WO2013159020A1 - Fibre de fluoropolymère filée par dispersion préparée à partir de polytétrafluoroéthylène non transformable à l'état fondu et de perfluoroalcoxy - Google Patents

Fibre de fluoropolymère filée par dispersion préparée à partir de polytétrafluoroéthylène non transformable à l'état fondu et de perfluoroalcoxy Download PDF

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Publication number
WO2013159020A1
WO2013159020A1 PCT/US2013/037418 US2013037418W WO2013159020A1 WO 2013159020 A1 WO2013159020 A1 WO 2013159020A1 US 2013037418 W US2013037418 W US 2013037418W WO 2013159020 A1 WO2013159020 A1 WO 2013159020A1
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WO
WIPO (PCT)
Prior art keywords
fluoropolymer
fluoropolymer fiber
particles
fiber
perfluoroalkoxy
Prior art date
Application number
PCT/US2013/037418
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English (en)
Inventor
Arthur Russell Nelson
Chester Darryl MOON
Original Assignee
Toray Fluorofibers (America), 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
Application filed by Toray Fluorofibers (America), Inc. filed Critical Toray Fluorofibers (America), Inc.
Publication of WO2013159020A1 publication Critical patent/WO2013159020A1/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
    • D01D1/00—Treatment of filament-forming or like material
    • D01D1/02—Preparation of spinning solutions
    • 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
    • D01D5/06—Wet spinning methods
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/02—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from cellulose, cellulose derivatives, or proteins
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/04—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from synthetic polymers

Definitions

  • the present invention is directed to a dispersion spun fluoropolymer fiber, and more particularly, to a dispersion spun fluoropolymer fiber prepared from non-melt processible, high molecular weight, polytetrafluoroethylene particles and perfluoroalkoxy particles.
  • Dispersion spun or wet polytetrafluoroethylene (PTFE) yarns are typically produced by forming a spin mix containing an aqueous dispersion of poly(tetrafluoroethylene) particles and a solution of a cellulosic ether matrix polymer.
  • the spin mix is then extruded at relatively low pressure (e.g., less than 150 pounds per square inch) through an orifice into a coagulation solution usually containing sulfuric acid to coagulate the matrix polymer and form an intermediate fiber structure.
  • the intermediate fiber structure once washed free of acid and salts, is passed over a series of heated rolls to dry the fiber structure and sinter the PTFE particles into a continuous PTFE filament yarn. Sintering the intermediate PTFE fiber structure causes the PTFE particles in the structure to coalesce and entangle thus forming a continuous PTFE filament fiber.
  • the present invention is directed to a dispersion spun fluoropolymer fiber including a blend of non-melt processible, high molecular weight, polytetrafluoroethylene particles and perfluoroalkoxy (PFA) particles.
  • the fluoropolymer fiber is prepared by forming an aqueous dispersion of perfluoroalkoxy particles and non-melt-processible polytetrafluoroethylene particles, the polytetrafluoroethylene particles having a standard specific gravity (SSG) of less than about 2.4.
  • SSG standard specific gravity
  • the ratio of polytetrafluoroethylene particles to perfluoroalkoxy particles in the aqueous dispersion may range from between about 6: 1 to about 3: 1, with specific ratios of 6: 1, 5: 1, 4: 1, and 3: 1.
  • the aqueous dispersion of polytetrafluoroethylene particles and perfluoroalkoxy particles is mixed with an aqueous matrix polymer solution containing a matrix polymer selected from the group consisting of methylcellulose, hydroxyethylcellulose, methylhydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, ethylcellulose and carboxymethylcellulose.
  • the mixture is then extruded into a coagulation bath containing a concentration of ions which coagulate the matrix polymer to form an intermediate fiber structure which carries ionic species. Thereafter, the intermediate fiber structure is sintered to decompose the matrix polymer and coalesce the polytetrafluoroethylene particles and the perfluoroalkoxy particles into a blended fiber.
  • the resulting, blended fluoropolymer fiber which exhibits improved properties relative to 100% dispersion spun polytetrafluoroethylene fibers, is suitable for use in bearings, bushings, fabrics, belts, diaphragms, coatings, filters and seals.
  • FIG. 1 is a differential scanning calorimeter (DSC) scan showing the melting behavior of a dispersion spun, fluoropolymer fiber prepared in accordance with the method described herein.
  • DSC differential scanning calorimeter
  • FIG. 2 is a DSC scan showing the melting behavior of a 100% PTFE dispersion spun fiber.
