Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Patent
1993-06-02
1995-11-28
Sluby, P.C.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
428329, 428330, 428340, 428409, 428508, 428509, 428910, 427496, 427498, 427499, 427500, B32B 2900, G03C 186, B05D 306
Patent
active
054706521
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a support sheet for photographic printing paper. More particularly, the present invention relates to a support sheet for a photographic paper sheet, which effectively prevents yellowing of a coated resin layer by developing treatment, has sufficient flexibility, and is, when converted to a photographic printing paper, capable of preventing or restricting a fogging in the photographic printing paper even when storing it for a long period of time, and a process for producing the same.
BACKGROUND ART
Currently, a polyolefin-coated support sheet produced by coating both surfaces of a substrate consisting of a paper sheet with a polyolefin resin is widely employed as a support sheet for photographic printing paper. Since the polyolefin coating layer is hydrophobic, the above-mentioned type of support sheet is advantageous in comparison with baryta paper in that in develop-fixing treatment, the treating liquid is not allowed to easily penetrate into the support sheet, and thus the necessary time for water-rinsing and drying is significantly shortened. Also, the support sheet has an advantage that since the treating liquid does not penetrate into the substrate paper sheet, the shrinkage and elongation of the support sheet are restricted and thus the support sheet exhibits an excellent dimensional stability.
For the purpose of enhancing an opacifying power or image-forming property, the polyolefin resin in the coating layer of the support sheet is mixed with an inorganic white pigment such as titanium dioxide. The pigment has a poor dispersing property for the resin and causes a problem such that when the resin is melt-extruded, the resin is foamed by a volatile component contained in the pigment and thus the resultant resin coating layer is cracked or broken. For this reason, it is impossible to increase the content of the pigment in the coating layer to a high level sufficient to obtain a satisfactory opacifying power and the image-forming property.
Generally speaking, when titanium dioxide pigment is employed, it is difficult to add this pigment at a content of about 20% by weight or more. Therefore, the photographic printing paper produced from this type of support sheet for photographic printing sheet is unsatisfactory in sharpness of images.
Recently, a support sheet for photographic printing paper, having an electron beam-cured resin coated layer formed by coating a resin composition curable by an electron beam irradiation, namely an electron beam-curable resin, on a support sheet, was provided by, for example, Japanese Examined Patent Publication (Kokoku) No. 60-17,104, Japanese Examined Patent Publication (Kokoku) No. 60-17,105, and Japanese Unexamined Patent Publication (Kokai) No. 57-49,496. In accordance with this method, when the coating layer is formed, it is unnecessary to heat and melt the resin composition at a high temperature, and thus the pigment content can increase to 20 to 80% by weight. Therefore, the photographic printing paper sheet produced from the above-mentioned type of support sheet has a significantly enhanced image sharpness in comparison with the conventional photographic printing paper sheet having the polyolefin resin coating layers. Nevertheless, with respect to the photographic printing paper produced by coating a photographic photosensitive layer on an electron beam-cured resin-coating layer cured by an electron beam irradiation, it is known that in the developing treatment, a phenomenon that a photographic developing reagent is absorbed by and remains in the resin coating layer, and thus the photographic printing sheet is discolored yellow after the developing treatment, namely a yellowing phenomenon occurs, and when a developing treatment is applied to the photographic printing paper after a lapse of a storage period, the degree of fogging increases to a level not negligible for practical use or the photosensitivity thereof changes. On the other hand, it is known that the resultant coating layer is hard and has little fle
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Ito Masataka
Kobayashi Masafumi
Miura Takaharu
Nemoto Hiroyuki
Tanaka Chieko
Oji Paper Co., Ltd
Sluby P.C.
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