Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/323—Organic colour formers, e.g. leuco dyes
  • B41M5/327—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring
  • B41M5/3275—Fluoran compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/333—Colour developing components therefor, e.g. acidic compounds
  • B41M5/3333—Non-macromolecular compounds
  • B41M5/3335—Compounds containing phenolic or carboxylic acid groups or metal salts thereof
  • B41M5/3336—Sulfur compounds, e.g. sulfones, sulfides, sulfonamides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/337—Additives; Binders
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/337—Additives; Binders
  • B41M5/3372—Macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/337—Additives; Binders
  • B41M5/3375—Non-macromolecular compounds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/337—Additives; Binders
  • B41M5/3377—Inorganic compounds, e.g. metal salts of organic acids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/04—Direct thermal recording [DTR]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/323—Organic colour formers, e.g. leuco dyes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/26—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used
  • B41M5/30—Thermography ; Marking by high energetic means, e.g. laser otherwise than by burning, and characterised by the material used using chemical colour formers
  • B41M5/323—Organic colour formers, e.g. leuco dyes
  • B41M5/327—Organic colour formers, e.g. leuco dyes with a lactone or lactam ring

Definitions

• the present invention relates to a heat-sensitive recording layer comprising organic color developers free from phenol groups, a coating composition for producing the heat-sensitive recording layer and a heat-sensitive recording material, in particular thermal paper, comprising the heat-sensitive recording layer.
• the present invention further relates to the use of the heat-sensitive recording layer for the production of the heat-sensitive recording material, a method for the production of the heat-sensitive recording material and the use of the heat-sensitive recording material in thermal paper applications. Because of its composition, the heat-sensitive recording material of the present invention has particularly good recyclability and high environmental compatibility.
• Heat-sensitive recording materials (often also referred to as "thermal papers”) have been known for many years and are very popular. This popularity is based, among other things, on the fact that the color-forming components are contained in the recording material itself, meaning that printers without toner and ink cartridges can be used. It is therefore no longer necessary to use toner or color cartridges, to stockpile, to change or to fill up.
• This innovative technology has become widespread in business life, particularly in public transport and in retail, where its flexible applicability in business transactions (at the "point-of-sale”) is valued.
• Pergafast ® 201 corresponds to N- (4-methylphenylsulfonyl) -N '-(3-(4-methylphenylsulfonyloxy)phenyl)urea
• "D8" corresponds to 4-hydroxy-4'- isopropoxydiphenylsulfone
• a thermal printout ie a heat-induced recording
• aqueous alcohol solutions and plasticizers in the document DE 10 2004 004 204 A1 proposed a heat-sensitive recording material whose heat-sensitive recording layer has conventional dye precursors and the combination of a phenolic color developer and a urea-urethane-based color developer.
• a heat-sensitive recording material which comprises a carrier substrate and a heat-sensitive color-forming layer containing at least one color former and at least one phenol-free color developer, N-phenyl-N'[(phenylamino)sulfonyl]-urea,N-(4- methylphenyl)-N'[(4-ethylphenylamino)sulfonyl]urea, N-(4-ethoxycarbonylphenyl)-N'[(4-ethoxycarbonylphenylamino)sulfonyl]urea or structurally similar compounds can be used.
• JP 2014-218062 A describes a heat-sensitive recording material having a heat-sensitive recording layer containing at least a leuco dye and a color developer on a support.
• a mixture of 4,4'-bis(3-tosylureido)diphenylmethane and N-[2-(3-phenylureido)phenyl]benzenesulfonamide is used as the color developer.
• WO 2016/136203 A1 describes a crystalline form of N-(2-(3-phenylureido)-phenyl)benzenesulfonamide and the use of this crystalline form in a recording material.
• WO 2018/065328 A1 as WO 2018/065330 A1 each disclose a heat-sensitive recording material comprising a carrier substrate and a heat-sensitive recording layer, wherein the heat-sensitive recording layer comprises a color former and a color developer mixture.
• the document WO 2019/166608 A1 describes a heat-sensitive recording material and color developer.
• a printed heat-sensitive recording material is exposed to a variety of different environmental influences, such as humidity, temperature extremes and/or chemicals, given its typical areas of application as tickets, entrance tickets, transport tickets, parking tickets and the like.
• heat-sensitive recording materials should therefore also have the highest possible resistance to thermal influences.
• the printed image should be preserved after printing and when exposed to heat, the printed image should fade as little as possible and the unprinted background should not discolor: this would make the print illegible.
• Thermal resistance is particularly important for parking tickets, which are stored behind the windshield after printing and are therefore exposed to high temperatures and direct sunlight in summer.
• a further object of the present invention was to provide a heat-sensitive recording material which, in the printed state, has high resistance to environmental influences, such as moisture, heat, fat or fats and/or chemicals.
