SELF-ADHESIVE HEAT-SENSITIVE RECORDING MATERIAL

Description

[0001] The invention relates to a self-adhesive, heat-sensitive recording material comprising a carrier substrate, a heat-sensitive color-forming layer applied to one side of the carrier substrate, comprising at least one non-phenolic color developer and at least one color former, a siliconized layer on the upper side of the heat-sensitive color-forming layer applied to the carrier substrate, and an adhesive layer on the side of the carrier substrate facing away from the heat-sensitive color-forming layer, a method for its production, and its use. The invention also relates to a semi-finished product, its production, and its use for the production of the self-adhesive, heat-sensitive recording material.

[0002] Self-adhesive, heat-sensitive recording materials for direct thermal printing applications are known. These materials comprise a heat-sensitive, color-forming layer (thermo-reaction layer) applied to a substrate and an adhesive layer on the other side of the substrate. The heat-sensitive, color-forming layer typically contains a color former and a color developer, which react with each other under the influence of heat, resulting in color development. These self-adhesive, heat-sensitive recording materials are usually applied to a carrier web ("release liner" or simply "liner") to prevent the individual units of the self-adhesive, heat-sensitive recording material from sticking to each other.

[0003] So-called linerless, self-adhesive, heat-sensitive recording materials are also known. In these materials, a siliconized layer is typically applied to the heat-sensitive, ink-forming layer. These materials are characterized by the fact that they are not applied to a backing material but can be rolled up on themselves, so that the heat-sensitive, ink-forming layer, onto which a siliconized layer is applied, is in direct contact with the adhesive layer. Since components of the adhesive layer, especially the plasticizers, can attack the heat-sensitive, ink-forming layer, leading to reduced recording performance, these linerless, self-adhesive, heat-sensitive recording materials also have a protective layer ("topcoat") located between the heat-sensitive, ink-forming layer and the siliconized layer.

[0004] However, the use of a protective layer significantly increases manufacturing costs, negating the cost advantages of using a carrier-free material. Furthermore, the open-pored surface of conventional thermal papers without a protective layer does not allow for good silicone coating. Consequently, large amounts of silicone are required, which not only drive up manufacturing costs but also lead to deposits on the thermal printheads.

[0005] US patent 4,851,383 A discloses a self-adhesive, heat-sensitive recording material comprising a carrier material with a heat-sensitive layer on one side and an adhesive layer on the other. A protective layer on the top side of the heat-sensitive layer is provided with a siliconized layer.

[0006] DE 19757589 B4 discloses a carrierless heat-sensitive recording adhesive sheet, comprising a substrate, a heat-sensitive recording layer provided on one side of the substrate, a barrier layer provided on the heat-sensitive recording layer, a release layer provided on the barrier layer and an adhesive layer provided on the other side of the substrate, wherein the barrier layer is formed from a coating composition comprising colloidal silica in the form of a colloid containing water as a dispersing medium and at least one resin selected from water-soluble resins and water-dispersible resins.

[0007] US patent 5,840,657 discloses a multilayered, carrierless recording material with a heat-sensitive layer containing a phenolic color developer on one side and an adhesive layer on the other. Two further layers, a base layer and a top layer, made of a polymer are applied to the heat-sensitive layer. The carrier material is only partially coated to make selected areas of the surface printable.

[0008] EP3109059A1 (prior art according to Article 54(3) EPC) discloses a multilayer heat-sensitive recording material with a web-shaped substrate on which a heat-sensitive recording layer is arranged on the front side. This layer contains at least one dye precursor and at least one reactive (color) developer. The front surface of the heat-sensitive recording material is non-adhesive to adhesive layers that can be applied to the back of the web-shaped substrate. To form the non-adhesive front surface, a diffusion layer and a release agent coating are arranged above the heat-sensitive recording layer.

[0009] EP1637339A1 discloses a thermal recording material comprising a substrate, a thermal dye layer, and a protective layer, wherein the protective layer comprises at least a binder resin, a crosslinker, a filler, and a release agent, wherein the release agent is a spherical and particulate silicone compound of the formula (CH3SiO3 / 2)n, where n is an integer greater than 15.

[0010] EP0780241A1 discloses a heat-sensitive recording material comprising a carrier, a heat-sensitive recording layer formed thereon, which contains an electron-donating dye compound, an electron-accepting compound and a binder resin, and a protective layer formed on the heat-sensitive recording layer, which contains a UV-curing resin and a copolymer resin, which contains a silicone component as a copolymerizing component.

[0011] EP2957427A1 discloses a heat-sensitive recording material with high recording density, excellent plasticizer resistance in the recorded areas and excellent resistance to thermal background fogging in high-temperature environments, which contains a specific sulfonamide compound.

[0012] The object of the present invention is to overcome the disadvantages of the prior art described above. In particular, it is an object to provide a self-adhesive, heat-sensitive recording material with the lowest possible production costs, which also exhibits high resistance to the plasticizers contained in the adhesive layer and, in addition to a desirable high dynamic pressure sensitivity, also displays good storage stability, especially under conditions of high storage temperature and ambient humidity, without losing the functional properties necessary for the application, such as surface whiteness and thermal response sensitivity. Furthermore, the self-adhesive, heat-sensitive recording material should allow for good siliconization of the surface of the heat-sensitive ink-forming layer.Furthermore, it is desirable to provide a self-adhesive, heat-sensitive recording material that can also be used without a backing. Finally, it is desirable to provide an environmentally suitable recording material.

[0013] According to the invention, this problem is solved with a self-adhesive heat-sensitive recording material according to claim 1, comprising a carrier substrate, a heat-sensitive color-forming layer applied to one side of the carrier substrate, comprising at least one non-phenolic color developer and at least one color former, a siliconized layer on the top side of the heat-sensitive color-forming layer applied to the carrier substrate, and an adhesive layer on the side of the carrier substrate facing away from the heat-sensitive color-forming layer, characterized in that the heat-sensitive color-forming layer comprises at least one platelet-shaped pigment, wherein the particle size of the platelet-shaped pigment is adjusted such that at least 70% of the particles have a particle size of < 2 µm, determined by sedigraphy, and the siliconized layer lies directly on the heat-sensitive color-forming layer.

[0014] Due to the direct contact of the siliconized layer with the heat-sensitive color-forming layer and the associated absence of a protective layer between the siliconized layer and the heat-sensitive color-forming layer, the production of the self-adhesive heat-sensitive recording material according to the invention involves significantly less effort and significantly lower costs.

