GB2074332A

GB2074332A - Imaging Film and Method

Info

Publication number: GB2074332A
Application number: GB8104744A
Authority: GB
Original assignee: Energy Conversion Devices Inc
Current assignee: Energy Conversion Devices Inc
Priority date: 1980-04-18
Filing date: 1981-02-16
Publication date: 1981-10-28
Also published as: BE888422A; CA1156869A; IT1136931B; FR2480675A1; JPS574796A; DE3109068A1; AU6906181A; AU545362B2; JPH0246396B2; IT8120337A0; GB2074332B; FR2480675B1

Abstract

A dry process, high sensitivity imaging film comprising a layer of a dispersion imaging material having a vapor deposited layer of a surface modifying substance such as an organic polymer on at least one surface thereof to provide enhanced sensitivity. A passivation layer desirably is provided on each side of the dispersion imaging material layer to shield the layer from the atmosphere. The multiple-layered structure advantageously is supported on a flexible substrate, and an abrasion resistant, protective overlayer desirable is applied to the outermost, or non-substrate containing layer of the film. The imaging film can serve as high contrast or low contrast (continuous tone) material. Imaging by a laser beam or by a xenon lamp or flash bulb can be effected.

Description

SPECIFICATION Imaging Film and Method The present invention relates to a dry process, high sensitivity imaging film, and to a method of producing such a film. In its more specific aspects, the present invention relates to improvements in the dispersion imaging film disclosed in United States Applications Serial No. 827,470, filed August 25, 1 977, entitled "Method of High Sensitivity Imaging and Imaging Film Therefor", and Serial No. 072,438, filed September 4, 1979, entitled "Imaging Film With Improved Passivating Layers", the latter application being a continuation-in-part application of Serial No.

827,470.

The dry process, high sensitivity imaging film disclosed in the first-mentioned application, that is; Serial No. 827,470, includes a solid, high optical density and substantially opaque layer of dispersion imaging material deposited on a substrate. The layer of dispersion imaging material comprises a plurality of separate layers of different and substantially mutually insoluble components having relatively high melting points and relatively low melting point eutectics, and interfaces between said layers having relatively low melting points.Energy is applied to the layer of dispersion imaging material, in an amount above a certain critical value sufficient to increase the absorbed energy in the dispersion imaging material above a certain critical temperature value related to the relatively low melting points of the interfaces, to substantially melt the low melting point interfaces and incorporate the different and substantially mutually insoluble components of the separate layers into the substantially molten interfaces and, hence, to change the layer to a substantially fluid state in which the surface tension of the dispersion imaging material acts to cause the substantially opaque layer, where subject to said energy, to disperse, or roll back, and change to a discontinuous layer comprising openings and deformed material which are frozen in place following the application of energy and through which openings light can pass for decreasing the optical density thereat. The film can provide high contrast imaging or continuous tone or gray scale imaging. A passivation layer may be deposited on the substrate of the film before the layer of dispersion imaging material is deposited thereon, and a second passivation layer may be deposited on the layer of dispersion imaging material. The passivation layers on each side of the layer of dispersion imaging material act to effectively prevent or substantially reduce oxidation of the dispersion imaging material and, hence, possible deterioration of the optical density of the layer of dispersion imaging material over a period of time.The imaging film of said application preferably also is provided with a protective overcoat layer on the side thereof opposite to that on which the substrate of the imaging film is located.

The high sensitivity imaging film disclosed in copending Application Serial No. 072,438, like the imaging film of Application Serial No.

827,470, comprises a high optical density and substantially opaque layer of a dispersion imaging material carried on a substrate. The dispersion imaging material layer may be comprised of a single, homogeneous region formed of a given element, alloy, or composition, or contiguous layered regions of different elements, alloys, or compositions comprising in totality a single image forming layer. As the title of Serial No. 072,438 indicates, the imaging film disclosed therein incorporates improved passivation layers, which, as in the imaging film of Serial No. 827,470, are positioned on each side of the dispersion imaging material layer.The imaging film can provide high contrast imaging or continuous tone or gray scale imaging, and as in the case of the imaging film of said earlier filed parent application, preferably also is provided with a protective overcoat layer.

In accordance with the present invention, a dry process imaging film has been evolved which can be imaged at minimal applied energy intensity levels thereby providing an imaging film having a sensitivity heretofore unattainable with prior dry process imaging films. Thus, merely by way of illustration, the imaging film of this invention is upwards of a hundred fold more sensitive than the high sensitivity dry process imaging films disclosed in the aforementioned two copending applications. Moreover, and quite unexpectedly, the greatly enhanced sensitivity achieved with the imaging film of the present invention in no way adversely affects the continuous tone properties of the high sensitivity films disclosed in the aforementioned copending applications.In fact, the continuous tone properties of the imaging film of this invention, surprisingly, are extended over a broader range of gray scales than is possible with the high sensitivity imaging films of said copending applications. Furthermore, the greatly enhanced sensitivity of the imaging film of the present invention does not in any way alter the high contrast properties of the films disclosed in said applications. Therefore, the imaging film can effectively serve as a high contrast imaging film having a high gamma or as a continuous tone or gray scale imaging film having a low gamma.The imaging film is equally adaptable to imaging by a beam of radiant energy such as a laser beam of coherent energy which serially scans the film and which may be intensity modulated for determining the amount of dispersion or change to a discontinuous condition of the dispersion image forming material layer, or by a noncoherent radiantenergy afforded by, for example, a Xenon lamp or flash bulb which is applied through an imaging mask having a full format continuous tone imaging pattern. The latter manner of continuous tone or gray scale imaging is particularly applicable to and has great significance in several respects in dry process imaging apparatus for producing microform records from light reflecting hard copy, as disclosed in U.S. Patent No. 3,966,317 and U.S.

