DE60013289T2 - An aqueous dispersion containing photosensitive silver halide and a substantially light-insensitive silver salt of an organic carboxylic acid - Google Patents

Description

technical Field of the invention

The The present invention relates to an aqueous dispersion which is radiation-sensitive Silver halide and a substantially light-insensitive silver salts an organic carboxylic acid contains and their manufacture and use.

general State of the art

In US 4,210,717 it is stated that preparation processes for dispersions containing radiation-sensitive silver halide and organic silver salts and in which the pH of the dispersion can be increased to more than 9.0 by using alkali salts of alkali or ammonium salts of organic acids as described in US Pat US 3,761,273 and DOS 2824556 (= US-A Ser. No. 803,549, filed June 6, 1977), which produce silver hydroxide during manufacture and are associated with silver loss due to the precipitation of silver hydroxide. US 4,210,717 describes a preparation process for dispersions of radiation-sensitive silver halide and organic acid halides and organic acid silver salts, maintaining a pH of less than 9.0 to improve the conversion percentage and overall conversion quality. It is well known that hydrolysis of silver halides to silver hydroxide and silver oxide gives increased background density in conventional silver halide emulsions, for example, reference is made to The Theory of the Photographic Process Fourth Edition, Ed. TH James, Eastman Kodak (1977), page 395 and the silver oxide formed at high pHs is expected to also provide increased background density and generally a decrease in background density stability in photothermographic materials.

In WO 97/04355 becomes a photothermographic recording material discloses containing a carrier and a photo-addressable heat-developable Element, the radiation-sensitive silver halide in catalytic Relationship to a substantially light-insensitive silver salt of a organic carboxylic acid, an organic reducing agent for the substantially light-insensitive Silver salt of an organic carboxylic acid in thermal effective Relationship thereto and contains a binder, characterized in that the binder is a non-proteinaceous water-soluble binder, a nonproteinaceous water-dispersible binder or a mixture of a non-proteinaceous water-soluble and a non-proteinaceous water-dispersible binder is.

at Photothermographic materials in which both partners in the leading to the formation of elemental image-forming silver particles Oxidation-reduction reaction even after image development still included There is a constant need for ways to get these materials before and after image formation without long air conditioning at elevated temperatures and to stabilize high relative humidities.

Tasks of present invention

task The present invention is an aqueous, radiation-sensitive Silver halide and a substantially light-insensitive silver salt an organic carboxylic acid to provide containing dispersion with the without long air conditioning at elevated Temperatures and high relative humidities photothermographic Materials with improved stability of the background density produced can be.

A Another object of the present invention is a method for making an aqueous, radiation-sensitive silver halide and a substantially light-insensitive Silver salt of an organic carboxylic acid-containing dispersion to provide with the without long air conditioning at elevated temperatures and high relative humidities photothermographic materials with improved stability of Background density can be produced.

Yet Another object of the present invention is to provide a photothermographic Material with improved stability of the background density, the no long air conditioning at elevated temperatures and high relative humidities requires to provide.

Further Objects and advantages of the present invention will become apparent from the the following description.

Short illustration of the present invention

Unexpectedly we have found that photothermographic recording materials, those made of watery, radiation-sensitive silver halide and a substantially light-insensitive Silver salt of an organic carboxylic acid-containing dispersions are coated by temporarily increasing the pH of the Dispersion to at least 8.0 a substantial reduction in background density and have an improvement in the stability of the background density, without causing a long air conditioning at elevated temperatures and high relative humidities is required.

Be solved the above mentioned Tasks by a process characterized by the following steps Process for the preparation of a first aqueous dispersion comprising radiation-sensitive silver halide prepared ex situ; and a substantially light-insensitive silver salt of an organic carboxylic acid includes: separate preparation of a second aqueous, produced ex situ radiation-sensitive silver halide-containing dispersion and a third aqueous, the substantially light-insensitive silver salt of an organic carboxylic acid containing dispersion, and mixing the second aqueous Dispersion with the third aqueous Dispersion for the preparation of a mixture of these two dispersions, characterized in that the first aqueous dispersion produced thereby substantially free of a water-soluble metal salt or ammonium salt an aliphatic carboxylic acid with more than 12 carbon atoms and the method of further includes a step of the following group of steps: increase the pH of the second aqueous Dispersion to at least 8.0 before mixing with the third aqueous Dispersion, increasing the pH of the third aqueous Dispersion to at least 8.0 before mixing with the second aqueous Dispersion and increase of the pH of the mixture to at least 8.0.

Be solved the above mentioned Tasks also by a first aqueous, after the above Preparation process preparable dispersion containing an ex situ produced radiation-sensitive silver halide and a substantially light-insensitive Contains silver salt of an organic carboxylic acid.

Be solved the above mentioned Tasks also by using the above-mentioned first aqueous Dispersion in the preparation of a photo-addressable heat-developable Elements of a photothermographic recording material, wherein the photoaddressable heat developable Element the radiation-sensitive silver halide, the essential light-insensitive silver salt of an organic carboxylic acid Reducing agent for it in a thermally effective relationship thereto and a binder.

Be solved the above mentioned Tasks also by a marked by the following steps A process for preparing a fourth aqueous dispersion comprising second radiation-sensitive silver halide prepared in situ and a substantially light-insensitive silver salt of an organic carboxylic acid includes: (I) providing the third aqueous Dispersion and (II) partial conversion of the substantially light-insensitive Silver salt of an organic carboxylic acid in the third aqueous dispersion into the second radiation-sensitive silver halide prepared in situ using a non-fluorine halide ion source, being an aqueous Dispersion is obtained, which is the substantially light-insensitive Silver salt of an organic carboxylic acid and the second, in situ prepared radiation-sensitive silver halide, characterized in that the fourth aqueous dispersion produced thereby substantially free of a water-soluble metal salt or ammonium salt an aliphatic carboxylic acid with more than 12 carbon atoms and the method of further includes a step of the following group of steps: increase the pH of the third aqueous Dispersion to at least 8.0 before step (II), increasing the pH the third aqueous Dispersion to at least 8.0 during Step (II) and raising the pH of the obtained from step (ii) aqueous Dispersion to at least 8.0.

