CA2040910A1

CA2040910A1 - Thermoplastic polyurethane-polyurea elastomers having increased heat resistance

Info

Publication number: CA2040910A1
Application number: CA002040910A
Authority: CA
Inventors: Tillmann Hassel; Hanns P. Muller
Original assignee: Individual
Current assignee: Bayer AG
Priority date: 1990-04-20
Filing date: 1991-04-17
Publication date: 1991-10-21
Also published as: EP0452775B1; EP0452775A2; DE59106702D1; ATE129260T1; DE4012629A1; EP0452775A3; JPH06145289A

Abstract

Mo3542 LeA 27,611 THERMOPLASTIC POLYURETHANE-POLYUREA
ELASTOMERS HAVING INCREASED HEAT RESISTANCE
ABSTRACT OF THE DISCLOSURE
The invention relates to improved thermoplastic polyurethane-polyurea elastomers based on 4,4'-diisocyanato-dicyclohexylmethane, cyclic secondary diamines, and macrodiols having a molecular weight greater than 400.

Mo3542

Description

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Mo3542 LeA 27,611 THERMOPLASTIC POLYURETHANE-POLYUREA
ELAS~OMERS HAVING INCREASED HEAT RESISTANCE
BACKGROUND OF THE INVENTION
This invention relates to new aliphatic, light-stable thermoplastic polyurethane-polyurea elastomers having increased heat resistance and to a process for their production.
Thermoplastic polyurethane elastomers ("TPU's") are known. For example, D. Dieterich in Methoden der Orqanischen Chemie (Houben-Weyl), Vol. E 20, pages 1638-41; Thieme, Stuttgart 1987. One disadvantage of TPU's is their moderate heat resistance which, particularly in the case of flexible types, is not far above 100C.
According to Kunststoffe, 68, (12), pages 819-825 (1978), the range of shear modulus curves for diol-extended TPU's extends only to 130C and, although amine extension increases the range to higher temperatures, the resultant polyurethane can no longer be plasticized without thermal damage. In general, therefore, NCO prepolymers are extended with amines only in RIM technology. The moldings thus produced, however, are not thermoplastic elastomers. Various methods have been adopted with a view to increasing the heat resistance of TPU's. According to German Offenlegungsschrift 3,329,775, the heat resistance of aromatic TPU's can be increased, for example, by partly replacing the 4,4'-diiso-2~ cyanatodiphenylmethane with 1,5-diisocyanatonaphthalene. The same effect is obtained by partial urea linkage with water or by addition of a diamine. See German Offenle~ungsschrift 2,423,764 and European Patent Application 21,323. In general, however, such measures also increase the hardness of the corresponding thermoplastic polyurethane, which is undesirable.
It is known from U.S. Patent 2,923,802 that thermoplastic polyurethane elastomers can be obtained by condensation of ~,~-chloroformates of long-chain polyether or polyester diols in admixture with piperazine. Elastomers such , . . .. . . . . . . . .
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as these, however, are no different from conventional TPU's in their behavior under dynamic stress at high temperatures.
It is known from U.S. Patent 3,635,908 that TDI-terminated prepolymers can be chain-extended with the bis-carbonate of 2-methylpiperazine to form soft thermoplastic polyurethane elastomers. U.S. Patent 3,655,627 describes light-stable TPU's for which the hard segment is synthesized from bis(4-isocyanato)cyclohexylmethane and isophoronediamine.
In view of the small hard segment component, these products are soft and have tensile strengths of up to 41 N/mm2 for breaking elongations of 412 to 630%. The products, however, show unsatisfactory dynamic behavior upon exposure to heat.
