Elastic nonwoven webs and method of making same

• US 5,470,639 A
• Filed: 02/03/1992
• Issued: 11/28/1995
• Est. Priority Date: 02/03/1992
• Status: Expired due to Term

• Current Assignee: Fiberweb Holdings Limited (Berry Global Group Inc.)
• Original Assignee: Fiberweb North America, Inc.
• Inventors: Newkirk, David D., Gessner, Scott L., Thomason, Michael M., Reeder, James O.
• Primary Examiner(s): CANNON, JAMES
• Application Number:
  US07/829,923
• Time in Patent Office: 1,394 Days
• Field of Search: 428/296, 428/288, 428/152, 428/286, 428/287, 428/302, 156/62.4, 156/161, 156/176, 156/181, 156/229, 156/309.3, 604/385.2
• US Class Current: 428/152
• CPC Class Codes: D01F 6/46 of polyolefins
• CPC Class Codes: D04H 1/559 the fibres being within layered webs
• CPC Class Codes: D04H 1/56 in association with fibre formation, e.g. immediately following extrusion of staple fibres
• CPC Class Codes: D04H 3/14 with bonds between thermoplastic yarns or filaments produced by welding
• CPC Class Codes: D04H 3/16 with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
• CPC Class Codes: Y10T 428/24446 Wrinkled, creased, crinkled or creped
• CPC Class Codes: Y10T 442/602 Nonwoven fabric comprises an elastic strand or fiber material
• CPC Class Codes: Y10T 442/66 Additional nonwoven fabric is a spun-bonded fabric
• CPC Class Codes: Y10T 442/671 Multiple nonwoven fabric layers composed of the same polymeric strand or fiber material
• CPC Class Codes: Y10T 442/681 Spun-bonded nonwoven fabric

Abstract

A spunbonded elastic nonwoven fabric comprises a web of bonded thermoplastic filaments of a thermoplastic elastomer. The spunbonded fabrics of the invention are prepared in a slot draw spunbonding process operated at a rate of less than about 2000 meters per minute. The elastic fabric is used in absorbent products, such as disposable diapers, adult incontinence pads, sanitary napkins and the like, and as coverstock for absorbent personal care products.

Claims

1. A spunbonded fabric comprising a web of bonded elastomeric thermoplastic substantially continuous filaments, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull, said fabric having been prepared by a spunbonding process conducted at a rate of less than about 1,200 meters per minute.

2. A spunbonded fabric according to claim 1, said spunbonded fabric further having a root mean square average recoverable elongation of at least about 70% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and two pulls.

3. A spunbonded fabric according to claim 1, said spunbonded fabric having a root mean square average recoverable elongation of at least about 65% based on machine direction and cross direction recoverable elongation values of the fabric after 50% elongation of the fabric and one pull.

4. A spunbonded fabric according to claim 1, said spunbonded fabric further having a root mean square average recoverable elongation of at least about 60% based on machine direction and cross direction recoverable elongation values of the fabric after 50% elongation of the fabric and two pulls.

5. A spunbonded fabric according to claim 1 wherein said thermoplastic elastomeric filaments comprise an elastomer selected from the group consisting of polyurethanes, ABA block copolymers, ethylene-polybutylene copolymers, poly(ethylenebutylene) polystyrene block copolymers, polyadipate esters, polyester elastomeric polymers, polyamide elastomeric polymers, polyetherester elastomeric polymers, primarily crystalline heterophasic olefin copolymers, and polymer blends thereof.

6. A spunbonded fabric according to claim 5 wherein said polymer blends comprise a polymer selected from the group consisting of polyethylene, polypropylene, polyester, and nylon.

7. A spunbonded fabric according to claim 1 wherein said thermoplastic elastomer is an olefin-based elastomer having a melt flow rate of about 5 to about 500.

8. A spunbonded fabric according to claim 7 wherein said thermoplastic olefin-based elastomer has a swell index of about 1.8 to about 5.

9. A spunbonded fabric according to claim 7 wherein said thermoplastic olefin-based elastomer has a flexural modulus of about 200 to about 10,000 psi.

10. A spunbonded fabric according to claim 7 wherein said thermoplastic olefin-based elastomer has a flexural modulus of about 2000 to about 8000 psi.

11. A spunbonded fabric according to claim 7 wherein said thermoplastic olefin based elastomer is a primarily crystalline heterophasic olefin copolymer comprising a crystalline base polymer block and an elastomeric amorphous copolymer block attached to the crystalline base polymer via a semi-crystalline polymer block fraction.

