The present invention relates to a thermoplastic polyurethane obtainable or obtained by reaction of at least one polyisocyanate, at least one chain extender, and at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on an aliphatic dicarboxylic acid (A1 ) and a compound (B1 ) selected from the group consisting of compounds of the general formula (I), compounds of the general formula (II) and compounds of the general formula (III). The present invention further relates to a process for producing such thermoplastic polyurethanes, and to the use of such polyurethanes for production of injection molded products, extrusion products, films and moldings.

Thermoplastic polyurethanes for various applications are known in principle from the prior art. By the variation of the feedstocks, it is possible to obtain different profiles of properties.

For example, WO 2006/082183 A1 discloses a process for continuously preparing thermoplas- tically processible polyurethane elastomers, in which a polyisocyanate, a compound having Zerevitinoff-active hydrogen atoms with a mean molecular weight of 450 g/mol to 5000 g/mol, a chain extender and further auxiliaries and additives are converted. This achieves specific pro- files of properties via specific processing.

EP 0 922 552 A1 also discloses a process for continuously producing pellets from thermoplastic polyurethane elastomers, wherein a pelletized material is first produced by reaction of organic diisocyanates, difunctional polyhydroxyl compounds having molecular weights of 500 to 8000 and difunctional chain extenders having molecular weights of 60 to 400 in the presence of catalysts and optionally auxiliaries and/or additives. Use for production of extruded, injection molded or calendered material, especially of cable sheathing, hoses and/or films, is likewise disclosed.

WO 98/56845 A1 discloses a thermoplastic polymer which is obtained by reaction of a polyiso- cyanate, a glycol as chain extender and a polyether polyol. Various isocyanates, chain extenders and polyols are disclosed.

Depending on the type of application, the properties of the thermoplastic polyurethane can be varied via the type of feedstocks and the quantitative ratios used. For example, for use as a hose material, a high burst pressure even at elevated temperatures is necessary. It is for example possible to influence stability by variation of the polyol component. It is also possible to influence stability via the processing, for example by heat treatment.

TPU tubes with improved gas barrier property are of great importance for applications such as bicycle tires. TPU tubes according to the state of the art do not show sufficient properties and the tubes have to be too thick. Therefore, an object of the present invention was to provide thermoplastic polyurethanes for the preparation of films or tubes which have good gas barrier properties and good mechanical properties. According to the invention, this object is achieved by a thermoplastic polyurethane obtainable or obtained by reaction of at least the components (i) to (iii): (i) at least one polyisocyanate;

(ii) at least one chain extender; and

(iii) at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on an aliphatic dicarboxylic acid (A1 ) and a com- pound (B1 ) selected from the group consisting of compounds of the general formula (I), compounds of the general formula (II) and compounds of the general formula (III):

X(R1 )2n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH;

Y(R1 ) _n (II) wherein

Y is an aromatic ring with 6 carbon atoms with n being 6, and each R1 is independently selected from the group consisting of -

CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH;

Z(R1 ) _n -i (III) wherein Z is an n-membered aromatic ring with n-1 carbon atoms and 1 heteroa- tom selected from nitrogen and oxygen with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH. It was surprisingly found that using the thermoplastic polyurethanes according to the present invention, films and tubes with good mechanical properties and improved gas barrier properties could be obtained. The gas barrier properties were for example tested with respect to N2, O2, According to the invention, the thermoplastic polyurethane is obtained or obtainable by reaction of at least one polyisocyanate, at least one chain extender, and at least one polyol composition comprising a polyesterpolyol (P1 ). In the context of the present invention, the polyol composition used comprises at least one polyesterpolyol (P1 ) which is based on an aliphatic dicarboxylic acid (A1 ) and a compound (B1 ).

In the context of the present invention, any aliphatic dicarboxylic acid can be used, for example an aliphatic dicarboxylic acid with 2 to 14 C-atoms, preferably an aliphatic dicarboxylic acid with 2 to 12 C-atoms, more preferable an aliphatic dicarboxylic acid with 2 to 8 C-atoms. According to the present invention, also mixtures of aliphatic dicarboxylic acids can be used. Preferably, the aliphatic dicarboxylaic acid is selected from the group consisting of succinic acid and adipic acid.

Therefore, according to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the aliphatic dicarboxylic acid (A1 ) is adipic acid.