  • FIG. 3 shows a heat flow cool down DSC scan of the fluoropolymer of FIG. 1
  • FIG. 4 shows a heat flow cool down DSC scan of the 100% PTFE dispersion spun fiber of FIG. 2.
  • the present invention is directed to a dispersion spun fluoropolymer fiber including a blend of polytetrafluoroethylene particles and perfluoroalkoxy particles.
  • the fluoropolymer fiber is prepared by forming an aqueous dispersion of perfluoroalkoxy particles and polytetrafluoroethylene particles, mixing the dispersion with an aqueous matrix polymer solution containing a matrix polymer, extruding the mixture into a coagulation bath and forming an intermediate fiber structure.
  • the intermediate fiber structure is then sintered to decompose the matrix polymer and coalesce the polytetrafluoroethylene particles and the perfluoroalkoxy particles into a blended fiber.
  • the matrix spinning process of PTFE allows for the inclusion of an appreciable concentration of PFA into a fiber structure that has sufficient tensile properties for normal textile processing such as knitting and weaving.
  • the inclusion of PFA into a matrix spun PTFE fiber results in a true bicomponent fluoropolymer fiber with typical thermal capabilities (maximum continuous use temperature) of PTFE.
  • the inclusion of PFA into the fiber matrix provides a lower melt component to the fiber. This lower melt component when in a fabric structure provides a system to which a PFA film can be laminated at lower temperatures and pressures compared to 100% PTFE.
  • An exemplary PFA laminated film product is described in U.S. Provisional Patent Application No. 61/635,721, filed on April 19, 2012 and titled "Flexible Laminate Structure".
  • the polytetrafluoroethylene particles used in the dispersion employed in this invention are non-melt-processible particles of polytetrafluoroethylene (PTFE) including modified PTFE which is not melt-processible.
  • PTFE polytetrafluoroethylene
  • Modified PTFE refers to copolymers of TFE with such small concentrations of comonomer that the melting point of the resultant polymer is not substantially reduced below that of PTFE.
  • the concentration of such comonomer is preferably less than 1 wt %, more preferably less than 0.5 wt %.
  • the modified PTFE contains a small amount of comonomer modifier which improves film forming capability during baking (fusing), such as perfluoroolefin, notably hexafluoropropylene (HFP) or perfluoro(alkyl vinyl)ether (PAVE), where the alkyl group contains 1 to 5 carbon atoms, with perfluoro (ethyl vinyl)ether (PEVE) and perfluoro(propyl vinyl)ether (PPVE) being preferred.
  • perfluoro (ethyl vinyl)ether (PEVE) and perfluoro(propyl vinyl)ether (PPVE) being preferred.
  • Chlorotrifluoroethylene (CTFE), perfluorobutyl ethylene (PFBE), or other monomer that introduces bulky side groups into the molecule are also included.
  • the PTFE typically has a melt creep viscosity of at least 1 x 10 9 Pa s.
  • the resins in the dispersion used in this invention when isolated and dried are non-melt- processible.
  • Such high melt viscosity indicates that the PTFE does not flow in the molten state and therefore is non-melt-processible
  • non-melt-processible it is meant that no melt flow is detected when tested by the standard melt viscosity determining procedure for melt-processible polymers. This test is according to ASTM D- 1238-00 modified as follows:
  • the cylinder, orifice and piston tip are made of corrosion resistant alloy, Haynes Stellite 19, made by Haynes Stellite Co.
  • the 5.0 g sample is charged to the 9.53 mm (0.375 inch) inside diameter cylinder which is maintained at 372 °C. Five minutes after the sample is charged to the cylinder, it is extruded through a 2.10 mm (0.0825 inch diameter), 8.00 mm (0.315 inch) long square-edge orifice under a load (piston plus weight) of 5000 grams. This corresponds to a shear stress of 44.8 KPa (6.5 pounds per square inch). No melt extrudate is observed.
  • the polytetrafluoroethylene particles have a standard specific gravity (SSG) of less than 2.40, typically from about 2.14 to about 2.40, preferably less than about 2.30, and more preferably less than about 2.25.
  • SSG standard specific gravity
  • the SSG is generally inversely proportional to the molecular weight of PTFE or modified PTFE.
  • the fluoropolymer particles in the dispersion used in this invention preferably have a number average particle size of about 100 nm to about 400 nm, most preferably, about 120 nm to about 220 nm.
