IL25681A - Imaging for use in photography - Google Patents

Description

'iiinji |iiD TJini^n ·π PATENT ATTORNEYS · □ 1 D 1 D 3 'DUD DR. REINHOLD COHN 9<¾-ί¾ i Τ^ΊΤ^Ϊδ MY^H) |Π3 ΠΙΠ_"Ί ' Π OR. MICHAEL COHN ^ ^¾ UJUJ ,Π . IK.'D Π ISRAEL SHACHTER B.Sc. h__g pig Q.3 η D 3111 1 N T LU ' PATENTS AND DESIGNS ORDINANCE SPECIFICATION Improvements in imaging for use in photography oiV'sa wio'w ni'iai mayna e» i av I (we) XfiROX GOxiPOBASIOH, a Body Corporate organized under the ia s of the State of He York, of Rochester, New York 14603, U.S.Δ* do hereby declare the nature of this invention and in what manner the same is to be performed, to he particularly described and ascertained in and by the following statement: - The present invention relates in general to imaging and, more specifically, to a new system for the formation of 3 very high gamma images by layer transfer in image configuration. 4 Although imaging techniques based on layer transfer 5 of a colored material have been known in the past, these β techniques have always been clumsy and difficult to operate 7 because they depend upon photochemical reactions and generall S involve the use of distinct layer materials for the two 0 functions of image-wise transfer and image coloration. A 0 typical example of the complex structures and sensitive 1 materials employed in prior art techniques is described in 2 U. S. patent 3,091,52 to Buskes. Not only does this 8 type of prior' art imaging system tend toward complexity in 4 structure in that it employs' separate materials for final image 5 coloration and image-wise transfer, but, in addition, image-wise 6 transfer generally depends upon a photo-induced chemical 7 reaction which changes the adherence of the layer so exposed. 8 The offecEIvoriesε of ehis cye of .photochemical reaction 0 depends, in turn, upon the vagaries of catalysts used in this 0 system, temperature, pH and many other factors which influence 1 the speed and effectiveness of chemical reactions in general. 2 Many of the prior art systems employ light-sensitive 3 compounds which are, of course, notoriously slow in their 4 response to light. In addition, because of the complexities 5 and critical nature of prior art systems they are for -the 6 most part, difficult and expensive to prepare, in the fir.;;: insctouce and then can only be used by trained operators.

It Is the object of the presen invention to provide & comparatively simple imaging process for simultaneously forming a positive and a negative* The present invention provides a method of Imaging comprising the steps off (a) providing a cohesively weak electrically photosensitive imaging layer sandwiched between a first layer and a second layer? (b) applying an electric field across said imaging laye f (o) exposing said imaging layer to a pattern of actinic electromagnetic radiation; and, (d) separating under said electric field said first layer from said second laye whereby said Imaging layer fractures in imagewlse coniguration i a posi ive image adhering to one of said first and second layers and a negative Image adhering to the othe of said first and second layers* She imaging member comprising the first layer* the imaging layer and the second layer is herein referred to as a "manifold set"; the Xatter term is to he in erpreted accordingly and, for example* when the imaging layer is yellow the imaging member is referred to as a yellow manifold set* She invention further provides an imaging member comprising a first layer, a second layer, and an electrically photosensitive cohesively weak imaging layer sandwiched between said first and second layers, at least one of said first and second layers being at least martially transparent to actinic electromagnetic radiation* The invention further provides imaging apparatus for carrying out the method of the invention comprisin a sub- sufficien residual solvent afer having been coated on ine substrate from a solution or paste. fhe activating step servesthe dual function of making the top surface of the imaging layer slightly tae¾y and, at the same time, weakening it structurally so that it ean he fractured more easily along a sharp line rtileh defines the Image to he reproduced* Qnee the imaging layer is activated, a receiver sheet is laid down over its surface. An electrical field is then applied across this manifo^ld set, preferably while it is exposed to a pattern of light and shadow representative of the image to he reproduced. Upon separation of the donor substrate and receiver sheet, the imaging layer fractures along the lines de ined by the pattern of light and shadow to which it has been exposed with part of this layer being transferred to the receiver sheet while the remainder is retained on the donor substrate so that a positive Image Is produced on one while a negative is produced on the other.

At least one of the donor substrate and the. receiver sheet is transparent and, in fact, both may be transparent so that exposure may be made from either side of the manifold set.

The manifold set may include separate electrodes on opposite sides of the donor substrate and receiver sheet for the application of the field or they may be directly on the back surfaces of these members and integral therewith. In another field application technique, one or both of the donor substrate and receiver sheet may be made of a conductive material. At least one of these is transparent so as to permit exposure of the imaging layer through this electrode. The imaging layer serves the dual function of imparting light sensitivity to the system while at the same time acting as the colorant for the final image produced, although other colorants such as dyes and pigments may be added, to it so as to intensif or medify Ch§ color of the final Images produced when image color is important. The imaging layer may be homogeneous; however, in a preferred form of the invm tion which has produced superior results a material such as a pigment, which is preferably metal-free phthalocyanine, is dispersed in a cohesively weak insulating binder. Other materials including particles made up of two or more layers, blends of materials, complexes, photoresponsive polymers, etc.' may also be dispersed in this type of binder.

In order that the invention will be clearly understood reference is now made to the accompanying drawings in which an embodiment of the invention is illustrated by way of example ' sensitivity required, the spectral sensitivity, the degree of contrast desired in the final image, whether a heterogeneous or a homogeneous system is desired and similar considerations. Typical photoconductors include substituted and unsubstituted phthalocyanine, quinacridones, zinc oxide, mercuric sulfide, Algol yellow (C.I. No. 67,300), cadmium sulfide, cadmium selenide, Indofast brilliant scarlet toner (C.I. No. 71,140), zinc sulfide, selenium, antimony sulfide, mercuric oxide, indium trisulfide, titanium dioxide, arsenic sulfide, Pb^ O , gallium triselenide, zinc cadmium sulfide, lead iodide, lead selenide, lead sulfide, lead telluride, lead chromate, gallium telluride, mercuric selenide, and the iodides, sulfides, selenides and tellurides of bismuth aluminum and molybdenum.