Patent No. 4,123,1 57, wherein the light reflecting hard copy is microimaged as a transparency on an intermediate mask film and wherein the microimaged transparency of the mask film is reproduced on the layer of dispersion imaging material by a short pulse of radiant or electromagnetic energy. The uniquely high sensitivity of the imaging film allows for greater tolerances in the lighting, lens system, intermediate mask film and flashing system of the apparatus disclosed in said patents while at the same time enabling faithful and accurate reproduction of microimages of hard copy including line drawings, printed material as well as photographs, or the like. The imaging film of this invention lends itself to production and use in the form of flexible sheets or strips capable of being wound in rolls, thereby facilitating handling and storage of the film before, during and after imaging.The imaging film, in addition, has excellent shelf life and archival properties.

The high sensitivity imaging film of the present invention, in brief, comprises a layer of a dispersion imaging material having a layer of a surface modifying substance in contact with at least one surface, and, in accordance with one embodiment of the invention, both surfaces thereof. The surface modifying substance advantageously comprises an organic material such as an organic polymer which shows very low or poor interfacial adhesion for the dispersion imaging material when the latter is in a substantially liquid or molten state during imaging. In accordance with the method aspects of the invention, the surface modifying substance layer is formed by vapor deposition as exemplified by glow discharge deposition, evaporation, sputtering, or the like.The imaging film of this invention further desirably includes at least one, and most advantageously, two passivation layers which act to shield the dispersion imaging material from reactive elements, such as oxygen, in the atmosphere. The imaging film also further desirable includes a substrate and a protective overlayer on the side of the film opposite to that on which the substrate is located. The substrate and the protective overlayer preferably comprise flexible plastic materials which, in co-operation with the other layers of the imaging film, impart the desired flexibility to the film.

The foregoing, and other features and advantages of the invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawings, in which: Fig. 1 is a greatly enlarged sectional and stylized view through an embodiment of the high sensitivity imaging film of this invention before imaging; Fig. 2 is a sectional view similar to Fig. 1 illustrating the imaging film when it is imaged by the application of relatively low energy above a critical value and having a relatively high optical density to provide a continuous tone or gray scale image on the film; Fig. 3 is a sectional view similar to Fig. 2 illustrating the film when it has been subject to a greater amount of energy above the critical value than was applied in the case of Fig. 2 to provide a continuous tone or gray scale image on the film;; Fig. 4 is a sectional view similar to Figs. 2 and 3 illustrating the imaging film of Fig. 1 when subjected to a still greater amount of energy and providing a high contrast image on the film; Fig. 5 is a greatly enlarged sectional and stylized view through another embodiment of the high sensitivity imaging film of this invention showing the surface modifying substance layer on the side of the dispersion imaging material layer opposite to the side on which it is positioned in the embodiment shown in Figs. 1,2 and 3; Fig. 6 is a greatly enlarged sectional and stylized view through yet another embodiment of the high sensitivity imaging film having a surface modifying substance layer on each side of the dispersion imaging material layer; Fig. 7 is a diagrammatic illustration of a system for the production of the imaging film in a continuous web process; and Fig. 8 is an enlarged schematic view of the glow discharge disposition station of the system shown in Fig. 7.

Referring, now, to Figs. 1,5 and 6, the embodiments of the high sensitivity imaging film illustrated and designated by reference numeral 10 in Fig.1, reference numeral 12 in Fig. 5 and reference numeral 14 in Fig. 6, each includes a substrate 16 which is preferably transparent.

While the substrate 16 may be formed from substantially any substrate material, it is most advantageously formed from a flexible, transparent plastic sheet material. Exemplary of suitable plastic sheet materials are those based upon polyesters, polyamides, cellulose acetates, polyethylenes, and polypropylenes, to mention a few. An especially preferred plastic sheet material is a polyester, namely, polyethylene terephthalate, known as Melinex type 0 microfilm grade sold by IC of America. The thickness of the substrate 1 6 desirably is in the range of about 2 to about 10 mils, preferably from about 3 or 4 to about 7 mils.

The embodiments of the imaging films 10, 12 and 14, as shown, also include a dispersion imaging material layer 18, at least one, and in certain instances, two (see Fig. 6) surface modifying substance layers 20 and two passivation layers 22. The nature of the layers 1 8, 20 and 22 will be discussed in detail below. The films 10, 12 and 14 further desirably are provided with a substantially transparent, protective overlayer 24. The overlayer 24 may comprise a polymeric resin material such as polyurethane, polyvinylidene chloride or a silicone resin. The polyurethane product sold under the designation "Estane No. 5715" (B.F. Goodrich Company), and the polyvinylidene chloride product available commercially under the designation "Saran" (Dow Chemical Company) form excellent overlayers for the imaging film. The thickness of the overlayer 24 can range from about 0.1 to about 3 microns, preferably from about 0.5 to about 1 micron. It can be applied to the imaging film in any of various ways, including spin coating, roller coating, spraying, vacuum deposition, or the like.

