Polypropylene fibers and fabrics

Patent metadata

Field	Value
Publication number	US-9322114-B2
Application number	US-201213691984-A
Country	US
Kind code	B2
Filing date	Dec 3, 2012
Priority date	Dec 3, 2012
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

This invention relates to polypropylene fibers and fabrics containing polypropylene fibers, the fibers comprising propylene polymers comprising at least 50 mol % propylene, said polymers having: a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 dg/min to about 25 dg/min; b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8)] at 190° C. from about 1.5 to about 30; c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 190° C., 1° C./min, where said polymer has 0 wt % nucleating agent present), of at least about 123° C.; d) an average meso run length determined by 13 C NMR of at least about 55 or higher; and e) optionally, a loss tangent, tan δ, [defined by Eq. (2)] at an angular frequency of 0.1 rad/s at 190° C. from about 14 to about 70.

First claim

What is claimed is:

1. A nonwoven fabric comprising polypropylene fibers, wherein said polypropylene fibers comprise a propylene polymer comprising at least 50 mol % propylene, said polymer having:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 dg/min to about 21.5 dg/min;
b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8) herein] at 190° C. from about 1.5 to about 28;
c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 1° C./min as described herein, where said polymer has 0 wt % nucleating agent present), of at least about 131° C.; and
d) an average meso run length determined by 13 C NMR of at least about 97 or higher.

2. A nonwoven fabric according to claim 1 , wherein said polypropylene fibers are present in an amount of at least 50% by weight, preferably at least 75% by weight, based on the total weight of fibers in said nonwoven fabric.

3. A nonwoven fabric according to claim 1 , having a fabric basis weight in the range of 5 to 70 gsm, preferably 7 to 15 gsm.

4. A nonwoven fabric according to claim 1 , having a tensile strength anisotropy defined as the ratio of the specific tensile strength in the MD over the specific tensile strength in the CD of less than about 2.7.

5. A nonwoven fabric according to claim 1 , having a total hand of less than about 6.8 gr.

6. A nonwoven fabric according to claim 1 , having a MD tensile modulus (as defined herein) of less than about 35 N/5 cm/gsm.

7. A nonwoven fabric according to claim 1 , having a CD specific tensile strength of at least 1.0 N/5 cm/gsm, a MD specific tensile strength of at least 2.7 N/5 cm/gsm and a total hand of less than about 6.8 gm force or a tensile modulus of less than about 32 N/5 cm/gsm.

8. A nonwoven fabric according to claim 7 , having a fabric tensile anisotropy (ratio of MD over CD specific tensile strength as defined herein) of less than about 2.7.

9. A nonwoven fabric according to claim 1 , having a CD specific tensile strength of at least 1.1 N/5 cm/gsm, MD specific tensile strength of at least 2.9 N/5 cm/gsm, and total hand of less than about 6.6 gm force or MD tensile modulus of less than about 30 N/5 cm/gsm.

10. A nonwoven fabric according to claim 1 , wherein said propylene polymer has:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 14 dg/min to about 19 dg/min;
b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8) herein] at 190° C. from about 2.5 to about 6.5;
c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 1° C./min as described below, where said polymer has 0 wt % nucleating agent present), of at least about 136° C.; and
d) an average meso run length determined by 13 C NMR of from 97 to 140.

11. A nonwoven fabric according to claim 1 , wherein the fibers have a dpf value of from 0.3 to 5 dpf.

12. A nonwoven fabric according to claim 1 , comprising a plurality of nonwoven layers that are bonded together.

13. A nonwoven fabric according to claim 1 , wherein said fibers comprise a propylene polymer composition comprises a combination of two or more propylene polymers.

14. A nonwoven fabric according to claim 1 , wherein said nonwoven fabric is a spunbonded nonwoven.

15. A nonwoven fabric according to claim 1 , wherein said nonwoven fabric is a meltblown nonwoven.

16. A nonwoven fabric according to claim 1 , comprising a laminate comprising a plurality of nonwovens each independently selected from spunbonded nonwovens and meltblown nonwovens.

17. A nonwoven fabric according to claim 1 , wherein the propylene polymer composition comprises a propylene polymer having an Mw/Mn of 1 to 7, and/or an Mz/Mw of 1.5 to 2.5.

