EP0950744B1 - Verbesserungen zum Herstellen van Vliesstoffen mit einem elektrostatischen geladenen Transportband - Google Patents

Verbesserungen zum Herstellen van Vliesstoffen mit einem elektrostatischen geladenen Transportband Download PDF

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Publication number
EP0950744B1
EP0950744B1 EP19980123893 EP98123893A EP0950744B1 EP 0950744 B1 EP0950744 B1 EP 0950744B1 EP 19980123893 EP19980123893 EP 19980123893 EP 98123893 A EP98123893 A EP 98123893A EP 0950744 B1 EP0950744 B1 EP 0950744B1
Authority
EP
European Patent Office
Prior art keywords
conveyor
filaments
web
polarity
charge
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19980123893
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English (en)
French (fr)
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EP0950744A1 (de
Inventor
Jian Weng
Marlene Storzer
Richard L. Ferencz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Avintiv Specialty Materials Inc
Original Assignee
Polymer Group Inc
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Filing date
Publication date
Application filed by Polymer Group Inc filed Critical Polymer Group Inc
Publication of EP0950744A1 publication Critical patent/EP0950744A1/de
Application granted granted Critical
Publication of EP0950744B1 publication Critical patent/EP0950744B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
    • D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
    • D04H3/16—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T19/00—Devices providing for corona discharge

