Multi-layer construction having good properties for printing

Abstract

The invention relates to a multi-layer construction having particular properties for printing with ink, comprising at least one backing layer A. comprising > 70% by weight of a polymer with respect to the total weight of the backing layer A., having a hardness in a range from 50 Shore D to 90 Shore D, wherein at least one of the at least one backing layer is in the form of an external layer A., and at least one polymer layer B. comprising at least one thermoplastic elastomer in a quantity of > 70% by weight with respect to the total weight of the polymer layer B., and to the production and use thereof.

Description

[0001] Multi-layer structure with good printing properties

[0002] The invention relates to a multi-layer structure with special properties for printing with ink, comprising at least one carrier layer A., ​​comprising > 70 wt.% of a polymer, based on the total weight of the carrier layer A., ​​with a hardness in a range from 50 Shore D to 90 Shore D, wherein at least one of the at least one carrier layer is designed as an outer layer A. and at least one polymer layer B., comprising at least one thermoplastic elastomer in an amount of > 70 wt.%, based on the total weight of the polymer layer B., as well as its production and use.

[0003] Known polymer films, as described in EP2181844A2, EP1404771 or US6040027, can be equipped with a wide variety of properties, depending on your desired application. Since the miniaturization of electronic components and sensors is becoming increasingly common, especially in the medical and diagnostic markets, there is a great demand for polymer films that are suitable for this purpose. The polymer films should be able to be printed with electrical conductors without the films retaining their properties and shape during printing, but also during further processing, which involves high thermal loads in addition to compressive and shear forces. A disadvantage of many polymer films is that they do not retain their shape under the high thermal and compressive loads or cannot be separated after printing because their adhesive strength to their co-extruded other film is too high, as in EP2181844A2.

[0004] One objective was therefore to provide a multilayer structure that at least partially minimizes at least one disadvantage of the prior art. Another objective was to provide a multilayer structure suitable for medical applications. In particular, one objective was to provide a multilayer structure that is low in migrating additives, has a film that is as soft and elastic as possible with high breathability and good printability with electrically conductive inks. Furthermore, one objective was to provide a multilayer structure that exhibits little warpage of the film(s) after printing while still allowing good removability from any carrier layer(s).

[0005] A first aspect of the invention relates to a multilayer structure comprising at least the following layers:

[0006] A. at least one carrier layer A., ​​comprising > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.% of a polymer, based on the total weight of the carrier layer A., ​​with a hardness in a range from 50 Shore D to 90 Shore D, preferably from 55 Shore D to 85 Shore D, particularly preferably from 60 Shore D to 80 Shore D, measured according to DIN ISO 7619-1-2012-02, wherein at least one of the at least one carrier layer is designed as an outer layer A.; B. at least one polymer layer B., comprising at least one thermoplastic elastomer, preferably a thermoplastic polyurethane (TPE-U) in an amount of > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.%, based on the total weight of the polymer layer B.;

[0007] C. optionally at least one hot-melt adhesive layer C., which is preferably arranged between the carrier layer A. and the polymer layer B.,

[0008] D. optionally at least one cover layer D. comprising > 50 wt.%, preferably > 70 wt.%, more preferably > 80 wt.%, particularly preferably > 90 wt.% of a polypropylene, based on the total weight of the cover layer D.,

[0009] E. optionally at least one further polymer layer E., comprising at least one thermoplastic elastomer, preferably a thermoplastic polyurethane (TPE-U) in an amount of > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.%, based on the total weight of the polymer layer E., wherein the co-extruded multi-layer structure has at least one, preferably at least two, more preferably at least three, particularly preferably all of the following properties:

[0010] (El) a layer thickness of the carrier layer A in a range from 30 to 200 pm, preferably from 40 to 150 pm, more preferably from > 50 to 120 pm; particularly preferably from 55 to 110 pm; most preferably from 60 to 100 pm;

[0011] (E2) a layer thickness of the polymer layer B. in a range from 30 to 200 pm, preferably from 40 to 150 pm, more preferably from > 50 to 120 pm; particularly preferably from 55 to 110 pm; most preferably from 60 to 100 pm;

[0012] (E3) a separation force between the carrier layer A. and one of the layers in contact with the carrier layer A., ​​selected from the group consisting of the polymer layer B., the adhesive layer C. or the further polymer layer E., in a range from 0.01 N / cm to 0.1 N / cm; preferably 0.015 N / cm to 0.08 N / cm, more preferably from 0.02 to 0.07 N / cm, particularly preferably from 0.025 to 0.06 N / cm;

[0013] (E4) a content of additives, for example waxes, adhesion promoters, dyes in the carrier layer A. in a range from 0 to 15 wt.%, more preferably from 0 to 12 wt.%, particularly preferably from 0.1 to 10 wt.%, in each case based on the total weight of the carrier layer A.; wherein it is preferred that the multilayer structure has a content of waxes in a range from 0 to 4 wt.%, preferably from 0.1 to 3.5 wt.% or a content of adhesion promoter in a range from 0 to 10 wt.%, preferably from 0.1 to 8 wt.%.

[0014] (E5) a content of additives in the polymer layer B, in particular selected from the group consisting of antiblocking agents, such as Acrawax™ C from Arxada, SUPER FLOSS E from Imerys or calcium stearate from SigmaAldrich, in an amount ranging from 0 to 10 wt.%, preferably 0.5 to 9 wt.%, more preferably 1 to 8 wt.%, particularly preferably 2 to 6 wt.%, based on the total weight of the polymer layer B, and / or matting agents in an amount ranging from 0 to 20 wt.%, preferably 1 to 18 wt.%, particularly preferably 5 to 15 wt.%, based on the total weight of the polymer layer B; particularly preferably, the multilayer structure comprises an antiblocking agent in an amount of 1 to 8 wt.% and a matting agent in an amount of 5 to 15 wt.%, based on the total weight of the polymer layer B.

[0015] (E6) a hardness of the polymer layer B. in a range of 60 Shore A and 55 Shore D, preferably 70 Shore A to 45 Shore D, particularly preferably 80 Shore A to 95 Shore A;

[0016] (E7) a water vapor permeability of at least the polymer layer B. of > 80 g / m 2 d, preferably > 100 g / m 2 d, particularly preferably > 150 g / m 2 d,

[0017] (E8) a resistance of a 200 pm wide conductor track strand produced according to process 1) of < 10 Q, more preferably < 5 Q, particularly preferably < 2 Q.

[0018] The release force / adhesion between carrier layer A and polymer layer B was measured according to ASTM F88a on a strip width of 200 mm.

[0019] In particular, a multilayer structure having properties (E1) and (E2) is preferred. Further preferred is a combination of properties (E1) and (E2) with one of properties (E3) to (E8), in particular the combination (E1), (E2), and (E3) or the combination (E1), (E2), (E3), and (E8).

[0020] Preferably, the adhesion between the carrier layer A. and the adjacent layer, selected from the group consisting of the polymer layer B., the adhesive layer C., or the further polymer layer E., is dimensionally stable after a heat / press / print process, yet the carrier layer A. can be removed non-destructively. This property is particularly important if the multilayer structure is to be printed with a conductive ink without the polymer layer B. warping, tearing, or otherwise changing its shape. Therefore, the carrier layer A. is only peeled off the polymer layer B. after the printing process.

[0021] The at least one carrier layer A. contains the polymer in a range from 70 to 100 wt. %, preferably in a range from 80 to 98 wt. %, particularly preferably in a range from 90 to 95 wt. %, based on the total weight of the respective carrier layer A. The polymer of the at least one carrier layer A. is preferably a thermoplastic material, in particular selected from the group consisting of a polyethylene (PE), a polypropylene (PP), a polyamide (PA), a polycarbonate (PC), a polyethylene terephthalate (PET) or a mixture of at least two thereof. The carrier layer A. particularly preferably contains polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET) or a mixture of at least two thereof in an amount of 70 to 100 wt. %, preferably in a range from 80 to 98 wt. %, particularly preferably in a range from 90 to 95 wt. %, based on the total weight of the respective carrier layer A.The polymer of the at least one carrier layer A is preferably selected from the group consisting of a polyethylene (PE), a polypropylene (PP), a polycarbonate (PC), a polyethylene terephthalate (PET), or a mixture of at least two thereof. Particularly preferably, the carrier layer A comprises polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), or a mixture of at least two thereof in an amount of 70 to 100 wt. %, preferably in a range of 80 to 98 wt. %, particularly preferably in a range of 90 to 95 wt. %, based on the total weight of the respective carrier layer.

