WO2007121458A2 - procédé et appareil pour la production de nanofibres soufflées à chaud - Google Patents

procédé et appareil pour la production de nanofibres soufflées à chaud Download PDF

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Publication number
WO2007121458A2
WO2007121458A2 PCT/US2007/066847 US2007066847W WO2007121458A2 WO 2007121458 A2 WO2007121458 A2 WO 2007121458A2 US 2007066847 W US2007066847 W US 2007066847W WO 2007121458 A2 WO2007121458 A2 WO 2007121458A2
Authority
WO
WIPO (PCT)
Prior art keywords
spinning
plate
orifices
polymer
flow
Prior art date
Application number
PCT/US2007/066847
Other languages
English (en)
Other versions
WO2007121458A3 (fr
Inventor
James E. Brang
Arnold Wilkie
Jeff Haggard
Original Assignee
Hills, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from US11/736,399 external-priority patent/US10041188B2/en
Application filed by Hills, Inc. filed Critical Hills, Inc.
Priority to EP07760821.4A priority Critical patent/EP2019875B1/fr
Priority to JP2009506734A priority patent/JP5439170B2/ja
Publication of WO2007121458A2 publication Critical patent/WO2007121458A2/fr
Publication of WO2007121458A3 publication Critical patent/WO2007121458A3/fr

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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D4/00—Spinnerette packs; Cleaning thereof
    • D01D4/02—Spinnerettes
    • D01D4/025—Melt-blowing or solution-blowing dies
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/08—Melt spinning methods
    • D01D5/098—Melt spinning methods with simultaneous stretching
    • D01D5/0985—Melt spinning methods with simultaneous stretching by means of a flowing gas (e.g. melt-blowing)