Definitions

  • This invention relates to improvements in production efficiencies of a nonwoven web in a process wherein fibers or filaments of a polymer are continuously deposited on a porous moving conveyor and are consolidated into a fabric.
  • Nonwoven fabrics comprise fibers or filaments which are formed as a flat web and are bonded together by processes other than weaving. Some processes start with individual fibers, which are carded or otherwise formed into a web and bonded by the use of heat or adhesives. In other processes, referred to as meltblowing or spunbonding or variants thereof, a molten polymer is extruded from a spinning head to produce strands, and a high flow of air is employed to elongate or attenuate the strands. The strands, in the form of continuous filaments or fibers, are then collected on a porous moving conveyor for subsequent processing.
  • Spunbond webs have been produced for more than thirty years, and the basic techniques for producing such webs are well known, as exemplified in U.S. patent no. 3,302,237, 3,325,906, 3,655,305, 3,502,763, 5,397,413 and many others, incorporated herein by reference.
  • the production of meltblown webs for example, is described in U.S. patent no. 3,849,241.
  • Spunbond and meltblown webs may be combined to form a single fabric, as described in U.S. patent no. 4,041,203.
  • These layered fabrics can be produced on a single line, and are referred to, for example, as SM, SMS, and SMMS fabrics, with the letter designating the type of fabric, spunbond and meltblown.
  • GB 1 087 410 discloses an apparatus and a process for the production of a nonwoven web, which uses said apparatus, comprising a porous moving conveyor of dielectric material, means for applying a web of filament onto the conveyor and means for applying electrostatic charges to the filaments and the conveyor so that the filaments are attracted to the conveyor.
  • a web of continuous filaments is produced and deposited on a moving porous conveyor in the form of a continuous web.
  • the filaments carry an electrostatic charge of a first polarity, usually negative, which is either acquired or externally applied.
  • the porous conveyor belt is made from a dielectric material.
  • a charge of an opposite polarity is applied to the conveyor belt in an area just upstream of the deposit of the filaments. The filaments are thus attracted to and adhere to the belt.
  • the charge to the conveyor belt is preferably applied by an insulated bar spaced from the belt and having a series of high voltage electrodes.
  • a second electrostatic bar may be positioned over the moving web at a location just prior to deposit of the second layer.
  • An electrostatic charge of a given polarity, for example, positive, is applied to the web in order to attract the negatively charged filaments deposited at the second location.
  • press rolls are used to compress the web at various locations, these rolls may comprise a dielectric surface which is charged with a polarity which will repel the charge carried by the fiber web, thus preventing pick-up of the web by the roll.
  • a neutralizing bar may be positioned across the web near the exit end of the conveyor.
  • An opposite polarity charge may be applied to the web to neutralize the attractive forces between the web and the conveyor, in order to facilitate the removal of the web for subsequent bonding.
  • the method and apparatus of the present invention provide many direct and important benefits, such as allowing operation of a spunbond line at higher rates of speed and higher basis weights, with substantially fewer defects, as well as improved basis weight uniformity.
  • Figure 1 generally shows a pair of spaced spunbond lines or beams 10 and 12, with a meltblown line 14 positioned between the two beams.
  • a molten polymer such as a polyolefin (polyethylene or polypropylene or various blends), polyester, polyamides, and the like are heated and pressurized by an extruder 16 in lines 10 and 12.
  • the molten polymer is fed through filter 18 and gear pump 20 to an extrusion head or spin beam 22 containing a spaced array of small extrusion openings to produce a large number of continuous filaments 24.
  • the filaments are initially cooled by the surrounding air and are passed through a slot drawing device 26 charged with a high flow of air from a suitable source 27.
  • the device 26 comprises a downwardly tapering passage causing elongation or attenuation of the filaments.
  • the filaments exit the slot attenuator in finer form, as shown at 28, whereupon they are deposited on a porous conveyor belt 30.
  • the meltblowing station 14 has a comparable operation, in that an extruder 32 forces molten polymer through a filter 34 and a pump 36 into an extrusion head 38 containing small orifices. In this case, however, hot air from a suitable source 40 is impinged on the extruded polymer near the point of extrusion. This typically produces fine fibers 42, which are deposited directly on the spunbond web of filament 28. The final spunbond beam 12 then deposits a final layer of filaments 44 on the meltblown layer.
  • the composite three layer web 45, moving on the conveyor belt 30 is then transferred off the belt to a bonding station, such as a pair of heated calendar rolls 46, on of which rolls is embossed, to point bond some of the filaments and fibers in the web.
  • a suction box 48 is provided beneath the porous conveyor belt 30 to allow the filaments or fibers, moving in high velocity air, to be evenly deposited on the conveyor.
  • a charging bar 50 containing a large number of electrodes arranged in a line in an insulating material, is connected to a high voltage source adjustable up to 30 KV or higher.
  • the charging bar 50 has a length coextensive with the filament array and is spaced from the filaments 28.
  • a ground bar 52 is spaced from the filaments 28 on the other side.
  • the filaments receive a charge, usually a negative charge from a DC voltage source, as they pass through the gap. This corona charge causes the like-charged filaments to repel each other and causes a more uniform web to be deposited.
  • press rolls 54 are usually employed downstream of the area of deposit to compress the web prior to the deposit of the next layer.
  • the web tends to cling to these rolls, causing unacceptably defects, with the problem increasing heavier basis weights and higher line speeds.
  • the same problem may arise when the web is transferred from the exit end of the conveyor to the bonding station.
  • the second spunbond layer When the second spunbond layer is deposited, it carries a charge having the same polarity as the web on the conveyor, and the two layers tend to repel each other.
  • an electrostatic charge of opposite polarity to that on the spunbond filaments, is applied to the conveyor belt 30 just upstream of the area of deposit of the filaments.
  • the belt is made of a nonconductive or dielectric fabric, such as an open mesh woven polyester fabric.
  • a static charging bar 60 having a large number of pointed electrodes is positioned closely adjacent to the conveyor belt 30, and the bar 60 is coextensive with the width of the belt. It has been found that the bar should be positioned between one and four inches (2,54 and 10,16cm) from the belt at a DC charge level of 20-30 kV from a power source 61. If the bar is too close to the belt, or is operated at higher voltage, arcing can occur. If the bar is too far away from the belt, or is operated at a lower voltage, an ineffective charge is applied. In the embodiment shown, the charge bar 60 is positioned adjacent the conveyor as it passes over a grounded return roll of the conveyor. Since the filaments 28 carry a negative charge, a positive charge is applied to the fabric of the conveyor. This causes the filaments to be attracted more strongly to the conveyor and to lie in a flatter relationship with the conveyor surface.
  • the first web of filaments 28 may be provided with an additional static charge just prior to deposit of the second layer 44.
  • This is likewise accomplished by positioning a second charging bar 64 above the width of the conveyor upstream of the second beam 12 and applying a positive charge to the first layer, which will attract the negatively charged second layer 44.
  • a ground plate 66 is placed beneath the conveyor opposite the charge bar 64 to cause movement of ions toward the surface of the web.
  • additional charging bars 68 may be located adjacent to the rolls to induce a charge on the rolls to repel the web.
  • a neutralizing charging bar may be positioned across the web, such as at 70, near the exit of the web from the conveyor, to reduce or neutralize the charge on the web, in order to facilitate transfer of the web to the bonding station. For example, if the web carries a net positive charge at this stage, a negative charge will be applied, to at least partially neutralize the charge on the web.
  • the charging bars and power supplies employed herein are commercially available, for example, from SIMCO in Hatfield, PA, U.S.A. These devices are commonly referred as corona discharging devices.
  • a trial was run using a conveyor contaminated with drips, with the electrostatic power off and then turned on.
  • a Measurex system was used to quantify web defects. Use of the system of the present invention resulted in a reduction of defects by 75%, or from one in every 3,000 linear yards (914,40 m) to one in every 12,402 linear yards (3780,13 m). This indicates that filaments are being attracted to the clogged areas, even though no suction is available.
  • the basis weight of the web was also continuously evaluated with the system turned off and on. It is desirable to produce a web of uniform basis weight.
  • the range of weights was 13.91 to 22.54 with charging of the conveyor turned off and 14.2 to 20.62 with the system turned on.
  • the system of the present invention offers several important and immediate benefits in the production of spunbond nonwovens and composites. These benefits include higher production rates at higher basis weights, fewer defects, and less down time, for example, due to clogged conveyor belts.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Nonwoven Fabrics (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