18. A nonwoven fabric having a fabric basis weight of not more than 15 gsm and comprising polypropylene fibers having a dpf value of 0.3 to 5 dpf, wherein said polypropylene fibers comprise a propylene polymer composition comprising at least 50 mol % propylene, said polymer composition having:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 to 25 dg/min
b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8)] at 190° C. from 1.5 to 30
c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 1° C./min as described below, where said polymer has 0 wt % nucleating agent present), of at least about 123° C. and
d) an average meso run length determined by 13 C NMR of at least about 55 or higher.

19. A nonwoven fabric according to claim 18 , said nonwoven fabric being obtainable by spun-bonding with a production line speed of at least 400 m/min.

20. A nonwoven fabric according to claim 18 , wherein said fabric has a fabric tensile anisotropy as defined herein of less than 3.0 when produced at a production line speed of 900 m/min.

21. A nonwoven fabric having a fabric basis weight of not more than 15 gsm and comprising polypropylene fibers having a dpf value of 0.3 to 5 dpf, wherein:
said nonwoven fabric is obtainable by spun-bonding with a production line speed of at least 400 m/min;
said polypropylene fibers are composed of a propylene polymer composition comprising at least 50 mol % propylene, said polymer composition having:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 to 25 dg/min
b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8)] at 190° C. from 1.5 to 30
c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 1° C./min as described below, where said polymer has 0 wt % nucleating agent present), of at least about 123° C. and
d) an average meso run length determined by 13 C NMR of at least about 55 or higher; and
said fabric has a ratio of CD elongation to CD peak Strength of 40 or more (when measured at speed of 200 mm/min, 100 mm gauge length) and a CD strength of 1.0 N/5 cm/gsm or more (when measured at speed of 100 mm/min, 200 mm gauge length).

22. A nonwoven fabric according to claim 21 having a CD strength of Y N/5 cm/gsm or more, where Y=−0.0005(X)+1.41 (preferably 1.45, preferably 1.5, preferably 1.6), where X is the production line speed of fabric and is at least 400 m/min.

23. A nonwoven fabric according to claim 21 , obtainable by spunbonding with a line speed of at least 600 m/min.

24. A laminate fabric comprising a nonwoven fabric according to claim 21 and at least one further fabric layer.

25. A polypropylene fiber comprising a propylene polymer comprising at least 50 mol % propylene, said polymer having:
a) a melt flow rate (MFR, ASTM 1238, 230° C., 2.16 kg) of about 10 dg/min to about 21.5 dg/min;
b) a dimensionless Stress Ratio/Loss Tangent Index R 2 [defined by Eq. (8) herein] at 190° C. from about 1.5 to about 28;
c) an onset temperature of crystallization under flow, T c,rheol , (as determined by SAOS rheology, 1° C./min as described herein, where said polymer has 0 wt % nucleating agent present), of at least about 131° C.; and
d) an average meso run length determined by 13 C NMR of at least about 97 or higher.

26. A fiber according to claim 25 , having a dpf value of from 0.3 to 5 dpf.

27. A fiber according to claim 25 , wherein the fiber is a yarn comprising a plurality of polypropylene filaments having a dpf value of from 0.3 to 5 dpf.

28. A fiber according to claim

Assignees

• Exxonmobil Chem Patents Inc
• Reifenhäuser Gmbh & Co Kg Maschinenfabrik
• Reifenhaeuser Masch

Inventors

• Macdonald Jeanne Marie
• Doufas Antonios K
• Sarrazin Jerome
• Ferry William Michael
• Kulkarni Rahul Ravindra
• Thurman Derek Wade
• Mitchell Cynthia Ann
• Frey Detlef
• Schlag Peter
• Geus Hans-Georg
• Cinquemani Claudio

Classifications

• Y10T442/68

  Melt-blown nonwoven fabric · CPC title

• Y10T442/696

  Including strand or fiber material which is stated to have specific attributes [e.g., heat or fire resistance, chemical or solvent resistance, high absorption for aqueous compositions, water solubility, heat shrinkability, etc.] · CPC title

• Y10T428/2904

  Staple length fiber · CPC title

• Y10T442/60

  Nonwoven fabric [i.e., nonwoven strand or fiber material] · CPC title

• D04H3/14

  with bonds between thermoplastic yarns or filaments produced by welding · CPC title