EP3746308B1 - Coating composition, heat-sensitive recording layer, heat-sensitive recording material, and corresponding uses and methods - Google Patents

Description

The present invention relates to a coating composition for producing a heat-sensitive recording material and a corresponding heat-sensitive recording layer. The coating composition comprises one or more color developers, one or more dye precursors, one or more specific fatty acid amides and one or more (further) specific sensitizers. The present invention also relates to a heat-sensitive recording material, comprising a carrier substrate and a heat-sensitive recording layer according to the invention. The present invention also relates to the use of specific fatty acid amides to increase the grease resistance of a heat-sensitive recording material or a heat-sensitive recording layer. The present invention also relates to a method for producing a heat-sensitive recording material or a heat-sensitive recording layer according to the invention.

Heat-sensitive recording materials (for example for direct thermal printing) which have a heat-sensitive color-forming recording layer applied to a carrier substrate have been known for many years and are very popular. This popularity is due, among other things, to the fact that their use is associated with the advantage that the color-forming components are contained in the recording material itself and therefore toner-free and ink-cartridge-free printers can be used. It is therefore not necessary to toner or color cartridges acquire or fill up. As a result, this innovative technology has established itself across the board, especially in public transport and retail.

A dye precursor and a color developer are present in a coating composition for the production of a heat-sensitive recording material and in heat-sensitive recording layers of conventional recording materials. Upon imagewise heating of the heat-sensitive recording layer to a suitable temperature using a suitable imaging tool, e.g and as a result of this chemical reaction, an image of high color density is almost instantaneously formed on the recording medium. The use of non-phenolic color developers has been preferred recently and also within the scope of the present invention.

A heat-sensitive recording material is regularly produced by applying a coating composition for producing a heat-sensitive recording layer to a suitable carrier substrate, ie a suitable paper web, a plastic film or a corresponding material, using a coating machine, then drying the coating composition to form the heat-sensitive recording layer and optionally using a calender is smoothed. In addition to the heat-sensitive recording layer, pre-, intermediate and/or top-coatings can be applied to either one or both sides of the recording material. This also applies to a heat-sensitive recording material according to the invention.

A coating composition for producing a heat-sensitive recording layer or a heat-sensitive recording material is often (as also in the context of the present invention) prepared by separately at least one dye precursor, at least one color developer and at least one sensitizer using bead or ball mills in water or a suitable Solvents are ground to a suitable grain size and dispersed. The fine dispersions produced in this way are mixed in the desired ratio with the binders, pigments, lubricants and release agents and other customary auxiliaries which are used together with these fine dispersions as the coating composition for the heat-sensitive recording layer.

• □ Bisphenol-A, das ist 2,2-Bis-(4-hydroxyphenyl)-propan, und
• □ Bisphenol-S, das ist 4,4-Dihydroxydiphenylsulfon,

verstärkt im Zentrum öffentlicher Kritik und werden deshalb beispielsweise vollständig oder teilweise ersetzt durch NKK, das ist N-[2-(3-Phenylureido)phenyl]benzolsulfonamid der Formel

In the recent past, concerns about the environmental compatibility of certain (bis)phenolic color developers in particular have increased. For example, the well-known and scientifically well-researched components known as

• □ Bisphenol-A, which is 2,2-bis-(4-hydroxyphenyl)-propane, and
• □ Bisphenol-S, that is 4,4-dihydroxydiphenylsulfone,

increasingly at the center of public criticism and are therefore, for example, completely or partially replaced by NKK, that is N-[2-(3-phenylureido)phenyl]benzenesulfonamide of the formula

The present invention relates to such a coating composition for preparing a heat-sensitive recording material and a heat-sensitive recording layer, each comprising NKK as a color developer.

The document DE 10 2014 107 567 B3 relates, according to its independent claim 1, to a heat-sensitive recording material comprising a carrier substrate and a heat-sensitive color-forming layer containing at least one color former (ie dye precursor), at least one phenol-free color developer and at least one sensitizer. Paragraph [0014] discloses N-[2-(3-phenylureido)phenyl]benzenesulfonamide (NKK) as a color developer. Paragraph [0024] discloses a list of sensitizers which includes stearamide, 1,2-diphenoxyethane and 1,2-di-(3-methylphenoxy)ethane, among a variety of other compounds.

The document DE 10 2004 004 204 A1 relates, according to its independent claim 1, to a heat-sensitive recording material having a substrate and a heat-sensitive recording layer containing a sensitizer, pigment, binder, at least one color former (ie dye precursor) and a phenolic and at least one further organic color developer, the phenolic color developer is selected from the group of bis(hydroxyphenyl) compounds and at least one of the other color developers is a urea-urethane compound.

The document DE 35 44 758 C2 according to its independent claim 1 relates to a paper coating composition containing an acetoacetyl group-containing polyvinyl alcohol resin.

The document DE 36 36 222 A1 according to its independent claim 1, relates to a heat-sensitive paper set capable of developing a black image with excellent oil and light fastness.

The document WO 98/43824 A1 relates, according to its independent claim 1, to a heat-sensitive recording sheet comprising a substrate, a heat-sensitive recording layer containing color formers (ie dye precursors) and color acceptors, and a pigment-containing protective layer formed on the recording layer and containing a mixture of water-soluble and water-insoluble binder.

The document DE 10 2008 007 596 A1 according to its independent claim 1 relates to a method for the production of a recording material comprising the step of applying a coating which contains components which protect a coating applied in a previous step from being adversely affected and which contains a self-crosslinking polyvinyl alcohol in combination with a polyurethane resin.

The document DE 102 41 903 A1 according to its independent claim 1 relates to a method for producing a sheet-shaped, laminated heat-sensitive recording material, the recording material comprising at least a substrate, a heat-sensitive recording layer containing color formers (ie dye precursors) and color acceptors, and a protective layer formed on the recording layer.

The document DE 11 2015 000 518 T5 (Mitsubishi Paper Mills Limited ) according to its independent claim 1 relates to a thermal recording material with a heat-sensitive recording layer on a paper base, which contains a colorless or slightly colored color base and a developer which reacts with the color base on heating and converts the color base into its colored form, the paper base having a Mass fraction of 0.25 to 1.0% of a neutral rosin sizing agent based on pulp solids in combination with calcium carbonate and aluminum sulfate, the developer having a phenylureido group in its molecule. In some embodiments, the developer is N-[2-(3-phenylureido)phenyl]benzenesulfonamide. Various compounds are listed as suitable sensitizers; in addition to a large number of other compounds, the list also includes stearic acid monoamide, 1,2-diphenoxyethane and 1,2-bis(3-methylphenoxy)ethane.

JP 2012-504442 (Hatsume Suishin Kyokai Kokai Giho; published November 22, 2012 ) discloses a RECORDING MATERIAL PRODUCED USING NON PHENOL COMPOUND (English translation of the title according to the translation from the German opposition proceedings concerning the patent DE 10 2014 107 567 B3 ).

The document EP 3 000 608 A1 according to its independent claim 1 relates to a heat-sensitive recording material comprising a heat-sensitive recording layer on a support, the heat-sensitive recording layer containing at least one leuco dye and a sulfonamide compound as developer. According to alternative (b) of claim 1, the heat-sensitive recording layer may further contain a saturated fatty acid amide. According to claim 5, the heat-sensitive recording material may further contain a sensitizer.

The document DE 10 2015 104 306 A1 according to its independent claim 1, relates to a heat-sensitive recording material comprising a carrier substrate and a heat-sensitive color-forming layer containing at least one color former and at least one phenol-free color developer.

With the aim of improving heat-sensitive recording materials, especially when used as tickets or lottery tickets, with regard to their resistance to environmental influences such as heat, moisture and chemicals, there is a constant interest in understanding the underlying chemistry and the manufacturing technology for producing such recording materials and the underlying them further develop the underlying coating compositions and recording layers.

In particular, there is a constant need for further heat-sensitive recording materials for a wide variety of uses, these being able to be produced at low production costs on account of high sales volumes in a fiercely contested market and therefore must have a simple structure. A particular challenge is that heat-sensitive recording materials in their typical uses as a ticket, entrance ticket, travel ticket, parking ticket and the like. are exposed to a variety of different environmental influences, such as moisture, heat or chemicals.

Thus, during normal use, heat-sensitive recording materials can come into contact with a large number of different substances which can affect the durability of the thermal printout. In addition to water and organic solvents, these also include fats and oils, which are contained, for example, in hand care products and can be transferred to the heat-sensitive recording material when it is touched. It is therefore also a grease resistance of the recording material required so that the recorded image in contact with oily or greasy substances such. B. with fat components in hair care products, hand creams or skin deposits, is not destroyed.

In addition to resistance to chemicals that can come into contact with the heat-sensitive recording materials, heat-sensitive recording materials must also have high resistance to thermal influences. On the one hand, it should be possible to print the heat-sensitive recording material in an energy-saving and easy way, for example in order to use less energy in mobile applications. On the other hand, the printed image should remain after printing, and exposure to heat should not fade the printed image, nor should the unprinted background discolor, rendering the print unreadable. For example, thermal resistance is extremely relevant for parking tickets that are stored behind the windscreen after printing and are therefore exposed to high temperatures and direct sunlight in summer.

The long-term stability of the heat-sensitive recording material is also very important for tickets such as concert tickets or plane tickets, which are often issued a long time in advance, or for receipts or proof of purchase, which are required as proof of purchase over a long guarantee period.

Especially against the background of the potential toxicity of (bis)phenolic chemicals, the development of new, heat-sensitive recording materials should also be considered the use of (bis)phenolic color developers is completely or completely dispensed with and instead the use of (bis)phenol-free color developers, such as NKK, is preferred.