[0022] A.

[0023] Preferably, the carrier layer A comprises a polypropylene in an amount of 70 to 100 wt.%, more preferably 80 to 95 wt.%, based on the total amount of the carrier layer A.

[0024] Carrier layer A preferably comprises at least two, more preferably at least three, layers of the respective polymer. Preferably, the layer that comes into contact with another layer of the multilayer structure during the extrusion process, such as polymer layer B or adhesive layer C, comprises the aforementioned additives. Preferably, the layers that do not come into contact with other layers of the multilayer structure do not comprise any additives.

[0025] The carrier layer A preferably has two layers containing 100 wt.% polypropylene and one layer containing 100 wt.% polyethylene, wherein the layer containing the polyethylene comes into direct contact with the polymer layer B. The layer containing polyethylene preferably has a thickness in a range from 2 to 50 pm, more preferably from 5 to 30 pm, particularly preferably from 10 to 20 pm.

[0026] The at least one polymer layer B comprises a thermoplastic elastomer, preferably a thermoplastic polyurethane. The polymer layer B comprises the thermoplastic elastomer in an amount of > 70 wt.%, preferably > 75 wt.%, more preferably > 80 wt.%, particularly preferably > 85 wt.%, very particularly preferably > 90 wt.%, most preferably in a range from 70 to 95 wt.%, based on the total weight of the polymer layer.

[0027] B.

[0028] Thermoplastic elastomers are materials that contain elastomeric phases either physically blended or chemically bonded into thermoplastically processable polymers. A distinction is made between polyblends, in which the elastomeric phases are physically blended, and block copolymers, in which the elastomeric phases are part of the polymer framework. Due to the structure of thermoplastic elastomers, hard and soft regions exist side by side. The hard regions form a crystalline network structure or a continuous phase whose interstices are filled with elastomeric segments. Due to this structure, these materials have rubber-like properties.The thermoplastic elastomer is preferably selected from the group consisting of a thermoplastic copolyamide (TPE-A), in particular a polyether block amide, a thermoplastic polyurethane (TPE-U), a thermoplastic polyester elastomer (TPE-E), a styrene block copolymer (TPE-S), TPE-V - vulcanized (crosslinked) PP / EPDM compounds or a mixture of at least two thereof.

[0029] The thermoplastic copolyamide (TPE-A) can be any copolyamide that a person skilled in the art would select for a layer structure, in particular polyether block amides (PEBA). Preferred polyether block amides are, for example, those consisting of polymer chains composed of repeating units according to formula (0). in which

[0030] A is the polyamide chain derived from a polyamide with 2 carboxyl end groups by loss of the latter and

[0031] B is the polyoxyalkylene glycol chain derived from a polyoxyalkylene glycol with terminal OH groups by loss of the latter, and n is the number of units forming the polymer chain. The terminal groups are preferably OH groups or residues of compounds that terminate the polymerization.

[0032] The dicarboxylic acid polyamides with terminal carboxyl groups are obtained in known ways, for example, by polycondensation of one or more lactams and / or one or more amino acids, or by polycondensation of a dicarboxylic acid with a diamine, in each case in the presence of an excess of an organic dicarboxylic acid, preferably with terminal carboxyl groups. These carboxylic acids become part of the polyamide chain during the polycondensation and, in particular, attach to its end, thereby obtaining a p-dicarboxylic acid polyamide. Furthermore, the dicarboxylic acid acts as a chain terminator, which is why it is also used in excess.

[0033] The polyamide can be obtained starting from lactams and / or amino acids with a hydrocarbon chain consisting of 4-14 C atoms, such as caprolactam, oenantholactam, dodecalactam, undecanolactam, decanolactam, 11-aminoundecanoic acid, or 12-aminododecanoic acid. Examples of polyamides obtained by polycondensation of a dicarboxylic acid with a diamine include the condensation products of hexamethylenediamine with adipic, azelaic, sebacic, and 1,12-dodecanedioic acid, as well as the condensation products of nonamethylenediamine and adipic acid.

[0034] The dicarboxylic acids used for the synthesis of the polyamide, i.e. on the one hand for fixing a carboxyl group at each end of the polyamide chain and on the other hand as chain terminating agents, are those with 4-20 C atoms, in particular alkanedioic acids, such as succinic, adipic, suberic, azelaic, sebacic, undecanedioic or dodecanedioic acid, and also cycloaliphatic or aromatic dicarboxylic acids, such as terephthalic or isphthalic or cyclohexane-1,4-dicarboxylic acid.

[0035] Polyoxyalkylene glycols containing terminal OH groups are unbranched or branched and contain an alkylene radical with at least two carbon atoms. These include, in particular, polyoxyethylene, polyoxypropylene, and polyoxytetramethylene glycol, as well as copolymers thereof.

[0036] The average molecular weight of these OH group-terminated polyoxyalkylene glycols can vary within a wide range, advantageously between 100 and 6000 g / mol, in particular between 200 and 3000 g / mol.

[0037] The weight fraction of the polyoxyalkylene glycol, based on the total weight of the polyoxyalkylene glycol and dicarboxylic acid polyamide used to produce the PEBA polymer, is preferably 5-85 wt%, preferably 10-50 wt%.

[0038] Processes for the synthesis of such PEBA polymers are known from FR-PS 7 418 913, DE-OS 28 02 989, DE-OS 28 37 687, DE-OS 25 23 991, EP-A 095 893, DE-OS 27 12 987 and DEOS 27 16 004.

[0039] Suitable and preferably suitable PEBA polymers are available, for example, under the trade names PEBAX from Atochem, Pebax® 5010, Pebax® 5020, Pebax® 5030, Pebax® 5040, Pebax® 5070 from Arkema (Germany), Vestamid from Hüls AG, Grilamid from EMS-Chemie and Kellaflex from DSM.

[0040] Preferred polyether block amides may also contain additives commonly used in plastics. Typical additives include pigments, stabilizers, flow agents, lubricants, and mold release agents.

[0041] Examples of thermoplastic copolyamides include products such as Pebax® 5010, Pebax® 5020, Pebax® 5030, Pebax® 5040, and Pebax® 5070 from Arkema (Germany). Examples of thermoplastic polyurethanes will be mentioned later. The thermoplastic polyester elastomer (TPE-E) can be any polyester elastomer that a person skilled in the art would select for a layer structure; polyester elastomers are preferably copolyesters. Suitable copolyesters (segmented polyester elastomers) are composed, for example, of a large number of repeating, short-chain ester units and long-chain ester units linked by ester bonds, with the short-chain ester units accounting for approximately 15-65 wt.% of the copolyester and having the formula (1): in which

[0042] R represents a divalent radical of a dicarboxylic acid having a molecular weight of less than about 350 g / mol,

[0043] D represents a divalent radical of an organic diol having a molecular weight of less than about 250 g / mol; the long-chain ester units constitute about 35-85 wt.% of the copolyester and have the formula (11) in which

[0044] R represents a divalent radical of a dicarboxylic acid having a molecular weight of less than about 350 g / mol,

[0045] G represents a divalent residue of a long-chain glycol having an average molecular weight of approximately 350 to 6000 g / mol. Examples of thermoplastic polyester elastomers (TPEEs) are DuPont™ Hytrel® 5556 or DuPont™ Hytrel® PC966 NC010 (DuPont, Wilmington, DE 19880-0709).

[0046] The copolyesters which are preferably used can be prepared by polymerising a) one or more dicarboxylic acids, b) one or more linear, long-chain glycols and c) one or more low-molecular-weight diols.

[0047] The dicarboxylic acids for the preparation of the copolyester are preferably aromatic acids with 8-16 C atoms, especially phenylenedicarboxylic acids, such as phthalic, terephthalic, and isophthalic acid. The low molecular weight diols for the reaction to form the short-chain ester units of the copolyesters preferably belong to the classes of acyclic, alicyclic, and aromatic dihydroxy compounds. The preferred diols have 2-15 C atoms, such as ethylene, propylene, tetramethylene, isobutylene, pentamethylene, 2,2-dimethyltrimethylene, hexamethylene, and decamethylene glycols, dihydroxycyclohexane, cyclohexanedimethanol, resorcinol, hydroquinone, and the like. Bisphenols for the present purpose include bis-(p-hydroxy)-diphenyl, bis-(p-hydroxyphenyl)-methane, bis-(p-hydroxyphenyl)-ethane, and bis-(p-hydroxy _, phenyl)-propane.

