AGING-RESISTANT TPU

Description

[0001] The present invention relates to thermoplastic polyurethanes obtainable or obtained by a process comprising reacting a thermoplastic polyester (PE-1) with a diol (D1) to obtain a composition (Z1) containing a polyester (PE-2) and reacting the composition (Z1) obtained according to step (i) with an isocyanate composition (11) containing at least one polyisocyanate, and a polyol composition (P1), wherein the polyol composition (P1) contains at least one polycarbonate polyol (PC1), as well as a process for producing the thermoplastic polyurethane. The present invention further relates to a composition comprising a thermoplastic polyurethane according to the invention and at least one flame retardant.The present invention also relates to the use of such a thermoplastic polyurethane for the manufacture of cable sheathing as well as films, molded parts, rolls, fibers, automotive trim, hoses, cable connectors, bellows, trailing cables, cable sheathing, seals, belts or damping elements containing such a thermoplastic polyurethane.

[0002] Thermoplastic polyurethanes are widely known for their good mechanical properties, high abrasion resistance, and high elasticity. They are therefore used in a wide variety of applications. However, increasingly stringent requirements are being placed on their aging and hydrolysis resistance in these applications. Furthermore, fire behavior is also frequently a requirement.

[0003] US 3,509,233 A discloses a thermoplastic polyurethane (TPU) obtainable by reacting a polyol blend with a polyisocyanate. DE 10 2013 021027A1 also discloses a process for producing a thermoplastic polyurethane, wherein a mixture of a polycarbonate polyol and a polyester polyol is first reacted with an aromatic diisocyanate and subsequently chain-extended with a diol.

[0004] DE 198 00 287 A1 discloses a thermoplastic polyurethane obtained by reacting a polyol mixture with a polyisocyanate, wherein the polyol mixture contains a polyester polyol and a polycarbonate polyol.

[0005] Particularly stringent requirements are placed on cables used in automotive applications, for example. Key standards for cables in automotive applications are LV 112 and ISO 6722, which classify materials according to specific temperature classes.

[0006] Previously, cables of temperature class C were sufficient for use in automotive applications. It was enough if they passed the standard winding test for cables after hot air aging at 125°C for 3000 hours. In addition, good hydrolysis resistance during humid heat storage for 1000 hours at 85°C and 85 percent relative humidity was often required.

[0007] For new applications, manufacturers often choose cables suitable for temperature class D (up to 150 °C) for applications close to the engine. Examples include the engine wiring harness and the transmission connection. Electric and hybrid vehicles place particularly high demands on the wiring harness and cables, which are only partially comparable to conventional vehicle electrical systems. Due to high voltages of up to 1000 V and correspondingly high currents, these cables must withstand significantly higher temperatures than their predecessors. The cables must pass the standard winding test after 3000 hours of hot air aging at 150 °C.

[0008] For temperature class D (up to 150 °C), ethylene tetrafluoroethylene copolymers (ETFE) are among the materials used. However, corrosive gases are formed when ETFE is used in the event of a fire, which often limits the use of these materials.

[0009] Another material option is special cross-linked polyolefin compounds. However, these cross-linked polyolefin compounds are very complex and expensive to produce due to the necessary post-processing cross-linking through irradiation or vulcanization, and often reach their limits due to chemical resistance and low mechanical strength. Furthermore, these cross-linked materials have the disadvantage of not being recyclable and can cause problems with water tightness when injection molded into connectors and grommets.

[0010] The now predominantly used LV 112 standard also introduces stricter requirements regarding hydrolysis resistance at high temperatures. While ISO 6722 is satisfied with 1,000 hours at 85 degrees Celsius and 85 percent relative humidity, LV 112 requires a service life of 3,000 hours in this respect as well.

[0011] The remaining requirements for cable sheathing are largely identical in both sets of regulations and are standard for the materials offered for this purpose today. These include insensitivity to cold, resistance to various media, inhibition of fungal growth, and compatibility with other materials in the cable assembly, such as adhesive tapes, heat shrink tubing, and connectors.

[0012] However, for many applications, there are no materials available that combine good mechanical properties with the special requirements of automotive applications.

[0013] One object of the present invention was to provide thermoplastic polyurethanes that combine the good mechanical and elastic properties and high abrasion resistance of thermoplastic polyurethanes with higher temperature and hydrolysis resistance.

[0014] According to the invention, this problem is solved by a thermoplastic polyurethane obtainable or obtained by a method comprising steps (i) and (ii) (i) Reaction of a thermoplastic polyester (PE-1) with a diol (D1) to obtain a composition (Z1) containing a polyester (PE-2) (ii) Reaction of the composition (Z1) obtained according to step (i) with an isocyanate composition (11) containing at least one polyisocyanate, and a polyol composition (P1), wherein the polyol composition (P1) contains at least one polycarbonate polyol (PC1), wherein the thermoplastic polyester (PE-1) has a molecular weight in the range of 15000 g / mol to 70000 g / mol and the polyester (PE-2) has a molecular weight in the range of 1000 g / mol to 6000 g / mol, and wherein the diol (D1) is 1,4-butanediol and the thermoplastic polyester (PE-1) is selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid.

[0015] The process according to the invention comprises steps (i) and (ii). According to step (i), at least one thermoplastic polyester (PE-1) is reacted with a diol (D1) to obtain a composition (Z1) containing a polyester (PE-2). According to step (ii) of the process according to the invention, the composition (Z1) obtained according to step (i) is reacted with an isocyanate composition (11), containing at least one polyisocyanate, and a polyol composition (P1), wherein the polyol composition (P1) contains at least one polycarbonate polyol (PC1).

