Positive-acting diazo type materials having photodecomposed gradient

This invention relates to an improvement in a material adapted for imagewise exposure to actinic light comprising a transparent or translucent support having a positive-acting quinone diazide light-sensitive coating composition in direct contact with one surface thereof, the improvement comprising that the surface of said coating in direct contact with said support is substantially photodecomposed, and that a gradient exists in said coating wherein the percentage of undecomposed light-sensitive quinone diazide increases with increasing distance from said support. The invention also relates to a method for preparing the novel material.

This invention relates to a novel presensitized positive-acting highly 
absorbent or opaque layer on a transparent or translucent carrier and a 
process for producing the same. A second feature of the invention relates 
to the deposition of an opaque surround on glass for use in making 
television picture tubes. 
In a positive-acting system, the image areas of the exposed and developed 
sheets correspond with the opaque areas of the transparency, whereas the 
non-image areas, which are transparent and colorless, correspond with the 
light-transmissive areas of the transparency. When coatings are made on 
glass for picture tube usage, the opaque areas correspond to the opaque 
portions of the mask and the windows or transparent areas correspond to 
the openings in the shadow mask. In a negative-working system the image 
areas of the exposed and developed sheets correspond with the light 
transmissive areas of the transparency, whereas the non-image areas 
correspond with the opaque areas of the transparency. 
It is known in the preparation of reproduction products that highly 
absorbent patterns can be obtained by exposing silver halide emulsions to 
electromagnetic radiation by means of projection through air, films, and 
solid objects of various densities or by reflection from another surface, 
as in a camera for example, and then developing the exposed area. It is 
known also that other materials and coatings can be used in a manner 
similar to silver halide emulsions for generation of highly absorbent 
patterns. Exemplary of such materials are diazo type coupling systems, 
dichromated colloids and photoresists based on polyvinyl cinnamate resins 
and the like. The highly absorbent patterns which are produced with these 
latter two materials frequently are obtained by dyeing the substantially 
transparent patterns prior to or after the development process. If highly 
absorbent dyes or pigments are incorporated into the coatings, the amount 
of illumination required to produce a satisfactory image is increased in 
proportion to the density of the opaque materials. To produce black 
patterns, the exposure times are in the range of 2 minutes to 30 minutes 
or longer, depending upon the light sensitivity of the active components 
of the coating and the density of the opacifying agent. 
To illustrate the undesirable effect upon exposure of opaque materials in 
light-sensitive coatings, reference is made to U.S. Pat. No. 3,365,292. In 
column 1, lines 59 to 66 of this patent, the effect upon exposure of a 
photoresist coating containing black pigment is described, and it is 
stated therein that the light-absorbing properties of the black pigment 
either prevent the actinic light from fully penetrating the layer of 
photoresist as required, or impose a prohibitively long exposure time. To 
overcome this problem the patentee discovered that he can add an optically 
transparent filler to a photo-resist coated upon a glass support which 
after exposure and development is converted to a permanently opaque state. 
Although acceptably short exposures are obtained, an expensive and 
time-consuming baking operation is needed, which is moreover unacceptable 
when the support is a plastic or other substance which is not heat 
resistant. 
A typical example of the state of the art of positive acting systems, 
suitable for making both black and colored duplicates of originals, is the 
product covered by U.S. Pat. No. 3,326,682. It describes positive-working 
color proofing foils in which a coating, comprising an intimate mixture of 
light-sensitive orthonaphthoquinone diazide and alkali fast dye is coated 
upon a transparent support. Such foils are imaged by placing a mask in 
direct contact with the coated surface and by exposure to actinic 
radiation followed by a developing step. The resultant image has good 
resolution. However, exposure times are very much dependent upon the 
density of the color of the coating since the actinic light must penetrate 
the entire thickness of the coating in order to achieve developability. 
Reasonably short exposures are obtained only with the lighter colors which 
absorb little of the actinic radiation. Consequently, the product has 
severe limitations which cannot be overcome but can be ameliorated only by 
deliberate reduction of the density of the coating. Truly black high 
density patterns for instance cannot be made within acceptable exposure 
times. Thus, the system has severe drawbacks and needs improvement. 