Be solved the above mentioned Tasks also by a according to the above manufacturing method preparable fourth aqueous Dispersion, which is a second, in situ produced radiation-sensitive Silver halide and a substantially light-insensitive silver salt an organic carboxylic acid.

Be solved the above mentioned Tasks also by using the above fourth aqueous Dispersion in the preparation of a photo-addressable heat-developable Elements of a photothermographic recording material, wherein the photoaddressable heat developable Element the radiation-sensitive silver halide, the essential light-insensitive silver salt of an organic carboxylic acid Reducing agent for it in a thermally effective relationship thereto and a binder.

Further preferred embodiments The present invention will be apparent from the subclaims.

Detailed description of the present invention

definitions

Under The term "watery" in the sense the present invention mixtures are understood, at least 60% by volume of water, preferably at least 80% by volume of water, and optionally water-miscible organic solvents such as alcohols, preferably methanol, ethanol, 2-propanol, butanol, isoamyl alcohol, Octanol, cetyl alcohol, glycols, e.g. Ethylene glycol, glycerol, N-methylpyrrolidone, Methoxypropanol, and ketones, e.g. 2-propanone and 2-butanone.

Under the term "water-soluble Salt "of course a solubility in water at 20 ° C of at least 2 mg / l. The term "metal salt or ammonium salt an aliphatic carboxylic acid with more than 12 carbon atoms "includes lithium, potassium, sodium, rubidium, cesium and ammonium salts of aliphatic carboxylic acids such as behenic acid and stearic acid or mixtures thereof.

"Essential free "does not mean Intentionally contained and if present, only in tiny quantities.

"Essential insensitive to light "means not intentionally sensitized and resistant to Darkening during exposure.

Ex means radiation-sensitive silver halide prepared in situ radiation-sensitive silver halide, not by partial conversion an organic silver salt by reaction with a non-fluorine-containing Halide ion source is made.

In means radiation-sensitive silver halide prepared in situ radiation-sensitive silver halide by partial conversion an organic silver salt by reaction with a non-fluorine-containing Halide ion source is made.

Of the Term "radiation-sensitive Silver halide " radiation-sensitive silver halide prepared in situ, ex Radiation-sensitive silver halide prepared in situ and mixtures from radiation-sensitive silver halides prepared in situ and ex situ.

The UAg of an aqueous liquid is referred to in this specification as the voltage difference between a silver electrode (having a purity of 99.99%) in the aqueous liquid and a salt bridge connected to the liquid via a salt bridge consisting of a 10% KNO ₃ salt solution. AgCl reference electrode defined in a 3M KCl solution at room temperature.

S is defined as the exposure in mJ / m ² at which the photothermographic recording material has an optical density of 1.0 above the Dmin. The lower the S value, the higher the radiation sensitivity of the photothermographic recording material.

Of the Term "thermal solvent" indicates in the present Invention on a non-hydrolyzable organic material, the at temperatures below 50 ° C in the solid state in the recording layer, but at Heating to a temperature of more than 60 ° C in the heated area to a Plasticizer for the recording layer in the heated Area becomes and / or turns out as dissolving liquid for at least one of the redox reagents, e.g. the reducing agent for the first Silver salt, pressed.

Under the term used in the present invention "under substantially anhydrous conditions heat-developable "goes without saying warming to a temperature between 80 ° C and 250 ° C under conditions where the reaction system is almost in equilibrium with water in the air and water for triggering or promoting the reaction is not in the air Particular or noticeable from the outside of the thermographic Fed recording material becomes. Such a condition is described by T.H. James in "The Theory of the Photographic Process ", 4th Edition, Macmillan 1977, page 374 described.

First aqueous dispersion, the radiation-sensitive silver halide prepared ex situ and a substantially light-insensitive silver salt of an organic carboxylic acid contains

The first aqueous dispersion contains so-called ex situ prepared silver halide, wherein the ex situ prepared silver halide is either mixed with particles of a substantially light insensitive silver salt of an organic carboxylic acid or is contained during the preparation of the particles of the substantially light insensitive silver salt of an organic carboxylic acid as described in U.S. Patent No. 4,360,854 US Pat. No. 3,839,049 , The first aqueous dispersion may further contain a first ex situ prepared radiation-sensitive silver halide, although the third aqueous dispersion further contains the first radiation-sensitive silver halide prepared in situ. So-called in situ prepared silver halides are obtained by conversion of a substantially light-insensitive silver salt of an organic carboxylic acid with a non-fluorine halide ion source as described in US Pat US 3,457,075 WO 97/48104 and WO 97/48105.

The Process for the preparation of the first aqueous according to the invention Dispersion, the radiation-sensitive silver halide and a substantially light-insensitive silver salt of an organic carboxylic acid all a step in that while the manufacturing process a pH of at least 8.0 is achieved. This will produce the unexpected result that the Dmin value without air conditioning at elevated Temperatures and high relative humidities at least stabilized is, with the drift of the Dmin value at 1 week storage in the dark at 20 ° C and about 45% relative humidity is negligible. It is preferred this pH is adjusted with ammonia, either as ammonia gas or in the form of an aqueous Ammonia solution. The pH may be during preferably not exceed 10.5 of the manufacturing process.

In a preferred embodiment the method for producing the first aqueous according to the invention Dispersion is the substantially light-insensitive silver salt of a organic carboxylic acid a silver salt of an aliphatic carboxylic acid having more than 12 carbon atoms.

The Process for the preparation of the first aqueous according to the invention Dispersion preferably also includes the addition of a water-soluble Silver salt with a solubility in water at 20 ° C of more than 0.1 g / l at all stages of the manufacturing process.

Second aqueous dispersion, the radiation-sensitive silver halide prepared ex situ contains

When Silver halide may be any radiation-sensitive silver halide can be used, e.g. Silver bromide, silver iodide, silver chloride, silver bromide iodide, Silver chlorobromoiodide or silver chlorobromide. The silver halide may be in any radiation-sensitive form such as in a non-limiting way, in cubic, orthorhombic, tabular, tetrahedral or octagonal shape and may be epitaxial Crystal growth on the surface exhibit.

