Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
2000-12-21
2002-04-02
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C428S195100, C428S913000, C428S914000
Reexamination Certificate
active
06365547
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a dye-donor element for thermal dye transfer, and more particularly to the use of a transferable protection overcoat in the element for transfer to a thermal print to provide protection from fading due to light exposure.
BACKGROUND OF THE INVENTION
In recent years, thermal transfer systems have been developed to obtain prints from pictures which have been generated electronically from a color video camera. According to one way of obtaining such prints, an electronic picture is first subjected to color separation by color filters. The respective color-separated images are then converted into electrical signals. These signals are then operated on to produce cyan, magenta and yellow signals. These signals are then transmitted to a thermal printer. To obtain the print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. The two are then inserted between a thermal printing head and a platen roller. A line-type thermal printing head is used to apply heat from the back of the dye-donor sheet. The thermal printing head has many heating elements and is heated up sequentially in response to one of the cyan, magenta and yellow signals. The process is then repeated for the other two colors. A color hard copy is thus obtained which corresponds to the original picture viewed on a screen. Further details of this process and an apparatus for carrying it out are contained in U.S. Pat. No. 4,621,271, the disclosure of which is hereby incorporated by reference.
Thermal prints are susceptible to retransfer of dyes to adjacent surfaces and to discoloration by fingerprints. This is due to dye being at the surface of the dye-receiving layer of the print. These dyes can be driven further into the dye-receiving layer by thermally fusing the print with either hot rollers or a thermal head. This will help to reduce dye retransfer and fingerprint susceptibility, but does not eliminate these problems. However, the application of a protection overcoat will practically eliminate these problems. This protection overcoat is applied to the receiver element by heating in a likewise manner after the dyes have been transferred. The protection overcoat will improve the stability of the image to fading from light exposure and oil from fingerprints.
The protection overcoat must adhere strongly to the top layer of the receiver element so that no imperfections exist in the transferred layer that can be observed without magnification. One such imperfection resulting from the lack of adhesion of the protection overcoat to the receiver surface is the presence of small voids or air bubbles. Bubbles are created if the temperature during transfer of the protection overcoat layer does not go above the Tg of the protection overcoat material, resulting in inadequate adhesion as the donor substrate is stripped away from the receiver.
U.S. Pat. No. 5,322,832 relates to a thermal dye transfer image-receiving element with a transferable protection overcoat containing an inorganic oxide, such as titanium dioxide or tin oxide. However, there is a problem with these materials in that the protection they provide from UV rays is not as good as one would like.
It is the object of this invention to provide a dye-donor element which contains a transferable protection layer which is capable of absorbing UV rays.
SUMMARY OF THE INVENTION
These and other objects are achieved in accordance with this invention which relates to a dye-donor element for thermal dye transfer comprising a support having thereon at least one dye layer area comprising an image dye in a binder and another area comprising a transferable protection layer, the transferable protection layer area being approximately equal in size to the dye layer area, wherein the transferable protection layer comprises a binder and a UV-absorber comprising an oxide of antimony.
By use of the invention, a thermal dye transfer print is obtained which has excellent protection from UV rays.
DETAILED DESCRIPTION OF THE INVENTION
In a preferred embodiment of the invention, the dye-donor element is a multicolor element comprising repeating color patches of yellow, magenta and cyan image dyes, respectively, dispersed in a binder, and a patch containing the protection layer.
In another embodiment of the invention, the protection layer is the only layer on the donor element and is used in conjunction with another dye-donor element which contains the image dyes.
In another preferred embodiment of the invention, the dye-donor element is a monochrome element and comprises repeating units of two areas, the first area comprising a layer of one image dye dispersed in a binder, and the second area comprising the protection layer.
In another preferred embodiment of the invention, the dye-donor element is a black-and-white element and comprises repeating units of two areas, the first area comprising a layer of a mixture of image dyes dispersed in a binder to produce a neutral color, and the second area comprising the protection layer.
The present invention provides a protection overcoat layer on a thermal print by uniform application of heat using a thermal head. After transfer to the thermal print, the protection layer provides superior protection against image deterioration due to exposure to light, common chemicals, such as grease and oil from fingerprints, and plasticizers from film album pages or sleeves made of poly(vinyl chloride). The protection layer is generally applied at a coverage of at least about 0.03 g/m
2
to about 1.5 g/m
2
to obtain a dried layer of less than 1 &mgr;m.
As noted above, the UV-absorber employed in the invention comprises an oxide of antimony. While any such oxide can be used, antimony pentoxide is preferred.
As noted above, the transferable protection layer comprises a UV-absorber dispersed in a binder, such as a polymeric binder. Many such polymeric binders have been previously disclosed for use in protection layers. Examples of such binders include those materials disclosed in U.S. Pat. No. 5,332,713, the disclosure of which is hereby incorporated by reference. In a preferred embodiment of the invention, poly(vinyl acetal) is employed.
In a preferred embodiment of the invention, inorganic particles are used in the protection layer. Examples of useful inorganic particles include, for example, silica, titania, alumina, antimony oxide, clays, calcium carbonate, talc, etc. as disclosed in U.S. Pat. No. 5,387,573. In a preferred embodiment of the invention, the inorganic particles are divinyl benzene. The inorganic particles improve the separation of the laminated part of the protection layer from the unlaminated part upon printing.
In a preferred embodiment of the invention, the protection layer contains from about 5% to about 60% by weight inorganic particles, from about 25% to about 60% by weight polymeric binder and from about 2% to about 60% by weight of antimony pentoxide.
In use, yellow, magenta and cyan dyes are thermally transferred from a dye-donor element to form an image on the dye-receiving sheet. The thermal head is then used to transfer the clear protection layer, from another clear patch on the dye-donor element or from a separate donor element, onto the imaged receiving sheet by uniform application of heat. The clear protection layer adheres to the print and is released from the donor support in the area where heat is applied.
Any dye can be used in the dye layer of the dye-donor element of the invention provided it is transferable to the dye-receiving layer by the action of heat. Especially good results have been obtained with sublimable dyes. Examples of sublimable dyes include anthraquinone dyes, e.g., Sumikaron Violet RS® (Sumitomo Chemical Co., Ltd.), Dianix Fast Violet 3R FS® (Mitsubishi Chemical Industries, Ltd.), and Kayalon Polyol Brilliant Blue N BGM® and KST Black 146® (Nippon Kayaku Co., Ltd.); azo dyes such as Kayalon Polyol Brilliant Blue BM®, Kayalon Polyol Dark Blue 2BM®, and KST Black KR® (Nippon Kayaku Co., Ltd.), Sumikaron Diazo Black 5G® (Sumitom
Foster David G.
Gray Maurice L.
Cole Harold E.
Eastman Kodak Company
Hess Bruce H.
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