Compound (B1 ) is selected from the group consisting of compounds of the general formula (I), compounds of the general formula (II) and compounds of the general formula (III):

X(R1 )2n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH;

Y(R1 ) (II) wherein Y is an aromatic ring with 6 carbon atoms with n being 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH;

Z(R1 ) _n -i (III) wherein

Z is an n-membered aromatic ring with n-1 carbon atoms and 1 heteroa- torn selected from nitrogen and oxygen with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH.

(B1 ) is selected from compounds of the general formula (I), (II), and (III) and according to the present invention, also mixtures of two or more compounds can be used. Preferably, compound (B1 ) is selected from compounds of the general formula (I),: X( 1 ) ₂ n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH. According to a further embodiment, compound (B1 ) is selected from compounds of the general formula (I) wherein X is a cycloalkyl ring with n being 6, i.e. a cyclohexyl ring. More preferably, compound (B1 ) is selected from the group consisting of cyclohexyl derivatives with 2, 3, 4, 5, or 6 residues attached to the cyclohexyl ring. Therefore, according to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the compound (B1 ) is cyclohexanedi- methanol. According to the invention, the polyol composition may comprise further polyols. Polyols are known in principle to those skilled in the art and are described, for example, in "Kunststoffhand- buch, Band 7, Polyurethane" [Plastics Handbook, Volume 7, Polyurethanes], Carl Hanser Ver- lag, 3rd edition 1993, chapter 3.1 . Particular preference is given to using polyesterols or poly- etherols as polyols. It is likewise possible to use polycarbonates. Copolymers may also be used in the context of the present invention. The number-average molecular weight of the polyols used in accordance with the invention is preferably between 0.5 x 10 ³ g/mol and 8 x 10 ³ g/mol, preferably between 0.6 x 10 ³ g/mol and 5 x 10 ³ g/mol, especially between 0.8 x 10 ³ g/mol and 3 x 10 ³ g/mol.

Polyethers are suitable in accordance with the invention, but also polyesters, block copolymers and hybrid polyols, for example poly(ester/amide). Preferred polyetherols in accordance with the invention are polyethylene glycols, polypropylene glycols, polyadipates, polycarbonate(diol)s and polycaprolactone.

In a further embodiment, the present invention accordingly relates to a thermoplastic polyurethane as described above, wherein the polyol composition used comprises at least one polytet- rahydrofuran and at least one polyol selected from the group consisting of polyethylene glycol, polypropylene glycol, polyadipates, polycarbonate(diol)s and polycaprolactones.

In a particularly preferred embodiment, the polyol used has a molecular weight Mn in the range from 500 g/mol to 4000 g/mol, preferably in the range from 800 g/mol to 3000 g/mol.

The present invention accordingly relates, in a further embodiment, to a thermoplastic polyure- thane as described above, wherein at least one polyol present in the polyol composition has a molecular weight Mn in the range from 500 g/mol to 4000 g/mol.

According to the invention, it is also possible to use mixtures of different polyols. Preferably, the polyols used and the polyol composition have a mean functionality between 1 .8 and 2.3, prefer- ably between 1 .9 and 2.2, especially 2. Preferably, the polyols used in accordance with the invention have only primary hydroxyl groups.

According to the invention, for example, further polyethers are suitable, but also polyesters, block copolymers and hybrid polyols, for example poly(ester/amide). Preferred polyetherols in accordance with the invention are polyethylene glycols, polypropylene glycols and polycaprolactone.

In a further embodiment, the present invention accordingly relates to a thermoplastic polyurethane as described above, wherein the polyol composition comprises at least one polytetrahy- drofuran and at least one further polyol selected from the group consisting of polyethylene glycol, polypropylene glycol and polycaprolactone. Therefore, according to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the polyol composition comprises at least one further polyesterol. In the context of the present invention, composition of the polyol composition may vary within wide ranges. For example, the content of polyesterpolyol (B1 ) may be in the range from 15% to 85%, preferably in the range from 20% to 80%, further preferably in the range from 25% to 75%, in each case based on the sum of all components of the polyol composition. According to the invention, the polyol composition may also comprise a solvent. Suitable solvents are known per se to those skilled in the art.

According to the invention, at least one chain extender is used. The chain extender can be used alone or a mixture of two or more chain extenders can be used according to the present inven- tion.

Suitable chain extenders are, for example, compounds having at least two functional groups reactive toward isocyanates, for example hydroxyl groups, amino groups or thiol groups. In a further embodiment, the present invention accordingly relates to a thermoplastic polyurethane as described above, wherein at least one chain extender selected from the group consisting of compounds having at least two functional groups reactive toward isocyanates is used.

