SKI BOOTS WITH TEMPERATURE-INDEPENDENT E-MODULE

Description

[0001] The present invention relates to the use of a thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol for the production of ski boots or parts of ski boots. Furthermore, the invention relates to ski boots, preferably ski boots, particularly preferably the outer shell of a ski boot, based on such a thermoplastic polyurethane and to processes for producing ski boots.

[0002] The production of ski boots, for example ski boots, in particular the outer, hard shells of ski boots by injection molding from thermoplastics is well known.

[0003] For example, WO 2007 / 118827A1 discloses ski boots based on thermoplastic polyurethane obtainable by reacting isocyanates with isocyanate-reactive compounds having a molecular weight (Mw) between 500 and 10,000 g / mol and chain extenders having a molecular weight between 50 and 499 g / mol, wherein the chain extender used is a mixture comprising a main chain extender and one or more co-chain extenders.

[0004] Thermoplastic polyurethanes, for example also obtained by reacting MDI and polyol compositions containing polytetrahydrofurans and chain extenders, are also disclosed, for example, in WO 2017 / 079188 A1, WO 2015 / 064140 A1, WO 2017 / 144502 A1 or WO 2006 / 029853 A1.

[0005] There is a need for ski boot development, especially to reduce the overall weight of the ski boot. This often involves reducing the wall thickness of the outer shell of the ski boot.

[0006] The requirements profile for thermoplastic polyurethane suitable for the production of such ski boots, especially their outer shell, is complex. Firstly, the material must have excellent low-temperature properties, meaning it should exhibit sufficient flexibility at the application temperatures and not break or splinter. Secondly, the material must be very rigid, so that sufficient stiffness of the ski boot can be achieved even with thin walls. It is also advantageous if the stiffness changes as little as possible over the temperature range of -30-20°C, as this ensures the ski boot's performance is temperature-independent.

[0007] The materials known from the prior art only inadequately meet these requirements. One of the underlying tasks of the present invention was therefore to develop thermoplastic polyurethanes for the production of ski boots that combine very high rigidity with excellent low-temperature properties.

[0008] According to the invention, this object is achieved by a method for producing a ski boot or a part of a ski boot, comprising the steps (i) Providing a thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol; (ii) producing a ski boot or a part of a ski boot from the thermoplastic polyurethane (TPU-1), wherein the thermoplastic polyurethane has a hard phase content of greater than 0.40, wherein the hard phase content is defined by the following formula: Hard phase proportion=∑x=1xmKVx / MKVx*MIso+mKVx / mtot with the following meanings: M KVx :Molar mass of the chain extender x in g / mol m KVx :Mass of the chain extender x in g M Iso :Molar mass of the isocyanate used in g / mol m ges :Total mass of all starting materials in gx:Number of chain extenders.

[0009] Surprisingly, it was discovered that the combination of the isocyanate component and the polyol component used results in thermoplastic polyurethanes with a property profile that is particularly suitable for the production of ski boots. The thermoplastic polyurethanes exhibit good low-temperature properties and typically have an elastic modulus greater than 200 MPa.

[0010] According to the invention, the isocyanate composition (IZ) containing MDI is reacted with a polyol composition (PZ) containing at least one polyol (P1) and a chain extender (KV1). Within the scope of the present invention, the polyol composition (PZ) may contain further polyols or further chain extenders. The isocyanate composition (IZ) may also contain other isocyanates in addition to MDI.

[0011] Thermoplastic polyurethanes are generally known. They are typically produced by reacting isocyanates and isocyanate-reactive compounds, and optionally chain extenders, optionally in the presence of at least one catalyst and / or conventional auxiliaries and / or additives. Isocyanates, isocyanate-reactive compounds, and chain extenders are also referred to individually or together as building blocks.

[0012] According to the invention, the polyol component contains at least the polyol (P1) as an isocyanate-reactive compound. In the context of the present invention, the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol, more preferably from polytetrahydrofurans having an average molecular weight Mn in the range from 1400 to 1600 g / mol, for example in the range from 1400 to 1500 g / mol.

[0013] Surprisingly, it has been found that the compositions according to the invention have sufficient hardness, particularly for use in the production of ski boots, and can be easily colored despite the molecular weight of the polyols used.

[0014] However, within the scope of the present invention, the polyol component may also contain other compounds that are reactive towards isocyanates.

