Photographic elements containing reflective or diffusely transmissive supports

Disclosed are photographic elements having reflective or diffusely transmissive supports shaped from a continuous polyester phase having dispersed therein microbeads of cellulose acetate which are at least partially bordered by void space, the microbeads of cellulose acetate being poresent in an amount of about 10-30% by weight based on the weight of said polyester, said void space occupying about 2-50% by volume of said shaped article. Such articles have excellent physical properties.

TECHNICAL FIELD 
The present invention is directed to photographic elements having supports 
such as film supports having a polyester continuous phase containing 
cellulose ester microbeads dispersed therein which are at least partially 
bordered by voids. The supports have unique properties of texture, 
whiteness in the absence of colorants, diffuse transmission of light, and 
generally good physical properties such as tensile properties. 
BACKGROUND OF THE INVENTION 
Blends of linear polyesters with other incompatible materials of organic or 
inorganic nature to form microvoided structures are well-known in the art. 
U.S. Pat. No. 3,154,461 discloses, for example, the linear polyester, 
poly(ethylene terephthalate), blended with, for example, calcium 
carbonate. U.S. Pat. No. 3,944,699 discloses blends of linear polyester, 
preferably poly(ethylene terephthalate) with 3 to 27% of organic material 
such as ethylene or propylene polymer. U.S. Pat. No. 3,640,944 also 
discloses the use of poly(ethylene terephthalate) but blended with 8% 
organic material such as polysulfone or poly(4-methyl, 1-pentene). U.S. 
Pat. No. 4,377,616 discloses a blend of polypropylene to serve as the 
matrix with a small percentage of another and incompatible organic 
material, nylon, to initiate microvoiding in the polypropylene matrix. 
U.K. Patent Specification No. 1,563,591 discloses linear polyester 
polymers, and particularly poly(ethylene terephthalate), for making an 
opaque thermoplastic film support in which have been blended finely 
divided particles of barium sulfate together with a void-promoting 
polyolefin, such as polyethylene, polypropylene and 
poly-4-methyl-1-pentene. 
The above-mentioned patents show that it is known to use incompatible 
blends to form films having paper-like characteristics after such blends 
have been extruded into films and the films have been quenched, biaxially 
oriented and heat set. The minor component of the blend, due to its 
incompatibility with the major component of the blend, upon melt extrusion 
into film forms generally spherical particles each of which initiates a 
microvoid in the resulting matrix formed by the major component. The 
melting points of the void initiating particles, in the use of organic 
materials, should be above the glass transition temperature of the major 
component of the blend and particularly at the temperature of biaxial 
orientation. 
As indicated in U.S. Pat. No. 4,377,616, spherical particles initiate voids 
of unusual regularity and orientation in a stratified relationship 
throughout the matrix material after biaxial orientation of the extruded 
film. Each void tends to be of like shape, not necessarily of like size 
since the size depends upon the size of the particle. 
Ideally, each void assumes a shape 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 in correspondence with the direction of orientation 
of the film structure. One major dimension is aligned with machine 
direction orientation, a second major dimension is aligned with the 
transverse direction orientation, and a minor dimension approximately 
corresponds to the cross-section dimension of the void-initiating 
particle. 
The voids generally tend to be closed cells, and thus there is virtually no 
path open from one side of a biaxially oriented film to the other side 
through which liquid or gas can traverse. 
Upon biaxial orientation of the resulting extruded film, the film becomes 
white and opaque, the opacity resulting from light being scattered from 
the walls of the microvoids. The transmission of light through the film 
becomes lessened with increased number and with increased size of the 
microvoids relative to the size of a particle within each microvoid. 
Also, upon biaxial orientation, a matte finish on the surface of the film 
results, as discussed in U.S. Pat. No. 3,154,461. The particles adjacent 
the surfaces of the film tend to be incompressible and thus form 
projections without rupturing the surface. Such matte finishes enable the 
film to be written upon with pencil or with inks, crayons, and the like. 
Although the films discussed so far are generally white and opaque, 
suitable dyes may be used either in what will become the matrix polymer or 
in the void initiating particles. U.S. Pat. No. 4,377,616 points out that 
interesting effects can be achieved by the use of spheres of different 
colors or by the use of spheres of different color absorption or 
reflectance. The light scattered in a particular void may additionally 
either be absorbed or reflected by the void initiating sphere and a 
separate color contribution is made to the light scattering in each void. 
U.S. Pat. No. 4,377,616 discloses that preferred particle size of a void 
initiating sphere may be about 0.1 to about 10 microns, and that preferred 
particle size range from about 0.75 to about 2 microns. U.S. Pat. No. 
3,154,461 specifies that a range of sizes may be approximately 0.3 micron 
to approximately 20 microns, and that when calcium carbonate is used, its 
size may range from 1 to 5 microns. 
U.S. Pat. No. 3,944,699, for example, indicates that the linear polyester 
component of the film may comprise any thermoplastic film forming 
polyester which may be produced by condensing one or more dicarboxylic 
acids or a lower alkyl diester thereof, such as terephthalic acid, 
isophthalic acid, 2,5-,2,6- or 2,7-naphthalene dicarboxylic acid, succinic 
acid, sebacic acid, adipic acid, azelaic acid, bibenzoic acid, and 
hexahydroterephthalic acid, or bis-p-carboxy phenoxy ethane, with one or 
more glycols. Such glycols may include ethylene glycol, 1,3-propanediol, 
1,4-butanediol, neopentyl glycol, and 1,4-cyclohexanedimethanol. Also, a 
copolyester of any of the above-indicated materials may be used. The 
preferred polyester is poly(ethylene terephthalate). 
U.S. Pat. No. 3,944,699 also indicates that the extrusion, quenching and 
stretching of the film may be effected by any process which is known in 
the art for producing oriented film, such as by a flat film process or a 
bubble or tubular process. The flat film process involves extruding the 
blend through a slit dye and rapidly quenching the extruded web upon a 
chilled casting drum so that the polyester component of the film is 
quenched into the amorphous state. The quenched film is then biaxially 
oriented by stretching in mutually perpendicular directions at a 
temperature above the glass transition temperature of the polyester. The 
film may be stretched in one direction and then in a second direction or 
may be simultaneously stretched in both directions. After the film has 
been stretched it is heat set by heating to a temperature sufficient to 
crystallize the polyester while restraining the film against retraction in 
both directions of stretching. 
Paper is essentially a non-woven sheet of more or less randomly arrayed 
fibers. The key properties of these structures are opacity, texture, 
strength, and stability. Obviously, fiber technology evolved 
synergistically with paper, and today we have a variety of synthetic 
fibers and synthetic papers. In both areas, however, the synthetic 
materials have never quite matched the cellulose-based natural polymers, 
like cotton for fibers and cellulose pulps for papers. On the other hand, 
the natural polymers are generally weaker and less stable. A serious 
problem, for example, is brightness reversion or fading of papers and 
fibers. The present invention advances the state of these prior arts. 
Although there are many ways to produce opaque media, this invention is 
concerned with creating opacity by stretching or orienting plastic 
materials to induce microvoids which scatter light, preferably white 
light. A large body of prior art deals with this technique, wherein a 
plurality of inorganic solid particles are used as the dispersed phase, 
around which the microvoids form. Some significant problems associated 
with this approach are: (1) agglomeration and particle size control, (2) 
abrasive wear of extrusion equipment, guides, and cutters, (3) high 
specific gravity of these solids, (4) poor void nucleation around the 
solid particles due to the low thermal contraction of solids relative to 
liquids and polymer wetting and adhesion to the solid surfaces, (5) cost 
of these materials on a volume basis, and (6) handling and processing 
problems in general. In every case, the invention reduces or eliminates 
the problem. 