Definitions

  • the present invention pertains to improved methods and apparatus for producing polymeric nanofibers and, more particularly to improvements in meltblown technology that permit production of polymeric nanofibers of small cross-section at a rate suitable for commercial operation.
  • the invention also encompasses webs and fabrics produced by the aforesaid methods and apparatus.
  • nanofibers refers to fibers with “diameters” (i.e., maximum transverse cross-section dimension) less than 0.5 microns (i.e., 0.5 x 10 "6 meters).
  • Typical polymeric nanofibers have diameters between 50 and 300 nanometers (i.e., between 0.05 x 10 "6 and 0.3 x 10 "6 meters).
  • Nanofibers provide for improved barrier fabrics for clothing and other applications, such as filtering. Only small quantities of nanofibers on the surface of meltblown fabrics greatly enhance liquid retention and decrease water contact angle. Other factors such as air resistance and breathability are also favorably impacted as nanofibers are added to a nonwoven fabric.
  • nanofibers have had limited commercial applicability, primarily because the production costs are too high.
  • the most common technique currently used for commercially producing nanofibers is electrospinning.
  • a polymer is typically dissolved in a solvent (although polymer melts may also be used) and placed in a glass pipette tube sealed at an upstream end and having a small opening in a necked-down portion at the downstream end.
  • a high voltage >50kV
  • This process can produce nanofibers with diameters as low as fifty nanometers, although the collected web usually contains fibers with varying diameters from fifty nanometers to two microns.
  • the production rate of this process is very low and is typically measured in grams per hour, much too low to have wide commercial applicability.
  • concentration of polymer in the solvent tends to be low (on the order of 10%) thereby further reducing the effective production rate and, if the system is operated at high volume, the operator is forced to contend with significant amounts of solvent and noxious off-gas byproducts. Further, switching the type of polymer that can be used in this process typically requires extensive machine modifications
  • meltblown webs have fiber diameters ranging from about one micron to ten microns. These webs are typically used for filtration applications, and the lowest possible fiber diameters are desirable because they offer better filtration efficiencies.
  • Conventional meltblown spinning technology is limited to two microns because of the inability to make sufficiently small spin holes (i.e., spinning orifices). Typically, the spin hole diameters cannot be made smaller than approximately 0.005 inch and have an L/D (length over diameter) ratio of less than approximately 10.
  • the spinneret disclosed in that patent includes a plate having channels etched or otherwise defined in a surface thereof, each channel having a downstream end extending to the edge of the plate.
  • the plate surface is covered with a similarly configured plate (i.e., with correspondingly defined passages) or a flat plate to define closed flow passages, and the downstream ends serve as a lineal array of spinning orifices at the plate edge.
  • Molten polymer is delivered to the upstream ends of the passages from a polymer source through a filter.
  • the outflowing polymer filaments or fibers flow parallel to the plate surfaces in which the spinning orifices are defined.
  • this type of spinneret will be referred to as a plate edge orifice spinneret (i.e., having plate edge spinning orifices in a linear array) to distinguish it from the spinneret type such as disclosed in U. S. Patent No. 5,162,074 (Hills) in which the filaments are spun perpendicularly to the spinneret plate surface from which they emanate.
  • Plate edge orifice spinnerets have been unable to produce fibers having diameters smaller than about 0.8 microns. It would be extremely valuable from a commercial perspective to be able to produce nanofibers from a meltblown process using plate edge orifice spinnerets with a commercially practical productivity rate.
  • a plate edge orifice spinneret i.e., a system of the general type disclosed in U. S. Patent No. 6,833,104
  • a plate edge orifice spinneret is significantly modified to provide spinning orifices having a large L/D (length divided by diameter) ratio with a very small spinning orifice diameter, and is operated with a throughput or polymer flow rate that is very low.
  • the density of the small spinneret orifices can be increased, a feature that is enabled by the small spin hole diameter.
  • cross-section of the spin holes is typically not circular and that the "D" dimension as used herein is intended to mean the maximum transverse cross-section dimension of the spin hole.
  • the present invention utilizes a plate edge orifice spinneret wherein: the spin hole L/D ratios are 20/1 or greater, preferably as high as 200/1 or even 1 ,000/1 ; flow rates less are than 0.01 ghm (grams per hole per minute); and spin holes are arranged in linear arrays with a density of 99 holes per inch or more, in some cases greater than 199 holes per inch.
