US3694208A

US3694208A - Production of photographic images or printing plates utilizing polyimides

Info

Publication number: US3694208A
Application number: US85811A
Authority: US
Inventors: Erwin Ranz; Harald Von Rintelen; Heinz-Dieter Schuetz; Gerhard Mueller; Wolfram Neumann
Original assignee: Agfa Gevaert AG
Current assignee: Agfa Gevaert AG
Priority date: 1969-11-06
Filing date: 1970-10-30
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26
Also published as: BE757908A; FR2082966A5

Abstract

PROCESS FOR THE PRODUCTION OF PHOTOGRAPHIC IMAGES OR PRINTING FORMS USING LIGHT SENSITIVE LAYERS WHICH ARE FREE FROM SILVER HALIDE AND CONTAIN CYCLIC POLYAMIDES ACCORDING TO GERMAN PATENT (P 15 22 385.5) WHEREIN THE PHOTOGRAPHIC MATERIAL IS IMAGEWISE EXPOSED AND HEATED TO A TEMPERATURE OF BETWEEN 100*C. AND 200*C. AND THEN IS UNIFORMLY EXPOSED. THE PROCESS IS BASED ON THE FINDING THAT THE COLOURED RADICAL IMAGE SUBSTANCE FORMED BY IMAGEWISE EXPOSURE IS IRREVERSIBLY CONVERTED INTO COLOURLESS OR ALMOST COLOURLESS COMPOUNDS BY HEATING THEM TO 100*C. TO 200*C.

Description

United States Patent 3,694,208 PRODUCTION OF PHOTOGRAPHIC IMAGES OR PRINTING PLATES UTILIZING POLYIMIDES Erwin Ranz, Harald von Rintelen, Heinz-Dieter Schutz,

Gerhard Muller, and Wolfram Neumann, Leverkusen,

Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany No Drawing. Filed Oct. 30, 1970, Ser. No. 85,811

Claims priority, application Germany, Nov. 6, 1969,

P 19 55 751.8 Int. Cl. G03c 3/24 US. CI. 96-48 HD 5 Claims ABSTRACT OF THE DISCLOSURE Process for the production of photographic images or printing forms using light sensitive layers which are free from silver halide and contain cyclic polyamides according to German patent (P 22 385.5) wherein the photographic material is .imagewise exposed and heated to a temperature of between 100 C. and 200 C. and then is uniformly exposed. The process is based on the finding that the coloured radical image substance formed by imagewise exposure is irreversibly converted into colourless or almost colourless compounds by heating them to 100 C. to 200 C.

The invention relates to a process for the production of photographic images or printing forms using light sensitive layers which are free from silver halide and contain cyclic polyimides.

Photographic materials are known which contain as light sensitive compounds cyclic naphthalene carboxylic acid diimides.

These compounds very rapidly become dark on exposure to light, especially to UV light, and so provide a very simple method of obtaining photographic images by a completely dry process. Photographic materials of this type have been described in US. Pat. specification 3,533,798.

To produce stable photographic images, it is necessary to fix the photographic images which are obtained by rendering the light sensitive cyclic polyimides insensitive to light in the unexposed areas of the layer. This is to be achieved e.g. by the action of reagents which react with unsaturated double bonds or have for example a ring opening effect on cyclopropane rings. Reagents which react with unsaturated double bonds are among others halogens such as bromine, chlorine or iodine, halogen hydroacids such as hydrogen chloride or hydrogen bromide, ozone, peroxy acids or hydrogen, sulphenyl chlorides or sulphur dichloride and potassium permanganate. Conversion of the light sensitive cyclic polyimides into compounds which are insensitive to light can also be achieved by degrading the imido group, e.g. by hydrolysis into polyamido carboxylic acid or by aminolysis into polyamides. Separation of the light sensitive cyclic polyimides into exposed and unexposed portions can also be achieved by selectively dissolving out the one component with suitable solvents.

Negative images of the original are obtained by this process. stabilising the images obtained on exposure of such photographic materials is a relatively complicated process. Moreover, it is not possible to produce reversal images by the process described above.