Chain extenders used in the context of the present invention may, for example, be compounds having hydroxyl or amino groups, especially having two hydroxyl or amino groups. According to the invention, the mean functionality of the mixture of chain extenders used is preferably two.

Preferably in accordance with the invention, chain extenders used are compounds having hydroxyl groups, especially diols. Diols used with preference may be aliphatic, araliphatic, aromatic and/or cycloaliphatic diols having a molecular weight of 50 g/mol to 220 g/mol. Preference is given to alkanediols having 2 to 10 carbon atoms in the alkylene radical, especially di-, tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and/or decaalkylene glycols. For the present invention, particular preference is given to 1 ,2-ethylene glycol, propane-1 ,3-diol, butane-1 ,4-diol, hexane-1 ,6-diol. It is also possible to use aromatic compounds such as hydroxyquinone bis(2- hydroxyethyl) ether.

According to the invention, it is also possible to use compounds having amino groups, for example diamines. It is likewise possible to use mixtures of diols and diamines.

Preferably, the chain extender is a diol having a molecular weight Mw < 220 g/mol.

In one embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein at least one chain extender selected from the group consisting of aliphatic and aromatic diols, diamines and amino alcohols is used. In a further embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein at least one chain extender selected from the group consisting of mo- noethylene glycol, aminopropanol, propane-1 ,3-diol, butane-1 ,4-diol, hexane-1 ,6-diol and hy- droxyquinone bis(2-hydroxyethyl) ether (HQEE).

According to the invention, preferably the chain extender is selected from diamines or diols having a molecular weight Mw < 220 g/mol. More preferable, the chain extender is selected from the group consisting of 1 ,3-propane diol, 1 ,4-butane diol, and 1 ,6-hexanediol. Mixtures of these can also be used according to the present invention.

Therefore, according to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the chain extender is a diol with a molecular weight Mw < 220 g/mol. According to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the chain extender is selected from the group consisting of 1 ,3-propane diol, 1 ,4-butane diol, and 1 ,6-hexanediol.

In the context of the present invention, the amount of the chain extender and of the polyol composition used may vary within wide ranges. For example, component (iii) and component (ii) are used in a molar ratio of (iii):(ii) of 1 :0.7, 1 :2.7 and 1 :7.3.

According to the invention, a polyisocyanate composition is used for preparation of the thermoplastic polyurethane. The polyisocyanate composition comprises at least one polyisocyanate. According to the invention, the polyisocyanate composition may also comprise two or more polyisocyanates.

Preferred polyisocyanates in the context of the present invention are diisocyanates, especially aliphatic or aromatic diisocyanates, further preferably aromatic diisocyanates. Therefore, according to a further embodiment, the present invention is also directed to the thermoplastic polyurethane as disclosed above, wherein the polyisocyanate is an aromatic diisocyanate.

In addition, in the context of the present invention, it is possible to use prereacted prepolymers as isocyanate components, in which some of the OH components have been reacted with an isocyanate in a preceding reaction step. These prepolymers are reacted with the remaining OH components in a subsequent step, the actual polymer reaction, and then form the thermoplastic polyurethane. The use of prepolymers offers the option of using OH components having secondary alcohol groups as well.

Aliphatic diisocyanates used are standard aliphatic and/or cycloaliphatic diisocyanates, for example tri-, tetra-, penta-, hexa-, hepta- and/or octamethylene diisocyanate, 2-methylpenta- methylene 1 ,5-diisocyanate, 2-ethyltetramethylene 1 ,4-diisocyanate, hexamethylene 1 ,6- diisocyanate (HDI), pentamethylene 1 ,5-diisocyanate, butylene 1 ,4-diisocyanate, trimethylhexa- methylene 1 ,6-diisocyanate, 1 -isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (iso- phorone diisocyanate, IPDI), 1 ,4- and/or 1 ,3-bis(isocyanatomethyl)cyclohexane (HXDI), cyclo- hexane 1 ,4-diisocyanate, 1 -methylcyclohexane 2,4- and/or 2, 6-diisocyanate, 4,4'-, 2,4'- and/or 2,2'-methylene dicyclohexyl diisocyanate (H12MDI).

