Polymers having improved processability

• US 6,255,445 B1
• Filed: 04/17/1998
• Issued: 07/03/2001
• Est. Priority Date: 09/15/1995
• Status: Expired due to Term

• Current Assignee: Perstorp Specialty Chemicals AB
• Original Assignee: Solvay Interox Limited
• Inventors: Dutton, Amanda Jane, Wasson, Robert Craig, Claeys, Ivan Lode André Maria
• Primary Examiner(s): Truong, Duc
• Application Number:
  US09/029,972
• Time in Patent Office: 1,173 Days
• Field of Search: 528/354, 528/355, 528/495, 528/502.B, 528/503, 264/45.2, 264/45.8, 264/45.9
• US Class Current: 528/354
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08J 2367/04 Polyesters derived from hydroxy carboxylic acids, e.g. lactones C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets

Abstract

Poly(lactones) are provided. The poly(lactones) are obtained by polymerization of a lactone with an initiator system comprising at least one polyfunctional initiator. The poly(lactones) have a shear viscosity at some temperature in the range of from 35 to 45° C. above the melting temperature of the poly(lactone) of at least 6 kPas at 0.1 s⁻¹ shear rate and no greater than 3.5 kPas at 100 s⁻¹ shear rate, and a shear viscosity activation energy of greater than 40 kJ/mol. Preferably, the poly(lactone) is poly(caprolactone).

Claims

1. A process for film-blowing a poly(lactone), comprising:

(a) providing a poly(lactone) having non-linear polymer chains, said poly(lactone) being formed by reaction between a lactone monomer and an initiator system comprising at least one polyfunctional initiator having at least three active hydrogens, the amount of said initiator being such that the theoretical molecular weight, per active hydrogen, of the poly(lactone) polymer chains formed by reaction with said initiator is at least 25,000, having a melting temperature of greater than 45°

C., having a shear viscosity, when measured at some temperature in the range of from 35 to 45°

C. above the melting temperature of the poly(lactone), of at least 6 kPas at 0.1 s<sup>−

1</sup> shear rate and not greater than 3.5 kPas at 100 s<sup>−

1</sup> shear rate, and having a shear viscosity activation energy of greater than 40 kJ/mol;

(b) extruding said poly(lactone) through an annular die to form a tube of molten polymer;

(c) inflating said tube to produce a bubble; and

(d) cooling the bubble or allowing the bubble to cool to solidify the polymer.

3. A process of film-blowing according to claim 1, characterized in that the poly(lactone) comprises a poly(ε

-caprolactone).

4. A process of film-blowing according to claim 1 or 3, characterized in that the low-shear viscosity is in the range of from 11 kPas to 18 kPas.

5. A process of film-blowing according to claim 4, characterized in that the high-shear viscosity is in the range of from 0.5 kPas to 2.5 kPas.

6. A process of film-blowing according to claim 1 or 3, characterized in that the shear viscosity activation energy is in the range of from 42 to 55 kJ/mol.

7. A process of film-blowing according to claim 1 or 3, characterized in that the poly(lactone) has a reciprocal melt elasticity, G″

/G′

, at some temperature in the range of from 35 to 45°

C. above the melting temperature of the poly(lactone), at a shear rate of 1 s<sup>−

1</sup>, of less than 7.

8. A process of film-blowing according to claim 1 or 3, characterized in that the initiator system comprises a tri or tetrafunctional initiator.

9. A process of film-blowing according to claim 8, characterized in that the mole ratio of lactone monomer to number of active hydrogens in the initiator is selected to be such that the theoretical molecular weight of polymer, assuming all the monomer reacts with the initiator, is at least 75,000.

10. A process of film-blowing according to claim 9, characterized in that the mole ratio of lactone monomer to number of active hydrogens in the initiator is selected to be such that the theoretical molecular weight of polymer, assuming all the monomer reacts with the initiator, is in the range of 90,000 to 110,000.

11. A process of film-blowing according to claim 1 or 3, characterized in that the initiator system comprises a mixture of at least one polyfunctional initiator with at least one mono or difunctional initiator.

12. A process of film-blowing according to claim 11 characterized in that the mole ratio of polyfunctional initiator:

mono or difunctional initiator is from 5;

1 to 1;

5.

13. A process of film-blowing according to claim 12, characterized in that the mono or difunctional initiator is selected from the group consisting of cetyl alcohol and butane-1,2-diol.

14. A process of film-blowing according to claim 1 or 3, characterized in that the polyfunctional initiator is selected from the group consisting of trimethylolpropane, pentaerythritol, poly(caprolactone) having a molecular weight of from 500 to 2,000 which has itself been initiated with trimethylolpropane, and a poly(caprolactone) having a molecular weight of from 500 to 2,000 which has itself been initiated with pentaerythritol.

29. A process of film-blowing according to claim 1 or 3, characterized in that the initiator system comprises a trifunctional initiator.