[0015] In principle, any suitable compounds known to those skilled in the art can be used as further isocyanate-reactive compounds. All suitable diols, for example other polyether diols, can be used within the scope of the present invention.

[0016] The chain extender (KV1) in the context of the present invention is selected from the group consisting of 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. According to the invention, two or more chain extenders can also be used, for example mixtures of 1,4-butanediol and another chain extender. Preferably, only one chain extender (KV1) is used in the context of the present invention.

[0017] In the context of the present invention, 1,4-butanediol is preferably used as a chain extender. According to a further embodiment, the present invention therefore relates to a thermoplastic polyurethane as described above, wherein the chain extender (KV1) is 1,4-butanediol.

[0018] In the context of the present invention, the isocyanate composition (IZ) containing MDI is used in the production of the thermoplastic polyurethane (TPU-1).

[0019] According to the invention, 2,2'-, 2,4'-, and / or 4,4'-diphenylmethane diisocyanate (MDI) can be used. Particular preference is given to using only 4,4'-MDI.

[0020] According to a further embodiment, the present invention therefore relates to a composition as described above, wherein the thermoplastic polyurethane is based on 4,4'-diphenylmethane diisocyanate.

[0021] The thermoplastic polyurethane of the ski boot according to the invention has a hard phase fraction of greater than 0.4, particularly preferably greater than 0.5. Accordingly, the present invention relates to a process as described above, wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hartphasenanteil = ∑ x = 1 x m KVx / M KVx * M Iso + m KVx / m ges with the following meanings: M KVx : Molar mass of the chain extender x in g / mol m KVx : Mass of the chain extender x in g M Iso : Molar mass of the isocyanate used in g / mol m ges : Total mass of all starting materials in gx: Number of chain extenders.

[0022] The thermoplastic polyurethanes used according to the invention preferably have a modulus of elasticity in the range from 400 to 1100 MPa, more preferably in the range from 800 to 1050 MPa, particularly preferably in the range from 900 to 1000 MPa.

[0023] The thermoplastic polyurethanes used in the invention exhibit good low-temperature properties. These can be characterized, for example, by the Charpy notched impact strength at -30°C.

[0024] According to another embodiment, the present invention also relates to a ski boot or part of a ski boot, wherein the thermoplastic polyurethane (TPU-1) has a Charpy notched impact strength at -30°C according to DIN EN ISO 179-1 / 1 eA of greater than 10 kJ / m 2<, preferably greater than 20 kJ / m 2<, more preferably greater than 30 kJ / m 2<. For example, within the scope of the present invention, the thermoplastic polyurethane can have an E-modulus of 400 MPa and a notched impact strength at -30°C in the range of 100 kJ / m 2<, or with an E-modulus of 1000 MPa, a notched impact strength at -30°C of approximately 35 kJ / m 2<. It is also possible within the scope of the present invention for the thermoplastic polyurethane to have an elastic modulus of 1000MPa and a notched impact strength of 10-20kJ / m 2<.

[0025] To adjust the hardness of TPUs, the components can be varied within a relatively wide molar ratio. For example, molar ratios of polyols to total chain extender used of 1:1 to 1:15, preferably 1:4 to 1:12, in particular 1:5 to 1:10, and more preferably 1:5 to 1:8 have proven effective, with the hardness of the TPU increasing with increasing chain extender content.

[0026] The reaction can take place at customary indexes, preferably at an index between 950 and 1050, particularly preferably at an index between 970 and 1010, in particular between 980 and 1000, further preferably in the range from 992 to 998. The index is defined by the ratio of the total isocyanate groups used in the reaction to the groups reactive towards isocyanates, i.e. the active hydrogens. With an index of 1000, there is one active hydrogen atom for each isocyanate group, i.e. one function reactive towards isocyanates. With indexes above 1000, there are more isocyanate groups than OH groups. The TPU can be produced using known processes continuously, for example using reaction extruders or the one-shot belt process or the prepolymer process, or discontinuously using the known prepolymer process.In these processes, the reacting components can be mixed together sequentially or simultaneously, with the reaction starting immediately. In the extruder process, the components, as well as any catalysts and / or other auxiliaries and additives, are introduced into the extruder individually or as a mixture, e.g., at temperatures of 100 to 280°C, preferably 140 to 250°C, to react. The resulting TPU is extruded, cooled, and granulated.

[0027] Catalysts and auxiliaries or additives used for the production of thermoplastic polyurethanes are known per se to the person skilled in the art.

