GB2030310A - Light-sensitive Imaging Material and Process for Imaging Therewith - Google Patents

Abstract

The imaging material has an imaging layer comprising a plastics binder, e.g. cellulose acetate phthalate, and a dye or pigment, e.g. carbon black particles, and an overlying light-sensitive layer comprising a photosensitive component which is rendered either insoluble, e.g. by cross-linking, or soluble in the regions struck by light during imagewise exposure. The exposed material is treated with a solvent, e.g. an aqueous alkaline solution, which dissolves the parts of the light-sensitive layer remaining soluble after exposure and hence also the underlying parts of the imaging layer. The material is suitable for the production of half-tone masters for printing plates and labelling assemblies.

Description

SPECIFICATION Light-sensitive Imaging Material and Process for Imaging therewith The present invention relates to a light-sensitive imaging material and a process for imaging therewith.

A number of light-sensitive imaging materials other than those which include the familiar gelatino-silver halide photographic emulsion have been proposed in the art.

United States patent specification 4 053 313 describes a material which is suitable for colour proofing and comprises a solvent-processable photosensitive layer applied over a non-photosensitive tonable layer. The photosensitive layer may be initially solvent-soluble and rendered insoluble in those areas struck by light during imagewise light exposure. Conversely, the photosensitive layer may be initially insoluble and rendered soluble in those areas struck by light. After exposure to light, the material is washed with a solvent to remove the areas of the photosensitive layer which remain soluble. The areas of the tonable layer which are revealed by the washing operation are toned by treatment with a coloured toner.

Japanese patent application 51 056631 describes a material comprising a dyed layer and a superimposed photoresist layer which can be imaged by exposure to light. The exposed material is treated in a developer solution to partially remove the photoresist layer and then in a solution of a sulphite salt to bleach the dye in the regions of the dyed layer revealed by the dissolution of the photoresist layer.

The present invention relates to a process for recording an image upon a light-sensitive imaging material, said light-sensitive imaging material comprising a self-supporting sheet or film, an imaging layer comprising a pigment or dye distributed throughout a plastics binder and applied to said selfsupporting sheet or film and a light-sensitive layer comprising a photosensitive component applied to the side of the imaging layer remote from the self-supporting sheet or film, said process comprising exposing the light-sensitive layer imagewise to light, the light-struck regions of the light-sensitive layer being rendered either insoluble or soluble in a solvent applied thereto by the action of light upon the photosensitive component therein, the remaining regions of the light-sensitive layer being correspondingly either soluble or insoluble in said solvent, applying said solvent to the light-sensitive layer to dissolve the soluble regions therein, and dissolving by means of the same or a different solvent the regions of the imaging layer revealed by the dissolution of the soluble regions of the light-sensitive layer.

The photosensitive component of the light-sensitive layer and the underlying regions of the imaging layer are preferably dissolved in a single operation and are most preferably soluble in a common solvent. If the soluble components of the layers are soluble in different solvents, dissolution of both layers may be achieved in a single operation by using a mixture of the appropriate solvents, or alternatively, the layers may be dissolved separately by sequential treatment with suitable solvents.

References herein to the solubility of the components of the imaging material in solvents are intended to include components which are inherently soluble or dispersible in the solvent or become soluble or dispersible therein by conversion into soluble or dispersible compounds after reaction with the solvent or an ingredient of the solvent.

According to another aspect of the present invention a light-sensitive imaging material suitable for use in the above process comprises a self-supporting sheet or film, an imaging layer applied thereto and a light-sensitive layer applied to the side of the imaging layer remote from the self-supporting sheet or film, said imaging layer comprising a pigment or dye distributed throughout a plastics binder and said light-sensitive layer comprising a photosensitive component which can be rendered either insoluble or soluble in a solvent by the action of light incident thereupon, said plastics binder of the imaging layer being soluble in the same or a different solvent.

