US4496508A
Expired / Lapsed
US
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Method for manufacturing polypropylene spun-bonded fabrics with low draping coefficient
Assignee: Carl Freudenberg KG
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Filing: 1982-09-10
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Granted: 1985-01-29
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Expires: 2002-09-10
Abstract
Abstract The present invention provides a method for manufacturing polypropylene spun-bonded fabrics, which method involves preparing a polypropylene melt at a temperature of about 240° to 280° C. and forming polypropylene filaments by extruding this melt through a spinning nozzle at an extrusion velocity of about 0.02 meter/second to 0.2 meter/second. The spinning nozzle, or spinneret, has holes with a diameter less than 0.8 millimeter. The filaments thus formed are subsequently quenched by transversely blowing air at a temperature between about 20° to 40° C. The filaments are also aerodynamically withdrawn by means sufficient to create a filament withdrawal velocity between about 20 meters/second and 60 meters/second. The ratio of the extrusion velocity to the withdrawal velocity (herein defined as the deformation ratio) is between about 1:200 and 1:1000. These aerodynamically withdrawn filaments are then deposited onto a moving porous support in order to form a continuous web. This web is then bonded by suitable means, forming a finished spun-bonded nonwoven fabric.
Inventors
- 👤 Ludwig Hartmann
- 👤 Ivo Ruzek
- 👤 Engelbert Locher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:17
CPC Classifications
D; D04; D04H; D04H3/00; D04H3/005; D04H3/007; D04H3/08; D04H3/16; Y; Y10; Y10T; Y10T442/00; Y10T442/60; Y10T442/681
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
210 words
A method for manufacturing polypropylene spun-bonded fabrics, from partially-drawn polypropylene filaments, comprising: preparing a polypropylene melt at a temperature of about 240° C. to 280° C.; forming polypropylene filaments by extruding the melt through a spinning nozzle at an extrusion velocity of about 0.02 meters/second to about 0.20 meters/second, said spinning nozzle having holes with a diameter less than about 0.8 millimeter; allowing the filaments extruded from the lower edge of the spinning nozzles to fall vertically a distance of at most about 0.8 meter; quenching the filaments by means of transversely blowing air over said filaments at a temperature between about 20° C. to about 40° C.; aerodynamically drawing the extruded filaments by means suffieient to create a filament withdrawal velocity between about 20 meters/second and 60 meters/second, and such that the ratio of the extrusion velocity to the withdrawal velocity is between about 1:200 and 1:1000; forming a fabric web by depositing the aerodynamically drawn filaments onto a moving porous support that has a vacuum beneath it creating suction; and bonding the fabric web to provide the spun-bnded fabric, wherein said aerodynamically drawn filaments have a maximum tensile elongation of at least about 200%, and have a fiber shrinkage determined in boiling water of less than about 10%.
Claim 2
Independent Claim
210 words
A method for manufacturing polypropylene spun-bonded fabrics, from partially-drawn polypropylene filaments, comprising: preparing a polypropylene melt at a temperature of about 240° C. to 280° C.; forming polypropylene filaments by extruding the melt through a spinning nozzle at an extrusion velocity of about 0.02 meters/second to about 0.20 meters/second, said spinning nozzle having holes with a diameter less than about 0.8 millimeter; allowing the filaments extruded from the lower edge of the spinning nozzles to fall vertically a distance of at most about 0.8 meter; quenching the filaments by means of transversely blowing air over said filaments at a temperature between about 20° C. to about 40° C.; aerodynamically drawing the extruded filaments by means suffieient to create a filament withdrawal velocity between about 20 meters/second and 60 meters/second, and such that the ratio of the extrusion velocity to the withdrawal velocity is between about 1:200 and 1:1000; forming a fabric web by depositing the aerodynamically drawn filaments onto a moving porous support that has a vacuum beneath it creating suction; and bonding the fabric web to provide the spun-bnded fabric, wherein said aerodynamically drawn filaments have a maximum tensile elongation of at least about 200%, and have a fiber shrinkage determined in boiling water of less than about 10%.