[0028] Catalysts which particularly accelerate the reaction between the NCO groups of the diisocyanates and the hydroxyl groups of the isocyanate-reactive compound and the chain extender are, in a preferred embodiment, 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 titanic acid 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 the oxidation states 2 or 3, in particular 3. Salts of carboxylic acids are preferred.Carboxylic acids with 6 to 14 carbon atoms are preferred, particularly preferably with 8 to 12 carbon atoms. Examples of suitable bismuth salts are bismuth(III) neodecanoate, bismuth 2-ethylhexanoate, and bismuth octanoate.

[0029] The catalysts are preferably used in amounts of 0.0001 to 0.1 part by weight per 100 parts by weight of the isocyanate-reactive compound. Tin catalysts, especially tin dioctoate, are preferred.

[0030] In addition to catalysts, conventional additives can also be used. These include, for example, surfactants, fillers, other flame retardants, nucleating agents, oxidation stabilizers, lubricants and demolding aids, dyes and pigments, optionally stabilizers (e.g., to protect against hydrolysis, light, heat, or discoloration), inorganic and / or organic fillers, reinforcing agents, and plasticizers. Suitable additives and auxiliaries can be found, for example, in the Kunststoffhandbuch (Plastics Handbook), Volume VII, published by Vieweg and Höchtlen, Carl Hanser Verlag, Munich 1966 (pp. 103-113).

[0031] Suitable production processes for thermoplastic polyurethanes are disclosed, for example, in EP 0 922 552 A1, DE 101 03 424 A1 or WO 2006 / 072461 A1. Production is usually carried out on a belt system or a reaction extruder, but can also be carried out on a laboratory scale, for example using the hand-casting process. Depending on the material properties of the components, these are all mixed together directly or individual components are premixed and / or pre-reacted, e.g. to form prepolymers, and only then is the polyaddition process carried out. In a further embodiment, a thermoplastic polyurethane is first produced from the components, optionally with a catalyst, into which auxiliary substances may also be incorporated. Homogeneous distribution is preferably carried out in an extruder, more preferably in a twin-screw extruder.

[0032] To produce the thermoplastic polyurethanes used according to the invention, the building components are preferably reacted in the presence of catalysts and optionally auxiliaries and / or additives, usually in amounts such that the equivalence ratio of NCO groups of the diisocyanates to the sum of the hydroxyl groups of the components used is 0.95 to 1.05:1, preferably 0.98 to 1.00:1, more preferably 0.992 to 0.998:1.

[0033] According to the invention, thermoplastic polyurethanes are preferably produced in which the thermoplastic polyurethane has an average molecular weight (MW) in the range from 50,000 to 200,000 Daltons, preferably in the range from 80,000 to 120,000 Daltons. The upper limit for the average molecular weight (MW) of the thermoplastic polyurethanes is generally determined by the processability and the desired range of properties.

[0034] It has surprisingly been found that the compositions used according to the invention, thanks to the combination of the components according to the invention, exhibit an optimized property profile, particularly for use in the production of ski boots or ski boot parts. In particular, it has surprisingly been found that the modulus of elasticity changes little over temperature. This is advantageous because the ski boots then exhibit the same stiffness at different temperatures.

[0035] The present invention relates to a method for producing a ski boot or a part of a ski boot, comprising the steps (i) Providing a thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1200 to 2000 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol; (ii) Producing a ski boot or a part of a ski boot from the thermoplastic polyurethane (TPU-1), wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hartphasenanteil = ∑ x = 1 x m KVx / M KVx * M Iso + m KVx / m ges with the following meanings: M KVx :Molar mass of the chain extender x in g / mol m KVx :Mass of the chain extender x in g M Iso :Molar mass of the isocyanate used in g / mol m ges :Total mass of all starting materials in gx:Number of chain extenders.

[0036] The production according to step (ii) can be carried out using conventional methods, preferably by injection molding. Accordingly, according to a further embodiment, the present invention also relates to a process as described above, wherein the thermoplastic polyurethane (TPU-1) according to step (ii) is processed by injection molding.

[0037] Furthermore, the present invention also relates to the use of a thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), for the production of ski boots or parts of ski boots, wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1200 to 2000 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol, wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hartphasenanteil = ∑ x = 1 x m KVx / M KVx * M Iso + m KVx / m ges with the following meanings: M KVx :Molar mass of the chain extender x in g / mol m KVx :Mass of the chain extender x in g M Iso :Molar mass of the isocyanate used in g / mol m ges :Total mass of all starting materials in gx:Number of chain extenders...

