GB2023861A - Dry processable printing plate having both photopolymer and diazo layering - Google Patents

Abstract

This invention relates to energy sensitized sheet constructions, which upon exposure to an ultraviolet energy source through a screened image can accurately and simultaneously reproduce said image in both its negative and positive forms. One form of said reproduction comprises a lithographic printing plate. The sheet construction in one embodiment comprises (1) a transparent top sheet; (2) a photo-polymerisable layer; (3) a light sensitive diazonium layer in contact with the surface of the photo-polymerisable layer; and (4) a base sheet layer supporting the diazonium layer. After exposure the layers may be separated to provide negative and positive images.

Description

SPECIFICATION Dry processable printing plate having both photopolymer and diazo layering This invention relates to novel energy sensitized sheet constructions which, upon exposure to a suitable ultraviolet energy source through a screened image can accurately and simultaneously reproduce said image in both its negative and positive forms.

The novel energy sensitive sheet construction of this invention is particularly useful in the graphic arts field. For example, in the lithogragphic printing arts, it is desirable to produce a lithographic printing plate which requires no wet processing after exposure but before printing.

The novel imaging system and products of this invention comprise a layered or sandwich type sheet construction, which in one embodiment is comprised of the following elements: 1. a transparent top sheet; 2. a photopolymerizable layer applied to and contacting at least one surface of said top sheet; 3. a light sensitive diazonium layer which is applied to and in contact with the surface of said photopolymerizable layer; and 4. a base sheet layer supporting said diazinium layer and bound thereby to said other layers.

To date, it has been a problem in the art to provide an imaging system which would allow the quick, easy and dependable availability of an image reproduction, in both its positive and negative forms, having a quality suitable for use in the graphic arts and other image reproducing applications. As part of the present invention it has been found that by forming a specific layered construction and exposing it through a transparent mask to an energy source, the layers may be immediately separated whereby a positive reproduction of the mask image is apparent on one leaf of the separated construction and a negative of said image appears on the other leaf. Furthermore, these images are available after separation for a series of other uses without any further developing treatment.This is an important point of novelty since other prior art sysems require some post treatment, such as image curing or development, before a useful product can be attained. One such prior art method requires development by heat treatment, another requires solvent development. Importantly, the present disclosure requires no chemical or other curing processing subsequent to exposure as is required by such other prior art methods.

Applications for which this dry transfer system is useful include, direct transferability of the image to other surfaces, manufacture of color proofing guides, art composition, engineering drawings letter and figure transfers, photocomposition, photoresists, nameplates, presensitized printing plates, and bimetal printing plates.

Advantages over the prior art include, the elimination of chemical processing or other treatment to attain the image after exposing; availability of a colored image without subsequent treatments; finer image resolution and a higher degree of energy response; no fixing is required; the image is instantly visible upon exposure and may be evaluated for quality without further processing, allowing a continued or multiple exposure if necessary or desirable. Other advantages include safe room light handling; no pollution or exposure of workers to caustic chemicals; and transferable and erasable images in both the positive and negative forms.

British patent 712,966 describes one method of preparing a print material whereby a diazo and resin composition is coated on a base, however, this disclosure requires development by subjecting an image to elevated temperatures after exposure to actinic light through a mask.

Japanese patent S38-9663 and U.S. Patent 3,353,955 demonstrate one type of peel apart system whereby a photosensitive composition is situated between a base and a film sheet whereby the photosensitive composition has a stronger bonding force exerted on the film than on the base before exposure and a stronger bonding force on the base than on film after imagewise exposure. This system has proved to be substantially unworkable since such subtle reversals in adhesive properties are difficult to achieve with consistent results. Still another method, as developed- by the Fuji Photo Film Company employs two light sensitive layers containing photopolymers which have different adhesive attractions for a base and a covering film sheet. This has been described in West German Patent Specification No. 2,558,530.

U.S. Patents 3,060,024 and 3,060,025 show another system whereby high polymers are imagewise formed.

Upon exposure certain areas are rendered tacky, particles are dusty to tacky areas, a transfer sheet is applied to the substrate and heated and the films then separated. In the instant invention there is no required application of dusted particles subsequent to exposure and no surface heating thereafter.

