DE102006056003A1 - Heat-sensitive recording material with authentication feature - Google Patents

Abstract

The proposal is for a heat-sensitive recording material comprising a substrate and a thermosensitive recording layer containing color formers and color acceptors, characterized in that the recording material has as an authentication feature an additional layer of non-colored, water-soluble and / or alcohol-soluble solid particles, the solid particles being in an aqueous Solution are strongly alkaline reactive.

Description

The The present invention relates to a heat-sensitive recording material with authentication feature comprising a substrate, optionally one on the substrate applied pigmented intermediate layer as well a thermosensitive color former containing color acceptors Recording layer.

recording materials of this kind determine daily life in society and within working life. For the use of recording materials, their authorized use generally by a specific marking of for material to be proved for this purpose has been the past already different solutions authentizitätsnachweisender Security features proposed.

• – echten Wasserzeichen, die durch Verdrängung (so genannte Licht-Wasserzeichen) oder durch Anreicherung (so genannte Schatten-Wasserzeichen) der Fasermasse beispielsweise unter Verwendung eines Egoutteurs in der Siebpartie einer Papiermaschine hergestellt werden,
• – halbechten, so genannten Moletten-Wasserzeichen, die durch die Prägung des noch nassen Papiers in der Pressenpartie einer Papiermaschine erzeugt werden, wobei die Ausbildung solcher wie auch echter Wasserzeichen in den Substraten wärmeempfindlicher Aufzeichnungsmaterialien unter anderem in der EP 0 611 664 B1 beschrieben wird,
• – und schließlich unechten Wasserzeichen, wobei letztere gewöhnlich außerhalb der Papiermaschine entweder durch das Prägen oder durch das Bedrucken des fertig gestellten Papiers mit einem farblosen, gerne auch unter UV-Licht fluoreszierenden Lack erstellt werden, wie es unter anderem in der EP-A-0 844 097 beschrieben wird. Im zuletzt beschriebenen Beispiel für ein unechtes Wasserzeichen wird selbstverständlich keine unterschiedliche Papierdicke mehr durch die Zeichnung im Papier hervorgerufen.

Authenticates for documents in the form of passive examinations, for example, are made possible by the greatest popularity of pleasing watermarks, ie drawings in the paper, which are usually caused by different paper thickness. It is differentiated between

• Genuine watermarks produced by displacement (so-called light watermarks) or by enrichment (so-called shadow watermarks) of the pulp, for example using a dandy cutter in the wire section of a paper machine,
• Semi-fast, so-called Moletten watermarks, which are produced by the embossing of the still wet paper in the press section of a paper machine, the formation of such as well as genuine watermarks in the substrates of heat-sensitive recording materials, inter alia in the EP 0 611 664 B1 is described
• - And finally spurious watermarks, the latter are usually created outside the paper machine either by embossing or by printing the finished paper with a colorless, even under UV light fluorescent varnish, as described inter alia in the EP-A-0 844 097 is described. Of course, in the example of a fake watermark described last, no different paper thickness is caused by the drawing in the paper.

outgoing from the known spurious watermarks it was considered a disadvantage for certain Applications recognized that this authenticity-proofing security feature is recognizable at any time. The present invention was then the Task, an authentication feature for a recording material to disposal to ask that not at any time and immediately, but only from a desired one Timing in which the authenticity of the recording material carrying the feature should be demonstrated, should be visible.

The given task is solved by a heat sensitive Recording material having an authentication feature, comprising a substrate and a color former and Farbakzeptoren containing thermosensitive Recording layer, wherein color formers and color acceptors Action of heat color forming react with each other. The proposed recording material has as an authentication feature an additional layer with non-colored, soluble in water and / or in alcohol Solid particles, wherein the solid particles in an aqueous solution strongly alkaline are reactive.

in the Meaning of the present invention does not mean colored in context with the solid particles that they appear white or whitish in the dry state, while a water or alcohol solution is transparent with these solid particles.

In a watery one solution the solid particles are strongly alkaline reactive, which means that such a watery solution a pH above 9.0, preferably over 10.0 and even better over 11.0.

