US3929481A

US3929481A - Etch bleaching processes for making lithographic printing plates using silver halide and/or diffusion transfer layers and a hydrophilic layer

Info

Publication number: US3929481A
Application number: US335219A
Authority: US
Inventors: Kikuo Kubotera; Eiichi Mizuki; Tadahiro Fujiwara; Nobuo Tsuji
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1972-02-25
Filing date: 1973-02-23
Publication date: 1975-12-30
Anticipated expiration: 1992-12-30
Also published as: GB1433121A; DE2309511A1; JPS4887901A; JPS561629B2

Abstract

In a plate or light-sensitive plate for making printing plates comprising a support having an oleophilic surface carrying thereon a photosensitive silver halide emulsion layer, a hydrophilic diffusion transfer image receiving layer containing physical development nuclei, or both an image receiving layer and a photosensitive silver halide emulsion layer formed on the image receiving layer, the press life of a printing plate made from the plate is effectively improved by providing between the support and the lowermost layer a hydrophilic intermediate layer of, e.g., gum arabic, a maleic anhydride-vinyl acetate copolymer or a partially saponified cellulose derivative.

Description

Kubotera et al.

ETCI-I BLEACI-IING PROCESSES FOR MAKING LITI-IOGRAPI-IIC PRINTING PLATES USING SILVER HALIDE AND/OR DIFFUSION TRANSFER LAYERS AND A HYDROPI-IILIC LAYER Inventors: Kikuo Kubotera; Eiichi Mizuki,

both of Saitama; Tadahiro Fujiwara; Nobuo Tsuji, both of Kanagawa, all of Japan Fuji Photo Film Co., Ltd., Minami-ashigara, Japan Filed: Feb. 23, 1973 Appl. No 335,219

Assignee:

Foreign Application Priority Data Feb. 25, 1972 Japan 47-19922 US. Cl. 96/29 L; 96/33 Int. Cl. G03C 5/54 Field of Search 96/29 L, 35.1, 33

References Cited UNITED STATES PATENTS 5/1968 Ormsbee 96/29 L Dec. 30, 1975 3,552,315 1/1971 Ormsbee 96/76 3,557,696 1/1971 Ho0ver...' 96/76 3,567,442 3/1971 Land 96/76 3,690,883 9/1972 Hyland 96/29 L Primary ExaminerCharles I... Bowers, Jr.

Assistant ExaminerJohn L. Goodrow Attorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT In a plate or light-sensitive plate for making printing plates comprising a support having an oleophilic surface carrying thereon a photosensitive silver halide emulsion layer, a hydrophilic diffusion transfer image receiving layer containing physical development nuclei, or both an image receiving layer and a photosensitive silver halide emulsion layer formed on the image receiving layer, the press life of a printing plate made from the plate is effectively improved by providing between the support and the lowermost layer a hydrophilic intermediate layer of, e.g., gum arabic, a maleic anhydride-vinyl acetate copolymer or a partially saponified cellulose derivative.

14' Claims, 7 Drawing Figures US. Patent Dec. 30, 1975 Sheet 1 0f 3 3,929,481

N? m n I5 25 22 VAWIIZI IJQE 2| 7 25 Q B NLNHQWz n 22 'IO 24 2;

I2 28 H H H 2 33 2o |9 m E 121 H W" 29 |r-| n g H/ZI 2O US Patent Dec. 30, 1975 Sheet 2 of3 3,929,481

US. atent Dec. 30, 1975 Sheet 3 of3 3,929,481

ETCH BLEACIIING PROCESSESFOR MAKING LITHOGRAPHIC PRINTING PLATES USING SILVER HALIDE AND/OR DIFFUSION TRANSFER LAYERS AND A HYDROPI-IILIC LAYER BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to a plate or light-sensitive plate for making printing plates and more particularly it relates to a plate or light-sensitive plate capable of providing a printing plate having improved printing life. The invention also relates to a lithographic printing plate having improved press life.

2. Description of the Prior Art A lithographic printing plate is generally composed of an oleophilic ink-receptiveportion forming an imaged portion anda hydrophilic portion forming a nonimaged portion. As methods of making such a lithographic printing plate there are known, e.g., a method in which a hydrophilic surface of a light-sensitive plate is converted into an oleophilic portion at only imaged portions and a method in which a hydrophilic layer is formed on the surface of an oleophilic material and the hydrophilic layer is removed at only the imaged portions, exposing the oleophilic surface of the substrate.

One method belonging to the latter type is described in the specification of Japanese Patent Publication No. 27,242/l969, which teaches a method of making a printing plate by forming on a support having an oleophilic surface a hydrophilic diffusion transfer image receiving layer containing nuclei for the diffusion transfer method, further applying thereto a photosensitive silver halide emulsion layer to provide a light-sensitive plate, forming a silver image in the hydrophilic layer by diffusion transfer development and removing, utilizing the silver ,image, the hydrophilic layer at the imaged portion by etching bleach processing to thereby expose the oleophilic surface of the support.

In. U.S. Pat. No. 3,385,701 there is described a method of making a printing plate in which a sheet prepared by forming a hydrophilic diffusion transfer image receiving layer containing nuclei for a diffusion transfer method directly on a support having an oleophilic surface is brought into contact with an imageexposed negative and is subjected to diffusion transfer development to form a silver image in the hydrophilic diffusion transfer image receiving layer. By utilizing the silver image, the hydrophilic diffusion transfer image receiving layer is removed at the imaged portions by an etching-bleach processing to thereby expose the oleophilic surface of the support.

Moreover, in Belgian Pat. No. 717,466 there is described a method of making a printing plate in which a light-sensitive plate comprising a support having thereon a non-porous hydrophilic layer having a contact angle of less than 65 and a light-sensitive silver halide emulsion layer having a melting point of lower than 82C. is image exposed and developed to form a positivesilver image in the emulsion layer, and then the plate is subjected to etching-bleach processing to etch the emulsion layer at the silver image portion and to expose the surface of the hydrophilic layer, whereby a printing plate having a hydrophilic surface at the imaged portions and an oleophilic emulsion layer at the non-imaged portions is obtained.

However, those known printing plates have various faults, e.g., when printing is conducted using those by the strippingof the hydrophilic layer(s) and thus it is difficult to obtain many prints having good quality using those printing plates. For instance, in the printing plate disclosed in the specification of Japanese Patent Publication No. 27,242/1969, a hydrophilic diffusion transfer image receiving layer is directly formed on the oleophilic surface of a support and thus the adhesive property between the support surface and the hydrophilic diffusion transfer image receiving layer is insufficient, which frequently results in stripping of the hydrophilic diffusion transfer image receiving layer at nonimaged portions during printing, thus causing stains by the adhesion of an oily ink thereto.

In an ordinary lithographic printing plate which is composed of an oleophilic surface and a hydrophilic diffusion transfer image receiving layer formed directly thereon, which utilizes the difference in affinity for an oily ink between the oleophilic surface exposed by removing the hydrophilic diffusion transfer image receiving layer at the imaged portions and the remaining hydrophilic layer, it is necessary to prevent the formation of stains caused by the adhesion of ink to the nonimaged portions by making the difference in affinity for the ink as large as possible. This can be attained by increasing the hydrophilicity of the hydrophilic layer. However, an increase in the hydrophilicity results in reducing the adhesive property between the oleophilic surface and the hydrophilic layer and causes stripping of the hydrophilic layer itself at non-imaged portions during printing which results in the formation of stains. Therefore, it has long been desired in this field of art to overcome the defects mentioned above and to provide printing plates having a large printing capacity.

SUMMARY OF THE INVENTION One object of this invention is, therefore, to provide a plate or light-sensitive plate for making a printing plate capable of giving a large number of printings without causing stains.

Another object of this invention is to provide a method of printing which gives more than several thousand stable prints without causing stains using an etching-bleach process.

Still another object of this invention is to provide a plate or light-sensitive plate for direct printing capable of providing dot images directly from an original using a highly sensitive silver halide light-sensitive material for giving a large number of prints from the original, the light-sensitive plate after forming dot images being used as a direct lithographic printing plate capable of giving halftone prints having good quality and a high light portion of good fine dot reproduction.

Still another object of this invention is to provide a light-sensitive material for photographic direct printing plates capable of being used as a line work printing plate.

Other objects of this invention will be understood from the following description.

These objects of the invention can be attained by using a plate or light-sensitive plate for making a printing plate comprising an oleophilic support carrying thereon a photosensitive silver halide emulsion layer anda hydrophilic diffusion transfer image receiving layer containing physical development nuclei (this layer is hereinafter called a silver image forming layer), or a silver image forming layer and a photosensitive silver halide emulsion layer wherein a hydrophilic 7 3 v intermediate layer is formed between the support and the-lowermost layer described above by applying to the surface of the olephilic support, prior to forming the aforesaid silver halide emulsion layer or the silver image forming layer, an organic solvent solution of a hydrophilic resin, a resin which can be modified so as to be hydrophilic upon contact with the alkali in a developer, an oleophilic'resin which becomes porous and hydrophilic by brushing, or a mixture of such resins, followed by removing the organic solvent.

The light-sensitive plate is exposed behind an original and developed to form a positive silver image in the silver image forming layer(s). The plate is then etchbleached in an acid solution containing cupric chloride and aoxidizing agent such as hydrogen peroxide to bleach the developed silver and at the same time to etch'away both the silver image forming layer carrying the developed silver image and the hydrophilic intermediate layer under the silver image portion, whereby the oleophilic surface of the support is exposed at that portion and thus a printing surface having excellent printabilityis obtained. 'The important feature of this invention in this case is that the thin hydrophilic intermediate layer formed under the silver image forming layer is etched away at portions corresponding to the silver image of the silver image forming layer by the etch-bleach treatment together with the silver image forming layer to expose the oleophilic surface of the support and to provide an excellent printing surface.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 7 show various embodiments of producing printing plates in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION The above-described phenomonon obtained using the light-sensitive material or plate for a printing plate has not hitherto been known and is an important feature of this invention, that is to say, the present invention is based on the new discovery that etching can be diffusion transferred.

