Substrate for image-receiving sheet material
AssigneeGlory Mill Papers Limited
InventorsRoger J. Reed, Paul Dunk, Christopher Cusick
Life of this patent
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Abstract
Photographic base paper (10) has a face side waterproof coating which is a co-extruded layer structure of at least a pigmented core layer (P) and top surface layer (E) of polyethylene. The thickness of layer (E) is no more than 12 .mu.m. The pigment content in the face side coating is at least 2 gm.sup.-2 and it is distributed such that the proportion by weight of pigment in the core layer is at least 1.75 times as great as the proportion by weight of pigment in the top surface layer. For optimum photodefinition (image sharpness) the top surface layer should be free of pigment, but as thin (1.5 to 3 .mu.m) as possible. The pigment is preferably TiO.sub.2.
Claims25
A substrate for an imaging layer which is to carry an image to be viewed by reflected light, said substrate comprising:
- a base sheet with a wire side and a face side;
- and
- an opaque co-extruded polymeric coating on said face side, said face side coating comprising:
- i) a core layer bearing a particulate opacifying pigment;
- and
- ii) a top surface layer thereon having a thickness no greater than 12 .mu.m and comprising low density polyethylene;
- iii) a total content of opacifying pigment in the face side coating of at least 3 gm.sup.-2 ;
- and
- iv) the top surface layer is devoid of pigment;
- wherein the co-extruded face side coating includes a lower layer on the face of the core layer remote from the top surface layer.
A substrate for an imaging layer which is to carry an image to be viewed by reflected light, said substrate comprising:
- a base sheet with a wire side and a face side;
- and
- an opaque co-extruded polymeric coating on said face side, said face side coating comprising:
- i) a bottom layer bearing a particulate opacifying pigment;
- and
- ii) a top surface layer thereon having a thickness no greater than 12 .mu.m and comprising low density polyethylene other than linear low density polyethylene;
- iii) a total content of opacifying pigment in the face side coating of at least 3 gm.sup.-2 ;
- and
- iv) the top surface layer being devoid of pigment.
Dependencies are inferred from the claim text.