Our own investigations have shown that the use of NKK as a color developer within coating compositions and heat-sensitive recording layers of heat-sensitive recording materials compared to conventional (bis)phenol-containing color developers disadvantageously leads to a reduction in the grease resistance of the resulting heat-sensitive recording material. According to our own investigations, the use of NKK led to a greatly accelerated color redevelopment after direct contact of the heat-sensitive recording material (a thermal paper) with fats and oils, which severely restricts the applications of NKK-containing, heat-sensitive recording materials without a top coat and thus at the expense of a simple structure of such recording materials.

als Farbentwickler umfassende Beschichtungszusammensetzung zur Herstellung eines wärmeempfindlichen Aufzeichnungsmaterials sowie eine entsprechende wärmeempfindliche Aufzeichnungsschicht anzugeben, welche sich durch eine nur langsame Farbrückentwicklung nach dem direkten Kontakt des mit einem aufgezeichneten Bild versehenen (bedruckten) Aufzeichnungsmaterials mit Fetten und Ölen auszeichnet. Es war eine weitere Aufgabe, ein entsprechendes wärmeempfindliches Aufzeichnungsmaterial sowie Verfahren zu dessen Herstellung anzugeben.It was a primary object of the present invention to provide an N-[2-(3-phenylureido)phenyl]benzenesulfonamide (NKK) of the formula

to specify a coating composition comprising a color developer for the production of a heat-sensitive recording material and a corresponding heat-sensitive recording layer, which is characterized by only slow redevelopment of color after direct contact of the (printed) recording material provided with a recorded image with fats and oils. A further object was to specify a corresponding heat-sensitive recording material and a method for its production.

The heat-sensitive recording material to be specified should also have good thermal responsiveness, high background whiteness and high image density, and improved resistance to moisture or heat of the recording made thereon by the action of heat; this applies correspondingly to the coating composition to be specified and the recording layer to be specified. The heat-sensitive recording materials should preferably exhibit low long-term aging even at high temperatures (40 to 60° C.) and possibly high atmospheric humidity.

Further objects result from the following description and the patent claims.

The subject matter of the invention is defined in the appended claims and in the description below.

• einen oder mehrere Farbentwickler, wobei der eine oder zumindest einer der mehreren Farbentwickler eine Verbindung der Formel (I) ist
  
• einen oder mehrere Farbstoffvorläufer,
• ein oder mehrere Fettsäureamide mit jeweils einer Zahl von C-Atomen im Bereich von 16 bis 24,
• als Sensibilisator ein oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan (DPE) und Ethylenglycol-m-tolyl-ether (EGTE),

wobei vorzugsweise das Verhältnis der Gesamtmasse von Fettsäureamiden mit einer Zahl von C-Atomen im Bereich von 16 bis 24 zu der Gesamtmasse von Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 4:1 bis 1,2:1 liegt.According to a first aspect of the invention, the above-mentioned primary object is achieved by a coating composition for the production of a heat-sensitive recording material or by a heat-sensitive recording layer, comprising

• one or more color developers, wherein the one or at least one of the more color developers is a compound of formula (I).
  
• one or more dye precursors,
• one or more fatty acid amides each having a number of carbon atoms in the range from 16 to 24,
• as a sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE),

preferably the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or of the heat-sensitive recording layer ranges from 4:1 to 1.2:1.

As indicated above, the compound of formula (I) is NKK, i.e. N-[2-(3-phenylureido)phenyl]benzenesulfonamide.

• ein Trägersubstrat,
  und
• eine erfindungsgemäße wärmeempfindliche Aufzeichnungsschicht (wie vorstehend und nachfolgend bzw. in den Ansprüchen definiert).

The invention also relates to a corresponding heat-sensitive recording material, comprising

• a carrier substrate,
  and
• a heat-sensitive recording layer according to the invention (as defined above and below or in the claims).

• einen oder mehrere Farbentwickler, wobei der eine oder zumindest einer der mehreren Farbentwickler eine Verbindung der Formel (I) ist
  
• einen oder mehrere Farbstoffvorläufer,
  und
• als Sensibilisator ein oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan (DPE) und Ethylenglycol-m-tolyl-ether (EGTE),

wobei vorzugsweise das Verhältnis der Gesamtmasse von Fettsäureamiden mit einer Zahl von C-Atomen im Bereich von 16 bis 24 zu der Gesamtmasse von Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether in dem wärmeempfindlichen Aufzeichnungsmaterial bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 4:1 bis 1,2:1 liegt.The invention solves other of the stated tasks by using a fatty acid amide having a number of carbon atoms in the range from 16 to 24 or a mixture of several fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably by using Octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide, for increasing the grease resistance of a heat-sensitive recording material or a heat-sensitive recording layer

• one or more color developers, wherein the one or at least one of the more color developers is a compound of formula (I).
  
• one or more dye precursors,
  and
• as a sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE),

preferably the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the heat-sensitive recording material or .of the heat-sensitive recording layer ranges from 4:1 to 1.2:1.

• Bereitstellen oder Herstellen
  • eines Trägersubstrats mit darauf angeordneter Zwischenschicht sowie
  • einer erfindungsgemäßen Beschichtungszusammensetzung (wie vorstehend und nachfolgend bzw. in den Ansprüchen definiert),
• Aufbringen der Beschichtungszusammensetzung auf die Zwischenschicht,
• Trocknen der aufgebrachten Beschichtungszusammensetzung, so dass eine wärmeempfindliche Aufzeichnungsschicht resultiert, die gemeinsam mit dem Trägersubstrat und der Zwischenschicht in dem wärmeempfindlichen Aufzeichnungsmaterial vorliegt.

Preference is given to a use according to the invention in which the fatty acid amide used has a number of carbon atoms in the range from 16 to 24 or the mixture used of several fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably octadecanoic acid amide and/or N-(Hydroxymethyl)octadecanamide, remains in the solid state during the thermal printing process. It therefore does not melt and therefore does not act as a sensitizer. The invention also solves other of the specified objects by a method for producing a heat-sensitive recording material according to the invention (as defined above and below or in the claims),
with the following steps:

• Deploy or Manufacture
  • a carrier substrate with an intermediate layer arranged thereon and
  • a coating composition according to the invention (as defined above and below or in the claims),
• applying the coating composition to the intermediate layer,
• Drying the applied coating composition, so that a heat-sensitive recording layer results, which is present together with the carrier substrate and the intermediate layer in the heat-sensitive recording material.

The compound of formula (I) is already known and is, for example, in EP 2 923 851 A1 or the above DE 10 2014 107 567 B3 disclosed. It corresponds to the connection already referred to as NKK in the previous text.

(also NKK, d.h. N-[2-(3-Phenylureido)phenyl]benzolsulfonamid)

• und zudem einen oder mehrere Farbstoffvorläufer umfasst, eine besonders und unerwartet hohe Fettbeständigkeit besitzt, wenn in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht gleichzeitig
• ein oder mehrere Fettsäureamide mit jeweils einer Zahl von C-Atomen im Bereich von 16 bis 24
  und
• als Sensibilisator ein oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan (DPE) und Ethylenglycol-m-tolyl-ether (EGTE)
• vorhanden sind, und vorzugsweise
• das Verhältnis der Gesamtmasse von Fettsäureamiden mit einer Zahl von C-Atomen im Bereich von 16 bis 24 zu der Gesamtmasse von Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 4:1 bis 1,2:1 liegt.

The invention is based on the surprising experimental finding that a coating composition for producing a heat-sensitive recording material or a corresponding heat-sensitive recording layer which contains a compound of the formula (I) as the color developer

(i.e. NKK, ie N-[2-(3-phenylureido)phenyl]benzenesulfonamide)

• and also comprises one or more dye precursors, has a particularly and unexpectedly high grease resistance when in the coating composition and the heat-sensitive recording layer at the same time
• one or more fatty acid amides each having a number of carbon atoms in the range from 16 to 24
  and
• as a sensitizer one or more compounds selected from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE)
• are present, and preferably
• the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition and the heat-sensitive one, respectively recording layer ranges from 4:1 to 1.2:1.

The increased fat resistance can presumably be attributed to a synergistic effect between the fatty acid amide and the sensitizer used. At least our own experimental investigations have shown that in coating compositions according to the invention, which contain either octadecanoic acid amide (stearamide) or N-(hydroxymethyl)octadecanoic acid amide and, as a sensitizer, either 1,2-diphenoxyethane (DPE) or ethylene glycol m-tolyl ether (EGTE) contained, the total mass of octadecanamide or N-(hydroxymethyl)octadecanamide and DPE and EGTE were kept constant in each case, but the mass ratio was varied, the experimentally determined grease resistance was not only due to the performance of the individual components octadecanoic acid amide or N-(hydroxymethyl)octadecanoic acid amide and DPE or EGTE. On the contrary, it was surprisingly found that the grease resistance in the mixtures was overadditive. Our own investigations into grease resistance were carried out according to a test method given below under the heading "Determination of the resistance of heat-sensitive recording materials to lanolin".

Commercially available lanolin (as used in our grease resistance studies) is a mixture obtained by melting together 65 parts by weight wool wax, 20 parts by weight water and 15 parts by weight thick paraffin. Wool wax (wool fat, Adeps Lanae, INCI designation: lanolin, E 913) is the secretion of the sebaceous glands of sheep. It is obtained by extracting sheep fleece with isopropanol. The name lanolin derives from the Latin lana = wool and oleum = oil.