[0048] The long-chain glycols used to produce the soft segments of the copolyesters preferably have molecular weights of approximately 600 to 3000 g / mol. These include poly(alkylene ether) glycols, in which the alkylene groups have 2-9 carbon atoms.

[0049] Glycol esters of poly(alkylene oxide) dicarboxylic acids or polyester glycols can also be used as long-chain glycols.

[0050] Long-chain glycols also include polyformals, which are obtained by reacting formaldehyde with glycols. Polythioether glycols are also suitable. Polybutadiene and polyisoprene glycols, copolymers thereof, and saturated hydrogenation products of these materials represent satisfactory long-chain polymeric glycols.

[0051] Processes for the synthesis of such copolyesters are known from DE-OS 2 239 271, DE-OS 2 213 128, DEOS 2 449 343 and US-A 3 023 192.

[0052] The copolyesters can also contain the additives commonly used in plastics. Typical additives include lubricants such as fatty acid esters, their metal soaps, fatty acid amides, and silicone compounds; antiblocking agents; inhibitors; stabilizers against hydrolysis, light, heat, and discoloration; flame retardants; dyes, pigments; inorganic or organic fillers; and reinforcing agents. Reinforcing agents are particularly fibrous reinforcing materials such as inorganic fibers, which are manufactured using state-of-the-art technology and can also be coated with a size. Further information on the auxiliaries and additives mentioned can be found in the specialist literature, for example JH Saunders, KC Frisch: “High Polymers”, Volume XVI, Polyurethanes, Parts 1 and 2, Interscience Publishers 1962 and 1964 respectively, R.Gächter, H.Müller (Ed.): Taschenbuch der Kunststoff-Additive, 3rd Edition, Hanser Verlag, Munich 1989, or DE-A 29 01 774.

[0053] The thermoplastic styrene block copolymer (TPE-S) can be any styrene block copolymer that a person skilled in the art would select for a layered structure. The preferred styrene-butylene block copolymers consist of a polyethylene-butylene rubber middle block with a polystyrene end block chemically coupled at both ends. The polystyrene content is less than 30%. The polystyrene end blocks are evenly distributed as spherical polystyrene domains in the ethylene rubber matrix.

[0054] Processes for the synthesis of suitable styrene block copolymers are known, for example, from US Pat. Nos. 3,485,787, 4,006,116 and 4,039,629.

[0055] The styrene block copolymers can also contain additives commonly found in plastics. Common additives include pigments, stabilizers, flow agents, lubricants, and mold release agents.

[0056] Examples of styrene block copolymers (TPEs) are Elastron G, such as Elaston Gl 00 and Gl 01, Elastron D, such as Elaston Dl 00 and Dl 01 from Elastron (Turkey), and Kraton™ D S1BS from Kraton Polymers (USA), Septon™, in particular Septon™ Q1250 or Septon™ V9461 from Kuraray (Japan), Styroflex® 2G66 from Ineos Styrolution Group GmbH (Germany), Thermolast® K from Kraiburg TPE (Germany), and Saxomer® TPE-S from PCW GmbH (Germany). Other suitable styrene-butylene block copolymers are available, for example, under the trade names 'Kraton G' and 'Elexar' from Shell Chemie GmbH.

[0057] The thermoplastic, vulcanized (cross-linked) PP / EPDM compound can be any PP / EPDM compound that a person skilled in the art would select for a layered structure. Examples of PP / EPDM compounds include Santoprene (from Exxon Mobil) or Sariink (from DSM).

[0058] The preferably hydrophilic TPE-Us are formed from alternating blocks of soft and hard segments, with the soft segments being formed from difunctional polyols composed of polymerized ethers and / or esters, and the hard segments being formed from the reaction products of low-molecular-weight diols, i.e., the chain extender and diisocyanates. These blocks are advantageously linked together in such a way that the hard segment forms the two ends of the molecular chain, and the reactive isocyanate groups located at the ends of the linear molecule can optionally be capped with alcohols.

[0059] The multilayer structure preferably comprises one or more layers of TPE-U as polymer layer(s) B, the soft segment phase of which is predominantly formed either from polyether soft segment building blocks or from polyester soft segment building blocks. Preferably, the at least one polymer layer B comprises the TPE-U in an amount ranging from >70 wt.% to 100 wt.%, more preferably in a range from >80 wt.% to 98 wt.%, particularly preferably >90 wt.% to 95 wt.%, based on the total weight of the polymer layer B.

[0060] Depending on the organic diisocyanates used, TPE-Us can be aliphatic or aromatic in nature. Aromatic diisocyanates are preferred. TPE-Us typically have a block or segmented structure. A basic distinction is made between hard segments and soft segments. Hard segments are formed from the organic diisocyanates used in the reaction and short-chain compounds with two to three hydroxyl, amino, thiol, or carboxyl groups, preferably compounds with two hydroxyl, amino, thiol, or carboxyl groups, particularly preferably diols, with an average molecular weight of 60 to 500 g / mol.Soft segments are formed from the organic diisocyanates used for the reaction and long-chain compounds with two to three hydroxyl, amino, thiol or carboxyl groups, preferably compounds with two hydroxyl, amino, thiol or carboxyl groups, particularly preferably diols, with an average molecular weight of > 500 and < 5000 g / mol.

[0061] Hard segments contribute the strength and the upper service temperatures to the TPE-U property profiles, while soft segments contribute the elastic properties and the cold flexibility to the material properties of the TPE-U.

[0062] Aromatic, aliphatic, araliphatic, heterocyclic and cycloaliphatic diisocyanates or mixtures of these diisocyanates can be used as organic diisocyanates for both the hard segments and the soft segments (cf. HOUBEN-WEYL ''Methods of Organic Chemistry”, Volume E20 ''Macromolecular Substances”, Georg Thieme Verlag, Stuttgart, New York 1987, pp. 1587-1593 or Justus Liebigs Annalen der Chemie, 562, pages 75 to 136).

[0063] The following may be mentioned as examples: aliphatic diisocyanates such as hexamethylene diisocyanate, cycloaliphatic diisocyanates such as isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1-methyl-2,4-cyclohexane diisocyanate and 1-methyl-2,6-cyclohexane diisocyanate and the corresponding isomer mixtures, 4,4'-dicyclohexylmethane diisocyanate, 2,4'-dicyclohexylmethane diisocyanate and 2,2'-dicyclohexylmethane diisocyanate and the corresponding isomer mixtures, aromatic diisocyanates such as 2,4-tolylene diisocyanate, mixtures of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate, mixtures of 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate, urethane-modified liquid 4,4'-diphenylmethane diisocyanates and 2,4'-diphenylmethane diisocyanates, 4,4'-diisocyanatodiphenylethane-(1,2) and 1,5-naphthylene diisocyanate.Preference is given to using 1,6-hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane 4,4'-diisocyanate, diphenylmethane diisocyanate isomer mixtures with a 4,4'-diphenylmethane diisocyanate content of > 96 wt.%, and in particular 4,4'-diphenylmethane diisocyanate and 1,5-naphthylene diisocyanate. The diisocyanates mentioned can be used individually or in the form of mixtures with one another. They can also be used together with up to 15 wt.% (calculated based on the total amount of diisocyanate) of a polyisocyanate, for example triphenylmethane 4,4',4"-triisocyanate or polyphenyl polymethylene polyisocyanates. Particularly preferred organic diisocyanates are, for example, 4,4'-diphenylmethane diisocyanate, hydrogenated 4,4'-diphenylmethane diisocyanate, 2,4-toluene diisocyanate, or a mixture of at least two thereof.

[0064] The preferred short-chain diols with a molecular weight of 60 to 500 g / mol are preferably aliphatic diols with 2 to 14 carbon atoms, for example ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol and dipropylene glycol. However, diesters of terephthalic acid with glycols with 2 to 4 carbon atoms are also suitable, e.g. terephthalic acid bis-ethylene glycol or terephthalic acid bis-1,4-butanediol, hydroxyalkylene ethers of hydroquinone, e.g. 1,4-di(ß-hydroxyethyl)-hydroquinone, ethoxylated bisphenols, e.g.l,4-Di(ß-hydroxyethyl)-bisphenol A, (cyclo)aliphatic diamines such as isophoronediamine, ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, N-methyl-propylene-1,3-diamine, N,N'-dimethylethylenediamine and aromatic diamines such as 2,4-tolylenediamine, 2,6-tolylenediamine, 3,5-diethyl-2,4-tolylenediamine or 3,5-diethyl-2,6-tolylenediamine or primary mono-, di-, tri- or tetraalkyl-substituted 4,4'-diaminodiphenylmethanes. Particular preference is given to using ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, 1,4-di(ß-hydroxyethyl)hydroquinone, or 1,4-di(ß-hydroxyethyl)bisphenol A. Mixtures of the above-mentioned compounds can also be used. Smaller amounts of triols can also be added.

