Process for the production of a thermoplastic elastomer and the thermoplastic elastomer

Abstract

A thermoplastic elastomer contains (a) hard segments of a polyester and (b) soft segments containing repeating units derived from an aliphatic carbonate, wherein the thermoplastic elastomer exhibits a melt flow index (MFI) measured at 230 C. under a load of 10 kg (MFI 230 C./10 kg) according to ISO1133 (2011) of at most 40 g/10 min. The thermoplastic elastomer is produced by subjecting a precursor of the thermoplastic elastomer to solid state post reaction processing at a temperature between 140 and 170 C. until the thermoplastic elastomer has the required MFI of at most 40 g/10 min measured at 230 C. under a load of 10 kg (MFI 230 C./10 kg) according to ISO1133 (2011).

Claims

1. A process for the production of a thermoplastic elastomer containing (a) hard segments of a polyester and (b) soft segments comprising repeating units derived from an aliphatic carbonate, wherein the process comprises subjecting a precursor thermoplastic elastomer to solid state post-reaction processing at a temperature between 140 and 170 C. until the thermoplastic elastomer has a melt flow index (MFI) measured at 230 C. under a load of 10 kg (MFI 230 C./10 kg), according to ISO1133 (2011) of at most 40 g/10 min.

2. The process according to claim 1, wherein the precursor thermoplastic elastomer is subjected to solid state post-reaction at a temperature below 165 C.

3. The process according to claim 1, wherein the hard segments (a) of a polyester contain as repeating units butylene terephthalate.

4. The process according to claim 1, wherein soft segments (b) contain alkylene carbonate repeating unit is represented by Formula I: ##STR00003## where R=H and/or alkyl; and X=2-20.

5. The process according to claim 1, wherein the hard segments (a) and the soft segments (b) are bonded via ester bonds forming copolyester units and the copolyester units are joined by a urethane group having the formula: ##STR00004## where R1=an alkyl, aryl or aralkyl group and p=2 or 3.

6. A thermoplastic elastomer comprising: (a) hard segments of a polyester, and (b) soft segments which comprise repeating units derived from an aliphatic carbonate, wherein the thermoplastic elastomer has a melt flow index (MFI) measured at 230 C. under a load of 10 kg (MFI 230 C./10 kg) according to ISO1133 (2011) of at most 40 g/10 min.

7. The thermoplastic elastomer according to claim 6, wherein the MFI of the thermoplastic elastomer is at most 30.

8. The thermoplastic elastomer according to claim 6, wherein the thermoplastic elastomer has a melting temperature measured with DSC according to ISO 11357-1:1997 under air atmosphere (purge 50 ml/min) using a heating and cooling rate of 20 K/min is at least 180 C.

9. The thermoplastic elastomer according to claim 8, wherein the melting temperature of the thermoplastic elastomer is at least 200 C.

10. The thermoplastic elastomer according to claim 6, wherein the hard segments (a) comprise butylene terephthalate as repeating units.

11. The thermoplastic elastomer according to claim 6, wherein the soft segments (b) comprise repeating units represented by Formula I: ##STR00005## where R=H and/or alkyl; and X=2-20.

12. A process for forming a blow-molded article which comprises blow molding a polymer composition comprising the thermoplastic elastomer according to claim 6.

13. The process according to claim 12, wherein the process is suction blow molding.

14. A shaped object comprising the thermoplastic elastomer according to claim 6, wherein the shaped object is an air duct, a corrugated tube for the production of jounce bumpers or a cover for a constant velocity joint.

Description

EXAMPLES

(1) Materials Used:

(2) Arnitel CM551, a copolymer containing polybutyleneterephtalate hard segments and polyhexamethylenecarbonate soft segments, having an MFI (230 C., 10 kg) of 60 g/10 min and a melting temperature of 205 C. Arnitel CM622, a copolymer containing polybutyleneterephtalate hard segments and polyhexamethylenecarbonate soft segments, having an MFI (230 C., 10 kg) of 65 g/10 min and a melting temperature of 208 C.
Test Methods: The melting temperature was measured with DSC, according to ISO 11357-1:1997 under air atmosphere (purge 50 ml/min) using a heating and cooling rate of 20 K/min. The melt flow index (MFI) was measured according to ISO 1133 (2011).

Comparative Experiments A, B, C, D and E and Examples I and II

(3) 25 grams of Arnitel CM622 pellets were loaded in a tubular reactor of 100 ml and heated to various temperatures under a continuous nitrogen flow of 500 grams/hour during 20 hours. The MFI and the melting temperature of the resulting material were measured. The results are given in table 1.

(4) TABLE-US-00001 TABLE 1 Comp. Exp./ Reaction Temperature MFI Melting Temperature Example ( C.) (g/10 min) ( C.) A 80 63 205 B 110 55 204 C 130 47 203 I 150 27 203 II 170 15 199 D 180 42 190 E 190 65 180

Comparative Experiment F and Example III

(5) 25 grams of Arnitel CM551 pellets were loaded in a tubular reactor of 100 ml and heated to various temperatures under a continuous nitrogen flow of 500 grams/hour during 16 hours. The MFI and the melting temperature of the resulting material were measured. The results are given in table 2.

(6) TABLE-US-00002 TABLE 2 Comp. Exp./ Reaction Temperature MFI Melting Temperature Example ( C.) (g/10 min) ( C.) III 150 16 199 F 185 >200 Amorphous

(7) At low reaction temperatures (comparative experiments A, B and C) no sufficient decrease in MFI is obtained, although no significant decrease in melting temperature is observed.

(8) At high reaction temperatures (comparative experiments D, E and F) even an increase in MFI is observed, and a steep decrease in melting temperature is observed.

(9) At temperatures between 140 C. and 170 C. both the significant decrease in MFI is obtained as required, while maintaining the melting temperature at an acceptable level.