1. 1. Die Verbindung der Formel (I)
   
   wird im vorliegenden Text als NKK bzw. als N-[2-(3-phenylureido)phenyl]benzolsulfonamid bezeichnet; dieselbe Verbindung wird in DE 10 2014 107 567 B3 ebenfalls als N-[2-(3-phenylureido)phenyl]benzolsulfonamid, und als Phenylureido-phenylbenzolsulfonamid bezeichnet. In der noch nicht veröffentlichten Anmeldung PCT/EP2017/074875 werden für dieselbe Substanz die Bezeichnungen N-{2-[(Phenylcarbamoyl)amino]phenyl}benzolsulfonamid und N-[2-(3-Phenylureido)phenyl]benzolsulfonamid verwendet. Auch Verbindungen mit der CAS-Nummer 215917-77-4 bzw. der EG-Nr. 806-543-7 werden als NKK bezeichnet.
2. 2. Ethylenglycol-m-tolyl-ether wird im vorliegenden Text auch als EGTE bezeichnet; dieselbe Verbindung wird in DE 10 2014 107 567 B3 als 1,2-Di-(3-methylphen-oxy)ethan bezeichnet. In der Anmeldung PCT/EP2017/074875 werden für dieselbe Substanz die Bezeichnungen 1,2-Di(m-methylphenoxy)ethan und 1,2-Bis(3-methyl-phenoxy)ethan verwendet. Auch die Verbindung mit der CAS-Nummer 54914-85-1 wird als Ethylenglycol-m-tolyl-ether bezeichnet.
3. 3. Octadecansäureamid wird in DE 10 2014 107 567 B3 als Stearamid oder als Stearinsäureamid bezeichnet. In der Anmeldung PCT/EP2017/074875 wird für dieselbe Substanz ebenfalls die Bezeichnung Stearamid verwendet. Auch die Verbindung mit der CAS-Nummer 124-26-5 wird als Octadecansäureamid bezeichnet.
4. 4. Benzyl-2-naphthylether wird im vorliegenden Text auch als Benzylnaphthylether bezeichnet; dieselbe Verbindung wird in DE 10 2014 107 567 B3 als 2-Benzyloxynaphthalin bezeichnet. Auch die Verbindung mit der CAS-Nummer 613-62-7 wird als Benzyl-2-naphthylether bezeichnet.
5. 5. Die Substanzklasse der Farbstoffvorläufer wird in DE 10 2014 107 567 B3 als Farbbildner bezeichnet. In der Anmeldung PCT/EP2017/074875 wird für dieselbe Substanzklasse sowohl die Bezeichnung Farbstoffvorläufer als auch die Bezeichnung Farbbildner verwendet.
6. 6. Die Substanzklasse der Sensibilisatoren wird in DE 10 2014 107 567 B3 als Sensibilisierungsmittel bezeichnet.

In the present text - as in a large number of documents from the prior art - a number of terms which are synonymous with one another and have identical content are used for the same substances in each case. Below, for a total of six substances or substance classes, it is explained which synonymous designations are used within the scope of the present text and in documents from the prior art.

1. 1. The compound of formula (I)
   
   referred to herein as NKK or as N-[2-(3-phenylureido)phenyl]benzenesulfonamide; the same compound is in DE 10 2014 107 567 B3 also referred to as N-[2-(3-phenylureido)phenyl]benzenesulfonamide, and as phenylureido-phenylbenzenesulfonamide. In the not yet published application PCT/EP2017/074875 the names N-{2-[(phenylcarbamoyl)amino]phenyl}benzenesulfonamide are used for the same substance and N-[2-(3-phenylureido)phenyl]benzenesulfonamide is used. Also connections with CAS number 215917-77-4 or the EC no. 806-543-7 are referred to as NKK.
2. 2. Ethylene glycol m-tolyl ether is also referred to as EGTE in this text; the same compound is in DE 10 2014 107 567 B3 referred to as 1,2-di-(3-methylphenoxy)ethane. In the registration PCT/EP2017/074875 the terms 1,2-di(m-methylphenoxy)ethane and 1,2-bis(3-methylphenoxy)ethane are used for the same substance. Also the connection with CAS number 54914-85-1 is referred to as ethylene glycol m-tolyl ether.
3. 3. Octadecanoic acid amide is used in DE 10 2014 107 567 B3 referred to as stearamide or as stearic acid amide. In the registration PCT/EP2017/074875 the term stearamide is also used for the same substance. Also the connection with CAS number 124-26-5 is referred to as octadecanoic acid amide.
4. 4. Benzyl-2-naphthyl ether is also referred to herein as benzyl naphthyl ether; the same compound is in DE 10 2014 107 567 B3 referred to as 2-benzyloxynaphthalene. Also the connection with CAS number 613-62-7 is referred to as benzyl 2-naphthyl ether.
5. 5. The substance class of the dye precursors is in DE 10 2014 107 567 B3 referred to as a color former. In the registration PCT/EP2017/074875 Both the designation dye precursor and the designation color former are used for the same substance class.
6. 6. The substance class of sensitizers is in DE 10 2014 107 567 B3 referred to as a sensitizer.

In the document mentioned above DE 10 2014 107 567 B3 there are no indications that the fatty acid amide stearamide (octadecanoic acid amide) used there could interact in a synergistic manner with one or more of the other sensitizers (sensitizers) specified in said document. In view of this fact, the technical effects that can be achieved with the present invention and the findings on which the invention is based are particularly surprising.

• weitere Sensibilisatoren,
• Pigmente,
• Dispergiermittel,
• Antioxidationsmittel,
• Trennmittel,
• Entschäumer,
• Lichtstabilisatoren,
  und
• Aufheller.

A coating composition or a heat-sensitive recording layer according to the invention (as defined above and in the claims) preferably comprises one or more components from the group consisting of

• other sensitizers,
• pigments,
• dispersant,
• antioxidant,
• release agent,
• defoamers,
• light stabilizers,
  and
• brightener.

In any case, a coating composition or heat-sensitive recording layer according to the invention comprises a sensitizer, namely at least one or more compounds from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE). The one or more fatty acid amides present according to the invention, each having a number of carbon atoms in the range from 16 to 24, are also understood by some experts as sensitizers. In addition, however, one or more further sensitizers are preferably present.

A sensitizer in a heat-sensitive recording layer is first melted during application of heat during printing, and the melted sensitizer dissolves the coexisting color formers and color developers and/or lowers the melting temperature of the color formers and color developers to bring about a color developing reaction. The sensitizer does not take part in the color development reaction itself.

A "further sensitizer" is understood to mean substances which (also) serve to set the melting temperature (color development temperature) of the heat-sensitive recording layer and with which a melting temperature of <100° C., preferably in the range from about 70 to 80° C., is set without the sensitizers themselves being involved in the color development reaction. Preferred further sensitizers are, for example, fatty acid salts, fatty acid esters and fatty acid amides (eg zinc stearate, palmitic acid amide, oleic acid amide, lauric acid amide, ethylene and methylenebisstearic acid amide, methylolstearic acid amide), naphthalene derivatives, biphenyl derivatives, phthalates and terephthalates.

A coating composition according to the invention or a heat-sensitive recording layer according to the invention is particularly preferred, the further sensitizer being selected from the group consisting of 2-(2H-benzotriazol-2-yl)-p-cresol, 2,2'-bis(4-methoxyphenoxy )diethyl ether, 4,4'-diallyloxydiphenylsulfone, 4-acetylacetophenone, 4-benzylbiphenyl, acetoacetic anilide, benzyl 2-naphthyl ether, benzyl naphthyl ether, benzyl 4-(benzyloxy)benzoate, benzylparaben, bis(4-chlorobenzyl)oxalate ester, bis(4 -methoxyphenyl) ether, dibenzyl oxalate, dibenzyl terephthalate, dimethyl terephthalate, dimethyl sulfone, diphenyl adipate, diphenyl sulfone, ethylenebisstearic acid amide, fatty acid anilides, m-terpenyl, N-methylol stearamide, N-stearyl urea, N-stearyl stearic acid amide, p-benzylbiphenyl, phenylbenzene sulfonate ester, salicylic acid anilide and α,α'- Diphenoxyxylene, with benzyl naphthyl ether and diphenyl sulfone being particularly preferred.

Also preferred as further sensitizers for use in a coating composition according to the invention or in a heat-sensitive recording layer according to the invention are the sensitizers that are described in paragraphs [0059] to [0061] of EP 2 923 851 A1 are revealed. The use of one or more further sensitizers is particularly preferred, with the respective sensitizer having a melting point in the range from 60.degree. C. to 140.degree. C., preferably a melting point in the range from 60.degree. C. to 100.degree.

In addition to sensitizers, a coating composition according to the invention or a heat-sensitive recording layer according to the invention preferably also comprises one or more components from the group consisting of pigments, dispersants, antioxidants, release agents, defoamers, light stabilizers and brighteners. Each of these components is preferably used in an amount with a mass fraction of 0.01 to 15%, in particular - with the exception of defoamer - 0.1 to 15%, preferably 1 to 10%, based on the total solids content of the coating composition according to the invention or the heat-sensitive recording layer. If an antifoam is used in a coating composition according to the invention or in a heat-sensitive recording layer according to the invention, the antifoam is preferably present in amounts with a mass fraction of 0.03 to 0.05% present based on the total solids content of the coating composition according to the invention or the heat-sensitive recording layer according to the invention.

A heat-sensitive recording layer according to the invention can of course be shielded by the arrangement of a covering protective layer in such a way that protection from external influences takes place. However, the provision of such a protective layer is generally not necessary within the scope of the present invention and is therefore also not preferred. The coating composition according to the invention and the heat-sensitive recording layer according to the invention are already equipped due to the selection and combination of fatty acid amides, each with a number of carbon atoms in the range from 16 to 24, with a sensitizer from the group consisting of DPE and EGTE that the resistance of a Thermal printout on a heat-sensitive recording layer according to the invention (which can in particular be part of a heat-sensitive recording material according to the invention) to substances selected from the group consisting of water, alcohols, fats, oils and mixtures thereof, in particular the resistance to fats and oils is excellent even without a protective layer.