[0016] The reaction according to step (i) is preferably carried out continuously. According to a further embodiment, the present invention therefore relates to a process for producing a thermoplastic polyurethane as described above, wherein the reaction according to step (i) is carried out continuously.

[0017] The reaction according to step (ii) is carried out under suitable conditions that allow the diisocyanate to react with the free reactive groups. According to the invention, the reaction can be carried out in suitable apparatus, and suitable methods are known to those skilled in the art. According to the invention, it is also possible to use additives or auxiliaries to accelerate or improve the reaction according to step (i) or (ii). In particular, catalysts can be used.

[0018] Suitable catalysts for the reaction according to step (i) are, for example, tributyltin oxide, tin(II) diisooctoate, dibutyltin dilaurate, tetrabutyl orthotitanate or bi(III) carboxylates.

[0019] In particular, the implementation according to step (i) or the implementation according to step (ii) or the implementation according to step (i) and step (ii) can be carried out in an extruder.

[0020] The conversion according to step (i) can, for example, take place at a temperature in the range of 200 to 310°C, preferably in the range of 220 to 300°C and particularly from 220 to 280°C, more preferably from 230 to 260°C, and a residence time of 15 seconds to 30 minutes, preferably 20 seconds to 10 minutes, in, for example, a flowable, softened or preferably molten state of the polyester and the diol, in particular by stirring, rolling, kneading or preferably extrusion, for example using conventional plasticizing devices such as mills, kneaders or extruders, preferably in an extruder.

[0021] The method according to the invention may include further steps, for example temperature adjustments or shaping steps.

[0022] According to step (i), a thermoplastic polyester (PE-1) is used. Suitable thermoplastic polyesters according to the invention are known per se. Suitable polyesters are composed of at least one dicarboxylic acid and at least one suitable dihydroxy compound. The polyesters can be produced, for example, by polycondensation of aliphatic or aromatic dicarboxylic acids or mixtures of aromatic and aliphatic and / or cycloaliphatic dicarboxylic acids and the corresponding ester-forming derivatives, such as dicarboxylic anhydrides, mono- and / or diesters with expediently a maximum of 4 carbon atoms in the alcohol residue, with aliphatic dihydroxy compounds at elevated temperatures, for example, from 160 to 260°C, in the presence or absence of esterification catalysts.

[0023] According to the invention, terephthalic acid is particularly suitable.

[0024] According to the invention, polyesters of functionalized dicarboxylic acids can also be used, for example, polyesters based on lactic acid.

[0025] Aliphatic or aromatic dihydroxy compounds can be used as further structural components of the thermoplastic polyesters (PE-1) within the scope of the present invention. Preferably, alkanediols with 2 to 6 carbon atoms and cycloalkanediols with 5 to 7 carbon atoms are suitable as aliphatic dihydroxy compounds. Examples and preferred applications include 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and 1,4-cyclohexanediol, or mixtures of at least two of the aforementioned diols.

[0026] According to the invention, suitable thermoplastic polyesters are selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid. The thermoplastic polyester (PE-1) is selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid.

[0027] According to the invention, suitable molecular weight ranges (Mn) of the polyester used are in the range of 15000 to 70000, particularly preferably in the range of 20000 to 30000.

[0028] According to the invention, the thermoplastic polyester (PE-1) has a molecular weight in the range of 15000 g / mol to 70000 g / mol.

[0029] Unless otherwise specified, the present invention describes the determination of the weight-mean molecular weights (Mw) of thermoplastic polyesters dissolved in HFIP (hexafluoroisopropanol) using GPC. The molecular weight is determined using two GPC columns connected in series (PSS gel; 100A; 5 µm; 300 x 8 mm, Jordi gel DVB; MixedBed; 5 µm; 250 x 10 mm; column temperature 60°C; flow rate 1 mL / min; RI detector). Calibration is performed using polymethyl methacrylate (EasyCal; PSS, Mainz, Germany), and HFIP is used as the mobile phase.

[0030] According to step (i), the thermoplastic polyester (PE-1) is reacted with a diol (D1). According to the invention, 1,4-butanediol is used as the diol (D1).

[0031] According to step (i) a composition (Z1) containing a polyester (PE-2) is obtained, which is then reacted according to step (ii).

[0032] The composition (Z1) is typically a mixture that, in addition to the polyester (PE-2), may also contain unreacted polyester (PE-1) or unreacted diol. According to the invention, the polyester (PE-2) is present as a mixture, wherein the individual molecules may differ, for example, in their distribution and the length of the polyester blocks. According to the invention, the polyester (PE-2) preferably has a molecular weight in the range of 1000 g / mol to 6000 g / mol, more preferably in the range of 1500 g / mol to 4500 g / mol, and particularly preferably in the range of 2000 g / mol to 4000 g / mol.

[0033] The composition (Z1) is then reacted with an isocyanate composition (I1) and a polyol composition (P1) according to step (ii).

