DE2315233B2 - METHOD OF MANUFACTURING A HEAT DEVELOPABLE, SILVER HALOGENIDE-FREE, LIGHT-SENSITIVE RECORDING MATERIAL - Google Patents

Description

The invention relates to a method for producing a heat-developable, silver halide-free, light-sensitive recording material by applying a first layer to a Layer support, which is a dispersion of a silver sal / .es ss a long chain fatty acid and a carboxylic acid, applying a coating solution containing a containing organic reducing agent on the first layer and drying to form a second Layer. r, o

Silver halide photography is well known to the other various pholographic processes superior in terms of sensitivity, gradation and the like. However, it has the disadvantage that its actions like development and fixation, <> <, are cumbersome in that they are done in a wet system and that it is in many ways it is difficult to mechanize the entire stages.

Many attempts have been made to improve silver halide photography in this regard by converting their treatment stages from a wet system to a dry system. Underneath there is also the proposal made in the patent literature, light-sensitive recording materials develop by heat treatment. For example, in Japanese Patent Publication 49 24/1968 (BE-PS 6 63 112, FR-PS 1441 691, DT-OS 15 72 203 and GB-PS 1110046) a through Heat developable photosensitive material has been proposed which is composed of a organic silver salt, a carboxylic acid, a reducing agent and a silver halide consists of Im Example 1 of DT-OS 15 72 203 describes a comparative experiment in which no halogen donor is used will. In this comparative experiment, a mixture of silver behenate and behenic acid, a reducing agent, a system consisting of a binder and an acidic stabilizer (succinic acid) exposed and then heat developed, with only one on a slightly dirty yellow background faint gray image is obtained. In the comparative experiment it is also stated that then it is also practical no favorable image density can be obtained if the exposure conditions and the heat development conditions to be changed.

The object of the invention is therefore to provide a recording material which can be developed by heat of the type mentioned with high photosensitivity and good shelf life.

In a method of the type mentioned at the outset, this object is achieved in that the thus obtained Material is subjected to a heat pretreatment at temperatures of 70 to 120 C in such a way that thereby changing the optical density on the surface of the recording material by less than 0.1.

By means of the method according to the invention, a silver halide-free, heat-developable material is produced for the first time Recording material created which has good photosensitivity and can be stored for a long time. Furthermore, the present invention made it possible for the first time to obtain silver salts of long-chain fatty acids, which were previously regarded as practically insensitive to light, sensitive to light and therefore of use in recording materials to make them accessible.

Although the exact mechanism by which the silver halide-free recording material is photosensitive is made so that it is possible to produce an effective image density, heretofore is not known, a possible explanation is the following: By the heat pre-treatment according to the invention ^ can the silver salt of long-chain fatty acid, because; is hardly dissociated at ambient temperature wise thermally dissociated with frcisetzunj of silver ions. The silver ions formed in the process can form a neutral silver aggregate, which is used as sensitivity in the subsequent exposure stage Heck can work. Another possible explanation is as follows: By the Wiirmcvor according to the invention treatment, the carboxylic acid is melted to act as a solvent, which the Schmclzci and dissociation of the silver salt of the long fur acid can facilitate. The dissociated transference then represents a mark of sensitivity as in the case of the one accepted Mechanism. It may be left open which mechanism applies; on every l-'a

It is most surprising that a silver salt of a long chain fatty acid that has hitherto been considered not or practical was not considered to be photosensitive, photosensitive due to the heat pretreatment according to the invention can be done.

According to a preferred embodiment of the invention a first coating layer, which is a silver salt, is applied to a substrate such as paper a long chain fatty acid and an organic carboxylic acid dispersed in a binder. Then the surface of the layer is treated with a treating solution containing a reducing agent treated and then dried. At this stage, however, the product hardly exhibits any image-forming property on. It is then subjected to the pretreatment heat treatment according to the invention. Excellent photosensitivity is achieved. The photosensitive recording material produced in this way is then exposed imagewise and at a temperature higher than the pre-heat treatment temperature. By this treatment is carried out in the exposed part under the influence of the reducing agent contained therein selectively generates a silver image. As an energy source for exposure, ultraviolet rays or any other radiant energy can be used in addition to visible light.

