EP2517888A1 - Heat-sensitive recording material with authentification mark - Google Patents

Abstract

Heat-sensitive recording material comprises; a sheet-like substrate; a heat-sensitive recording layer; at least one intermediate layer located between the substrate and heat-sensitive recording layer; and a proof of authenticity concerns about security feature based on luminescent components, where the luminescent components are introduced as inorganic components in the intermediate layer. An independent claim is included for a process for producing a heat-sensitive recording material comprising forming a sheet-like substrate, preparing a third coating comprising an organic and/or an inorganic pigment, a binder and the proof of authenticity concerns about security feature based on luminescent components, applying the prepared third coating composition for forming a pigmented intermediate layer on the substrate, drying the third coating composition, preparing a first coating composition comprising at least one dye precursor, at least one color acceptor, where the color precursor and the color acceptor are reacted to form a color under the action of heat, applying the prepared first coating composition for forming the heat-sensitive recording layer on the pigmented intermediate layer, drying the first coating composition, and rolling up the sheet-like substrate formed with the pigmented intermediate layer formed with the heat-sensitive recording layer.

Description

The present invention relates to a thermosensitive recording material having at least a sheet-like substrate, a heat-sensitive recording layer, and optionally a protective layer covering the thermosensitive recording layer. In this case, the proposed recording material should contain at least one authentication feature. The invention also aims at a method for producing such a thermosensitive recording material.

Recording materials determine daily life in today's society and especially within today's professional life. Recording materials, in particular with paper as a web-shaped substrate and with at least one heat-sensitive recording layer on at least one of the two sides of the web-shaped substrate are known since the early years chemically reactive recording materials and enjoy an unbroken popularity, which is due, inter alia, that their use, for example Entry, flight and travel tickets for ticket issuers are associated with great benefits. Because the color-forming components are stuck in the recording material itself in the heat-sensitive recording method, the toner and color-cartridge-free printers, which no longer need to be regularly controlled and maintained by anyone, can be set up in large numbers. Thus, this innovative technology has prevailed in particular in public passenger transport, buses and trains as well as in air traffic, but also at stadium and museum funds as well as parking ticket issuers.

For the use of recording materials, the authorized use of which is generally to be demonstrated by a specific marking of the material approved for this purpose, various solutions of authenticity-proofing security features have already been proposed in the past. Practically only two groups of security features have prevailed on the market and among consumers to this day.

On the one hand, recording materials are known which have a watermark as an authenticity-proofing security feature. A watermark is generally understood to mean a drawing in the paper, whereby a distinction is made between genuine watermarks which are produced by displacement (so-called light watermarks) or by enrichment (so-called shadow watermarks). For example, the fiber stock may be produced using a dandy cutter in the wire section of a paper machine, so-called molten watermarks created by embossing still-wet paper in the press section of a paper machine, and finally spurious watermarks, either by printing on the paper finished paper outside the paper machine with a colorless paint or by embossing the finished paper outside the paper machine are created. In addition to the undisputed effect as an authenticity-proofing security feature, genuine watermarks are also so popular because they seem to give the recording material equipped with them a particularly high-quality character.

On the other hand, recording materials are known which, as an authenticity-proofing security feature, usually have fluorescent components under special light. The present invention relates in general terms to recording materials having this type of authenticity-proofing security features.

In contrast to the control of watermarked recording materials, the authenticity-detecting control of recording materials with fluorescent components usually requires a minimum of technical equipment, be it in the form of special light sources, either or alternatively in the form of suitable detectors and display devices. This alleged disadvantage of not everywhere and immediately possible authenticity-proofing control is counteracted by the much more meaningful and much worse to falsify control result for recording materials with fluorescent components.

Basically, recording materials with fluorescent components are known as an authenticity-proofing security feature in a thoroughly complex manner.

For example, the EP 1 233 106 B1 a security feature generally in the form of a component, there referred to as a segment, with linearly polarized photoluminescence before then It. The EP 1 446 528 B1 in a paper or a paper-like structure, thus more precisely in the substrate of a paper to be involved. Just like in the EP 1 348 575 A1 The components known in this way, which are to be used as authenticity-proofing security feature, are aimed at organic basic substances, usually in the form of fibers, which are labeled with organic fluorescent dyes as well. By stretching the thus labeled basic substances arise polarization effects, which are the underlying and / or characteristic components of the solutions proposed in the aforementioned writings.

In a diametrically opposite direction aims a proposal of EP 0 966 504 B1 In which a usable as a proof of authenticity end security feature phosphor based on crystals, which means, it is proposed on the basis of inorganic basic substances. Indications of how the phosphors thus disclosed are to be used, however, are largely absent from this document.

A proposal of DE 198 60 093 A1 Correspondingly, a value document, such as a banknote, identity card or the like, is known with a combination of at least two authenticity-proofing security features, in which the first security feature is in the form of an inorganic luminescent substance and the second security feature is in the form of an organic luminescent substance.

In principle, the components known in this way, which usually fluoresce under special light, have proven to be authenticity-proofing security features in numerous applications, but their incorporation into coatings of heat-sensitive recording materials on the side with the heat-sensitive recording layer itself is not known on the one hand from the prior art, on the other hand also results from the great technical difficulties associated with the incorporation of such components in the said coatings of the heat-sensitive recording materials and to which the inventors were faced in many attempts underlying the invention.

Thus, it is an object of the present invention to provide the public with a heat-sensitive recording material which has at least one characteristic authenticity-detecting security feature based on luminescent components. This authenticity-detecting security feature based on luminescent components is intended to be incorporated on the side of a web-shaped substrate on which the heat-sensitive recording layer itself is formed, so that the security feature of the recording material proposed here as part of its intended use as a public transport ticket, on buses and as well as in air traffic, but also as a ticket to stadium and museum cash registers is particularly easy and quickly detectable and - as evidence of his Authenticity - is directly related to the induced by the action of heat typeface.

• □ ein bahnförmiges Substrat,
• □ eine wärmeempfindliche Aufzeichnungsschicht,
• □ ein authentizitätsnachweisendes Sicherheitsmerkmal auf der Basis von lumineszierenden Komponenten,

wobei das wärmeempfindliche Aufzeichnungsmaterial optional eine die wärmeempfindliche Aufzeichnungsschicht abdeckende Schutzschicht aufweist,
dadurch gekennzeichnet, dass

• ■ die lumineszierenden Komponenten als anorganische Bestandteile in der wärmeempfindlichen Aufzeichnungsschicht und/oder in der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht eingebunden sind.

