Roughness elimination by control of strength of polymer sheet in relation to base paper

The invention relates to a photographic element comprising a paper base, at least one photosensitive silver halide layer, a biaxially oriented polymer sheet between said paper base and said silver halide layer, wherein said polymer sheet has a thickness of between 13 microns and 65 microns and a Young's modulus of between 700 and 5200 MPa wherein said base paper has a Young's modulus between 1380 MPa and 13800 MPa, a thickness between 75 microns and 200 microns, and an average roughness on the emulsion side of between 0.18 and 0.68 microns and wherein the ratio of thickness between said polymer sheet and said base paper is between 0.1 and 0.5.

FIELD OF THE INVENTION 
This invention relates to photographic materials. In a preferred form it 
relates to laminated base materials for photographic elements. 
BACKGROUND OF THE INVENTION 
In the formation of color paper it is known that the base paper has applied 
thereto a layer of polymer, typically polyethylene. This layer serves to 
provide waterproofing to the paper, as well as providing a smooth surface 
on which the photosensitive layers are formed. The formation of a suitably 
smooth surface is difficult requiring great care and expense to ensure 
proper laydown and cooling of the polyethylene layers. One defect in prior 
formation techniques is caused when an air bubble is trapped between the 
forming roller and the polyethylene which will form the surface for 
casting of photosensitive materials. This air bubble will form a pit that 
will cause a defect in the photographic performance of photographic 
materials formed on the polyethylene. It would be desirable if a more 
reliable and improved surface could be formed at less expense. 
In color papers there is a need for providing color papers with improved 
resistance to curl. Present color papers will curl during development and 
storage. Such curl is thought to be caused by the different properties of 
the layers of the color paper as it is subjected to the developing and 
drying processes. Humidity changes during storage of color photographs 
lead to curling. There are particular problems with color papers when they 
are subjected to extended high humidity storage such as at greater than 
50% relative humidity. Extremely low humidity of less than 20% relative 
humidity also will cause photographic papers to curl. 
In photographic papers the polyethylene layer also serves as a carrier 
layer for titanium dioxide and other whitener materials as well as tint 
materials. It would be desirable if the colorant materials rather than 
being dispersed throughout the polyethylene layer could be concentrated 
nearer the surface of the layer where they would be more effective 
photographically. 
It has been proposed in U.S. Pat. No. 5,244,861 to utilize biaxially 
oriented polypropylene in receiver sheets for thermal dye transfer. 
It would be desirable if paper base materials could be made smoother. In 
conventional practice paper base materials are coated with a layer of 
polyethylene which serves as the base for imaging layers. The method of 
casting of the polyethylene onto the paper base results in imperfections 
in the surface onto which the imaging layers are cast. These imperfections 
are at least the result of the roughness of the paper base material. The 
paper base has a particularly objectionable roughness in the spatial 
frequency range of 0.3 to 6.35 mm. This results in a defect usually 
referred to as orange peel. It would be desirable if this defect in 
photographic base paper could be minimized or eliminated. 
PROBLEM TO BE SOLVED BY THE INVENTION 
There remains a need for photographic papers that have less surface 
roughness so that the photographic images are glossier and smoother. 
SUMMARY OF THE INVENTION 
An object of the invention is to provide a photographic color paper that 
has improved surface properties. 
Another object of the invention is to provide photographic paper with a 
more glossy surface. 
These and other objects of the invention are generally accomplished by a 
photographic element comprising a paper base, at least one photosensitive 
silver halide layer, a biaxially oriented polymer sheet between said paper 
base and said silver halide layer, wherein said polymer sheet has a 
thickness of between 13 microns and 65 microns and a Young's modulus of 
between 700 and 5200 MPa wherein said base paper has a Young's modulus 
between 1380 MPa and 13800 MPa, a thickness between 75 microns and 280 
microns, and an average roughness on the emulsion side of between 0.18 and 
0.68 microns and wherein the ratio of thickness between said polymer sheet 
and said base paper is between 0.1 and 0.5. 
In another preferred embodiment of the invention, a photographic element 
wherein said element comprises at least one photosensitive layer, a base 
paper, and a biaxially oriented polymer sheet between said base paper and 
said polymer sheet wherein said base paper has a Young's Modulus between 
2100 MPa and 3500 MPa in the cross direction, thickness between 152 and 
230 microns and a roughness average on the photosensitive side of between 
0.5 and 0.7 microns and wherein the properties of the polymer sheet are 
determined according to a formula for predicting the ratio of final 
smoothness to initial smoothness of said base paper on Formula I. 
##EQU1## 
where the caliper is in microns and the modulus is in units of MPa. 
ADVANTAGEOUS EFFECT OF THE INVENTION 
There are numerous advantages of the invention over prior practices in the 
art. The invention provides a photographic image that has an exceptionally 
glossy and smooth finish. Further the laminated base is low in cost, as 
the biaxially oriented sheet may be laminated to a relatively low quality 
base paper and still result in exceptional smoothness of the laminated 
structure. 
DETAILED DESCRIPTION OF THE INVENTION 
The invention has numerous advantages over prior photographic base 
materials. The invention has the advantage of providing a smoother base 
for formation of photosensitive layers. This results in improved gloss to 
the photograph. Further, the cost of the laminated base may be lower, as a 
lower quality base paper may be utilized. The films of the invention 
exhibit less orange peel effect, as the laminated biaxially oriented sheet 
provides a smoother base as the paper defect that contributes to orange 
peel is minimized by the effect of the strong biaxially oriented sheet. 
The invention provides a photographic element that has much less tendency 
to curl when exposed to extremes of humidity. Further, the invention 
provides a photographic paper that is much lower in cost as the 
criticalities of the formation of the polyethylene are removed. There is 
no need for the difficult and expensive casting and cooling in forming a 
surface on the polyethylene layer as the biaxially oriented polymer sheet 
of the invention provides a high quality surface for casting of 
photosensitive layers. The optical properties of the photographic elements 
in accordance with the invention are improved as the color materials may 
be concentrated at the surface of the biaxially oriented sheet for most 
effective use with little waste of the colorant materials. Photographic 
materials utilizing microvoided sheets of the invention have improved 
resistance to tearing. The photographic materials of the invention are 
lower in cost to produce as the microvoided sheet may be scanned for 
quality prior to assembly into the photographic member. With present 
polyethylene layers the quality of the layer cannot be assessed until 
after complete formation of the base paper with the polyethylene 
waterproofing layer attached. Therefore, any defects result in discard of 
expensive product. The invention allows faster hardening of photographic 
paper emulsion, as water vapor is not substantially transmitted from the 
emulsion through the biaxially oriented sheets. 
Another advantage of the microvoided sheets of the invention is that they 
are more opaque than titanium dioxide loaded polyethylene of present 
products. They achieve this opacity partly by the use of the voids as well 
as the improved concentration of titanium dioxide at the surface of the 
sheet. The photographic elements of this invention are more scratch 
resistant as the oriented polymer sheet on the back of the photographic 
element resists scratching and other damage more readily than 
polyethylene. These and other advantages will be apparent from the 
detailed description below. 
The base papers utilized in photographic materials, while of high quality 
and good surface smoothness, nevertheless exhibit a range of surface 
irregularity that contributes to defects in photographic images that are 
formed on these papers. A particular problem is the defect in the paper 
having a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.5 to 0.7 microns. This defect, when coated with polyethylene, is not 
filled in and leveled even with large amounts of polyethylene extruded 
onto the paper. This defect is a major contributor to the orange peel 
defect of a photographic paper image. Photographic paper is also subject 
to changes in its bulk caused by humidity changes that cause changes in 
the bulk of the paper. The humidity changes cause the paper to become 
thicker and thinner in a somewhat irregular manner. The biaxially oriented 
sheet of the laminated structure of the invention minimizes the 
transferance of the bulk defects of humidity change to the photographic 
image. 
