FR2477296A1 - Ultraviolet-sensitive photographic materials - based on acidic cellulose ether(s) or ester(s) - Google Patents

Abstract

Photographic materials comprise a light-sensitive cellulose deriv. (I) selected from acidic cellulose ethers and esthers their copolymers with synthetic monomers. The materials can be used to produce outline or halftone images, e.g. of engineering drawings or advertisements, in UV light without interference from scattered visible light. They have good thermal, chemical and storage stability, and produce images with good resolution and contrast.

Description

The present invention relates to the photographic products industry and in particular relates to a photographic material containing no silver and making it possible to obtain a developed image composed of metal particles.

 The invention may be used in the photographic products industry, in particular for obtaining line and halftone images on paper, films and fabrics. The photographic material which is the subject of the present invention can be used in particular for obtaining copies of industrial designs in the mechanical industry, as well as advertising posters. The photographic material in question may be used in instruments making photographic recordings and provided with sources of ultraviolet radiation, or else for the direct recording of ultraviolet radiation.

 There are already known a very large number of photographic materials with silver halides, executed in the form of a photosensitive layer applied to a support.

Due to the multiplicity of the constituents of the photosensitive layer, these known materials are characterized by a heterogeneous distribution of the structural photosensitive elements on the surface of the support, which results in an excessive "grain" of the image. In the wet state and at high temperature, the photosensitive layer is easily detached from the support. In addition, known silver halide photographic materials are incapable, without the use of special reagents, of recording radiation in the far ultraviolet, because of the strong inactive absorption (parasite) of said radiation by the gelatin of the photosensitive layer.

On the other hand, there were photographic materials on which images are obtained by photopolymerization processes or chemical transformations of polymers. However, these known photographic materials are complicated to manufacture, require the use of costly and costly reagents, and the image which in many cases consists of organic dyes is poorly preserved over time. In addition, the known materials are, in the majority of cases, heterogeneous systems and their resolving power is limited by the heterogeneity of the entire system (United States patent
NOs 3 368 900, 3 259 499, FRG patent NO 2 118 609).

A homogeneous photographic material is known which is derived from monocarboxylcellulose and which is an anhydro-glucose-anhydro-uronic acid copolymer. Under the action of ultraviolet radiation on this photographic material, there is an effect of formation of latent image centers which can be made visible by the action of a physical developer (USSR author's certificate NO 244888) .

A photographic material of this kind has a better resolving power than that of known heterogeneous photographic materials. However, a disadvantage of this homogeneous material derived from cellulose is its low sensitivity to light, its instability in storage over time, its low physicomechanical indices in the presence of chemical and thermal actions (in case of treatment with alkaline liquors, if heated). Besides this, obtaining a photographic material of this kind is linked to the use of toxic products such as nitrogen oxides.

 The object of the present invention is to eliminate the aforementioned drawbacks.

It has therefore been proposed to create a homogeneous photographic material based on cellulose modified with reagents such that the photosensitivity of the material is increased and that the stability of said material during its conservation is improved.

 This problem is solved in that the photographic material composed of modified photosensitive cellulose, consists, according to the present invention, of acidic esters (ethers-oxides) of cellulose or of copolymeric esters (ethers-oxides) of cellulose acids - synthetic comonomers .

The use of cellulose acid esters (ethers-oxides) or of cellulose ethers (ethers-oxides) cellulose acids - synthetic comonomers makes it possible to obtain a photographic material having improved sensitivity, having stability in storage. , as well as resistance to thermal and chemical effects. The homogeneous structure of the photographic material, object of the invention, ensures the absence of a marked grain of the image and a very high resolution power, which is essentially limited only by the texture of the material. of the material in question on the highly productive material currently used in the production of known polymeric materials (such as paper, films) makes it possible to exclude complicated and expensive processes for obtaining layers of photosensitive emulsions and their application on the support. the photographic material, object of the invention, makes it possible to obtain the image without playing with the silver metal. In addition, an indisputable advantage of said material lies in its use and its treatment (for visualization) with light, since it is only sensitive to the ultraviolet part of the spectrum.

 According to the invention, it is advantageous that the acidic cellulose ester is a carboxymethylcellulose. The use of carboxymethylcellulose makes it possible to obtain a photo-sensitive material having a relatively high sensitivity in the ultraviolet part of the spectrum, going hand in hand with an absence of sensitivity in the visible part of the spectrum, which explains the promising nature of the new photographic materials. subject of the present invention for the recording of ultraviolet rays in the presence of diffuse visible light, the existing materials intended for the recording of the ultraviolet part of the spectrum often having a higher sensitivity in the visible part than in the part at short wavelengths of the spectrum.