[0065] The long-chain compounds with two to three hydroxyl, amino, thiol, or carboxyl groups, preferably compounds with two hydroxyl, amino, thiol, or carboxyl groups, particularly preferably diols, with a number-average molecular weight of > 500 and < 5000 g / mol, can be divided into two main groups: polyetherdiols and polyesterdiols. Polyetherdiols are based, for example, on polytetrahydrofuran, polyethylene oxide, polypropylene oxide, and mixtures thereof. Polyesterdiols are typically based on adipates, such as 1,4-butanediol adipate and 1,6-hexanediol adipate, and caprolactone. Cocondensates are also possible.

[0066] The thermoplastic polyurethane of polymer layer B preferably comprises a polyetherdiol. If only polyetherdiol is used as the polyol component in the production of the TPE-U for polymer layer B, it is preferred that a cover layer D be arranged on the side of polymer layer B opposite the first carrier layer A.

[0067] In the production of TPE-U, known and conventional catalysts can be used according to the state of the art. These can be tertiary amines such as triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo[2,2,2]octane and the like, as well as in particular organic metal compounds such as titanic acid esters, iron compounds or tin compounds such as tin diacetate, tin dioctoate, tin dilaurate or the tin dialkyl salts of aliphatic carboxylic acids such as dibutyltin diacetate or dibutyltin dilaurate or the like. Preferred catalysts are organic metal compounds, in particular titanic acid esters, iron and tin compounds. The total amount of catalysts in the TPE-U can generally be about 0 to 5 wt. %, preferably 0 to 2 wt. %, based on the total amount of TPE-U.

[0068] Furthermore, the TPE-U can contain auxiliaries and additives up to a maximum of 30 wt.%, preferably up to a maximum of 20 wt.%, based on the total amount of TPE-U.

[0069] Typical auxiliaries and additives are pigments, dyes, flame retardants, stabilizers against aging and weathering influences, plasticizers, lubricants and mold release agents, fungistatic and bacteriostatic substances as well as fillers and their mixtures.

[0070] Examples of lubricants are fatty acid esters, their metal soaps, fatty acid amides, fatty acid ester amides, and silicone compounds. Antiblocking agents, inhibitors, stabilizers against hydrolysis, light, heat, and discoloration, flame retardants, dyes, pigments, inorganic and / or organic fillers, for example polycarbonates, as well as plasticizers and reinforcing agents are also preferably used as additives in the TPE-U. Reinforcing agents are, in particular, fibrous reinforcing materials, such as inorganic fibers, which are manufactured using state-of-the-art technology and may also be coated with a size. Further information on the aforementioned auxiliaries and additives can be found in the specialist literature, for example the monograph by J.H. Saunders and K.C. Frisch, "High Polymers," Volume XVI, Polyurethanes, Parts 1 and 2, Interscience Publishers, 1962 and 1964, and the handbook for plastics additives by R. Gächter and H.Müller (Hanser Verlag Munich 1990) or DE-A 29 01 774.

[0071] The TPE-U preferably comprises the individual additives in a range of 1 to 25 wt.%, more preferably in a range of 2 to 20 wt.%, particularly preferably in a range of 3 to 15 wt.%, based on the total amount of TPE-U.

[0072] Suitable TPE-Us are available on the market under the trade names Desmopan™, Elastollan™, Pellethane™, Estane™, Morthane™ or Texin™.

[0073] The multilayer structure preferably has at least two polymer layers B., a first polymer layer B. and a further polymer layer B. The first polymer layer B. of the multilayer structure according to the invention preferably contains at least one TPE-U, preferably a TPE-U with a predominantly linear molecular structure, whose longer-chain diol component is preferably a difunctional polyether or polyester and particularly preferably a difunctional hydrophilic polyether or polyester, and which has a Shore hardness of preferably 70 - 95 A, particularly preferably 80 - 90 A, determined according to DIN 53 505. Preferably, several polymer layers B., comprising TPE-U with different water vapor permeability, are used. This can be achieved by different soft segments and / or modified hard segments of the TPE-U in the individual polymer layers B.For the soft segments, the water absorption capacity increases in the order: polyester < polytetrahydrofuran < polyethylene oxide.

[0074] Ether-carbonate soft-segment building blocks are also suitable. These are characterized by good resistance to hydrolysis. Furthermore, such materials exhibit good resistance to fungal and microbial attack. Ether-soft-segment building blocks based on polytetramethylene glycol are particularly preferred.

[0075] For the hard segments, modifications are possible, for example, as realized in the dual hydrophilized lmpraperm® types marketed by Covestro AG, and as described, for example, in EP-A 0 525 567 and DE-A 42 36 569.

[0076] To produce the at least one further polymer layer B., in addition to the previously described TPE-Us, methyl methacrylate acrylonitrile butadiene styrene polymers (MABS) are used, preferably thermoplastic methyl methacrylate acrylonitrile butadiene styrene polymers.

[0077] The MABS preparations used preferably consist of copolymers containing methyl methacrylate (MMA), acrylonitrile, butadiene, and styrene. These can be arranged in alternating blocks and segments or randomly. Grafted copolymers with MMA blocks grafted onto units of terpolymers of acrylonitrile, butadiene, and styrene, or elastic copolymers of butadiene and styrene, are particularly preferred.

[0078] The TPE-U and MABS components are homogeneously miscible in the molten state, but upon cooling or solidification, they form multiple phases due to decreasing miscibility. Thus, after the melt solidifies, the MABS units exist in rigid domains. These thermally initiated property changes can be repeated multiple times, thus allowing for multiple process steps with these materials.

[0079] The MABS copolymers used in the TPE-U matrix have a gloss-reducing effect when forming thin-walled films, especially in blown film extraction.

[0080] The use of mixtures of different TPE-Us based on different ethers or esters is preferred, particularly preferably a mixture of different ether-based or ester-based TPE-Us, of which at least one TPE-U has a soft segment molecular weight distribution that allows the formation of crystalline superstructures. The use of mixtures of different TPE-Us based on different ethers is particularly preferred.

[0081] Blends of thermoplastic polyurethanes and thermoplastic MABS copolymers are preferred for the production of the additional polymer layer B. If necessary, the phase separation of the blend can be further stabilized by adhesion and phase-promoting substances, particularly modified PE copolymers.

[0082] In a preferred embodiment of the multilayer structure, the proportion of MABS copolymers in the further polymer layer B is between 5 and 40 wt.%, preferably between 10 and 30 wt.%, based on the total weight of the polymer layer B.

[0083] Common thermal forming processes for processing plastics into multilayer sheet structures are particularly suitable for producing the multilayer structure according to the invention. Examples include coextrusion, such as the blown film process or the flat film process.

[0084] The multilayer structure is preferably produced using the blown film process. Coextrusion also allows for improved bonding between the first polymer layer B, containing pure TPE-U, and the second polymer layer B, consisting of blends of thermoplastic polyurethanes and thermoplastic MABS.

[0085] The multi-layer structure can additionally be modified in its surface properties on one or both sides using known physical and chemical treatment methods, such as corona treatment.

[0086] The at least one optional hot-melt adhesive layer C., also simply called adhesive layer C., preferably comprises a thermoplastic polymer. The thermoplastic polymer is preferably selected from the group consisting of a thermoplastic polyurethane (TPE-U), a polyamide, a co-polyamide, a polyester, or a co-polyester. The polymer of the hot-melt adhesive layer C. preferably has a softening temperature in a range from 80 to 170°C, more preferably from 80 to 160°C, particularly preferably from 100 to 150°C, determined according to the instructions under measurement methods. The hot-melt adhesive layer C. preferably has a thickness in a range from 5 to 150 μm, more preferably from 10 to 100 μm, particularly preferably from 20 to 80 μm. The polymer of the adhesive layer C. preferably has a lower softening temperature than the polymer of the polymer layer B. The softening temperature of the polymer of the adhesive layer C is preferablyat least 20°C, further preferably in a range from 20°C to 80°C, more preferably from 30 to 60°C lower than that of the polymer of the polymer layer B.. The release force of the adhesive layer C. from the carrier layer A. is preferably in a range from 0.01 N / cm to 0.1 N / cm, preferably 0.015 N / cm to 0.08 N / cm, more preferably from 0.02 to 0.07 N / cm, particularly preferably from 0.025 to 0.06 N / cm. The adhesive layer C. preferably has a high release force from textiles such as cotton fabrics, wool fabrics, polymer fabrics, for example fabrics containing polyester, polyurethane, polyacrylate, polyamide, polyterephthalate. The adhesive layer C. preferably has a release force in a range from 0.1 N / cm to 10 N / cm, preferably 0.2 N / cm to 8 N / cm, more preferably from 0.5 to 6 N / cm, particularly preferably from 0.8 to 5 N / cm to cotton fabrics, wool fabrics or polymer fabrics.