Others include the more soluble organic photoconductors (which facilitate the fabrication of homogeneous systems) especially when these are complexed with small amounts (up to about 5%) of suitable Lewis acids. Typical of these organic photoconducto . are 4,5-diphenylimidazolidinone; 4,5-diphenylimidazolidinethione; 4,5-bis- (4'-amino-phenyl)-imidazolidinone;l,5-dicyanonaphthalene; 1,4-dicyanonaphthalene aminophthalodinitrile; nitrophthal^di-nitrile; 1,2,5,6- tetraazacyclooctatetraene- (2,4,6,8) ; 3,4-di- (4*-methoxy-phenyl)-7,8-diphenyl-1,2,5,6-tetraazacyclooctate-traene- (2,4,6,8); 3,4-di- (4'-phenoxy-phenyl-7,8-diphenyl-1,2,5,6-tetraaza-cyclooctatetraene- (2,4,6,8) ; 3,4,7,8-tetramethoxy-1,2,5,6- tetraaza-cyclooctatetraene- (2,4,6,8) ; 2-mercapto-benzthiazole; 2-phenyl-4-diphenylidene-oxazolone; 2-phenyl-4-p-methoxy-benzylidene-oxazolone; 6-hydroxy-2-phenyl-3- (p-dimethylamino phenyl)-benzofurane; 6-hydroxy-2,3-di- (p-methoxy-phenyl)-benzofurane; 2,3,5,6- tetra- (p-methoxyphenyl)-furo-(3, 2f)-benzofurane; 4-dimethylamino-benzylidene-ben2hydraside furfurylidene- (2)-4' -dimethy1amino-benzhydrazide ; 5-benzilidene- amino-acenaph hene; 3-benzylidene-amino-carbazole; (4-N»N- dimeth lamino-benzy1idene) -p-N,N-dimethylaminoaniline; ; (2-nitro-benzylidene)-p-bromo-aniline ; N,N-dime hyl-N*- (2-nitro-4-cyano-benzylidene)-p-phenylene-diamin ; 2,4,- diphenyl-quinazoline ; 2- (48 -amino-phenyl) -4-phenyl-quinazoline ; 2-pheny1-4- (4' -di-methy1-amino-pheny1)- 7-methoxy-quinazoline; 1.3-diphenyl- tetrahydroimidazole; 1,3-di- (4'chlorophenyl)- tetrahydroimidazole; 1,3-diphenyl-2-4' -dimethyl amino phenyl)- tetrahydroimidazole; 1,3-di- (p- tolyl)-2- [quinolyl- (28-7j -tetra- hydroimidazole; 3- (4'-dime hylamino-phenyl)-5- (4"-methoxy- phenyl-6-phenyl-l,2,4-triazine; 3-pyridyl- (4')-5- (4"-dimethyl- amino-phenyl)-6-phenyl-1,2,4- triazine ;3, (4 -amino-phenyl)- (l'J -1,3,4- triazole; l,5-diphenyl-3-methyl-pyrazoline; 1,3,4,5- tetraphenyl-pyrazoline ; 1-methyl-2- (3 '48 - dihydroxy- methylene-phenyl)-benzimidazole; 2- (4 -dimethylamino phenyl)- benzoxazole; 2- (4'-methoxyphenyl)-*benzthiazole; 2,5-bis- p- aminophenyl- (1)J -1,3,4-oxidiazole; 4 , 5-diphenyl- imidazolone ; 3,-aminocarbazole; copolymers and mixtures thereof. Any suitable) Lewis acid (electron acceptor) may be employed under complexing conditions with many of the aforementioned more soluble organic materials and also with many of the more insoluble organises co impart very important increases in photosensitivity to those materials. Typical Lewis acids are 2,4,7- rinitro- 9- fluo enone; 2,4,5,7- etranitro- 9- fluorenone; picric acid; 1,3,5- trinitro-benzene chloranil; benzo-quinone; 2,5-dichlorobenzoquinoiie; 2-6-dichlorobenzo-quinone; chloranil ; naph hoquinone- (1. ) ; 2,3-dichloronaphthoquinone- (1,4) ; anthraquinone ; 2-mothyl- anthraquinone-2-carboxylie acid; 1,5-dichloroanthraquinone, l-chloro-4-nitroanthraquinone ; phenanthrene-quinone; acenaphthene- quinone; pyranthrenequinone ; chrysene- uinone; thio-naphthene- quinone; a hraquinone-1 , 8-disulfonic acid and anthraquinone-2-aldehyde; triphthaloyl-benzene aldehydes such as bromal, 4-nitrobenzaldehyde; 2, 6-di~chlorobenzaldehyde-2, ethoxy-1-naphthaldehyde; anthracene-9- aldehyde; pyrene-3-aldehyde; oxindole-3-aldehyde; pyridine-2,6-dialdehyde, biphenyl-4-aldehyde ; organic phosphonic acids such as 4-chloro-3-nitro-benzene-phosphonic acid; nitrophenols ; such as 4-nitrophenol and picric acid; acid anhydrides; for example, acetic-anydride, succinic anhydride, maleic anhydride; phthalic anydride, tetrachloro-phthalic anhydride; perylene 3,4, 9,10- tetracarboxylic acid and chrysene-2,3 ,8, 9- etracarboxylic anhydride; di-brcmo maleic acid anhydride; metal-halides of the metals and metalloids of the groups IB, II through to group VIII of the periodical system, for example: aluminum chloride, zinc chloride, ferric chloride, tin tetrachloride (stannic chloride) ; arsenic trichloride; stannous chloride; antimony pentachloride, magnesium chloride, magnesium bromide, calcium bromide, calcium iodide, strontium bromide, chromic bromide, manganous chloride, cobaltous chloride, cobaltic chloride, cupric bromide, eerie chiorioe, thorium chloride; arsenic tri- iodide; boron halide ccmpouiids , for example: boron trifluoride and boron trichloride; axul ketones, such as acetophanone benzophenone; 2--ioetyi~naphihalene; benzil; benzoin; 5-bea-ioyl acenaphthene, bi^caae-dione, S-acotyl-anthracene, 9-benzoyl- anthracene; 4- (4-disivithylami-no-cinnamoyl)-l-acetylbensene; acetoacetic acid anilide; ir:dandione~ (1, 3) ( · (1-3-diketo-hydrindene) ; acenaphthene quinone- ichlGride; anisil, 2 2- ridil furil mineral acids such as the h dro en halides monochloro-acetic acid; dichloro-acetic acid; Crichloro-acetic acid; phenylacetic acid; and ό-iaethy1-couraarinylacetic acid (4); maleic acid, cinnamic acid; benzoic acid; 1- (4-diethyl- amine—benzoyl)-benzene-2-carboxylie acid; phihalic acid; and tetrachlorophthalic acid; alpha-beta-di-bromo-beta- fora X- acrylic acid (mucobromic acid); dibromo-maleic acid; 2-bromo-benzoic acid; gallic acid; 3-nitro-2-hydroxyl-l-benzoic acid; 2-ni ro phenoxy-acetic acid, 2-nitro-benzoic acid; 3-nitro benzoic acid; 4-nitro-benzoic acid; ' 3-nitro-4-ethoxy-benzoic acid; 2-chloro-4-nitro-l-benzoic acid, 2-chloro-4-nitro~l-benzoic acid, 3-nitx"o-4-methoxy-benzoic acid, 4-nitro-l-methyl-benzoic acid; 2-chloro-5-nitro-l-benzoic acid; 3-chloro~6-nitro-l-benzoic acid; 4-chloro-3-nitro-l-benzoic acid; 5-ehlora-3-nitro-2 hydroxy-benzoic acid; 4-chloro-2-hydroxy~benzoic acid; 2,4-dinitro-l-benzoic acid; 2-bromo-5-nitro-benzoic acid; 4-chloro-phenyl-acetic acid; 2-chloro-cinnamic acid; 2-cyano-cinnamic acid; 2,4-dichlorobenzoic acid; 3,5-dinitro-benzoie. cid; 3,5-dinitro-saljcylic acid; malonic acid; mucic acid; acsto-salycylic acid; benzilic acid; butane- etra-carboxyiie acid; citric acid; cyano-acetic acid; cyclo-hexane-dicarbo;ylic acid; cyclo-hexane-carboxylic acid; 9, 10-dichloro- stearic acid; furaaric acid ; itaconic acid; levulinic acid; (lev lie aci 3} ; malic acid; succinic acid; alpha-bromo-stearie acid; citraionic acid; dibromo-succinic acid; pyrene-2,3, 7, 3- tetra-carbcxyl c acid; tartaric acid; organic sulphonic acids ,such as' -ccI ene suLphonic acid; and benzene sulphonic acid; 2,4-dinitro-i- ....-ichyl-benzene^-sulphonic acid; 2, 6-dinitro-l-hydroxy~benzene-4~ sulphonic acid and mixtures thereof.

