DE19516350A1 - Reduced fog photothermographic photosensitive material - Google Patents

Description

The invention relates to a heat developable light-sensitive material with at least one binder layer applied on a substrate, which contains at least one light-sensitive silver halide light-insensitive silver salt of an organic acid, and in this layer or in a reactive relationship with it standing further layer at least one reducing agent contains.

Materials of this type are also under the labels "photothermographic materials" or "dry silver materials ". They are summarized, for example in Research Disclosure 170 029 (June 1978), in particular under "System B", and in Research Disclosure 299 063 (March 1989).

Dry silver materials are processed usually in a step of about 10 s duration Temperatures over 100 ° C. In these circumstances, it is particularly difficult to find the optimal ratio between Sensitivity and contrast on the one hand and obfuscation on the other hand. Because of the strong Temperature dependence of the chemical reactions involved and the short response time result in a short time Deviations in time and temperature that the Sensitivity not fully used or the picture too strong is veiled.

It is therefore common to use the photosensitive layers of the Dry silver materials special anti-fog Add connections. A number of such substances are in the mentioned research disclosures. EP 04 97 053-A1 proposes in particular 1-hydroxybenzotriazole and 1,2,3-  Benzotriazin-4 (3H) -one to reduce the tendency to fog in front.

EP-06 00 587-A1 describes tribromomethyl ketones as anti-fog compounds.

EP-06 05 981-A1 describes dry silver materials claims the certain tribromomethylsulfonylthiadiazole included as anti-fog compounds.

Even with the known anti-fog compounds do not avoid the veil of the Dry silver material when processing with growing The temperature or duration of the heat treatment increases constantly. It there is therefore still a need for alternative and effective anti-fog compounds.

The object of the invention is to provide a dry silver material create a slight tendency to obscure during that has heat development.

This problem is solved by a photothermographic light-sensitive material with at least one binder layer applied on a substrate, which at least one photosensitive silver halide and a light-insensitive silver salt of an organic acid contains, with the recording material in this layer or in another reactive relationship with it Layer at least one reducing agent and one contains an antifoggant compound, and thereby is characterized in that the anti-fog compound general formula (A)

has what
X chlorine or bromine and
A represents an optionally substituted amino group or a thioether group.

Preferred anti-fog compounds are by one of the following general formulas (I) or (II):

Mean in it
R₁, R₂, R₃ alkyl, alkenyl, cycloalkyl, aryl, aralkyl or a heterocyclic radical, where these radicals can be substituted with hydroxyl, halogen or with an optionally further substituted amino group,
R₁ also an optionally substituted amino group,
R₂ is also hydrogen,
R₁ and R₂ also alkylene groups, the free bonds of which are closed directly or via an oxygen or sulfur atom or via an optionally substituted imino group to form a ring,
X chlorine or bromine.

If the radicals R₁, R₂, R₃ are alkyl or alkylene groups, then these preferably contain 1 to 20 carbon atoms. As Aryl groups become those with 6 to 14 carbon atoms preferred, for example phenyl or naphthyl. Aralkyl groups preferably contain 7 to 20 carbon atoms, examples are Benzyl and phenethyl. Preferred cycloalkyl groups have 5 up to 10 carbon atoms.

Heterocyclic radicals in the function of R₁, R₂, R₃ are preferably residues of bonded via a carbon atom heterocyclic compounds used as antifoggants for aqueous silver halide emulsions are known, for example Residues of triazole, imidazole, thiazole, the tri- and Tetraazaindenes, benztriazole, benzimidazole, benzthiazole and purine.

The radicals mentioned can be further substituted especially with hydroxyl groups, amino groups and with Halogen atoms. Instead of the hydroxyl group, a Ester group, instead of the amino group also an amide or Step sulfonamide group.

The ring possibly formed by the radicals R₁ and R₂ can for example a pyrrolidine, piperidine, pyrazane, Thiazine, pyrazine or morpholine ring.

Individual compounds of the general formulas (I) and (II) are as intermediate or end products in the manufacture of Dyes or pharmaceuticals known (e.g. DE 30 48 487-A1, EP 02 75 997-A1, EP 02 01 765-A2, Angewandte Chemie 77 (1965), Page 282 ff.). There you will also find general information on Manufacturing.

The synthesis of the compounds starts from 4,5-dichloro- or 4,5-dibromo-3 (2H) -pyridazone, in which the halogen atom is accessible in the 5-position for electrophilic substitution. By reaction with primary or secondary amines to compounds of formula (I), with thiolates Compounds of formula (II).

General synthesis instructions for compounds of the formula (I):
10 mmol 4,5-dichloro- or 4,5-dibromo-3 (2H) -pyridazone are stirred in 75 ml ethanol. 20 mmol of the corresponding amine are added and the mixture is boiled under reflux for 10 to 24 hours (control of the conversion by thin layer chromatography). Then distilled off two thirds of the solvent and allowed to crystallize in the cold. If the product does not crystallize, the ethanol can be distilled off completely, the residue extracted with ethyl acetate, the extract dried and evaporated.

