EP0106772B1 - Thermographic compositions containing these developers and thermographic copying materials - Google Patents

Description

ou de leurs sels de formules :

(avec Y = X moins hydrogène dans le cas où X # H)
dans lesquelles R₁, R₂, R₃, R₄ identiques ou différents représentent H, alkyl, N0₂, halogène, aryl, NH₂, OH, COOH, S0₃H, NZ, Z₂, COOZ₃, OZ₄ (Z_i, Z_z, Z₃, Z₄ = alkyl ou aryl) X représente H ou un groupement possédant un H labile capable de former un anion stable par perte d'un proton H⁺, et M⁺ représente un cation métallique, ou de leurs mélanges, comme développeur de couleur dans des compositions thermoréactives comprenant un composé générateur de couleur, qui n'est pas un sel. De préférence, X représente H, -OH, (CH₂)_m―OH. avec 1 ≤ m ≤ 10, ou :

l'atome d'hydrogène étant particulièrement préféré. Lors d'une élévation de température, ces dérivés de la saccharine ou leurs sels réagissent avec le générateur de couleur pour donner une coloration irréversible. Ces deux types de produits sont conditionnés sur un support (papier ou autre) qui peut être utilisé dans tous les appareils ayant un système de visualisation thermique des informations : par exemple imprimantes de calculateurs, appareils de veille médicaux et industriels, télécopieurs...The present invention relates to new thermographic recording compositions, as well as the thermographic recording systems obtained from these compositions. The invention is characterized by the use of saccharin derivatives (or benzoic sulfimide, or 2,3-dihydro-1,2-benz-1,2-isothiazolone-3-dioxide-1,1) of formula:

or their formula salts:

(with Y = X minus hydrogen in the case where X # H)
in which R ₁ , R ₂ , R ₃ , R ₄ identical or different represent H, alkyl, N0 ₂ , halogen, aryl, NH ₂ , OH, COOH, S0 ₃ H, NZ, Z ₂ , COOZ ₃ , OZ ₄ ( Z _i , Z _z , Z ₃ , Z ₄ = alkyl or aryl) X represents H or a group having a labile H capable of forming a stable anion upon loss of an H ⁺ proton, and M ⁺ represents a metal cation, or of their mixtures, as a color developer in thermoreactive compositions comprising a color-generating compound, which is not a salt. Preferably, X represents H, -OH, (CH ₂ ) _m ―OH. with 1 ≤ m ≤ 10, or:

the hydrogen atom being particularly preferred. During a rise in temperature, these saccharin derivatives or their salts react with the color generator to give an irreversible coloring. These two types of products are packaged on a medium (paper or other) which can be used in all devices with a thermal information display system: for example calculator printers, medical and industrial watch devices, fax machines, etc.

• - Agent édulcorant : en effet, à cause de sa saveur sucrée intense, la saccharine trouve ici sa principale application.
• - Agent complexant de l'argent métallique formé par réduction dans un système photothermogra- phique, permettant d'intensifier les couleurs. FUJI PHOTO FILM Co., FR 1 542 505, 18 octobre 1968. 3M, US 3 080 254 (5 mars 1963). Ce brevet US 3080254 décrit des améliorations pour des papiers photothermographiques obtenues par l'incorporation de dérivés hétérocycliques dont la saccharine comme « toning agent ». Le rôle de cet agent est, par une réaction d'ionisation, de donner un anion qui réagit (formation d'un complexe d'argent) avec les ions argent (cations métalliques) adsorbés autour des grains d'argent métallique déjà formés, et conduit ainsi à des grains de plus grosse taille, donc à une image plus dense. Les particules plus grosses conduisent à une réflexion interne de la lumière, à l'intérieur de ces particules, plus importante, et donc à une image apparaissant plus noire. Dans ce cas, la saccharine sous forme anionique sert d'agent complexant pour des cations métalliques, et renforce physiquement une image métallique déjà créée par une réaction d'oxydo-réduction procédant d'un autre mécanisme dans lequel la saccharine n'intervient pas directement dans le mécanisme de formation de la couleur.

Currently, the industrial uses of saccharin and its derivatives are as follows.

