Base paper for photographic prints
AssigneeThe Wiggins Teape Group Limited
InventorPaul Dunk
Life of this patent
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Abstract
Resin coated photographic base paper having improved stiffness is made by co-extruding a face side resin coating having a first layer of pigmented LDPE and over it a thin layer of a stiff polymer, especially polycarbonate. An intermediate layer of a strongly adhesive polymer may be included to enhance bonding between the first and second layers. The base paper may also have a co-extruded wire side resin coating with a stiff polymer second layer.
Claims17
Resin coated photographic base paper comprising a substrate of paper and a composite coating comprising ( 1) from 10 to 50 g.m.sup.-2 of an extruded first coating layer consisting essentially of a low density polyethylene (having a density of 0.910-0.940 g/cm.sup.3) or a blend of low density and high density polyethylenes (the high density polyethylenes having a density greater than or equal to 0.941 g/cm.sup.3) containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment and, (2) overlying the first coating layer and firmly bonded thereto, from 0.1 to 18 gm.sup.-2 of an extruded second coating layer of a polymer having a stiffness modulus of at least 2.0 GPa.
Resin coated photographic base paper comprising a substrate of paper carrying on its face side a composite coating comprising:
- from 10 to 50 gm.sup.-2 of an extruded first coating layer consisting essentially of a low density polyethylene (having a density of 0.910-0.940 g/cm.sup.3) or a blend of low density and high density polyethylene (having a density greater than or equal to 0.941 g/cm.sup.3) containing at least 50% by weight of low density polyethylene, the first coating layer containing at least 5% by weight of opacifying pigment;
- from 0.1 to 18 gm.sup.-2 of an extruded second coating layer of a polymer having a stiffness modulus of at least 2.0 GPa;
- and
- intermediate the said first and second coating layers, a layer of from 1 to 10 gm.sup.-2 of a polymer, which is strongly adhesive towards both the first and second layers, serving to firmly bond the said first and second layers.
Resin coated photographic base paper, comprising a substrate of paper to which has been applied, by extrusion, a combination of coating layers, which combination essentially consists of:
- (i) a first resin coating layer of which at least 5 wt % is pigment, the resin of the said first layer consisting essentially of low density polyethylene (having a density of 0.910-0.940 g/cm.sup.3) or a blend of low density and high density polyethylene (the high density polyethylene having a density greater than or equal to 0.941 g/cm.sup.3 containing at least 50 wt % low density polyethylene and said first layer being coated at a coatweight in a range of from 10 to 50 gm.sup.-2 ;
- and
- (ii) a second resin coating layer, present on a side of the first coating layer remote from said substrate, of a resin having a stiffness modulus (in accordance with ASTM D790-80) of at least 2.0 GPa, and said second layer being coated at a coat weight in a range of from 0.1 to 18 gm.sup.-2.
Dependencies are inferred from the claim text.