LOW ENERGY ELECTRON BEAM TREATMENT OF POLYMERIC FILMS, AND APPARATUS THEREFORE

• US 3,846,521 A
• Filed: 02/03/1971
• Issued: 11/05/1974
• Est. Priority Date: 02/03/1971
• Status: Expired due to Term

• Current Assignee: Fred D. Osterholtz
• Original Assignee: Fred D. Osterholtz
• Inventors: Osterholtz, Fred D.
• Primary Examiner(s): Anderson, Philip E.
• Application Number:
  US05/112,125
• Time in Patent Office: 1,371 Days
• Field of Search: 264/41,22,340,331,216,320,321,DIG.13 55/16 204/168,159.13,159.14,159.19,159.2,160.1
• US Class Current: 264/423
• CPC Class Codes: B01D 67/009 with wave-energy, particle-radiation or plasma
• CPC Class Codes: B29C 2035/0877 using electron radiation, e.g. beta-rays
• CPC Class Codes: B29C 71/04 by wave energy or particle radiation , e.g. for curing or vulcanising preformed articles during moulding, e.g. in a mould B29C35/08
• CPC Class Codes: B29K 2001/00 Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
• CPC Class Codes: B29K 2001/12 Cellulose acetate
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/12 PPO, i.e. polyphenylene oxide; PPE, i.e. polyphenylene ether
• CPC Class Codes: B29K 2995/0065 Permeability to gases
• CPC Class Codes: B29L 2007/008 Wide strips, e.g. films, webs
• CPC Class Codes: B29L 2031/755 Membranes, diaphragms
• CPC Class Codes: Y10S 264/13 Cell size and distribution control while molding a foam

Abstract

Polymeric films are exposed to a low energy electron beam in order to alter the permeability characteristics of the polymeric films for gases. The so treated polymeric films have enhanced utility for separating gases such as hydrogen and helium from mixtures containing same.

Claims

1. PROCESS WHICH COMPRISES EXPOSING AN ORGANIC POLYMERIC FILM TO A BEAM OF LOW ENERGY ELECTRONS AT A POTENTIAL FROM ABOUT 10 TO ABOUT 30,000 VOLTS, AND UNDER AN ABSOLUTE PRESURE BELOW THE PRESSURE AT WHICH GLOW DISCHARGE OCCURS AND BELOW ABOUT 5 X 10**-3 TORR, THE TOTAL EXPOSURE OF SAID POLYMERIC FILM TO SAID BEAM OF ELECTRONS BEING WITHIN THE RANGE OF FROM ABOUT 0.005 TO ABOUT 1,000 VOLT-AMPERE-SECONDS PER AQUARE CENTIMETER AND SUFFICIENT TO LOWER THE PERMEABILITY OF SAID POLYMERIC FILM WITH RESPECT TO AT LEAST ONE GAS.

2. The process of claim 1 wherein the total exposure of said polymeric film to said beam of electrons is sufficient to increase the permeation separation selectivity towards at least one gas.

3. The process of claim 1 wherein the total exposure of said polymeric film to said beam of electrons is sufficient to increase the barrier properties of said polymeric film with respect to at least one gas.

4. The process of claim 1 wherein said potential is within the range of from about 10 to about 3,000 volts.

5. The process of claim 1 wherein said pressure is above about 10 7 torr.

6. The process of claim 1 wherein said pressure is within the range of from about 10 5 torr to about 3 X 10 3 torr.

7. The process of claim 1 wherein the total exposure of said polymeric film to said beam of electrons is within the range of from about 0.005 to about 1,000 volt-ampere-seconds per square centimeter.

8. The process of claim 7 wherein said total exposure is above about 0.05 volt-ampere-seconds per square centimeter.

9. The process of claim 1 wherein the rate of exposure of said polymeric film to said beam of electrons is within the range of from about 0.0002 to about 3 volt-amperes per square centimeter.

10. The process of claim 1 wherein the said polymeric film is exposed to said beam of electrons at a rate within the range of from about 0.0005 to about 20 milliamperes per square centimeter.

