DE60304811T2 - Toner for use in near-light-insensitive recording materials - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The The present invention relates to toning agents for use in substantially light-insensitive thermographic Recording materials.

GENERAL STATE OF THE ART

The Thermography is a heating step comprehensive imaging process and thus also includes the photothermography in which the image forming process is an imagewise exposure and direct thermal processes, wherein the imaging process a pictorial heating step includes. Direct thermal printing becomes a visible pattern by imagewise heating of a Produced recording material.

Thiazoline-2-thione and benzothiazoline-2-thione compounds are well known as toning agents in silver halide-based photographic DTR materials in which they are used in a liquid developer, for example GB 1 101 927 . US 3,433,640 and US 3,702,246 and in photographic silver halide materials in which they are combined as toning agents with different stabilizers, for example US 3 418 131 , 3,666,471, JP 07-306492 and JP 11-202444. Furthermore, in US Pat. No. 3,620,749 radiation-sensitive compositions containing silver complexes of 3-alkylbenzothiazoline-2-thiones in combination with 2-mercapto-1,3,4-oxadiazole derivatives, as well as radiation-sensitive elements containing such compositions disclosed.

wobei X eine zur Bildung eines durch eine -SO₃M-, -COOM- und/oder -OM-Gruppe substituierten Heteroringes benötigte Atomgruppe darstellt, X eine durch eine -SO₃M-, -COOM- und/oder -OM-Gruppe substituierte Atomgruppe mit möglicher Heterozyklusbildung darstellt und M ein Wasserstoffatom, ein Metallatom, eine quaternäre Ammonium- oder Phosphoniumgruppe darstellt, jedoch nicht der Substruktur -NH-C(=S)- in der heterocyclischen Struktur entspricht,

wobei A₁ und A₁, eine -SO₃M-, -COOM- oder -OM-Gruppe darstellen, M ein Wasserstoffatom, ein Metallatom, eine quaternäre Ammonium- oder Phosphoniumgruppe darstellt, wobei sogar wenn A₁ und A₁, die gleiche Bedeutung haben, sie unterschiedlich sein können, m eine ganze Zahl zwischen 1 und 10 bedeutet, A₂ und A₂, eine elektronenanziehende Gruppe bedeuten, wobei sogar wenn A₂ und A₂, die gleiche Bedeutung haben, sie unterschiedlich sein können, n eine ganze Zahl zwischen 1 und 10 darstellt, A₃ und A₃, jeweils eine funktionelle Gruppe mit einem S-, Se- oder Te-Atom in eventueller Kombination mit einem Komplexion darstellen, wobei sogar wenn A₃ und A₃, die gleiche Bedeutung haben, sie unterschiedlich sein können, r 0 oder 1 bedeutet, Y, Y₁ und Y₂ eine alifatische, aromatische oder heterocyclische Gruppe bedeuten, Z ein S-, Se- oder Te-Atom bedeuten und p1 oder 2 bedeutet.JP 11-202444 discloses a heat-developable heat-sensitive material containing at least one kind of compound represented by the following general formulas (1), (2) or (3):

wherein X represents an atomic group needed to form a hetero ring substituted by a -SO ₃ M, -COOM and / or -OM group, X represents an -SO ₃ M, -COOM and / or -OM group represents a substituted atomic group with possible heterocyclic formation and M represents a hydrogen atom, a metal atom, a quaternary ammonium or phosphonium group, but does not correspond to the substructure -NH-C (= S) - in the heterocyclic structure,

wherein A ₁ and A _{1 represent} an -SO ₃ M, -COOM or -OM group, M represents a hydrogen atom, a metal atom, a quaternary ammonium or phosphonium group, even if A ₁ and A _{1 are} the same Have meaning that they may be different, m is an integer between 1 and 10, A ₂ and A _{2 are} an electron attracting group, and even if A ₂ and A _{2 are} the same, they may be different, n is one represents integer between 1 and 10, A ₃ and A ₃ , each represent a functional group with an S, Se or Te atom in eventual combination with a complex ion, even if A ₃ and A _{3 have} the same meaning in that they may be different, r is 0 or 1, Y, Y ₁ and Y _{2 are} an aliphatic, aromatic or heterocyclic group, Z is an S, Se or Te atom and p is 1 or 2.

JP 11-202444 also describes the following substances:

In US 4,451,561 discloses a heat-developable recording material comprising on a support a heat-developable image-forming layer comprising (a) an organic silver salt, (b) a reducing agent, (c) a binder, and (d) at least one amide derivative of a 5-mercapto-1, Contains 3,4-triazoles or 5-mercaptothiadiazoles.

In US Pat. No. 3,080,254 there is disclosed a typical heat-sensitive copying paper containing in the heat-sensitive layer a thermoplastic binder, eg, ethylcellulose, a water-insoluble silver salt, eg, silver stearate, and a suitable organic reducing agent, for which 4-methoxy-1-hydroxydihydronaphthalene is a typical example. Spatial heating of the sheet in the thermographic reproduction process, or for testing purposes, by temporary contact with a metal test bar heated to a suitable transition temperature in the range of approximately 90-150 ° C causes a visible change in the heat-sensitive layer. The initially white or light colored layer darkens brownish in the heated area. To obtain a more neutral hue, the composition of the heat-sensitive layer is added with a heterocyclic organic tinting agent such as phthalazinone.

in der R¹, R², R³ und R⁴ jeweils ein Wasserstoffatom, eine Alkylgruppe, eine Arylgruppe, eine Acylamidgruppe, ein Halogenatom, eine Hydroxylgruppe oder eine Nitrogruppe darstellen.U.S. Patent No. 3,885,967 discloses a radiation-sensitive material for a heat-developable photosensitive element comprising a) a silver laurate or silver caprate-containing silver salt component, b) a catalytic amount of a radiation-sensitive silver halide component comprising a radiation-sensitive silver halide or a compound containing silver laurate or silver caprate reacting to form a radiation-sensitive silver halide, c) a reducing agent, d) a binder and e) a tinting agent with a compound of the formula:

represent R ^1, R ^2, R ³ and R ⁴ each represents a hydrogen atom, an alkyl group, an aryl group, an acylamide group, a halogen atom, a hydroxyl group or a nitro group.

in der R¹ ein Wasserstoffatom, -CH₂OH, -(C=O)-R, -CONHR oder M bedeutet, R², R³, R⁴ und R⁵ unabhängig voneinander jeweils ein Wasserstoffatom, -O-(C=O)-OR oder -NH-(C=O)-OR bedeuten und zumindest eines dieser R-Elemente kein Wasserstoffatom ist, wenn R¹ auch ein Wasserstoffatom darstellt, R eine gegebenenfalls substituierte Alkylgruppe oder Arylgruppe darstellt und M ein einwertiges Schwermetallion darstellt.EP-A-0 752 616 discloses a thermographic material composed of at least one element, said element (s) containing a substantially light-insensitive organic heavy metal salt and an organic reducing agent therefor, said material being capable of to form an image by heating from the organic heavy metal salt and the reducing agent, and the material contains a 1,3-benzoxazine-2,4-dione tinting agent of the general formula (I):

in which R ^{1 is} a hydrogen atom, -CH ₂ OH, - (C = O) -R, -CONHR or M, R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom, -O- (C = O) -OR or -NH- (C = O) -OR and at least one of these R-elements not a hydrogen atom when R ¹ represents a hydrogen atom, R represents an optionally substituted alkyl group or aryl group, and M represents a monovalent heavy metal ion.

differences between thermography and photography

Of the Exposure market has long recognized that between the field thermography, which is both photothermography and substantially light-insensitive Thermography includes, and the field of thermography significant Differences exist. Photothermographic and substantially light-insensitive thermographic materials are quite different from conventional ones photographic silver halide materials that undergo development with the help of watery development solutions require.

at Photothermographic and substantially light-insensitive thermographic Imaging materials is the creation of a visible image a warming due to the reaction of a developer contained in the element. For this Development requires a temperature of at least 50 ° C. Become routine for photothermographic Materials temperatures of more than 100 ° C and for significantly light-insensitive thermographic materials requires even higher temperatures. Conventional, wet however, require developable photographic imaging elements to produce a visible image a development in aqueous processing baths (e.g., developing and fixing baths) and the development leading to the creation of a visible image takes place usually more moderate Temperatures (e.g., 30 ° C to 50 ° C).