The prior art also teaches a variety of methods of creating surface 
texture. Often the surface is roughened by physical means like abrasion, 
crimping, etc. Many chemical methods are also used to react with, etch, or 
otherwise alter the surface. Flame, electrical corona, and electromagnetic 
radiations are often employed. Coating technology is well advanced for 
filling and whitening, and often inorganic materials are major components 
of these coatings. Even if the orientation or stretching step is 
eliminated, a coating step is required. Not only do most of the problems 
above remain, but new ones are created in such areas as adhesion, 
uniformity, and coating stability. 
The cited prior art concentrates on synthetic paper compositions and 
methods of manufacturing directly related to this invention, namely 
compositions of matter involving polyesters and/or cellulose esters, 
stretching incompatible/immiscible thermoplastic blends to create voided 
structures with or without texture, and some of the properties and 
problems associated with the use of inorganic, nonmelting materials. The 
blend compositions and processing methods of this invention constitute a 
significant improvement over the immiscible polymer blend systems found in 
the prior art. 
SUMMARY OF THE INVENTION 
In one aspect, this invention is directed to a photographic element 
comprised of a reflective or diffusely transmissive support and, coated on 
the support, at least one radiation-sensitive silver halide emulsion 
layer. The photographic element is characterized in that the support is 
comprised of a continuous polyester phase having dispersed therein 
microbeads of cellulose acetate which are at least partially bordered by 
void space, the microbeads of cellulose acetate being present in an amount 
of 10-30% by weight based on the weight of the polyester, the void space 
occupying 2-50% by volume of the support.

DESCRIPTION OF PREFERRED EMBODIMENTS 
A photographic element 10 satisfying the requirements of the invention is 
shown in FIG. 1. The photographic element is comprised of a support 12 and 
an imaging unit 14 coated on the support. The imaging unit is comprised of 
at least one radiation-sensitive silver halide emulsion layer. In the 
simplest form of the invention the imaging unit consists of a single 
silver halide emulsion layer. Black-and-white photographic elements, for 
example, often contain a single silver halide emulsion layer. 
Alternatively, the imaging unit can be comprised of a plurality of silver 
halide emulsion layers. For example, color photographic elements typically 
contain blue, green, and red color forming layer units. Each of these 
color forming layer units contains at least one silver halide emulsion 
layer. In the most elaborate commonly employed form each color forming 
layer unit contains three separate silver halide emulsion layers of 
similar spectral sensitivity within a single color forming layer unit, but 
differing in speed. 
As shown in FIG. 1 the photographic element is being imagewise exposed to 
radiation capable of producing a latent image in the silver halide 
emulsion layer or layers of the imaging unit. Exposing radiation, 
indicated by arrows 16a and 16b, strikes the imaging unit. Part of the 
incident radiation is absorbed in the imaging unit, with the remainder 
penetrating the imaging unit and striking the support, as indicated by 
arrows 18a and 18b. 
Because of the highly reflective nature of the support chosen for the 
photographic element, a very high percentage of the exposing radiation 
striking the support is reflected, as indicated by arrows 20a and 20b. The 
reflected radiation traverses the imaging unit a second time, where, 
again, it is in part absorbed. The unabsorbed radiation is indicated by 
arrows 22a and 22b. 
An important point to notice is that the reflective support allows exposing 
radiation to penetrate the imaging unit twice, almost doubling the 
opportunity for its absorption. This is in direct contrast to a 
photographic element having a transparent or absorptive support, which 
relies almost entirely on radiation producing a latent image in the 
imaging unit based on a single penetration of the imaging unit. Thus, with 
the same imaging unit a photographic element with a reflective support 
exhibits a higher photographic speed than a photographic element with a 
transmissive or absorptive support. 
The photographic elements of this invention exhibit higher effective speeds 
than photographic elements with comparable imaging units and conventional 
reflective supports, since the reflective supports which satisfy the 
requirements of this invention reflect a larger percentage of exposing 
radiation that impinges upon them, particularly when the wavelength of the 
exposing radiation is in the blue (400 to 500 nm) and near ultraviolet 
(280 to 400 nm) range. Very large increases in reflection as compared to 
conventional titania loaded reflective photographic supports are observed 
at exposing wavelengths of 450 nm or less. 
A portion of the exposing radiation incident on the support 12 is neither 
reflected nor absorbed, but is transmitted through the support. This 
portion of the radiation is not shown in FIG. 1, since it is possible to 
reduce transmitted radiation to a negligibly small portion of the total 
radiation while concurrently increasing reflected radiation by increasing 
the thickness of the support. 
However, it is another significant advantage of the photographic elements 
of this invention that they can be constructed with supports that are 
diffusely transmissive. This is illustrated by reference to FIG. 2. In 
FIG. 2 the photographic element 10 is shown after it has been imagewise 
exposed and processed to produce an image. To view the image formed in the 
imaging unit 14 one of two different modes of viewing can be undertaken. 
The first of these is reflection viewing, in which ambient light 
penetrates the imaging unit and is reflected by the support back toward 
the viewer's eyes. The support reflects uniformly, with the perceived 
image being a function of the modulation of the ambient light that occurs 
during its initial and reflection passages through the imaging unit. 
The second mode of viewing is transmission viewing. As shown in FIG. 2, an 
illumination source 30 directs light, indicated by arrows 32, to the 
support 12. While a portion of this light, not shown, is reflected by the 
support, a significant portion of the incident light enters the support 
and is diffusely transmitted. Diffuse transmission differs from specular 
transmission in that the light becomes scattered during the course of 
penetrating the support. Stated another way, even with the imaging unit 
exhibiting zero density or being entirely omitted, one viewing the support 
12 from above (as shown) could not see the light source, but could see 
transmitted light, indicated by arrows 34, emanating from the support. 
With no image present in the imaging unit, the illuminated support appears 
uniformly white. When the imaging unit contains an image, this is 
superimposed on the illuminated white background provided by the support, 
and the image is readily viewed. 
If the support were specularly transmissive (i.e., transparent), viewed 
from above (as shown), the viewer could see the illumination source as 
well as any image present in the imaging unit. This is visually 
objectionable, since the two images, the illumination source and the image 
in the imaging unit are superimposed. By providing a photographic element 
with a diffusely transmissive support a superior support for transmission 
viewing is provided. 
A significant advantage of the photographic elements of this invention over 
those of the prior art is that a support construction is provided that is 
capable of use as either a reflective or diffuse transmission support. 
STRETCH CAVITATION MICROVOIDED SUPPORTS 
FIG. 3 illustrates a support 60 satisfying the requirements of this 
invention which has been biaxially oriented [biaxially stretched, i.e., 
stretched in both the longitudinal (X) and transverse (Y) directions], as 
indicated by the arrows. The support 60 is illustrated in section, showing 
microbeads 62 contained within circular microvoids 64 in the polymeric 
continuous matrix 66. The microvoids 64 surrounding the microbeads 62 are 
theoretically regular in shape, but on microscopic examination often show 
irregularities, particularly when the random spacing of the microbeads 
results in two or more microbeads being located in close proximity. 
