CA1080535A - Producing a direct image in doubly exposed vesicular photographic material by pretreatment with an aqueous fluid - Google Patents

Abstract

CYCLED DIRECT IMAGE FILM

ABSTRACT OF THE DISCLOSURE
A process for the production of a direct image in a vesicular photographic material. The film is expos-ed imagewise, degassed and re-exposed and developed by heating. The film is pretreated with an aqueous fluid and is incapable of producing a visible image if not pre-treated.

Description

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 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.
~4 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 ~ -6-s ,. .
~: 7 -` 10~0535 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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~ 20 ." ., ~, , -6a-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 ~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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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 ,, ,,5\
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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 --11-- ~

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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
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~ 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 .

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 ,~ ~ .

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 . ' ~
: 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 A
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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 . .

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

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In 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.