Preferred aliphatic polyisocyanates are hexamethylene 1 ,6-diisocyanate (HDI), 1 -isocyanato- 3,3,5-trimethyl-5-isocyanatomethylcyclohexane and 4,4'-, 2,4'- and/or 2,2'-methylene dicyclohexyl diisocyanate (H12MDI).

Preferred aliphatic diisocyanates are hexamethylene 1 ,6-diisocyanate (HDI), 1 -isocyanato- 3,3,5-trimethyl-5-isocyanatomethylcyclohexane and 4,4'-, 2,4'- and/or 2,2'-methylene dicyclohexyl diisocyanate (H12MDI); especially preferred are 4,4'-, 2,4'- and/or 2,2'-methylene dicyclohexyl diisocyanate (H 12MDI) and 1 -isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane or mixtures thereof.

In a further embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein the polyisocyanate composition used comprises at least one polyisocy- anate selected from the group consisting of methylene diphenyl diisocyanate (MDI), hexameth- ylene 1 ,6-diisocyanate (HDI) and 4,4'-, 2,4'- and 2,2'-methylene dicyclohexyl diisocyanate (H12MDI).

Suitable aromatic diisocyanates are especially naphthylene 1 ,5-diisocyanate (NDI), tolylene 2,4- and/or 2, 6-diisocyanate (TDI), 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI), p-phenylene diisocyanate (PDI), diphenylethane 4,4'-diisocyanate (EDI), diphenylmethane diisocyanate, dimethyl diphenyl 3,3'-diisocyanate, diphenylethane 1 ,2-diisocyanate and/or phenylene diisocyanate.

Preferred examples of higher-functionality isocyanates are triisocyanates, e.g. triphenylmethane 4,4',4"-triisocyanate, and additionally the cyanurates of the aforementioned diisocyanates, and also the oligomers obtainable by partial reaction of diisocyanates with water, for example the biurets of the aforementioned diisocyanates, and also oligomers obtainable by controlled reaction of semiblocked diisocyanates with polyols having an average of more than two and preferably three or more hydroxyl groups.

According to the invention, the polyisocyanate composition may also comprise one or more solvents. Suitable solvents are known to those skilled in the art. Suitable examples are nonreactive solvents such as ethyl acetate, methyl ethyl ketone and hydrocarbons.

It is further possible in the context of the present invention to use crosslinkers as well, for example the aforementioned higher-functionality polyisocyanates or polyols or else other higher- functionality molecules having two or more functional groups reactive toward isocyanates. According to the invention, components (i) to (iii) are used in such a ratio that the molar ratio of the sum total of the functionalities of the polyol composition and chain extenders used to the sum total of the functionalities of the isocyanate composition used is in the range from 1 :0.8 to 1 :1 .3. The ratio is preferably in the range from 1 :0.9 to 1 :1 .2, further preferably in the range from 1 :0.965 to 1 :1.05, more preferably in the range from 1 :0.98 to 1 :1.03.

In a further embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein the molar ratio of the sum total of the functionalities of the polyol composition and chain extenders used to the sum total of the functionalities of isocyanate composi- tion used is in the range from 1 :0.8 to 1 :1.3.

A further parameter which is taken into account in the conversion of components (i) to (iii) is the isocyanate index. The index is defined here as the ratio of the total for number of isocyanate groups of component (i) used in the reaction to the isocyanate-reactive groups, i.e., more par- ticularly, the groups of components (ii) and (iii). At an index of 1000, there is one active hydrogen atom per isocyanate group of component (i). At indices exceeding 1000, there are more isocyanate groups than isocyanate-reactive groups. Preferably, the index in the conversion of components (i) to (iii) is in the range from 965 to 1 1 10, for example in the range from 970 to 1 1 10, further preferably in the range from 970 to 1050, more preferably in the range from 980 to 1030.

In a further embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein the index in the conversion is in the range from 965 to 1 100. According to the invention, in the conversion of components (i) to (iii), it is possible to add further additives, for example catalysts or auxiliaries and additions. Additions and auxiliaries are known per se to those skilled in the art. According to the invention, it is also possible to use combinations of two or more additives. In the context of the present invention, the term "additive" is especially understood to mean catalysts, auxiliaries and additions, especially stabilizers, nucleating agents, fillers or crosslinkers.

Suitable additives/additions are, for example, stabilizers, nucleating agents, fillers, for example silicates, or crosslinkers, for example polyfunctional aluminosilicates.