Images are recorded in the light-sensitive imaging material according to the present invention by the action of a solvent or solvents upon the light-sensitive and imaging layers. The imagewise exposure of the light-sensitive layer renders the light-struck regions of the photosensitive component therein either insoluble or soluble in the solvent subsequently applied thereto with the result that selected parts determined by the imagewise exposure to light of the light-sensitive layer are dissolved in the solvent whilst others are not. This selective dissolution is achieved by a treatment which consists essentially of subjecting the light-sensitive layer to the action of the solvent.It is not necessary to subject the light-exposed light-sensitive layer to any conditioning treatment or reagent which might modify the physical or chemical nature of the photosensitive component prior to treatment with the solvent. The undissolved parts of the light-sensitive layer, which correspond to the image to be recorded, serve as an insoluble mask for the solvent treatment of the underlying imaging layer, so that the imaging layer is only dissolved in the unmasked parts. Of course, if different solvents are used to treat the light-sensitive layer and the imaging layer, the undissolved masking parts of the light-sensitive layer must be insoluble in the solvent employed for treating the imaging layer.It will be appreciated that an excessively prolonged immersion in the solvent for the imaging layer may enable the solvent to penetrate laterally through the imaging layer and beneath the masking regions of the light-sensitive layer with the result that the recorded image may become distorted. Prolonged immersion in the solvent should therefore preferably be avoided. Optimum immersion times can be determined by simple experiment.

The images obtained according to this invention exhibit excellent resolution and high contrast.

The plastics binder of the imaging layer is preferably insoluble in water alone but soluble in aqueous alkaline solutions of pH greater than approximately 8.0 and also preferably soluble in suitable organic solvents (e.g. esters, ketones) so that the imaging layer may be applied to the sheet or film as a solution in the organic solvent. Polymers suitable for use as the plastics binder may contain, for example, free carboxyl groups in their molecule. A preferred polymer, suitable as the plastics binder of the imaging layer, comprises an ester of cellulose with a polybasic carboxylic acid or a mixed ester of cellulose derived from at least one polybasic carboxylic acid and another carboxylic acid, the resulting cellulose ester containing free carboxylic groups. Suitable polybasic carboxylic acids are phthalic acid, succinic acid, citric acid and tartaric acid.Mixed esters are particularly preferred and especially cellulose acetate phthalate, cellulose acetate succinate, cellulose acetate citrate and cellulose acetate tartarate. Such cellulose esters may be dissolved in aqueous solvents by virtue of the free carboxyl group contained in their structure. Thus, the cellulose esters which are substantially insoluble in water can be treated with alkaline aqueous solvents and rendered soluble by conversion into soluble compounds by reaction of the free carboxyl groups. Suitable alkaline aqueous solvents include aqueous solutions of hydroxides such as ammonium sodium or potassium, sodium silicate, sodium bicarbonate, sodium carbonate, trisodium phosphate, sodium sesquicarbonate, sodium borate (borax), ethanolamine, diethanolamine, tris(hydroxymethyl) aminomethane, etc.Additives such as buffering agents and surface active agents may be added to the alkaline aqueous solvent to maintain a constant pH and to assist in the dissolution of the imaging layer.

Any suitable pigment or dye may be included in the imaging layer provided it is not reactive with the plastics binder of the imaging layer, is not reactive with the solvent or solvents used to treat the imaging layer, and is not reactive with the components of the light-sensitive layer. The preferred pigment consists of carbon black particles which have an average arithmetical mean particle size of less than 1 ym, and are preferably employed at a concentration sufficient to produce a suitable visual or actinic density in an imaging layer having a thickness in the range 0.1 ym to 6 ,um. Thicknesses in the range 2 to 3 tjm are preferred in one preferred embodiment of the invention for the formation of half-tone images for lithographic or screen printing plates whilst thicknesses less than 1 ym are suitable in another preferred embodiment for labelling assemblies.

Depending upon the chemical nature of the photosensitive component in the light-sensitive layer, the parts of the photosensitive component which are either exposed or not exposed to light are dissolvable by the action of the solvent applied thereto, the remaining insoluble parts serving as the mask for the solvent treatment of the imaging layer.