A coating composition according to the invention or a heat-sensitive recording layer according to the invention comprises a compound of the formula (I) (ie NKK). A compound of formula (I) is already known and is, for example, in EP 2 923 851 A1 described. However, it has been shown that the compound of formula (I) can exist in two different crystalline forms. Both crystalline forms have different physical properties, which can influence the properties of the coating composition according to the invention, the heat-sensitive recording layer according to the invention and the heat-sensitive recording material according to the invention.

A first crystalline form of the compounds of formula (I) has a melting point of about 158°C, while a second crystalline form of the compounds of formula (I) has a melting point of 175°C. In connection with heat-sensitive recording materials, only the compound with the formula (I), which is the crystalline form with a melting point of approx. 158 °C, has so far been described in the literature (cf. for example EP 2 923 851 A1 Paragraph [0084]). Neither the production nor the use of the crystalline form of the compounds of the formula (I) with a melting point of about 175° C. used according to the invention are in the previously published literature, see however the application PCT/EP2017/074875 . Accordingly, it must be assumed that, according to the published prior art, the crystalline form of the compound of formula (I) with a melting point of approx. 158° C. was always used, even if the melting point is not explicitly mentioned in the relevant document. The crystalline form of the compound of the formula (I) used according to the invention and having a melting point of 175° C. has also recently become commercially available.

According to the invention, preference is therefore given to a coating composition according to the invention, a heat-sensitive recording layer according to the invention and a heat-sensitive recording material according to the invention, the crystalline form of the compound of the formula (I) having a (preferably endothermic) transition at a temperature between 170° C. and 178° C., preferably between 173° C. and 177° C., particularly preferably between 174° C. and 176° C., determined using differential scanning calorimetry (DKK) at a heating rate of 10 K/min.

Both crystalline forms of the compounds of formula (I) can also be distinguished from one another in the IR absorption spectrum. An absorption band in the IR spectrum at 3401±20 cm ^-1 is particularly characteristic of the crystalline form of the compounds of the formula (I) used according to the invention. In the crystalline form of the compounds of the formula (I), which has a melting point of about 158° C., this band is not present, but rather a band at 3322 and 3229 cm ^-1 .

According to the invention, preference is given to a heat-sensitive recording material in which the crystalline form of the compound of the formula (I) has absorption bands at 689±10 cm ^-1 , 731±10 cm ^-1 , 1653±10 cm ^-1 , 3364±20 cm -1 in the IR spectrum ^{. 1} and 3401 ± 20 cm ^-1 .

According to the invention, preference is given to a coating composition according to the invention, a heat-sensitive recording layer according to the invention, or a heat-sensitive recording material according to the invention, in which the IR absorption spectrum of the crystalline form of the compound of the formula (I) essentially corresponds to that in Fig. 1a ), 2a) and/or 3a) corresponds to the IR absorption spectrum shown.

Both crystalline forms of the compounds of the formula (I) can also be distinguished from one another in the X-ray powder diffractogram. A coating composition according to the invention is preferred according to the invention Heat-sensitive recording layer and a heat-sensitive recording material according to the invention, the crystalline form of the compound of the formula (I) having an X-ray powder diffractogram with reflections at °20 values of 10.00 ± 0.20, 11.00 ± 0.20, 12.40 ± 0 .20, 13.80 ± 0.20 and 15.00 ± 0.20.

Preference is given according to the invention to a coating composition according to the invention, a heat-sensitive recording layer according to the invention and a heat-sensitive recording material according to the invention, the crystalline form of the compound of the formula (I) having an X-ray powder diffractogram which essentially corresponds to that in Figure 4b ) X-ray powder diffractogram shown.

In our own investigations, we mainly worked with a crystalline form of the compound of the formula (I), which has an absorption band at 3401 ± 20 cm ^-1 in the IR spectrum and has a melting point of 175° C. or has a transition at a temperature between 170 °C and 178 °C (determined using differential scanning calorimetry (DKK) at a heating rate of 10 K/min) or in the X-ray powder diffractogram diffraction reflections at °2θ values of at least 10.00 ± 0.20, 11.00 ± 0.20, 12.40 ± 0.20, 13.80 ± 0.20 and 15.00 ± 0.20. The use of such a compound of formula (I) is somewhat preferred for all aspects of the present invention. A coating composition according to the invention and a heat-sensitive recording layer according to the invention preferably comprise pigments. The pigments can be organic pigments, inorganic pigments or a mixture of organic pigments and inorganic pigments.

A coating composition or a heat-sensitive recording layer according to the invention (as defined above, preferably as referred to above as preferred) is preferred, wherein the one or more fatty acid amides having a number of carbon atoms in the range from 16 to 24 is octadecanoic acid amide (stearic acid amide; stearamide) is. Octadecanoic acid amide is chemically compatible with the compound of formula (I) (NKK) and sensitizers from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE). As a pure substance, octadecanoic acid amide has a melting point of 109 °C and is therefore an excellent sensitizer (cf. the corresponding use according to DE 10 2014 107 567 B3 ); it does not itself take part in the color development reaction. The ability of octadecanoic acid amide (and other fatty acid amides with a number of carbon atoms in the range from 16 to 24) to have synergistic interactions with DPE and/or EGTE was previously lacking not known in the prior art. The use of N-(hydroxymethyl)octadecanoic acid amide as the fatty acid amide is also preferred.

A coating composition according to the invention and a heat-sensitive recording layer according to the invention are preferred in which octadecanoic acid amide or N-(hydroxymethyl)octadecanoic acid amide is used in combination with DPE and/or EGTE such that the color reaction can take place even at an exposure temperature (color development temperature) of 100° C . Because octadecanoic acid amide has a melting point of 109 °C and N-(hydroxymethyl)octadecanoic acid amide has a melting point of > 107 °C, but EGTE has a melting point in the range of 96 to 100 °C and diphenoxyethane has a melting point in the range of 94 to 96 °C, In coating compositions according to the invention or recording layers adjusted in this way, the actual sensitizing effect is primarily due to the presence of DPE or EGTE. In a corresponding configuration, the primary task of the octadecanoic acid amide is to achieve or ensure the desired fat resistance through synergistic interaction with DPE and/or EGTE. The desired fat resistance is achieved or ensured in a similar manner in a further embodiment according to the invention through the synergistic interaction of N-(hydroxymethyl)octadecanoic acid amide with DPE and/or EGTE.

A coating composition according to the invention or a heat-sensitive recording layer according to the invention is preferred, the ratio of the mass of the compound of the formula (I) to the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 (preferably octadecanoic acid amide) in the coating composition or .of the heat-sensitive recording layer is in the range of 1.2:1 to 4:1. In preferred embodiments, the mass of NKK used therefore at least slightly (1.2:1) outweighs the total mass of fatty acid amides used. Too large an excess of NKK (mass ratio greater than 4:1) is no longer advantageous because the positive properties and effects of the fatty acid amide (preferably octadecanoic acid amide) then no longer come into play in the desired manner.

As already stated, a preferred coating composition or heat-sensitive recording layer according to the invention comprises octadecanoic acid amide (as one or as one of several fatty acid amides each having a number of carbon atoms in the range from 16 to 24). In such preferred coating compositions or In heat-sensitive recording layers, the ratio of the mass of the compound of formula (I) (NKK) to the mass of octadecanoic acid amide in the coating composition or in the heat-sensitive recording layer is in the range from 1.2:1 to 4:1.

A preferred coating composition according to the invention or a heat-sensitive recording layer according to the invention (as defined above, preferably as described above as preferred) is characterized in that the ratio of the total mass of fatty acid amides with a number from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE) in the coating composition or the heat-sensitive recording layer is in the range from 4:1 to 1.2:1, preferably in the range from 1.5: 1 to 1.2:1. Such ratios of the total amount of fatty acid amides with a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of DPE and EGTE are particularly preferred because they achieve particularly high grease resistance and a low color development temperature at the same time will. A low color development temperature is advantageous because no unnecessarily large amounts of energy are required to produce a color change. A high grease resistance increases the practical benefit and makes corresponding heat-sensitive recording materials suitable for certain applications in the first place. The fatty acid amides (preferably octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide) and DPE and/or EGTE preferably act synergistically together, so that the amount of fatty acid amides (preferably: octadecanoic acid amide) required to achieve a given grease resistance is comparatively low , compared to a situation where neither DPE nor EGTE are present. This dependence of the fat resistance and color development temperature parameters, which are decisive for practical use, on the mixing ratio of the components fatty acid amides (preferably octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide) and DPE and/or EGTE is surprising in view of the prior art. If, in a coating composition according to the invention or a corresponding heat-sensitive recording layer, the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of DPE and/or EGTE is too high, i.e. for example a ratio of >4 , it is no longer guaranteed in every case that the color development temperature is as low as desired. On the other hand, if a ratio that is too low is selected, it is no longer guaranteed in each individual case that the grease resistance meets the requirements.

• einen oder mehrere Farbentwickler, wobei der eine oder zumindest einer der mehreren Farbentwickler eine Verbindung der Formel (I) ist
  
• einen oder mehrere Farbstoffvorläufer,
• Octadecansäureamid und/oder N-(Hydroxymethyl)octadecansäureamid,
• als Sensibilisator 1,2-Diphenoxyethan (DPE) und/oder Ethylenglycol-m-tolyl-ether (EGTE),

• wobei das Verhältnis der Masse der Verbindung der Formel (I) zu der Masse von Octadecansäureamid in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 1,2:1 bis 4:1 liegt
  und
• wobei das Verhältnis der Gesamtmasse von Octadecansäureamid und N-(Hydroxymethyl)octadecansäureamid zu der Gesamtmasse von 1,2-Diphenoxyethan (DPE) und Ethylenglycol-m-tolyl-ether (EGTE)
• in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 1,5:1 bis 1,2:1 liegt.