In addi on other photoconductors may be fo ^.so -complexing one or more suitable Lewis acids with pol stire nich polymers which may be conrplexed in this manner include the following illustrative materials: polyethylene terephthalate, polyamides, polyimides, polycarbonates, polyacrylates, polymethylmethacrylates , polyvinyl fluorides, polyvinyl chlorides, polyvinyl acetates, polystyrene, styrene-butadiene copolymers, β polymethacrylates, silicone resins, chlorinated rubber, and 7 mixtures and copolymers thereof where applicable; thermosetting β resins such as epoxy resins, phenoxy resins, phenolics, epoxy-0 phenolic copolymers, epoxy ureaformaldehyde copolymers, epoxy 0 melamine-formaldehyde copolymers and mixtures thereof, where 1 applicable. Other typical resins are epoxy esters, vinyl 2 epoxy resins, tall-oil modified epoxies, and mixtures thereof 8 where applicable.

It is also to be understood in connection with the heterogeneous system, that the photoconductive particles themselves may consist of any, suitable one or more of the aforementioned photoconductors , either organic or -inorganic, dispersed in, in solid solution in, or copolymerized with, any suitable insulating resin whether or not the resin itself is photoconductive. This particula r type of particle may be particularly desirable to facilitate dispersion of the particle, to prevent undesirable reactions between the binder 14 and the photoconductor or between the photoconductor and the activator and for similar purposes. Typical resins of this type include polyethylene, polypropylene, polyamides, polymethacrylates, polyacrylates, polyvinyl chlorides, polyvinyl acetates, polystyrene, polysiloxanes, chlorinated rubbers, polyacrylonitrile, epoxies, phenolics, hydrocarbon resins and other natural resins such as rosin derivatives as well as mixtures and r t reof in the heterogeneous system may range from about 10 to 1 to about 1 to 10, but it has generally been found that proportions in the range of from about 1 to 2 to about 2 to 1 produce the best results and, accordingly, this constitutes a preferred range.

As stated above, imaging layer 12 has relatively low cohesive strength either in the as-coated condition or after it has been suitably activated. This, of course, is true for both the homogeneous systeraand the heterogeneous system. One technique for achieving low cohesive strength in the layer 12 is to employ relatively weak, low molecular weight materials therein. Thus, for example, in a single component, homogeneous layer 12, a raonomeric compound or a low molecular weight polymer complexed with a Lewis acid to impart a high level of photo-response to the layer may be employed. Similarly, when a homogeneous layer utilizing two or more components in solid solution is selected to make up layer 12, either one or both of the components of the solid solution may be a low molecular weight material so that the layer has the desired low level of cohesive strength. This approach may also be taken in connection with the heterogeneous layer 12 illustrated in Fig. 1. Although the binder material 14 in the heterogeneous system may in itself be photoresponsive, it does not necessarily have this property so that materials such as microcrys alllne wax, paraffin wax, low molecular weight polyethylene and other low molecular weight polymers may be selected for use as this binder material solely on the basis of physical properties and the fact that they are insulating materials without regard to their photoresponse. This is also true of the two-component homogeneous system where non-photoresponsive solid solution with photoresponsive material. Any other techniqu for achieving low cohesive strength in imaging layer 12 may also be employed. For example, suitable blends. of incompatible materials such as a blend of a polysiloxane resin with a polyacrylic ester resin may be used either as binder layer 14 in a heterogeneous system or in conjunction with a "homogeneous" system in which the photoresponsive material may be either one of the incompatible components (complexed with a Lewis acid) or a separate and additional component of the layer. The thickness of imaging layer 12 is not critical and layers from about 0.5 to about 10 microns have been used.

