Oriented polymeric articles and method

• US 9,134,471 B2
• Filed: 06/28/2006
• Issued: 09/15/2015
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Johnston, Raymond P., Insley, Thomas I.
• Primary Examiner(s): OCHYLSKI, RYAN M
• Application Number:
  US11/427,149
• Publication Number:
  US 20080014410A1
• Time in Patent Office: 3,366 Days
• Field of Search: 264/1.34, 264/1.36, 264/1.6, 264/435, 264/436, 264/464, 264/465, 264/466, 264/469, 264/479, 264/483, 264/484, 264/108, 264/138, 264/146, 264/147, 264/148, 264/151, 264/164, 264/167, 264/212, 264/214, 264/299, 264/310
• US Class Current: 1/1
• CPC Class Codes: B29C 33/62 based on polymers or oligomers
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 55/00 Shaping by stretching, e.g. drawing through a die; Apparatus therefor B29C61/08 takes precedence
• CPC Class Codes: B29C 55/06 parallel with the direction of feed
• CPC Class Codes: B29C 59/04 using rollers or endless belts
• CPC Class Codes: B29C 71/0081 using an electric field, e.g. for electrostatic charging electrostatic pinning of extruded material B29C48/9165; fixing linings by electrostatic charges B29C63/0043
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29L 2031/731 Filamentary material, i.e. comprised of a single element, e.g. filaments, strands, threads, fibres cables B29L2031/707
• CPC Class Codes: C08J 2323/12 Polypropene
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: D01D 5/423 by fibrillation of films or filaments
• CPC Class Codes: G02B 5/30 Polarising elements light-modulating devices with active elements G02F1/00
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249986 Void-containing component contains also a solid fiber or solid particle
• CPC Class Codes: Y10T 428/2973 Particular cross section
• CPC Class Codes: Y10T 428/2978 Surface characteristic

Abstract

Stretched articles, such as oriented polymeric films or fibers, having microstructure features on at least one surface thereof, and processes for making such articles, are disclosed. A method of making fibers comprises forming a polymeric film having a body having a first surface and a second surface and having a longitudinal dimension. The film also comprises a plurality of elongate microstructure features disposed on the first surface of the body in a direction substantially parallel to the longitudinal dimension of the body, wherein the elongate microstructure features are substantially parallel. The method further comprises stretching the polymeric film in a direction substantially parallel to the longitudinal dimension of the body, and fibrillating the stretched polymeric film along the longitudinal dimension of the body to provide one or more fibers, wherein each fiber has at least one microstructure feature thereon.

Claims

1. A method of making fibers comprising:

forming a polymeric film having

a body having a first surface and a second surface and having a longitudinal dimension, and

a plurality of elongate microstructured surface features disposed on the first surface of the body in a direction substantially parallel to the longitudinal dimension of the body, wherein the microstructured surface features are substantially parallel;

stretching the polymeric film in a direction substantially parallel to the longitudinal dimension of the body; and

separating the stretched polymeric film along generally longitudinally disposed separation lines to define a plurality of discrete fiber elements, wherein one or more of the fiber elements have at least one microstructured surface feature thereon.

2. The method of claim 1, and further comprising:

exposing the polymeric film to an electric field.

3. The method of claim 2 wherein the exposing step defines the film as an electret.

4. The method of claim 3, wherein the forming step further comprises:

defining the shape of at least one of the microstructure features to enhance electrical field effects.

5. The method of claim 2 wherein the exposing step precedes the stretching step.

6. The method of claim 2 wherein the stretching step precedes the exposing step.

7. The method of claim 1, wherein the body has a first thickness and the microstructure features have a second thickness, and wherein after stretching, the ratio of the first thickness to the second thickness is at most 2.

8. The method of claim 1 wherein the forming step further comprises:

defining the longitudinal separation lines on the polymeric film.