FIG. 4 also illustrates a support 70 which has been unidirectionally 
oriented (stretched in one direction only, as indicated by the arrow). 
Microbeads 72 are contained between microvoid lobes 74 and 74'. The 
microvoid lobes in this instance form at opposite sides of the microbeads 
as the sheet is stretched. Thus, if the stretching is done in only the 
longitudinal direction (X) as indicated by the arrow, the microvoids will 
form on the leading and trailing sides of the microbeads. This is because 
of the unidirectional orientation as opposed to the bidirectional 
orientation of the sheet shown in FIG. 4. This is the only difference 
between the supports of FIGS. 3 and 4. 
Attention is particularly directed to the texture of the upper surfaces of 
the supports in each of FIGS. 3 and 4. 
FIGS. 5 and 6 are sectional views which illustrate on an enlarged scale a 
microbead 80 being entrapped within the polymeric continuous matrix 82 and 
encircled by microvoid 84. This lshape results from the support being 
stretched in both the X and Y directions. 
FIG. 7 is a view similar to FIG. 5, except illustrating in enlarged form 
microbead 90 entrapped in the polymeric continuous matrix 92, having 
formed on opposite sides thereof microvoid lobes 94 and 94', which are 
formed when the support is stretched only in the direction of the arrow X. 
FIG. 8 is an enlargement illustrating a specific manner in which microvoids 
can be formed in a polyester continuous matrix as the support is stretched 
or oriented. The formation of the microvoids 100 and 100' around 
microbeads 102 is illustrated on a stretch ratio scale as the support is 
stretched up to 4 times its original dimension. For example, as the 
support is stretched 4 times its original dimension in the X direction 
(4X), the microvoids extend to the points 104 and 104', respectively. 
FIGS. 9 and 10 are actual photomicrographs of sections of a support 
according to this invention which has been frozen and fractured. The 
continuous polymeric matrix, microbeads, and microvoids are obvious. FIG. 
11 is an actual photomicrograph of a section of support oriented in one 
direction. The scale of these photomicrographs is indicated at the top of 
each in micrometers (.mu.m). 
In this preferred form of the invention the supports are comprised of a 
continuous thermoplastic polyester phase having dispersed therein 
microbeads of cellulose ester which are at least partially bordered by 
voids. The supports are conveniently in the form of sheets or film. The 
polyester is relatively strong and tough, while the cellulose acetate is 
relatively hard and brittle. 
More specifically, the present invention provides supports comprising a 
continuous thermoplastic polyester phase having dispersed therein 
microbeads of cellulose ester which are at least partially bordered by 
voids, the microbeads of cellulose acetate being present in an amount of 
10-30% by weight based on the weight of polyester, the voids occupying 
2-50% by volume of the shaped article, the composition of the shaped 
article when consisting only of the polyester continuous phase and 
microbeads of cellulose ester bordered by voids characterized by having a 
Kubelka-Munk R value (infinite thickness) of 0.90 to 1.0 and the following 
Kubelka-Munk values when formed into a 3 mil (76.2 microns) thick film: 
______________________________________ 
Opacity about 0.78 to about 1.0 
SX 25 or less 
KX about 0.001 to 0.2 
Ti about 0.02 to 1.0 
______________________________________ 
wherein the opacity values indicate that the article is opaque, the SX 
values indicate a large amount of light scattering through the thickness 
of the article, the KX values indicate a low amount of light absorption 
through the thickness of the article, and the Ti values indicate a low 
level amount of internal transmittance of the thickness of the article. 
The R (infinite thickness) values indicate a large amount of light 
reflectance. 
Obviously, the Kubelka-Munk values which are dependent on thickness of the 
article must be specified at a certain thickness. Although the supports 
themselves may be very thin, e.g., less than 1 mil (25.4 micron) or they 
may be thicker, e.g., 20 mils (508 microns), the Kubelka-Munk values, 
except for R(.infin.), are specified at 3 mils (76.2 microns) and in the 
absence of any additives which would effect optical properties. Thus, to 
determine whether supports have the optical properties called for, the 
polyester containing microbeads at least partially bordered by voids, 
without additives, should be formed in a 3 mils (approx. 75 .mu.m) thick 
film for determination of Kubelka-Munk values. 
The supports according to this invention are useful, for example, when in 
the forms of sheets or films. In the absence of additives or colorants, 
they are very white. The supports are very resistant to wear, moisture, 
oil, tearing, etc. 
The polyester (or copolyester) phase may be any article-forming polyester 
such as a polyester capable of being cast into a film or sheet, spun into 
fibers, extruded into rods or extrusion, blow-molded into containers such 
as bottles, etc. The polyesters should have a glass transition temperature 
between 50.degree. C. and 150.degree. C., preferably 
60.degree.-100.degree. C., should be orientable, and have an I.V. of at 
least 0.55, preferably 0.6 to 0.9. 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, and mixtures thereof. Examples of suitable 
glycols include ethylene glycol, propylene glycol, butanediol, 
pentanediol, hexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, 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. Nos. 
2,465,319 and 2,901,466. The preferred polyester is polyethylene 
terephthalate having a Tg of about 80.degree. C. Other suitable polyesters 
include liquid crystal copolyesters formed by the inclusion of a 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. 
Blends of polyesters and/or copolyesters are useful in the present 
invention. Also, small amounts of other polymers such as polyolefins can 
be tolerated in the continuous matrix. 
Suitable cellulose acetates are those having an acetyl content of 28 to 
44.8% by weight, and a viscosity of 0.01-90 seconds. Such cellulose 
acetates are well known in the art. Small contents of propionyl can 
usually be tolerated. Also, processes for preparing such cellulose 
acetates are well known in the art. Suitable commercially available 
cellulose acetates include the following which are marketed by Eastman 
Chemical Products, Inc.: 
__________________________________________________________________________ 
Cellulose 
Viscosity.sup.1 Acetyl 
Hydroxyl 
Melting Number Average 
Acetate Poises Content 
Content 
Range Tg, Molecular 
Type Seconds 
(Pascal-Sec.) 
%.sup.2 
%.sup.2 
.degree.C. 
.degree.C. 
Weight.sup.3 
__________________________________________________________________________ 
CA-394-60S 
60.0 22.8 39.5 4.0 240-260 
186 60,000 
CA-398-3 
3.0 1.14 39.8 3.5 230-250 
180 30,000 
CA-398-6 
6.0 2.28 39.8 3.5 230-250 
182 35,000 
CA-398-10 
10.0 3.80 39.8 3.5 230-250 
185 40,000 
CA-398-30 
30.0 11.40 39.7 3.5 230-250 
189 50,000 
CA-320S 
0.05 0.02 32.0 8.4 190-269 
about about 
180-190 
18,000 
CA-436-80S 
80 30.4 43.7 0.82 269-300 
180 102,000 
__________________________________________________________________________ 
.sup.1 ASTM D817 (Formula A) and D1343 
.sup.2 ASTM D817 
.sup.3 Molecular weights are polystyrene equivalent molecular weights, 
using Gel Permeation Chromatography 
The microbeads of cellulose esters range in size from 0.1-50 microns, and 
are present in an amount of 10-30% by weight based on the weight of the 
polyester. The microbeads of cellulose acetate have a Tg of at least 
20.degree. C. higher than the Tg of the polyester and are hard compared to 
the polyester. 