[0034] According to the invention, the polyol composition (P1) contains at least one polycarbonate polyol (PC1). Suitable polycarbonate polyols are known to those skilled in the art. Within the scope of the present invention, aliphatic polycarbonate diols are particularly suitable. Suitable polycarbonate diols are, for example, polycarbonate diols based on alkane diols. Suitable polycarbonate diols are strictly difunctional OH-functional polycarbonate diols, preferably strictly difunctional OH-functional aliphatic polycarbonate diols. Suitable polycarbonate diols are based, for example, on butanediol, pentanediol, or hexanediol, in particular 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentane-(1,5)diol, or mixtures thereof, especially preferably 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, or mixtures thereof.Preferably, within the scope of the present invention, polycarbonate diols based on butanediol and hexanediol, polycarbonate diols based on pentanediol and hexanediol, polycarbonate diols based on hexanediol, and mixtures of two or more of these polycarbonate diols are used.

[0035] According to a further embodiment, the present invention also relates to a thermoplastic polyurethane as previously described, wherein the at least one polycarbonate polyol (PC1) is selected from the group consisting of polycarbonate diols based on butanediol and hexanediol, polycarbonate diols based on pentanediol and hexanediol, polycarbonate diols based on hexanediol, and mixtures of two or more of these polycarbonate diols.

[0036] Preferably, the polycarbonate diols used have a number-average molecular weight Mn in the range of 500 to 4000, determined by GPC, preferably in the range of 650 to 3500, determined by GPC, and particularly preferably in the range of 800 to 3000, determined by GPC.

[0037] According to a further embodiment, the present invention also relates to a thermoplastic polyurethane as previously described, wherein the at least one polycarbonate polyol (PC1) has a number-average molecular weight Mn in the range of 500 to 4000, determined via GPC.

[0038] According to the invention, the polyol composition (P1) can contain further polyols. Suitable polyols are generally known to those skilled in the art and are described, for example, in the "Plastics Handbook, Volume 7, Polyurethanes", Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1. Polyester ols or polyether ols are particularly preferred as polyols. Polyethylene polyols are especially preferred. The number-mean molecular weight of the polyols used according to the invention is preferably between 500 g / mol and 3000 g / mol, more preferably between 600 g / mol and 2500 g / mol, and particularly between 650 g / mol and 2000 g / mol.

[0039] Preferred polyetherols according to the invention are polyethylene glycols, polypropylene glycols and polytetrahydrofurans.

[0040] According to the invention, the polyol composition can, for example, also contain a solvent. Suitable solvents are known to those skilled in the art.

[0041] Within the scope of the present invention, additives or auxiliaries can also be used in the conversion in the polyol composition, for example antioxidants, UV absorbers, UV filters, hydrolysis inhibitors, waxes, lubricants, plasticizers, processing aids, nucleating agents, fillers, flame retardants.

[0042] According to the invention, at least one isocyanate composition (I1) containing at least one polyisocyanate is used. Preferably, a diisocyanate is used as the polyisocyanate. According to the invention, mixtures of two or more diisocyanates can also be used. Preferred diisocyanates within the scope of the present invention are, in particular, aliphatic or aromatic diisocyanates.

[0043] Preferably aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates are used, further preferably tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene diisocyanate-1,5, 2-ethylbutylene diisocyanate-1,4, pentamethylene diisocyanate-1,5, butylene diisocyanate-1,4, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl cyclohexane (isophorone diisocyanate, IPDI), 1,4- and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or -2,6-cyclohexane diisocyanate and / or 4,4'-, 2,4'- and 2,2'-Dicyclohexylmethane diisocyanate, 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl diisocyanate, 1,2-diphenylethane diisocyanate and / or phenylene diisocyanate. 4,4'MDI is particularly preferred.

[0044] Common aliphatic and / or cycloaliphatic diisocyanates are used, for example tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 2-ethyltetramethylene-1,4-diisocyanate, hexamethylene-1,6-diisocyanate (HDI), pentamethylene-1,5-diisocyanate, butylene-1,4-diisocyanate, trimethylhexamethylene-1,6-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (isophorone diisocyanate, IPDI), 1,4- and / or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or 1-methyl-2,6-cyclohexane diisocyanate. 4,4'-, 2,4'- and / or 2,2'-Methylenedicyclohexyl diisocyanate (H12MDI).

[0045] According to a further embodiment, the present invention also relates to a thermoplastic polyurethane as previously described, wherein the polyisocyanate is selected from the group consisting of hexamethylene diisocyanate and diphenylmethane diisocyanate (MDI).

[0046] According to the invention, the isocyanate composition can be used in pure form or in the form of a composition containing the diisocyanate and at least one solvent. Suitable solvents are known to those skilled in the art. Suitable examples include non-reactive solvents such as ethyl acetate, methyl ethyl ketone, tetrahydrofuran, and hydrocarbons.

[0047] According to the invention, further input materials can be added during the implementation according to step (ii), for example catalysts or auxiliary and additive materials.

[0048] Catalysts that particularly accelerate the reaction between the NCO groups and the hydroxyl groups of compounds reactive towards isocyanates are, for example, tertiary amines, in particular triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N'-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo-(2,2,2)octane; in another preferred embodiment, these are organic metal compounds such as titanium dioxide esters, iron compounds, preferably iron(III) acetylacetonate, tin compounds, preferably tin diacetate, tin dioctoate, tin dilaurate or the tin dialkyl salts of aliphatic carboxylic acids, preferably dibutyltin diacetate, dibutyltin dilaurate or bismuth salts in which bismuth is preferably present in oxidation states 2 or 3, in particular 3. Salts of carboxylic acids are preferred. Carboxylic acids with 6 to 14 carbon atoms, and especially those with 8 to 12 carbon atoms, are preferably used.Examples of suitable bismuth salts are bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate. The catalysts (d) are preferably used in amounts of 0.0001 to 0.1 parts by weight per 100 parts by weight of the isocyanate-reactive compound (b). Tin catalysts, in particular tin dioctoate, are preferred.