• – eines Musters,
• – von Logos bzw. von fortlaufenden Nummerierungen
• – eines diagonalen Streifengittermusters

und/oder in Formen, wie sie aus zyklisch wiederkehrenden Wasserzeichen bekannt sind, aufgebracht. Es ist möglich, die wärmeempfindliche Aufzeichnungsschicht mit der zusätzlichen Schicht zu unterlegen, so dass sie zwischen Substrat und Aufzeichnungsschicht bzw., sofern im Rahmen einer bevorzugten Ausführungsform gegeben, zwischen pigmentierter Zwischenschicht und Aufzeichnungsschicht gelegen ist. Als besonders bevorzugt gilt eine Ausführungsvariante, bei der die zusätzliche Schicht mit den nicht farbigen, in Wasser und/oder in Alkohol löslichen Feststoffpartikeln direkt auf die wärmeempfindliche Aufzeichnungsschicht aufgebracht ist.The additional layer is preferably in the form

• - a pattern,
• - of logos or consecutive numbers
• - a diagonal stripe grid pattern

and / or in forms known from cyclically recurring watermarks. It is possible to underlay the heat-sensitive recording layer with the additional layer so as to be located between the substrate and the recording layer or, if given in a preferred embodiment, between the pigmented intermediate layer and the recording layer. Particularly preferred is a variant in which the additional layer with the non-colored, water-soluble and / or alcohol-soluble solid particles is applied directly to the heat-sensitive recording layer.

When possible Methods for applying the additional Layer on the heat-sensitive Recording layer have stamping as well as generally all analog Printing method proven especially offset printing, without to be limited in any way. Also, the application of the additional Layer suitable by ink jet printing. However, heat-sensitive ones apply Recording materials with on the heat-sensitive recording layer stamped or printed additional layer as particularly preferred.

One good example for the solid particles of the additional Layer is guanidine carbonate. A 15% aqueous guanidine carbonate solution with a pH of 11.5, in a preferred embodiment with an addition of, based on the aqueous guanidine carbonate solution, 5 % Ethanol, leaves as an authentication feature outstanding on the heat-sensitive Apply recording layer, wherein a thus formed Layer also absorbs quickly and dries.

guanidine carbonate is excellently capable of the color-forming reaction of color former and color acceptors when heat is applied by blocking the formation of a highly alkaline environment, wherein this blocking essential to the invention sharply limited and in the form of the intended design. A disadvantage of guanidine carbonate is its low stability, which is indicated by a gray to yellowish discoloration. Will the recording material of the invention only for a comparatively short period of a few hours used to few days, guanidine carbonate is due to lower Very good to use procurement prices.

Another example of the solid particles of the additional layer is arginine satisfying the following formula (1):

arginine does not have the disadvantages of low stability and is at the same time capable of very sharp blockages of the color-forming reaction of color former and Farbakzeptoren when heat to ensure. For this purpose, a 3 to 5% strength aqueous arginine solution is preferably used for Application to the heat-sensitive Recording layer used. In this solution can additionally Wetting agents, in particular olefin, and, based on the arginine solution, too 1 to 3.5%, for example 12% polyvinylalcohol solution and be added to 4 to 8% ethanol.

One another example of the solid particles of the additional Layer is lysine.

The heat-sensitive according to the invention Recording material can as a color former at least one substance included, selected from the group of known from the prior art phthalide, xanthene, Fluoran, triarylmethane, diphenylmethane, fluorene, oxazine, thiazine or spiropyran compounds, where xanthene compounds are considered preferred.

typical Compounds of this type are, for example:

Xanthene compounds:

Rhodamine B anilinolactam, Rhodamine-B-p-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7-phenylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-diethylamino-7- (2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N-ethyl, N-tolyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilino-fluoran, 3- (N-ethyl, N-tolyl) amino-6-methyl-7-phenylethyl fluoran, 3-diethylamino-7- (4-nitroanilino) fluoran, 3- (N-methyl, N-propyl) amino-6-methyl-7-anilinofluoran, 3- (N -methyl, N-cyclohexyl) amino-6-methyl-7-anilino-fluoran, 3- (N-ethyl, N-tetrahydrofuryl) amino-6-methyl-7-anilinofluoran, Etc.