Above imaging layer 12 is a third or receiving layer 16. This receiver sheet is ordinarily supplied as a separate layer which does not initially adhere to layer 12. Accordingly, although the whole imaging member or "manifold set" may be supplied in a convenient three-layer sandwich as shown in Fig. 1, receiving layer 16 may also be supplied as a separate sheet or roll if desired. On the other hand, in those systems where activation of the imaging layer is not required or where imaging layer 12 has been preactivated at the factory, layer 16 adheres to or is at least tacked onto imaging layer 12. In the particular embodiment of the manifold set, shown in Fig. 1, both the donor substrate 11 and the receiver sheet 16 are made up of an electrically conductive material such as cellophane with at least one of them being optically transparent to provide for the exposure of layer 12. There should be a fairly close balance between the adherence of imaging layer 12 for the donor and receiver layers 11 and 16, respectively, with a slightly stronger adherence to the donor at the time of imaging. Accordingly, layers 11 and 16 should be selected with this in same material for layer 16 as is used for layer 11.

Although the structure of Fig. 1 represents one of 3 the simplest forms which the manifold set may take, another 4 embodiment is illustrated in Fig. 2 where imaging layer 12 6 may take any one of the forms as described above in connection β with Fig. 1. In the Fig. 2 embodiment imaging layer 12 is 7 deposited on an insulating donor substrate 17 which is backed -8 with a conductive electrode layer 18 while the image receiving 9 portion of the manifold set also consists of an insulating 0 receiver sheet 19 backed with a conductive electrode layer 21. 1 Here again, either or both of the pairs of layers 17-18 and 2 layers 19-21 may be transparent so as to permit exposure of 8 imaging layer 12. Flexible, transparent conductive materials, 4 such as cellophane which may be used in the Fig. 1 embodiment 6 of the invention, are for the most part relatively weak β materials with the choice of these materials being quite limited. 7 The Fig. 2 structure which uses an insulating donor substrate 8 and receiver sheet 17 and 19, respectively, allows for the use 9 of high strength insulating polymers such as polyethylene, 0 polypropylene, polyethylene terephthalate, cellulose acetate, 1 Saran (vinyl chloride-vinylidene chloride copolymer) and the 2 like. Not only does the use of this type of high strength 3 polymer provide a strong substrate for the positive and negative 4 images formed on the donor substrate and receiver sheet, but, 6 in addition, it provides an electrical barrier between the 6 electrodes and the imaging layer 12 which tends to inhibit 7 electrical breakdown of the system. Combinations of the 8 structure described in Figs. 1 and 2 may also be used in carrying 9 out the invention with a relatively conductive layer immediately Referring now to the flow diagram of Fig. 3, it is seen that the first step in the imaging process is the activation step. In this stage of the imaging process, the manifold set is opened and the activator is applied to imaging layer 12 following which these layers are closed back together again, as indicated in the second block of the process flow diagram of Fig. 3. Although the activator may be applied by any suitable technique, such as with a brush, with a smooth or rough surfaced roller, by flow coating, by vapor condensation or the like, Fig. 3a which diagrammatically illustrates the firs two process steps shows the activator fluid 23 being sprayed on to imaging layer 12 of the manifold set from a container 24.

Following the deposition of this activator fluid, the set is closed by a roller 26 which also serves to squeegee out any excess activator fluid which may have been deposited. The activator serves to create an adhesive bond between imaging layer 12 and receiver sheet 16 as well- as to swell ,or otherwise weaken and thereby lower the cohesive strength of imaging layer 12. The activator should also have a high level of resistivity sc that it will not provide any electrically conductive paths through imaging layer 12 and in addition, so that the imaging layer will support the electrical field which is applied through it during the exposure. Accordingly, it will generally be found to be desirable to purify commercial grades of activators so as to remove impurities which might impart a higher level of conductivity to the activating fluids. This may be accomplished by running the fluids through a clay column or by any other suitable purification technique. Generally speaking, the activator may consist of any suitable solvent having the aforementioned properties and which has the above-described spirits and white mineral oil, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone an vegetable oils such as coconut oil, babussu oil, palm oil, olive oil, castor oil, peanut oil and neatsfoot oil and mixtures thereof.

In certain instances, the first two steps of the imaging process as diagrammatically illustrated in Fig. 3a, ma 8 be omitted. Thus, for example, a manifold set which is pre-8 activated at the factory may be supplied or if imaging layer 12 0 is initially fabricated to have a low enough cohesive strength, 1 activation may be omitted and receiving layer 16 may be adhered 2 to the surface of imaging layer 12 at the time when that layer 8 is coated on substrate 11 either from solution or from a hot 4 melt. It is generally preferable, however, to include an 6 activation step in the imaging process because if this step is β included, then a stronger and more permanent imaging layer 12 7 may be provided which can withstand storage and tramsporation 8 prior to imaging and which will provide a more permanent final 9 image after imaging. 0 Once the proper physical properties have been imparted 1 to imaging layer 12 and the receiving sheet 16 has been adhered 2 to its upper surface, an electrical field is applied across the 8 manifold set and it is exposed to the image to be reproduced. 4 Upon separation of substrate 11 and receiving sheet 16, imaging 6 layer 12 fractures along the edges of exposed areas and at the 6 surface where it is adhered to either substrate 11 or receiving 7 sheet 16. Accordingly, once separation is complete, exposed 8 portions of imaging layer 12 are retained on one of layers 11 » and 16 while unexposed portions are retained on the other layer, 0 resultin in the simultaneous formation of a hi h amma ositive 1 other. Whether exposed portions are retained on donor substrate 2 11 or transferred to receiver sheets 16 will, of course, depend 3 on the particular photoresponsive material employed in the 4 imaging member as well as the polarity of the applied field.