It is known that the hard segments of a polyurethane can be optimally aggregated only if the synthesis components of the hard segment are both chemically and stereochemically identical. Unless this synthetic principle is observed, the products obtained have low melting points and poor thermal stability. According to Rubber ChemistrY and TechnoloqY, Vol.
58, pages 985-996 (1985), for example, butanediol-extended TPU's based on 4,4'-diisocyanatodicyclohexylmethane achieve satisfactory thermal stability only if the trans-trans content in the isomer mixture of the diisocyanate is high. In accordance with this finding, British Patent 1,554,102 describes polyurethanes having a 4,4'-diisocyanatodicyclohexyl-methane/butanediol hard segment for which the advantage for the application described therein lies precisely in the synthesis of the hard segment disturbed by the presence of an isomer mixture of the isocyanate and, hence, in the low melting point of the products.
Accordingly, it was not to be expected that thermoplastic polyurethane/polyurea elastomers of remarkably high thermal stability, despite their small hard segment component, would be obtained when 4,4'-diisocyanatodicyclo-hexylmethane is used as an isomer mixture. This mixture is optionally diluted by addition of more aliphatic diisocyanates Mo3542 : , ,. . ~
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., and the nard segment is synthesized by chain extension with p;perazine.
The hard segments thus produced are polyureas. The melting points and aggregation of polyurea hard segments are generally higher than those of the corresponding polyurethanes.
This, however, applies only to chain extension with diprimary diamines because it is only then that the very strong interchain interaction occurs via bifurcate hydrogen bridges.
See Coll. Polvm. Sci., 263, 335-341 (1985).
Piperazine, on the other hand, is a disecondary diamine. Consequently, when this compound is used, the number of possible hydrogen bridges in the hard segment corresponds to those of corresponding polyurethanes. Accordingly, it was not to be expected that the higher heat resistance observed in accordance with the invention would be caused by the polyurea structure of the hard segments because no more hydrogen bridges are present than in the polyurethane.
Accordingly, the problem addressed by the present invention was to provide thermoplastic polyurethanes combining relatively low hardness with excellent heat resistance.
SUMMARY OF THE INVENTION
The present invention relates to thermoplastic polyurethane polyureas based on an aliphatic polyisocyanate, at least one macrodiol, and a diamine chain-extending agent prepared by a process comprising reacting (a) 4,~'-diisocyanatodicyclohexylmethane, (b) a cyclic secondary diamine, and (c~ a macrodiol having a molecular weight greater than 400, optionally in the presence of (d) low molecular weight diols, chain regulators, and typical auxil;arles and additives.
The diamine (b) is preferably a piperazine which may optionally be substituted with one or more C1-C6 alkyl (preferably one or two methyl groups). In a preferred Mo3542 .
, ,.~ , embodiment, the thermoplastic contains partly recurring structural units corresponding to formula I
~1 -C-N- ~ -CH2- ~ -N-C-N\__~ N- (I) wherein Rl and R2 are independently hydrogen or methyl (preferably hydrogen), with the remainder of the thermoplastic, of course, including urethane-based structural units formed by reaction of the macrodiol hydroxyl groups with isocyanate groups.
DETAILED DESCRIPTION OF TH~ INVENTION