Photosensitive components which are rendered insoluble in the treatment solvent for the lightsensitive layer may comprise materials which are photocrosslinkable, photopolymerisable or photodimerisable. Examples of suitable materials include diazonium salts and polymeric diazonium compounds which are formed by the condensation of an aldehyde, e.g. formaldehyde, with a diazonium salt, e.g. p-diazo-diphenylamine zinc chloride double salt, and their mixtures with hydrophilic polymers, e.g. polyvinyl alcohol; azides, e.g. p-phenylenebisazide, and polymeric azides, e.g. polyvinyl azide, and their mixtures with hydrophilic polymers; chemicals and polymers containing ethylenic unsaturation which are capable of polymerisation by means of photochemically generated free radicals, e.g.

acrylamide, N,N'-methylene-bis-acrylamide, ethylene glycol dimethacrylate, acrylated polyurethanes; polyvinyl cinnamate; polyvinyl phosphonic mono esters of chalkones; styrene/maleic anhydride copolymers containing cinnamoyl or chalkone groups.

Photosensitive components which are rendered soluble in the treatment solvent upon exposure to light may be generally termed photosolubilisable. Examples of such materials are 2-diazonhenols (quinone diazides), e.g. 2-diazo-1 -naphthoquinone; 3-diazo-oxindoles, e.g. 1 -methyl-3-diazo-oxindole; diazomethane derivatives, e.g. dibenzenesulphonyldiazomethane. The photosolubilisable components may be used in admixture with suitable polymeric components, e.g. novolak phenol-formaldehyde resins, or the active photosensitive group combined into a polymeric structure, e.g. 2-diazophenolformaldehyde resins. Polymers which are depolymerised by the action of light may also be used.

The light-sensitive layer may also contain agents which impart increased resistance to alkaline solvents. Such agents are not light-sensitive, and may comprise cross-linking agents such as ureaformaldehyde resins, melamine-formaldehyde resins, hexamethoxymethylmelamines, glyoxal and dialdehydes or polymeric materials such as polymers and copolymers of vinyl acetate.

The self-supporting sheet or film of the light-sensitive imaging material may be opaque or transparent and may comprise metal, paper, cardboard or preferably a plastics materials, such as cellulose esters, e.g. cellulose acetate, or thermoplastics, such as polystyrene, polyamides, polymers and copolymers of vinyl chloride, polycarbonate, polymers and copolymers of olefines, e.g.

polyethylene and polypropylene, polysulphones and linear polyesters which may be obtained by condensing one or more dicarboxylic acids or their lower alkyl diesters, e.g. terephthalic acid, isophthalic, phthalic, 2,5-, 2,6- and 2,7-naphthalene dicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, diphenyl dicarboxylic acid, and hexahydroterephthalic acid or bis-p-carboxyl phenoxy ethane, optionally with a monocarboxylic acid, such as pivalic acid, with one or more glycols, e.g. ethylene glycol, 1,3-propanedioi, 1,4-butanediol, neopentyl glycol and 1,4- cyclohexanedimethanol. Biaxially oriented and heat-set films of polyethylene terephthalate are particularly useful according to this invention.

If desired, the plastics films or sheets may be coloured to provide a decorative effect, e.g. for labelling, by the inclusion of a dye or pigment or may be opacified by the inclusion of suitable particulate fillers.

If desired, the surface of a plastics sheet or film may be pretreated and/or coated with an adhesion-promoting layer prior to the application of the imaging layer. Polyethylene terephthalate film sheets or films may be pretreated by coating with solutions of materials having a solvent or swelling action on the film such as halogenated phenols in common organic solvents, e.g. solutions of p-chlorom-cresol, 2,4-dichlorophenol, 2,4,6-or 2,4,5-trichlorophenol or 4-chlororesorcinol or a mixture of such materials in acetone or methanol.After application of such a solution the film surface can be dried and heated at an elevated temperature for a few minutes, e.g. 2 minutes at 600C to 1 00 C. If desired, the pretreating solution may also contain an adhesion-promoting polymer such as a partially hydrolysed copolymer of vinyl chloride and vinyl acetate and/or a polymer which assists the complete dissolution of the subsequently applied imaging layer when the latter is treated with a suitable solvent after exposure to light, such a polymer normally being chosen to be the same as that used as the plastics binder in the imaging layer.

