EP3414099A1 - Nouveau révélateur chromogène destiné à un support d'enregistrement thermosensible, et matériau d'enregistrement thermosensible à base de pla - Google Patents

Nouveau révélateur chromogène destiné à un support d'enregistrement thermosensible, et matériau d'enregistrement thermosensible à base de pla

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Publication number
EP3414099A1
EP3414099A1 EP18700648.1A EP18700648A EP3414099A1 EP 3414099 A1 EP3414099 A1 EP 3414099A1 EP 18700648 A EP18700648 A EP 18700648A EP 3414099 A1 EP3414099 A1 EP 3414099A1
Authority
EP
European Patent Office
Prior art keywords
formula
heat
sensitive recording
colour
compound
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP18700648.1A
Other languages
German (de)
English (en)
Inventor
Diana Valentina Becerra Siabato
Nora Wilke
Matthias Neukirch
Martinus Adrianus Getrudus JANSEN
Armin Johannes MICHEL
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi HiTec Paper Europe GmbH
Original Assignee
Mitsubishi HiTec Paper Europe GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP17201462.3A external-priority patent/EP3482963A1/fr
Application filed by Mitsubishi HiTec Paper Europe GmbH filed Critical Mitsubishi HiTec Paper Europe GmbH
Priority to EP19152586.4A priority Critical patent/EP3505358A1/fr
Publication of EP3414099A1 publication Critical patent/EP3414099A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/91—Polymers modified by chemical after-treatment
    • C08G63/912—Polymers modified by chemical after-treatment derived from hydroxycarboxylic acids
    • 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
    • B41M5/333—Colour developing components therefor, e.g. acidic compounds
    • B41M5/3331—Macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
    • C08G63/688—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur
    • C08G63/6882—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur derived from hydroxy carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
    • C09D167/04—Polyesters derived from hydroxycarboxylic acids, e.g. lactones
    • 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]

Definitions

  • the present invention pertains in one aspect to a novel colour developer for a thermo- sensitive recording medium, and related thereto, in a further aspect to a heat-sensitive recording material based on PLA.
  • the present invention is directed to an agent which is capable, upon heating, of reacting with a leuco dye in a colour-forming manner. More particularly, the present invention is directed to a colour developer which comprises an agent which is a macromolecular compound comprising a terminal sulfonyl group, a urea group and a linking group there- between.
  • the colour developer is suitable for inclusion in the colour developing layer of a thermo-sensitive recording medium.
  • the colour developing layer (5) comprises at least i) a colour developer which is usually a weak acid and which donates a proton under the action of heat to ii) a colour former, which is an initially light-coloured or colourless compound but which can change colour with the addition of said proton.
  • the colour developer should have an appropriate melting point to react at the temperatures generated by the thermal head (7) of the printer but should equally be thermally stable at lower temperatures. It will be appreciated that there are also functional constraints on the acidity (pKa value) and solubility of such colour developers, as well as the common, practical need for the colour developer to be of improved economics given the large scale of its application.
  • Well established colour developers include: Bisphenol A; Bisphenol F; Bisphenol AP; Bisphenol S; 4-hydroxy-4'-isopropoxydiphenylsulfones; bis-(3-allyl-4-hydroxyphenyl)- sulfone; phenol-4-[[4-(2-propen-1 -25 yloxy)phenyl]sulfonyl]; 1 ,7-bis(4-hydroxyphenylthio)- 3,5-dioxaheptane; and, the phenol, 4, 4'-sulfonylbispolymer with 1 ,1 '-oxybis[2- chloroethane] (CAS Number 191680-83-8, D90).
  • Palygorskite or attapulgite are a magnesium aluminium phyllosilicate with formula (Mg,AI) 2 Si 4 O 10 (OH)-4(H 2 O) that occurs in a type of clay soil, for example, common to the Southeastern United States.
  • Halloysite is an aluminosilicate clay mineral with the empirical formula AI 2 Si 2 05(OH)4. Its main constituents are aluminium (20.90%), silicon (21 .76%) and hydrogen (1 .56%). Halloysite typically forms by hydrothermal alteration of alumino-silicate minerals. It can occur intermixed with other clay minerals, for example, kaolinite. Further alternatives to bisphenols have also been disclosed in the art.
  • US 2014/0235437 A1 discloses a colour acceptor for chemical reaction with a dye precursor to form a visually recognizable colour: the colour acceptor is constructed of lactic acid monomers.
  • This citation also discloses a heat-sensitive recording material with a substrate and a heatsensitive recording layer, wherein the heat-sensitive recording layer contains at least one dye precursor and at least one colour acceptor - which compounds react with one another in a colour-forming manner when heat is applied - and wherein the colour acceptor is constructed of lactic acid monomers.
  • the invention aims at providing one or more alternative colour developers having improved properties, which enable them to react with a leuco dye under optimized conditions.
  • an agent capable reacting with a leuco dye upon heating wherein said agent meets Formula (A-l):
  • R1 and R2 are independently a hydrogen atom, a C1-C6 alkyl group, a C1- C6 alkoxy group or a halogen atom;
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and, a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • the parameter (a+b) of Formula (A-l) will generally meet the condition 1 ⁇ (a+b) ⁇ 40.
  • the molecular weight of the agent of Formula (A-l) should generally be 8000 or less, for example 6000 or less.
  • R1 , R2, R3, R4, R5 and R6 are independently a hydrogen atom or a C1-C3 alkyl group.
  • R3 and R4 are inde- pendently a hydrogen atom or a methyl group and more preferably R3 is H and R4 is methyl.
  • X is O; R1 and R2 are both methyl and are para- substituents of the phenyl group; and/or 1 ⁇ a ⁇ 10 and 1 ⁇ b ⁇ 10.
  • X is O; R1 and R2 are both methyl and are para- substituents of the phenyl group; and/or 1 ⁇ a ⁇ 10 and 1 ⁇ b ⁇ 10.
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and, a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • the compound of Formula (A-l I) may be obtained by a method comprising acting: i) a compound of the formula
  • R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3- C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and, ii) a cyclic ester of a hydroxycarboxylic acid having the formula
  • R3 and R4 are independently a hydrogen atom, a C1 -C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group.
  • the compound of Formula (A-ll) represents an important starting material for the synthesis of the agent of Formula (A-l). More particularly, the present invention provides a method for producing the agent of Formula (A-l) as defined herein above, said method comprising the steps of: a) providing a compound as defined in Formula (A-ll); and, b) reacting said compound with at least one sulfonyl isocyanate of Formula (A-l II): O
  • R is a hydrogen atom, a C1 -C6 alkyl group, a C1 -C6 alkoxy group or a halogen atom
  • the agents of Formula (A-l) are effective as developers in the colour developing layers of thermosensitive media, in particular thermal papers. They are stable at low temperatures and particularly at temperatures below 40 °C at which thermosensitive media will usually be transported and stored prior to their use.
  • the compounds are stable in aqueous disper- sion for an operable period of time, and their use is not compromised by the environmental concerns which surround the large scale use of bisphenols.
  • the reactants used to obtain compounds of Formula (A- 11 ) - and thus indirectly the agents of Formula (A-l) - can be derived from compounds of biologic origin, such as urea and lactide: as a consequence, it is postulated that the agents of Formula (A-l) may be biodegradable.
  • an aqueous dispersion comprising the agent of Formula (A-l) as defined above.
  • the average particle size of the agent is less than 20 microns, for instance from 0.5 to 10 microns, as measured by dynamic light scattering.
  • thermosen- sitive recording medium having a colour developing layer comprising; a leuco dye; and, a colour developer which reacts with said leuco dye upon heating to form a colour layer, wherein said colour developer comprises an agent as defined herein before and in the appended claims.
  • the leuco dye of the thermosensitive medium is selected from the group consist- ing of: triphenylmethanephthalide leuco compounds; triallylmethane leuco compounds; flu- oran leuco compounds; phenothiazine leuco compounds; thiofluoran leuco compounds; xanthene leuco compounds; indophthalyl leuco compounds; spiropyran leuco compounds; azaphthalide leuco compounds; couromeno-pyrazole leuco compounds; methine leuco compounds; rhodamineanilino-lactam leuco compounds; rhoda- minelactam leuco compounds; quinazoline leuco compounds; diazaxanthene leuco compounds; bis-lactone leuco compounds; and, mixtures thereof.
  • the colour developing layer comprises a fluoran leuco dye.
  • the present invention also provides a method of producing a thermo-sensitive recording medium comprising the steps of: a) providing a preferably planar substrate; b) applying an aqueous coating composition to said substrate, said aqueous coating composition comprising a leuco dye and a dispersed developer which reacts with said leuco dye upon heating; and, c) forming a coating layer by drying the applied aqueous coating composition at a temperature below the minimum reaction temperature of the developer and the leuco dye, wherein said developer comprises the agent as defined above.
  • the substrate will comprise paper.
  • said method may be characterized in that the applied coating composition has a solids content of from 35 to 50 wt.%.
  • C1 -C6 alkyl refers to a monovalent group that contains 1 to 6 carbons atoms, that is a radical of an alkane and includes straight-chain and branched organic groups.
  • alkyl groups include, but are not limited to: methyl; ethyl; propyl; isopropyl; n-butyl; isobutyl; sec-butyl; tert-butyl; n-pentyl; and, n-hexyl.
  • alkyl groups may be unsubstituted or may be substituted with one or more substituents such as halo, nitro, cyano, amido, amino, sulfonyl, sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyi, sulfamide and hydroxy.
  • substituents such as halo, nitro, cyano, amido, amino, sulfonyl, sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyi, sulfamide and hydroxy.
  • C2-C6 alkenyl refers to an aliphatic carbon group that contains 2 to 6 carbon atoms and at least one double bond. Like the aforementioned alkyl group, an alkenyl group can be straight or branched, and may optionally be substituted. Examples of C2-C6 alkenyl groups include, but are not limited to: allyl; isoprenyl; 2-butenyl; and, 2-hexenyl.
  • C3-C6 cycloalkyl is understood to mean a saturated, mono- or bicyclic hydrocarbon group having from 3 to 6 carbon atoms.
  • Examples of cycloalkyl groups include: cyclopropyl; cyclobutyl; cyclopentyl; and, cyclohexyl.
  • lactic acid in this application refers to 2-hydroxypropionic acid with the chemical formula C 3 H 6 0 3 and, unless specified herein, can refer to either stereoisomeric form of lactic acid (L-lactic acid or D-lactic acid).
  • lactide refers to the cyclic diester obtained by dehydrationcondensation of two lactic acid molecules. Lactide exists as three optical isomers: L-lactide formed from two L-lactic acid molecules; D-lactide formed from two D-lactic acid molecules; and, meso-lactide formed from L20 lactic acid and D-lactic acid. Where appropriate, lactoyi units of the compounds of Formulas (A-l) and (A-ll) may be derived from one, two or three of said isomers.
  • said lactoyl units be derived from a source of lactide in which the level of meso-lactide is as low as possible and preferably for said lactide source to consist of L-lactide and/or D-lactide.
  • the lactide consists only of optically pure D-lactide or, preferably, optically pure L-lactide.
  • Instructive disclosures on the preparation of purified lactide include but are not limited to: US Patent No. 6,313,319 B1 (US 6,313,319 B1 ); Japanese Examined Patent Publication No. 51 -6673 (JP S51 -6673 B1 / US 3,597,449 A); Japanese Laid- Open Patent Publication No.
  • JP S63-101378 JP S63-101378 A / EP 0 261 572 A1
  • Japanese Laid-Open Patent Publication No. 6-256340 JP H06-256340 A / DE 44 04 838 A1
  • Japanese Laid-Open Patent Publication No. 7-165753 JP H07-165753 A / EP 0 657 447 A1 .
  • a "catalytic amount” means a sub-stoichiometric amount of catalyst relative to a reactant.
  • solvents are substances capable of dissolving another substance to form a uniform solution; during dissolution neither the solvent nor the dissolved substance undergoes a chemical change. Solvents may either be polar or non-polar.
  • Water for use as a (co-)solvent or carrier herein, is intended to mean water of low solids content as would be understood by a person of ordinary skill in the art.
  • the water may, for instance, be distilled water, demineralized water, deionized water, reverse osmosis water, boiler condensate water, or ultra-filtration water. Tap water may be tolerated in certain circumstances.
  • Hydroxyl (OH) values are measured according to Japan Industrial Standard (JIS) K-1557, 6.4.
  • molecular weights referred to in this specification can be measured with gel permeation chromatography (GPC) using polystyrene calibration standards, such as is done according to ASTM 3536. And molecular weight as given here means “number average molecular weight (Mn)" unless specifically stated otherwise. All percentages, ratios and proportions used herein are given on a weight basis unless otherwise specified.
  • the present invention is primarily directed to an agent capable of reacting with a leuco dye upon heating, wherein said agent meets Formula (A-l):
  • R1 and R2 are independently a hydrogen atom, a C1-C6 alkyl group, a C1- C6 alkoxy group or a halogen atom
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group
  • R1 and R2 are independently a hydrogen atom, a C1-C6 alkyl group, a C1- C6 alkoxy group or a halogen atom
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group
  • X is O, S or NH; and, a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • thermosensitive medium in particular a thermal paper
  • a suitable substrate - of an aqueous coating composition comprising a dispersed developer which reacts with said leuco dye upon heating; in the present invention that developer comprises the agent as defined above and further described herein below.
  • the leuco dye of the colour developing layer may be provided within such an aqueous coating composition or may be applied in- dependently to the substrate.
  • the average particle size of any dispersed agent is less than 20 microns, for example from 0.5 to 10 microns, as measured by dynamic light scattering.
  • the reactive agent in accordance with the present invention and having Formula (A-l) is optimally formed in a two-stage process comprising:
  • R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3- C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and, ii) a cyclic ester of a hydroxycarboxylic acid having the formula
  • R3 and R4 are independently a hydrogen atom, a C1-C6 alkyl group, a C3- C6 cycloalkyl group or a C2-C6 alkenyl group, to thereby form an intermediate compound of Formula (A-l I): b
  • R is a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom.
  • a compound of Formula (A-ll) might alternatively be prepared by grafting of a preformed oligomer, such as a pre-formed polylactide, onto the appropriate starter molecule, such as urea.
