US 3839028 A
An imaging process which comprises selectively eliminating or adding imagewise at least a component of a system consisting of a hydrophilic macromolecular substance, a metal ion, a compound capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water or a substance which provides such a compound when decomposed and a compound represented by the following general formula:
Description (OCR text may contain errors)
United States Patent [1 1 Tamai et al.
1 IMAGING PROCESS  Assignee: Fuji Photo Film Co., Ltd.,
Kanagawa, Japan  Filed: Dec. 30, 1971 [211 App]. No.: 214,141
 Foreign Application Priority Data Dec. 30, 1970 Japan 45-123038  US. Cl....96/1 R, 96/35.], 101/463, 117/17.5, 117/37 R, 204/18 PC, 250/317, 346/1  Int. Cl. G03g 13/22, G03c 5/08  Field of Search 204/2, 18 PC; 96/27, 35, 96/351, 1, 1.5; 101/450, 463; 117/201, 8,
 References Cited UNITED STATES PATENTS 3,332,857 7/1967 Lieblich 204/2 3,632,484 l/l972 Richards 204/2 Primary Examiner-Charles E. Van Horn Assistant Examiner-M. B. Wittenberg Attorney, Agent, or Firm-J. T. Martin; Gerald J. Ferguson, Jr.; Joseph .1. Baker [5 7] ABSTRACT An imaging process which comprises selectively elimi nating or adding imagewise at least a component of a system consisting of a hydrophilic macromolecular substance, a metal ion, a compound capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water or a substance which provides such a compound when decomposed and a compound represented by the follow ing general formula:
wherein Z,Z non-metallic atoms constituting heterocyclic structure, X anion, and Y atom belonging to the group 68 of the periodic table, from or to the system thereby obtaining an image containing water-insoluble macromolecular substance.
24 Claims, 14 Drawing Figures 1 IMAGING PROCESS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an imaging process, and particularly to an imaging process utilizing the reaction of compounds capable of effecting a specific reaction with macromolecular substances.
2. Description of the Prior Art The formation of images consisting of macromolecular substances by tanning development of the matrix film with gelatin and silver halide is known. A process utilizing a silver halide and an addition polymerizable substance is already disclosed for example in U.S. Pat. No. 3,194,661. Also U.S. Pat. No. 2,927,002 disclosed a process not utilizing silver halide, in which addition polymerizable substance and photoactivatable addition polymerization initiator are combinedly used with cellulose derivative. Besides various photosensitive resins are already disclosed in number of patents and made commercially available, such as Dycril from DuPont, Nyloprint from Badisch Anilin und Soda Fabrieken, A.P.R. from Asahi Chemical, T.P.R. from Tokyo Oka Industries, K.P.R. from Eastman Kodak, etc. The earliest composition known in this field is the combination of polyvinyl-alcohol with bichromate. The abovementioned processes or the materials for obtaining macromolecular image have been associated with drawbacks such as delicate handling, insufficient shelf life, low sensitivity, etc.
Furthermore, the process of obtaining macromolecular image on the surface of electrolytic photosensitive layer is already disclosed in US. Pat. No. 3,106,516 according to the process, a hardener or softener pattern obtained by an electrolytic photographic method is pressed against a sheet having a macromolecular substrate for an after-treatment to obtain a macromolecular image. The process, however, involves a transfer step, so that the obtained image lacks in sharpness. Also U.S. Pat. No. 3,172,827 discloses a process in which polyamide resin contained in the electrolytic bath is insolubilized imagewise on the photosensitive layer by means of pH increase at the cathode during electrolysis.
It has been found, however, that by the process it is difficult to obtain an image having sufficient mechanical strength and solvent proof property.
Furthermore, the processes for forming polymer image by the passage of electric current are already disclosed for example in U.S. Pat. No. 3,409,431, U.S. Pat. No. 3,436,215, British Pat. No. 1,178,552 and British Pat. No. 1,136,209. These processes employ polymerizable monomer and therefore pose frequent difficulty in shelf life.
Furthermore, a process of controlling the enzymatic activity by the passage of electric current is disclosed in Japanese Pat. No. 549,870, but this process requires considerable caution to obtain stable gelatin image.
Also the use of polymer as toner in electrophotographic process is already known. Finely powdered polymer obtained by crushing polymer material for example by jet mill is mixed with carrier particles to obtain electrophotographic cascade developer. Also electrophotographic liquid developer can be prepared by dispersing powdered polymer in an insulative liquid incapable of dissolving said polymer. Thus polymer image can be obtained by developing electrostatic latent image with such developers. In general liquid developer gives better image quality than with dry developer. It has been considerably difficult, however, to obtain stable dispersion when the polymer is hydrophilie. For example, the processes disclosed in German Pat. OLS Nos. 2,004,817 and 2,005,180 show the drawback of requiring complicated procedure to prepare the developer. On the other hand dry developer containing toner consisting of finely powdered hydrophilic polymer has been associated with the drawback of easily absorbing moisture to aggregate.
Furthermore, it is well known that protein is insolubilized against water by means of various organic compounds, for example, aldehydes such as formalin, chlorotriazine, mucoehromic acid, etc. It is known as well that protein is insolubilized by certain metal ion such as chromium ion. These compounds have been important in photographic industry, but the insolubilizing effect thereof is excessively slow or the stability of compounds themselves is not sufficient.
SUMMARY OF THE INVENTION As the result of extensive investigations on reaction conditions between hydrophilic macromolecular substances and various organic compounds, the presentare capable of extremely rapidly solidifying hydrophilic macromolecular substances such as gelatin, at a pH value not lower than 8 and in the presence of metal ions. On the basis of this finding, the present inventors have reached a novel and useful imaging process which comprises selectively eliminating or adding imagewise at least a compound of a system consisting of (A) hydrophilic macromolecular substance, (B) a metal ion belonging to groups 6A, 7A, 8, 1B or 2B of the periodic table (periodic table of IUPAC Comptes Rondus XXIII Conference, p. 183, 1965), including chromium, manganese, iron, cobalt, nickel, copper, zinc, palladium, silver, cadmium, mercury, gold, molybdenum, tungsten, rhenuim, ruthenium, rhodium, osmium, iridium, and platinum. (C) a compound capable of maintaining the pH value of water or a water-containing solvent at not less than 8 when brought into contact therewith or a substance which provides such a compound when decomposed, and (D) a compound represented by the following general formula:
l l l I I l l I wherein Z and 2' represent a group of non-metallic atoms necessary to complete a heterocyclic structure; X represents an anion; and Y represents an atom belonging to group 68 of the periodic table, from or to said system thereby obtaining an image containing water-insoluble macromolecular substance.
In this invention, the imagewise elimination or addition of component(s) of said system can be realized by various methods such as electrolytic electroconductographic process, electrophotographic processes, electroconductive recording processes, thermal recording processes, etc., or naturally by direct manual addition.