U.S. Patent 2,760,863 describes another system whereby insoluble high polymers are formed by photopolymerization and non-image areas are removed by washing with a solvent after exposure.

U.S. Patent 3,136,637 provides still another imaging system, which also requires solvent development.

The instant invention is distinctly different from each cited reference.

The present invention provides a multi-layered ultraviolet- energy sensitive image forming construction which is capable, upon imagewise exposure, of providing both positive and negative reproductions of an image.

The construction comprises successive adherent layers, namely a transparent top layer, a photopolymerisable layer, a photosensitive diazo layer, and a base support.

Upon imagewise exposure of the construction through a mask, the radiant energy is selectively transmitted through the transparent top layer and causes activation and hardening of the photopolymerizable layer.

The radiant energy then passes through the photopolymerizable layer and reaches the light sensitive diazonium layer thereunder, thus selectively hardening it by a method well known in the art. By separating both the top and base layers, the adhesive forces exerted between the layers are such that the photopolymerizable and diazo layers are imagewise sheared and selectively adherent to both the top and bottom layers such that a positive reproduction of the original image is apparent upon the top layer and a negative reproduction of the image is apparent upon the bottom layer without anay further processing.

When the base support comprises a suitable substrate, it may be effectively employed as a lithographic printing plate.

Both positive and negative images are now available for use in any of a variety of ways as hereinbefore discussed.

It is, therefore, an object of the present invention to provide a multilayered image forming construction which is capable of providing image reproduction in both its positive and negative form.

It is another object of the present invention to provide a multilayered image forming construction which does not require additional curing treatment or development after exposure.

It is a further object of the present invention to provide a long running, commercially acceptable lithograhic printing plate without wet development treatments after imagewise exposure to an ultraviolet light source.

These and other objects of the invention will be in part discussed and in part apparent upon consideration of the detailed description of the preferred embodiment as provided hereinafter.

As heretofore mentioned, the construction of the instant invention comprises a base support having a surface which is either hydrophilic or has been made hydrophilic, a light sensitive negative acting diazonium layer adhered to said hydrophilic surface of said base support, a photopolymerizable layer adhered to said diazonium layer and a flexible, transparent top support adhered to said photopolymerizable layer.

When said construction is imagewise exposed to ultraviolet radiation through a photographic transparency from the direction of the transparent top support, said radiation causes the exposed photopolymerizable material to harden and further causes the exposed diazonium layer to insolublize and tenaciously adhere to both the base support and the exposed photopolymerizable layer.

When the bottom and top supports are peeled apart, the strongly adherent exposed diazonium layer is firmly bonded to the bottom support and the exposed photopolymerisable layer. Whereas, at the unexposed areas, there is no such firm bond between the bottom support, and the diazonium layer and the unexposed photopolymerizable and diazonium layer adhere to the top rather than the bottom support.

Therefore, upon peeling apart the top and bottom supports a positive reproduction of the photographic transparency appears on the top support in the form of the unexposed photopolymerizable and diazo layers and a negative reproduction of the photographic transparency appears on the bottom support in the form of the exposed diazonium and photopolymerizable layers.