The object is achieved with a heat-sensitive recording material which has at least:

• □ a web-shaped substrate,
• □ a heat-sensitive recording layer,
• □ an authenticity-proofing security feature based on luminescent components,

wherein the heat-sensitive recording material optionally has a protective layer covering the heat-sensitive recording layer,
characterized in that

• The luminescent components are incorporated as inorganic constituents in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer.

• □ dass bei einem Fehlen der Schutzschicht die lumineszierenden Komponenten in der wärmeempfindlichen Aufzeichnungsschicht eingebunden sind und
• □ dass bei einem Vorhandensein der Schutzschicht die lumineszierenden Komponenten
  • entweder nur in dieser Schutzschicht
  • oder in einem ganz besonderen Maße bevorzugt sowohl in der wärmeempfindlichen Aufzeichnungsschicht wie auch in der Schutzschicht eingebunden sind, wobei die spezifische Masse an lumineszierenden Komponenten -jeweils bezogen auf 1 kg aller Bestandteile zum einen der wärmeempfindlichen Aufzeichnungsschicht und zum anderen der Schutzschicht - in der Schutzschicht bevorzugt höher als in der wärmeempfindlichen Aufzeichnungsschicht eingestellt ist.

The invention is characterized according to the statements of the previous paragraph, characterized in that the luminescent components are incorporated as inorganic constituents in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer. In this case, it is particularly preferred if the luminescent components are incorporated as inorganic constituents in the outer layer of the heat-sensitive recording material proposed here - this means

• □ that in the absence of the protective layer, the luminescent components are incorporated in the heat-sensitive recording layer, and
• □ that in the presence of the protective layer, the luminescent components
  • either only in this protective layer
  • or, to a very special extent, are preferred both in the heat-sensitive recording layer and in the protective layer, wherein the specific mass of luminescent components - in each case based on 1 kg of all components on the one hand the heat-sensitive recording layer and on the other hand the protective layer - in the protective layer is set higher than in the heat-sensitive recording layer.

It is considered within the scope of the invention proposed here as preferred if the inorganic constituents are fluorescent components, which means that the emission of the authenticity-detecting radiation, preferably in the form of infrared radiation, immediately after the start of excitation of the components usually by high-energy radiation, for example in the form of UV light and / or in the form of infrared rays, as they can be emitted, for example, lasers, laser diodes and LEDs begins, and that the emission of authentizitätsnachweisenden radiation soon after excitation end of the components also ends again, demonstrating the authenticity of a present Sufficient recording material and what is usually preferred by the users of the proposed recording material here. However, the invention is in no way limited to such fluorescent components: even after long excitation end nachstrahlende components are quite possible and can represent a preferred depending on the purpose embodiment.

• mindestens ein Element umfasst, das den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet wird,
  oder
• eine Mehrzahl an Elementen umfasst, die den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet werden.

In a preferred embodiment, the luminescent or preferably fluorescent components are formed as inorganic constituents in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer from a substance which

• comprises at least one element attributed to the transition metals and / or the rare earth metals,
  or
• comprises a plurality of elements attributed to the transition metals and / or the rare earth metals.

• □ solche, wie sie in der EP 0 966 504 B1 beansprucht werden und die dort als Zusammensetzung Ln_xYb_yEr_zO_aS_b vorgeschlagen werden, wobei
  • Ln mindestens ein Element darstellt, das ausgewählt ist aus der Gruppe, bestehend aus Yttrium (Y), Gadolinium (Gd), Scandium (Sc) und Lanthan (La),
  • Yb = Ytterbium, Er = Erbium, O = Sauerstoff, S = Schwefel ist,
  • die Summe aus (x+y+z) = 2 ergibt,
  • die Summe aus (a+b) ≤ 3 und b < 1 ist, a ≥ 2 ist und
  • die Werte für b die Relation 0,001 ≤ b ≤ 0,9 erfüllen;
• □ solche, wie sie in der EP 1 478 715 B1 beansprucht werden und die dort als Zusammensetzung (M_x, Yb_y, Tm_z)₂O₂S vorgeschlagen werden, wobei
  • M ausgewählt ist aus der Gruppe, bestehend aus Yttrium (Y), Gadolinium (Gd) und Lanthan (La),
  • Yb = Ytterbium, Tm = Thulium, O = Sauerstoff, S = Schwefel ist,
  • die Summe aus (x+y+z) = 1 ergibt und
  • die Relationen x > 0, y > 0 und 0,0025 ≤ z ≤ 0,03 erfüllt sind.

Preferred examples of such substances include

• □ such as those in the EP 0 966 504 B1 are claimed and proposed there as a composition Ln _x Yb _y Er _z O _a S _b , wherein
  • Ln represents at least one element selected from the group consisting of yttrium (Y), gadolinium (Gd), scandium (Sc) and lanthanum (La),
  • Yb = ytterbium, Er = erbium, O = oxygen, S = sulfur,
  • the sum of (x + y + z) = 2,
  • the sum of (a + b) ≤ 3 and b <1, a ≥ 2, and
  • the values for b satisfy the relation 0.001 ≤ b ≤ 0.9;
• □ such as those in the EP 1 478 715 B1 are claimed and proposed there as a composition (M _x , Yb _y , Tm _z ) ₂ O ₂ S, wherein
  • M is selected from the group consisting of yttrium (Y), gadolinium (Gd) and lanthanum (La),
  • Yb = ytterbium, Tm = thulium, O = oxygen, S = sulfur,
  • the sum of (x + y + z) = 1 gives and
  • the relations x> 0, y> 0 and 0.0025 ≤ z ≤ 0.03 are satisfied.

• mindestens ein Element umfasst, das den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet wird,
  oder
• eine Mehrzahl an Elementen umfasst, die den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet werden,

eingebunden in eine erste Beschichtungszusammensetzung. Dabei dient diese erste Beschichtungszusammensetzung zur Ausbildung der wärmeempfindlichen Aufzeichnungsschicht.In the context of a first preferred embodiment, the substance is the

• comprises at least one element attributed to the transition metals and / or the rare earth metals,
  or
• comprises a plurality of elements attributed to the transition metals and / or the rare earth metals,

integrated into a first coating composition. At this time, this first coating composition serves to form the heat-sensitive recording layer.