• - Sweetening agent: indeed, because of its intense sweet flavor, saccharin finds its main application here.
• - Agent complexing metallic silver formed by reduction in a photothermographic system, making it possible to intensify the colors. FUJI PHOTO FILM Co., FR 1,542,505, October 18, 1968. 3M, US 3,080,254 (March 5, 1963). This patent US 3080254 describes improvements for photothermographic papers obtained by the incorporation of heterocyclic derivatives including saccharin as "toning agent". The role of this agent is, by an ionization reaction, to give an anion which reacts (formation of a silver complex) with the silver ions (metal cations) adsorbed around the metallic silver grains already formed, and thus leads to larger grains, therefore to a denser image. The larger particles lead to a greater internal reflection of light inside these particles, and therefore to an image appearing darker. In this case, the saccharin in anionic form serves as complexing agent for metal cations, and reinforces physically a metallic image already created by an oxidation-reduction reaction proceeding from another mechanism in which saccharin does not intervene directly in the color formation mechanism.

• - Agent bactéricide et fongicide : c'est le cas de certains dérivés de la saccharine substitués convenablement.

In the present application, saccharin is used in another form and in the presence of dyes to react with these.

• - Bactericidal and fungicidal agent: this is the case of certain saccharin derivatives suitably substituted.

JAPAN AGRICULTURAL CHEMICALS AND INSECTICIDES Co. LTD., Japan 72 46 059 (November 20, 1972),

MEIJI SEIKA KAISHA LTD, Japan Kokai, Tokyo Koho 79 109 968 (August 29, 1979), 79 109 986 (August 29, 1979),

• - Agent retardateur de combustion et ignifugeant :
  • DYNAMIT NOBEL A.G., Ger. offen. 2 800 019, 2 janvier 1978,
  • CIBA GEIGY A.G., Ger. Offan 2 727 699, 5 janvier 1978, Ger. Offan 2 727 775, 5 janvier 1978.
• - Catalyseur de réticulation d'adhésifs : NATIONAL STARCH AND CHEMICAL CORP., Ger. Offen 2 805 174, 1^er février 1979 et US 4 052 244, 4 octobre 1977.

KUMIAI CHEMICAL INDUSTRI Co. LTD, Japan 73 05 906 (February 21, 1973), Japan 73 08 500 (March 15, 1973), Japan Kokai 73 08 929 (February 3, 1973).

• - Fire retardant and flame retardant:
  • DYNAMIT NOBEL AG, Ger. offen. 2 800 019, January 2, 1978,
  • CIBA GEIGY AG, Ger. Offan 2,727,699, January 5, 1978, Ger. Offan 2,727,775, January 5, 1978.
• - Adhesive crosslinking catalyst: NATIONAL STARCH AND CHEMICAL CORP., Ger. Offen 2,805,174, February ^1, 1979 and US 4,052,244, 4 October 1977.

All these uses have nothing to do with the use which is the subject of the present invention: developer of color generators in thermoreactive compositions.

• - le processus de formation de l'image est simple et permet d'obtenir des reproductions de bonne qualité en ce qui concerne la couleur et le contraste,
• - les appareils utilisés sont souvent faciles à entretenir et à utiliser,
• - la feuille d'enregistrement thermique, en plus de ses performances techniques remarquables, a un coût relativement faible.

The recent increase in information and communication needs has increased the use and demand for data recording, transmission and restitution systems. Among these, thermoreactive systems are experiencing very significant growth, for several reasons:

• - the image formation process is simple and allows obtaining good quality reproductions with regard to color and contrast,
• - the devices used are often easy to maintain and use,
• - the thermal recording sheet, in addition to its remarkable technical performance, has a relatively low cost.

As heat sensitive recording sheets which can be used for these applications, we know those described initially in French patent n ° 1 440892 (NATIONAL CASH REGISTER COMPANY) and subsequently, in the cascade of patents deriving from this main system. , thus for example the patents US 3,539,375 (NCR Company) and US 3,746,675 (NCR Company).

All these patents relate to the following system: the heating induces the reaction in the molten state of a colorless or pale-colored chromogenic leuco-dye (color generator) and of a phenolic substance (developer) and leads to the formation of a colorful species.

Different leuco-coloring pairs - phenolic compounds have been described for these thermographic applications. For the former, mention may be made of: indolinic spiropyrans, lactones of triphenylmethane dyes, compounds of the fluorane family, phthalides, spirodihydropyrans (French patent No. 2,272,082), chromenes or chromanes, etc. ... For the second, we can cite: bisphenol A (isopropylidene-4,4 'diphenol), p-tertiobutylphenol, p-phenylphenol, p, p' (methyl-1-n-hexylidene) diphenol, phenolic novolak resins, etc.