In accordance with the present invention it has been found that the base layer, may be comprised of any solid sheet material having a substantially regular surface which is or has been made hydrophilic by methods well known in the art. These include, but are not limited to the following compositions and combinations thereof: glass, metals, e.g. aluminum sheets, paper, silicon, and films or sheets comprised of: Acrylonitrile-butadiene-styreneterpolymers (ABS) Cellulose Acetate Cellulose triacetate Cellulose acetate butyrate Cellulose propionate Polybutylene Polybutadiene Polycarbonate Polyester Polyethersulfone Polyethylene (low, medium and high density) Ethylene-propylene copolymers Ethylene vinyl acetate copolymers Nylons (polyamides) Acrylonitrile copolymers lonomers Polyimides Polymethyl methacrylates Polychlorotrifluoroethylenes Fluoronated ethylene propylene copolymers Perfluoroalkoxy resins Ethylene-chlorotrifluoroethylene copolymers Ethylene-tetrafluoroethylene copolymers Polyvinyl fluoride resins Polyvinylidne fluoride resins Polypropylenes Polystyrene (and oriented polystyrene) Polyurethane elastomers Polyvinyl chloride - plasticised Polyvinyl chloride - unplasticized Polyvinyl chloride copolymer resins Polyvinylidene chloride and its copolymers Polyvinyl acetate Polyvinyl alcohol The diazonium layer may include such photosensitive compositions as the diazo and azide substances which may include the reaction product of paradiazo diphenyl-amine-para-formaldehyde condensate and 2-hydroxy-4-methoxy benzophenone sulfonic acid; P-N,N-dimethylaminobenzenediazonium zinc chloride P-N,N-diethylaminobenzenediazonium zinc chloride 4-(p-tolyl-mercapto)2,5-dimethoxybenzene diazonium zinc chloride 4-(p-tolyl-mercapto)-2,5-diethoxybenzene diazonium zinc chloride 4-morpholino-2, 5-dibutoxybenzenediazonium zinc chloride 4-morpholino-2,5-dibotoxybenzenediazonium fluoborate P-N-ethyl-N-benzylaminobenzene diazonium zinc chloride 4-diazo-diphenylamine sulfate 1-diazo-4-N,N-dimethylamino-benzene zinc chloride 1-diazo-4-N,N-diethylamino-benzene zinc chloride 1-diazo-4-N-ethyl-N-hydroxyethylamino-benzene 1/2 zinc chloride 1 1 -diazo-4-N-Methyl-N-hydroxyethylamino-benzene 1/2 zinc chloride 1 -diazo-2,5-diethoxy-4-benzoylamino-benzene, 1/2 zinc chloride 1-diazo-4-N-benzylamino-benzene, 1/2 zinc chloride 1-diazo-4-N,N-dimethylamino-benzene borofluoride 1-diazo-4-morpholino-benzene, 1/2 zinc chloride 1-diazo-4-morpholino-benzene-borofluoride 1 -diazo-2,5-dimethoxy-4-p-tolyl mercaptobenzene, 1/2 zinc chloride 1 -diazo-2-ethoxy-4-N,N-dimethylaminobenzene, 1/2 zinc chloride p-diazo-dimethyl aniline, 1/2 zinc chloride 1-diazo-4-N,N-diethylamino-benzene, 1/2 zinc chloride 1 -diazo-2,5-dibutoxy-4-morpholino-benzene sulfate 1-diazo-2,5-diethoxy-4-morpholino-benzene,1/2 zinc chloride 1-diazo-2,5-diethoxy-4-morpholino-benzene, zinc chloride 1-diazo-2,5-diethoxy-4-morpholino-benzene, 1/2 zinc chloride 1-diazo-2,5-diethoxy-4-morpholino-benzene-borofluoride 2-diazo-1-naphthol-5-sulfonic acid, sodium salt 1-diazo-4-N,N-diethylamino-benzene, borofluoride 1 -diazo-2,5-diethoxy-4-p-tolylmercapto-benzene, 1/2 zinc chloride 1 -diazo-3-ethoxy-4-N-methy-N-benzylamino-benzene, 1/2 zinc chloride 1-diazo-3-chloro-4-N-methyl-N-benzylamino-benzene, -1/2 zinc chloride 1-diazo-3-methyl-4-pyrrolidino-benzene chloride, zinc chloride 1 -diazo-3-methyl-4-pyrrolidino-benzene-borofluoride 1-diazo-2-chloro-4-N,N-dimethylamino-5-methoxy-benzene, borofluoride 1-diazo-3-methoxy-4-pyrrolidino benzene, zinc chloride condensation product of 4-diazo-diphenylamine sulfate and formaldehyde zinc chloride p-azide cinnamic acid 2,6-di(4'-azidebenzal)-4-methylcyclohexanone 3-azide phthalic anhydride 4,4'-diazide-3,3'-dimethyl-biphenyl 4,4'-diazide-3,3' -dichloro-biphenyl 4,4'-diazidebenzol acetylacetone 4,4'-diazide-3, 3'-dimethoxyl-biphenyl 4,4'-diazide diphenylmethane 4,4'-diazide diphenyl sulfone 2,6-di-(4'-azidebenzal)-cyclohexanone 4,4'-diazidebenzalacetone-2, 2'-disulfic acid sodium salt 4,4'-diazide stylbene-2, 2' disulfic acid sodium salt azidopyrenes, such as, 1 -azido-pyrene, 6-nitro-1 -azidopyrene, 1 6-diazidopyrene, 1 ,8-diazido-pyrene, 1 - propionyl-6-azido-pyrene, 1 -acetyl-6-azidopyrene, 1 -a-butyrvl-6-azidopyrene, 1 -n-propionyl-8-bromo-6- azidopyrene; and 8-n-propionyl-1, 6-diazidopyrne; and the aromatic diazo-oxide compounds, for example, benzoquinone diazides, naphthoquinone diazides. Also included are those photosensitive diazo composi tions listed in Light Sensitive Systems, Jaromir Kosar, John Wiley and Sons, New York, 1965.