• composition of the above-mentioned heat-sensitive recording layer according to the invention makes it possible to use it to produce a heat-sensitive recording material, in particular a thermal paper, which has particularly good recyclability and high environmental compatibility.
• the heat-sensitive recording layer according to the invention contains no developers containing phenol groups, making it particularly suitable for the production of heat-sensitive recording material with good recyclability, since such heat-sensitive recording material causes little or no irreversible discoloration, for example in deinking systems.
• the heat-sensitive recording layer according to the invention and the heat-sensitive recording material according to the invention also come without classic organic sensitizer compounds (hereinafter referred to as "sensitizers") such as benzyl 2-naphthyl ether, 1,2-diphenoxyethane, 1,2-bis(3 -methylphenoxy)-ethane or 1-phenoxy-2-(4-methylphenoxy)ethane, which are increasingly regarded as unattractive from the point of view of environmental compatibility.
• the heat-sensitive recording layer according to the invention preferably does not contain any organic hollow body pigments which could get into the environment as undesired "microplastics". Dyes which are potentially harmful to the environment or health, such as carbon black, can preferably be dispensed with entirely in the heat-sensitive recording layer according to the invention and in the heat-sensitive recording material according to the invention.
• the above-mentioned heat-sensitive recording layer according to the invention preferably comprises exclusively components (or constituents) which, according to the " Award criteria for printing and press paper mainly made from waste paper", DE-UZ 72, January 2020 issue, version 1 , for the "Blue Angel” eco-label of the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (hereinafter referred to as "Award Criteria Blue Angel DE-UZ 72") and the " Award criteria for graphic paper and cardboard made from 100% waste paper (recycled paper and cardboard)", DE-UZ 14a, January 2020 issue, version 2 , for which the aforementioned environmental label of the "Blue Angel” (hereinafter referred to as "award criteria Blue Angel DE-UZ 14a”) are approved.
• the heat-sensitive recording layer according to the invention specified above comprises, as component K1), one or more organic dye precursors, each of which comprises a fluoran structure.
• the compound fluoran per se is known as a triarylmethane dye.
• the chemical structure of the fluoran is of formula I given below also known as the structural core of a number of organic dye precursors, which include substituted derivatives of fluoran (also referred to as "fluorane leuco dyes" and "fluorane leuco dye precursors,” respectively).
• the abovementioned heat-sensitive recording layer according to the invention preferably comprises as component K1) one or more organic dye precursors which comprise an abovementioned substituted fluoran structure of the formula I as the structural core.
• the heat-sensitive recording layer according to the invention specified above comprises, as component K4), one or more, preferably synthetic, amide waxes which each have a melting point in the range from 80.degree. C. to 120.degree.
• amide waxes are preferably synthetically produced waxes, which are preferably produced by reacting technical fatty acids, fatty acid esters and/or triacylglycerols with ammonia, monovalent amines, polyvalent amines and/or amino alcohols.
• sensitizers to be used according to the invention act as or assume the function of a sensitizer known per se.
• a sensitizer used in a heat-sensitive recording layer is at least partially melted by the application of heat during printing.
• the at least partially melted sensitizer dissolves and/or lowers the melting point (or melting range) of the color former and color developer coexisting in a heat-sensitive recording layer, thereby facilitating or inducing a color-developing reaction.
• the sensitizer does not usually take part in the color development reaction itself.
• an above-mentioned heat-sensitive recording layer according to the invention or a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text
• a heat-sensitive recording layer according to the invention or a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text is) a composition specified in this text, in addition to the one or more, preferably synthetic, amide waxes specified as component K4), each of which has a melting point in the range from 80 ° C to 120 ° C (or in addition to the one specified below as preferred or more, preferably synthetic, amide waxes, do not have to contain any further sensitizers as component K4)), in particular no "classical" sensitizers, in order to have the advantageous properties specified above or below.
• the above-mentioned heat-sensitive recording layer according to the invention preferably contains such sensitizers in a total amount of ⁇ 1 percent by mass, based on the dry mass of the heat-sensitive recording layer, which are selected from the group "classical" sensitizers consisting of 1,2-bis(3-methylphenoxy)ethane, 1,2-diphenoxyethane, 1-phenoxy-2-(4-methylphenoxy)ethane, benzyl 2-naphthyl ether, 2-(2H-benzotriazole- 2-yl)-p-cresol, 2,2'-bis(4-methoxyphenoxy)diethyl ether, 4,4'-diallyloxydiphenylsulfone, 4-acetylacetophenone, 4-benzylbiphenyl, acetoacetic anilide, benzyl 4-(benzyloxy)benzoate, benzylparab
• inventive heat-sensitive recording layer specified above particularly preferably contains no sensitizers selected from the above-specified group of “classic” sensitizers.
• preferred heat-sensitive recording layers according to the invention offer the advantage that (with a suitable selection of the other components) they can also be used safely, e.g. in the food sector, even if e.g. direct or indirect contact of the recording layer with the food cannot be ruled out.