• mindestens ein Element umfasst, das den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet wird,
  oder
• eine Mehrzahl an Elementen umfasst, die den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet werden,

zu mindestens 0,5 g, besonders bevorzugt in einem Bereich von 1 g bis 25 g und ganz besonders bevorzugt in einem Bereich von 1,8 g bis 8,5 g - bezogen auf 1 kg aller Bestandteile der ersten Beschichtungszusammensetzung - in der ersten Beschichtungszusammensetzung zur Ausbildung der wärmeempfindlichen Aufzeichnungsschicht eingebunden.In the context of a particularly preferred embodiment of this first preferred embodiment, the substance is the

• comprises at least one element attributed to the transition metals and / or the rare earth metals,
  or
• comprises a plurality of elements attributed to the transition metals and / or the rare earth metals,

to at least 0.5 g, more preferably in a range of 1 g to 25 g and most preferably in a range of 1.8 g to 8.5 g - based on 1 kg of all components of the first coating composition - in the first coating composition integrated to form the heat-sensitive recording layer.

The thermosensitive recording layer formed from the first coating composition preferably comprises at least one organic dye precursor and at least one organic dye acceptor, with dye precursors and color acceptor under the action of heat color-forming react with each other.

Preferred dye precursors within the heat-sensitive recording layer are preferably those 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-anilinofluoran and 3- (N-ethyl-N-tetrahydrofuryl) amino-6-methyl-7-anilinofluoran. Very particular preference is given to 3-dibutylamino-6-methyl-7-anilinofluoran - also known as ODB-2.

It is also possible that the first coating composition for forming the thermosensitive recording layer has more than one dye precursor each selected from the dye precursors listed in the above paragraph.

• ■ 2,2 bis (4-hydroxyphenyl)-propan;
• ■ 4-[(4-(1-methylethoxy)phenyl)sulfonyl]phenol;
• ■ 4,4'-Dihydroxydiphenylsulfon;
• ■ N-(p-toluensulphonyl)-N'-(3-p-toluensulphonyl-oxy-phenyl)-harnstoff, auch bekannt als Pergafast^® 201 der Firma CIBA Speciality Chemicals Inc. und darstellbar gemäß der nachfolgenden Formel (1), wobei in manchen Darstellungen die CH₃-Gruppen auch weggelassen werden;
  
• ■ 2,4'-dihydroxy-diphenylsulfon;
• ■ N-(2-hydroxyphenyl)-2-[(4-hydroxyphenyl)thio]acetamid.

The heat-sensitive recording layer formed from the first coating composition preferably contains as color acceptor at least one substance selected from the list, comprising:

• ■ 2,2 bis (4-hydroxyphenyl) -propane;
• ■ 4 - [(4- (1-methylethoxy) phenyl) sulfonyl] phenol;
• 4,4'-dihydroxydiphenylsulfone;
• ■ N- (p-toluensulphonyl) -N '- (3-p-toluensulphonyl-oxy-phenyl) urea, also known as Pergafast ^® 201 from Ciba Specialty Chemicals Inc. and represented by the following Formula (1), wherein in some representations the CH ₃ groups are also omitted;
  
• ■ 2,4'-dihydroxydiphenylsulfone;
• ■ N- (2-hydroxyphenyl) -2 - [(4-hydroxyphenyl) thio] acetamide.

Suitable binders for incorporation into the heat-sensitive recording layer are, for example, water-soluble binders such as starch, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, in particular polyvinyl alcohols, modified polyvinyl alcohols, sodium polyacrylates, acrylamide-acrylate copolymers, acrylamide-acrylate-methacrylate terpolymers, in particular ethylene- Vinyl alcohol copolymers, alkali metal salts of styrene-maleic anhydride copolymers or ethylene-maleic anhydride copolymers, which can be used alone or in combination with one another; Water-insoluble latex binders such as styrene-butadiene copolymers, acrylonitrile-butadiene copolymers and methyl acrylate-butadiene copolymers are also suitable as binders for incorporation into the heat-sensitive recording layer. For the purposes of the present invention are polyvinyl alcohol in conjunction with ethylene-vinyl alcohol copolymers as very particularly preferred binders whose combination as the sole binder in a proportion of 12 to 27.5 wt .-%, based on the total weight of the first coating composition in the heat-sensitive recording layer are involved.

To avoid sticking to a thermal head and avoiding excessive wear of the thermal head, the first coating composition for forming the thermosensitive recording layer may further contain lubricants and release agents such as metal salts of higher fatty acids, for example, zinc stearate, calcium stearate and waxes such as paraffin, oxidized paraffin , Polyethylene, polyethylene oxide, stearamides and castor wax. Other constituents of the heat-sensitive recording layer may be, for example, pigments, preferably inorganic pigments such as, for example, kaolin, silicon (di) oxide, bentonite, talc, calcium carbonate and aluminum (hydr) oxide and in particular boehmite here. With respect to the kaolin, in the laboratory and experimental production work on which the invention is based, the present inventors recognized that calcined kaolin should be rejected because of its high abrasiveness for incorporation into the first coating composition for forming the thermosensitive recording layer, particularly when a protective layer covering the thermosensitive recording layer is not provided. For the purposes of the present invention, particular preference is given to calcium carbonate, which should preferably be incorporated in the heat-sensitive recording layer in an amount of from 10 to 18% by weight, based on the total weight of the first coating composition.

It has also been recognized that, in particular, a ratio based on the weight% in the first coating composition
Fabric _according to paragraphs _{[0016] to [0019]} : total amount of dye precursor and dye acceptor in a range of 1 g: 1 kg to 25 g: 1 kg.

• mindestens ein Element umfasst, das den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet wird,
  oder
• eine Mehrzahl an Elementen umfasst, die den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet werden,

eingebunden in eine vierte Beschichtungszusammensetzung. Dabei dient diese vierte Beschichtungszusammensetzung zur Ausbildung der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht.In the context of a second preferred embodiment, the substance is the

• comprises at least one element attributed to the transition metals and / or the rare earth metals,
  or
• comprises a plurality of elements attributed to the transition metals and / or the rare earth metals,

integrated into a fourth coating composition. In this case, this fourth coating composition serves to form the protective layer covering the heat-sensitive recording layer.