The polymer sheet forming the laminate base of the invention is designed to 
be strong enough to overcome roughness of the base sheet to which it is 
adhered. It has been found that by selection of particular properties of 
thickness and Young's modulus, the roughness of the paper base may be 
overcome. Suitable thickness for the polymer sheet has been found to be 
between 13 and 65 microns. A suitable Young's modulus has been found to be 
between 700 and 5200 MPa. The preferred thickness for the polymer sheet 
has been found to be between 35 and 40 microns because this gives the best 
combination of strength and cost efficiency. The preferred Young's modulus 
for the polymer sheet has been found to be between 2400 and 3600 MPa 
because this gives the best combination of strength and cost efficiency. 
The base paper utilized in the laminated base material of the invention is 
selected to provide a laminated base that has desirable properties. 
Generally the base papers have an average roughness of between about 0.18 
and 0.68 microns. 
The ratio of the thickness between the polymer sheet and the base paper may 
be any combination that produces a desirable laminated base. Generally the 
ratio of thickness between said polymer sheet and said base paper is 
between 0.1 and 0.5. 
The laminated base of the invention has a roughness improvement over the 
roughness of the base paper of between about 10 and 50 percent as measured 
by the decrease in roughness average at a spatial frequency of 0.3 to 6.35 
mm. The product preferably provides an increase in smoothness of greater 
than 20 percent and up to 35 percent in photographs formed with silver 
halide imaging systems over conventional systems. This amount of 
improvement is easily noticeable to the professional photographer. 
In the art of photographic and near photographic paper manufacturing, there 
is a need to have prints that are smooth and glossy appearing. By near 
photographic it is meant techniques such as thermal dye transfer and ink 
jet imaging systems. It is known that the raw stock roughness plays a role 
in the final print gloss and appearance. The most objectionable feature is 
"orange peel" which is a long wave length spatial frequency in the range 
of 0.3 to 6.35 mm. 
While primarily drawn to substrates for photographic use, the laminated 
imaging substrates of the invention also find use in other imaging systems 
such as ink jet, electrophotography, and thermal dye transfer. 
Previous attempts to reduce the effect of raw stock orange peel has been 
centered around making the raw stock smoother by a variety of techniques 
such as calendering, densification, refining, pressing . . . etc. Attempts 
have also been made to coat or apply layers of a variety of materials to 
the surface to level or fill in the valleys to make a smooth appearing 
paper. In the art of polyethylene extrusion or lamination of film to 
paper, it has been found that thicker layers of polyethylene have a 
dampening effect on certain frequencies of orange peel. As part of this 
invention, it has been found that the dampening effect can be greatly 
improved over only polyethylene coating by changing the modulus of the 
polymer in combination with the layer thickness. Reduced surface roughness 
can be achieved by increasing the modulus of the film. The combination of 
higher modulus and thicker films has the largest dampening effect on the 
orange peel roughness. 
The terms as used herein, "top", "upper", "emulsion side", and "face" mean 
the side of a photographic member bearing the imaging layers. The terms 
"bottom", "lower side", and "back" mean the side of the photographic 
member opposite from the side bearing the photosensitive imaging layers or 
developed image. 
Any suitable biaxially oriented polyolefin sheet may be used for the sheet 
on the top side of the laminated base of the invention. Microvoided 
composite biaxially oriented sheets are preferred and are conveniently 
manufactured by coextrusion of the core and surface layers, followed by 
biaxial orientation, whereby voids are formed around void-initiating 
material contained in the core layer. Such composite sheets are disclosed 
in, for example, U.S. Pat. Nos. 4,377,616; 4,758,462 and 4,632,869, the 
disclosure of which is incorporated for reference. 
The core of the preferred composite sheet should be from 15 to 95% of the 
total thickness of the sheet, preferably from 30 to 85% of the total 
thickness. The nonvoided skin(s) should thus be from 5 to 85% of the 
sheet, preferably from 15 to 70% of the thickness. 
The density (specific gravity) of the composite sheet, expressed in terms 
of "percent of solid density" is calculated as follows: 
##EQU2## 
Percent solid density should be between 45% and 100%, preferably between 
67% and 100%. As the percent solid density becomes less than 67%, the 
composite sheet becomes less manufacturable due to a drop in tensile 
strength and it becomes more susceptible to physical damage. 
The total thickness of the composite sheet can range from 12 to 100 
microns, preferably from 20 to 70 microns. Below 20 microns, the 
microvoided sheets may not be thick enough to minimize any inherent 
non-planarity in the support and would be more difficult to manufacture. 
At thicknesses higher than 70 microns, little improvement in either 
surface smoothness or mechanical properties are seen, and so there is 
little justification for the further increase in cost for extra materials. 
The biaxially oriented sheets of the invention preferably have a water 
vapor permeability that is less than 1.55.times.10.sup.-4 g/mm.sup.2 
/day/atm. This allows faster emulsion hardening during formation, as the 
laminated invention support does not substantially transmit water vapor 
from the emulsion layers during coating of the emulsions on the support. 
The transmission rate is measured by ASTM F1249. 
"Void" is used herein to mean devoid of added solid and liquid matter, 
although it is likely the "voids" contain gas. The void-initiating 
particles which remain in the finished packaging sheet core should be from 
0.1 to 10 microns in diameter, preferably round in shape, to produce voids 
of the desired shape and size. The size of the void is also dependent on 
the degree of orientation in the machine and transverse directions. 
Ideally, the void would assume a shape which is defined by two opposed and 
edge contacting concave disks. In other words, the voids tend to have a 
lens-like or biconvex shape. The voids are oriented so that the two major 
dimensions are aligned with the machine and transverse directions of the 
sheet. The Z-direction axis is a minor dimension and is roughly the size 
of the cross diameter of the voiding particle. The voids generally tend to 
be closed cells, and thus there is virtually no path open from one side of 
the voided-core to the other side through which gas or liquid can 
traverse. 
The void-initiating material may be selected from a variety of materials, 
and should be present in an amount of about 5 to 50% by weight based on 
the weight of the core matrix polymer. Preferably, the void-initiating 
material comprises a polymeric material. When a polymeric material is 
used, it may be a polymer that can be melt-mixed with the polymer from 
which the core matrix is made and be able to form dispersed spherical 
particles as the suspension is cooled down. Examples of this would include 
nylon dispersed in polypropylene, polybutylene terephthalate in 
polypropylene, or polypropylene dispersed in polyethylene terephthalate. 