[0087] The at least one optional cover layer D. preferably comprises a polymer with a hardness in a range from 50 Shore D to 90 Shore D, preferably from 55 Shore D to 85 Shore D, particularly preferably from 60 Shore D to 80 Shore D, measured according to DIN ISO 7619-1-2012-02. The polymer of the at least one optional cover layer D. is preferably a thermoplastic material, in particular selected from the group consisting of a polyethylene (PE), a polypropylene (PP), a polycarbonate (PC), a polyethylene terephthalate (PET) or a mixture of at least two thereof. The at least one optional cover layer D. contains the polymer in a range from 70 to 100 wt.%, preferably in a range from 80 to 95 wt.%, particularly preferably in a range from 85 to 90 wt.%, based on the total weight of the respective cover layer D. The cover layer D.preferably has a thickness in a range from 5 to 200 pm, preferably from 10 to 150 pm, more preferably from 15 to 120 pm; particularly preferably from 20 to 110 pm.

[0088] If the cover layer D. is present and is in contact with the polymer layer B., the separation force between the cover layer D. and the polymer layer B. is preferably in a range of 0.02 to 0.1 N / cm, more preferably 0.03 to 0.08 N / cm.

[0089] The at least one optional further polymer layer E. comprises at least one thermoplastic elastomer, preferably a thermoplastic polyurethane (TPE-U) in an amount of > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.% based on the total weight of the polymer layer E.. The thermoplastic elastomer of the polymer layer E. is preferably selected from the group of thermoplastic elastomers as described for the polymer layer B. The thermoplastic elastomer of the further polymer layer E. can contain the same polymer as the polymer layer B. or a different one.

[0090] The polymer of polymer layer E. is preferably a TPE-U, as described for polymer layer B. More preferably, polymer layer E. comprises the same polymer as polymer layer B., wherein the amount and composition of the additives preferably differs from polymer layer B. Polymer layer E. preferably has fewer additives than polymer layer B.. Polymer layer E. preferably has a maximum of half as many additives as polymer layer B.. Polymer layer E. preferably has a thickness in a range from 30 to 200 pm, further preferably from 40 to 150 pm, more preferably from > 50 to 120 pm; particularly preferably from 55 to 100 pm; most preferably from 60 to 90 pm.

[0091] Preferably, the multilayer structure has the layer sequence selected from the group consisting of A.-B., A.-B.-D., A.-C.-B.-D., A.-E.-B.-D., A.-C.-E.-B.-D.

[0092] In a preferred embodiment of the multilayer structure, the multilayer structure has at least one applied, preferably printed, conductor track. With a conductor track width of 200 μm, a design as shown in Figure 2, and determined according to method 1), the conductor track preferably has an electrical resistance of < 10 , more preferably < 5 , and particularly preferably < 2 .

[0093] Preferably, the at least one conductor track has a thickness in a range of 1 to 20 pm.

[0094] Preferably, the at least one conductor track is produced by means of a printing process selected from the group consisting of a screen printing process, a rotary printing process, an inkjet printing process, a mass printing process such as gravure, offset or flexographic printing, or a combination of at least two thereof.

[0095] In a preferred embodiment of the multi-layer structure, the at least one conductor track has at least one, preferably at least two, particularly preferably all of the following properties:

[0096] LI. a width of > 10 pm, preferably in a range of 10 to 1000 pm;

[0097] L2. a thickness in a range of >1 pm, preferably in a range of 1 pm to 20 pm;

[0098] L3. an electrical resistance < 10 Ω, more preferably < 5 Ω, particularly preferably < 2 Ω, with a conductor track width of 200 pm, wherein the conductor track has a design as shown in Figure 2 and was produced according to method 1).

[0099] In a preferred embodiment of the multi-layer structure, the at least one carrier layer A. comprises a polypropylene or a PET or a mixture thereof, preferably a polypropylene.

[0100] In a preferred embodiment of the multi-layer structure, the adhesive layer C contains a polymer selected from the group consisting of polyamide, co-polyamide, polyester, co-polyester, TPE-U or a mixture of at least two thereof.

[0101] In a preferred embodiment of the multi-layer structure, the elastomer of the polymer layer B comprises a thermoplastic polyurethane (TPE-U) which is composed of a polyol component and a polyisocyanate component, wherein the polyol component of the TPE-U is preferably selected from the group consisting of polytetrahydrofuran groups, polyethylene glycol ether groups, polyethylene glycol ester groups or a combination of at least two thereof.

[0102] Preferably, the TPE-U of the polymer layer B comprises exclusively polytetrahydrofuran groups and / or polyethylene glycol ether groups or exclusively polyethylene glycol ester groups.

[0103] In a preferred embodiment of the multi-layer structure, the thermoplastic polyurethane used in the polymer layer B comprises polyethylene glycol ether groups or polyethylene glycol ester groups or a combination of these two in an amount in a range of 20 to 80 wt.%, preferably in a range of 30 to 70 wt.%, particularly preferably in a range of 40 to 60 wt.%, based on the total weight of the polymer layer B.

[0104] In a preferred embodiment of the multi-layer structure, at least one of the at least one carrier layer A., ​​in particular the carrier layer A., ​​has at least one, preferably at least two, particularly preferably all of the following properties:

[0105] (Al) A thickness in a range of 40 to 150 pm;

[0106] (A2) A density in a range of 0.8 to 1.0 g / cm 3 ;

[0107] (A3) A hardness in a range of 55 Shore D to 85 Shore D;

[0108] In a preferred embodiment of the multilayer structure, the polymer layer B. has at least one of the following properties:

[0109] (Bl) A thickness in a range of 40 to 150 pm;

[0110] (B2) A density in a range of 1.0 to 1.5 g / cm 3 , preferably 1.05 to 1.4 g / cm 3 , particularly preferably from 1.09 to 1.3 g / cm 3 according to DIN EN ISO 1183-1-A;

[0111] (B3) A tear strength in a range of 50 to 130 kN / m, preferably 60 to 120 kN / m, measured according to DIN ISO 34-1, B;

[0112] (B4) An elongation at break in a range of 300 to 800%, preferably in a range of 350 to 750%, particularly preferably 400 to 700%, measured according to DIN EN ISO 527-2016-09;

[0113] (B5) A fracture stress in a range of 50 to 80 MPa, preferably 55 to 75 MPa, measured according to DIN EN ISO 527-2016-09;

[0114] (B6) A stress at 50% strain in a range of 4 to 11 MP according to DIN EN ISO 527-2016-09

[0115] (B7) A Shore hardness in a range of 70 - 100 A, preferably 80 - 95 A;

[0116] In a preferred embodiment of the multilayer structure, the multilayer structure is constructed in at least 3 layers, preferably with a carrier layer A., ​​a polymer layer B., optionally at least one adhesive layer C. between the carrier layer A. and the polymer layer B.. The layer A., ​​B. or C. can contain several layers of the aforementioned polymers.

[0117] In a preferred embodiment of the multi-layer structure, the multi-layer structure has at least 4 layers, preferably with a carrier layer A., ​​a polymer layer B., at least one adhesive layer C. and / or a cover layer D., wherein the adhesive layer C., if present, is arranged between the carrier layer A. and the polymer layer B. and the cover layer D., if present, is arranged on the outside of the polymer layer B. The layers A., B. or C. can contain several layers of the aforementioned polymers.

[0118] In a preferred embodiment of the multilayer structure, the multilayer structure is produced by a blown film process.