An mentioned before, according to the inventions described in Japanese Patent Publication No. 27242/1969 and US. Pat. No. 3,385,701, a hydrophilic diffusion transfer image receiving layer or a photosensitive silver halide emulsion layer is directly formed on the oleophilic surface of a support, a silver image is formed in the image receiving layer or the silver halide emulsion layer, the image receiving layer or the silver halide emulsion layer is removed at the silver image portions to thereby expose the oleophilic surface of the support and to thus provide a printing surface. Further, in the specification of Belgian Patent No. 717,466 there is described an example in which a hydrophilic layer formed under a silver image forming layer is not etched, that is, according to this Belgian patent a lightsensitive material for a printing plate prepared by forming a hardened gelatin layer containing titanium dioxide on the surface of an aluminum plate which had been anodically oxidized in a phosphoric acid bath, and further applying thereto a hardenable silver chloride emulsion, is exposed, developed and then bleached for 60 seconds in a solution having the following composition.

Cupric chloride g g -continued Citic acid g Thiourea 75 g Water containing l5/ 1000 of hydrogen peroxide solution 1 liter.

The plate is then washed with water to remove the etched silver halide emulsion layer and to provide a printing surface. By this method, however, ink will adhere to the subbing layer, i.e. since the hardened gelatin layer formed under the silver halide emulsion layer remains without being etched away, ink adhereas to the layer to cause stains. Thus, the Belgian patent describes an example of forming a polyacrylamide layer in place of the gelatin subbing layer in Example 2 of the Belgian patent, and by using the light-sensitive plate having the polyacrylamide subbing layer, a printing plate is produced by the same manner as in Example l of the same patent. In this case, the hydrophilic surface of the polyacrylamide layer formed under the silver halide emulsion layer remains without being removed by the etching treatment and is exposed by the etching treatment. Thus, the exposed surface of the polyacrylamide subbing layer is utilized as a hydrophilic printing surface and the remaining silver halide emulsion layer is utilized as an oleophilic imageforming surface. i

As mentioned above, in the conventional techniques disclosed as lithographic printing methods wherein silver images are etched in an etch-bleach bath to provide printing surfaces with a difference inink receptive power, only the colloid layer or emulsion layer having a silver image is removed by etching, and a hydrophilic layer formed under the colloid layer or the emulsion layer remains without being etched away and is utilized as it is as the printing surface.

On the other hand, we have discovered, in this invention, the astonishing new fact that etching at the portion of a silver image forming layer carrying a silver image works upon a subbing layer and have succeeded in-making an excellent printing plate or surface.

In more detail, the inventionrelates to a light-sensitive material for making a printing plate comprising a support having an oleophilic surface carrying thereon a photosensitive silver halide emulsion layer, a material for making a printing plate comprising a support having an oleophilic surface carrying thereon a hydrophilic diffusion transfer image receiving layer containing physical development nuclei, or a light-sensitive material for making a printing plate comprising a support having an oleophilic surface carrying thereon a photosensitive silver halide emulsion layer and. a hydrophilic diffusion transfer image receiving layer containing physical development nuclei or carrying thereon the hydrophilic diffusion transfer image receiving layer as above and a photosensitive silver halide emulsion layer, characterized in that a hydrophilic intermediate layer is formed between the support and the lowermost layer. The invention also relates to a method of producing a printing plate from such a light-sensitive material or material for making a printing plate.

We discovered, as disclosed in our prior application, Japanese Patent Publication No. 2283,/197 4, a similar light-sensitive material for making printing plate having a thin gelatin or nitrocellulose layer as the hydrophilic intermediate layer which is positioned between a support and a lowermost layer and is also etched away by etch-bleach treatment at a silver image portion. In the present invention, however, we have further discovered that an excellent light-sensitive material for printing plates the same as or superior to those of our prior application can also be obtained using specific compounds other than gelatin or nitrocellulose as the material for the intermediate layer.

As the materials or light-sensitive materials of this invention for making printing plates, there are many embodiments, which will be explained in detail by referring to the accompanying drawings, in which FIG. 1 to FIG. 7 show typical embodiments of our invention each including a materials for making a printing plate and the manner of making a printing plate.

FIG. 1 is schematic view showing an embodiment of our invention. FIG. LA is a sectional view showing the light-sensitive material of this invention for making a printing plate composed of a support 10 having an oleophilic surface, a hydrophilic intermediate layer 11 which can be etched away at the portion corresponding to a silver image formed in a silver halide emulsion layer, and an unhardened silver halide emulsion layer 12. FIGS. l-B to l-E are cross sectional views of the material of this invention in the main stages of making a printing plate by an embodiment of the method of this invention. In the stage shown in FIG. l-B, the light-sensitive material 13 for making a printing plate is exposed through a negative original 15 having continuous tone behind a contact screen 14. A dot latent image 16 is formed in this stage from the continuous tone original by the contact screen. The stage of FIG. l-C shows the state when the plate is developed in a lithographic developer, whereby the latent image 16 at the exposed portion of the emulsion layer 12 is developed to form a silver image 17. This silver image has the opposite gradation to that of the original, in other words, because the original is negative in this case, the silver image formed is positive. After development, the plate may be fixed, but usually the fixing step is omitted. After rinsing, the plate thus developed is treated in an etch-bleach solution, and thus the portion of the silver halide emulsion layer having the silver image is etched. This state is shown in the state of FIG. l-D, in the case of which the hydrophilic intermediate layer 11 under the silver halide emulsion layer 12 has been affected by the etching action at the portions corresponding to the silver image.

When the plate surface is rubbed with a sponge in a warm water bath at about 30C., the hydrophilic intermediate layer 11 is removed at the portion affected by the etching action together with the silver halide emulsion layer 12. This state is shown in the stage of FIG. l-E. Thus, the hydrophilic intermediate layer 11 is removed at the portion corresponding to the image portion to expose the surface 18 of the oleophilic support 10 providing an image yielding portion at printing, while the hydrophilic intermediate layer 11 remains at the portion 19 corresponding to the non-imaged portions providing a non-imaged yielding portion at printing. The printing plate thus prepared can be used by an ordinary printing method.

FIG. 2 is schematic views showing a second embodiment of our invention. In FIG. 2-A is shown a sectional view of an embodiment of the light-sensitive material of this invention for making a printing plate composed of a support 20 having an oleophilic surface, a hydrophilic intermediate layer 21 to be etch-bleached at the portions corresponding to a silver image formed in a silver halide emulsion layer, a negative emulsion stripping layer 22 and a hardenable silver halide emulsion layer 23.

FIG. 2-B to FIG. 2-E are schematic views showing the stages of making a printing plate using the light-sensitive material shown in FIG. l-A according to an embodiment of the method of this invention.

In the stage shown in FIG. 2-B, the light-sensitive material 24 for making a printing plate is exposed through a negative continuous tone original 26 behind a contact screen 25. In this stage, a dot latent image 27 is formed in the silver halide emulsion layer 23 of the light-sensitivematerial 24 from the continuous tone original by the contact screen. The plate thus exposed is developed in a lithographic developer and this state is shown in FIG. 2-C, in the case of which a silver image 28 is formed in the silver halide emulsion layer at the portion having the latent image 27. The plate is then treated in an etch-bleach solution, whereby the silver halide emulsion layer 23 is etched at the imaged portion and also the stripping layer 22 and the hydrophilic intermediate layer 21 are affected by the etching action. This state is shown in FIG. 2-1).

When the plate surface is rubbed by a sponge in a warm water bath at 30C. the hydrophilic intermediate layer is removed at portions affected by the etching action together with the silver halide emulsion layer 23 and the stripping layer 22. This state is shown in FIG. 2-E. In this stage, the hydrophilic intermediate layer 21 is removed at the portion corresponding to the image portions of thesilver halide emulsion layer tothereby expose the surface 29 of the oleophilic support 20, while the hydrophilic intermediate layer 21 remains at the portion corresponding to the non-imaged portions. The printing plate thus prepared can be used in a conventional manner.

Each of the embodiments explained above is a negative process or a process of forming a printing plate of the type where ink adheres to the exposed portions of the light-sensitive material.

The case of applying our invention to a positive process or a process of preparing a printing plate of the type where ink adheres at portions corresponding to the unexposed portions of the light sensitive material will be described by the following embodiments.

FIG. 3 is schematic views showing a third embodiment of our invention. FIG. 3-A is a cross sectional view showing an embodiment of the light-sensitive material of this invention for making a printing plate composed of a support 30 having an oleophilic surface, a hydrophilic intermediate layer 31 which can be etched at the portions corresponding to the silver image formed in a silver halide emulsion layer, and an unhardenable silver halide emulsion layer 32 of the direct positive type.

FIG. 3-B to FIG. 3-D are schematic views showing the stages of preparing a printing plate using the lightsensitive plate shown in FIG. 3-A according to one embodiment of the method of this invention.

In FIG. 3-B, the light-sensitive plate 33 of this invention is exposed through a positive original 34 having a dot or line image, and a latent image 32 is formed in the silver halide emulsion layer 33 at the non-imaged portions. The plate is then developed in an ordinary developer, and this stage is shown in FIG. 3-C. In this stage a silver image is formed in the silver halide emulsion layer 32 at unexposed portions. After development, the plate may be fixed, but usually the fixing step is omitted. After rinsing, the plate is treated in a known etchbleach solution, whereby the portion of the silver halide emulsion layer having the silver image is etched and in this case the hydrophilic intermediate layer 31 under the silver halide emulsion layer is affected by the etching action at portions corresponding to the silver image. Then, when the plate surface is lightly rubbed with a sponge in a warm bath at about 30C., the silver halide emulsion layer and the hydrophilic intermediate layer at the portions affected by the etching action are removed. This state is shown in FIG. 3-E, in which the silver halide emulsion layer has been removed together with the hydrophilic intermediate layer thereunder at portions corresponding to the silver image to thereby expose the oleophilic surface of the support, while the hydrophilic intermediate layer remains at the nonimaged portions. The printing plate thus made can be used in a conventional manner.