• the heat-sensitive recording layer according to the invention specified above comprises one or more particulate inorganic pigments as component K5).
• the particulate inorganic pigments to be used according to the invention preferably not only or not primarily fulfill the function of dyes, but also at least or even predominantly fulfill the function of particulate fillers. If the particulate inorganic pigments to be used according to the invention at least also have the function of Dyes have, it is preferably white pigments. For more information on the particulate inorganic pigments to be used according to the invention, see also below.
• the heat-sensitive recording layer according to the invention specified above preferably comprises organic hollow body pigments (in particular those as specified or defined in the document WO 2012/145456 A1 ) at most in a total amount of ⁇ 1 percent by mass, based on the dry mass of the heat-sensitive recording layer.
• organic hollow body pigments in particular those as specified or defined in the document WO 2012/145456 A1
• the above-mentioned heat-sensitive recording layer according to the invention contains no such organic hollow body pigments.
• the heat-sensitive recording layer according to the invention specified above comprises one or more lubricants as component K6).
• lubricant is understood to mean - as is customary in the paper industry - additives for plastic compositions containing fillers (such as coating colors or coating compositions), which preferably serve to make the fillers more easily gliding and the plastic compositions thus more easily deformable or to make it processable.
• the one or more lubricants of component K6) are preferably selected from the group consisting of metal soaps (preferably salts of fatty acids with a total number of carbon atoms in the range from ⁇ 12 to ⁇ 22 with metal ions with a single or double positive charge), wax dispersions, paraffin dispersions, sulfated oils and mixtures thereof.
• metal soaps preferably salts of fatty acids with a total number of carbon atoms in the range from ⁇ 12 to ⁇ 22 with metal ions with a single or double positive charge
• wax dispersions preferably salts of fatty acids with a total number of carbon atoms in the range from ⁇ 12 to ⁇ 22 with metal ions with a single or double positive charge
• paraffin dispersions preferably s of sulfated oils and mixtures thereof.
• the sum of the components K1) to K6) makes up ⁇ 95 percent by weight of the dry weight of the heat-sensitive recording layer.
• “Dry mass” in the context of the present invention is preferably understood to mean the water- and moisture-free mass of a sample (here: the heat-sensitive recording layer according to the invention) measured (under laboratory conditions at 23° C. and 50% RH).
• the dry mass is preferably determined—as is customary in the field—on the sample to be examined (here: the heat-sensitive recording layer according to the invention), which had been dried at 105° C. to constant weight before the determination.
• the dry mass of a sample (in particular a sample of the heat-sensitive recording layer according to the invention) can be determined for the purposes of the present invention by heating a sample of defined mass before drying (e.g. 1.5 g of the sample before drying) at 105° C. for five hours dries in the drying oven and then, after cooling to room temperature (in case of doubt to 23 °C) checks for constant weight (sample, e.g. by heating it up again and determining the mass again) in a manner known per se, whereby, of course, reabsorption of water during the cooling process must be avoided (desiccator ).
• a sample of defined mass before drying e.g. 1.5 g of the sample before drying
• room temperature in case of doubt to 23 °C
• the dry mass of a sample in particular a sample of the heat-sensitive recording layer according to the invention
• a moisture determination device for example a halogen moisture determination device known per se, under the conditions specified above (105° C., heating to constant weight).
• process auxiliaries preferably selected from the group consisting of defoamers, biocides, dispersants and wetting agents, preferably in a total amount of ⁇ 5 percent by mass, particularly preferably in a total amount in the range from ⁇ 0.1 to ⁇ 3 percent by mass and more preferably in the range from ⁇ 0.1 to ⁇ 2 percent by mass, based on the dry mass of the heat-sensitive recording layer.
• the one or more process auxiliaries K7) preferably serve to facilitate or enable the processing of a heat-sensitive recording layer according to the invention (or a coating composition according to the invention for producing a heat-sensitive recording layer according to the invention) in the industrial production process, in particular in the industrial process of paper production.
• a heat-sensitive recording layer according to the invention as indicated above (or a heat-sensitive recording layer according to the invention indicated as preferred in this text) which additionally comprises one or more optical brighteners may be preferred. If a heat-sensitive recording layer according to the invention additionally comprises one or more optical brighteners, it is preferred if the heat-sensitive recording layer according to the invention contains this one or more optical brighteners in a total amount of ⁇ 1 percent by mass, more preferably in a total amount of ⁇ 0.75 percent by mass, based on the dry mass of the heat-sensitive recording layer. Particularly preferably, the above-mentioned heat-sensitive recording layer according to the invention (or a heat-sensitive recording layer according to the invention which is referred to as preferred in this text) contains no optical brighteners.