12. A spunbonded fabric comprising a web of bonded elastomeric thermoplastic substantially continuous filaments, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull, wherein said thermoplastic elastomer is selected from the group consisting of polyurethanes, ABA block copolymer, ethylene-polybutylene copolymers, poly(ethylene-butylene) polystyrene block copolymers, polyadipate esters, polyester elastomeric polymers, polyamide elastomeric polymers, polyetherester elastomeric polymers, primarily crystalline heterophasic olefin copolymers, and polymer blends thereof, said fabric having been prepared by a spunbonding process conducted at a rate less than about 1,200 meters per minute.

13. A spunbonded fabric comprising a web of bonded theremoplastic substantially continuous filaments, said thermoplastic filaments comprising a thermoplastic olefin-based elastomer comprising a polymer having a melt flow rate of about 5 to about 500, a swell index of about 1.8 to about 5, and a flexural modulus of about 200 to about 10,000 psi, said thermoplastic olefin-based elastomer being present in said thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on average machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull.

14. A spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an elastomeric amorphous copolymer block attached to the crystalline base polymer via a semi-crystalline polymer block fraction, said thermoplastic primarily crystalline olefin heterophasic block copolymer being present in said elastomeric thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull.

15. A spunbonded fabric according to claim 14, said spunbonded fabric further having a root mean square recoverable elongation of at least about 70% based on average machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and two pulls.

16. A spunbonded fabric according to claim 14, said spunbonded fabric further having a root mean square average recoverable elongation of at least about 60% based on machine direction and cross direction recoverable elongation values of the fabric after 50% elongation of the fabric and two pulls.

17. A spunbonded fabric according to claim 14 wherein said thermoplastic filaments are prepared by a spunbonding process conducted at a rate of less than about 2000 meters per minute.

18. A spunbonded fabric according to claim 14 wherein said copolymer has a melt flow rate of about 5 to about 500.

19. A spunbonded fabric according to claim 14 wherein said copolymer has a swell index of about 1.8 to about 5.

20. A spunbonded fabric according to claim 14 wherein said copolymer has a flexural modulus of about 200 to about 10,000 psi.

21. A spunbonded fabric according to claim 14 wherein said copolymer has a flexural modulus of about 2000 to about 8000 psi.

22. A spunbonded fabric according to claim 14 wherein the crystalline base polymer block is present in said heterophasic copolymer in an amount of between about 60 and about 85 parts by weight.

23. A spunbonded fabric according to claim 14 wherein the crystalline base polymer block is present in said heterophasic copolymer in an amount of between about 65 to about 75 parts by weight.

24. A spunbonded fabric according to claim 14 wherein the crystalline base polymer block of the heterophasic copolymer is a copolymer of propylene and at least one alpha-olefin having the formula H₂ C═

CHR, where R is H or a C_2-6 straight or branched chain alkyl moiety.

25. A spunbonded fabric according to claim 14 wherein the amorphous copolymer block with elastic properties of the heterophasic copolymer is present in said heterophasic copolymer in an amount of about 10 to about 40 parts by weight.

26. A spunbonded fabric according to claim 14 wherein the amorphous copolymer block with elastic properties of the heterophasic copolymer is present in said heterophasic copolymer in an amount of about 10 to less than about 30 parts by weight.

27. A spunbonded fabric according to claim 14 wherein the amorphous copolymer block with elastic properties of the heterophasic copolymer comprises an alpha-olefin and propylene with or without a diene or a different alpha-olefin termonomer.

28. A spunbonded fabric according to claim 14 wherein the semi-crystalline copolymer block is present in said heterophasic copolymer in an amount of about 1 to less than about 15 parts by weight.

29. A spunbonded fabric according to claim 14 wherein the semi-crystalline copolymer block is a low density, essentially linear copolymer consisting substantially of units of the alpha-olefin used to prepare the amorphous block or the alpha-olefin used to prepare the amorphous block present in the greatest amount when two alpha-olefins are used.

30. A spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said bonded thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic elastic block copolymer including a crystalline base polymer block present in an amount of from about 60 to 85 parts by weight and an amorphous copolymer block with elastic properties as a second phase in an amount of from about 10 to about 40 parts by weight blocked to the crystalline base polymer block via a semi-crystalline copolymer block in an amount of from about 1 to about 15 parts by weight, said thermoplastic primarily crystalline olefin heterophasic block copolymer being present in said thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable of the fabric after 30% elongation of the fabric and one pull.