[0015] The heat-sensitive, color-forming layer contains at least one platelet-shaped pigment.

[0016] The at least one platelet-shaped pigment is preferably selected from the group consisting of kaolin, Al(OH)₃ and / or talc. The use of kaolin is particularly preferred. The use of a spreadable kaolin is especially preferred. Such a product is available, for example, under the trade name Kaolin ASP 109 (BASF, Germany).

[0017] The use of these plate-shaped pigments, especially kaolin, has the main advantage that the heat-sensitive color-forming layer can be siliconized very well.

[0018] A platelet-shaped pigment is understood to be a pigment in which the ratio of diameter to thickness is approximately 7 to 40 to 1, preferably approximately 15 to 30 to 1.

[0019] The particle size of the platelet-shaped pigment is adjusted such that at least approximately 70%, preferably at least approximately 85%, of the particles have a particle size of approximately < 2 µm (sedigraph). The pH value of the platelet-shaped pigment in aqueous solution is preferably 6 to 8.

[0020] The at least one platelet-shaped pigment is present in the heat-sensitive, color-forming layer of the self-adhesive, heat-sensitive recording material according to the invention, preferably in an amount of about 5 to about 60 wt.%, particularly preferably in an amount of about 15 to about 55 wt.%, based on the total solids content of the heat-sensitive layer. If less than 5 wt.% of the platelet-shaped pigment is present, this has the disadvantage that good siliconizability is no longer guaranteed. The use of more than 60 wt.% has the disadvantage that the tendency to deposit on the printhead increases and the writing performance decreases, since the ratios between pigments, binder, colorant, and developer are negatively affected.

[0021] The choice of substrate is not critical. However, it is preferred to use paper, synthetic paper and / or a plastic film as the substrate.

[0022] Preferably, the self-adhesive heat-sensitive recording material according to the invention is a linerless self-adhesive heat-sensitive recording material.

[0023] Carrierless in this context means that the self-adhesive, heat-sensitive recording material according to the invention is not applied to a carrier material, but is wound onto itself. This has the advantage that manufacturing costs can be further reduced, more linear meters per roll are achievable, no disposal costs for the liner are necessary, and more labels can be transported per specific cargo space volume.

[0024] The at least one non-phenolic color developer is preferably a sulfonyl urea and / or a compound of formula (I) where Ar 1 and Ar 2 are a phenyl group and / or a C 1 -C 4 -alkyl-substituted phenyl group.

[0025] A compound of formula (I) is particularly preferred.

[0026] The C1-C4 alkyl-substituted phenyl residue is preferably a methyl residue, particularly preferably a para-methyl residue.

[0027] In a particularly preferred embodiment, Ar 1 and Ar 2 are a para-methyl-substituted phenyl residue.

[0028] In a further particularly preferred embodiment, Ar 1 is a phenyl residue and Ar 2 is a para-methyl-substituted phenyl residue.

[0029] In a particularly preferred embodiment, Ar 1 and Ar 2 are each a phenyl residue, i.e., the at least one color developer is N-(2-(3-Phenylureido)phenyl)benzenesulfonamide (hereinafter also referred to as NKK 1304; manufacturer: Nippon Soda Co.Ltd.).

[0030] The sulfonyl urea contained in the color-forming heat-sensitive layer of the self-adhesive heat-sensitive recording material according to the invention, additionally or instead of a color developer according to formula (I), is preferably selected from the group consisting of N'-(p-toluenesulfonyl)-N'-phenyl urea, N-(p-toluenesulfonyl)-N'-3-(p-toluenesulfonyl-oxyphenyl) urea, (trade name Pergafast 201 ®< , PF201 of BASF) and / or 4,4'-bis-(p-tolylsulfonylureido)-diphenylmethane.

[0031] Particularly preferred is an embodiment of the self-adhesive heat-sensitive recording material characterized in that the heat-sensitive color-forming layer contains N-(2-(3-Phenylureido)-phenyl)benzenesulfonamide (NKK 1304) and / or N-(p-Toluenesulfonyl)-N'-3-(p-toluenesulfonyl-oxy-phenyl)-urea (Pergafast 201 (PF201), from BASF) as a color developer.

[0032] The use of N-(2-(3-Phenylureido)phenyl)benzenesulfonamide (NKK 1304) and / or N-(p-Toluenesulfonyl)-N'-3-(p-toluenesulfonyl-oxyphenyl)-urea (PF201) has the particular advantage that the writing performance is good even after prolonged storage.

[0033] The most preferred option is the use of N-(2-(3-Phenylureido)phenyl)benzenesulfonamide (NKK 1304), as its use leads to even better writing performance even after prolonged storage.

[0034] The use of a non-phenolic color developer is environmentally friendly.

[0035] The sulfonylurea and / or the compound of formula (I) are preferably present in an amount of about 5 to about 40 wt.%, particularly preferably in an amount of about 10 to about 25 wt.%, based on the total solids content of the heat-sensitive layer. If the amount of color developer falls below 5 wt.%, the writing performance is compromised. If the amount of color developer exceeds 40 wt.%, the cost-effectiveness suffers without any significant increase in writing performance.

[0036] The present invention is not subject to any significant limitations with regard to the choice of color former. However, the color former is preferably a triphenylmethane-type, fluorane-type, azaphthalide-type, and / or fluorene-type dye. A fluorane-type dye is particularly preferred because its availability and balanced application-related properties enable the provision of a recording material with an attractive price-performance ratio.

[0037] Particularly favored fluorane-type dyes are: 3-Diethylamino-6-methyl-7-anilinofluoran, 3-(N-Ethyl-N-p-toludinamino)-6-methyl-7-anilinofluoran, 3-(N-Ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran, 3-Diethylamino-6-methyl-7-(o,p-dimethylanilino)fluoran, 3-Pyrrolidino-6-methyl-7-anilinofluoran, 3-(Cyclohexyl-N-methylamino)-6-methyl-7-anilinofluoran, 3-Diethylamin-7-(m-trifluoromethylanilino)fluoran, 3-N-n-Dibutylamin-6-methyl-7-anilinofluoran, 3-Diethylamino-6-methyl-7-(m-methylanilino)fluoran, 3-N-n-Dibutylamin-7-(o-chloroanilino) fluoran, 3-(N-Ethyl-N-tetrahydrofurfurylamin)-6-methyl-7-anilino-fluoran, 3-(N-Methyl-N-propylamin)-6-methyl-7-anilinofluoran, 3-(N-Ethyl-N-ethoxypropylamin)-6-methyl-7-anilinofluoran, 3-(N-Ethyl-N-isobutylamin)-6-methyl-7-anilinofluoran und / oder 3-Dipentylamin-6-methyl-7-anilinfluoran.