The dispersion imaging material layer 18 of the imaging films 10, 12 and 14 may comprise low melting point amorphous semiconductors, exemplified by the chalcogenide elements, except oxygen, and compositions containing them, as disclosed in U.S. Patent No. 4,000,334 and in copending application Serial No, 577,003, filed May 13, 1975, entitled "Method For Full Format Imaging". These include the materials which are known as memory materials and which are characterized by their ability to physically change from one condition to another under the effect of energy. These materials may be used in their amorphous or in their crystalline form.Specific examples of such materials are tellurium and various compositions containing tellurium, and other chalcogenides (parts being by weight) such as, for example, a composition 92.5 atomic parts tellurium, 2.5 atomic parts germanium, 2.5 parts silicon and 2.5 atomic parts arsenic; a composition of 95 atomic parts tellurium and 5 atomic parts silicon; a composition of 90 atomic parts tellurium, 5 atomic parts germanium, 3 atomic parts silicon and 2 atomic parts antimony, to mention a few. The layer 18 also may comprise low melting point metals or metal alloys such as those disclosed in U.S. Patent Nos. 4,082,861 and 4,137,078, and the aforementioned copending application Serial No. 827,470.

Exemplary of such materials are bismuth, alloys of bismuth with tin and lead, tiered layers comprising bismuth and its oxide, and tiered layers comprising bismuth, zinc, lead, tin, cadmium and indium, for example, which form low melting point eutectics at their interfaces.

In this connection, it should be understood that in referring herein to a layer of dispersion imaging material, the term "layer" is intended to encompass a layer of dispersion imaging material which is comprised of one homogeneous region of a given element or composition, or contiguous tiered regions of different elements or compositions which form in totality a single dispersion imaging material layer. The thickness of the layer 18 advantageously is such as to provide an optical density of from about 1 to about 5, preferably from about 1.2 to about 3, in the completed imaging film depending upon the opacity desired.Generally speaking, the optimum objectives of the invention are achieved with dispersion imaging material layer thicknesses of the order of about 200 Angstroms to about 2000 Angstroms, with a thickness in the range of about 250 Angstroms to about 1000 Angstroms being preferred. Deposition of the layer 18 may be accomplished by sputtering, vacuum deposition, or the like.

The layer, or layers, 20 of surface modifying substance comprising the imaging films 10, 12 and 14, as illustrated, are in direct contact with the layer 18 of dispersion imaging material. As indicated hereinabove, the presence of the layer 20, whether it is in contact with one or both surfaces of the layer 18 has the surprising and unexpected effect of increasing, by upwards of a hundred times, the sensitivity of the imaging film of this invention over high sensitivity films such as those disclosed in the aforementioned copending applications Serial Nos. 827,470 and 072,438.

The layer 20 preferably is formed of an organic, or organic-like, material capable, upon being vapor deposited in a manner to place it in contact with one or both of the surfaces of the layer 18 of dispersion imaging material, of forming a thin, flexible and transparent layer on said surface or surfaces. The formed layer 20 is characterized by the very low or poor interfacial adhesion between the material of the layer 20 and the dispersion imaging material of the layer 18 when the material of the layer 18 is in a substantially liquid or melted state during imaging, and, concomitantly, by the apparent ability of the layer 20 to enhance, augment and increase the roll back or dispersion capabilities of the layer 18 when the material thereof is in said state to provide, as indicated above, an imaging film having improved continuous tone and high contrast properties.These factors, coupled with the substantial absence of electrostatic charges at the interface of the layers 18 and 20, enable dispersion or roll back of the dispersion imaging material of the layer 18 to be achieved with substantially less intensity of applied energy than was heretofore possible with dry process imaging films. In addition to the aforementioned desiderata, the layer 20 should be chemically inert with respect to the dispersion imaging material layer, and possess properties of adhesion with respect to the passivation layers consistent with the structural and imaging requirements of the imaging film. Also, for cost effective production, it is desirable that the layer 20 be capable of rapid deposition with standard vapor deposition equipment such as glow discharge deposition, evaporation, sputtering, or the like, apparatus.The thickness of the layer or layers 20 of the surface modifying substance need only be sufficient to change the interfacial adhesion properties of the contiguous surface of the layer 18. This can be effectively achieved with essentially monomolecular thicknesses of the substance. In general, however, the optimum objectives of the invention are attained with surface modifying substance layer thicknesses-up to about 300 Angstroms, preferably from about 25 to about 20Q, or 250, Angstroms.

Exemplary of organic, or organic-like, materials useful in forming the layer 20 of the high sensitivity imaging film of this invention are polymerizable monomeric materials such as methane, ethane, ethene, propane, propene, butane, butene, isobutane, isobutylfluoride, carbon tetrafluoride, carbon hexafluoride, ethylidene fluoride, chlorotrifluoromethane, difluorodichloromethane, isopropylfluoride, isopropylidene fluoride, and the like, and copolymerizable mixtures thereof. Also useful are polymerizable organic-like materials exemplified by monosilane, chlorosilane, methylmonosilane, dimethylsilane, trifluorosilane, and the like, and copolymerizable mixtures thereof. Of the foregoing materials, fluorinated hydrocarbonates, as exemplified by carbon tetrafluoride, are preferred.It is noteworthy that the surface modifying materials useful in forming the layer, or layers, 20 of the imaging film most advantageously are gases. In this form, the materials are more readily adaptable to continuous mass production of the imaging film in a vapor depostion chamber where the various layers of the imaging film are deposited by vacuum deposition or, as in the case of the layer, or layers 20 by glow discharge deposition, evaporation, sputtering, or the like, techniques. It should be understood, however, that surface modifying materials, especially organic, or organic-like materials which normally exist in a liquid state, but which can be easily converted to a gaseous state for vapor deposition as by glow discharge deposition, for example, are contemplated for use in forming the layer or layers 20.Exemplary of such materials are pentane, 1 -pentene, hexane, 1 -hexene, to mention a few.