The photosensitive recording material produced according to the invention is prior to the heat pretreatment hardly sensitive to light and can therefore be exposed to normal interior lighting for a short time will. In addition, by adding mercury salts, hereinafter referred to as antifoggants photosensitivity can be completely eliminated prior to preheating. In particular, there is no special light-blocking feature during packaging, storage or transport Measure or device required if the recording material is imminent its introduction into a step exposure device guided by a heating roller or another Heat pre-treatment is subjected.

The photosensitivity imparted to the recording material by the heat pretreatment is practically not lost with the passage of time. This property differs significantly from the phenomenon that the sensitivity caused by an electric charge with the lapse of time is lost in electrophotography. The sensitivity, however, has a tendency to be gradual decrease when the recording material is stored in an atmosphere containing a solvent vapor contains, which is able to cause the coating material to swell and to to solve. Therefore, in order to prevent the decrease in sensitivity, it is preferable to use a Solvent atmosphere, for example that of trichlorethylene, toluene, acetone and alcohol, avoided. If, on the other hand, one wants to intentionally support the reduction in sensitivity, the recording material can exposed to the atmosphere of these solvents.

According to the invention suitable silver salts of long-chain fatty acids are those which are at room temperature hardly impaired or darkened under interior lighting, such as silver chcnate, silver stearate, Silver palmitate, silver myristate, silver laurate, silver croleate and silver hydroxystcarate. Silver salts of Fatty acids with 18 to 24 carbon atoms, in particular silver behenate and / or silver stearate, are preferred

Examples of reducing agents which can be used according to the invention are substituted by a hydroxyl group aromatic compounds. Particularly effective compounds are hydroquinone, methylhydroquinone, Chlorohydroquinone, bromohydroquinone, pyrocatechol, pyrogallol, methylhydroxynaphthalene, aminophenol, 2,2'-methylenebis (6-terL-butyl-4-methylphenol), 4,4'-butylidene-bis (6-tert-butyl-3-methylphenol) and 4,4'-thiobis (6-tert-butyl-2-methylphenol). In addition, amino compounds such as N, N'-diethyl-p-phenylenediamine and N-phenyl-N'-isopropyl-p-phenylenediamine, be used. Bisnaphthol reducing agents, such as see them in US patent 36 72 904 (French patent 20 90 923, Belgian patent 7 66 589) are described. These compounds can be used singly or in combination.

Examples of carboxylic acids which can be used according to the invention are aliphatic monocarboxylic acids, unsaturated aliphatic monocarboxylic acids, dicarboxylic acids and aromatic carboxylic acids, such as capric acid, Lauric acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, Linoleic acid, oleic acid, succinic acid, adipic acid, sebacic acid, benzoic acid, cinnamic acid, salicylic acid, p-hydroxybenzoic acid, 2,6-dihydroxybenzoic acid, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, Diphenic acid, 5,5'-methylene-bis-salicylic acid, tetrachlorobenzoic acid and tetrabromobenzoic acid. Long-chain fatty acids with 18 to 24 carbon atoms are particularly preferred.

The optimal temperature range and the optimal heating time of the heat pre-treatment, the one The characteristic features of the present invention depends on the kind of silver salt used the long-chain fatty acid, the organic reducing agent used and the carboxylic acid used away. In this heat pretreatment, it is advisable to add so much to the recording material Apply heat as possible while staying below the limit at which a haze appears the recording material is generated; in other words, the amount of heat supplied is measured in such a way that that the change in optical density on the surface of the recording material during the Pre-heat treatment is less than 0.1. The heat pre-treatment is preferably carried out during carried out over a short period of time. For example, if a system is used that uses silver behenate, 2.2'-methylene-bis- (6-tert-butyl-4-methylphenol) and behenic acid, the heat pre-treatment is used preferably carried out at 80 ° C. for 5 to 30 seconds or at 100 ° C. for 1 to 5 seconds. The heating a long period of time is undesirable because it leads to fogging.