In a further embodiment, the present invention accordingly relates to a thermoplastic polyurethane as described above, wherein the thermoplastic polyurethane comprises at least one additive. Examples of auxiliaries and additions include surface-active substances, flame retardants, nucleating agents, oxidation stabilizers, antioxidants, lubricants and demolding aids, dyes and pigments, stabilizers, for example against hydrolysis, light, heat or discoloration, inorganic and/or organic fillers, reinforcers and plasticizers. Suitable auxiliaries and additions can be found, for example, in the Kunststoffhandbuch, volume VII, edited by Vieweg and Hochtlen, Carl Hanser Verlag, Munich 1966 (p. 103-1 13).

Suitable catalysts are likewise known in principle from the prior art. Suitable catalysts are, for example, organic metal compounds selected from the group consisting of tin organyls, titanium organyls, zirconium organyls, hafnium organyls, bismuth organyls, zinc organyls, aluminum organyls and iron organyls, for example tin organyl compounds, preferably tin dialkyls such as dimethyltin or diethyltin, or tin organyl compounds of aliphatic carboxylic acids, preferably tin diacetate, tin dilaurate, dibutyltin diacetate, dibutyltin dilaurate, bismuth compounds such as bismuth alkyi compounds or the like, or iron compounds, preferably iron(VI) acetylacetonate, or the metal salts of the carboxylic acids, for example tin(ll) isooctoate, tin dioctoate, titanic esters or bismuth(lll) neodecanoate.

In a preferred embodiment, the catalysts are selected from tin compounds and bismuth com- pounds, further preferably tin alkyi compounds or bismuth alkyi compounds. Particularly suitable are tin(ll) isooctoate and bismuth neodecanoate.

The catalysts are typically used in amounts of 0 to 2000 ppm, preferably 1 ppm to 1000 ppm, further preferably 2 ppm to 500 ppm and most preferably of 5 ppm to 300 ppm.

The properties of the thermoplastic polyurethanes of the invention may vary within wide ranges according to the application. The thermoplastic polyurethanes of the invention have, for example, a Shore hardness in the range from 60 A to 80 D, determined according to DIN 53505, preferably in the range from 80 A to 60 D, determined according to DIN 53505, further prefera- bly in the range from 95 A to 58 D, determined according to DIN 53505.

In a further embodiment, the present invention relates to a thermoplastic polyurethane as described above, wherein the thermoplastic polyurethane has a Shore hardness in the range from 60 A to 80 D, determined according to DIN 53505.

In a further aspect, the present invention also relates to a process for producing a thermoplastic polyurethane comprising the reaction of (i) at least one aliphatic polyisocyanate;

(ii) at least one chain extender; and

(iii) at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on an aliphatic dicarboxylic acid (A1 ) and a compound (B1 ) selected from the group consisting of compounds of the general formula

(I), compounds of the general formula (II) and compounds of the general formula (III):

X(R1 )2n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH;

Y(R1 ) _n (II) wherein Y is an aromatic ring with 6 carbon atoms with n being 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH;

Z(R1 ) _n -i (III) wherein

Z is an n-membered aromatic ring with n-1 carbon atoms and 1 heteroa- tom selected from nitrogen and oxygen with n being 5 or 6, and each R1 is independently selected from the group consisting of -

CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH.

With regard to preferred embodiments of the process, suitable feedstocks or mixing ratios, ref- erence is made to the above remarks which apply correspondingly.

Therefore, according to a further embodiment, the present invention is also directed to the process for producing a thermoplastic polyurethane as disclosed above, wherein ein the compound (B1 ) is cyclohexanedimethanol.

Furthermore, according to a further embodiment, the present invention is also directed to the process for producing a thermoplastic polyurethane as disclosed above, wherein the aliphatic dicarboxylic acid (A1 ) is adipic acid. The conversion of components (i) to (iii) can in principle be conducted under reaction conditions known per se. The conversion can be effected batchwise or else continuously, for example in a belt process or a reactive extrusion process. Suitable processes are described, for example, in EP 0 922 552 A1 or WO 2006/082183 A1

In a preferred embodiment, the conversion of components (i) to (iii) is conducted at elevated temperatures relative to room temperature. According to the invention, the heating can be effected in any suitable manner known to those skilled in the art.

In the case of a conversion by means of reactive extrusion methods, for example, the reaction is conducted in such a way that the zone temperature is in the range from 170°C to 245°C, prefer- ably in the range from 180°C to 235°C, further preferably in the range from 190°C to 230°C.