 It is advantageous, according to the invention, that the acidic esters (ethers-oxides) of cellulose contain, together with the carboxyl groups, acetyl groups. This embodiment of the invention makes it possible to obtain photographic films by chemical modification of the cellulosic materials delivered industrially, by one. Any imposed thickness, stable over time. A photographic material based on cellulose acid ester (6ther-oxide) containing, in addition to the carboxyl groups, acetyl groups, can be used as a negative. It should be noted that the negatives obtained on new photographic materials can be used (without additional procedures) for printing on photographic materials derived from silver halides with the use of known apparatus. Conversely, to obtain copies from negatives based on materials derived from silver halides and other known materials, it is possible to use the photographic material which is the subject of the present invention, using the same methods as those currently applied, except that the support for the coating and the emulsion layer must be transparent in the ultraviolet part of the spectrum, and that the light source must emit ultraviolet rays.

To increase the resistance to fire and heat of photographic materials, thus allowing their use in large-scale advertising, it is advantageous, according to the present invention, to use as cellulose acid ester a cellulose phosphate.

 In order to widen the spectral sensitivity range of the materials and to increase their overall photosensitivity, it is advantageous to use, according to the present invention, salts of acid esters and acidic cellulose ether oxides. The use of silver, platinum, palladium, iron, bismuth, lead salts makes it possible to use a single bath development process by reduction, which considerably simplifies the technological process of obtaining an image on photographic matter.

When, according to the present invention, as the salts of esters and acid ether oxides of cellulose, salts of iron, bismuth or lead, it is possible to use as a developer a product based on copper and formaldehyde, which makes it possible to avoid using precious metals at all stages of the photographic process and to obtain a low cost price for photographic materials
According to another embodiment of the present invention, the photographic material is applied to a support. This opens up possibilities for the use of esters and of acidic cellulose ether ethers in the form of powders, with their subsequent application on a solid support. .

 Other characteristics and advantages of the invention will be better understood on reading the detailed description which follows of various nonlimiting embodiments of the invention.

 According to the present invention, there is provided a photographic material obtained from esters or ethers of cellulose acid ethers, or copolymers of esters or ethers of cellulose acid ethers and synthetic monomers. The research carried out has made it possible to demonstrate that the acidic esters and ethers-oxides of cellulose show sensitivity to the effects of ultraviolet radiation and form metastable centers of excess latent image electrons.

As the experimental researches have shown, it is possible to use as pbographic materials ethers-oxides and cellulose esters varied from the point of view of their structure, containing acid groups carboxylic esters held carboxymethyl-cellulose, esters of cellulose with malic, citric, tartaric, glutaric, ethylenediaminetetraacetic, maleic, phthalic, adipic, succinic acid, cellulose acid esters with polybasic inorganic acids, noted with phosphoric acid, sulfuric acid.

 As is known, the cellulose esters which are the subject of the present invention are obtained by the action of acid esterifying reagents on the cellulosic material. By varying the reagent concentrations, the time and temperature regimes of the treatments, it is possible to obtain acidic cellulose esters with varied content of acidic groups. The content of acidic groups in the photographic material is from 0.3 to 17% by weight.

Thus, for example, carboxymethylcellulose is obtained by causing monochloroacetic acid to act on alkaline cellulose

Sulfoethylcellulose is obtained by causing sodium chloroethylsulfonate or bromoethylsulfonate to act on the cellulose in an alkaline medium.

R being a cellulose residue.

Cellulose citrates are obtained by impregnating a cellulosic material with a 20% solution of citric acid, drying it and subjecting it to a treatment.

R being a cellulose residue.

The phosphoric acid esters of cellulose are obtained by acting by heating aqueous liquors of orthophosphoric acid and urea on the cellulose:

R being a cellulose residue.

 The use of carboxymethylcellulose makes it possible to obtain a photographic material having a relatively high sesibility in the ultraviolet part of the spectrum with an absence of sensitivity in the visible part of the spectrum, which allows the use of new photographic materials conforming to the invention for recording ultraviolet rays in the presence of diffuse visible light.

It has been found, according to the present invention, that the acidic ethers of cellulose containing, together with the carboxyl groups, acetyl groups, are endowed with sensitivity to the ultraviolet part of the spectrum. This makes it possible to obtain photographic films by chemical modification of the cellulosic materials produced industrially. The photographic material based on an acidic ether oxide of cellulose containing, together with carboxyl groups, acetyl groups can be used as a negative for the printing on photographic materials based on silver halides and on other known graphic photo materials
found that by using cellulose phosphate esters of cellulose phosphates it was possible to improve the fire and heat resistance of photographic materials.