Triarylmethane compounds:

3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (Crystal Violet Lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindole-3-yl) phthalide, 3- (p-Dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindol-3-yl) phthalide, 3,3-bis (1,2-dimethylindole-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindol-3-yl) -6-dimethylamino-phthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3 (1-methylpyrrol-2-yl) -6-dimethylaminophthalide, Etc.

Diphenylmethane compounds:

4,4'-bis-dimethylaminophenyl-benzhydryl benzyl, N-halophenylleucoauramines, N-2,4,5-trichlorophenyl leucoauramine, and the same.

Thiazine compounds:

benzoylleucomethylene, p-nitrobenzoylleucomethylene blue, etc.

Spiropyran compounds:

3-methyl-spiro-dinaphthopyran, 3-ethylspiro-dinaphthopyran, 3,3-dichlorospiro-dinaphthopyran, 3-benzyl-spiro-dinaphthopyran, 3-methyl-naphtho- (3-methoxy-benzo) spiropyran, 3-propyl-spiro-benzopyran, etc.

Furthermore, the recording layer can also contain, for example, one or more of the following near infrared absorbing compounds:
3,6-Bis (dimethylamino) fluorene-9-spiro-3 '- (6'-dimethylaminophthalide), 3-diethylamino-6-dimethylaminofluorene-9-spiro-3' - (6'-dimethylaminophthalide), 3.6- Bis (diethylamino) -fluorene-9-spiro-3 '- (6'-dimethylaminophthalide), 3-dibutylamino-6-dimethylaminofluorene-9-spiro-3' - (6'-dimethylaminophthalide), 3-dibutylamino-6-diethylaminofluorene -9-spiro-3 '- (6'-dimethylaminophthalide), 3,6-bis (dimethylamino) fluorene-9-spiro-3' - (6'-diethylamino-phthalide), 3-diethylamino-6-dimethylaminofluorene-9 -spiro-3 '- (6'-diethylaminophthalide), 3-dibutylamino-6-dimethylaminofluorene-9-spiro-3' - (6'-diethylaminophthalide), 3,6-bis (diethylamino) fluorene-9-spiro 3 '- (6'-diethylaminophthalide), 3,6-bis (dimethylamino) fluorene-9-spiro-3' - (6'-dibutylaminophthalide), 3-dibutylamino-6-di-ethylaminofluorene-9-spiro-3 '- (6'-diethylaminophthalide), 3-diethylamino-6-dimethylaminofluorene-9-spiro-3' - (6'-dibutylaminophthalide), 3,3-bis [2- (4-dimethylamino-phenyl) -2- ( 4-methoxyphenyl) -ethenyl] -4,5,6,7-tetrachlorophthalide, etc.

When Very particularly preferred color formers in the heat-sensitive recording layer apply in the context of the present invention, such substances selected from the list comprising: 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane and 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluoran.

auf.In principle, the recording layer of the heat-sensitive recording material according to the invention may contain all color acceptors, in particular organic color acceptors, which are suitable in particular for the cited and, in particular, the preferred color formers. Preferably, the heat-sensitive recording layer has, as a color acceptor, N- (p-toluenesulphonyl) -N'-3- (p-toluenesulphonyl-oxy-phenyl) -urea according to the formula (2)

on.