A decorative effect, e.g. in labelling assemblies, may also be obtained by applying a lightreflecting metallic layer to one surface of the self-supporting sheet or film except when the sheet or film itself is a metal. Such a metallic layer may be applied to either surface of the sheet or film and preferably to the surface other than that bearing the imaging and light-sensitive layers. Particularly attractive decorative effects are provided by applying the metallic layer to the surface of a transparent film or sheet other than the surface bearing the imaging and light-sensitive layers especially if the transparent film is coloured, e.g. by the inclusion of a dye therein.

Such a metallic layer may be applied to the sheet or film surface by any suitable means such as vapour deposition, sputtering, electron beam deposition, ion plating, electro-plating or electroless plating. Vacuum deposition is especially useful for the application of metal layers to thermoplastics sheets or films. Suitable metals include zinc, aluminium and copper. Aluminium layers having a thickness in the range represented by a surface resistivity in the range 1.5 to 5 ohms per square (approximately 200 to 500A) are particularly effective.

A decorative effect, also suitable for labelling assemblies, may alternatively be obtained by interposing a pigmented or dyed layer, of thickness preferably 1 to 10 um, between the imaging layer and the self-supporting sheet or film or by applying a pigmented or dyed layer to the surface of the sheet or film other than that bearing the imaging and light-sensitive layers. Pigments suitable for inclusion in such a layer may include metal pigments.The pigmented or dyed layer may include a plastics medium which may comprise nitroceilulose, cellulose esters such as cellulose acetate, cellulose acetate butyrate and cellulose acetate propionate, copolymers of vinyl chloride and vinyl acetate or copolymers of alkyl esters of methacrylic acid such as methyl and n-butyl methacrylates, styrene/acrylonitrile copolymers, polyamides and any other soluble or dispersible resins conventionally employed in paints and printing inks.

The pigments and dyes included in the pigmented or dyed layer are present solely to provide a white or coloured effect by the selective absorption of certain wavelengths of incident light employed to view the material. The total luminous transmittance of the pigmented or dyed layer preferably does not exceed 20% and may be as low as zero %. Pigments may be included in the pigmented or dyed layer in an amount in the range 5 to 30% by weight based on the weight of the plastics medium and may be chosen from carbon black or those identified by the Colour Index names or numbers (the commercially available pigments are named in parenthesis) 74160 (Polymon Blue LBS), 1 5850 (Rubine Toner 4BS), Pigment Yellow 34 (Pure Lemon Chrome L6GS), 69800 (Paliogen Blue RR) and Azoic Blue 7 (Printing Blue R).Dyes may be included in the layer in an amount in the range 5 to 30% by weight based on the weight of the polymeric binder and may be chosen from those identified by the Colour Index names or numbers (the commercially available dyes are named in parenthesis) Solvent Blue 70 (Neozapon Blue FLE), Solvent Red 60 (Neozapon Fire Red BL), 12716 (Neozapon Red GE), Solvent Blue 49 (Orasol Blue BLN), Solvent Blue 53 (Orasol Navy Blue 2RB), Solvent Blue 67 (Orasol Brilliant Blue GN), 12055 (Lacquer Orange VG), Solvent Blue 65 (Waxoline Blue 2RS), 61 551 (Waxoline Blue APS), 60505 (Waxoline Red MPS), 47000 (Waxoline Yellow TS) and 5041 5 (Methasol Nigrosine ENS).

When the pigmented or dyed layer is derived from a printing ink, suitable inks include those available commercially as 'Impac Microfilm' Black, Pale Blue, Red, Green, Orange, Pink and White (Fishburn Printing Ink Co Ltd), 'Propalin Blue' and 'Propalin Red' (both Gothams) and 'Silver Gravure Ink' (L6rrileux and Bolton Limited). Paints suitable for the formation of the pigmented or dyed layer include the range of 'Dulux' emulsion paints (Imperial Chemical Industries Limited) especially black, blue red and green hues.

It will be appreciated that a dye or pigment included in the sheet or film or in a layer applied thereto for decorative effect should contrast with the image-forming dye or pigment in the imaging layer and should be different therefrom.