  • the polylactide could be derived from either lactide or lactic acid as both alternatives are established in the art.
  • no further mention will be made of said embodiment and the two stage process will be described further below.
  • R3, R4, R5 and R6 as defined above are independently a hydrogen atom or a C1-C3 alkyl group; and, X is O. More preferably, R3 and R4 are independently a hydrogen atom or a methyl group and most preferably R3 is H and R4 is methyl.
  • first stage reactants glycolide, lactide and urea might therefore be mentioned.
  • polymeric blocks of unit lengths a and b may be formed by a ring-opening reaction or a ring opening polymerization of the cyclic ester using an appropriate ionic or nonionic catalyst, as described in Ring Opening Polymerization, Vol.
  • catalysts which may be used alone or in combination, include but are not limited to: amine compounds or salts thereof with carboxylic acids, such as butylamine, octylamine, laurylamine, dibutylamines, mono- ethanolamines, diethanolamines, triethanolamine, diethylenetriamine, triethylenetetra- mine, oleylamines, cyclohexylamine, benzylamine, diethylaminopropylamine, xylylenediamine, triethylenediamine, guanidine, diphenylguanidine, 2,4,6- tris(dimethylaminomethyl)phenol, morpholine, N-methylmorpholine, 2-ethyl-4- methylimidazole and 1 ,8-diazabicyclo-(5,4,0)-undecene-7 (DBU) ; tin 2-
  • catalyst there is no particular limitation on the amount of catalyst used but it will typically be 0.0001 to 5 parts by weight, and preferably from 0.05 to 1 part by weight, based on 100 parts by weight of the cyclic ester.
  • the ring-opening reaction or polymerization reaction can be performed at room temperature but is preferably performed with heating at a temperature of from 100 to 200 °C , or from 130 to 190 °C. If the temperature is lower than 100 °C , the reaction rate is unfa- vorably low. On the other hand, if the temperature is higher than 200 °C, the oligomer degradation rate is increased and low-molecular weight components can vaporize.
  • the reaction should be performed under anhydrous conditions and in the absence of any further compounds having an active hydrogen atom. Exposure to atmospheric moisture may be avoided by providing the reaction vessel with an inert, dry gase- ous blanket. Whilst dry nitrogen, helium and argon may be used as blanket gases, precaution should be used when common nitrogen gases are used as a blanket, because such nitrogen may not be dry enough on account of its susceptibility to moisture entrain- ment; the nitrogen may require an additional drying step before use herein.
  • the process pressure is not critical to the first-stage reaction. As such, the reaction can be run at subatmospheric, atmospheric, or super-atmospheric pressures but pressures at or above atmospheric pressure are preferred.
  • reaction may be performed in solution or in the melt without a solvent.
  • suitable solvents for the reaction should be non-reactive, organic liquids capable of dissolving at least 1 wt.% and preferably over 10 wt.% of the compounds of Formula (A-ll) at 25 °C.
  • the progress of the reaction can be monitored by known methods - for instance by analyzing monomer conversion using gas chromatography or by monitoring the product hydroxyl (OH) values - and the reaction stopped when desired. This aside, the reaction generally requires a time of 0.5 to 12 hours to reach completion, and more commonly from 1 to 6 hours.
  • first stage reaction product - of Formula (A-ll) - may be worked up, using methods known in the art, to isolate and purify the product: for example, any solvent present may be removed by stripping at reduced pressure. That said, it is noted that there is no particular need to work up the first stage reaction product: the second reaction stage may proceed directly from the first stage. Second Stage 2)
  • the intermediate compound of Formula (A-ll) and one or more compounds of Formula (A-lll) are reacted in the second stage of the process.
  • a single compound of Formula (A-lll) is reacted such that the resultant terminal groups of the reactive agent (Formula (A-l)) are the same.
  • This second stage nominally the preparation of a sulfony- lurethane - is an addition reaction and not a polymerization reaction; therefore the molecular weights of the intermediate compound (Formula (A-ll)) and of the or each compound of Formula (A-lll) are determinative of the molecular weight of the reaction product, the compound of Formula (A-l).
  • Exemplary compounds of Formula (A-lll) include phenylsulfonylisocyante, toluenesolyl- sulfonyl isocyanate, and chlorophenylsulfonyl isocyanate.
  • non-hydrogen substitu- ents (R) are present in the compounds of Formula (A-lll)
  • these are preferably para- substituents of the phenyl group.
  • p- toluenesulfonylisocyanate is used as a reactant.
  • the molar ratio of the reactants of Formula (A-ll) and Formula (A-lll) should be selected to ensure the complete conversion of the hydroxyl groups of Formula (A-ll). Generally, the molar ratio of hydroxyl groups to sulfonyl isocyanate groups should be maintained in the range of from 1 :1 to 1 :0.8.
  • the second stage reaction is typically performed in organic solution and under anhydrous conditions.
  • the intermediate compound of Formula (A-ll) is dispersed in a suitable organic solvent and, under stirring, the sulfonyl isocyanate is added thereto either in pure form or in solution.
  • Suitable organic solvents are those capable of dissolving at least 1 wt.% and preferably over 10 wt.% of the reaction product - the compounds of Formula (A-l) - at 25 °C.
  • the compound of Formula (A-lll) may actually be sufficiently reactive towards to the hydroxyl functional, intermediate compound (Formula (A-ll)) that the reaction need not occur either at a significantly elevated temperature or under catalysis.
  • the second stage reaction may be performed at a temperature of from 30 °C or 40 °C to 80 °C and either some cooling of the reaction vessel or the introduction of the reactants at a slow rate may in fact be needed to maintain such low temperatures given the exothermic nature of the reaction. That said, in certain circumstances it may be expedient to employ one or more conventional catalysts which are known to accelerate the isocyanate-hydroxyl reaction.
  • catalyst When employed, there is again no intended limitation on the amount of catalyst which may be used, but it will typically be 0.0001 to 5 parts by weight, and preferably from 0.05 to 1 part by weight, based on 100 parts by weight of hydroxyl functional, intermediate compound (Formula (A-ll).
  • any compound that can catalyze the reaction of a hydroxyl group and an isocyanato group to form a urethane bond can be used.
  • examples thereof include: tin carboxylates; tin alkoxides; tin oxides; reaction products between dibutyltin oxides and phthalic acid esters; dibutyltin bisacetylacetonate; titanates, such as tetrabutyl titanate and tetrapropyl titanate; organoaluminum compounds such as aluminum trisacetylaceto- nate, aluminum trisethylacetoacetate, and diisopropoxyaluminum ethylacetoacetate; chelate compounds such as zirconium tetraacetylacetonate and titanium tetraacetylace- tonate; lead octanoate; amine compounds or salts thereof with carboxylic acids, such as butylamine, octylamine, lau
  • organic tin compounds include: tin(ll) and tin(IV) salts of carboxylic acids, such as tin(ll) acetate, tin (II) 2-ethylhexanoate (tin octanoate), tin(ll) oleate, tin(ll) laurate, dibutyl tin diacetate, dibutyl tin dilaurate, dibutyl tin maleate, dioctyl tin diacetate, dibutyl tin di-2-ethyl hexanoate, tributyl tin acetate and triphenyl tin acetate; tin(IV) alkoxides, such as tributyl tin methoxide, tributyl tin ethoxide
  • carboxylic acids such as tin(ll) acetate, tin (II) 2-ethylhexano
  • tin octanoate may be employed as the catalyst of both the first and second reaction stages. This allows for a "one-pot synthesis", wherein the first and second stages can be performed sequentially without the need to remove any first-stage catalyst from the intermediate product.
  • the progress of the second stage reaction can be monitored by known methods - again including the monitoring of reactant conversion by gas chromatography and by hydroxyl (OH) value measurement - and the reaction stopped upon completion.
  • the reaction generally requires a time of 0.1 to 4 hours to reach completion and more commonly from 0.2 to 2 hours.
  • the output of the second reaction stage may be worked up, using methods known in the art, to isolate and purify the compounds of Formula (A-l): mention in this regard may be made of extraction, evaporation, distillation and chromatography as suitable techniques.
  • the compound of Formula (A-l) is dispersed in an aqueous medium in the presence or absence of a leuco dye.
  • Leuco dyes included as the so-called "colour formers" in the aqueous coating compositions and thermal sensitive recording materials of this invention, are colourless or light coloured basic substances which become coloured when oxidized by acidic substances.
  • Exemplary leuco dyes that can be used herein, either alone or in combination, include: triphenylmethanephthalide leuco compounds; triallylmethane leuco compounds; fluoran leuco compounds; phenothiazine leuco compounds; thiofluoran leuco compounds; xan- thene leuco compounds; indophthalyl leuco compounds; spiropyran leuco compounds; azaphthalide leuco compounds; couromeno-pyrazole leuco compounds; methine leuco compounds; rhodamineanilino-lactam leuco compounds; rhodaminelactam leuco compounds; quinazoline leuco compounds; diazaxanthene leuco compounds; and, bis
  • the aqueous coating composition comprises a leuco base of a triphenylmethane dye as represented by Formula L1 :
  • Rx, Ry, and Rz are independently selected from the group consisting of hydrogen, hydroxyl, halogen, C1-C6 alkyl, nitro and aryl.
  • Specific examples of dyes meeting Formula L1 include: 3,3-bis(pdimethylaminophenyl)-phthalide, 3,3-bis(p-dimethylaminophenyl)-6- dimethylaminophthalide (Crystal Violet Lactone), 3,3-bis(p-dimethylaminophenyl)-6-di- ethylaminophthalide, 3,3-bis(p-dimethylaminophenyl)-5 6-chlorophthalide, and 3,3-bis(p- dibutylaminophenyl)-phthalide.
  • the aqueous coating composition comprises a leuco dye comprises a compound represented by Formula L2:
  • R1 1 and R12 are independently selected from the group consisting of hydrogen, C1-C6 alkyl, substituted phenyl, unsubstituted phenyl, cyanoethyl and, R- halogenated ethyl, or R1 1 and R12 in combination form a cyclic structure and represent— (CH2— )4, ( ⁇ CH2 ⁇ )5; at least one of R13 and R14 is hydrogen and the other is hydrogen, C1-C6 alkyl, aralkyl, amyl, or phenyl;
  • X1 , X2 and X3 each independently selected from the group consisting of hydrogen, C1-C6 alkyl, halogen, halogenated methyl, nitro, amino and substituted 5 amino; and,
  • X4 represents hydrogen, C1-C6 alkyl or C1-C6 alkoxy and n is an integer of from 0 to 4.
  • lactone compounds meeting Formula L2 are: 3-(2'-hydroxy-4'-dime- thylaminophenyl)-3-(2' -methoxy-5'-chlorophenyl)phthalide, 3-(2'-hydroxy-4'-dimethyla- minophenyl)-3-(2'-methoxy-5'-nitrophenylphthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)- 3-(2'-methoxy-5'-methylphenyl)phthalide, and 3-(2'-methoxy-10 4'-dimethylaminophenyl)- 3-(2'-hydroxy-4'-chloro-5'-methylphenyl)-phthalide.
  • the aqueous coating composition comprises a fluoran leuco dye.
  • fluoran leuco dyes include: 3-diethylamino-6-methyl-7-chlorofluoran; 3-pyrroli- dino-6-methyl-7-anilinofluoran; and, 2-[3,6-bis(diethylamino)-9-(0-chloroan- ilino)xanthylbenzoic acid lactam].
  • the dye may be a leuco base of a fluoran dye as represented by Formula L3:
  • Rx, Ry, and Rz are independently selected from the group consisting of hydrogen, hydroxyl, halogen, C1-C6 alkyl, nitro and aryl.
  • leuco dyes conforming to Formula L3 might be mentioned 3-cyclo- hexylamino-6-chlorofluoran, 3-(N-N-diethylamino)-5-methyl-7-(N,N-dibenzylamino) fluoran, 3-dimethylamino-5,7-dimethylfluoran and 3-diethylamino-7-methylfluoran.
  • the amount of said colour developer included in the aqueous coating compositions is preferably selected so that the resultant thermo-sensitive medium comprises the compound of Formula (A-l) in an amount of from 0.5 and 10 parts by weight, relative to 1 part by weight of a basic leuco dye.
  • the colour developer may comprise or consist of the compound of Formula (A-l).
  • the present invention does not preclude the colour developer - and thereby the resultant colour developing layer of the thermosensitive medium - from comprising one or more further compounds which are supplementary to the above defined agent but which can also oxidize the constituent leuco dyes and change the colour thereof.
  • Any co-agent should typically melt at a temperature of from 50 °C to 250 °C and be sparingly soluble in water.
  • Suitable co-agents may be selected from the group consisting of: benzyl paraben; mono- and dihydroxy diphenyl sulfones; acidic clays; phenolic resins; and, salicylic acids and salicylates of lead, aluminum, magnesium, nickel or, preferably zinc.
  • co-agents include: 4,4'-isopropylenediphenol (bisphenol A); p-tert-butylphenol, 2-4-dinitrophenol; 3,4-dichlorophenol; p-phenylphenol; 4,4- cyclohexylidenediphenol; and, 3-tert-butylsalicylic acid, 3,5-tert-butysalicylic acid, 5-a- methylbenzylsalicylic acid and zinc, lead, aluminum, magnesium or nickel salts thereof.
  • bisphenol A 4,4'-isopropylenediphenol
  • p-tert-butylphenol 2-4-dinitrophenol
  • 3,4-dichlorophenol 3,5-tert-butysalicylic acid
  • 5-a- methylbenzylsalicylic acid 5-a- methylbenzylsalicylic acid and zinc, lead, aluminum, magnesium or nickel salts thereof.
  • the amount of co-agent included in the colour developer aqueous coating composition is preferably selected so that the resultant thermosensitive medium comprises from 0.01 to 5 parts by weight thereof, relative to 1 part by weight of basic leuco dye. Whilst the use of bisphenol compounds as co-agent(s) is not precluded in the present invention, it is preferred that the thermosensitive medium comprises less than 0.1 parts by weight of such compounds, relative to 1 part by weight of basic leuco dye.
  • thermosensitive recording medium comprising the steps of: a) providing a preferably planar substrate; b) applying an aqueous coating composition to said substrate, said aqueous coating composition comprising a leuco dye and a dispersed developer which reacts with said leuco dye upon heating; and, c) forming a coating layer by drying the applied aqueous coating composition at a temperature below the minimum reaction temperature of the developer and the leuco dye, wherein said colour developer comprises the agent as defined hereinabove.
