PROCESS OF PREPARING GELLED CELLULOSE TRIACETATE PRODUCTS AND THE PRODUCTS PRODUCED THEREBY

• US 3,846,404 A
• Filed: 05/23/1973
• Issued: 11/05/1974
• Est. Priority Date: 05/23/1973
• Status: Expired due to Term

• Current Assignee: Moleculon, Inc. (Mayne Pharma)
• Original Assignee: Larry D. Nichols
• Inventors: Nichols, Larry D.
• Primary Examiner(s): Czaja, Donald E.
• Assistant Examiner(s): Griffin, Ronald W.
• Application Number:
  US05/363,267
• Time in Patent Office: 531 Days
• Field of Search: 264/41,49,342R,DIG.71 210/500 106/196 260/23R
• US Class Current: 536/76
• CPC Class Codes: B01D 67/0009 by phase separation, sol-gel transition, evaporation or solvent quenching
• CPC Class Codes: B01D 71/16 Cellulose acetate
• CPC Class Codes: C08B 3/22 Post-esterification treatments, including purification
• CPC Class Codes: D01F 2/28 from organic cellulose esters or ethers, e.g. cellulose acetate
• CPC Class Codes: Y10S 264/71 Processes of shaping by shrinking

Abstract

Unique gelled cellulose triacetate products, for example, in film or fiber form, prepared by: providing a solution of cellulose triacetate in an acidic nonhydrolyzing solvent; forming the solution into a desired product, such as film or fiber; contacting the product with a nonsolvent for cellulose triacetate which is miscible in the given solvent, to form a gelled product by solvent replacement; recovering a strong, flexible, transparent, high-liquid-content gelled cellulose triacetate product; and optionally removing or replacing all or part of the liquid content to yield modified gels with useful properties. The gelled cellulose triacetate products are useful, for example, as packaging materials by virtue of their strong contraction during drying, good final strength, and heat resistance; as intermediates in the production of cellulose triacetate films and fibers strengthened by drying under tension; as semipermeable membranes; and as carriers for other materials, such as liquids with good lubricating, medicinal or electrical properties.

Claims

1. A PROCESS OF PREPARING A GELLED CELLULOSE TRICETATE PRODUCT, WHICH PROCESS COMPRISES:

A. PROVIDING A POLYMER SOLUTION COMPRISING CELLULOSE TRIACETATE WITH AN ACETYL CONTENT GREATER THAN ABOUT 42 PERCENT AND A MAJOR AMOUNT OF A NONHYDROLYZING ACIDIC SOLVENT FOR THE CELLULOSE TRIACETATE;

B. FORMING THE POLYMER SOLUTION INTO A CONFIGURATION OF THE PRODUCT;

C. INTRODUCING THE FORMED PRODUCT INTO CONTACT WITH AN EXCESS OF A GELLING LIQUID WHICH IS BOTH A NONSOLVENT FOR THE CELLULOSE TRIACETATE AND MISCIBLE WITH THE SOLVENT USED FOR A PERIOD OF TIME, SO AS TO REPLACE SUBSTANTIALLY THE ENTIRE SOLVENT IN THE FORMED PRODUCT WITH THE GELLING LIQUID, THE REPLACEMENT CARRIED OUT AT A TEMPERATURE LOW ENOUGH TO PROVIDE AN ULTAMICROPOROUS GELLED PRODUCT HAVING DISTINCT INTERPENETRATING POLYMER AND LIQUID PHASES, WHICH IN FILM OR FIBER FORM IS FLEXIBLE, TRANSPARENT AND SELF-SUPPORTING;

AND D. RECOVERING THE GELLED PRODUCT TO PREPARED.

2. The process of claim 1 which includes incorporating the recovered product about an object, and evaporating the gelling liquid to effect shrinkage about the object.

3. The process of claim 2 which includes the use of a volatile gelling liquid, wrapping the product about an object, and evaporating the liquid to effect shrinkage of the product about the object.

4. The process of claim 1 wherein the polymer solution comprises from about 4 to 25 percent by weight of cellulose triacetate.

5. The process of claim 1 wherein the polymer solution comprises from about 75 to 96 percent by weight of the solvent.

6. The process of claim 1 wherein the polymer solution contains up to 10 percent by weight of a plasticizer.

7. The process of claim 1 wherein the polymer solution or the liquid gelling agent contains up to 10 percent by weight of a monomeric or polymeric additive.

8. The process of claim 7 wherein the polymeric additive is nylon.

9. The process of claim 1 wherein the polymer solution has a viscosity of from 102 to 106 centipoises at 25*C.

10. The process of claim 1 wherein the acidity of solvent is about the same or greater than metacresol, but insufficient to degrade the cellulose triacetate by hydrolysis.

11. The process of claim 1 wherein the acidic solvent is selected from the group consisting of formic acid, acetic acid, acetic anhydride, trifluoroacetic acid, metacresol and combinations thereof.