[0038] The at least one color former is preferably present in an amount of about 2 to about 20 wt.%, preferably about 5 to about 15 wt.%, based on the total solids content of the heat-sensitive layer.

[0039] If, in addition to the at least one color former, another color former is present, it is preferably present in an amount of 0.5 to 5 wt.%, based on the total solid content of the heat-sensitive layer.

[0040] If the amount of colorant falls below 2% by weight, the functionality is no longer guaranteed. If the amount of colorant exceeds 20% by weight, the efficiency suffers significantly without a corresponding increase in writing performance.

[0041] The self-adhesive heat-sensitive recording material according to the invention can contain conventional additives in the heat-sensitive color-forming layer, such as sensitizing agents, stabilizers, binders, release agents and / or brighteners.

[0042] In general, substances whose melting point is between about 90 and about 150°C are advantageously considered as sensitizing agents and which, in the molten state, dissolve the color-forming components (color formers and color developers) without disturbing the formation of the color complex.

[0043] Preferably, the sensitizing agent is a fatty acid amide, such as stearamide, behenamide or palmitamide; an ethylenebis fatty acid amide, such as N,N'-ethylenebis-stearic acid amide or N,N'-ethylenebis-oleic acid amide; a wax, such as polyethylene wax or montan wax; a carboxylic acid ester, such as dimethyl terephthalate, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-(p-methylbenzyl)oxalate, di-(p-chlorobenzyl)oxalate or di-(p-benzyl)oxalate; an aromatic ether, such as 1,2-diphenoxyethane, 1,2-di-(3-methylphenoxy)ethane, 2-benzyloxynaphthalene or 1,4-diethoxynaphthalene; an aromatic sulfone, such as diphenylsulfone; and / or an aromatic sulfonamide, such as benzenesulfonanilide or N-Benzyl-p-toluenesulfonamide.

[0044] The use of fatty acid amides is particularly preferred, as they are inexpensive to purchase.

[0045] The stabilizer preferably consists of sterically hindered phenols, particularly preferably 1,1,3-Tris-(2-methyl-4-hydroxy-5-cyclohexyl-phenyl)-butane, 1,1,3-Tris-(2-methyl-4-hydroxy-5-tert-butylphenyl)-butane, 1,1-Bis-(2-methyl-4-hydroxy-5-tert-butyl-phenyl)-butane.

[0046] Urea-urethane compounds of general formula (II), commercial product UU (urethanes), or ethers derived from 4,4'-dihydroxydiphenylsulfone, such as 4-benzyloxy-4'-(2-methylglycidyloxy)-diphenylsulfone (trade name NTZ-95 ®< , Nippon Soda Co. Ltd.), or oligomeric ethers of general formula (III) (trade name D90 ®< , Nippon Soda Co. Ltd.) can also be used as stabilizers in the recording material according to the invention.

[0047] The urea-urethane compounds of general formula (II) are particularly preferred.

[0048] In a further preferred embodiment, the heat-sensitive, color-forming layer contains at least one binder. This binder is preferably water-soluble starches, starch derivatives, methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, partially or fully saponified polyvinyl alcohols, chemically modified polyvinyl alcohols or styrene maleic anhydride copolymers, styrene-butadiene copolymers, acrylamide-(meth)acrylate copolymers, acrylamide-acrylate-methacrylate terpolymers, polyacrylates, poly(meth)acrylic acid esters, acrylate-butadiene copolymers, polyvinyl acetates and / or acrylonitrile-butadiene copolymers.

[0049] In a further preferred embodiment, at least one release agent (non-stick agent) or lubricant is present in the heat-sensitive, color-forming layer. These agents are preferably fatty acid metal salts, such as zinc stearate or calcium stearate, or also behenate salts, synthetic waxes, e.g., in the form of fatty acid amides, such as stearamide and behenamide, fatty acid alkanolamides, such as stearamide methylolamide, paraffin waxes of different melting points, ester waxes of different molecular weights, ethylene waxes, propylene waxes of different hardnesses, and / or natural waxes, such as carnauba wax or montan wax.

[0050] To control the surface whiteness of the heat-sensitive recording material according to the invention, optical brighteners can be incorporated into the heat-sensitive color-forming layer. These are preferably stilbenes.

[0051] In order to improve certain coating properties, it is preferred in individual cases to add further components, in particular rheology aids such as thickeners and / or surfactants, to the essential components of the heat-sensitive recording material according to the invention.

[0052] The surface application weight of the (dry) heat-sensitive, ink-forming layer of the self-adhesive, heat-sensitive recording material according to the invention is preferably about 1 to about 10 g / m², and particularly preferably about 2 to about 6 g / m². If the surface application weight falls below 1 g / m², the material loses its functionality. If the surface application weight exceeds 10 g / m², it becomes uneconomical and negative properties, such as adhesion to the printhead, increase.

[0053] As mentioned above, a siliconized layer is located directly on the heat-sensitive, color-forming layer. This siliconized layer is preferably based on at least one siloxane. In this preferred embodiment, this is at least one poly(organo)siloxane, in particular an acrylic poly(organo)siloxane.

[0054] In a further embodiment, the siliconized layer of the self-adhesive, heat-sensitive recording material according to the invention comprises a mixture of at least two siloxanes. A mixture of at least two acrylic poly(organo)siloxanes is preferred.

[0055] Examples of particularly preferred siloxanes are siloxanes known under the trade names TEGO®< RC902 and TEGO®< RC711 (both from Evonik, Germany).

[0056] The surface weight of the siliconized layer is approximately 0.3 to approximately 2.5 g / m², preferably approximately 0.5 to approximately 1.5 g / m², and most preferably approximately 0.6 to approximately 1.0 g / m². If the surface weight falls below 0.3 g / m², the release effect is no longer effective. If the surface weight exceeds 2.5 g / m², the cost-effectiveness decreases and the risk of deposits on the printer's thermal printhead increases.

[0057] The siliconized layer is preferably anhydrous. It is also preferred that the siliconized layer does not contain any Pt catalysts.

[0058] The siliconized layer preferably contains an initiator, particularly preferably a photoinitiator. This serves to cure the silicon by radical action. The TEGO® photoinitiator A18 (from Evonik, Germany) is especially preferred. The siliconized layer may preferably contain further additives, such as matting agents and / or adhesion promoters.