Accordingly, the present invention, in a further embodiment, also relates to a process for preparing a thermoplastic polyurethane as described above, wherein the conversion is effected by means of a reactive extrusion process and the zone temperature is in the range from 170°C to 245°C.

According to the invention, it is also possible that the process comprises further steps, for example a pretreatment of the components or an aftertreatment of the thermoplastic polyurethane obtained. Accordingly, the present invention also relates, in a further embodiment, to a process for preparing a thermoplastic polyurethane as described above, wherein the thermoplastic polyurethane obtained is heat-treated after the conversion.

The thermoplastic polyurethane of the invention or a thermoplastic polyurethane obtained or obtainable by a process according to the invention can be used in various ways. More particu- larly, the thermoplastic polyurethanes of the invention are suitable for the production of moldings and films, further preferably for the production of tubes.

The present invention therefore also further relates to the use of a thermoplastic polyurethane as described above or of a thermoplastic polyurethane obtainable or obtained by a process of the invention for production of injection molding products, extrusion products, films, and shaped bodies.

The present invention is also directed to the use of a thermoplastic polyurethane as disclosed above or of a thermoplastic polyurethane obtainable or obtained by a process as disclosed above for producing extrusion products, films and moldings.

It is also possible in the context of the present invention that the injection molding products, extrusion products, films or shaped bodies obtained are subjected to an aftertreatment. Further embodiments of the present invention can be inferred from the claims and examples. It will be apparent that the aforementioned features of the subject matter/processes/uses of the invention and those that are elucidated hereinafter are usable not just in the particular combina- tion specified but also in other combinations, without leaving the scope of the invention. For example, the combination of a preferred feature with a particularly preferred feature, or that of a feature that has not been characterized further with a particularly preferred feature, etc., is implicitly also encompassed even if this combination is not mentioned explicitly. Illustrative embodiments of the present invention are listed hereinafter, although these do not restrict the present invention. More particularly, the present invention also encompasses those embodiments which arise from the dependency references and hence combinations cited hereinafter.

1 . A thermoplastic polyurethane obtainable or obtained by reaction of at least the components (i) to (iii):

(i) at least one polyisocyanate;

at least one chain extender; and

at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on an aliphatic dicarboxylic acid (A1 ) and a compound (B1 ) selected from the group consisting of compounds of the general formula (I), compounds of the general formula (II) and compounds of the general formula (III):

X(R1 )2n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH;

Y(R1 ) (II) wherein

Y is an aromatic ring with 6 carbon atoms with n being 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH;

Z(R1 ) _n -1 (III) wherein

Z is an n-membered aromatic ring with n-1 carbon atoms and 1 heteroa- tom selected from nitrogen and oxygen with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH.

The thermoplastic polyurethane according to claim 1 , wherein the compound (B1 ) is cy- clohexanedimethanol.

The thermoplastic polyurethane according to claim 1 or 2, wherein the aliphatic dicarbox- ylic acid (AI ) is adipic acid.

4. The thermoplastic polyurethane according to claim 1 or 3, wherein the polyol composition comprises at least one further polyesterol. 5. The thermoplastic polyurethane according to any of claims 1 to 4, wherein the chain extender is a diol with a molecular weight Mw < 220 g/mol.

6. The thermoplastic polyurethane according to any of claims 1 to 5, wherein the chain extender is selected from the group consisting of 1 ,3-propane diol, 1 ,4-butane diol, and 1 ,6- hexanediol.

7. The thermoplastic polyurethane according to any one of claims 1 to 6, wherein the polyi- socyanate is an aromatic diisocyanate. 8. A process for producing a thermoplastic polyurethane comprising the reaction of

(i) at least one aliphatic polyisocyanate;

(ii) at least one chain extender; and

(iii) at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on an aliphatic dicarboxylic acid (A1 ) and a compound (B1 ) selected from the group consisting of compounds of the general formula (I), compounds of the general formula (II) and compounds of the general formula (III): X(R1 )2n (I) wherein

X is a cycloalkyl ring with n carbon atoms with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCHs, -OEt, CI, Br, F, I, H, -CH ₂ OH,and -CH ₂ CH ₂ OH;

Y(R1 ) _n (II) wherein

Y is an aromatic ring with 6 carbon atoms with n being 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH3, -OEt, CI, Br, F, I, H, -CH2OH, and -CH ₂ CH ₂ OH;

Z(R1 ) _n -1 (III) wherein

Z is an n-membered aromatic ring with n-1 carbon atoms and 1 heteroa- tom selected from nitrogen and oxygen with n being 5 or 6, and each R1 is independently selected from the group consisting of - CH ₃ , -CH2CH3, -CH2CH2CH2CH3, -CH(Me) ₂ , -OCH3, -SCH ₃ , -OEt, CI, Br,

F, I, H, -CH2OH, and -CH ₂ CH ₂ OH.