• a heat-sensitive recording layer according to the invention specified above or a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text
• the sum of components K1) to K6) being ⁇ 97 percent by mass, preferably ⁇ 98 percent by mass, more preferably ⁇ 98, 5 percent by mass that makes up the dry mass of the heat-sensitive recording layer
• the heat-sensitive recording layer according to the invention comprises a component K7
• the sum of the components K1) to K7) makes up ⁇ 99 percent by mass, particularly preferably 100 percent by mass, of the dry mass of the heat-sensitive recording layer.
• the color developers which contain phenol groups and which are therefore preferably not used as phenol-group-free organic color developers K2) in an above-mentioned heat-sensitive recording layer according to the invention include, in particular, the known compounds bisphenol A (4,4'-propane-2,2 -diyldiphenol), bisphenol S (4,4'-sulfonyldiphenol), bisphenol AP (1,1-bis(4-hydroxyphenyl)-1-phenylethane CAS RN 1571-75-1 ), 4-[(4-Isopropoxyphenyl)sulfonyl]phenol (also known as "D8", CAS RN 95235-30-6 ), 4,4'-Methylenediphenol, 2,2'-Methylenediphenol, 4-[4'-[(1'-Methylethyloxy)phenyl]sulfonyl]phenol (also known as "D90", CAS RN 191680-83-8 ), 2,2'-diallyl-4,4'-sul
• one or at least one of the several phenol-free organic color developers K2) can be the compound N- (4-methylphenylsulfonyl) -N '-(3-(4-methylphenylsulfonyloxy)phenyl)urea of the formula III be or include (see above), which are also referred to as "Pergafast 201" ( CAS no. 232938-43-1 ) is known.
• one or at least one of the several phenol-free organic color developers K2) can also contain the compound 5-(N-3-methylphenylsulfonylamido)-(N',N"-bis-(3-methylphenyl )-isophthalic acid diamide of the formula IV be.
• the compound 5-(N-3-methylphenylsulfonylamido)-(N',N''-bis-(3-methylphenyl)isophthalic acid diamide of the formula IV is known per se, for example from the document WO 2019/166608 A1 , and can be prepared using the methods given there.
• the compound of formula IV can exist in several different crystalline forms. These different crystalline forms may have different physical properties, which may have influences on a heat-sensitive recording layer containing such crystalline forms as a color developer. At least three different crystalline forms of the compound of the formula IV are currently known, which are referred to as the crystalline modification " ⁇ ", as the crystalline modification " ⁇ " or as the crystalline modification " ⁇ " (cf.
• the heat-sensitive recording layer of the present invention may be any individual of these three different crystalline forms of the compound of the formula IV (as component K2)) and mixtures thereof.
• a heat-sensitive recording layer according to the invention as described above (preferably a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text), wherein the compound of formula I comprises a crystalline form or wherein the compound of formula IV is present in a crystalline form, where preferably the or at least one crystalline form of the compound of formula IV has a melting point in the range from 195°C to 217°C, preferably from 200°C to 215°C, more preferably from 205°C to 213°C, as determined by differential thermal analysis (DSC).
• DSC differential thermal analysis
• a heat-sensitive recording layer according to the invention as described above (preferably a heat-sensitive recording layer according to the invention, which is referred to in this text as preferred), wherein the compound of formula IV comprises a crystalline form or wherein the compound of formula IV is present in a crystalline form, wherein the crystalline form of the compound of formula I is the crystalline modification " ⁇ " as described in WO 2019/166608 A1 , p. 8, lines 9-13.
• a heat-sensitive recording layer according to the invention as described above (preferably a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text), wherein the compound of the formula IV comprises a crystalline form or wherein the compound of the formula IV is present in a crystalline form, where the crystalline form of the compound of the formula IV has an X-ray powder diffractogram with diffraction reflections at °2 ⁇ values (+/- 0.2°) of 5.5, 6.1, 6.4, 12.1, 16.1, 16.8, 17.1, 18.3, 19.1, 19.9, 20.2, 21.4, 22.1, 22.7, 23.3, 24.3, 24.7, 25.0, 26.4, 27.7 and 29.3.
• a heat-sensitive recording layer according to the invention as described above (preferably a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text), where the compound of the formula IV accounts for ⁇ 95% by mass, preferably completely (to the extent of 100% by mass). , is present as the crystalline modification " ⁇ " (as described above), based on the total mass of the compound of formula IV present in the heat-sensitive recording layer.
• one or at least one of the several organic color developers K2) free from phenol groups can also contain the compound N- [2-(3-phenylureido)phenyl]benzenesulfonamide of the formula V be.
• the compound N-[2-(3-phenylureido)phenyl]benzenesulfonamide of the formula V is one, for example from EP 2 923 851 A1 , known compound, for example, under the name "NKK-1304".
• the compound of formula V can exist in several different crystalline forms. These different crystalline forms may have different physical properties, which may have influences on a heat-sensitive recording layer containing such crystalline forms as a color developer.