Any metallic, pigmented or dyed layer applied to the surface of the self-supporting sheet or film, especially layers on the side of the sheet or film remote from the imaging layer, for the purposes of providing a contrasting colour or decorative effect, should be unaffected by the solvent or solvents used to develop the image in the imaging layer. If necessary, such layers may be further protected by an additional surface coating of a material impervious to the solvent or solvents used to develop the image.

The imaging material and process of the invention are especially useful, as mentioned above, for the production of half-tone images which are suitable for use as masters in the production of lithographic or screen printing plates. Generally, such assemblies do not require the presence of a metallic, pigmented or dyed decorative layer.

Another preferred application of the imaging material and process of the invention resides, also as mentioned above, in the production of labelling assemblies wherein the labelling design or data is formed as a pigment or dye image in the imaging layer and is preferably provided with a contrasting background by the various means described above for obtaining a decorative effect, e.g. by pigmenting, dyeing or opacifying the sheet or film, by a metallic, pigmented or dyed layer. Such labelling assemblies preferably also include a self-adhesive or pressure-sensitive adhesive layer applied to the side of the assembly remote from the imaging layer to enable the assemblies to be mounted upon a receptive surface.Resins suitable for the formation of such an adhesive layer are described in "Handbook of Adhesives" edited by I Skeist, Rheinhold Pub Corp, New York, 1962 and may include copolymers based on aliphatic (4-12 carbon atoms) acrylate esters, e.g. iso-octyl acrylate copolymers, natural and/or synthetic rubber-based copolymers blended with a "tackifying component such as a polyterpene and styrene/butadiene rubbers".

If a pigmented or dyed layer is included in the labelling assembly and located on the side thereof other than that bearing the imaging and light-sensitive layers, a resin which confers self-adhesive or pressure-sensitive adhesive properties may be included in such a layer as an alternative means of providing adhesive properties for mounting the labels upon receptive substrates.

Alternative uses for the process and imaging material of the present invention include: 1 dry transfer materials wherein the adhesion of the imaging layer to the sheet or film is weak and a pressure-sensitive transfer adhesive layer is applied over the light-sensitive layer; 2 graphic arts duplicating film; 3 drawing office master films which can be corrected or amended wherein the sheet or film has a matt pencil/ink receptive surface provided by the incorporation therein of a particulate additive or coating with a matting lacquer; and 4 proofing media wherein the sheet or film is a white opaque material.

Preferred embodiments of the invention are described with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional view of a preferred light-sensitive imaging material during imagewise exposure to light; Figure 2 is a cross-sectional view of a half-tone master for the production of lithographic printing plates produced by the light-exposure and solvent treatment of the imaging material illustrated in Figure 1; and Figure 3 is a cross-sectional view of a light-sensitive imaging material suitable for the production of a labelling assembly.

Figure 1 illustrates a light-sensitive imaging material 1 consisting of a conventional transparent biaxially oriented and heat-set polyethylene terephthalate film 2 of thickness 100 ym carrying an adhesion-promoting layer 3, an imaging layer 4 and a light-sensitive layer 5.

The adhesion-promoting layer 3 was applied from a solution containing the following ingredients and dried to a thickness of 0.1 ym: Cellulose acetate phthalate (commercially available as 'Eastman' C.A.P., from Eastman Chemical Products Inc,)* 0.25 g p-chloro-m-cresol 5.00 9 2-methoxyethanol 4.00 g Methyl alcohol 36.00 ml Methyl ethyl ketone 60.00 ml *manufacturers' quoted analysis: combined phthalyl as C8H503 30.0 to 36.0% by weight free acid as C8H604 6.0% by weight maximum combined acetyl as CH3Co 19.0 to 23.5% by weight The imaging layer 4 was applied from a dispersion prepared by mixing the following ingredients in a ball-mill for 48 hours:: Cellulose acetate phthalate (commercially available as 'Eastman' C.A.P., from Eastman Chemical Products Inc, manufacturers' quoted analysis as above) 12.09 Carbon black pigment (commercially available as 'Special Black' 5, having an average arithmetical mean particle size of 20 nm, from Degussa AG) 12.09 2-methoxyethanol 36.0 9 Methyl alcohol 15.or Methyl ethyl ketone 25.09 25 parts by weight of the resulting dispersion were diluted by the addition of 50 parts by weight methyl ethyl ketone and 25 parts by weight methyl alcohol. The resulting diluted dispersion was filtered through a filter medium of pore size 2 ,um and applied to the adhesion-promoting layer 3 and dried to a thickness of approximately 2 ,um.