31. A disposable absorbent personal care product comprising a plurality of layers, at least one of said layers comprising a spunbonded fabric comprising a web of bonded thermoplastic substantially continuous elastomeric filaments, said spunbonded fabric having a root means square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric after one pull, wherein said bonded thermoplastic elastomeric filaments are prepared by a spunbonding process conducted at a rate of less than 1,200 meters per minutes.

32. A disposable absorbent personal care product according to claim 31 wherein said thermoplastic elastomeric filaments comprise an elastomer selected from the group consisting of polyurethanes, ABA block copolymers, ethylene-polybutylene copolymers, poly(ethylene-butylene) polystyrene block copolymers, polyadipate esters, polyester elastomeric polymers, polyamide elastomeric polymers, polyetherester elastomeric polymers, primarily crystalline heterophasic olefin copolymers, and polymer blends thereof.

33. A disposable absorbent personal care product according to claim 32 wherein said polymer blends comprise a polymer selected from the group consisting of polyethylene, polypropylene, polyester, and nylon.

34. A disposable absorbent personal care product according to claim 31 wherein said disposable absorbent personal care is a diaper or incontinence pad.

35. A disposable absorbent personal care product according to claim 31 wherein said disposable absorbent personal care is a sanitary napkin.

43. A method according to claim 32 wherein said molten elastomer is selected from the group consisting of polyurethanes, ABA block copolymers, ethylene-polybutylene copolymers, poly(ethylene-butylene) polystyrene block copolymers, polyadipate esters, polyester elastomeric polymers, polyamide elastomeric polymers, polyetherester elastomeric polymers, primarily crystalline heterophasic olefin copolymers, and polymer blends thereof.

44. A method according to claim 43 wherein said polymer blends comprise a polymer selected from the group consisting of polyethylene, polypropylene, polyester, and nylon.

36. A disposable absorbent personal care product comprising a plurality of layers, at least one of said layers comprising a spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said bonded thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block, said thermoplastic primarily crystalline olefin heterophasic block copolymer being present in said bonded thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull.

37. A medical barrier composite fabric comprising at least one meltblown fabric layer bonded to and sandwiched between opposing spunbonded fabric layers, wherein at least one of said opposing spunbonded fabric layers is an elastic spunbonded fabric comprising a web of bonded thermoplastic substantially continuous elastomeric filaments and having a root mean square average recoverable elongation of at least 75% based on machine direction and cross direction recoverable elongation values after 30% elongation of the fabric and one pull, wherein said bonded thermoplastic elastomeric filaments are prepared by a spunbonding process conducted at a rate of less than 1,200 meters per minute.

38. the medical barrier composite fabric according to claim 37 wherein said elastic spunbonded layer is maintained in a stretched condition during bonding to said meltblown layer.

39. The medical barrier composite fabric according to claim 38 comprising a plurality of thermal spot bonds for bonding of said opposing spunbonded layers and said meltblown layer to each other.

40. A medical barrier composite fabric according to claim 37 wherein said thermoplastic elastomeric filaments comprise an elastomer selected from the group consisting of polyurethanes, ABA block copolymers, ethylene-polybutylene copolymers, poly(ethylene-butylene) polystyrene block copolymers, polyadipate esters, polyester elastomeric polymers, polyamide elastomeric polymers, polyetherester elastomeric polymers, primarily crystalline heterophasic olefin copolymers, and polymer blends thereof.

41. A medical barrier composite fabric according to claim 40 wherein said polymer blends comprise a polymer selected from the group consisting of polyethylene, polypropylene, polyester, and nylon.

42. A method for producing an elastic nonwoven fabric, the method comprising:

extruding molten thermoplastic elastomer through a spinneret to form a plurality of filaments,

quenching said plurality of filaments sufficiently to produce substantially non-tacky filaments;

drawing said non-tacky filaments by contacting the non-tacky filaments with a high velocity fluid; and

collecting said as a web of bonded filaments at a rate of at least about 100 meters per minute up to about 2000 meters per minute.

45. The process of claim 42 wherein said filaments are collected at a rate of less than about 1,500 meters per minute.

46. A method for producing an elastic nonwoven fabric, the method comprising:

extruding molten thermoplastic polymer through a spinneret to form a plurality of filaments, said molten thermoplastic polymer comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block in an amount sufficient to provide a fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull;

quenching said plurality of filaments sufficiently to produce substantially non-tacky filaments;

drawing said non-tacky filaments by contacting the non-tacky filaments with a high velocity fluid; and

collecting said filaments as a web of bonded filaments.

47. A method according to claim 46 wherein the step of drawing the filaments comprises the step of contacting the filaments with a fluid at a velocity of about 0 to 100 meters per minute and gradually increasing the velocity of said fluid to at least about 1000 meters per minute.