[0059] The adhesive layer, which is applied to the side of the carrier material facing away from the heat-sensitive color-forming layer, comprises at least one adhesive, preferably a hot melt adhesive.

[0060] Preferably, the hot melt adhesive is a rubber- and / or acrylate-based hot melt adhesive.

[0061] Examples of particularly preferred hot melt adhesives are known under the trade names TLH4280E (Bostik), PS8746 (Henkel / Technomelt), PS1212 (Novamelt) and / or L1945 (Collano).

[0062] The surface application weight of the adhesive layer is preferably about 10 to about 40 g / m², particularly preferably about 12 to about 25 g / m². If the surface application weight falls below 10 g / m², the adhesive effect is no longer effective. If the surface application weight exceeds 40 g / m², the cost-effectiveness decreases and the risk of deflection rollers and cutting blades in label dispensers becomes clogged.

[0063] In a particularly preferred embodiment, the self-adhesive, heat-sensitive recording material according to the invention is carrier-free, the at least one color developer is a sulfonyl urea, and the platelet-shaped pigment is a coating kaolin. In this particularly preferred embodiment, the sulfonyl urea is present in an amount of about 5 to about 40% by weight, based on the total solids content of the heat-sensitive layer. The platelet-shaped pigment is present in this particularly preferred embodiment in an amount of about 5 to about 60% by weight, based on the total solids content of the heat-sensitive layer.

[0064] In a particularly preferred embodiment, the self-adhesive, heat-sensitive recording material according to the invention is carrier-free, the at least one color developer is N-(2-(3-phenylureido)phenyl)benzenesulfonamide, and the platelet-shaped pigment is a coating kaolin. In this embodiment, the amounts of N-(2-(3-phenylureido)phenyl)benzenesulfonamide and platelet-shaped kaolin used are also approximately 5 to approximately 40 wt.% and approximately 5 to approximately 60 wt.%, respectively.

[0065] The self-adhesive, heat-sensitive recording material according to the invention can be obtained using known manufacturing methods.

[0066] The manufacturing process according to the invention is characterized in that an aqueous suspension containing the starting materials of the heat-sensitive color-forming layer, comprising at least one non-phenolic color developer, at least one color former and at least one platelet-shaped pigment, wherein the particle size of the platelet-shaped pigment is adjusted so that at least 70% of the particles have a particle size of < 2µm, determined by sedigraphy, is applied to a carrier substrate and dried, the heat-sensitive color-forming layer is subsequently siliconized and an adhesive layer is applied to the side of the carrier substrate facing away from the heat-sensitive color-forming layer.

[0067] The self-adhesive heat-sensitive recording material according to the invention is particularly preferably obtained by a process in which an aqueous suspension containing the starting materials of the heat-sensitive color-forming layer is applied to a carrier substrate and dried, wherein the aqueous application suspension has a solids content of about 20 to about 75 wt.%, preferably about 25 to about 50 wt.%, and is applied and dried using the curtain coating process at an operating speed of the coating system of at least about 400 m / min, the heat-sensitive color-forming layer is subsequently siliconized, and an adhesive layer is applied to the side of the carrier substrate facing away from the heat-sensitive color-forming layer.

[0068] This method is particularly advantageous from an economic point of view.

[0069] If the solids content falls below approximately 20% by weight, efficiency deteriorates because a large quantity of water must be removed from the coating quickly through gentle drying, which negatively impacts the application speed. Conversely, if the value exceeds 75% by weight, this only results in increased technical effort to ensure the stability of the coating curtain during the application process.

[0070] As mentioned above, it is advantageous to produce the self-adhesive, heat-sensitive recording material according to the invention using a method in which the aqueous coating suspension is applied using the curtain coating method at an operating speed of the coating system of at least approximately 400 m / min. The so-called curtain coating method is known to those skilled in the art and is characterized by the following criteria: In the curtain coating method, a freely falling curtain of coating dispersion is formed. By falling freely, the coating dispersion, which is present in the form of a thin film (curtain), is "poured" onto a substrate in order to apply the coating dispersion to the substrate. DE 10196052 T1 discloses the use of the curtain coating method in the production of information recording materials, among other things.also of heat-sensitive recording materials, whereby multilayer recording layers are created by applying the curtain consisting of several coating dispersion films to substrates.

[0071] Setting the operating speed of the coating machine to at least approximately 400 m / min offers both economic and technical advantages. A particularly preferred operating speed is at least approximately 750 m / min, a very preferred speed is at least approximately 1000 m / min, and a very preferred speed is at least approximately 1500 m / min. It was particularly surprising that even at the latter speed, the heat-sensitive recording material is in no way affected and that the operation proceeds optimally even at this high speed.

[0072] In a preferred embodiment of the process according to the invention, the aqueous deaerated coating suspension has a viscosity of approximately 100 to approximately 1000 mPas (Brookfield, 100 rpm, 20 °C). If the value falls below approximately 100 mPas or exceeds approximately 1000 mPas, this leads to poor flowability of the coating compound on the coating unit. Particularly preferably, the viscosity of the aqueous deaerated coating suspension is approximately 150 to approximately 700 mPas.

[0073] In a preferred embodiment, to optimize the process, the surface tension of the aqueous coating suspension can be adjusted to approximately 30 to approximately 60 mN / m, preferably to approximately 35 to approximately 50 mN / m (measured according to the static ring method according to Du Noüy, DIN 53914).

[0074] The formation of the heat-sensitive, color-forming layer can take place online or in a separate offline application process. This also applies to any subsequent layers or intermediate coats.

[0075] It is advantageous to subject the dried, heat-sensitive, color-forming layer to a smoothing process. In this process, it is advantageous to adjust the Bekk smoothness, measured according to DIN 53101, to approximately 150 to approximately 1500 seconds, preferably to approximately 250 to approximately 800 seconds.

[0076] The preferred embodiments listed in connection with the self-adhesive heat-sensitive recording material according to the invention also apply to the method according to the invention.

[0077] The present invention also relates to a self-adhesive heat-sensitive recording material obtainable according to the inventive method described above.

[0078] The present invention further comprises a method for producing a semi-finished product for a self-adhesive, heat-sensitive recording material, characterized in that an aqueous suspension containing the starting materials of the heat-sensitive color-forming layer, comprising at least one non-phenolic color developer, at least one color former, and at least one platelet-shaped pigment, wherein the particle size of the platelet-shaped pigment is adjusted such that at least 70% of the particles have a particle size of < 2 µm, as determined by sedigraphy, is applied to a carrier substrate and dried. The semi-finished product for a self-adhesive, heat-sensitive recording material according to the invention is thus produced analogously to the self-adhesive, heat-sensitive recording material according to the invention, but without subsequent siliconization and application of the adhesive layer.