The passivation layers 22 which comprise the imaging film of this invention can be formed of any material capable of effectively providing a barrier or shield for the dispersion imaging material layer 18 to prevent or substantially limit oxidation of the components of the layer. Specific examples of materials which can be used to form the passivation layers are silicon monoxide and dioxide, aluminum oxide, germanium oxide, tellurium oxide, tin oxide, beryllium oxide, and the like. Especially preferred materials for use in forming the passivation layers are those disclosed in the previously referred to copending application Serial No. 072,438. The materials comprise oxides of Group IV metals. The oxides advantageously are in an amorphous form and are stabilized in this form by alloying them with amorphous oxides or halides of a metal or semiconductor.Specific examples of compositions of this type useful in forming the passivation layers of the imaging film of this invention are the following wherein the subscript numbers indicate the approximate percentage of the crucible mixture by weight of the compounds involved: (G eO2) 70(Al2o3),o(B2o3) .ro(Pbo).ro (GeO2)#80(Al2O3)#10(Pbo).10 (GeO2).85(TiO2).10(Al2o3) .os (GeO2).80(Al2o3).o5(pbo).o5(K2o) 1o (GeO2)#80(Al2O3)#10(PbO)#05(K2O) e05 (GeO2)#70(Al2O3)#10(TiO2)#10(PbO) .05(K20).05 (GeO2).#(AI2O3).10(TiO2) 05(MgO),05(K2O)#05 The passivation layers 22 must be continuous and essentially free of holes or voids.In addition, they must be flexible and not susceptible to cracking or fracturing when the imaging film is wound in a roll. Experience has shown that the required flexibility is attained with passivation layer thicknesses ranging from about 75 to about 450 Angstroms, with a thickness in the range of from about 100 to about 200 Angstroms being especially preferred. The passivation layers are most effectively deposited on the film by vapor deposition using an election beam source.While in the preferred embodiments of the high sensitivity film shown, separate passivation layers 22 are included as an integral component of the film, it should be understood that the layers 22 may not be necessary in those instances where the substrate 16 and the protective overlayer 24, for example, are inherently capable of providing a barrier or shield to prevent or substantially limit oxidation of the dispersion imaging material.

As stated hereinabove, the various layers comprising the imaging film most advantageously are deposited by vapor deposition techniques. The dispersion imaging material layer 18 and the passivation layers 22 desirably are deposited by vacuum deposition, including resistance heating or electron beam deposition. The layer, or layers 20 of surface modifying substance, on the other hand, as indicated above, preferably are deposited by glow discharge, evaporation, sputtering, or the like, techniques. By way of illustration, and with specific reference to Figs. 7 and 8 of the drawings, the deposition of the dispersion imaging film layer 18, the surface modifying substance layer, or layers 20 and the passivation layers 22 may be carried out in a continuous web process. In Fig. 7, there is schematically illustrated apparatus for producing the imaging film of this invention by such a process.The apparatus, designated generally by reference numeral 30, comprises a vacuum chamber 32 having positioned therein a web take-up spool 34, a rotatable metal drum 36 and a web take-up spool 38 with the substrate 16 coursing the same. The apparatus as shown also includes a metal walled glow chamber 40 positioned along the periphery of the metal drum 36, and a plurality of evaporation sources represented by boats 42. The materials contained in the boats 42 may be selectively evaporated by electron beam guns (not shown), for example, and deposited on the substrate 1 6 as it is passed over the drum 36.

The apparatus also preferably includes a web position idler (not shown) arranged between the drum 36 and the web takeup spool 38. In addition, the apparatus also desirably includes a crystal rate controller (not shown) which electronically controls the deposition power of the electron beam guns, and an optical monitor (not shown) for monitoring the depositions of the respective layer materials on the substrate 16 as to optical density. The vacuum chamber 32 is evacuated by means of a vacuum pump 44 through a particle trap 46 and a control valve 48.

As best shown in Fig. 8, the glow chamber 40 includes a cathode 50 connected to an RF or DC power input source, and backed by a suitable insulating material 52 to prevent plasma discharge in undesirable regions. The metal walls of the chamber 40 are connected to an electrical ground (not shown). The materials to be deposited by glow discharge deposition are supplied to the chamber 40 through one or more conduits 54. A pressure gauge 56 is provided to indicate the vacuum pressure in the glow chamber 40 and is used in connection with the control of the vacuum pump 44. The exhausted gas from the chamber 40 escapes into the vacuum chamber 32 through the restricted openings or clearance spaces 58 between the walls of the chamber 40 and the surface of the substrate 16 supported on the drum 36.The drum 36 is attached to an electrical ground connection (not shown) and serves as the ground electrode for the glow discharge deposition of the surface modifying substance layer, or layers 20.