The use, as photosensitive materials of copolymers of cellulose acid esters and of synthetic comonomers improves the physico-mechanical indices of said material, in particular its tensile breaking load, its resistance to corrosive environments.

Thus, the use of the cellulose phosphate-polyacrylonitrile copolymer makes it possible to obtain a photographic material having an improved resistance to the alkaline environment.

The choice of synthetic comonomers depends on the optical characteristics, above all on the absorption and diffusion in the ultraviolet, as well as peculiarities of the chemical treatment, on the efficiency of the diffusion of the aqueous solutions in the mass of the polymer. For this reason, according to the prescriptions laid down for a given photosensitive material, it is possible to use as comonomers products of various hydrophilic characteristics, different aptitudes for iibibition and manifesting different optical properties.

 As it follows from the above, obtaining cellulose esters (ethers-oxides) is easily carried out, and in this way the preparation of the photographic material according to the invention excludes a complicated and expensive process for the preparation of a photosensitive emulsion and its application on a support, which is essential for the production of known photographic materials.

An essential advantage of the photographic material that is the subject of the invention lies in the possibility of producing it, using it and processing it in daylight.
Since the property of forming a latent image is specific to cellulose acid esters (ethers-oxides) and not to additives, new photographic materials can be produced in any physical form in which it is possible to obtain the articles in cellulose: films, papers, fabrics, threads, emulsions. Furthermore, said photographic materials can be photosensitive either in their entire volume (in the case of materials free of support), or at any imposed depth.

During the study of photochemical transformations of cellulose acid esters (ethers-oxides) under the action of ultraviolet rays, we discovered the effect of the formation of a latent image which can be demonstrated by physical development.
It should be observed that, for all the acidic esters (ethers-oxides) of cellulose, Hitherto, their general property was not known to form, under the effect of ultraviolet radiation, metastable centers with excess of latent image electrons, capable of being developed chemically with reinforcement.

 For some of the acidic esters (ethers- oxides) of cellulose, photosensitivity is known which makes it possible to obtain an image using photopolymerization, photodegradation, thermoplastic recording methods, etc. The visible image for materials of this kind is most often manifested in the form of reliefs (bosses) formed either under the effect of differences in swelling or solubility in the exposed or unimpressed areas, or by modification of the physical characteristics of matter impressed due to physical actions on the Impressed material (by heating or by application of an electric charge bubble image, thermoplastic recording or electrography). To achieve photosensitivity in photographic systems of this type, it is essential to have links - C = C - polarized by neighboring groups (like carbonyls), azides or diazo creating photosensitivity.

 The property discovered by the authors of the present invention practically does not depend on the presence or on the absence, within the polymer, of - C - C - bonds of diapo groups, of pyridine residues; of bridged bonds, of thermoplastic properties, of capacity for photopolymerization. In the case under consideration, these properties do not have a decisive influence on the formation of the image, since the formation of the latent image during exposure of cellulose acid esters (ethers- oxides) is entirely determined by the presence of acid groups, and not only carboxyl groups, as shown by experimental research, but also of acid residues of any type .

This property of the cellulose acid esters and ethers is specific to these compounds not only in the form of acids but also in the form of salts, in particular salts of silver, platinum, palladium, iron, bismuth, lead. Furthermore, the use of certain saline forms of cellulose acid esters (ethers-oxides) (palladium, silver salts) makes it possible to carry out the chemical treatment without using a physical developer, born only under the action of reducer solutions, analogous to the development of silver halide materials.

When iron, bismuth, lead salts are used as the acidic ester (ether-oxide) salts of cellulose, it is possible to use as a developer a copper and fora aldehyde developer, it is that is to say to exclude the use of precious metals at all stages of the photographic process, which allows them to be obtained inexpensively.

 The acidic cellulose esters (ethers-oxides) which are produced industrially, such as carboxymethylcellulose, sulfocellulose, in the form of powders, can also be used for obtaining photographic materials by inclusion of small particles of esters (ethers-oxides) cellulose acids in the composition of gelatin films or the manufacture of emulsion layers from isolated particles of cellulose acid ester (ether-oxide) distributed in polyvinyl alcohol, and its application to a solid support (glass, wood, metal, film or yarn "before trade name of a polyester terephthalic material). It is possible to apply cellulose acid esters (ethers-oxides) on a support with an adhesive layer.

New photographic materials can be impressed with various types of mercury vapor quartz lamps. The exposure time, in this case, can be of the same order of magnitude as in the case of the use of known photographic materials impressed by visible light.