  • said method may be characterized in that the applied coating composition in one embodiment of the invention has a solids content of from 35 to 50 wt.%.
  • the said method may be characterized in that the applied coating composition has a solids content of from 20 to 50 wt.%.
  • the shape, structure, size and material of the substrate to be coated will be selected based on what is appropriate for the intended purpose of the thermo-sensitive medium ; no particular limitation is intended here. Exemplary shapes of the substrate includes plates and sheets and, moreover, the substrate may have a single-layer or multi-layer structure. That aside, it is advised that the base layer (2) of the substrate can significantly affect the final characteristics of a thermosensitive medium, such as a thermal paper, and thereby must be carefully chosen on the basis of its optical and mechanical properties.
  • the base layer (2) of the substrate will be selected from the group consisting of: paper, including synthetic paper; cardboard; other fibrous webs; textile materials; and, synthetic resin films.
  • the thickness of the base layer (2) of the substrate will be in the range from 20 to 250 microns.
  • the structural properties of the base layer (2) can be modified by the provision of a backcoat (3) as illustrated in Figure 4.
  • aqueous compositions may be directly coated onto the base layer (2) of the sub- strate.
  • the presence of an intermediate layer (4) is not precluded and indeed may be preferable in some circumstances.
  • the aqueous coating compositions are liquid at their application temperature, said temperature typically being from 20 °C to 50 °C.
  • the liquid might have a corresponding viscosity of from 2,000 to 70,000 centipoises, preferably from 3,000 to 30,000 cP as determined at application temperature using a Brookfield Thermosel Viscometer Model DV-I using a number 27 spindle.
  • the sensitivity of the substrate and, more particularly, of the coating composition to a given tempera- ture may determine which application temperature is applicable. Such physical characteristics as the viscosity and rate of set of the compositions may be varied to accommodate such application
  • Illustrative techniques for the application of the aqueous coating composition to the substrate, in particular for its application in the form of a continuous surface film include but are not limited to: roll coating; spray coating; T-die coating; knife coating; comma coating; curtain coating; dip coating; and, spin coating.
  • the composition might also be applied by dispensing, ink-jet printing, screen printing or offset printing where more localized applica- tion of the coating composition is required or where application is required in a variety of continuous or intermittent forms such as a point, line, triangle, square, circle or arc.
  • the coated substrate is then dried, typically using an air dryer, with close control of the temperature and any air flow, given that the coating is sensitive to heat.
  • the substrate may then be over-coated and/or finished by calendaring, cutting, sheeting and the like. It is quite typical for the colour developing layer (5) to be wholly or partially coated with a protective layer (6) which can protect this recording layer from organic solvents, oils, fats, water, plasticizers and the like.
  • the basis weight of the colour developing layer (5) is typically from 2 g/m 2 to 8 g/m 2 , for example from 2 g/m 2 to 5.0 g/m 2 .
  • thermosensitive medium of the present invention may further comprise one or more of: a sensitizer; a lubricant; a binder; a filler; a pigment; a stabilizer; a dispersant; a de- foamer; a flow modifier; and, an insolubiliser.
  • a sensitizer may be included in the above defined aqueous coating compositions and thereby be included in the colour developing layer: it is preferred, for instance, that the colour developing layer further comprises a sensitizer.
  • these adjunct materials may be included in supplementary layers of the thermosensitive medium: this may be particularly appropriate for binders and pigments, for example. For completeness, it is noted that the inclusion of one of these adjunct materials in the colour developing layer (5) does not preclude the further addition of that adjunct material in such supplementary layers.
  • Sensitizers - sometimes referred to as thermo-sensitivity promoter agents - may be used in the coating compositions and media of the present invention to ensure a good colour density is attained. Without being bound by theory, it is considered that certain sensitizers can assist in the colour forming reaction by forming a eutectic compound with one or more of the colour forming compounds: this brings down the melting point of these compounds and thereby depresses the temperature at which the colour forming reaction takes place.
  • Suitable sensitizers are typically selected from the group consisting of: fatty acid amides, preferably C12-C24 fatty acid amides; methylol compounds of said fatty acid amides; p- hydroxybenzoate acid esters, preferably C1 -C6 alkyl p-hydroxybenzoates; and, mixtures thereof.
  • sensitizers might be mentioned: stearic acid amide; linolenic acid amide; lauric acid amide, myristic acid amide; methylenebis (stearamide); ethylenebis (stearamide); methyl p-hydroxybenzoate; n-propyl p-hydroxybenzoate; iso- propyl p-hydroxybenzoate; and, benzyl p-hydroxybenzoate.
  • the amount of sensitizer used is preferably selected so that the thermosensitive medium comprises from 0.5 to 10 parts by weight relative to 1 part by weight of a basic leuco dye.
  • Lubricants are often added to a thermosensitive medium to ensure that thermal heads contacting the medium are not abraded or worn down.
  • suitable lubricants are: linseed oil; tung oil; paraffin wax; oxidized paraffin wax; polyethylene wax; chlorinated paraffin wax; castor wax; metal salts of higher fatty acids, such as calcium stearate and zinc stearate; and, stearic acid amide.
  • Binders can often constitute an important ingredient of the aqueous coating composition used to form the colour developing layer: the inclusion of a binder may be determinative of the viscosity, rheology, water release properties and set time for the aqueous coating composition. Furthermore, binders may be important to the structural integrity of the overall thermosensitive medium, particularly where pigments and/or fillers are also included therein.
  • the binders may be water-soluble, emulsion or latex polymers.
  • water soluble binders considered suitable for the coating compositions and thermosensitive recording media of the present invention include: polyvinyl alcohol; starch and starch derivatives; cellulose derivatives, such as methoxycellulose, hydroxyethylcel- lulose, carboxymethylcellulose, methylcellulose, and ethylcellulose; sodium salts of polyacrylic acid; polyvinylpyrrolidone; acrylamide-acrylate copolymer; acrylamide- acrylatemethacrylic acid copolymer; alkali salts of styrene-maleic anhydride copolymer; alkali salts of isobutylenemaleic anhydride copolymer; polyacrylamide; sodium alginate; gelatin, and, casein.
  • Exemplary, but nonlimiting, emulsion polymers for use as binders in the present invention include: polyvinyl acetate; polyurethane; polyacrylic acid; polyacry- late; vinyl chloride-vinyl acetate copolymer; polybuthylmethacrylate; and, ethylene-vinyl acetate copolymer.
  • exemplary latex polymers include styrene-butadiene copolymers and styrene-butadiene-acrylate copolymers.
  • any fillers and pigments used in the thermosensitive medium should conventionally be finely pulverized.
  • such fillers and pigments be characterized by: a mean particle diameter of less than 10 ⁇ , preferably less than 5 ⁇ ; a maximum specific surface area of 150 m 2 /g; and/or, an oil absorption of at least 150 ml / 100 g.
  • typical examples include: calcium carbonate; silica; alumina; magnesia; kaolin; talc; diatomaceous earth; barium sulfate; aluminum stearate; and, mixtures thereof.
  • the thermo-sensitive medium should preferably contain, in total, from 0.5 to 10 parts by weight of particulate fillers and pigments relative to 1 part by weight of basic leuco dye.
  • the heat-sensitive recording material according to the invention has a pigment-containing intermediate layer (4) arranged between the substrate and the heat-sensitive recording layer.
  • an intermediate layer of this type can positively contribute to the levelling of the surface to be coated so that the required amount of coating composition to be applied for the heat-sensitive recording layer is reduced.
  • levelling coating devices - such as roller coating units, knife coating units, and (roll) doctor coating units - are preferable for applying the pigmented intermediate layer.
  • the pigments of this intermediate layer can absorb any wax constituents of the heat-sensitive recording layer which are liquefied by the heating effect during induced recording.
  • the basis weight of such a pigment containing intermediate layer is suitably from 5 g/m 2 to 20 g/m 2 , preferably from 5 g/m 2 to 10 g/m 2 .
  • thermosensitive recording medium (1 ) comprising: a planar, paper base layer (2) having a thickness of from 20 to 250 microns; and, a colour developing layer (5) having a basis weight of from 2 g/m 2 to 8 g/m 2 and containing a fluoran leuco dye and a developer which reacts with said fluoro leuco dye upon heating to form a colour layer, wherein said developer is characterized in that it comprises an agent meeting Formula (A-l):
  • R1 and R2 are independently a hydrogen atom or a C1-C3 alkyl group disposed as a parasubstituent of the phenyl group;
  • R3 and R4 are independently a hydrogen atom or a methyl group
  • R5 and R6 are independently a hydrogen atom or a C1-C3 alkyl group
  • X is O; and, a and b are integer values wherein 1 ⁇ a ⁇ 10 and 1 ⁇ b ⁇ 10.
  • Puralact B3 Available from Corbion Purac B.V.
  • Urea and Puralact B3 were loaded into a reaction vessel under a nitrogen atmosphere.
  • the vessel was heated to 150 °C and 100 ppm of tin octoate catalyst was added thereto. The temperature of the vessel was then raised to 180 °C and the reaction allowed to proceed for approximately 6 hours.
  • the vessel was cooled to 60 °C, MEK was added thereto and then p-toluenesulfonylisocyanate was added slowly to the reaction mixture over time to ensure the reaction temperature remained between 60 and 70 °C. Following the addition of the p-toluenesulfonylisocyanate, the reaction was allowed to proceed under stirring for a further 1 hour. The MEK was then removed under vacuum.
  • the present invention relates to a coating composition for forming a heat-sensitive recording material or heat-sensitive recording layer, comprising one or more dye precursors and one or more colour developers based on lactic acid units, and also to a coating colour for forming a coating composition or a heat-sensitive recording layer, comprising one or more dye precursors and one or more colour developers based on lactic acid units, and further to a heat-sensitive recording material comprising a supporting substrate and a heat-sensitive recording layer of the invention, and also to a method of forming this heat-sensitive recording material and to the use of this heat- sensitive recording material.
  • the present invention here also relates to such a coating composition or heat-sensitive recording layer as further contains at least one further colour developer not based on lactic acid units.
  • the invention lastly also relates to a compound based on lactic acid units, preferably for use as a colour developer in the above context, to such a use itself, and to a method of forming this compound based on lactic acid units.
  • Heat-sensitive recording materials have been around for many years and are very popular.
  • One of the reasons for their popularity is that their use is associated with the advantage that the colour-forming components reside in the recording material itself, allowing the use of printers that are free from toner and ink cartridges. It is accordingly no longer necessary to purchase and/or refill toner or ink cartridges.
  • This innovative technology has thus become substantially all pervasive, particularly in public transport, public and/or cultural events, logistics, mail order, the gaming or gambling industry, biomedical engineering as well as the retail trade.
  • EP 2 574 645 A1 proposes a novel colour acceptor for chemical reaction with a dye precursor to form a visually discernible colour wherein the colour acceptor is constructed from lactic acid monomers, attention being drawn to the fact that polylactic acid is fully biodegradable. Since the lactic acid polymer, in addition to an entirely hydroxyl group, contains at the two ends of its long molecules but one carboxyl group as potential reactant with the dye precursors, there is a further proposal to increase the number of useful carboxyl groups by grouping the oligomers of polylactic acid n-fold around an n- basic acid, preferably a dibasic acid.
  • Examples recited in respect of such a preferred dibasic acid are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid and hexadecanedioic acid.
  • oxalic acid malonic acid
  • succinic acid glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid and hexadecanedioic acid.
  • a heat-sensitive recording material is formulated by addition of potentiating compounds so as to increase the printing density (i.e. the desired blackness or jetness) of the thermal printout versus a heat-sensitive recording material without such potentiating compounds.
  • a person skilled in the art typically uses a densitometer to determine the printing density of a thermal printout.
  • EP 2 784 133 A1 proposes for this a composition for forming a visually discernible colour that comprises or consists of the components a) one, two, three or more colour developer compounds each comprising one, two, three or more than three structural units of formula (B-l)
  • n in any one of the structural units of formula (I) is an integer above 1 , the particular value being independent of the value in any other structural unit of formula (B-l),
  • a further challenge especially when partial, preferably very substantial, but more preferably ideally full biodegradability is required, consists in a printed heat-sensitive recording material being exposed to a multiplicity of different environmental influences, such as moisture, heat or chemicals, in the course of its typical use as lottery ticket, entrance ticket, travel ticket, pay & display car park ticket and the like.
  • the composition or the heat-sensitive recording material shall be obtainable at commercially acceptable expense.
  • heat-sensitive recording materials may come into contact with a multiplicity of different substances that can affect the durability of the thermal printout.
  • These in addition to water and organic solvents, also include fats and oils which, for example, are present in hand care products and may become transferred to the heat-sensitive recording material on touching the latter. Particularly the durability against fats and oils is therefore very relevant.
  • the heat-sensitive recording material should be easily and energy-sparingly printable in order that little energy is consumed in the case of mobile applications for example.
  • the printed image should last after printing and the action of heat should cause neither the printed image to fade nor the unprinted background to discolour, resulting in the print ceasing to be legible.
  • Pay & display car park tickets which, once printed, are displayed behind the windscreen and thereby become exposed in the summer to high temperatures and direct sunlight, are an example of where thermal durability is extremely relevant.
  • the durability of the heat-sensitive recording material is very important. Especially when it has to be supposed that the heat- sensitive recording materials may come into contact with moisture, for example when the recording materials used as concert ticket, flight ticket or purchase receipt are kept close to the body (in the trouser pocket for example) and thereby may come into contact with perspiration, it has to be ensured that the recording materials remain readily legible even after any contact with moisture.
  • heat-sensitive recording materials used as flight tickets and entrance tickets for example - which are offset printed in particular.
  • the heat-sensitive recording material is initially printed in a large number of copies with any unalterable data, for example with the company logo, pictures and text to create a heat-sensitive blank (a ticket blank for example).
  • the heat-sensitive blanks obtained are loaded into a thermal printer at the point of sale and can then be individually thermoprinted with data before the individualized recording material is handed to the final customer.
  • These data may vary with every printing operation, for example in date, event name, seat number, card number, mass, price, etc.