[0079] The preferred embodiments mentioned in connection with the self-adhesive heat-sensitive recording material according to the invention and the method for producing it apply accordingly to the method for producing the semi-finished product for a self-adhesive heat-sensitive recording material and to the semi-finished product itself, which is also encompassed by the present invention.

[0080] The present invention further comprises the use of a semi-finished product for a self-adhesive heat-sensitive recording material comprising a carrier substrate, a heat-sensitive color-forming layer applied to one side of the carrier substrate, comprising at least one non-phenolic color developer, at least one color former and at least one platelet-shaped pigment, wherein the particle size of the platelet-shaped pigment is adjusted such that at least 70% of the particles have a particle size of < 2µm, determined by sedigraphy, for the production of a self-adhesive heat-sensitive recording material as described above.

[0081] The advantages associated with the present invention can be summarized essentially as follows: The present invention provides a self-adhesive, heat-sensitive recording material, which is preferably carrier-free and exhibits not only a desirable high dynamic pressure sensitivity but also exceptionally good storage stability, particularly under conditions of high storage temperature and ambient humidity, without losing the functional properties necessary for the application, such as surface whiteness and thermal response sensitivity. Furthermore, the composition of the heat-sensitive, color-forming layer allows for good siliconization. The self-adhesive, heat-sensitive recording material according to the invention is preferably carrier-free and can therefore be wound onto itself.The color-forming layer exhibits high resistance to the components of the adhesive layer, particularly to hydrophobic substances such as plasticizers, greasy or oily substances, etc. This enables the provision of a carrier-free, self-adhesive, heat-sensitive recording material. Furthermore, the self-adhesive, heat-sensitive recording material according to the invention is environmentally friendly.

[0082] The self-adhesive, heat-sensitive recording material according to the invention is well suited for POS (point-of-sale) and / or label applications. It is also suitable for the production of stickers, labels, and luggage tags.

[0083] The invention is explained in detail below using unrestricted examples. Examples:

[0084] The application of an aqueous coating suspension to form the heat-sensitive ink-forming layer of a heat-sensitive recording paper was carried out on a laboratory scale using a doctor blade on one side of a 69 g / m² thermal base paper. After drying, a thermal recording sheet was obtained. The amount of the heat-sensitive ink-forming layer applied was between 4.0 and 4.5 g / m².

[0085] On a production scale, the aqueous coating suspension was applied to a paper web with a basis weight of 64 g / m² using the curtain coating process. The viscosity of the aqueous coating suspension was 170–570 mPas (according to Brookfield, 100 rpm, 20 °C) (in the deaerated state). The coating unit was arranged in-line. The curtain coating process was operated at a speed of 450 m / min.

[0086] After application of the aqueous coating suspension, the coated paper substrate was dried in the usual manner. The basis weight of the dry, heat-sensitive layer was 4.0–4.5 g / m².

[0087] The following formulations were produced by first mixing dispersions A1, A2, B and C separately by grinding the components in a bead mill, and then thoroughly mixing these dispersions together with the other components.

[0088] The heat-sensitive coating suspensions thus obtained (formulations 1a, 1b, 2a, , 2b, and 3), which result from Tables 1 to 6 below, were used to produce semi-finished products from paper carrier and heat-sensitive color-forming layer. Table 1: Recipe 1a component Weighted parts remark / Trade name chemical nomenclature Dispersion A1 Color Former 1 11,06 5-205 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 20,04 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion A2 Color Former 2 16,58 OBD-2 3-Nn-Dibutylamino-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 30,05 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion B Color developer 76,79 Bisphenol A 4,4'-Isopropylenediphenol PVA low viscosity, low saponification (15%) 54,41 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion C Sensitization aid 25,62 Receipt 2-Benzyloxynaphthalene PVA low viscosity, low saponification (15%) 18,15 Poval 4-85, Kuraray company Polyvinyl alcohol solution Stearic acid amide dispersion (25%) 108,17 Zinc stearate dispersion (30%) 54,9 PCC slurry (56%) 121,77 precipitated calcium carbonate optical brightener (31.3%) 5,75 Blankophor PT anionic stilbene derivative PVA high viscosity, highly saponified (10%) 330 Poval 28-99 Polyvinyl alcohol solution Crosslinker, glyoxal-based (42%) 11,29 Cartabond type, Archroma company Rheology aids 0,83 Sterocoll type, BASF Anionically modified polyacrylamide Table 2: Recipe 1b component Weighted parts remark / Trade name chemical nomenclature Dispersion A1 Color Former 1 11,06 S-205 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 20,04 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion A2 Color Former 2 16,58 OBD-2 3-Nn-Dibutylamino-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 30,05 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion B Color developer 76,79 Bisphenol A 4,4'-Isopropylenediphenol PVA low viscosity, low saponification (15%) 54,41 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion C Sensitization aid 25,62 Receipt 2-Benzyloxynaphthalene PVA low viscosity, low saponification (15%) 18,15 Poval 4-85, Kuraray company Polyvinyl alcohol solution Stearic acid amide dispersion (25%) 108,17 Zinc stearate dispersion (30%) 54,9 Kaolin slurry (72%) 94,71 ASP-109 optical brightener (31.3%) 5,75 Blankophor PT anionic stilbene derivative PVA high viscosity, highly saponified (10%) 330 Poval 28-99 Polyvinyl alcohol solution Crosslinker, glyoxal-based (42%) 11,29 Cartabond type, Archroma company Rheology aids 0,83 Sterocoll type, BASF Anionically modified polyacrylamide Table 3: Recipe 2a component Weighted parts remark / Trade name chemical nomenclature Dispersion A1 Color Former 1 9,0 S-205 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 16,31 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion A2 Color Former 2 21,0 OBD-2 3-Nn-Dibutylamino-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 38,05 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion B Color developer 60 NKK 1304 N-[2-(3-Phenylureido)phenyl]benzenesulfone amide PVA low viscosity, low saponification (15%) 70,59 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion C Sensitization aid 36 Receipt 2-Benzyloxynaphthalene PVA low viscosity, low saponification (15%) 25,51 Poval 4-85, Kuraray company Polyvinyl alcohol solution Stearic acid amide dispersion (25%) 176,77 Zinc stearate dispersion (30%) 0 Kaolin slurry (72%) 94,88 ASP 109, BASF optical brightener (31.3%) 2,88 Blankophor PT anionic stilbene derivative PVA high viscosity, highly saponified (10%) 330 Poval 28-99, Kuraray Company Polyvinyl alcohol solution Crosslinker, glyoxal-based (42%) 11,29 Cartabond type, Archroma company Rheology aids 0,83 Sterocoll type, BASF Anionically modified polyacrylamide Table 4: Recipe 2b component Weighted parts remark / Trade name chemical nomenclature Dispersion A1 Color Former 1 0 S-205 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 0 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion A2 Color Former 2 30,0 OBD-2 3-Nn-Dibutylamino-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 54,36 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion B Color developer 60 PF201 N-(p-Toluenesulfonyl)-N'-(3-(p-Toluenesulfonyloxy)phenyl)urea) PVA low viscosity, low saponification (15%) 70,59 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion C Sensitizing agents 36 Receipt 2-Benzyloxynaphthalene PVA low viscosity, low saponification (15%) 25,51 Poval 4-85, Kuraray company Polyvinyl alcohol solution Stearic acid amide dispersion (25%) 176,77 Zinc stearate dispersion (30%) 0 Kaolin slurry (72%) 94,88 ASP 109, BASF optical brightener (31.3%) 2,88 Blankophor PT anionic stilbene derivative PVA high viscosity, highly saponified (10%) 330 Poval 28-99, Kuraray Company Polyvinyl alcohol solution Crosslinker, glyoxal-based (42%) 11,29 Cartabond type, Archroma company Rheology aids 0,83 Sterocoll type, BASF Anionically modified polyacrylamide Table 5: Recipe 3 component Weighted parts remark / Trade name chemical nomenclature Dispersion A1 Color Former 1 0 S-205 3-(N-ethyl-N-isopentylamino)-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 0 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion A2 Color Former 2 29 OBD-2 3-Nn-Dibutylamino-6-methyl-7-anilinofluoran PVA low viscosity, low saponification (15%) 52,54 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion B Color developer 46,4 PF201 N-(p-toluenesulfonyl)-N'-(3-(p-toluenesulfonyloxy)phenyl)urea PVA low viscosity, low saponification (15%) 30,94 Poval 4-85, Kuraray company Polyvinyl alcohol solution Dispersion C Sensitizing agents 15,47 Receipt 2-Benzyloxynaphthalene PVA low viscosity, low saponification (15%) 10,96 Poval 4-85, Kuraray company Polyvinyl alcohol solution Stearic acid amide dispersion (25%) 213,6 Zinc stearate dispersion (30%) 41,26 Kaolin slurry (72%) 117,85 ASP 109, BASF optical brightener (31.3%) 1,85 Blankophor PT anionic stilbene derivative PVA high viscosity, highly saponified (10%) 290 Poval 28-99 Polyvinyl alcohol solution Crosslinker, glyoxal-based (42%) 9,94 Cartabond type, Archroma company Rheology aids 1,61 Sterocoll type, BASF Anionically modified polyacrylamide