Claim 3
Dependent Claim
76 words
A method according to claim 1 wherein the polypropylene is atactic polypropylene having a molecular weight distribution such that at a temperature of about 280° C., and a shear velocity of about 362 l/s, said atactic polypropylene has a melt viscosity of about 45 Pa.sec+3%, at a shear velocity of about 3600 l/s, the melt viscosity is about 14 Pa.sec+2%, and at a shear velocity of about 14,480 l/s, the melt viscosity is about 6 Pa.sec+1.5%.
Claim 4
Dependent Claim
52 words
The method according to claim 1 wherein the cross-sectional area of the means which aerodynamically withdraws the filaments is adjusted relative to the number of filaments, so that light bundles constantly alternating between about 2 to 5 filaments each are formed, and the bundles are randomly deposited on the moving porous support.
Claim 5
Dependent Claim
47 words
A method according to claim 1 wherein the fabric web is bonded by means of a calender which comprises an engraved and a smooth cylinder, at a temperature of between about 130° C. and 160° C., and a line pressure of between about 40 and 500 N/cm.
Claim 6
Dependent Claim
31 words
A method according to claim 1, further comprising treatment of the spun-bonded fabric with a suitable wetting agent to provide the fabric with a surface tension of about 35×10 -5 N/cm.
Claim 7
Dependent Claim
19 words
The method according to claim 1 wherein the filaments have a maximum tensile elongation of at least about 400%.
Claim 8
Dependent Claim
25 words
The method according to claim 1 wherein the spun-bonded fabrics are characterized by a draping coefficient of less than or equal to 1.65 (area weight)+30%.
Claim 9
Dependent Claim
31 words
A method according to claim 1 wherein the filament withdrawal velocity is about 10 to 20 times the velocity of the moving porous support on which the fabric web is formed.
Claim 10
Dependent Claim
31 words
A method according to claim 2 wherein the filament withdrawal velocity is about 10 to 20 times the velocity of the moving porous support on which the fabric web is formed.
Claim 11
Dependent Claim
63 words
A method according to claim 1 further comprising oscillation of the aerodynamically drawn filaments as they are deposited onto the moving porous support, and wherein ths oscillation is characterized by a velocity vector transverse to the moving support's velocity vector, and also wherein said transverse velocity vector has a value between about 0 and 2 times that of the moving support's velocity vector.
Claim 12
Dependent Claim
63 words
A method according to claim 2 further comprising oscillation of the aerodynamically drawn filaments as they are deposited onto the moving porous support, and wherein this oscillation is characterized by a velocity vector transverse to the moving support's velocity vector, and also wherein said transverse velocity vector has a value between about 0 and 2 times that of the moving support's velocity vector.
Claim 13
Dependent Claim
63 words
A method according to claim 8 further comprising oscillation of the aerodynamically drawn filaments as they are deposited onto the moving porous support, and wherein this oscillation is characterized by a velocity vector transverse to the moving support's velocity vector, and also wherein said transverse velocity vector has a value between about 0 and 2 times that of the moving support's velocity vector.
Claim 14
Dependent Claim
63 words
A method according to claim 9 further comprising oscillation of the aerodynamically drawn filaments as they are deposited onto the moving porous support, and wherein this oscillation is characterized by a velocity vector transverse to the moving support's velocity vector, and also wherein said trasverse velocity vector has a value between about 0 and 2 times that of the moving support's velocity vector.
Claim 15
Independent Claim
26 words
A method according to any one of claims 1, 2, 8, 9, 10, 11, 12 and 13 wherein said fabric web has a crossed parallel texture.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-01-29 | 1988-07-30 | 1989-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-29 | 1992-07-30 | 1993-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-29 | 1996-07-30 | 1997-01-29 | $7700.00 | Window Closed / Lapsed |