The rotatable drum 36 may be heated or cooled by means of hot or cold water or other fluid which can be circulated through the drum with rotating fluid feed troughs (not shown) which are in communication with the surrounding atmosphere outside of the chamber 32. The temperature of the drum is measured and controlled by measuring and controlling the temperature of the heat-exchange fluid from outside of the chamber 32.

In utilizing the apparatus schematically illustrated in Figs. 7 and 8 to produce the high sensitivity film of this invention, the vacuum chamber 32 is evacuated by means of the pump 44 to less than about 5 x 10-5 Torr and the substrate 1 6 is paid off the payoff spool 34 over the water cooled drum 36 to the takeup spool 38, and reversed back onto the payoff spool 34 at a speed of about 10 ft/min for the purpose of first outgassing the polyester substrate 16.The substrate 16 is then advanced from the payoff spool 34 and has deposited thereon by means of electron beam guns a first passivation layer of about 1 50 Angstroms of GeO2, for example, contained in one of the boats 42, at a rate of about 60 Angstroms/sec and a web speed of about 10 ftimin. The deposition rate is controlled by using a crystal rate controller (not shown) which electronically controls the deposition power of the electron beam guns. The passivation layer coated substrate is then returned to the web payoff spool 34 for the next deposition step.

About a 400 Angstrom layer of bismuth and tin, for example, is then co-evaporated on the passivation layer coated substrate, as it is again advanced toward the boats 42, from another set of electron beam guns at a rate of about 150 Angstroms/sec, with a web speed of about 10 ft/min. The deposition rate is again controlled by the crystal rate controller, and the optical density of the film is monitored by an optical monitor (not shown) during the run. The substrate, with the GeO2 passivation layer and the co-deposited bismuth-tin dispersion imaging material layer is again returned to the web payoff spool 34 for deposition of a layer of surface modifying substance on the dispersion imaging material layer.

As indicated, the space in the glow chamber 40 between the cathode 50 and the electrically grounded metal surface of the drum 36 provides for a glow discharge condition therebetween so as to produce a plasma therebetween. The vacuum chamber 32 is first pumped down by means of the pump 44 to a pressure of about 20 m torr prior to deposition of the surface modifying substance layer. A polymerizable gas comprised of carbon tetrafluoride (CF4), for example, is fed into the glow chamber 40 through one or both of the conduits 54. The gas is fed at a constant ratio of about 10-50 sec/min into the glow chamber 40, the pressure of which is maintained within the range of about 0.1 to 2, preferably 0.5 torr. The partial pressure in the glow chamber 40 and the gas introduced therein provide an atmosphere therein which contains such gas.A plasma is generated in said atmosphere over the coated substrate 16 using a radio frequency power, for example, of about 1000 watts, operating at about 12 to about 15, preferably 13.5 MHz. A layer of about 200 Angstroms of a pclymer based upon the carbon tetrafluoride is deposited on the layer of the dispersion imaging material using a deposition rate of about 10 to about 50, preferably about 30 Angstroms per second.

Following the glow discharge deposition of the surface modifying substance layer, a second layer of a passivation layer comprising GeO2, for example, is deposited on the surface modifying substance layer utilizing the same procedure employed to deposit the first passivation layer. It should be understood that the passivation layers may be formed of the same or different materials.

Thus, the second, or last to be deposited passivation layer may comprise SiO, for example.

Similarly, in those instances where a surface modifying substance layer is provided on each surface of the dispersion imaging material layer as shown in Fig. 6, each of the layers 20 of the surface modifying substance may be formed from the same surface modifying material, or they each may be formed of a different surface modifying material. After deposition of the second passivation layer, the web is then removed from the vacuum chamber and is roller coated with a polymer overcoat having a thickness of about 500 to about 6000 Angstroms. Care is taken in the payoff and takeup spools, both during evaporation depositions and overcoating to control the web tension to avoid scratching, telescoping and so forth of the imaging film.

Referring again, now, to Figs. 1-6 of the drawings, imaging films 10, 12 and 16 may be imaged by energy, such as, for example, non coherent radiant energy from a Xenon lamp or a flashbulb or the like through an imaging mask 26.

The imaging mask 26 can control the amount of non-coherent radiant energy passing therethrough and the amount of energy absorbed in the dispersion imaging material layer 18 and, therefore, can control the amount of dispersion of the dispersion imaging material and the optical density thereof where imaged.

In accordance with this invention, as expressed above, dry process, exceptionally high sensitivity imaging is provided, including high contrast imaging or continuous tone or gray scale imaging, depending upon the nature of the high sensitivity imaging film. In Fig. 1, the portion 26a of the imaging maks 26 has a sufficiently high optical density to limit the amount or intensity of the energy, as shown by the arrows, applied therethrough to the layer 18 of dispersion imaging material, so that the absorbed energy in the material is not increased above the aforesaid certain critical value. As a result, the material is not changed to a substantially fluid state and the layer 1 8 of dispersion imaging material remains in its solid, high optical density and substantially opaque condition.There are no openings in the layer 18 through which light can pass, the layer being substantially opaque and having an optical density of subtantially 1.0 to 1.5 or the like, for example. This stage of imaging is applicable to both the high contrast and the continuous tone or gray scale imaging films produced in accordance with the teachings of the present invention.