Another positive-working system, by which opaque patterns can be obtained 
is described in U.S. Pat. No. 3,211,553, to Ito. Ito makes a 
positive-acting color proofing film by coating a corona-treated polyester 
film with the reaction product of poly-complex oxygenated anion, for 
example, phosphotungstic acid and para diazo diphenylamine monomer. The 
light-sensitive surface so formed is overcoated with polyvinyl formal 
containing a phthalocyanine blue pigment to make a cyan color proofing 
film. Similarly, magenta and yellow films are made by using appropriate 
color pigments. 
The coated sheets are exposed imagewise to ultraviolet radiation through 
the transparent support (called "back-exposure"). This back-exposure has 
the advantage that the exposure time is less than if exposed through the 
upper light-absorbing pigmented layer. It, however, has the disadvantage 
that imagewise exposure through the base results in a loss of resolution. 
After exposure, the sheets are developed to remove the photodecomposed 
areas and with them the overlying pigmented coating, revealing a positive 
image on a clear polyester support. At this point, the image is still 
light-sensitive and due to the yellowish color of the light-sensitive 
diazonium material its color is not true. To correct the off-color, the 
image is now fully exposed in an exposure frame and then bleached (but not 
subjected to developer action which would, of course, remove all of the 
image). Finally, the film is washed, rinsed and dried. 
For the users of this positive-acting proofing film, the required sequence 
of imagewise exposure, development, overall exposure to destroy remaining 
sensitizers, bleaching, washing and then rinsing is time consuming and 
troublesome. Furthermore, the imagewise exposure through the back results 
in an undesirable loss of resolution. Consequently, the material of Ito is 
also not entirely satisfactory. 
Although not explicitly discussed in Ito, diazo photosensitive materials in 
thin coatings used to make copy films, proofing films and printing plates, 
all require intense ultraviolet light to initiate the photochemical 
reaction. Ultraviolet light is usually considered to have a wavelength of 
approximately 400 nanometers. The relative insensitivity to higher 
wavelength is advantageous both in manufacturing and user handling, in 
that all operations can be conducted under subdued light or yellow light 
as the sensitivity of the coatings to such light is negligible. 
Consequently, any exposure of the coatings of Ito or any other diazo type 
coating to subdued safe light is of no moment and has no effect upon the 
observed results. Exposure to such subdued light can in no way be compared 
to exposure to ultraviolet radiation; only the second is actinic for diazo 
type coatings. 
Both in the description of the process of making a positive color image 
from a camera positive by exposure through the back, and throughout the 
Ito patent, is reiterated the fact that a positive-working diazo is 
decomposed by ultraviolet light, such as is emitted by a carbon arc, in 
the light-struck areas to a material which is readily washed away, 
confirming hereby what has long been well known in the art of the use of 
positive-working diazos. As opposed to this, negative-working diazos and 
also photopolymer systems react in just the opposite way in that exposure 
to actinic light, such as that emitted by a carbon arc, result in either 
decreasing the solubility of the material, or enhancing its bonding to the 
substrate or both. 
Examples of such negative-working systems are for instance Thommes, U.S. 
Pat. No. 3,241,973. This patent relates to a process for anchoring a 
negative-working photopolymer layer to a support by means of a second 
negative-working photopolymer composition, the latter functioning as an 
adhesive. The typical photopolymerizable materials employed by Thommes are 
ethylenically-unsaturated compounds capable of forming high polymers by 
free radical-initiated chain propagating addition polymerization. 
In this instance, the spectral range of photosensitivity of the adhesive 
and photopolymer layers is differentiated by choice of initiators. The use 
of different radiation sources and light filters is also possible. The 
adhesive layer then can be photopolymerized first and independently, even 
though the two layers are in contact. If the support is opaque, the 
exposure is made from the emulsion side. The upper photopolymer layer is 
formulated in a manner such that it is not affected in the time required 
to polymerize and harden the adhesive layer. If the support is 
transparent, this is not as necessary in that the adhesive layer can be 
exposed through the support. In either case the plate or film is next 
exposed imagewise through the upper polymerizable layer to photo harden 
the image. Contrary to the positive-working system referred to above, 
development removes the unexposed areas, resulting in a relief image 
suitable for printing. 