4,4'-Diisocyanatodicyclohexylmethane is generally prepared as an isomer mixture. The properties of the hard segments are largely determined by the trans-trans isomer content of the diisocyanate. It has been found that with a very small trans-trans isomer content, the polyurethanes obtained show unsatis~actory elastic properties and poor thermal stability. In contrast, with a high trans-trans isomer content, the thermoplastic products obtained cannot be processed without decomposition.
According to the invention, therefore, preferred polyurethanes are those according to the invention in which the 4,4'-diisocyanatodicyclohexylmethane used in the synthesis of recurring structural units corresponding to formula I is an isomer mixture containing about 10 to about 30% (preferably 20%~ of the trans-trans isomer, the remainder being cis-trans and/or cis-cis isomers.
In a preferred embodiment, 4,4'-diisocyanatodicyclo-hexylmethane is blended with other polyisocyanates. The prepolymers thereby obtained are thinner liquids than those obtained with the same molar quantity of Mo3542 -.

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4,4'-diisocyanatodicyclohexylmethane alone. It has been found that such blending is possible without causing significant adverse effects on the properties of the end products as long as the content of 4,4'-diisocyanatodicyclohexylmethane does not fall below 20%. Accordingly, the present invention preferably relates to polyurethanes in which mixtures of 4,4'-diiso-cyanatodicyclohexylmethane and other aliphatic diisocyanates (preferably hexamethylene diisocyanate and isophorone diiso-cyanate) are used for the synthesis of the hard segments, with the proviso that these mixtures must contain between 20 and 90 mol-% (preferably between 40 and 80 mol-% and more preferably between 60 and 70 mol-%) 4,4'-diisocyanatodicyclohexylmethane.
In a preferred embodiment, the thermoplastics according to the invention contain at least 10% by weight of the recurring units corresponding to formula I.
The polyurethanes according to the invention acquire their spectrum of properties through the special synthesis of their hard segments. These hard segments are produced by chain extension with cyclic secondary diamines, especially with p;perazine and its 2-monoalkyl or 2,5-d;alkyl derivatives, unsubstituted piperazine being particularly preferred.
Suitable additional chain-extending agents are the short-chain alcohols typically used in polyurethane chemistry, which generally have an isocyanate functionality of two.
Examples of suitable such compounds include alcohols such as ethylene glycol, 1,4 butanediol, 1,6-hexanediol, neopentyl glycol, hydroquinone bis(2-hydroxyethyl ether), 1,4-cyclo-hexanediol, diethylene glycol, and 4,4'-dihydroxydicyclohexyl-methane.
~he soft segment macrodiols used in the synthesis of the thermoplastic polyurethane-polyurea elastomers according to the invention may be any of the preferably difunctional and, optionally in small quantities of preferably up to 10%, trifunctional polyols known in the art. Suitable such polyols include polyesters, polylactones, polyethers, polythioethers, Mo3542 - . , ~, .

polyester amides, polycarbonates, and polyacetals typically used in polyurethane chemistry and known in the art; vinyl polymers (for example, polybutadiene diols); polyhydroxyl compounds already containing urethane or urea groups; and optionally modified natural polyols and other compounds containing Zerewitinoff-active groups capable of reacting with isocyanates, such as amino, carboxyl, or thiol groups. These compounds are described in detail, for example, in German Offenlegungsschriften 2,302,564, 2,423,764, 2,549,372, 2,402,804, 2,920,501, and 2,457,387.
Preferred polyols according to the invention are substantially difunctional hydroxyl-containing polyesters of diols and adipic acid, hydroxyl polycarbonates, hydroxyl caprolactones, hydroxyl polytetrahydrofurans, or hydroxy-polyethers based on polyethylene oxide and/or polypropylene oxide, as well as corresponding mixed ethers of such components.
These polycls have average molecular weights of about 550 to about lO,OOO and preferably 1,000 to 4,000. Polyols having molecular weights of 1,500 to 2,500 are particularly preferred.
The monofunctional alcohols, amines, and aliphatic isocyanates typically used in polyurethane chemistry and known in the art may be used as chain regulators in quantities of f 25 0.05 to 5 mol-%, based on the soft segment polyol. However, it ha~ proved to be particularly favorable to use monofunctional ethylene oxide-propylene oxide mixed polyethers having molecular weights of about 2,000 as the chain regulators.
These chain regulators also reduce the viscosity of the prepolymers and thus favorably affect their processability.
Accordingly, ~he present invention particularly relates to polyurethanes according to the invention in which mono-functional ethylene ox;de/propylene oxide polyethers having a molecular weight of 400 to 4,000 (preferably 1,000 to 2,000) Mo3542 ~ "