In Fig. 2, the portion 26b of the imaging mask 26 has a lower optical density to allow more radiant energy, as shown by the arrows, to pass through and be applied to the layer 18 of dispersion imaging material. Here, the intensity of the applied energy is such that the absorbed energy in the layer 1 8 is just above the aforesaid certain critical value. The layer 18 of dispersion imaging material is changed by such energy to a substantially fluid state in which the surface tension of the material causes the material to disperse and change to a discontinuous film having openings 18a and deformed material 18b which are frozen in place following said application of energy and through which openings 1 8a light can pass.In the case of the continuous tone or gray scale imaging, the dispersion imaging material is deformed only a small amount, as indicated at 18b to provide only small area openings 18a in the layer 18, there being only a small amount of roll back of the deformed material 18b from the openings 18a. The transmissivity of the film is low, but more than that of the substantially opaque undispersed films 10, 12 and 14 shown in Figs. 5 and 6. Thus, the optical density of the film, where subject to such application of energy, is decreased a small amount. The area of the substantially opaque deformed material 18b is extremely large while the area of the openings 18a is extremely small.

In Fig. 3, the portion 26c of the imaging mask 26 has a lower optical density to allow still more radiant energy, as shown by the arrows, to pass therethrough and be applied to the layer 18 of the dispersion imaging material. The intensity of the applied energy is such that the absorbed energy in the layer 18 is considerably above the aforesaid certain critical value. Because of the increased intensity of the applied energy, the dispersion imaging material is deformed a greater extent as indicated at 1 8b to provide larger area openings 1 8a in the layer 18, there being a larger amount of roll back of the deformed material 1 8c from the openings 1 8a. The transmissivity of the film is thus increased, the optical density thereof decreased a greater amount.

In Fig. 4, the portion 26d of the imaging mask 26 has a still lesser optical density to allow still more radiant energy, as shown by the arrows, to pass therethrough and be applied to the layer 18 of dispersion imaging material. Here, the intensity of the applied energy is such that the absorbed energy in the film is still more above the aforesaid certain critical value, substantially a maximum value. Because of this further increased intensity of the applied energy, the dispersion imaging material is deformed a greater extent to small spaced globules 1 8c and the openings 1 8a are increased to form substantially free space between the globules, there being a larger roll back of the deformed material 1 8c from the openings 1 8a.The trnnsmissivity of the film is thus increased to a maximum and the optical density thereof decreased to a minimum.

As distinguished from the continuous tone or gray scale imaging having the intermediate steps illustrated in Figs. 2 and 3, in the vigh contrast imaging, upon the formation of the openings 1 8a and the deformed material 1 by, there is a substantial instantaneous and complete roll back of the imaging material to the discontinuous film condition illustrated in Fig. 4.

The embodiments 12 and 14 of the imaging film illustrated in Figs. 5 and 6 differ from the embodiment of the film 10 shown in Figs. 1-4 in that the surface modifying substance layer 20 in the imaging film 12 is positioned on the surface of the dispersion imaging material layer 18 opposite to the surface on which it is positioned in the film 10, while in the fiml 14, a layer 20 of surface modifying substance is positioned on, or in contact with, each surface of the layer 18.

The energy employed to image the film of the present invention may comprise various forms of energy. Thus, the energy may comprise Joule heat energy applied to the film by means of, for example, direct electrical heating, electrically energized heating means, or the like, and absorbed in the film. The intensity of the applied Joule heat energy above the certain critical value may determine the amount of dispersion or change of the film to the discontinuous film for continuous tone imaging, as discussed above. The heating means may include a single heating point which serially scans the film and which is intensity modulated, or it may comprise an advanceable matrix of heating points which are intensity modulated, for full format imaging of the film. In both cases continuous tone imaging may be obtained.The applied energy may also comprise a beam of radiant energy, such as, a laser beam of coherent energy or the like, which serially scans the film and which may be intensity modulated for determining the amount of dispersion or change to the discontinuous film and providing continuous tone or gray scale imaging.

This applied energy may also be non-coherent radiantenergy, afforded by, for example, a Xenon lamp or flash bulb or the like, which is applied through an imaging mask such as the mask 26 which may have a full format continuous tone imaging pattern including portions of continuously differing transmissivity for the applied energy, to the substantially opaque film of dispersion imaging material substantially evenly in a full format pattern corresponding to the full format continuous tone imaging pattern of the imaging mask and having areas of different intensities of the applied energy above the certain critical value to provide at one time in the substantially opaque film of dispersion imaging material a stable finished full format image pattern of discontinuous film corresponding to the full format continuous tone pattern of the applied energy.In this instance the energy is preferably applied as a short pulse of said energy.

As expressed above, this invention is principally directed to a high sensitivity imaging film requiring only a minimum amount of applied energy to change the imaging film from a solid high optical density film to a discontinuous film of lower optical density. In order to demonstrate the unexpected and exceptionally high sensitivity of the imaging film, an imaging film is prepared in accordance with the teachings of the present invention, and compared with high sensitivity imaging film prepared as disclosed in the aforementioned copening application Serial No.