An additional example of a negative working system in which exposure to 
actinic light such as is emitted by a carbon arc results in a decrease in 
solubility of the coating is Thommes, U.S. Pat. No. 3,259,499. It 
describes photopolymerizable elements which may be placed upon opaque or 
transparent supports, which are of the same class as described in Thommes, 
U.S. Pat. No. 3,241,973. The element can be exposed through the base so 
that only the lower stratum becomes polymerized and this 
photopolymerizable stratum, as is normal upon exposure of negative-working 
systems, becomes resistant to the action of the usual developing solvents. 
Thus, the two Thommes patents covering negative-working systems are 
essentially similar and differ from the positive-working systems in that 
exposure results, as expected, in a decrease in solubility, whereas in the 
positive-working systems such as that of Ito, exposure results, also as 
expected, in a conversion to a material readily washed away. 
Further, Miller et al, U.S. Pat. No. 3,635,711, resembles the Thommes 
patent, in that it also employs negative-working photopolymerizable 
compositions which are made into relief plates by steps which include 
exposure of these compositions through a transparent base to effect 
photo-hardening at the interface, and an imagewise exposure through the 
front. Here also, exposure results according to theory in an 
insolubilization of the coating as opposed to Ito, where exposure, as is 
well known in the art, converts the positive-working material into a state 
in which it can be readily washed away. 
Haas et al, U.S. Pat. No. 3,671,237, describes still another 
negative-working imaging system, in which the unexposed portions are 
subsequently removed by a developing step. Essentially light-absorbing 
particles are caused to adhere to a substrate by the direct action of an 
image-wise intense radiation thereupon. With the removal of the unexposed 
particles by a high pressure gas jet, the image is revealed. This is the 
developing step. If the support is transparent, an alternative developing 
technique is used which is to radiate through the support. This serves to 
blast away the particles which have not been acted upon by imagewise 
exposure. Thus, again exposure forms the image areas which become 
unremovable by the developer, whereas in Ito exposure forms the non-image 
areas by rendering the exposed material soluble. 
Although there are, as described above, several negative-working systems by 
which opaque images of adequate resolution within reasonable exposure 
times can be obtained, there is a great need for an improved 
positive-working system in which upon imagewise exposure, in reasonably 
short exposure times, the area struck by light can be developed and 
thereby removed resulting in highly opaque images of excellent resolution. 
Therefore, one object of this invention is to provide such a material. A 
further object of the present invention is to combine the highly opaque 
pigmented materials with the light-sensitive diazo coating, so that the 
resulting opaque coated film can be obtained from a single coating 
operation. Still a further object of the present invention is to provide 
an improved method of utilizing black or opaque pigments to establish a 
screen structure of a color image reproducer having by a light absorbing 
border for the elemental phosphor areas. A still further provision is a 
method for imaging positive photoresists containing graphite, pigments, 
dyes and other opaque materials whereby imagewise exposure time can be 
reduced by 70% or more. 
Quite unexpectedly and contrary to all theory, it was found that a 
positive-acting coating on a transparent or translucent carrier fulfilling 
all the requirements of excellent resolution and short exposure time and 
yielding highly opaque images can be produced by the simple method of 
overall exposure of the coated material from the backside followed by a 
short imagewise exposure from the emulsion side prior to development. 
Superficially, this system resembles the one used for instance by Thommes 
in U.S. Pat. No. 3,241,973, which utilizes an overall exposure through the 
support followed by an imagewise exposure through the front. However, it 
is readily seen that the differences are great in that the Thommes system 
is predictable since negative-acting photo layers, as is well known in the 
art, are photohardenable and become insoluble upon exposure. Thus, the 
purpose and action in Thommes to harden the bottom of the layer in contact 
with the support, thus to act as an adhesive, can be readily achieved by 
exposure through the back. In contrast, the overall exposure through the 
base of a positive system such as is utilized in the present invention, 
would be expected to eliminate adhesion of the photo layer because it is 
photo-decomposed and, as is well known in the art, thereby becomes readily 
soluble. Thus, upon development after image-wise exposure through the 
front, the entire coating should be readily washed away. This, rather 
unexpectedly, for reasons not fully understood, does not occur. It is 
evident that the chemistry, specifically the photo reaction as well as the 
purpose of Thommes differs radically from the present invention and above 
all from the results obtained. Furthermore, the Thommes results can be 
expected and are predictable by theory, whereas the results of the present 
invention are totally unexpected and contrary to the teachings of the 
prior art. 