The microbeads of cellulose acetate are at least partially bordered by 
voids. The void space in the shaped article should occupy 2-50%, 
preferably 20-30%, by volume of the shaped article. Depending on the 
manner in which the supports are made, the voids may completely encircle 
the microbeads, e.g., a void may be in the shape of a doughnut (or 
flattened doughnut) encircling a microbead, or the voids may only 
partially border the microbeads, e.g., a pair of voids may border a 
microbead on opposite sides. 
The invention does not require but permits the use or addition of a 
plurality of organic and inorganic materials such as fillers, pigments, 
anti-blocks, anti-stats, plasticizers, dyes, stabilizers, nucleating 
agents, etc. These materials may be incorporated into the matrix phases, 
into the dispersed phases, or may exist as separate dispersed phases. 
The microvoids form on cooling without requiring nucleating agents. During 
stretching the voids assume characteristic shapes from the balanced 
biaxial orientation of paperlike films to the uniaxial orientation of 
microvoided/satin-like fibers. Balanced microvoids are largely circular in 
the plane of orientation while fiber microvoids are elongated in the 
direction of the fiber axis. The size of the microvoids and the ultimate 
physical properties depend upon the degree and balance of the orientation, 
temperature and rate of stretching, crystallization kinetics, the size 
distribution of the microbeads, and the like. 
The supports according to this invention are prepared by 
(a) forming a mixture of molten polyester and cellulose acetate wherein the 
cellulose acetate is a multiplicity of microbeads uniformly dispersed 
throughout the polyester, the polyester being as described hereinbefore, 
the cellulose acetate being as described hereinbefore, 
(b) forming a shaped article from the mixture by extrusion, casting or 
molding, 
(c) orienting the article by stretching to form microbeads of cellulose 
acetate uniformly distributed throughout the article and voids at least 
partially bordering the microbeads on sides thereof in the direction, or 
directions of orientation. 
The mixture may be formed by forming a melt of the polyester and mixing 
therein the cellulose acetate. The cellulose acetate may be in the form of 
solid or semi-solid microbeads, or in molten form. Due to the 
incompatability between the polyester and cellulose acetate, there is no 
attraction or adhesion between them, allowing the cellulose acetate to 
"bead-up" if molten to form dispersed microbeads upon mixing. If solid or 
semi-solid, the microbeads become uniformly dispersed in the polyester 
upon mixing. 
When the microbeads have become uniformly dispersed in the polyester, a 
shaped article is formed by processes such as extrusion, casting or 
molding. Examples of extrusion or casting would be extruding or casting a 
film or sheet. Such forming methods are well known in the art. If sheets 
or film material are cast or extruded, it is important that such article 
be oriented by stretching, at least in one direction. Methods of 
unilaterally or bilaterally orienting sheet or film material are well 
known in the art. Basically, such methods comprise stretching the sheet or 
film at least in the machine or longitudinal direction after it is cast or 
extruded by an amount of about 1.5-10 (usually 3-4) times its original 
dimension. Such sheet or film may also be stretched in the transverse or 
cross-machine direction by apparatus and methods well known in the art, in 
amounts of generally 1.5-10 (usually 3-4) times the original dimension. 
Such apparatus and methods are well known in the art--e.g., they are 
described in such U.S. Pat. Nos. 3,903,234, incorporated herein by 
reference. 
The voids, or void spaces, referred to herein surrounding the microbeads 
are formed as the polyester continuous matrix is stretched at a 
temperature between the polyester Tg and the cellulose acetate Tg. The 
microbeads of cellulose acetate are relatively hard compared to the 
polyester continuous matrix. Also, due to the incompatability and 
immiscibility between the cellulose acetate and the polyester, the 
polyester continuous matrix slides over the microbeads as it is stretched, 
causing voids to be formed at the sides in the direction or directions of 
stretch, which voids elongate as the polyester matrix continues to be 
stretched. Thus, the final size and shape of the voids depends on the 
direction(s) and amount of stretching. If stretching is only in one 
direction, microvoids will form at the sides of the microbeads in the 
direction of stretching. If stretching is in two directions (bidirectional 
stretching), in effect such stretching has vector components extending 
radially from any given position to result in a doughnut-shaped void 
surrounding each microbead. 
The preferred preform stretching operation simultaneously opens the 
microvoids and orients the matrix material. The final product properties 
depend on and can be controlled by stretching time-temperature 
relationships and on the type and degree of stretch. For maximum opacity 
and texture, the stretching is done just above the glass transition 
temperature of the matrix material. When stretching is done in the 
neighborhood of the higher glass transition temperature, both phases 
stretch together and opacity decreases. In the former case, the materials 
are pulled apart, a mechanical anti-compatibilization process. In the 
latter case, they are drawn together, a mechanical compatibilization 
process. Two examples are high-speed melt spinning of fibers and melt 
blowing of fibers and films to form non-woven/spun-bonded products. In 
summary, the scope of this invention includes the complete range of 
forming operations just described. 
In general, void formation occurs independent of, and does not require, 
crystalline orientation of the matrix phase. Opaque, microvoided films 
have been made in accordance with the methods of this invention using 
completely amorphous, non-crystallizing copolyesters as the matrix phase. 
Crystallizable/orientable (strain hardening) matrix materials are 
preferred for some properties like tensile strength and barrier 
effectiveness. On the other hand, amorphous matrix materials have special 
utility in other areas like tear resistance and heat sealability. The 
specific matrix composition can be tailored to meet many product needs. 
The complete range from crystalline to amorphous matrix materials is part 
of the invention. 
Stretching experiments reveal that increasing the cellulose ester content 
of the blends reduces the effective natural draw ratio relative to that of 
the matrix material and raises the effective orientation or draw 
temperature. When melt casting these films, required casting roll 
temperature increases with cellulose ester content. Minimal cooling below 
the orientation temperature prior to stretching is preferred since the 
cooled preform state is often brittle, the brittleness increasing with 
cellulose ester content. 
The following examples are submitted for a better understanding of the 
invention. 
In the examples the specified materials were combined and mixed in a dry 
state prior to extrusion. Most of the materials used in these examples are 
granules (ground through a 2 millimeter screen) and fine powders. This 
form permits good dry blending without separation during processing. In 
most cases, the mixed materials were dried under vacuum conditions with 
nitrogen bleed to carry off the volatiles. Of course, when substantial 
amounts of low-melting materials were used, separate drying was done, 
followed by mixing and immediate extrusion. The relative amounts of the 
polyester, cellulose ester, and other materials are indicated by mass 
ratios; and all percents are weight %. During extrusion, the materials are 
melted and mixed as viscous melts. Shear emulsification of the immiscible 
melts was enhanced with a mixing section centrally located in the metering 
section of the extruder screw. Residence time was kept small by design; 
for example, screw L/D was 24:1 [Killion 1.25 inch (31.8 mm) extruder] and 
the dies were joined directly to the extruder via small-sized adaptors. 
The extrudate is quenched to form flat films or sheet. The required 
orientation was carried out by conventional equipment and methods 
associated with the specific forming operation. 
EXAMPLES OF STRETCH CAVITATION MICROVOIDED SUPPORTS 
The following are specific examples illustrating the preparation of stretch 
cavitation microvoided articles suitable for use as supports for the 
photographic elements of this invention. 