r ,~,, ,1 r-, are used as chain regulators in quantities of about 0.05 to about 5 mol-%, based on the macrodiol or mixture used.
Further auxiliaries and additives are understood to be the known catalysts used in polyurethane chemistry, such as, 5 for example, tin(II) octoate, dibutyltin dilaurate, titanium tetrabutylate, iron(II) acetylacetonate, diazabicyclooctane, and N,N-tetramethyl ethylenediamine. Other additives include fillers and reinforcing materials, such as glass fibers, carbon fibers, TiO2, diatomaceous earth, aromatic polyamides, liquid 10 crystal ("LC") polyesters, even in ground form, quartz powder, and polyureas, as well as inorganic or organic dyes or pigments. Such additives are insoluble in the hydrocarbon phase and are advantageously incorporated in the macropolyols used before carrying out direct synthesis of the polyurethane 15 powder.
Several methods for preparing the polyurethane polyureas according to the invention can be used. In the preferred methods, an NCO prepolymer is prepared by the reaction of the 4,4'-diisocyanatodicyclohexylmethane (or 20 diisocyanate mixtures) with the macrodiol component. The prepolymer is then chain-extended with the cyclic secondary diamine to form the polyurethane polyurea. Suitable methods for preparing the polyurethane polyureas according to the invention include synthesis in known manner in solution using 25 polyurethane solvents, the solution processes described in German Offenlegungsschrift 2,644,434 being particularly suitable. The product may be subsequently separated from the solvent (mixture) in an evaporation screw. Synthesis of the polymer, however, may also be carried out in heterogeneous 30 phase using emulsifiers for the NCO prepolymer, with the product accumulating in powder form. Such processes using a hydrocarbon carrier phase are known and are described, for example, in German Offenlegungsschriften 2,556,945, 2,559,769, and 2,442,085 and U.S. Patents 4,032, 516 and 3,787,525. The emulsifiers which are the subject of German Offenleyungs-Mo3542 ', ., , ~

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schriften 3,928,150 and 3,928,149 and the synthesis processesdescribed therein are used with particular advantage for this synthesis.
Suitable such emulsifiers include substantially l;near, surface-active copolymers that can be obtained by copolymerization of (A) a partial reaction product of (A)(l) (meth)acrylic acid or a derivative thereof and (A)(2) a macromolecular compound substituted with at least two functional groups selected from OH and NH2, the functional groups which are not reacted with (A)(l) being irreversibly blocked with (B) a urethane of (B)(1) a long-chain alkyl isocyanate and (B)~2) a hydroxyalkyl (meth)acrylate.
Using these surface-active copolymers, polyurethane powders may be directly produced in finely divided form by reaction of polyisocyanates and isocyanate-reactive compounds in a carrier phase.
By virtue of the low reactivity of the NCO-terminated prepolymers to water, the chain-extending reaction may be carried out in water as the continuous phase. Urea chain extension by hydrolysis of the NCO groups takes place to only a limited extent, if at all. Processes such as these are also known and are described, for example, in U.S. Patent 3~655,627 and in German Offenlegungsschri~t 2,906,159. In general, surfactants must also be added in these processes to enable them to be carried out safely.
As discussed above, polyurethanes according to the invention may be synthesized both in hydrocarbons and in water as the continuous phase. The polyurethanes accumulate in powder form and are isolated, for example, by filtration.
However, this powder synthesis ;n water as the continuous phase is particularly easy to carry out when polyurethane polyureas are prepared using monofunctional ethylene oxide/propylene oxide polyethers having a molecular weight of about 400 to Mo3542 - . .......... . .

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_9_ about 4,000 (preferably 1,000 to 2,000) in quantities of 0.05 to 5 mol-%, based on the macrodiol or mixture used. In the production of these polyurethanes in powder form in an aqueous carrier phase, surfactants need not be added. As a result, the steps that would otherwise be necessary for removing these substances from the product are not needed.
Accordingly, the present invention also relates to a process for the production of polyurethanes in powder form, wherein the chain-extending agent is initially introduced in water, the prepolymer is stirred into the aqueous carrier phase, and the chain-extending reaction is completed (optionally at elevated temperature).
The polyurethanes according to the invention may be processed to molded articles by conventional methods, for example, by injection molding or press molding. By virtue of their powder form, the polyurethanes may be used with particular advantage for the production of elastic, flexible skins and coatings by sintering.
Preferred polyurethanes are prepared using about 1.7 to about (preferably 1.8 to 2.2) mol of diisocyanate (mixture) per mol of macrodiol, optionally in admixture with low molecular weight diols having a molecular weight in the range from 62 to 400.
The polyurethanes according to the invention are soft products having Shore A hardnesses of about 60 to about 80, coupled with good elastic behavior and high heat resistance.
These properties are achieved by a surprisingly small hard segment content when compared with MDI-butanediol types.
The special hard segment synthesis of the TPU's, by which soft products having a heat resistance of greater than about 130C are obtained~ is a key feature of the invention.
The following examples further illustrate details for the preparation of the compounds of this invention. The invention, which is set forth in the foregoing disclosure, is not to be limited either in spirit or scope by these examples.
Mo3542 , ,. `