According to our invention, all four components must be present to form an image. Thus, it is clear that the image can be formed only at those portions where all components are present. For example, by contacting imagewise a gelatin layer (A) containing metal ion (B) and compound (D) with alkali solution(C), an image is formed by an addition process. On the other hand, in the system wherein all four components are present, one (or more) component may be eliminated imagewise. The latter is an eliminating process. Thus, the present invention may be carried out by eliminating at I least one component from a system containing all of four components, (A), (B), (C), and (D). For example, the alkali (C) may be removed by adding an acid.
One preferable embodiment according to this purpose comprises (1) introducing into a system containing all of four components a substance which can release a compound acting as an acid by action of electromagnetic radiation, (2) imagewise exposing the system to an electromagnetic radiation to form an acid which neutralizes an alkali (that is removes alkali (C)) whereby an image is formed.
As the substance releasing the acid, organic halogen compounds may be used such as carbon tetrabromide, iodoform, hexachlorethan, polyvinylchloride and polyvinylidene-chloride. These compounds release a halogen radical upon exposure to electromagnetic radiation. The halogen radical catches a hydrogen atom from the system to form hydrogen halide which is a strong acid.
The image obtainable according to this invention is composed of a macromolecular substance and therefor can be utilized not only for ordinary recording and copying but also for preparing printing plate for spirit printing, offset printing, intaglio printing, letterpress printing, and mimeographic printing and preparing gelatin reliefs for dye transfer prints. Also the image obtainable according to this invention can be applied to the preparation of printed circuits, braille printing and transparencies for overhead projection. Also, according to the invention it is possible to produce electron beam recording materials.
In summary, the main object of this invention is to provide a macromolecular image and processes for forming the image.
BRIEF DESCRIPTION OF THE DRAWINGS lytic treatment.
FIG. 5 shows the method of removing the photoconductive layer from the photosensitive element after said treatment with warm water.
FIG. 6 shows the method of removing electroconductive layer.
FIG. 7 shows the metallic image obtained according to this invention.
FIG. 8 shows the method of thermographic copying according to this invention.
FIG. 9 shows the polymer image obtained by thermographic copying according to this invention.
FIG. 10 shows the mimeographic plate material according to this invention.
FIG. 11 shows the mimeographic plate prepared according to this invention.
FIG. 12 shows the method of transferring the polymer image obtained according to this invention onto a metallic plate.
FIG. 13 shows the method of etching the surface of metallic plate after said transfer.
FIG. 14 shows the printing plate obtained by removing the polymer image after said etching.
DETAILED DESCRIPTION OF THE INVENTION The hydrophilic macromolecular substance (A) employed in this invention preferably contains a primary amino radical. Such macromolecular substance can be, for example, a natural protein containing lysine or arginine as amino acid units such as gelatin, glue, casein, aloumin, protamin, globrin, etc. Also, various synthetic macromolecular substances containing primary amino radicals can be used for this purpose.
As examples of such synthetic macromolecular substances there are polymers obtained from aminecontaining monomers, i.e. aminoethylvinylether (Liebigs Annales der Chemie, 601, 81 (1956)); aminostyrene (Chemical Abstract 34, 389 (1940)); aminophenyvinyI-ether (Chemical Abstract 56, 12,781 (1962 or vinylbenzylamine (Berichte der Deutschen Chemischen Gesellschaft 56, 2,154 (1923)). Copolymers containing the above-mentioned monomers can be utilized for this purpose.
Also employable are polymers obtained from macromolecular reactions such as between polymethyl acrylate and diamines (Die Macromolecular Chemie, 22, 31 (1957)) or the reduction of polyacrylamide by lithium aluminum hydride (The Journal of Organic Chemistry, 26, 1274 (1961)). Polymerized primary amines such as polyvinylamines, polylysine, etc. fall within this category.
The following table shows examples of synthetic polymers containing primary amino radical:
CII2-CII- 27 8 III 4 ll ll) oooom CHz-CII a 2 2 1 1 1 ooNuwHanNH,
-CH2CH 2 CH NHr n a 3 3 a 2 2 30, 1%NaC1 2.60 1.85 1.88 1.83 1.54 1.62 3.07
Intrinsic viscosity at 30 C. in 1% aqueous solution sodium chloride.
6 These polymers can be prepared by conventional The metallic ion (B)to be employed in this invention processes, as shown by the following examples. is preferred to-be an ion of an element belonging to Synthesis of polymer 1 groups 6A, 7A, 8 1B or 2B of the periodic table, such 76 g of a copolymer of methyl acrylate (30 mol. peras chromium, manganese, iron, cobalt, nickel, copper,
cent) and acrylamide (70 mol. percent) was dissolved 5 zinc, palladium, silver, cadmium mercury, gold, etc., in 2 l. of water, and 25 g of 1,3-propane diamine added and particularly suitable for this purpose are the ions of under agitation. The system was kept at 40 50C for manganese, cobalt, nickel, copper, zinc, silver and cad- 4 hours. The aqueous solution of polymer containing mium. These metal ions can be employed in the imagprimary amine thus obtained was subjected to dialysis ing process as a water-soluble salt, or as a salt sparingly with distilled water for one night and then freeze-dried. soluble in the case of the above-mentioned particularly The polymer obtained was found, by titration with 0.05 preferred metals. A complex salt, of course, naturally N hydrochloric acid, to contain amino radicals in an meets this purpose. These metal ions can be used in this amount of 3 mol. percent. 'llre polymer showed an ininvention singly or in combination. Furthermore, it is trinsic viscosity [1 tag- 260. T possible to use various compounds capable of generat- The copolymers 2 to 6 are prepared repeating the [5 ing the above-mentioned ions by decomposition, oxidamethod of synthesis of Polymer 1 except the starting tion, reduction, etc. The ions are particularly preferred copolymers and the reaction conditions shown in the to be divalent, but ions of other valence states such as following table. Cr or Fe can be employed, depending on the Polymer 2 3 4 5 6 Starting copolymer composition acrylamide 90 80 95 90 80 methylacrylate 10 5 10 20 Reaction time 4 4 3 3 3 (hour) r Reaction temperature (C) 40-50 40-50 -40 30-40 30-40 Synthesis of p lym r 7 conditions for forming the image. Some kinds of the 14.2 g (0.2 mol.) of powdered polyacrylamide (mo- 30 aforementioned metal ions can per se render gelatin inlecular weight about 100,000) was dispersed in 11. of soluble, but the effect attained according to the invendioxane, 4 g of lithium aluminum hydride and heated tion is far stronger than due to these ions alone. Also, for 6 hours under reflux (ca. 100C) and agitation. it is found that the quantity of metal ions necessary to Gradually there was added to the reaction mixture 5 render the gelatin insoluble is considerable less as compercent hydrochloric acid to inactivate unreacted lithpared to the case of using only metal ions alone. ium aluminum hydride. Then dioxane was removed Compound to be mpl yed In his nventi n can until the reaction product became solid. The solid was be an Organic or inorganic compound which becomes typically being the alcohols, ketones, dioxanes, etc.