If the polymer is preshaped and blended into the matrix polymer, the 
important characteristic is the size and shape of the particles. Spheres 
are preferred and they can be hollow or solid. These spheres may be made 
from cross-linked polymers which are members selected from the group 
consisting of an alkenyl aromatic compound having the general formula 
Ar--C(R).dbd.CH.sub.2, wherein Ar represents an aromatic hydrocarbon 
radical, or an aromatic halohydrocarbon radical of the benzene series and 
R is hydrogen or the methyl radical; acrylate-type monomers include 
monomers of the formula CH.sub.2 .dbd.C(R')--C(O)(OR) wherein R is 
selected from the group consisting of hydrogen and an alkyl radical 
containing from about 1 to 12 carbon atoms and R' is selected from the 
group consisting of hydrogen and methyl; copolymers of vinyl chloride and 
vinylidene chloride, acrylonitrile and vinyl chloride, vinyl bromide, 
vinyl esters having formula CH.sub.2 .dbd.CH(O)COR, wherein R is an alkyl 
radical containing from 2 to 18 carbon atoms; acrylic acid, methacrylic 
acid, itaconic acid, citraconic acid, maleic acid, fumaric acid, oleic 
acid, vinylbenzoic acid; the synthetic polyester resins which are prepared 
by reacting terephthalic acid and dialkyl terephthalics or ester-forming 
derivatives thereof, with a glycol of the series HO(CH.sub.2).sub.n OH 
wherein n is a whole number within the range of 2-10 and having reactive 
olefinic linkages within the polymer molecule, the above described 
polyesters which include copolymerized therein up to 20 percent by weight 
of a second acid or ester thereof having reactive olefinic unsaturation 
and mixtures thereof, and a cross-linking agent selected from the group 
consisting of divinylbenzene, diethylene glycol dimethacrylate, diallyl 
fumarate, diallyl phthalate and mixtures thereof. 
Examples of typical monomers for making the crosslinked polymer include 
styrene, butyl acrylate, acrylamide, acrylonitrile, methyl methacrylate, 
ethylene glycol dimethacrylate, vinyl pyridine, vinyl acetate, methyl 
acrylate, vinylbenzyl chloride, vinylidene chloride, acrylic acid, 
divinylbenzene, acrylamidomethyl-propane sulfonic acid, vinyl toluene, 
etc. Preferably, the cross-linked polymer is polystyrene or poly(methyl 
methacrylate). Most preferably, it is polystyrene and the cross-linking 
agent is divinylbenzene. 
Processes well known in the art yield non-uniformly sized particles, 
characterized by broad particle size distributions. The resulting beads 
can be classified by screening the beads spanning the range of the 
original distribution of sizes. Other processes such as suspension 
polymerization, limited coalescence, directly yield very uniformly sized 
particles. 
The void-initiating materials may be coated with agents to facilitate 
voiding. Suitable agents or lubricants include colloidal silica, colloidal 
alumina, and metal oxides such as tin oxide and aluminum oxide. The 
preferred agents are colloidal silica and alumina, most preferably, 
silica. The cross-linked polymer having a coating of an agent may be 
prepared by procedures well known in the art. For example, conventional 
suspension polymerization processes wherein the agent is added to the 
suspension is preferred. As the agent, colloidal silica is preferred. 
The void-initiating particles can also be inorganic spheres, including 
solid or hollow glass spheres, metal or ceramic beads or inorganic 
particles such as clay, talc, barium sulfate, calcium carbonate. The 
important thing is that the material does not chemically react with the 
core matrix polymer to cause one or more of the following problems: (a) 
alteration of the crystallization kinetics of the matrix polymer, making 
it difficult to orient, (b) destruction of the core matrix polymer, (c) 
destruction of the void-initiating particles, (d) adhesion of the 
void-initiating particles to the matrix polymer, or (e) generation of 
undesirable reaction products, such as toxic or high color moieties. The 
void-initiating material should not be photographically active or degrade 
the performance of the photographic element in which the biaxially 
oriented polyolefin sheet is utilized. 
For the biaxially oriented sheet on the top side toward the emulsion and 
the back side of the base paper forming the laminated imaging substrate, 
suitable classes of thermoplastic polymers for the biaxially oriented 
sheet and the core matrix-polymer of the preferred composite sheet 
comprise polyolefins. 
Suitable polyolefins include polypropylene, polyethylene, 
polymethylpentene, polystyrene, polybutylene and mixtures thereof. 
Polyolefin copolymers, including copolymers of propylene and ethylene such 
as hexene, butene, and octene are also useful. Polypropylene is preferred, 
as it is low in cost and has desirable strength properties. 
The nonvoided skin layers of the composite sheet can be made of the same 
polymeric materials as listed above for the core matrix. The composite 
sheet can be made with skin(s) of the same polymeric material as the core 
matrix, or it can be made with skin(s) of different polymeric composition 
than the core matrix. For compatibility, an auxiliary layer can be used to 
promote adhesion of the skin layer to the core. 
Addenda may be added to the core matrix and/or to the skins to improve the 
whiteness of these sheets. This would include any process which is known 
in the art including adding a white pigment, such as titanium dioxide, 
barium sulfate, clay, or calcium carbonate. This would also include adding 
fluorescing agents which absorb energy in the UV region and emit light 
largely in the blue region, or other additives which would improve the 
physical properties of the sheet or the manufacturability of the sheet. 
For photographic use, a white base with a slight bluish tint is preferred. 
The coextrusion, quenching, orienting, and heat setting of these composite 
sheets may be effected by any process which is known in the art for 
producing oriented sheet, such as by a flat sheet process or a bubble or 
tubular process. The flat sheet process involves extruding the blend 
through a slit die and rapidly quenching the extruded web upon a chilled 
casting drum so that the core matrix polymer component of the sheet and 
the skin components(s) are quenched below their glass solidification 
temperature. The quenched sheet is then biaxially oriented by stretching 
in mutually perpendicular directions at a temperature above the glass 
transition temperature, below the melting temperature of the matrix 
polymers. The sheet may be stretched in one direction and then in a second 
direction or may be simultaneously stretched in both directions. After the 
sheet has been stretched, it is heat set by heating to a temperature 
sufficient to crystallize or anneal the polymers while restraining to some 
degree the sheet against retraction in both directions of stretching. 
The composite sheet, while described as having preferably at least three 
layers of a microvoided core and a skin layer on each side, may also be 
provided with additional layers that may serve to change the properties of 
the biaxially oriented sheet. A different effect may be achieved by 
additional layers. Such layers might contain tints, antistatic materials, 
or different void-making materials to produce sheets of unique properties. 
Biaxially oriented sheets could be formed with surface layers that would 
provide an improved adhesion, or look to the support and photographic 
element. The biaxially oriented extrusion could be carried out with as 
many as layers if desired to achieve some particular desired property. 
These composite sheets may be coated or treated after the coextrusion and 
orienting process or between casting and full orientation with any number 
of coatings which may be used to improve the properties of the sheets 
including printability, to provide a vapor barrier, to make them heat 
sealable, or to improve the adhesion to the support or to the photo 
sensitive layers. Examples of this would be acrylic coatings for 
printability, coating polyvinylidene chloride for heat seal properties. 
Further examples include flame, plasma or corona discharge treatment to 
improve printability or adhesion. 
By having at least one nonvoided skin on the microvoided core, the tensile 
strength of the sheet is increased and makes it more manufacturable. It 
allows the sheets to be made at wider widths and higher draw ratios than 
when sheets are made with all layers voided. Coextruding the layers 
further simplifies the manufacturing process. 
The structure of a typical biaxially oriented, microvoided sheet of the 
invention is as follows: 
##EQU3## 
The sheet on the side of the base paper opposite to the emulsion layers may 
be any suitable sheet. The sheet may or may not be microvoided. It may 
have the same composition as the sheet on the top side of the paper 
backing material. Biaxially oriented sheets are conveniently manufactured 
by coextrusion of the sheet, which may contain several layers, followed by 
biaxial orientation. Such biaxially oriented sheets are disclosed in, for 
example, U.S. Pat. No. 4,764,425, the disclosure of which is incorporated 
for reference. 
The preferred biaxially oriented sheet is a biaxially oriented polyolefin 
sheet, most preferably a sheet of polyethylene or polypropylene. The 
thickness of the biaxially oriented sheet should be from 10 to 150 
microns. Below 15 microns, the sheets may not be thick enough to minimize 
any inherent non-planarity in the support and would be more difficult to 
manufacture. At thicknesses higher than 70 microns, little improvement in 
either surface smoothness or mechanical properties are seen, and so there 
is little justification for the further increase in cost for extra 
materials. 