The light-sensitive layer was applied from a solution containing the following ingredients and dried to a thickness of between 1 and 2 ym: Condensation product of formaldehyde and p-diazo-diphenylamine zinc chloride double salt (commercially available as 'Fi-line Sensitiser' ZAL from ABM Chemicals Ltd.) 0.66 9 Polyvinyl alcohol (available commercially as 'Poval' polyvinyl alcohol 1 10 from Kurashiki Rayon Co Ltd)# 3.0 9 Hexamethoxymethylmelamine (available commercially as 'Cymel' 300 from Cyanamide International) 0.02 9 Methyl alcohol 20.0 ml Methyl ethyl ketone 10.0 ml Water 70.0 ml #manufacturers' quoted analysis:: acetyl content, i.e. combined acetic acid 1.6 to 2.8% by weight viscosity, 4% aqueous solution at 200C 9.0 to 11.0 centipoise An image was recorded upon the light-sensitive imaging material 1 by imagewise exposure to light through a photographic negative 6 comprising a transparent film support 7 and a photographic emulsion layer 8 comprising light-absorbing silver imaged regions 9. Although the light-sensitive imaging material 1 and the photographic negative 6 are not so illustrated in Figure 1 (so as to facilitate illustration), in practice they were held in firm contact during imaging. Exposure was effected by means of ultra-violet light incident in the direction of the arrow A from a 2 kw ultra-violet light source located at a distance of 1 m above the surface of the photographic emulsion layer 8 for a duration of 4 minutes.

The exposed film was treated in a solvent consisting of a 0.5% by weight aqueous solution of sodium silicate and finally washed in water. Figure 2 illustrates the resulting imaged material.

Ultra-violet light incident through the transmitting areas 10 of the photographic negative 6 serves to form a cross-linked structure in the corresponding underlying regions of the light-sensitive layer 5 thereby rendering the regions insoluble in the solvent. Such insoluble parts function as a mask, as indicated by the reference numeral 1 1 in Figure 2, to prevent the imaging layer 4 being dissolved by the solvent. However, those parts of the light-sensitive layer 5 which are not exposed to light, i.e.

those parts underlying the silver imaged regions 9 of the photographic negative 6, do not cross-link and are therefore dissolved by the applied solvent with the result that the corresponding parts of the imaging layer 4 are dissolved by the solvent.

The image recorded on the light-sensitive imaging material, in the form of the carbon black particles of the imaging layer 4 remaining on the surface of the film 2 in the light-struck parts had excellent resolution and high contrast and was suitable for use as a half-tone master in the production of lithographic printing plates.

In a modification of the material illustrated in Figures 1 and 2, the transparent film 2 is replaced by a white pigmented and opaque biaxially oriented and heat-set polyethylene terephthalate film having a thickness of about 100 ym. The resulting product is suitable for use as a labelling assembly.

Such 'an assembly preferably has an imaging layer 4 having an esitmated thickness of approximately 0.2 #m and a reflection density exceeding 1.0, measured using a 'Macbeth' (registered trade mark) Reflection Densitometer model RD514 and a 'Wratten' (registered trade mark) 106 filter. If desired, a pressure-sensitive adhesive layer may be applied to the surface 12 of the film 2, as shown in Figure 2.

Figure 3 illustrates a light-sensitive imaging material 15 consisting of a conventional transparent biaxially oriented and heat-set polyethylene terephthalate film 1 6 having a thickness of 100 ym. A white pigmented layer 17 consisting of 'Impac Microfilm' white ink was applied to one surface of the film 16 and had a thickness of approximately 5 ym. An adhesion-promoting layer 3, an imaging layer 4 and a light-sensitive layer 5 were applied to the other surface of the film 1 6 and have formulations and thicknesses corresponding to the similar layers illustrated in Figure 1 with the exception that the imaging layer 4 in the material of Figure 3 had an estimated thickness of approximately 0.2 ssm and a reflection density exceeding 1.0, measured using a 'Macbeth' Reflection Densitometer model RD5 14 and a 'Wratten' 106 filter.