For photothermographic elements, only a small amount of silver halide is used to absorb light, and another type of silver (eg, silver behenate) serves to thermally form the image. The imaged silver halide serves as a catalyst for the physical development process with the non-radiation-sensitive, reducible silver source and the incorporated reducing agent. On the other hand, conventional wet-processed black-and-white photographic materials use only a single silver species (ie, silver halide) that will self-translate into the silver image upon chemical development or physical development will add an external source of silver (or other reducible metal ions which, when reduced to the corresponding metal Black images result) requires. Thus, photothermographic materials require an amount of silver halide per unit area that is only a fraction (not more than 1/100) of the amount used in a conventional wet-developed photographic material.

at Moreover, photothermographic systems are all for imaging required "chemical Components "im Material included. Exemplary contain such materials a developer (i.e., a reducing agent for the reducible silver ions), while which is usually not the case with photographic materials. Even with so-called "instant photography" are the chemical Development components up to the desired development moment physically separated from the radiation-sensitive silver halide. With the incorporation of the developer into substantially light-insensitive thermographic and photothermographic materials are at a higher risk This is accompanied by different types of "fog" and other unwanted sensitometric side effects occur. For this reason was in the preparation and manufacture essentially light-insensitive thermographic and photothermographic Materials very much strived for these problems during the Preparation of the essentially light-insensitive thermographic and photothermographic dispersions, as well as during coating, storage and post-processing handling to a minimum.

at Moreover, photothermographic materials are the unexposed silver halide After development usually still intact and needs the material protected from further image formation and development. In conventional photographic materials, on the other hand, the silver halide is after the development in a solution removed from the material (i.e., during the aqueous fixing step) to prevent further image production.

at Photothermographic and substantially light-insensitive thermographic Materials is a variety of binders in question and are several binders (both hydrophilic and hydrophobic binders) available. In conventional photographic materials, on the other hand, the selection is almost exclusively on limited to hydrophilic binders such as gelatin.

There photothermographic and substantially light-insensitive thermographic Elements a heat development require other factors during their manufacture and use considered and pose other problems than traditional wet-developed photographic silver halide materials. Ingredients that are conventional photographic silver halide materials have a certain effect cause, when used in substantially light-insensitive thermographic or photothermographic materials with their significantly more complex underlying basic chemistry quite different behavior. The use of such ingredients, including, for example, stabilizers, Antifreeze, sensitivity enhancing substances, sensitizers, Supersensitizers and spectral and chemical sensitizers counting, in conventional photographic materials does not allow statements regarding possible Advantages or disadvantages of using them in substantially light-insensitive thermographic or photothermographic materials. exemplary is not it unusual that one in conventional Photographic materials useful photographic anti-fog when used in substantially light-insensitive thermographic or photothermographic materials, various types of fog or that supersensitizers with proven efficacy in photographic materials no effectiveness in photothermographic Have materials.

These and other differences between photothermographic and essential light-insensitive thermographic materials and photographic Materials are described in "Imaging Processes and Materials" (Neblette's Eighth Edition), J. Sturge et al, publisher: van Nostrand Rheinhold, New York, 1989, chapter 9, in "Unconventional Imaging processes "E. Brinckman et al., Editors: The focal Press, London and New York, 1978, pp. 74-75, and in "J. Imaging Sci. Technol. " Zou, Sahyun, Levy and Serpone, 1996, 40, pp. 94-103.

differences between essentially light-insensitive thermographic recording materials and photothermographic recording materials

The technology of substantially light-insensitive thermographic materials in which the images The reduction in organic silver salts is significantly different from that of photothermographic materials, despite the fact that imaging in both cases is based on the reduction of organic silver salts. However, this is a superficial similarity which masks the very different composition of the substances catalyzing this reduction, ie in photothermographic recording materials image-wise exposure of radiation-sensitive silver halide photoaddressable heat-developable elements is performed, while in thermographic recording materials imagewise heating of heat-sensitive elements containing no radiation-sensitive silver halide he follows. Other clear features of the difference in technology are the nature of the ingredients used in the two types of material, the most notable being the absence of radiation-sensitive silver halide and spectral sensitizers in substantially non-photosensitive thermographic recording materials, as well as the different types of reducing agents used, in Furthermore, the heat development processes themselves are substantially different in that the whole material in the case of photothermographic recording materials within seconds (eg 10 s) to temperatures of less is heated as 150 ° C, while the materials in the case of substantially light-insensitive thermographic recording materials at much higher temperatures within milliseconds (eg 10-20 ms) are imagewise heated. Due to the very short heating times, the generation of a neutral image tone is a significant problem with substantially non-photosensitive thermographic recording materials, while this problem is much less pronounced with photothermographic materials due to the much longer heating times.

problem

Essential light-insensitive thermographic materials from the current Tinting agents known from the prior art have weak storage properties, as is the case for example, phthalazinone, and / or an image color with insufficient neutral tone in black and white pictures, as is the case with, for example, succinimide, phthalimide, phthalic acid and Phthalazine. By using 3,4-dihydro-2,4-dioxo-1,3,2H-benzoxazine as a tinting agent in thermographic materials as described in US-P 3,951,660, an improvement of the storage properties and the neutrality of the image tone has been achieved in both substituted form as described in U.S. Patent 3,885,967 and U.S. Patent 3,951,660, as in unsubstituted form as described in US Pat. No. 3,951,660. Such tinting agents are not enough soluble in ecological acceptable coating solvents and thermographic materials containing these toning agents an undesirable severe deterioration of the image color as well as an undesirable increase in the image Image background (veil) during storage. Furthermore, such migrate tint through the thermographic materials to the thermal head, causing cloudiness (Turbidity) in the imaging material, deposition of ingredients and by-products from the imaging process to the surface of the thermographic material and, in the case of substantially light-insensitive thermographic Materials in thermal head printers, worsening the picture quality due to contamination of the thermal head leads.

TASKS OF PRESENT INVENTION

task The present invention accordingly provides the provision of tinting agents, the without impairment of the image tone in a substantially light-insensitive, for use in thermographic printers suitable thermographic recording materials be used.