Particularly preferred is a coating composition according to the invention or a heat-sensitive recording layer according to the invention as defined above (preferably as referred to above as preferred) comprising

• one or more color developers, wherein the one or at least one of the more color developers is a compound of formula (I).
  
• one or more dye precursors,
• octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide,
• as a sensitizer 1,2-diphenoxyethane (DPE) and/or ethylene glycol m-tolyl ether (EGTE),

• wherein the ratio of the mass of the compound of formula (I) to the mass of octadecanoic acid amide in the coating composition or the heat-sensitive recording layer is in the range from 1.2:1 to 4:1
  and
• wherein the ratio of the total mass of octadecanoic acid amide and N-(hydroxymethyl)octadecanoic acid amide to the total mass of 1,2-diphenoxyethane (DPE) and ethylene glycol m-tolyl ether (EGTE)
• in the coating composition or the heat-sensitive recording layer is in the range from 1.5:1 to 1.2:1.

Such a coating composition according to the invention or such a heat-sensitive recording layer according to the invention combines the advantages discussed above and is therefore in particular particularly grease-resistant and has a comparatively low color development temperature without the need for particularly high amounts of octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide in order to achieve grease resistance.

A coating composition according to the invention or a heat-sensitive recording layer according to the invention (as defined above, preferably as described above as preferred) preferably comprises 1,2-diphenoxyethane (DPE) or a mixture of 1,2-diphenoxyethane (DPE) and ethylene glycol-m- tolyl ether (EGTE). DPE is therefore present in such preferred coating compositions or heat-sensitive recording layers. With regard to preferred quantitative ratios, reference is made to the statements made above.

• 8 bis 30 prozentuale Massenanteile (Massenanteile ausgedrückt in %) einer Gesamtmenge von einem oder mehreren Farbentwicklern, wobei der eine oder zumindest einer der mehreren Farbentwickler eine Verbindung der Formel (I) ist
  
  vorzugsweise 8 bis 30 prozentuale Massenanteile des Farbentwicklers der Formel (I), jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand
  und/oder
• 4 bis 16 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Farbstoffvorläufern, bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand
  und/oder
• 2,4 bis 34 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Fettsäureamiden mit jeweils einer Zahl von C-Atomen im Bereich von 16 bis 24, vorzugsweise 2,4 bis 34 prozentuale Massenanteile einer Gesamtmenge von einer oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus Octadecansäureamid und N-(Hydroxymethyl)octadecansäureamid, besonders vorzugsweise 2,4 bis 34 prozentuale Massenanteile Octadecansäureamid, jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand
  und/oder
• als Sensibilisator 2 bis 8,5 prozentuale Massenanteile einer Gesamtmenge von einer oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether, vorzugsweise 2 bis 8,5 prozentuale Massenanteile 1,2-Diphenoxyethan oder 2 bis 8,5 prozentuale Massenanteile einer Mischung von 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether, jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand
  und/oder
• 6 bis 24 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Bindemitteln, vorzugsweise 6 bis 24 prozentuale Massenanteile Polyvinylalkohol (PVA) (als besonders bevorzugtem Bindemittel), jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand
  und/oder
• 25 bis 55 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Pigmenten, bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand.

Preference is given to a coating composition according to the invention or a heat-sensitive recording layer according to the invention as defined above (preferably as referred to above as preferred), based on the oven-dried state comprising

• 8 to 30 wt% (wt %) of a total of one or more color developers, wherein the one or at least one of the more color developers is a compound of formula (I).
  
  preferably 8 to 30 mass percentages of the color developer of the formula (I), in each case based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state
  and or
• 4 to 16 wt% of a total amount of one or more dye precursors based on the total amount of the oven-dried coating composition or the oven-dried heat-sensitive recording layer
  and or
• 2.4 to 34 percent by mass of a total amount of one or more fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably 2.4 to 34 percent by mass of a total amount of one or more compounds selected from the group consisting of Octadecanamide and N-(hydroxymethyl)octadecanamide, particularly preferably 2.4 to 34 percentage parts by mass of octadecanamide, in each case based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state
  and or
• as a sensitizer, 2 to 8.5 wt% of a total of one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether, preferably 2 to 8.5 wt% 1,2-diphenoxyethane or 2 to 8.5 weight percentages of a mixture of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether, each based on the total amount of the oven-dried coating composition or the oven-dried heat-sensitive recording layer
  and or
• 6 to 24 wt% of a total amount of one or more binders, preferably 6 to 24 wt% polyvinyl alcohol (PVA) (as a particularly preferred binder), each based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state
  and or
• 25 to 55 weight percent of a total amount of one or more pigments based on the total amount of the oven-dried coating composition or the oven-dried heat-sensitive recording layer.

• 8 bis 30 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Farbentwicklern, wobei der eine oder zumindest einer der mehreren Farbentwickler eine Verbindung der Formel (I) ist,
  
  vorzugsweise 8 bis 30 prozentuale Massenanteile des Farbentwicklers der Formel (I), jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand,
• 4 bis 16 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Farbstoffvorläufern, bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand,
• 2,4 bis 34 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Fettsäureamiden mit jeweils einer Zahl von C-Atomen im Bereich von 16 bis 24, vorzugsweise 2,4 bis 34 prozentuale Massenanteile einer Gesamtmenge von einer oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus Octadecansäureamid und N-(Hydroxymethyl)octadecansäureamid, besonders vorzugsweise 2,4 bis 34 prozentuale Massenanteile Octadecansäureamid, jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand,
• als Sensibilisator 2 bis 8,5 prozentuale Massenanteile einer Gesamtmenge von einer oder mehr Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether, vorzugsweise 2 bis 8,5 prozentuale Massenanteile 1,2-Diphenoxyethan oder 2 bis 8,5 prozentuale Massenanteile einer Mischung von 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether, jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand,
• 6 bis 24 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Bindemitteln, vorzugsweise 6 bis 24 prozentuale Massenanteile Polyvinylalkohol (PVA), jeweils bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand, und
• 25 bis 55 prozentuale Massenanteile einer Gesamtmenge von einem oder mehreren Pigmenten, bezogen auf die Gesamtmenge der Beschichtungszusammensetzung im ofentrockenen Zustand bzw. der wärmeempfindlichen Aufzeichnungsschicht im ofentrockenen Zustand

mit der Maßgabe, dass für diese besonders bevorzugte Beschichtungszusammensetzung bzw. wärmeempfindliche Aufzeichnungsschicht vorzugsweise das Verhältnis der Gesamtmasse von Fettsäureamiden mit einer Zahl von C-Atomen im Bereich von 16 bis 24 zu der Gesamtmasse von Verbindungen ausgewählt aus der Gruppe bestehend aus 1,2-Diphenoxyethan und Ethylenglycol-m-tolyl-ether in der Beschichtungszusammensetzung bzw. der wärmeempfindlichen Aufzeichnungsschicht im Bereich von 4:1 bis 1,2:1 liegt. Analoge Maßgaben gelten vorzugsweise für Ausgestaltungen einer solchen besonders bevorzugten Beschichtungszusammensetzung bzw. wärmeempfindlichen Aufzeichnungsschicht, die durch Kombination mit bevorzugten Ausgestaltungen bzw. Merkmalen resultieren, wie sie vorstehend oder nachfolgend in den beigefügten Ansprüchen definiert sind.A coating composition according to the invention or a heat-sensitive recording layer according to the invention as defined above (preferably as described above as preferred), based on the oven-dried state, is therefore particularly preferred

• 8 to 30% by mass of a total amount of one or more color developers, wherein the one or at least one of the more color developers is a compound of formula (I),
  
  preferably 8 to 30 percentage parts by mass of the color developer of the formula (I), in each case based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state,
• 4 to 16 mass percentages of a total amount of one or more dye precursors, based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state,
• 2.4 to 34 percent by mass of a total amount of one or more fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably 2.4 to 34 percent by mass of a total amount of one or more compounds selected from the group consisting of Octadecanamide and N-(hydroxymethyl)octadecanamide, particularly preferably 2.4 to 34 percentage parts by mass of octadecanamide, based in each case on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state,
• as a sensitizer, 2 to 8.5 wt% of a total of one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether, preferably 2 to 8.5 wt% 1,2-diphenoxyethane or 2 to 8.5 percentage parts by mass of a mixture of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether, in each case based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state,
• 6 to 24 wt% of a total of one or more binders, preferably 6 to 24 wt% polyvinyl alcohol (PVA), in each case based on the total amount of the coating composition in the oven-dried state or the heat-sensitive recording layer in the oven-dried state, and
• 25 to 55 weight percent of a total amount of one or more pigments based on the total amount of the oven-dried coating composition or the oven-dried heat-sensitive recording layer

with the proviso that for this particularly preferred coating composition or heat-sensitive recording layer, the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition and the heat mode recording layer, respectively, ranges from 4:1 to 1.2:1. Analogous stipulations preferably apply to configurations of such a particularly preferred coating composition or heat-sensitive recording layer which result from a combination with preferred configurations or features as defined above or below in the appended claims.

It should be noted that the statements "relative to the oven-dried state" and "in the oven-dried state" specify that the specified mass fractions of coating composition or heat-sensitive recording layer relate to a measurement carried out on oven-dried material. However, the statements do not mean that only oven-dried materials are defined; Rather, a coating composition or a heat-sensitive recording layer, for example, also falls under the respective definition if it contains significant amounts of liquid (e.g. water) as long as, after oven drying, a corresponding measurement results in total amounts of the components discussed falling within the respective ranges specified .

It is preferred according to the invention if the heat-sensitive recording layer has a Bekk smoothness of 100 to 1200 seconds, preferably 150 to 1100 seconds, determined according to DIN 53107:2016-05 (title: Testing of paper and cardboard - Determination of Bekk smoothness).