• mindestens ein Element umfasst, das den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet wird,
  oder
• eine Mehrzahl an Elementen umfasst, die den Übergangsmetallen und/oder den Metallen der Seltenen Erden zugerechnet werden,

zu mindestens 1 g, besonders bevorzugt in einem Bereich von 1,5 g bis 75 g und ganz besonders bevorzugt in einem Bereich von 2,25 g bis 10,5 g - bezogen auf 1 kg aller Bestandteile der vierten Beschichtungszusammensetzung - in der vierten Beschichtungszusammensetzung zur Ausbildung der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht eingebunden.In the context of a particularly preferred embodiment of this second preferred embodiment, the substance is the

• comprises at least one element attributed to the transition metals and / or the rare earth metals,
  or
• comprises a plurality of elements attributed to the transition metals and / or the rare earth metals,

to at least 1 g, more preferably in a range of from 1.5 g to 75 g, and most preferably in a range of from 2.25 g to 10.5 g, based on 1 kg of all components of the fourth coating composition, in the fourth coating composition for forming the protective layer covering the heat-sensitive recording layer.

• □ die im Rahmen einer ersten bevorzugten Ausführungsform auf der Basis von Ethylen-Vinyl-Alkohol-Copolymer (EVOH) hergestellt ist und die dann bevorzugt zu mindestens 90 Gew.-%, ganz besonders bevorzugt zu mindestens 98 Gew.-% - jeweils bezogen auf das Gesamtgewicht einer solchen Schutzschicht - Ethylen-Vinyl-Alkohol-Copolymer enthält,
• □ gilt insbesondere eine im Rahmen einer zur ersten bevorzugten Ausführungsform alternativen zweiten Ausführungsform ausgebildete Schutzschicht in einem ganz besonderen Maße im Sinne der vorliegenden Erfindung als bevorzugt, die als Bindemittel zu mindestens 60 Gew.-%, besonders bevorzugt zu mindestens 85 Gew.-%, Diaceton-modifizierten Polyvinylalkohol aufweist, wobei sich diese beiden Werte zu den Gew.-% auf den Gesamtanteil an Bindemittel in der Schutzschicht gemäß zweiter Ausführungsform beziehen.

In addition to a protective layer,

• □ which is produced in the context of a first preferred embodiment based on ethylene-vinyl alcohol copolymer (EVOH) and which then preferably at least 90 wt .-%, most preferably at least 98 wt .-% - in each case based on contains the total weight of such a protective layer - ethylene-vinyl alcohol copolymer,
• In particular, a protective layer formed in the context of a second embodiment which is an alternative to the first preferred embodiment is considered to be particularly preferred in the sense of the present invention, which as binder at least 60 wt .-%, particularly preferably at least 85 wt .-%, Diaceton-modified polyvinyl alcohol, wherein these two values relate to the wt .-% on the total content of binder in the protective layer according to the second embodiment.

In the context of this second embodiment, the particularly preferred protective layer of the proposed heat-sensitive recording material may, in addition to the diacetone-modified polyvinyl alcohol in a first possible embodiment, comprise further binders, in particular mixtures of different carboxyl group-modified or silanol-modified polyvinyl alcohols. These then make up a maximum of 40 wt .-%, more preferably only a maximum of 15 wt .-%, again, based on the total amount of binder in the protective layer. In a second possible embodiment, the protective layer of the proposed thermosensitive recording material has as binder exclusively diacetone-modified polyvinyl alcohol. In particular, when diacetone-modified polyvinyl alcohol is the sole binder in the protective layer covering the heat-sensitive recording layer, it is most preferable that the binder content in the protective layer is in a range of 35 to 65% by weight based on the total weight of the protective layer ,

Suitable crosslinking aids in the protective layer according to the second embodiment are, in particular, those selected from the group comprising: boric acid, polyamine, epoxy resin, dialdehyde, formaldehyde oligomers, epiochlorohydrin resin, adipic dihydrazide, dimethylurea, melamine-formaldehyde. It is also possible to use mixtures of different crosslinking aids.

It is preferable that within the protective layer according to the second embodiment, the ratio of the weight percent of the binder, especially the diacetone-modified polyvinyl alcohol, to the crosslinking aid is in a range of 20: 1 to 5: 1, and more preferably in a range of 12: 1 to 7: 1.

Particularly good results have been achieved if the protective layer additionally contains an inorganic pigment. It is particularly recommended that the inorganic pigment is selected from the group consisting of silica, aluminum hydroxide, bentonite, calcium carbonate, non-calcined kaolin or a mixture of said inorganic pigments. In particular, a ratio pigment and here very particularly preferably non-calcined kaolin to the diacetone-modified polyvinyl alcohol in a range of 1: 1.5 to 1: 4.5 set, the ratio values based on the respective wt .-% of pigment and polyvinyl alcohol in the protective layer.

The heat-sensitive recording material proposed herein preferably comprises a pigmented intermediate layer formed of a third coating composition located between the sheet-shaped substrate and the heat-sensitive recording layer. The pigmented intermediate layer very particularly preferably has both at least one organic pigment and at least one inorganic pigment. It is possible that not only one inorganic pigment but several different inorganic pigments are incorporated into the third coating composition for forming the pigmented intermediate layer. The inorganic pigments are preferably selected individually or in combination with one another from the list, comprising: kaolin, silicon (di) oxide, bentonite, talc, calcium carbonate and aluminum (hydr) oxide and, in particular, boehmite.

The ratio between organic and inorganic pigment is a compromise of the effects caused by the two types of pigments, which is particularly advantageously solved 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.

The organic pigments have a wall of thermoplastic resin which preferably comprises (meth) acrylonitrile copolymer, polyvinyl chloride, polyvinylidene chloride, polystyrene, styrene acrylate, polyacrylonitrile or polyacrylic acid ester. Pigment mixtures of different organic pigments are conceivable. A glass transition temperature greater than or equal to 100 ° C and preferably greater than or equal to 105 ° C was found to be advantageous because below these temperatures, an increased degree of yellowing was detected.

In addition to the inorganic and optionally also organic pigments, the third coating composition contains at least one binder, preferably based on a synthetic polymer, wherein, for example, styrene-butadiene latex gives particularly good results. The use of at least one synthetic binder with the admixture of at least one natural polymer, more preferably starch, is a particularly suitable embodiment. Numerous tests have also found that with a binder to pigment ratio within the third coating composition 3: 7 and 1: 9, in each case based on wt .-%, a particularly suitable embodiment is present.