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

SHORT PRESENTATION THE PRESENT INVENTION

It has surprisingly been found that compounds according to formulas (I) and (II) which adsorb particularly fast on silver nanoparticles, as evidenced by time-resolved SERS measurements (surface-enhanced Raman spectroscopy), and a rapid Aggregation of these particles causes the image tone of thermographic materials to become more neutral in the case of thermographic materials whose imaging process is based on the imagewise reduction of substantially light-insensitive organic silver salts, ie, they have so-called tinting properties. Moreover, it has been unexpectedly found that when used in a particular binder matrix, a combination of tinting agents, both with faster adsorption on silver nanoparticles and are able to effect a rapid aggregation of these particles, but on the other hand characterized by a slow or rapid migration into the polymer matrix used, favorable synergistic effects on the image tone and a spread of these effects on the surface of the thermographic materials can be achieved.

in der R¹ eine gegebenenfalls durch eine Hydroxylgruppe, Carboxylgruppe, Carboxylestergruppe, Acylgruppe oder Carbonatgruppe substituierte Alkylgruppe bedeutet, X S, O oder N-R⁶ ist, R⁶ eine gegebenenfalls substituierte Alkylgruppe bedeutet, R², R³, R⁴ und R⁵ unabhängig voneinander jeweils ein Wasserstoffatom, ein Halogenatom oder eine Alkylgruppe, eine Alkoxygruppe, eine Thioalkoxygruppe, eine Nitrogruppe, eine Cyangruppe, eine Carboxylgruppe, eine Carboxylestergruppe, eine Acylgruppe, eine Aldehydgruppe, eine Acylamidgruppe, eine Sulfonamidgruppe, eine Acylaminogruppe, eine Carbonatgruppe, eine Hydroxylgruppe oder eine Acylgruppe bedeuten oder R² und R³, R³ und R⁴ und/oder R⁴ und R⁵ unabhängig voneinander jeweils die zur Bildung einer carbocyclischen oder heterocyclischen Gruppe benötigten Atome darstellen oder R¹ und R⁵ und/oder R² und R⁶ unabhängig voneinander jeweils die zur Bildung eines heterocyclischen Ringes benötigten Atome darstellen,
oder eine Verbindung der Formel (II) verwendet wird:

in der R⁷ eine gegebenenfalls substituierte Alkylgruppe bedeutet, Y S, O oder N-R¹⁰ bedeutet, R¹⁰ eine gegebenenfalls substituierte Alkylgruppe bedeutet, R⁸ und R⁹ unabhängig voneinander jeweils ein Wasserstoffatom, ein Halogenatom oder eine Alkylgruppe, eine Alkoxygruppe, eine Thioalkoxygruppe, eine Nitrogruppe, eine Cyangruppe, eine Carboxylgruppe, eine Carboxylestergruppe, eine Acylgruppe, eine Aldehydgruppe, eine Acylamidgruppe, eine Sulfonamidgruppe, eine Acylaminogruppe, eine Carbonatgruppe, eine Hydroxylgruppe oder eine Arylgruppe bedeuten oder R⁸ und R⁹ die zur Bildung eines heterocyclischen oder nicht-aromatischen carbocyclischen Ringes benötigten Atome darstellen oder R⁸ und R¹⁰ und/oder R⁹ und R⁷ unabhängig voneinander jeweils die zur Bildung eines heterocyclischen Ringes benötigten Atome bedeuten und R⁸ und R⁹ nicht beide eine Alkylgruppe bedeuten können.The objects of the present invention are achieved by a monochrome thermographic sheet with a support and a thermosensitive element, wherein the thermosensitive element contains a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermally effective relationship thereto, a binder and at least one toning agent in that as the at least one tinting agent a compound of the formula (I):

wherein R ^{1 is} an alkyl group optionally substituted by a hydroxyl group, carboxyl group, carboxyl ester group, acyl group or carbonate group, X is S, O or NR ⁶ , R ^{6 is} an optionally substituted alkyl group, R ² , R ³ , R ⁴ and R ^{5 are} independently each represents a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a thioalkoxy group, a nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or a Acyl group or R ² and R ³ , R ³ and R ⁴ and / or R ⁴ and R ⁵ are each independently required for forming a carbocyclic or heterocyclic group atoms or R ¹ and R ⁵ and / or R ² and R ⁶ each independently represent the atoms needed to form a heterocyclic ring,
or a compound of formula (II) is used:

wherein R ^{7 is} an optionally substituted alkyl group, YS, O or NR ¹⁰ , R ^{10 is} an optionally substituted alkyl group, R ⁸ and R ⁹ are each independently a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a Thioalkoxygruppe, a Nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or an aryl group; or R ⁸ and R ^{9 are} those for forming a heterocyclic or non-aromatic Carboxylic ring required atoms represent or R ⁸ and R ¹⁰ and / or R ⁹ and R ⁷ independently of one another in each case the required for forming a heterocyclic ring atoms and R ⁸ and R ⁹ can not both represent an alkyl group.

preferred embodiments The present invention is described in the detailed description of the present Invention described.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

definitions

Under as used in the description of the present invention Term "thermographic material" are both photothermographic Materials as substantially light-insensitive thermographic materials to understand.

The term "alkyl" includes all possible variants for each number of carbon atoms in the alkyl group, ie for three carbon atoms: n-propyl and isopropyl, for four carbon atoms: n-Bu tyl, isobutyl and t-butyl, for five carbon atoms: n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 2-methylbutyl, etc.

Of the Term "acyl group" in the description of the present invention means a - (C = O) -aryl group and a - (C = O) alkyl group.

Of the Term "carbocyclic Ring "includes both alicyclic rings as aromatic rings.

"Essential insensitive to light "means not intentionally sensitized to light.

The CIELAB values L *, a * and b * are in ASTM standard E179-90 in one R (45/0) geometry defined. Their evaluation is based on the ASTM standard E308-90. These CIELAB values are used to identify the picture tone thermographic according to the invention Materials used.

The warming in connection with that used in the present invention Expression "essential Anhydrous conditions "means a warming to a temperature of 80 ° C up to 250 ° C. Under the term used in the present invention "substantially anhydrous conditions " itself, that the reaction system is almost in equilibrium with water is in the air and water for the triggering or promoting the reaction not in particular or to a considerable degree of the outside the thermographic recording material is supplied. Such a condition is described by T.H. James in The Theory of the Photographic Process, 4th Edition, Macmillan 1977, page 374 described.

thermosensitive element

Of the as used in the present invention, term "heat-sensitive Element "is that Element containing all the image-forming components. The heat-sensitive according to the invention Element contains one or a plurality of substantially light-insensitive organic silver salts, one or more reducing agents for this in thermal effective Relationship to it and a binder. The element can be made of a layer system exist in which the above-mentioned agents in different Layers can be dispersed however, must the substantially light-insensitive organic silver salts in reactive Relative to the reducing agents, i. during the Heat development process The reducing agent must be present in such a way that it is in the particles the substantially light-insensitive organic silver salt over-diffuse and that with it the reduction to silver can take place. at Such materials may be one or more Substantially light-insensitive organic silver salts and / or a or more organic reducing agents therefor in heat-sensitive microcapsules encapsulate, as described in the as a reference to this document EP-A 0 736 799.