The used according to the invention Although silver halide can be used without modification, it may with a chemical sensitizer such as a compound containing sulfur, Contains selenium or tellurium, a compound containing gold, platinum, palladium, iron, ruthenium, rhodium or iridium contains, a reducing agent such as tin halide or a combination the same are chemically sensitized. More details about this Methods are by T.H. James in The Theory of the Photographic Process, 4th Edition, Macmillan Publishing Co. Inc., New York (1977), Chapter 5, pages 149 to 169, described.

The Grain size of the silver halide particles can according to the Moeller-Teller-procedure are determined, wherein the silver halide containing Pattern is sedimented on filter paper, which is then together with a needle-shaped negative platinum electrode and a reference electrode in electrolyte is immersed. The silver halide particles on the filter paper be with the needle-shaped Electrode slowly scanned individually, after which the silver halide grains on the cathode can be reduced individually electrochemically. At this Electrochemical reduction is given a current pulse, as Function of time is recorded and then integrated to the charge transfer Q for the electrochemical reduction of the silver halide particle corresponding to the Particle volume is proportional to obtain. From the grain volume let yourself the equivalent Circle diameter of each grain and from this the mean particle size and particle size distribution determine.

The proportion of the radiation-sensitive silver halide used according to the invention is between 0.1 and 100 mol%, preferably between 0.2 and 80 mol%, particularly preferably between 0.3 and 50 mol%, very particularly preferably between 0.5 and 35 mol% and in particular between 1 and 12 mol%, based on the substantially light-insensitive silver salt of an organic carboxylic acid.

The second watery, radiation-sensitive silver halide-containing dispersion can according to conventional Dispersion techniques such as those described in Chapter III of the book The Theory of the Photographic Process ", 4th edition, ed. T.H. James, Eastman Kodak (1977) ", be made.

Third aqueous dispersion, which is a substantially light-insensitive silver salt of an organic Contains carboxylic acid

In Section II of the Research Disclosure published in June 1978 No. 17029 is an overview various processes for the preparation of organic silver salts. To obtain a fine dispersion of an organic heavy metal salt must be either the synthesis in an organic solvent guided be described, for example, in US-P 3,700,458, or in a mixture of water and a substantially water-insoluble organic solvents, such as. described in U.S. Pat. No. 3,960,908 for silver carboxylates.

Preferred substantially light-insensitive silver salts of an organic carboxylic acid are the silver salts of organic carboxylic acids which, in particular, contain as their organic group an aryl, aralkyl, alkaryl or alkyl group. For example aliphatic carboxylic acids known as fatty acids in which the aliphatic carbon chain preferably contains at least 12 carbon atoms, eg silver laurate, silver palmitate, silver stearate, silver hydroxystearate, silver oleate and silver behenate, these silver salts being also referred to as "silver soaps". Silver salts of aliphatic carboxylic acids modified with a thioether group, as described, for example, in GB-P 1,111,492, and silver salts of carboxylic acids as described in Research Disclosure 17029, but not the silver salts of heterocyclic thione group-substituted organic carboxylic acids as described in Research Disclosure 12542 and US 3,785,830 , are also suitable for the production of a thermally developable silver image in question.

In a preferred according to the invention embodiment is the substantially light-insensitive silver salt of an organic carboxylic acid a silver salt of a fatty acid.

Of the Term "essential light-insensitive silver salt of an organic carboxylic acid "also includes Mixtures of different organic silver salts.

to Preparation of the third aqueous Dispersion containing such a substantially light-insensitive silver salt an organic carboxylic acid contains come any conventional Dispersion techniques in question, for example, a ball mill, a Microfluidizer, a bead mill etc., in combination with anionic surfactants, nonionic surfactants and / or dispersing agents. The third aqueous dispersion, which is a significant light-insensitive silver salt of an organic carboxylic acid may also be prepared directly as described in EP-A 848 286 and EP-A 754 969.

Fourth aqueous dispersion, a second in situ prepared radiation-sensitive silver halide and a substantially light-insensitive silver salt of an organic carboxylic acid contains

The fourth aqueous dispersion contains a second silver halide prepared in situ. So-called silver halide produced in situ can be prepared by converting a substantially light-insensitive silver salt of an organic carboxylic acid with a non-fluorine-containing halide ion source as described in US Pat US 3,457,075 WO 97/48104 and WO 97/48105.

The Process for the preparation of the first aqueous according to the invention Dispersion, the radiation-sensitive silver halide and a contain substantially light-insensitive silver salt of an organic carboxylic acid, all involve a step in which during the manufacturing process a pH of at least 8.0 is achieved. This will be the unexpected Result achieved that the Dmin value without air conditioning at elevated temperatures and high relative humidities is at least stabilized, the drift of the Dmin value being 1 week in the dark at 20 ° C and about 45% relative humidity is negligible. It is preferred this pH is adjusted with ammonia, either as ammonia gas or in the form of an aqueous Ammonia solution. The pH may be during preferably not exceed 10.5 of the manufacturing process.

In a preferred embodiment of the process for preparing the fourth aqueous dispersion according to the invention, the substantially light-insensitive silver salt of an organic carboxylic acid is a Sil Compound of an aliphatic carboxylic acid having more than 12 carbon atoms.

The Process for the preparation of the fourth aqueous according to the invention Dispersion preferably also includes the addition of a water-soluble Silver salt with a solubility in water at 20 ° C of more than 0.1 g / l at all stages of the manufacturing process.

water-soluble silver salt

While at usual photographic emulsions by adding a water-soluble Silver salt in a dispersion of radiation-sensitive silver halide before the coating process a photographic material with a lot high degree of haze, we have unexpectedly found that by adding a silver salt with a water solubility greater than 0.1 g / L of water in an aqueous dispersion containing essentially light-insensitive and substantially insoluble in water organic silver salt and a radiation-sensitive silver halide contains unexpectedly much lower S-values and therefore much higher radiation sensitivity is achieved as with the addition of ammonia or the soluble Silver salt alone with a negligible effect on the background density of copies printed with it.

preferred water-soluble Silver salts have a solubility in water at 20 ° C of more than 1 g / l.