Those skilled in the art will readily understand that known variations of the conditions and processes of the following preparative procedures can be used to prepare these compounds.
Unless otherwise noted~ all temperatures are degrees Celsius and all percentages are percentages by weight.
EXAMPLES
Example 1 Hexanediol polycarbonate (OH value 56, functionality 2) (90 9) was introduced into a 2-liter three-necked flask equipped with a stirrer and reflux condenser and dehydrated for 2 hours at 120C/14 mbar. Commercial 4,4'-diisocyanatodicyclo-hexylmethane containing 20% trans-trans isomer (20.0~ 9) was then added and the mixture was stirred at 110 to 120C. After 2 hours, the prepolymer had an NCO content of 2.36%. The prepolymer was diluted with 155 ml of toluene. A solution of 2.7 9 of piperazine in 230 ml of 1:1 toluene/isopropyl alcohol was rapidly added dropwise to the resultant solution with stirring at 60C until the product was NCO-free (IR control~.
A 1.5-ml portion of the chain-extending solution remained unused. Because of viscosity, the mixture was diluted with 535 ml of the 1:1 toluene/isopropyl alcohol mixture. Films were cast from the solution and, after evaporation of the solvent, were reduced in si~e, dried, and press-molded under a pressure of 100 bar at 180C to form 1-mm thick test specimens.

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The product had the following properties:
Hardness (Shore A) 74 Melting point (Kofler, from 240C
film, 5 mins. dwell time) Modulus (100%) 4.43 N/mm2 Modulus (300%) 10.52 N/mm2 Ultimate tensile stress 21.9 N/mm2 Elongation at break 631%
Softening point under static load 198C
(Penetration method: I mm diameter bar, load 0.2N; test specimen thickness 1 mm) ExamPle 2 A mixture of 45 9 of hexanediol polycarbonate (OH
value 56, functionality 2~ and 45 9 of hexanediol/neopentyl glycol polyadipate (OH value 56, functionality 2) was dehydrated as in Example 1 and then prepolymerized with a mixture of 13.36 of 4,4'-diisocyanatodicyclohexylmethane and 5.56 g of isophorone diisocyanate to an NCO content of 2.42%.
The prepolymer was dissolved in 600 ml of toluene and chain-extended as in Example 1 with 2.7 g of piperazine in 225 ml of 2:1 toluene/isopropyl alcohol. A 10-ml portion of the chain-extending solution remained unused. After dilution with 400 ml of 2:1 toluene/isopropyl alcohol, films ~ere cast as in Example I and press-molded to test specimens.
The product had the following properties:
Hardness (Shore A) 70 Melting point (Kofler) 230C
Ultimate tensile stress 34.7 N/mm2 30 Elongation at break 1100%
Softening point under static load 138C
Example 3 Ethylene glycol polyadipate (~H value 56, functionality 2) (9 kg) was dehydrated for 2 hours at 120C/40 mbar in a 150-liter reactor equipped with an anchor stirrer, Mo3542 , , .