31. A process of film-blowing according to claim 1 wherein said poly(lactone) comprises a poly(caprolactone) and wherein said initiator system comprises:

(a) a poly(caprolactone) having a molecular weight of from 500 to 2000 and which has itself been initiated by trimethylolpropane or pentaerythritol, and

(b) cetyl alcohol and butane-1,4-diol, said poly(caprolactone) having a shear viscosity at 100°

C. from 10 kPas to 20 kPas at 0.1 s<sup>−

1</sup> shear rate and from 1 kPas to 2 kPas at 100 s<sup>−

1</sup> shear rate.

2. A polymerization process for the production of a poly(lactone) having non-linear polymer chains which comprises:

(a) reacting a lactone monomer with an initiator system, said initiator system comprising at least one polyfunctional initiator having at least three active hydrogens, the amount of said initiator system being such that the theoretical molecular weight, per active hydrogen, of the poly(lactone) polymer chains formed by reaction with said initiator is at least 25,000, said reaction being carried out under an air or inert atmosphere in the presence of a catalyst; and

continuing the reaction until the reaction is substantially complete and until the poly(lactone) produced has a melting temperature of greater than 45°

C., a shear viscosity when measured at some temperature in the range of 35 to 45°

C. above the melting temperature of the poly(lactone) of at least 6 kPas at 0.1 s<sup>−

1</sup> shear rate and not greater than 3.5 kPas at 100 s<sup>−

1</sup> shear rate, and a shear viscosity activation energy of greater than 40 kJ/mol.

15. A polymerization process according to claim 2, characterized in that the poly(lactone) is a poly(ε

-caprolactone).

16. A polymerization process according to claim 2 or 15, characterized in that the low-shear viscosity is in the range of from 11 kPas to 18 kPas.

17. A polymerization process according to claim 16, characterized in that the high-shear viscosity is in the range of from 0.5 kPas to 2.5 kPas.

18. A polymerization process according to claim 2 or 15, characterized in that the shear viscosity activation energy is in the range of from 42 to 55 kJ/mol.

19. A polymerization process according to claim 2 or 15, characterized in that the poly(lactone) has a reciprocal melt elasticity, G″

/G′

, at some temperature in the range of from 35 to 45°

C. above the melting temperature of the poly(lactone), at a shear rate of 1 s<sup>−

1</sup>, of less than 7.

20. A polymerization process according to claim 2 or 15, characterized in that the initiator system comprises a tri or tetrafunctional initiator.

21. A polymerization process according to claim 20, characterized in that the mole ratio of lactone monomer to number of active hydrogens in the initiator is selected to be such that the theoretical molecular weight of polymer, assuming all the monomer reacts with the initiator, is at least 75,000.

22. A polymerization process according to claim 21, characterized in that the mole ratio of lactone monomer to number of active hydrogens in the initiator is selected to be such that the theoretical molecular weight of polymer, assuming all the monomer reacts with the initiator, is in the range from 90,000 to 110,000.

23. A polymerization process according to claim 2 or 15, characterized in that the initiator system comprises a mixture of at least one polyfunctional initiator with at least one mono or difunctional initiator.

24. A polymerization process according to claim 23, characterized in that the mole ratio of polyfunctional initiator:

mono or difunctional initiator is from 5;

1 to 1;

5.

25. A polymerization process according to claim 24, characterized in that the mono or difunctional initiator is selected from the group consisting of cetyl alcohol and butane-1,2-diol.

26. A polymerization process according to claim 2 or 15, characterized in that the polyfunctional initiator is selected from the group consisting of trimethylolpropane, pentaerythritol, poly(caprolactone) having a molecular weight of from 500 to 2,000 which has itself been initiated with trimethylolpropane, and a poly(caprolactone) having a molecular weight of from 500 to 2,000 which has itself been initiated with pentaerythritol.

27. A polymerization process according to claim 23, characterized in that the mole ratio of lactone monomer to total number of active hydrogens in the initiator system, assuming all the monomer reacts with the initiator and that each of the active hydrogens is equally reactive, is such that the theoretical molecular weight of polymer per active hydrogen is at least 25,000.

28. A polymerization process according to claim 27, characterized in that the mole ratio of lactone monomer to total number of active hydrogens in the initiator system, assuming all of the monomer reacts with the initiator and that each of the active hydrogens is equally reactive, is such that the theoretical molecular weight of polymer per active hydrogen is from 30,000 to 50,000.

30. A polymerization process according to claim 2 or 15, characterized in that the initiator system comprises a trifunctional initiator.

32. A polymerization process according to claim 2 wherein said poly(lactone) comprises a poly(caprolactone) and wherein said initiator system comprises:

(a) a poly(caprolactone) having a molecular weight of from 500 to 2000 and which has itself been initiated by trimethylolpropane or pentaerythritol, and

(b) cetyl alcohol and butane-1,4-diol, said poly(caprolactone) having a shear viscosity at 100°

C. from 10 kPas to 20 kPas at 0.1 s<sup>−

1</sup> shear rate and from 1 kPas to 2 kPas at 100 s<sup>−

1</sup> shear rate.