By making the initial degree of adherence of layer 12 only β slightly higher for layer 11 than for layer 16, imaging layer 7 12 is finally retained on layer 11 unless the combined effect 8 of exposure and applied field are added to the bond strength 9 of layers 12 and 16, thereby exceeding the strength of the bond 0 between layers 11 and 12. In this way, an amplification effect 1 is achieved and transfer may be caused with relatively low 2 levels of light exposure. The application of the required 8 electrical field is relatively straightforward; however, with 4 some materials, there is a preferred polarity orientation. 6 Thus, for example, with an imaging layer made up of finely β divided metal- free phthalocyanine particles dispersed in 7 a microcrystalline wax, the best images are formed when the 8 donor is positioned at the illuminated electrode which is made 9 negative and the non- illuminated electrode is positive. The 0 reversal of this polarity generally results in a poorer image 1 or lower sensitivity' and sometimes in a reversal of position 2 in that a duplicate of the exposed original is formed on the 3 non- illuminated side of the manifold set instead of at the 4 illuminated side which is the usual case. Accordingly, potential 6 source 28, shown in Fig. 3b, is indicated as having its negative side connected to substrate 18 through which exposure is made by light rays 29. Preferred field strengths are in the range 8 of about 1,500 to 2,000 volts per mil. across the manifold set. Thus, using 2 mil. Mylar sheets for both donor substrate and receiver sheet the referred applied voltage is 6,000 to 8,000 4,000 co about 10,000 volts. In general, the receiver sheet is rolled down onto the activated imaging layer 12 with the.power on. However, to prevent air gap breakdown at the nip which will result in the production of Lichtenberg patterns, a fairly large resistance is preferably inserted in series with the power β supply to limit the flow of current and the rate of charging 7 of the capacitor which the manifold set forms. A fairly large 8 resistor on the order of from about at least 5,000 to 20,000 8 megohms satisfactorily performs this function although the largest value resistors lower the gamma somewhat. This resistance 11 may be omitted if sheet closure occurs before the field is 12 applied. However, even then the resistor is preferably retained 18 in the circuit to provide protection for the operator and limit , 14 the energy in a spark when occasional breakdown occurs in flaws 16 or pinholes in the Mylar. Another important function of this 1β resistor, which is shown as resistor* 30 in Fig. 3b, is that it ιτ; provides a path for discharging the capacitor at an adequate 18 rate to prevent sparking during separation of the donor and the receiver sheet.

A visible light source, an ultraviolet light source 21 or any other suitable source of actinic electromagnetic radiation 22 may be used to expose the manifold set of this invention*. Better 28 quality Images are produced by exposing from the donor side 4 of the imaging layer and, accordingly, the receiver sheet 16 26 is usually separated from the other layers of the manifold set 26 just after image exposure and generally with the power on both 7 electrodes. This operation involves a current flow because 8 as the layers are separated the capacitance of the manifold set 8 is reduced and charge stored in this capacitor is caused to flow Che exposure step- seem Co have no deleterious effects on the images produced. Essentially- the same result is produced if separation occurs af er the power is turned off because the charge stored in the capacitor which is formed by the manifold set still applies a field across the imaging layer but generally poorer images result. It is to be noted that even when the power supply is turned off, it still acts as part of a closed circuit connecting the resistor to the two electrodes of the manifold set because of the L-C filter network in the output of this type power supply. It is believed that a charge differential is built up between exposed and unexposed areas of layer 12 during the process so that when layers 11 and 16 are separated, the applied field causes image-wise portions of layer 12 to go with receiver 16 while the complementary or background areas are retained on layer 11 to which layer 12 adheres more strongly.

If a relatively volatile activator is employed, such as petroleum ether or carbon tetrachloride or Freon 215, fixing occurs almost instantaneously after separation of the layer because the relatively small quantity of activator in the 2-5 micron layer of imaging material flashes off very rapidly.

With somewhat less volatile activators, such as the Sohio odorless solvent 3440 or Freon 214, described above, fixing may be * accelerated by blowing air over the images or warming them to about 150°F. , whereas with the even less volatile activators, such as transformer oil, fixing is accomplished by absorption of the activator into another layer such as a paper substrate to which the image is transferred. Many other fixing techniques and methods for protecting the Lmages such as overcoating, laminatin with a trans arent thermo lastic sheet and the like and hardness may also be achieved by treatment with an Image material hardening agent or with a hard polymer solution which will wet the image material but not the donor substrate.

In general, the apparatus for carrying out the -imaging procedure described above will employ the elements β illustrated in Figs. 3a and 3b including a source of activator 7 fluid, a squeegee roller to remove excess activator fluid, 8 a power supply with series resistor and a set of electrodes 0 which may or may not be built in to the manifold set. Opening 0 the manifold set for activation, closing the set for exposure 1 and opening again for separation and image formation may be 2 accomplished by any one of a number of techniques which will 3 be obvious to those skilled in the art. However, one straight4 forward way to accomplish this result is to supply the imaging 6 materials in the form of long webs which can be entrained over β rollers so as to provide opening and closing of the set during 7 the 'imaging process. . · 8 It is to be noted that as pointed out supra manifold 9 sets may be supplied in any color desired either by taking 0 advantage of the natural color of the photoresponsive or binder 1 materials in the imaging layer of the manifold set or by the 2 use of additional dyes and pigments therein whether photo3 responsive or not, and, of course, various combinations of 4 these photoresponsive and non-photoresponsive colorants may be 6 used in the imaging layer so as to produce the desired color. 6 Although manifold images are in the form of transparencies when first produced, these images may be laminated with opaque backing material of various contrasting colors to produce prints. In addition, manifold images using different colored ima in la ers such as cyan, magenta and yellow may be combined transparencies. It Is also to be noted that different photoresponslve materials have different spectral responses and that the spectral response of many pho oresponslve materials may be modified by d^esensitization so as to either Increase and narrow the spectral response of a material to a peak or to broaden It to make It more panchromatic In Its response. Thus, the material can be used to make ordinary "black and white" Images using panchromatic response while narrow spectral response materials may be employed for the production of color separations or the like.

The invention having been generally described above, the following specific examples of preferred embodiments of the invention are given in the following examples. All parts in the examples are taken by weight unless otherwise indicated.

EXAMPLES I - IV A commercial, metal-free phthalocyanine is first purified by acetone extraction to remove organic impurities.

