Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
2000-09-06
2002-03-26
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C428S207000, C428S327000
Reexamination Certificate
active
06362132
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 a matte surface thereon.
BACKGROUND OF THE INVENTION
In recent years, thermal transfer systems have been developed to obtain prints from pictures that 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 light fade and oil from fingerprints.
In a thermal dye transfer printing process, it is desirable for the finished prints to compare favorably with color photographic prints in terms of image quality. The look of the final print is very dependent on the surface texture and gloss. Typically, color photographic prints are available in surface finishes ranging from very smooth, high gloss to rough, low gloss matte.
If a matte finish is desired on a thermal print, it has been previously accomplished by using matte sprays or by matte surface applications through post printing processors. However, both of these solutions are costly and add a degree of complexity to the process.
Ser. No. 09/550,367 of Simpson et al., filed Apr. 19, 2000, and JP 09/323482 relate to the use of expandable microspheres in a transferable protection layer area of a dye-donor element. However, there is a problem with these microspheres in that they will not provide a defect-free print with a desired gloss at a low printhead temperature.
It is the object of this invention to provide a dye-donor element for thermal dye transfer printing that can impart a matte or low gloss finish onto a receiving element. It is another object of this invention to provide a dye-donor element for thermal dye transfer printing that provides a protection layer which improves the adhesion between the protection layer and the receiving layer resulting in less defects. It is another object of the invention to provide a dye-donor element for thermal dye transfer printing that provides a protection layer wherein the gloss can be varied.
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 contains inorganic particles, a polymeric binder and unexpanded synthetic thermoplastic polymeric microspheres, the microspheres having a particle size in the unexpanded condition of from about 5 to about 20 &mgr;m, and which expand to about 20 to about 120 &mgr;m upon application of heat during transfer of the protection layer to an image-receiving layer to provide a matte surface thereon, the microspheres comprising a mixture of low softening point microspheres and high softening point microspheres, the low softening point microspheres having a softening point less than about 105° C., the high softening point microspheres having softening point greater than about 110° C., and the ratio of the low softening point microspheres to the high softening point microspheres being from about 9:1 to about 1:6, preferably from about 4:1 to about 1:4.
By use of the invention, a dye-donor element is provided containing a transferable protection layer which is capable of giving a variable gloss.
DETAILED DESCRIPTION OF THE INVENTION
During application of the protection layer to the receiver element, heat from the linear thermal printing head causes the microspheres to expand to many times their original size. This causes a roughening of the surface to occur resulting in a matte or lower gloss image comparable to that obtained on a matte surface photographic paper. In accordance with the invention, a mixture of microspheres that differ in the softening temperature, or T-start of the microsphere wall is used. When a low printhead temperature is employed, a 60° gloss value of 65 or greater is obtained, while at a high print head temperature, a 60° gloss value of less than 40 is obtained. Thus, by merely varying the temperature of transfer of the protection layer, any desired degree of gloss may be obtained. The temperature of transfer of the protection layer can be varied by changing the power supplied to the thermal print head.
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.
Any expandable microspheres may be used in the invention provided they have the softening point parameters as described above. Materials which can be used are disclosed, for example, in U.S. Pat. No. 3,556,934 and 3,779,951, the disclosures of which are hereby incorporated by reference.
In a preferred embodiment of the invention, the expandable microspheres are white, spherically-formed, hollow particles of a thermoplastic shell encapsulating a low-boiling, vaporizable substance, such as a liquid, which acts as a blowing agent. When the unexpanded microspheres are heated, the thermoplastic shell softens and the encapsulated blowing agent expands, building pressure. This results in expansion of the microsphere. The various expandable microspheres differ in the temperature where the microspheres began to expand. This is known as t
Hastreiter, Jr. Jacob J.
Simpson William H.
Cole Harold E.
Eastman Kodak Company
Hess Bruce H.
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