• the compound of the formula V which is not differentiated according to polymorphic forms, is used in the literature CAS RN 215917-77-4 attributed.
• the heat-sensitive recording layer according to the invention can contain each of these three different crystalline forms of the compound of the formula V (as component K2)) and mixtures thereof.
• the first of these crystalline forms of the compound of formula V has a melting point of about 158°C. This crystalline form was used in connection with heat-sensitive recording materials, for example, in the EP 2 923 851 A1 , described.
• the second crystalline form of the compound of formula V has a melting point of about 175°C.
• the compound of formula V which is the crystalline form with a melting point of 175°C, has been described in the document WO 2018/065328 A1 .
• the third crystalline form of the compound of the formula V has a melting point of about 160° C. to 162° C. and was described, for example, in document EP 3 263 553 A1 described.
• second crystalline form of the compound of the formula VII preferably between 173 °C and 177 °C, particularly preferably between 174 °C and 176 °C, determined with the aid of differential thermal analysis (DSC), also known as "differential scanning calorimetry" (DKK), at a heating rate of 10 K/min.
• DSC differential thermal analysis
• DKK differential scanning calorimetry
• At least the first and the second of the aforementioned crystalline forms of the compounds of formula V 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 compound of the formula V used according to the invention. In the crystalline form of the compound of the formula V, which has a melting point of about 158° C., this band is not present, but rather a band at 3322 and 3229 cm -1 .
• a heat-sensitive recording layer is also preferred according to the invention, the crystalline form of the compound of the formula V in the IR spectrum having absorption bands at 689 ⁇ 10 cm -1 , 731 ⁇ 10 cm -1 , 1653 ⁇ 10 cm -1 3364 ⁇ 20 cm -1 and 3401 ⁇ 20 cm -1 ("second crystalline form of the compound of formula V").
• At least the first and the second of the aforementioned crystalline forms of the compound of the formula V can also be distinguished from one another in the X-ray powder diffractogram or diffraction diagram.
• a heat-sensitive recording material is preferred according to the invention, the crystalline form of the compound of the formula V having an X-ray powder diffractogram with reflections at °2 ⁇ values of 10.00 ⁇ 0.20, 11.00 ⁇ 0.20, 12.40 ⁇ 0.20, 13.80 ⁇ 0.20 and 15.00 ⁇ 0.20 ("second crystalline form of the compound of formula V").
• a heat-sensitive recording layer in which the crystalline form of the compound of the formula V has an X-ray powder diffractogram which essentially corresponds to that in FIG. 4b) of FIG WO 2018/065328 A1 shown X-ray powder diffraction pattern ("second crystalline form of the compound of formula V").
• a compound of the formula V preferably describes the crystalline form which has an absorption band at 3401 ⁇ 20 cm -1 in the IR spectrum or has a melting point of 175° C. or has a transition at a temperature between 170 °C and 178 °C (determined by differential thermal analysis, at a heating rate of 10 K/min) or in the X-ray powder diffractogram diffraction reflections at °2 ⁇ 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 unless the presence of the other crystal structure is explicitly stated ("second crystalline form of the compound of formula V").
• a heat-sensitive recording layer according to the invention as described above (preferably a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text), wherein the compound of formula V comprises a crystalline form or wherein the compound of formula V is in a crystalline form ( if the heat-sensitive recording layer comprises, for example, a color developer mixture, the color developer mixture comprising, in addition to a compound of the formula IV, at least one further organic color developer which comprises or is a compound of the formula V), where preferably the or at least one crystalline form of the compound of formula II has an absorption band at 3401 ⁇ 20 cm -1 in the IR spectrum.
• a color developer mixture comprising a compound of formula V (NKK-1304) as defined above, preferably wherein the compound of formula V is in a crystalline form having an absorption band at 3401 ⁇ 20 cm-1 in the IR spectrum, and a compound as defined above of the formula III (Pergafast 201), in the proportions defined above, and the advantages that can be achieved with this color developer mixture in a heat-sensitive recording layer or in a heat-sensitive recording material are described in the documents WO 2018/065328 A1 and WO 2018/065330 A1 , the contents of which are hereby expressly referred to in connection with the present invention.
• thermal printouts produced with a heat-sensitive recording layer according to the invention or with a heat-sensitive recording material according to the invention have particularly advantageous properties if the heat-sensitive recording layer used for this purpose contains the one or more amide waxes K4) (preferably the ones mentioned above as preferred designated one or more amide waxes K4) in the total amount indicated above (preferably in the total amounts indicated above as preferred).
• the particularly advantageous properties of the thermal printouts produced in this way include, in particular, high resistance to plasticizers, high resistance to lanolin, high resistance to water or aqueous ethanol solution, but also high climate resistance and high heat resistance.