The recording layer of the heat-sensitive recording material of the present invention may also preferably be sensitizers having a melting point, preferably from 60 ° C to 180 ° C, more preferably having a melting point of from 80 ° C to 90 ° C, to increase the thermal responsiveness 140 ° C, included. Such sensitizers are, for example: benzyl p-benzyloxybenzoate, stearamide, N-methylol stearamide, p-benzylbiphenyl, 1,2-di (phenoxy) ethane, 1,2-di (m-methylphenoxy) ethane, m-terphenyl, Dibenzyl oxalate, benzyl naphthyl ether, diphenyl sulfone, etc., with benzyl naphthyl ether, diphenyl sulfone, 1,2-di (m-methylphenoxy) ethane and 1,2-di (phenoxy) ethane being preferred.

suitable Binder for incorporation into the heat-sensitive recording layer are, for example, water-soluble Binders such as starch, Hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, Casein, polyvinyl alcohols, modified polyvinyl alcohols, sodium polyacrylates, Acrylamide-acrylate copolymers, Acrylamide-acrylate-methacrylate terpolymers, alkali metal salts of styrene-maleic anhydride copolymers or ethylene-maleic anhydride copolymers, etc., which can be used alone or in combination with each other; also water Latex binders such as styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, Methyl acrylate butadiene copolymers, etc. offer themselves as binders for integration into the heat-sensitive Recording layer on. For the purposes of the present invention are polyvinyl alcohol alone and / or in conjunction with acrylate copolymers and / or in Compound with methylcellulose as particularly preferred binder, together, based on the total weight (atro) of the recording layer, in a range from 12 to 25% by weight (atro), preferably in one Range of 18 to 22 wt .-% (atro) in the heat-sensitive recording layer are involved.

to Avoid sticking to a thermal head and avoid excessive wear the thermal head can be heat sensitive Recording layer further contain lubricants and release agents like metal salts higher fatty acids, for example, zinc stearate, calcium stearate, etc .; Waxes, for example Paraffin, oxidized paraffin, polyethylene, polyethylene oxide, stearamides, Kastorwachs, etc. Further components of the recording layer are, for example, pigments, preferably inorganic pigments such as, for example Aluminum (hydr) oxide, silica and calcium carbonate, in particular calcium carbonate, the preferably in an amount of 10 to 18 wt .-%, based on the total weight the recording layer, incorporated in the recording layer should be considered as preferred.

Roller coater, knife coater, curtain coater or air brush are particularly suitable as coating apparatus for applying the heat-sensitive recording layer. According to a preferred embodiment, the coating composition used to form the recording layer is aqueous. The subsequent drying of the coating composition is usually done by a method in which heat is supplied, as is done by hot-air floating dryer or contact dryer. Proven is also a combination of the listed dry processes. The basis weight of the heat-sensitive recording layer is preferably from 2 to 6 g / m ^2, and more preferably from 2.3 to 5.8 g / m ² .

Between the recording layer and the substrate of the heat-sensitive recording material according to the invention, a pigmented intermediate layer is expediently arranged. If the intermediate layer is applied in a preferred embodiment with leveling coating devices, such as, for example, roller coater, doctor blade or doctor blade coaters, the intermediate layer can also make a positive contribution to equalization of the substrate surface, thus increasing the amount of coating material necessarily to be applied to the substrate heat-sensitive recording layer reduced. For the basis weight of the intermediate layer, a preferred range between 5 and 20 g / m ² and even better between 7 and 11 g / m ^{2 has} proven.

Become in the intermediate layer located between the recording layer and the substrate inorganic oil-absorbing Pigments involved these pigments liquefied by the heat of the thermal head Wax components of heat-sensitive Recording layer in the print image training and favor thus a still safer and faster functioning of the heat-induced Recording why such an embodiment is considered preferable.

It is particularly advantageous if the pigments of the intermediate layer has an oil absorption of at least 80 ^cm3 / 100 g, and more preferably 100 ^cm3 / 100 g, determined according to the Japanese standard JIS K 5101, is having. Calcined kaolin has proven particularly useful due to its large absorption reservoir in the cavities. However, the following inorganic pigments are also very well suited as constituents of the intermediate layer: silicon oxide, bentonite, calcium carbonate and aluminum oxide and, in particular, boehmite here. Also mixtures of several different types of inorganic pigments are conceivable.