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reflux condenser, and addition funnel. A mixture of 1.572 kg of 4,4'-diisocyanatodicyclohexylmethane (trans-trans content of 20%) and 666 9 of isophorone diisocyanate was introduced and the mixture was prepolymerized at 110C. After 30 minutes, the NCO content had fallen to 3.36%. The prepolymer was dissolved in 15.5 L of toluene and chain-extended at 60C with a solution of 3~7 9 piperazine in 23 L of 1:1 toluene/isopropyl alcohol.
Because of viscosity, the solution was diluted with another 53.5 L of the 1:1 toluene/isopropyl alcohol solvent mixture.
The product was freed from the solvent in an evaporation screw, granulated, dried, and injection-molded to test specimens.
The product had the following properties:
Hardness (Shore A) 73 Melting point (Kofler) 230C
15 Ultimate tensile stress 21.7 N/mm2 Elongation at break llCO%
Softening point under static load 159C
Example 4 A mixture of 75.735 9 of a hexanediol/neopentyl glycol polyadipate (OH value 66, functionality 2) and 1.0125 9 of a butanol-started ethylene oxide/propylene oxide mixed polyether having an average molecular weight of 2250 was dehydrated and prepolymerized with a mixture of 6.5934 9 of isophorone diisocyanate and 18.1566 g of 4,4'-diisocyanato-dicyclohexylmethane at 110C to an NCO content of 4.27%. Thehot (100C) prepolymer was added dropwise over a period of 15 minutes to a rapidly stirred sulution of 403856 g of piperazine in 439.5 g water. To complete the reaction, the suspension of the resultant powder was stirred for 12 hours at 80~C. The powder was f;ltered under suction and dried, giving a quantitative yield of a material having a melting point of 2307C (Kofler) Test specimens (1 mm thickness) were prepared from the powder by press molding at 180~C ~200 bar). The product had the following properties:
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13 2 s Hardness (Shore A) 74 Modulus (300%) 7 N/mm2 Modulus (600%) 21 N/mm2 Ultimate tensile stress 25 N/mm2 5 Elongation at break 600%
Storage modulus G (from Plateau up to 140C
torsion measurement) Example 5 As in Example 4, 89.1 g of an ethylene glycol polyadipate (OH value 56, functionality 2) and 1.0125 9 of the sàme butanol-started ethylene oxide/propylene oxide mixed polyethPr were dehydrated and prepolymerized with a mixture a 6.5934 9 of isophorone diisocyanate and 18.1566 g of 4,4'-diisocyanatodicyclohexylmethane to an NCO content of 3.95%.
The hot prepolymer was added dropwise over a period of 15 minutes to a rapidly stirred solution of 4.3856 9 of piperazine in 439.5 g of water. The reaction mixture was then stirred as in Example 4 and the powder was separated off, dried, and processed to test specimens. The yield was quantitative.
The product had the following properties:
Hardness (Shore A) 73 Melting point (Kofler) 220C
Modulus (300%) 7.5 N/mm2 Modulus (600%) 24 N/mm2 Ultimate tensile stress 33 N/mm Elongation at break 760%
Storage modulus G (from Plateau up to lSOC
torsion measurement) Mo3542 .
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Claims

1. A thermoplastic polyurethane polyurea prepared by a process comprising reacting (a) 4,4'-diisocyanatodicyclohexylmethane, (b) a cyclic secondary diamine, and (c) a macrodiol having a molecular weight greater than 400.

2. A thermoplastic polyurethane polyurea according to Claim 1 wherein the cyclic secondary diamine (b) is a piperazine.

3. A thermoplastic polyurethane polyurea according to Claim 2 wherein the piperazine is substituted with one or more C1-C6 alkyl.

4. A thermoplastic polyurethane polyurea according to Claim 2 wherein the piperazine is substituted with one or two methyl.

5. A thermoplastic polyurethane polyurea according to Claim I containing at least 10% by weight partly recurring structural units corresponding to the formula wherein R1 and R2 are independently hydrogen or methyl.

6. A thermoplastic polyurethane polyurea according to Claim 5 wherein R1 and R2 are hydrogen.

7. A thermoplastic polyurethane polyurea according to Claim 1 wherein the 4,4'-diisocyanatodicyclohexylmethane is an isomer mixture containing 10 to 30% of the trans-trans isomer.