The heat-sensitive recording material proposed here may alternatively or preferably also contain, in addition to the pigmented intermediate layer formed from the third coating composition, a barrier-forming intermediate layer formed from a second coating composition. The reason for forming the barrier layer sandwiched between the substrate and the heat-sensitive recording layer is to protect the heat-sensitive recording layer from chemicals that can either cause an unwanted color-forming reaction in the recording layer or a weakening of a typeface to be formed or formed in the recording layer and, crucially, may also be contained in larger amounts in the substrate and / or applied to the backside of the substrate. The above-mentioned chemicals are primarily intended to include but are not limited to plasticizers, and more particularly organic solvents. The chemicals mentioned can come into contact with the recording material proposed here on the one hand in the context of its intended use as a ticket or as a ticket or as part of applied authentification-proofing test tinctures.

The barrier-forming intermediate layer of the proposed heat-sensitive recording material formed within this second coating composition preferably comprises at least 90% by weight, most preferably at least 98% by weight, based in each case on the total weight of the barrier-forming intermediate layer, of the ethylene-vinyl alcohol copolymer. Further constituents of this barrier-forming intermediate layer can furthermore be, for example, defoamers and / or agents for stabilizing the color curtain in the case of a possible application of the second coating composition by means of curtain coats or slide coaters.

• ■ dass die Barriere bildende Zwischenschicht dem Substrat zugewandt ist und
• ■ dass die pigmentierte Zwischenschicht der wärmeempfindlichen Aufzeichnungsschicht zugewandt ist.

If the heat-sensitive recording material proposed here has both a pigmented intermediate layer formed from a third coating composition and a barrier-forming intermediate layer formed from a second coating composition, the order of these two intermediate layers must be set in such a way that

• ■ that the barrier-forming intermediate layer faces the substrate and
• ■ that the pigmented intermediate layer faces the heat-sensitive recording layer.

• □ einem bahnförmigen Substrat,
• □ einer aus der zweiten Beschichtungszusammensetzung ausgebildeten Barriere bildenden Zwischenschicht und/oder einer aus der dritten Beschichtungszusammensetzung ausgebildeten pigmentierten Zwischenschicht
• □ einer aus der ersten Beschichtungszusammensetzung ausgebildeten wärmeempfindlichen Aufzeichnungsschicht,
• □ optional einer aus der vierten Beschichtungszusammensetzung ausgebildeten, die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht,

wobei

• ■ lumineszierenden Komponenten als anorganische Bestandteile in mindestens einer der optional beiden Zwischenschichten, in der wärmeempfindlichen Aufzeichnungsschicht und/oder in der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht eingebunden sind.

As part of further attempts in the run-up to this invention, samples of heat-sensitive recording materials were made with

• □ a web-shaped substrate,
• □ a barrier-forming intermediate layer formed from the second coating composition and / or a pigmented intermediate layer formed from the third coating composition
• □ a thermosensitive recording layer formed of the first coating composition,
• Optionally, a protective layer formed of the fourth coating composition covering the heat-sensitive recording layer,

in which

• ■ Luminescent components are incorporated as inorganic constituents in at least one of the optional two intermediate layers, in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer.

• in mindestens einer der optional beiden Zwischenschichten,
• in der wärmeempfindlichen Aufzeichnungsschicht und/oder
• in der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht
• in der Schutzschicht bevorzugt höher als in der wärmeempfindlichen Aufzeichnungsschicht, in der wärmeempfindlichen Aufzeichnungsschicht bevorzugt höher als in der optionalen pigmentierten Zwischenschicht und in der optionalen pigmentierten Zwischenschicht bevorzugt höher als in der optionalen Barriere bildenden Zwischenschicht eingestellt ist.

A possible embodiment of the invention disclosed in the previous paragraph is considered to be very particularly preferred, with particularly convincing results could be achieved if the specific mass of luminescent components - in each case based on 1 kg of all components

• in at least one of the optional two intermediate layers,
• in the heat-sensitive recording layer and / or
• in the protective layer covering the heat-sensitive recording layer
• in the protective layer is preferably higher than in the heat-sensitive recording layer, preferably higher in the heat-sensitive recording layer than in the optional pigmented intermediate layer and in the optional pigmented intermediate layer, higher than in the optional barrier-forming intermediate layer.

• ■ als nicht oberflächenbehandeltes, idealerweise in der Masse geleimtes Papier,
• ■ als ungeleimtes, aber zumindest einseitig präpariertes Papier,
• ■ als zumindest einseitig mit einer Polyolefinbeschichtung versehenes Papier

zum Einsatz kommt. Dabei kann dieses Papier - gerade bei seiner vorgesehenen Verwendung als Fahrscheinmaterial bei Bussen und Bahnen genauso wie im Flugverkehr - insbesondere ein Wasserzeichen als ein zweites authentizitätsnachweisendes Sicherheitsmerkmal aufweisen, wobei - wie bereits eingangs ausgeführt - unterschieden wird zwischen

• echten Wasserzeichen, die durch Verdrängung (sogenannte Licht-Wasserzeichen) oder durch Anreicherung (sogenannte Schatten-Wasserzeichen) der Fasermasse beispielsweise unter Verwendung eines Egoutteurs in der Siebpartie einer Papiermaschine hergestellt werden,
• halbechten, sogenannten Moletten-Wasserzeichen, die durch die Prägung des noch nassen Papiers in der Pressenpartie einer Papiermaschine erzeugt werden, und schließlich
• unechten Wasserzeichen, wobei letztere entweder durch das Bedrucken des fertig gestellten Papiers außerhalb der Papiermaschine mit einem farblosen Lack oder durch das Prägen des fertig gestellten Papiers außerhalb der Papiermaschine erstellt werden.

Im Sinne der vorliegenden Erfindung gelten alle oben genannten Sicherheitsmerkmale als bevorzugt, die Einbindung eines echten Wasserzeichens überdies als ganz besonders bevorzugt.As a web-shaped substrate paper is preferred as that particular

• ■ as non-surface treated, ideally sized paper,
• ■ as unsized, but at least unilaterally prepared paper,
• ■ Paper provided with a polyolefin coating on at least one side

is used. In this case, this paper - especially in its intended use as a ticket material on buses and trains as well as in air traffic - in particular have a watermark as a second authentizitätsnachweisendes security feature, which - as already mentioned - a distinction between

• genuine watermarks produced by displacement (so-called light watermarks) or by enrichment (so-called shadow watermarks) of the fiber mass, for example using a dandy cutter in the wire section of a paper machine,
• Halbchten, so-called Moletten watermarks, which are produced by embossing the still wet paper in the press section of a paper machine, and finally
• spurious watermarks, the latter being created either by printing the finished paper outside the paper machine with a colorless paint or by embossing the finished paper outside the paper machine.