These light-sensitive diazo substances may be combined with a binder resin such as, a) polymers, copolymers, terpolymers, etc., graft copolymers block copolymers, etc., prepared from one or more of the following monomers: Ethylene Propylene 1 -Butene Isobutylene 1-Pentene Il-Hexene 1-Heptene 1-Octene 1-Decene 1-Dodecene a cr Olefins (C11-C18) Butadiene Isoprene 1 ,3-pentadiene Chloroprene 2,3 Dichloro-1,3 Butadiene Dipentene Styrene a Methyl Styrene t-Butyl Styrene 4 Methyl pentyl styrene Divinyl benzene Cyclopentene Cyclohexene Cycloheptene Cyclooctene CycloNonene 4-Methyl Cyclopentene 4-Ethyl Cyclopentene 4Pentyl Cyclopentene 4-Hexyl Cyclodecene Cyclopentadiene 1,3 Cyclohexadiene 1,3,5, Cyclooctatriene 1,3,5 Cyclododecatriene 3-allyl indene ss-piene A3-Carene Methyl acrylate Ethyl acrylate n-Butyl acrylate Isobutyl acrylate 5-Butyl acrylate 2-Methyl butyl acrylate Methyl pentyl acrylate Methyl pentyl acrylate n-Hexyl Acrylate n-Heptyl Acrylate 2-Ethylhexyl acrylate n-Octyl acrylate n-Nonyl acrylate n-Decyl acrylate n-Undecyl acrylate Lauryl acrylate 6-Methoxy acrylate Hydroxyethyl acrylate Hydroxypropyl acrylate Methoxy butyl acrylate Butanediol monoacrylate Ethylene glycol monoacrylate Diethylene glycol triacrylate Trimethylolpropane triacrylate Tetraethylene glycol diacrylate Tetraethylene glycol di(chloroacrylate) 3-Chlorl-2-hydroxypropyl acrylate 2-Cyanoethyl acrylate Glycidyl acrylate Methyl methacrylate n-Butyl methacrylate t-Butyl methacrylate n-Hexyl methacrylate 2-Ethylhexyl methacrylate n-Nonyl methacrylate n-Decyl methacrylate n-Dodecyl methacryhlate 1-Chlorodecyl methacrylate Hydroxypropyl methacrylate Diethylene glycol dimethacrylate Triethylene glycol dimethacrylate Tetraethylene glycol dimethacrylate Trimethylol propane trimethacrylate Dipropylene glycol dimethacrylate Di(pentamethylene glycol) dimethacrylate Ethylene glycol dimethyl methacrylate 2-Cyanoethyl methacrylate Dimethylamino ethyl methacrylate Glycidyl methacrylate Trimethoxysilylpropyl methacrylate Acrylic acid Methacrylic acid Crotonic acid Fumaric acid Succinic Anhydride Itaconic acid Maleic Anhydride Methylene Glutaric acid n-t-C12 Maleamic acid Vinyl acetate Vinyl chloride Vinylidene chloride Vinyl benzyl alcohol Sodium vinyl sulfonate Methyl vinyl ether Ethyl vinyl ether Isobutyl vinyl ether Acrylonitrile Methacrylonitrile Methylene glutaro nitrile ss-Propiolactone N-vinyl pyrrolidone N-vinyl caprolactam N-vinyl imidazole Acrylamide Methacrylamide N-t-Butyl acrylamide N-Octyl acrylamide Diacetone acrylamide N-Methylol acrylamide N-n-Butoxymethyl methacrylamide N-Methylol methacrylamide Trimethylamine methacrylimide Triethylamine methacrylimide Tributylamine methacrylimide 3-(2-acryloxyethyl dimethylammonium) propionate betaine 2-(2-Methacryloxyethyl dimethylammonium) propionate betaine 3-(2-Acryloxyethyl dimethylammonium) sulfonate betaine 1,1-Dimethyl-1(2-dryroxypropylamine) 4-isopropenyl benzimide Trimethylamine 4-isopropenyl benzimide Trimethylamine 4-isopropenyl benzimide Trimethyl amine 4-vinyl benzimide N-(2-Aminoethyl) aziridine N-(2-Cyanoethyl) aziridine N-(2-Hydroxyethyl) aziridine Acrolein Diketene Dibutyl fumarate Ethyl acid maleate Dioctyl maleate Methyl hydrogen fumarate Acrylic acid 2-isocyanate ester Acrylol malonic acid diethyl ester Phenyi allyl alcohol a-Propane sulfone Allyl glycidyl ether 3-Methacryloxypropyl tromethoxysilane b) Natural and synthetic polymers and elastomers such as: Natural rubber Gelatin Cellulose acetate butyrate Polyamides Polyterpene resins Extract acid polyepoxide resins Silicone resins Chlorinated rubber Ethyl cellulose Polyvinyl alcohol Phenol4ormaldehyde resins Polyurethane resins Isocyanate cross linked polyester resins Hydroxy terminated polysiloxanes c) Polymers and elastomers listed above which have been subjected to various chemical modifications such as hydroxylation, carboxylation, thiolation, sulfonation and the like.