• - des sels métalliques d'acides organiques, et, de préférence, gras (résinates, acétates, phénates, stéarates, ricinoléates, oléates, etc...). Brevet suisse n° 406 257 (NCR Company),
  
• - des composés de structure
  • Demande de brevet en FRANCE n° 79 28 857 (CIBA-GEIGY A. G.),
• - des carbonates ou éthers dérivés de dihydroxy-2,3 naphtalène. Demande de brevet en FRANCE n° 2427210 (78-16 954) (LA CELLOPHANE),
• - des dérivés siliciés et phosphorés du dihydroxy-2,3 naphtalène. Demande de brevet en FRANCE n° 2 427 209 (78-16 953) (LA CELLOPHANE),
• - des monoaldéhydes ou polyaldéhydes substitués électronégativement et/ou leurs produits de réaction avec un composé organique contenant des groupes hydroxyles ou bien les produits intermédiaires. Demande de brevet en FRANCE n° 2 391 858 (78-15806) (CIBA-GEIGY A.G.).

Also known as thermoreactive recording compositions are those containing other developers of the leuco-dyes described above, in place of the phenolic compounds, such as for example:

• - metallic salts of organic acids, and preferably fatty acids (resinates, acetates, phenates, stearates, ricinoleates, oleates, etc.). Swiss Patent No. 406,257 (NCR Company),
  
• - structural compounds
  • Patent application in FRANCE n ° 79 28 857 (CIBA-GEIGY AG),
• - carbonates or ethers derived from 2,3-dihydroxy naphthalene. Patent application in FRANCE n ° 2427210 (78-16 954) (LA CELLOPHANE),
• - silicon and phosphorus derivatives of 2,3-dihydroxy naphthalene. Patent application in FRANCE n ° 2 427 209 (78-16 953) (LA CELLOPHANE),
• - electronegatively substituted monoaldehydes or polyaldehydes and / or their reaction products with an organic compound containing hydroxyl groups or even the intermediate products. Patent application in FRANCE No. 2,391,858 (78-15806) (CIBA-GEIGY AG).

All these processes have, of course, their own qualities. The fact remains that most of them have imperfections, particularly with regard to the long-term stability and persistence of the recorded image. Indeed, most of these present a more or less marked weakening colors recorded under the effect of ambient light, as well as a rise of the background veil in humidity and heat.

This stability of the recorded image and of the non-colored background obviously depends on the nature and the structure of the leuco-coloring color generator used, but also on the developer chosen in combination with it. The combination chosen between the dye precursor and the developer therefore has a great importance on the preservation qualities of the paper and of the image recorded.

It has been found, according to the invention, that in thermoreactive compositions, an entirely different family of compounds could be used as a developer in association with conventional dye precursors.

dans laquelle R₁, R_z, R₃, R₄ identiques ou différents représentent alkyl, aryl, N0₂, halogène, NH₂, OH, COOH, NZ, Z₂ (Z₁, Z₂ = alkyl ou aryl) COOZ₃ (Z₃ = alkyl ou aryl), OZ₄ (Z₄ = alkyl ou aryl), S0₃H, X étant H ou un groupement possédant un H labile et capable de former un anion stable par perte d'un proton H⁺ et, de préférence, H, -OH, (CH₂)_m―OH avec 1 ≤ m ≤ 10, ou

Comme exemples non limitatifs, nous pouvons citer : la saccharine, la bromo-1' saccharine, la nitro-1' saccharine, l'amino-1' saccharine, l'acide saccharine carboxylique-5', la méta ou para disaccharine, la méthylol-1 saccharine, etc...This family consists of the saccharin derivatives of structure:

in which R ₁ , R _z , R ₃ , R ₄ identical or different represent alkyl, aryl, N0 ₂ , halogen, NH ₂ , OH, COOH, NZ, Z ₂ (Z ₁ , Z ₂ = alkyl or aryl) COOZ ₃ (Z ₃ = alkyl or aryl), OZ ₄ (Z ₄ = alkyl or aryl), S0 ₃ H, X being H or a group having a labile H and capable of forming a stable anion by loss of an H ⁺ proton and , preferably, H, -OH, (CH ₂ ) _m ―OH with 1 ≤ m ≤ 10, or

As nonlimiting examples, we can cite: saccharin, bromo-1 'saccharin, nitro-1' saccharin, amino-1 'saccharin, saccharin carboxylic acid-5', meta or para disaccharin, 1-methylol saccharin, etc.