[0119] Another object of the invention relates to a method for producing a multi-layer structure, comprising at least the steps:

[0120] (51) Providing a first polymer A) comprising a polypropylene in an amount in a range of 70 wt% to 100 wt%;

[0121] (52) providing a further polymer B) comprising at least one thermoplastic polyurethane in an amount in a range of 70 wt% to 98 wt%;

[0122] (53) Optionally providing a further polymer C) comprising at least one thermoplastic polymer different from polymer B) in an amount in a range of 80 wt% to 100 wt%;

[0123] (54) Optionally providing a further polymer D) comprising at least one polypropylene in an amount in a range of 50 wt% to 100 wt%, preferably 70 to 90 wt%;

[0124] (55) Optionally providing a further polymer E) comprising at least one thermoplastic polymer, preferably a polyether block amide or a TPE-U, or both in an amount in a range of 80 wt% to 100 wt%;

[0125] (56) melting the two polymers A) and B) and optionally C) and / or D) and / or E) in separate extruders;

[0126] (57) feeding the melts of the polymers A) and B) and optionally C) and / or D) and / or E) into an annular die of a blown film line; (S8) coextruding the melts of the polymers A) and B) and optionally C) and / or D) and / or E) in the blown film line to form the multilayer structure, comprising at least one carrier layer A. formed from the polymer A) and a polymer layer B. formed from the polymer B) and optionally an adhesive layer C. formed from the polymer C), optionally a cover layer D. formed from the polymer D) and optionally a further polymer layer E. formed from the further polymer E), and subsequently cooling the multilayer structure, wherein the multilayer structure has a separating force between the carrier layer A. and a layer in contact with the carrier layer A., ​​selected from the group consisting of the polymer layer B., the adhesive layer C. or the further polymer layer E., in a range from 0.01 N / cm to 0.1 N / cm; preferably 0.015 N / cm to 0.08 N / cm, more preferably from 0.02 to 0.07 N / cm, particularly preferably from 0.025 to 0.06 N / cm.

[0127] The release force / adhesion between carrier layer A and polymer layer B was measured according to ASTM F88a on a strip width of 200 mm.

[0128] In a preferred embodiment of the method, the carrier layer A. and optionally further layers located between the carrier layer A. and the polymer layer B. are separated from the polymer layer B. and then at least one electrical conductor track is printed onto the polymer layer B. The printing of the at least one conductor track is preferably carried out according to method 1).

[0129] A further subject matter of the invention relates to the use of a multilayer structure according to the invention or a multilayer structure produced by the method according to the invention for producing a sensor, for example for use in medical applications, or a wearable device with at least one electrical conductor track. The conductor track preferably has at least one of the following properties:

[0130] LI. A width in a range from 10 pm to 1000 pm, preferably in a range from 20 to 800 pm, particularly preferably in a range from 50 to 500 pm, most particularly preferably in a range from 80 to 300 pm.

[0131] L2. A thickness of the conductor track after the first printing pass of > 1 pm, preferably in a range of 1 pm to 20 pm;

[0132] L3. An electrical resistance <10 , more preferably <5 , particularly preferably <2 with a conductor track width of 200 pm, a design as shown in Figure 2 and carried out according to method 1. Examples

[0133] The films described in the following examples and comparative examples were produced by blown film coextrusion. The design of screw dies suitable for breaking down thermoplastic resins is described, for example, by Wortberg, Mahlke, and Effen in Kunststoffe, 84 (1994), pp. 1131-1138; by Pearson in Mechanics of Polymer Processing, Elsevier Publishers, New York, 1985; or by Davis-Standard in Paper, Film & Foil Converter 64 (1990), pp. 84-90. Die tools for shaping the melt into films are explained, among others, by Michaeli in Extrusions-Werkzeuge, Hanser Verlag, Munich, 1991.

[0134] Raw materials:

[0135] Ether-TPE-U: Thermoplastic polyurethane with crystalline superstructures based on

[0136] Polytetrahydrofuran, methylenediphenylene diisocyanate and butanediol as chain extenders and a Shore A hardness of 87 measured according to DIN 53 505, corresponding to a hardness of 36 Shore D

[0137] Ester-TPE-U: Thermoplastic polyurethane with crystalline superstructures based on

[0138] Adipic acid, methylene bisphenyl isocyanate and butanediol as chain extenders and a Shore A hardness of 93 measured according to DIN 868

[0139] Hydrophilic Ether-TPE-U :

[0140] Thermoplastic polyurethane based on polyethylene glycol, methylenediphenyl diisocyanate and butanediol as chain extender and a Shore A hardness of 83, measured according to DIN 53 505, corresponding to a hardness of 32 Shore D

[0141] Silicate: Diatomaceous earth

[0142] PS: Polystyrene

[0143] PE compound: Polyethylene with additives for improved lubrication and a density of 0.98 g / cm 3

[0144] Thermoplastic MABS copolymer:

[0145] Transparent grafted methyl methacrylate-acrylonitrile-butadiene-styrene copolymer with a ball indentation hardness of 75 MPa according to ISO 2039-1 measured at 358 N load over 30 seconds

[0146] PE-LD: Low density polyethylene without waxes and additional

[0147] Antiblocking additives and a density of 0.924 g / cm3; Shore D hardness of 48 measured according to DIN 53 505 PP: Polypropylene with a density of 0.9 g / cm 3 and a Shore D hardness of 67 measured according to ISO 868

[0148] PP compound: Polypropylene compound with a density of 0.89 g / cm 3

[0149] Example 1 :

[0150] Using a three-layer blown film die, a film with a 70 pm thick carrier layer A. made of 100 wt.% polypropylene with a Shore D hardness of 67 was produced.

[0151] A coextruded 100 pm thick polymer layer B was made from a mixture of 80 wt% of a thermoplastic ester TPE-U with a Shore A hardness of 93 and 16 wt% of a thermoplastic MABS copolymer and 4 wt% of a hydrophilic ether TPE-U with a Shore A hardness of 83.

[0152] All components used for each layer were melted together in an extruder.

[0153] The extrusion lines operated at temperatures between 160°C and 220°C. The melt streams were stacked in a three-layer blown film die with a processing temperature of 195°C and discharged through a 600 mm diameter annular die. The annular melt streamer was cooled by air blowing, then flattened, separated, and wound up.

[0154] Example 2:

[0155] Using a three-layer blown film die, a film with a 70 pm thick carrier layer A consisting of a mixture of 98 wt.% of a polypropylene with a Shore D hardness of 67 and 2 wt.% of PE compound was produced.

[0156] A 100 pm thick polymer layer B facing the carrier layer A was made from a mixture of 80 wt.% of a thermoplastic ether TPE-U with a Shore A hardness of 87 and 16 wt.% of a thermoplastic MABS copolymer and 4 wt.% of a hydrophilic ether TPE-U with a Shore A hardness of 83.

[0157] A 70 pm thick cover layer D. was made from a mixture of 98 wt.% PP compound and 2 wt.% PE compound and, after extrusion, was located on the side of the carrier layer A. opposite the polymer layer B.

[0158] All components used for each layer were melted together in an extruder. The extrusion equipment operated at temperatures between 160°C and 220°C. The three melt streams were layered on top of each other in a three-layer blown film die with a processing temperature of 195°C and extruded through a 600 mm diameter annular die. The annular melt streamer was cooled by blowing air, then flattened, separated, and wound up.

[0159] Comparison example 1:

[0160] Using a three-layer blown film die, a film with a 100 pm thick polymer layer B consisting of a mixture of 95 wt.% of a thermoplastic ether-TPE-U with a Shore A hardness of 87 and 3 wt.% hydrophilic ether-TPE-U as well as 2 wt.% silicate was produced.

[0161] All components used were melted together in an extruder.

[0162] The extrusion lines operated at temperatures between 160°C and 200°C. The melt streams were stacked in a three-layer blown film die with a processing temperature of 195°C and discharged through a 500 mm diameter annular die. The annular melt streamer was cooled by air blowing, then flattened, separated, and wound up.

[0163] Evaluation of the produced films:

[0164] All previously described films were tested for water vapor permeability, measured according to DIN 53122-2001-08 at 38°C and 90% relative humidity, and mechanical strength, measured according to DIN EN ISO 527-1-2019-12 (tensile test) and DIN 53515-1990-01 (tear propagation resistance). The release force / adhesion between carrier layer A and polymer layer B was measured based on ASTM F88a on a strip width of 200 mm.

[0165] Method 1): To characterize the printability of polymer layer B, the following steps were carried out.

[0166] 1. First, polymer layer B was printed using a screen printing process, using the print layout shown in Figure 2. The print layout featured conductor tracks of varying widths (also called conductor track widths), namely 200 μm, 150 μm, 120 μm, and 100 μm. The screen consisted of 120 PET threads per centimeter with a thread thickness of 34 μm. The electrically conductive printing paste LOCTITE EC1 1014 from Henkel AG & Co. KGaA was used.