As already explained above, the invention also relates to a heat-sensitive recording material, comprising a carrier substrate and a heat-sensitive recording material according to the invention recording layer. In such a heat-sensitive recording material according to the invention, one or more intermediate layers are preferably arranged between the carrier substrate and the heat-sensitive recording layer. Such an intermediate layer preferably contains pigments. The pigments can be organic pigments, inorganic pigments or a mixture of organic pigments and inorganic pigments.

It is preferred according to the invention if the mass per unit area of the intermediate layer is in the range from 5 to 20 g/m ² , preferably in the range from 7 to 12 g/m ² .

If the intermediate layer contains pigments, it is preferred in one embodiment of the invention if the pigments are organic pigments, preferably organic hollow body pigments.

Our own investigations have shown that the incorporation of organic pigments in the intermediate layer is advantageous, since organic pigments have a high ability to reflect heat. Increased thermal reflection of the intermediate layer designed with organic pigments increases the response of the heat-sensitive recording layer to heat, since the radiated heat is at least partially reflected into the heat-sensitive recording layer instead of being conducted to the carrier substrate. As a result, the sensitivity and the resolving power of the heat-sensitive recording material are significantly increased and the printing speed in the thermal printer is also increased. In addition, the energy consumption during the printing process can be reduced, which is particularly advantageous for mobile devices. Hollow body pigments have air inside them, whereby they usually have an even higher heat reflection, and the sensitivity and resolving power of the heat-sensitive recording material can be further increased.

If the intermediate layer contains pigments, it is preferred in an alternative embodiment of the invention if the pigments are inorganic pigments, preferably selected from the list consisting of calcined kaolin, silicon oxide, bentonite, calcium carbonate, aluminum oxide and boehmite .

If inorganic pigments are integrated into the intermediate layer between the recording layer and the substrate, these pigments can absorb the components of the heat-sensitive recording layer that have been liquefied by the heat of the thermal head during the formation of the typeface and thus promote even more reliable and faster functioning of the heat-induced recording.

It is particularly advantageous if the inorganic pigments of the intermediate layer have an oil absorption of at least 80 cm ³ /100 g and even better of 100 cm ³ /100 g, determined according to DIN EN ISO 787-5:1995-10 (Title: General test methods for Pigments and extenders - Part 5: Determination of oil absorption (ISO 787-5:1980); German version EN ISO 787-5:1995). Calcined kaolin has proven particularly useful due to its large absorption reservoir in the cavities. Mixtures of several different types of inorganic pigments are also conceivable.

The selection of the quantitative ratio of organic to inorganic pigments brings about a combination of the effects caused by the two types of pigment. It is particularly advantageous if the pigment mixture consists of a mass fraction of 5 to 30% or better 8 to 20% organic and 95 to 70% or better 92 to 80% inorganic pigment. Pigment mixtures of different organic pigments and/or inorganic pigments are advantageous in individual cases.

According to the invention, preference is given to a heat-sensitive recording material in which the intermediate layer, optionally in addition to the inorganic and/or organic pigments, contains at least one binder, preferably based on a synthetic polymer, with styrene-butadiene latex giving particularly good results. Polyvinyl alcohol (PVA) is another preferred binder. The use of a synthetic binder with the admixture of at least one natural polymer, such as particularly preferably starch, is a particularly suitable embodiment of an intermediate layer. In experiments with inorganic pigments, it was also found that a Binder-pigment ratio within the intermediate layer between 3:7 and 1:9, in each case based on the percentage by mass in the intermediate layer, represents a particularly suitable embodiment.

A heat-sensitive recording material according to the invention is preferred in which no further layer is arranged on that side of the heat-sensitive recording layer which is remote from the carrier substrate. The heat-sensitive recording layer of the heat-sensitive recording material according to the invention thus has in particular no top coat. Although such a top coat is possible, it is not preferred, in particular because the heat-sensitive recording layer has a particularly high grease resistance, as explained above, and a top coat is therefore no longer required to bring about this property in the first place.

A heat-sensitive recording material according to the invention is preferred (preferably a recording material according to the invention as defined as preferred above), the carrier substrate being made of paper, synthetic paper, plastic film or a combination of these materials. The technical effects associated with the present invention are largely independent of the carrier substrate, so that this can be selected from a wide group of materials.

However, a non-surface-treated base paper is particularly preferred as the carrier substrate, since it has good recyclability and good environmental compatibility. A non-surface-treated base paper is to be understood as meaning a base paper that has not been treated in a size press or in a coating device. Films made of polypropylene or other polyolefins are preferred as plastic films. Papers coated with one or more polyolefins (particularly polypropylene) are also preferred according to the invention.

In a very particularly preferred embodiment variant, the carrier substrate is a paper with a proportion by mass of recycled fibers of at least 70%, based on the total proportion of fibers in the paper.

A coating composition according to the invention and a heat-sensitive recording layer according to the invention each comprise one or more dye precursors (color formers). Preference is given to using color formers which are compounds of the fluoran type, preference being given to compounds selected from the group consisting of

3-Diethylamino-6-methyl-7-anilinofluoran, 3-Diethylamino-6-methyl-7-(3'-methylphenylamino)fluoran (6'-(diethylamino)-3'-methyl-2'-(m- tolylamino)-3H-spiro[isobenzofuran-1,9'-xanthene]-3-one; ODB-7), 3-di-n-pentylamino-6-methyl-7-anilinofluoran, 3-(diethylamino)- 6-methyl-7-(3-methylphenylamino)fluoran, 3-di-n-butylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-6-methyl -7-xylidinofluoran, 3-diethylamino-7-(2-carbomethoxyphenylamino)fluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-(4-n-butyl-phenylamino )fluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3-Nn-dibutylamino-6-methyl-7-anilinofluoran (ODB-2), 3-(N-methyl-N-cyclohexyl)amino-6 -methyl-7-anilinofluoran, 3-(N-methyl-N-propyl)amino-6-methyl-7-anilinofluoran, 3-(N-methyl-N-tetrahydrofurfuryl)amino-6-methyl-7-anilinofluoran ), 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluoran, 3-(N-ethyl-N-tolyl)amino-6-methyl-7-anilinofluoran, 3-(N-ethyl -N-tetrahydrofuryl)amino-6- methyl-7-anilinofluoran, 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran, 3-(N-ethyl-4-toluidino)6-methyl-7-(4-toluidino) fluoran and 3-(N-cyclopentyl-N-ethyl)amino-6-methyl-7-anilinofluoran.

Also preferred are coating compositions according to the invention or heat-sensitive recording layers which, as dye precursors (color formers), are as described in paragraphs [0049] to [0052] of EP 2 923 851 A1 contain said compounds.

Particularly preferred according to the invention is a coating composition according to the invention and a heat-sensitive recording layer according to the invention, wherein a dye precursor (color former) is used which is selected from the group consisting of 3-N-di-n-butylamino-6-methyl-7-anilinofluoran (ODB -2) and 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran.

handelt. Die Verbindung der Formel (I) (NKK) liegt vorzugsweise (aber nicht zwingend) in einer vorstehend bereits beschriebenen kristallinen Form vor, die im IR-Spektrum eine Absorptionbande bei 3401 ± 20 cm^-1 aufweist.A coating composition and a heat-sensitive recording layer according to the invention comprise one or more color developers, wherein the one or at least one of the more color developers is NKK. In addition to NKK, one or more other color developers can be present, resulting in a color developer mixture overall. A coating composition according to the invention and a heat-sensitive recording layer according to the invention are preferred in which, in addition to a compound of the formula (I) (NKK) as the first color developer, a further color developer is provided which is a compound of the formula (II)

acts. The compound of the formula (I) (NKK) is preferably (but not necessarily) present in a crystalline form which has already been described above and which has an absorption band at 3401±20 cm ^-1 in the IR spectrum.

The compound of formula (II) is the already known compound N- (4-methylphenylsulfonyl)-N'-(3-(4-methylphenylsulfonyloxy)phenyl)urea, which is marketed under the name ^Pergafast® 201 and, for example in the EP 1 140 515 B1 is described. Pergafast ^® 201 is the most commonly used phenol-free color developer.

Surprisingly, the simultaneous presence of the compound of the formula (II) in addition to the compound of the formula (I) (NKK) again contributes to further increasing the grease resistance of a heat-sensitive recording layer according to the invention or a corresponding heat-sensitive recording material according to the invention will. With regard to the resistance to grease, a synergistic effect was observed which results from the simultaneous presence of the compounds of formula (I) and (II). In coating compositions, heat-sensitive recording layers and heat-sensitive recording materials according to the invention, preference is given to a mass ratio between the compound of the formula (I) and the compound of the formula (II) which is from 0.5:99.5 to 99.5:0.5. It has been shown in our own investigations that with a mass fraction of less than 0.5% of the compound of the formula (I) or (II), based on the total mass of the compounds of the formula (I) and (II), the positive influence of the respective compound is not so pronounced.

Particularly preferred according to the invention are a coating composition according to the invention, a heat-sensitive recording layer according to the invention and a heat-sensitive recording material according to the invention, the mass ratio between the compound of the formula (I) and the compound of the formula (II) being from 35:65 to 65:35, preferably 40:60 to 60:40, more preferably 45:55 to 55:45.

Appropriate mixtures bring about a (further) synergistic effect with regard to improved resistance to lanolin and also improved long-term stability.

As already stated above, certain objects underlying the present invention are achieved through the use of a fatty acid amide (as defined above and in the claims). For this use according to the invention, all of the statements made above regarding (preferred) coating compositions, heat-sensitive recording layers and heat-sensitive recording materials according to the invention apply accordingly, mutatis mutandis.