tint

in der R¹ eine gegebenenfalls durch eine Hydroxylgruppe, Carboxylgruppe, Carboxylestergruppe, Acylgruppe oder Carbonatgruppe substituierte Alkylgruppe bedeutet, X S, O oder N-R⁶ ist, R⁶ eine gegebenenfalls substituierte Alkylgruppe bedeutet, R², R³, R⁴ und R⁵ unabhängig voneinander jeweils ein Wasserstoffatom, ein Halogenatom oder eine Alkylgruppe, eine Alkoxygruppe, eine Thioalkoxygruppe, eine Nitrogruppe, eine Cyangruppe, eine Carboxylgruppe, eine Carboxylestergruppe, eine Acylgruppe, eine Aldehydgruppe, eine Acylamidgruppe, eine Sulfonamidgruppe, eine Acylaminogruppe, eine Carbonatgruppe, eine Hydroxylgruppe oder eine Arylgruppe bedeuten oder R² und R³, R³ und R⁴ und/oder R⁴ und R⁵ unabhängig voneinander jeweils die zur Bildung einer carbocyclischen oder heterocyclischen Gruppe benötigten Atome darstellen oder R¹ und R⁵ und/oder R² und R⁶ unabhängig voneinander jeweils die zur Bildung eines heterocyclischen Ringes benötigten Atome darstellen, oder eine Verbindung der Formel (II) verwendet wird:

in der R⁷ eine gegebenenfalls substituierte Alkylgruppe bedeutet, Y S, O oder N-R¹⁰ bedeutet, R¹⁰ eine gegebenenfalls substituierte Alkylgruppe bedeutet, R⁸ und R⁹ unabhängig voneinander jeweils ein Wasserstoffatom, ein Halogenatom oder eine Alkylgruppe, eine Alkoxygruppe, eine Thioalkoxygruppe, eine Nitrogruppe, eine Cyangruppe, eine Carboxylgruppe, eine Carboxylestergruppe, eine Acylgruppe, eine Aldehydgruppe, eine Acylamidgruppe, eine Sulfonamidgruppe, eine Acylaminogruppe, eine Carbonatgruppe, eine Hydroxylgruppe oder eine Arylgruppe bedeuten oder R⁸ und R⁹ die zur Bildung eines heterocyclischen oder nicht-aromatischen carbocyclischen Ringes benötigten Atome darstellen oder R⁸ und R¹⁰ und/oder R⁹ und R⁷ unabhängig voneinander jeweils die zur Bildung eines heterocyclischen Ringes benötigten Atome bedeuten und R⁸ und R⁹ nicht beide eine Alkylgruppe bedeuten können.The objects of the invention are achieved by a substantially light-insensitive single-sheet black and white recording material comprising a support of a heat-sensitive element, the heat-sensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal effective relation thereto, a binder and at least one tinting agent, characterized in that as the at least one toning agent a compound of the formula (I):

wherein R ^{1 is} an alkyl group optionally substituted by a hydroxyl group, carboxyl group, carboxyl ester group, acyl group or carbonate group, X is S, O or NR ⁶ , R ^{6 is} an optionally substituted alkyl group, R ² , R ³ , R ⁴ and R ^{5 are} independently each represents a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a thioalkoxy group, a nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or a Aryl group or R ² and R ³ , R ³ and R ⁴ and / or R ⁴ and R ⁵ are each independently the represent atoms needed to form a carbocyclic or heterocyclic group, or R ¹ and R ⁵ and / or R ² and R ⁶ are each independently the atoms needed to form a heterocyclic ring, or a compound of formula (II) is used:

wherein R ^{7 is} an optionally substituted alkyl group, YS, O or NR ¹⁰ , R ^{10 is} an optionally substituted alkyl group, R ⁸ and R ⁹ are each independently a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a Thioalkoxygruppe, a Nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or an aryl group; or R ⁸ and R ^{9 are} those for forming a heterocyclic or non-aromatic Carboxylic ring required atoms represent or R ⁸ and R ¹⁰ and / or R ⁹ and R ⁷ independently of one another in each case the required for forming a heterocyclic ring atoms and R ⁸ and R ⁹ can not both represent an alkyl group.

As suitable possible substituents for the alkyl groups of R ¹ , R ⁶ , R ⁷ and R ¹⁰ are independently carboxyl ester groups mentioned. Preferably, no carboxyl groups, sulfo groups and hydroxyl groups are used. Suitable substituted alkyl groups include -CH ₂ COOH, -C ₂ H ₄ COOH and -C ₂ H ₄ COOC ₂ H ₅ .

According to a second embodiment of the substantially light-insensitive single-sheet black and white recording material according to the invention, R ² , R ³ , R ⁴ and R ⁵ independently of one another each represent a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a thioalkoxy group, a nitro group, a cyano group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group or an aryl group, or R ² and R ³ , R ³ and R ⁴ and / or R ⁴ and R ⁵ are each independently the same to form a carbocyclic or Heterocyclic group required atoms or R ¹ and R ⁵ and / or R ² and R ⁶ are each independently required for forming a heterocyclic ring atoms.

According to a third embodiment of the substantially light-insensitive single-sheet black and white recording material of the invention, R ⁸ and R ⁹ independently represent a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a thioalkoxy group, a nitro group, a cyano group, a carboxylester group, an acyl group, an aldehyde group, a Acylamide group, a sulfonamide group, an acylamino group, a carbonate group or an aryl group, or R ⁸ and R ^{9 are} the atoms needed to form a heterocyclic or non-aromatic carbocyclic ring or R ⁸ and R ¹⁰ and / or R ⁹ and R ^{7 are} independently the atoms needed to form a heterocyclic ring and R ⁸ and R ⁹ can not both be an alkyl group.

To a fourth embodiment of the invention essential light-insensitive single sheet black and white recording material contains the heat sensitive Element further at least one toning agent from the group consisting of phthalazinone, phthalazinone derivatives, Pyridazone, pyridazone derivatives, Benzoxazine dione, benzoxazine dione derivatives, naphthoxazine dione and naphthoxazine dione derivatives.

Of the synergetic effect of a combination of either two tinting agents according to the invention or a tinting agent according to the invention and another toning agent, such as benzoxazinedione, a benzoxazine dione derivative, phthalazinone, a phthalazinone derivative, Pyridazone or a pyridazone derivative, while obtaining a more neutral Picture Tone as the one one would expect, if one uses the two tinting agents could add separately obtained image tone values, in our opinion on combining toning agents with on the one hand silver nanoparticle aggregate forming properties and on the other hand, very different diffusion coefficients be due.

To a fifth embodiment of the invention essential light-insensitive single sheet black and white recording material contains the heat sensitive Element at least two toning agents with a difference in diffusion in the binder of at least a factor of 2, but less than a factor of 1,000, and preferably at least a factor of 10.

In a sixth embodiment of the substantially light-insensitive single-sheet black and white recording material of the invention, R ¹ in the compound (s) of formula (I) is -CH ₂ COOR ¹¹ or -CH ₂ CH ₂ COOR ¹¹ wherein R ^{11 is} a hydrogen atom or an alkyl group means.

According to a seventh embodiment of the substantially light-insensitive single-sheet black and white recording material according to the invention, the compound (s) of the formula (I) are selected from the following group:

According to an eighth embodiment of the substantially light-insensitive black and white single-sheet recording material of the invention R ⁷ is in (one of) compound (s) of formula (II) -CH ₂ COOH or -CH ₂ CH ₂ COOH.