FIG. 4 shows schematic views of a fourth embodiment of our invention. That is to say, FIG. 4-A is a sectional view showing an example of the light-sensitive material for making a printing plate composed of a support 40 having an oleophilic surface, a hydrophilic intermediate layer 41 which can be etched at portions corresponding to a silver image formed in a silver halide emulsion layer, a negative emulsion stripping layer 42, and a hardenable silver halide emulsion layer of the direct positive type 43.

FIG. 4-B to FIG. 4-E are schematic views showing the stages of making a printing plate using the light-sensitive plate shown in FIG. 4-A according to an embodiment of the method of this invention.

In the stage of FIG. 4-B, the light-sensitive plate 44 of this invention is exposed through a positive original 45 and in this stage there is formed a latent image 46 in the emulsion layer 45 of the light-sensitive plate 44 at the exposed portions, i.e., the portions corresponding to the non-image portions of the original. The plate is then developed, whereby a silver image is formed in the silver halide emulsion layer 43 at the portions corresponding to the image portions of the original. This state is shown in FIG. 4-C.

After rinsing, the plate is treated in a conventional etch-bleach solution, whereby the silver halide emulsion layer is etched at the portion having the silver image and in this case both the stripping layer 42 under the silver halide emulsion layer and the hydrophilic intermediate layer 41 are affected by the etching action. This state is shown in FIG.'4-D. When the surface of the plate is lightly rubbed with a sponge in a warm water bath at about 30C. the silver halide emulsion layer 43 and the stripping layer 42 are removed together with the hydrophilic intermediate layer 41 at the portions affected by the etching action. This state is shown in FIG. 4-E, in which the silver halide emulsion layer and the stripping layer have been removed together with the hydrophilic intermediate layer at the non-image portions to thereby expose the oleophilic surface of the support 47, while the hydrophilic intermediate layer 48 remains at the non-image portions. The printing plate thus made can be used according to a conventional manner.

FIG. is schematic views of a fifth embodiment of this invention for making a printing plate. FIG. 5-A is a sectional view of an example of the light-sensitive plate of this invention for making printing plate composed of a support 50 having an oleophilic surface, a hydrophilic intermediate layer 51, and a hydrophilic diffusion transfer image-receiving layer 52 containing physical development nuclei.

FIG. S-B to FIG. 5-D are schematic views showing the stages of making a printing plate using the light-sensitive plate of FIG. 5-A according to an embodiment of the method of this invention.

In FIG. S-B, the plate 55 of this invention having the above-mentioned structure and a light-sensitive material 56 composed of a support 54, such as a paper or a plastic film, and a photosensitive silver halide emulsion layer 53 formed thereon are shown.

In the light-sensitive material 56, a latent image 53a has been preliminaraly formed by exposure at portions of the photosensitive silver halide emulsion layer corresponding to the non-image portions of an original. The light-sensitive material 56 is placed on the plate 55 for a printing plate with a diffusion transfer photographic developer between them to conduct the development. This state is shown in FIG. S-C, and in this stage the silver halide in the exposed portion, i.e., the latent image portion of the silver halide emulsion layer 53, is chemically developed to form a silver image therein. The silver image thus formed is negative to the original image. On the other hand, in the image receiving layer 52 of the plate 55 there is formed a silver image at the portions corresponding to the image portion of the original because the silver halide in the silver halide emulsion layer 53 at the unexposed portions diffuses as a complex salt into the image receiving layer 52 by the action of a solvent for silver halides contained in the developer, whereby the complex salt of a silver halide is brought into contact with the physical development nuclei present in the image receiving layer to be reduced into metallic silver and to form a silv'erimage therein. This silver image formed in the image receiving layer is positive to the original.

After development, the plate 55 is separated from the light-sensitive material 56 and, after rinsing, the plate is treated in a conventional etch-bleach solution. By this treatment the image receiving layer is etched at the portions having the silver image. In this case, the hydrophilic intermediate layer 51 under the image receiving layer is affected by etching action at the portion corresponding to the silver image portion of the image receiving layer. Then, when the surface of the plate is lightly rubbed with a cotton pad, the image receiving layer and the hydrophilic intermediate layer are removed at the etched portions to expose the oleophilic surface of the support 50. On the other hand, the hydrophilic image receiving layer of the nonimaged portion remains together with the hydrophilic intermediate layer under the non-imaged portion of the image receiving layer. This state is shown in FIG. S-D.

The printing plate thus formed can provide many stable duplications having high image quality using commercially available printing inks and wetting water.

In the embodiment shown in FIG. 5, the plate for making a printing plate is separated from the light-sensitive material and thus the plate can be combined, at use, with any desired light-sensitive material, if necessary. Also, the plate for making a printing plate is itself non-light sensitive, and thus the preservation and handling of such a plate are quite simple.

Now, if it is possible to form an image on a light-sensitive material from an original and to make a printing plate therefrom using a simple procedure, such a system is economically attractive and is also labor saving. Both of these objects are met by combining a light-sensitive material and a plate for a printing plate according to the present invention, as illustrated by the embodiments shown in FIG. 6 and FIG. 7.

FIG. 6 shows a sixth embodiment of our invention. FIG. 6-A is a cross sectional view of the light-sensitive plate for a printing plate of this invention composed of a support 60 having an oleophilic surface, a hydrophilic intermediate layer 61, a hydrophilic diffusion transfer image receiving layer 62 containing physical development nuclei, and a non-hardenable photosensitive silver halide emulsion layer 63. FIG. 6-B to FIG. 6-F are schematic views showing the stages of making a printing plate by the sixth embodiment of this invention using the light-sensitive plate shown in FIG. 6-A.

In FIG. 6-B is a cross sectional view showing exposing the light-sensitive plate 64 of this invention through a positive original 65. In this stage there is formed a latent image 66 in the silver halide emulsion layer 63 of the light-sensitive plate 64 at the positions corresponding to the non-image portions of the original 65. This latent image is negative to the original.

FIG. 6-C shows the state where the light-sensitive plate thus exposed is subjected to a diffusion transfer development, whereby the silver halide in the exposed portions 66 of the silver halide emulsion layer 63 is chemically developed form a silver image. On the other hand, in the image receiving layer 62 there is formed a silver image at the portion corresponding to the nonexposed portions of the emulsion layer 62. The silver image of the image receiving layer 62'is formed due to the phenomenon that the silver halide in the nonexposed portions of the silver halide emulsion layer 63 is diffused as a complex salt thereof into the image receiving layer 62 by a solvent for silver halides contained in the developer, is brought into contact with the physical developement nuclei in the image receiving layer and is there reduced into metallic silver. This silver image is positive to the original, i.e'., is the same image as the original.

The plate for a printing plate thus developed is immersed in a warm bath at about C., where the silver halide emulsion layer is removed. This state is shown in FIG. 6-D.

The plate having the positive silver image in the image receiving layer 62 is treated in an etch-bleach solution containing hydrogen peroxide. By this treatment, the portion of the image receiving layer 62 having the silver image is etched and at the same time the portions of the hydrophilic intermediate layer 61 under the silver image portion of the image receiving layer 62 are also etched. This state is shown in FIG. 6-E.

By rubbing weakly the surface of the plate thus subjected to the etch-bleach treatment, the etched portions of the both layers are removed and the oleophilic surface of the support 60 is exposed. This state is shown in FIG. 6-F.

The printing plate thus prepared can provide many prints having excellent image quality.

FIG. 7 shows schematic views of a seventh embodiment of this invention.

FIG. 7-A is a cross sectional view of the light-sensitive plate for a printing plate of this invention composed of a support 70 having an oleophilic surface, a hydrophilic intermediate layer 71 formed thereon, a hydrophilic diffusion transfer image receiving layer 72 containing physical development nuclei, a stripping layer 73 for negative emulsion layerand a hardenable photosensitive silver halide emulsion layer 74.

FIG. 7-B to FIG. 7-F are schematic views showing the stages of making a printing plate by the seventh embodiment of this invention using the light-sensitive plate shown in FIG. 7-A.

FIG. 7-B' is a sectional view of the state of exposing the light-sensitive plate 75 of this invention through a positive original 76. In this stage there is formed a latent image 77 at the portions of the silver halide emulsion layer 74 corresponding to the non-image portions of the original. This latent image is negative to the original.

FIG. 7-C shows the state where the plate thus exposed is subjected to a diffusion transfer development, whereby the silver halide in the exposed portion of the silver halide emulsion layer 74 is chemically developed to form a silver image. On the other hand, in the image receiving layer 72 there is also formed a silver image at the portions corresponding to the nonexposed portions of the silver halide emulsion layer 74. The silver image in the image receiving layer 72 has been formed by the phenomenon that the silver halidein the non-exposed portions of the silver halide emulsion layer is diffused as .a complex salt thereof through the stripping layer 73 into the image receiving layer 72, brought into contact with the physical development nuclei'in the image receiving layer 72, and reduced into metallic silver. The silver image is positive to the original.

The plate thus developed is immersed in a warm water bath at about 30C. to remove the emulsion layer. This state is shown in FIG. 7-D. Then, the plate having the positive silver image is treated in an etchbleach solution containing hydrogen peroxide and by this treatment the portions of the image receiving layer having the silver image are etched and at the same time the portions of the hydrophilic intermediate portion under the silver image portion of the image receiving layer are etched and become readily removable. This state is shown in FIG. 7-E. I

Then, by weakly rubbing the surface of the plate thus subjected to the etch-bleach treatment with a cotton pad, the etched portions are removed to expose the oleophilic surface of the support 70, while the hydrophilic image receiving layer remains on the support at the non-image portions together with the intermediate layer under these portion. This state is shown in FIG. 7-F.

The printing plate thus prepared can provide many prints having excellent image quality by using commercially available printing ink and wetting water.

In the practice of this invention it is a necessary factor for improving the press life of the printing plate made from the plate or light-sensitive plate of this invention that the hydrophilic intermediate layer be strongly adhered to the oleophilic surface of the support.