dissolved in 100 ml. ofa 5 percent aqueous solution of alkaline wh n ought into contact w th water or wasodium hydroxide to obtain a homogeneous aqueous ,te -eentem s ql 9 example mustratwe l i f h polymfl Th l i was l d i a 40 ganics are oxides, hydroxides, carbonates, etc., of alkali cellophane bag, subjected to dialysis overnight in dismetals and alka'h f f metalswfuer'shluble orgahlc till d water d th f d j Yi l q lg o g, ; bases such as ptpertdme, morpholme, triethanolamme i&7u, -r 3.07. Titration v'vi'tii 0.05N hydrochloric can s be employed for this P p Further, p acid showed that the content of amino radicals was 2 15 the use of Compounds capable of rendering the mo]. percent. medium alkaline upon being decomposed by an elec- The macromolecular substance (A) to be employed tl'ic cuffeht of y heating Ah example P Sucha P in this invention is preferred to be soluble in cold or hot pound 18 Water, Whlch renders h area m pr ximity to water or in a water-containing ix d l t where a cathode alkaline when electrolyzed. Urea, thiourea,
there is 20 percent by volume of water, the solvents ammonium l be pl y in this vention since these compounds are easily decomposed Macromolecular substance (A) can be associated with y ating o render the atmosphere alkaline due to other macromolecular substances miscible with subgenerated ammonia. It is also possible to use substrates stance (A), for example, polyacrylic acid, polyvinyl alcapable of generating a basic material under electron cohol, polyacrylamide, polyvinylbenzene sulfonic acid, eam radiati n. for e amp p ya y n d po ypolyamide, etc. or copolymers thereof where the ratio methy ol ac y am de, p ly mylpynd e.
of the macromolecular substance (A) must be to the polyvinylamidazole or copolymers containing said other macromolecular substances is typically greater compounds. In this invention a pH value not lower than than 0.1. 8 is required for the formation of the image.
The minimum mumber of primary amino groups in Compound represented by the foregoing general the polymer is two (2). The preferable amount may be formula (I) is found to be particularly effective when more than 2 per 1,000 of recurring units of the poly- Y therein stands for sulfur or selenium atom. As X mers. There is no restriction as to the position of the such an ions as Cl,Br',l',ClO ',HSOf and primary amino group in the polymer. The terminal groups of the polymer are not necessarily a substantial 0386-508 part of the invention.
may be mentioned.
Reaction between the polymer, the compound and the metal ion is thought to occur as follows: a primary amino group of the polymer reacts with compound (D) and bonds to a carbon atom which is attached to S and Y to form a Schiff base and simultaneously ring Z is opened to form an SH group. (Ring Z is usually remained). Then two SH groups thus formed are bonded through the metal ion by forming a complex.
Thus a cross-linking reaction is completed as illustrated l y hei l winamodels--. a- Polymercompound metal polymer As mentioned above, the compound (D) must react with the primary amino group and form an -SH group ion 4565mm which reacts with the metal ion. In this respect the cyclic compound (D) having the linkages represented by the foregoing general formula (I) are suitable. Compound (D) easily reacts with a primary amino group and causes a ring-opening reaction to form an Sl-l group.
As a subclass of the heterocyclic nucleus, Z and Z may be non-metallic atoms which form a five or six membered heterocyclic ring which may have further substituen ts including fusing rings.
Particularly preferred examples of species of compound (D) are listed below.
Melting point, Compound C.
1 S S Br- 258 S S1 N 3 SWS Br-- 260 4 S: S S Br 267 CHaN-N 5 Q. s s Br- 275.
H3C-S-( Y I y N- 6 Se (S7 Br- 288 7.. SYS Br- 235 I ll CH3 I MM Continued Melting point, Compound C.
9 SYS Cl- 305 II r S S Cl-2H2O J+ 11 S S L C104 196 N" I OH;
12 S S ClOr' 220 T TCH: !-L
13 S S C10;- 185 T on, l ,l. l
l4 STS H80;- 255 'c'dmBbhnds ll-l4 may be prepared iJdEElibed in Nippon Yakugaku Zasshi (Journal of the Pharmaceutical Society of Japan Vol. 89, pages 469-474 (1969)).
Compound (D) can generally be easily synthesized by heating an azole compound containing a methylmercapto radical and ethylene bromide or 1,3- dibromopropane at ca. C, as shown by the following examples.
Synthesis of Compound 1 20 g of ethylene bromide and 16 g of Z-methylthiobenzothiazole were heated at 160C for 4 hours. After cooling, the precipitated crystal was collected by filtration and recrystallized from ethanol to obtain 17 g of Compound 1 as needles melting at 258C.
Synthesis of Compound 6 20 g of Z-methylthiobenzoselenazole and 20 g of ethylene bromide were heated at 160C for 4 hours. After cooling, the precipitated crystal was collected by filtration and recrystallized from ethanol-water mixture to obtain 18 g of compound 6 as needles melting at 288C.
Compounds 8 and 9 and Compound 10 can be synthesized according to the process described in Chemical Abstracts 72, 31666 (1970), and ibid. 63, 11569 (1965), respectively.
It has been found that compound (D), when added to the hydrophilic macromolecular substance (A), shows an effect of lowering the solubility thereof in warm water (typically above 35C. due to a crosslinking reaction, and that said effect is enhanced in the presence of a metal ion and in alkaline conditions.
When an aqueous solution containing compound (D), hydrophilic macromolecular substance (A) and metal ion (B) is made alkaline, the solution immediately shows a crosslinking reaction to turn to the gelled state or a remarkable increase of viscosity, though,
without gelling, in certain cases. Gelling occurs where A more cross-linkages occur than viscosity increasing state. The metal ion (B) is found to be effective even in trace amounts, and does not show any adverse effect so long as it is totally soluble in the system.
As regards the crosslinking reaction between substance (A) and the compound (D), the amount of the compound (D) should not be less than 0.2 parts (hereinafter amounts will be represented by parts by weight), preferably not less than 2 parts, per 1,000 parts of the macromolecular substance (A). As indicated, the amount of metal ion (B) can be very small, and is found to be effective in an amount of 0.002 parts with respect to 1,000 parts of compound (D), but is preferably present in an amount of 0.01 parts or more with respect thereto.
The above-mentioned quantitative relationships arise exclusively from the requirements for the crosslinking reaction, and the amounts to be employed in the practical cases vary depending upon the exact embodiment.
it is possible that a compound can act as component I (A) as well as component (C). For example, certain synthetic polymers containing primary amino radicals as mentioned above show a pH value higher than 8 in aqueous solution, and therefore can be employed as component (A) as well as component (C).