According to a ninth embodiment of the substantially light-insensitive single-sheet black and white recording material according to the invention, the compound (s) of the formula (II) are selected from the following group:

According to a tenth embodiment of the substantially light-insensitive single-sheet black and white recording material according to the present invention, the heat-sensitive element further contains at least one tinting agent selected from the group consisting of benzo [e] - [1,3] oxazine-2,4-dione, 7-methylbenzo [e] [1,3] -oxazine-2,4-dione, 7-methoxybenzo [e] - [1,3] -oxazine-2,4-dione, 7-butoxybenzo [e] - [1,3] -oxazine 2,4-dione, 7- (ethyl carbonate) benzo [e] - [1,3] oxazine-2,4-dione,

Suitable toning agents of the formula (I) according to the invention are listed in the following table:

Suitable toning agents of the formula (II) according to the invention are listed in the following table:

organic silver salt

To an eleventh embodiment of the invention essential light-insensitive single sheet black and white recording material the organic silver salts no organic double salts, the one Silver cation in combination with a second cation, e.g. Magnesium- or iron ions.

To a twelfth embodiment of the invention essential light-insensitive single sheet black and white recording material at least one of the organic silver salts is a substantially light-insensitive Silver salt of an organic carboxylic acid.

To a thirteenth embodiment of the invention essential light-insensitive single sheet black and white recording material at least one of the organic silver salts is a substantially light-insensitive Silver salt as a fatty acid known aliphatic carboxylic acid, in which the aliphatic carbon chain is preferably at least Contains 12 carbon atoms, e.g. Silver laurate, silver palmitate, silver stearate, silver hydroxystearate, Silver oleate and silver behenate, these silver salts also be referred to as "silver soaps". Other silver salts of an organic carboxylic acid as described in GB-P 1,439,478, e.g. Silver benzoate, also come for the production a heat-developable Silver picture in question. Combinations of different silver salts an organic carboxylic acid are also suitable for use in the present invention, as described in EP-A 964 300.

Organic silver salts can be dispersed by standard dispersion techniques. In this case, for example, ball mills, bead mills, microfluidizers ^®, ultrasonic apparatuses, rotor stator mixers etc. have been found to be usable. Mixtures of dispersions of organic silver salts prepared by various techniques, for example mixtures of coarser and finer ground dispersions of organic silver salts, are also suitable for achieving the desired thermographic properties.

reducing agent

To a fourteenth embodiment of the invention essential light-insensitive single sheet black and white recording material the reducing agent is an organic compound containing at least one contains active hydrogen bonded to O, N or C, such as this is the case with aromatic di- and trihydroxy compounds. Preference is given to 1,2-dihydroxybenzene derivatives such as catechol, 3- (3,4-dihydroxyphenyl) propionic acid, 1,2-dihydroxybenzoic acid, gallic acid and Gallussäureester, e.g. Methyl gallate, ethyl gallate, propyl gallate and 3,4-dihydroxybenzoic acid ester, the applications included in the references incorporated herein by reference EP-A 0 692 733, EP-A 0 903 625, EP-A 1 245 403 and EP-A 1 245 404 particularly preferred, e.g. Ethyl 3,4-dihydroxybenzoate, n-butyl-3,4-dihydroxybenzoate, 3,4-dihydroxybenzaldehyde, 3,4-dihydroxyacetophenone, 3,4-butyrophenone, 3,4-dihydroxybenzophenone, 3,4-dihydroxybenzophenone derivatives, 3,4-dihydroxybenzonitrile and tannic acid.

It is also possible to use combinations of reducing agents which, when heated, become participants in the reduction reaction of the at least one substantially light-insensitive organic silver salt. Useful combinations include, for example, combinations of sterically hindered phenols with sulfonyl hydrazide reducing agents, as described in EP-A-0 022 931 US 5,464,738 , Trityl hydrazides and formylphenyl hydrazides, as in US 5,496,695 described trityl hydrazides and formylphenyl hydrazides with various auxiliary reducing agents as described in US 5,545,505 . US 5,545,507 and US 5 558 983 , Acrylonitrile compounds as described in US 5,545,515 and US 5 635 339 , and 2-substituted malondialdehyde compounds as described in US 5,654,130 ,

binder the heat-sensitive Elements

When film-forming binder for the heat sensitive Element are all kinds of natural, modified natural or synthetic resins or mixtures of such resins in which the organic silver salt (s) either in aqueous media or solvent media is homogeneously dispersible, e.g. Cellulose derivatives, starch ethers, Gallactomannan, polymers derived from α, β-ethylenically unsaturated Compounds such as polyvinyl chloride, post-chlorinated polyvinyl chloride, Copolymers of vinyl chloride and vinylidene chloride, copolymers of Vinyl chloride and vinyl acetate, polyvinyl acetate and partially hydrolyzed Polyvinyl acetate, polyvinyl alcohol, polyvinyl acetals made from polyvinyl alcohol as starting material, in which only part of the repeating Optionally reacted with an aldehyde, are prepared, preferably polyvinyl butyral, copolymers Acrylonitrile and acrylamide, polyacrylates, polymethacrylates, polystyrene and polyethylene or mixtures thereof.

suitable water-soluble, film-forming binders for use in substantially insensitive to light according to the invention Recording materials are polyvinyl alcohol, polyacrylamide, polymethacrylamide, polyacrylic acid, polymethacrylic Polyvinylpyrrolidone, polyethylene glycol, proteinaceous binders, Polysaccharides and water-soluble Cellulose derivatives. A preferred water-soluble binder for use in essential to the invention light-insensitive recording materials is gelatin.

The weight ratio the binder to the organic silver salt is preferably between 0.2 and 7 and the strength the heat-sensitive Elements preferably between 5 and 50 microns. Preference is given to binders without additives, such as certain antioxidants (e.g., 2,6-di-tert-butyl-4-methylphenol), or foreign substances that the thermographic properties of the essential light-insensitive recording materials in which it uses be affected.

stabilizers

To a fifteenth embodiment of the invention essential light-insensitive single-sheet black and white recording material contains the heat-sensitive Element further a stabilizer.

in der R³ eine -NR⁴R⁵-Gruppe, eine -OR⁶-Gruppe oder eine gegebenenfalls substituierte Arylgruppe oder Heteroarylgruppe bedeutet, R⁴ ein Wasserstoffatom oder eine gegebenenfalls substituierte Alkylgruppe, Arylgruppe oder Heteroarylgruppe bedeutet, R⁵ eine gegebenenfalls substituierte Arylgruppe oder Heteroarylgruppe bedeutet und R⁶ eine gegebenenfalls substituierte Arylgruppe bedeutet, und Verbindungen mit zwei oder mehr Gruppen der Formel (IV):

in der Q die zur Bildung eines 5- oder 6-gliedrigen ungesättigten heterocyclischen Ringes benötigten Atome bedeutet, A ein Wasserstoffatom, ein Gegenion zum Ausgleichen der Negativladung der Thiolatgruppe bedeutet oder zwei oder mehr A-Gruppen eine Verbindungsgruppe zwischen den zwei oder mehr Gruppen der Formel (IV) darstellen.According to a sixteenth embodiment of the substantially light-insensitive cut sheet black and white recording material of the present invention, the heat-sensitive element further contains a stabilizer selected from the group consisting of benzotriazole, substituted benzotriazoles, aromatic polycarboxylic acid such as orthophthalic acid, 3-nitrophthalic acid, tetrachlorophthalic acid, mellitic acid, pyromellitic acid and trimellitic acid and anhydrides thereof, 1-phenyl-5-mercaptotetrazole compounds in which the phenyl group is substituted by a substituent with an optionally substituted aryl group, 1- (5-mercapto-1-tetrazolyl) -acetyl compounds of the formula (III):

in which R ^{3 is} an -NR ⁴ R ⁵ group, an -OR ⁶ group or an optionally substituted aryl group or heteroaryl group, R ^{4 is} a hydrogen atom or an optionally substituted alkyl group, aryl group or heteroaryl group, R ^{5 is} an optionally substituted aryl group or Heteroaryl group and R ⁶ denotes an optionally substituted aryl group, and compounds having two or more groups of the formula (IV):

wherein Q represents the atom needed to form a 5- or 6-membered unsaturated heterocyclic ring, A represents a hydrogen atom, a counterion to balance the negative charge of the thiolate group, or two or more A groups represent a linking group between the two or more groups of the formula (IV).