  • the present invention enhances meltblown technology of the type described in the aforementioned Berger patent to allow production of a nonwoven web with the same size nanofibers as those produced by electrospinning processes.
  • the end product is the same but the production rate is much higher, the cost is much lower and there are no byproduct noxious fumes.
  • a greater variety of polymers can be used without extensive machine modifications.
  • webs can be made with most of the fibers less than 0.5 micron in diameter and at production rates of 1.5 kg/meter/hour or higher.
  • Fig. 1 is a partially schematic view in longitudinal section of a preferred embodiment of a spinning assembly employing a plate edge orifice spinneret according to one aspect of the invention.
  • Fig. 2 is an enlarged detail view in longitudinal section of the outlet end of the assembly of Fig. 1.
  • Fig. 3 is a top view in plan of the channeled surface of one of the plates of the plate edge orifice spinneret employed in the assembly of Fig. 1.
  • Fig. 4 is an enlarged detail view in plan of a portion of the channeled surface of Fig. 3.
  • Fig. 5 is a view in elevation of a potion of the edge of the plate edge orifice spinneret of Fig. 3 showing the array of spin holes.
  • a pump 10 delivers molten polymer received from a polymer inlet 11 to pump block 13 where the polymer is metered and delivered to an inlet manifold 15 of a meltblown spinneret pack 17.
  • the meltblown spinneret pack 17 comprises a first block 19 and a second block 20 secured in close relation to one another along respective surfaces and to respective air jet blocks 23, 24 proximate the downstream or outflow end of the unit.
  • Between blocks 19 and 20 there is a thin plate spinneret 21 which, in the preferred and illustrated embodiment, comprises two thin plates 21a and 21b joined flush against one another in any suitable manner.
  • Thin plates 21a and 21b have shallow channels and passages etched or otherwise formed in their abutting surfaces in a pattern that is the same for both plates. Thus, when the plates are superposed, one on the other, each plate provides one half of each flow region or passage for the overall thin plate spinneret.
  • the only significant difference between plates 21a and 21 b is the through hole or opening 26 defined in plate 21a serving as in inlet for the thin plate spinneret to receive molten polymer from inlet manifold 15 through a filter 16 extending across the downstream end of manifold 15.
  • the channels and passages formed in plate 21a include a spinneret reservoir region 25 for receiving polymer at elongated opening 26 from filter 16 (Fig. 2).
  • Opening 26 extends most of the length of plate 21a, and inflowing polymer is directed into reservoir region 25 in a direction transverse to the length dimension of opening 26.
  • Each spin hole 30 is formed by two superposed semi-cylindrical, rectangular or other shaped recesses in the plates 21a and 21b.
  • the spinneret plates are secured together by any conventional manner such a bonding, clamping, welding, etc.
  • Relatively large spaces are provided between spinneret block 19 and air jet block 23, and between spinneret block 20 and air jet block 24, upstream of edge 28 to define respective reservoirs 35 and 36 for receiving pressurized draw air in a conventional manner from an air supply (not shown).
  • These reservoirs deliver the draw air through significantly narrower spaces between the blocks serving as wide air nozzles 37, 38 extending into the plane of the drawings in Figs. 1 and 2.
  • Nozzles 37, 38 are directed at converging similar angles relative the linear array of spin holes 30 and have their downstream ends terminating at edge 28 along respective sides of that linear array to issue the draw air angularly toward the spun nanofibers as the fibers emanate from spin holes 30.
  • the component described above are similar in many respects to those described in the aforementioned Berger patent, although it should be noted that the preferred embodiment disclosed in that patent produces bicomponent fibers of greater thickness than nanofibers, whereas the preferred embodiment of the present invention is concerned with producing homopolymer nanofibers.
  • the spinneret in the Berger patent includes two polymers being fed to the spinning section from opposite sides of that section, the primary embodiment disclosed herein is typically a homopolymeric spinneret wherein a single polymer is delivered to the thin plate 21.
  • the present invention can also be used to produce bicomponent or multicomponent nanofibers, in which case the assembly may be modified to deliver different polymers to the spinneret plate.
  • An important aspect of the invention is the ratio (L/D) of the length L of each spin hole to the diameter (or maximum transverse cross-section dimension) D of that hole is very large in comparison to the ratios employed in prior art units.
  • L/D ratios of at least 20 are employed.
  • the L/D ratio is in excess of 200, or even 1 ,000.
  • Another important feature of the invention is that the flow rate of polymer through the unit is far lower that used in conventional systems.
  • Pump block 13 delivers the molten polymer to the spinneret at a flow rate per spin hole that is less than 0.01 ghm.