Claims (5)

  1. Vorrichtung zur Herstellung eines Vliesstoffes, wobei die Vorrichtung ein poröses Förderband (30) aus dielektrischem Material, eine erste Einrichtung (10) zum Aufbringen einer ersten Bahn aus dielektrischen Polymerfasern (28) auf das Förderband (30), wobei die Polymerfasern (28) eine elektrostatische Ladung einer ersten Polarität tragen und an einer ersten Stelle auf dem Förderband (30) abgelagert werden, eine erste von dem Förderband (30) beabstandete Einrichtung (60) zum Aufbringen einer elektrostatischen Ladung mit einer Polarität, die entgegengesetzt zu der Polarität der Ladung auf den Fasern (28) ist, wodurch die Fasern (28) an das Förderband (30) angezogen werden, eine zweite Einrichtung (12) zum Aufbringen einer Bahn aus dielektrischen Polymerfasern (44) auf das Förderband (30), die von der ersten Einrichtung (10) beabstandet ist, wobei die zweite Bahn aus Fasern eine elektrostatische Ladung der ersten Polarität trägt und auf dem Förderband (30) an einer zweiten Stelle abgelagert wird, die von der ersten Stelle beabstandet ist, und eine zweite Einrichtung (64) enthält, die von dem Förderband (30) gleich vor der zweiten Stelle angeordnet ist, zum Aufbringen einer elektrostatischen Ladung auf die erste Bahn und das Förderband (30), die eine Polarität hat, die entgegengesetzt zu der ersten Polarität ist, wodurch die zweite Bahn aus Fasern (44) an die erste Bahn angezogen wird.
  2. Vorrichtung nach Anspruch 1, wobei das Förderband einen Ausgang enthält, und eine Einrichtung (70) vorgesehen ist, um die Ladung zwischen den Fasern und dem Förderband (30) nahe dem Ausgang zu neutralisieren.
  3. Vorrichtung nach Anspruch 1, wobei die Einrichtung zum Aufbringen einer Bahn von dielektrischen Polymerfasern auf das Förderband (30) eine Spunbondvorrichtung (10;12) enthält.
  4. Vorrichtung nach Anspruch 1, wobei eine Walze (54) unter Druck an der ersten Bahn von Fasern anliegt und wobei eine Einrichtung (68) vorgesehen ist, um die Fläche der Walze mit derselben Polarität wie die erste Polarität der Fasern elektrostatisch zu laden, wodurch die Fasern von der Walze abgestoßen werden.
  5. Verfahren zur Herstellung einer geschichteten Spunbondbahn, wobei das Verfahren die Schritte des Ablagerns einer ersten Schicht gesponnener Polymerfasern (28) auf einem laufenden porösen, dielektrischen Förderband (30) an einer ersten Stelle und des Ablagerns einer zweiten Schicht von gesponnenen Polymerfasern (44) auf der ersten Schicht an einer zweiten Stelle stromabwärts im Abstand von der ersten Stelle, wobei die erste und die zweite Schicht aus Fasern dieselbe elektrostatische Ladung einer ersten Polarität tragen, des Aufbringens einer elektrostatischen Ladung auf das Förderband (30) mit einer Polarität, die entgegengesetzt zu der ersten Polarität ist, gleich stromaufwärts der ersten Stelle, und des Aufbringens einer elektrostatischen Ladung mit einer Polarität entgegengesetzt zu der ersten Polarität auf die erste Schicht und das Förderband (30) gleich stromaufwärts der zweiten Stelle aufweist.
EP19980123893 1998-04-17 1998-12-16 Verbesserungen zum Herstellen van Vliesstoffen mit einem elektrostatischen geladenen Transportband Expired - Lifetime EP0950744B1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US175711 1988-03-31
US8210198P 1998-04-17 1998-04-17
US82101P 1998-04-17
US17571198A 1998-10-20 1998-10-20