Used according to the invention suitable water-soluble Silver salts are u.a. Silver nitrate, silver acetate, silver propionate, Silver sulfate, silver butyrate, silver isobutyrate, silver benzoate, silver tartrate, Silver salicylate, silver malonate, silver succinate and silver lactate, being water-soluble Silver salts from the group consisting of silver nitrate, silver acetate, Silver lactate and silver sulfate are preferred.

Out Silver halide photography is known to be soluble Silver salts in a silver halide dispersion increase the UAg value (= decrease in pAg value = increase in the ratio free silver ions) and as a result a partial reduction of contained silver salts and thereby the formation of metal silver germs trigger can. Such metal silver germs go with a higher degree of fog in photographic Silver halide accompanied. Maybe it's an analogue Effect that occurs when adding water-soluble silver salt Increase in sensitivity.

photo-addressable developable element

The Photothermographic recording material in which the first and the fourth aqueous dispersion according to the invention can be used a carrier and a photo-addressable heat-developable Element satisfying two requirements: (i) it contains a first Silver salt, a reducing agent for the first silver salt in thermal effective relationship thereto, a radiation-sensitive silver halide and a binder, and (ii) it contains a layer through Coating with a first aqueous dispersion according to the invention or a fourth aqueous according to the invention Dispersion is obtained.

These two requirements overlap in that the first watery Dispersion an ex situ prepared radiation-sensitive silver halide and a third aqueous one Contains dispersion, containing the substantially light-insensitive silver salt of an organic carboxylic acid and optionally a reducing agent for the substantially light-insensitive Silver salt of an organic carboxylic acid, a spectral sensitizer, a supersensitizer, one or more stabilizers and a binder, or the fourth aqueous dispersion, the above-mentioned third aqueous Emulsion, some of which in a second, in situ produced radiation-sensitive Silver halide is converted, and optionally a reducing agent for the Substantially light-insensitive silver salt of an organic carboxylic acid, a spectral sensitizer, a supersensitizer, or contains several stabilizers and a binder.

The photoaddressable thermally developable element may comprise a single layer, ie a layer made with the aqueous dispersion according to the invention, or several layers, one of which is made with the first or fourth aqueous dispersion and the other layers contain the necessary ingredients for image formation, eg a reducing agent for the first silver salt, a binder, a tinting agent and one or more stabilizers. In this layer system, the radiation-sensitive silver halide is said to be catalytically related to the substantially light-insensitive silver salt of an organic carboxylic acid, and the spectral sensitizer optionally together with a supersensitizer is intimately sensitizing to the silver halide particles, and is intended to aid the others in heat development or pre- or post-stabilization Elements involved in of the same layer or in different layers, provided that the organic reducing agent and the optional toning agent are in effective thermal relationship to the substantially light insensitive silver salt of an organic carboxylic acid, ie during the heat development process, the reducing agent and the optional toning agent must be present in such a way capable of diffusing to the particles of the substantially light-insensitive silver salt of an organic carboxylic acid.

The Photo-addressable heat-developable Element can also be provided with a protective layer.

organic reducing agent

Suitable organic reducing agents for the reduction of the substantially light-insensitive silver salt of an organic carboxylic acid are organic compounds containing at least one active hydrogen bonded to O, N or C, as is the case with aromatic di- and tri-hydroxy compounds, aminophenols, METOL ^™ , p Phenylenediamines, alkoxynaphthols, for example 4-methoxy-1-naphthol, as described in US Pat. No. 3,094,412, pyrazolidin-3-one-type reducing agents, for example PHENIDONE ^™ , pyrazolin-5-ones, indan-1,3- dione derivatives, hydroxytetronic acids, hydroxytetronimides, hydroxylamine derivatives, as described, for example, in US Pat. No. 4,082,901, hydrazine derivatives and reductones, for example ascorbic acid. It is also noted in U.S. Patents 3,074,809, 3,080,254, 3,094,417 and 3,887,378. Particularly suitable reducing agents are sterically hindered phenols, bisphenols, sulfonamidophenols and the reducing agents described in WO97 / 04357.

It can also combinations of reducing agents are used, the when heated to participants in the reduction reaction of the substantially light-insensitive Silver salt of an organic carboxylic acid. Suitable for Example combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents, as described in U.S. Pat. No. 5,464,738, trityl hydrazides and formylphenyl hydrazides, as described in U.S. Pat. No. 5,496,695, trityl hydrazides and formylphenyl hydrazides with various auxiliary reducing agents as described in US-P 5,545,505, US 5,545,507 and US 5,558,983, acrylonitrile compounds, as described in US-P 5,545,515 and US-P 5,635,339, and 2-substituted Malonodialdehyde compounds as described in US Pat. No. 5,654,130.

Binder for the photoaddressable developable element

The film-forming binders for use in the aqueous dispersions and in the photo-addressable heat-developable Element in which the first and fourth inventive aqueous dispersion can be used, a water-dispersible or water-soluble Be a binder.

suitable water-soluble film-forming binders are polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic Polyethylene glycol, polyvinylpyrrolidone, proteinaceous binders such as gelatin, modified gelatins such as phthaloyl gelatin, polysaccharides, like strength, Gum arabic and dextran, and water-soluble cellulose derivatives.

suitable Water-dispersible binders are all water-insoluble Polymers, e.g. water Cellulose derivatives, Polyurethanes, polyesters, polycarbonates and polymers derived from α, β-ethylenically unsaturated Compounds such as post-chlorinated polyvinyl chloride, partially hydrolyzed Polyvinyl acetate, polyvinyl acetals, preferably polyvinyl butyral, and homopolymers and copolymers of monomers consisting of the group of vinyl chloride, vinylidene chloride, acrylonitrile, acrylamide, methacrylamide, Methacrylate, acrylate, methacrylic acid, acrylic acid, vinyl ester, Styrene, diene or alkene or mixtures thereof.

It It should be noted that there are no tiny polymer particles clear transition between a polymer dispersion and a polymer solution, whereby the smallest particles of the polymer in dissolved form and the slightly larger particles will be in dispersed form.