[0038] With regard to the preferred embodiments, reference is made to the above statements regarding the components preferably used.

[0039] The invention further relates to ski boots, preferably ski boots, particularly preferably the outer shell of a ski boot, based on the thermoplastic polyurethane described above. Furthermore, the invention relates to processes for producing ski boots, preferably ski boots, particularly preferably the outer shell of a ski boot, wherein the thermoplastic polyurethane according to the invention is processed by injection molding to form the ski boot, preferably ski boots, particularly preferably the outer shell of a ski boot. The thermoplastic polyurethanes according to the invention are used for producing ski boots, preferably ski boots, in particular outer shells of ski boots, ski boot heels, cuffs for the ski boot shaft, and decorative elements. The production of these products by conventional injection molding processes is generally known.

[0040] Accordingly, according to a further aspect, the present invention also relates to a ski boot or part of a ski boot obtained or obtainable according to a method as described above. According to preferred embodiments, reference is made to the above statements.

[0041] Further embodiments of the present invention can be found in the claims and the examples. It is understood that the features of the inventive subject matter / method or uses mentioned above and explained below can be used not only in the respective combinations specified, but also in other combinations without departing from the scope of the invention. For example, the combination of a preferred feature with a particularly preferred feature, or of a feature not further characterized with a particularly preferred feature, etc., is implicitly encompassed, even if this combination is not explicitly mentioned.

[0042] 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. Example 1 - Raw materials

[0043] Poly PTHF ®< 1000: Polytetrahydrofuran 1000, CAS number: 25190-06-1, BASF SE, 67056 Ludwigshafen, GERMANY, Business Division Intermediates. Poly PTHF ®< 2000: Polytetrahydrofuran 2000, CAS number: 25190-06-1, BASF SE, 67056 Ludwigshafen, GERMANY, Business Division Intermediates. 1,4-Butanediol: Butane-1,4-diol, CAS number: 110-63-4, BASF SE, 67056 Ludwigshafen, GERMANY, Business Division Intermediates. Lupranat MET: 4,4'-Methylenediphenyl diisocyanate, CAS number: 101-68-8, BASF SE, 67056 Ludwigshafen, GERMANY Color masterbatch 1: Elastollan Konz 315 F (Red), BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemförde Color masterbatch 2: Elastollan Konz 530 / 1 (Blue), BASF Polyurethanes GmbH, Elastogranstrasse 60, 49448 Lemförde 2. Example 2 - Production of materials

[0044] The materials AN were produced using a twin-screw extruder type ZSK 58 from Werner and Pfleiderer Stuttgart with a process section length of 48 D, divided into 12 barrels. Granulation was carried out using a standard underwater granulator from Gala (UWG). The formulations of the individual materials are summarized in Table 1.

[0045] TPU materials with average molecular weights of the polyol component greater than 2000 Dalton could not be produced. 3. Determination of properties

[0046] The mechanical properties were determined on injection molded specimens. Density was determined according to DIN EN ISO 1183-1 (A), hardness according to DIN 53505, tensile strength, elongation at break, and elastic modulus according to DIN EN ISO 527, tear strength according to DIN ISO 34-1, B (b), notched impact strength according to DIN EN ISO 179-1 / 1eA, and abrasion according to DIN 53516.

[0047] The properties of the individual materials are summarized in Table 1. 4. Notched impact strengths at low temperatures.

[0048] The inventive examples (EB) in Table 1 illustrate that using a PTHF with average molecular weights in the range of 1400-1700, materials with high impact strength at low temperatures are obtained. Materials with approximately the same stiffness at 20°C were compared.

[0049] For example, for the material J according to the invention, a notched impact strength of 117 kJ / m 2< is measured at -30°C, while for the non-inventive material K, a notched impact strength of 8 kJ / m 2< is determined at -30°C.

[0050] Analogously, for example, the inventive materials A and E can be compared with the non-inventive material D. For material A, a notched impact strength of 120 kJ / m 2< is measured at -30°C, while for the non-inventive material D, a notched impact strength of 9 kJ / m 2< is determined at -30°C. For material A, a notched impact strength of 110 kJ / m 2< is measured at -20°C, while for the non-inventive material D, a notched impact strength of 15 kJ / m 2< is determined at -20°C.