It is an object of the invention to provide a simple method of stabilising photographic materials containing cyclic naphthalene carboxylic acid diimides and to modify the process hitherto known so that direct positive images can be produced.

3,694,208 Patented Sept. 26, 1972 We now have found a process for the production of photographic images by exposing and stabilising a light sensitive photographic layer which contains as light sensitive compound a cyclic polyimide of the formula in which R is a 2n-valent mononuclear or polynuclear condensed aromatic radical, e.g., a radical of the phenylene, naphthylene or perylene series, preferably a phenyl or naphthyl radical, which may be substituted, e.g. with an alkyl radical, in particular an alkyl having up to 5 carbon atoms such as methyl, ethyl or propyl, with halogen such as chlorine or bromine, nitrile or alkoxy, in particular alkoxy having up to 5 carbon atoms, and the like;

R' is an olefinically unsaturated linear or cyclic radical,

in particular an unsaturated aliphatic radical containing up to 8 carbon atoms, e.g. allyl, butenyl or pentenyl, cyclohexenyl or cyclopentenyl or a dihydropyran radical, the cyclic radicals being attached to the nitrogen atom either directly or through an alkylene bridge having up to 3 carbon atoms; R may also represent S-membered or 6-membered rings which contain a cyclopropane group and which preferably have an endomethylene structure, e.g. a ring of the tricyclene series;

n represents 2 or 3, preferably 2;

in which the photographic material is imagewise exposed and heated to a temperature of between C. and 200 C. and then is uniformly exposed.

The process according to the invention is based on the finding that the coloured radical image substance formed by imagewise exposure is irreversibly converted into colourless or almost colourless compounds by heating them to 100 C. to 200 C. The following compounds exhibit particular utility:

lCO 0-C4H9 oCt-OCO H000 CO-NH HNCO -COOH -@r N I N I l H H l I VII 0 O f K33 M ed QW The light sensitive cyclic aryl polyirnides in the unexposed areas of the layer are not influenced by this heating. The light sensitive substance in the areas which have not previously been exposed is then coloured dark by a uniform after-exposure to actinic light, preferably UV light. Since the areas which were originally exposed are now pale, a direct positive image of the original is obtained. The reversal images obtained in this way are stable in ordinary daylight.

The light-sensitive cyclic aryl polyimides and their open chain primary products which are not sensitive to light are suitable for the process according to the invention. These primary products can be converted into the light 4 sensitive compounds by a certain preliminary treatment as described in the US. Pat. specification 3,533,798.

The process according to the invention may also be used for such photographic materials of the above US. Pat. specification which contain as accelerator for the conversion reaction an isourea derivative of the formula in which R is alkyl, cycloalkyl or aryl, R is hydrogen or R, R is alkyl with up to 5 carbon atoms and R is R.

For the preparation of the light sensitive compound, the methods given in US. Pat. specification 3,533,798 for production of the layers and processing are applicable.

The process according to the invention can be used for producing offset foils which can be processed dry because the physical properties of the layer are altered imagewise by heating the imagewise exposed material to a temperature of between about 100 C. and 200 C. and then uniformly exposing the material to ultraviolet light. Even with the naked eye it can be seen that after the subsequent exposure with ultraviolet light, the areas of imagewise exposure are highly glossy and the other parts of the layer are matt. In addition, the wetting properties have been altered in that the glossy areas which have been exposed imagewise have become hydrophobic and readily take up fatty printing dyes. The other areas of the layer are more hydrophilic and repel printing dyes. The images produced by this method can therefore be used immediately as printing forms for offset printing.

The differences in the wetting properties can be still further increased by additional measures. Thus, the light sensitive substances, with or without binder, may be applied to a strongly hydrophilic layer support such as suitably coated paper. After the layer has been heated and then exposed to UV light, the parts of the layer which are already hydrophilic can easily be removed by rubbing with a moist cloth or sponge, thereby exposing the highly hydrophilic surface of the layer support. Surprisingly, the imagewise exposed parts of the layer adhere much more firmly to the support and are therefore not removed by rubbing. These effects can be reinforced as desired by suitably modifying the light sensitive layers. The offset foils produced in this way can be used for the offset process in the usual manner.

