Note: Descriptions are shown in the official language in which they were submitted.
1081053S
The present invention relates to vesicular pho-
tography and more particularly to a way of improving the
uniformity of direct images obtained on vesicular photo-
graphic materials.
A vesicular photographic material is a photo-
graphic material which produces an image in the form of
microscopic bubbles, known as vesicles. The vesicles
scatter light, which increases density in the areas of
the film which contain them. The materials are gènerally
composed of a plastic (referred to as a "vehicle"), or-
dinarily coated onto a backing layer, and containing a
light sensitive agent (referred to as a "sensitizer")
dispersed substantially uniformly in the vehicle, the -~
sensitizer being one which decomposes when irrad"iated
with light or other radiation and thereby releases gas.
The plastic is one which is sufficiently stiff or rigid
to encapsulate the vesicles.
Vesicles are formed by shining light on select-
ed portions of the film in accordance with an image,
causing decomposition of sensitizer in those selected
portions of the vehicle, the amount of sensitizer decom-
posed depending on the intensity and duration of the ex-
posure to light. Generally speaking vesicles are formed
by gently warming the vehicle sufficiently to soften it,
permitting coalescence of gas released by decomposition
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~080535
of the sensitizer into bubbles and for the bubbles to
expand. Then the vehicle is cooled to trap the vesicles.
When the material is developed in the way just
described, the vesicles are formed in the areas which ~
5 have been irradiated. Those areas then become opaque, ~ -
because the vesicles reduce the amount of light which ~ -
can pass through the vehicle. When the vehicle is coat-
ed onto a transparent backingO it produces a photograph-
ic negative because the developed image appears dark in
the areas previously illuminated with light.
For some purposes, it is desirable to produce
a photographic positive~ generally referred to as a dir-~ ~
ect imageO In a direct image, the vesicles appear in ! ,
the areas which have not been exposed to light, i.e.,
the dark portions of the image. U.S. Patent 20911,299
describes a process whereby a direct image can be produc- ~
ed. In that process, the gas generated during the ex- ,
posure is allowed to diffuse from the vehicle. ~hen the
material is reexposed, this time to light which more or
2Q less uniformly illuminates the material and decomposes
whatever sensitizer is left over from the first exposure.
Finally, the material is developed by gentle warming and
vesicles appear, thereby producing the direct image.
Machines capable of performing these successive
steps have been sold. In such machines, the diffusion
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1080S35
step is accelerated by a very mild heating, insufficient
to cause development. Such machines are therefore cap-
able of performing the process continuously, the diffu-
sion step taking place while the vesicular material
moves, from a lamp which causes the first exposure, to
one which provides the second exposure. There also have
been available for many years vesicular materials capable
of performing this process, but there have been difficul-
ties with them. Particularly, they have suffered from
undesirable variations in sensitivity. Such variations
result from unavoidable changes in manufacturing condi-
tions as successive portions of a roll of the material
is made.
It is known that these variations in sensitiv-
ity can be reduced by treating vesicular photographic
materials with a hot aqueous fluid as described in U.S.
Patent 3,149,9710 However, it has not been possible to
apply that process to direct image films. It has been
found that the treatment with hot aqueous fluid increases
the sensitivity of the non-diffused gas remaining after
the first exposure to a sufficient degree for the resid-
ual gas to produce undesirable background density in the
image produced by the second exposure. T~erefore, one-
pass direct image processing as described above has not
been practical with films treated by the process of U.S.
Patent 3,149,971.
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1080S35 - .
The present invention is based on the discovery
that the process of U.S. patent 30149~971 can succe~sful-
ly be applied to a category of vesicular photographic ma-
terials which are characterized by a common photometric
property, without preventing direct image processing.