  • R1 and R2 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom;
  • R3, R4, R5 and R6 are each independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and a and b are integers satisfying the conditions a > 0, b > 0 and (a + b) > 1.
  • the unpublished patent application referred to also describes a method of forming such compounds, which comprises the reaction of i) a compound of the formula
  • R5 and R6 are each independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyi group or a C2-C6 alkenyl group;
  • X is O, S or NH; and ii) a cyclic ester of a hydroxy carboxylic acid having the formula
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyi group or a C2-C6 alkenyl group, to obtain initially a compound conforming to "Formula (II)":
  • R3, R4, R5 and R6 are each independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyi group or a C2-C6 alkenyl group;
  • X is O, S or NH; and
  • a and b are integers satisfying the conditions a > 0, b > 0 and (a + b) > 1 .
  • a method of forming the agent of "Formula (I) said method comprising the steps of: a) providing a compound of "Formula (II)”; and b) reacting the said compound with at least one sulfonyl isocyanate of "Formula (III)”:
  • R is a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom.
  • the first stage of this process may lead to the formation of polymeric blocks of unit lengths a and b via a ring-opening reaction or a ring-opening polymerization of the cyclic ester by using a suitable ionic or non-ionic catalyst, as described in "Ring Opening Polymerization", Vol. I, pages 461-521 , K.J. Ivin and T. Saegusa (1984).
  • the ring-opening or polymerization reaction may be carried out at room temperature, but is preferably carried out by heating at a temperature of 100 to 200 °C or of 130 to 190 °C.
  • the temperature is lower than 100 °C, the reaction rate is disadvantageous ⁇ low.
  • the temperature is higher than 200 °C, the oligomer degradation rate is increased and low molecular weight components may vaporize. What is important is that the reaction should be carried out under anhydrous conditions and in the absence of further compounds having an active hydrogen atom. Exposure to atmospheric moisture may be avoided by providing an inert, dry gaseous blanket to the reaction vessel.
  • the intermediate of "Formula (II)" and one or more compounds of “Formula (III)” are reacted in the second stage of the process.
  • a single compound of "Formula (III)” is reacted such that the resulting terminal groups of the reactive agent ("Formula (I)") are identical.
  • This second stage - nominally the formation of a sulfonylurethane - is an addition reaction and not a polymerization reaction; it is therefore the molecular weights of the intermediate (“Formula (II)") and of the or each compound of "Formula (III)” which determine the molecular weight of the reaction product, the compound of "Formula (I)".
  • Exemplary compounds of "Formula (III)" include phenylsulfonyl isocyanate, toluenesulfonyl isocyanate and chlorophenylsulfonyl isocyanate.
  • Methods of forming suitable aromatic sulfonyl isocyanates and their chemical behaviour are described inter alia in: H. Ulrich Chem. Soc. Rev. 65, pages 369-376 (1965); U.S. Patent No. 2,666,787 (US 2,666,787 A); and U.S. Patent No. 3,484,466 (US 3,484,466 A).
  • the reaction of the second stage is typically carried out in an organic solvent and under anhydrous conditions.
  • the intermediate of "Formula (II)" is dispersed in a suitable organic solvent and then the sulfonyl isocyanate is admixed under agitation either in pure form or in solution.
  • the reaction of the second stage may be carried out at a temperature of 30 °C or 40 °C to 80 °C and either a certain amount of reaction vessel cooling or the introduction of the reactants at a slow rate of admixture may be required in order that such low temperatures may be maintained given the exothermic nature of the reaction.
  • a preferable embodiment of the invention shall more particularly provide a heat-sensitive recording material which, in the printed state, also has good durability to fats and oils.
  • a coating composition for forming a heat-sensitive recording material or a heat-sensitive recording layer comprising one or more dye precursors
  • the one or at least one colour developer of the two or more colour developers is a compound which in the colour developer contains
  • R1 and R2 are each independently a hydrogen atom, a C1 -C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • R3 and R4 are each independently a hydrogen atom, a C1 -C6 alkyl group, a C1 -C6 alkoxy group or a halogen atom ; and
  • a and b are each an integer and satisfy the conditions a > 0, b > 0 and (a+b) > 1 .
  • the colour developer may contain at least one of the terminal electron acceptor groups with one of the structural units of formula (lb),
  • Lactic acid and compounds derived therefrom are already well known in the prior art.
  • Lactic acid is a hydroxy carboxylic acid having a hydroxyl group as well as a carboxyl group and therefore is known inter alia as 2-hydroxypropionic acid and has the lUPAC nomenclature name of 2-hydroxypropanoic acid .
  • the salts and esters of lactic acid are known as lactates.
  • Customary names for lactic acid in the prior art are: 2-hydroxypropanoic acid, 2-hydroxypropionic acid , (R)-lactic acid, (S)-lactic acid, (RS)-lactic acid, DL-lactic acid, ( ⁇ )-lactic acid, and E 270.
  • D-(-)-lactic acid (interchangeably: (R)-lactic acid)
  • L-(+)-lactic acid (interchangeably: (S)-lactic acid) are also referred to as laevorotatory lactic acid and dextrorotatory lactic acid, respectively.
  • Racemic lactic acid is a 1 : 1 mixture of (R)- and (S)-lactic acid (D-/L-lactic acid).
  • Lactic acid appears under the following Chemical Abstracts Service Registry Numbers: CAS® RN 50- 21 -5 (lactic acid, general), CAS® RN 598-82-3 (dl-form), CAS® RN 10326-41 -7 (d-form) and CAS RN 79-33-4 (l-form).
  • the Chemical Abstracts Service Registry Number, CAS ® RN is a designation for a Registry Number (RN) used by the Chemical Abstracts Service (CAS) since 1965 to unambiguously identify chemical entities.
  • Lactic acid is capable of intermolecular formation of esters. Water is eliminated to form, for example as a dimer, lactoyllactic acid which on prolonged standing or on heating undergoes further esterification to polylactic acid. Lactic acid is manufactured industrially, particularly for use in the food industry and also for formation of polylactides (PLAs; also: polylactic acids). Lactic acid is preferably produced biotechnologically via a fermentation of carbohydrates (sugar, starch). About 70 to 90 % of current global lactic acid production is by the fermentative route. In addition, lactic acid can also be manufactured synthetically on the basis of petrochemical feedstocks (acetaldehyde).
  • Lactic acid is the monomer of the polylactides or polylactic acids (PLAs), which are widely used as biodegradable bioplastics.
  • PLA is biodegradable by virtue of its molecular structure, although certain environmental conditions are needed for biodegradability, which are generally found in industrial composting facilities.
  • Lactide is the cyclic diester of lactic acid and used as starting material in the industrial production of polylactides (polylactic acids). Lactide is obtainable by acid-catalytic condensation of lactic acid. Industrially, however, it is these days mostly derived biotechnologically from glucose and molasses. Since lactide contains two stereocentres each substituted by analogous moieties, there are three isomeric lactides: (S,S)-lactide, (R.R)-lactide and (meso)-lactide.
  • the lactide of the natural L-lactic acid [interchangeably: (S)-lactic acid] has (S,S)-configuration.
  • (R.R)-Lactide and (meso)-lactide are not very important by comparison with (S.S)-lactide.
  • Lactide is a colourless, odourless powder which on contact with water immediately hydrolyses into lactic acid.
  • the lactide [or more precisely: the (S,S)-lactide] of L-lactic acid converts into polylactide by ionic polymerization.
  • Polylactides also called polylactic acids (PLAs for short), are synthetic polymers which are members of the family of polyesters. They are constructed of chemically interbonded lactic acid molecules. So the customary designation of "polylactic acid” is actually misleading, since what it refers to is not a polymer having a plurality of acidic groups. Polylactides are by virtue of the asymmetrical carbon atom optically active polymers and exist in the form of D- or as L-lactides depending on whether they derive from L-(+)-lactic acid [interchangeably: (S)-(+)-lactic acid] or from D-(-)-lactic acid [interchangeably: (R)-(- )-lactic acid].
  • polylactides depend chiefly on the molecular mass, the crystallinity and the proportion of any copolymer. A higher molecular mass raises the glass transition and melting temperatures, the tensile strength and also the modulus of elasticity (E-modulus) and lowers the elongation at break. The methyl group renders the material water-repellent (hydrophobic), thereby reducing the water absorption and thus also the hydrolysis rate of the principal bonding.
  • Polylactides are further soluble in many organic solvents (e.g. dichloromethane, trichloromethane; it can be reprecipitated by admixing a solvent such as ethanol in which the polylactide is less soluble).
  • PLA has numerous properties making it advantageous for many and varied fields of use: A low degree of moisture absorption coupled with a high capillary effect, hence suitable for sports and functional apparel. A low flammability, high UV resistance and colour fastness. Moreover, the density of PLA is relatively low. Bending strength is 0.89-1 .03 MPa. UV resistance is to be understood as meaning that PLA-based products can be exposed to sunlight and other sources of ultraviolet radiation (UV radiation) without being damaged by being irradiated. UV radiation refers to that part of the electromagnetic spectrum between visible light and x- rays.
  • Polylactides and polylactic acids are obtainable by different methods of synthesis. Polylactides are chiefly obtainable by the ionic polymerization of lactide, a ring-shaped union of two lactic acid molecules. Whereas polylactides are produced by ring-opening polymerization, polylactic acids are formed by direct condensation reactions. Conversion of lactide (left) into polylactide (right) by thermal and catalytic ring-opening polymerization. The formation of polylactides and/or polylactic acids is described in the prior art; see for instance D. Garlotta, "A Literature Review of Poly(Lactic Acid)", Journal of Polymers and the Environment, Vol. 9, No. 2, April 2001 , 63-84 ( ⁇ 2002).
  • the conditions, especially the temperatures, in the formation of polylactides and/or polylactic acids are dependent on the catalysts used for polymerization.
  • a ring-opening polymerization will take place for example at temperatures between 120 and 150 °C and also through the agency of catalytic tin compounds (e.g. tin oxide).
  • Temperatures can be for example T ⁇ 100 °C for cationic polymerization and T « 120 °C for anionic polymerization.
  • high molecular weight and pure polylactides are obtainable directly from lactic acid by using the so-called polycondensation. At industrial scale, however, the disposal of the solvent is problematic.
  • a coating composition for forming a heat-sensitive recording material or a heat-sensitive recording layer as defined above may be preferable wherein the one or the at least one colour developer of the two or more colour developers of formula (B-l) is a compound which contains a structural unit of formula (B-lc),
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom. It is thus selected iminourea-, urea- or thiourea- containing colour developer structures which are present in the invention.
  • a coating composition or heat-sensitive recording layer as defined above, comprising a colour developer of formula (B-l) may be preferable wherein the colour developer has one or two terminal electron acceptors having a structural unit of formula (B-lb),
  • the preference in the invention is in some cases for a coating composition or heat-sensitive recording layer as defined above wherein the particle sizes, measured by laser diffraction for the one or at least one of the more than one colour developers are each independently in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ .
  • the preference in the invention is in some cases for a coating composition or heat-sensitive recording layer as defined above wherein the particle sizes measured as the X50 value by laser diffraction for the one or at least one of the more than one colour developers are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1 .7 ⁇ and more preferably in the range from 0.85 to 1 .65 ⁇ .
  • the particle sizes can be determined by use of laser diffraction (HELOS particle size analysis).
  • HELOS particle size analysis An R1 Helos (H1453) & Quixel instrument from Sympatec GmbH was used in the context of the invention (analysis by WINDOX 4).
  • the average particle size can be determined by particle size analysis in the laser diffraction method of DIN/ISO 13320-1 [1999].
  • a laser scattered light spectrometer operates in the measurement range from 0.01 ⁇ to 3000 ⁇ on the basis of the statistical laser light scattering standardized in DIN/ISO 13320-1 [1999]. The instrument does not have to be reset for this.
  • the automated measurement is prepared by placing the particle sample into a circulation unit for wet measurement.
  • An integrated ultrasonic probe prevents particle reticulation and makes an external form of sample preparation superfluous.
  • the interaction of laser light with particles creates, by diffraction, refraction, reflection and absorption, scattered light patterns characteristic of the particle size. Mie theory allows the particle size distribution to be deduced from these scattered light patterns.
  • particle size distributions are determined by measuring the angle dependence of the intensity of scattered light from a laser beam passing through a dispersed silica particle sample. Large particles here scatter light at small angles relative to the laser beam, whereas small particles lead to large scattering angles.
  • the data for the angle-dependent scattered light intensity are analysed and used as a basis for computing the size of the particles responsible for the diffraction pattern.
  • Mie theory is used for this.
  • the particle size is reported as the diameter of the sphere having the same volume.
  • the scattered light theory developed by Mie in 1908 is based on the supposition that the scattered light pattern generated by a particle displays characteristic features which, given knowledge of the optical parameters, enable an unambiguous assignment of size.
  • a coating composition or heat-sensitive recording layer as defined above comprising at least one colour developer which is a phenol-free compound.
  • the at least one colour developer is then a so-called phenol-free colour developer.
  • phenol-free compound herein also comprehends mixtures of phenol-free compounds and/or the term “phenol-free colour developer” herein also comprehends mixtures of phenol-free colour developers.
  • phenol-free compound and/or “phenol-free colour developer” are meant such compounds which as degradation products preferably release nothing by way of phenols into the environment, but at least not significant amounts of phenols, i.e. amounts of phenols which impair the environment and/or are at most below statutory limiting values. This is desirable because biodegradability is very poor for many phenols while phenols are very harmful to water courses and even in minimal concentrations impair the taste of water and fish. Phenols therefore have to be very substantially removed from wastewater.
  • a coating composition or heat-sensitive recording layer as defined above comprising at least one phenol-free colour developer or a mixture of phenol-free colour developers.
  • a sometimes preferred coating composition or heat-sensitive recording layer containing at least one phenol-free colour developer may in addition to the compound of formula (B-l) include one or more further non-phenolic colour developers, preferably selected from the group of sulfonylureas, more preferably N'-(p-toluenesulfonyl)-N'-phenylurea, N-(p- toluenesulfonyl)-N'-3-(p-toluenesulphonyloxyphenyl)urea (A/-(4-methylphenylsulfonyl)-/V- (3-(4-methylphenylsulfonyloxy)phenyl)urea, Pergafast ® 201 ), and/or 4,4'-bis(p- to
  • NKK has an alpha form and a beta form, the alpha form having a melting point of 158 °C and the beta form having a melting point of 175 °C. Furthermore, NKK alpha is in a crystalline form having an absorption band at 3322 and 3229 cm “1 in the IR spectrum and NKK beta is in a crystalline form which has an absorption band at 3401 ⁇ 20 cm "1 in the IR spectrum.