Publications (2)

Publication Number Publication Date
EP0950744A1 EP0950744A1 (de) 1999-10-20
EP0950744B1 true EP0950744B1 (de) 2004-03-03

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EP19980123893 Expired - Lifetime EP0950744B1 (de) 1998-04-17 1998-12-16 Verbesserungen zum Herstellen van Vliesstoffen mit einem elektrostatischen geladenen Transportband

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DE (1) DE69822127T2 (de)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6709623B2 (en) 2000-12-22 2004-03-23 Kimberly-Clark Worldwide, Inc. Process of and apparatus for making a nonwoven web
US20030208886A1 (en) * 2002-05-09 2003-11-13 Jean-Louis Monnerie Fabric comprising shaped conductive monofilament used in the production of non-woven fabrics
US7488441B2 (en) 2002-06-15 2009-02-10 Kimberly-Clark Worldwide, Inc. Use of a pulsating power supply for electrostatic charging of nonwovens
US7504060B2 (en) 2003-10-16 2009-03-17 Kimberly-Clark Worldwide, Inc. Method and apparatus for the production of nonwoven web materials
US8333918B2 (en) 2003-10-27 2012-12-18 Kimberly-Clark Worldwide, Inc. Method for the production of nonwoven web materials
US20060012084A1 (en) * 2004-07-13 2006-01-19 Armantrout Jack E Electroblowing web formation process
DE102008024000A1 (de) * 2008-05-18 2009-12-17 Jonas & Redmann Automationstechnik Gmbh Verfahren zum Festhalten von flachem Transportgut an der Transportfläche eines Bandriemens eines Transportbandes
EP2157034A1 (de) * 2008-08-22 2010-02-24 GKD-Gebr. Kufferath AG Prozessband, Verfahren zum Herstellen von Papier oder Vlies und Verwendung eines Prozessbands
WO2014150998A1 (en) * 2013-03-15 2014-09-25 Wm. Wrigley Jr. Company Low density chewing gum and systems and processes for making such
CN112226907A (zh) * 2020-10-09 2021-01-15 常州聚武机械有限公司 一种无纺布多功能生产设备

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3387326A (en) * 1964-06-04 1968-06-11 Du Pont Apparatus for charging and spreading a web
US4208366A (en) * 1978-10-31 1980-06-17 E. I. Du Pont De Nemours And Company Process for preparing a nonwoven web
US5597645A (en) * 1994-08-30 1997-01-28 Kimberly-Clark Corporation Nonwoven filter media for gas

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Publication number Publication date
DE69822127D1 (de) 2004-04-08
DE69822127T2 (de) 2005-02-03
EP0950744A1 (de) 1999-10-20

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