To a seventeenth embodiment of the invention essential light-insensitive single-sheet black and white recording material contains the heat-sensitive Element further at least one optionally substituted aliphatic or carbocyclic polycarboxylic acid and / or their anhydride in a mole percentage of at least 15, based on the total amount of the (the) organic silver salts (s) and in a thermally effective relationship thereto. The polycarboxylic acid can be used in anhydride form or partially esterified form, provided that contain at least two free carboxylic acids or in the Heat recording step available.

Surfactants and dispersant

surfactants and dispersants facilitate the dispersion of ingredients, which are not soluble in the dispersion medium used. The invention used Substantially light-insensitive material may be one or more, anionic, nonionic or cationic surfactants and / or one or more Contain dispersant. Suitable dispersants are natural polymeric substances, synthetic polymeric substances and finely divided Powder, for example, finely divided non-metallic inorganic Powder like silica.

carrier

To a nineteenth embodiment of the invention essential light-insensitive single sheet black and white recording material the carrier a translucent or translucent carrier. Preferably, the carrier a thinner one flexible carrier of a sheet of transparent resin, e.g. from a cellulose ester, 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 subbed to bond to the heat-sensitive material applied to it Element to improve. The carrier can be colored or pigmented to provide a translucent colored background for the image receive.

protective layer

To a twentieth embodiment of the invention essential light-insensitive monolayer black and white recording material is the heat sensitive Element provided with a protective layer. The protective layer protects that thermosensitive Element usually from humidity and surface damage by scratching etc. and prevents direct contact from printheads or Heat sources with the recording layers. On protective layers for heat-sensitive Elements that come into contact with a heating source and under pressure brought past it Need to become, the requirement is made that they be resistant to local deformation and have good sliding properties when used during the Heating be promoted by the heat source over. A sliding layer, the outermost layer is, can be solved from one Lubricant and / or a particulate material such as e.g. talc particles consist of, optionally, the outer layer protrude. examples for suitable lubricants are surfactants, liquid lubricants, solid lubricants or mixtures thereof with or without polymeric Binder.

coating techniques

Of the Application of any layer of the inventively used light-insensitive Material can be made by any coating technique, such as. described 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. For coating one can watery or solvent media use, on which then dried, partially dried or Undried layers are applied.

thermographic processing

The thermographic image formation takes place by imagewise exposure with heat, either analogously by direct exposure through an image or by reflection from an image or in a digital manner pixel-by-pixel exposure with an infrared heater source, for example a Nd: YAG laser or other infrared laser, one essential light-insensitive thermographic material, preferably contains an infrared absorbing compound, or by direct thermal Imaging with a thermal head.

Under thermal pressure, image signals are converted into electrical impulses which are then selectively applied to a thermal print head via a driver circuit. The thermal print head consists of microscopic thermal resistance elements that convert the electrical energy into heat via the Joule effect. The operating temperature of conventional thermal printing heads is between 300 and 400 ° C and the heating time per pixel is 1.0 ms or less, wherein the pressure contact of the thermal print head with the recording material, for example, between 200 and 1,000 g / running cm, ie at a contact area (Grip area) between 200 and 300 microns, a pressure between 5,000 and 50,000 g / cm ^{2 is} applied to a good To ensure heat transfer.

The Control of the heating elements can be power modulated or at constant Power pulse length modulated become. EP-A 654 355 describes a method of production a picture by imagewise heating by means of a thermal head with excitable heating elements, wherein the Control of the heating elements after a duty cycling operation he follows. In EP-A 622 217 a method for producing a Image using a direct thermal imaging element discloses improvements in halftone reproduction become.

For the imagewise warming of the Recording material is also suitable embedded in the material electrical resistance band. The imagewise or patternwise heating of the Recording material can also be modulated by a pixel-by-pixel Ultrasound treatment be made.

industrial application

The thermographic imaging can be used for the generation of both Supervision copies and transparencies are used, in particular in medical diagnostics, when working with a viewing device exam techniques Black-and-white transparency find widespread application.

The The following comparative and inventive examples illustrate the present invention. The percentages and ratios in these examples are in weight, unless otherwise stated is.

Inhaltsstoffe des wärmeempfindlichen Elements außer den obengenannten Inhaltsstoffen: BL5HP = S-LEC BL5HP, ein Polyvinylbutyral von SEKISUI, Öl = BAYSILON, ein Silikonöl von BAYER, VL = DESMODUR VL, ein 4,4'-Diisocyanatdiphenylmethan von BAYER, Reduktionsmittel: R01 = 3,4-Dihydroxybenzonitril, R02 = 3,4-Dihydroxybenzophenon, Stabilisatoren: S01 = Glutarsäure, S02 = Tetrachlorphthalsäureanhydrid S03 = Benztriazol, Tönungsmittel:

Inhaltsstoffe der Schutzschicht: ERCOL^TM 48 20 = ein Polyvinylalkohol von ACETEX EUROPE, LEVASIL^TM VP AC 4055 = eine 15%ige wässrige Dispersion von kolloidaler Kieselsäure mit vorwiegend mit Natriumionen neutralisierten Säuregruppen und einer spezifischen Oberfläche von 500 m²/g von BAYER AG / umgewandelt in das Ammoniumsalz, ULTRAVON^TM W = 75–85%iges Konzentrat eines Natriumarylsulfonats von Ciba Geigy, umgewandelt in eine Säure nach Passage durch eine Ionenaustauschsäule, SYLOID^TM 72 = Kieselsäure von Grace, SERVOXYL^TM VPDZ 3/100 = ein Mono[isotridecylpolyglycolether-(3 EO)]-phosphat von SERVO DELDEN B.V. SERVOXYL^TM VPAZ 100 = ein Gemisch aus Monolauryl- und Dilaurylphosphat von SERVO DELDEN B.V., MICROACE TALC P3 = ein indischer Talk von NIPPON TALC, RILANIT^TM GMS = ein Glycerinmonotalgsäureester von HENKEL AG, TMOS = in Gegenwart von Methansulfonsäure hydrolysiertes Tetramethylorthosilikat. Adhesive layer no. 1 on the emulsion side of the carrier has the following composition:

Ingredients of the heat-sensitive element other than the above-mentioned ingredients: BL5HP = S-LEC BL5HP, a polyvinyl butyral from SEKISUI, oil = BAYSILON, a silicone oil from BAYER, VL = DESMODUR VL, a 4,4'-diisocyanatodiphenylmethane from BAYER, Reducing agent: R01 = 3,4-dihydroxybenzonitrile, R02 = 3,4-dihydroxybenzophenone, stabilizers: S01 = Glutaric acid, S02 = Tetrachlorophthalic anhydride S03 = Benzotriazole, Tint:

Ingredients of the protective layer: ERCOL ^TM 48 20 = a polyvinyl alcohol from ACETEX EUROPE, LEVASIL ^™ VP AC 4055 = a 15% aqueous dispersion of colloidal silica with acid groups neutralized predominantly with sodium ions and a specific surface area of 500 m ² / g of BAYER AG / converted into the ammonium salt, ULTRAVON ^TM W = 75-85% concentrate of a sodium aryl sulphonate from Ciba Geigy converted to an acid after passage through an ion exchange column, SYLOID ^TM 72 = Silica from Grace, SERVOXYL ^TM VPDZ 3/100 = a mono [isotridecyl polyglycol ether (3 EO)] phosphate from SERVO DELDEN BV SERVOXYL ^TM VPAZ 100 = a mixture of monolauryl and dilauryl phosphate from SERVO DELDEN BV, MICROACE TALC P3 = an Indian talc from NIPPON TALC, RILANIT ^TM GMS = a glycerol monotassium ester from HENKEL AG, TMOS = in the presence of methanesulfonic acid hydrolyzed tetramethyl orthosilicate.