  • the low throughput of polymer resulting from this low flow rate is compensated for by the fact that the very small spin hole diameters permits high lineal densities of the spin holes 30. Specifically, densities on the order of one hundred spin holes per inch and greater can readily be achieved, thereby enabling a commercially realizable productivity from a machine of reasonable size. In some cases spin hole densities on the order of two hundred holes per inch can be achieved. In one preferred embodiment, the following parameters are employed:
  • Polymer Polypropylene having an 1800 MFI (melt flow index) Operating Temperature: 250 0 C
  • the unit has a density of about 100 spin holes per inch, a flow rate of 0.007 ghm, D is approximately 0.005" (0.127 mm), L is approximately 0.3" (7.62 mm) - (L/D ⁇ 60), the polymer is PP-1800 MFI and the operating temperature is 250°C.
  • acceptable parameter ranges are at least the following: Polymer flow rate: less than 0.01 ghm
  • Polymer Any melt spinnable polymer including, but not limited to PP; PET; PA-6; PA 6-6; PE; HDPE; UHMWPE; TPU; LCP; PFE; Co- PET; Co-PA; PLA Operating Temperature: As necessary to melt polymer to flowability, typically 250 0 C or greater.
  • the flow passages forming the spin holes 30 are typically photo-chemically etched in the surfaces of the thin spinneret plates 21a and 21 b. However, other known techniques for defining small passages in metal or other solid surfaces may be employed.
  • the spin holes 30 must be long to develop back pressure for even polymer flow distribution.
  • polymer operating pressures on the order, preferably, of at least 400 psi are required.
  • the apparatus of the invention in a broad sense, may be viewed as a meltblown spinneret die that has the spin holes formed by grooves in the surface of plate(s) where the polymer exits at the edge of the plate.
  • the grooves are smaller than 0.005" wide x 0.004" deep and have an L/D at least as large as 20:1.
  • the tip of the spin hole has a flat section 0.002" x 0.030" across the spin hole.
  • the method of the invention in a broad sense, may be viewed as a meltblown process for making a web of fibers that are mostly less than 0.5 microns in diameter by extruding polymer into the meltblown die described above. Any melt spinnable polymer may be employed.
  • the invention may also be viewed as including a meltblown fabric having fibers mostly less than 0.5 microns in diameter, preferably made using the method and apparatus described above. Also included in the invention is a fabric comprising spunbond and meltblown layers with one or more of the meltblown layers being a meltblown fabric having fibers mostly less than 0.5 microns in diameter.
  • the production rate of nanofibers using the present invention may be low compared to the production rate for producing conventional larger fibers using conventional meltblown technology.
  • the present invention has much higher nanofibers production rates.
  • electrospinning is a solvent spinning process wherein the concentration of polymer tends to be low in the solvent, typically on the order of ten percent.
  • the production is low, and if performed to produce large volume, the resulting solvent and noxious off-gas byproducts must be dealt with.
  • One manufacturer who employs electrospinning to produce polymeric nanofibers reports production rates on the order of 10,000 square meters per day. The present invention exceeds that rate by orders of magnitude.
  • two etched plates 21a and 21b are employed.
  • the plates are typically positioned to align the flow channels and regions and then bonded together to form a single spinneret plate 21.
  • the plates need not be bonded together but instead can be clamped, bolted, glued, or otherwise secured to one another. If the plates are not bonded, cleaning of the flow channel is more easily accomplished by separating the plates.
  • spin holes as small as those used herein tend to clog more readily than spin holes of conventional size, making a non-bonding approach more appealing for cleaning purposes.
  • the present invention may be embodied either way (either with bonded or non-bonded plates).
  • the flow passages can be defined in the surface of only one plate, and that surface would be covered by a flat plate secured thereto. Also, if two etched plates are used, they can be superposed with the channels forming the spin holes slightly offset in a transverse direction so that each channel is part of two spin holes and, thereby, the spin hole density can be approximately doubled.
  • Each array could share a common set of air knives, or preferably have its own set of air knives, to heat the extruded fibers.
  • a single linear array of spin holes is shown in the preferred embodiment; however, it will be understood that two or more parallel arrays can be employed as the application requires.
  • the preferred embodiment is described in terms of recessed channels or grooves defined in the surface of one or more plates.
  • the flow regions and passages can be formed as through holes defined entirely through a plate and sealed by additional plate surfaces disposed adjacent opposite plate sides.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Textile Engineering (AREA)
  • Nonwoven Fabrics (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