Of course, it is possible to subsequently render the obtained polymer image stronger by using a known hardener.
The following applications of this invention will be explained with reference to the attached drawings. APPLICATION I APPLICATION IN ELECTROLYTIC ELECTRO- PI-IOTOGRAPI-IIC PROCESS The process of this invention can be applied to an electrolytic-electrophotographic process to obtain an image by means of the decrease of electrical resistance resulting from light exposure on a photoconductive material. Known electrolytic-electrophotographic process consist of the steps of projecting a light image on a photoconductive layer which is composed of a powdered photoconductive material such as cadmium sulfide, titanium oxide, zinc sulfide, zinc oxide, etc. uniformly dispersed in an insulative resin, and which is provided on an electroconductive support material, and subjecting the layer to electrolysis simultaneously with, or succeeding said projection, in an electrolytic bath containing suitable material capable of forming image on said layer by means of reduction or oxidation, thereby effecting an electrolytic reaction in accordance with the pattern formed due to the difference in electroconductivity resulting from photoconduction to obtain a visi-' ble image.
As an example of such electrolytic electrophotographic process there is disclosed in U.S. Pat. No. 3,010,883 a process of obtaining a copy by treating a recording material provided with a photosensitive layer of zinc oxide in an electrolytic bath containing metal salts which are capable of forming a colored metal image when reduced, e.g., silver nitrate, nickel chloride, cupric sulfate, etc., or an organic compound capable of generating color when reduced. There is also already known a modified process in which, for example, indium oxide is added alone, or together with zinc oxide to the photosensitive layer while the electrolytic bath has added thereto only salts of relatively basic metals which reduce the indium ion contained in the photosensitive layer. Also known is a process in which water-soluble metal salts capable of giving a metal image when reduced are mixed with hydrophilic binder, such as gelatin, and applied onto the surface of photosensitive layer together with other electrolytes.
This invention provides extremely desirable results .when applied to such an electrolytic electrophotographic process. In such an application it is possible to employ an ordinary photosensitive element for the electrolytic electrophotographic process, namely, one composed of a support material provided with suitable mechanical properties and a photosensitive layer provided thereon and consisting of powdered photoconductive material in an electroinsulative binder.
In order to apply the electric potential required for electrolytic reaction, the interface between the support material and the photosensitive layer is required to be highly electroconductive. Consequently, if the support material is composed of a plastic material etc., it is necessary to provide the surface thereof with a thin layer of aluminum or other metal though ordinarily vacuum deposited aluminum is used. Examples of other available support materials are electroconductive glass provided with a thin layer of tin oxide, paper containing carbon black, paper containing fine metal fibers, paper laminated with aluminum foil, etc. The use of a metal plate as the support is naturally desirable.
The photosensitive layer consists of a thin layer of an intimate mixture of, for example, photoconductive zinc oxide and an electroinsulative binder. The zinc oxide is preferably manufactured by the French method. The binding material has a significant influence on the electr'sphsts' rassre"ptaasaias'and cah b'aesresipnasa s styrene-butadiene copolymers (Pliolite S--5D and S7; Goodyear Tire and Rubber). Fatty acid epoxy esters, vinyl chloride-vinyl acetate copolymers, polyvinyl acetate, etc. can also be utilized for this purpose. The binder can have added thereto plasticizers, inactive pigments (for example colloidal silica, talc, titanium dioxide, etc.), lubricants, etc., if desired. The addition of surface active agents is often desirable in order to regulate the coating properties. sensitizing dyes are often added in order to widen the photosensitive wavelength range of the zinc oxide, which is basically limited to the ultraviolet to blue region. Other sensitizing materials may also be added as minor additives.
This invention can be applied to electrolytic electroconductographic process by adding the components (A) hydrophilic macromolecular substance; (B) metal ion; and (D) the aforementioned compound to the surface of the photosensitive layer or to the electrolytic bath. The alkali generating compound (C), water in this case, renders the proximity of the cathode alkaline upon electrolysis. In this case it is possible to add all three components (A), (B) and (D) to the electrolytic bath, or to overlay the three components in layers on the photosensitive layer. Furthermore, it is possible to apply components (A) and (B) or (A) and (D) in layers on the photosensitive layer and to add component (D) or (B) into the electrolytic bath, respectively.
pared photosensitive element 10, which is composed of a transparent or opaque support material 11, an electroconductive layer 12 and an insulative photoconductive layer 13, on which is provided a hydrophilic macromolecular layer 14 consisting, for example, of gelatin and aforementioned compound 1. Such a macromolecular layer 14 preferably has a thickness of 0.1 500 microns in the dry state.
FIG. 2 shows the step of imagewise light projection on the photosensitive element shown in FIG. 1, in which a transparency original 21 consists of opaque areas 22 and translucent area 23 distributed according to the image. The uniform light from above (indicated by the arrows) is transmitted through the transparent area 23 of original plate 21 and the macromolecular layer 14 and reaches the photoconductive layer 13 to thereby form a low resistance area [a] and high resistance area [b]. Layer 14 may previously have added thereto a dye or pigment. If such a dye or pigment has an absorption within the sensitive wavelength range of layer 13, it is also possible to form said macromolecular layer 14 after the imagewise exposure of the photoconductive layer 14 to light.
FIG. 3 shows the step of effecting electrolysis on the photosensitive element 10 after imagewise exposure, thereon, where 31 is a container for electrolytic solution 32 consisting, for example, of an aqueous solution of metal ions (B). It has been found in this step that a slightly acidic electrolytic bath is capable of providing a sharper image. The photosensitive material 10 after imagewise exposure thereon and a counter electrode 33 are, respectively, connected with the cathode and anode of an electric source 34 which supplies a voltage of 0.3 100 volts DC for the electrolysis. During the course of electrolytic treatment, gelatin in area [a] of the macromolecular layer is rendered insoluble in water which is warm by means of a crosslinking reaction with metal ions (B) and compound (D) due to alkalinity generated by the electrolysis of water. Such a reaction does not proceed in unexposed area [b] in macromolecular layer 14 due to the absence of an increase in the pH value. It has also been found possible to obtain a colored macromolecular image by adding a compound capable of generating formazan dye on reduction, such as triphenyltetrazolium chloride, in the electrolytic bath. More simply, it is also possible to add a coloring component not causing undesirable effects upon the crosslinking reaction in the electrolytic bath by incorporating the colored component into the macromolecular image to render the image more easily visible.
tive surface through an electrode connected thereto (the cathode is connected when zinc oxide is used as the photosensitive material) in the electrolytic bath directly after or during the imagewise exposure. The electrolytic bath can be substituted for by absorbent materials capable of holding electrolytic solution in an amount sufficient to effect the electrolytic treatment, such as brushes, sponges, porous papers, etc. Contact between the electrolytic bath and the photosensitive layer can be made either at one time over the whole surface thereof or progressively in small portions thereof, such as by a roll covered with sponge.