Optionally, additives may be incorporated into this layer such as fillers, for example, fine silica to modify delamination speed; ultraviolet absorbers, such as, G.A.F. Uvinul M40, to control exposure speed, plasticizers such as, dioctyl phthalate and castor oil to lower melting points and colorants such as Rose Bengal, Rhodamin B and methylene blue as well as al such suitable colorants as set forth in the Color Index; and stabilizers such as orgnic acids, for example, phosphoric or citric acid, and inorganic acids such as, zinc chloride, other stabilizers include thiourea.

These ingredients may be. blended with a solvent system which comprises up to about 98% of the total composition. The non solvent ingredients may be present in the following percentages by weight: diazo composition from about 50% to 100%, binder resin up to 50%, fillers up to 10%, ultraviolet absorbers up to 5%, colorants up to 5% and stailizers up to 10%.

The photopolyrnerizable layer may include any material which is capable of being photohardened, photopolymerized or photocrosslinked, and is preferably comprised of, based on weight of solids: I. From about 25% to 100% light sensitive composition comprising (i) up to 10% photoinitiator; (ii) at least 90% material capable of hardening, crosslinking, or polymerizing upon being blended with said photoinitiator and being exposed to ultraviolet radiation; and II. Up to 75% of materials selected from the group consisting of binding resins, fillers and colorants as heretofore mentioned is suitable for the diazonium layer.

Such photopolymerizable materials are generally ethylenically unsaturated monomes and oligomers capable of forming a high molecular weight polymer upon being blended with a photoinitiator and being exposed to ultraviolet radiation. Such photopolymer systems per se are well known in the art and are not a point of novelty here.

These photopolymerizable materials may be composed of any of those materials previously listed as available as binding resins, also those photopolymers and photoinitiators enumerated in U.S. Patents No's 2,760,863; 3,060,024, and 3,060,025 and in the publication, Light Sensitive Systems by Jaromir Kosar, J.

Wiley Sons, New York, 1965. Optionally this photopolymer layer may contain any coloring agentwhich includes all those listed in the Color Index which are substantially UV absorbing. The photopolymer layer may also optionally contain other additives such as a dispersant, i.e. cobalt naphthenate or iron naphthenate. These ingredients may optionally be mixed in a solvent system wherein the solvent constituents comprise up to 98% of the total composition.