The reason that the hydrophilic intermediate layer must be strongly bonded to the oleophilic surface of a support in our invention is considered to be as follows, although the following theory is not always definitive. By selectively employing a definite material for the hydrophilic intermediate layer and a definite organic solvent therefor in accordance with the present invention, a co-fusion of the material of the intermediate layer and the support is caused at the interface of both layers, which results in a strong adherance of the hydrophilic intermediate layer to the oleophilic surface of the support. Thus, the printing plate made using the plate or the light-sensitive plate of this'invention has an 11 1 improved press life. This feature is also important factor of this invention. On the other hand, a conventional plate for making printing plate is produced by forming a coating composition on the oleophilic surface of a support using water as the solvent, and thus the adhesion between both layers is weak, stains are apt to form caused by stripping of. the hydrophilic layer at printing and the press life of the printing plate is poor.

. The hydrophilic intermediate layer used in this invention is selected from the materials satisfying three factors: the hydrophilic intermediate layer adheres strongly to the oleophilic surface of a support; the hydrophilic intermediate layer provides a good hydrophilic printing surface at printing; and the. hydrophilicintermediate layer must be etched in the etch-bleach treatment at portions corresponding to the silver image-containing portions of the layer above the intermediate layer.

Known materials usually used in the field of photography as subbing materials may be used as materials for the hydrophilic intermediate layer if they meet the above three factors. However, as is well known, materials used as a subbing layer must be selected from those satisfying the requirement that they have a strong adhesive property to both the surface of a silver halide emulsion layer which is formed from an aqueous emulsion and the surface of a hydrophobic support, such as a polyester film or a cellulose acetate film, both of which have different properties.

The hydrophilic intermediate layer in this invention isrequired to have a strong adhesion to the oleophilic surface of a support and aproper adhesive property to the ,gelatino-silver halide emulsion layer formed thereon since the silver halide emulsion layer must be stripped away, after the etch-bleach treatment. Therefore, in the practice of this invention it is not necessary to select materials for the hydrophilic intermediate layer based solely upon the conventional concept of ,subbing materials regarding adhesive property and the-materials may be selected from a broader range. However, itis most important to select materials so that the hydrophilic intermediate layer made from the materials are etched at portions corresponding to the silver image containing portion of the layer above it in the case; of etch-bleaching the silver image portion of the above layer and further the non-imaged portions of the intermediate layer remaining on the support must give a good hydrophilic printing face. This point is also one of the important featuresof this invention.

As the materials for the hydrophilic intermediate layers in this invention, there may used hydrophilic resins, resins which will be modified into hydrophilic resins by contact with an alkaline developer, and resins which are endowed with a hydrophilic property by the porosity thereof, and these may be used alone or as a mixture thereof. The hydrophilic resins of the present invention serve a superior protective colloid function, have good light transparency, superior permeability in contact with an alkaline developer and mixed easily in greatly varying proportions with gelatin.

The resins to be used as the materials for the hydrophilic intermediate layers inthis invention are shown below:

Group A: (hydrophilic resins) gum arabic, alginic acid, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, polyacrylamide, polyvinyl pyrrolidone, copolymers of the above compounds; polyvinyl alcohol, and polyvinyl alcohol derivatives;

' Group B: maleic'anhydride-vinyl acetate copolymers, maleic anhydride-ethylene copolymers, maleic anhydride-methylvinyl ether copolymers, maleic anhydridestyrene copolymers, half ester derivatives of those copolymers, acrylic acid copolymers, and methacrylic acid copolymers;

Group C: partially saponified cellulose acetate, partially saponified cellulose butyrate and partially saponified cellulose acetate butyrate' The compounds of Group A, Group B, and Group C may be used alone or as a mixture thereof.

While any of the above hydrophilic resins can be used in the present invention if they illustratethe general superior characteristics hereto recited, and the selection of any one specific hydrophilic resin is not overly limited, nonetheless certain preferred materials do exist, which are described below. 1

' Group A: polyvinyl pyrrolidone having an average molecular weight of generally from 1,000 to 400,000, preferably 4,000 to 360,000; polyacrylamide having an average molecular weight of from 100,000 to 1,500,000, preferably 500,000 to 1,000,000; hydroxyethyl cellulose having an average molecular weight of from 50,000 to 300,000; methyl cellulose having an average molecular weight from 50,000 to 500,000; carboxymethyl cellulose having an average molecular weight of from 50,000 to 500,000; polyvinyl alcohol or derivatives thereof having a degree of saponification of from 50 to preferably 60 to 99% and an average degree of polymerization of 300 to 5,000, preferably 500 to 2,000; copolymers of polyvinylpyrrolidone and polyacrylamide have a copolymerization ratio on the order of one having a molecular weight of 100,000 to 500,000.

Group B: copolymers of maleic acid anhydride vinyl acetate, maleic acid anhydride ethylene and maleic acid anhydridemethyl vinyl ether having a copolymerization ratio on the order of 1:1, copolymers of maleic acid anhydride-styrene having a copolymerization ratio less than 1:1, preferably 1:1 to 1:3; half-ester derivatives of the above materials such as meleic acid anhydride and methyl, ethyl, propyl, etc., half-esters where the degree of esterification is 30 to 50%; acrylic acid copolymers with, for example, N-vinyl pyrrolidone, acrylamide, methacrylic acid, methacrylic amidevinyl acetate, diethyl acrylamide, and the like, the copolymerization ratio being freely variable but most preferably on the order of 1:1; copolymers of methacrylic acid with, for example, acrylamide, diethyl acrylamide, vinyl pyrrolidone, methyl acrylate, butyl methacrylate, propyl,.methyl acrylate, methylmethacrylate, ethylacrylate and the like, using a copolymerization ratio as desired, preferably on the order of 1:1.

Group C: preferred are those materials where the degree of saponification is less than 50%, preferably 0 to 30%.

In general, a hydrophilic layeris formed by dissolving or dispersing gelatin, nitrocellulose, a mixture of gelatin and nitrocellulose, or a copolymer of maleic anhydride and vinyl acetate in' an organic solvent and applying the solution or the dispersion onto a support in an ordinary manner. followed by drying to remove, the organic solvent. However, using the compounds of Group A, Group B, or Group C a plate or light-sensitive plate for making a printing. plate showing excellent printability the same as or superior to that of the case of using gelatin, nitrocellulose, etc., as above is obtained.

The organic solvent used for coating the above-mentioned material is one which has the capability to swell, soften or dissolve the surface of the support. Practical examples of such an organic solvent are acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, methanol, ethanol, ethyl formate, methyl acetate, benzene, toluene, methylene chloride, ethylene chloride, tetrachloroethane, trichloroethane, chloroform, chlorobenzene, ethylene chlorohydrin, chlorosulfonic acid, nitromethane, dimethylformamide, morpholine, formic acid, acetic acid, benzoic acid, salicylic acid, salicylic acid esters, monochloroacetic acid, dichloroacetic acid, trichloracetic acid, trifluoroacetic acid, Z-nitropropanol, benzyl alcohol, benzamide, benzonitrile, benzylamine, methyl nicotinate, phenol, ochlorophenol, cresol, a divalent phenol such as resorcinol and other phenol derivatives.

Those organic solvents may be used alone or as mixtures thereof.

The water content in the organic solvent varies depending upon the nature of the hydrophilic polymer used for the hydrophilic intermediate layer, and the water acts as an aid for dispersing or dissolving the polymer in the organic solvent. The essential mechanism involved is that first the hydrophilic polymer is dissolved in the water, and then the polymer (actually a hydrous solution thereof) diffuses into the organic solvent. However, because the adhesion between the oleophilic surface of the support and the hydrophilic polymer is influenced by the water content in the organic solvent, it is preferred, for strongly adhering the hydrophilic polymer layer to the surface of the oleophilic support, that the water content be as small as possible. Furthermore, if necessary, an additive for improving the coating property, an antihalation dye, or a developing agent may be dissolved or dispersed in the coating composition or emulsion comprising the aforesaid polymer and the organic solvent.

It is very important for obtaining the hydrophilic intermediate layer effective for the present invention to select and suitably control the composition of the material for forming the intermediate layer and the hardenability and the thickness of the layer. Moreover, the above factors are also influenced by the composition, hardenability and thickness of the silver image forming layer(s) formed over the hydrophilic intermediate layer, and also the amount of total silver formed by the development and the form of silver.

In general, the thickness of the hydrophilic intermediate layer is from 0.1 micron to 3 microns, preferably from 0.2 micron to L5 microns.

Discussing some of the factors mentioned above in greater detail, and the relationship of various layers, the hardenability of the hydrophilic intermediate layer must be such that it can be etched by means of an etch-bleach bath because when the emulsion layer is peeled off at about 40C the hydrophilic intermediate layer is not dissolved.

The hydrophilic diffusion transfer image receiving layer containing physical development nuclei will generally have a thickness of from about 0.1 to about 3 microns, preferably 0.2 to 1.5 microns. The layer should not be so thick that during etching the facing portions of the hydrophilic intermediate layer are not etched, and on the other hand the layer should not be so hard that the layer is insufficiently etched during the etching treatment. If the above faults are encountered, the layer cannot be used as a lithographic plate because the hydropholic support will not be exposed. It is generally sufficient if the amount-of silver formed in this layer is greater than 0.3 (optical concentration).

The silver halide emulsion layer which can be used instead of or in addition to the hydrophilic diffusion transfer image receiving layer is generally about 1 to about 15 microns thick, more preferably 2 to 8 microns thick. The weight ratio of silver halide/binder can vary greatly but normally is in the range of 1/4 to 6/1 more preferably l/ 1 to 4/1. Generally speaking, better results are achieved at higher silver concentrations, and the amount of silver will usually be 5 to 60 mg/dm preferably l0 30 mg/dm In this regard, it is appropriate to mention that the hydrophilic, diffusion transfer image receiving layer containing physical development nuclei merely need contain sufficient nuclei to permit an etchable image to be formed. The exact amount of physical development nuclei can vary greatly, but generally speaking the weight ratio of nuclei/binder is usually from about 0.1/l to about 0.001/1, the total nuclei content being at least about 0.001 mg/dm.