• - Traité de chimie organique de V. Grignard « Hétérocycles à deux hétéroatomes N et S •, p. 548 et suivantes.
• - G. B. Kauffman et P. M. Priebe, Ambix, 1978, 25 (3), 191-207.

More information on these compounds, as chemicals, can be found in the following publications:

• - Treatise on organic chemistry by V. Grignard “Heterocycles with two heteroatoms N and S •, p. 548 and following.
• - GB Kauffman and PM Priebe, Ambix, 1978, 25 (3), 191-207.

(avec Y = X moins hydrogène dans le cas où X ≠ H)These saccharin-derived compounds are used, either as such, or in the form of salts:

(with Y = X minus hydrogen in the case where X ≠ H)

These salts are obtained by direct reaction of the saccharin derivative with a suitable metal salt, thus, for example, the salts of the following metals: Cu, Cd, Co, Fe (II), Ni, Mn, Zn.

• - Traité de Chimie Organique de V. Grignard « Hétérocycles à deux hétéroatomes N et S •, p. 548 et suivantes,
• - KVD, Alexander ; Kohl, Albert ; Ger. Offen 2 610 853, 22 septembre 1977,
• - MAGRI A. D. D'ASCENZO G., MUNZIANTE CESARO S., Chiacchierini, E. ; Thermochim. Acta, 1980, 36 (3) 279-86.

As literature concerning the obtaining and the conventional chemical properties of saccharin salts, we can cite:

• - Treatise on Organic Chemistry by V. Grignard “Heterocycles with two heteroatoms N and S •, p. 548 and following,
• - KVD, Alexander; Kohl, Albert; Ger. Offen 2,610,853, September 22, 1977,
• - MAGRI AD D'ASCENZO G., MUNZIANTE CESARO S., Chiacchierini, E.; Thermochim. Acta, 1980, 36 (3) 279-86.

• - un ou plusieurs générateurs de couleur (« color-former ») : ce produit peut appartenir à diverses familles chimiques classiquement utilisées en thermoréactif comme, par exemple, les lactones de colorants triphényl méthane, les fluoranes, les phtalides, les leuco-colorants de triaryl méthanes, les spiropyrannes, les chromènes, les chromanes, les leuco-colorants de phénoxazine ou phénothiazine substituée.

The thermographic recording compositions according to the invention therefore contain the constituents following kills:

• - one or more color generators (“color-former”): this product can belong to various chemical families conventionally used as a thermoreactive such as, for example, the lactones of triphenyl methane dyes, fluorans, phthalides, leuco-dyes of triaryl methanes, spiropyrans, chromenes, chromanes, leuco-dyes of phenoxazine or substituted phenothiazine.

• 3,3-bis (p-diméthylaminophényl)-6-diméthylaminophtalide (CVL), 3,3-bis-(p-diméthylaminophényl) phtalide, 3-(p·diméthylaminophényl)-3-(1,2-diméthylindole-3-yl) phtalide, 3-(p-diméthylaminophényl)-3-(2-méthylindole-3-yl) phtalide, 3,3-bis-(1,2-diméthylindole-3-yl)-5-diméthylaminophtalide, 3,3-bis-(1,2-diméthylindole-3-yl)-6-diméthylaminophtalide, 3,3-bis-(9-éthylcarbazole-3-yl)-5-diméthylaminophtalide, 3,3-bis(2-phénylindole-3-yl)-5-diméthylaminophtalide, 3-p-diméthylaminophényl-3-(1-méthylpyrrole-2-yl)-6-diméthylaminophtalide, éther benzylique de 4,4'-bis-diméthylaminobenshydrine, N-halogénophényl- leuco-auramine, N-2,4,5-trichlorophényl-leuco-auramine, rhodamine-B-anilinolactame, rhodamine-(p-nitro-anilino) lactame, rhodamine-(p-chloranilino) lactame, 7-diméthylamino-2-méthoxyfluorane, 7-diéthylamino-2-méthoxyfluorane, 7-diéthylamino-3-méthoxyfluorane, 7-diéthylamino-3-chlorofluorane, 7-diéthylamino-3-chloro-2-méthylfluorane, 7-diéthylamino-2, 3-diméthylfluorane, 7-diéthylamino-(3-acétyl- méthylamino) fluorane, 7-diéthylamino-(3-méthylamino) fluorane, 3,7-diéthylaminofluorane, 7-diéthylamino-3-(dibenzylamino) fluorane, 7-diéthylamino-3-(méthylbenzylamino) fluorane, 7-diéthylamino-3-(chlo- réthylméthyl-amino) fluorane, 7-diéthylamino-3-(diéthylamino) fluorane, 2-phénylamino-3-méthyl-6-(N-éthyl-N-p-toluyl) amino-fluorane, bleu de benzoyl-leucométhylène, bleu de p-nitrobenzyl-leucométhylène, 3-méthyl-spiro-dinaphtopyrane, 3-éthyl-spiro-dinaphtopyrane, 3,3'-dichloro-spiro-dinaphtopyrane, 3-ben- zyl-spiro-dinaphtopyrane, 3-méthyl-naphto-(3-méthoxybenzo)-spiro-pyrane et 3-propyl-spiro-dibenzopy- rane. Les substances chromogènes incolores mentionnées ci-dessus peuvent être utilisées individuellement ou en mélange.