Since this extraction step yields the less sensitive beta crystalline form, the desired alpha form is obtained by dissolving 100 grams of beta in 600 cc. of sulfuric acid, precipitating it by pouring the solutio into 3,000 cc. of ice' water and washing with water to neutrality. The thus purified alpha phthalocyanine is then salt milled for 6 days and desalted by slurrying in distilled water, vacuum filtering, water washing and finally methanol washing until the initial filtrate is clear. After vacuum drying to remove residual methanol, the X-form ph halocyanine thus produced is used to prepare the imaging layer according to the following procedure: 5 gratrs of Sunoco 1290, a microcrystalline wax with a melting point of ° purified and milled phthalocyanlne produced according to the above procedure are then added to the wax paste along with 1/2 pint of clean porcelain balls in a 1 pint mill jar. This formulation is then ball milled in darkness for 3 1/2 hours at 70 r.p.m. and after milling 20 cc. of Sohio solvent 3440 is added to the paste. This paste is then coated in subdued green light on a 2 mil. Mylar sheet with a No. 12 wire-wound draw down rod which produces a 2.5 micron thick coating after drying. The same paste is also applied on three other Mylar sheets with a No. 8 draw down rod to produce a coating thickness of 1 1/2 microns, with a No. 24 rod to produce a coating thickness of microns and a No. 36 rod to produce a coating thickness of 7 1/2 microns. Each of these coatings is then heated to about ' 140°F. in darkness in order to dry it. Then the coated donors are placed on the tin oxide surface.of NESA glass plates with their coatings facing away from the tin oxide. A receiver sheet also of 2 mil. thick Mylar is then placed on the coated surface of each donor. Then, a sheet of black, electrically conductive paper is placed over the receiver sheet to form the complete manifold set. The receiver sheet is then lifted up and the phthalocyanlne wax layer is activated with one quick brush stroke of a wide camel's hair brush saturated with petroleum ether.

The receiver sheet is then lowered back down and a roller is rolled! slowly once over the closed manifold set with light pressure to remove excess petroleum ether. The negative terminal of an 8,000 volt d.c. power supply is then connected to the NESA coating in series with a 5,500 megohm resistor and the positive terminal is connected to the black opaque electrode and grounded. With the ' voltage applied, a white incandescent light image is projected applied for 5 seconds for a total incident energy of 0.05 foot- candle-second. After exposure, the receiver sheet is peeled from the set with the potential source still connected. The small amount of petroleum ether present evaporates within a second or so after separation of the sheets yielding a pair of excellent quality images with a duplicate of the original on the donor sheet and a reversal of the original on the receiver sheet. All four coating thicknesses produce good quality images; however it is apparent that there is a slight increase in sensitivity and gamma with increasing thickness of the phthalocyanine wax coating.

EXAMPLES V - VIII Five donor substrates are coated according to the procedure of Example I except that the ratio of phthalocyanine pigment to wax is 5 to 1 in Example V, 1 to 4 in Example VI, 1 to 5 in Example VII and 1 to 10 in Example VIII. When these donors are imaged according to the procedure of Exam le I, all produce dense high resolution images with the exception of Example VIII which produces a coating of lower reflection density and noticeably lower resolution.

EXAMPLES IX - XIII The procedure of Example Γ is repeated except, that the phthalocyanine pigment is mixed at a ratio of 1 to 1 for each of 'the following binders: for Example IX Sunoco microcrystalline wax grade 5825 having an ASTM-D-127 melting point of I51°F. is used; for Example X, grade 985, another Sunoco microcrystalline wax having a melting point of 193°F. is used; for Example XI, Sunoco paraffin wax grade 5512 having a melting point of 153°F. (ASTM-D-87) is used; for Example XII a low molecular weight 1 weight of 3,700, a ring and ball softening point of 92"C. , an 2 ¾cid No. of 0.05 and a density at 25°C. of 0.893 is used; for 8 Sxaraple XIII grade N-ll of the Epolene low. molecular weight 4 >olyethylene series is employed having an approximate molecular weight of 1,500, a ring and ball softening point of 170°C. , a β Jensity at 25°C. of .924 and an acid number of 0.05. Each of 7 these coatings is imaged according to the procedure of Example I 8 md all are found to produce good quality images although Sunoco 9 >825 microcrystalline wax of Example IX and 5512 paraffin wax of 10 Sxample XI produce some blue haze in the background of the image 11 ?hich remains on the donor apparently because of the fact that 12 :hese waxes are softer than the other materials tested. 18 EXAMPLES XIV - XVIII 14 Five donors are prepared according to the procedure 16 >f Example I and imaged according to the procedure given in that 16 -xample with the exception that the following activators are used 17 .n each of the Examples. In Example XIV, .it is activated with 18 !ohio odorless- solvent 3440, Example XV is activated with carbon id :etrachloride, Example XVI is activated with Freon 214 (tetra- 20 :hlorotetrafluoropropane) , Example XVII is activated with 21 )ow-Corning silicone oil DC200 (dimethylpolysiloxane) , and 2 Ixample XVIII is activated with Wemco-C transformer oilt a very 23 ligh boiling point long chain aliphatic oil available from 4 testinghouse Electric. In each of these Examples, the activators 6 roduce a high quality image upon separation. In the case of 6 Ixamples XIV - XVI, the final images require mild heating at 7 tost to dry off the activator and harden the image, while in the 8 ase of Example XVII and XVIII, the non-drying activator maintains 0 he image in a wet condition. These two images are then rolled 0 ff on an absorbent a er substrate which picks up mos of the EXAMPLES XIX - XXIV In Examples XIX - XXIV, six donors are made according to the procedure of Example I and the imaging procedure of Example I is followed with the only exception that the pigment used in forming the imaging layer is as follows. In Example XIX, the stabilized alpha crystalline form of metal-free phthalocyanine is employed. This material is prepared by acetone extraction of the commercial metal- free phthalocyanine and sulfuric acid solution reprecipitation of the extracted material as in Example I followed by neat milling for one day of the precipitated material in a porcelain mill with Burundum balls. This milling stabilizes the alpha form from conversion to the beta form. In Example XX, the beta form of metal- free phthalocyanine is used. This is produced by the same acetone extraction; and procipitation f¾?om oulfuric acid solution with tio milling. In Example XXI, Algol yellow GC Color Index No. 67,300 (1, 2,5,6-di(C,C'-diphenyl)-thiazole-anthraquinone is used. In Example XXII, the pigment used is 2, 9-dimethylquinacridone. In Example XXIII, French process zinc oxide is used as the pigment. In Example XXIV, mercuric sulfide is used as the pigment. While all of these materials produce images, it is found that the stabilized alpha phthalocyanine of Example XIX has about one order lower sensitivity as the X-erystal form of Example I while the beta ph halocyanine is about two orders of magnitude slower than this speed. Contrasting the remaining pigments, it is found that 750 foot-candles seconds exposure is required in Example XXI, 1.0,500 foot-candles seconds is required in Example XXII, 5,000 ffoot-candles seconds is required in Example XXIII and 10,000 foot-candles seconds in Example XXIV.