EXAMPLE 1 
Blends were prepared with a polyester and a cellulose acetate. The 
polyester is Polyester A (described below) and the cellulose ester is 
cellulose acetate CA-398-30. Two blends (80/20) and (90/10) were melt cast 
to form sheets between 15 to 20 mils (381 to 508 microns) thick. These 
sheets were simultaneously stretched 4X (a multiple of 4) in both 
directions to form white, paper-like films just over 1 mil (25.4 microns) 
thick. The films of this invention are highly diffuse reflective over the 
visible spectrum and remain highly reflective in the near UV (300 to 400 
nanometer wavelengths) region. Typical films properties and processing 
conditions are given below. 
EXAMPLE 2 (CONTROL) 
This example is an example of prior art. It is given here for direct 
comparison with Example 1. Blends were prepared with the same polyester as 
Example 1 and inorganic materials. The inorganics are titanium dioxide 
(Rutile R-100) and calcium carbonate (Microwhite 25). A (90/10) blend of 
the polyester and each of the inorganics was melt cast to form sheets 
between 15 to 20 mils (381 to 508 microns) thick. These sheets were 
simultaneously stretched 4X in both directions to form white, plastic-like 
films just over 1 mil (25.4 microns) thick. Typical film properties and 
processing conditions are given below. 
EXAMPLE 3 
Blends were prepared with a polyester and a cellulose acetate. The 
polyester is a blend of Polyester A and Polyester A containing a 
covalently bound colorant. The cellulose acetate is CA-398-30. Two (80/20) 
blends (one containing 0.5% red moiety and one containing 0.5% blue 
moiety) were melt cast to form sheets 20 mils (508 microns) thick. These 
sheets were simultaneously stretched 4X in both directions to form 
pastel-colored, paper-like films about 1.75 mils (44.5 microns) thick. 
Typical film properties and processing conditions are given below. 
EXAMPLE 4 
Blends were prepared with a polyester and a mixed cellulose ester, 
cellulose acetate propionate. The polyester is Polyester A and the 
cellulose ester is CAP-482-20. This (90/10) blend and a (90/10) blend made 
like Example 1 were melt cast to form sheets 15 mils (381 microns) thick. 
These sheets were simultaneously stretched 4X in both directions to form 
translucent, paper-like films about 1 mil (25.4 microns) thick. Typical 
film properties and processing conditions are given below. 
EXAMPLE 5 
Blends were prepared with the same polyester and cellulose acetate as 
Example 1. The specific blends (95/5), (90/10), (85/15), (80/20), (75/25), 
and (70/30) were melt cast to form sheets 25 mils (635 microns) thick. 
Extrusion conditions were similar to those of Example 1. These sheets were 
simultaneously stretched 3X in both directions to form white, paper-like 
films 3 mils (76.2 microns) thick. These sheets were also simultaneously 
stretched 4X in both directions to form white, paper-like films 2 mils 
(50.8 microns) thick. Typical film optical properties are given below. 
EXAMPLE 6 
This example shows that light-colored, opaque structures developed when the 
dispersed phase was colored. The polyester of Example 1 was mixed with a 
cellulose acetate (CA-320S, containing a covalently bonded colorant). A 
(90/10) blend (containing 0.13% red moiety) was melt cast to form sheets 
15 mils (381 microns) thick. These sheets were stretched as in Example 1 
yielding uniformly pastel-red, opaque, paper-like films. 
EXAMPLE 7 
This example shows that lower viscosity polyesters containing minor amounts 
of additives yielded products of this invention. A blend was prepared with 
a polyester and a cellulose acetate. The polyester is Polyester B 
(described below) and the cellulose acetate is CA-398-30. A (90/10) blend 
was melt cast to form sheets between 15 to 20 mils (381 to 508 microns) 
thick. A Brabender 3/4-inch (19-mm) laboratory extruder without a mixing 
screw was used at 110 RPM and 260.degree. C. (melt temperature). These 
sheets were simultaneously stretched 4X in both directions to form white, 
paper-like films just over 1 mil (25.4 microns) thick. These films 
contained visible particles of cellulose acetate resulting from the 
incomplete shear emulsification on this machine. 
EXAMPLE 8 
This example shows that white, opaque properties developed over a range of 
stretching conditions. A (90/10) blend of the same materials as Example 1 
was melt cast using the equipment of Example 6. Stretching conditions were 
(2.times.1), (2.times.2), (3.times.1), (3.times.2), (3.times.3), 
(4.times.1), (4.times.2), (4.times.3) and (4.times.4). Whiteness and 
opacity were visually evident at all levels of stretching, increasing with 
balance and degree of stretch. 
EXAMPLE 9 
This example illustrates that polyester/polyester blends can be used with 
cellulose acetates to produce articles of this invention. The specific 
blends of this example are (65/25/10) and (65/15/20) using Polyester A, 
Polyester C, and CA-398-30 respectively. Films were made as in Example 1, 
and the resulting properties were similar. The films of this example, 
however, were more flexible due to the presence of the thermoplastic 
elastomer in the blend. 
EXAMPLE 10 
Blends were prepared with a polyester and a cellulose acetate. The 
polyester is Polyester A and the cellulose acetate is CA-394-60S. The 
following blends (95/5), (90/10), (85/15), and (80/20) were melt extruded 
and simultaneously biaxially oriented on a laboratory blown film line. The 
oriented tubes had a layflat width of 9 to 12 inches (22.9 to 30.5 
centimeters), and the film thickness was about 0.5 mil (12.7 microns). 
These films were white, opaque, and had tissue paper qualities. Typical 
film properties and processing conditions are given below. 
EXAMPLE 11 
Blends were prepared with a polyester and a cellulose acetate. The 
polyester is a blend of Polyester A and Polyester A containing a 
covalently bound colorant. The cellulose acetate is CA-398-30. Four 
(80/20) blends were melt extruded and simultaneously biaxially oriented as 
in Example 10. Typical film properties and processing conditions are given 
below. 
EXAMPLE 12 
A (90/10) blend was prepared with a higher glass transition polyester, 
Polyester D, and a cellulose acetate (CA-394-60S). This blend was melt 
extruded at a melt temperature of 270.degree. C. and simultaneously 
biaxially oriented at about 140.degree. C. as in Example 10. The resulting 
film was white, opaque, and paper-like. This blend system is especially 
attractive if high temperature resistant products are being manufactured. 
EXAMPLE 13 
The blends of this example were prepared from a polyester, a polypropylene, 
and a cellulose acetate. The polyester is Polyester A; the polypropylene 
homopolymer is PP 4230; and the cellulose acetate is CA-394-60S. Three 
blends (70/10/20), (75/5/20), and (77/3/20) were melt extruded and 
simultaneously biaxially oriented as in Example 10. White, opaque, 
paper-like films were made, however film strength and quality decreased as 
the level of polypropylene increased. 
EXAMPLE 14 
A (90/10) blend was prepared with a polyester, Polyester A, and a cellulose 
triacetate CA-436-80S. This blend was melt extruded at a melt temperature 
of 275.degree. C. and simultaneously biaxially oriented as in Example 10. 
White, opaque, paper-like films were made, however the quality of the film 
was degraded by the presence of small particles of incompletely melted 
cellulose triacetate. 
EXAMPLE 15 
Blends were prepared with a polyester, Polyester A, a water-dispersible 
polyester, and a cellulose acetate (CA-398-30). The blend was melt 
extruded and simultaneously biaxially oriented as in Example 10. The 
white, opaque, paper-like films were of good quality, with an enhanced 
hydrophilic character due to the presence of the hydrophilic polyester. 
