Self-bonded nonwoven web and porous film composites

• US 5,208,098 A
• Filed: 10/23/1990
• Issued: 05/04/1993
• Est. Priority Date: 10/23/1990
• Status: Expired due to Term

• Current Assignee: Propex Operating Company LLC (Solmax International Incorporated)
• Original Assignee: Amoco Corporation (BP PLC)
• Inventors: Stover, Walter H.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US07/601,519
• Time in Patent Office: 924 Days
• Field of Search: 428/332, 428/348, 428/474.4, 428/475.2, 428/480, 428/482, 428/296, 428/288, 428/903, 428/219, 428/284, 428/286, 428/297, 428/298, 428/171, 428/172, 428/287
• US Class Current: 442/398
• CPC Class Codes: B32B 2305/026 Porous
• CPC Class Codes: B32B 2305/20 in the form of a non-woven mat
• CPC Class Codes: B32B 2307/724 Permeability to gases, adsorption
• CPC Class Codes: B32B 2307/7265 Non-permeable
• CPC Class Codes: B32B 2323/10 Polypropylene
• CPC Class Codes: B32B 2607/02 Wall papers, wall coverings
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: E04D 12/002 Sheets of flexible material, e.g. roofing tile underlay
• CPC Class Codes: Y10T 428/24603 Fiber containing component
• CPC Class Codes: Y10T 428/24612 Composite web or sheet
• CPC Class Codes: Y10T 442/678 Olefin polymer or copolymer sheet or film [e.g., polypropylene, polyethylene, ethylene-butylene copolymer, etc.]

Abstract

A self-bonded nonwoven web and porous film composite comprising at least one layer of a self-bonded, fibrous nonwoven web comprising substantially continuous filaments adhered to at least one layer of a polymeric porous film and having vapor-permeable and liquid-impermeable properties.

Claims

1. A self-bonded nonwoven web and porous film composite comprising,

at least one layer of a uniform basis weight self-bonded, fibrous nonwoven web comprising a plurality of substantially randomly disposed, substantially continuous thermoplastic filaments wherein said web has a Basis Weight Uniformity Index of 1.0±

0.05 determined from average basis weights having standard deviations of less than 10%, adhered to

at least one layer of a vapor-permeable polymeric porous film.

2. The composite of claim 1 wherein said Basis Weight Uniformity Index is 1.0±

0.03 determined from average basis weights having standard deviations of less than 10%.

3. The composite of claim 1 wherein said filaments have deniers in the range of about 0.5 to about 20.

4. The composite of claim 1 wherein said self-bonded web comprises a thermoplastic selected from the group consisting of polypropylene, high-density polyethylene, low density polyethylene, linear low density polyethylene, polyamide, polyester, a blend of polypropylene and polybutene and a blend of polypropylene and linear low density polyethylene.

5. The composite of claim 4 wherein said uniform basis weight self-bonded nonwoven web comprises a polypropylene.

6. The composite of claim 4 wherein said uniform basis weight self-bonded web comprises a blend of a polypropylene and a polybutene wherein said polypropylene has a weight ratio of about 0.99 to about 0.85 and wherein said polybutene has a number average molecular weight in the range of about 300 to about 2,500 and has a weight ratio of about 0.01 to about 0.15.

7. The composite of claim 4 wherein said uniform basis weight self-bonded web comprises a blend of a polypropylene and a linear low density polyethylene wherein said polypropylene has a weight ratio of about 0.99 to about 0.85 and wherein said linear low density polyethylene has a density in the range of about 0.91 to about 0.94 g/cc and has a weight ratio of about 0.01 to about 0.15.

8. The composite of claim 1 wherein said porous film comprises a propylene-based resin or a low density polyethylene and has a moisture vapor transmission rate of about 100 g/m² /24 hr or greater as determined according to ASTM E-96, procedure E.

12. The composite of claim 1 in the form of a protective fabric having vapor-permeable and liquid-impermeable properties.