Therefore, the invention provides a category of vesicu-
lar photographic materials having improved uniformity of
sensitivity which nevertheless are susceptible of direct
image processingO Briefly, the common photometric prop-
erty which characterizes the foregoing discovery is theability of giving a usable photographic image after ex-
` posure and development~ if t~ey have been subjected to
the process of U.S. Patent 3,149~9719 but which do ~t
give that result prior to being subjected to that proc- ~ .
ess, i.e., films which have simply been coated but with-
out a post treatmentO As will be explained further be-
low, these photographic materials~ when processed for
:: -
direct images~ provide a further unanticipated advantage, ;
i.e., greater adju~tability of sensitometric character-
20 istics through adjustment of development conditions. -
The vesicular photographic materials to which
the present invention applies are preferably those in
which the vehicle is characterized by a relatively high
diffusivity as measured by the procedure of U.S. Patent ~ -
25 3,032,414 Such high diffusivity may be achieved by the
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108~535
selection of polymers having high diffusivity as set forth in
patent 3,032,414, or as further described in patent 3,032,414,
diffusivity can be adjusted by blending polymers of high and
low diffusivity. Thus the invention is applicable to vesicular
photographic materials which have a wide variety of polymers
and polymer blends as their vehicles.
In accordance with one broad aspect, the invention
relates to a process for producing a direct image in a vesicular
photographic material which comprises a plastic vehicle coated
onto a backing layer and containing a light sensitive agent
dispersed substantially uniformly in the vehicle, said light
sensitive agent decomposing on irradiation to release a gas,
said process comprising exposing said material imagewise to
actinic radiation, diffusing from said material gas liberated
by the imagewise exposure, reexposing said material to actinic
radiation and developing said material by heating to an elevated
developing temperature to produce a visible image, the
improvement which comprises using a vesicular photographic
material which, prior to said imagewise exposure, has been
contacted with an aqueous fluid at an elevated treatment
temperature, said photographic material being capable of ~:
producing an image only if it receives aqueous treatment and
thereby being incapable of producing a visible image if exposed
to actinic radiation and heated to said developing temperature ~ :
under the same conditions if said material has not been `~
contacted with said aqueous fluid at said elevated temperature.
In general the polymers and polymer blends which ~ ~:
comprise the vehicles of these photographic materials are
characterized by a diffusion constant of 0.17 to 300 x 10 9cm2/
sec at the temperature used for gas diffusion between the first
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and second exposures. However, other values may be
appropriate, as discussed below. The considerations which
lead to selection of this range are related to the time
available for diffusion of gas from the vehicle between the
first and second exposures, the ease with which vesicles can
be produced, the amount of sensitizer present, the thickness
of the vehicle and the efficiency of gas utilization in
producing visible density. The diffusion constant is
controlled through the selection of polymer(s) and any other
additives for the vehicle as well as the temperature at which
gas is diffused from the vehicle. In general the rate of
diffusion increases with the increasing temperature. The
sensitizer concentration has little effect on the rate
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108053,5
of diffusion, but it does affect the amount of gas to be
diffused, and therefore the time required to reduce the
amount of residual gas from the first exposure available
to produce background density. The diffusion rate is of
course reduced if the vehicle is made thicker.
Assuming that the film is being processed at
lO ft~minute, a minimum acceptable speed, and that the
film is allowed to travel 30 feet between its first and
second exposures, the film will have 180 seconds to dif-
fuse gas generated in the first exposure. It is notnecessary to diffuse all of the gas liberated in ~he
first exposure~ It is only necessary that the amount re-
maining is insufficient for producing a visible image if
the film is heated to its development temperatureO This
minimum amount of gas whlch can remain after diffusion
depends on gas utilizationO which is increased by the
process of UOSo patent 3~14909710 ~or example, film not
treated by that process may require all of the gas to
produce a visible image if developed~ whereas treated
film may produce a visible image with only l~/o of its
gas. ~-
The diffusion rate for film is given by ~he
equation
tl = O . 04919I2/D
where tl is the time in seconds required for a t~in film
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~080535
to lose half of its absorbed gas, I is the film thickness
and D is the diffusion constant in cm2/sec. If tl is
approximately 100 secO, as in the above-mentioned maximum
diffusion time illustration~ the diffusion constant is
calculated from the foregoing equation~ depending on the
film thickness, to give the following values:
I (mils) 0.2 0 3 0.4 0.5 006
D x 109 (cm2/sec) 0.17 0.29 0.51 0.79 1.14
If the film is assumed to travel at a faster rate or the
distance between exposure lamps is reduced, so that the
diffusion time is reduced to tl = 1.0 second, the corre-
sponding values are the followingo
I (mils) 002 003 OD4 005 0~6
D x 109 (cm2/sec) 17 29 51 79 114
on this basis it is calculated that the diffusion con-
stant will be in the range 0017 to 114 x 10-9 cm2/sec.