 When the photographic materials of the present invention are impressed with ultraviolet light, a latent image is obtained which is subjected to a chemical treatment during which the metal is deposited by the exposed areas.

It is possible to carry out the chemical treatment of materials based on cellulose acid esters and ethers-oxides by means of a physical development which includes the execution of a sorption with exchange (before or after exposure to radiation) metal cations capable of reduction and with subsequent reduction with formation of the visible image comprising metal particles inserted within the material. In the case of such chemical treatment of the photographic material, the visualization of the image intervenes not directly because of the products of the primary photochemical process or the subsequent physical or chemical actions, as a result of which an image composed of the material of the polymer itself or of the products of the photolytic process is obtained, but thanks to the image centers which act as a catalyst in the reactions which result in the formation of the visible image.

The image in this case is formed from particles either of precious metals such as silver, palladium, or of metals such as copper, cobalt, nickel. It is important to note that even when precious metals are used, significant savings can be achieved by lowering their specific consumption (10-5 to 10-7 g / cm2).

The image obtained on new photographic materials is extremely stable, because the substance which forms the image, that is to say the metal particles, is inserted into the photographic material which simultaneously serves as support and vector. In photographic materials with silver halides and other kinds of photographic materials, the image which is obtained in the gelatin layer is in an easily separable state in case of wet treatment and under mechanical effects, it degrades in the presence moderate heating as observed in the case of thermoplastic recording.

 The developed image obtained on the photographic material produced in cellulose acid esters (ethers-oxides) is stable to bleaching and other mechanical actions. After obtaining the developed image, the photographic material is easily tinted by current methods, it being understood moreover that its aptitude for tinting is better than the tinting of an unmodified cellulose canvas . The metal particles distributed within each filament reduce the degree of electrification.

 The stability of the image over time depends on the storage stability of the metal whose particles make up the image. In a certain number of cases, the image is stable if it is made up of metal particles which are resistant to conservation (in particular silver).

 It should be noted that the photographic materials of the present invention in the undeveloped state can be easily regenerated for reuse, which is essential in cases where it is important to make a long-term photographic recording of a developing process. only the interesting part of the documesstation that was photographed. Several known materials (except electrophotographic materials or materials intended for thermoplastic recording) cannot be regenerated after exposure.

 The conservation of the acid groups in the composition of the photographic material after the chemical treatment gives the possibility of reusing the material after development.

After the elimination of the visible image, it is possible to carry out the exposure and the chemical treatment of the photographic material. This allows, if necessary, to obtain images by composite printing, to make corrections, to print new images in the unimpressed or poorly impressed areas.

As for most known photographic materials, they lose their sensitivity to light after development.

Example 1.
The carboxytnCthylcellulose is obtained by treatment of the cellulose with a 30% alkaline solution for 30 minutes at a temperature of 2 to 30C, followed by its admission into the reactor where a solution of monochloroacetic acid is poured then the reaction mass is stirred for 18 minutes in the cold, it is heated to 70 ° C. and kept at this temperature for 50 minutes then the product is washed and a sheet of paper is poured, to obtain the product in cycle H (form H), the paper is treated with a 0.1 N solution of formic acid for one hour. The carboxymethylcellulose obtained is impressed by ultraviolet rays (full spectrum of a mercury vapor quartz lamp) of which the luminous flux intensity is 4.3.1016 quanta / cm2.s 0 Then the material is developed in a physical developer which consists of two solutions
1. 0.1 N AgNO3
2. phenidone-hydroquinone developer.

After development, the samples are fixed in an ordinary fixing medium. The developed image is colored in brown whose intensity increases with the exposure time o The optical densities of the carboxymethylcellulose impressed in the event of development with the developer with phenidone-hydroquinone according to the duration of the exposure time are as follows
exposure time, minutes 1 4 8 12
optical density 0.20 0.59 0.64 0.89
The gradation characteristics of the material are as follows
useful interval of exposure times 1.2
average gradient 0.7-;
maximum optical density 0.9
optical density of the web 0.02 to 0.05.

EXAMPLE 2.
Triacetyl cellulose films (dt 2.9) are poured beforehand. For this purpose a 1X solution of triacetylcellulose in a mixture of methylene chloride, methanol and butanol is prepared in a volume ratio of 9: 1: 025.

 Films of 20 to 35 microns thick are obtained on an icy polished surface. The thickness of the films can be changed.

 3.5 grams of films obtained are treated for 14 minutes while heating (including 6 minutes at the boiling point) with a mixture of 600 cm 3 of a 0.1 N solution of caustic soda in 96% alcohol and 14 grams of monochloroacetic acid in 120 cm3 of water.