• heat-sensitive recording materials produced with heat-sensitive recording layers according to the invention have a dynamic print density which is generally at least comparable to that of a conventional heat-sensitive recording material and in some cases even better.
• the dynamic print density of a heat-sensitive recording material indicates how quickly a heat-sensitive recording material can be printed on. The higher the dynamic print density, the faster a thermal printer can print on the heat-sensitive recording material with otherwise unchanged settings.
• the present invention also relates to a coating composition for producing a heat-sensitive recording layer, comprising the components K1) to K6) defined above and preferably component K7) as above for the heat-sensitive recording layer according to the invention (or for a heat-sensitive recording layer according to the invention, which is referred to in this text as is designated preferred), defined, preferably wherein the coating composition additionally comprises: K8) one or more carrier liquids, preferably selected from the group consisting of (i) water, (ii) monohydric alcohols having a total number of carbon atoms in the range from 1 to 4 and (iii) mixtures of water with one or more monohydric alcohols with a Total number of carbon atoms ranging from 1 to 4.
• thermo printouts with particularly advantageous properties.
• thermal printouts include, in particular, high resistance to plasticizers, high resistance to lanolin, high resistance to water or aqueous ethanol solution, but also high climate resistance and high heat resistance.
• heat-sensitive recording materials produced with heat-sensitive recording layers according to the invention have a dynamic print density which is generally at least comparable to that of a conventional heat-sensitive recording material and in some cases even better.
• a heat-sensitive recording material according to the invention specified above or a heat-sensitive recording material according to the invention which is referred to as preferred in this text—even without a corresponding top layer—already has excellent scratch resistance.
• the heat-sensitive recording material according to the invention has one or more intermediate layers arranged between the substrate and the heat-sensitive recording layer, such an intermediate layer preferably comprises pigments and/or fillers.
• the pigments (or fillers) of such an intermediate layer are preferably inorganic pigments (or fillers), particularly preferably selected from the list consisting of calcined kaolin, silicon dioxide, bentonite, calcium carbonate, aluminum oxide and boehmite.
• inorganic pigments are integrated into the intermediate layer between the recording layer and the substrate, they can absorb and promote the components (eg waxes) of the heat-sensitive recording layer that have been liquefied by the heat of the thermal head during the formation of the typeface thus an even safer and faster functioning of the heat-induced recording.
• the inorganic pigments (or fillers) 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 Japanese standard JIS K 5101. 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.
• a heat-sensitive recording material is preferred according to the invention, the intermediate layer optionally containing, in addition to the inorganic pigments (or fillers), at least one binder, preferably based on a synthetic polymer, with styrene-butadiene latex giving particularly good results.
• a synthetic binder with the admixture of at least one natural polymer, such as particularly preferably starch, represents a particularly suitable embodiment.
• a binder-pigment ratio within the intermediate layer of between 3:7 and 1:9, based in each case on the percentage by mass in the intermediate layer, represents a particularly suitable embodiment.
• the dry mass per unit area of an intermediate layer described above is in the range from 5 to 20 g/m 2 , preferably in the range from 7 to 12 g/m 2 .
• an above-mentioned heat-sensitive recording material according to the invention (preferably a heat-sensitive recording material according to the invention, which is referred to as preferred in this text) also enables very good thermal prints if its heat-sensitive recording layer is only relatively thin (thickness ) is present and preferably the dry mass per unit area of the heat-sensitive recording layer is in the range from ⁇ 1.8 g/m 2 to ⁇ 2.3 g/m 2 , preferably in the range from ⁇ 1.9 g/m 2 to ⁇ 2.2 g/ m 2 , particularly preferably in the range from ⁇ 1.9 g/m 2 to ⁇ 2.15 g/m 2 .
• Such a variant of the present invention enables a particularly economical production of a heat-sensitive recording material with only a small consumption of material. Another advantage of such a variant is that that only relatively small amounts of waste arise when disposing of a heat-sensitive recording material. Since a heat-sensitive recording material according to the invention also largely or preferably exclusively contains components that meet the award criteria of the "Blue Angel" (see above), a heat-sensitive recording material according to the invention has a particularly good ecological balance sheet according to this variant.
• the mass of an "air-dry" paper substrate given above is determined under standard ambient conditions (23°C, 50% RH, 1013 hPa). A water content of the paper substrate of 10 percent by mass is assumed for an air-dried paper substrate--as is customary in the technical field.
• the present invention also relates to the use of an above-described heat-sensitive recording layer according to the invention (or a heat-sensitive recording layer according to the invention, which is referred to as preferred in this text) for the production of a heat-sensitive recording material, preferably for the production of a heat-sensitive recording material according to the invention (or a heat-sensitive according to the invention recording material designated as preferred in this text).
• the present invention also relates to the use of a heat-sensitive recording material according to the invention described above (or a heat-sensitive recording material according to the invention, which is referred to as preferred in this text) as a flight, train, ship or bus ticket, gambling receipt, parking ticket, label, receipt , self-adhesive label, medical chart paper, fax paper and/or barcode label.