Suitable classes of thermoplastic polymers for the biaxially oriented sheet 
include polyolefins, polyesters, polyamides, polycarbonates, cellulosic 
esters, polystyrene, polyvinyl resins, polysulfonamides, polyethers, 
polyimides, polyvinylidene fluoride, polyurethanes, polyphenylenesulfides, 
polytetrafluoroethylene, polyacetals, polysulfonates, polyester ionomers, 
and polyolefin ionomers. Copolymers and/or mixtures of these polymers can 
be used. 
Suitable polyolefins include polypropylene, polyethylene, 
polymethylpentene, and mixtures thereof. Polyolefin copolymers, including 
copolymers of propylene and ethylene such as hexene, butene and octene are 
also useful. Polypropylenes are preferred because they are low in cost and 
have good strength and surface properties. 
Suitable polyesters include those produced from aromatic, aliphatic or 
cycloaliphatic dicarboxylic acids of 4-20 carbon atoms and aliphatic or 
alicyclic glycols having from 2-24 carbon atoms. Examples of suitable 
dicarboxylic acids include terephthalic, isophthalic, phthalic, 
naphthalene dicarboxylic acid, succinic, glutaric, adipic, azelaic, 
sebacic, fumaric, maleic, itaconic, 1,4-cyclohexanedicarboxylic, 
sodiosulfoisophthalic and mixtures thereof. Examples of suitable glycols 
include ethylene glycol, propylene glycol, butanediol, pentanediol, 
hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, other 
polyethylene-glycols and mixtures thereof. Such polyesters are well known 
in the art and may be produced by well known techniques, e.g., those 
described in U.S. Pat. No. 2,465,319 and U.S. Pat. No. 2,901,466. 
Preferred continuous matrix polyesters are those having repeat units from 
terephthalic acid or naphthalene dicarboxylic acid and at least one glycol 
selected from ethylene glycol, 1,4-butanediol and 
1,4-cyclohexanedimethanol. Poly(ethylene terephthalate), which may be 
modified by small amounts of other monomers, is especially preferred. 
Other suitable polyesters include liquid crystal copolyesters formed by 
the inclusion of suitable amount of a co-acid component such as stilbene 
dicarboxylic, acid. Examples of such liquid crystal copolyesters are those 
disclosed in U.S. Pat. Nos. 4,420,607, 4,459,402 and 4,468,510. 
Useful polyamides include nylon 6, nylon 66, and mixtures thereof. 
Copolymers of polyamides are also suitable continuous phase polymers. An 
example of a useful polycarbonate is bisphenol-A polycarbonate. Cellulosic 
esters suitable for use as the continuous phase polymer of the composite 
sheets include cellulose nitrate, cellulose triacetate, cellulose 
diacetate, cellulose acetate propionate, cellulose acetate butyrate, and 
mixtures or copolymers thereof. Useful polyvinyl resins include polyvinyl 
chloride, poly(vinyl acetal), and mixtures thereof. Copolymers of vinyl 
resins can also be utilized. 
The biaxially oriented sheet on the back side of the laminated base can be 
made with layers of the same polymeric material, or it can be made with 
layers of different polymeric composition. For compatibility, an auxiliary 
layer can be used to promote adhesion of multiple layers. 
Addenda may be added to the biaxially oriented sheet to improve the 
whiteness of these sheets. This would include any process which is known 
in the art including adding a white pigment, such as titanium dioxide, 
barium sulfate, clay, or calcium carbonate. This would also include adding 
fluorescing agents which absorb energy in the UV region and emit light 
largely in the blue region, or other additives which would improve the 
physical properties of the sheet or the manufacturability of the sheet. 
The coextrusion, quenching, orienting, and heat setting of these biaxially 
oriented sheets may be effected by any process which is known in the art 
for producing oriented sheet, such as by a flat sheet process or a bubble 
or tubular process. The flat sheet process involves extruding or 
coextruding the blend through a slit die and rapidly quenching the 
extruded or coextruded web upon a chilled casting drum so that the polymer 
component(s) of the sheet are quenched below their solidification 
temperature. The quenched sheet is then biaxially oriented by stretching 
in mutually perpendicular directions at a temperature above the glass 
transition temperature of the polymer(s). The sheet may be stretched in 
one direction and then in a second direction or may be simultaneously 
stretched in both directions. After the sheet has been stretched, it is 
heat set by heating to a temperature sufficient to crystallize the 
polymers while restraining to some degree the sheet against retraction in 
both directions of stretching. 
The biaxially oriented sheet on the back side of the laminated base, while 
described as-having preferably at least one layer, may also be provided 
with additional layers that may serve to change the properties of the 
biaxially oriented sheet. A different effect may be achieved by additional 
layers. Such layers might contain tints, antistatic materials, or slip 
agents to produce sheets of unique properties. Biaxially oriented sheets 
could be formed with surface layers that would provide an improved 
adhesion, or look to the support and photographic element. The biaxially 
oriented extrusion could be carried out with as many as 10 layers if 
desired to achieve some particular desired property. 
These biaxially oriented sheets may be coated or treated after the 
coextrusion and orienting process or between casting and full orientation 
with any number of coatings which may be used to improve the properties of 
the sheets including printability, to provide a vapor barrier, to make 
them heat sealable, or to improve the adhesion to the support or to the 
photo sensitive layers. Examples of this would be acrylic coatings for 
printability, coating polyvinylidene chloride for heat seal properties. 
Further examples include flame, plasma or corona discharge treatment to 
improve printability or adhesion. 
The structure of a typical biaxially oriented sheet of the invention is as 
follows: 
##EQU4## 
The support to which the microvoided composite sheets and biaxially 
oriented sheets are laminated for the laminated support of the 
photosensitive silver halide layer may be a polymeric, a synthetic paper, 
cloth, woven polymer fibers, or a cellulose fiber paper support, or 
laminates thereof. The base also may be a microvoided polyethylene 
terephalate such as disclosed in U.S. Pat. Nos. 4,912,333; 4,994,312 and 
5,055,371, the disclosure of which is incorporated for reference. 
The preferred support is a photographic grade cellulose fiber paper. When 
using a cellulose fiber paper support, it is preferable to extrusion 
laminate the microvoided composite sheets to the base paper using a 
polyolefin resin. Extrusion laminating is carried out by bringing together 
the biaxially oriented sheets of the invention and the base paper with 
application of an adhesive between them followed by their being pressed in 
a nip such as between two rollers. The adhesive may be applied to either 
the biaxially oriented sheets or the base paper prior to their being 
brought into the nip. In a preferred form the adhesive is applied into the 
nip simultaneously with both the biaxially oriented sheets and the base 
paper. The adhesive may be any suitable material that does not have a 
harmful effect upon the photographic element. A preferred material is 
polyethylene that is melted at the time it is placed into the nip between 
the paper and the biaxially oriented sheet. 
During the lamination process, it is desirable to maintain control of the 
tension of the biaxially oriented sheet(s) in order to minimize curl in 
the resulting laminated support. For high humidity applications (&gt;50% RH) 
and low humidity applications (&lt;20% RH), it is desirable to laminate both 
a front side and back side film to keep curl to a minimum. 