12. The process of claim 1 wherein the product is formed by extruding the polymer solution as a fiber or film.

13. The process of claim 1 wherein the product is formed by casting the polymer solution as a thin film.

14. The process of claim 13 wherein the polymer is formed by casting the polymer solution onto a woven or nonwoven supporting sheet material.

15. The process of claim 1 wherein the gelling liquid comprises an aqueous solution.

16. The process of claim 1 wherein the gelling liquid is water or water-soluble organic nonsolvent for the cellulose triacetate.

17. The process of claim 1 wherein the gelling liquid comprises alcohol, glycol or a polyol having a meltpoint below 40*C.

18. The process of claim 1 wherein the gelling liquid is a nonaqueous liquid, and wherein the replacement of the solvent is carried out at a temperature of below about 40*C.

19. The process of claim 1 wherein the gelling liquid is an aqueous solution and the replacement of the solvent is carried out at a temperature of below about 35*C.

20. The process of claim 1 wherein the acidic solvent is an acidic phenolic compound, the gelling liquid is an alcohol, and the replacement is carried out at a temperature of less than 40*C.

21. The process of claim 20 wherein the acidic solvent is metacresol, and the gelling liquid is methanol.

22. The process of claim 1 wherein the acidic solvent is a carboxylic acid, the gelling liquid is water and the replacement is carried out at a temperature of from 0* to 30*C.

23. The process of claim 1 which includes the step of drying the gelled product recovered under tension to provide a product of improved strength.

24. The process of claim 23 wherein the gelling liquid is a volatile gelling liquid, and wherein the gelling liquiD is removed by drying the gelled product under tension.

25. The process of claim 1 wherein the gelling liquid comprises a volatile nonsolvent and a nonvolatile additive, and which includes the step of removing the volatile nonsolvent from the gelled product to provide a cellulose triacetate product containing the nonvolatile additive.

26. The process of claim 25 wherein the removal of the volatile nonsolvent of the gelling liquid is carried out while the gelled product is under tension.

27. The process of claim 1 which includes drying the recovered gelled product to remove all or a part of the gelling liquid to provide a cellulose triacetate product with a reduced content of gelling liquid.

28. The process of claim 27 wherein the gelled product is heated by immersing the gelled product in hot water.

29. A process of preparing a cellulose triacetate product, which process comprises:

a. providing a polymer solution comprising i. cellulose triacetate with an acetyl content greater than about 42 percent, ii. more than 75 percent by weight of a nonhydrolyzing acidic water-miscible solvent, and iii. up to 10 percent by weight of a diluent additive;

b. forming the polymer solution into a product form;

c. immersing the formed product directly into an excess of water as a gelling liquid for a time sufficient to replace substantially all of the solvent with the gelling liquid at a temperature below about 35*C to provide a gelled product containing cellulose triacetate as a polymer phase and the gelling liquid as a liquid phase, the gelled product being ultramicroporous and in film and fiber form, transparent and self-supporting; and

d. recovering the gelled product.

30. The process of claim 29 wherein the polymer solution comprises from about 4 to 15 percent by weight of cellulose triacetate and the acidic solvent is selected from the group consisting of formic acid, acetic acid, metacresol, acetic anhydride, trifluoroacetic acid and combinations thereof, and the replacement of the solvent is carried out at a temperature of from 0* to 30*C.

31. The process of claim 29 wherein the gelling liquid contains a plasticizer or a monomeric or polymeric additive.

32. A process of preparing a gelled cellulose triacetate product, which process comprises:

a. providing a polymer solution comprising i. cellulose triacetate with an acetyl content greater than about 42 percent, ii. more than 75 percent by weight of a nonhydrolyzing acidic water-miscible solvent, and iii. up to 10 percent by weight of a diluent additive;

b. forming the polymer solution into a product form;

c. immersing the formed product directly into an excess of an alcohol, glycol or polyol as a gelling liquid for a time sufficient to replace substantially all of the solvent with the gelling liquid, and at a temperature sufficient to provide a gelled product containing cellulose triacetate as the polymer phase and the gelling liquid as the liquid phase, the gelled product being ultramicroporous and in film and fiber form, transparent and self-supporting; and

d. recovering the gelled product.

33. The process of claim 32 wherein the solvent is an acidic phenolic compound, the gelling liquid is methanol, and the replacement is carried out at a temperature below 40*C.

34. The process of claim 1 which includes the step of replacing the first and subsequent gelling liquids from the gelled product of the first and subsequently recovered gelled products by contacting the gelled product with a second or subsequent gelling liquid, each of which is a nonsolvent for the cellulose triacetate and which is miscible with the prior gelling liquid to be replaced for a time sufficient to permit the replacement of the prior gelling liquid to obtain a gelled product containing cellulose triacetate as the polymer phase and the last gelling liquid as the liquid phase. 35. The process of claim 34 wherein the gelling liquid comprises a polymerizable liquid, a plasticizer, transformer oil, mineral oil, benzene, xylene or a hydrocarbon.