EXAMPLE 16 
A (90/10) blend of an amorphous copolyester and a cellulose acetate was 
prepared. The copolyester was Polyester E, and the cellulose acetate was 
CA-394-60S. The blend was melt extruded and simultaneously biaxially 
oriented as in Example 10; however the white, opaque, paper-like films had 
a faint, yellowish tint, indicating greater thermal degradation. 
EXAMPLE 17 
A (90/10) blend of another copolyester and a cellulose acetate was 
prepared. The copolyester was Polyester F and the cellulose acetate was 
CA-398-30. The blend was melt extruded and simultaneously biaxially 
oriented as in Example 10. A good quality, white, opaque, paper-like film 
resulted. 
EXAMPLE 18 
A (90/10) blend was prepared from a polyester, Polyester A, and a lower 
viscosity cellulose acetate (CA-398-3). A second (90/10) blend of this 
polyester with a lower percent acetyl cellulose acetate (CA-320S) was also 
prepared. Both blends were melt extruded and simultaneously biaxially 
oriented as in Example 10. Good quality, white, opaque, paper-like films 
resulted. 
______________________________________ 
EXAMPLE 1 
TYPICAL CAST & TENTERED FILM PROPERTIES 
FOR 80/20 & 90/10 POLYESTER/CELLULOSE ACETATE 
______________________________________ 
Material (80) Polyester A 
(90) Polyester A 
(20) CA-398-30 
(10) CA-398-30 
Melt Temp., .degree.C. 
260 262 
Screw Speed (rpm) 
50 50 
Cast Roll Temp., .degree.C. 
82 58 
Cast Roll Speed (fpm) 
6.0 (1.83 -- 
meters/min) 
Stretch Temp., .degree.C. 
120 110 
Film Thickness (mil) 
1.37 (34.8 1.17 (29.7 
microns) microns) 
Inherent Visc. (dl/g) 
0.590 0.623 
Density (g/cc) 1.023 1.303 
Tensile Yield 7.40/6.67 12.8/12.6 
(10.sup.3 psi)(mPa)* 
(51.0/46.0) (88.3/86.9) 
Tensile Break (10.sup.3 psi) 
10.4/8.74 23.5/22.4 
(71.7/60.3) (162/154) 
Elongation to Break (%) 
70/61 92/77 
Oxygen Transmission 
16.0(6.30) 9.54(3.76) 
(cc-mil/100 in.sup.2 24-hr-atm) 
##STR1## 
Kubelka-Munk Analysis 
(560 nm): 
Scattering SX 3.644 2.308 
Absorption KX 0.002x 0.002x 
Transmittance T(i) 
0.214 0.302 
Reflectance R(inf) 
0.966 0.966 
Opacity 0.812 0.722 
______________________________________ 
*megaPascals 
______________________________________ 
EXAMPLE 2 
CAST & TENTERED FILM PROPERTIES 
FOR 90/10 POLYESTER/INORGANIC FILLER 
______________________________________ 
Material (90) Polyester A 
(90) Polyester A 
(10) Rutile R-100 
(10) Microwhite 25 
Melt Temp., .degree.C. 
263 263 
Screw Speed (rpm) 
50 50 
Cast Roll Temp., .degree.C. 
42 50 
Cast Roll Speed (fpm) 
-- meter/min -- 
Stretch Temp., .degree.C. 
110 110 
Film Thickness (mil) 
1.13 (28.7 1.33(33.8 
microns) microns) 
Inherent Visc. (dl/g) 
0.563 0.573 
Density (g/cc) 1.432 1.323 
Tensile Yield 11.3/12.0 10.8/11.2 
(10.sup.3 psi)(mPa)* 
(77.9/82.7) (74.5/77.2) 
Tensile Break (10.sup.3 psi) 
18.6/20.3 16.5/17.7 
(128/140) (114/122) 
Elongation to Break (%) 
103/100 73/71 
Oxygen Transmission 
8.72 (3.43) 10.2 (4.02) 
(cc-mil/100 in.sup.2 24-hr-atm) 
##STR2## 
Kubelka-Munk Analysis 
(560 nm): 
Scattering SX 2.310 1.115 
Absorption KX 0.005x 0.008x 
Transmittance T(i) 
0.300 0.468 
Reflectance R(inf) 
0.936 0.886 
Opacity 0.742 0.591 
______________________________________ 
*megaPascals 
______________________________________ 
EXAMPLE 3 
FOR 75/5/20 POLYESTER/RED POLYESTER/CELLULOSE 
ACETATE 75/5/20 POLYESTER/BLUE 
POLYESTER/CELLULOSE ACETATE 
______________________________________ 
Material (75) Polyester A 
(75) Polyester A 
(5) Polyester A 
(5) Polyester A 
(Red) (Blue) 
(20) CA-398-30 
(20) CA-398-30 
Melt Temp., .degree.C. 
260 260 
Screw Speed (rpm) 
50 50 
Cast Roll Temp., .degree.C. 
82 82 
Cast Roll Speed (fpm) 
6.0 (1.83 6.0 (1.83 
meters/min) meters/min) 
Stretch Temp., .degree.C. 
120 125 
Film Thickness (mil) 
1.78 (45.2 1.75 (44.4 
microns) microns) 
Inherent Visc. (dl/g) 
0.640 0.672 
Density (g/cc) 0.889 0.895 
Tensile Yield 6.19/6.00 4.97/4.92 
(10.sup.3 psi)(mPa)* 
(42.7/41.4) (34.3/33.9) 
Tensile Break (10.sup.3 psi) 
8.10/7.75 5.78/5.38 
(55.8/53.4) (39.9/37.1) 
Elongation to Break (%) 
50/42 41/23 
Oxygen Transmission 
18.4 (7.24) 21.8 (8.58) 
(cc-mil/100 in.sup.2 24-hr-atm) 
##STR3## 
Kubelka-Munk Analysis 
(560 nm): 
Scattering SX 5.571 6.530 
Absorption KX 2.332x 2.408x 
Transmittance T(i) 
0.003 0.000 
Reflectance R(inf) 
0.413 0.434 
Opacity 1.000 1.000 
______________________________________ 
*megaPascals 
______________________________________ 
EXAMPLE 4 
CAST & TENTERED FILM PROPERTIES 
FOR 90/10 POLYESTER/CELLULOSE ACETATE 
AND 90/10 POLYESTER/CELLULOSE ACETATE PROPIONATE 
______________________________________ 
Material (90) Polyester A 
(90) Polyester A 
(10) CA-398-30 
(10) CAP-482-20 
Melt Temp., .degree.C. 
264 264 
Screw Speed (rpm) 
50 50 
Cast Roll Temp., .degree.C. 
49 49 
Cast Roll Speed (fpm) 
6.0 (1.83 6.0 (1.83 
meters/min) meters/min) 
Stretch Temp., .degree.C. 