Based on the assumptions of film and printer
mentioned above~ films having gas diffusion constants in
the range 0.17 to 110 x 10-9 cm2/sec may be used. How-
ever, if the film has more efficient gas utilization, sothat essentially complete diffusion is required before
the second exposure, the value of D will be two to three
times higher than quoted above.
Suitable polymer blends for the vehicles accord-
` 108~53S
ing to the present invention are illustrated by the fol-
lowing formulations, in which all parts are by weight,
Formulation
Part A
Saran Resin R 2127 (a copolymer of 75% ,
vinylidene chloride and
25% acrylr~nitrile)....O.... 40 parts
Elvacite 2042 (polyethyl methacrylate).... 35 parts
Epon 1002 (epoxy resin)................... 25 parts
Tetrahydro furan.......................... 60 parts
Methyl ethyl ketone...................... 244 parts
Part~
2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate................... 11.6 parts
acetonitrile..... ,........................ 32 parts
Kodak Polyester Blue dye (Disperse Blue 62).. 0.2 parts
Formulation 2
.
Part A
Saran Resin R2127.......................... 100 parts
- R
Acryloid B66 (Methyl/Butyl methacrylate
copolymer)....................... 50 parts
Epon 1002 ................................... 15 parts
Tetrahydrofuran...... ,................ ,... 120 parts
Methyl ethyl ketone................... .... 380 parts
Part B
2,5-diethoxy-4-morpholino benzene diazonium
fluoborate................................ 12 parts
Acetonitrile................................. 80 parts
:~ _g_
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1080535
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Kodak Polyester Blue Dye ......................................... Ø2 parts
Formulation 3
Part A
VAG~ resin ~partially hydrolyzed vinyl
chloride/vinyl acetate copolymer
(91% vinyl chloride, 3% vinyl ace-
tate, 6h vinyl alcohol by hydroly-
sis))........ ,,,.,,.. ,.. ,.. ..,.,,.,.,.. ., 42 parts
Acryloid B66,,..,,,..,,,.,.,,..,...,,,,..,,.... 20 parts
Elvacite 2042,,,.,,.,,.,....,.,,,.,,,...,.,..,. 20 parts
Epon 1002,.. ,... ,.................. ,.,.. ..,.,...... ,.. ......,.,,.. ..18 parts
- Tetrahydrofuran..... ..,.......... ,..... ,,.,,,,,,... ..54 parts
Methyl ethyl ketone,.,.,,,... .,.. ,.................... .......,,... ,,158 parts
Part B
2,5-dibutoxy-4-morpholino benzene diazonium
- fluoborate,,,,,,,,,,,,,,,,,,,,.,.,,,.,,, 11,6 parts
Acetonitrile,....... .,... ,,... ,,,.,,,,.. ,... , 32 parts
Kodak Polyester blue dye,.... ,,.. ..,............ 0,2 part
Formulation 4
Part A
Acryloid B-44 (methyl methacrylate copolymer) 100 parts
Methyl ethyl ketone,,,,,,,,,.,..,,..,....,,, 200 parts
- Part B
- 2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate.,,...... ,.............. 6 parts
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iO8~5;~
Formulation 5
Part A
Acryloid A-101 (a solution containing 4~%
solid acryloid A-10 (polymethyl methacrylate)
S in 60% methyl ethyl ketone)..................... 50 parts
Acryloid B-44 .................................... 80 parts
Methyl ethyl ketone........................ ~..... 180 parts
part B
2,5-dibutoxy-4-morpholino bénzene
diazonium fluoborate...................... ..... 6 parts
Formulation 6
Part A
Acryloid A-101....... ,.... ,... ,.,,,,,................. 62 parts
~) .