The material illustrated in Figure 3 was subjected to imagewise exposure to light and processing in a solvent to develop the desired image in the manner described above in relation to the material illustrated in Figures 1 and 2. The resulting product had a black image formed in the light-struck parts of the material wherein the imaging layer 4 and the carbon black particles therein were retained after processing, the image having excellent resolution and high contrast against the white background of the pigmented layer 17.

In a modification of the material illustrated in Figure 3 a pressure-sensitive adhesive layer may be applied to the exposed surface of the pigmented layer 17 and may comprise a self-curing acrylic polymer which may be applied from a composition comprising: Ingredients Quantities Self-curing acrylic polymer commerically available as 'Gelva' RA1753 (analysis: 31% by weight solids in a solvent mixture comprising by volume 55% ethyl acetate, 35% isopropanol and 10 hexane) 50 ml Ethyl acetate 50 ml and dried to a dry thickness of about 25 microns by heating at 800C for 20 seconds.

Claims (13)

Claims

1. A process for recording an image upon a light-sensitive imaging material, wherein said light-sensitive imaging material comprises a self-supporting sheet or film, an imaging layer comprising a pigment or dye distributed throughout a plastics binder and applied to said self-supporting sheet or film and a light-sensitive layer comprising a photosensitive component applied to the side of the imaging layer remote from the self-supporting sheet or film, said process comprising exposing the light-sensitive layer imagewise to light, the light-struck regions of the light-sensitive layer being rendered either insoluble or soluble in a solvent applied thereto by the action of light upon the photosensitive component therein, the remaining regions of the light-sensitive layer being correspondingly either soluble or insoluble in said solvent, applying said solvent to the lightsensitive layer to dissolve the soluble regions therein, and dissolving by means of the same or a different solvent the regions of the imaging layer revealed by the dissolution of the soluble regions of the light-sensitive layer.

2. A process according to claim 1, in which the plastics binder of the imaging layer is dissolved, after the material has been exposed to light, in an aqueous alkaline solution.

3. A process according to claim 1 or 2, in which the plastics binder of the imaging layer comprises cellulose acetate phthalate, cellulose acetate succinate, cellulose acetate citrate or cellulose acetate tartarate.

4. A process for recording an image upon a light-sensitive imaging material substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawing.

5. A process for recording an image upon a light-sensitive imaging material substantially as hereinbefore described with reference to and as illustrated in Figure 3 of the accompanying drawing.

6. A light-sensitive imaging material, which comprises a self-supporting sheet or film, an imaging layer applied thereto and a light-sensitive layer applied to the side of the imaging layer remote from the self-supporting sheet or film, said imaging layer comprising a pigment or dye distributed throughout a plastics binder and said light-sensitive layer comprising a photosensitive component which can be rendered either insoluble or soluble in a solvent by the action of light incident thereupon, said plastics binder of the imaging layer being soluble in the same or a different solvent.

7. A light-sensitive imaging material according to claim 6, in which the plastics binder of the imaging layer comprises cellulose acetate phthalate, cellulose acetate succinate, cellulose acetate citrate or cellulose acetate tartarate.

8. A light-sensitive imaging material according to claim 6 or 7, in which the self-supporting film comprises a biaxially oriented and heat-set film of polyethylene terephthalate.

9. A light-sensitive imaging material according to any of claims 6, 7 or 8, in which the selfsupporting sheet or film is dyed, pigmented, opacified, or coated with a metallic or a dyed or pigmented layer.

10. A light-sensitive imaging material according to any of claims 7 to 9 in the form of a labelling assembly.

11. A light-sensitive imaging material according to claim 10, in which a self-adhesive or pressuresensitive adhesive is applied to the side of the self-supporting sheet or film remote from the imaging layer.

12. A light-sensitive imaging material substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 of the accompanying drawing.

13. A labelling assembly substantially as hereinbefore described with reference to and as illustrated in Figure 3 of the accompanying drawing.