[0049] The catalysts are typically used in amounts of 3 ppm to 2000 ppm, preferably 10 ppm to 1200 ppm, more preferably 20 ppm to 1000 ppm and most preferably 30 ppm to 800 ppm.

[0050] In addition to catalysts, common additives can also be added during the reaction according to step (ii). Examples include surfactants, fillers, further flame retardants, nucleating agents, oxidation stabilizers, sliding and demolding aids, dyes and pigments, optionally stabilizers (e.g., against hydrolysis, light, heat, or discoloration), inorganic and / or organic fillers, reinforcing agents, and plasticizers. Suitable additives and additives can be found, for example, in the Plastics Handbook, Volume VII, edited by Vieweg and Höchtlen, Carl Hanser Verlag, Munich 1966 (pp. 103–113).

[0051] According to the invention, a thermoplastic polyurethane is obtained. The properties of the thermoplastic polyurethane according to the invention can vary in further ranges. Preferably, the thermoplastic polyurethane according to the invention has a Shore hardness in the range of 45A to 78D, more preferably a Shore hardness in the range of 80A to 70D, and particularly preferably a Shore hardness in the range of 85A to 95A.

[0052] According to a further embodiment, the present invention also relates to a thermoplastic polyurethane as previously described, wherein the thermoplastic polyurethane has a Shore hardness in the range of Shore 45 A to Shore 78 D.

[0053] According to another aspect, the present invention also relates to a method for producing a thermoplastic polyurethane, comprising steps (i) and (ii) (i) Reaction of a thermoplastic polyester (PE-1) with a diol (D1) to obtain a composition (Z1) containing a polyester (PE-2) (ii) Reaction of the composition (Z1) obtained according to step (i) with an isocyanate composition (11) containing at least one polyisocyanate, and a polyol composition (P1), wherein the polyol composition (P1) contains at least one polycarbonate polyol (PC1), wherein the thermoplastic polyester (PE-1) has a molecular weight in the range of 15000 g / mol to 70000 g / mol and the polyester (PE-2) has a molecular weight in the range of 1000 g / mol to 6000 g / mol, and wherein the diol (D1) is 1,4-butanediol and the thermoplastic polyester (PE-1) is selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid.

[0054] Regarding preferred embodiments, reference is made to the above-mentioned explanations.

[0055] The present invention further relates to a composition containing a thermoplastic polyurethane according to the invention. Within the scope of the present invention, the composition may contain further components such as fillers, glass fibers, plasticizers, or flame retardants. The composition may contain one or more of the aforementioned components.

[0056] The present invention therefore also relates to a composition comprising at least the components (A) and (B) (A) a thermoplastic polyurethane according to the present invention, (B) at least one flame retardant.

[0057] Suitable fillers, plasticizers, or flame retardants are known to those skilled in the art. Preferably, within the scope of the present invention, flame retardants selected from the group consisting of metal hydroxides, nitrogen-containing flame retardants, and phosphorus-containing flame retardants can be used.

[0058] According to a further embodiment, the present invention also relates to a composition as previously described, wherein the flame retardant is selected from the group consisting of metal hydroxides, nitrogen-containing flame retardants and phosphorus-containing flame retardants.

[0059] The composition according to the invention contains the at least one thermoplastic polyurethane typically in an amount in the range of 20 wt.% to 90 wt.%, based on the total composition, preferably in the range of 50 wt.% to 90 wt.%, more preferably in the range of 60 wt.% to 85 wt.% and particularly preferably in the range of 65 wt.% to 85 wt.%, in each case based on the total composition.

[0060] According to a further embodiment, the present invention also relates to a composition as described above, wherein the proportion of the total thermoplastic polyurethanes in the composition is in the range of 20 to 90 wt.%, based on the total composition.

[0061] In one embodiment, thermoplastic polyurethane and flame retardant are processed in a single step to produce the compositions according to the invention. In other preferred embodiments, a thermoplastic polyurethane, preferably as granules, is first produced using a reaction extruder, a conveyor belt system, or other suitable equipment. At least one further flame retardant is then incorporated into this granulate in at least one further step, or even several further steps.

[0062] The mixing of the thermoplastic polyurethane with the at least one flame retardant takes place, for example, in a mixing device, which is preferably an internal kneader or an extruder, preferably a twin-screw extruder. In another preferred embodiment using an extruder, the introduced flame retardant is liquid at the temperature prevailing downstream in the flow direction after its addition to the extruder.

[0063] Suitable flame retardants include metal hydroxides. In the event of a fire, metal hydroxides release only water and therefore do not form toxic or corrosive flue gas products. Furthermore, these hydroxides are able to reduce the density of the flue gas in a fire. However, a disadvantage of these substances is that they may promote the hydrolysis of thermoplastic polyurethanes and also influence the oxidative aging of polyurethanes.

[0064] Suitable metal hydroxides for the purposes of the present invention are preferably magnesium, calcium, zinc, and / or aluminum hydroxides, or mixtures thereof. Particularly preferred is a metal hydroxide selected from the group consisting of aluminum hydroxides, aluminum oxide hydroxides, magnesium hydroxide, and a mixture of two or more of these hydroxides.

[0065] The compositions according to the invention can also contain a phosphorus-containing flame retardant. In principle, all known phosphorus-containing flame retardants for thermoplastic polyurethanes can be used according to the invention.