105 115 
Film Thickness (mil) 
1.03 (26.2 0.94 (23.9 
microns) microns) 
Inherent Visc. (dl/g) 
0.603 0.665 
Density (g/cc) 1.192 1.364 
Tensile Yield 13.5/13.7 15.9/15.1 
(10.sup.3 psi)(mPA)* 
(93.1/94.5) (111/104) 
Tensile Break (10.sup.3 psi) 
25.5/25.9 29.0/29.2 
(176/179) (200/201) 
Elongation to Break (%) 
84/78 103/108 
Oxygen Transmission 
8.01 (3.15) 7.34 (2.89) 
(cc-mil/100 in.sup.2 24-hr-atm) 
##STR4## 
Kubelka-Munk Analysis 
(560 nm): 
Scattering SX 2.397 0.398 
Absorption KX 0.006x 0.006x 
Transmittance T(i) 
0.292 0.711 
Reflectance R(inf) 
0.930 0.848 
Opacity 0.756 0.334 
______________________________________ 
*megaPascals 
__________________________________________________________________________ 
EXAMPLE 5 
KUBELKA-MUNK ANALYSES 
Polyester/ 
Cellulose 
Stretch 
Stretch 
Reheat 
Acetate 
Ratios 
Temp., 
Time 
Thickness Kubelka-Munk Values 
(Mass Ratio) 
(X x Y) 
.degree.C. 
(Sec) 
(Mils) 
(Microns) 
SX KX T(i) 
R.infin. 
Opacity 
__________________________________________________________________________ 
99/1 3 .times. 3 
100 45 2.7 68.6 0.201 
0.012X 
0.822 
0.710 
0.233 
98/2 3 .times. 3 
100 45 2.8 71.1 0.272 
0.014X 
0.775 
0.730 
0.289 
95/5 3 .times. 3 
100 60 2.9 73.7 0.861 
0.013X 
0.529 
0.838 
0.545 
90/10 3 .times. 3 
100 75 3.2 81.3 2.611 
0.014X 
0.271 
0.901 
0.794 
85/15 3 .times. 3 
100 75 3.7 94.0 6.484 
0.015X 
0.128 
0.933 
0.917 
80/20 3 .times. 3 
100 75 4.0 102 11.892 
0.013X 
0.073 
0.954 
0.958 
75/25 3 .times. 3 
100 60 3.4 86.4 12.126 
0.016X 
0.071 
0.950 
0.961 
70/30 3 .times. 3 
110 75 5.2 132 19.160 
0.015X 
0.045 
0.961 
0.978 
75/25 3.5 .times. 3.5 
115 60 2.7 68.6 7.262 
0.012X 
0.117 
0.945 
0.922 
70/30 3.5 .times. 3.5 
115 60 5.0 127 21.990 
0.012X 
0.040 
0.967 
0.980 
99/1 4 .times. 4 
110 60 1.6 40.6 0.195 
0.011X 
0.828 
0.719 
0.224 
98/2 4 .times. 4 
110 60 1.6 40.6 0.260 
0.011X 
0.785 
0.749 
0.273 
95/5 4 .times. 4 
110 60 1.8 45.7 0.745 
0.010X 
0.567 
0.851 
0.497 
90/10 4 .times. 4 
110 60 2.1 53.3 2.583 
0.010X 
0.274 
0.914 
0.782 
85/15 4 .times. 4 
115 60 2.0 50.8 4.076 
0.009X 
0.193 
0.937 
0.851 
80/20 4 .times. 4 
115 45 2.7 68.6 9.699 
0.011X 
0.090 
0.954 
0.943 
70/30 4 .times. 4 
120 120 5.8 147 22.634 
0.015X 
0.037 
0.964 
0.983 
__________________________________________________________________________ 
__________________________________________________________________________ 
EXAMPLE 10 
BLOWN FILM PROPERTIES 
__________________________________________________________________________ 
Material of Blend 
(95) Polyester A 
(90) Polyester A 
(85) Polyester A 
(80) Polyester A 
(5) CA-394-60S 
(10) CA-394-60S 
(15) CA-394-60S 
(20) CA-394-60S 
Extruder Melt Temp., .degree.C. 
255 254 260 260 
Extruder Pressure, psig 
1400 1400 1500 1400 
(megaPascals) (9.66) (9.66) (10.34) (9.66) 
Extruder Screw (rpm) 
40 40 50 50 
NIP Speed, ft/min 
46 46 43 51 
(meters/min) (14.0) (14.0) (13.1) (15.5) 
Film Thickness, mil 
0.49 0.49 0.59 0.48 
(microns) (12.4) (12.4) (15.0) (12.2) 
Area Weight, grams/sq ft 
1.71 1.60 2.01 1.27 
[grams/(meter).sup.2 ] 
(18.4) (17.2) (21.6) (13.7) 
Density (sp. gr.) 
1.301 1.302 1.208 1.120 
Yield Stress, 10.sup.3 psi 
8.6/7.6 7.8/5.9 5.3/7.4 5.1/6.4 
(MD/TD)* 
(megaPascals or mPa) 
(59.3/52.4) 
(53.8/40.7) 
(36.5/51.0) 
(35.2/44.1) 
__________________________________________________________________________ 
*(Machine Direction/Transverse Direction) 
__________________________________________________________________________ 
EXAMPLE 11 
BLOWN FILM PROPERTIES 
__________________________________________________________________________ 
Material or Blend 
(80) Polyester A 
(75) Polyester A 
(75) Polyester A 
(80) Polyester A 
(20) CA-398-30 
(5) Polyester A 
(5) Polyester A 
(5) Polyester A 
(Yellow) 
(Red) (Blue) 
(20) CA-398-30 
(20) CA-398-30 
(20) CA-398-30 
Extruder Melt Temp., .degree.C. 
255 255 256 257 
Extruder Pressure, psig 
1400 1400 1400 1400 
(megaPascals) 
(9.66) (9.66) (9.66) (9.66) 
Extruder Screw, rpm 
50 50 50 50 
(meters/min) (15.5) (15.5) (15.5) (15.5) 
NIP Speed (ft/min) 
51 51 51 51 
Film Thickness, mil 
0.60 0.53 0.49 0.48 
(microns) (15.2) (13.5) (12.4) (12.2) 
Area Weight, grams/sq ft 
1.84 1.57 1.53 1.44 
[grams/(meter).sup.2 ] 
(19.8) (16.9) (16.5) (15.5) 
Inherent Viscosity (dl/gm) 
0.629 0.650 0.660 0.657 
Density (sp. gr.) 
1.143 1.143 1.109 1.117 
Yield Stress, 10.sup.3 psi 
8.8/7.2 9.1/8.2 8.1/7.6 8.0/7.6 
(MD/TD) 
(megaPascals) 
(60.7/49.6) 
(62.7/56.5) 
(55.8/52.4) 
(55.2/52.4) 
Oxygen Transmission 
11.5 12.2 11.7 11.8 
(cc-mil/100 in.sup.2 -24 hr-atm) 
##STR5## (4.53) (4.80) (4.61) (4.65) 
__________________________________________________________________________ 
______________________________________ 
Polyester A is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
dimethyl terephthalate 
or Ester Thereof 
Glycol(s) ethylene glycol 
I.V. 0.70 
Tg 80.degree. C. 
Tm 255.degree. C. 
Polyester B is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
dimethyl terephthalate 
or Ester Thereof 
Glycol(s) ethylene glycol 
I.V. 0.64 
Tg 80.degree. C. 
Tm 255.degree. C. 
Polyester C is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
99.5 mol % 1,4-cyclo- 
or Ester Thereof hexanedicarboxylic 
acid 
0.5 mol % trimellatic 
anhydride 
Glycol(s) 91.1 mol % 1,4-cyclo- 
hexanedimethanol 
8.9 mol % poly(tetra- 
methylene ether glycol) 
I.V. 1.05 
Tg below 0.degree. C. 