FIG. 4 shows the step of treatment with hot water of the photosensitive material after the electrolytic treatment thereon, in which uncrosslinked area is removed 'by the hot water 42 supplied from the nozzle 41,
thereby leaving area [a] as a water-insoluble macromolecular image 43 on the photosensitive layer 13 to thus obtain a negative image of the original image 21.
The macromolecular image 43 thus obtained can be utilized in various printing processes. For example, the image can be employed in dye transfer printing by impregnating the image with a water-soluble dye. Thus, the sheet holding the macromolecular image 43 thereon can be used as the gelatin relief for dye transfer printing. In this case, it is possible to apply a hardening treatment in order to reinforce the image. When the photosensitive material is composed of zinc oxide, it has also been found preferable to remove the zinc oxide with acid, etc., in order to obtain a clearer transfer image. The image can also be utilized in spirit printing by impregnating the image with a sufficient amount of a dye soluble in water and alcohol.
Furthermore, the macromolecular image can be utilized for offset printing since image 43 is hydrophilic whereas the photoconductive layer 13 is hydrophobic. Furthermore, it is possible to obtain a thick macromolecular image 43 by subjecting macromolecular layer 14 with a dry thickness larger than 10 microns to electrolytic treatment. Such an image constitutes a relief of considerable height in the water-containing state, and therefore can be utilized in braille printing or in letterpress printing with an aqueous printing ink.
It is possible to obtain a metal image by further treat ment on the sheet provided with macromolecular image 43. Such treatment may comprise, as shown in FIG. 5, spraying a solvent 52 for the binder of the photoconductive layer 13 from a nozzle 51 thereby removing the photoconductive layer except for the area 53 protected by the macromolecular image 43, and then spraying an etching solution 62 from a nozzle 61 to thereby remove the thus exposed elcctroconductive layer as shown in FIG. 6. In this case the said electroconductive layer 12 and the etching solution 62 are, respectively, composed of a copper chloride and ferric chloride solution. Successive removal of macromolectain a resist image on the plate (the plate may be, for
example, copper). The pressing can be accomplished by means of a roller 121. A'successive etching treatment as shown in FIG. 13, followed by removal of the macromolecular image [e], provides a printing plates as shown in FIG. 14. The area [f] indicates the nonetched surface of the plate.
It is also possible to prepare a mimeographic printing plate according to this invention by an electrolytic electroconductographic process. A photosensitive element for preparing mimeographic printing plate is shown in FIG. as composed of a support material 11, an electroconductive layer 12, a photoconductive layer 13 and a porous sheet 101 composed, for example, of Japanese paper impregnated with hydrophilic macromolecular material 100 and aforementioned compound (D). The Japanese paper layer can be provided on the photosensitive layer 13 prior to or after the imagewise exposure thereof, but it is preferred to provide the layer after imagewise exposure in order to obtain a mimeographic plate of higher quality. The area [d] indicates the unexposed portion of the photosensitive layer. The electrolytic bath employed in this case is preferred to be slightly acidic and to contain metal ions (B). The mimeographic printing plate as shown in FIG. 11 can be obtained by washing the element with hot water after electrolytic treatment to thereby remove unexposed areas, and peeling off the Japanese paper layer from the element in a solvent for the binder of the photosensitive layer 13. The plate is composed of uncrosslinked area 111 permeable to printing ink and crosslinked area 112 constituting a barrier to ink.
In the case of applying the present invention to the electrolytic electroconductographic process, the temperature of the electrolytic bath is preferred not to exceed 45C, since a temperature exceeding this limit will accelerate the decay of retentive photoconduction resulting from light irradiation and makes complete crosslinking reaction impossible.
APPLICATION II APPLICATION IN AN ELECTROPHOTOGRAPI-IIC PROCESS On the other hand, a layer of hydrophilic macromolecular substance (A) provided on a water-resistant support material is moistened with an alkaline aqueous solution and pressed against a xerographic plate holding developed toner image thereon. After pressing, the sheet provided with the macromolecular layer is peeled from the xerographic plate and treated with hot water. The macromolecular layer after treatment is found to be insolubilized exclusively in the area which has been in contact with the toner image. Generally, in this case at least one member in the four components (A), (B), I
(C) and (D) is incorporated in the toner thereby electrophotographically making the four components pres ent in the image area to cause the crosslinking reaction. Thus, the hydrophilic macromolecular image is obtained exclusively in the area where the four components are all present. Theoretically, it is possible to use any and at least one member of the four components I in the toner, but practically the hydrophilic macromolecular substance (A) is preferred not to be used in the toner but to be applied in a layer on the support material in order to facilitate handling.
The electrophotographic process used in conjunction with the present invention can employ any conventional developing processes, such as cascade developing, magnetic brush developing powder cloud developing, liquid developing, toner sheet developing, etc. In
addition, it is also possible to obtain a macromolecular image by bringing an aqueous alkali solution impreg: nated in a porous material, such as sponge, into contact for a short period with the surface holding the electrostatic latent image to thereby form the distribution pattern of alkaline material on the xerographic plate, and then press a sheet provided with a wet layer containing components (A), (B) and (D) against the surface of the xerographic plate.
APPLICATION Ill APPLICATION TO AN ELECTROCONDUCTIVE RECORDING PROCESS This invention can easily be applied to an electroconductive recording process to obtain a macromolecular image by means of a crosslinking reaction initiated by the alkalinity generated at the proximity of a cathode by an electric current. For example, in this case a recording layer of hydrophilic macromolecular substance (A) containing compound (D) and metal ion (B) provided on an electroconductive support material is moistened with water or water vapor prior to recording thereon and a metal needle is displaced while keeping contact therewith. An electric voltage modulated by means of an electric signal is applied to the metal needle in order to generate alkalinity on the layer in correspondence with the electric signal. The alkalinity causes the crosslinking reaction in the macromolecular layer according to the amount of electric current passed therethrough.
A water-insoluble macromolecular image can thus be obtained by treating the recording layer with hot water. The image thus obtained can be utilized for multiple copying by means of dye transfer process.
Metal ion (B) can be supplied from the metal needle instead of being incorporated as a water-soluble salt in said recording layer. For this purpose, the metal needle can be composed, for example, of silver, nickel, cobalt, zinc, etc. Metal ions are generated from the metal needle connected with the anode of the electric source and supplied into the recording layer. Excessive metal ion is again reduced to the metallic state and deposited on the surface of the recording layer, giving a colored macromolecular image in this case.
The metal needle can be used singly or in the form of pin matrix. Thus, according to this invention, it is possible to obtain a printing plate from a pin matrix type cathode ray tube.