In one preferred embodiment, in order to produce photographic elements with 
a desirable photographic look and feel, it is preferable to use relatively 
thick paper supports (e.g., at least 120 .mu.m thick, preferably from 120 
to 250 .mu.m thick) and relatively thin microvoided composite sheets 
(e.g., less than 50 .mu.m thick, preferably from 20 to 50 .mu.m thick, 
more preferably from 30 to 50 .mu.m thick). 
The photographic elements can be single color elements or multicolor 
elements. Multicolor elements contain image dye-forming units sensitive to 
each of the three primary regions of the spectrum. Each unit can comprise 
a single emulsion layer or multiple emulsion layers sensitive to a given 
region of the spectrum. The layers of the element, including the layers of 
the image-forming units, can be arranged in various orders as known in the 
art. In an alternative format, the emulsions sensitive to each of the 
three primary regions of the spectrum can be disposed as a single 
segmented layer. 
The photographic emulsions useful for this invention are generally prepared 
by precipitating silver halide crystals in a colloidal matrix by methods 
conventional in the art. The colloid is typically a hydrophilic film 
forming agent such as gelatin, alginic acid, or derivatives thereof. 
The crystals formed in the precipitation step are washed and then 
chemically and spectrally sensitized by adding spectral sensitizing dyes 
and chemical sensitizers, and by providing a heating step during which the 
emulsion temperature is raised, typically from 40.degree. C. to 70.degree. 
C., and maintained for a period of time. The precipitation and spectral 
and chemical sensitization methods utilized in preparing the emulsions 
employed in the invention can be those methods known in the art. 
Chemical sensitization of the emulsion typically employs sensitizers such 
as: sulfur-containing compounds, e.g., allyl isothiocyanate, sodium 
thiosulfate and allyl thiourea; reducing agents, e.g., polyamines and 
stannous salts; noble metal compounds, e.g., gold, platinum; and polymeric 
agents, e.g., polyalkylene oxides. As described, heat treatment is 
employed to complete chemical sensitization. Spectral sensitization is 
effected with a combination of dyes, which are designed for the wavelength 
range of interest within the visible or infrared spectrum. It is known to 
add such dyes both before and after heat treatment. 
After spectral sensitization, the emulsion is coated on a support. Various 
coating techniques include dip coating, air knife coating, curtain coating 
and extrusion coating. 
The silver halide emulsions utilized in this invention may be comprised of 
any halide distribution. Thus, they may be comprised of silver chloride, 
silver chloroiodide, silver bromide, silver bromochloride, silver 
chlorobromide, silver iodochloride, silver iodobromide, silver 
bromoiodochloride, silver chloroiodobromide, silver iodobromochloride, and 
silver iodochlorobromide emulsions. It is preferred, however, that the 
emulsions be predominantly silver chloride emulsions. By predominantly 
silver chloride, it is meant that the grains of the emulsion are greater 
than about 50 mole percent silver chloride. Preferably, they are greater 
than about 90 mole percent silver chloride; and optimally greater than 
about 95 mole percent silver chloride. 
The silver halide emulsions can contain grains of any size and morphology. 
Thus, the grains may take the form of cubes, octahedrons, 
cubo-octahedrons, or any of the other naturally occurring morphologies of 
cubic lattice type silver halide grains. Further, the grains may be 
irregular such as spherical grains or tabular grains. Grains having a 
tabular or cubic morphology are preferred. 
The photographic elements of the invention may utilize emulsions as 
described in The Theory of the Photographic Process, Fourth Edition, T. H. 
James, Macmillan Publishing Company, Inc., 1977, pages 151-152. Reduction 
sensitization has been known to improve the photographic sensitivity of 
silver halide emulsions. While reduction sensitized silver halide 
emulsions generally exhibit good photographic speed, they often suffer 
from undesirable fog and poor storage stability. 
Reduction sensitization can be performed intentionally by adding reduction 
sensitizers, chemicals which reduce silver ions to form metallic silver 
atoms, or by providing a reducing environment such as high pH (excess 
hydroxide ion) and/or low pAg (excess silver ion). During precipitation of 
a silver halide emulsion, unintentional reduction sensitization can occur 
when, for example, silver nitrate or alkali solutions are added rapidly or 
with poor mixing to form emulsion grains. Also, precipitation of silver 
halide emulsions in the presence of ripeners (grain growth modifiers) such 
as thioethers, selenoethers, thioureas, or ammonia tends to facilitate 
reduction sensitization. 
Examples of reduction sensitizers and environments which may be used during 
precipitation or spectral/chemical sensitization to reduction sensitize an 
emulsion include ascorbic acid derivatives; tin compounds; polyamine 
compounds; and thiourea dioxide-based compounds described in U.S. Pat. 
Nos. 2,487,850; 2,512,925; and British Patent 789,823. Specific examples 
of reduction sensitizers or conditions, such as dimethylamineborane, 
stannous chloride, hydrazine, high pH (pH 8-11) and low pAg (pAg 1-7) 
ripening are discussed by S.Collier in Photographic Science and 
Engineering, 23,113 (1979). Examples of processes for preparing 
intentionally reduction sensitized silver halide emulsions are described 
in EP 0 348934 A1 (Yamashita), EP 0 369491 (Yamashita), EP 0 371388 
(Ohashi), EP 0 396424 A1 (Takada), EP 0 404142 A1 (Yamada), and EP 0 
435355 A1 (Makino). 
The photographic elements of this invention may use emulsions doped with 
Group VIII metals such as iridium, rhodium, osmium, and iron as described 
in Research Disclosure, September 1994, Item 36544, Section I, published 
by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North Street, 
Emsworth, Hampshire PO10 7DQ, ENGLAND. Additionally, a general summary of 
the use of iridium in the sensitization of silver halide emulsions is 
contained in Carroll, "Iridium Sensitization: A Literature Review," 
Photographic Science and Engineering, Vol. 24, No. 6, 1980. A method of 
manufacturing a silver halide emulsion by chemically sensitizing the 
emulsion in the presence of an iridium salt and a photographic spectral 
sensitizing dye is described in U.S. Pat. No. 4,693,965. In some cases, 
when such dopants are incorporated, emulsions show an increased fresh fog 
and a lower contrast sensitometric curve when processed in the color 
reversal E-6 process as described in The British Journal of Photography 
Annual, 1982, pages 201-203. 
A typical multicolor photographic element of the invention comprises the 
invention laminated support bearing a cyan dye image-forming unit 
comprising at least one red-sensitive silver halide emulsion layer having 
associated therewith at least one cyan dye-forming coupler; a magenta 
image-forming unit comprising at least one green-sensitive silver halide 
emulsion layer having associated therewith at least one magenta 
dye-forming coupler; and a yellow dye image-forming unit comprising at 
least one blue-sensitive silver halide emulsion layer having associated 
therewith at least one yellow dye-forming coupler. The element may contain 
additional layers, such as filter layers, interlayers, overcoat layers, 
subbing layers, and the like. The support of the invention may also be 
utilized for black and white photographic print elements. 
The photographic elements may also contain a transparent magnetic recording 
layer such as a layer containing magnetic particles on the underside of a 
transparent support, as in U.S. Pat. Nos. 4,279,945 and 4,302,523. 
Typically, the element will have a total thickness (excluding the support) 
of from about 5 to about 30 microns. 
In the following Table, reference will be made to (1) Research Disclosure, 
December 1978, Item 17643, (2) Research Disclosure, December 1989, Item 
308119, and (3) Research Disclosure, September 1996, Item 38957, all 
published by Kenneth Mason Publications, Ltd., Dudley Annex, 12a North 
Street, Emsworth, Hampshire PO10 7DQ, ENGLAND. The Table and the 
references cited in the Table are to be read as describing particular 
components suitable for use in the elements of the invention. The Table 
and its cited references also describe suitable ways of preparing, 
exposing, processing and manipulating the elements, and the images 
contained therein. 