The light-sensitive element employed in the process of the present 
invention comprises (1) a support of transparent or translucent plastic 
film such as polyester, polyimide, polycarbonate, polystyrene, 
polypropylene, cellulose acetate and the like, or glass, or combinations 
of paper and plastic coatings, and (2) a positive-working light-sensitive 
layer having a weight of up to 20 grams/square meter, preferably 0.2 to 15 
grams/square meter when dry, and containing light-sensitive diazo 
compounds (such as quinone diazide compounds of the type disclosed in U.S. 
Pat. No. 3,148,983, for example), optionally, one or more binders such as: 
novolak resins and maleic acid-styrene copolymers and one or more pigments 
or dyes and/or dyestuffs. The ratio of resins to diazo compound preferably 
is in the range of 6 to 1 by weight, although other weights may be 
employed and no resin is absolutely necessary. The quantity of pigment or 
dyestuff in the dry coating may vary between 5 to 50 percent by weight and 
preferably is in the range of 10 to 40 percent by weight of the coating. 
The addition of graphite, carbon black, or organic pigments usually 
requires high speed blending of a previously dispersed material such as is 
obtained by ball milling. The finer dispersions are obtained by milling 
from 1 to 24 hours at room temperature (25.degree. C.). 
The coating solutions can be applied to the substrate by any of the common 
techniques such as dip, whirling, spray, wire bar and the like. The 
exposure of the coated materials can be made with any source of actinic 
light. Exemplary of such sources are carbon arcs, mercury vapor lamps, 
Xenon lamps, and sunlight. 
For cathode ray screens, the overall exposure through the support and the 
imagewise exposure through the film transparency or shadow mask can be 
made immediately after the coating dries or at any time thereafter. The 
mask is positioned on the coated side of the support and the several 
exposures are made through the mask using a point light source to expose 
the "windows". Contact exposure is suitable when film carriers are to be 
imaged. A suitable overall exposure is also made through the support at 
any time in the procedure. 
After rear exposure and imaging, the exposed coating is removed by dipping 
it in a bath or spraying with the developer, or wiping with a cotton pad 
soaked with the developer. The developer may be, for example, an aqueous 
alkaline solution containing salts, such as sodium phosphate, sodium 
metasilicate, sodium hydroxide, and mixtures of these or other alkaline 
materials and solvents. Development is followed by a water rinse and the 
reproduction materials are then air-dried.

In typical use for the positive-acting light-sensitive coating on 
transparent supports, the invention is practiced by first exposing the 
coating uniformly through the support to actinic light to create a unique 
product which now requires significantly lower exposure when later 
irradiated with actinic light from the face of the coating by emulsion to 
emulsion exposure through a mask or image transparency, a prerequisite for 
obtaining high resolution. While it has been found that the sequence of 
imagewise and overall exposure is immaterial, it is clear that more 
technical utility is obtained by practice of the invention when the 
photosensitive foil is first exposed uniformly through the support, prior 
to imagewise exposure through the other surface. 
It is believed that the chemical structure of the photosensitive coating 
composition layer is altered as a result of overall exposure through the 
support. Initially, as prepared, the coating is a homogeneous solid 
solution of a quinone diazide in binder, if present, and a colorant. After 
an overall exposure through the support to actinic light, the quinone 
diazide is substantially photodecomposed at the surface of the support. As 
actinic light is absorbed, both by the colorant present, and by the 
quinone diazide, its intensity decreases as does the degree of 
photodecomposition, as the distance from the support increases within the 
coating layer. In effect, a gradient is created with maximum 
photodecomposition at the interface of the support and photosensitive 
layer and a minimum at the surface of the photosensitive layer in contact 
with air. Experimental evidence for this representation is given in 
Example 17 below. 
Although there is substantially complete photodecomposition at the surface 
of the support, and hence solubility in developer in an overall preexposed 
coating, immersion in a developer solution for a period equal to and even 
somewhat greater than that used for normal development will not cause the 
pre-exposed layer to wash away. This is so because the top surface of the 
coating is substantially unexposed and remains insoluble in the developer 
preventing access of the developer to the photodecomposed zone closest to 
the support. 