  • the preference of the present invention may thus be for a coating composition or heat- sensitive recording layer as defined above that further contains at least one further colour developer of formula (B-l I) ,
  • the compound of formula (B-l I) is likewise already known, being described in EP 2 923 851 A1 for example. It is marketed under the designation NKK (N-(2-(3- phenylureido)phenyl)benzenesulfonamide).
  • NKK N-(2-(3- phenylureido)phenyl)benzenesulfonamide).
  • the addition of minimal amounts of the compound of formula (B-l I) to the subject invention compound of formula (B-l) may, if necessary or desired, stabilize an even already good durability to moisture for even prolonged periods, so this durability to moisture is maintained.
  • the preference of the present invention may thus be for a coating composition or heat-sensitive recording layer as defined above that further contains at least one further colour developer of formula B-l II),
  • the compound of formula (B-lll) is the already known compound ⁇ /-(4- methylphenylsulfonyl)-/V-(3-(4-methylphenylsulfonyloxy)phenyl)urea, which is marketed under the designation Pergafast ® 201 and is described in EP 1 140 515 B1 for example.
  • Pergafast ® 201 is the most frequently used phenol-free colour developer.
  • the addition of minimal amounts of the compound of formula (B-XVI) to the subject invention compound of formula (B-l) or of formula (B-l I) may, if necessary or desired, improve the durability to fats and oils.
  • the preference of the invention is likewise in some cases for a coating composition or heat-sensitive recording layer according to an above described and defined type wherein the proportion of the colour developer of a colour developer mixture in the coating composition or heat-sensitive recording layer is, for example, at least 10 wt.%, especially at least 15 or 20 wt.%, and/or up to not more than 65 wt.%, especially up to not more than 60 wt.%, and preferably is 24 to 60 wt.%, preferably 35 to 58 wt.%, more preferably 39 to 56 wt.%, based on the entire solids content of the coating composition or heat-sensitive recording layer.
  • the preference of the invention is further for a coating composition or heat-sensitive recording layer as defined above and additionally comprising one or more constituents from the group consisting of sensitizers, pigments, dispersants, antioxidants, release agents, defoamers, light stabilizers and brighteners.
  • the preference of the invention is further for a coating composition or heat-sensitive recording layer as defined above and independently or combined with an above coating composition or heat-sensitive recording layer additionally comprising one or more constituents from the group consisting of sensitizers, pigments, dispersants, antioxidants, release agents, defoamers, light stabilizers and brighteners, wherein the coating composition or heat-sensitive recording layer comprises a sensitizer selected from the group consisting of benzyl naphthyl ether (BNE), diphenyl sulfone (DPS), ethylene glycol m-tolyl ether (EGTE), ethylene glycol phenoxyethane (EGPE), 1 ,2-di(m- methylphenoxy)ethane (DMPE) and 1 ,2-diphenoxyethane (DPE), or a combination thereof.
  • BNE benzyl naphthyl ether
  • DPS diphenyl sulfone
  • EGTE ethylene glycol m-tolyl ether
  • pigments may be provided in the coating composition on a regular basis in order that favourable values may be obtained and ensured for the customary paper parameters.
  • the preference of the present invention is for a coating composition or heat-sensitive recording material wherein the supporting substrate is paper, synthetic paper or self- supporting polymeric film/sheeting.
  • Coating basepaper which has not been surface treated is particularly preferable for use as supporting substrate by reason of its good recyclability and good environmental compatibility.
  • Coating basepaper which has not been surface treated is coating basepaper which has not been treated in a size press or in a coating apparatus.
  • Self-supporting film/sheeting of polypropylene or other polyolefins are preferable for use as self-supporting polymeric film/sheeting.
  • the preference of the present invention is also for papers coated with one or more polyolefins (especially polypropylene).
  • the supporting substrate is paper having a recycled-fibre content of not less than 70 wt.%, based on the overall fibre content of the paper.
  • a heat-sensitive recording material additionally comprising an interlayer between the supporting substrate and the heat-sensitive recording layer, wherein the interlayer preferably contains pigments.
  • the pigments may comprise organic pigments, inorganic pigments or a mixture of organic pigments and inorganic pigments.
  • the basis weight of the interlayer is in the range from 5 to 20 g/m 2 , preferably in the range from 7 to 12 g/m 2 .
  • the interlayer contains pigments
  • preference in one embodiment of the invention is for organic pigments, preferably hollow-body organic pigments.
  • organic pigments preferably hollow-body organic pigments.
  • An increased level of heat reflection for the interlayer endowed with organic pigments enhances the heat response of the heat-sensitive recording layer, since incident thermal radiation is at least partly reflected into the heat-sensitive recording layer instead of being conducted onto the supporting substrate.
  • the sensitivity and the resolving power of the heat-sensitive recording material are distinctly up and the printing speed in the thermal printer is also increased.
  • energy consumption during printing decreases, which is advantageous with mobile devices in particular.
  • Hollow-body pigments contain air on the inside, as a result of which they typically have a still higher level of heat reflection and the sensitivity and the resolving power of the heat-sensitive recording material are still further enhanced.
  • the preference of an alternative embodiment of the invention is for the pigments to comprise inorganic pigments, preferably selected from the list consisting of calcinated kaolin, silica, bentonite, calcium carbonate, alumina and boehmite.
  • inorganic pigments When inorganic pigments are incorporated in the interlayer between the recording layer and the substrate, these pigments are capable, at the script formation stage, of absorbing the constituents (waxes for example) of the heat-sensitive recording layer which are liquefied by the heating effect of the thermal head, and thereby promote a yet faster and more consistent performance of the heat-induced recording.
  • Calcinated kaolin will be found particularly advantageous owing to its large absorption reservoir in the cavities. Mixtures of two or more different inorganic pigments are also conceivable.
  • the quantitative ratio between organic and inorganic pigment is a compromise between the effects engendered by the two types of pigment, which is resolved in a particularly advantageous manner when the pigment mixture consists to 5-30 wt.% or preferably to 8-20 wt.% of organic pigment and to 95-70 wt.% or preferably to 92-80 wt.% of inorganic pigment.
  • Pigment mixtures of different organic pigments and/or inorganic pigments are conceivable.
  • the preference of the present invention is a coating composition or heat-sensitive recording material wherein the interlayer in addition to the inorganic and/or organic pigments optionally contains at least one binder preferably based on a synthetic polymer, in which case styrene-butadiene latex delivers particularly good results.
  • a synthetic binder admixed with at least one natural polymer such as, with particular preference, starch
  • at least one natural polymer such as, with particular preference, starch
  • tests involving inorganic pigments have further shown that a binder-pigment ratio between 3:7 and 1 :9 within the interlayer, both based on wt.% in the interlayer, constitutes a particularly suitable embodiment.
  • the preference of the present invention is a coating composition or heat-sensitive recording material wherein the colour former is selected from derivatives of compounds from the group consisting of fluoran, phthalide, lactam, triphenylmethane, phenothiazine and spiropyran.
  • a preferred coating composition or heat-sensitive recording material in the present invention preferably includes colour former compounds of the fluoran type 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'-xanthen]-3-one; ODB-7), 3-di-n-pentyl-amino-6-methyl-7- anilinofluoran, 3-(diethylamino)-6-methyl-7-(3-methylphenylamino)fluoran, 3-di-n- butylamino-7-(2-chloranilino)fluoran, 3-diethylamin
  • the invention gives particular preference to a coating composition or heat-sensitive recording material wherein the colour former is selected from the group consisting of 3-N-di-n-butylamine-6-methyl-7-anilinofluoran (ODB-2) and 3-(N-ethyl-N-isopentylamino)- 6-methyl-7-anilinofluoran.
  • the colour former is selected from the group consisting of 3-N-di-n-butylamine-6-methyl-7-anilinofluoran (ODB-2) and 3-(N-ethyl-N-isopentylamino)- 6-methyl-7-anilinofluoran.
  • the preference in the invention is a coating composition or heat-sensitive recording material wherein the coating composition or heat-sensitive recording layer contains a sensitizer.
  • the sensitizer When a sensitizer is used, the sensitizer first melts during the supply of heat during the printing process and the molten sensitizer dissolves the colour former and colour developer compounds present side by side in the coating composition or heat-sensitive recording layer, and/or lowers the melting temperature of the colour former and colour developer compounds to induce a colour-developing reaction.
  • the sensitizer itself plays no part in the colour-developing reaction.
  • Sensitizer accordingly refers to substances used to establish the melting temperature of the coating composition or heat-sensitive recording layer and preferably capable of establishing a melting temperature of about 70 to 80 °C, without the sensitizers themselves participating in the colour-developing reaction.
  • Useful sensitizers for the purposes of the present invention include, for example, fatty acid salts, fatty acid esters and fatty acid amides (e.g. zinc stearate, stearamide, palmitamide, oleamide, lauramide, ethylene- and methylenebisstearamide, methylolstearamide), naphthalene derivatives, biphenyl derivatives, phthalates and terephthalates.
  • fatty acid salts e.g. zinc stearate, stearamide, palmitamide, oleamide, lauramide, ethylene- and methylenebisstearamide, methylolstearamide
  • fatty acid amides e.g. zinc stearate, stearamide, palmitamide, oleamide, lauramide, ethylene- and methylenebisstearamide, methylolstearamide
  • naphthalene derivatives biphenyl derivatives
  • phthalates and terephthalates e.
  • the invention has a particular preference for a coating composition or heat-sensitive recording material wherein the sensitizer is selected from the group consisting of 1 ,2- bis(3-methylphenoxy)ethane (other names: 3,3'-(ethylenebisoxy)bistoluene, 1 ,2-bis(3- methylphenyloxy)ethane (DMPE), ethylene glycol m-tolyl ether (EGTE) [1 ,2-di(m- methylphenoxy)ethane (DMPE, CAS ® RN is according to DB "Chemical Book" another name for EGTE)], 1 ,1 '-[1 ,2-ethanediylbis(oxy)]bis[3-methylbenzene, CAS ® RN 54914-85- 1 ), 1 ,2-diphenoxyethane (diphenoxyethane (DPE, optionally also known under the abbreviation of "EGPE”), CAS ® RN 104-66-5), 2-(2H-
  • these sensitizers are each used alone, that is to say, not in combination with the other named sensitizers from the above list.
  • a second, equally preferred embodiment incorporates two or more sensitizers selected from the above list in the coating composition or heat-sensitive recording layer.
  • the preference of the invention is for a coating composition or heat-sensitive recording material wherein the sensitizer has a melting point of 60 °C to 180 °C, preferably a melting point of 80 °C to 140 °C.
  • Coating compositions or heat-sensitive recording materials are preferable if desired when the heat-sensitive recording layer contains a binder, preferably a crosslinked or uncrosslinked binder selected from the group consisting of polyvinyl alcohol, carboxyl- modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer, a combination of polyvinyl alcohol and ethylene-vinyl alcohol copolymer, polyvinyl alcohol modified with silanol groups, diacetone-modified polyvinyl alcohol, acrylate copolymer and film-forming acrylic copolymers.
  • a binder preferably a crosslinked or uncrosslinked binder selected from the group consisting of polyvinyl alcohol, carboxyl- modified polyvinyl alcohol, ethylene-vinyl alcohol copolymer,
  • the crosslinking agent is preferably selected from the group consisting of zirconium carbonate, polyamideamine epichlorohydrin resins, boric acid, glyoxal, dihydroxybis(ammonium lactato)titanium(IV) (CAS ® RN 65104- 06-5; Tyzor LA) and glyoxal derivatives.
  • the heat-sensitive recording layer contains one or more binders crosslinked by reaction with one or more crosslinking agents, said crosslinking agent or agents being selected from the group consisting of zirconium carbonate, polyamideamine epichlorohydrin resins, boric acid, glyoxal, dihydroxybis(ammonium lactato)titanium(IV) (CAS ® RN 65104-06-5; Tyzor LA) and glyoxal derivatives.
  • crosslinked binder here is meant the reaction product formed by reacting a binder with one or more crosslinking agents.
  • the preference of the invention is in some cases likewise for a coating composition or heat-sensitive recording layer of a type described and defined above wherein the proportion of the colour developer or of a colour developer mixture in the coating composition or heat-sensitive recording layer is for example at least 10 wt.%, especially at least 15 or 20 wt.%, and/or up to not more than 65 wt.%, especially up to not more than 60 wt.%, and preferably 24 to 60 wt.%, more preferably 35 to 58 wt.%, more preferably 39 to 56 wt.%, based on the entire solids content of the coating composition or heat-sensitive recording layer.
  • the preference of the invention is for a coating composition or heat-sensitive recording material wherein the basis weight of the heat-sensitive recording layer is in the range from 1 .5 to 8 g/m 2 , preferably in the range from 1 .5 to 6 g/m 2 , more preferably in the range from 2 to 6 g/m 2 and yet more preferably in the range from 2.0 to 5.5 g/m 2 .
  • Recording materials according to the invention may additionally also employ image stabilizers, dispersants, antioxidants, release agents, defoamers, light stabilizers, brighteners as known in the prior art.
  • Every one of the components is typically used in an amount of 0.01 to 15 wt.%, especially - with the exception of defoamer - 0.1 to 15 wt.%, preferably 1 to 10 wt.%, based on the entire solids content of the heat-sensitive recording layer.
  • the recording materials of the invention may contain the defoamer in amounts of 0.03 to 0.05 wt.%, based on the entire solids content of the heat-sensitive recording layer.
  • the invention also provides a coating colour for forming a coating composition or a heat-sensitive recording layer, comprising - one or more dye precursors; and one or more than one colour developer, wherein the one or at least one colour developer of the two or more colour developers is a compound as defined herein for the purposes of the invention.
  • coating colour here refers to a technical term familiar in the paper industry in relation to the production of coated papers.
  • coating colour also coating compound or coating mix
  • coating media containing or consisting of pigments, binders and additives which are coated on the paper surface using specific coating machines to surface finish the paper.