APPLICATION IV APPLICATION TO A THERMOGRAPI-IIC COPYING PROCESS This invention can further be applied to a thermal copying process as shown in FIG. 8 showing a support material 81 of low thermal conductivity and a thermosensitive recording layer 82. In this case, the thermosensitive recording layer 82 is composed of hydrophilic macromolecular substance (A), metal ion (B), a compound capable of generating alkali when decomposed (C) and compound (D). Alkaline source (C) can be, for example, urea, thiourea, ammonium carbonate, etc., which liberates alkali on decomposition by heatmg.
In this process recording layer 82, contacted tightly against an original 83, is exposed to uniform irradiation of infrared light for a short period. The image area 84 in the original which absorbs infrared light shows a local temperature increase, resulting in a local temperature increase by thermal conduction in the corresponding area  in the recording layer. In area , compound (C) is thermally decomposed to render the area alkaline, thereby causing a reaction between the hydrophilic macromolecular substance (A), metal ion- (B) and compound (D) to insolubilize the macromolecular substance (A) against water. Thus a macromolecular image 91 is obtained on the support material 81 by treating the recording layer with hot water after the exposure to infrared light. The sheet holding the thus prepared image thereon can be utilized as a gelatin relief for dye transfer printing, as an offset printing plate, as a spirit printing plate, etc.
A recording layer containing the macromolecular substance (A), metal ion (B), alkali source (C), compound (D) and a colored powder such as a pigment or dye is suitable for direct recording with laser light. When the surface of such a recording layer is scanned with a signal-modulated laser light, the colored powdered material absorbs the light to elevate the temperature thereof, resulting in the decomposition of alkali source (C) and initiating the crosslinking reaction. OTHER APPLICATIONS This invention can naturally be applied to the direct scribing recording process. In such a case, a recording layer containing hydrophilic macromolecular substance (A), metal ion (B) and compound (D) is provided .on a transparent support material, and the recording is directly inscribed on the layer with a pen, painting brush, felt pen, etc., containing an aqueous solution of alkali (C). This aqueous solution may be colored, if desired. After inscribing, the recording layer is treated with hot water to remove unrecorded areas, thereby leaving a macromolecular image on the transparent support. The sheet thus prepared can be utilized as a transparency for overhead projection as an original plate for making multiple transparencies by the dye transfer process.
Furthermore, this invention can be applied to electron beam recording. For example, when a recording element consisting of a recording layer containing the hydrophilic macromolecular substnace (A), metal ion (B), compound (D) and a compound capable of generating alkali when decomposed under electron beam irradiation and a support material is subjected to electron beam irradiation, compound (C) is decomposed in the irradiated area to cause a hardening reaction.
It is also possible to obtain a hydrophilic macromolecular image by providing pressure-rupturable microcapsules containing alkaline material (C) on the bottom surface of a paper sheet, placing thereunder another paper sheet provided with a layer containing components (A), (B) and (D) and rupturing the microcapsules by means of scribing pressure, etc.
The process of this invention is thus characterized by the co-existcnce at imaging of the aforementioned four components (A), (B), (C), and (D),
This invention will be further explained by the following examples. It will be readily understood to those skilled in the art that the examples cited below can be subjected to variations and modifications as to the composition or combination of components, order of the process, etc. within the scope of this invention, and therefore, the examples should not be regarded as limiting this invention. Parts mentioned are by weight.
Example 1 The following composition was kneaded for 20 hours in a porcelain ball mill:
Photoconductive zinc oxide (Sakai Chemical, Sazex) I00 parts Pliolites S-SD (Goodyear Tire and Rubber) (styrene butadiene copolymer, the molar ratio of styrene and butadiene being 851l5) 25 parts Toluene parts Methylethylketone 25 parts The white paste thus prepared was diluted with tolu- (Photographic grade) gelatin 6 parts Compound-l 0.4 parts Nickel chloride hexahydrate 9 parts Distilled water parts The periphery of the sheet was covered with insulative adhesive tape prior to dipping into the electrolytic bath in order to prevent direct contact between the bath and the aluminum layer. The electrolysis was carried out by placing a nickel plate as an anode at a distance of 1.5 cm from the sheet of which the aluminum layer acted as cathode. A DC. potential of 4 volts was applied therebetween. The sheet was taken from the bath after electrolysis for 10 seconds. In this condition the sheet was wet exclusively in the exposed areas which showed a pale gray color. The sheet was then washed with water, dried and finally wiped with a sponge impregnated with an aqueous solution (concentration 0.2 percent) of a blue dye (C.I. acid blue 54) to obtain a blue negative image. The optical density of the image was 0.57.
Example 2 17 Example 3 in this example, a percent aqueous solution of photographic gelatin was coated onto the photosensitive layer in Example 1, and cooled and dried to obtain gelatin layer 1.9 microns thick after drying. The photosensitive layer was successively subjected to imagewise exposure at ca. 10,000 lux for 8 seconds with a light source as in Example 1.
The composition of the electrolytic bath employed was as follows:
Nickel chloride hexahydrate 3 parts Cobalt (ll) chloride hexahydrate 2 parts Compound-l 0.4 parts Distilled water 100 parts The sample was washed with hot water after electrolytic treatment as in Example 1. After drying, the sample was coated with an aqueous solution of formalin to harden the gelatin image and dipped into an aqueous solution of CI. acid blue 54 as in Example 1. Then the aqueous solution of Color Index acid blue 54. A transfer process as shown in Example 3 provided a dark blue transferred image. it was found that the gelatin layer was totally insoluble in hot water in the area subjected to maximum exposure.
Example 5 The procedure of Example 4 was repeated except that the electrolytic bath had further added thereto 0.2 parts of Compound I. The results obtained were comparable to those of Example 4.
Example 6 I in this example the photosensitive layer was dyesensitized by adding a dye solution of the following composition to the photosensitive composition of Example l at the solvent dilution thereof. The following table also indicates the resulting sensitivity to white light (tungsten lamp, color temperature ca. 3,000K). The amounts in this table are with respect to 100 g of zinc oxide.
sample was pressed against a sheet provided with a gelatin layer which had been previously subjected to modanting treatment to thereby obtain a blue transferred image on the sheet. As a result it was found that gelatin in the exposed areas was insoluble in hot water with a maximum thickness of 0.2 microns.
The following composition was coated onto the photosensitive layer of Example 1.
Gelatin (Photographic grade) 5 parts Compound-l 0.5 parts Compound-4 0.1 parts Distilled water 100 parts The thickness after drying of the gelatin layer was 2.0
microns. The electrolytic bath employed was as follows:
Nickel chloride hexahydrate 3 parts Cobalt (ll) chloride hexahydrate 2 parts Hydrochloric acid 0.02 parts Distilled water 100 parts After exposure and electrolysis as in Example 1, the photosensitive surface was washed with hot water at 45C to leave thereon a pale-gray gelatin image which was so sharply raised that it could be felt with ones fingers.