It has already been explained above that the invention also solves certain objects on which the present invention is based by a method for producing a heat-sensitive recording material according to the invention (as defined there and in the claims). In this respect, too, the above statements on (preferred) coating compositions, heat-sensitive recording layers and heat-sensitive recording materials according to the invention apply accordingly, mutatis mutandis.

In a method according to the invention, the coating composition is preferably applied in an amount of from 2.2 to 2.6 g/m ² to the carrier substrate or one thereon arranged intermediate layer applied. Such a coating weight is comparatively low in comparison with prior art coating compositions which are also said to have high grease resistance. In the context of the present invention, it is possible to achieve high grease resistance with such a low coat weight because, due to the synergistic interaction between the fatty acid amide having a number of carbon atoms in the range from 16 to 24 (preferably octadecanoic acid amide and/or N- (Hydroxymethyl)octadecanoic acid amide) and the sensitizers DPE or EGTE, it is not necessary to use a large amount of fatty acid amide, which increases the resistance to grease.

• Bereitstellen oder Herstellen
  • eines Trägersubstrats mit darauf angeordneter Zwischenschicht (jeweils vorzugsweise wie vorstehend als bevorzugt beschrieben)
    sowie
  • einer erfindungsgemäßen Beschichtungszusammensetzung
• Aufbringen der Beschichtungszusammensetzung auf die Zwischenschicht,
• Trocknen der aufgebrachten Beschichtungszusammensetzung, so dass eine (erfindungsgemäße) wärmeempfindliche Aufzeichnungsschicht resultiert, die gemeinsam mit dem Trägersubstrat und der Zwischenschicht in dem wärmeempfindlichen Aufzeichnungsmaterial vorliegt.

Preference is given to a method according to the invention (as defined above and/or in the claims) for the production of a heat-sensitive recording material (according to the invention), with the following steps:

• Deploy or Manufacture
  • a carrier substrate with an intermediate layer arranged thereon (in each case preferably as described above as preferred)
    as
  • a coating composition according to the invention
• applying the coating composition to the intermediate layer,
• Drying of the applied coating composition, so that a heat-sensitive recording layer (according to the invention) results, which is present together with the carrier substrate and the intermediate layer in the heat-sensitive recording material.

The heat-sensitive recording material produced by the process according to the invention is a layered composite which has at least one carrier substrate, an intermediate layer arranged thereon and a heat-sensitive recording layer in turn arranged on the intermediate layer. For the advantages and the preferred configurations of a heat-sensitive recording material with an intermediate layer, see the comments above.

With regard to preferred configurations and combinations for a coating composition used in a method according to the invention, the explanations given above for the heat-sensitive recording materials according to the invention apply accordingly (if appropriate analogously), and vice versa.

In the context of the present invention and consistent with the general understanding in the field of paper technology, the term "coating composition" refers to paints containing or consisting of pigments or matrix pigments, binders and additives, which are applied to the paper surface or to layers already applied to paper surfaces applied ("coated") with special coating devices for surface finishing or modification of the paper. Papers produced in this way are referred to as "coated papers" and are characterized, for example, by a better feel. The term "coating composition" is thus the generic term for all spreadable coating compositions, preparations and/or solutions in the paper industry for treating, modifying or finishing a paper surface.

Various painting techniques are known to those skilled in the art for applying the coating composition to a supporting substrate or an intermediate layer, for example: blade coating, film press coating, cast coating, curtain coating, knife coating, air knife coating or spray coating. All of these known, aforementioned brushing techniques are suitable for applying the coating compositions according to the invention to a substrate, preferably a paper, which comprises one or more primers or intermediate coats or which also comprises no primer or intermediate coat.

Another aspect of the present invention relates to products, preferably tickets, TITO tickets (ticket-in, ticket-out), flight, train, ship or bus ticket, gambling receipt, parking ticket, label, receipt, bank statements, self-adhesive label, medical and /or technical chart paper, fax paper, security paper or barcode labels, comprising a heat-sensitive recording material according to the invention.

A further aspect of the present invention is the use of a heat-sensitive recording material according to the invention as a barcode label, self-adhesive ticket, self-adhesive admission ticket, self-adhesive proof of purchase, self-adhesive label, self-adhesive admission ticket, admission ticket, TITO tickets (ticket-in, ticket-out), Airplane, train, boat or bus ticket, gambling receipt, parking ticket, label, sales receipt, bank statement, medical and/or technical chart paper, fax paper or security paper.

• Bereitstellen eines erfindungsgemäßen wärmeempfindlichen Aufzeichnungsmaterials (wie vorstehend und in den Ansprüchen definiert, vorzugsweise wie vorstehend als bevorzugt bezeichnet) oder Durchführen des erfindungsgemäßen Herstellungsverfahrens (wie vorstehend und in den Ansprüchen definiert, vorzugsweise wie vorstehend als bevorzugt bezeichnet), so dass ein wärmeempfindliches Aufzeichnungsmaterial resultiert
• Wärmebehandeln des Aufzeichnungsmaterials, so dass sich Farbentwickler und Farbstoffvorläufer unter Ausbildung einer Färbung umsetzen.

The invention also relates to a method for producing a thermally printed heat-sensitive recording material, with the following steps:

• Providing a heat-sensitive recording material according to the invention (as defined above and in the claims, preferably as described above as preferred) or carrying out the production method according to the invention (as defined above and in the claims, preferably as described above as preferred), so that a heat-sensitive recording material results
• Heat-treating the recording material so that the color developer and dye precursor react to form a color.

The fatty acid amide used with a number of carbon atoms in the range from 16 to 24 or the mixture of several fatty acid amides each with a number of carbon atoms in the range from 16 to 24, preferably octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide, remains , at the place of heat treatment (where the thermal head acts in practice) preferably in the solid state.

The fatty acid amide used with a number of carbon atoms in the range from 16 to 24 or the mixture of several fatty acid amides used, each with a number of carbon atoms in the range from 16 to 24, preferably octadecanoic acid amide and/or N-(hydroxymethyl)octadecanoic acid amide, thus melts preferably not and thus does not act as a sensitizer.

The coloring formed is preferably part of a printed image, in particular a printed graphic, lettering, a pattern or a recording.

• Figur 1 zeigt einen Vergleich von IR-Spektren im Wellenzahlenbereich von ca. 4000 bis 2000 cm^-1 der zwei kristallinen Formen der Verbindung der Formel (I). Im oberen Teil abgebildet und mit a) bezeichnet ist das IR-Spektrum der erfindungsgemäß verwendeten kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von 175 °C. Im unteren Teil abgebildet und mit b) bezeichnet ist das IR-Spektrum der kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von ca. 158 °C.
• Figur 2 zeigt einen Vergleich von IR-Spektren im Wellenzahlenbereich von ca. 2400 bis 400 cm^-1 der zwei kristallinen Formen der Verbindung der Formel (I). Im oberen Teil abgebildet und mit a) bezeichnet ist das IR-Spektrum der erfindungsgemäß verwendeten kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von 175 °C. Im unteren Teil abgebildet und mit b) bezeichnet ist das IR-Spektrum der kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von ca. 158 °C.
• Figur 3 zeigt einen Vergleich von IR-Spektren der zwei kristallinen Formen der Verbindung der Formel (I). Im oberen Teil abgebildet und mit a) bezeichnet ist das IR-Spektrum der erfindungsgemäß verwendeten kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von 175 °C. Im unteren Teil abgebildet und mit b) bezeichnet ist das IR-Spektrum der kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von ca. 158 °C.
• Figur 4 zeigt einen Vergleich von Röntgenpulverdiffraktogrammen der zwei kristallinen Formen der Verbindung der Formel (I). Im oberen Teil abgebildet und mit a) bezeichnet ist das Röntgenpulverdiffraktogramm der kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von ca. 158 °C. Im unteren Teil abgebildet und mit b) bezeichnet ist das Röntgenpulverdiffraktogramm der erfindungsgemäß verwendeten kristallinen Form der Verbindung der Formel (I) mit einem Schmelzpunkt von 175 °C.

The attached figures 1 , 2 , 3 and 4 are graphic reproductions (clean drawings) of machine-generated original spectra or machine-generated original diffractograms.

• figure 1 shows a comparison of IR spectra in the wave number range from about 4000 to 2000 cm ^-1 of the two crystalline forms of the compound of formula (I). The IR spectrum of the crystalline form of the compound of the formula (I) with a melting point of 175° C. used according to the invention is shown in the upper part and is denoted by a). The IR spectrum of the crystalline form of the compound of the formula (I) with a melting point of approx. 158° C. is shown in the lower part and labeled b).
• figure 2 shows a comparison of IR spectra in the wave number range from about 2400 to 400 cm ^-1 of the two crystalline forms of the compound of formula (I). Shown in the upper part and denoted by a) is the IR spectrum of the crystalline used according to the invention Form of the compound of formula (I) having a melting point of 175°C. The IR spectrum of the crystalline form of the compound of the formula (I) with a melting point of approx. 158° C. is shown in the lower part and labeled b).
• figure 3 Figure 1 shows a comparison of IR spectra of the two crystalline forms of the compound of formula (I). The IR spectrum of the crystalline form of the compound of the formula (I) with a melting point of 175° C. used according to the invention is shown in the upper part and is denoted by a). The IR spectrum of the crystalline form of the compound of the formula (I) with a melting point of approx. 158° C. is shown in the lower part and labeled b).
• figure 4 Figure 1 shows a comparison of X-ray powder diffractograms of the two crystalline forms of the compound of formula (I). The X-ray powder diffractogram of the crystalline form of the compound of the formula (I) with a melting point of approx. 158° C. is shown in the upper part and denoted by a). The X-ray powder diffractogram of the crystalline form of the compound of the formula (I) with a melting point of 175° C. used according to the invention is shown in the lower part and labeled b).