  • coating colours are referred to as “coated papers” and are notable for superior printability and haptics.
  • coating colour is thus the hypernym for all coatable mixes, compounds, preparations and/or solutions in the paper industry.
  • the precoat or intercoat is therefore a particular embodiment of a coating colour, namely that which is the first to be applied to the paper substrate.
  • the next coat or layer applied is frequently a coating colour as functional coating, for example in order to provide a thermal functionality or a barrier functionality.
  • the next layer or coat which may optionally be applied is a coating colour for the purpose of establishing a protective function, for example a protective topcoat layer.
  • a thermal layer with a silicone-containing coating colour to form a release layer.
  • a silicone-containing coating colour may alternatively also be coated on a protective layer.
  • the paper substrate side opposite the silicone-containing layer is frequently coated with an adhesive-containing coating colour.
  • the application of the adhesive-containing coating colour may likewise be preceded by the application to the paper substrate of a coating colour as precoat.
  • a coating colour in the context of the present invention is to be understood as of the present invention when it can be applied as a functional coating to a substrate which may optionally already display one or more precoats, in order to provide on the substrate a thermal functionality, i.e. such a coating colour of the present invention comprises one or more dye precursors; and one or more than one colour developer, wherein the one or at least one of the more than one colour developers is a compound as defined herein as being of the present invention.
  • various coating techniques are known to a person skilled in the art, examples being: blade coating, film press coating, cast coating, curtain coating, spray coating.
  • the invention provides a heat-sensitive material comprising a supporting substrate, and a heat-sensitive recording layer as defined herein for the purposes of the invention.
  • the preference of the invention is for an above heat-sensitive recording material additionally containing an interlayer between the supporting substrate and the heat- sensitive recording layer, wherein the interlayer preferably contains pigments.
  • the pigments comprise a) organic pigments, preferably hollow-body organic pigments and/or b) inorganic pigments, preferably selected from the list consisting of calcinated kaolin, silica, bentonite, calcium carbonate, alumina and boehmite.
  • the heat-sensitive recording layer is wholly or partly covered by a protective layer.
  • the application of a protective layer covering the heat-sensitive recording layer also shields the heat- sensitive recording layer towards the outside and/or towards the supporting substrate of the next ply within a roll, protecting it from external influences.
  • a protective layer of this type in addition to protecting from environmental influences the heat-sensitive recording layer arranged underneath the protective layer, frequently in such cases has the additional positive effect of improving the printability of the subject invention heat-sensitive recording material particularly in indigo, offset and flexographic printing. It may therefore be desirable for certain application scenarios that the heat- sensitive recording material of the present invention should have a protective layer even though the presence of a colour developer mixture as above defined in the heat-sensitive recording layer of the heat-sensitive recording material of the present invention ensures that the durability to entities selected from the group consisting of water, alcohols, fats, oils and mixtures thereof for a thermal printout obtainable on a heat-sensitive recording material of the present invention is already sufficient even without protective layer.
  • the protective layer of the heat-sensitive recording material according to the present invention preferably contains one or more crosslinked or uncrosslinked binders selected from the group consisting of carboxyl-modified polyvinyl alcohols, polyvinyl alcohols modified with silanol groups, diacetone-modified polyvinyl alcohols, acetoacetyl-modified polyvinyl alcohol, partially and completely hydrolysed polyvinyl alcohols and film-forming acrylic copolymers.
  • the coating compound for forming the protective layer of the heat- sensitive recording material according to the present invention in addition to one or more binders, contains one or more crosslinking agents for the binder or binders.
  • the crosslinking agent is then preferably selected from the group consisting of boric acid, polyamines, epoxy resins, dialdehydes, formaldehyde oligomers, epichlorohydrin resins, adipodihydrazide, melamine-formaldehyde, urea, methylolurea, ammonium zirconium carbonate, sodium/calcium glyoxylate, polyamide-epichlorohydrin resins and Tyzor LA.
  • the protective layer contains one or more crosslinked binders due to reaction with one or more crosslinking agents, the crosslinking agent or agents being selected from the group consisting of boric acid, polyamines, epoxy resins, dialdehydes, formaldehyde oligomers, epichlorohydrin resins, adipodihydrazide, melamine-formaldehyde, urea, methylolurea, ammonium zirconium carbonate and polyamide epichlorohydrin resins.
  • crosslinked binder here is meant the reaction product formed by reacting a binder with one or more crosslinking agents.
  • the protective layer wholly or partly covering the heat-sensitive recording layer is obtainable from a coating compound comprising one or more polyvinyl alcohols and one or more crosslinking agents. It is preferable for the polyvinyl alcohol of the protective layer to be modified with carboxyl groups or especially silanol groups. Mixtures of various carboxyl- or silanol-modified polyvinyl alcohols are usable with preference.
  • a protective layer has high affinity for the preferably UV-crosslinking printing ink (UV stands for: ultraviolet radiation) used in the offset printing process. This makes a decisive contribution to meeting the demand for outstanding printability within offset printing.
  • the crosslinking agent or agents of the protective layer according to this embodiment are preferably selected from the group consisting of boric acid, polyamines, epoxy resins, dialdehydes, formaldehyde oligomers, polyamine epichlorohydrin resins, adipodihydrazide, melamine-formaldehyde and Tyzor LA. Mixtures of various crosslinking agents are also possible.
  • the weight ratio of the modified polyvinyl alcohol to the crosslinking agent in the coating compound for forming the protective layer in this embodiment is preferably in a range of 20:1 to 5:1 and more preferably in a range of 12:1 to 7:1 . Particular preference is given to a ratio in the range from 100 parts by weight to 8 to 1 1 parts by weight of the modified polyvinyl alcohol to the crosslinking agent.
  • the protective layer in this embodiment additionally contains an inorganic pigment.
  • This inorganic pigment is preferably selected from the group consisting of silica, bentonite, alumina, calcium carbonate, kaolin and mixtures thereof.
  • the basis weight in which the protective layer is applied in this embodiment is preferably in a range of 1 .0 g/m 2 to 6 g/m 2 and more preferably of 1 .2 g/m 2 to 3.8 g/m 2 .
  • the protective layer therein is preferably formed as a single ply.
  • the coating compound for forming the protective layer comprises a water-insoluble self-crosslinking acrylic polymer as binder, a crosslinking agent and a pigmentary constituent, wherein the pigmentary constituent of the protective layer consists of one or more inorganic pigments and not less than 80 wt.% is formed of a highly purified alkali-pretreated bentonite, the binder of the protective layer consists of one or more water-insoluble self-crosslinking acrylic polymers, and the binder/pigment ratio is in a range of 7:1 to 9:1 .
  • a self-crosslinking acrylic polymer within the protective layer in the second version described here of the embodiment is preferably selected from the group consisting of styrene-acrylic ester copolymers, copolymers formed from styrene and acrylic ester and containing acrylamide groups, and also copolymers based on acrylonitrile, methacrylamide and acrylic ester. The latter are preferred.
  • Alkali-pretreated bentonite, natural or precipitated calcium carbonate, kaolin, silica or aluminium hydroxide may be incorporated in the protective layer as pigment.
  • Preferred crosslinking agents are selected from the group consisting of cyclic urea, methylolurea, ammonium zirconium carbonate and polyamide epichlorohydrin resins.
  • the protective layer itself can be applied by employing customary coating mechanisms for which inter alia a coating colour is usable, preferably with a basis weight in a range of 1 .0 to 4.5 g/m 2 .
  • the protective layer has been applied by printing in an alternative version.
  • Protective layers curable by application of actinic radiation are particularly suitable because of their processing and technological properties.
  • actinic radiation is to be understood as meaning UV or ionizing radiations, such as electron beam rays.
  • Actinity is to be understood as meaning the photochemical activity of electromagnetic radiation differing in wavelength.
  • the appearance of the protective layer is dispositively determined by the type of smoothing and of the cylinder surfaces, which influence the friction in the smoothing mechanism and calender, and their materials.
  • a further aspect of the present invention relates to a use of a subject invention heat- sensitive recording material as lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical and/or technical diagram paper, fax paper, security paper or barcode labels.
  • TITO ticket-in, ticket-out
  • a further aspect of the present invention relates to products, preferably lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical diagram paper, fax paper, security paper or barcode labels, comprising a subject invention heat-sensitive recording material.
  • TITO ticket-in, ticket-out
  • TITO Ticket-in, ticket-out
  • a TITO machine prints out a TITO ticket (barcode ticket) which can either be exchanged for cash or inserted into other TITO machines.
  • TITO machines have a network interface for communication with a central system which tracks the credits associated with the TITO tickets barcode tickets. This technology is useful wherever changeable credits are required yet no cash is to be used, for example in canteens, refectories, leisure parks, swimming baths and/or saunas.
  • a further aspect of the present invention relates to a method of forming a heat-sensitive recording material or a heat-sensitive recording layer, as respectively defined herein, said method comprising the steps of: i. providing or forming a supporting substrate; and also providing or forming a coating composition as described and defined herein according to the invention, or a coating colour, as described and defined herein according to the invention, comprising a compound of formula (B-l) as is used in a subject invention heat- sensitive recording material; ii. applying the provided or formed coating composition to the provided or formed supporting substrate or to an interlayer positioned thereon; iii. drying the applied coating composition to obtain a heat-sensitive recording layer which combines with the supporting substrate to form a heat-sensitive recording material; iv.
  • an above method comprising said steps i. to iii. for forming a heat-sensitive recording material or for forming a heat-sensitive recording layer and further comprising the step of applying a protective layer to wholly or partly cover the heat-sensitive recording layer and drying the protective layer to obtain a heat- sensitive recording layer which combines with the supporting substrate to form a heat-sensitive recording material and is wholly or partly covered by the protective layer.
  • the preference of the invention is for a method additionally comprising the steps of a) providing or forming a coating composition or coating colour comprising pigments; b) applying the provided or formed coating composition or coating colour to the
  • step iii. of the subject invention method is effected onto the formed interlayer and not directly onto the provided or formed supporting substrate.
  • the invention likewise has a preference for a method additionally comprising the steps of A) providing or forming a coating composition; B) applying the provided or formed coating composition to the heat-sensitive recording layer;
  • steps A) to C) drying the applied coating composition to form a protective layer; wherein steps A) to C) are carried out after step iv. and the protective layer is on the heat-sensitive recording layer.
  • the preference of the invention may further be for a method of forming a subject invention heat-sensitive recording material or a subject invention heat-sensitive recording layer that further comprises the step of applying a protective layer to wholly or partly cover the heat-sensitive recording layer and drying the protective layer to obtain a heat- sensitive recording layer which combines with the supporting substrate to form a heat- sensitive recording material and is wholly or partly covered by the protective layer.
  • the invention further provides a compound preferably for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the compound comprises: a) at least one structural unit of lactic acid and b) two mutually independent terminal electron acceptor groups for the colour developer, wherein the compound is a compound of formula (B-l) as indicated and defined above according to the invention, for example, in the Embodiments B and/or C, and in Claim 17.
  • the compound is a compound of formula (B-l) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 17 and containing a structural unit of formula (B-lc) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 18.
  • the compound is a compound of formula (B-l) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 17 and as comprising two mutually independent terminal electron acceptor groups having the structural unit of formula (B-lb) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 17; and wherein the compound of formula (B-l) also includes a structural unit of formula (B-lc) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 18.
  • the compound is a compound in which at least one structural unit of formula (B-llla) and/or of formula (B-lllb) of lactic acid or its lactide is present in the compound of formula (B-l), as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 17,
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2;
  • the compound is a compound of formula (B-l) as indicated and defined according to the invention, the said Embodiments B and/or C, and in Claim 17, wherein the compound has one or two terminal structural units of formula (B-lb), preferably two terminal structural units of formula (B-lb),
  • the particle sizes of the one or at least one of the compounds when two or more compounds are present, as defined above, as measured by laser diffraction, of the one or at least one compound of the two or more compounds are each independently, in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ .
  • the preference of the invention in some cases is for a compound or mixtures thereof or as a mixture with at least one further compound of formula (B-XIV), as defined above, wherein the particle sizes measured as X 50 value by laser diffraction for the one or at least one compound of the two or more compounds are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1 .7 ⁇ and more preferably in the range from 0.85 to 1 .65 ⁇ .
  • the particle sizes can be determined by use of laser diffraction (HELOS particle size analysis).
  • An R1 Helos (H1453) & Quixel instrument from Sympatec GmbH was used in the context of the invention (analysis by WINDOX 4).
  • the invention further provides for the use of a compound as defined above, i. as colour developer as indicated under A) to D), and/or ii. for forming a colour developer as indicated under A) to D), and/or iii. as colour developer for forming as indicated under A) to D), wherein the colour developer is suitable and/or intended for and/or serves for forming
  • the invention finally also provides a method of forming a compound according to the invention as described and defined above, preferably a compound for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the method comprises the reaction of a compound (i.e. with a cyclic ester of a hydroxy carboxylic acid, lactide) of formula (B-IV),
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2,
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom;
  • reaction is carried out under conditions where the compound of formula (B-V) does not decompose at all or at least not wholly, preferably under conditions where the temperature in the reaction is at least 1 °C, preferably at least 2 °C or 3 °C or 4 °C or 5 °C lower, more preferably at least 5 °C to 10 °C lower, than the decomposition temperature of a compound of formula (B-V);
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of formula (B-VII) as precursor compound to an electron acceptor group,
  • the invention further provides a method of forming a compound as indicated previously, preferably a compound for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat- sensitive recording layer, wherein the method comprises the reaction of
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2,
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of formula (B-VII) as precursor compound to an electron acceptor group,
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom,
  • the compound of formula (B-l-A) is symmetrical and contains a central structural urea unit whereto, via each nitrogen atom, a structural lactide unit is attached in each case, the compound of formula (B-l-A) thus altogether containing two structural lactide units, and wherein a p-toluenesulfonylaminocarbonyl moiety attaches terminally to the structural lactide units in each case, as an electron acceptor group.
  • the present invention is further defined in the example which follows. This example, which discloses an embodiment of the invention, is only depicted for visualization.
  • Urea and Puralact B3 were placed in a reaction vessel under nitrogen.
  • the vessel was heated to 150 S C and 100 ppm of tin octoate catalyst were added thereto. The temperature of the vessel was then raised to 180 S C and the reaction was continued for about 6 hours.