Also preferred are water-dispersible binders with crosslinkable Groups, e.g. Epoxy groups, acetoacetoxy groups and crosslinkable ones Double bonds. Preferred water-dispersible binders for Use in the photo-addressable heat-developable element, in which the first and fourth aqueous dispersion according to the invention are used are polymeric latices, as described in WO 97/04355 are.

The mentioned above Binders or mixtures thereof may be used in combination with waxes or "thermal Solvents ", also referred to as" thermal solvents ", the the reaction rate of the redox reaction at elevated temperature increase, be used.

spectral sensitizer

The Photo-addressable heat-developable Element of the photothermographic recording material in which the first and fourth aqueous Dispersion according to the invention can be used and aqueous dispersions according to the invention can a spectral sensitizer for the silver halide, optionally in combination with a supersensitizer, wherein the Sensitizer sensitizing the wavelength of the used light source, the near infrared light, visible light, e.g. 630 nm or 670 nm, or infrared light can be effected. The silver halide can be mixed with various known dyes such as Cyanine dyes, merocyanine dyes, styryl dyes, hemicyanine dyes, Oxonol dyes, hemioxonol dyes and xanthene dyes and optionally, especially in the case of sensitization to infrared radiation, spectrally sensitized in the presence of a supersensitizer become. Useful cyanine dyes include i.a. those with a basic Ring such as a thiazoline ring, an oxazoline ring, a pyrroline ring, a pyridine ring, an oxazole ring, a thiazole ring, a selenazole ring and an imidazole ring. Useful preferred merocyanine dyes are u.a. those that except the above-described basic ring also an acid ring such as a thiohydantoin ring, a rhodanine ring, an oxazolidinedione ring, a thiazolidinedione ring, a barbituric ring, a thiazolinone ring, a malononitrile ring and a pyrazolone ring. Both Cyanine and merocyanine dyes described above are those having Imino or carboxyl groups particularly useful.

supersensitisers

The Photosensitive heat-developable Element in which the first and fourth inventive aqueous dispersion can be used and aqueous dispersions according to the invention can further contain a supersensitizer. Preferred supersensitizers are mercapto compounds, disulfide compounds, stilbene compounds, Organoborate compounds and styryl compounds.

tint

To the Obtain a neutral black image tone in the upper density zones and of neutral gray in the lower density zones can be the photoaddressable developable Element in which the first and fourth inventive aqueous dispersion can be used and aqueous dispersions according to the invention one or more toning agents contain. The toning agents should while the heat processing in thermally effective relationship with the substantially light-insensitive Silver salt of an organic carboxylic acid stand.

Stabilizers and antifreeze

A further improvement of storage stability and background density can be by embedding stabilizers and antifoggants in the photo-addressable heat-developable Element in which the first and fourth inventive aqueous dispersion can be used and aqueous dispersions according to the invention be achieved.

carrier

Of the carrier for the Photothermographic recording material in which the first and fourth aqueous dispersion according to the invention can be used and aqueous dispersions according to the invention can be translucent, translucent or opaque and is preferred a thinner one flexible carrier from e.g. Paper or polyethylene-coated paper or a film transparent resin, e.g. from a cellulose ester, e.g. cellulose triacetate, Polypropylene, polycarbonate or polyester, e.g. Polyethylene terephthalate. The carrier may be in the form of a bow, ribbon or web and if necessary with Subbed an adhesive layer. The carrier can also be made from a be prepared opacified resin composition

antihalation

The photothermographic recording materials in which the first and fourth invention aqueous dispersion can also contain antihalation dyes or screening dyes which absorb the light penetrated by the heat-sensitive heat-developable photographic material and thus prevent reflection of that light. Such dyes may be incorporated in the photoaddressable thermally developable element or in any other layer of the photothermographic recording material in which the first and fourth aqueous dispersions of the present invention can be used.

Antistatic layer

In a preferred embodiment of the photothermographic invention Recording material in which the first and fourth inventive aqueous dispersion can be used gets on the outer layer applied an antistatic layer.

Surfactants and dispersant

surfactants are surface active Means, being soluble Compounds is the interfacial tension between a liquid and reduce a solid. The aqueous according to the invention Dispersions can anionic, nonionic or amphoteric surfactants, wherein anionic and nonionic are preferred as described in WO 97/04356. Suitable dispersants are natural polymers Substances, synthetic polymeric substances and finely divided Powder, e.g. finely divided non-metallic inorganic powders such as silica.

coating process

The Application of a layer of the aqueous dispersions of the invention can by Any coating method, for example by Procedures used in "Modern Coating and Drying Technology ", Edited by Edward D. Cohen and Edgar B. Gutoff, (1992) VCH Publishers Inc., 220 East 23rd Street, Suite 909, New York, NY 10010, USA, are described.

Photo Thermographic print

The Exposure of photothermographic recording materials in which the first and fourth inventive aqueous dispersion used can be can use radiation with a wavelength between the wavelength of X-rays and a wavelength of 5 nm, the image either by pixel-wise exposure with a focused light source such as a cathode ray tube, a Ultraviolet laser, a laser for visible Light, an infrared laser such as a He / Ne laser, an infrared laser diode, the e.g. emitted at 780 nm, 830 nm or 850 nm, or a light-emitting Diode (LED), for example a 659 nm emitting LED, or but by direct exposure of the object itself or an image of the article with a suitable exposure source, e.g. an ultraviolet source, visible light or infrared light becomes.

For the heat development of imagewise exposed Photothermographic recording materials in which the first and fourth aqueous dispersion of the invention can be used comes any heat source in question, within a for the respective application acceptable period uniform Heating the recording materials to the development temperature secures, e.g. Contact heating, radiant heating and microwave heating.

Industrial application

Photothermographic Recording materials in which the first and fourth inventive aqueous dispersion can be used can for the Generation of both transparencies, for example in the field medical diagnostics, where black-image transparency is widespread at with a viewing device working examination techniques can be used as well as supervised copies are used to Example in the graphic hard copy area and in microfilm applications. For such Applications becomes the carrier translucent or opaque, i.e. a white light having reflective aspect. When using a translucent support can the carrier colorless or colored be, e.g. colored blue for medical Diagnostic applications.