______________________________________ 
Reference Section Subject Matter 
______________________________________ 
1 I, II Grain composition, 
2 I, II, IX, X, 
morphology and 
XI, XII, preparation. Emulsion 
XIV, XV preparation including 
I, II, III, IX 
hardeners, coating aids, 
3 A & B addenda, etc. 
1 III, IV Chemical sensitization and 
2 III, IV spectral sensitization/ 
3 IV, V desensitization 
1 V UV dyes, optical 
2 V brighteners, luminescent 
3 VI dyes 
1 VI Antifoggants and stabilizers 
2 VI 
3 VII 
1 VIII Absorbing and scattering 
2 VIII, XIII, materials; Antistatic layers; 
XVI matting agents 
3 VIII, IX C 
& D 
1 VII Image-couplers and image- 
2 VII modifying couplers; Dye 
3 X stabilizers and hue 
modifiers 
1 XVII Supports 
2 XVII 
3 XV 
3 XI Specific layer arrangements 
3 XII, XIII Negative working 
emulsions; Direct positive 
emulsions 
2 XVIII Exposure 
3 XVI 
1 XIX, XX Chemical processing; 
2 XIX, XX, Developing agents 
XXII 
3 XVIII, XIX, 
XX 
3 XIV Scanning and digital 
processing procedures 
______________________________________ 
The photographic elements can be exposed with various forms of energy which 
encompass the ultraviolet, visible, and infrared regions of the 
electromagnetic spectrum as well as with electron beam, beta radiation, 
gamma radiation, x-ray, alpha particle, neutron radiation, and other forms 
of corpuscular and wave-like radiant energy in either noncoherent (random 
phase) forms or coherent (in phase) forms, as produced by lasers. When the 
photographic elements are intended to be exposed by x-rays, they can 
include features found in conventional radiographic elements. 
The photographic elements are preferably exposed to actinic radiation, 
typically in the visible region of the spectrum, to form a latent image, 
and then processed to form a visible image, preferably by other than heat 
treatment. Processing is preferably carried out in the known RA-4.TM. 
(Eastman Kodak Company) Process or other processing systems suitable for 
developing high chloride emulsions. 
The laminated substrate of the invention may have copy restriction features 
incorporated such as disclosed in U.S. patent application Ser. No. 
08/598,785 filed Feb. 8, 1996 and application Ser. No. 08/598,778 filed on 
the same day. These applications disclose rendering a document copy 
restrictive by embedding into the document a pattern of invisible 
microdots. These microdots are, however, detectable by the electro-optical 
scanning device of a digital document copier. The pattern of microdots may 
be incorporated throughout the document. Such documents may also have 
colored edges or an invisible microdot pattern on the back side to enable 
users or machines to read and identify the media. The media may take the 
form of sheets that are capable of bearing an image. Typical of such 
materials are photographic paper and film materials composed of 
polyethylene resin coated paper, polyester, (poly)ethylene naphthalate, 
and cellulose triacetate based materials. 
The microdots can take any regular or irregular shape with a size smaller 
than the maximum size at which individual microdots are perceived 
sufficiently to decrease the usefulness of the image, and the minimum 
level is defined by the detection level of the scanning device. The 
microdots may be distributed in a regular or irregular array with 
center-to-center spacing controlled to avoid increases in document 
density. The microdots can be of any hue, brightness, and saturation that 
does not lead to sufficient detection by casual observation, but 
preferably of a hue least resolvable by the human eye, yet suitable to 
conform to the sensitivities of the document scanning device for optimal 
detection. 
In one embodiment the information-bearing document is comprised of a 
support, an image-forming layer coated on the support and pattern of 
microdots positioned between the support and the image-forming layer to 
provide a copy restrictive medium. Incorporation of the microdot pattern 
into the document medium can be achieved by various printing technologies 
either before or after production of the original document. The microdots 
can be composed of any colored substance, although depending on the nature 
of the document, the colorants may be translucent, transparent, or opaque. 
It is preferred to locate the microdot pattern on the support layer prior 
to application of the protective layer, unless the protective layer 
contains light scattering pigments. Then the microdots should be located 
above such layers and preferably coated with a protective layer. The 
microdots can be composed of colorants chosen from image dyes and filter 
dyes known in the photographic art and dispersed in a binder or carrier 
used for printing inks or light-sensitive media. 
In a preferred embodiment the creation of the microdot pattern as a latent 
image is possible through appropriate temporal, spatial, and spectral 
exposure of the photosensitive materials to visible or non-visible 
wavelengths of electromagnetic radiation. The latent image microdot 
pattern can be rendered detectable by employing standard photographic 
chemical processing. The microdots are particularly useful for both color 
and black-and-white image-forming photographic media. Such photographic 
media will contain at least one silver halide radiation sensitive layer, 
although typically such photographic media contain at least three silver 
halide radiation sensitive layers. It is also possible that such media 
contain more than one layer sensitive to the same region of radiation. The 
arrangement of the layers may take any of the forms known to one skilled 
in the art, as discussed in Research Disclosure 37038 of February 1995. 
The following examples illustrate the practice of this invention. They are 
not intended to be exhaustive of all possible variations of the invention. 
Parts and percentages are by weight unless otherwise indicated. Examples 
1-5 are general examples of laminated base materials. The higher number 
examples better illustrate the invention as herein claimed. 
Commercial Grade Paper of Examples 
A photographic paper support was produced by refining a pulp furnish of 50% 
bleached hardwood kraft, 25% bleached hardwood sulfite, and 25% bleached 
softwood sulfite through a double disk refiner, then a Jordan conical 
refiner to a Canadian Standard Freeness of 200 cc. To the resulting pulp 
furnish was added 0.2% alkyl ketene dimer, 1.0% dationic cornstarch, 0.5% 
polyamide-epichlorohydrin, 0.26 anionic polyacrylamide, and 5.0% TiO.sub.2 
on a dry weight basis. An about 46.5 lbs. per 1000 sq. ft. (ksf) bone dry 
weight base paper was made on a fourdrinier paper machine, wet pressed to 
a solid of 42%, and dried to a moisture of 10% using steam-heated dryers 
achieving a Sheffield Porosity of 160 Sheffield Units and an apparent 
density 0.70 g/cc. The paper base was then surface sized using a vertical 
size press with a 10% hydroxyethylated cornstarch solution to achieve a 
loading of 3.3 wt. % starch. The surface sized support was calendered to 
an apparent density of 1.04 gm/cc.

EXAMPLES 
Example 1 
The following laminated photographic base was prepared by extrusion 
laminating the following sheets to both sides of a photographic grade 
cellulose paper support: 
Top sheet: (Emulsion side) 
OPPalyte 350 TW (Mobil Chemical Co.) 
A composite sheet (38 .mu.m thick) (d=0.62 g/cc) consisting of a 
microvoided and oriented polypropylene core (approximately 73% of the 
total sheet thickness), with a titanium dioxide pigmented non-microvoided 
oriented polypropylene layer on each side; the void initiating material is 
poly(butylene terephthalate). 
Bottom sheet: (Back side) 
BICOR 70 MLT (Mobil Chemical Co.) 
A one-side matte finish, one-side treated polypropylene sheet (18 .mu.m 
thick) (d=0.9 g/cc) consisting of a solid oriented polypropylene core. 
Both the above top and bottom sheets were extrusion laminated to a 
photographic grade cellulose paper support with a clear polyolefin (25 
g/m.sup.2). 