8. A thermoplastic polyurethane polyurea according to Claim 1 wherein the 4,4'-diisocyanatodicyclohexylmethane is an isomer mixture containing 20% of the trans-trans isomer.
Mo3542

9. A thermoplastic polyurethane polyurea according to Claim 1 wherein the 4,4'-diisocyanatodicyclohexylmethane is used as a mixture with hexamethylene diisocyanate and/or isophorone diisocyanate, with the proviso that said mixture must contain between 20 and 90 mol-% 4,4'-diisocyanatodicyclo-hexylmethane.

10. A thermoplastic polyurethane polyurea according to Claim 1 wherein 1.7 to 3 mol of 4,4'-diisocyanatodicyclo-hexylmethane is used per mol of the macrodiol.

11. A thermoplastic polyurethane polyurea according to Claim 1 wherein 1.8 to 2.2 mol of 4,4'-diisocyanatodicyclo-hexylmethane is used per mol of the macrodiol.

12. A thermoplastic polyurethane polyurea according to Claim 9 wherein 1.7 to 3 mol of the mixture of 4,4'-diiso-cyanatodicyclohexylmethane with hexamethylene diisocyanate and/or isophorone diisocyanate is used per mol of the macrodiol.

13. A thermoplastic polyurethane polyurea according to Claim 1 prepared by a process comprising reacting components (a), the, and (c) in the presence of (d) a low molecular weight diol having a molecular weight in the range from 62 to 400.

14. A thermoplastic polyurethane polyurea according to Claim 13 wherein 1.7 to 3 mol of 4,4'-diisocyanatodicyclo-hexylmethane is used per mol of the macrodiol.

15. A thermoplastic polyurethane polyurea according to Claim 13 wherein 1.8 to 2.2 mol of 4,4'-diisocyanatodicyclo-hexylmethane is used per mol of the macrodiol.

16. A thermoplastic polyurethane polyurea according to Claim 1 prepared by a process comprising reacting components (a), (b), and (c) in the presence of (e) a chain regulator.

17. A thermoplastic polyurethane polyurea according to Claim 16 wherein the chain regulator is a monofunctional ethylene oxide/propylene oxide polyether having a molecular Mo3542 weight of 400 to 4,000 used in a quantity of 0.05 to 5 mol-%, based on the macrodiol.

18. A thermoplastic polyurethane polyurea according to Claim 17 wherein the polyether has a molecular weight of 1,000 to 2,000.

19. A process for preparing a thermoplastic polyurethane polyurea according to Claim 1 in powder form comprising (a) adding a cyclic secondary diamine to water to form an aqueous carrier phase;
(b) stirring into the aqueous carrier phase an NCO prepolymer prepared by reacting (i) 4,4'-diisocyanatodicyclohexylmethane and (ii) a macrodiol having a molecular weight greater than 400; and (c) allowing the cyclic secondary diamine and the NCO
prepolymer to react to completion, optionally at elevated temperature.

20. A process according to Claim 19 wherein the cyclic secondary diamine (b) is a piperazine or a piperazine substituted with one or two C1-C6 alkyl.

21. A process for preparing a thermoplastic polyurethane polyurea according to Claim 1 in powder form comprising (a) adding a cyclic secondary diamine to water to form an aqueous carrier phase;
(b) stirring into the aqueous carrier phase an NCO prepolymer prepared by reacting (i) a mixture of 4,4'-diisocyanatodicyclohexylmethane with hexamethylene diisocyanate and/or isophorone diisocyanate, with the proviso that said mixture must contain between 20 and 90 mol-% 4,4'-diisocyanato-dicyclohexylmethane, and (ii) a macrodiol having a molecular weight greater than 400; and Mo3542 (c) allowing the cyclic secondary diamine and the NCO
prepolymer to react to completion, optionally at elevated temperature.

22. A process according to Claim 21 wherein the cyclic secondary diamine (b) is piperazine or piperazine substituted with one or two C1-C6 alkyl.

Mo3542