9. The process according to claim 8, wherein the compound (B1 ) is cyclohexanedimethanol. 10. The process according to claim 8 or 9, wherein the aliphatic dicarboxylic acid (A1 ) is adip- ic acid.

1 1 . The use of a thermoplastic polyurethane according to any one of claims 1 to 7 or of a

thermoplastic polyurethane obtainable or obtained by a process according to any one of claims 8 to 10 for producing extrusion products, films and moldings.

12. A thermoplastic polyurethane obtainable or obtained by reaction of at least the components (i) to (iii): (i) at least one polyisocyanate;

(ii) at least one chain extender; and

(iii) at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on dithio propionic acid and an aliphatic diol with a molecular weight Mw < 220 g/mol.

13. The thermoplastic polyurethane according to claim 12, wherein the aliphatic diol is cyclo- hexanedimethanol.

14. The thermoplastic polyurethane according to claim 12 or 13, wherein the polyol composition comprises at least one further polyesterol. 15. The thermoplastic polyurethane according to any of claims 1 1 to 14, wherein the chain extender is a diol with a molecular weight Mw < 220 g/mol.

16. The thermoplastic polyurethane according to any of claims 1 1 to 15, wherein the chain extender is selected from the group consisting of 1 ,3-propane diol, 1 ,4-butane diol, and 1 ,6-hexanediol.

17. The thermoplastic polyurethane according to any one of claims 12 to 16, wherein the polyisocyanate is an aromatic diisocyanate. 18. A process for producing a thermoplastic polyurethane comprising the reaction of

(i) at least one aliphatic polyisocyanate;

(ii) at least one chain extender; and

(iii) at least one polyol composition comprising a polyesterpolyol (P1 ), wherein the polyesterpolyol (P1 ) is based on dithio propionic acid and an aliphatic diol with a molecular weight Mw < 220 g/mol.

19. The use of a thermoplastic polyurethane according to any one of claims 12 to 17 or of a thermoplastic polyurethane obtainable or obtained by a process according to claim 18 for producing extrusion products, films and moldings.

Brief description of the figures:

Fig. 1 shows the results of measurements of the gas permeability of nitrogen measured through a TPU film of 200 micrometer thickness for the different examples. The gas permeability (y-axis) is measured in cm ^3* mm/(m ^2* d ^* bar) and depicted for the respective entries (1 ) to (12).

Fig. 2 shows the results of measurements of the gas permeability of oxygen measured through a TPU film of 200 micrometer thickness for the different examples. The gas permeability (y-axis) is measured in cm ^3* mm/(m ^2* d ^* bar) and depicted for the respective entries (1 ) to (12).

Fig. 3 shows the results of measurements of the gas permeability of carbon dioxide meas- ured through a TPU film of 200 micrometer thickness for the different examples. The gas permeability (y-axis) is measured in cm ^3* mm/(m ^2* d ^* bar) and depicted for the respective entries (1 ) to (12).

Fig. 4 shows the results of measurements of the gas permeability of methane measured through a TPU film of 200 micrometer thickness for the different examples. The gas permeability (y-axis) is measured in cm ^3* mm/(m ^2* d ^* bar) and depicted for the respective entries (1 ) to (12).

The examples which follow serve to illustrate the invention, but are in no way restrictive with regard to the subject matter of the present invention.

EXAMPLES

1. Materials used

Following TPU's were synthesized incorporating the Polyols based on ADS/CHDM through partial incorporation as depicted in table 1 :

Table 1

TPU1 : Elastollan 685 A (available from BASF Polyurethanes) Polyol A polyol based on adipic acid (ADA)/ Cyclohexandimethanol (VP 90055) (OH value 1 14.83, F =2, M _w = 977 g/mol).

Polyol B: Polyol based on Dithiodipropionic acid / Cyclohexandimethanol (CHDM) (OH value 55.19, F=2, M _w = 2032 g/mol).