This laminated support was then coated with a color photosensitive silver 
halide layer. 
To evaluate curl of the above photographic element the Kodak Curl Test was 
used. 
This test measures the amount of curl in a parabolically deformed sample. A 
8.5 cm diameter round sample of the composite was stored at the test 
humidity for 21 days. The amount of time required depends on the vapor 
barrier properties of the laminates applied to the moisture sensitive 
paper base, and it should be adjusted as necessary by determining the time 
to equilibrate the weight of the sample in the test humidity. The curl 
readings are expressed in ANSI curl units, specifically, 100 divided by 
the radius of curvature in inches. 
The radius of curvature is determined by visually comparing the curled 
shape, sighting along the axis of curl, with standard curves in the 
background. The standard deviation of the test is 2 curl units. The curl 
may be positive or negative, and for photographic products, the usual 
convention is that the positive direction is curling towards the 
photosensitive layer. 
The curl results for Example 1 are presented in Table I below: 
TABLE I 
______________________________________ 
curl units 100/r 
% Humidity Control Example 1 
______________________________________ 
5 22 12 
20 6 4 
50 -7 -1 
85 -18 2 
______________________________________ 
The data above show that photographic grade cellulose paper, when extrusion 
laminated on both sides with a biaxially oriented sheet, is superior for 
photographic paper curl compared to photographic bases used for related 
prior art bases. 
Example 2 
The following laminated photographic base was prepared by extrusion 
laminating the following sheets to both sides a photographic grade 
cellulose paper support: 
Top sheet: (Emulsion side) 
PF1. OPPalyte 350 TW (Mobil Chemical Co.). 
A composite sheet (38 .mu.m thick) (d=0.50 g/cc) consisting of a 
microvoided and oriented polypropylene core (approximately 73% of the 
total sheet thickness), with a titanium dioxide pigmented non-microvoided 
oriented polypropylene layer on each side; the void initiating material is 
poly(butylene terephthalate). 
PF2. OPPalyte 350 TW (Mobil Chemical Co.) 
A composite sheet (38 .mu.m thick) (d=0.70 g/cc) consisting of a 
microvoided and oriented polypropylene core (approximately 73% of the 
total sheet thickness), with a titanium dioxide pigmented non-microvoided 
oriented polypropylene layer on each side; the void initiating material is 
poly(butylene terephthalate). 
PF3. OPPalyte 350 TW (Mobil Chemical Co.) 
A composite sheet (38 .mu.m thick) (d=0.90 g/cc) consisting of a solid and 
oriented polypropylene sheet. 
Bottom sheet: 
BICOR 70 MLT (Mobil Chemical Co.) 
A one-side matte finish, one-side treated polypropylene sheet (18 .mu.m 
thick) (d=0.9 g/cc) consisting of a solid oriented polypropylene core. 
The following three samples were made by extrusion laminating to a 
photographic grade cellulose paper support with a clear polyolefin (25 
g/m.sup.2): 
Support A: PF1 top sheet and 70 MLT bottom sheet 
Support B: PF2 top sheet and 70 MLT bottom sheet 
Support C: PF3 top sheet and 70 MLT bottom sheet 
To evaluate the opacity of the above photographic elements the Hunter 
spectrophotometer CIE system D65 was used to perform a standard opacity 
test. In this test a control sample consisting of a standard color 
photographic paper was used to compare the results. This opacity test uses 
a sample cut to 25.times.106 cm in size and measuring the opacity of the 
samples. The percent opacity was calculated as follows: 
##EQU5## 
where sample opacity equals the measured opacity for the support samples 
and the control opacity equals the opacity of standard color photographic 
support. The results are presented in Table II below: 
TABLE II 
______________________________________ 
Opacity Improvement Data Table 
Support 
% Opacity 
______________________________________ 
Support A 
103.40% 
Support B 
100.50% 
Support C 
98.20% 
Control 
100% 
______________________________________ 
The data above show by that extrusion laminating microvoided biaxially 
oriented sheets (in the case of Support A and Support B) to standard 
cellulose photographic paper, the opacity of the photographic support is 
superior compared to photographic supports used for related prior art 
supports. The Support C being non-microvoided has less opacity. This 
demonstrates the superior opacity of microvoided Supports A and B when 
compared to the control. Support C would be satisfactory for uses where 
opacity was not of prime importance such as when it is overcoated with 
titanium dioxide but still achieves the benefits of increased resistance 
to curl and improved image quality. 
Example 3 
The following laminated photographic base was prepared by extrusion 
laminating the following sheets to both sides of a photographic grade 
cellulose paper support. 
Top sheet: 
OPPalyte 350 TW (Mobil Chemical Co.) 
A composite sheet (38 .mu.m thick) (d=0.75 g/cc) consisting of a 
microvoided and oriented polypropylene core (approximately 73% of the 
total sheet thickness), with a titanium dioxide pigmented system 
(including required color adjustment) non-microvoided oriented 
polypropylene layer on the one side and a clear non-microvoided oriented 
polypropylene layer side; the void initiating material is poly(butylene 
terephthalate). 
Bottom sheet: 
BICOR 70 MLT (Mobil Chemical Co.) 
A one-side matte finish, one-side treated polypropylene sheet (18 .mu.m 
thick) (d=0.9 g/cc) consisting of a solid oriented polypropylene core. 
Both the above top and bottom sheets were extrusion laminated to a 
photographic grade cellulose paper support with a clear polyolefin (25 
g/m.sup.2). 
It was not necessary to coat this laminated support with a color 
photosensitive silver halide layer, since the whiteness is measured before 
other photosensitive layers are added. 
To evaluate whiteness of the above photographic element, The HUNTER 
spectrophotometer CIE system D65 procedure was used to measure L Star UVO 
(ultraviolet filter out). In this test a control sample consisting of a 
standard color photographic paper was used to compare results. L Star UVO 
values of 92.95 are considered normal. The results for the example were 
93.49, a significant change in the desirable direction. 
The data above show that photographic grade cellulose paper, when extrusion 
laminated on both sides with a biaxially oriented sheet, is superior for 
photographic whiteness compared to photographic bases used for related 
prior art bases. 
Example 4 
The following laminated photographic base was prepared by extrusion 
laminating the following sheets to both sides of a photographic grade 
cellulose paper support. 
Top sheet: 
OPPalyte 350 TW (Mobil Chemical Co.) 
A composite sheet (38 .mu.m thick) (d=0.62 g/cc) consisting of a 
microvoided and oriented polypropylene core (approximately 73% of the 
total sheet thickness), with a titanium dioxide pigmented non-microvoided 
oriented polypropylene layer on each side; the void initiating material is 
poly(butylene terephthalate). 
Bottom sheet: 
BICOR 70 MLT (Mobil Chemical Co.) 
A one-side matte finish, one-side treated polypropylene sheet (18 .mu.m 
thick) (d=0.9 g/cc) consisting of a solid oriented polypropylene core. 
The assembled structure has demonstrated superior tear resistance over 
other paper base structures that are coated with polyethylene or other 
polyolefins. 
To evaluate tear resistance, the above structure and control samples of 
standard color support were tested by Elmendorf Tear testing using TAPPI 
Method 414. The results are given in the Table III below. 
TABLE III 
______________________________________ 
Elmendorf Tear Improvement by Laminating BOPP* vs. Extrusion 
Coating Polyethylene 
Control Lam. w BOPP 
% Change 
______________________________________ 
Mach. Direction 
99 122 23 
Cross Direction 
110 151 37 
______________________________________ 
*BOPP is Biaxially Oriented Polypropylene 
The data above show that photographic grade cellulose paper, when extrusion 
laminated on both sides with a biaxially oriented sheet, is superior for 
photographic base tear resistance as compared to photographic bases used 
for related prior art bases. 