48. A method of making a disposable absorbent personal care product, the method comprising:

providing a spunbonded fabric comprising a web of bonded thermoplastic substantially continuous elastomeric filaments, said bonded thermoplastic elastomeric filaments having been prepared by a spunbonding process conducted at a rate less than about 2000 meters per minute, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

combining said web of bonded thermoplastic substantially continuous filaments with an absorbent laminate comprising an absorbent body layer located in facing relationship with the inner surface of a substantially liquid impermeable backsheet layer.

49. A method of making a disposable absorbent personal care product, the method comprising:

providing a web of bonded thermoplastic substantially continuous elastomeric filaments, said bonded thermoplastic elastomeric filaments having been prepared by a spunbonding process conducted at a rate less than about 2000 meters per minute, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

stretching said web of bonded thermoplastic substantially continuous filaments by at least about 10% of its original size;

providing barrier properties to said web of bonded thermoplastic substantially continuous filaments; and

combining said web of bonded thermoplastic substantially continuous filaments with an absorbent article comprising an absorbent body located in facing relationship with the inner surface of a substantially liquid permeable topsheet layer.

50. A method according to claim 49 wherein the step of providing barrier properties to said web of bonded thermoplastic substantially continuous filaments comprises the step of laminating a polyolefin film to the web of bonded thermoplastic substantially continuous filaments.

51. A method of making a disposable absorbent personal care product, the method comprising:

providing a web of bonded thermoplastic substantially continuous elastomeric filaments, said bonded thermoplastic elastomeric filaments having been prepared by a spunbonding process conducted at a rate less than about 2000 meters per minute, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

stretching said first web of bonded thermoplastic substantially continuous filaments by at least about 10%;

providing barrier properties to said first web of bonded thermoplastic substantially continuous filaments while said web is in the stretched condition;

providing a second spunbonded fabric comprising a web of bonded thermoplastic elastomeric substantially continuous filaments, said bonded thermoplastic elastomeric filaments having been prepared by a spunbonding process conducted at a rate less than about 2000 meters per minute, said spunbonded fabric having a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

combining said first web and said second web with an absorbent body to form a structure having a substantially liquid impermeable backsheet layer, an absorbent inner layer and a substantially liquid permeable topsheet layer.

52. A method of making a disposable absorbent personal care product, the method comprising:

providing a spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said bonded thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block, said heterophasic copolymer being present in said elastic thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on both machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

combining said web of bonded thermoplastic substantially continuous filaments with an absorbent laminate comprising an absorbent body layer located in facing relationship with the inner surface of a substantially liquid impermeable backsheet layer.

53. A method of making a disposable absorbent personal care product, the method comprising:

providing a spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block, said heterophasic copolymer being present in said entangled thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull;

stretching said web of bonded thermoplastic substantially continuous filaments by at least about 10% of its original size;

providing barrier properties to said web of bonded thermoplastic substantially continuous filaments; and

combining said web of bonded thermoplastic substantially continuous filaments with an absorbent article comprising an absorbent body located in facing relationship with the inner surface of a substantially liquid permeable topsheet layer.

54. A method according to claim 53 wherein the step of providing barrier properties to said web of bonded thermoplastic substantially continuous filaments comprises the step of laminating a polyolefin film to the web of bonded thermoplastic substantially continuous filaments.

55. A method of making a disposable absorbent personal care product, the method comprising:

providing a first spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said bonded thermoplastic filaments comprising a thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block, said heterophasic copolymer being present in said bonded thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull;

stretching said first web of bonded thermoplastic substantially continuous filaments by at least about 10%;

providing barrier properties to said first web of bonded thermoplastic substantially continuous filaments while said web is in the stretched condition;

providing a second spunbonded fabric comprising a web of bonded thermoplastic substantially continuous filaments, said bonded thermoplastic filaments comprising thermoplastic primarily crystalline olefin heterophasic block copolymer including a crystalline base polymer block and an amorphous copolymer block with elastic properties as a second phase blocked to the crystalline base polymer block via a semi-crystalline copolymer block, said heterophasic copolymer being present in said bonded thermoplastic filaments in an amount sufficient that said spunbonded fabric has a root mean square average recoverable elongation of at least about 75% based on machine direction and cross direction recoverable elongation values of the fabric after 30% elongation of the fabric and one pull; and

combining said first web and said second web with an absorbent body to form a structure having a substantially liquid impermeable backsheet layer, an absorbent inner layer and a substantially liquid permeable topsheet layer.