EXAMPLES XXV - XXVIII and Imaged according to the procedure of Example I with the exception that various electrodes, donor substrates and receivers are employed as follows: Receiver Upper Example No. Base Electrode Donor Substrate Sheet Electrode XXV Cellophane Electrode Electrode Cellophane XXVI Cellophane Mylar Electrode Cellophane XXVII NESA glass Cellulose Cellulose Conductive Acetate Acetate Black Paper XXVIII NESA glass Mylar Electrode Aluminum Each of these structures produce results which are about equivalent to those of the Example I procedure.

EXAMPLE XXIX Eight parts by weight of 2,5-bis (p-aminophenyl) 1,3,4- oxadiazole and 12 parts by weight of Lucite 2008, a low molecular weight polymethylmethacrylate available from E. I. DuPont & Co. are dissolved in 80 parts by weight of methylethyl ketone along with 0.25 parts by weight of bromphenol blue dye. This solution is then coated on a 2 mil. Mylar substrate and before the coating is fully dried, it is dipped in a water bath which dilutes the solution causing the solids to precipitate out in a weak semi-particulate form in which the individual particles are bonded at their interfaces much' like a sintered layer. The donor thus prepared is imaged according to the procedure of Example I with a Mylar receiver sheet beneath an electrically conductive black paper electrode and using a transparent NESA glass electrode beneath the Mylar layer of the donor. Although the dye increases the sensitivity of the layer somewhat and imparts a pink tinge to it, both the sensitivity of the system and the resolution of the image produced are lower than that of the system of Example I.

EXAMPLE XXX Twenty parts by weight of polyvinylcarbazole is weight of a 2,4,7- trinitro-9-fluorenone charge transfer complexing 2 agent and 0.05 parts by weight of a bromphenol blue sensitizing 8 dye. After partial drying of the coating, it is dipped in acetone 4 which causes precipitation of the solids from solution in the 6 same type of physical structure as described above in connection β with Example XXIX. This donor is imaged according to the same 7 procedure as used in connection with Example XXIX and is somewhat 8 more sensitive than the coating of Example XXIX. 9 The new system herein described for the formation of 0 high gamma images by layer transfer in image configuration 1 can be used in color proofing and in the production of color 2 separations. 8 A problem has confronted the prior art in forming 1 4 color separations and proofing the separations prior to 6 making plates for three-color printing. Since color printing is carried out from at least three different plates, each β of which is used to print one of the three primary colors, 7 the original colored image must first be separated into its 8 primary color components so that the three plates can be 9 made from these separations. 0 1 Somewhere in the process screening is also required 2 since each plate must finally be halftone in order to operate in the printing process. This screening may take place when 3 the Reparations are first made and is then known as "direct 4 screening" or the separations may be screened later for 6 proofing and plate making. Since the manufacture of long run 6 color printing plates and their set up in the press is a very 7 expensive and time consuming affair, it is highly desirable 8 to check or "proof" the image which will be made by the screene< 9 separations before the plates are made and set up in the press. 0 The making of these separations and proofing has been expensive first instance by exposing the original image to three successive conventional gelatin-silver halide films through three different filters and then processing these films through the conventional silver halide developing and fixing processes. In order to proof these separations they are used to produce a color positive Which will reproduce as closely as possible the three-color image which will be printed when the screened separations are used to make the three plates. This proofing process can be accomplished in several ways, for example, by the use of material sold under the name of "Color Key" by the Minnesota Mining and Manufacturing Co. or by the use of especially made diazo proofing materials. In each case such a proofing procedure involves a separate set of operations, none of which are germane to the main task except as a check on the accuracy of the work.

The present invention provides an improved system for color proofing using imaging layers of the invention each of a color such that it absorbs light principally in bne region of the visible spectrum not more than about 100 millimicrons wide. This system is capable of producing color separations and proofs in one simultaneous exposure.

In order to proof at the time of screening, the three (or four) separations are screened on different colored manifold sets so that the blue separation is screened on the yellow set, t e green separation on a magenta set, the red separation on a cyan set and the black separation on a black set (if a black separation is used) . In this case the manifold sets need not necessarily have peaked spectral responses so long as they show response to the color of light of the particular separation to which they are exposed. In this way, no matter what type of plate making is used either the negative or the positive sheets separations (as described by F.R. Clapper "Improved Color Separation of Transparencies by Direct Screening" J. Phot.

Sci. 12, 28 Jan.-Feb. 1964) may also be used in which case the screened separations are merely exposed to the correct manifold set for proofing.

In addition, by providing manifold sets with selective spectral response so that the yellow set responds only to blue light, the magenta set responds only to green light and the cyan set responds only to red light or by using suitable filters with sets which have broader spectral responses these sets may be employed directly to produce the screened separations. This is particularly advantageous in "direct screening" . The complementary images produced in each of the sets are then superposed for proofing .so that color separation, screening and proofing is combined into one quick virtually dry process.

EXAMPLE XXXI ' Three manifold sets made with yellow, cyan and magenta pigments, as described in Examples XXI, XIX and XXII, respectively, are made up and imaged according to the procedure of those examples. The yellow, cyan and magenta manifold sets are exposed through a screen to the blue, red and green color separations formed from a colored original. Upon separation of the 'manifold sets the positive images are superimposed with the yellow on the bottom followed by the magenta and cyan positives so that a screened proof is provided. At the same time the three screened negatives formed on separation of the manifolds are ready for use in making the plates providing the proof is satisfactory. It is accordingly seen that the proofs are made simultaneously with the formation of the

Claims (1)