Experiments have shown that the incorporation of organic pigments into the pigmented intermediate layer can also be very advantageous, which is justified by the fact that such organic pigments are used in a special measure a high heat reflectivity of the intermediate layer are beneficial. The arranged in an intermediate layer of a heat-sensitive recording material organic, so-called hollow body pigments have in their interior air, which is a good heat insulator. The intermediate layer thus optimized as the heat reflection layer increases the response of the recording layer to heat, which remarkably increases the resolving power of the thermosensitive recording material and further raises the printing speed in the thermal printer.

The ratio between organic and inorganic pigment is a compromise the effects caused by the two types of pigments, the particular solved advantageous is when the pigment mixture to 5 to 30 wt .-% or better to 8 to 20 wt .-% of organic and 95 to 70 wt .-% or better to 92 to 80 wt .-% consists of inorganic pigment. pigment mixtures from different organic pigments are conceivable.

Next the inorganic and optionally also organic pigments contains the pigmented intermediate layer preferably at least one binder based on a synthetic polymer, for example, styrene-butadiene latex particularly good Delivers results. The use of a synthetic binder with admixture of at least one natural polymer, such as especially prefers strength, provides a particularly suitable embodiment In the context of experiments with inorganic pigments was further found that having a binder to pigment ratio within the pigmented intermediate layer between 3: 7 and 1: 9, respectively based on wt .-%, a particularly suitable embodiment is present.

Especially, if the extra Layer with the non-colored, water-soluble and / or alcohol-soluble Solid particles on the heat-sensitive Recording layer is stamped or printed, has the proposed recording material preferably a protective layer on, even for any indication of a possible authentication feature or to prevent its form.

To form such a protective layer, for example, coating colors, as they are used in the EP-B-0 909 242 and secondly in the EP-B-1 333 991 be proposed. In both cases, the protective layer combines high environmental resistance with recyclability and good printability in the wet offset process. The protective layers mentioned are both relatively cheap to produce and apply in one layer.

When inorganic pigments are for the protective layer is natural or precipitated Calcium carbonate, kaolin or titanium oxide possible As a crosslinking agent for the Protective layer are especially cyclic urea, methylolurea, Polyamide-epichlorohydrin resin, ammonium zirconium carbonate.

It is preferred to apply the protective layer with a basis weight in a range of 1.5 to 6 g / m ² and especially between 1.8 and 4 g / m ² , in particular roller coater, doctor blade or (roll) doctor blade coater , but also offer curtain coaters and airbrush application units as coating units for application of the protective layer.

In a special size applies the printing technology application of a protective layer as preferred. Technical processing and particularly suitable in terms of their technological properties are such protective layers which are curable by means of actinic radiation. By the term "actinic Radiation "are UV or ionizing radiations, such as electron beams, to understand.

Although not limited to paper as a substrate, paper and especially a non-surface treated base paper preferred in a range for the basis weight between 45 and 130 g / m ^2, the substrate, which is also in the market with regard to the good environmental performance because of Good recycling ability has prevailed and is preferred for the purposes of the invention. A non-surface treated base paper is to be understood as meaning a base paper which has not been treated in a size press or in a coating device. For the purposes of the present invention, in particular a non-surface-treated, sized in the mass base paper with an inorganic pigment, in particular calcium carbonate, is considered suitable in the mass. For the invention, films of, for example, polyolefin and polyolefin-coated papers as a substrate are possible to the same extent, without such an embodiment having an exclusive character.

The in the description and in the claims made to areal Mass, by weight (% by weight), are each based on the "atro" weight, i.e., absolute dry parts by weight.

The invention will be further clarified by the following example:
The substrate used on a fourdrinier paper machine made of bleached and ground hardwood and softwood pulps with the addition of, based on the total solids content (atro) of the pulp fed to the paper machine, 0.6 wt .-% (atro) Harzleim as engine sizing and other conventional admixtures a support paper having a basis weight of 53 g / m ^{2 was} produced. On the front side, a calcined kaolin pigment, styrene-butadiene latex as a binder and, in addition to other aids, starch as cobinder-containing intermediate layer having a basis weight of 9 g / m ^{2 is} applied using a doctor blade.