36. The process of preparing a gelled cellulose triacetate product, which process comprises:

a. providing a polymer solution comprising cellulose triacetate with an acetyl content greater than about 42 percent, and a major amount of a nonhydrolyzing acidic solvent for the cellulose triacetate;

b. forming the polymer solution into a configuration of the product;

c. introducing the formed product into contact with an excess of a first gelling liquid which is both a nonsolvent for the cellulose triacetate and miscible with the solvent used for a period of time, so as to replace substantially the entire solvent in the formed product with the first gelling liquid, the replacement carried out at a temperature low enough to provide an ultramicroporous gelled product having distinct interpenetrating polymer and liquid phases, which in film or fiber form is flexible, transparent and self-supporting; and

d. contacting the gelled product containing the first gelling liquid with a second gelling liquid which is not a solvent for the cellulose triacetate, but which is miscible in the first gelling liquid to replace all or a part of the first gelling liquid with the second gelling liquid, the replacement carried out at a temperature to provide an ultramicroporous gelled product having distinct interpenetrating polymer and liquid phases, with the second gelling liquid as the liquid phase.

37. The process of claim 36 wherein the first gelling liquid is a volatile liquid and the second gelling liquid is a nonvolatile liquid.

38. The process of claim 36 wherein the second gelling liquid is a polymerizable liquid, a plasticizer, an alcohol, a glycol, polyol, mineral oil, transformer oil or a hydrocarbon.

39. The process of claim 36 wherein the first gelling liquid is water and the second gelling liquid is an alcohol.

40. The process of claim 36 wherein the first gelling liquid is an alcohol and the second gelling liquid is a hydrocarbon or a plasticizer.

41. The process of claim 36 wherein the first gelling liquid comprises methanol and the second gelling liquid comprises a nonaqueous methanol-miscible liquid.

42. The process of claim 35 which includes replacing the second gelling liquid with a third and subsequent gelling liquid in the same manner as the first liquid is replaced by the second.

43. The process of claim 42 wherein the first, second and third gelling liquids are respectively an alcohol, a hydrocarbon and a nonvolatile oil or plasticizer.

44. The process of claim 42 which includes forming the polymer solution into a fiber form, and removing all or a portion of the second or subsequent gelling liquid from the gelled fiber under tension.

45. The process of claim 36 which includes casting the polymer solution onto a supporting substrate and recovering a gelled film containing the second or a subsequent gelling liquid.

46. A gelled, deacidified, cellulose triacetate product composed of:

a. an interpenetrating cellulose triacetate polymer phase and a gelling liquid phase;

b. which product is ultramicroporous;

c. the gelling liquid phase susceptible to replacement by another nonsolvent gelling liquid which is miscible with the gelling liquid phase;

d. the liquid phase composed of a major amount of the gelling liquid;

e. the product self-supporting in film or fiber form; and

f. the product, on removal of the liquid phase without tension, irreversibly shrinkable.

47. The product of claim 46 wherein the gelling liquid in the liquid phase comprises more than 75 percent by weight of the gelled cellulose triacetate product.

48. The product of claim 46 wherein the cellulose triacetate comprises no more than 25 percent by weight of the product.

49. The product of claim 46 wherein the gelled cellulose triacetate is characterizEd by having the property of being elongated by 30 to 70 percent without rupture of the gelled cellulose triacetate product.

50. The product of claim 46 in oriented dried film or fiber form.

51. The product of claim 46 wherein the gelling liquid in the liquid phase contains a plasticizer, a polymerizable liquid or a polymer.

52. The product of claim 46 in film or fiber form which is characterized as transparent, flexible and self-supporting.

53. The product of claim 46 wherein the gelling liquid in the liquid phase comprises water, alcohol, glycol, polyol, a hydrocarbon, a plasticizer, an ester, an ether, mineral oil, a high dielectric liquid or combinations thereof.

54. The product of claim 46 wherein the gelling liquid comprises methanol, ethanol, benzene, xylene, ethylene glycol, glycerine, chlorobenzene, methyl isobutyl ketone and combinations thereof.

55. The product of claim 46 wherein the gelled cellulose triacetate is in film form and secured to or impregnated into a woven or nonwoven fibrous material.

56. The product of claim 46 in dried fiber form, the fiber dried under tension and characterized by a tensile strength of greater than 30,000 psi. and exhibiting optical birefringence.

57. The gelled product of claim 46 wherein the gelling liquid in the liquid phase comprises a volatile and a nonvolatile liquid, the nonvolatile liquid subject to evaporation on heating, with the nonvolatile liquid remaining as the liquid phase.

58. The gelled product of claim 46 wherein the product contains a polymeric additive in amounts which do not exceed the cellulose triacetate content.

59. The gelled product of claim 46 wherein the gelling liquid in the liquid phase is an organic liquid which is miscible with methanol.

60. The gelled product of claim 46 characterized by a hydrophobic surface, and wherein the gelling liquid is water.

61. The gelled product of claim 46 which comprises the gelled product in flexible film form secured to a supporting sheet material, and wherein the gelling liquid in the liquid phase is a high dielectric liquid, the gelled product suitable for use as a dielectric sheet material.