For the purposes of the present invention, all the above-mentioned security features are considered to be preferred, the inclusion of a real watermark moreover than being particularly preferred.

The invention also relates, to the same extent, to processes for producing a heat-sensitive recording material in all the embodiments and variants already proposed here.

• □ Ausbilden eines bahnförmigen Substrates;
  
• □ Vorbereiten einer ersten Beschichtungszusammensetzung, wobei diese erste Beschichtungszusammensetzung mindestens umfasst:
  • mindestens einen Farbstoffvorläufer,
  • mindestens einen Farbakzeptor,
    wobei Farbstoffvorläufer und Farbakzeptor unter Einwirkung von Wärme farbbildend miteinander reagieren;
• □ Aufbringen der vorbereiteten ersten Beschichtungszusammensetzung zur Ausbildung einer wärmeempfindlichen Aufzeichnungsschicht auf der optionalen pigmentierten Zwischenschicht;
• □ Trocknen der ersten Beschichtungszusammensetzung;
• □ Vorbereiten einer vierten Beschichtungszusammensetzung;
• □ Aufbringen der vorbereiteten vierten Beschichtungszusammensetzung zur Ausbildung einer die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht;
• □ Trocknen der vierten Beschichtungszusammensetzung;

wobei lumineszierende Komponenten als anorganische Bestandteile in der ersten Beschichtungszusammensetzung zur Ausbildung der wärmeempfindlichen Aufzeichnungsschicht und/oder in der vierten Beschichtungszusammensetzung zur Ausbildung der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht eingebunden sind;

• □ Aufrollen des bahnförmigen Substrates mit der ausgebildeten pigmentierten Zwischenschicht, mit der ausgebildeten wärmeempfindlichen Aufzeichnungsschicht und mit der ausgebildeten die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht.

In this case, such a method preferably comprises the following method steps:

• □ forming a web-shaped substrate;
  
• □ preparing a first coating composition, said first coating composition comprising at least
  • at least one dye precursor,
  • at least one color acceptor,
    wherein dye precursor and color acceptor react with each other under the action of heat in a color-forming manner;
• Applying the prepared first coating composition to form a heat-sensitive recording layer on the optional pigmented intermediate layer;
• □ drying the first coating composition;
• □ preparing a fourth coating composition;
• □ applying the prepared fourth coating composition to form a protective layer covering the heat-sensitive recording layer;
• □ drying the fourth coating composition;

wherein luminescent components as inorganic constituents in the first coating composition for forming the heat-sensitive recording layer and / or in the fourth coating composition for forming the protective layer covering the heat-sensitive recording layer;

• Rolling up the web-shaped substrate with the formed pigmented intermediate layer, with the heat-sensitive recording layer formed and with the protective layer covering the heat-sensitive recording layer.

• entweder nur in dieser Schutzschicht
• oder in einem ganz besonderen Maße bevorzugt sowohl in der wärmeempfindlichen Aufzeichnungsschicht wie auch in der Schutzschicht eingebunden sind, wobei die spezifische Masse an lumineszierenden Komponenten - bezogen auf 1 kg aller Bestandteile zum einen der wärmeempfindlichen Aufzeichnungsschicht und zum anderen der Schutzschicht - in der Schutzschicht höher als in der wärmeempfindlichen Aufzeichnungsschicht eingestellt werden.

In this case, it is particularly preferred if the luminescent components are incorporated as inorganic constituents in the outer layer of the heat-sensitive recording material proposed here with regard to its production method - this means that the luminescent components

• either only in this protective layer
• or, to a very special extent, are preferably incorporated in both the heat-sensitive recording layer and in the protective layer, the specific mass of luminescent components - based on 1 kg of all components on the one heat-sensitive recording layer and on the other hand the protective layer - in the protective layer being higher than in the heat-sensitive recording layer.

• □ Ausbilden eines bahnförmigen Substrates;
• □ Vorbereiten einer zweiten Beschichtungszusammensetzung, wobei diese zweite Beschichtungszusammensetzung mindestens umfasst:
  • Ethylen-Vinyl-Alkohol-Copolymer,
  • optional Entschäumer,
  • optional Mittel zur Stabilisierung eines Farbvorhangs;
• □ Aufbringen der vorbereiteten zweiten Beschichtungszusammensetzung zur Ausbildung einer Barriere bildende Zwischenschicht auf dem bahnförmigen Substrat;
• □ Trocknen der zweiten Beschichtungszusammensetzung;
• □ Vorbereiten einer dritten Beschichtungszusammensetzung, wobei diese dritte Beschichtungszusammensetzung bevorzugt mindestens umfasst:
  • mindestens ein organisches und/oder mindestens ein anorganisches Pigment,
  • ein Bindemittel;
• □ Aufbringen der vorbereiteten dritten Beschichtungszusammensetzung zur Ausbildung einer pigmentierten Zwischenschicht auf dem bahnförmigen Substrat;
• □ Trocknen der dritten Beschichtungszusammensetzung;
• □ Vorbereiten einer ersten Beschichtungszusammensetzung, wobei diese erste Beschichtungszusammensetzung mindestens umfasst:
  • mindestens einen Farbstoffvorläufer,
  • mindestens einen Farbakzeptor,
    wobei Farbstoffvorläufer und Farbakzeptor unter Einwirkung von Wärme farbbildend miteinander reagieren;
• □ Aufbringen der vorbereiteten ersten Beschichtungszusammensetzung zur Ausbildung einer wärmeempfindlichen Aufzeichnungsschicht auf der optionalen pigmentierten Zwischenschicht;
• □ Trocknen der ersten Beschichtungszusammensetzung;
• □ Vorbereiten einer vierten Beschichtungszusammensetzung;
• □ Aufbringen der vorbereiteten vierten Beschichtungszusammensetzung zur Ausbildung einer die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht;
• □ Trocknen der vierten Beschichtungszusammensetzung;

wobei lumineszierende Komponenten als anorganische Bestandteile in der ersten Beschichtungszusammensetzung zur Ausbildung der wärmeempfindlichen Aufzeichnungsschicht und/oder in der vierten Beschichtungszusammensetzung zur Ausbildung der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht eingebunden sind;

• □ Aufrollen des bahnförmigen Substrates mit der ausgebildeten Barriere bildenden Zwischenschicht, mit der ausgebildeten pigmentierten Zwischenschicht, mit der ausgebildeten wärmeempfindlichen Aufzeichnungsschicht und mit der ausgebildeten, die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht.