9. The method of claim 1, and further comprising:

laterally cutting the fiber elements;

mixing the cut fiber elements; and

forming a filtration layer of mixed fiber elements.

10. The method of claim 1 wherein at least one microstructure feature is continuous along the first surface of the body.

11. The method of claim 1 wherein at least one microstructure feature is discontinuous along the first surface of the body.

12. The method of claim 1 wherein at least two adjacent microstructure features are spaced apart laterally by a separation span of the body.

13. The method of claim 12 wherein at least one of the separation lines extends within one of the separation spans and is spaced laterally from the microstructure features on each side of that separation span.

14. The method of claim 1 wherein at least one of the fiber elements has a plurality of microstructure features thereon.

15. The method of claim 1 wherein at least one microstructure feature has a discontinuity.

16. The method of claim 1 wherein at least one microstructure feature has a plurality of discontinuities.

17. The method of claim 1, wherein the forming step further comprises:

defining at least one generally laterally disposed lateral separation line across the longitudinal dimension of the body; and

separating each fiber element into one or more fiber element segments.

18. The method of claim 17 wherein the film separating and fiber element separating steps occur simultaneously.

19. The method of claim 1, and further comprising:

maintaining the plurality of discrete fiber elements in an array having a substantially parallel fiber element alignment.

20. A method of making fibers comprising:

forming a polymeric film having

a body having a first surface and a second surface and having a longitudinal dimension, and

a plurality of elongate microstructured surface features disposed on the first surface of the body in a direction substantially parallel to the longitudinal dimension of the body, wherein the elongate microstructured surface features are substantially parallel;

stretching the polymeric film in a direction substantially parallel to the longitudinal dimension of the body; and

fibrillating the stretched polymeric film along the longitudinal dimension of the body to provide one or more fibers, wherein each fiber has at least one microstructured surface feature thereon.

21. The method of claim 20, and further comprising:

exposing the polymeric film to an electric field.

22. The method of claim 21 wherein the exposing step defines the film as an electret.

23. The method of claim 22, wherein the forming step further comprises:

defining the shape of at least one of the microstructure features to enhance electrical field effects.

24. The method of claim 21 wherein the exposing step precedes the fibrillating step.

25. The method of claim 21 wherein the fibrillating step precedes the exposing step.

26. The method of claim 20, wherein the body has a first thickness and the microstructure features have a second thickness, and wherein after stretching, the ratio of the first thickness to the second thickness is at most 2.

27. The method of claim 20 wherein the fibrillating step separates the stretched polymeric film into fibers along generally longitudinal separation lines, and wherein the forming step further comprises:

defining the longitudinal separation lines on the polymeric film.

28. The method of claim 20, and further comprising:

laterally cutting the fibers;

mixing the cut fibers; and

forming a filtration layer of mixed fibers.

29. The method of claim 20 wherein at least one microstructure feature is continuous along the first surface of the body.

30. The method of claim 20 wherein at least one microstructure feature is discontinuous along the first surface of the body.

31. The method of claim 20 wherein the fibrillating step separates the stretched polymeric film into fibers along generally longitudinal separation lines, and wherein at least some adjacent microstructure features are spaced apart laterally by a separation span of the body.

32. The method of claim 31 wherein at least one of the separation lines extends within one of the separation spans and is spaced laterally from the microstructure features on each side of that separation span.

33. The method of claim 20 wherein at least one of the fibers has a plurality of microstructure features thereon.

34. The method of claim 20 wherein at least one microstructure feature has a discontinuity.

35. The method of claim 20 wherein at least one microstructure feature has a plurality of discontinuities.

36. The method of claim 20, wherein the forming step further comprises:

defining at least one generally laterally disposed lateral separation line across the longitudinal dimension of the body; and

separating each fiber into one or more fiber segments.

37. The method of claim 36 wherein the fibrillating and fiber separating steps occur simultaneously.

38. The method of claim 20, and further comprising:

maintaining the fibers in an array having a substantially parallel fiber alignment.