[0066] Preferably, derivatives of phosphoric acid, derivatives of phosphonic acid, or derivatives of phosphinic acid, or mixtures of two or more of these derivatives, are used within the scope of the present invention. According to a further preferred embodiment, the phosphorus-containing flame retardant is liquid at 21 °C.

[0067] Preferably, the derivatives of phosphoric acid, phosphonic acid, or phosphinic acid are salts with an organic or inorganic cation or are organic esters. Organic esters are derivatives of the phosphorus-containing acids in which at least one oxygen atom directly bonded to the phosphorus is esterified with an organic residue. In a preferred embodiment, the organic ester is an alkyl ester, and in another preferred embodiment, an aryl ester. Particularly preferably, all hydroxyl groups of the corresponding phosphorus-containing acid are esterified.

[0068] Suitable organic phosphate esters include, for example, the triesters of phosphoric acid, such as trialkyl phosphates and especially triaryl phosphates, such as resorcinol bis (diphenyl phosphate).

[0069] According to the invention, salts of the respective derivatives of phosphoric acid, phosphonic acid, or phosphinic acid are particularly suitable, and phosphinate salts are more preferably used. Melamine polyphosphate or dithylaluminum phosphinate are suitable examples within the scope of the present invention.

[0070] Furthermore, nitrogen-containing flame retardants can also be used within the scope of the present invention. According to the invention, in principle all known nitrogen-containing flame retardants for thermoplastic polyurethanes can be used.

[0071] Suitable flame retardants within the scope of the present invention include, for example, melamine derivatives such as, in particular, melamine polyphosphate or melamine cyanurate.

[0072] Within the scope of the present invention, it is also possible that the composition contains, in addition to the thermoplastic polyurethane, mixtures of various flame retardants, for example a melamine derivative and a phosphoric acid derivative, or a melamine derivative and a phosphinic acid derivative, or a melamine derivative, a phosphoric acid derivative and a phosphinic acid derivative.

[0073] The melamine derivative may preferably be a melamine cyanurate. Accordingly, the present invention, according to a further embodiment, may also relate to a composition which, in addition to the thermoplastic polyurethane, contains, for example, a melamine cyanurate and a phosphoric acid derivative, or a melamine cyanurate and a phosphinic acid derivative, or a melamine cyanurate, a phosphoric acid derivative, and a phosphinic acid derivative. For example, the composition according to the invention comprises at least one thermoplastic polyurethane, at least one melamine cyanurate, at least one first phosphorus-containing flame retardant (F1) selected from the group consisting of phosphoric acid derivatives and phosphonic acid derivatives, and at least one further phosphorus-containing flame retardant (F2) selected from the group consisting of phosphinic acid derivatives.

[0074] Preferably, the composition contains no further flame retardants besides melamine cyanurate, at least one phosphorus-containing flame retardant (F1), and at least one phosphorus-containing flame retardant (F2). More preferably, the composition according to the invention contains exactly one phosphorus-containing flame retardant (F1) selected from the group consisting of derivatives of phosphoric acid and derivatives of phosphonic acid, and exactly one phosphorus-containing flame retardant (F2) selected from the group consisting of derivatives of phosphinic acid.

[0075] The present invention also relates to the use of the composition according to the invention, comprising at least one flame-retardant thermoplastic polyurethane as described above, for the production of coatings, damping elements, bellows, films or fibers, molded parts, flooring for buildings and transportation, nonwovens, preferably seals, rollers, shoe soles, hoses, cables, cable connectors, cable sheathing, cushions, laminates, profiles, belts, saddles, foams, connectors, trailing cables, solar modules, and automotive trim. Its use for the production of cable sheathing is preferred. Production is carried out, preferably from granules, by injection molding, calendering, powder sintering, or extrusion and / or by additional foaming of the composition according to the invention.

[0076] According to another aspect, the present invention also relates to the use of a thermoplastic polyurethane as previously described or a composition as previously described for the manufacture of cable sheathing.

[0077] Due to their good mechanical properties and good temperature behavior, the thermoplastic polyurethanes and compositions according to the invention are particularly suitable for the production of films, molded parts, rolls, fibers, trims in automobiles, hoses, cable connectors, bellows, trailing cables, cable sheathing, seals, belts or damping elements.

[0078] Accordingly, the present invention also relates to films, molded parts, rolls, fibers, automotive trim, hoses, cable connectors, bellows, trailing cables, cable sheathing, seals, belts or damping elements containing a thermoplastic polyurethane as previously described or a composition as previously described.

[0079] The following examples serve to illustrate the invention, but are in no way limiting with regard to the subject matter of the present invention. EXAMPLES 1. Raw materials:

[0080] Poly PTHF® < 1000: Polytetrahydrofuran 1000, CAS number: 25190-06-1, BASF SE, 67056 Ludwigshafen, GERMANY, Intermediates Division. 1,4-Butanediol: Butane-1,4-diol, CAS number: 110-63-4, BASF SE, 67056 Ludwigshafen, GERMANY, Intermediates Division. Lupranat MET: 4,4'-Methylenediphenyl diisocyanate, CAS number: 101-68-8, BASF SE, 67056 Ludwigshafen, GERMANY. Polyol A: Copolyesterdiol based on 1,4-butanediol, 1,6-hexanediol (ratio 2:1) and adipic acid, water content % (w / w) < 0.1, acid value [KOH mg / g] < 0.6, OH number [KOH mg / g] = 48-53. Capromer PD1-20 (PolyCLO NPG2000): Polycaprolactone, CAS number: 69089-45-8, water content % (w / w) < 0.1, acid value [KOH mg / g] < 0.25, OH number [KOH mg / g] = 54-58. Eternacoll PH-200D: Polycarbonate diol based on 1,6-hexanediol and 1,5-pentanediol in a 1:1 ratio, water content % (w / w) < 0.1, acid value [KOH mg / g] < 0.1, OH number [KOH mg / g] = 51-61; UBE Chemical Europe SA, 28016 Madrid, Spain.Irganox 1010:Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), CAS Number: 6683-19-8, BASF SE, 67056 Ludwigshafen, GERMANY. Irganox 1098: N,N'-Hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide], CAS number: 23128-74-7, BASF SE, 67056 Ludwigshafen, GERMANY. Elastostab H01: Hydrolysis inhibitor for polyester polyurethane, BASF Polyurethanes GmbH, 49440 Lemfoerde, GERMANY. Tin dioctoate: Catalyst metal 93690, tin bis(2-ethylhexanoate), CAS number: 301-10-0, BASF Polyurethanes GmbH, 49440 Lemfoerde, GERMANY. Melapur MC 15 ED: Melamine cyanurate (1,3,5-triazine-2,4,6(1H,3H,5H)-trione, compound with 1,3,5-Triazine-2,4,6-triamine (1 : 1)), CAS #: 37640-57-6, BASF SE, 67056 Ludwigshafen, GERMANY, Particle size D99% < / = 50 µm, D50%<= 4,5 µm, Wassergehalt % (w / w) < 0,2. Ultradur B4500 NAT:Polymer auf Basis: Polybutylenterephthalat (PBT), BASF SE, 67056 Ludwigshafen, GERMANY. . 2. Production using hand casting methods

[0081] The specified amount of polyol and chain extender, as defined in the underlying formula, is weighed into the tin can and briefly covered with nitrogen. The can is then sealed with a lid and heated to approximately 90°C in a heating cabinet.

[0082] Another heating cabinet for tempering the rind is preheated to 80 °C. The Teflon tray is placed on the heating table, which is then set to 125 °C.

[0083] The calculated quantity of liquid isocyanate is determined by volumetric measurement. For this, the liquid isocyanate (MDI is measured at a temperature of approximately 48 °C) is weighed into a PE beaker and poured into another PE beaker within 10 seconds. The emptied beaker is then tared and filled with the calculated quantity of isocyanate. In the case of MDI, this is stored in a heating cabinet at approximately 48 °C.

[0084] Additives such as hydrolysis protection, antioxidants, etc., which are present as solids at room temperature, are weighed in directly.

[0085] The preheated polyol is placed on a lifting platform under the stationary stirrer. The reaction vessel is then raised using the lifting platform until the stirring blades are completely immersed in the polyol.

[0086] Before switching on the mixing motor, ensure that the speed control is in the zero position. Then slowly increase the speed to ensure thorough mixing without incorporating air.

[0087] Then, additives such as antioxidants are added to the polyol.

[0088] The temperature of the reaction mixture is carefully adjusted to 80°C using a hot air gun.

[0089] If necessary, catalyst is dosed into the reaction mixture using a microliter syringe before the isocyanate is added. At 80 °C, the isocyanate is added by injecting the previously measured amount into the reaction mixture within 10 seconds. The weight is checked by weighing. Deviations greater or less than 0.2 g from the recipe quantity are documented. The stopwatch is started when the isocyanate is added. When the temperature reaches 110 °C, the reaction mixture is poured into the Teflon dishes, which have been preheated to 125 °C.

[0090] Ten minutes after the stopwatch starts, the rind is removed from the heating table and then stored in a heating cabinet at 80°C for 15 hours. The cooled rind is then shredded in a cutting mill. The granules are then dried at 110°C for 3 hours and stored in a dry place.

[0091] In principle, this process can be transferred to the reaction extruder or the belt process. 3. Reaction extruder process - Production as described in EP 1419188 B1

[0092] The TPU described below was produced on a Werner & Pfleiderer ZSK 58 twin-screw extruder. The extruder section was 12 housings long, with the housings themselves being four times the screw diameter. A gear pump discharged the screw from the extruder; granulation was carried out in a standard underwater pelletizing unit. The resulting granules were then dried in a fluidized bed dryer at temperatures between 60° and 100°C with residence times of 5 to 10 minutes to a moisture content of less than 0.03%, and subsequently tempered for 15 hours at 80°C.

[0093] The temperature of extruder housing 1 was 260°C, housings 2-4 290 to 250°C, housing 5 240°C, and housings 6-12, including the melt discharge device, 230°C. Under these conditions, at a throughput of approximately 200 kg / h and a rotational speed of 200 rpm, a melt temperature of 220-230°C was achieved.

[0094] A commercially available polybutylene terephthalate (Ultradur® < B 4500 / BASF Aktiengesellschaft) was used as the semi-crystalline, high-molecular-weight polyester, butanediol-1,4- was used as the low-molecular-weight diol for the degradation of the high-molecular-weight PBT, and 4,4'-diisocyanatodiphenylmethane (MDI) was used as the aromatic diisocyanate. The polydiols (PDOs) used are described and characterized in Table 1.