 Then the film is washed with a dilute hydrochloric acid solution, then with distilled water until a negative reaction with the chlorine ion occurs. The film obtained is a cellulose ester which, in addition to other groups characteristic of acetyl-cellulose, contains ionogenic carboxyl groups.

To test the sensitivity to light, the film obtained is printed for 10 minutes with a mercury vapor quartz lamp with a luminous flux intensity of 2.1 × 1017 quanta / cm2 s. After exposure, physical development is carried out successively in two solutions
1. 10 3 N PdCl2
2. copper developer - formaldehyde containing a complexing agent (for example potassium and sodium tartrate).

The optical density of the developed sample is 170 for an optical density of the haze equal to zero; the contrast factor determined from the results of the characteristic curve (sensitometric) is -2.5
Example 3.

 A material derived from the cellulose acid ester obtained and impression created in the same manner as in Example 2 is treated with a 10-3N solution of Ag M03, which is washed in water and for 1 minute in a 10% ammonia solution to remove the chemically non-combined silver, and then for 5 minutes in water, then it is dried. Then, the material is developed in a physical developer containing a silver salt. . The optical density of the developed sample is 0.090, the optical density of the haze being 0.09.

ss e 4
3.5 g of cellulose, known under the commercial denomination "Cellophane", were sorted for 16 minutes (including 11 minutes at the boiling point) with a mixture of 600 cm 3 of a solution of caustic soda in 96% alcohol and 14 gd monochloroacetic acid in 120 cm3 of water. Then the film is washed with a dilute solution of hydrochloric acid, then with distilled water until negative reaction with the chlorine ion To test the sensitivity of the film to light, it is exposed for 10 minutes to the rays of a mercury vapor quartz lamp with a light flux intensity of 2.1.1017 quanta / cm2.s. After exposure, a chemical treatment by physical development is applied in two solutions
1. 10-3 N PdCl
2. developer with copper - formaldehyde containing a complexing agent. The optical density of the developed sample is 0.68 for an optical density of the haze of 0.02
EXAMPLE 5.
Cellulose citrate paper is obtained by impregnating cellulose chromatographic paper with a 20% citric acid solution for 20 hours, drying and then heat treating at 1250C for 30 minutes, with subsequent washing with water to elimination of the excess of reagents. The cellulose ester-citrate obtained is exposed to the rays of a mercury vapor quartz lamp with an intensity of light flux of 4.3 × 1016 quanta / cin2.s; we subject it to physical development in two solutions
1. 0.1N AgNO3 with subsequent washing with water for the elimination of the chemically unbound silver;
2. "Amidol" developer (trade name).

The optical densities of the samples developed according to the duration of the exposure time are as follows
exposure time, minutes 1 4 8
optical density 0.15 0.36 0.60
The optical density of the veil is equal to 0.02.

Example 6.
A photosensitive material based on cellulose phosphate is prepared in the following manner.

A cotton cloth is treated, in order to remove the finish, with a solution of soap and sodium carbonate for 40 minutes and it is washed with distilled water.

Then the fabric is placed in a tank at a temperature set at the thermostat and containing an aqueous solution of orthophosphoric acid and urea in a molar urea: orthophosphoric acid ratio of 4: 1, the modulus of the bath being 10: 1. After impregnation for 30 minutes at a temperature of 750C, the fabric is wrung and dried at 40 C. The dried material is subjected to a heat treatment for 2 minutes at 1700C, after which it is washed with hot distilled water and washed. dried. After synthesis, the phosphoric residues (P043) of the ester are in the form of an ammoniacal salt. To obtain a photosensitive material in an acid form (cycle H), the tissue is treated with 0.1N formic acid for one hour. , then it is washed again with distilled water until neutral reaction. Then the photosensitive fabric is impressed with a mercury vapor quartz lamp at the intensity of the light flux of 4.8 × 1016 quanta / cm 2.

The physical development of the impressed sample is carried out in two solutions
1. 0.1 N AgNO3
2. "Amidol" developer.

 After development, the material is fixed in an ordinary fixing medium used for silver halide materials and is freed from excess fixing by washing. The optical densities of the developed cellulose phosphate samples immersed for 5 and 10 minutes are 0.93 and 1.1, respectively.

 If we replace in the physical developer, the N02 solution by a developer solution "Metol" (trade name), it is possible to obtain not black and white images but images colored in brown tone.