[0051] Furthermore, Examples D to I, all with a hard phase content of 53%, show that the notched impact strength at -30°C for the inventive materials (EI) with average molecular weights for PTHF in the range of 1400-1700 are always above 20 kJ / m 2 . Despite a much lower Young's modulus at 20°C, the non-inventive Example D has notched impact strengths at -30°C significantly below 20 kJ / m 2 . 5. Stiffening at low temperatures

[0052] The inventive examples (EB) in Table 1 illustrate that when using a PTHF with average molecular weights in the range of 1400-1700, materials are obtained whose stiffness (Young's modulus) increases only moderately at low temperatures. Materials with approximately the same stiffness at 20°C were compared.

[0053] For example, for the material J according to the invention, an increase in the elastic modulus to 180% is recorded from 20°C to -30°C, while for the non-inventive material K, an increase to 340% is determined.

[0054] Analogously, for example, the inventive material A can be compared with the non-inventive material D. For the inventive material A, an increase in the elastic modulus of 260% is found from 20°C to -30°C, while for the non-inventive material D, an increase in the elastic modulus of 660% is determined. Table 1a: Recipes and properties of the materials AG material A B C D E F G EB-inventive example / VB-comparative example EB EB EB VB EB EB EB HS share [%] 47 49 51 53 53 53 53 Average molecular weight PTHF [Dalton] 1700 1700 1700 1000 1200 1400 1500 Poly THF 2000 OH: 56.1 [g] 37,64 36,16 34,76 0 12,83 22,52 26,54 PolyTHF 1000 OH:112.2 [g] 8,06 7,74 7,44 37,09 25,58 16,85 13,24 Lupranat MET [g] 40,9 42,15 43,34 47,94 46,62 45,64 45,23 Butanediol, 1.4 [g] 12,31 12,85 13,37 13,87 13,87 13,89 13,89 Density [g / cm3] 1,14 1,14 1,15 1,17 1,16 1,16 1,16 Hardness [Shore D] 53 54 57 59 59 60 60 Tensile strength [MPa] 37 42 43 57 42 49 41 Elongation at break [%] 370 370 380 430 360 370 330 Tear strength [kN / m] 96 107 114 171 176 171 168 Abrasion [mm 3< ] 40 40 43 32 51 58 50 Young's modulus at 20°C [MPa] 281 382 435 205 353 528 591 Young's modulus at 0°C [MPa] 395 514 587 438 556 870 807 Young's modulus at -10°C [MPa] 477 586 680 608 758 954 902 Young's modulus at -20°C [MPa] 571 712 809 922 1169 1191 1134 Young's modulus at -30°C [MPa] 736 885 1064 1345 1301 1334 1260 Percentage increase in elastic modulus from room temperature to -30°C. 262 231 244 656 368 253 213 Charpy notched impact strength at -10°C [kJ / m 2 ] 107 104 102 175 139 117 114 Charpy notched impact strength at -20°C [kJ / m 2 ] 110 112 114 15 122 118 116 Charpy notched impact strength at -30°C [kJ / m 2 ] 120 120 124 9 25 113 121 Colorability with 2% color masterbatch 1 (*) 3 3 3 1 1 1 2 Dyeability with 2% 3 3 3 1 1 1 2 Color masterbatch 2 (*) nd - not determined Table 1b: Recipes and properties of the materials HN material H I J K L M N EB-inventive example / VB-comparative example EB EB EB VB EB EB EB HS share [%] 53 53 57 60,5 62,5 72 60,5 Average molecular weight PTHF [Dalton] 1600 1700 1700 1000 1700 1700 1400 Poly THF 2000 OH: 56.1 [g] 30,13 33,34 30,54 0 26,63 19,83 18,93 PolyTHF 1000 OH:112.2 [g] 10,05 7,14 6,54 31,38 5,7 4,24 14,2 Lupranat MET [g] 44,84 44,53 46,9 52,25 50,2 55,95 49,92 Butanediol, 1.4 [g] 13,88 13,89 14,92 15,99 16,37 18,88 15,85 Density [g / cm3] 1,15 1,15 1,16 1,20 1,18 1,20 and Hardness [Shore D] 58 57 62 75 66 74 and Tensile strength [MPa] 42 43 43 65 44 51 and Elongation at break [%] 330 360 310 380 260 180 and Tear strength [kN / m] 168 126 155 220 183 238 and Abrasion [mm 3< ] 48 47 52 22 75 113 and Young's modulus at 20°C [MPa] 550 561 803 774 1101 1597 and Young's modulus at 0°C [MPa] 731 700 943 1370 1354 2000 and Young's modulus at -10°C [MPa] 783 816 1043 1841 1431 2256 and Young's modulus at -20°C [MPa] 940 927 1170 2171 1606 2525 and Young's modulus at -30°C [MPa] 1137 1286 1439 2642 1980 2835 and Percentage increase in the elastic modulus from room temperature to -30°C 206 229 179 341 179 178 and Charpy notched impact strength at -10°C [kJ / m 2 ] 105 105 114 9 91 and and Charpy notched impact strength at -20°C [kJ / m 2 ] 107 118 122 9 82 and and Charpy notched impact strength at -30°C [kJ / m 2 ] 119 123 117 8 31 and and Colorability with 2% color masterbatch 1 3 3 5 1 5 5 1 Colorability with 2% color masterbatch 2 3 3 5 1 5 5 1 nd - not determined (*) Assessment of colorability: 1 - very good 2 - good 3 - satisfactory 4 - sufficient 5 - poor Cited literature