[0095] Ultradur® granules were continuously dosed into housing 1 of the twin-screw extruder, while butanediol-1,4, along with tin dioctoate as a catalyst to accelerate degradation, was added to housing 3. Polyol, MDI, and tin dioctoate were added to housing 5 of the twin-screw extruder. Stabilizers (Elastostab H01 and Irganox 1125) were added to housing 8 of the twin-screw extruder via laterally mounted dosing units. 4. Compounding

[0096] The mixtures were each produced using a Berstorff ZE 40 A twin-shaft extruder with a process section length of 35 D, divided into 10 housings. The flame retardant was added in Zone 5. Granulation was carried out in a standard underwater pelletizing unit. The resulting granules were then dried in a fluidized bed dryer at temperatures between 60° and 100°C with residence times of 5 to 10 minutes to a moisture content of < 0.03% and subsequently tempered for 15 hours at 80°C. 5. Formulations of TPU 1-7

[0097] Table 1 TPU 1 TPU 2 TPU 3 TPU 4 TPU 5 TPU 6 TPU 7 Manufacturing process Hand casting Hand casting Hand casting Extruder process Extruder process Extruder process Extruder process PTHF 1000 1000 1000 Polyol A 1000 1000 Capromer PD1-20 1000 Eternacoll PH-200D 1000 1000 Ultradur B4500 NAT 785,312 434,9 483,54 714,354 Lupranat MET 630 440 565 400,125 195,08 203,71 224,096 Butanediol-1,4 136,74 111,62 156,64 48,954 20,66 22,89 32,146

[0098] To all formulations, 0.5% Irganox 1010, 0.5% Irganox 1098, 1% Elastostab H01 and 200ppm tin dioctoate were added as a catalyst. 6. Formulations of flame-resistant TPU - Compound 1-4

[0099] Table 2 Compound 1 (comparative example) Compound 2 (comparative example) Compound 3 (comparative example) Compound 4 (according to the invention) Manufacturing process Compounding Compounding Compounding Compounding TPU 1 80 TPU 3 80 TPU 4 80 TPU 7 80 Melapur MC 15 ED 20 20 20 20 MFR [g / 10 min] DIN EN ISO 1133 190 °C 2.16 kg 17 32 21 61 7. Production of the test specimens

[0100] The granules were extruded into films with a thickness of 1.6 mm using a single-shaft extruder type Arenz with a three-zone screw and mixing section (screw ratio 1:3). 8. Determination of mechanical properties

[0101] The tensile strength or elongation at break (according to DIN 53504), the density (DIN EN ISO 1183-1, A), the tear strength (DIN ISO 34-1, B (b)), the abrasion (DIN 53516) and the Shore hardness A (according to DIN 53505) of the corresponding specimens were measured. Table 3 TPU 1 TPU 2 TPU 3 TPU 4 TPU 5 TPU 6 TPU 7 Density [g / cm3] 1,12 1,19 1,21 1,16 1,19 1,18 1,23 Shore A 87 87 91 91 85 85 92 ZF [MPa] 45 50 43 41 45 46 47 RD [%] 600 650 490 730 750 690 500 WRF [kN / m] 70 70 114 87 65 69 117 Abrasion [mm 3< ] 25 30 38 36 35 43 38 Table 4 Compound 1 (comparative example) Compound 2 (comparative example) Compound 3 (comparative example) Compound 4 (according to the invention) Standard mechanics Density [g / cm3] [g / cm3 ] 1,193 1,263 1,229 1,293 Shore A [A] 91 87 96 96 ZF [MPa] [MPa] 42 35 18 26 RD [%] [%] 540 550 600 510 WRF [kN / m] [kN / m] 65 78 73 102 Abrasion [mm 3< ] [mm3] 31 44 55 34 9. Determination of aging resistance and hydrolysis resistance

[0102] In connection with this invention, oxidative aging refers to the negative changes in the mechanical parameters of thermoplastic polyurethanes over time, such as tensile strength, elongation at break, tear strength, flexibility, impact strength, softness, etc.

[0103] To assess oxidative aging resistance, a test specimen is stored suspended in a convection oven at 150 °C for 3000 h, at 175 °C for 240 h, and at 200 °C for 6 h, and mechanical parameters are subsequently determined. The results are summarized in the following tables.

[0104] To assess hydrolysis resistance, a test specimen is stored at 85°C and 85% relative humidity for 3000 hours, and mechanical parameters are subsequently determined. The results are summarized in the tables below. Table 5 TPU 1 TPU 2 TPU 3 TPU 4 TPU 5 TPU 6 TPU 7 Hot air aging 200°C / 6h ZF [MPa] (Difference to 0h [%]) ** ** ** 20 (-51) ** ** 26 (-45) RD [%] (Difference to 0h [%]) ** ** ** 590 (-19) ** ** 670 (+34) Hot air aging 175°C / 240h ZF [MPa] (Difference to 0h [%]) [MPa] ** ** ** ** 18 (-60) 23 (-50) 27 (-43) RD[%] (Difference to 0h [%]) [%] ** ** ** ** 340 (-54) 460 (-33) 300 (-40) Hot air aging 150°C / 3000h ZF [MPa] (Difference to 0h [%]) [MPa] ** 9 (-82) 41 (-5) ** 17 (-62) 21 (-54) 20 (-58) RD[%] (Difference to 0h [%]) [%] ** 420 (-35) 190 (-61) ** 310 (-58) 250 (-74) 310 (-38) Moist heat 85 / 85 / 3000h ZF [MPa] (Difference to 0h [%]) [MPa] 31 (-31) ** 36 (-16) 21 (-49) ** ** 25 (-47) RD [%] (Difference to 0h [%]) [%] 470 (-22) ** 470 (-4) 770 (+5) ** ** 250 (-50) ** Sample destroyed