By forming the hydrophilic intermediate layer on the surface of a support according to the present invention, the adhesive property between the layer and the oleophilic surface of the support is strengthened and the strength of the hydrophilic intermediate layer can be increased, whereby the press life of the printing plate prepared from the light-sensitive plate having such a hydrophilic intermediate layer can be greatly increased and also the printing operation can be conducted quite stably by using the printing plate. However, the following fault has to be overcome, that is, in order-to expose the oleophilic surface of the support at the desired portions, the hydrophilic intermediate layer formed on the support must be effectively etched at the portions corresponding to the silver image portions formed in the adjacent layer over the intermediate layer in the etch-bleach treatment. Thus, according to the present invention, there is provided a plate or light-sensitive plate for making a printing plate in which the hydrophilic intermediate layer can be easily removed and the oleophilic surface of the support is exposed by'an etchbleach treatment as indicated above, i.e., the properties required for the hydrophilic intermediate layer, the image forming layer or the stripping layer can beattained by properly controlling the composition,-hardenability, and thickness of those layers and also the total amount of silver formed in the image forming layer and the ratio of the amount of silver to the medium in the layer.

Other elements of the plate for printing plate of this invention, such as the support, image-receiving layer, etc., can be formed using known compositions. As the support, there can be illustrated polymer films such as polyethylene terephthalate, cellulose acetate, synthetic papers, water proof papers, metallic sheets, and the like. When a hydrophilic metallic support such as an aluminum support is used, an oleophilic layer is formed on'the surface of the support by coating, vacuum evaporation, plating, spray painting, laminating, etc. A polyethyelene terephthalate film is frequently used since it has an excellent oleophilic property and excellent dimensional stability and flexibility.

Further illustrative of the many different types of resins which can be used as supports in accordance with the present invention are polystyrene and polypropylene. There can also be used metal plates, such as zinc, and resin treated papers such a melamine resin treated paper, polystyrene treated paper.

The one necessary property of the oleophilic support is that it repellwater and absorb ink. The degree .of oleophilicity can be determined by standard art-recog-. nized techniques, i.e., measuring the contact angle, thesolubility, the suction and the like.

The supports illustrated above may, if desired, be subjected to a surface treatment. Examples of such a surface treatment are a corona discharge treatment, an ultrasonic treatment, a heat treatment, a chemical treatment, an ultraviolet irradiation, an oxidation by ozone, a laser irradiation, a high frequency wave irradiation, a blasting treatment, for instance, toughening by propelling small grains against the surface, rubbing with emery paper, brushing and the like.

The hydrophilic image receiving layer in this invention is formed by dispersing physical development nuclei in a medium which will be etched away by the action of a silver image in an etch-bleach treatment. A suitable material to be used as the medium is gelatin. Examples of the materials to be employed as the physical development nuclei are colloidal silver, silver sulfide, nickel sulfide, zinc sulfide, sodium sulfide, colloidal sulfur, thiosinamine, stannous chloride, chloroauric acid and the like. The nuclei materials are typically provided by adding a salt such as nickel salt to a gelatin hydrous solution and thereafter adding, e.g., a sulphide to precipitate the diffusion transfer nuclei.

.Thev mediums to be used for forming the hydrophilic image-receiving layer and the stripping layer for negative emulsion layer work in this invention are hydrophilic colloids or a mixture of such hydrophilic colloids. Examples of the hydrophilic colloid to be used for this purpose are gelatin, an-alginate, gum arabic, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxyethyl starch, hydroxy propione starch, starch, polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, a copolymer of vinyl acetate and maleic anhydride, a copolymer of vinyl pyrrolidone and methacrylic acid, and a copolymer of acrylic acid and methyl methacrylate. Particularly effective materials are, however, gelatin, an alginate, and a mixture thereof. It will be apparent to one skilled in the art that to improve the stripping of a layer the degree of crosslinking should be weak since it would be preferred to dissolve the layer in hot water of a relatively low temperature. For instance, a Stripping layer which is, at most, only slightly cross-linked can be coated between the emulsion layer and the hydrophilic image receiving. Of course, the silver image formed by transfer diffusion cannot be affected by the components of the stripping layer.

The photographic properties, and the etching property of these layers depend upon the molecular weight, the cross-linking degree and the thickness of the hydrophilic colloid layers. In general, it is preferred that the cross-linking degree be low and the thickness of the layer be about 0.l-3 microns.

For making a printing plate using the plate orlightsensitive plate of this invention, any known process may be used. That is to say, a printing plate is obtained by image-exposing the light-sensitive plate of this invention, developing the plate to form a positive silver image in the image forming layer of the plate and then subjecting the developed plate to an etch-bleach treatment removing the image forming layer at the portion 16 having the silver image together with the hydrophilic intermediate layer under the silver image portion of the image-receiving layer. For photographing an original,

an ordinary silver halide photographic emulsion is used. In particular, a light-sensitive material having a diffusion transfer silver halide emulsion layer or a lithographic silver halide emulsion layer is preferred. The image exposure may be conducted by contact exposure, enlarging exposure, transmission exposure or reflection exposure.

The development of the plate of this invention may be conducted by any conventional manner, but a lithographic development is suitable in a negative to positive system and a diffusion transfer development or a lithographic development is preferred in a positive to positive system (see Japanese patent application Open Public Inspection No. 47339/1973).

The etch-bleach treatment in this invention may also be conducted by a known manner. 7

In our invention, any photosensitive silver halide emulsion layers commonly used can be used. The silver halide in this invention may be suitably selected from silver chloride, silver bromide, silver iodide, silver chlorobromide, silver chloroiodide, silver bromoiodide and silver chlorobromoiodide, but from the objects of our invention a silver halide having high contrast is preferred, e.g., silver chloride, silver bromide and a high contrast silver bromo salt emulsion. As suitable silver halide emulsions for the objects of this invention, a lithographic silver halide emulsion is particularly preferred. There is no overly critical matter involved in selecting any specific silver halide-binder combination for use in forming the silver halide emulsion layer used in the present invention. I

As the binder, gelatin is generally used, but other hydrophilic colloids can be used if desired, e.g., phthalolated gelatin, other gelatin derivatives, vinyl derivatives such as polyvinyl pyrrolidone, polyvinyl alcohol, etc. The silver halide emulsions used in this invention may contain, if desired, known additives such as sensitizers, sensitizing dyes, antifoggants, hardening agents, surface active agents and the like.

A relatively high amount of silver halide is preferred with respect to binder is that the silver halide layer provides an excellent silver salt image when higher amounts of silver are formed and at the same time with higher; amounts of silver the silver halide layer is etched easily. Since it is necessary that the unhardened portions of the silver halide be removable, preferably by dissolving with water at about 40C, no portion of the emulsion layer should be overly hardened. However, when a stripping layer is used in combination with the silver halide layer the layer can be hardened to a degree similar to that of known photosensitive negative emulsion layers.

In our invention, printing plates may be prepared from the light-sensitive plates of this invention by any ordinary method, for example, first the light-sensitive plate of this invention is exposed to an original and developed to form a silver positive image in the silver halide emulsion layer orthe image-receiving layer. In the photographic processing for forming the silver image in the present invention any ordinary developer containing as a developing agent monomethyl-paminophenol sulfate, hydroquinone, l-phenyl-3- pyrazolidone, amidole, etc., individually or as mixtures thereof can be used, but from the objects of our invention, the use of a lithographic developer or a litho- 17 graphic type diffusion transfer developer is most preferred.

The silver halide emulsion layer of the light-sensitive plate of this invention thus developed is preferably, then, processed in an etch-bleach solution to form a lithographic plate. Typical etch-bleach solutions used in this invention contain an ordinary oxidizing agent such as hydrogen peroxide or ammonium peroxide which may contain red prussiate, dichromate, peroxysulfate and the like, an insoluble silver salt forming agent such as chloride ions and a metal ion catalyst such as copper ions. The etch-bleach solution may contain a gelatin softening agent such as citric acid or urea.

The oxidizing agents are added in amounts as are used in the prior art to conduct photo-bleaching, and the amount may vary greatly depending upon the exact oxidizing agent or agents selected. Usually, a minimum of 0.35 weight percent is used, though up to 100 weight percent can be used with weaker oxidizing agents. For instance, in the case of using hydrogen peroxide, preferably a l to 3 weight percent solution of hydrogen perioxide is used. By the processing in the etch-bleach solution, the silver image is etched and at the same time the gelatin at the silver image portions is decomposed to finish the etching. The important matter in this case is that the hydrophilic intermediate layer under the silver image portion also be etched in the processing. After the etch-bleach treatment, the remaining softened colloid layer is removed by softly rubbing the surface of the plate. Examples of etch-bleach solutions useful in the practice of this invention are illustrated below. The printing plate thus produced can be used in any ordinary manner.

Com osition exam le 1:

A Cupric chloride (dihydrate) g Citric acid 10 g Water added to make 1 liter.

B Ammonium persulfate 120 g Water added to make I liter.

Composition example 2:

A Water 750 cc Cupric chloride 10 g Citric acid 10 Water to make 1 iter.

B Hydrogen peroxide (30% aq. soln.) 1 liter.

In the etch-bleach bath it is preferred to add a material such as a cupric salt or acid or material which reacts with silver to form a low solubility complex.

Exemplary of such cupric salts are copper chloride, copper bromide, copper nitrate, copper sulfate, copper citrate and the like, all of which are soluble in water. Cupric halides are preferred.

Illustrative of the acids which can be used are organic acids such as acetic, citric, tartaric acid and the like, and inorganic acids such as hydrochloric, nitric, sulfuric acid and the like.

As materials which form a complex of low solubility by reacting with silver there can be mentioned the halogenides, tartrates and carbonates, with the halogenides being especially effective.

These promoting agents can be used singly or in combination, and the amount added is usually 0.05 to 50% based on the weight of the treating solution. Generally speaking, one would avoid a totally saturated solution and would have a tendency to add the promoting agents so that the total amount of all promoting 18 agents would at most be 50% based on the weight of the treating solution.

Although substantially non-critical in the sense that one merely selects a temperature which permits adequate etch-bleaching to proceed, usually etch-bleaching is at about 5 to about 40C, more generally 15 to 30C.

The etch-bleaching step is merely conducted for a time sufficient to bleach the silver image, and this will vary depending upon the thickness, temperature selected and oxidizing agents used. Usually, more than about 5 seconds is required, and it can be said that for the majority of processings the etch-bleaching is conducted in from about 15 to about 60 seconds, this being sufficient to permit hydrophilic layers containing a silver image to be etched.