Tm 200.degree. C. 
Polyester D is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
Naphthalene dicarboxylic 
or Ester Thereof acid 
Glycol(s) ethylene glycol 
I.V. 0.80 
Tg 125.degree. C. 
Tm 265.degree. C. 
Polyester E is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
terephthalic acid 
or Ester Thereof 
Glycol(s) 69 mol % ethylene glycol 
31 mol % 1,4-cyclo- 
hexanedimethanol 
I.V. 0.75 
Tg 80.degree. C. 
Tm amorphous 
Polyester F is described as follows: 
Reaction Product Of: 
Dicarboxylic acid(s) 
75 mol % terephthalic 
or Ester Thereof acid 
25 mol % trans-4,4'- 
stilbene dicarboxylic 
acid 
Glycol(s) ethylene glycol 
I.V. 0.8 
Tg 95.degree. C. 
Tm 215.degree. C. 
______________________________________ 
The cellulose acetates, designated as "CA" are as defined in the table 
above. 
Where ratios or parts are given, e.g., 80/20, they are parts by weight, 
with the polyester weight specified first. 
The following applies to Kubelka-Munk values: 
SX is the scattering coefficient of the whole thickness of the article and 
is determined as follows: 
##EQU1## 
wherein: 
EQU b=(a.sup.2 -1)1/2 
Ar ctgh is the inverse hyperbolic cotangent 
##EQU2## 
Ro is reflectance with black tile behind sheet R is reflectance with white 
tile behind sheet 
Rg is reflectance of a white tile=0.89 
KX is the absorption coefficient of the whole thickness of the article and 
is determined as follows: 
EQU KX=SX(a-1) 
wherein SX and a are as defined above 
R (infinity) is the reflectance of an article if the article was so thick 
that additional thickness would not change it and is determined as 
follows: 
EQU R(infinity)=a-(a.sup.2 -1).sup.1/2 
wherein a is as defined above 
Ti is the internal light transmittance and is determined as follows: 
EQU Ti=[(a-Ro).sup.2 -b.sup.2 ].sup.1/2 
Opacity=Ro/Rg 
wherein Ro and Rg are as defined above. 
In the above formulae, Ro, R and Rg are determined in a conventional manner 
using a Diano Match-Scan II Spectrophotometer (Milton Roy Co.) using a 
wavelength of 560 nanometers. Also above, X in the formulae SX and KX is 
the thickness of the article. A full description of these terms is found 
in "Business, Science and Industry" 3rd Edition, by Deane B. Judd & Gunter 
Wyszecki, published by John Wiley & Sons, N.Y. (1975), pages 397-439, 
which is incorporated herein by reference. 
Glass transition temperatures, Tg, and melt temperatures, Tm, are 
determined using a Perkin-Elmer DSC-2 Differential Scanning Calorimeter. 
In the examples, physical properties are measured as follows: 
______________________________________ 
Tensile Strength at Yield 
ASTM D882 
Tensile Strength at Break 
ASTM D882 
Elongation at Break ASTM D882 
______________________________________ 
Unless otherwise specified inherent viscosity is measured in a 60/40 parts 
by weight solution of phenol/tetrachloroethane 25.degree. C. and at a 
concentration of 0.5 gram of polymer in 100 mL of the solvent. 
Where acids are specified herein in the formation of the polyesters or 
copolyesters, it should be understood that ester forming derivatives of 
the acids may be used rather than the acids themselves as is conventional 
practice. For example, dimethyl isophthalate may be used rather than 
isophthalic acid. 
In the examples, oxygen permeability is determined according to ASTM D 
3985, in cubic centimeters permeating a 1 mil (25.4 .mu.m) thick sample, 
100 inches square (approx. 64,500 cm.sup.2), for a 24-hour period under 
oxygen partial pressure difference of one atmosphere at 30.degree. C. 
using a MOCON Oxtran 10-50 instrument. Oxygen permeability is also given 
in S.I. (Systems International) units in cubic centimeters permeating a 1 
cm. thick sample, 1 cm. square, for 1 second at atmospheric pressure. 
Unless otherwise specified, all parts, ratios, percentages, etc. are by 
weight. 
IMAGING UNITS 
The imaging units of the photographic elements of this invention contain 
one or more radiation-sensitive silver halide emulsion layers. The silver 
halide emulsion layers can take any convenient conventional form. 
In the simplest possible form the photographic elements contain a single 
silver halide emulsion layer. In the simplest possible form a silver 
halide emulsion can consist of radiation-sensitive silver halide grains 
and a vehicle. The silver halide grains can be chosen from among silver 
bromide, silver chloride, silver iodide, silver chlorobromide, silver 
chloroiodide, silver bromoiodide, silver chlorobromoiodide, or mixtures 
thereof. The vehicle can be comprised of a hydrophilic colloid peptizer, 
such as gelatin or a gelatin derivative. 
Suitable imaging units containing one or more silver halide emulsion layers 
are illustrated by Research Disclosure, Vo. 176, Dec. 1978, Item 17643, 
the disclosure of which is here incorporated by reference. Research 
Disclosure is published by Kenneth Mason Publications, Ltd., Emsworth, 
Hampshire P010 7DD, England. The silver halide grain structures of silver 
halide emulsions are specifically disclosed by Section I of Item 17643. 
Vehicles for the emulsions are specifically illustrated by Section IX of 
Item 17643. 
The following conventional photographic element features can be present in 
the imaging unit, again referring to sections of Item 17643: 
Section III. 
Chemical sensitizers; 
Section IV. 
Spectral sensitizers and desensitizers; 
Section V. 
Brighteners; 
Section VI. 
Antifoggants and stabilizers; 
Section VII. 
Color materials; 
Section VIII. 
Absorbing and scattering materials; 
Section X. 
Hardeners; 
Section XI. 
Coating Aids; 
Section XII. 
Plasticizers and Lubricants; 
Section XVI. 
Matting agents; 
Section XX. 
Developing agents; 
Section XXI. 
Development modifiers; 
Section XXII. 
Physical development systems; 
Section XXIII. 
Image transfer systems; 
Section XXIV. 
Dry development systems; 
Section XXV. 
Printing and lithography; 
Section XXVI. 
Printout; and 
Section XXV. 
Direct-print. 
In addition to the varied forms of imaging units disclosed by Item 17643, 
cited above, the following are additionally specifically contemplated: 
(a) Imaging units containing one or more radiation-sensitive tabular grain 
silver halide emulsion layers, illustrated by Research Disclosure, Vol. 
225, Jan. 1983, Item 22534; Abbott et al U.S. Pat. No. 4,425,426; 
Daubendiek et al U.S. Pat. No. 4,672,027 and 4,693,964; Sowinski et al 
U.S. Pat. No. 4,656,122; Maskasky U.S. Pat. Nos. 4,173,320 and 4,173,323; 
and Reeves U.S. Pat. No. 4,435,499. 
(b) Element constructions specifically adapted for radiography, illustrated 
by Research Disclosure, Vol 184, Aug. 1979, Item 18431. 
(c) Reflection color print materials, illustrated by Research Disclosure, 
Vol. 176, Nov. 1979, Item 18716. 
The imaging units can be exposed and processed by any convenient 
conventional technique. Such techniques are illustrated by the items of 
paragraphs (a), (b), and (c), cited above. 
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.