The photographic material obtained has a fire resistance improve
Example 7.
A cellulose phosphate in the form of paper is prepared in the following manner. Chromatographic paper is placed in a thermostatic reactor containing an aqueous solution of orthophosphoric acid and urea in a molar urea: phosphoric acid ratio of 4: 1; bath module 10:19 The solution is brought to 750C beforehand and the sample is kept at this temperature for 30 minutes. Then it is wrung and dried at 400 C. The dried sample is subjected to a heat treatment for 5 minutes at 140 C, then it is washed with distilled hot water and dried. Then the cellulose phosphate obtained in the form of ammoniacal salt is passed to the acid form, treating it with 0.1 N formic acid for one hour, with subsequent washing with distilled water until neutral reaction.

The photosensitive sample obtained is exposed to the full spectrum of a mercury vapor quartz lamp to the intensity of the luminous flux of 4.3.1016 quanta / cm2 .5.

The physical development is carried out after exposure by proceeding successively in two solutions
1. 0.1 N AgN03
2. "Amidol" developer.

 The optical densities of the developed samples exposed for 2 to 5 minutes are 1.4 and 1.9 respectively, the optical density of the haze being 0.3.

Example 8.-
The carboxymethylcellulose is prepared under conditions analogous to those described in Example 1.

To form the salts, a 0.1 N solution of AgNO 3 is used, after which the sample is washed with distilled water to release it from the adsorbed silver.

The salts obtained are impressed with a mercury vapor quartz lamp with an intensity of the luminous flux of 4.3.1016 quanta / cm 2 .8, and the development is carried out with a phenidone-hydroquinone developer, then fixing in a fixing medium. ordinary and washing with water to remove excess fixing.

The optical densities of the samples developed according to the irradiation time are as follows
irradiation time,
seconds 1 3 6 12 24 60
optical density 0.300.40 0.65 0.90 1.040.98
It follows from the results obtained that the light sensitivity of the material in the salt form is higher than in the acid form.

Material gradation characteristics
useful exposure time interval 0.9
average gradient 1.0
maximum optical density 1.04
haze optical density 0.04
Example 9.
The cellulose citrate is prepared under conditions analogous to those described in Example 5.

For the formation of the salts, the cellulose citrate is treated with a 0.1N solution of AgNO3 for 15 minutes; it is washed with distilled water and dried. To study the photosensitivity of a paper produced from silver salt of carboxymethylcellulose, it is exposed to the rays of a mercury vapor quartz lamp at intensity of luminous flux of 1.6.1016 quanta / cm2s.

then it is developed in an "Amidol" developer.

The optical density of the veil is 0.02. The optical densities of the samples developed according to the duration of exposure are indicated in the table below
duration of irradiation,
seconds I 6 6 12 24 36
optical density 0.26 0.59 0.94 1.22 1.37 1.39
Gradation characteristic of the photographic material:
Useful time interval
exposure 1.14
average gradient 1.1
maximum optical density 1.40.

Example 10.
The cellulose citrate is prepared under conditions analogous to those described in Example 5 (not based on cellulose in the form of paper but on the basis of cellulose in the form of "Cellophane"). The silver salt of cellulose citrate is obtained as described in Example 7. Then the silver salt of cellulose citrate is exposed to the rays of a mercury vapor quartz lamp i intensity of the light radiation of 1 , 6.1016 quanta / cm2.s, and it is then developed with a "! 4etol" -hydroquinone developer. The optical density of the developed sample impressed for 15 to 30 seconds is 0.42 and 0.70 respectively.

Example 11.
To form a salt, a material in the form of a film obtained under conditions analogous to those described in example 2 is treated for 2 hours with a 0.01 N solution of uranyl sulfate. Then the film is washed with water and dried. To carry out the light sensitivity tests, the uranyl salt of acid cellulose ester, which contains, together with carboxyl groups, acetyl groups, is exposed to ultraviolet rays for 1 minute, then the development under the action of a physical developer analogous to that described in Example 2. In this case the optical density of the developed sample is 0.51, the optical density of the haze is 0.04. optical density of the cellulose ester under the frme (cycle) H impressed and developed under analogous conditions is 0.17.

 Thus the introduction of uranyl ions into the acidic cellulose ester by sorption and ion exchange increases the light sensitivity of the material by three times.

Furthermore, during the exposure of the uranyl salt of cellulose acid ester to the radiation of a mercury vapor quartz lamp, isolated by an optical filter with a passband greater than 350 nm, and of the subsequent development in conditions similar to those indicated in example 2, a visible image is observed, the optical density of which during an exposure of 15 minutes is 0.35 for an optical density of the haze of 0.04, which testifies to the possibility of sensitizing matter to near ultraviolet by the introduction into the material of metal cations.