When the overall exposed film is imagewise exposed from the other side, 
vertical channels of photodecomposed (and therefore developer soluble) 
matter are formed corresponding to the rays of actinic light, which meet 
the zone of photodecomposed matter already formed by the first overall 
exposure. Developer can readily penetrate in these channels and reach the 
surface of the support to remove the unwanted, non-image areas. 
Development is evidently completed quickly enough to avoid any possibility 
of washing away the entire coating. At most, there may be a slight 
undercutting of the bases of dots forming the image in the case of a 
screened halftone reproduction. The degree of undercutting is insufficient 
to affect the image quality. 
When a 21-Step Stouffer Exposure Scale is imagewise exposed with a normal 
coating, not overall pre-exposed through the support, not only is a long 
exposure required but the scale shows five to six steps of gray tones, 
indicating a similar profile in halftone dots. In contrast, when the 
coating is first given an overall exposure as in the practice of the 
present invention, not only is the imagewise exposure time reduced, as 
previously noted, but additionally, the number of grey steps on the 
Stouffer scale is reduced to one. This indicates that a sharp dot is 
formed, which is considered highly desirable in halftone, screened 
reproduction. 
Also, rather unexpectedly, the coated film may be exposed overall through 
the emulsion and imagewise through the base in any sequence of these two 
operations with a resultant shortening of the imagewise exposure 
requirement, but obviously with a loss of resolution. 
For convenience in defining exposure relations, it is preferred to call 
normal exposure that amount of actinic energy needed to image the coating 
when irradiating from one side only followed, as shown in the examples, by 
standard development in a developer solution normally used for this 
operation. It has been found that if one exposes overall through the 
support to increasing amounts of actinic energy, followed by standard 
development, one reaches a maximum exposure level marked by a noticeable 
deterioration of coating uniformity after normal development when viewed 
by transmitted light. The deterioration may take the form of pinholes, 
suddenly increased susceptibility to scratching, void areas of various 
sizes, and the like. Any greater exposure results in drastic coating loss 
and is useless. 
Any overall exposure through the support under the maximum in which 
highlight dots are not lost after halftone imaging is beneficial within 
the scope of the invention. The longer the overall exposure through the 
base, the shorter is the required imagewise exposure from the other side. 
As a further unexpected beneficial result, contrast is increased over that 
obtained by normal exposure, particularly when higher levels of overall 
exposure are employed, making dots harder. 
Also, it has been found that there is a finite minimum exposure which still 
results in a practical shortening of imagewise exposure. This minimum 
useful overall exposure is about one-half of one percent of the 
aforedefined normal exposure and results in at least a 10% reduction from 
normal exposure. Throughout the range from minimum to maximum there is a 
corresponding shortened imagewise exposure which may be readily determined 
by experiment, in a manner well known in the photographic arts. 
While the invention is of maximum advantage in reducing imagewise exposures 
of the densest coated films, it is also useful in adjusting the exposure 
for foils of relatively low optical density, as for example in a set of 
four-color proofing foils to obtain equal exposure times for all colors. 
This facilitates automation. 
For example, a black foil which required a normal exposure of 320 seconds, 
was made imagewise in only 10 seconds by first exposing it overall through 
the base for 60 seconds. This is an exposure reduction of over 95% from 
the normal. 
Also, rather unexpectedly, the same black foil could be exposed in the 
reverse manner in that overall exposure was made through the emulsion and 
imagewise exposure through the base. This mode is also usable whenever 
maximum resolution is not required and results in a desirable shortening 
of overall exposure. 
The invention is also applicable to Minnesota Mining and Manufacturing 
Corporation's Positive Color Key, U.S. Pat. No. 3,211,553, gaining for 
this product the improved resolution benefit of emulsion-to-emulsion 
exposure. The photosensitive material is a complex with 
p-diazodiphenylamine sensitizer in bi-layered configuration. The diazo 
complex layer is in contact with the support and has a separate color 
layer coated on the top thereof. The film is intended to be exposed 
imagewise through the base and required a 28-second exposure determined by 
experiment. If exposed imagewise through the emulsion under the same light 
source, the required exposure was 720 seconds, which although it gave 
improved resolution, is impractical. However, only 10 seconds of overall 
exposure through the base was needed in order to make possible an 
imagewise exposure of 28 seconds through the emulsion. 
The benefit of the overall exposure is durable, there being no known fading 
of the effect upon storage. Nor are there other observable unwanted side 
effects. This virtue makes possible the convenient use for graphic arts of 
foils at a much later date which have been previously exposed overall 
through the support. 