• the above for the heat-sensitive recording layer according to the invention and/or for the according to the invention apply Coating composition and/or for the heat-sensitive recording material according to the invention and/or for the inventive use of a heat-sensitive recording layer according to the invention and/or for the process according to the invention for the production of a heat-sensitive recording material in accordance with the explanations given in each case, and vice versa.
• a raw paper with a mass per unit area of 42 g/m 2 was provided as the paper substrate.
• a coating composition for forming an intermediate layer having a basis weight (dry weight) of 9 g/m 2 was applied on the front side of this paper substrate with a bar coater and dried conventionally. Water was used as the carrier liquid for the coating composition for forming an intermediate layer.
• the components of the coating composition for forming an intermediate layer after drying on the paper substrate (dry weight, see above) and their amounts (in percent by mass based on the dry weight of the coating composition for forming the intermediate layer) are given below in Table 1: ⁇ u>Table ⁇ /u> 1: Components of a coating composition for forming an intermediate layer component Total amount [mass%] Dispersant based on polysiloxane 0.2 - 0.8 strength 1 - 5 Calcined kaolin 65 - 85 Na carboxymethyl cellulose 0.3 - 1 ground calcium carbonate 2 - 10 Styrene butadiene copolymer dispersion 7 - 15
• a coating composition according to the invention (for producing a heat-sensitive recording layer) was prepared by mixing together the ingredients listed below in Table 2, water being used as the carrier liquid.
• the components of the coating composition and their amounts (in percent by mass based on the dry weight of the coating composition) are given in Table 2 below: ⁇ u>Table ⁇ /u> 2: Constituents of a coating composition according to the invention for producing a heat-sensitive recording layer component component Total amount [mass%] K1) 3-di-N-butylamino-6-methyl-7-anilinofluoran (ODB-2) 8 - 12 K2) N -(4-Methylphenylsulfonyl)- N' -(3-(4-methylphenylsulfonyloxy)phenyl)urea (Pergafast 201) 19 - 26 K3) Polyvinyl alcohol, degree of hydrolysis > 80% 10 - 18 K4) octadecanamide 17 K5) Calcium carbonate, finely divided, precipitated 21 -
• compositions according to the invention were prepared in accordance with the preparation process described here above, with the amount of octadecanamide being varied in each case, while the proportion of the other components was not changed.
• the coating compositions prepared in this way, their abbreviations and the total amounts of octadecanamide used in each case (in percent by mass, based on the dry mass of the coating composition) in these coating compositions are given in Table 3 below.
• Table ⁇ /u> 3 Coating compositions according to the invention for producing heat-sensitive recording layers coating composition Total amount of octadecanamide [mass%] BSZE-1 14.0 BSZE-2 16.9 BSZE-3 19.7 BSZE-4 22.2 BSZE-5 24.6 BSZE-6 26.9
• a coating composition according to the invention for the production of a heat-sensitive recording layer was provided (for production see Example 2 above) and a paper substrate which was coated on its front side with an intermediate layer (for production see Example 1 above).
• the coating composition according to the invention was then applied to the intermediate layer of the paper substrate by means of a doctor blade to produce a heat-sensitive recording layer with a mass per unit area of 2.1 g/m 2 (dry mass) and dried conventionally, resulting in a heat-sensitive recording layer according to the invention (arranged on the intermediate layer of the paper substrate) and also a heat-sensitive recording material according to the invention.
• Heat-sensitive recording materials according to the invention Heat-sensitive recording material Coating composition used WAME-1 BSZE-1 WAME -2 BSZE-2 WAME -3 BSZE-3 WAME -4 BSZE-4 WAME -5 BSZE-5 WAME -6 BSZE-6
• a paper substrate coated on its front side with an intermediate layer (prepared as in Example 1) and a conventional coating composition not according to the invention for the production of a heat-sensitive recording layer were provided.
• the conventional coating composition, not according to the invention, for producing a heat-sensitive recording layer was produced by mixing the components listed in Table 5 below with each other, water being used as the carrier liquid.
• the non-inventive coating composition for producing a heat-sensitive recording layer with a mass per unit area of 2.3 g/m 2 (dry mass) was then applied to the intermediate layer of the paper substrate using a doctor blade and dried conventionally. so that a non-inventive heat-sensitive recording layer (located on the interlayer of the paper substrate) as well as a non-inventive heat-sensitive recording material (comparison) resulted.
• the heat-sensitive recording material not according to the invention is hereinafter referred to as "WAMV-1" for short.
• Example 5 Determination of the heat resistance of heat-sensitive recording materials at 60 °C / 24 hours
• the print density was determined with a spectral -Densitometer of the type TECHKON SpectroDens Advanced performed.