The main feature of the plate of this invention for making a printing plate lies in the point that a hydrophilic intermediate layer is formed between an elecphilic support and an image-forming layer but, if necessary, a known layer such as a protective layer, a stripping layer (which is merely removed by mechanical rubbing), an antihalation layer, etc., may be further formed.

The invention will now be further illustrated by the following examples, but the invention should not be construed as limited to these examples.

EXAMPLE 1 (illustrating Embodiment 1; negative-positive process) The surfaces of a polyethylene terephthalate film having a thicknessof 0.18 mm were treated in a solution of 400 cc sulfuric acid, 200 cc phosphoric acid, and g potassium bichromate (water added to make 3 liters, film immersed in system for 3 minutes at 50C same conditions used in all examples where called for), an antihalation layer was applied to one surface, and a solution of an alkali soluble hydrophilic resin having the following composition was applied to the opposite side of the film followed by drying for 2 minutes at C. to provide a hydrophilic intermediate layer having a thickness of 0.3 micron.

Maleic anhydride-vinyl acetate (1 l) copolymer Methanol Acetone Methylene chloride Monochloroacetic acid Chromium sulfate A panchromatically sensitized high contrast lithographic unhardenable gelatino silver chlorobromide emulsion (containing 70% silver chloride and 1 mole of silver per kg of the emulsion) was applied to the intermediate layer in a thickness of 4 microns and dried. Furthermore, a 1% aqueous gelatin solution was applied to the silver halide emulsion layer in a thickness of 1 micron as a protective layer and dried to provide a light-sensitive plate of this invention for making printing plates.

The light-sensitive plate thus prepared was exposed through a color negative original having continuous gradation using a half tone screen. The exposure was conducted at a distance of 1 meter from the light source [Fuji Exposure Lamp (made by Fuji Photo Film Co., Ltd.)] for 2 seconds at 18 volts using a red filter [Fuji Filter SC 62 (made by Fuji Photo Film Co., Ltd.)]. Thereafter, the plate was developed for 3 min- 19 utes at 20C. in a lithographic developer having the following composition.

Boric acid 7 g Hydroquinone 20 g Para-formaldehyde l g Potassium bromide 25 g Potassium hydrogen sulfite 2 g Sodium carbonate (monohydrate) 85 g Water added to make 1 liter.

After washing with water, the plate was immersed for one minute at 20C. in the etch-bleach solution prepared by mixing equal amounts of Solution I and Solution ll of the following compositions.

Solution 1:

Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1 liter. Solution 11:

3% aqueous solution of hydrogen peroxide.

In the processing, the hydrophilic intermediate layer of the portion corresponding the silver image portion of the silver halide emulsion layer had been subjected to the etching action and thus when the surface of the plate was rubbed softly in a warm water bath at 30C. the etched portion of the hydrophilic intermediate layer was removed together with the silver halide emulsion layer, whereby the oleophilic surface of the support was exposedjThus, a cyan separate plate of the original was obtained.

The cyan separate plate was placed on a Davidson SOO-type offset printing machine (made by Davidson & Fairchild Corp.) and 5000 prints were made using a commercial printing ink, A-Set Ink (made by Morohoshi lnk K. K. and wetting water, Fuji Pronodupli Solution No. 50 (made by Fuji Photo Film Co., Ltd.). Thus, a cyan separate image of the original was obtained as high quality printed copies having excellent continuous gradation reproducibility. After the run, no stains or defects were observed on the surface of the printing plate and thus the printing plate could be used for further printing.

By repeating the same procedure as above, a magenta separate plate, a yellow separate plate and a black separate plate of the original were formed, and by using the four separate plates prepared above fourcolor printed copies of the original were obtained.

EXAMPLE 2 (illustrates Embodiment 2; negative-positive process) After treating the surfaces of a polyethylene terephthalate film having a thickness of 0.18 mm with a solution containing sulfuric acid, phosphoric acid, and potassium bichromate (as in Example 1) an antihalation layer was applied to one of the surfaces and a solution of an alkali-soluble hydrophilic resin having the following composition was applied to the opposite surface of the support followed by drying for 2 minutes at 120C. to form a hydrophilic intermediate layer having a thickness of 0.3 micron.

Maleic anhydride-vinyl acetate (1 l) copolymer ethanol -continued Acetone 25 g Methylene chloride 20 g Monochloroacetic acid 10 g Chromium sulfate 0.4 g

A solution of a l 1 copolymer of acrylic acid and methyl methacrylate containing a slight amount of chromium sulfate was applied to the intermediate layer and dried to form a negative emulsion stripping layer having a thickness of 0.2 micron. Then, a panchromatically sensitized high-contrast lithographic hardenable gelatino silver chlorobromide emulsion silver chloride and 1 mole of silver per kg of the emulsion) was applied to the stripping layer in a thickness of 4 microns and dried. Furthermore, a 1% aqueous gelatin solution was applied as a protective layer in a thickness of 1 micron and dried. Thus, a light-sensitive plate of this invention for making printing plates was obtained.

The light-sensitive plate was exposed through a color negative original using a half tone screen. The exposure was conducted at a distance of 1 meter from a light source [Fuji Exposure Lamp (made by Fuji Photo Film Co., Ltd.)] for 2 seconds at 18 volts using a red filter [Fuji Filter SC-(made by Fuji Photo Film Co., Ltd.)]. Then, the plate was developed for 3 minutes at 20C. in a lithographic developer having the following composition:

Boric acid Hydroquinone Potassium bromide Para-formaldehyde Sodium hydrogen sulfite Sodium carbonate (monohydrate) 8 Water added to make After washing with water, the plate was immersed for 1 minute at 25C. in an etch-bleach solution prepared by mixing equal amounts of Solution l and Solution ll having the following compositions.

Solution 1 Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1 liter. Solution 11 3% aqueous hydrogen peroxide solution.

By the treatment, the silver halide emulsion layer of the portion having a silver image and also the hydrophilic intermediate layer and the negative emulsion stripping layer were subjected to etching at the portions corresponding to the silver image portions of the silver halide emulsion layer, and when the surface of the plate was rubbed softly in warm water at 30C. the etched portion of the hydrophilic intermediate layer was removed together with the silver halide emulsion layer and the stripping layer to expose the oleophilic surface of the support film. Thus, a cyan separate plate of the original was obtained.

By following the same procedure as in Example 1 using the cyan separate plate thus obtained, 7000 printed copies were obtained. The prints of the cyan separate image of the original had excellent continuous gradation reproducibility and high image quality. Neither stains nor defects were observed on the surface of 21 the printing plate and the printing plate could be used for further printing. 7

By the same procedure as above, a magenta separate plate, a yellow separate plate and a black separate plate of the original were produced, and by -using the .four

separate plates thus produced four-color printed copies of the original were obtained. r

EXAMPLE 3 (illustrates Embodiment 3, positive-positive process) Maleic anhydride-vinyl acetate (1 l) copolymer Methanol Acetone Methylene chloride Monochloroacetic acid Chromium sulfate 0 n #3852321.) WOQOQU UQOQ Then, a direct positive silver halide emulsion (0.5 mole of silver per kg of the emulsion) was applied to the intermediate layer at a thickness of 4 microns and dried. Furthermore, a 1% aqueous gelatin solution was applied thereto at a thickness of 1 micron and dried to provide a light-sensitive plate for making printing plates.

The light-sensitive plate thus obtained was exposed through a positive original for 30 seconds at 18 volts at a distance of 1 meter from the light source [Fuji Exposure Lamp (made byFuji Photo Film Co.," Ltd.)] using a yellow filter [Fuji Auto Posi Filter (made by Fuji Photo Film Co., Ltd.)]. The plate was then developed for 3 minutes at 25C. in a developer having the following composition to provide a positive silver image the same as the original: I

Monomethyl-p-aminophenol sulfate Anhydrous sodium sulfite Hydroquinone Sodium carbonate (monohydrate) Potassium bromide Water Solution l Cupric chloride (dihydrate) Citric acid 1 Water to make Solution ll 3% aqueous hydrogen peroxide solution.

g l0 g 1 liter.

By this treatment, the emulsion layer of the silver image-having portion and the hydrophilic intermediate layer under the silver image portion were'subjected to etching, and thus when the surface of the plate was lightly rubbed in warm'water at about 30C. the etched portions of the hydrophilic intermediate layer were removed together with the emulsion layer to expose the oleophilic surface of the support. The printing plate thus obtained gave 7000 line-image printed copies having good quality by conducting printing in the same manner as in Example 1. i

- EXAMPLE 4 (illustrates Embodiment 4;

positive-positivev process) After treating the surfaces of a polyethylene terephthalate film having a thickness of 180 microns in, a solution containing sulfuric acid, phosphoric acid, and potassium bichromate, an antihalation layer was applied to one ofthe surfaces and a solution of an alkalisoluble hydrophilic resin having the following composition was'applied tothe opposite surface of the film followed by drying for 2 minutes at C. to form a hydrophilic intermediate layer having a thickness of 0.3

' micron.

Maleic anhydride-vinyl acetate (1 l)-copolymer 1.3 g

. Methanol 45 g Acetone 25 g Methylene chloride 20 g Monochloroacetic acid 10, g Chromium sulfate 0.4 g

Then, a 0.5% sodium alginate solution containing a slight amount of chromium sulfate was applied to the intermediate layer and dried to form a stripping layer (for a negative emulsion layer) having a thickness of 0.2 micron. Thereafter, a direct positive type hardenable silver halide emulsion, (0.5 mole of silver per kg of the emulsion) was applied thereto at.a thickness of 4 microns and dried. Furthermore, a 1% aqueousgelatin solution wasapplied to the silver halide emulsion layer at a, thickness of l micron as a protective layer and Moncmethyl-p-aminophenol sulfate Anhydrous sodium sulfite Hydroquinone Sodium carbonate (monohydrate) Potassium bromide" Water.adde'd to make After washing with water, the plate was immersed for 1 minute at 259C. in an etch-bleach solution prepared by mixing equal amounts of Solutionl and Solution ll having the following compositions:

Solution l Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1 liter.