Such pre-exposed foils may be conveniently handled under safelights such as 
commonly used gold fluorescent lamps which have virtually no actinic 
content. Typical foils have been left under such safelights for as much as 
eight hours with no detectable changes. 
Pre-exposure through one surface of the colored films has the additional 
advantage of decomposing enough of the yellowish-colored diazo sensitizer 
that in selected cases a post-exposure to attain true color value no 
longer is necessary. 
Many factors influence the normal exposure of positive-acting color foils: 
nature and density of colorant, thickness of coating, kind and amount of 
diazo sensitizer, kind and amount of resin binder, solvents used in 
coating, even the nature of the support and coating techniques. By 
prolonged investigation, many of the results of which are set forth in the 
examples, it has been found that in all cases, a valuable exposure 
reduction results from the use of the teachings of this invention. 
The invention will be further illustrated by reference to the following 
specific examples: 
EXAMPLE 1 
A positive-working light-sensitive coating containing: 2.5 parts by weight 
of metacresol-formaldehyde novolak resin, 0.6 part by weight of 
naphthoquinone diazide sulfo ester, as described in Example 1 of U.S. Pat. 
No. 3,148,983, 
1.0 part by weight of powdered graphite, 
8.0 parts by weight of ethylene glycol monoethyl ether acetyl ester 
1.0 part by weight of butyl acetate, and 
1.0 part by weight of xylene 
was coated onto a glass plate for two minutes and dried at a temperature of 
100.degree. C. An aperture mask, similar to one used in a tri-color 
cathode ray tube, was placed in front of the coating and then illuminated 
for 10 minutes with a 1500 watt mercury vapor tube at a distance of 1.5 
feet in order that the exposed areas could be completely removed with an 
alkaline developer solution. 
However, if the sample is first exposed through the glass support for 75 
seconds before or after exposing the coating through the aperture mask for 
105 seconds, an image of equal quality is obtained after development with 
the same alkaline solution for the same length of time. A reduction in 
exposure time of 70 percent is thereby realized. The resulting pattern is 
rendered suitable for laying down phosphor materials in their respective 
positions as described in U.S. Pat. No. 3,365,292. 
EXAMPLE 2 
The light-sensitive coating as described in Example 1 was coated onto a 
polyester film and dried. A positive half-tone film transparency was 
placed in contact with the coated surface and exposed for 10 minutes to a 
1500 watt mercury vapor tube at a distance of 1.5 feet before the image 
could be completely developed with an alkaline aqueous solution. 
An exposure through the polyester support to the same light source for 75 
seconds before or after exposing through the positive transparency for 105 
seconds enabled the coating to be completely removed in the exposed areas 
without loss of image quality when developed with the same alkaline 
developer. 
EXAMPLE 3 
A coating solution as described in Example 1 with the exception that 3.6 
parts of resin instead of 2.5 parts were coated onto a polyimide sheet 
and, after drying, the further procedure as described in Example 2 was 
followed. A reduction in total exposure time of 70 percent was obtained by 
exposure through the support for 75 seconds prior to or after exposure 
through the film transparency. 
EXAMPLE 4 
A light-sensitive coating solution as described in Example 1 containing 1.5 
parts by weight of carbon black instead of the pigment was applied to a 
translucent polyester film. Processing was as described in Example 2, and 
similar results were obtained. 
EXAMPLE 5 
A light-sensitive coating solution as described in Example 1, with the 
exception that 1.5 parts by weight of an organic basic black dye, such as 
HE-801 Fast Black HB, was used instead of the pigment, was applied to a 
clear polyester film. Processing was as described in Example 2 above. A 
high density black image was formed duplicating the original transparency. 
EXAMPLE 6 
A light-sensitive coating solution containing 9 parts by weight Kodak KAR 
(described in U.S. Pat. No. 3,526,503) and 1 part by weight of powdered 
graphite was applied to a polyester film. The exposure source, distance 
and developer were the same as in Example 2. A positive transparency was 
placed in contact with the coated surface and exposed for 5 minutes before 
the image could be completely developed. Another sample of the same 
coating was now exposed overall through the support for 40 seconds. 