In order to produce a heat-sensitive recording material with both a barrier-forming intermediate layer and with a pigmented intermediate layer, such a method preferably comprises at least the following method steps:

• □ forming a web-shaped substrate;
• □ preparing a second coating composition, said second coating composition comprising at least
  • Ethylene-vinyl alcohol copolymer,
  • optional defoamer,
  • optional means for stabilizing a color curtain;
• Applying the prepared second coating composition to form a barrier-forming intermediate layer on the web-shaped substrate;
• □ drying the second coating composition;
• □ preparing a third coating composition, said third coating composition preferably comprising at least
  • at least one organic and / or at least one inorganic pigment,
  • a binder;
• Applying the prepared third coating composition to form a pigmented intermediate layer on the web-shaped substrate;
• □ drying the third coating composition;
• □ preparing a first coating composition, said first coating composition comprising at least
  • at least one dye precursor,
  • at least one color acceptor,
    wherein dye precursor and color acceptor react with each other under the action of heat in a color-forming manner;
• Applying the prepared first coating composition to form a heat-sensitive recording layer on the optional pigmented intermediate layer;
• □ drying the first coating composition;
• □ preparing a fourth coating composition;
• □ applying the prepared fourth coating composition to form a protective layer covering the heat-sensitive recording layer;
• □ drying the fourth coating composition;

wherein luminescent components are incorporated as inorganic constituents in the first coating composition for forming the thermosensitive recording layer and / or in the fourth coating composition for forming the protective layer covering the thermosensitive recording layer;

• Rolling the sheet-like substrate with the barrier layer forming intermediate layer, with the formed pigmented intermediate layer, with the formed heat-sensitive recording layer and with the formed, the heat-sensitive recording layer covering protective layer.

In a possible preferred embodiment of the invention, the luminescent components can be incorporated as inorganic constituents in at least one of the optionally two intermediate layers, in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer.

• in mindestens einer der optional beiden Zwischenschichten,
• in der wärmeempfindlichen Aufzeichnungsschicht
  und/oder
• in der die wärmeempfindliche Aufzeichnungsschicht abdeckenden Schutzschicht
• in der Schutzschicht höher als in der wärmeempfindlichen Aufzeichnungsschicht, in der wärmeempfindlichen Aufzeichnungsschicht höher als in der optionalen pigmentierten Zwischenschicht und in der optionalen pigmentierten Zwischenschicht höher als in der optionalen Barriere bildenden Zwischenschicht eingestellt werden.

The corresponding method then preferably provides that the specific mass of luminescent components,
in each case based on 1 kg of all components

• in at least one of the optional two intermediate layers,
• in the heat-sensitive recording layer
  and or
• in the protective layer covering the heat-sensitive recording layer
• are set higher in the protective layer than in the heat-sensitive recording layer, higher in the heat-sensitive recording layer than in the optional pigmented intermediate layer and in the optional pigmented intermediate layer than in the optional barrier-forming intermediate layer.

The formation of the web-like substrate is done for example on a paper machine, in which at least one upstream Mischbütte a paper pulp of different pulps, optionally groundwood, fillers and water is applied and where to this paper pulp before being fed to the paper machine preferably further ingredients such as resin glue for engine sizing and other customary additives, such as pigments, shading dyes and / or optical brighteners are added. In particular, but not limitation, when such a paper machine is a fourdrinier paper machine, it constitutes a preferred embodiment when a dandy is placed above the papermachine fabric or other suitable location in the papermaking machine, with the aid of which a real one Watermark is pressed into the still wet substrate.

After a possible smoothing of the optionally produced by Egoutteur, genuine watermarked paper web as a web-shaped substrate, this can be rolled up at the end of the paper machine as a semi-finished product on a spool.

• ausgesucht aus der Barriere bildenden Zwischenschicht und der pigmentierten Zwischenschicht -

und darauf die vorbereitete erste Beschichtungszusammensetzung zur Ausbildung einer wärmeempfindlichen Aufzeichnungsschicht aufgebracht.After an optionally necessary upstream unrolling of the web-shaped substrate as a semi-finished product from a spool, the web-shaped substrate is optionally optionally at least one intermediate layer

• selected from the barrier-forming intermediate layer and the pigmented interlayer -

and then applying the prepared first coating composition for forming a heat-sensitive recording layer.

The optional second coating composition for forming the barrier-forming intermediate layer is preferably applied in particular by means of non-contact application devices, such as air brushes and curtain coater, without being limited to these in any way. The coating weight for the barrier-forming intermediate layer is preferably in a range of 0.9 to 5.0 g / m 2, most preferably in a range of 1.5 to 3.5 g / m 2.

Preferably, the optional third coating composition for forming the pigmented interlayer is applied by means of a leveling coating process selected from the list comprising: roller coater, doctor blade or doctor blade coater. Especially in a method using any of these coating methods, the intermediate layer can positively contribute to leveling of the substrate surface, thus reducing the amount of the applied mass of the first coating composition for forming the heat-sensitive recording layer. The subsequent drying of the coating composition of this third coating composition is usually carried out by a method in which heat is supplied, as is done by hot-air floatation dryer or contact dryer. Proven is also a combination of the listed dry processes. For the basis weight of the pigmented intermediate layer, a preferred range between 5 and 20 g / m ² and even better between 7 and 12 g / m ^{2 has} proven.

Preferably, the first coating composition is applied by means of a coating process selected from the list comprising: roller blade coater, knife coater, curtain coater or air brush. The first coating composition used to form the heat-sensitive recording layer is preferably aqueous. The subsequent drying of the first coating composition is usually carried out by a method in which heat is supplied, as is done by hot-air floatation 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 2.2 to 4.8 g / m ² .

A coating apparatus for applying the thermosensitive recording layer covering a fourth coating composition formed protective layer are particularly suitable for roller blade coater, knife coater, curtain coater or air brush. The basis weight of the protective layer is preferably between 1.0 and 3.0 g / m ² and more preferably between 1.6 and 2.3 g / m ² .