As color generators, the following compounds are mentioned as non-limiting examples:

• 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (CVL), 3,3-bis- (p-dimethylaminophenyl) phthalide, 3- (p · dimethylaminophenyl) -3- (1,2-dimethylindole-3- yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindole-3-yl) phthalide, 3,3-bis- (1,2-dimethylindole-3-yl) -5-dimethylaminophthalide, 3.3 -bis- (1,2-dimethylindole-3-yl) -6-dimethylaminophthalide, 3,3-bis- (9-ethylcarbazole-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindole-3 -yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrole-2-yl) -6-dimethylaminophthalide, 4,4'-bis-dimethylaminobenshydrin benzyl ether, N-halophenyl-leuco-auramine, N-2,4,5-trichlorophenyl-leuco-auramine, rhodamine-B-anilinolactam, rhodamine- (p-nitro-anilino) lactam, rhodamine- (p-chloranilino) lactam, 7-dimethylamino-2-methoxyfluorane, 7- diethylamino-2-methoxyfluorane, 7-diethylamino-3-methoxyfluorane, 7-diethylamino-3-chlorofluorane, 7-diethylamino-3-chloro-2-methylfluorane, 7-diethylamino-2, 3-dimethylfluorane, 7-diethylamino- (3 -In this yl-methylamino) fluorane, 7-diethylamino- (3-methylamino) fluorane, 3,7-diethylaminofluorane, 7-diethylamino-3- (dibenzylamino) fluorane, 7-diethylamino-3- (methylbenzylamino) fluorane, 7-diethylamino-3 - (chloro-methylethylamino) fluorane, 7-diethylamino-3- (diethylamino) fluorane, 2-phenylamino-3-methyl-6- (N-ethyl-Np-toluyl) amino-fluorane, benzoyl-leucomethylene blue, p-nitrobenzyl-leucomethylene blue, 3-methyl-spiro-dinaphtopyran, 3-ethyl-spiro-dinaphtopyrane, 3,3'-dichloro-spiro-dinaphtopyrane, 3-ben-zyl-spiro-dinaphtopyrane, 3-methyl-naphto - (3-methoxybenzo) -spiro-pyrane and 3-propyl-spiro-dibenzopyranane. The colorless chromogenic substances mentioned above can be used individually or as a mixture.

• - un développeur de couleur, caractéristique de l'invention, appartenant à la famille des dérivés de la saccharine ;
  
  ou de leurs sels :
  
  (avec Y = X moins hydrogène dans le cas où X :0 H) tels que définis précédemment.

The saccharin derivatives used according to the invention make it possible to optimally develop all the known color generators. This development is optimal given the color generator used. However, a certain number of qualities of the trace formed: color, stability, intensity ... depend mainly on the nature of the color generator and, in particular, on the chemical structure of the family to which it belongs. In our case, the color developer of the saccharin family strengthens some of these qualities: intensity, stability to light, to humidity, but does not radically modify them. Thus, for example, a color generator leading, by the action of a conventional color developer to a dye not very stable to light, will see, by the use of saccharin derivatives, its light fastness a little improved, but it will not become excellent.

• - a color developer, characteristic of the invention, belonging to the family of saccharin derivatives;
  
  or their salts:
  
  (with Y = X minus hydrogen in the case where X: 0 H) as defined above.