Non-limiting examples of suitable photoinitiators include Michler's ketone, benzophenone, benzoin, benzoin methyl ether, diphenyl disulfide, benzii and the like.

The top covering layer may comprise any flexible, transparent material, some examples of which has been mentioned hereinbefore as suitable for use as the bottom layer.

Typically the base layer has a thickness in excess of from about 0.25 mil. and preferably at least 4 mils. The diazo and photopolymer layers have a coating weight of from about 1 mg/sq. ft. to about 10 g/sq.ft. and the top layer has a thickness of from about 0.25 to about 4 mils.

The construction may be erected by any convenient means such as applicator coating fluid state compositions with subsequent drying or pressure lamination of solids.

Characteristically, the exposure mask is held in intimate contact with the upper surface of the top layer by means of a vacuum frame as is well known in the part. Exposure energy may then be supplied by the introduction of ultraviolet, actinic, or xenon flash irradiation for from about 1/1000 second to about lo minutes. It is also within the contemplation of the instant invention that energy may also selectively be applied from a laser energy source.

Optionally, after peel apart, the reproduction comprises of the unexposed photosensitige layers may be subsequently exposed to ultraviolet radiation of various uses.

The optimum combination of ingredients, proportions and application conditions may be selected by the skilled worker depending upon the specific results sought to be achieved.

The following specific examples illustrate the invention but it is to be understood that variations and modifications can be made therein without departing from the spirit and scope of the invention.

Example 1 A sheet of lithographic grade 3003 aluminium was first grained using wet pumice and a rotating brush.

The plate was then treated in a warm 2% sodium silicate solution and water rinsed.

A photopolymer having the following composition was applied to this sheet at a 300 mg/sq. ft. coating weight.

Pentaerythritol triacrylate 3g Versamid 520 (General Mills) 1.5 g Michler's ketone 0.1 g Benzophenone 0.1 g Isopropyl alcohol 20 ml Toluene 20 ml After air drying, a 0.5 mil polyester film was laminated on this photopolymer layer.

After exposure to an ultraviolet light source through the polyester film, and subsequent peel apart of the aluminum and polyester sheets a lithographic printing plate was produced on the aluminum plate. This prepared plate was then run on an off-set printing press and after 4,000 impressions some portion of the image areas lifted from the base metal thereby rendering the plate subsequently unuseable.

Another sample of a thusly producted plate was subjected to accelerated aging ina 60 degrees C. oven for 4 days. Another kind of failure showed up in the form of background toning, thus rendering the plate unuseable.

Example 2 The following diazonium layer was coated between the base sheet of aluminum and photopolymer layers of example 1 with the same exposure and peel apart treatment: The condensation product of, 4-diazo-diphenylamine bisulfate and formaldehyde 4 g Phosphoric acid 0.29 Waterto make II.

No image deterioration was observed after 20,000 impressions and under similar accelerated aging conditions no background toning was noticed.

Example 3 Lithographic grade aluminum 1100 was degreased and etched lightly with 1.5% HCI using alternate current for 20 minutes, desmutted and silicated with a 2% sodium silicate solution. The plate was coated first with a solution consisting of: Wipe-on Diazo (Polychrome Corp. #910) 3 9 Citric Acid 1.5 g Watertomake 11.

Then overcoated with a photopolymer composition consisting of, DV 53 (Polychrome) 209 Epocryl 322 resin (Shell Chemical) 159 Irgacure (Ciba-Geigy) 29 Toluene 300 ml.

to a coating weight of 350 mg/sq. ft.

After air drying the coating, a 0.5 mil. polyester film was laminated to the photopolymer under the pressure of nip rollers.

Exposure to UV light and subsequent peel apart development produced a printing plate capable of printing over 50,000 acceptable copies with a clear background both immediately after production and after a one year accelerated life testing.

Example 4 An aluminum sheet (grade 3003) was wet pumice grained with a rotating brush and subsequently anodized in a 15% sulfuric acid both to give a 150 mg/sq. ft. anodic coating weight.