A method of comprising steps ofs providing a cohesively electrically sensitive imaging layer sandwiched a first layer and a second applying an electric field across said imaging exposing said imaging layer to a pattern of actinic electromagnetic separating under electric field first layer from said second layer whereby imaging layer fractures iraagewlse configuration with a positive adhering to one of said first and second layers and a negative image adhering to the other of said first and second method of Claim wherein imaging layer coated on one of said first layer and said second method of Claim 1 or wherein said first and said second layers are conductive and said electric field applied between and second e method of Claim 1 or wherein said first layer is insulating and further Including the step of providing an electrode on the side of said first layer opposite ging layer and applying electric field between said electrode and sad second method of Claim 1 or wherein said first layer and said second layer are insulating and further including the step of providing electrodes on sides of said first and second layers opposite said imaging layer and applying said electric field between said The method any Claims 1 at least one of said first layer layer at least partially The method of any of Claims 1 to wherein said first layer is at least partially transparent and said imaging layer is exposed through said first The method of any of Claims 1 to wherein said imaging layer comprises a homogeneous The method of any of Claims 1 to wherein said imaging layer comprises a solid solution of electrically phot sensitive material in a The method of any of Claims 1 to wherein said layer comprises a solid solution of electrically sensitive material in an The method of any of Claims 1 to wherein said imaging layer comprises a solid solution of electrically sensitive material in a The method of any of Claims 1 to wherein said layer comprises a heterogeneous The method of any of Claims 1 to wherein said imaging layer comprises electrically photosensitive particles dispersed in an insulating The method of any of Claims 1 to wherein layer comprises electrically photosensitive particles dispersed in an electrically photosensitive The method of any of Claims 1 to wherein said imaging layer comprises an electrically photosensitive material made up of an organic compound completed with a Lewis 33 The method of any of Claims 1 to wherein said imaging layer comprises a of materials which together form a cohesively weak method of any of Claims 1 to wherein said imaging layer of a precipitated form as hereinhe The method of any of Claims 1 to wherein said imaging layer oomprises phthalocyanine in a The method of any of Claims 1 to said imaging layer comprieee phthalocyanine in the talline form in a The method of any of Claims 1 to wherein said imagine layer comprises in the alpha crystalline form in a The method of any of Claims 1 to wherein said imaging layer comprises in a The method of any of Claims 1 to wherein imaging layer comprises in a The method of any Claims 1 to wherein said imaging layer comprises zinc oxide a The method of any of Claims 1 to wherein said imaging layer eomprieee an electrically photoeeneitive material in a wax The method of any of Claims 1 to wherein said imaging layer comprises electrically photosensitive material in a wax The of any of Claims 1 to wherein said layer eleotrically photosensitive material in a polymeric method of any of 1 to wherein said field has field of about volts per mil to about volts across said first laye said second layer and said She method of any of Claims 1 to and further including the step of overcoating at least one of said positive and negative The method of any Claims 1 to wherein said imaging layer is from microns to microns method of any of Claims 1 to therein said imaging layer is rendered cohesively weak by applying an activator to said The method of Claim wherein said activator is volatile and farther the step heating at least one said positive and said negative after separating said first layer from said second layer to evaporate the The method of wherein said activator is substantially and further including the step of contacting at one of said positive and negative with an absorbent material afte separating said first layer from said second A method proofing colour separations comprising imaging green and red separations from a colour original respectively on magenta and cyan manifold sets by a method according to any of Claims 1 to and superimposing the positive 35 formed said manifold sets to A method as Claim 33 further including imaging a separation from said original on a black manifold set by a method to any of Claims 1 to 32 and superimposing it on the other three positive images to synthesize said A method for simultaneously proofing and ing colour separations made from a polychromatic original comprisin imaging green and red separations made said original through a screen on magenta and cyan manifold sets by a method according to any of Claims 1 to retaining the screened negative produced from said manifold sets for plate preparation and superimposing the ive images formed from said manifold sets to subtractively synthesize an A method as in Claim 35 further including imaging a blaek from said original on a black manifold set through a screen by a method to any of Claims 1 to retaining the screened blaek negative for the formation of a blaek printing plate and superimposing the screened positive manifold image on the other three method for the simultaneous formation of colour separation screening and proofing comprising successively imaging a coloured original on at least magenta and cyan manifold by a method according to any of Claims 1 to wherein each of manifold sets is electrically photosensitive in essentially only that portion of the visible spectrum which is absorbed by that particular set with each of said images being made by exposure through a and the positive images formed from said manifold to ractively synthesize an An imaging member comprising a first a second layer and an electrically photosensitive cohesively weak layer sandwiched between said first and second at least one of said first and second layers being at partially transparent to actinic electromagnetic An imaging member according to Claim wherein said imaging layer is coated on one of said first and said second An imaging member according to Claim or wherein at least one of said first and second layers is An imaging member according to Claim 33 or 3 wherein both of said first and second la ra are An imaging member according to Claim 38 or wherein said first and second layers are insulating and further including an electrode on each of said first and second layers and wherein at least one of said electrodes is at least partially transparent to actinic electromagnetic An imaging member according to Claim wherein said imaging layer comprises a homogeneous An imaging member according to Claim w erein said imaging layer comprises a soUd solution of electrically photosensitive material in an insulating An imaging member according to Claim wherein said imaging layer comprises a solid solution of electrically photosensitive material in a photoconduotive An to Claim wherein said imaging layer comprises a heterogeneous An imaging according to Claim eaid imaging layer comprises electrically photosensitive particles dispersed in an insulating An imaging member according to Claim wherein imaging layer comprises electrically photoaeneitive particles dispersed in an electrically photosensitive An imaging member according to said imaging layer composes an electrically photosensitive material made up of an organic completed a lewis An imaging member according to Claim 38 wherein said imaging layer comprises a blend incompatible materials which together form a cohesivel weak An imaging member according to Claim wherein said imaging layer is of a precipitated weak as hereinbefore An imaging member according to Claim wherein eaid imaging layer comprises phthalocyanine in a An imaging member according to Claim wherein said imaging layer comprises phthalocyanine the crystalline form in a An imaging member according to therein said layer comprises phthalocyanine in alpha crystalline in a An imaging member according to Claim said imaging layer comprises in a An imaging according Glaim wherein said imaging layer in a An imaging member according to Claim wherein said imaging layer comprises oxide in a An imaging member according to wherein said layer an electrically photosensitive material in a wax An imaging member according to Claim said layer comprises electrically photosensitive material in a microcrystalline wax An imaging member according to Claim said imaging layer comprises electrically photosensitive material in a low molecular weight Imaging apparatus for carrying out the method of

1. Claim 1 comprising a substantially transparent first eleetrode adapted to support one side of the imaging means to apply an activator to said imaging means to squeeze out excess a electrode adapted contact the side of said imaging layer opposite said first to apply an electric field across said imaging layer between said means to expose said imaging layer to an image with actinic electromagnetic radiation said and means to separate said first eleetrode from said second electrode whereby an image is An apparatus according to Claim wherein layer is poaitioned between a first insulating layer and a second insulating layer respectively located between said layer and said first and second electrodes and including to separate said first layer and said second layer and said first and second electrodes whereby an image is method of 1 substantially as herein insufficientOCRQuality