• - un liant polymérique dont le principal rôle est d'assurer la cohésion de l'ensemble de l'émulsion, ainsi que son accrochage sur le support. Il peut intervenir également par ses caractéristiques propres sur le ramolissement de la couche. Ces liants sont, soit solubles dans l'eau (le générateur de couleur et le développeur étant, la plupart du temps, insolubles ou très faiblement solubles dans l'eau), dans ce cas, on peut opérer en une couche, soit solubles dans des solvants organiques, dans ce cas, il vaut mieux opérer en deux couches quand le solvant utilisé solubilise le générateur de couleur ou le développeur pour éviter toute réaction prématurée entre ces deux composés. Le générateur de couleur et le développeur sont alors placés dans des couches différentes. Ces liants peuvent être choisis dans les familles suivantes : polymères ou latex acryliques, vinyliques, cellulosiques, styréniques, halogénés, maléiques... Comme exemples non limitatifs non pouvons citer : l'amidon, l'alcool polyvinylique, l'hydroxyéthyl cellulose, la méthyl cellulose, la carboxy-méthyl cellulose, la gélatine, la caséine, la gomme arabique, des sels de copolymères de styrène et d'anhydride maléique, une émulsion d'un copolymère de styrène et de butadiène, une émulsion d'un copolymère d'acétate de vinyle et d'anhydride maléique, un copolymère de chlorure de vinylidène...
• - des cires ou composés à bas point de fusion qui servent à ajuster la température de réaction du milieu à une valeur désirée, à empêcher l'adhésion à la tête chauffante, à éviter la salissure par friction, par exemple cires paraffiniques, cires polyoléfiniques, amides gras et leurs dérivés de méthylol, acides gras supérieurs et leurs sels métalliques, les produits de condensation d'un acide gras supérieur et d'un amine, des esters de polyalcools et d'acides gras supérieurs, des alcools supérieurs...
• - une charge pigmentaire destinée à donner une meilleure consistance à la composition de couchage, à améliorer la blancheur du fond, à réduire les problèmes de poissage de la couche et les phénomènes d'encrassement et d'usure des appareils utilisant ces émulsions, par exemple : CaC0₃, kaolin, talc, amidon, TiO₂, ZnO, MgC0₃, Al(OH)₃, argile calcinée, pigments organiques comme des polymérisats urée-formaldéhyde (par exemple « Pergopak" de CIBA-GEIGY), silice colloïdale ou précipitée, silicoaluminates divers...
• - différents adjuvants couramment utilisés pour la préparation et le couchage des émulsions : dispersants, azurants, tensio-actifs, anti-mousse, plastifiants, antioxydants, anti UV, agents tamponnant le pH du milieu et stabilisant la composition comme NaHCO₃ ou NH₄HCO₃. Le choix et la nature de chacun de ces produits étant aisément effectués par un homme de l'art.

These compositions also contain all the species necessary for the formation of a good quality layer on the support.

• - A polymeric binder whose main role is to ensure the cohesion of the entire emulsion, as well as its attachment to the support. It can also intervene by its own characteristics on the softening of the layer. These binders are either soluble in water (the color generator and the developer being, most of the time, insoluble or very slightly soluble in water), in this case, one can operate in a layer, or soluble in organic solvents, in this case, it is better to operate in two layers when the solvent used dissolves the color generator or the developer to avoid any premature reaction between these two compounds. The color generator and the developer are then placed in different layers. These binders can be chosen from the following families: acrylic, vinyl, cellulosic, styrenic, halogenated, maleic polymers or latexes. As nonlimiting examples, we cannot cite: starch, polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxy-methyl cellulose, gelatin, casein, gum arabic, salts of copolymers of styrene and maleic anhydride, an emulsion of a copolymer of styrene and butadiene, an emulsion of a copolymer of vinyl acetate and maleic anhydride, a copolymer of vinylidene chloride ...
• - waxes or compounds with a low melting point which are used to adjust the reaction temperature of the medium to a desired value, to prevent adhesion to the heating head, to avoid soiling by friction, for example paraffinic waxes, polyolefinic waxes, fatty amides and their methylol derivatives, higher fatty acids and their metal salts, the condensation products of a higher fatty acid and an amine, esters of polyalcohols and higher fatty acids, higher alcohols ...
• - a pigment filler intended to give a better consistency to the coating composition, to improve the whiteness of the background, to reduce the problems of sticking of the layer and the phenomena of fouling and wear of the devices using these emulsions, for example : CaC0 ₃ , kaolin, talc, starch, TiO ₂ , ZnO, MgC0 ₃ , Al (OH) ₃ , calcined clay, organic pigments like urea-formaldehyde polymers (for example "Pergopak" from CIBA-GEIGY), colloidal silica or precipitated, various silicoaluminates ...
• - various adjuvants commonly used for the preparation and coating of emulsions: dispersants, brighteners, surfactants, anti-foam, plasticizers, antioxidants, anti UV, agents buffering the pH of the medium and stabilizing the composition such as NaHCO ₃ or NH ₄ HCO ₃ . The choice and the nature of each of these products being easily made by a person skilled in the art.