EXAMPLE 1 Preparation of the light sensitive layer 5 g. of Compound VI dissolved in 300 ml. of chloroform are mixed with 200 ml. of a 20% polyvinylacetate solution in chloroform, applied to a paper support and dried.

Processing-The layer is exposed to a mercury vapour lamp Osram HQA (400 watt) behind a continuous tone original (silver image). Exposure time is 30 seconds to 1 minute at a distance of 30 cm. A dark positive image of the original with excellent reproduction of the continuous tones is obtained.

Similar results are obtained, for example, when using Compound I in the same way.

The picture is then heated in a heating cupboard at 200 C. for seconds either immediately or at any time after exposure. The colour of the radical image substance disappears almost completely on heating. During the subsequent after exposure to diffuse light (30 seconds, 30 cm. distance) from the mercury vapour lamp used for the imagewise exposure, the coloured radical image substance appears in those areas of the sample which were not exposed during the imagewise exposure. The imagewise exposed areas which had become pale as a result of the heating to 200 C. are not changed during the subsequent diffuse exposure.

A high contrast reversal image which is stable in daylight is obtained.

EXAMPLE 2 A high contrast reversal image which is stable in dayon a hydrophilic paper support. It is exposed imagewise to a UV lamp as described in Example 1. It is then heated at 200 C. for 2 minutes. After subsequent diffuse exposure to UV or daylight, the image areas are highly glossy and the surroundings are matt. By gently rubbing with a wad of cotton wool steeped in alcohol, the binder is completely removed from those areas (matt) which were not exposed imagewise.

When this layer is used as master in an oifset printing apparatus, oil dye is taken up by those areas which are relatively hydrophobic. Offset prints of high quality are obtained.

What we claim is:

1. The production of photographic images by imagewise exposing a layer of supported light sensitive material which comprises a light sensitive polyimide of the formula ll R NR' in which R is a 2nvalent, mononuclear or polynuclear aromatic radical; R is either (1) an olefinically unsaturated linear aliphatic radical, (2) an olefinically unsaturated cyclic aliphatic radical linked to the nitrogen either directly or through an alkylene chain or (3) a 5 or 6 membered ring which comprises a cyclopropane grouping and n is 2 or 3, t for the production of an image of a colored radical image of a colored radical image substance, heating the exposed layer to a temperature in the range of 100-200 C. to convert in the imagewise exposed areas the colored radical image substance to a substantially colorless light-insensitive compound and uniformly exposing said treated layer to form a positive photographic image by coloring said light sensitive polyimide. 2. A process for the production of printing forms for offset printing which comprises imagewise exposure of a photographic photosensitive hydrophillic layer on a support comprising a light sensitive polyimide of the formula 0 it B N-R ll in which R is a 2n-valent, mononuclear or polynuclear aromatic radical;

R is either (1) an olefinically unsaturated linear aliphatic radical, (2) an olefinically unsaturated cyclic aliphatic radical linked to the nitrogen either directly or through an alkylene chain or (3) a 5 or 6 membered ring which comprises a cyclopropane grouping and n is 2 or 3, forming a colored radical image substance in said hydrophillic layer by said imagewise exposure, heating the hydrophillic layer to a temperature between and 200 C. to convert the image substance to a substantially colorless light insensitive compound, and uniformly exposing the treated layer to produce hydrophobic imagewise exposed areas and the remaining areas of said printing form being less hydrophobic. 3. A printing form for offset printing produced in accordance with the process of claim 2.

4. A process as claimed in claim 1 in which R is an olefinically unsaturated cyclic radical.

5. A process as claimed in claim 1 in which the polyimide used is one of the compounds of Formulae I to XIV illustrated herein.

References Cited UNITED STATES PATENTS 3,533,798 10/1970 Muller et al 96-90 OTHER REFERENCES Advanced Organic Chemistry by Fieser and Fieser, Reinhold Publishing Co. New York, 1965 at page 24.

NORMAN G. TORCHIN, Primary Examiner W. H. LOUIE, JR. Assistant Examiner US. Cl. X.R. 96-90, 33