General synthesis instructions for compounds of the formula (II):
10 mmol 4,5-dichloro- or 4,5-dibromo-3 (2H) -pyridazone are stirred in 75 ml ethanol. 10 mmol of the thiol and 5 ml of 2N sodium hydroxide solution are added and the mixture is heated under reflux for 10 to 24 hours (control of the conversion by thin-layer chromatography). The ethanol is then completely distilled off, the residue is taken up in water, extracted with ethyl acetate, the extract is dried and evaporated.

The compounds of general formulas (I) and (II) are colorless to light yellow.

Examples of compounds of general formula (I) are in listed in Table 1 below:  

Table 1

Table 2 contains examples of compounds of the general Formula (II).

Table 2

The anti-fog compounds are the photosensitive layer or one with this in reactive Related layer incorporated. "Reactive relationship" means here that components of this layer at least under the conditions of heat development in the photosensitive Cross shift and be able to react there.

The compounds are useful in one for incorporation Solvent dissolved, which with the coating material for which is compatible with the corresponding layer. Are suitable for example methanol, ethanol, i-butanol, ethyl acetate, Acetone.  

The amounts to be used are between 0.5 and 30 g, preferably 5 to 15 g of the compounds (I) and between 0.2 and 10 g, preferably 2 to 5 g of the compounds (II) per mol of silver.

The dry silver materials according to the invention consist at least from a photosensitive layer on one Layer support. This photosensitive layer contains at least one binder, a light-insensitive silver salt an organic acid and a silver halide, as well as a Reducing agent for this silver salt and the Anti-fog compound according to the invention.

The dry silver materials can besides that photosensitive layer contain further layers, which in are reactive to the photosensitive layer. In In this case, the reducing agent, the anti-fog Connection and other means to influence the Properties of the material and the images created with it, such as toners, agents for improving the storage stability of the Materials and images, to increase sensitivity and the rate of development, in addition or only in those in a reactive relationship with the light-sensitive layer standing layers may be included.

Natural and synthetic polymers are used as binders such as cellulose acetates, polyvinyl acetals, polyolefins, polymers Esters, for example terephthalic acid, polyamides, Poly (N-vinyl) amides, polyvinyl / vinylidene chloride, polystyrene, Polyacrylonitrile, polycarbonates and the like as well Copolymers of the polymers on which these are based Monomers in question.

The non-photosensitive silver salt is preferably a salt an unbranched fatty acid with 12 to 22 carbon atoms, for example laurin, myristin, palmitin, stearin, Arachic or behenic acid, or a mixture of such salts. Silver stearate is particularly preferred.  

Aromatic dihydroxy compounds can be used as reducing agents such as hydroquinone, pyrocatechol. Other than are also suitable photographic developer compounds, such as m- or p-aminophenols, 3-pyrazolidinones, ascorbic acid and their Derivatives, as well as others, in the above-mentioned prior art listed connections. Bisphenols are preferred, for example the bis (2-hydroxy-3-t-butyl-6- methylphenyl) methane. The reducing agent can in the photosensitive layer or in an adjacent Auxiliary layer may be included. Its amount is usually 0.1 to 3 equivalents based on the total amount reducible silver salts.

The photosensitive silver halide can be generated in situ from the non-photosensitive silver salt by reaction with a limited amount of a compound, the halide ions can be released. Such connections are for example the halides of alkali metals and Ammonium or organic N-halogen compounds such as N-bromosuccinimide, N-bromophthalimide, N-chlorophthalazinone, N-bromoacetamide and others. Other procedures of this type are in Research Disclosure No. 17029, Chapter I (June 1978) and No. 29963, Chapter XV (March 1989) Publications described.

Preferably, the silver halide is in one separate operation ("ex situ") in an aqueous solution prepared which is a hydrophilic colloid, preferably gelatin, contains. One uses the ones from the conventional one Technique of silver halide photographic emulsions known methods of precipitation and chemical and spectral sensitization. After that it can Silver halide are separated from the protective colloid, for example, according to the procedure of GB 13 54 186. Das Silver halide is isolated and sensitized if necessary the coating composition for the photosensitive layer of the Dry silver material added. As a silver halide silver bromide and silver bromoiodide with a  Iodide content up to 10 mole percent. The grain size of the Silver halide is preferably between 0.05 and 0.5 μm, its share in the total silver salt content of photosensitive layer is generally less than 10, preferably 0.2 to 2 mole percent.

It is advantageous to the invention Add a so-called toner to dry silver materials, so that the developed silver picture is a neutral black Hue and high density. Known toners are in Research Disclosure 17029 (June 1978), Chapter V, and 29963 (March 1989) Chapter XXII. Examples usable toners are phthalazinone and its derivatives, for example 2-acetylphthalazinone, phthalimide and derivatives, such as N-hydroxyphthalimide, succinimide, N-hydroxy-1,8-naphthalimide.