The temperature of the warm water capable used generally ranges between about 30C. and about 98C. After drying, the sample was further treated with formalin to harden the gelatin image and dipped into an Photosensitive layer No. 3 was further provided with a gelatin layer as shown in Example 4 and subjected to imagewise exposure through a negative photographic film placed in a photographic enlarger (enlarger for 35 mm film produced by Fuji Photo Film.) The exposure was carried out for 3.5 seconds with maximum luminance at the exposed surface of lux. Electrolytic treatment similar to that in example 4 provided a satisfactory positive gelatin image.
The procedure of Example 1 was repeated using an electrolytic bath of the following composition:
Polymer-l 5 parts Compound-l 0.4 parts Nickel chloride hexahydrate 9 parts Distilled water parts Results comparable to those in Example I were obtained.
The procedure of Example 1 was repeated using an electrolytic bath of the following composition:
6 parts Polymer-3 Compound-2 0.3 parts Cobalt chloride hexahydrate 9 parts Distilled water 100 parts The procedure of Example I provided results comparable to those obtained in Example 1.
l9 Example 9.
The following composition was kneaded for 20 hours in a porcelain ball mill.
Photoconductive zinc oxide 100 parts (Sakai Chemical. Sazex) Pliolite S-D (Goodyear Tire and Rubber) 28 parts Toluene 1 80 parts Methylethylketone 20 parts The white paste thus prepared was diluted with toluene to an appropriate viscosity, then coated onto the copper surface of a laminated plate for printed circuits (Matsushita Electric Co.) composed of an epoxy resin support plate and copper layer provided thereon. The coating thickness was 16 microns after drying.
The photosensitive layer thus prepared was further coated with the following composition:
Photographic grade gelatin 5 parts Polymer-3 2 parts Compound-l 0.8 parts Distilled water 100 parts The coating thickness after drying was 3 microns. The electrolytic bath employed was as follows:
Cobalt (ll) chloride hexahydrate 9 parts Glacial acetic acid 0.02 parts Distilled water 100 parts The photosensitive element thus prepared was subjected to imagewise exposure through a negative original for printed circuits, electrolytic treatment, washing with hot water (45C) and hardening with formalin as shown in Example 4, and further washed with ligroin to remove the bare photosensitive layer in unhardened areas. The element was then dipped into an acidic solution of ferric chloride (40 Be) for 15 minutes at 45C, then washed with water. A sharp printed circuit was obtained by strongly wiping the hardened areas with benzene to remove the photosensitive layer and the hardened image provided thereon.
Example 1 l The procedure of Example 10 was repeated except that the laminated printed circuit plate was further provided with a vacuum-evaporated aluminum layer of 750 angstroms on the copper layer to obtain a sharp printed circuit comparable to that obtained in Example l0. In this example the aluminum layer could be eliminated by washing with a 1N sodium hydroxide solution. Insertion of the aluminum layer between the photosensitive layer and the copper layer reduced the necessary exposure time to /2 /'s that in Example 10.
, 20 Example 12 The following mixture was dried and crushed:
Compound-l 5 parts Nickel acetate 0.] parts jected to imagewise exposure to form an electrostatic latent image thereon, which was then developed with the above-mentioned dry developer by a cascade process to obtain a white toner image on the xerographic plate.
The following composition was separately coated on a sheet of polyethylene terephthalate previously irradiated with ultraviolet light (thickness: 120 microns):
Gelatin 5 parts Sodium dodecylbenzene sulfonate 005 parts (wetting agent) Distrilled water 100 parts The coating layer was first set by cooling and then dried by exposing it to warm air. The gelatin layer was swollen in a 0.1N sodium hydroxide solution at 15C and tightly pressed against the surface of the xerographic plate holding the toner image thereon. The
' sheet was then peeled off and washed with water at 45C to obtain a gelatin image corresponding to the toner image on the sheet.
Example 13 The following composition was coated onto a sheet of polyethylene terephthalate of 120 microns thick which had been previously irradiated with ultraviolet light to obtain a coating thickness of 3 microns after drying:
Carbon black 0.8 parts Gelatin 8 parts Cadmium sulfate 0.l parts Compound-2 0.6 parts Distilled water parts reproduce this transparency by dipping the sheet in a dye solution and transferring the dye to other transfer sheets.
Example 14 The following composition was coated onto a sheet of polyethylene terephthalate (thickness 60 microns) previously subjected to ultraviolet irradiation so as to provide a dry thickness of 2 microns:
Gelatin 5 parts Compound-l 0.5 parts Nickel chloride hexahydrate 0.01 parts Urea 0.8 parts Distilled water l00 parts Example I 5 The photosensitive layer of Example 1 was subjected to imagewise exposure through a line positive image. Separately, a sheet of thin Japanese paper was dipped into the following solution kept at 28C.
Gelatin 4 parts Compound-I 0.3 parts Manganese chloride hexahydrate 0.01 parts Distilled water I parts The wet Japanese paper sheet was superposed onto the photosensitive layer shown in Example 1 directly after imagewise exposure thereon and made to stick firmly thereto by setting the gelatin by means of blowing cold air thereon. The photosensitive layer was then subjected to the electrolytic treatment described in Example 1 in the electrolytic bath of Example 4, then washed with hot water, dipped into toluene and the Japanese paper sheet was peeled off the photosensitive layer. After drying, it was found that gelatin in unexposed areas (Iine image areas) was removed from the paper sheet. The thus treated paper sheet showed satisfactory performance as a stencil master (mimeographic 22 Example 18 A composition consisting of Gelatin 5 parts Red pigment (brilliant Carmine 613) l part Compound-2 0.3 part Urea 0.8 part Ferric chloride 0.01 part Distilled water 100 parts was coated to a thickness of 4 microns as a dry layer on a polyethylene terephthalate film to prepare a laser sensitive recording material. The recording material thus obtained was exposed to an argon ion laser light modified by a signal and treated with warm water at a temperature of 40C to obtain a red gelatin image.
Example 19 The following compositions were heated at 40C to form a uniform solution.
Gelatin 6 parts Compound-l 0.2 parts Cobalt chloride 0.01 parts Distilled water 100 parts To the solution kept at 70C, 10 parts of 5 percent acetone solution of carbontetrabromide was added under stirring. Carbon tetrabromide was dispersed in fine particles of about 2 microns. The solution was applied to a cellulose triacetate film of 100 microns. Dry
printing plate). Thin cloth of synthetic fibers instead of Japanese paper gave comparable results.
An epoxy resin-zinc laminate plate for letter press printing plate use was coated with the white photosensitive paste shown in Example 10. After drying, the plate was further coated with the composition shown in Example 10 in a thickness as shown in Example 10. The photosensitive element thus prepared was subjected to imagewise exposure, washing with warm water (45C), and hardening with formalin as shown in Example 4, and further treated with ligroin to remove the photosensitive layer present in the unexposed portions thereof. Then the plate was dipped into an etching solution (Itoh Chemical Co.) containing ferric chloride at 45C for 15 minutes to dissolve zinc present in the unhardened areas. After washing with water, the photosensitive layer in the hardened areas was removed to gether with the hardened image by means of wiping with benzene to provide a zinc letterpress plate.
was coated to a thickness of 2 microns as a dry layer on a polyethylene terephthalate film to prepare an electron beam recording material. The recording material thus obtained was exposed to an electron beam image in vacuum and treated with warm water to obtain a gelatin image.