Polyol C: Polyol based on adipic acid (ADA)/ Cyclohexandimethanol (OH value 1 14.83,

Polyol D: Polyol based on 3,3'-Dithiodipropionic acid/ hexanediol (H1.6) (OH value

105.3, F =2, Mw = 1065 g/mol).

Polyol E: Polyolesterol based on ADA/ Cyclohexandimethanol (OH value 1 12.07, F =2,

Polyol F: Polyolesterol based on ADA/ Cyclohexandimethanol (OH value 120.27, F =2,

Polyol G: hydroxyl terminated polybutadiene (LBH-P2000, F=2I).

Polyol H: hydroxyl terminated polybutadiene (LBH-P3000, F=2I).

Polyol I: Polyol based on caprolacton / thiodiglycol (F =2).

Polyol J: Polyol based on adipic acid (ADA)/ furan (F =2).

Gas permeability of films

The permeability of different gases (namely, N2, O2, CH ₄ , CO2, H2O) were subsequently measured through a TPU film of 200 micrometer thickness. The gas permeability values with different recipes were plotted in figures 1 to 4. The gas permeability is measured in cm ^3* mm/(m ^2* d ^* bar).

20% exchange of the standard ADA/BDO based polyol with ADA/CHDM polyol for a standard TPU1 (also referred to as E685A) recipe, resulted in around 40% improvement of the gas barrier properties for oxygen and nitrogen.

The gas permeability of carbon dioxide and methane, was found to be reduced by around 30-40% through partial incorporation (20% exchange) of ADA/CHDM based PESOLs in comparison to our standard recipe based on ADA/BDO polyesterols. This is marked with an arrow in the figures. The respective entry refers to the column in the respective figures 1 to 4. The following materials were tested:

Mechanical performance of the synthesized TPU:

In order to check the mechanical performance of the TPU, standard mechanical testing were performed on 2 mm thick injection molded plates. The results are summarized in table 2.

Table 2

The tensile strength and elongation at break values were found to be comparable to the standard TPU1 . The abrasion values and also the tensile strengths were found to be marginally improved after 20% exchange of the standard polyesterols with ADS/CHDM based polyols.

4. Higher loading of ADS/CHDM PESOL: Increased incorporation of adipic acid and CHDM based polyesterols were further carried out. Two polyols based on ADA CHDM with Mw's 932 and 1001 g/mol were incorporated into the standard TPU1 recipe through partial exchange as depicted in table 3.

Table 3

47G0, 60 and 100% of Polyesterol based on adipic acid and CHDM were exchanged and incHorporated into the standard TPU1 recipe. The gas permeability tests for water vapor were carried out after extruding 0.2 mm thin films. The SD/D values were measured, the results are summarized in table 5.

It was observed that with an increase in the content of the ADA/CHDM polyol from 40% to 100% incorporation, resulted in a steep increase in the SD/D value of the water vapor permeation from 7.14 to 31 .66. In comparison, the standard TPU1 showed a value of only 3.365.

Additionally, the mechanical testing was also performed on the 2 mm injection molded plates and the mechanical testing results other than the 100% polyol exchange, were found to be comparable to the standard the TPU1 material as shown in table 4.

Table 4

Even though films could be extruded with complete exchange of ADA/CHDM based polyesterols, injection molded plates were found to be deformed after annealing and therefore no mechanical testing results were obtained in that particular case. It was additionally observed that the tensile strength was marginally improved with 40- 60% of ADA/CHDM incorporation. Along with that a marginal improvement of tear strength was also noticed. Thus, the ADA/CHDM based PESOL exchange not only improved the gas barrier properties but also showed improved mechanical performance.

Table 5 shows the results of measurements of the water vapor permeability carried out after extruding 0.2 mm thin films.

Table 5.

Sample No. SD/D 0.2 mm films

Example 5 3,365

Example 6 7,145

Example 7 7,205

Example 8 1 1 ,56

Example 9 31 ,66

Literature cited

WO 2006/082183 A1

EP 0 922 552 A1

WO 98/56845 A1

Kunststoffhandbuch, Volume 7, "Polyurethanes", Carl Hanser Verlag, 3rd edition 1993, chapter 3.1

Kunststoffhandbuch, Volume 7, "Polyurethanes", Carl Hanser Verlag, Munich, 1966 (p. 103- 1 13)