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
1999-09-09
2001-09-11
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...
C430S212000, C430S533000, C430S536000, C430S538000, C430S950000, C347S105000, C162S136000, C428S220000, C428S311710, C428S511000, C428S513000, C428S537500
Reexamination Certificate
active
06287743
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to imaging materials. In a preferred form it relates to base materials for photographic papers.
BACKGROUND OF THE INVENTION
In the formation of photographic paper it is known that the base paper has applied thereto a layer of polyolefin resin, typically polyethylene. This layer serves to provide waterproofing to the paper and provide a smooth surface on which the photosensitive layers are formed. The formation of the smooth surface is controlled by both the roughness of the chill roll where the polyolefin resin is cast, the amount of resin applied to the base paper surface and the roughness of the base paper. Since the addition of polyolefin resin to improve the surface adds significant cost to the product it would be desirable if a smoother base paper could be made to improve the gloss of the photographic paper.
Typical photographic grade cellulose paper base has a particularly objectionable roughness in the spatial frequency range of 0.30 to 6.35 &mgr;m. In this spatial frequency range, a surface roughness average greater than 0.50 micrometers can be objectionable to consumers. Visual roughness greater than 0.50 micrometers in usually referred to as “orange peel”. An imaging element with roughness less than 1.10 &mgr;m at a spatial frequency of between 200 cycles/mm and 1300 cycles/mm is considered smooth and is typically defined as a glossy image.
Traditional photographic papers contain chemistry to provide certain properties to the paper that are not inherent in the paper fiber. This chemistry includes materials known in the art to improve wet strength and dry strength. Since photographic paper that comprises laminated biaxially oriented polyolefin sheets laminated to base paper has greatly improved tensile strength over traditional photographic papers, the addition of wet and dry strength to the paper adds unwanted cost to the product. It would be desirable if a base paper could be made that was free of wet and dry strength resins.
It has been proposed in U.S. Pat. No. 5,866,282—Bourdelais et al., to utilize a composite support material with laminated biaxially oriented polyolefin sheets as a photographic imaging material. In U.S. Pat. No. 5,866,282, biaxially oriented polyolefin sheets are extrusion laminated to cellulose paper to create a support for silver halide imaging layers. The biaxially oriented sheets described in U.S. Pat. No. 5,866,282 have a microvoided layer in combination with coextruded layers that contain white pigments. The composite imaging support structure described in U.S. Pat. No. 5,866,282 has been found to be more durable, sharper and brighter than prior art photographic paper imaging supports that use cast melt extruded polyethylene layers coated on cellulose paper. The surface roughness of the paper base in U.S. Pat. No. 5,866,282 is replicated on the surface of the imaging element.
It has been proposed in U.S. Pat. No. 5,244,861 to utilize biaxially oriented polypropylene laminated to a base paper for use as a reflective imaging receiver for thermal dye transfer imaging. While the invention does provide an excellent material for the thermal dye transfer imaging process, this invention can not be used for imaging systems that are gelatin based such as silver halide and ink jet because of the sensitivity of the gel imaging systems to humidity. The humidity sensitivity of the gel imaging layer creates unwanted imaging element curl. One factor contributing to the imaging element curl is the ratio of base paper stiffness in the machine direction to the cross direction. Traditional photographic base papers have a machine direction to cross direction stiffness ratio, as measured by Young's modulus, of approximately 2.0. For a composite photographic material with laminated biaxially oriented polyolefin sheets to a base paper it would be desirable if the machine direction to cross direction stiffness ratio were approximately 1.6 to reduce imaging element curl.
A receiving element with cellulose paper support for use in thermal dye transfer has been proposed in U.S. Pat. No. 5,288,690 (Warner et al.). While the cellulose paper in U.S. Pat. No. 5,288,690 solved many of the problems existing with thermal dye transfer printing on a laminated cellulose paper, this cellulose paper is not suitable for a laminated cellulose photographic paper since this paper has undesirable surface roughness in the spatial frequency range of 0.30 to 6.35 mm and the pulp used in U.S. Pat. No. 5,288,690 is expensive compared to alternative pulps. It would be desirable if “orange peel” roughness could be minimized in the laminated photographic base paper.
PROBLEM TO BE SOLVED BY THE INVENTION
There remains a need for a more effective base paper to provide an improved smooth surface as well as provide a stronger photographic element.
SUMMARY OF THE INVENTION
An object of the invention is to provide an imaging material that has improved surface properties.
Another object of this invention is to provide an imaging material with a glossy surface.
A further object of this invention is to provide a base paper that provides a stronger photographic element.
These and other objects of the invention are generally accomplished by an imaging element comprising an imaging layer and an upper cellulose paper base wherein said base has a surface roughness of between 0.30 and 0.95 &mgr;m at a spatial frequency of between 200 cycles/mm and 1300 cycles/mm.
ADVANTAGEOUS EFFECT OF THE INVENTION
The invention provides an improved paper for imaging elements. It particularly provides an improved paper for imaging elements that are smoother, more opaque and are low cost.
DETAILED DESCRIPTION OF THE INVENTION
There are numerous advantages of the invention over prior practices in the art. The invention provides a imaging element that has a smoother surface, increasing the commercial value of the imaging element by providing a glossy photographic print material and eliminating the need for expensive smooth casting rolls that are typical of melt extruded photographic base materials. By improving the smoothness of the imaging element, the reflective print material has a more maximum black as the reflective properties of the improved surface are more specular that prior art materials. Further, as both the whites and blacks are improved, the contrast of the reflective photographic paper is improved. Improved contrast range has been shown to reduce unwanted fringing in digital optical printing applications. Another advantage is the significant reduction in dust generation as this base paper is cut in both the cross and machine directions in imaging converting applications such as the slitting of wide rolls of imaging support, punching of imaging elements as in photographic processing equipment and chopping as in photographic finishing equipment. A further advantage is the improvement in opacity for the imaging element, reducing back side show through that exists during the viewing of images allowing a higher density back side branding to be utilized. These and other advantages will be apparent from the detailed description below.
To accurately define a smooth surface for photographic grade cellulose base paper, the surface roughness of the cellulose paper is used to quantify the surface smoothness. A smooth surface is one that has a low surface roughness value. A non glossy surface or a rough surface is one that has a high surface roughness value. The Bourdelais surface roughness continuum is defined as surface roughness values from 0.30 to 0.95 micrometers at a spatial frequency of between 200 cycles/mm and 1300 cycles/mm. A surface roughness of 0.25 micrometers is approximately equal to the surface roughness of melt cast, oriented polyolefin. A surface roughness of approximately 1.1 micrometers is equal to prior art photographic cellulose paper bases. A spatial frequency of between 200 cycles/mm and 1300 cycles/mm has been selected for the Bourdelais roughness continuum because it represents a critical perceptual range of surface roughness. A spatial frequenc
Aylward Peter T.
Bourdelais Robert P.
Dagan Sandra J.
Oakland Michelle M.
Eastman Kodak Company
Leipold Paul A.
Schilling Richard L.
LandOfFree
Imaging material with smooth cellulose base does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Imaging material with smooth cellulose base, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Imaging material with smooth cellulose base will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2454222