There is a preferred heat pre-treatment

do in that you can the surface of one with a dispersion of a silver salt of a long-chain fatty acid and .liner organic carboxylic acid in a suitable Binder-coated carrier, which is treated with a solution of a reducing agent in a suitable

('s neten solvent has been treated with a Ileizwalze, a hot plate or hot air during during drying or at a suitable time after drying, but before exposure to light.

The photosensitive recording material produced according to the invention can, depending on the type of used silver salt or reducing agent used a tinting agent, an antifoggant and the like can be added. For example, phthalazinone and its derivatives are described in US Pat 30 80254 as a tinting agent for a heat-sensitive, a silver salt of a long-chain Fatty acid-containing reproductive papers are described as effective tinting agents. Others Also effective tinting agents are the cyclic ones described in US Pat. No. 3,672,904 Imide. The mercury salts described in US Pat. No. 3,589,903 are effective antifoggants, Storage stabilizers and tinting agents. White pigments such as zinc oxide, titanium dioxide and the like. improve the whiteness of the background (the non-image Partly) as well as the image density and the apparent sensitivity.

The photosensitive recording material according to the invention can be incorporated in a manner known per se a customary spectral sensitizing dye from the class of the cyanines, merocyanines, oxonols and acridines are sensitized. Although acridine yellow is claimed to have no sensitizing effect on silver halides, it can also be used in the present invention. To the A binder can preferably be incorporated into the recording material produced according to the invention. Examples of suitable binders are polyvinyl butyral, cellulose acetate butyrate, polymethyl methyl acrylate, Polyvinylpyrrolidone, ethyl cellulose, cellulose acetate, cellulose acetate butyrate, polyninylacetate, polyvinyl alcohol and gelatin.

Any material that is resistant to heating can be used as the support. Examples Synthetic resin films, such as films made of polyethylene terephthalate, polycarbonate, are suitable for support and cellulose acetate, metal foils such as aluminum foils, and various types of paper.

The optimum ratio of the components in the photosensitive recording material according to the invention depends on the type of long chain fatty acid silver salt used, the type of used Reducing agent and the type of carboxylic acid used. In general it is advisable to to 1 part by weight of the silver salt of a long-chain fatty acid 10 to 0.01 part by weight of the organic Reducing agent and 10 to 0.01 parts by weight of the carboxylic acid to be used. Preferably be per mole of the silver salt of a long-chain fatty acid 1 to 0.1 mole of the organic reducing agent and 10 to 0.1 mol of the organic carboxylic acid is used / ends.

Of course, instead of pretreating the above-described recording material a selective heat image is also applied to produce a heat-sensitive reproduction and then the entire surface can be exposed and heat developed.

The examples illustrate the invention.

example 1

A first coating dispersion of the composition given below was used a roll coater applied to a photographic base paper and then dried. The coating amount after drying was 12 g per nr support.

Silver behenate

Behenic acid

Polyvinyl butyral

toluene

Ethanol

17g

13g

40 g

350 ml

350 ml

Thereafter, a roll coater was applied a a reducing agent enthaitende second coating solution of the following composition and dried at a temperature below 50 C using. The coating amount after drying was 1.0 g per m ^{2 of the} support.

Hydroquinone

Polyvinyl butyral

Methanol

30 g

10g

iOOOml

The resulting coating was 5 seconds subjected to a heat pretreatment at 90 ° C. with a heating roller and then through a Negative image exposed to light from a blue fluorescent lamp. Then it was given 5 seconds to develop heated at 105 C for a long time to form a dark brown positive image.