Examples: Determination of the resistance of heat-sensitive recording materials to lanolin:

For the metrological determination of the resistance of a thermal printout on the heat-sensitive recording materials of the examples according to the invention and the examples not according to the invention to lanolin, black and white checkered thermal printouts were each printed on the heat-sensitive recording materials to be tested using an Atlantek Model 400 "Thermal Response Test System" device. by Global Media Instruments, LLC (USA), using a thermal head with a resolution of 300 dpi and an energy per unit area of 16 mJ/mm ² .

After the creation of the black and white checkered thermal test prints, after a rest period of more than 5 minutes, the print density was determined in three places of the black colored areas of the thermal test prints using a densitometer TECHKON ^® SpectroDens Advanced - spectral densitometer. The mean value was formed from the respective measured values.

Then the created thermal proof of the heat-sensitive recording material to be tested was coated with lanolin hand cream. After an exposure time After 5 or 10 minutes, the lanolin was carefully dabbed off and the treated thermal paper printout was then stored at 23° C. and 50% humidity. After 4 or 24 hours, the thermal paper printout was removed and the print density was again determined at three points on each of the black-colored areas of the thermal test printouts using a densitometer ^TECHKON® SpectroDens Advanced - spectral densitometer.

The mean value was formed from the respective measured values.

The permanence of the print image in % corresponds to the quotient of the mean value of the print density of the black-colored areas before and after treatment with lanolin and subsequent storage at 23 °C and 50 % humidity multiplied by 100.

Own investigations:
The measurement results determined in our own investigations show that the print density of examples according to the invention decreases less than the print density of examples not according to the invention. The resistance of the printed image to lanolin, ie the grease resistance, is therefore higher in examples according to the invention than in examples not according to the invention in which only one fatty acid amide or only 1,2-diphenoxyethane or ethylene glycol m-tolyl ether was used. The combination of stearamide (octadecanoic acid amide) or N-(hydroxymethyl)octadecanoic acid amide and 1,2-diphenoxyethane or ethylene glycol m-tolyl ether as sensitizer used according to the invention thus has a synergistic effect.

In further in-house investigations, preferred mixing ratios for coating compositions containing both stearamide (octadecanoic acid amide) and 1,2-diphenoxyethane (DPE) were determined. When these experimental investigations were carried out, a coating composition was prepared which largely corresponded to the aqueous application suspension of recipe 1 DE 10 2014 107 567 B3 (see section [0060] there). In our own investigations, the total amount of octadecanoic acid amide (stearamide) and DPE was 40 parts by weight (corresponding to the 40 parts by weight of sensitizer from formulation 1 of DE 10 2014 107 567 B3 ). In our own investigations, the said 40 parts by mass were divided between the components octadecanoic acid amide and DPE, with the mixing ratios being varied. Results of the investigations are given in Table 1 below. Table 1: Mass fractions sensitizers Octadecanoic acid amide : 1,2-diphenoxyethane 20:20 23:17 25:15 27:13 Test series I I-1 I-2 I-3 I-4 Print density before lanolin exposure 1:16 1.23 1:21 1:13 Print density after 5 min exposure to lanolin and 4 h exposure time 0.70 0.97 0.87 0.67 Durability / % 60.3 78.9 71.9 59.3 Test series II II-1 II-2 II-3 II-4 Print density before lanolin exposure 1:15 1.24 1.20 1:13 Print density after 10 min exposure to lanolin and 24 h exposure time 0.18 0.32 0.24 0.27 Durability / % 15.7 25.8 20.0 23.9

Frame composition for a coating composition according to the invention or for a heat-sensitive recording layer according to the invention:
Table 2 gives a preferred framework composition for a coating composition according to the invention or for a heat-sensitive recording layer according to the invention. All information relates to measurements on oven-dried material; the actual coating composition or the actual heat-sensitive recording layer may contain liquid (particularly water); it was therefore subjected to oven drying prior to determination of the mass fractions. Table 2: Mass fraction [%] N-[2-(3-Phenylureido)phenyl]benzenesulfonamide (NKK, color developer) 8-30 dye precursor 4-16 Octadecanoic acid amide (fatty acid amide) 2:4-34 1,2-diphenoxyethane (sensitizer) 2-8.5 Polyvinyl alcohol (PVA, binder) 6-24 pigments 25-55 in total 100

The percentages by mass given in the right-hand column of Table 2 add up to a total of 100%.

Claims (14)

1. A coating composition for producing a heat-sensitive recording material or heat-sensitive recording layer, comprising

   - one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

   

   - one or plural dye precursors,

   - one or plural fatty acid amides each having a number of carbon atoms in the range from 16 to 24,

   - as sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether,

   the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in the range from 4:1 to 1.2:1.
2. The coating composition or heat-sensitive recording layer as claimed in claim 1, further comprising one or plural constituents from the group consisting of

   - further sensitizers,

   - pigments,

   - dispersants,

   - antioxidants,

   - release agents,

   - defoamers,

   - light stabilizers,
   and

   - brighteners.
3. The coating composition or heat-sensitive recording layer as claimed in either of claims 1 and 2, said one or one of the plural fatty acid amides having a number of carbon atoms in the range from 16 to 24

   being octadecanamide and/or N-(hydroxymethyl)octadecanamide
   and/or

   possessing a melting point which is greater than 103°C, preferably greater than 105°C.
4. The coating composition or heat-sensitive recording layer as claimed in any of the preceding claims,

   the ratio of the mass of the compound of the formula (I) to the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 in the coating composition or the heat-sensitive recording layer being in the range from 1.2:1 to 4:1 and/or

   the ratio of the mass of the compound of the formula (I) to the mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition or the heat-sensitive recording layer being in the range from 1.2:1 to 4:1.
5. The coating composition or heat-sensitive recording layer as claimed in any of the preceding claims, the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in the range from 1.5:1 to 1.2:1.
6. The coating composition or heat-sensitive recording layer as claimed in any of the preceding claims, comprising

   - one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

   

   - one or plural dye precursors,

   - octadecanamide and/or N-(hydroxymethyl)octadecanamide,

   - as sensitizer, 1,2-diphenoxyethane and/or ethylene glycol m-tolyl ether,

   the ratio of the mass of the compound of the formula (I) to the mass of octadecanamide and/or N-(hydroxymethyl)octadecanamide in the coating composition or the heat-sensitive recording layer being in the range from 1.2:1 to 4:1,
   and

   the ratio of the total mass of octadecanamide and N-(hydroxymethyl)octadecanamide to the total mass of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the coating composition or the heat-sensitive recording layer being in the range from 1.5:1 to 1.2:1.
7. The coating composition or heat-sensitive recording layer as claimed in any of the preceding claims, comprising as sensitizer 1,2-diphenoxyethane or a mixture of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether.
8. A heat-sensitive recording material, comprising

   - a carrier substrate
   and

   - a heat-sensitive recording layer as claimed in any of claims 1 to 7.
9. The heat-sensitive recording material as claimed in claim 8, wherein

   - one or plural interlayers are disposed between carrier substrate and heat-sensitive recording layer
   and/or

   - no further layer is disposed on the side of the heat-sensitive recording layer that faces away from the carrier substrate
   and/or

   - the carrier substrate consists of paper, synthetic paper, polymeric film, or an assembly of these materials.
10. The use of a fatty acid amide having a number of carbon atoms in the range from 16 to 24 or of a mixture of plural fatty acid amides each having a number of carbon atoms in the range of 16 to 24, preferably use of octadecanamide and/or N-(hydroxymethyl)octadecanamide,
    for increasing the grease resistance of a heat-sensitive recording material or a heat-sensitive recording layer, comprising

    - one or plural color developers, said one or at least one of the plural color developers being a compound of the formula (I)

    

    - one or plural dye precursors,
    and

    - as sensitizer, one or more compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether,

    the ratio of the total mass of fatty acid amides having a number of carbon atoms in the range from 16 to 24 to the total mass of compounds selected from the group consisting of 1,2-diphenoxyethane and ethylene glycol m-tolyl ether in the heat-sensitive recording material or the heat-sensitive recording layer being in the range from 4:1 to 1.2:1.
11. A method for producing a heat-sensitive recording material as claimed in either of claims 8 and 9 or a heat-sensitive recording layer, having the following steps:

    - providing or producing a carrier substrate and also a coating composition as claimed in any of claims 1 to 7,

    - applying the coating composition to the carrier substrate or an interlayer disposed thereon,

    - drying the applied coating composition, to give a heat-sensitive recording layer which is present together with the carrier substrate in a heat-sensitive recording material.
12. The method as claimed in claim 11, for producing a heat-sensitive recording material as claimed in either of claims 8 and 9, having the following steps:

    - providing or producing

    - a carrier substrate with interlayer disposed thereon
    and also

    - a coating composition as claimed in any of claims 1 to 7,

    - applying the coating composition to the interlayer,

    - drying the applied coating composition, to give a heat-sensitive recording layer which is present together with the carrier substrate and the interlayer in the heat-sensitive recording material.
13. A method for producing a thermally printed heat-sensitive recording material, having the following steps:

    - providing a heat-sensitive recording material as claimed in either of claims 8 and 9 or implementing the method as claimed in either of claims 11 and 12, to give a heat-sensitive recording material,

    - heat-treating the recording material, so that color developers and dye precursors react so as to develop a coloration.
14. The method as claimed in claim 13, wherein the fatty acid amide used having a number of carbon atoms in the range from 16 to 24 or the mixture used of plural fatty acid amides each having a number of carbon atoms in the range from 16 to 24, preferably octadecanamide and/or N-(hydroxymethyl)octadecanamide, remains in the solid state at the location of the heat treatment.

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