Following this pre-exposure, only 50 seconds exposure through the positive 
transparency in contact with the coating was necessary to obtain a 
satisfactory image. Development time was 150 seconds. 
EXAMPLE 7 
A positive-working light-sensitive coating of the following composition was 
dissolved in suitable aliphatic solvents and coated upon a sheet of 
polyester film: 
______________________________________ 
Meta cresol-formaldehyde novolak resin 
1 gram 
Condensation product of trihydroxy benzophenone 
10 grams 
with 2-diazo-1-naphthoquinone-5-sulfochloride 
Solvent soluble, alkali-fast black dye 
6 grams 
______________________________________ 
A black coating of uniform appearance resulted. After removal of the 
solvent, the film was measured in a Hunter colorimeter and a Macbeth color 
densitometer: 
______________________________________ 
Hunter "L" Value 8 
Green Filter Density (Macbeth) 
2.2 
______________________________________ 
Samples of film were exposed overall through the base for various intervals 
using a 5,000 watt mercury halide source at a distance of 30 inches. Half 
of the sample representing each such overall exposure through the base was 
further exposed imagewise from the other side for various times to 
determine needed exposure. The other half was retained. After exposure, 
all samples were developed manually at room temperature for one-half 
minute in an aqueous alkaline developer, examined visually. The exposure 
times and observations after development were as follows: 
______________________________________ 
OVERALL EXPOSURE 
THROUGH BASE IMAGEWISE 
Appearance of film 
EXPOSURE 
Time, seconds 
after development 
Emulsion side; seconds 
______________________________________ 
0 No change from 
original foil 320 
1.3 " 288 
5 " 160 
30 " 30 
60 Slight pinholing 
10 
80 Severe developer attack 
Not usable 
100 Total removal of coating 
Not usable 
______________________________________ 
In this example, 60 seconds is the maximum overall exposure through the 
base. 
EXAMPLE 8 
A sample of the film of Example 7 was exposed overall through the emulsion 
for 5 seconds. When imaged for 160 seconds through the base carrier and 
developed, a duplicate of the original was obtained. Correspondingly, a 
pre-exposure for 10 seconds was made. Now, when imaged for 60 seconds 
through the base and developed, a duplicate of the original was also 
obtained. The maximum overall exposure was found to be 15 seconds, when 
using the same criteria as in Example 7. 
EXAMPLE 9 
The composition of Example 7 was prepared and coated except that only half 
the weight of novolak resin was used. The density of the resulting film 
was 1.2 with the Green Filter on the Macbeth color densitometer, and the 
Hunter "L" value was 19--indicating a less black coating. 
Overall exposures through the base and imagewise through the emulsion were 
made as in Example 7. Corresponding data were: 
______________________________________ 
OVERALL EXPOSURE 
THROUGH BASE 
Appearance of film 
IMAGEWISE EXPOSURE 
Time, seconds 
after development 
Emulsion side; seconds 
______________________________________ 
0 No change 80 
5 No change 30 
10 No change 20 
15 Slight pinholing 
7 
______________________________________ 
EXAMPLE 10 
A positive-working light-sensitive coating of the following composition was 
dissolved in suitable aliphatic solvents and coated upon a sheet of 
polyester film: 
______________________________________ 
Black dye of Example 7 2 grams 
Sensitizer of Example 7 
3 grams 
______________________________________ 
The density of the resultant film was 0.9 with the Green Filter on the 
Macbeth color densitometer and the Hunter "L" value was 29. The film was 
exposed at various times and developed in dilute aqueous alkali and the 
appearances noted as in Example 7. The corresponding data were: 
______________________________________ 
OVERALL EXPOSURE 
THROUGH BASE 
Appearance of film 
IMAGEWISE EXPOSURE 
Time, seconds 
after development 
Emulsion side; seconds 
______________________________________ 
0 No change 40 
4 No change 12 
6 No change 7 
8 Slight pinholing 
4 
______________________________________ 
EXAMPLES 11, 12, 13 
Three colored compositions were dissolved in suitable aliphatic solvents 
and separately coated on a polyester support. The first contained yellow 
dye, the second contained a magenta, and the third contained a cyan dye. 
All dyes were solvent soluble and alkali fast. 