All these different constituents are ground, emulsified or dissolved in the medium and coated in one or more layers on a paper or other support (plastic for example). Preferably, the color generator and the color developer are ground separately, so as to avoid any premature reaction. The two dispersions being mixed before coating in the case of a coating in one layer. The nature, the grammage of the support, as well as the number and the thickness of the layers and their method of coating depend on the intended use, as well as on the desired effect, and are easily determined by a person skilled in the art. .

The various examples given below are for illustration and are in no way limiting.

Example 1

The following compositions are ground separately:

qui est couché à raison de 6,5 g/m² sec sur un papier de 50 g/m².Then the following mixture is prepared:

which is coated at a rate of 6.5 g / m ² sec on a paper of 50 g / m ² .

After drying and calendering, the paper is used on a XEROX 485 fax machine. We obtain a good quality of restitution of the original, with black densities from 0.90 to 1.00. These densities are measured by reflection with a GAM RD 144 densitometer (WRATTEN filter No. 106).

Example 2

et:

Puis, on prépare le mélange suivant :

qui est couché à raison de 6,5 g/m² sec environ sur un papier de 55 g/m². Après séchage et calandrage, ce papier est utilisé sur une machine à calculer de bureau à imprimante thermique OLIVETTI LOGOS n° 7. La trace bleue a une densité de 1,0 (densitomètre GAM RD 144, filtre WRATTEN n° 106). Le seuil de réaction du papier est très marqué et se situe à 85 °C environ.The following compositions are ground separately:

and:

Then, the following mixture is prepared:

which is coated at a rate of approximately 6.5 g / m ² sec on a paper of 55 g / m ² . After drying and calendering, this paper is used on an office calculating machine with thermal printer OLIVETTI LOGOS n ° 7. The blue trace has a density of 1.0 (densitometer GAM RD 144, WRATTEN filter n ° 106). The paper reaction threshold is very marked and is around 85 ° C.

Example 3

The following composition is ground in a homogeneous manner:

This layer is deposited at a rate of 4 g / m ² sec on a 55 g / m ² paper support and then, after drying, the following composition, previously ground, is deposited over it, at a rate of approximately 3 g / m ² sec. :

After drying and possibly calendering, this paper is used in a device for recording EKGs of the "cardiopan 571" type from PHILIPS and makes it possible to obtain a very finely resolved black line, whatever the speed of the paper 50, 25 or 10 mm / s. The density of the trace is 1.15 (GAM RD 144 densitometer, WRATTEN filter No. 106).

Example 4

The following composition is ground in a homogeneous manner:

This layer is deposited at a rate of 4 g / m ² on a Terphane polyester support from RHONE POULENC 100 μm thick. After drying, the following composition, deposited beforehand, is deposited over, at a rate of approximately 3 g / m ² sec:

After drying and possibly calendering, this thermoreactive film is tested on a “Thermotest device from the company SETARAM (LYON). We obtain red traces of density 1.4 (GAM RD 144 densitometer, green WRATTEN filter n ° 581). The reaction threshold for this paper is well marked and is around 85 ° C.

Example 5

The following composition is dispersed in a homogeneous manner, after having ground the color-former and the saccharin separately, the other constituents being distributed equitably between the two grindings:

This layer is deposited on a paper of 50 g / m ² at a rate of 6.5 g / m ^2. After drying and calendering, this paper is used on a thermal printer ANDERSON-JACOBSON AJ 630 (10 characters per inch and 6 lines per inch) and allows us to obtain blue records with a density of 1.0 to 0.85, depending on the speed selected: 10, 15 or 30 characters per second (densitometer GAM RD 144, WRATTEN filter n ° 106) .

The reaction threshold is very marked and is around 95 ° C.

Example 6

This example is identical to Example 1, except that the saccharin ... 97 g is replaced in the grinding (1) by:

Bromo-1 'saccharin

The results obtained under identical conditions with such a formulation are comparable to those obtained in Example 1.