Example 2

Coating compositions were prepared in the same way as in Example 1, but this time under Use of an equimolar amount of sebacic acid instead of behenic acid and 23 g of N-phenyl-N'-isopropyl-p-phenylenediamine instead of hydroquinone as a reducing agent in the second coating liquid. These coatings were processed in the same manner as in Example 1 on the same Paper carrier applied. After pre-heat treatment, exposure and heat development as in example 1 a dark brown positive image was obtained. Appropriate heating conditions in the pre-heat treatment and heat generation in this case were 5 seconds at 80 (and 5 seconds at 100 (.

Example 3

A thermally developable light-sensitive material was prepared in the same manner as in Example I except that a second coating solution having the following composition was used. The coating amount after drying was 2.5 g per m ^{2 of} substrate.

2,2'-methylene-bis- HX) g (o-tcrt.-butyl ^ -methylphenol) Phthalazinone 5g Polyvinyl butyral 10g Methanol IOOOml

The recording material thus obtained was heated using a heat roller for 5 seconds subjected to a pre-heat treatment and then using a blue fluorescent lamp as Light source exposed through a step wedge. This was followed by heating to 105 (for 5 seconds. The samples subjected to the pre-heat treatment provided a pleasant one, depending on the amount of exposure black picture. The relationships between the pre-heat treatment temperatures and those derived therefrom resulting blood properties are given in the table below.

Sample wamic pretreatment

No temperature

Sensitivity *) Density **)

Dm

Dl

Dm-Df

2 40

3 60

4 80 7

5 100 11

*) The sensitivity is indicated by the number of steps of the step wedge, the one

Gave density of 0.1 above haze.
**) Dm and Df mean the maximum image density and the fog density, respectively.

0.08 0.08 0 0.08 0.08 0 0.25 0.08 0.07 1.00 0.08 0.92 1.55 0.15 1.40

Example 4

The first coating dispersion and the second coating solution are given below Compositions were applied to photographic paper support in this order and then dried.

First coating dispersion

Silver stearate 15 g

Stearic acid 11 g

Polyvinyl butyral 20 g

Toluene 300 ml

Ethanol 300 ml

Second coating solution

2,2'-methylene-bis- 100 g (6-tert-butyl-4-methylphenol)

Phthalazinone 5 g

Polyvinyl butyral 10 g

Methanol 1000 ml

The coated paper thus obtained was subjected to a heat pre-treatment for 15 seconds at 80 C by touching the back surface of the same with a hot plate brought. A negative image was then printed on using a blue fluorescent lamp. After heating at 95 ° C. for 5 seconds, a positive brown image was obtained on a white background.

Example 5

The first coating dispersion and the second coating solution are those given below Compositions were applied to photographic paper support in this order and then dried

First coating dispersion

The coated paper thus obtained was cut into two pieces. One of the pieces was subjected to 5 seconds of a heat treatment at 100 ¹ C by the rear surface thereof brought into contact with a heating roller. A negative image was then printed on using a blue fluorescent lamp. After heating at 110 ° C. for 5 seconds, a completely fog-free, clear, black positive image was obtained, the background of which was white.

The other piece was made with light from a 40 W daylight fluorescent lamp, used for indoor lighting, at a distance of 2 m 2 hours exposed long before the heat pretreatment. After that, in the same way as above, the Heat pre-treatment, exposure and heat development carried out. Despite the above A completely fog-free, clear, black image could be obtained after 2 hours of exposure.

Example 6

100 parts of the first coating dispersion used in Example 1 were prepared. Then were before application the following components are added and one after the other solved:

Silver behenate 17 g Behenic acid 13 g Mercury (II) acetate 0.12 g Polyvinyl butyral 40 g toluene 350 ml Ethanol 350 ml Second coating solution 2,2'-methylene-bis- 100 g (6-tert-butyl-4-methylphenol) Phthalazinone 5g Polyvinyl butyral 10 g Methanol 1000 ml

2,2'-methylene-bis-

(6-tert-butyl-4-methylphenol)

Phthalazinone

0.65 g

The coating solution thus obtained was applied to a photographic base paper and dried. After pre-heat treatment, exposure and heat development as in the previous one Example, a positive black image could be obtained.