[0105] The TPU 7 according to the invention meets the requirements of temperature class D as well as the stricter regulations of LV 112 for hydrolysis resistance. Table 6 Compound 1 (comparative example) Compound 2 (comparative example) Compound 3 (comparative example) Compound 4 (according to the invention) Hot air aging 200°C / 6h ZF [MPa] (Difference to 0h [%]) [MP a] ** ** 8(-56) 14(-46) RD [%] (Difference to 0h [%]) [%] ** ** 130(-78) 490 (-4) Hot air aging 175°C / 240h ZF [MPa] (Difference to 0h [%]) [MP a] ** ** 11 (-39) 18(-31) RD [%] (Difference to 0h [%]) [%] ** ** 2(-100) 280(-45) Hot air aging 165°C / 1000h ZF [MPa] (Difference to 0h [%]) [MP a] ** ** ** 14(-46) RD [%] (Difference to 0h [%]) [%] ** ** ** 100(-80) Hot air aging 150°C / 3000h ZF [MPa] (Difference to 0h [%]) [MP a] ** ** ** 17(-35) RD [%] (Difference to 0h [%]) [%] ** ** ** 160(-69) Moist heat 85 / 85 / 3000h ZF [MPa] (Difference to 0h [%]) [MP a] 14(-67) 15(-57) 8(-56) 10(-62) RD [%] (Difference to 0h [%]) [%] 630(+17) 580(+5) 120(-80) 380(-25) ** Sample destroyed

[0106] The compound 4 according to the invention meets the requirements of temperature class D as well as the stricter regulations of LV 112 for hydrolysis resistance. Cited literature

[0107] "Plastics Handbook, Volume 7, Polyurethanes", Carl Hanser Verlag, 3rd edition 1993, Chapter 3.1 Plastics Handbook, Volume VII, edited by Vieweg and Höchtlen, Carl Hanser Verlag, Munich 1966 (pp. 103-113)

Claims

1. A thermoplastic polyurethane obtainable or obtained by a process comprising steps (i) and (ii): (i) reaction of a thermoplastic polyester (PE-1) with a diol (D1) to obtain a composition (Z1) comprising a polyester (PE-2), (ii) reaction of the composition (Z1) obtained in step (i) with an isocyanate composition (I1) comprising at least one polyisocyanate, and with a polyol composition (P1), where the polyol composition (P1) comprises at least one polycarbonate polyol (PC1), where the thermoplastic polyester (PE-1) has a molecular weight in the range from 15 000 g / mol to 70 000 g / mol and the polyester (PE-2) has a molecular weight in the range from 1000 g / mol to 6000 g / mol, and where the diol (D1) is butane-1,4-diol and the thermoplastic polyester (PE-1) is selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid.

2. The thermoplastic polyurethane according to claim 1, where the at least one polycarbonate polyol (PC1) is selected from the group consisting of polycarbonatediols based on butanediol and hexanediol, polycarbonatediols based on pentanediol and hexanediol, polycarbonatediols based on hexanediol, and mixtures of two or more of these polycarbonatediols.

3. The thermoplastic polyurethane according to claim 1 or 2, where the at least one polycarbonate polyol (PC1) has a number-average molecular weight Mn in the range from 500 to 4000, determined by GPC.

4. The thermoplastic polyurethane according to any of claims 1 to 3, where the polyisocyanate is selected from the group consisting of hexamethylene diisocyanate and diphenylmethane diisocyanate (MDI).

5. The thermoplastic polyurethane according to any of claims 1 to 4, where the thermoplastic polyurethane has a Shore hardness in the range from Shore 45 A to Shore 78 D.

6. A process for producing a thermoplastic polyurethane, comprising steps (i) and (ii): (i) reaction of a thermoplastic polyester (PE-1) with a diol (D1) to obtain a composition (Z1) comprising a polyester (PE-2), (ii) reaction of the composition (Z1) obtained in step (i) with an isocyanate composition (I1) comprising at least one polyisocyanate, and with a polyol composition (P1), where the polyol composition (P1) comprises at least one polycarbonate polyol (PC1), where the thermoplastic polyester (PE-1) has a molecular weight in the range from 15 000 g / mol to 70 000 g / mol and the polyester (PE-2) has a molecular weight in the range from 1000 g / mol to 6000 g / mol, and where the diol (D1) is butane-1,4-diol and the thermoplastic polyester (PE-1) is selected from the group consisting of polyalkylene terephthalates and poly-L-lactic acid.

7. A composition comprising at least components (A) and (B) (A) a thermoplastic polyurethane according to any of claims 1 to 5, (B) at least one flame retardant.

8. The composition according to claim 7, where the flame retardant is selected from the group consisting of metal hydroxides, nitrogen-containing flame retardants and phosphorus-containing flame retardants.

9. The composition according to either of claims 7 and 8, where the total content of the thermoplastic polyurethanes in the composition is in the range from 20% by weight to 80% by weight, based on the entire composition.

10. The use of a thermoplastic polyurethane according to any of claims 1 to 5 or of a composition according to any of claims 7 to 9 for the production of cable sheathing.

11. A film, molding, roller, fiber, automobile cladding, hose, cable plug, folding bellows, drag cable, cable sheathing, gasket, belt or damping element comprising a thermoplastic polyurethane according to any of claims 1 to 5 or a composition according to any of claims 7 to 9.