827,470. The dispersion imaging material layer in each case is comprised of a codeposited layer of bismuth and tin approximately 400 Angstroms thick. The film prepared as disclosed in the said copending application has transparent passivation layers approximately 150 Angstroms in thickness comprised of germanium oxide in contact with both the inner or substrate-facing side of the dispersion imaging material layer and the outer, or overlayer-facing side of the dispersion imaging material. The dispersion image material layers and the passivation layers are supported on a transparent polyester substrate about 5 mils thick. A transparent overlayer about 5000 Angstroms thick and comprised of polyurethane is applied to the upper or outer passivation layer.

The maximum optical density (ODmax) of the film is about 1.6. The threshold energy value (Eth) of the film is about 0.15 J/cm2; the Admin is about 0.18; and the applied maximum energy value (Ernax) is about 0.6 J/cm2.

The imaging film of this invention differed from the film prepared as disclosed in said copending application in that a polymerized, transparent layer of carbon tetrafluoride approximately 150 Angstroms in thickness is applied to the upper, or non-substrate facing surface of the bismuth-tin dispersion imaging material layer before the GeO2 passivation layer is deposited. The construction of the film otherwise is the same as the film of the copending application. Before imaging the optical density (0may) of the film is about 1.6. The threshold energy value (Eth) of the film is about 0.002 J/cm2; the ODmin is about 0.20; and the applied energy (Ernax) for obtaining maximum dispersion is about 0.008 J/cm2. Thus, it is seen that the energy required to disperse or roll back the dispersion imaging layer of the imaging film of the present invention is of the order of seventyfive times less than is required in the case of the film prepared as disclosed in copending application Serial No.827,470, which film itself is characterized by its high sensitivity. The sensitivity of the imaging film of this invention is even greater when two layers of a polymerized substance are used as illustrated in Fig. 6 of the drawings.

While for purposes of illustration various forms of this invention have been disclosed, other forms thereof may become apparent to those skilled in the art upon reference to this disclosure and, therefore, this invention should be limited only by the scope of the appended claims.

Claims

1. A dry process, high sensitivity imaging film, comprising: a substantially continuous opaque layer of a dispersion imaging material, said dispersion imaging material, upon application of energy to the imaging film in an amount sufficient to increase the absorbed energy in the dispersion imaging material above a certain critical value, being capable of changing to a substantially fluid state in which the surface tension of the dispersion imaging material acts to cause the substantially continuous opaque layer where subject to said energy to disperse and change to a discontinuous layer; and at least one layer of a vapor deposited surface modifying substance in contact with the layer of dispersion imaging material, said surface modifying substance layer being energy transmissive and having minimal interfacial adhesion with respect to the dispersion imaging material thereby enabling dispersion or roll back of the dispersion imaging material in its substantially fluid state to take place at minimal intensities of applied energy.

2. An imaging film according to claim 1, wherein the surface modifying substance layer comprises a polymerizable organic or organic-like material.

3. An imaging film according to claim 1, wherein the thickness of the surface modifying substance layer is at least monomolecular.

4. An imaging film according to claim 1, wherein a layer of the surface modifying substance is provided on each side of the dispersion imaging material layer.

5. An imaging film according to claim 1, wherein the dispersion imaging material layer and the surface modifying substance layer are supported on a substrate.

6. An imaging film according to claim 1, wherein a transparent, protective polymeric overlayer is provided for the dispersion imaging material layer and the surface modifying substance layer.

7. An imaging film according to claim 1, wherein at least one passivation layer is provided for the dispersion imaging material layer to substantially prevent oxidation of the material comprising the dispersion imaging material layer.

8. An imaging film according to claim 7, wherein a passivation layer is provided for each side of the dispersion imaging material layer.

9. An imaging film according to claim 5, wherein the substrate has a passivation layer on the side thereof on which the dispersion imaging material layer and the surface modifying substance layer are supported.

10. An imaging film according to claim 4, wherein each of the surface modifying substance layers are positioned on opposite sides of the dispersion imaging material layer, and a passivation layer is provided on each of the sides of the surface modifying substance layers not in contact with the dispersion imaging material layer.

11. An imaging film according to claim 10, wherein one of the passivation layers is in contact with a flexible substrate, and the other passivation layer is in contact with a flexible protective overlayer.

12. An imaging film according to claim 4, wherein the layers of the surface modifying substance are transparent and flexible.

13. An imaging film according to claim 8, wherein the passivation layers are transparent and energy transmissive.

14. An imaging film according to claim 2, wherein the polymerizable material comprises a fluorinated hydrocarbon.

1 5. An imaging film according to claim 1, wherein the dispersion imaging material comprises bismuth or an alloy thereof.

16. An imaging film according to claim 1, wherein the dispersion imaging material comprises a plurality of separate layers of different and substantially mutually insoluble components having relatively high melting points and relatively low melting point eutectics and interfaces between said layers having relatively low melting points, said layer of dispersion imaging material, upon application of energy in an amount above a certain critical value sufficient to increase the absorbed energy in the layer material above a certain critical temperature value related to the relatively low melting points of the interfaces, being capable of changing to a substantially fluid state in which the surface tension of the layer material acts to cause the substantially opaque layer, where subject to said energy, to disperse and change to a discontinuous layer comprising openings and deformed material which are frozen in place following said application of energy and through which openings light can pass for decreasing the optical density thereat.

17. An imaging film according to claim 16 wherein the interfaces between said layers include a layer of a eutectic mixture of the separate components for providing the interfaces with low melting points.

18. An imaging film according to claim 16, wherein the atomic weight percents of the respective components of the separate layers of the dispersion imaging material correspond substantially to the atomic weight percents of the eutectic of said components.