Example 7

The following composition is ground in a homogeneous manner:

This composition is deposited at a rate of 4 g / m ² sec on a 55 g / m ² paper support. Then, after drying, the following composition, previously ground, is deposited over, at a rate of approximately 3 g / m ² sec:

After drying and calendering, this paper is used in an apparatus for recording electrocardiograms of the "Cardiopan 571" type from PHILIPS and makes it possible to obtain a dark brown trace very finely resolved, whatever the speed of movement of the paper: 50, 25 or 10 mm / s. The density of the trace is 0.90 (densitometer GAM RD 144, WRATTEN filter n ° 106).

Example 8

Puis on prépare le mélange suivant :

qui est couché, à raison de 6,5 g/m² sec environ, sur un papier de 50 g/m^2. Après séchage et calandrage, ce papier est utilisé sur une machine à calculer de bureau à imprimante thermique HEWLETT-PACKARD 97. La trace noire légèrement rougeâtre a une densité de 1,15 (densitomètre GAM RD 144, filtre WRATTEN n° 106).The following compositions are ground separately:

Then the following mixture is prepared:

which is coated, at a rate of approximately 6.5 g / m ² sec, on a paper of 50 g / m ^2. After drying and calendering, this paper is used on a desktop calculating machine with thermal printer HEWLETT-PACKARD 97 The slightly reddish black trace has a density of 1.15 (GAM RD 144 densitometer, WRATTEN filter n ° 106).

These few examples are not limiting but are intended to illustrate the description of the invention. It goes without saying that many other examples could have been described by changing the saccharin derivative, the color former, the number and the arrangement of the layers, without thereby departing from the scope of the invention.

We must also emphasize that all of these compositions have good light and storage stability under ambient temperature and humidity conditions, as well as under more severe conditions, at high humidity for example.

Claims (11)

1. Thermographic composition characterized in that it contains an organic color generator which is not a salt, and at least one compound of formula :

in which

R₁, R₂, R₃, R₄, are identical or different, and are H, alkyl, N0₂, halogen, aryl, NH₂, OH, COOH, S0₃H, NZ₁Z₂, COOZ3, OZ4 (Z₁, Z2, Z3, Z₄ = alkyl or aryl)

X is H or a group having a labile H capable of forming a stable anion by losing a proton H⁺, or their salts of formulae :

(with Y = X less hydrogen in the case where X ≠ H)
in which R₁, R₂, R₃, R₄ are as defined above and M⁺ is a metallic cation.

2. Thermographic composition according to claim 1, characterized in that X = H, -OH, (CH₂)_m -OH with 1 < m < 10 or

3. Thermographic composition according to claim 1 or 2, characterized in that X = H.

4. Thermographic composition according to one of claims 1 to 3, characterized in that R₁, R₂, R₃, R₄, are selected from : H, lower alkyl, halogen, nitro, amino.

5. Thermographic composition according to one of claims 1 to 4, characterized in that M is selected from : Cu, Cd, Co, Fe(II), Ni, Mn et Zn.

6. Thermographic composition according to one of claims 1 to 5, characterized in that they are selected from :

saccharin,

1'-bromo saccharin,

1'-nitro saccharin,

1'-amino saccharin,

saccharin 5'-carboxylic acid,

meta or para disaccharin,

1-methylol saccharin.

7. Thermographic composition according to claim 1, characterized in that the color generator is selected from lactones of triphenyl methane dyes, fluoranes, phthalides, triaryl methane leuco-dyes, spiropyrannes, chromenes, chromanes, leuco-dyes of phenoxazine or substituted phenothiazine.

8. Thermographic composition according to claim 1, characterized in that it further contains a polymeric binder and/or waxes or compounds at its melting point, and/or a pigment filler, and/or other conventional additives.

9. Composition according to the preceding claims, characterized in that the color generator/developer pairs are the following :

- Pergascript IBR black (black color former)/saccharin,

- Lactone crystal violet/saccharin-zinc acetate,

- I-G-B pergascript red (red color former)/saccharin,

- Lactone crystal violet/saccharin,

- IBR pergascript black (black color former)/1'-bromo saccharin, /Methylol saccharin,

- Product T

- IBR pergascript black (black color former)/saccharin-manganese nitrate.

10. Thermographic system, characterized in that it contains an external layer of a composition according to one of claims 1 to 9.

11. Thermographic system according to claim 10, characterized in that it contains in this order :

- a paper support,

- a layer of a composition according to one of claims 1 to 9, in the form of two separate layers, the first containing the developer and the upper layer containing the generator.