11. The process of claim 1 wherein said potential is within the range of from about 10 to about 3,000 volts, wherein said pressure is within the range of from about 10 5 to about 3 X 10 3 torr, wherein the total exposure of said polymeric film to said beam of electrons is within the range of from about 0.0005 to about 1,000 volt-ampere-seconds per square centimeter, and wherein said polymeric film has a thickness of up to about 10 mils.

12. The process of claim 11 wherein the rate of exposure of said polymeric film to said beam of electrons is within the range of from about 0.0002 to about 3 volt-amperes per square centimeter.

13. The process of claim 1 wherein said polymeric film is a film of a polymer of an olefinically unsaturated monomer.

14. The process of claim 4 wherein said polymeric film is a film of a polymer of an olefinically unsaturated monomer.

15. The process of claim 6 wherein said polymeric film is a film of a polymer of an olefinically saturated monomer.

16. The process of claim 7 wherein said polymeric film is a film of a polymer of an olefinically unsaturated monomer.

17. The process of claim 12 wherein said polymeric film is a film of a polymer of an olefinically unsaturated monomer.

18. The process of claim 1 wherein said polymeric film is a film of a cellulosic polymer.

19. The process of claim 4 wherein said polymeric film is a film of a cellulosic polymer.

20. The process of claim 6 wherein said polymeric film is a film of a cellulosic polymer.

21. The process of claim 7 wherein said polymeric film is a film of a cellulosic polymer.

22. The process of claim 12 wherein said polymeric film is a film of a cellulosic polymer.

23. The process of claim 22 wherein the cellulosic polymer is cellulose acetate.

24. The process of claim 1 wherein said polymeric film is a film of a polycarbonate.

25. The process of claim 4 wherein said polymeric film is a film of a polycarbonate.

26. The process of claim 6 wherein said polymeric film is a film of a polycarbonate.

27. The process of claim 7 wherein said polymeric film is a film of a polycarbonate.

28. The process of claim 12 wherein said polymeric film is a film of a polycarbonate.

29. The process of claim 28 wherein said polycarbonate is a polycarbonate of a bisphenolalkane.

30. The process of claim 29 wherein said bisphenol alkane is 2, 2-bisphenolpropane.

31. The process of claim 28 wherein said polycarbonate is a polycarbonate of 2,2,4,4-tetramethyl-1,3-butanediol.

32. The process of claim 1 wherein said polymeric film is an asymmetric film.

33. The process of claim 12 wherein said polymeric film is an asymmetric film.

34. The process of claim 23 wherein the cellulose acetate film is asymmetric.

35. The process of claim 1 wherein said polymeric film is a film of a siloxane polymer.

36. The process of claim 12 wherein the polymeric film is a film of a siloxane polymer.

37. The process of claim 1 wherein the polymeric film is a film of a polyphenylene oxide.

38. The process of claim 12 wherein said polymeric film is a film of a polyphenylene oxide.

39. Apparatus for exposing an organic polymeric film to a beam of low energy electrons which comprises in combination:

a. a source of low energy electrons having a potential from about 10 to about 30,000 volts;

b. a target to receive said low energy electrons;

c. electrical circuit means to impel said electrons between said source and said target along a predetermined path;

d. means for inserting an organic polymeric film in said path; and

e. means for containing said source, target, path, and polymeric film under an absolute pressure below the pressure at which glow discharge occurs and below about 5 X 10 3 torr.

40. The apparatus of claim 39 wherein said target to receive electrons comprises an electrically conductive member capablE of supporting said polymeric film at a position in said path.

41. The apparatus of claim 40 wherein said electrically conductive member comprises a rotatably mounted member adapted to continuously move said polymeric film through said path.

42. The apparatus of claim 40 wherein the electrical circuit means includes means for inducing a positive potential on said electrically conductive member and a negative potential on said source of electrons.

43. The apparatus of claim 42 wherein said source of electrons comprises a heated filament.