Example 7

The second coating solution of Example 5 was replaced by the following coating solution, the the spectrally sensitizing indicated below contained the dye

Second coating solution

2,2-methylene-bis-100 g
(6-tert-butyl-4-methylphenol)

Phthalazinone 5 g

Acridine yellow (C. 1.46025) 0.01 g

Polyvinyl butyral 10 g

Methanol 100 ml

The coated paper thus obtained was subjected to heat pretreatment at 100 ° C. for 5 seconds

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interjected by bringing the rear surface thereof into contact with a heating roller. After a 5 second exposure to light from a 150 W tungsten lamp at a distance of 30 cm and subsequent heat development for 5 seconds at 110 ° C., a clear black was obtained positive image similar to that of Example 5, the background of which was white.

Example 8

On the surface of a coated paper prepared in the same manner as in Example 5 was applied the following third coating solution which is a spectral sensitizing dye contained, applied.

Third coating solution

l-carboxymethylo - [(3-ethyl- 0.01 g

2- (l) -benzoxazoliden) ethylidene] -

3-phenyl-2-thiohydantoin

Methanol 1000 ml

After the heat treatment, the subsequent exposure and the subsequent exotherm in the same manner as in Example 7 get a positive black image.

Example 9 with comparative example

Sample No. 4 of Example 3 was used as the test sample according to the invention.

For comparison, the first coating dispersion from Example 1 was mixed with 0.2 g of ammonium bromide, which was dissolved with stirring. This dispersion was applied to a photographic by means of a roller

IS carrier paper applied and dried. The second coating solution from Example 3 was applied to this first layer by roller application and dried in the same way as described in Example 1 at a temperature of below 50.degree. The resulting material was heated to 105 (. 'For 5 seconds after imagewise exposure.

Both test samples were exposed to artificial light or sunlight under the conditions shown in the following Conditions compiled in the table. The changes in the white backing of these Test specimens after exposure were measured. The results are compiled in the table below. Changes in discoloration density before and after exposure were measured using a blue filter.

Tabel

Test sample light conditions

Artificial light

500 lux. 120 hours

sunlight

45,000 lux. 6h

3 ° Known discolored to brown
0.20 *)

Invention no change
0.00 *)

*) Measured through a blue filter.

discolored to brown 0.25 *)

pale yellow 0.06 *)

The comparison report shows that according to the invention produced recording material is subject to significantly less discoloration over time than the material produced according to the method of DT-OS 15 72 203.

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Claims (6)

Patent claims: 1. Process for the production of a heat developable, syllable; halide-free, photosensitive Recording material by applying a first layer to a layer support, containing a dispersion of a silver salt of a long chain fatty acid and a carboxylic acid a coating solution containing an organic reducing agent to the first Layering and drying to form a second layer, characterized in that one the material obtained in this way is subjected to a heat pretreatment at temperatures of 70 to 120 C, in such a way that the optical density on the surface of the recording material is thereby changed less than 0.1 changes. 2. The method according to claim 1, characterized in that a 0.1 to 10 mol of carboxylic acid enl- containing dispersion and a 0.1 to 1 mol of organic reducing agent-containing coating solution, each based on 1 mol of the silver salt of a long-chain fatty acid is used. 3. The method according to claim 1 and / or 2, characterized in that a silver salt is a long-chain fatty acid with 18 to 24 carbon atoms, in particular silver behenate and / or Silver stearate containing dispersion is used. 4. The method according to at least one of claims 1 to 3, characterized in that a a long-chain fatty acid having 18 to 24 carbon atoms as a carboxylic acid-containing dispersion is used. is 5. The method according to at least one of claims 1 to 4, characterized in that a Dispersion is used which disperses the silver salt of a long chain fatty acid and the carboxylic acid contains in a binder. 6. The method according to at least one of claims 1 to 5, characterized in that in the recording material is also a customary, spectral sensitizing dye from the class the cyanines, merocyanines, oxonols and acridines are incorporated in a manner known per se.