Abstract

L'invention concerne un procédé et un appareil pour la production de nanofibres polymériques utilisant une filière soufflée à chaud ayant des orifices de filage formés par des rainures dans une ou plusieurs surfaces d'une plaque ou de plusieurs plaques où un polymère sort au niveau d'un ou de plusieurs bords de ladite ou desdites plaques. Les rainures sont inférieures à 0,005 in. en largeur x 0,004 in. en profondeur et ont un L/D d'au moins 20:1. Les débits du polymère à travers l'appareil sont très faibles, de l'ordre de 0,01 ghm ou moins. Les produits du procédé/appareil peuvent également être vus comme comprenant un tissu soufflé à chaud ayant des fibres pour la plupart inférieures à 0,5 micron en diamètre.
PCT/US2007/066847 2006-04-18 2007-04-18 procédé et appareil pour la production de nanofibres soufflées à chaud WO2007121458A2 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP07760821.4A EP2019875B1 (fr) 2006-04-18 2007-04-18 Procede et appareil pour la production de nanofibres soufflees a chaud
JP2009506734A JP5439170B2 (ja) 2006-04-18 2007-04-18 メルトブローンナノファイバの生産のための方法および装置

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US79269106P 2006-04-18 2006-04-18
US60/792,691 2006-04-18
US89493907P 2007-03-15 2007-03-15
US60/894,939 2007-03-15
US11/736,399 2007-04-17
US11/736,399 US10041188B2 (en) 2006-04-18 2007-04-17 Method and apparatus for production of meltblown nanofibers

Publications (2)

Publication Number Publication Date
WO2007121458A2 true WO2007121458A2 (fr) 2007-10-25
WO2007121458A3 WO2007121458A3 (fr) 2008-06-12

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2204349A1 (fr) * 2008-12-26 2010-07-07 Korea Institute of Science and Technology Nano-poudre, nano-encre et micro-tige, et leurs procédés de fabrication
WO2010081832A1 (fr) 2009-01-13 2010-07-22 INSERM (Institut National de la Santé et de la Recherche Médicale) Nappe de nanofibres biomimétiques, procédé et dispositif de fabrication associés
WO2011091251A3 (fr) * 2010-01-22 2011-09-15 Fiber Web, Inc. Filière de filage de fibre fabriquée par extrusion-soufflage
US8206484B2 (en) 2008-08-13 2012-06-26 Dow Global Technologies Llc Process for producing micron and submicron fibers and nonwoven webs by melt blowing
US8365925B2 (en) 2008-08-13 2013-02-05 Dow Global Technologies Llc Filter medium
US8524796B2 (en) 2008-08-13 2013-09-03 Dow Global Technologies Llc Active polymer compositions

Citations (2)

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US5162074A (en) 1987-10-02 1992-11-10 Basf Corporation Method of making plural component fibers
US6833104B2 (en) 1999-02-17 2004-12-21 Hills, Inc. Method and apparatus for spinning a web of mixed fibers, and products produced therefrom

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US3849241A (en) * 1968-12-23 1974-11-19 Exxon Research Engineering Co Non-woven mats by melt blowing
US3825380A (en) * 1972-07-07 1974-07-23 Exxon Research Engineering Co Melt-blowing die for producing nonwoven mats
KR100549140B1 (ko) * 2002-03-26 2006-02-03 이 아이 듀폰 디 네모아 앤드 캄파니 일렉트로-브로운 방사법에 의한 초극세 나노섬유 웹제조방법
US20050053782A1 (en) * 2003-09-04 2005-03-10 Ayusman Sen Process for forming polymeric micro and nanofibers

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5162074A (en) 1987-10-02 1992-11-10 Basf Corporation Method of making plural component fibers
US6833104B2 (en) 1999-02-17 2004-12-21 Hills, Inc. Method and apparatus for spinning a web of mixed fibers, and products produced therefrom

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP2019875A4

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8206484B2 (en) 2008-08-13 2012-06-26 Dow Global Technologies Llc Process for producing micron and submicron fibers and nonwoven webs by melt blowing
US8365925B2 (en) 2008-08-13 2013-02-05 Dow Global Technologies Llc Filter medium
US8524796B2 (en) 2008-08-13 2013-09-03 Dow Global Technologies Llc Active polymer compositions
EP2204349A1 (fr) * 2008-12-26 2010-07-07 Korea Institute of Science and Technology Nano-poudre, nano-encre et micro-tige, et leurs procédés de fabrication
WO2010081832A1 (fr) 2009-01-13 2010-07-22 INSERM (Institut National de la Santé et de la Recherche Médicale) Nappe de nanofibres biomimétiques, procédé et dispositif de fabrication associés
WO2011091251A3 (fr) * 2010-01-22 2011-09-15 Fiber Web, Inc. Filière de filage de fibre fabriquée par extrusion-soufflage

Also Published As

Publication number Publication date
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