Particularly preferred toners are pyridazones, for example 6-pyridazones of the general formula

wherein M is a hydrogen or alkali metal atom, R₁, R₂ and R₃ may be the same or different and are hydrogen, methyl, Ethyl, propyl, R₁ and R₂ are also chlorine or bromine can.

The toners are preferably one to the photosensitive one Layer added reactive layer.

The dry silver materials can besides that photosensitive layer and any existing to this layers in a reactive relationship Contain layers, for example above or below the light-sensitive layer arranged auxiliary layers such as  Protective layers or adhesion-promoting layers or on antihalo or Anti-curl layers.

Both clear and colored or pigmented plastic films, for example Polyethylene terephthalate or cellulose acetate, as well as raw or coated papers.

The dry silver materials according to the present invention are characterized by low tendency to fog and high contrast excellent. In particular, the veil rises during the Heat development only slightly, so that development time and temperature according to the respective requirements without Problems can be adjusted. In particular, the Maximum density and sensitivity through "torture" be increased. Also inevitable affect Fluctuations in development conditions do not affect the Image quality.

The materials according to the invention can be used for the production of images using exposure and heat generation especially for contact copies, Projection enlargements and camera shots in the Reproduction technology.

Embodiment

A photosensitive coating for one Dry silver material was produced in the following way:

In a pearl mill
196 g silver stearate,
1500 ml ethanol,
40 g of polyvinylpyrrolidone K 30 (molecular weight 40,000),
4 ml nonylphenol ethoxylate (10 EO) and
7 g behenic acid

with 1000 ml glass beads (2 mm diameter) with cooling Ground for 18 hours. To control the degree of grinding a sample of the dispersion at a hundredfold magnification  viewed under a microscope, with no particles recognizable were. The coating solution prepared in this way is treated with A designated.

This dispersion was stirred

60 g polyvinylpyrrolidone,
1.28 g of mercury (II) chloride in 200 ml of ethanol,
16 g phthalazinone in 200 ml ethanol and
6.4 g of 5-nitroindazole in 250 ml of ethanol

and 8 g each of the anti-fog compound (as in Table 3 indicated) admixed. After removing the glass beads this coating solution B is ready for coating.

In a mixed solvent

400 ml methylene chloride and
80 ml of isopropanol were
4 ml nonylphenol ethoxylate (10 EO),
40 g polyvinyl butyral (molecular weight 36,000),
34 g of 3,3'-di-t-butyl-2,2'-dihydroxy-5,5'-dimethyl-diphenylmethane

dissolved to form the coating solution C.

The coating solution B was with a layer thickness of 60 µm on a polyethylene terephthalate support applied and dried. The was on the dry layer Coating solution C with a layer thickness of 100 µm applied and dried again.

In this way, dry silver films were obtained, which only in the manner of those contained in the photosensitive layer distinctive anti-fog compound. Samples of this Films were processed in a contact exposure device using a Mask exposed imagewise and by touching one Metal surface, which had a temperature of 105 ° C over developed the time given in Table 3. Was judged the minimum transmission density Dmin at the points below the impervious areas of the mask.  

Table 3

Claims (5)

1. Photothermographic photosensitive recording material having at least one binder layer applied to a support which contains at least one light-sensitive silver halide and one light-insensitive silver salt of an organic acid, the recording material in this layer or in a further layer which is in a reactive relationship to it, at least one reducing agent and one contains an anti-fog compound, characterized in that the anti-fog compound has the general formula (A) has what
X chlorine or bromine and
A represents an optionally substituted amino group or a thioether group. 2. Material according to claim 1, characterized in that the fog-inhibiting compound of the general formula (A) has one of the formulas (I) or (II) below, in what mean
R₁, R₂, R₃ alkyl, alkenyl, cycloalkyl, aryl, aralkyl or a heterocyclic radical, where these radicals can be substituted with hydroxyl, halogen or with an optionally further substituted amino group,
R₁ also an optionally substituted amino group,
R₂ is also hydrogen,
R₁ and R₂ also alkylene groups, the free bonds of which are closed directly or via an oxygen or sulfur atom or via an optionally substituted imino group to form a ring,
X chlorine or bromine. 3. Material according to claim 1 or 2, characterized in that the amount of the anti-fog compound 0.5 to 30 g each mol of silver. 4. Material according to any one of claims 1 to 3, characterized in that there is a toner compound of the general formula in the light-sensitive layer or in a layer which is in a reactive relationship to this wherein M is a hydrogen or alkali metal atom, R₁, R₂ and R₃ may be the same or different and may be hydrogen, methyl, ethyl, propyl, R₁ and R₂ may also be chlorine or bromine. 5. Material according to one of claims 1 to 4, characterized in that the photosensitive silver halide is formed ex situ and is chemically and possibly spectrally sensitized.