Example 12.
The cellulose phosphate is treated in the form of paper, obtained under conditions analogous to those described in Example 6, for one hour with a 0.1 N solution of copper acetate to obtain a copper salt of acid phosphate of cellulose. Then the copper salt of cellulose phosphate is impressed by means of a mercury vapor quartz lamp with an intensity of the light flux of 4.3 × 1016 quanta / cm 2 s for 5 minutes. Development of the sample is carried out by the physical development method in a 0.1N solution of AgNO3 with subsequent fixation in an ordinary fixing medium and washing with water to remove the excess fixing.

The optical density of the developed sample is 0.48, with an optical density of the haze of 0.05
It is known that if the copper salt of cellulose phosphate is used as a photographic material, it is possible to carry out the development in a single bath.

Example 13.-
In order to eliminate the use of precious metals at all stages of the photographic process and thereby lower the cost of photographic materials, acid ester salts of cellulose are used, the cation of which is the trivalent iron ion, and the anion, the acid residue of the corresponding ester.

 The cellulose citrate produced in the form of paper is treated, under conditions analogous to those which were indicated in Example 5, with a solution of trivalent iron chloride with a concentration of 10-2M for 5 minutes. Then the samples are washed with distilled water to remove the adsorbed iron ions, and dried. The material obtained is impressed with a mercury vapor quartz lamp with an intensity of the light flux of 6.8 × 1015 quanta / cm 2 s. The duration of the exposure time is 90 seconds.

Development is carried out by a chemical treatment comprising two baths
1. an alkaline solution of formaldehyde
2. a copper-formaldehyde developer containing glycerin.

The photographic image obtained is characterized by a sufficient density reaching unity) and by a high contrast.

Example 14.-
Samples of carboxymethylcellulose prepared under conditions analogous to those of Example 1 are treated for 5 hours with a solution of trivalent iron chloride with a concentration of 102M, washed, dried and subjected for 3 hours. minutes of radiation from a mercury vapor quartz lamp with a luminous flux intensity of 6.8.1015 quanta / cm2.s. Development is carried out under conditions analogous to those indicated in Example 1.

 The image obtained is characterized by a high density and a total absence of haze.

Example 15.
To prepare a photosensitive material having a high stability in an alkaline medium and a high resistance to heat, a copolymer of cellulose phosphate and of polyacrylonitrile is obtained.

 The graft copolymer is synthesized on a cellulose phosphate-Fe + 2 -H202 redox system.

The copolymerization is carried out as follows.

 blanks a flask containing 100 d 150 cm3 of a 1% solution of FeS04.7H20 at pH 4.3 to 4.8, 0.5 gram of phosphate is placed at room temperature and for 5 to 10 minutes of cellulose obtained under conditions analogous to those of Example 9. The excess of Fe + 2 is removed by washing with distilled water at pH = 5. Then the sample is placed in an acrylonitrile solution of a concentration of 1.1 mol / l. The polymerization is carried out for 2 hours at 60 C. The hydrogen peroxide is used as a polymerization initiator at a concentration of 0.002 mol / l. After the copolymerization, the copolymer is washed thoroughly and dried to a constant mass. To remove Fe + 3 remaining in the grafted cellulose, a 0.5 M solution of oxalic acid is used.

 The copolymer of cellulose phosphate and polyacrylonitrile is impressed with a mercury vapor quartz lamp, the radiation intensity of which is 4.3 × 10 6 quanta / cm 2.

 The development of the sample is carried out under conditions analogous to those indicated in example 9. The optical density of the developed sample, impressed for 5 minutes, is 0.86.

Research carried out to realize the alkali resistance of the photosensitive material obtained from the phosphate-cellulose and polyacrylonitrile copolymer has shown that under the actions of 10% caustic soda for 24 hours, it does not no defibration (separation of the fibers) of the product occurs, while the unmodified cellulose in the presence of such actions loses its fibrous structure.

 Thus, pure copolymerization of esters and ether-photosensitive acidic ethers of cellulose with comonomers of chemical structure and highly valued characteristics, it is possible to modify all of the physical and chemical properties of a photographic material.

Example 16.
5 cm 3 of an aqueous 5% polyvinyl alcohol solution are stirred with 0.4 μm of carboxymethylcellulose powder. The suspension is applied to a cleaned glass plate (1 cm 3 by 23 cm 2). then the glass plate to which the suspension of carboxymethyl cellulose in polyvinyl alcohol is applied is brought to 80 ° C. for 2 hours. The applied layer is stable to the action of water and of the solutions used for chemical treatment.