[0167] 2. The print was dried at 120°C for 15 minutes. 3. The electrical resistance was measured using a multimeter for each printed circuit board (Figure 2) at the respective track width. If no resistance is measured, this means that the printed circuit board is not fully printed. Based on the current setup, the respective film can only be printed with functional track widths that are wider.

[0168] Table 1: Properties of the multilayer structures according to the invention compared to the structure not according to the invention

[0169] * Printed with ink LOCTITE ECI 1014 from Henkel AG & Co. KGaA, with screen consisting of 120

[0170] PET threads per centimeter and a thread thickness of 34 pm The inventive films from Examples 1 and 2 are significantly superior to the known films from Comparative Example 1. The inventive film structure in Examples 1 and 2 achieved a significant reduction in gloss at all measurement angles compared to Comparative Example 1.

[0171] The release force between the carrier film and the TPE-U layers as well as the friction coefficient are similarly good for all multilayer structures.

[0172] The inventive films from Examples 1 and 2 are significantly superior to the known films from Comparative Example 1 in terms of electrical resistance. The inventive film structure in Examples 1 and 2 achieved a significant reduction in electrical resistance with a conductor track width of 200 μm, a design as shown in Figure 2 and manufactured according to Method 1.

[0173] Measurement methods:

[0174] Softening temperature: based on standard EN ISO 60335-1:2020-08

[0175] Used Kofler bench: Company: Wagner & Münz, Device: Heating bench, Type: WME

[0176] Procedure: Four strips of film to be tested, approximately 25 cm long and approximately 4 mm wide, are cut from the film to be tested and placed on the Kofler heating bench so that the length of the film strips is positioned over the various heating zones of the preheated heating bench. After approximately 2 minutes, the measurement is performed by lifting the sample from the heating surface with tweezers and then slowly pulling it upwards at an angle of approximately 90° to the Kofler heating bench, starting from the lowest to the highest temperature. The softening point can be read directly on the heating bench at the point where the film tears and the remainder of the film adheres to the heating bench.

[0177] Evaluation: of 4 values ​​determined in a series of measurements on the same material, the lowest and highest values ​​are given as the softening range; e.g. 110 - 113°C.

[0178] Separation force / adhesion between two layers (e.g. carrier layer A. and polymer layer B.) based on ASTM F88 (method a) or DIN 53357:1982-10 (method A) on a strip width of 200 mm

[0179] The separation force measurements were performed on a 1NSTRON® 5564K4491 device from 1NSTRON®, Darmstadt, Germany, using a 10 N load cell under standard conditions of 23°C and 50% relative humidity at atmospheric pressure. The software used on the device was Bluehill V3.66.4160 (N). The clamping jaws were 50 mm wide. The measurement accuracy was 1%. The clamping jaw spacing was set to 25 mm, the measuring travel was 200 mm, and the test speed was 300 mm / min.

[0180] Before the actual measurement, the multi-layer structure to be tested was stored for at least 16 hours in a climate-controlled room under the conditions specified above. Three test specimens were cut out of the film of the multi-layer structure to be tested in the film running direction using a template (200 x 250 mm). The cut test specimens were distributed across the entire width of the film and the test specimens showed no creases or folds and had smooth cut edges. The layers of the test specimen for which the separation force was to be determined were separated from each other on one narrow side by approximately 30 + 1 mm, i.e. pre-separated over this distance. The pre-separation was carried out mechanically, preferably by hand. The polymer layer A. was thus separated from the adjacent polymer layer B. or adhesive layer C. or polymer layer E.pre-separated and adhered to a 250 mm wide metal rail that was equipped with a 200 mm wide double-sided adhesive strip from Tesa, Germany (tesa® 4965 PPI 9 or similar acrylic adhesive tape). The remaining multi-layer structure was placed on polymer layer A with the layer that had previously been in contact with polymer layer A. and adhered to a second metal rail, which also had a double-sided adhesive strip from Tesa, Germany (tesa® 4965 PPI 9 or similar acrylic adhesive tape). The second metal rail was clamped in the upper clamping jaw of the 1NSTRON® 5564K4491 measuring device and the first metal rail with polymer layer A. was placed in the lower clamping jaw. The force of the load cell was set to 0, whereby the force was not set back to 0 for the second and third measurements. The film should neither sag nor exert any force on the load cell.The uncut end of the film was directed forward. The film end was held at a right angle to the direction of tension using a metal rod, and the machine was started. The metal rod was moved along in such a way that the right angle was maintained. After a measuring travel of 200 mm, the test was completed, and the measurement diagram could be removed from the device. The first and last quarters of the diagram were not used to calculate the separation force. The average separation force, which corresponded to the average tensile force acting on the test specimens, was calculated from the middle two quarters of the diagram.

[0181] Figures

[0182] Figures 1-2 describe preferred embodiments of the multilayer structure and the method for its production, which are not to be interpreted as limiting. The figures show

[0183] Figure 1a: a schematic representation of a multilayer structure according to the invention with a carrier layer A and a polymer layer B;

[0184] Figure 1b: a schematic representation of a multi-layer structure according to the invention with a carrier layer A. and a polymer layer B. as well as an adhesive layer C. and a cover layer D.

[0185] Figure 2: a representation of a multilayer structure with electrical conductor tracks;

[0186] Figure 1a shows a multilayer structure 100 according to the invention, which has a first carrier layer A. 10 and a polymer layer B. 20, produced as described in Example 1. Optionally, a cover layer D. 40 can be arranged on the side of the polymer layer B. 20 that is opposite the carrier layer A. 10. Figure 1b shows a multilayer structure 100 according to the invention, which has a first carrier layer A. 10 and a polymer layer B. 20 and also has a further polymer layer E. 50 and optionally a cover layer D. 40.

[0187] Figure 1c shows a multilayer structure 100 according to the invention, which comprises a first carrier layer A. 10 and a polymer layer B. 20, and optionally also comprises an adhesive layer C. 30 and optionally a cover layer D. 40. Furthermore, the multilayer structure 100 also comprises a further polymer layer E. 50, which is located between the carrier layer A. 10 and the polymer layer B. As mentioned, an adhesive layer C. 30 can also be inserted between the polymer layer B. and the polymer layer E.

[0188] Figure 2 shows a multilayer structure 100 according to the invention, as it was produced according to Example 1 and subsequently printed with an electrically conductive ink to produce an electrical conductor track 60, as described for the examples in Table 1 with reference to Example 1. The conductor track 60 is applied in a meandering shape to the polymer layer B of the multilayer structure 100. Each strand 65 of the conductor track 60 is connected to an adjacent conductor track strand 65, 67 or 69 via a meandering loop 180. The outer conductor track strands 67 and the innermost conductor track strand 69 are minimally longer than all other strands 65, with the lengths 160 and 120 of the respective conductor track strands 65 each being 83.6 mm and the inner conductor track strand 69 having a length 130 of 86 mm. The two outer conductor track strands 67 are each connected to a contact 110. The contact 110 has a width of 170 of 2 mm and a length of 190 of 2 mm.The width 140 of the complete meandering conductor track 60 is 5.7 mm. An enlargement of some conductor track strands 65 and one conductor track strand 67 of the conductor track 60 can be seen in the magnifying glass 70. The width 80 of the conductor track 60 is between 100 and 200 μm, depending on the design, with a maximum deviation of 10 μm. The magnifying glass 200 shows the meandering or U-shaped spacers 180 between the conductor track strands 65, 67, and 69, with the length 150 of the U 180 being approximately 0.25 mm.