" What is claimed is? thickness of the layer was 7 microns. The film was then immersed in 0.05N aqueous potassium hydroxide solution at 15C for 2 seconds and dried. By the treatment with alkali the layer was hardened and rendered insoluble in warm water (60C). The above-mentioned pro cesses were carried out under a subdued light excluding ultra-violet radiation.
The film thus formed was exposed in contact with a transparent original to a light from a high pressure mercury lamp of W at a distance of 35 cm. for 3 minutes. Then the film was washed with warm water of 60C. The exposed portions of the layer were washed out, while the unexposed portions were remained. The film was immersed in a mixed solvent of acetone and water (1:1) by volume) to remove carbontetrabromide present in the unexposed portions.
Numerous modifications of the invention will become apparent to one of ordinary skill in the art upon reading the foregoing disclosure. During such a reading it will be evident that this invention provides a unique imaging process for accomplishing the objects and advantages herein stated.
1. A process for forming an image in a system including a recording layer, said process comprising imagewise forming first and second portions in said system by forming a water insoluble first portion in or on said recording layer by reacting a hydrophilic macromolecular substance (A) containing primary amino radicals, a metal ion (B) selected from the group consisting of ions of metallic atoms belonging to groups 6A, 7A, 8, 1B, and 2B of the periodic table of the IUPAC Comptes Rondus XXIII Conference, 1965, a compound (D) represented by the following general formula:
2. An imaging process as in claim Where said reconsisting of said hydrophilic macromolecular sub-' stance (A), said metal ion (B), said compound (D) and a compound (C) capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water or a compound (C) which provides a compound (C) when decomposed and reacting the thus obtained powder image with the remaining members of said group to obtain a final image.
3. A process as in claim 1 where said recording layer contains all said substance (A), ion (B), compound (D) and a compound (C), which after decomposure, is capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water, said compound (C) maintaining the surrounding medium at a pH value not less than 8 when decomposed by electron beams, and selectively imagewise irradiating said recording layer with an electron beam to decompose said compound (C) and water insolubilize said recording layer at the electron beam exposed portions.
4. An imaging process as claim 1 where said first portion of the system is maintained at said pH value by introducing into the system a compound (C), which is capable of maintaining the surrounding medium at said pH value when brought into contact with water, and bringing said system into contact with water.
5. An imaging process as in claim 4 where said compound (C) is selected from the group consisting of oxides, hydroxides, carbonates of alkali metals and alkali earth metals and water soluble, organic bases.
6. An imaging process as in claim 1 where said pH value is maintained by applying to said recording layer an alkali solution.
7. An imaging process as in claim 6 where at least one of said substance (A), said ion (B) or said compound (D) is only imagewise present in or on said recording layer.
8. An imaging process as in claim 6 where an alkali solution is applied imagewi'se to said recording layer.
9. An imaging process as in claim 1 where said first portion of the system is maintained at said pH value by introducing into the system a substance (C) which provides by decomposition a compound, which is capable of maintaining the surrounding mediumat said pH value when brought into contact with waterfdecomposing said substance, and contacting the system with water.
10. An imaging process as in claim 9 where said substance (C) is decomposed thermally.
11. An imaging process as in claim 10 where said substance (C) is at least one member chosen from urea,
thiourea, and ammonium carbonate.
12. An imaging process as in claim 10 where said substance (C') is decomposed by electric current.
13. An imaging process as in claim 10 where said substance (C') is decomposed by laser beam.
14. An imaging process as in claim 10 where said substance (C') is decomposed by electron beam.
15. An imaging process as in claim 1 where said metal ion is selected from the group consisting of chromium, manganese, iron cobalt, nickel, coppen zincf palladium, silver, cadmium, mercury and gold.
16. An imaging process as in claim 15 where said metal ion is selected from the group consisting of maganese, cobalt, nickel, copper, zinc, silver and cadmium.
17. An imaging process as in claim 1 where said recording layer is a photosensitive element, said process including the steps of projecting a light image onto said photosensitive element comprising an electroconductive support and a photoconductive layer provided thereon and selectively passing an electric current through the exposed areas of said photoconductive layer in an aqueous solution optionally containing at least one component of said substance (A), ion (B), and compound (D) at a point no earlier than simultaneously with said exposure, the remaining components (if any) of said system being present in at least one outer layer provided on said photoconductive layer, the medium adjacent the surface of the light exposed areas of said photoconductive layer being maintained at a pH value not less than 8 by said electric current to thereby enable the components of said system to react and form a water insoluble image at the light exposed areas.
18. An imaging process as in claim 1 7 wh ere said hydrophilic macromolecular substance (A) and said compound (D) are present in outer layers provided on said photoconductive layer, and said metal ion (B) is dissolved in said aqueous solution.
19. An imaging process as in claim 17 where said hydrophilic macromolecular substance (A), and metal ion (B), and said compound (D) are present in said aqueous solution.
20. An imaging process as in claim 17 where said electroconductive support layer is disposed on a further support layer, said process comprising the further steps of selectively removing. said photoconductive layer and electroconductive support at the image area to expose said electroconductive support layer on said further support layer.
21. A process as in claim 1 where said recording layer contains at least said hydrophilic macromolecular substance (A), said metal ion (B), said compound (D), and a compound (C which after decomposure, is capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water, said compound (C) maintaining the surrounding medium at a pH value not less than 8 when decomposed by an electric current, said recording layer being disposed on an electroconductive support layer, and scanning said recording layer with means for 22. A process as in claim 21 where said metal ion (B) is present in said recording layer.
23. A process as in claim 1 where said recording layer contains all said substance (A), ion (B), compound (D) and a compound (C which after decomposure, is capable of maintaining the pH value of the surrounding medium at not less than 8 when brought into contact with water, said compound (C) maintaining the surrounding medium at a pH value not less than 8 when decomposed by heat, forming a heat image at said recording layer to thereby enable said component (A), (B), (C), and (D) to react where the image portions of said heat image are present to thereby water insolubilize the recording layer at said image portions.
24. A process as in claim 23 including providing said recording layer with an additional component which raises the temperature of said surrounding medium when it absorbs light, said heat image forming step ineluding scanning said recording layer with a modulated laser beam, the beam being so modulated that when an image portion is to be formed in said recording layer, the intensity of the beam is made sufiicient to elevate the temperature so that said component (C decomposes to thereby water insolubilize said recording layer at said image portion.