifically, from the viewpoint of color, the uniform repeated output of images, and the high resolution, various systems, utilizing said laser-induced thermal recording, are comprised of promising techniques. In addition, laser-induced thermal transfer recording materials are demanded which are manufactured at lower cost and exhibit higher sensitivity, as well as excellent color reproduction.
Said laser-induced thermal transfer recording materials are divided into two types; one in which the ink layer is comprised of light-to-heat converting materials, and the other in which the ink layer is not comprised of said light-to-heat converting materials but said light-to-heat converting layer is provided separately from said ink layer. Among these, it is more advantageous to provide said light-to-heat converting layer separately from said ink layer because light-to-heat converting materials, having an absorption in the visible region, can be employed. Specifically, when color images are prepared, said configuration is more advantageous in terms of color reproduction. When applied to color proofs which require accurate color reproduction, it is desired that printing pigments are employed as coloring materials incorporated into the ink layer, and the light-to-heat converting layer and the ink layer are kept separate.
Further, it has been demanded an increased recording speed for said laser-induced thermal transfer recording. And further it has been desired that the employed laser-induced thermal transfer materials be increased in sensitivity. Japanese Patent Publication Open to Public Inspection Nos. 5-169861 and 6-122280 disclose techniques to provide a cushioning layer to form high sensitivity images in the image forming method in which each of the ink layers is transferred employing laser beam exposure. The cushion layer is normally provided between the support and the light-to-heat converting layer in order to be effectively functioned as a cushion.
U.S. Pat. No. 5,156,938 discloses a technique of an image forming method employing an ink layer which is subjected to ablation transfer by incorporating light-to-heat converting agents and sensitizers in said ink layer. In addition, U.S. Pat. Nos. 5,171,650, 5,256,506, and 5,501,938, and Japanese Patent Publication Open to Public Inspection No. 6-510490 disclose techniques which provide a dynamic releasing layer (DRL) such as an aluminum vacuum-evaporated layer under an ink layer which is subjected to ablation transfer.
In order to prepare high-sensitive laser-induced thermal transfer materials, it is effective to make the light-to-heat converting layer thinner and more light-absorptive, employing infrared absorbing dyes having a high absorption efficiency for the specific wavelengths of the laser beam, as light-to-heat converting agents which absorb a laser beam and convert it to thermal energy. However, problems occur in which color contamination occurs due to the transfer of said light-to-heat converting agents together with the ink layer.
Further, since said cushioning layer is adhesive, its incorporation increases production cost due to the requirement of special production facilities.
SUMMARY OF THE INVENTION
From the view of the foregoing, the present invention was achieved. An object of the present invention is to provide a laser-induced thermal transfer ink sheet which exhibits high sensitivity, decreased color contamination, excellent color reproduction, and high productivity.
The object of the present invention is achieved by the embodiments described below.
(1) A laser-induced thermal transfer ink sheet for forming a transfer image, comprising a support having thereon a light-to-heat converting layer containing a light-to-heat converting compound, an interlayer containing a resin, and an ink layer in that order,
wherein the light-to-heat converting compound and the resin satisfy one of the following requirements (a) and (b):
(a) the light-to-heat converting compound is soluble in an organic solvent and the resin is soluble in water; and
(b) the light-to-heat converting compound is soluble in water and the resin is soluble in an organic solvent.
(2) The laser-induced thermal transfer ink sheet of item (1), wherein the resin in the interlayer is soluble in an amount of at least 5 weight % in a solvent in which the solubility of the light-to-heat converting compound in the light-to-heat converting layer is at most 0.1 weight %.
(3) The laser-induced thermal transfer ink sheet of item (1), wherein the light-to-heat converting compound is soluble in an organic solvent and the resin is soluble in water.
(4) The laser-induced thermal transfer ink sheet of item (1), wherein the light-to-heat converting compound is soluble in water and the resin is soluble in an organic solvent.
(5) The laser-induced thermal transfer ink sheet of item (3), wherein the light-to-heat converting layer further comprises a binder resin and a hardening agent.
(6) The laser-induced thermal transfer ink sheet of item (4), wherein the interlayer further comprises a hardening agent.
(7) The laser-indu
Konuma Taro
Maehashi Tatsuichi
Maejima Katsumi
Ohta Tomohisa
Konica Corporation
Muserlian Lucas and Mercanti
Schilling Richard L.
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