  • the vessel was cooled down to 20-60 °C, MEK was added thereto and then p-toluenesulfonyl isocyanate was gradually added to the reaction mixture over time in order to ensure that the reaction temperature stayed between 60 and 70 °C. Following completion of addition of the p-toluenesulfonyl isocyanate, the reaction proceeded for a further hour under agitation. The MEK was then removed in vacuo.
  • the reaction product obtained was used for the performance tests of thermal papers.
  • lactide (Puralact B3, commercially available from Corbion Purac B.V., Netherlands) was subjected in the presence of urea and in a conventional manner to a catalytic ring-opening reaction and polymerization to polylactide, the conversion being effected under conditions where urea does not decompose at all or entirely.
  • urea disintegrates into carbon dioxide and ammonium salts on heating in an aqueous solution with acids and into carbonates and ammonia on heating with alkalis. The conversion is carried out at temperatures as indicated in the description part.
  • the urea which is preferably also used as lactide ring opener, will react with the ring-opened lactide directly and/or with the intermediate, lactide ring opened to the desired extent after polymerization, via the carboxyl groups present therein, to form an amide group. Then, the resulting urea-lactide intermediate is made to react with p-toluenesulfonyl isocyanate (CAS ® RN 4083-64-1 ) as electron acceptor group E.
  • the conversion product obtained contains a compound of formula (B-l). Purification and isolation of the reaction product obtained and/or of the one compound or more compounds was eschewed since it was known from the prior art (e.g. EP 2 574 645 A1 and EP 2 784 133 A1 ) that any polylactic acids present should not interfere with performance trials on thermal papers.
  • the lactide (Puralact B3) and urea were placed in a reaction vessel under inert gas before being heated to about 150 °C.
  • a tin catalyst was admixed in ppm quantity followed by an approximately 6 hour reaction at temperatures up to 180 °C during which urea serves as ring opener and promotes the polymerization to polylactide and/or polylactic acid.
  • reaction mixture was cooled down to room temperature up to slightly elevated temperatures (20 °C to 60 °C).
  • first methyl ethyl ketone was added as solvent followed by p-toluenesulfonyl isocyanate, and under agitation the p-toluenesulfonyl isocyanate reacted away over about 1 hour.
  • the methyl ethyl ketone solvent was stripped off in vacuo.
  • the reaction product obtained was used for the performance trials of thermal papers. Performance examples with comparative examples
  • Example 3 Comminution of material, formation of coating colour, coating of paper
  • Initial trials were started in order to comminute the colour developer material, form a coating colour therewith and then coat this coating colour on paper.
  • Two versions were coated.
  • the first version was turraxed to a particle size of 8 ⁇ and the second version was comminuted with a stirred ball mill (for example with LabStar stirred ball mill from Netzsch) to 1 .6 ⁇ .
  • the material was initially only turraxed (for example with ULTRA-TURRAX ® high-performance disperser from the appliance maker IKA ® -Werke GmbH & CO. KG, alternatively with POLYTRON ® PT 6100 D stand disperser from Kinematica GmbH Dispersing and Mixing technology).
  • Comminuting with ULTRA- TURRAX ® or POLYTRON ® PT 6100 D is based on the rotor-stator principle.
  • the turning rotor creates an underpressure whereby the sample to be dispersed is aspirated and conveyed through the stator slots to the outside.
  • the sample is subjected to high decelerating and accelerating forces in that the individual particles are pulled apart and comminuted through further cutting and impacting effects down to a few micrometres.
  • the high shearing effect created in the process leads to the comminution of solids in the sample.
  • the two versions utilized the same recipe for forming the coating colour and coating on paper.
  • the recipes for the coating colours were determined in preliminary tests using other PLA specimens.
  • the specimens of the coating colour recipes of the invention were compared with two commercially available standard varieties (BPA and Pergafast ® 201 ).
  • Recipes (standard formulations) containing inventive PLA specimens and any comparative recipes were coated on paper and the papers were dried in a conventional manner. Papermakers distinguish three grades for the dry matter content of paper and chemical pulp: “atro” (absolutely dry), “lutro” (air dry) and “otro” (oven dry). This is reported in each case as “% atro", “% lutro” and "% otro". Where "atro" represents a paper or chemical pulp of 0 % water.
  • the dynamic printing density is determined as follows: The thermal recording material described above was thermally printed with an Atlantek 400 (ATLANTEK Model 400 Thermal Response Test System from Global Media Instruments, LLC (USA)) printer using different energy settings. The thermally printed regions obtained as a result were measured with the aid of a spectral densitometer (SpectroDens from Techkon).
  • Fig. 1 shows the printouts obtained in a comparison between an inventive PLA specimen (1 ) having a particle size of 8 ⁇ and a prior art developer, BPA (2).
  • Fig. 2 shows the measured dynamic printing density as a printout for an inventive PLA specimen (1 ) having a particle size of 8 ⁇ .
  • Fig. 2 shows the dynamic printing density as a diagram where [A] denotes the energy (mj/mm 2 ) and [B] denotes the dynamic printing density.
  • the static printing density is determined as follows: The thermal recording material described above was printed with the Heat gradient tester No. 884 (Toyoseiki) at different temperatures, at defined pressure over a defined time. The thermally printed regions obtained as a result were measured with the aid of a spectral densitometer (SpectroDens from Techkon). Testinq the environmental durability:
  • thermal test printouts chequered black and white, were prepared on each of the heat-sensitive recording materials to be tested, using an Atlantek 400 with a thermal head having a resolution of 300 dpi and a 16 mJ/mm 2 energy per unit area.
  • the printing density was determined with SpectroDens densitometer from Techkon at respectively three places of the black areas of the thermal test printout. The respective values measured for the black areas were averaged in each case to form the mean.
  • the printing density was determined with SpectroDens densitometer from Techkon at respectively the three places of the black areas of the thermal test printout which had already been measured before treating the thermal test printout. The respective values measured for the black areas were averaged in each case to form the mean.
  • Measurement 1 particle size (TG) of 8 ⁇ ;
  • Measurement 2 particle size (TG) of 1 .6 ⁇ .
  • the inventive PLA specimen used gave a D-Max of 0.96 (as determined using ATLANTEK Model 400 Thermal Response Test System from Global Media Instruments, LLC (USA)).
  • the Epson printout with the inventive PLA specimen used looks black. An optical printing density of 0.98 was measured here.
  • the printout is somewhat uneven which - without wishing to be tied to one specific theory - might be due to coarse particles, since the material used was initially only turraxed to 8 ⁇ and therefore some coarse particles were still also present on the coated paper.
  • Fig. 2 shows two exemplary printouts with a comparative scale.
  • the 2D barcode with the inventive PLA specimen used was readable to a value of 2.4; the comparative BPA has a value of 2.2.
  • Substance C Dispersant for developer
  • Tesa strip adhesive strip, adhesive film, from Tesa SE, Germany; the term "adhesive strip” is a collective designation for strip-shaped supporting materials, e.g. comprising self-supporting polymeric film/sheeting) one- or both-sidedly coated with pressure-sensitive adhesives transversely.
  • the final dispersion is distributed on the Tesa strip in one line.
  • the dispersion is coated over the paper leaving little behind.
  • the paper is air dried or at not more than 60 °C oven dried for 1 min.
  • a lighter is then used to briefly heat the paper from behind. This short exposure is itself sufficient to engender a (colour) reaction.
  • thermal test printouts chequered black and white
  • ATLANTEK 400 Thermal Response Test System from Global Media Instruments, LLC (USA) with a thermal head having a resolution of 300 dpi and a 16 mJ/mm 2 energy per unit area.
  • the printing density was determined with RD - 1152 "B" Gretag Macbeth densitometer at respectively three places of the black areas of the thermal test printout. The respective values measured for the black areas and the uncoloured areas were averaged in each case to form the mean.
  • a thermal test printout was suspended in a conditioning cabinet at 40 °C and a relative humidity of 90 %. After 24 hours the thermal paper printout was removed, cooled down to room temperature and remeasured for its printing density, with an RD - 1 152 "B" Gretag Macbeth densitometer at those three places of the black areas and of the uncoloured areas of the thermal test printout. The respective values measured for the black areas and the uncoloured areas were averaged in each case to form the mean.
  • the durability of the printed image in % corresponds to the ratio of mean printing density of the coloured areas before and after storage in the conditioning cabinet multiplied by 100.
  • Example 7 Test procedure
  • thermal test printouts chequered black and white, were prepared on each of the heat-sensitive recording materials to be tested, using an ATLANTEK 400 Thermal Response Test System from Global Media Instruments, LLC (USA) with a thermal head having a resolution of 300 dpi and a 16 mJ/mm 2 energy per unit area.
  • the printing density was determined with TYPE D19C Gretag Macbeth densitometer at respectively three places of the black areas of the thermal test printout. The respective values measured for the black areas and the uncoloured areas were averaged in each case to form the mean.
  • the thermal test printout prepared on the heat-sensitive recording material to be tested was then generously coated with lanolin. Following a soak-in time of 10 minutes, the lanolin is carefully wiped off and remeasured for its printing density, with a TYPE D19C Gretag Macbeth densitometer at those three places of the black areas and of the uncoloured areas of the thermal test printout. The respective values measured for the black areas and the uncoloured areas were averaged in each case to form the mean.
  • the lanolin durability in % corresponds to the ratio of mean printing density before the lanolin treatment and after the lanolin treatment multiplied by 100.
  • the durability to water and/or aqueous ethanol solutions corresponds to the ratio of mean printing density before and after the treatment with the particular test liquid multiplied by 100.
  • Example 9 Bekk smoothness test procedure
  • the smoothness (or roughness) is a significant surface property of papers. It represents the quality of the surface structure.
  • the Bekk smoothness relies on the principle of air leak measurement. To this end, a sample is placed on a specified glass plate and pressed in place via a rubber plate using defined pressure. This is followed by a certain volume of air being sucked from the outside through the contact area via an established vacuum.
  • the Bekk smoothness is measured in accordance with DIN 53107:2016-05 "Testing of Paper and Board - Determination of Bekk Smoothness".
  • the Bekk smoothness is the time in seconds needed for a certain volume of air to be sucked out of the ambient air at a defined differential pressure and radially inwardly through between a paper surface and a ring-shaped, nearly perfectly plane area under fixed contact conditions.
  • the samples were each subjected to ten measurements being carried out on the overside (OS). A new sample was used for every measurement.
  • the sample was placed with the in— test side on the glass plate so as to completely cover it.
  • the rubber plate and the pressure plate were then placed on the sample, the areal press of 100 kPa was applied and the prepressure Pv created in the vacuum container.
  • the vacuum container is then connected to the drilled hole in the glass plate. What is measured, then, is the time for the pressure drop between pi (measurement pressure at the start of the measurement, in kilopascals) and p ⁇ (measurement pressure at the end of the measurement, in kilopascals).
  • the measurements were carried out with a Bekk smoothness tester from Messmer Biichel. This test instrument is unreservedly useful for testing according to DIN 53107 / ISO 5627.
  • [A] energy (mj/mm 2 )
  • Embodiments A1 to A16 are identical to Embodiments A1 to A16:
  • R1 and R2 are independently a hydrogen atom, a C1 -C6 alkyl group, a 5 C1 - C6 alkoxy group or a halogen atom;
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1 -C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH
  • a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • the agent according to Claim 1 wherein R1 , R2, R3, R4, R5 and R6 are independently a hydrogen atom or a C1 -C3 alkyl group.
  • thermosensitive recording medium having a colour developing layer comprising: a leuco dye; and,
  • thermosensitive medium wherein said leuco dye is selected from the group consisting of: triphenylmethanephthalide leuco com- pounds; triallylmethane leuco compounds; fluoran leuco compounds; phenothiaz- ine leuco compounds; thiofluoran leuco compounds; xanthene leuco compounds; indophthalyl leuco compounds; spiropyran leuco compounds; azaphthalide leuco compounds; couromenopyrazole leuco compounds; methine leuco compounds; rhodamineanilino-lactam leuco compounds; rhodaminelactam leuco compounds; quinazoline leuco compounds; diazaxanthene leuco compounds; bislactone leuco compounds; and, mixture
  • thermosensitive medium according to Embodiment 9 in which the colour developing layer comprises a fluoran leuco dye.
  • said colour developing layer further comprises one or more of:
  • thermo-sensitive recording medium comprising the steps of:
  • aqueous coating composition comprising a leuco dye and a dispersed colour developer which reacts with said leuco dye upon heating;
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH
  • a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH
  • R3 and R4 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group.
  • R is a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom.
  • Embodiments B1 to B15 are identical to Embodiments B1 to B15:
  • Coating composition for forming a heat-sensitive recording material or a heat-sensitive recording layer comprising
  • the one or at least one colour developer of the two or more colour developers is a compound which in the colour developer contains
  • the one or the at least one colour developer of the two or more colour developers is a compound of formula (B-l),
  • Coating composition for forming a heat-sensitive recording material or a heat-sensitive recording layer according to Embodiment 1 wherein the one or the at least one colour developer of the two or more colour developers of formula (B-l) is a compound which
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom;
  • Coating composition or heat-sensitive recording layer according to either of Embodiments 1 and 2, wherein the particle sizes, measured by laser diffraction for the one or at least one colour developer of the two or more colour developers are each independently in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ ; or wherein the particle sizes measured as the X50 value by laser diffraction for the one or at least one colour developer of the two or more colour developers are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1.7 ⁇ and more preferably in the range from 0.85 to 1.65 ⁇ .
  • the coating composition or heat-sensitive recording layer comprises a sensitizer selected from the group consisting of benzyl naphthyl ether (BNE), diphenyl sulfone (DPS), ethylene glycol m-tolyl ether (EGTE), ethylene glycol phenoxyethane (EGPE), 1 ,2-di(m-methylphenoxy)ethane (DMPE) and 1 ,2- diphenoxyethane (DPE), or a combination thereof.