19. An imaging film according to claim 16, wherein the atomic weight percents of the respective components of the separate layers of the dispersion imaging material are substantially different from the atomic weight percents of the eutectic of said components.

20. A dry process, high sensitivity imaging film, comprising: a substrate; a passivation layer on a surface of the substrate; a layer of a polymerized organic or organic-like surface modifying substance on the passivation layer; a layer of a dispersion imaging material on the polymerized substance layer; and a passivation layer on the dispersion imaging material layer.

21. An imaging film according to claim 20, wherein a second layer of a polymerized organic or organic-like surface modifying substance is deposited between the dispersion imaging material layer and the last-mentioned passivation layer.

22. An imaging film according to claim 20, wherein all of said layers on each side of the dispersion imaging material layers are transparent, energy transmissive and flexible.

23. An imaging film according to claim 20, wherein the polymerized substance layer comprises a fluorinated hydrocarbon.

24. An imaging film according to claim 23, wherein the polymerized substance layer comprises a polymer formed of carbon tetrafluoride.

25. An imaging film according to claim 20, wherein a polymeric overcoat layer is provided on the last-mentioned passivation layer.

26. An imaging film according to claim 20, wherein the substrate is formed of a flexible polyester sheet material.

27. An imaging film according to claim 20, wherein the passivation layers are each formed of a different material.

28. An imaging film according to claim 20, wherein the dispersion imaging material layer comprises a plurality of sets of separate layers of different and substantially mutually insoluble components, and layers of a solid material interposed between said sets of layers, which solid material is capable of remaining solid when said layer of dispersion imaging material is changed to its substantially fluid state upon the application of energy thereto.

29. An imaging film according to claim 21, wherein the second layer of polymerized substance is formed of a material which is different from the other layer of polymerized substance.

30. An imaging film according to claim 29, wherein the second layer of polymerized substance comprises a vapor deposited polymer of ethene.

31. An imaging film according to claim 20, wherein the passivation layers comprise an amorphous oxide of a Group IV metal.

32. An imaging film according to claim 31, wherein the oxide is germanium oxide.

33. An imaging film according to claim 20, wherein the polymerized substance layer is formed of a gaseous polymerizable organic compound.

34. A method of making a high sensitivity imaging film comprising: depositing on a substrate successive and separate layers of a dispersion imaging material, a surface modifying substance and a passivation material, the layer of surface modifying substance being deposited in a manner to place it in contact with the dispersion imaging material layer and the passivation material layer.

35. A method according to claim 34, wherein the surface modifying substance layer is deposited by vapor deposition to provide a polymeric layer which is transparent and energy transmissive.

36. A method according to claim 35, wherein glow discharge deposition is used to deposit the surface modifying substance layer.

37. A method according to claim 34, wherein the dispersion imaging material layer is deposited in a manner to sandwich it between at least one surface modifying substance layer and a passivation material layer.

38. A method according to claim 34, wherein the successive and separate layers are deposited in a manner to provide a layer of surface modifying substance on each side of and in contact with the dispersion imaging material layer.

39. A method according to claim 34, wherein two passivation layers are deposited in a manner to place one, only, of the passivation layers in contact with the dispersion imaging film layer.

40. A method according to claim 38, wherein separate passivation layers are deposited in a manner to place them in contact with the surface modifying substance layers.

41. A method according to claim 34, wherein vacuum deposition is employed to deposit the dispersion imaging material and the passivation material layers.

42. A method according to claim 34, wherein an overcoat layer formed of a polymeric resin is applied on the side of said layers opposite to the side on which the substrate is located.

43. A method according to claim 34, wherein the surface modifying substance layer is formed of a fluorinated hydrocarbon.

44. A method according to claim 34, wherein the passivation material is an amorphous oxide of a Group IV metal.

45. A method according to claim 44, wherein the oxide is germanium oxide.

46. A method according to claim 34, wherein the dispersion imaging material is bismuth, or an alloy thereof.

47. A method according to claim 34, wherein the dispersion imaging material layer is formed by depositing a plurality of separate layers of different and substantially mutually insoluble components having relatively high melting points and relatively low melting point eutectics and including interfaces between said layers having relatively low melting points, said deposited film of dispersion imaging material, upon application of energy in an amount above a certain critical value sufficient to increase the absorbed energy in the film material above a certain critical temperature related to the relatively low melting points of the interfaces, being capable of changing to a substantially fluid state in which the surface tension of the film material acts to cause the substantially opaque film, where subject to said energy, to disperse and change to a discontinuous film comprising openings and deformed material which are frozen in place following said application of energy and through which opening light can pass for decreasing the optical density thereat.

48. A method according to claim 47, wherein the separate layers of different and substantially mutually insoluble components are vacuum deposited in sequence.

49. A method according to claim 34, wherein said layers are deposited in a manner to provide a dispersion imaging material layer sandwiched between two surface modifying substance layers, the surface modifying substance layers and dispersion imaging material layer, in turn, being sandwiched between two passivation material layers.

50. A method according to claim 49, wherein each of the surface modifying substance layers are formed of the same or a different surface modifying material.

51. An imaging film substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4, 5 or 6 of the accompanying drawings.

52. A method for forming an imaging film substantially as hereinbefore described with reference to the accompanying drawings.