______________________________________ 
Weight in Grams 
Ex- Ex- Ex- 
Component ample 11 ample 12 ample 13 
______________________________________ 
Color Yellow Magenta Cyan 
Dye 3 2 2 
Sensitizer of Example 7 
7 6 7 
Hunter "L" Value 82 42 48 
Color Filter Density (Macbeth) 
0.6 Blue 1.04 1.0 Red 
Green 
______________________________________ 
Samples of each of the films were exposed for varying lengths of time and 
then developed as in Example 7. The corresponding data were identical for 
each of the three colored films: 
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OVERALL EXPOSURE 
THROUGH BASE 
Appearance of film 
IMAGEWISE EXPOSURE 
Time, seconds 
after development 
Emulsion side; seconds 
______________________________________ 
0 No change 20 
0.08 No change 18 
1 No change 15 
2 No change 10 
3 Pinholing (slight) 
3 
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The 0.08 second value was calculated from data obtained with an Aristo Grid 
SD-39 source calibrated against the mercury halide 5,000 watt source used 
in all the other exposures. 
EXAMPLE 14 
The following composition was dissolved in a suitable aliphatic solvent and 
whirler coated on a polyester support: 
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Black dye of Example 7 2.7 grams 
Condensation product of .beta.-naphthol and form- 
aldehyde further reacted with 2-diazo-1-naphtho- 
quinone-5-sulfochloride 4.4 grams 
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The resultant film had a Hunter "L" value of 19 and a Green Filter density 
of 1.25. Its normal exposure time was 80 seconds. When a sample of the 
film was uniformly exposed through the base for 5 seconds and image-wise 
exposed through the emulsion for 30 seconds, an excellent image after 
development was obtained. 
EXAMPLE 15 
The procedure of Example 14 was followed except that the sensitizer used 
was 4.4 grams of the condensation product of cumyl phenol and 
2-diazo-1-naphthoquinone-4-sulfochloride. The same density values were 
obtained as in Example 14. When uniformly exposed through the base for 5 
seconds and imagewise through the emulsion for 30 seconds an excellent 
image after development resulted. 
EXAMPLE 16 
3 M Positive Color Key (black) was exposed to a 5000 watt mercury halide 
source for various intervals to determine normal exposure according to the 
manufacturer's instructions. Twenty-eight seconds through the base was 
found to produce a solid step 4 on a Stouffer stepwedge, after 
development, fixing and postbleaching with light. A series of overall 
exposures were next made through the base, as in Example 7, followed by 
imagewise exposure through the emulsion and development. The results were 
as follows: 
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OVERALL EXPOSURE 
THROUGH BASE 
Appearance of film 
IMAGEWISE EXPOSURE 
Time, seconds 
after development 
Emulsion side; seconds 
______________________________________ 
0 No change 720 
5 No change over 30 
10 Silght pinholding 
28 
15 Coating completely 
-- 
removed 
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EXAMPLE 17 
The positive working light-sensitive coating of Example 7 was coated upon a 
sheet of polyester film at reduced thickness so that the optical density 
of the resulting coating was one-quarter that of the film of Example 7. 
Thus, the green filter density (Macbeth) was 0.55. Four pieces were cut 
and placed one above the other. The combined optical density of the four 
layer was 2.2 with the green filter (Macbeth). A fifth piece of film of 
one-quarter density was used to determine the concentration of sensitizer 
present by means of U.V. spectroscopy. Now the assembly of four layers 
(placed emulsion to base) was exposed from the base direction for 55 
seconds using a 5000 watt mercury halide source at a distance of 30" as in 
Example 7. After exposure, the pieces were separated and individually 
analyzed for photodecomposition of the sensitizer by U.V. spectroscopy. 
The results were as follows: 
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Layer 1 (closest 
lost 98% of its quinone diazide content 
to light source) 
Layer 2 lost 70% of its quinone diazide content 
Layer 3 lost 30% of its quinone diazide content 
Layer 4 (farthest 
lost 15% of its quinone diazide content 
from light source) 
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As can be seen from these data, the photodecomposition is not uniform 
throughout the film but is greatest, closest to the base support and least 
at the surface farthest from the support. Further, this corresponds to the 
greatest photodecomposition at the surface nearest the source of overall 
actinic irradiation. 
It will be obvious to those skilled in the art that many modifications may 
be made within the scope of the present invention without departing from 
the spirit thereof, and the invention includes all such modifications.