  • BNE benzyl naphthyl ether
  • DPS diphenyl sulfone
  • EGTE ethylene glycol m-tolyl ether
  • EGPE ethylene glycol phenoxyethane
  • DMPE ,2-di(m-methylphenoxy)ethane
  • DPE diphenoxyethane
  • Coating composition or heat-sensitive recording layer according to any preceding Embodiment wherein the basis weight of the coating composition or heat-sensitive recording layer is in the range from 1 .5 to 8 g/m 2 , preferably in the range from 1 .5 to 6 g/m 2 , more preferably in the range from 2 to 6 g/m 2 and yet more preferably in the range from 2.0 to 5.5 g/m 2 .
  • Coating colour for forming a coating composition or a heat-sensitive recording layer comprising one or more dye precursors; and one or more than one colour developer, wherein the one or at least one colour developer of the two or more colour developers is a compound as defined in any one of Embodiments 1 to 5.
  • Heat-sensitive recording material comprising a supporting substrate, and a heat-sensitive recording layer as defined in any one of Embodiments 1 to 5; preferably wherein the heat-sensitive recording material additionally contains an interlayer between the supporting substrate and the heat-sensitive recording layer, wherein the interlayer preferably contains pigments; more preferably wherein the pigments comprise a) organic pigments, preferably hollow-body organic pigments, and/or b) inorganic pigments, preferably selected from the list consisting of calcinated kaolin, silica, bentonite, calcium carbonate, alumina and boehmite; preferably a heat-sensitive recording material wherein the heat-sensitive recording layer is wholly or partly covered by a protective layer.
  • Products preferably lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical diagram paper, fax paper, security paper or barcode labels, comprising a subject invention heat- sensitive recording material according to Embodiment 7.
  • TITO ticket-in, ticket-out
  • Embodiments 7 and 8 Use of a heat-sensitive recording material according to either of Embodiments 7 and 8 as lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical and/or technical diagram paper, fax paper, security paper or barcode labels.
  • TITO ticket-in, ticket-out
  • a protective layer for forming a heat-sensitive recording material or for forming a heat-sensitive recording layer and further comprising the method step of applying a protective layer to wholly or partly cover the heat-sensitive recording layer and drying the protective layer to obtain a heat-sensitive recording layer which combines with the supporting substrate to form a heat-sensitive recording material and is wholly or partly covered by the protective layer.
  • the compound preferably for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat- sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the compound comprises: a) at least one structural unit of lactic acid and b) two mutually independent terminal electron acceptor groups for the colour developer, wherein the compound is a compound of formula (B-l) as indicated and defined in Embodiment 1 ; preferably wherein the compound is a compound of formula (B-l) as indicated and defined in Embodiment 1 and containing a structural unit of formula (B-lc) as indicated and defined in Embodiment 2; more preferably wherein the compound is a compound of formula (B-l) as indicated and defined in Embodiment 1 and as comprising two mutually independent terminal electron acceptor groups having the structural unit of formula (B-lb) as indicated and defined in Embodiment 1 ; and wherein the compound of formula (B-l)
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2; and particularly preferably wherein the compound is a compound of formula (B-l) as indicated and defined in Embodiment 1 , wherein the compound has one or two terminal structural units of formula (B-lb), preferably two terminal structural units of formula (B-lb),
  • Compound according to Embodiment 1 1 preferably for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the particle sizes, measured by laser diffraction for the one or at least one compound of two or more compounds are each independently in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ ; or wherein the particle sizes measured as the X 50 value by laser diffraction for the one or at least one of the more than one colour developers are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1 .7 ⁇ and more preferably in the range from 0.85 to 1 .65 ⁇ .
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2,
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom;
  • reaction is carried out under conditions where the compound of formula (B-V) does not decompose at all or at least not wholly, preferably under conditions where the temperature in the reaction is at least 1 °C, preferably at least 2 °C or 3 °C or 4 °C or 5 °C lower, more preferably at least 5 °C to 10 °C lower, than the decomposition temperature of a compound of formula (B-V);
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of formula (B-VII) as precursor compound to an electron acceptor group,
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2, and ( ⁇ ) at least one precursor compound to an electron acceptor group as defined in Embodiment 3, preferably at least one compound of the formula (B-Vla) and/or of formula (B-Vlb),
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of formula (B-VII) as precursor compound to an electron acceptor group,
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom,
  • Embodiments C1 to C19 are identical to Embodiments C1 to C19:
  • R1 and R2 are independently a hydrogen atom, a C1-C6 alkyl group, a 5 C1- C6 alkoxy group or a halogen atom;
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; preferably wherein X is O; and,
  • a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • R1 , R2, R3, R4, R5 and R6 are independently a hydrogen atom or a C1-C3 alkyl group; preferably wherein R1 , R2, R5 and R6 are independently a hydrogen atom or a C1-C3 alkyl group, and R3 and R4 are independently a hydrogen atom or a methyl group, and more preferably wherein R3 is H and R4 is methyl; and/or wherein R1 and R2 are both methyl and are parasubstituents of the phenyl group.
  • R3, R4, R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH
  • a and b are integer values meeting the conditions a > 0, b > 0 and (a+b) > 1.
  • R5 and R6 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group;
  • X is O, S or NH; and, a cyclic ester of a hydroxycarboxylic acid having the Formula
  • R3 and R4 are independently a hydrogen atom, a C1-C6 alkyl group, a C3-C6 cycloalkyl group or a C2-C6 alkenyl group.
  • R is a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom.
  • Coating composition for forming a heat-sensitive recording material or a heat-sensitive recording layer comprising
  • the one or at least one colour developer of the two or more colour developers is a compound which in the colour developer contains
  • the one or the at least one colour developer of the two or more colour developers is a compound of Formula (B-l),
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom;
  • Coating composition or heat-sensitive recording layer according to either of Embodiments 7 and 8, wherein the particle sizes, measured by laser diffraction for the one or at least one colour developer of the two or more colour developers are each independently in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ ; or wherein the particle sizes measured as the X50 value by laser diffraction for the one or at least one colour developer of the two or more colour developers are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1.7 ⁇ and more preferably in the range from 0.85 to 1.65 ⁇ .
  • the coating composition or heat-sensitive recording layer comprises a sensitizer selected from the group consisting of benzyl naphthyl ether (BNE), diphenyl sulfone (DPS), ethylene glycol m-tolyl ether (EGTE), ethylene glycol phenoxyethane (EGPE), 1 ,2-di(m-methylphenoxy)ethane (DMPE) and 1 ,2- diphenoxyethane (DPE), or a combination thereof.
  • BNE benzyl naphthyl ether
  • DPS diphenyl sulfone
  • EGTE ethylene glycol m-tolyl ether
  • EGPE ethylene glycol phenoxyethane
  • DMPE ,2-di(m-methylphenoxy)ethane
  • DPE diphenoxyethane
  • Heat-sensitive recording material comprising
  • the heat-sensitive recording material additionally contains an interlayer between the supporting substrate and the heat-sensitive recording layer, wherein the interlayer preferably contains pigments;
  • organic pigments preferably hollow-body organic pigments
  • inorganic pigments preferably selected from the list consisting of calcinated kaolin, silica, bentonite, calcium carbonate, alumina and boehmite;
  • a heat-sensitive recording material wherein the heat-sensitive recording layer is wholly or partly covered by a protective layer.
  • Products preferably lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical diagram paper, fax paper, security paper or barcode labels, comprising a subject invention heat- sensitive recording material according to Embodiment 12.
  • TITO ticket-in, ticket-out
  • a heat-sensitive recording material as lottery tickets, ticket-in, ticket-out (TITO) tickets, travel tickets, entrance tickets, flight, rail, ship or bus ticket, gambling ticket, pay & display car park ticket, label, sales colour, bank statements, sticker, medical and/or technical diagram paper, fax paper, security paper or barcode labels.
  • TITO ticket-in, ticket-out
  • iv. preferably an above method comprising said steps i. to iii. for forming a heat-sensitive recording material or for forming a heat-sensitive recording layer and further comprising the method step of applying a protective layer to wholly or partly cover the heat-sensitive recording layer and drying the protective layer to obtain a heat-sensitive recording layer which combines with the supporting substrate to form a heat-sensitive recording material and is wholly or partly covered by the protective layer.
  • Compound preferably for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the compound comprises: a) at least one structural unit of lactic acid
  • the compound is a compound of Formula (B-l) as indicated and defined in Embodiment 7 and containing a structural unit of Formula (B-lc) as indicated and defined in Embodiment 8;
  • the compound is a compound of Formula (B-l) as indicated and defined in Embodiment 7 and as comprising two mutually independent terminal electron acceptor groups having the structural unit of Formula (B-lb) as indicated and defined in Embodiment 7; and wherein the compound of Formula (B- I) also includes a structural unit of Formula (B-lc) as indicated and defined in Embodiment 8;
  • the compound is a compound in which at least one structural unit of Formula (B-l Ma) and/or of Formula (B-lllb) of lactic acid or its lactide is present in the compound of Formula (B-l),
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2;
  • the compound is a compound of Formula (B-l) as indicated and defined in Embodiment 17, wherein the compound has one or two terminal structural units of Formula (B-lb), preferably two terminal structural units of Formula (B-lb),
  • Compound according to Embodiment 16 preferably for use as colour developer in a coating composition for forming a heat-sensitive recording material or as colour developer in a heat-sensitive recording layer or as colour developer in a coating colour for forming a coating composition or a heat-sensitive recording layer, wherein the particle sizes, measured by laser diffraction for the one or at least one compound of two or more compounds are each independently in the range from 0.5 to 10 ⁇ , preferably in the range from 0.8 to 8 ⁇ and more preferably in the range from 0.8 to 4 ⁇ ; or wherein the particle sizes measured as the X50 value by laser diffraction for the one or at least one of the more than one colour developers are each independently in the range from 0.8 to 2 ⁇ , preferably in the range from 0.85 to 1.7 ⁇ and more preferably in the range from 0.85 to 1.65 ⁇ .
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2, a compound of Formula (B-V),
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom;
  • reaction is carried out under conditions where the compound of Formula (B-V) does not decompose at all or at least not wholly, preferably under conditions where the temperature in the reaction is at least 1 °C, preferably at least 2 °C or 3 °C or 4 °C or 5 °C lower, more preferably at least 5 °C to 10 °C lower, than the decomposition temperature of a compound of Formula (B-V);
  • R3 and R4 are each independently a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group or a halogen atom, preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of Formula (B-VII) as precursor compound to an electron acceptor group,
  • a and b are each independently an integer from 1 to 10, preferably from 1 to 6, more preferably from 1 to 3 and most preferably 2, and
  • R3 and R4 are each independently a hydrogen atom, a C1 -C6 alkyl group, a C1 -C6 alkoxy group or a halogen atom , preferably a hydrogen atom or a methyl group, more preferably a methyl group, yet more preferably a p-toluenesulfonyl isocyanate of Formula (B-VI I) as precursor compound to an electron acceptor group,
  • R1 and R2 are each independently a hydrogen atom, a methyl group, preferably a hydrogen atom,

Abstract

La présente invention concerne un agent apte à réagir en présence d'un leuco-colorant lors du chauffage, ledit agent répondant à la formule (A-I). Dans la formule (A-I), R1 et R2 sont indépendamment un atome d'hydrogène, un groupe alkyle en C1-C6, un groupe alcoxy en C1-C6 ou un atome d'halogène ; R3, R4, R5 et R6 représentent indépendamment un atome d'hydrogène, un groupe alkyle en C1-C6, un groupe cycloalkyle en C3-C6 ou un groupe alcényle en C2-C6 ; X représente O, S ou NH ; et a et b sont des valeurs entières satisfaisant aux conditions a ≥ 0, b ≥ 0 et (a + b) ≥ 1. La présente invention concerne également un support d'enregistrement thermosensible ayant une couche révélatrice chromogène comprenant : un leuco-colorant ; et, un révélateur chromogène qui réagit en présence dudit leuco-colorant lors du chauffage pour former une couche colorée, ledit révélateur chromogène comprenant un agent répondant à ladite formule (A-I). La présente invention concerne également une composition de revêtement destinée à former un matériau d'enregistrement thermosensible ou une couche d'enregistrement thermosensible, comprenant un ou plusieurs précurseurs de colorant et un ou plusieurs révélateurs chromogènes à base d'unités d'acide lactique, ainsi qu'une couleur de revêtement destinée à former une composition de revêtement ou une couche d'enregistrement thermosensible, comprenant un ou plusieurs précurseurs de colorant et un ou plusieurs révélateurs chromogènes à base d'unités d'acide lactique, et en outre un matériau d'enregistrement thermosensible comprenant un substrat de support et une couche d'enregistrement thermosensible de l'invention, ainsi qu'un procédé de formation de ce matériau d'enregistrement thermosensible et l'utilisation de ce matériau d'enregistrement thermosensible. La présente invention concerne également une telle composition de revêtement ou une telle couche d'enregistrement thermosensible qui contient en outre au moins un autre révélateur chromogène qui n'est pas à base d'unités d'acide lactique. L'invention concerne enfin un composé à base d'unités d'acide lactique, de préférence destiné à être utilisé en tant que révélateur chromogène dans le contexte ci-dessus, ladite utilisation, et un procédé de formation de ce composé à base d'unités d'acide lactique.
EP18700648.1A 2017-01-10 2018-01-10 Nouveau révélateur chromogène destiné à un support d'enregistrement thermosensible, et matériau d'enregistrement thermosensible à base de pla Withdrawn EP3414099A1 (fr)

Priority Applications (1)

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EP19152586.4A EP3505358A1 (fr) 2017-01-10 2018-01-10 Nouveau révélateur de couleur pour un support d'enregistrement thermosensible

Applications Claiming Priority (3)

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EP17150842 2017-01-10
EP17201462.3A EP3482963A1 (fr) 2017-11-13 2017-11-13 Matériel d'enregistrement sensible à la chaleur à base de pla
PCT/EP2018/050574 WO2018130576A1 (fr) 2017-01-10 2018-01-10 Nouveau révélateur chromogène destiné à un support d'enregistrement thermosensible, et matériau d'enregistrement thermosensible à base de pla

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EP18700648.1A Withdrawn EP3414099A1 (fr) 2017-01-10 2018-01-10 Nouveau révélateur chromogène destiné à un support d'enregistrement thermosensible, et matériau d'enregistrement thermosensible à base de pla

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EP3505358A1 (fr) 2019-07-03
WO2018130576A1 (fr) 2018-07-19
DE202018107306U1 (de) 2019-01-28

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