Claims

A co-extruded multilayer structure comprising at least the following layers: A. at least one carrier layer A., ​​comprising > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.% of a polymer, based on the total weight of the carrier layer A., ​​with a hardness in a range from 50 Shore D to 90 Shore D, preferably from 55 Shore D to 85 Shore D, particularly preferably from 60 Shore D to 80 Shore D, measured according to DIN ISO 7619-1-2012-02, wherein at least one of the at least one carrier layer is designed as an outer layer A.; B. at least one polymer layer B., comprising at least one thermoplastic elastomer, preferably a thermoplastic polyurethane in an amount of > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.% based on the total weight of the polymer layer B.; C. optionally at least one hot-melt adhesive layer C., which is preferably arranged between the carrier layer A. and the polymer layer B., D. optionally at least one cover layer D. comprising > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.% of a polypropylene, based on the total weight of the cover layer D., E. optionally at least one further polymer layer E, comprising at least one thermoplastic elastomer, preferably a thermoplastic polyurethane in an amount of > 70 wt.%, preferably > 80 wt.%, particularly preferably > 90 wt.%, based on the total weight of the polymer layer E. wherein the co-extruded multi-layer structure has at least one, preferably at least two, more preferably at least three, particularly preferably at least all of the following properties: (El) a layer thickness of the carrier layer A in a range from 30 to 200 pm, preferably from 40 to 150 pm, more preferably from > 50 to 120 pm; particularly preferably from 55 to 110 pm; most preferably from 60 to 100 pm; (E2) a layer thickness of the polymer layer B. in a range from 30 to 200 pm, preferably from 40 to 150 pm, more preferably from > 50 to 120 pm, particularly preferably from 55 to 110 pm; most preferably from 60 to 100 pm; (E3) a separation force between the carrier layer A. and one of the layers in contact with the carrier layer A., ​​selected from the group consisting of the polymer layer B., the adhesive layer C. or the further polymer layer E., in a range from 0.01 N / cm to 0.1 N / cm; preferably 0.015 N / cm to 0.08 N / cm, more preferably from 0.02 to 0.07 N / cm, particularly preferably from 0.025 to 0.06 N / cm; (E4) has a content of additives, for example waxes, adhesion promoters, dyes in the carrier layer A. in a range from 0 to 15 wt.%, more preferably from 0 to 12 wt.%, particularly preferably from 0.1 to 10 wt.%, in each case based on the total weight of the carrier layer A.; (E5) a content of additives in the polymer layer B., in particular selected from the group consisting of an antiblocking agent, in an amount in a range from 0 to 10 wt.%, preferably 1 to 8 wt.%, particularly preferably 2 to 6 wt.%, based on the total weight of the polymer layer B. and / or matting agents in an amount in a range from 0 to 20 wt.%, preferably 1 to 18 wt.%, particularly preferably 5 to 15 wt.%, in each case based on the total weight of the polymer layer B.; (E6) a hardness of the polymer layer B. in a range of 60 Shore A and 55 Shore D, preferably 70 Shore A to 45 Shore D, particularly preferably 80 Shore A to 95 Shore A; (E7) a water vapor permeability of at least the polymer layer B. of > 400 g / c 2 d, preferably > 500 g / c 2 d; (E8) a resistance of a 200 pm wide conductor track strand produced according to method 1) of < 10 , more preferably < 5 , particularly preferably < 2 . The multilayer structure according to claim 1, wherein the multilayer structure has at least one applied, preferably printed, conductor track. The multilayer structure according to claim 2, wherein the at least one conductor track has at least one of the following properties: LI. a width of > 10 pm, preferably in a range of 10 to 1000 pm; L2. a thickness in a range of >1 pm, preferably in a range of 1 pm to 20 pm; L3. an electrical resistance < 10 , more preferably < 5 , particularly preferably < 2 Ω, with a conductor track width of 200 pm, wherein the conductor track has a design as shown in Figure 2 and was produced according to method 1. The multilayer structure according to one of the preceding claims, wherein the at least one carrier layer A. comprises a polypropylene polymer or a PET or a mixture thereof, preferably polypropylene.

5. The multi-layer structure according to one of the preceding claims, wherein the adhesive layer C. comprises a polymer selected from the group consisting of polyamide, co-polyamide, polyester, co-polyester, TPE-U or a combination of at least two thereof.

6. The multilayer structure according to one of the preceding claims, wherein the elastomer of the polymer layer B. comprises a thermoplastic polyurethane composed of a polyol component and a polyisocyanate component, wherein the polyol component of the TPE-U is selected from the group consisting of polytetrahydrofuran groups, polyethylene glycol ether groups, polyethylene glycol ester groups or a combination of at least two thereof.

7. The multi-layer structure according to one of the preceding claims, wherein the thermoplastic polyurethane used in the polymer layer B. comprises polyethylene glycol ether groups or polyethylene glycol ester groups or a combination of these two in an amount in a range of 20 to 80 wt.%, preferably in a range of 30 to 70 wt.%, particularly preferably in a range of 40 to 60 wt.%, based on the total weight of the polymer layer B.

8. The multi-layer structure according to one of the preceding claims, wherein at least one of the at least one carrier layer A., ​​in particular the carrier layer A., ​​has at least one, preferably at least two, particularly preferably all of the following properties: (Al) A thickness in a range of 40 to 150 pm; (A2) A density in a range of 0.8 to 1.0 g / cm 3 ; (A3) A hardness in a range of 55 Shore D to 85 Shore D.

9. The multilayer structure according to one of the preceding claims, wherein the polymer layer B. has at least one of the following properties: (Bl) A thickness in a range of 40 to 150 pm; (B2) A density in a range of 1.05 to 1.3 g / cm 3 , preferably 1.1 to 1.25 g / cm 3 , particularly preferably from 1.12 to 1.21 g / cm 3 , according to DIN EN ISO 1183-1-A; (B3) A tear strength in a range of 50 to 80 kN / m, preferably 60 to 120 kN / m, measured according to DIN ISO 34-1,B; (B4) An elongation at break of a 50 pm thick film in a range of 350 to 800%, preferably in a range of 400 to 700%, particularly preferably 450 to 650% according to DIN EN ISO 527-2016-09; (B5) A fracture stress in a range of 50 to 80 MPa, preferably 55 to 75 MPa, measured according to DIN EN ISO 527-2016-09 (B6) A stress at 50% strain in a range of 4 to 11 MP according to DIN EN ISO 527-2016-09; (B7) A Shore hardness in the range of 70 - 100 A, preferably 80 - 95 A.

10. The multilayer structure according to one of the preceding claims, wherein the multilayer structure has at least 3 layers, preferably with two carrier layers A., one polymer layer B., optionally at least one adhesive layer C. between one of the at least one carrier layers A., preferably the carrier layer A. and the polymer layer B.

11. The multilayer structure according to one of the preceding claims, wherein the multilayer structure has at least 4 layers, preferably with two carrier layers A., one polymer layer B., optionally at least one adhesive layer C. between one of the at least one carrier layers A., preferably the carrier layer A. and the polymer layer B., optionally one.

12. The multilayer structure according to any one of the preceding claims, wherein the multilayer structure is produced by a blown film process.

13. A method for producing a multilayer structure, comprising at least the steps: (51) Providing a first polymer A) comprising a polypropylene in an amount in a range of 80 wt% to 100 wt%; (52) providing a further polymer B) comprising at least one thermoplastic polyurethane in an amount in a range of 80 wt% to 98 wt%; (53) Optionally providing a further polymer C) comprising at least one thermoplastic polyurethane in an amount in a range of 80 wt% to 98 wt%; (54) Optionally providing a further polymer D) comprising at least one thermoplastic polyurethane in an amount in a range of 80 wt% to 98 wt%; (55) Optionally providing a further polymer E) comprising at least one thermoplastic polymer, preferably a polyether block amide or a TPE-U, or both in an amount in a range of 80 wt% to 100 wt%; (56) melting the two polymers A) and B) and optionally C) and / or D) and / or E) in separate extruders; (57) feeding the melts of polymers A) and B) and optionally C) and / or D) and / or E) into a ring die of a blown film line; (58) Coextruding the melts of the polymers A) and B) and optionally C) and / or D) and / or E) in the blown film line to form the multilayer structure, comprising at least one carrier layer A. formed from the polymer A) and one polymer layer B., formed from the polymer B) and optionally an adhesive layer C., formed from the polymer C), optionally a cover layer D., formed from the polymer D) and optionally a further polymer layer E., formed from the further polymer E), and then cooling the multilayer structure, wherein the multilayer structure has a separation force between the carrier layer A. and a layer in contact with the carrier layer A., ​​selected from the group consisting of the polymer layer B., the adhesive layer C. or the further polymer layer E., in a range from 0.01 N / cm to 0.1 N / cm; preferably 0.015 N / cm to 0.08 N / cm, more preferably from 0.02 to 0.07 N / cm, particularly preferably from 0.025 to 0.06 N / cm.The method according to claim 13, wherein the carrier layer A. and optionally further layers located between the carrier layer A. and the polymer layer B. are separated from the polymer layer B. and then an electrical conductor track is printed onto the polymer layer B. A use of a multilayer structure according to one of claims 1 to 13 or produced according to one of claims 13 or 14 for producing a medical sensor or a wearable with at least one electrical conductor track.

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