• the mean value (“before heating") was formed from the measured values for the black-colored areas ("image") and for the uncolored areas ("background").
• the thermal test prints were then hung in a drying cabinet at 60 °C. After 24 hours, the thermal paper printouts were removed again, cooled to room temperature (23 °C) and the print density was again determined at three points each on the black colored areas and the uncolored areas of the thermal test printouts (averaging and densitometer as described above; " after heating”).
• the permanence of the print image in "%” determined under the test conditions corresponds to the quotient of the mean value formed of the print density of the colored areas "before heating” and after storage in the drying cabinet ("after heating"), multiplied by 100.
• the determined under the test conditions The contrast of the print image in “%” corresponds to the quotient of the mean value of the print density of the uncolored areas ("background”) "before heating” and after storage in the drying cabinet ("after heating”), multiplied by 100.
• Example 6 Determination of the climatic stability of heat-sensitive recording materials at 40 °C/24 hours and 90% RH.
• the print densities on the black were measured analogously to the specification given in Example 5 above colored areas ("image") and for the uncolored areas ("background”) before and after storage in a climatic cabinet (at 40 °C and 90 % RH for 24 hours; instead of storage in a drying cabinet at 60 °C for 24 hours as determined in Example 5).
• Example 7 Determination of the resistance of heat-sensitive recording materials to lanolin (exposure time 10 minutes)
• the print density was determined using a TECHKON SpectroDens Advanced densitometer - spectral densitometer. The mean value was formed from the respective measured values of the black-colored areas and the uncolored areas.
• the created thermal proof of the heat-sensitive recording material to be tested was generously coated with lanolin by hand.
• the lanolin was carefully wiped off and the print density was again measured in three places each on the black colored areas and the uncolored areas of the thermal test prints using a densitometer TECHKON SpectroDens Advanced - spectral densitometer certainly.
• the mean value was formed from the respective measured values of the black-colored areas and the uncolored areas.
• the determined resistance of the thermal prints to lanolin in "%" corresponds to the quotient of the mean value of the print density formed before the lanolin treatment and after the lanolin treatment, multiplied by 100.
• a heat-sensitive recording material according to the invention (WAME-1 to WAME-6) has at least one improvement over a conventional heat-sensitive recording material (WAMV-1). comparable - and in many cases even better - resistance of the printed image to lanolin.
• Example 8 Determination of the resistance of heat-sensitive recording materials to water and aqueous ethanol solution (23 °C, 50% RH, 24 hours)
• test liquids are used to assess the resistance of an image produced on the heat-sensitive recording layer of heat-sensitive recording materials to water or to 25% (v/v) aqueous ethanol solution ("test liquids").
• a drop of distilled water or the selected aqueous 25% ethanol solution was applied to the printed areas produced with the printer ATLANTEK Model 400-Thermal Response Test System with the energy level medium level 10.
• the excess test liquid is dabbed off with a filter paper or cotton cloth and the test sheet is then stored in a room climate (23 °C, 50 % relative humidity) for 24 hours.
• the optical density of the printed areas and their difference were determined with the densitometer TECHKON SpectroDens Advanced - spectral densitometer (mean value from measurements on three printed areas).
• the resistance of the thermal print image on a heat-sensitive recording material in "%" to water or aqueous ethanol solution corresponds to the quotient of the mean value of the print density formed before and after treatment with the respective test liquid, multiplied by 100.
• Example 9 Determination of the resistance of heat-sensitive recording materials to plasticizers of an adhesive film (23 °C, 50% RH)
• the resistance of the thermal print image on a heat-sensitive recording material in "%" to plasticizers contained in a graphic adhesive film corresponds to the quotient of the mean value formed of the print density before application and after application of the graphic adhesive film, multiplied by 100.
• a heat-sensitive recording material according to the invention (WAME-1 to WAME-6) has a print image durability which is at least comparable to that of a conventional heat-sensitive recording material (WAMV-1) and in many cases even improved compared to plasticizers contained in a graphic adhesive film.
• Example 10 Determination of the dynamic print density (or the dynamic sensitivity) of heat-sensitive recording materials
• the sensitivity of a heat-sensitive recording material defines the degree of reaction at a certain energy input. It is usually shown in graphs that show the generated image density or optical density (OD) as a function of the energy or heat supplied.
• Optical density is a measure of the ratio between incident and reflected light.
• An optical density, specified in "Optical Density Units" (ODU), of approx. 1.1 is usually completely black for the human eye. Therefore, lower optical densities result in different shades of gray.
• ODU Optical Density Units
• the dynamic sensitivity (or dynamic print density) of a heat-sensitive recording material indicates how quickly a heat-sensitive recording material can be printed on.
• a heat-sensitive recording material according to the invention (WAME-1 to WAME-6) has a dynamic print density which is at least comparable to a conventional heat-sensitive recording material (WAMV-1) and in some cases even improved .

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