The following INVENTIVE EXAMPLES 1 to 6 and COMPARATIVE EXAMPLES 1 and 2 illustrate the present invention. The percentages are expressed in weight, if nothing else is noted. The following ingredients are used:

• R16875 = R16875, eine Phthaloylgelatine von ROUSSELOT,
• K7598 = Typ 7598, eine calciumfreie Gelatine von AGFAGEVAERT GELATINEFABRIEK,
• AgB = Silberbehenat,
• LOWINOX 22IB46 = 2-Propyl-bis-(2-hydroxy-3,5-dimethylphenyl)methan von CHEM. WERKE LOWI,
• SENSI 01 =
  
• Tensid Nr. 1 = MARLON^TM A-396, ein Natriumalkylphenylsulfonat von Hüls,
• Tensid Nr. 2 = ERKANTOLTM BX, ein Natriumdiisopropylnaphthalinsulfonat von BAYER,
• Tensid Nr. 3 = ULTRAVON^TM W, als 75–85%iges Konzentrat eines Natriumarylsulfonats erhältlich durch CIBA-GEIGY,
• STABI 01 =
  
• STABI 02 = 4-Methylphthalsäure,
• STABI 03 = Phenyltribrommethylsulfon,
• TA01 = Phthalazin,

Photo-addressable heat-developable element:

• R16875 = R16875, a phthaloyl gelatin from ROUSSELOT,
• K7598 = Type 7598, a calcium free gelatin from AGFAGEVAERT GELATINEFABRIEK,
• AgB = silver behenate,
• LOWINOX 22IB46 = 2-propyl bis (2-hydroxy-3,5-dimethylphenyl) methane from CHEM. WORKS LOWI,
• SENSI 01 =
  
• Surfactant # 1 = MARLON ^™ A-396, a sodium alkylphenyl sulfonate from Huls,
• Surfactant No. 2 = ERKANTOL ™ BX, a sodium diisopropylnaphthalenesulfonate from BAYER,
• Surfactant # 3 = ULTRAVON ^™ W, as a 75-85% Concentrate of a Sodium Aryl Sulfonate Available from CIBA-GEIGY
• STABI 01 =
  
• STABI 02 = 4-methylphthalic acid,
• STABI 03 = phenyltribromomethylsulfone,
• TA01 = phthalazine,

• K7598 = Typ 7598, eine calciumfreie Gelatine von AGFAGEVAERT GELATINEFABRIEK, vorm. KOEPFF & SÖHNE,
• KIESELSOL 300F = eine 30%ige wässrige Dispersion von kolloidaler Kieselsäure von BAYER,
• LATEX 01 = ein Poly(ethylacrylat)-Latex,
• ANTIHALO 01 (Lichthofschutzstoff) =
  

antihalation:

• K7598 = Type 7598, a calcium-free gelatin from AGFAGEVAERT GELATINEFABRIEK, before. KOEPFF & SONS,
• KIESELSOL 300F = a 30% aqueous dispersion of colloidal silica from BAYER,
• LATEX 01 = a poly (ethyl acrylate) latex,
• ANTIHALO 01 (antihalation) =
  

• K7598 = Typ 7598, eine calciumfreie Gelatine von AGFAGEVAERT GELATINEFABRIEK, vorm. KOEPFF & SÖHNE,
• Tensid Nr. 4 = Ammoniumsalz von Perfluorcaprylsäure.

Protective layer:

• K7598 = Type 7598, a calcium-free gelatin from AGFAGEVAERT GELATINEFABRIEK, before. KOEPFF & SONS,
• Surfactant # 4 = ammonium salt of perfluorobutyric acid.

manufacturing of radiation-sensitive silver halide

The Silver halide emulsion consisting of 11.44 wt .-% 100 mol% silver bromide with a Moeller-Teller method (see above for more details Data) of the particle size of 73 nm and 5.17 wt% X16875 as a dispersant in demineralized Water is made according to conventional Silver halide production techniques prepared at 50.5 ° C, such as from T.H. James in "The Theory of the Photographic Process ", 4th Edition, Macmillan Publishing Co. Inc., New York (1977), Chapter 3, pages 88-104.

INVENTIVE EXAMPLES 1 to 6 & COMPARATIVE EXAMPLES 1 and 2

• i) 136,2 g (0,4 Mol) Behensäure werden bei einer Geschwindigkeit von 310 TpM mit einem Typhoon-Rührer mit einem Durchmesser von 80 mm unter Rühren in einem Gefäß mit einem Durchmesser von 200 mm in 549 ml einer 10%igen Lösung von Tensid Nr. 1 und 662 g entmineralisiertem Wasser bei 80°C dispergiert,
• ii) anschließend werden 188 ml einer 2-molaren wässrigen Lösung von Natriumhydroxid bei einer Geschwindigkeit von 310 TpM mit einem Typhoon-Rührer mit einem Durchmesser von 80 mm bei einer Temperatur von 80°C und über 10 Minuten hinweg in das Gefäß mit einem Durchmesser von 200 mm eingerührt, um eine klare Lösung, die als Hauptbestandteil Natriumbehenat enthält, zu erhalten,
• iii) anschließend werden 360 ml einer 1-molaren wässrigen Silbernitratlösung bei einer Geschwindigkeit von 310 TpM mit einem Typhoon-Rührer mit einem Durchmesser von 80 mm bei einer Temperatur von 80°C und über 4,5 Minuten hinweg in das Gefäß mit einem Durchmesser von 200 mm eingerührt, um das Natriumbehenat völlig in Silberbehenat umzuwandeln.

Single-jet preparation of silver behenate dispersions in an aqueous medium without using an organic solvent The aqueous silver behenate dispersion used in INVENTION EXAMPLES 1 and 6 and COMPARATIVE EXAMPLES 1 and 2 is prepared as follows

• i) 136.2 g (0.4 mol) of behenic acid are mixed at a rate of 310 ppm with a Typhoon stirrer with a diameter of 80 mm with stirring in a vessel with a diameter of 200 mm in 549 ml of a 10% solution of surfactant No. 1 and 662 g of demineralized water at 80 ° C,
• (ii) then add 188 ml of a 2 molar aqueous solution of sodium hydroxide at a rate of 310 ppm with a Typhoon stirrer of 80 mm diameter at a temperature of 80 ° C and for 10 minutes in the vessel of diameter Stirred 200 mm to obtain a clear solution containing sodium behenate as its main component,
• iii) then 360 ml of a 1 molar aqueous silver nitrate solution at a speed of 310 ppm with a Typhoon stirrer with a diameter of 80 mm at a temperature of 80 ° C and over 4.5 minutes in the vessel with a diameter of 200 mm stirred to convert the sodium behenate completely in silver behenate.