Example 5 
Yellow emulsion YE1 was prepared by adding approximately equimolar silver 
nitrate and sodium chloride solutions into a well-stirred reactor 
containing gelatin peptizer and thioether ripener. Cesium 
pentachloronitrosylosmate was added from 1% to 70% of the making process, 
and potassium iodide was added at 93% of the making process to form a band 
of silver iodide in the grain. The resultant emulsion contained cubic 
shaped grains of 0.60 .mu.m in edge length size. This emulsion was 
optimally sensitized by the addition of glutarydiaminophenylsulfide 
followed by the addition of a colloidal suspension of aurous sulfide and 
heat ramped to 60.degree. C. during which time blue sensitizing dye, Dye 
1, potassium hexachloroiridate, Lippmann bromide, and 
1-(3-acetamidophenyl)-5-mercaptotetrazole were added. 
Magenta emulsion ME1 was precipitated by adding approximately equimolar 
silver nitrate and sodium chloride solutions into a well-stirred reactor 
containing gelatin peptizer and thioether ripener. The resultant emulsion 
contained cubic shaped grains of 0.30 .mu.m in edge length size. This 
emulsion was optimally sensitized by the addition of a colloidal 
suspension of aurous sulfide and heated to 55.degree. C. The following 
were then added: potassium hexachloroiridate, Lippmann bromide, and green 
sensitizing dye, Dye 2. The finished emulsion was then allowed to cool, 
and 1-(3-acetamidophenyl(-5-mercaptotetrazole was added a few seconds 
after the cool down began. 
Cyan emulsion CE1 was precipitated by adding approximately equimolar silver 
nitrate and sodium chloride solutions into a well-stirred reactor 
containing gelatin peptizer and thioether ripener. In addition, mercury 
was added during the make. The resultant emulsion contained cubic shaped 
grains of 0.40 .mu.m in edge length size. This emulsion was optimally 
sensitized by the addition of 
Bis(1,4,5-trimethyl-1,2,4-triazolium-3-thiolate)gold(I)fluoroborate and 
sodium thiosulfate followed by heat digestion at 65.degree. C. The 
following were then added: 1-(3-acetamidophenyl)-5-mercaptotetrazole, 
potassium hexachloroiridate, and potassium bromide. The emulsion was 
cooled to 40.degree. C., and the red sensitizing dye, Dye 3, was added. 
Emulsions YE1, ME1, and CE1 were combined with coupler-bearing dispersions 
by techniques known in the art and applied to laminated base of Example 1 
according to the structure shown in Format 1 to prepare a photographic 
element of low curl and excellent strength characteristics. 
______________________________________ 
Format 1 
Item Description Laydown mg/ft.sup.2 
______________________________________ 
Layer 1 Blue Sensitive Layer 
Gelatin 122 
Yellow emulsion YE1 (as Ag) 
20 
Y-1 45 
ST-1 45 
S-1 20. 
Layer 2 Interlayer 
Gelatin 70 
SC-1 6. 
S-1 17 
Layer 3 Green Sensitive Layer 
Gelatin 117 
Magenta emulsion (as Ag) 
7 
M-1 29 
S-1 8 
S-2 3 
ST-2 2 
ST-3 17.7 
ST-4 57 
PMT 10 
Layer 4 UV Interlayer 
Gelatin 68.44 
UV-1 3 
UV-2 17 
SC-1 5.13 
S-1 3 
S-2 3 
Layer 5 Red Sensitive Layer 
Gelatin 126 
Cyan emulsion CE1 17 
C-1 39 
S-1 39 
UV-2 25 
S-2 3 
SC-1 0.3 
Layer 6 UV Overcoat 
Gelatin 48 
UV-1 2 
UV-2 12 
SC-1 4 
S-1 2 
S-3 2 
Layer 7 SOC 
Gelatin 60 
SC-1 2 
______________________________________ 
##STR1## 
Example 6 
The 10 samples below illustrate the formation of laminated base materials 
in accordance with the invention. The samples vary in the properties of 
the biaxially oriented sheets laminated to the same base paper. The 
caliper and modulus of the biaxially oriented sheets are varied. As will 
be apparent, the samples with the higher modulus and greatest thickness in 
combination yield the best roughness improvement for the laminated base 
material. 
1) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 13 microns thick and a modulus of 2800 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.58 microns, a 3.3% 
improvement. 
2) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 23 microns thick and a modulus of 3100 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.56 microns, a 6.7% 
improvement. 
3) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 33 microns thick and a modulus of 3100 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.52 microns, a 13% 
improvement. 
4) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
which 0.60 microns is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 13 microns thick and a modulus of 3800 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.53 microns, a 12% 
improvement. 
5) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.06 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 23 microns thick and a modulus of 3800 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.50 microns, a 17% 
improvement. 
6) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 33 microns thick and a modulus of 3800 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.43 microns, a 28% 
improvement. 
7) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that 13 micron thick and a modulus of 4500 MPa on 
the side to be coated with photographic emulsion or other image receiving 
layer and the back side coated with 27 g/m.sup.2 of medium density 
polyethylene. The resultant roughness was 0.34 microns, a 43% improvement. 
8) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 23 microns thick and a modulus of 4800 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.41 microns, a 32% 
improvement. 
9) a 171 g/m.sup.2 basis weight photographic raw base with an orange peel 
with a spatial frequency between 0.3 to 6.35 mm and roughness average of 
0.60 microns which is then extrusion laminated with a low density 
polyethylene of 12.2 g/m.sup.2 tie layer to adhere a sheet of biaxially 
oriented polypropylene that is 33 microns thick and a modulus of 5200 MPa 
on the side to be coated with photographic emulsion or other image 
receiving layer and the back side coated with 27 g/m.sup.2 of medium 
density polyethylene. The resultant roughness was 0.26 microns, a 57% 
improvement. 
10) A control structure of a 171 g/m.sup.2 basis weight photographic raw 
base with an orange peel with a spatial frequency between 0.3-6.35 mm and 
a roughness average of 0.6 microns which is extrusion coated with a 26 
micron layer of low density polyethylene at 207 MPa modulus. The resultant 
roughness average is 0.58 microns. 
TABLE IV 
______________________________________ 
Roughness 
Sample Modulus (Mpa) 
Caliper (microns) 
Average (microns) 
______________________________________ 
1 2800 13 .58 
2 3100 23 .56 
3 3100 33 0.52 
4 3800 13 0.53 
5 3800 23 0.50 
6 3800 33 0.43 
7 4500 13 0.41 
8 4800 23 0.34 
9 5200 33 0.26 
10 (control) 
207 26 0.58 
______________________________________ 
The data in the above table shows that the modulus of the film can reduce 
the orange peel of the raw stock from 3-57%. The impact of modulus is 
greater than that of higher film thickness. The orange peel dampening is 
further enhanced when done in combination with thicker films. This 
provides a cost effect means of making smoother surfaces from low grades 
of raw stock with enough latitude to tailor the combined effects while 
controlling the final thickness of the product. 
The above Table IV shows that as the biaxially oriented films become 
stronger and of higher caliper, the roughness of the resulting laminated 
base decreases as compared to the control sample 10 which is a 
polyethylene coated paper such as conventionally used in color 
photographic paper materials. Sample 9 is the best laminated base material 
as the roughness is the least and, therefore, if utilized in an imaging 
member would provide a smooth surface substantially free of orange peel. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.