This surface was then treated with mild sodium silicate solution, rinsed and dried. A 1.5% aqueous solution of a low molecular weight condensation product between Diazo S (American Hoechst) and formaldehyde together with 2% each solid weight of citric acid and thiourea was applied by a whirler coating method. After air drying the surface the following composition was applied at a 200 mg/sq. ft. coating weight: DV 53 (Polychrome Corp.) 109 AT 64 (Rohm & Haas Co.) 10g Michler's ketone 0.1 g Benzophenone 0.1 g Toluene to make > 150 ml.

A 0.5 mil. polyester film with a matte surface on one side was laminated onto the surface of the plate with smooth side of the film in contact with the photopolymer coating. A brief exposure to a UV light source and peeling of the matte cover sheet produced a printing plate with strong image and clear background.

Example 5 A A lithographic grade aluminum (3003) was degreased, etched in sodium hydroxide solution and anodized in 20% sulfuric acid to give 250 mg/sq. ft. anodic coating weight. The surface of the plate was given a coating of diazo resin coating solution used in Example 1.

The plate was then coated with the following composition: Halowax (Koppers Corp.) 5g DV 53 (Polychrome Corp.) 5g Michler's ketone 0.5g Benzophenone 0.59 Toluene to make 100 ml.

to give approximate coating weight of 250 mg/sq. ft.

A 0.5 mil. polyester sheet was then laminated under heat (250 degrees F.) and pressure on a laminator (by Rhexham Corp.) to the photopolymer layer.

Exposure and peel apart development produced a lithographic printing plate with good length or run and clear background.

Example 6 Example 4 was repeated with the following photopolymer composition: n-(lsobutoxymethyl) acrylamide (Amer. Cyanamid) 10 9 Versamid 520 (General Mills) 10g Michler's ketone 1g Benzophenone 1g Tolueneto make 200 ml.

with likewise excellent results.

Claims (6)

CLAIMS 1. A multi-layered sheet construction capable of reproducing both positive and negative forms of a photographic transparency image which comprises successive adherent layers comprised of: (a) A flexible top support capable of transmitting radient ultraviolet energy therethrough and having adhered to one surface thereof; (b) Afirst photosensitive composition layer which comprises,

1. From about 25% to 100% light sensitive composition comprising (i) up to 10% of a photoinitiator(ii) at lease 90% of a material capable of hardening, crosslinking or polymerizing upon being blended with said photoinitiator and being exposed to ultraviolet radiation; and II.Up to 75% of materials selected from binding resins, fillers and colorants; said first photosensitive composition layer having adhered thereto; (c) A second photosensitive composition layer which comprises (i) a major amount of a light-sensitive, negative working, water soluble diazonium composition which may contain (ii) minor amounts of additives selected from resinous materials and stabilizers; said second photosensitive composition being rendered substantially insoluble upon exposure to ultraviolet radiation, said second photosensitive layer having adhered thereto; (d) A hydrophilic bottom support having a substantially regular surface.

2. A construction as claimed in claim 1 wherein the bottom support is comprised of aluminium or the alloys thereof.

3. A construction as claimed in claim 1 or 2, wherein the diazonium composition is the condensation product of paradiazo diphenyl amine and formaldehyde.

4. A method of producing both negative and positive forms of a photographic transparency image by a single exposure which comprises exposing a multilayered construction as claimed in claim 1,2 or 3, to an ultraviolet light source through a photographic transparency from the direction of said top support, and subsequently peeling apart said top and said bottom supports, whereby said first and said second photosensitive composition layers are subjected to dissociative imagewise separating shearing froces along the interfaces between their exposed and unexposed areas to produce a negative reproduction of the photographic transparency image in the form of said bottom support, the exposed, negatively imagewise separated -diazonium layer adhering to said bottom support and the exposed negatively imagewise separated photopolymer material adhering to said exposed diazonium material and a positive reproduction of said photographic transparency image in the form of said top support, the unexposed, positively imagewise searated photopolymer layer adhering to said top support and the unexposed, positively imagewise separated diazonium materiaSadhering to the unexposed photopolymer material.

5. A construction as claimed in claim 1, substantially as hereinbefore described in any one of the Examples.

6. A method as claimed in claim 4 substantially as hereinbefore described in any one of the Examples.