' -continued Solution ll 3% aqueous hydrogen peroxide solution.

\ EXAMPLE 5 (illustrates Embodiment 5;

positive-positive process) After treating the'surfaces of a polyethylene terephthalate having a thickness of 180 microns with a solution containing sulfuric acid, phosphoric'acid, and potassium bichromate, a solution of an alkali-soluble hydrophilic resin having the following composition was applied to one surface of the film and fried for 2 minutes at 120C. to form a hydrophilic intermediate layer having a thickness of 0.2 micron:

Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol 45 g Acetone 25 g Methylene chloride g Monochloroacetic acid 10 g C hromium sulfate 0.4 g

1 Then, an aqueous gelatin solution containing physical development nuclei having the following composition was applied to the hydrophilic intermediate layer and dried for 60 minutes at 60C. to form a hydrophilic diffusion transfer image receiving layer having a thickness of 0.5 micron. A plate for making printing plates was thus prepared.

Aqueous gelatin dispersion of nickel gelatin 0.5%

, Gelatin 0.6 g

Water 100 g Aqueous 1% solution of sodium dodecylbenzene sulfonate 0.1 g

Aqueous 1% solution of chromium acetate l2 g The plate for printing plates thus prepared was brought into contact with an image-exposed silver halide light-sensitive material, and while applying a developer having the following composition between the two elements, diffusion transfer development was conducted for 30 seconds at C.

Monomethyl-p-aminophenol sulfate Anhydrous sodium sulfite Hydroquinone Anhydrous sodium thiosulfate Sodium hydroxide Water added to make Then, the light-sensitive material was separated from the plate .for. printing plates and after washing the plate with water, the plate was immersed for seconds at 259C. in'an etching solution prepared by mixing equal 5 amounts of Solution la and {Solution 11- having the. following compositions: i

Solution la Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1 liter.

Solution ll 3% aqueous hydrogen peroxide solution.

By the treatment, the silver imageformed in the image receiving layer of the plate was-bleached and at thesame time the silver image portion was etched.

.' Furthermore, at the same time the hydrophilic intermediate layer under the silver image portion was etched by the treatment. Thus, when the surface of the plate was lightly rubbed with a cotton cloth the etched portion of the hydrophilic intermediate layer was removed together with the image receiving layer, and thus the oleophic surface of the support was exposed. The printing plate thus obtained gave 5000 printed copies having a good quality by printing in the same manner as in Example 1.

EXAMPLE 6 (illustrates Embodiment 6; positive-positive process) An antihalation layer was appliedto one surface of a polyethylene terephthalate film having a thickness of 180 microns which had been treated in a solution containing sulfuric acid, phosphoric acid and potassium bichromate and a solution of an alkali-soluble hydrophilic resin having the following composition was applied to the opposite surface of the film followed by drying for 10 minutes at 100C. to form a'hydrophilic intermediate layer having a thickness of 0.3 micron.

Maleic anhydride-vinyl acetate- (1 z 1) copolymer Methanol Acetone Methylene chloride Monochloroacetic acid V Chromium sulfate To the hydrophilic intermediate layer an aqueous gelatin-gum arabic solution containing physical development nuclei having the following composition was applied and dried for 60 minutes at 60C. to form a hydrophilic diffusion transfer image receiving layer having a thickness of 0.5 micron:

Gelatin dispersion of nickel sulfide (same as in Example 5) 0.6 g Gelatin 0.3 g Gum arabic 0.3 g Water 100 g Aqueous 1% solution of sodium dodecylbenzene sulfonate 0.4 g Aqueous 1% solution of chromium acetate 12 g On the image receiving layer there was formed a layer of a panchromatic lithographic unhardenable gelatino silver chlorobromide emulsion silver chloride, 1 mole of silver per kg of the emulsion) so that the dry thickness of the layer became 4 microns.

Furthermore, an aqueous 1% gelatin solution was applied to the silver halide emulsion layer and dried to form a protective layer having a thickness of 1 micron.

The light-sensitive plate for printing plates thus prepared was exposed to a positive original and then developed in a developer having the composition same as in Example 5 for 30 seconds at 20C. The emulsion layer was then removed by washing with water at 30C and then the plate was immersed for 1 minute at 25C in an etch-bleach solution prepared by mixing equal amounts of Solution 1 and Solution 11 having the following compositions:

Solutionl Cupric chloride (dihydrate) g Citric acid 10 g Water added to make 1 liter Solution 11 3% aqueous hydrogen peroxide solution When the surface of the plate was lightly rubbed weakly with a cotton cloth, the image-receiving layer and the etched portion of the hydrophilic intermediate layer were removed to expose the oleophilic surface of the support.

The printing plate thus produced gave 5000 duplications of good quality.

Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol 45 g Acetone 25 g Methylene chloride g Monochloroacetic acid 10 g Chromium sulfate 0.4 g

To the surface of the intermediate layer there was applied an aqueous sodium alginate solution containing physical development nuclei having the following composition and the thus formed layer dried for 60 minutes at 60C to form a hydrophilic diffusion transfer image receiving layer having a thickness of 0.5 micron:

Aqueous elatin dispersion of nickel sulfide 0.4 g

nickel sulfide 5 X 10*% gelatin 0.5% Sodium alginate Water Aqueous 1% solution of sodium dodecylbenzene sulfonate Aqueous 1% solution of chromium acetate moo new To the image receiving layer there was applied an aqueous 1% hydroxyethyl cellulose solution containing a slight amount of chromium sulfate and the solution dried to form a negative emulsion stripping layer having a thickness of 0.2 micron. Then, a panchromatically sensitized lithographic hardenable gelatin silver chlorobromide emulsion (70% silver chloride, 1 mole of silver per kg of the emulsion) was applied thereto at a thickness of 4 microns and dried, and further an aqueous 1% gelatin solution was applied and dried to form a protective layer having a thickness of 1 micron to form a light-sensitive plate for making printing plates.

The light-sensitive plate thus formed was exposed to a color positive original having continuous gradation using a half tone screen at a distance of 1 meter from the light source [Fuji Exposure Lamp (made by Fuji Photo Film Co., Ltd.)] for 2 seconds at 18 volts using a red filter [Fuji Filter SC-62 (made by Fuji Photo Film Co., Ltd.)]. The plate was then developed for 30 seconds at 25C in a developer having the following composition:

l-Phenyl-S-pyrazolidone Anhydrous sodium sulfite Hydroquinone Anhydrous sodium thiosulfate Sodium hydroxide Water added to make The emulsion layer was then removed by washing with water at 30C and the plate was immersed for 1 minute at 25C in an etch-bleach solution prepared by mixing equal amounts of Solution 1 and Solution 11 having the followingcompositions:

Solution 1 Cupric chloride (dihydrate) 10 g Citric acid 10 g Water added to make 1 liter Composition ll 3% aqueous hydrogen peroxide solution By this treatment the image receiving layer of the silver image containing portion and also the stripping layer and the hydrophilic intermediate layer under the silver image portion were etched, and thus when the surface of the plate was lightly rubbed with a cotton pad in warm water at about 30C the etched portions were removed to expose the oleophilic surface of the support. A cyan separate plate of the original was thus prepared.

The cyan separate plate was place on a Davidson 500 Type Offset Machine (made by Davidson & Fairchild Corp.) and printing of 5000 copies was conducted using the ink and wetting water as in Example 1. Thus, the cyan image of the original was obtained as the high quality printed copies having excellent continuous gradation reproducibility. The printing plate thus used showed neither stains or defects on the surface thereof and thus could be used for further printing.

By conducting the same procedure as above, a magenta separate plate, a yellow separate plate and a black separate plate of the original were prepared, and by utilizing the four color separate plates obtained above, 4-color printed copies were obtained.

EXAMPLE 8 Maleic anhydride-vinyl acetate (1 l)copo|ymer 1.3 g Methanol 45 g Acetone 25 g -continued Methylene chloride 20 g Monochloroacetic acid g Chromium sulfate 0.4 g

When the procedures of Example 1 to 7 were applied to the intermediate layer, in each case of Embodiments 1-7 illustrated above 7000 printed copies of excellent quality were obtained.

EXAMPLE 9 Maleic anhydride-vinyl acetate (1 l) copolymer 1.3 g Methanol 45 g Acetone 25 g Methylene chloride g Monochloroacetic acid 10 g Chromium sulfate 0.4 g

To the hydrophilic intermediate layer was applied a gelatino silver chlorobromide emulsion (containing 80% silver chloride, 0.8 mole of silver per kg of the emulsion), 2 g of mucochloric acid and 30 g of hydroquinone to provide a dry thickness of 4 microns, and further an aqueous 1% gelatin solution was applied thereto and dried to form a protective layer having a thickness of 1 micron.

The light-sensitive plate for printing plates was exposed through a microfilm using an enlarger and then the plate was developed for 15 seconds at C in a developer having the following composition:

Anhydrous sodium sulfite 2 Sodium hydroxide 3 Potassium bromide Water added to make EXAMPLE 10 Examples 1 to 7 were repeated except that a resin solution having the following composition was used to form the hydrophilicintermediate layer, and in each case 5000 excellent printed copies were obtained.

Polyvinyl alcohol mixed acetalated by (I) mixed acetal benzaldehyde of polyvinyl alcohol and (ll) sodium salt of benzaldehyde- 2-sulfonic acid (I: 25%, ll: 45%,

and -OH Methanol Acetone Benz l alcohol o-Ch orophenol EXAMPLE 1 1 Examples 1 to 7 were repeated except that a resin solution having the following composition was used to 28 form the hydrophilic intermediate layer. 5000 excellent printed copies were obtained in each case.