The thus obtained aqueous Contains silver behenate dispersion 8.15 wt .-% of silver behenate and 2.78 wt .-% of the surfactant No. 1 and will follow desalted and by ultrafiltration to an aqueous dispersion of 22.37 Concentrated by weight% silver behenate.

manufacturing of watery dispersions

26.2 g K7598 are dissolved in 150 g demineralised water at 40 ° C. In these Be gelatin solution then 19.35 g of a 11.44% by weight silver halide dispersion for 20 seconds, which corresponds to 11.7 mmol of silver halide, stirred. Then be the amounts of ammonia listed in Table 1 as a 2.5% by weight aqueous solution before, while or after the addition of the in Table 1 for the various EXAMPLES amount of silver nitrate added as a 3.56% by weight aqueous solution and the resulting dispersion is kept at a constant temperature from 40 ° C made up to 265.4 g with demineralised water. After stirring for 1 hour 40 ° C is the UAg measured (UAg-1), after which 206.6 g of the above described silver behenate dispersion added together with 2.4 g of 1N nitric acid and after another 20 minutes stir at 40 ° C a second UAg measurement (UAg-2) is made.

To the second UAg measurement, the following ingredients are added: 8.7 g of a solution containing 4 g / l SENSI 01, followed by stirring for 20 minutes, then 11.8 g of an 8 wt .-% solution in methanol from STABI 01 and finally just before the order 112 g of a dispersion containing 4.68% by weight phthalazine, 16.84% by weight LOWINOX 22IB46 and 2 wt .-% surfactant no. 2 contains

Table 1

Production of photothermographic recording materials

to Preparation of an antihalation dispersion 62.5 g K7598 dissolved in 1 liter of demineralized water at 40 ° C. Then the following will be Ingredients to the resulting gelatin solution added: 14.5 g of a 10 wt .-% aqueous solution of ANTIHALO 01, 8 g of a 10% by weight aqueous dispersion of LATEX 01 and 42 g of a 20 wt .-% aqueous dispersion of KIESELSOL 300F, after which the pH is adjusted to 6 before the resulting solution in a wet layer thickness of 45 μm on one side of a subbed 100 μm thick polyethylene terephthalate aufzurakeln and 5 minutes at 25 ° C. to dry.

Subsequently, will a solution for the first layer of heat-sensitive Elements, wherein 42.5 g K7598 demineralized in 1928.2 g Water of 40 ° C solved and then the following ingredients are stirred: 8.7 g STABI 02, 179.1 g of a STABI 03 dispersion (consisting of 17.5% by weight STABI 03, 10 wt% K7598 and 1 wt% surfactant # 1), 6 g in 227.3 g of methanol dissolved 1-phenyl-5-mercaptotetrazole and 17.4 g of a 10% solution of Surfactant No. 3.

On which is not coated with the antihalation layer side then in a wet layer thickness of 50 μm the solution for the first layer of heat-sensitive Elements after 5 minutes drying at 25 ° C, the first Layer of heat-sensitive Elements is obtained.

On the first layer of heat-sensitive Elements is then in a wet film thickness of 100 microns the above-described aqueous Dispersion after 5 minutes drying at 25 ° C, the second Layer of heat-sensitive Elements is obtained.

Finally will on the second layer of the heat-sensitive Elements in a wet layer thickness of 50 μm one solution of 57 g of K7598 in 2,560 g of demineralized water, to which 78 g a 5 wt .-% solution of surfactant # 4 was applied, drying after 5 minutes of drying at 25 ° C a protective layer is obtained.

Evaluation of photothermographic recording materials

The photothermographic recording materials of INVENTION EXAMPLES 1 to 6 and COMPARATIVE EXAMPLES 1 and 2 are first exposed with a He-Ne laser (632.8 nm) behind a grayscale wedge used for grading the film exposure and then heated at 100 ° C for 20 seconds. to create a wedge image. The variation of the print density in the wedge image is determined with a MACBETH TD903 densitometer with an optical filter and is a representation of the dependence of the optical density on the applied exposure. The S-values defined as the exposure in mJ / m ² , at which an optical density of 1.0 over Dmin is reached, are calculated from this relationship optical density / exposure. The lower the exposure value S required to obtain an optical density of 1.0 above Dmin, the higher the radiation sensitivity of the photothermographic material.

The Photothermographic evaluation is performed on freshly coated photothermographic Recording materials and after 1 week storage in the dark at 20 ° C and about 45% relative humidity. This will be the change the background density Dmin (ΔDmin) and the S-values (ΔS) are determined. The results of the evaluation of the photothermographic recording materials of the INVENTION EXAMPLES 1 to 6 and COMPARATIVE EXAMPLES 1 and 2 are shown below Table 2 listed.

Compared to the Dmin and S values obtained with the photothermographic recording material of Comparative Example 1, the photothermographic recording materials obtained with the freshly coated and after 1-week storage in the dark at 20 ° C and about 45% relative humidity show the INVENTION EXAMPLES 1 to 6 recorded Dmin and S values that a much smaller change in Dmin and S values can be observed by addition of ammonia alone in quantities of 1.256 to 1.889 mol / mol of silver halide, as can be seen from the lower ΔDmiri value (+0.13 to +0.15 compared to +0.91) and the lower .DELTA.S-value (0 to +349 mJ / m ² compared to +509 mJ / m ²⁾ according to 1wöchiger storage in the dark at 20 ° C and about 45 % relative humidity.

Table 2

The photothermographic recording material of the invention EXAMPLE 1 has the best overall performance, ie the lowest Dmin value for the fresh material and the lowest change in the Dmin value with a ΔDmin value of +0.15 and a ΔS value of 0 mJ / m ² . On the other hand, the S values of 501 and 1,000 mJ / m ² for the fresh photothermographic recording materials of INVENTION EXAMPLES 1 and 2 are very high, indicating a low radiation sensitivity.

