Protective undercoating for a printed medium

#The present invention relates to a clear protective undercoat for a printed medium, achieved with a thermal transfer material and a carrier ribbon forming a donor web which is subjected to heat and pressure to transfer a segment of thermal transfer material from the donor web onto the printed area on the printable surface of a medium.

#Digital photography and imaging provide cost-effective alternatives for capturing images, but known methods of producing durable, hardcopy prints of digitally printed areas are at least as expensive as traditional photographic methods. Further, with increasing use of various printing and imaging technologies in the publishing industry as well as in the home, protecting imaged or printed documents against abrasion, water alcohol, other liquid spills, ink smear, fading, blocking or other image-degradation processes and effects has become an important consideration. Such protection is particularly desirable for printed or imaged documents produced with water-based (water-soluble) or other liquid inks, as well as documents printed or imaged with toner. These are commonly used in ink-jet printing, offset printing, electrophotography and the like.

#Photography provides an easy and reliable way to permanently capture images for a variety of uses. While photographs provide durable images, they are prone to scratches, have poor resistance to light and ultraviolet radiation (which causes photographic images to fade over time), and degrade when exposed to water, other liquids or to vapors of such liquids. Traditional photography uses harsh and expensive chemicals, requires silver recovery, and involves a process requiring several intermediate steps of handling negatives. While photographic processes can be automated, such automatic processing machines are expensive and bulky and do not eliminate the inherent problems of chemical exposure and handling negatives. Additionally, producing large prints (larger than the traditional 3-by-5 inch or 4-by-6 inch prints) can be quite expensive.

#FIG. 1 is a cross sectional view of an undercoated photo quality print having a medium (2) with a printable surface on to which an image (4) is printed and a thermal transfer material undercoat (6) is also transferred to the printable surface of the medium to cover the printed image.

#FIG. 2 is schematic view of the apparatus of the present invention, showing a frame (8) housing a loader (10), a sheet of the medium (12), a heating element (14), a source roll (16), a take-up roll (18), a tensioned section of the donor web (20) and a base (22).

#FIG. 3 is an alternate schematic view of the apparatus of FIG. 2 with the ribbon handler (source roll and take-up roll) tensioning the donor web in a position away from the medium.

#The present invention provides a means of creating inexpensive, durable digital prints that can compete or improve upon the quality and durability of traditional silver halide prints or other coating protected digital prints. This invention uses a thermally-transferred, opaque undercoat material, which is applied as a colorless transparent film, to protect the printed area on the media.

#The undercoated media of the present invention is obtained by transferring protective undercoat from a donor web which has a top side of carrier ribbon material, the carrier ribbon material anchoring the bottom side which has at least one layer of undercoat materials. This bottom side may include a release layer, a protective undercoat material, and an adhesive layer. The protective undercoat material may be a single layer or include multiple layers. As the donor web is heated and pressed into contact with the printable surface of a medium, the protective undercoat is transferred onto the printable surface of the medium.

#The protective undercoat film of the present invention improves print quality and increases durability of the printed areas. For example, the undercoat provides good protection against various substances that might spill, either in the form of liquid or dry spills, on the surface of a print. Non-limiting examples of substances which the present invention would protect against would be water, alcohol, ink, coffee, soda, ammonia based or other cleaning liquids, food stains (e.g. mustard, chocolate, berry), and dirt.