Copolymer of 66% diethyl acrylamide and 34% methacrylic acid Methanol Acetone Methylene chloride o-Chlorophenol Chromium acetate EXAMPLE 12 Examples 1 to 7 were repeated except that a resin solution having the following composition was used to form the hydrophilic intermediate layer. 500 excellent printed copies were obtained in each case:

Maleic anhydride-methyl vinyl ether (1 l) copolymer l.5 g Methanol 45 g Acetone 25 g Methylene chloride 23 g Resorcinol 10 g Chromium acetate 0.5 g

EXAMPLE 13 Examples 1 to 7 were repeated except that a resin solution having the following composition was used to form the hydrophilic intermediate layer. 5000 excellent printed copies were obtained in each case:

Examples 1 to 7 were repeated except that a resin solution having the following composition was used to form the hydrophilic intermediate layer. 5000 excellent printed copies were obtained in each case:

Hydroxyethyl cellulose 1.5 g Water 1 g Acetic acid 1 g Phenol 5 g Tetrachloroethane 20 g Methanol 40 g Methylene chloride 10 g Acetone 60 g EXAMPLE 15 Examples 1 to 7 were repeated except that a resin solution having the following composition was used to form the hydrophilic intermediate layer. 5000 excellent printed copies were obtained in each case:

Polyvinyl pyrrolidone-polyvinyl alcohol (6 4) copolymer Water Salicylic acid Methanol Acetone Formalin Resorcinol ulutp meoOOm&N oeunonoeonoetn -continued COMPARISON EXAMPLES 1-3 X I A plate for making printing plates or a light-sensitive plate for makingprinting plates was prepared as in Examples 5-7 except that no hydrophilic intermediate layer was formed, that is to say, the plate for printing plates was produced by coating a polyethylene terephthalate film subjected to a surface treatment with an aqueous gelatin solution containing physical development nuclei and drying for minutes at 120C to form hydrophilic diffusion transfer image receiving layer having a thickness of 0.3 micron. The plates thus produced were exposed and developed as in Examples 5-7. However, when the negative materials were separated from the developed plates the hydrophilic diffusion transfer image receiving layers were also stripped from the polyethylene terephthalate film s, and thus the plates could not be used as printing plates.

COMPARISON EXAMPLES 4-6 Polyester 0.7 g Nitrocellulose l .0 g Ethylene dichloride 150.0 g Acetone 50.0 g Methanol l 3 .0 g Tetrachloroethane l 5.0 g

The polyester was prepared by reacting a mixture of 1 mole of dimethyl terephthalate, 1.5 moles of ethylene glycol. and 1 mole of triethylene glycol.

An aqueous gelatin solution containing physical development nuclei (the same as was used in Examples 5-7) was applied to the surface of the intermediate layer and dried for 60 minutes at 60C to form a hydrophilic diffusion transfer image receiving layer having a thickness of 0.5 micron. The plate for printing plates thus produced was exposed and developed in the same manner as in Examples 5-7. In the printing plate thus prepared the intermediate layer had not been sufficiently etched and thus printing ink did not attach to the image portions, which made it impossible to use the printing plate for printing.

From the above comparison examples, the remarkable merits of the hydrophilic intermediate layers formed according to the present invention will be well understood.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

What is claimed is:

l. A method of making a lithographic printing plate from a plate comprising a support having an oleophilic surface bearing thereon a hydrophilic intermediate layer containing at least one compound selected from the following groups A, B and C:

Group A: gum arabic, alginic acid, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, polyacrylamide, polyvinyl pyrrolidone, co-

polymers of the above components, polyvinyl alcohol, and apolyvinyl alcohol derivative;

Group B: a maleic anhydride-vinyl acetate copolymer, a maleic I anhydride-ethylene copolymer, a maleic anhydride-methyl vinylether copolymer, a maleic anhydride-styrene copolymer, half ester derivatives of those copolymers, half amide derivatives of those copolymers, an acrylic acid copolymer, and a methacrylic acid copolymer; and

Group C: partially saponified cellulose acetate, partially saponified cellulose butyrate, and partially saponified cellulose acetate butyrate;

said intermediate layer bearing thereon a photosensitive silver halide emulsion layer a; or

a hydrophilic diffusion transfer image receiving layer (b) containing physical development nuclei, or

a layer b carrying thereon a silver halide emulsion layer a on the side thereof away from the hydrophilic intermediate layer, which method comprises:

forming a silver image in layer a or b,

removing layer a when it is present on layer b, and

etch bleaching the silver image, thereby etching away layer a or b at silver image portions thereof and at the same time the hydrophilic intermediate layer under the silver image portions thereof to thereby expose the oleophilic surface of the support at portions corresponding to the silver image portions in layer a or b.

2. A method as claimed in claim 1, wherein the degree of saponification of the materials of Group C is less than 2%.

3. A method as claimed in claim 1, where the photosensitive silver halide emulsion layer has a thickness of from 1 to 15 microns.

4. A method as claimed in claim 1, wherein the photosensitive silver halide emulsion layer comprising at least one silver halide and a binder present at a ratio of from l/4 to 6/1.

5. A method as claimed in claim 1, wherein the hydrophilic diffusion transfer image receiving layer has a thickness of from 0.1 to 3 microns.

6. A method as claimed in claim 5, wherein the hydrophilic diffusion transfer image receiving layer comprises physical development nuclei and a binder, the ratio of nuclei/binder being from 0.1/1 to 0.001/1.

7. A method as claimed in claim 1, wherein said plate further comprises a stripping layer between the photosensitive silver halide emulsion layer and a layer thereunder.

8. A method as claimed in claim 1, wherein both the photosensitive silver halide emulsion layer and the hydrophilic diffusion transfer image receiving layer are present.

9. A method as claimed in claim 1, wherein the compound is selected from Group A.

10. A method as claimed in claim 1, wherein the compound is selected from Group B.

11. A method as claimed in claim 1, wherein the compound is selected from Group C.

12. A method as claimed in claim 1 where said hydrophilic intermediate layer is substantially free of physical development nuclei.

13. A plate as claimed in claim 1 where said hydrophilic intermediate layer is substantially free of physical development nuclei.

14. A method as claimed in claim 1, wherein the hydrophilic diffusion transfer image receiving layer 31 containing physical development nuclei has a thickness of from 0,1 to 3 microns, wherein the hydrophilic intermediate layer has a thickness of from 0.1 to 3 microns, whereinthe amount of silver formed in the image receiving layer (b) is greater than 0.3 in optical density, 5

wherein the thickness of the silver halide-emulsion layer is from about l to about microns, wherein the weight ratio of silver halide to binder of the emulsion layer is in the range of about 1/4 to 6/1, wherein the

Claims

1. A METHOD OF MAKING A LITHOGRAPHIC PRINTING PLATE FROM A PLATE COMPRISING A SUPPORT HAVING AN OLEPHILIC SURFACE BEARING THEREON A HYDROPHILIC INTERMEDIATE LAYER CONTAINING AT LEAST ONE COMPOUND SELECTED FROM THE FOLLOWING GROUPS A, B AND C: GROUP A: GUM ARABIC, ALGINIC ACID, HYDROXYETHYL CELLULOSE, METHYL CELLULOSE, CARBOXYMETHYL CELLULOSE, POLYACRYLAMIDE, POLYVINYL PYRROLIDONE, COPOLYMERS OF THE ABOVE COMPONENTS, POLYVINYL ALCOHOL, AND A POLYVINYL ALCOHOL DERIVATIVE; GROUP B: A MALEIC ANHYDRIDE-VINYL ACETATE COPOLYMER, A MALE;IC ANHYDRIDE-ETHYLENE COPOLYMER, A MALEIC ANHYDRIDE-METHYL VINYLETHER COPOLYMER, A MALEIC ANHYDRIDESTYRENE COPOLYMER, HALG ESTER DERIVATIVES OF THOSE COPOLYMERS, HALF AMIDE DERIVATIVES OF THOSE COPOLYMERS, AN ACRYLIC ACID COPOLYMER, AND A METHACRYLIC ACID COPOLYMER; AND GROUP C: PARTIALLY SAPONIFIED CELLULOSE ACETATE, PARTIALLY SAPONIFIED CELLULOSE BUTYRATE, AND PARTIALLY SAPONIFIED CELLULOSE ACETATE BUTYRATE; SAID INTERMEDIATE LAYER BEARING THEREON A PHOTOSENSITIVE SILVER HALIDE EMULSION LAYER A; OR A HYDROPHILIC DIFFUSION TRANSFER IMAGE RECEIVING LAYER (B) CONTAINING PHYSICAL DEVELOPMENT NUCLEI, OR A LAYER B CARRYING THEREON A SILVER HALIDE EMULSION LAYER A'' ON THE SIDE THEREOF AWAY FROM THE HYDROPHILIC INTERMEDIATE LAYER, WHICH METHOD COMPRISES: FORMING A SILVER IMAE IN LAYER A OR B, REMOVING LAYER AZ WHEN IT IS PRESENT ON LAYER B, AND ETCH BLEACHING THE SILVER IMAGE, THEREBY ETCHING AWAY LAYER A OR B AT SILVER IMAGE PORTIONS THEREOF AND AT THE SAME TIME THE HYDROPHILIC INTERMEDIATE LAYER UNDER THE SILVER IMAGE PORTIONS THEREOF TO THEREBY EXPOSE THE OLEOPHILIC SURFACE OF THE SUPPORT AT PORTIONS CORRESPONDING TO THE SILVER IMAGE PORTIONS IN LAYER A OR B.

4. A method as claimed in claim 1, wherein the photosensitive silver halide emulsion layer comprising at least one silver halide and a binder present at a ratio of from 1/4 to 6/1.

14. A method as claimed in claim 1, wherein the hydrophilic diffusion transfer image receiving layer containing physical development nuclei has a thickness of from 0.1 to 3 microns, wherein the hydrophilic intermediate layer has a thickness of from 0.1 to 3 microns, wherein the amount of silver formed in the image receiving layer (b) is greater than 0.3 in optical density, wherein the thickness of the silver halide emulsion layer is from about 1 to about 15 microns, wherein the weight ratio of silver halide to binder of the emulsion layer is in the range of about 1/4 to 6/1, wherein the amount of silver of the silver halide in the emulsion layer is from about 5 to about 60 mg/dm2, wherein the weight ratio of nuclei to binder of the image receiving layer (b) is from about 0.1/1 to about 0.001/1 and the total nuclei content is at least about 0.001 mg/dm2, and wherein the hardenability of the hydrophilic intermediate layer is such that it can be etched by means of an etch-bleach bath.