[0089] For siliconization, a mixture of 50 parts TEGO RC902, 25 parts TEGO RC711, and 25 parts TEGO RC1772 (as a matting agent) was prepared, plus 3 to 5 parts SR9051 as an adhesion additive and 1.5 parts photoinitiator A18 (manufacturer: Evonik, Germany; exception: SR9051 from Sartomer, Archema Group). Siliconization of the heat-sensitive, color-forming layer was carried out using a five-roller application process with prior corona treatment.

[0090] The self-adhesive, heat-sensitive recording materials based on the application suspensions listed in Tables 1 to 5 were carrier-free and were evaluated as described below. The results are shown in Tables 6 and 7.

[0091] Storage stability of the carrierless self-adhesive heat-sensitive recording material:To assess the storage stability of a carrierless self-adhesive heat-sensitive recording material, the heat-sensitive recording material, which is siliconized on the top side (i.e., directly on the thermoreaction layer), was coated on both sides with hot melt adhesives to simulate a roll winding (i.e., adhesive influence from the top and bottom).

[0092] The adhesives used were Technomelt PS 8746 (Henkel) and Collano L1 945 (Collano). These were already available coated on a carrier film.

[0093] To carry out the experiment, the respective adhesive film was first laminated to the back of the thermal paper at room temperature, and then a checkerboard pattern with 10 energy levels was thermally printed using an Atlantek 200 thermal printer. The image density (optical density, OD) of the printed image was measured using a SpectroEye densitometer (X-Rite).

[0094] Another strip of the same thermal paper, laminated on the reverse side in the same manner but no longer thermally printed, was also laminated on the top side with the adhesive film and then stored in a climate-controlled chamber at 60°C / 50% relative humidity between Plexiglas plates and a weight load of 10.5 kg. After defined intervals of 1, 2, and 4 weeks, a sample was taken and acclimatized at room temperature for 1 hour. The adhesive film was then removed from the top side, and the thermal side was dynamically printed on using the Atlantek 200 thermal printer to determine the remaining print quality. The following applies: % Ver ä nderung der Schreibleistung = Bilddichte nach Lagerung Bilddichte vor Lagerung − 1 ∗ 100 % (Image density determined at an energy density of 0.45 mJ / dot) Determination of the cut-off values

[0095] The method used allows the determination of the force required to peel the release paper from the adhesive-coated top layer. This enables a preliminary assessment of processing behavior – very low values ​​result in premature label detachment during the manufacturing or dispensing process – high values ​​lead to tearing during die-cutting grid removal or dispensing problems in automated dispensing.

[0096] The separation force at slow pull-off is the force required to peel a self-adhesive coated material from its release paper (or vice versa, the release paper from the self-adhesive material) at an angle of 180° and a clamping speed of 300 mm / min. Required equipment:

[0097] A test device capable of separating a composite material with a pull-off angle of 180° and a clamping speed of 300 mm / min at an accuracy of ±2% was used. The test device had a backplate on which test strips were mounted to maintain a 180° angle during testing. Metal bearing weights applied a pressure of 6.86 kPa (70 g / cm²) to the material samples. The test strips were cut from a representative sample of the material. The strips were 50 mm wide and at least 175 mm long in the direction of travel. The cut was clean and straight. At least three strips were provided for each material sample. Conditions:

[0098] The test strips were stored for 20 hours at 23 ±2°C between two flat metal plates under a pressure of 6.86 kPa (70 g / cm²). This ensured good contact between the release agent and the adhesive. After this pressure storage, the strips were removed from between the plates and acclimatized for at least four hours under standard conditions (23 ±2°C and 504 ± 5% RH) before measurement. Testing procedure:

[0099] Each test strip was fully adhered to the test plate using double-sided adhesive tape, allowing for a 180° peel test. During this test, the label was separated from the release material. The clamping speed was set to 300 mm / min. The force was measured five times at 10 mm intervals in the center of the strip during the test. The average force for each strip was calculated from these five measurements. Results:

[0100] The breaking force during slow trigger pull is given as an average value in centinewtons per 50 mm (cN / 50 mm).

