Uniform distribution polycarbonate pellets

• US 5,414,056 A
• Filed: 02/11/1993
• Issued: 05/09/1995
• Est. Priority Date: 12/03/1990
• Status: Expired due to Fees

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Kirk, Richard O.
• Primary Examiner(s): Kight, III, John
• Assistant Examiner(s): Jones, Richard
• Application Number:
  US08/016,374
• Time in Patent Office: 817 Days
• Field of Search: 525/461, 525/100, 525/106, 525/403, 525/431, 525/446, 525/453, 525/461
• US Class Current: 525/461
• CPC Class Codes: B29B 2009/125 Micropellets, microgranules, microparticles
• CPC Class Codes: B29B 9/065 under-water, e.g. underwater pelletizers
• CPC Class Codes: B29B 9/12 characterised by structure or composition
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material

Abstract

A polycarbonate pellet having a size between 200 and 1,500 microns, not inclusive, is produced by extruding molten polycarbonate through a die and cutting such extrudate with a die face cutter.

Claims

1. A composition of matter comprising pellets of a blend of an aromatic polycarbonate with one or more polymers selected from the group consisting of polyacetal;

polyacrylate;

polyamide;

polyester;

poly(ethylene oxide);

polymethacrylate;

polyolefin;

poly(phenylene ether);

polystyrene;

polyurethane;

acrylonitrile/butadiene/styrene copolymer;

poly(vinyl acetate);

poly(vinyl alcohol);

poly(vinyl amide);

poly(vinyl chloride);

poly(vinyl ether), said pellets being characterized in that

(a) the median particle size of said pellets is between 250 and 1,000 microns;

(b) the particle size dispersion of said pellets is less than 100 microns; and

(c) the skew of the particle distribution is less than 0.25;

each as determined according to ASTM Designation D 1921-63.

2. The pellets of claim 1 characterized in that the particle size dispersion of said pellets is less than 60 microns.

3. The pellets of claim 1 characterized in that the particle size dispersion of said pellets is less than 40 microns.

10. The pellets of claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 characterized in that the skew of the particle distribution is less than 0.1.

11. The pellets of claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 characterized in that the skew of the particle distribution is less than 0.05.

21. The pellets of claim 10 which are formed by cutting such blend which has been forced in molten form through a die.

22. The pellets of claim 21 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

23. The pellets of claim 22 which are formed by cutting such blend at the face of a die.

24. The pellets of claim 21 which are cylindrical in shape.

25. The pellets of claim 24 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.

26. The pellets of claim 21 in the form of a batch of pellets which weighs at least 150 pounds.

27. The pellets of claim 11 which are formed by cutting such blend which has been forced in molten form through a die.

28. The pellets of claim 27 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

29. The pellets of claim 28 which are formed by cutting such blend at the face of a die.

30. The pellets of claim 27 which are cylindrical in shape.

31. The pellets of claim 30 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.

32. The pellets of claim 27 in the form of a batch of pellets which weighs at least 150 pounds.

33. The pellets of claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 13 or 14 wherein the polycarbonate is prepared from 2,2-bis(4-hydroxyphenyl)propane.

34. The pellets of claim 1 which are formed by cutting such blend which has been forced in molten form through a die.

35. The pellets of claim 34 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

36. The pellets of claim 34 which are formed by cutting such blend at the face of a die.

37. The pellets of claim 34 which are cylindrical in shape.

38. The pellets of claim 34 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.

39. The pellets of claim 34 in the form of a batch of pellets which weighs at least 150 pounds.

4. A composition of matter comprising pellets of a blend of an aromatic polycarbonate with one or more polymers selected from the group consisting of polyacetal;

polyacrylate;

polyamide;

polyester;

poly(ethylene oxide);

polymethacrylate;

polyolefin;

poly(phenylene ether);

polystyrene;

polyurethane;

acrylonitrile/butadiene/styrene copolymer;

poly(vinylacetate);

poly(vinyl alcohol);

poly(vinyl amide);

poly(vinyl chloride);

poly(vinyl ether), said pellets being characterized in that

(a) the median particle size of said pellets is between 500 to 900 microns;

(b) the particle size dispersion of said pellets is less than 100 microns; and

(c) the skew of the particle distribution is less than 0.25;

each as determined according to ASTM Designation D 1921-63.