COMPARATIVE EXAMPLES 1 to 8 and INVENTION EXAMPLES 1 to 19

Influence of the connections according to the formulas (I) and (II) on the aggregation of silver nanoparticles

An assay method was developed using a silver hydrosol prepared 20 to 30 minutes prior to assaying the compounds of formulas (I) and (II). 1 ml of a 0.001 molar solution of the compound to be tested is then added to 10 ml of this yellow silver hydrosol. If discoloration of the silver hydrosol occurs within one hour, 10 ml of a 0.5% aqueous gelatin solution are added 10 seconds after this color change in order to prevent further agglomeration of silver particles. If no discoloration is observed after one hour, the ratio of the compound to be tested in the hydrosol is increased from 10 ^-4 M to 10 ^-3 M. Reference experiments are performed on each silver hydrosol lot to test performance with a 10 ^-3 molar of BOD06 which is an immediate aggregation-inducing compound.

The Absorption of silver nanoparticles is known to shift Aggregation with increasing aggregate size to ever higher wavelengths. These Displacement turns out to be a change the color of very pale yellow with 10 nm silver particles over orange to red, purple and finally blue. Accordingly, the Degree of aggregation according to the following Criteria visually according to a scale of 6 levels between ++++ and - - rated:

The with TA-I-1 to TA-I-11, TA-II-1 to TA-II-7, COMP-1 to COMP-3 and BOD01 to BOD05 obtained aggregation degrees are shown below Table 1 is listed.

Diffusion performance of Compounds according to the formulas (I) and (II)

The diffusion experiments are carried out with the surface of an applied on a glass substrate S-LEC BL5HP layer (15 g / m ² ) containing the compound to be tested in a ratio of 15 mol%, based on a quantity of silver behenate, which is a quarter of the amount S-LEC BL5HP contains, in contact with the surface of an S-LEC BL5HP layer (10 g / m ² ) coated on a SERS sample, the glutaric acid in a ratio of 24 mol% based on a quantity of silver behenate , which is a quarter of the amount S-LEC BL5HP contains. In this configuration, the SERS sample is at the top. The diffusion test is carried out by heating the S-LEC BL5HP coated glass carrier in contact with a heated electrically to a temperature of 150 ° C plate over a predetermined period. The configuration is then removed from the heated plate and a Raman spectrum is recorded by Dilor XY laser spectroscopy with the 514 nm line of a Coherent Innova 70C argon-krypton mixed gas laser at 12 mW through the glass plate, allowing determine the basis of the surface-enhanced Raman spectrum of the ingredient, whether the ingredient under investigation has over-diffused to the silver nanoparticles in the SERS sample, the spectrum being surface-enhanced due to the "surface-enhanced Raman scattering effect" (SERS effect) in contact with silver.

Of the coated glass slides and the coated SERS sample by coating the glass slide with a solution of S-LEC BL5HP in 2-butanone and the ingredient to be tested or coating the SERS sample with a solution of S-LEC BL5HP in 2-butanone and glutaric acid, drying at room temperature and finally 10 minute Heating the coated glass slide and coated SERS sample at 85 ° C produced.

The SERS sample is prepared by adding an aqueous silver nitrate solution in an aqueous Kaliumborhydridlösung and stabilization of the 5 to 10 nm silver nuclei by addition of polyvinyl alcohol, the final composition being 0.01 Mol of silver nitrate, 0.015 mol of potassium borohydride and 1% of polyvinyl alcohol contains. The resulting silver hydrosol then becomes a hardener Biocide, an inorganic pigment and a hardening regulator containing gelatin solution. The resulting mixture is in a dry film thickness of 100 nm applied to glass plates on which there is a thin, yellow, translucent, Containing silver seeds with a diameter between 5 and 10 nm Foil forms. The coated glass plate then becomes 15 minutes long in at 40 ° C heated demineralized water and then in a heated to 25 ° C 0.001 molar aqueous Silver nitrate solution 0.5% gelatin and 0.001 mole ascorbic acid, a reducing agent for silver cations, contains immersed. This immersion causes rather an electroless deposition of silver on the silver nuclei as the formation of new particles and Although germination requires much more energy than growth already existing silver germs. Finally, the 90 nm silver particles rinsed layer with demineralized water and dried. These 90 nm silver particles are for the laser wavelength (514.5 nm) used in these experiments is required. Depending on the composition of the bath, bath temperature and immersion time can obtained other silver particle sizes become.

For receiving Raman reference spectra becomes a droplet of aqueous solution in Table 1 for the various embodiments and COMPARATIVE EXAMPLES mentioned molecules attached to the SERS sample and is going through the Raman spectrum Dilor XY laser spectroscopy with the 514 nm line of a Coherent Innova 70C argon-krypton mixed gas laser recorded at 12 mW, the spectrum being surface-enhanced with silver due to the "surface-enhanced Raman scattering effect" (SERS effect).

The with TA-I-1 to TA-I-11, TA-II-1 to TA-II-7, COMP-1 to COMP-3 and BOD01 to BOD05 obtained diffusion results are shown below Table 1 is listed.

All Compounds of the invention TA-I-1 to TA-I-11 and TA-II-1 to TA-II-7 give silver particle aggregation values within 10 seconds between ++ and ++++, with only one exception, TA-I-3, in the diffusion times through the S-LEC-BLSHP and glutaric acid containing layer of 120 s or more at 150 ° C are observed.

The non-inventive compounds COMP-01 to COMP-03 cause either a very weak aggregation of silver particles or no aggregation and their diffusion properties are not evaluated.

The known from the current state of the art compounds BOD01 to BOD05 result inside for half of 10 seconds at 150 ° C a degree of aggregation between + and +++ and have diffusion times through the S-LEC-BL5HP and glutaric acid-containing layer between 5 and 30 s at 150 ° C, resulting in an undesirable rapid diffusion to the surface of essentially light-insensitive materials leads.

Table 1:

COMPARATIVE EXAMPLES 9 to 15 and INVENTION EXAMPLES 19 to 35

The essentially light-insensitive thermographic materials of the COMPARATIVE EXAMPLES 9 to 15 and INVENTION EXAMPLES 19 to 35 receives one by order one containing the following ingredients Dispersion in 2-butanone on a 175 μm blue-pigmented, on the emulsion side with adhesive layer 01 coated polyethylene terephthalate with a CIELAB a * value of -9.5 and a CIELAB b * value of -17.9, where after 3 minutes Drying at 85 ° C in a drying oven layers with those in the table below 2 compositions are obtained.