[0101] The separation values ​​were determined using two different adhesives (tesa 7475 and 7476). Silicone application instructions

[0102] This test method enables a fast and accurate determination of the silicone content of a release coating with minimal sample preparation. The release coating is located on a carrier material, such as that used to manufacture release materials for self-adhesive labels or other release applications. Definition:

[0103] The silicone application weight is defined as the amount of cured silicone release coating per standard area of ​​a substrate. It is specified in grams per square meter (g / m²). Devices:

[0104] The method is based on the analysis of X-ray fluorescence (XRF). Material samples:

[0105] A suitable number of test specimens were taken from a representative sample of the cover material of a laminate or siliconized release agent under investigation. Contamination of the samples, especially with silicone-containing material, was avoided. The samples were cut or punched onto a dry, clean sheet of tissue paper and then handled only by the edges with tweezers. Preconditioning of the samples was not required. Testing procedure:

[0106] The samples were then inserted into the instrument and moved into a special measuring chamber, where irradiation with primary X-rays induces the emission of secondary X-ray fluorescence, which is characteristic of the element under investigation, in this case silicon. After 30 to 60 seconds, the measurement was complete, and the program directly displayed the silicon coating weight in g / m² (see also "Results" below). XRF is a relative, not an absolute, method. Therefore, a calibration curve had to be established before routine analyses could be performed. Calibration requires setting up the instrument to register silicon X-rays and then measuring known standards. However, it must be emphasized that each substrate material produces a different background radiation.Therefore, to create the calibration curve, it is not only necessary to measure a series of different silicone coating weights, but also to do so separately for each substrate material. Results:

[0107] The results are given directly in grams of silicone per square meter. It should be noted that the conversion from elemental silicon to silicone has already been performed.

[0108] Several samples were taken from a representative coated substrate to detect possible variations across the web width. Generally, the longer the measurement time, the higher the measurement accuracy. Accuracies are on the order of ±0.05 to ±0.01 (g / m²). Methylene blue test Scope:

[0109] This test procedure describes a method for evaluating the coverage quality of silicone coatings. This test can only be performed with paper substrates that can be stained with the dye test solution used. Definition:

[0110] The coating quality is assessed by testing with methylene blue as a dye. A specific amount of the dye is applied to the silicone-coated liner for a limited time; the dye is then rinsed or wiped off, and the liner is dried. The coating quality is then evaluated visually. Procedure:

[0111] a. A 1-liter polyethylene bottle was placed on an electronic scale. b. 5 grams of methylene blue were weighed into the bottle. c. 1 liter of distilled water was added using a graduated cylinder. The bottle was sealed and shaken vigorously to dissolve the dye. Test equipment:

[0112] 1. Cobb tester with a ring approximately 11.5 cm in diameter. 2. Stopwatch with reverse function and alarm. 3. Small container with 200 ml markings. 4. Methylene blue solution. 5. Absorbent cleaning paper. Material samples:

[0113] Several samples of the release agent were evaluated. If these samples came from a specific location on the paper web, this was noted accordingly for reference purposes. Stain test:

[0114] 1. Cut out a 14 cm x 14 cm sample of the release paper. The release paper must be free of holes or perforations. 2. Do not touch the silicone surface before testing, as this could distort the staining. Place the release paper sample, silicone side up, under the test ring of the Cobb tester. 3. Clamp the ring securely to prevent the dye from leaking out during testing. 4. Pour 200 ml of the dye solution into the Cobb tester and start the timer. The contact time was 120 seconds. 5. After the selected contact time, drain the dye solution, remove the test ring, and lift it off the sample. 6. Blot the test sample with absorbent paper and allow it to dry for five minutes. Once dry, the sample can be examined or measured. Results:

[0115] The subjective assessment of the sample takes into account the overall coloration of the liner and the penetration of the dye solution into the base paper. With good coating quality, no penetration should be visible. The more visible and intense the coloration, the greater the risk that the adhesive will migrate through the silicone coating to the base paper and thus cause release problems (potentially dispensing problems with labels or release problems with adhesive tapes, etc.).

[0116] The coloration was rated on a scale from + to ++++, where ++++ represents complete coloration of the base paper, as with the raw paper, and + represents a perfect color test with no discernible penetration.

[0117] The methods described above can also be found in the "FINAT TECHNICAL HANDBOOK, Test methods" 9th edition, August 2014 (FINAT, World-wide Association for self-adhesive labels and related products, The Hague, Netherlands). Test results:

[0118] Table 6: Results of the separation value determination and storage stability Nr. Silicone application Separation values (tense 7475) Separation values (tense 7476) Writing performance % 60°C / 50% r.F. Recipe Acrylic tape rubber band Technomelt PS8746 Collano L1 945 (g / m²<) cN / in cN / in 1 week. 2 weeks. 4 weeks. Where. Where. 4 weeks. 1. Rez.1a (BPA and PCC) 0,84 blocked -- -- -- nb, blocked -- -- -- 2. Rez.1a (BPA and PCC) 1,34 509 355 -- -- -- -- -- -- 3. Rez.1a (BPA and PCC) 1,05 966 464 -- - -- -- -- -- 4. Rez.1b (BPA and Kaolin) 0,75 35 -- - -- 37,4 -- -- -- 5. Rez.1b (BPA and Kaolin) 1,45 5 46 -- -- - -- -- -- 6. Rez.1b (BPA and Kaolin) 1,10 6 51 -- -- -- -- -- -- 7. Ricoh Topcoat 150 UTB 0,78 9 - -- -- 98,7 -- -- -- 8. Ricoh Topcoat 150 UTB 0,54 11 -- 100,0 101,7 99,4 97,3 99,5 36,6 9. Rez.2a (NKK 1304 and Kaolin) 0,69 16 169 86,3 80,1 75,3 73,2 75,4 10,6 10. Rez.2a (NKK 1304 and Kaolin) 0,82 9 -- -- -- 76,3 -- -- -- 11. Rez.2b (PF201 and Kaolin) 0,68 12 156 69,2 54,8 26,0 54,9 26,1 9,2 12. Rez.3 (PF201 and Kaolin) 0,76 203 -- -- -- 19,1 -- -- -- BPA: Bisphenol A PCC: precipitated CaCO 3 NKK 1304: N-[2-(3-phenylureido)phenyl]benzenesulfonamide PF201: N-(p-toluenesulfonyl)-N'-(3-(p-toluenesulfonyl-oxy-phenyl)-urea