[0055] WO 2007 / 118827A1 Kunststoffhandbuch, Volume VII, edited by Vieweg and Höchtlen, Carl Hanser Verlag, Munich 1966 (pp. 103-113) EP 0 922 552 A1 DE 101 03 424 A1 WO 2006 / 072461 A1

Claims

1. A process for producing a ski boot or part of a ski boot, comprising the steps of (i) providing a thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol; (ii) producing a ski boot or part of a ski boot from the thermoplastic polyurethane (TPU-1), wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hard phase fraction = ∑ x = 1 x m KVx / M KVx ∗ M iso + m KVx / m tot with the following definitions: MKVx: Molar mass of the chain extender x in g / mol mKVx: Mass of the chain extender x in g Miso: Molar mass of the employed isocyanate in g / mol mtot: Total mass of all starting materials in g x: Number of chain extenders.

2. The process as claimed in claim 1, wherein the thermoplastic polyurethane (TPU-1) is processed by injection molding according to step (ii).

3. The process as claimed in either of claims 1 and 2, wherein the chain extender (KV1) is 1,4-butanediol.

4. A ski boot or part of a ski boot obtained or obtainable by a process as claimed in any of claims 1 to 3.

5. The ski boot or part of a ski boot as claimed in claim 4, wherein the thermoplastic polyurethane has a Charpy notched impact strength at -30°C according to DIN EN ISO 179-1 / 1 eA of greater than 10 kJ / m2.

6. The use of a thermoplastic polyurethane (TPU-1) obtained or obtainable by reaction of an isocyanate composition (IZ) containing MDI with a polyol composition (PZ) for production of ski boots or parts of ski boots, wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol, and wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hard phase fraction = ∑ x = 1 x m KVx / M KVx ∗ M iso + m KVx / m tot with the following definitions: MKVx: Molar mass of the chain extender x in g / mol mKVx: Mass of the chain extender x in g Miso: Molar mass of the employed isocyanate in g / mol mtot: Total mass of all starting materials in g x: Number of chain extenders.

7. The use as claimed in claim 6, wherein the chain extender (KV1) is 1,4-butanediol.

8. A thermoplastic polyurethane (TPU-1) obtained or obtainable by reacting an isocyanate composition (IZ) containing MDI with a polyol composition (PZ), wherein the polyol composition (PZ) contains at least one polyol (P1) and a chain extender (KV1), wherein the polyol (P1) is selected from polytetrahydrofurans having an average molecular weight Mn in the range from 1300 to 1700 g / mol and the chain extender (KV1) is selected from the group consisting of 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol, wherein the thermoplastic polyurethane has a hard phase fraction of greater than 0.40, wherein the hard phase fraction is defined by the following formula: Hard phase fraction = ∑ x = 1 x m KVx / M KVx ∗ M iso + m KVx / m tot with the following definitions: MKVx: Molar mass of the chain extender x in g / mol mKVx: Mass of the chain extender x in g Miso: Molar mass of the employed isocyanate in g / mol mtot: Total mass of all starting materials in g x: Number of chain extenders.

9. The thermoplastic polyurethane as claimed in claim 8, wherein the chain extender (KV1) is 1,4-butanediol.