The addition of both ammonia and a soluble silver salt such as silver nitrate yields the photothermographic recording materials of INVENTION EXAMPLES 3 to 6 with S-values for fresh materials 79 to 100 mJ / m ^2, ie, radiation-sensitivities among the values with ammonia alone (501 and 1,000 mJ / m ² for the fresh photothermographic recording materials of INVENTION EXAMPLES 1 and 2, respectively) or soluble silver salt alone (141 mJ / m ² for the novel photothermographic recording materials of COMPARATIVE EXAMPLE 2). When adding both ammonia and a soluble silver salt, therefore, an unexpected synergistic effect is observed.

Becomes the aqueous according to the invention solution except Silver nitrate an aqueous solution of ammonia in an amount of 1.256 to 1.889 moles / mole of silver halide added, so receives So you photothermographic recording materials with a noticeable reduction in Dmin change, taking after 1 week storage in the dark at 20 ° C and about 45% relative humidity ΔDmin values from +0.07 to +0.16 (INVENTION EXAMPLES 3 to 6) compared to +0.57 for the photothermographic material of the COMPARATIVE EXAMPLE 2 are obtained.

The moment of adding the same amount of the aqueous solution of ammonia, ie, simultaneously with the addition of silver nitrate, as in Inventive Example 4, after adding the silver nitrate, as in Inventive Example 5, or before adding the second silver salt as in Inventive Example 6, has no influence, ie, within the experimental error range, on the imaging performance of the resulting photothermographic recording materials (results in Table 2).

To the detailed description of preferred embodiments of the present invention It should be clear to the experts in this field that here within the scope of the following claims numerous modifications possible are.

Claims (13)

A process characterized by the following steps for the preparation of a first aqueous dispersion comprising an ex-situ prepared radiation-sensitive silver halide and a substantially light-insensitive silver salt of an organic carboxylic acid: separately preparing a second aqueous radiation-sensitive silver halide-containing dispersion prepared ex situ and a third aqueous the substantially light-insensitive silver salt of an organic carboxylic acid-containing dispersion, and mixing the second aqueous dispersion with the third aqueous dispersion to produce a mixture of these two dispersions, characterized in that the first aqueous dispersion thus prepared substantially free of a water-soluble metal salt or ammonium salt of an aliphatic carboxylic acid with more than 12 carbon atoms and the method further comprises a step of the following group of steps: S increasing the pH of the second aqueous dispersion to at least 8.0 before mixing it with the third aqueous dispersion, increasing the pH of the third aqueous dispersion to at least 8.0 before mixing it with the second aqueous dispersion and increasing the pH of the aqueous solution. Value of the mixture to at least 8.0. Manufacturing method according to claim 1, characterized in that that the third aqueous Dispersion also a first, in situ produced radiation-sensitive Contains silver halide. Production method according to claim 1 or 2, characterized characterized in that the pH of at least 8.0 by adding ammonia is reached. Manufacturing method according to one of claims 1 to 3, characterized in that the substantially light-insensitive Silver salt of an organic carboxylic acid a silver salt of an aliphatic Carboxylic acid with is more than 12 carbon atoms. One after a manufacturing process after one of the preceding claims preparable first aqueous Dispersion which is an ex-situ produced radiation-sensitive Silver halide and a substantially light-insensitive silver salt an organic carboxylic acid contains. First watery Dispersion according to claim 5, characterized in that the first aqueous Dispersion further a reducing agent for the substantially light-insensitive Contains silver salt of an organic carboxylic acid. Use of the first aqueous dispersion according to claim 5 or 6 for producing a photo-addressable heat-developable Elements of a photothermographic recording material, wherein the photoaddressable heat developable Element radiation-sensitive silver halide, the essential light-insensitive silver salt of an organic carboxylic acid Reducing agent for it in a thermally effective relationship thereto and a binder. A process characterized by the steps of producing a fourth aqueous dispersion comprising a second in situ prepared radiation-sensitive silver halide and a substantially light-insensitive organic carboxylic acid silver salt: (i) providing the third aqueous dispersion of claim 1 and (ii) partial conversion the substantially light-insensitive silver salt of an organic carboxylic acid in the third aqueous dispersion in the second, in situ prepared radiation-sensitive silver halide using a non-fluorine halide ion source, wherein an aqueous dispersion is obtained, the substantially light-insensitive silver salt of an organic carboxylic acid and the second, in situ prepared radiation-sensitive silver halide, characterized in that the thus prepared fourth aqueous dispersion substantially free of a water-soluble metal salt or Ammo nium salt of an aliphatic carboxylic acid having more than 12 carbon atoms and the method further comprises a step of the following group of steps: increasing the pH of the third aqueous dispersion to at least 8.0 before step (ii), increasing the pH of the third aqueous dispersion to at least 8.0 during step (ii) and increasing the pH of the aqueous dispersion obtained from step (ii) to at least 8.0. Manufacturing method according to claim 8, characterized in that that the pH reaches at least 8.0 by adding ammonia becomes. Manufacturing method according to claim 8 or 9, characterized characterized in that the substantially light-insensitive silver salt an organic carboxylic acid a silver salt of an aliphatic carboxylic acid having more than 12 carbon atoms is. One after a manufacturing process after one the claims 8 to 10 preparable fourth aqueous Dispersion, which is a second, in situ produced radiation-sensitive Silver halide and a substantially light-insensitive silver salt an organic carboxylic acid contains. Fourth aqueous Dispersion according to claim 11, characterized in that the fourth aqueous Dispersion further a reducing agent for the substantially light-insensitive Contains silver salt of an organic carboxylic acid. Use of the fourth aqueous dispersion according to claim 11 or 12 for producing a photo-addressable heat-developable Elements of a photothermographic recording material, wherein the Photo-addressable heat-developable Element radiation-sensitive silver halide, which is substantially light-insensitive Silver salt of an organic carboxylic acid, a reducing agent for this in thermal effective relationship to it and containing a binder.