[0119] Recipes 7 and 8 correspond to a self-adhesive, heat-sensitive recording material on a carrier material (topcoat) according to the prior art (manufacturer Ricoh; paper type 150 UTB). Recipes 9 to 12 are embodiments according to the invention. Table 7: Results of the methylene blue test Nr. Recipe Methylene blue staining 1 Rez.1a (BPA and PCC) ++++ 2 Rez.1a (BPA and PCC) +++ 3 Rez.1a (BPA and PCC) ++++ 4 Rez.1b (BPA and Kaolin) ++ 5 Rez.1b (BPA and Kaolin) + 6 Rez.1b (BPA and Kaolin) + 7 Ricoh Topcoat 150 UTB + 8 Ricoh Topcoat 150 UTB + 9 Rez.2a (NKK 1304 and Kaolin) + 10 Rez.2a (NKK 1304 and Kaolin) + 11 Rez.2b (PF201 and Kaolin) + 12 Rez.3 (PF201 and Kaolin) + (++++) = distinct blue coloration, (+++) = blue coloration, (++) = slight blue coloration, (+) = barely visible blue coloration BPA: Bisphenol A PCC: Precipitated CaCO3 NKK 1304: N-[2-(3-Phenylureido)phenyl]benzenesulfonamide PF201: N-(p-Toluenesulfonyl)-N'-(3-(p-toluenesulfonyl-oxyphenyl)-urea

[0120] Tables 6 and 7 show that the heat-sensitive recording material according to the invention exhibits very good separation values ​​with medium silicone application, shows very good writing performance even after 4 weeks of storage at 60 °C and 50% relative humidity and is very easy to siliconize, as shown by the very low blue coloration after the methylene blue test.

Claims

1. A self-adhesive, heat-sensitive recording material, comprising a carrier substrate, a heat-sensitive colour-forming layer applied to one side of the carrier substrate, said layer comprising at least one non-phenolic colour developer and at least one colour former, a siliconised layer on the upper side of the heat-sensitive colour-forming layer applied on the carrier substrate, and an adhesive layer on the side of the carrier substrate facing away from the heat-sensitive colour-forming layer, characterised in that the heat-sensitive colour-forming layer additionally comprises at least one flaky pigment, wherein the particle size of the flaky pigment is configured such that at least 70% of the particles have a particle size of < 2µm, determined by sedigraphy, and that the siliconised layer rests directly on the heat-sensitive colour-forming layer.

2. A self-adhesive, heat-sensitive recording material according to claim 1, characterised in that the at least one flaky pigment comprises a kaolin, and especially preferably a coating kaolin.

3. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the carrier substrate is paper, synthetic paper and / or a plastic film.

4. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the self-adhesive heat-sensitive recording material is a carrier-free self-adhesive heat-sensitive recording material.

5. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the at least one colour developer is sulfonylurea and / or a compound of formula (I), wherein Ar1 and Ar2 are a phenyl group and / or a C1-C4-alkyl-substituted phenyl group.

6. A self-adhesive, heat-sensitive recording material according to claim 5, characterised in that the sulfonylurea is N'-(p-toluenesulfonyl)-N'-phenylurea, N-(p-toluenesulfonyl)-N'-3-(p-toluenesulfonyl-oxy-phenyl)-urea and / or 4,4'-bis-(p-tolylsulfonylureido)-diphenylmethane.

7. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the at least one colour former is a triphenylmethane-type, fluoran-type, azaphthalide-type and / or fluorene-type dye, preferably fluoran-type dye.

8. A self-adhesive heat-sensitive recording material according to at least one of the preceding claims, characterised in that the siliconised layer is applied to at least one polyorganosiloxane, preferably an acrylic polyorganosiloxane.

9. A self-adhesive, heat-sensitive recording material according to claim 8, characterised in that the siliconised layer additionally contains an initiator, preferably a photoinitiator.

10. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the adhesive layer comprises at least one hot-melt adhesive, preferably based on rubber and / or acrylate.

11. A self-adhesive, heat-sensitive recording material according to at least one of claims 2 to 10, characterised in that the at least one flaky pigment is present in an amount of about 5 to about 60 wt.%, preferably of about 15 to about 55 wt.%, in relation to the total solids content of the heat-sensitive layer.

12. A self-adhesive, heat-sensitive recording material according to at least one of the preceding claims, characterised in that the self-adhesive, heat-sensitive recording material is wound up on itself.

13. A method for producing a self-adhesive heat-sensitive recording material according to at least one of the preceding claims, characterised in that an aqueous suspension containing the starting materials of the heat-sensitive, colour-forming layer, comprising at least one non-phenolic colour developer, at least one colour former and at least one flaky pigment, wherein the particle size of the flaky pigment is configured such that at least 70% of the particles have a particle size of < 2µm, determined by sedigraphy, is applied to a carrier substrate and dried, the heat-sensitive colour-forming layer is subsequently siliconised and in that an adhesive layer is applied on the side of the carrier substrate facing away from the heat-sensitive colour-forming layer.

14. A self-adhesive, heat-sensitive recording material, obtainable according to the method according to claim 13.

15. A method for producing a semi-finished product for a self-adhesive, heat-sensitive recording material according to claim 1, characterised in that an aqueous suspension containing the starting materials of the heat-sensitive colour-forming layer, comprising at least one non-phenolic colour developer, at least one colour former and at least one flaky pigment, wherein the particle size of the flaky pigment is configured such that at least 70% of the particles have a particle size of < 2µm, determined by sedigraphy, is applied to a carrier substrate and dried.

16. A semi-finished product for a self-adhesive, heat-sensitive recording material obtainable by the method according to claim 15.

17. A use of the semi-finished product for a self-adhesive, heat-sensitive recording material according to claim 16 for producing a self-adhesive, heat-sensitive recording material according to at least one of the preceding claims 1 to 12 and 14.

18. A use of a self-adhesive, heat-sensitive recording material according to at least one of the preceding claims 1 to 12 and 14 as a label.