Table 2:

• * VB = comparative example
• ° EB Example according to the invention

Subsequently, the heat-sensitive elements are coated in a wet thickness of 85 .mu.m with an aqueous composition containing the following ingredients with a pH adjusted to 3.8 with 1N nitric acid, and the coating is dried at 50.degree. C. for 15 minutes to give a protective layer obtained with the following composition: ERCOL ^TM 48 20 = 2.1 g / m ² LEVASIL ^TM VP AC 4055 = 1.05 g / m ² ULTRAVON ^TM W = 0.075 g / m ² SYLOID ^TM 72 = 0.09 g / m ² SERVOXYL ^TM VPDZ 3/100 = 0.075 g / m ² SERVOXYL ^TM VPAZ 100 = 0.075 g / m ² MICROACE TALC P3 = 0.045 g / m ² RILANIT ^TM GMS = 0.15 g / m ² TMOS = 0.87 g / m ² (with complete conversion of TMOS into SiO ₂ )

The applied protective layer is characterized by 7-day heating of the essential light-insensitive thermographic material at 45 ° C and a cured relative humidity of 70%.

thermographic print

The substantially light-insensitive thermographic recording materials of COMPARATIVE EXAMPLES 9 to 15 and INVENTION EXAMPLES 19 to 35 are used in a DRYSTAR ^™ 4500 printer from AGFA-GEVAERT in a printing cycle. The printer prints at a resolution of 508 dpi, which had been changed to print at a print speed of 14 mm / s and a line time of 3.5 ms instead of 7.1 ms. In the printer, the 75 μm long (in the direction of conveyance) and 50 μm wide thermal head resistors are power modulated to print different image densities.

evaluation thermographic properties

Of the Picture tone fresher, with the substantially light-insensitive thermographic Recording materials of COMPARATIVE EXAMPLES 9 to 15 and INVENTIVE EXAMPLES 19 to 35 printed prints is based on the CIELAB values L *, a * and b * in an optical Density D of 1.0 and 2.0 evaluated. The results of the evaluation are listed in Tables 3 to 7.

Evaluation of the diffusion of ingredients and reaction products of the imaging process to the protective layer surface

The diffusion of ingredients and reaction products of the imaging process to the protective layer surface is visually evaluated according to a scale of 0 to 5 according to the following criteria:

The results for printed materials after 3 days Storage at 57 ° C and 34% relative humidity are in the tables below 3 to 7 listed.

Table 3:

Also the results in Table 3 show that even the two combinations the tinting agent according to the invention TA-I-1 and TA-I-2, respectively, with the different benzoxazine dione tinting agent BOD01 unexpectedly lead to a more neutral image tone, as can be achieved by simple Combining the properties of the two toning agents would be expected. This Result indicates an unexpected synergistic effect.

Table 4:

Also the results in Table 4 show that even the two combinations of the tinting agent according to the invention TA-I-2 with the different benzoxazine dione tinting agent BOD03 unexpectedly lead to a more neutral image tone, as you can by simple Combining the properties of the two toning agents would be expected. This Result indicates an unexpected synergistic effect.

Table 5:

Also the results in Table 5 show that also the combinations of the tinting agent according to the invention TA-I-2 with the different benzoxazine dione tinting agent Unexpectedly, BOD04 results in a more neutral picture than one would expect by simple Combining the properties of the two toning agents would be expected. This Result indicates an unexpected synergistic effect.

Table 6:

• * ANDD = Evaluation of the post-diffusion after 3 days of storage at 57 ° C and 34% relative humidity

The Results in Table 6 show that a combination of two benzoxazine dione toners neither the synergetic neutral image tone nor the synergistic reduction the diffusion results from a combination of one each Tinting agent according to the invention with a benzoxazine dione tinting agent be achieved.

Table 7:

The Results in Table 7 show that toning agents according to the invention in a specific heat-sensitive Element a little bit result in a neutral picture tone. However, these results do not close the possibility from that in another heat sensitive Element not a much bigger improvement neutrality of the picture tone could be achieved.

The The present invention may implicitly or explicitly include any herein property described, any combination of those described herein Properties or generalization thereof include, in independence of whether it relates to the invention claimed herein. Due to the above description of the present invention, it should be understood be clear to experts in this field that here within the scope of the present invention numerous modifications possible are.

Claims (5)

A substantially light-insensitive black-and-white thermographic sheet black-and-white recording material comprising a support and a thermosensitive element, the thermosensitive element comprising a substantially light-insensitive organic silver salt, an organic reducing agent therefor in thermal effective relation thereto, a binder and at least one tinting agent, characterized in that as the at least a tinting agent is a compound of the formula (I):

wherein R ^{1 is} an alkyl group optionally substituted by a hydroxyl group, carboxyl group, carboxyl ester group, acyl group or carbonate group, X is S, O or NR ⁶ , R ^{6 is} an optionally substituted alkyl group, R ² , R ³ , R ⁴ and R ^{5 are} independently each represents a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a thioalkoxy group, a nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or a Aryl group or R ² and R ³ , R ³ and R ⁴ and / or R ⁴ and R ⁵ are each independently the atoms required to form a carbocyclic or heterocyclic group or R ¹ and R ⁵ and / or R ² and R ⁶ each independently represent the atoms needed to form a heterocyclic ring, or a compound the formula (II) is used:

wherein R ^{7 is} an optionally substituted alkyl group, YS, O or NR ¹⁰ , R ^{10 is} an optionally substituted alkyl group, R ⁸ and R ⁹ are each independently a hydrogen atom, a halogen atom or an alkyl group, an alkoxy group, a Thioalkoxygruppe, a Nitro group, a cyano group, a carboxyl group, a carboxylester group, an acyl group, an aldehyde group, an acylamide group, a sulfonamide group, an acylamino group, a carbonate group, a hydroxyl group or an aryl group; or R ⁸ and R ^{9 are} those for forming a heterocyclic or non-aromatic Carboxylic ring required atoms represent or R ⁸ and R ¹⁰ and / or R ⁹ and R ⁷ independently of one another in each case the required for forming a heterocyclic ring atoms and R ⁸ and R ⁹ can not both represent an alkyl group. Thermographic recording material according to Claim 1, characterized in that the compound (s) of the formula (I) are chosen from the following group:

Thermographic recording material according to Claim 1, characterized in that the compound (s) of the formula (II) are chosen from the following group:

Thermographic recording material according to a the preceding claims, characterized in that the heat-sensitive element is further at least one toning agent from the group consisting of phthalazinone, phthalazinone derivatives, Pyridazone, pyridazone derivatives, benzoxazine dione, benzoxazine dione derivatives, naphthoxazine dione and naphthoxazinedione derivatives. A thermographic recording material according to claim 4, characterized in that the at least one benzoxazine dione derivative is selected from the group consisting of benzo [e] - [1,3] oxazine-2,4-dione, 7-methylbenzo [e] - [1, 3] -oxazine-2,4-dione, 7-methoxybenzo [e] - [1,3] -oxazine-2,4-dione, 7-butoxybenzo [e] - [1,3] -oxazine-2,4 dione, 7- (ethyl carbonate) benzo [e] - [1,3] oxazine-2,4-dione,

is selected.