5. The pellets of claim 4 characterized in that the particle size dispersion of said pellets is less than 60 microns.

6. The pellets of claim 4 characterized in that the particle size dispersion of said pellets is less than 40 microns.

40. The pellets of claim 4 which are formed by cutting such blend which has been forced in molten form through a die.

41. The pellets of claim 40 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

42. The pellets of claim 40 which are formed by cutting such blend at the face of a die.

43. The pellets of claim 40 which are cylindrical in shape.

44. The pellets of claim 40 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.

45. The pellets of claim 40 in the form of a batch of pellets which weighs at least 150 pounds.

7. A composition of matter comprising pellets of a blend of an aromatic polycarbonate with one or more polymers selected from the group consisting of polyacetal;

polyacrylate;

polyamide;

polyester;

poly(ethylene oxide);

polymethacrylate;

polyolefin;

poly(phenylene ether);

polystyrene;

polyurethane;

acrylonitrile/butadiene/styrene copolymer;

poly(vinyl acetate);

poly(vinyl alcohol);

poly(vinyl amide);

. poly(vinyl chloride);

poly(vinyl ether), said pellets being characterized in that

(a) the median particle size of said pellets is between 600 to 800 microns;

(b) the particle size dispersion of said pellets is less than 100 microns; and

(c) the skew of the particle distribution is less than 0.25;

each as determined according to ASTM Designation D 1921-63.

8. The pellets of claim 7 characterized in that the particle size dispersion of said pellets is less than 60 microns.

9. The pellets of claim 7 characterized in that the particle size dispersion of said pellets is less than 40 microns.

46. The pellets of claim 7 which are formed by cutting such blend which has been forced in molten form through a die.

47. The pellets of claim 46 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

48. The pellets of claim 46 which are formed by cutting such blend at the face of a die.

49. The pellets of claim 46 which are cylindrical in shape.

50. The pellets of claim 46 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.

51. The pellets of claim 46 in the form of a batch of pellets which weighs at least 150 pounds.

12. A composition of matter comprising pellets of a blend of an aromatic polycarbonate with one or more polymers selected from the group consisting of polyacetal;

polyacrylate;

polyamide;

polyester;

poly(ethylene oxide);

polymethacrylate;

polyolefin;

poly(phenylene ether);

polystyrene;

polyurethane;

acrylonitrile/butadiene/styrene copolymer;

poly(vinyl acetate);

poly(vinyl alcohol);

poly(vinyl amide);

poly(vinyl chloride);

poly(vinyl ether), said pellets being characterized in that,

(a) after said pellets have been agitated on a screen having a mesh opening size of 850 microns, and after those pellets not retained on said 850 micron screen have then been agitated on a screen having a mesh opening size of 710 microns, the portion of said pellets which together is retained on one or the other of said screens is more than 85% by weight; and

(b) none of said pellets are retained after agitation on a mesh screen having a mesh opening size of 1,500 microns or more.

13. The composition of claim 12 wherein more than 90% by weight of said pellets are together retained on one or the other of said screens.

14. The composition of claim 12 wherein more than 95% by weight of said pellets are together retained on one or the other of said screens.

15. The pellets of claims 12, 13 or 14 which are formed by cutting such blend which has been forced in molten form through a die.

16. The pellets of claim 15 which are formed by cutting such blend which has been forced through a die hole having a diameter of about 0.25 mm to about 0.8 mm.

17. The pellets of claim 15 which are formed by cutting such blend at the face of a die.

18. The pellets of claim 15 which are cylindrical in shape.

19. The pellets of claim 15 in the form of a batch of pellets which weighs at least 150 pounds.

20. The pellets of claim 18 wherein the cylinder has a length/diameter ratio of 2/1 to 1/2.