Onto this pigmented intermediate layer, a heat-sensitive recording layer having a basis weight of 5.4 g / m ^{2 is} applied by means of a roller doctor coater. The aqueous coating used for this purpose contains the following components according to the formulation shown in Table 1: TABLE 1 Data in wt .-% (atro), based on the total weight of the heat-sensitive recording layer color formers 3-dibutylamino-6-methyl-7-anilinofluoran (ODB-2) 9 color acceptor N- (p-toluensulphonyl) -N'-3- (p-toluensulphonyl-oxyphenyl) -urea according to formula (2), which is Pergafast ^® 201 (CIBA) 22 sensitizer Benzylnaphthyl ether (BNE) 22 binder Polyvinyl alcohol (PVA) 7 co-binder Acrylate copolymers 12 methylcellulose 2 pigment calcium carbonate 16 90

Further not in percent and based on the total weight in% by weight (atro) specified components of the heat-sensitive The recording layer includes, but is not limited to, dispersants, defoamers, optical Brightener, thickener, waxes and crosslinkers.

After drying the heat-sensitive recording layer and smoothing the recording material, here a value of 150 Bekk sec is measured, applied with the aid of a stamp, the application of an aqueous solution to the heat-sensitive recording layer, wherein for the solution, the following components according to the formulation shown in Table 2 be used: Table 2: In wt .-% (atro), based on the total weight of the aqueous arginine solution Solid particles Arginine according to formula (1) 4 wetting agent Olfin 0.5 binder polyvinyl alcohol 1

Based to 100 parts of the finished arginine solution will eventually 7 parts of ethanol added.

to Identification of the thus formed authentication feature becomes the heat sensitive Recording material for Placed in a drying oven at 120 ° C for 2 min. The heat causes a blackening the heat sensitive Recording layer as a result of the color-forming reaction of color former and Farbakzeptor, but this darkness is sharp-edged where the aqueous arginine solution was previously applied had been.

The experiment shows very clearly that it can convincingly with the proposed invention gen is to provide an authentication feature for a recording material that can not be visualized immediately, but only from a desired date in which the authenticity of the feature-bearing recording material is to be detected. In the case described, this point in time is the formation of the heat-induced blackening of the recording layer, which, of course, can not only be applied nationwide, but also with the aid of a thermal printer according to a printed image. It is equally possible to apply a solvent tincture to the recording layer with the additional layer as an authentication feature in the context of a rapid test, for example with a correspondingly prepared felt-tip pen. In this case, the solvent would cause blackening of the recording layer, but this blackening does not occur in sharp-edged places where the aqueous arginine solution had previously been applied.

Claims (9)

A heat-sensitive recording material having an authentication feature, comprising a substrate and a heat-sensitive recording layer containing a color former and color acceptors, characterized in that the recording material has as an authentication feature an additional layer of non-colored, water-soluble and / or alcohol-soluble solid particles, the solid particles being in an aqueous Solution are strongly alkaline reactive. thermosensitive Recording material according to claim 1, characterized that extra Layer is applied in the form of a pattern. thermosensitive Recording material according to one of the claims 1 and 2, characterized that extra Layer is stamped on the recording layer. thermosensitive Recording material according to one of the claims 1 and 2, characterized that extra Layer is printed on the recording layer. Heat-sensitive recording material according to one of the claims 1 and 4, characterized in that the solid particles form a substance which satisfies the following formula (1):

thermosensitive Recording material according to one of the claims 3 and 4, characterized that the recording material with a recording layer with applied additional layer having protective covering layer. thermosensitive Recording material according to one of the claims 1 to 6, characterized that the heat sensitive Recording layer has a color former, selected from the list comprising: 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6-methyl-7-anilinofluorane and 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluoran. Heat-sensitive recording material according to one of claims 1 to 7, characterized in that the heat-sensitive recording layer as color acceptor N- (p-toluenesulphonyl) -N'-3- (p-toluenesulphonyl-oxy-phenyl) -urea according to the formula (2)

having. thermosensitive Recording material according to one of the claims 1 to 8, characterized that between the substrate and the heat-sensitive recording layer a pigmented intermediate layer is formed.