To determine the photosensitivity characteristics of the emulsion layer obtained, it is subjected to the radiation of a mercury vapor quartz lamp for 1 minute, after which the physical development is carried out in a two-bath developer.
1. PdCl2 with a concentration of 10-3M
2. copper-formaldehyde developer.

 The optical density of the developed sample, measured relative to a standard sample (barite slide) is equal to 0.98.

Example 17.
A photosensitive film is obtained from sulfoethylcellulose in the following manner. 0.5 g of industrial sulfoethylcellulose powder is mixed comprising ionogenic sulfate groups (in the composition of the ester group - C2H4303H) obtained under industrial conditions by causing sodium bromethylsulfonate or sodium chloroethylsulfonate to act on the cellulose in an alkaline medium, with 10 cm3 of a 5% gelatin solution, and the mixture is applied to a glass plate at the rate of 1 cm 3 per 8 cm 2, after which the sample is dried in air. The photosensitive film obtained is subjected to radiation of a mercury vapor quartz lamp and we proceed to its physical development by means of two solutions
1. 0, ÎN AgNO3
2. "Metol" -hydroquinone developer.

 After development, the sample is fixed in an ordinary fixing medium. The optical density of the developed sample impressed for 5 minutes is 0.30.

Example 18.
To form salts, a cellulose citrate paper (obtained under conditions analogous to those indicated in Example 5) is treated with a 0.1 M solution of bismuth tartrate, washed with a batten to remove the Bi +3 adsorbed, and it is dried. The sample obtained is impressed with a mercury vapor quartz lamp with a luminous flux intensity of 0.75.1016 quanta / cm2 .s for 2 minutes} its physical development is carried out using a copper formaldehyde developer and we wash it with water.

The density of the developed sample is 0.65, the density of the haze being 0.02
The material senses a good hold over time of the developed image; the image is developed in a single bath, which simplifies the technological process of obtaining the image.

Example 19.
To form salts, the carboxymethylcellulose (obtained under conditions analogous to those indicated in example 1) is treated with a 0.1 M solution of bismuth acetate, the adsorbed Bi + 3 ions are removed with water. it is dried and impressed with a mercury vapor quartz lamp with an intensity of the luminous flux of 0.75.1016 quanta / cm2s.

 Then the samples are developed in a physical developer with copper-formaldehyde and washed with water. The optical densities of the developed samples exposed for 0.5, 9 and 2 minutes are 0.23, 0.53 and 0.77 respectively, the haze being practically absent.

Example 20.-
Lead salts are prepared with acidic cellulose esters by treating the cellulose citrate with a solution Q, 1 M of lead acetate, with subsequent drying. To obtain photographic images, the salt is impressed with a mercury vapor quartz lamp and development is carried out in a copper-formaldehyde developer. The photographic images obtained are characterized by a sufficiently high optical density (for papers, up to 1.3-1.4) and sufficient contrast. The optical density of the veil is practically zero.

Example 21.
It is also possible to use, as photosensitive materials, copolymers of cellulose and synthetic comonomers containing acid groups, such as, for example, a copolymer of cellulose and acrylic acid. When you print this polymer with a mercury vapor quartz lamp for 4 minutes and then develop it under the action of a physical developer comprising two baths
1. PdCl2 10 3 M,
2. copper-formaldehyde developer, an image with sufficient optical density (up to 0.9) and high contrast is obtained.

Of course, the invention is in no way limited to the embodiments described which have been given only by way of example. In particular, it includes all the means constituting technical equivalents of the means described as well as their combinations if these are executed according to its spirit and implemented within the framework of protection as claimed.

Claims (7)

 1.- photographic material comprising a modified photosensitive cellulose, characterized in that it consists of esters or ether-acid oxide ethers of cellulose, or alternatively of copolymers of esters or ethers-ether oxides of acidic cellulose and synthetic comonomers  2 Photographic material according to claim 1, characterized in that the cellulose acid ester used is carboxymethylcellulose. 3. Photographic material according to either of Claims 1 and 2, characterized in that the acidic esters or ethers of cellulose oxides used contain, together with carboxyl groups, acetyl groups.  4. Photographic material according to claim 1, characterized in that as cellulose acid ester it contains cellulose phosphate.  5. Photographic material according to claim 1, characterized in that it consists of salts of esters or ethers of cellulose acid oxides.  6.- Photographic material according to one of claims 1 and 5, characterized in that, as ester salts or acid ether oxides of cellulose, it contains bismuth iron or lead salts 7.- Photographic material according to one of claims i to 6, characterized in that it is applied to a solid support.