9. A self-bonded nonwoven web and porous film composite having a basis weight in the range of about 0.2 oz/yd² or greater comprising,

at least one layer of a uniform basis weight self-bonded, fibrous nonwoven web having a basis weight of about 0.1 oz/yd² or greater and a Basis Weight Uniformity Index of 1.0±

0.05 determined from average basis weights having standard deviations of less than 10% comprising a plurality of substantially randomly disposed, substantially continuous thermoplastic filaments wherein said filaments comprise a thermoplastic selected from the group consisting of polypropylene, high-density polyethylene, low density polyethylene, linear low density polyethylene, polyamide, polyester, a blend of polypropylene and polybutene and a blend of polypropylene and linear low density polyethylene adhered to

at least one layer of a polymeric vapor-permeable porous film having a basis weight of 0.1 oz/yd² or greater and a moisture vapor transmission rate of about 2,000 g/m² /24 hr or greater as determined according to ASTM E-96, procedure E, comprising an oriented porous film comprising a low density polyethylene or propylene-based resin comprising a blend of about 70 to 100 wt % of a polypropylene and about 30 to 0 wt % of an ethylene-propylene copolymer having an ethylene content of about 10 to about 50 wt %.

10. The composite of claim 9 wherein said filaments have deniers in the range of about 0.5 to about 20.

11. The composite of claim 9 having a basis weight of about 1.0 to about 4.0 oz/yd² comprising two layers of a polypropylene self-bonded nonwoven web and one layer of the oriented propylene-based resin vapor-permeable porous film located between and bonded to the two layers of the self-bonded web.

13. The composite of claim 9 in the form of an air-infiltration barrier.

14. A self-bonded nonwoven web and porous film composite having a basis weight in the range of about 1.0 to about 6.0 oz/yd² comprising,

at least two layers of a uniform basis weight self-bonded, fibrous nonwoven web having a basis weight of about 0.25 oz/yd² or greater and a Basis Weight Uniformity Index of 1.0±

0.05 determined from average basis weights having standard deviations of less than 10% comprising a plurality of substantially randomly disposed, substantially continuous thermoplastic filaments wherein said filaments comprise a thermoplastic selected from the group consisting of polypropylene, a blend of polypropylene and polybutene and a blend of polypropylene and linear low density polyethylene and said webs are adhered to

at least one layer of an oriented vapor-permeable polymeric porous film having a basis weight of 0.5 oz/yd² or greater comprising a blend of about 70 to 100 wt % of a polypropylene and about 30 to 0 wt % of an ethylene-propylene copolymer having an ethylene content of about 10 to about 50 wt % and formed by the steps of;

(a) forming a homogeneous blend of a propylene-based resin and about 0.5 to about 10 ppm of a nucleating agent capable of producing beta-spherulites,

(b) extruding the blend into a film having a thickness of about 0.01 to about 0.4 millimeters on a cast film line having a chill roll temperature of about 90°

to about 130°

C.,

(c) cooling the film below the crystallization temperature of the propylene-based resin to form at least 20 wt % beta-spherulites in the film,

(d) extracting beta-spherulites corresponding to at least 15 wt % of the blend from the cast film by immersing the cast film in a toluene bath at a temperature of about 85°

to about 95°

C. for a time period of 10 minutes or less to form a porous film and drying the porous film at a temperature of about 15°

to about 110°

C. for 20 minutes or less, and

(e) orienting the porous film be heating the porous film at a temperature of about 115°

to about 135°

C. for a time period of about 2 to about 20 seconds and stretching the heated porous film in at least one direction at a stretch ratio of about 1.5 to about 7.5 to form the oriented porous film.

15. The composite of claim 14 wherein said oriented porous film has a moisture vapor transmission rate of about 2,000 g/m² /24 hr or greater as determined according to ASTM E-96, procedure E.

16. The composite of claim 14 wherein said propylene-based resin comprises a polypropylene having a melt flow rate of about 1.0 to about 10 as measured by ASTM D-1238 or a blend of about 70 to about 80 wt % of a polypropylene having a melt flow rate of about 1.0 to about 10 as measured by ASTM D-1238 and about 20 to about 30 wt % of an ethylene-propylene copolymer having an ethylene content of about 10 to about 50 wt % and having a melt flow rate of about 0.5 to about 10 as measured by ASTM D-1238.

17. The composite of claim 14 in the form of a vapor-permeable and liquid-impermeable construction fabric.