Acryloid B-44~ 50 parts
Acryloid B-72 (e~hyl methacrylate copolymer)... 25 parts
Methyl ethyl ketone.................................. l70 parts
Part B
2,5-dibutoxy-4-morpholino benzene
diazonium ~luoborate............................... 6 parts
Formulation 7
Part A
Elvacite 6024 (methyl methacrylate/n-butyl
- methacrylate copolymer, 40~ solids in
toluene.....................,.,,................... 250 parts
Part B
2,5-dibutoxy-4-morpholino benzene diazonium
fluoborate......................................... 6 parts
methyl ethyl ketone................................... 20 parts
Acetonitrile.......... ,....... ..,.,.......... ,....... , 5 parts
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1080535
Formulation 8
Part A
Epon 1007~ 60 parts
Acryloid A-101..........,.,,,,,,,,,,.... ,.,,,, 100 parts
5 Methyl ethyl ketone.................... ........ 100 parts
part B
2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate.,,,... ,......... ,,. 6 parts
Formulation 9
Part A
~) ,
Epon 1007,,,,,,.......... ,,,,,,,,.,,,.......... 60 parts
Elvacite 2043 (polyethyl methacrylate)......... 40 parts
Methyl ethyl ketone....,,,,,,,,,,,,,,,,,,,,. 160 parts
Part B
15 2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate,.,............... , 6 parts
Formulation 10
Part A
~ .
~ VAGH resin... ,.................. ,.............. 40 parts
,
Acryloid B-66.,,,,,,,,,,,,,,,,,,,...,,.,,.,. 45 parts
.
Epon 1002,,,.,,,,,.,,,,,,,.,,,,,,,,,,,,,,,,, 15 parts
Methyl ethyl ketone,,,,.,,,,,,,,,,,,...,.... 158 parts
Tetrahydrofuran,,,,.,,,,,,,,,,,,,,,,,,.,..., 52 parts
Part B
25 2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate.,,,,,,,................ 6 parts
Acetonitrile,,,,.,....... ,................ ,. 32 parts
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108V53S
Formulation 11
Part A
VAGH resin ...,.,,,,,,,..,,.,,.,,,,,,.,,,,, 26 parts
Elvacite 2042,.. ,,,,,,,,,,,,,,,,,,,.... ,,,, 64 parts -
Epon 1002.................. .,............... 10 parts ~;
Methyl ethyl ketone.. ,,,,.. ..,.,.,,,,,,..... 158 parts
Tetrahydrofuran,,..,,,,....,...,...,,,,,... 52 parts
Part B
2,5-dibutoxy-4-morpholino benzene
10 diazonium fluoborate,,................. ,,,,,.~.......... 6 parts
Acetonitrile.,,,..,,,,,,,,,,,.,,,,.,,,,,.,, 32 parts
Formulation 12
Part A
-
VAGH resin,.......... ,,,,,,,,,,.,,,,,,,,.. ,,, 67 parts
Tyril 750 Resin (styrene-acrylonitrile
copolymer) ,,,,,,,,,,.,,,,,,,,,,,,,,...,. 33 parts
Methyl ethyl ketone.. ,,,,,,.,,,,,,,,,, 300 parts ,
Part B
2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate,,,,,,.,,,,,.,......... 6,7 parts
Formulation 13
Part A
VAGH resin,.,,,,,.... ......,,,,,...... ,,,, 67 parts ~-
, -~
Zerlon 150 (styrene-methyl methacrylate
copolymer),,,,..... ,,,O,,,,,,,,,,... ,....... 33 parts
Methyl ethyl ketone.,,...,..,.,,,,,,,,,,,,, 300 parts
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iO8~535
Part B
2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate....................... 6.7 parts
Formulation 14
5 Part A
VAG ~resin......................................67 parts
Pliolite ACL (styrene-acrylate copolymer)....... 33 parts
Methyl ethyl ketone............................300 parts
Part B
10 2,5-dibutoxy-4-morpholino benzene
diazonium fluoborate....................... 6.7 parts
All of the foregoing formulations may be made by separate-
ly mixing parts A and B and then blending the respective
mixtures. Films may be made by applying the solutions
onto a polyethylene terephthalate film base, and drying
the coatings, say at 160F for 5 minutes, followed by
curing for 5 minutes at 240F. Obviously, other base ma-
terials such as glass may be used.