The method for producing a heat-sensitive recording material, as proposed here, provides, in a preferred variant, smoothing of the substrate with the now applied and dried first, optionally second and / or third and fourth coating compositions. The aim of such a smoothing by a calender or a calender is to create a flattened, possibly shiny surface, with which applied typefaces appear more colorful and lively. Furthermore, a smoother surface of the heat-sensitive recording layer or an existing protective layer by improved contact with the thermal head supports the heat transfer and thus the sensitivity of this heat-sensitive recording layer.

Finally, the recording material finished in this way is preferably rolled up on a spool and is then ready for use according to the customer's wishes, in particular as a ticket.

The present invention, in addition to the disclosed methods for producing a thermosensitive recording material in all the embodiments and variants already proposed herein and in addition to the recording material itself, also claims the use of the here proposed recording material for issuing tickets and / or tickets for entry and use public transport systems and for public events at a suitable thermal printer. Numerous tests and test series of heat-sensitive recording materials according to the embodiments and variants proposed here have been able to show their superior effect in their use as a public transport ticket, on buses and trains as well as in air traffic, but also as tickets to stadium and museum funds.

The details given in the description and patent claims relating to basis weight,% by weight (% by weight) and parts by weight (parts by weight) relate in each case to the "atro" weight, ie absolutely dry parts by weight. In the comments on the organic pigments of the pigment-containing intermediate layer, the relevant figures are calculated from the "lutro" weight, ie air-dry Parts by weight, less the proportion by weight of water around and inside the pigments as supplied.

Claims (17)

Heat-sensitive recording material, comprising at least: □ a web-shaped substrate, □ a heat-sensitive recording layer, □ an authenticity-proofing security feature based on luminescent components,
wherein the heat-sensitive recording material optionally has a protective layer covering the heat-sensitive recording layer,
characterized in that The luminescent components are incorporated as inorganic constituents in the heat-sensitive recording layer and / or in the protective layer covering the heat-sensitive recording layer. Heat-sensitive recording material according to claim 1, characterized in that the inorganic constituents are fluorescent components. Heat-sensitive recording material according to one of the claims 1 or 2, characterized in that the inorganic constituents are formed from a substance which comprises at least one element which is attributed to the transition metals and / or the metals of the rare earths. Heat-sensitive recording material according to one of claims 1 to 2, characterized in that the inorganic constituents are formed from a substance comprising a plurality of elements which are attributed to the transition metals and / or the metals of the rare earths. Heat-sensitive recording material according to one of the claims 3 or 4, characterized in that the substance which at least one element attributed to the transition metals and / or the metals of the rare earths,
or a plurality of elements attributed to the transition metals and / or the rare earth metals,
to at least 0.5 g - based on 1 kg of all components of a first coating composition - is incorporated in the first coating composition for forming the heat-sensitive recording layer. Heat-sensitive recording material according to one of the claims 3 to 5, characterized in that the substance, the at least one element attributed to the transition metals and / or the metals of the rare earths,
or a plurality of elements attributed to the transition metals and / or the rare earth metals, to at least 0.5 g, based on 1 kg of all components of a fourth coating composition, is incorporated in the fourth coating composition for forming the protective layer covering the heat-sensitive recording layer. Heat-sensitive recording material according to one of claims 1 to 6, characterized in that the specific mass of luminescent components - in each case based on 1 kg of all constituents of one of the heat-sensitive recording layer and the other of the protective layer - in the protective layer preferably set higher than in the heat-sensitive recording layer is. A heat-sensitive recording material according to any one of claims 1 to 7, characterized in that the heat-sensitive recording material has a pigmented intermediate layer formed of a third coating composition. Heat-sensitive recording material according to claim 8, characterized in that the pigmented intermediate layer formed from the third coating composition contains at least one organic pigment and at least one inorganic pigment. Heat-sensitive recording material according to one of the claims 1 to 9, characterized in that the heat-sensitive recording layer comprises at least one organic dye precursor and at least one organic dye acceptor, wherein the dye precursor and dye acceptor react color-forming with the action of heat. A heat-sensitive recording material according to any one of claims 1 to 10, characterized in that the heat-sensitive recording layer contains, as a binder, a substance selected from the list comprising: polyvinyl alcohol, ethylene-vinyl alcohol copolymer or a combination of polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Heat-sensitive recording material according to one of claims 1 to 11, characterized in that the protective layer comprises at least 60% by weight, based on the total amount of binder in the protective layer, of diacetone-modified polyvinyl alcohol as binder. Process for the preparation of a heat-sensitive recording material according to one of claims 8 to 12, comprising at least the following process steps: □ forming a web-shaped substrate; □ preparing a third coating composition, said third coating composition comprising at least at least one organic and / or at least one inorganic pigment, a binder; Applying the prepared third coating composition to form a pigmented intermediate layer on the web-shaped substrate; □ drying the third coating composition; □ preparing a first coating composition, said first coating composition comprising at least at least one dye precursor, at least one color acceptor,
wherein dye precursor and color acceptor react with each other under the action of heat in a color-forming manner; Applying the prepared first coating composition to form a heat-sensitive recording layer on the pigmented intermediate layer; □ drying the first coating composition; □ preparing a fourth coating composition; □ applying the prepared fourth coating composition to form a protective layer covering the heat-sensitive recording layer; □ drying the fourth coating composition; wherein luminescent components are incorporated as inorganic constituents in the first coating composition for forming the thermosensitive recording layer and / or in the fourth coating composition for forming the protective layer covering the thermosensitive recording layer; Rolling up the web-shaped substrate with the formed pigmented intermediate layer, with the heat-sensitive recording layer formed and with the protective layer covering the heat-sensitive recording layer. A process for producing a heat-sensitive recording material according to claim 13, characterized in that the third coating composition is applied by means of a leveling coater selected from the list comprising: roller coater, doctor blade or doctor blade coater. A process for the preparation of a thermosensitive recording material according to any one of claims 13 and 14, characterized in that the fourth coating composition is applied by means of a coating aggregate selected from the list comprising: roller blade coater, knife coater, curtain coater or air brush. Process for the preparation of a heat-sensitive recording material according to one of the claims 13 to 15, characterized in that the web-shaped substrate is produced by means of a paper machine having a dandy who presses a real watermark into the still wet substrate. Use of a heat-sensitive recording material according to one of the claims 1 to 12 as a ticket for entry and use for public transport systems and for public events.