From the foregoing description, it will be ap-
parent that vehicles which are particularly useful forthis invention correspond to the following general formu-
lations:
VAGH resin 25-50 parts
Acryloid ~~660-45 parts
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: 25 Elvacite 20420-65 parts
1~
Epon 1002 0-20 parts
Methyl ethyl ketone158 parts
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10~05~5
Tetrahydrofuran 52 parts
However,it will be understood that a wide variety of
polymers may be used. In general, acrylate ester poly-
mers and styrene polymers increase the diffusivity of
the vehicle. Therefore, they may be added to polymers
of inherently low diffusivity to render them useful for
the present invention.
The films thus produced then are subjected to
a treatment with an aqueous fluid according to the dis-
closure of U.S. Patent 3,149,971.Briefly this process invol~es
contacting the film with an aqueous fluid, preferably at
an elevated temperature, for a sufficient time to impart
the desired changes in photographic characteristics.
These include a speed increase~ a reduction in photograph-
ic gamma, and improvements in uniformity. As noted in
patent 3,149,971, a very mild haze appears to indicate
approximately the desired degree of treatment.
In the case of the foregoing blends, a suitable
treatment was found to be immersion in water at 200F
for several seconds until a slight haze was seen.
These films, after drying, may be processed ac-
cording to U.S. Patent 2,911,299. Thus films made ac-
cording to the foregoing formulations can then be print-
ed at rates of 20-80 feet per minute on a Kalvar Model
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A
... . . . . . . . . . . . .
lO~S35
410C MultLmode Reproducer. On that machine, after initi-
al exposure, the film passes through a degassing oven for
6 to 24 seconds at 120-180F and then is reexposed uni-
formly.
As noted above, films treated according to the
present invention have advantageous uniformity from roll-
to-roll because they have been treated by ~he process of
U.S. patent 3,149,971 but nevertheless do not produce un-
desirable background when processed for direct image. In
addition, they have been found to possess unusual respon-
siveness of photographic properties to development con-
ditions, when subjected to direct image processing. This
is illustrated by experiments performed on a film whose
emulsion had the following formulation:
. 15 Part A
VAGH resin 42 parts
Acryloi~ B-66 25 parts
R
El~acite 2042 25 parts
;~ Epon 1002 8 parts
20 Tetrahydrofuran 40 parts
Methyl ethyl ketone 180 parts
Part B
2,5-dibutoxy-4-morpholino
benzene diazonium fluoborate 8.0 parts
25 Acetonitriie 25 parts
- Kodak Polyester Blue Dye 0.16 part
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10~0535
This formulation was made and coated as described above
and then the sensitometric characteristics of the film
were determined, both for direct image processing and
reversal processing. The films were exposed at 80 feet
per minute on a Kalvar Model 410C Multimode Reproducer.
Degassiny was carried out for 18 seconds in an oven
maintained at 150F, followed by overall exposure. The
sensitometric characteristics obtained are shown in
curves in the drawing, and are summarized below.
Development Development Bar
Drum Drum Gamma
Curve Dwell Time Temperature (0.1)
B 0.9 second 300F -2.4
C 0.5 second 300F -3.1 ~ -
- 15 F 0.9 second 280F -0.95
G 0.5 second 280F -1.4
It can be seen that changes in development time and tem-
perature produce very significant changes in gamma, much
greater than observed in reversal processing of the same
film, after initial exposure under the same conditions as
above. The characteristics are shown in Figures 1 and 2 ~
and are s D arized below. -
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101~0535
Development Development Bar
Drum Drum Gamma
Curve Dwell Time Temperature (0.1)
, ~
A 0.8 second 300F 3O5
5 D 0.8 second 280F 205
E 0.4 second 280F 2.6
It can be seen that, in the direct image mode,
density and the absolute value of gamma increased very
substantially with increasing development temperature
or decreasing development drum dwell time. The magni-
tude of these ehanges is very surprising.
The drawings also demonstrate that the photo-
graphic materials according to the present invention
have low background density, even though processed for
direct images. In this important respect, they are un-
like more conventional vesicular photographic materials
which have been treated by the process of U.S. Patent
3,149,971. Accordingly~ these materials make it possi-
ble to produce direct images 9 with far greater uniform-
ity than hithertoO
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