  • the perfluoroalkoxy particles used in the dispersion employed in this invention are melt-processible particles of perfluoroalkoxy (PFA).
  • PFA perfluoroalkoxy
  • perfluoroalkoxy refers to a copolymer of tetrafluoroethylene and perfluoroalkylvinylether.
  • a suitable aqueous PFA dispersion is available from E. I. duPont de Nemours & Co., Wilmington, Del. under the name Teflon® PFA TE-7224.
  • Teflon® PFA TE-7224 is a negatively charged, hydrophobic colloid, containing approximately 60% (by total weight) of 0.05 to 0.5 ⁇ perfluoroalkoxy (PFA) resin particles suspended in water.
  • Teflon® PFA TE-7224 also contains approximately 5% by weight of a nonionic wetting agent and stabilizer (based on the weight of the PFA solids). Viscosity at room temperature is approximately 20 cP. Nominal pH is 10.
  • the resin in Teflon® PFA TE-7224 is a true thermoplastic and will exhibit some flow above its melting point. When properly processed, the PFA resin in Teflon® PFA TE-7224 exhibits retention of properties after service at 260°C (500°F), useful properties at -240°C (-400°F), chemical inertness to nearly all industrial chemicals and solvents, and low friction and antistick surfaces. Spinning Composition and Matrix Polymers
  • the present invention provides a spinning composition useful for the dispersion spinning of non-melt-processible fluoropolymer fiber comprising a mixture of an aqueous solution of a matrix polymer and an aqueous dispersion of perfluoroalkoxy particles and non- melt-processible polytetrafluoroethylene particles having an SSG of less than about 2.40, typically from about 2.14 to about 2.40.
  • the non-melt-processible polytetrafluoroethylene particles have an SSG of less than 2.30, and more preferably less than about 2.25.
  • the aqueous dispersion of perfluoroalkoxy particles and polytetrafluoroethylene particles is prepared by pouring the PTFE dispersion into a tote and adding the PFA dispersion to the PTFE dispersion.
  • the dispersion is mixed mechanically in the tote for about an hour with slow agitation to avoid shear.
  • the mixed dispersion is then loaded into a supply tank and put under vacuum.
  • the aqueous dispersion includes, by weight, 75% PTFE and 25% PFA.
  • Matrix polymers used in the practice of the present invention may be polymers containing only hydrogen, carbon, oxygen and nitrogen that are soluble in aqueous solutions that may be coagulated or precipitated by a salt or a shift of pH.
  • cellulose xanthate may be the soluble form of the matrix.
  • the use of viscose in fiber forming suffers from serious disadvantages related to cost of manufacture, production time and environmental hazards.
  • Alternatives to viscose forming have been developed and most recently a process using cellulosic ethers with a uniform degree of substitution of the matrix has been fully described in U.S. Pat. Nos. 5,762,846 and 5,820,984.
  • Cellulosic ether polymers are preferred since these polymers do not melt or soften below the temperature range in which most fluorinated olefinic polymers melt and the polymer decomposes into carbonaceous material on sintering.
  • such cellulosic polymers are methylcellulose, hydroxyethylcellulose, methylhydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose, ethylcellulose and carboxymethylcellulose.
  • the cellulosic ethers preferred for use in this invention as a matrix polymer have a uniform degree of substitution, and are soluble in strong aqueous alkali hydroxide, but insoluble in near neutral pH water.
  • near neutral pH water water having a pH from about 6 to 8.
  • the matrix polymers used in the practice of the present invention have no softening or melting point. These polymers decompose at temperatures near the sintering temperature of the fiber providing requisite tensile strength until the fluoropolymer particles have coalesced such that the resultant fluoropolymer structure provides the necessary tensile strength.
  • intermediate fiber structure means the extruded and coagulated mixture of the matrix polymer solution and the polymer particle dispersion.
  • the intermediate fiber structure produced in the practice of the present invention after washing in near neutral pH water to substantially remove ions and impurities, shows no substantial loss of strength or integrity, and may be worked, for example drawn at a modest draw ratio, and sintered to form a final, coalesced fluorinated polymer fiber or shaped article.
  • the intermediate fiber structure produced by the present invention may be isolated, worked in subsequent processing or used for producing fabrics or batts as is known in this art.
  • the composition of the intermediate fiber structure has a cellulosic ether present as a minor constituent of the fiber solids, while the major constituents are perfluoroalkoxy and non-melt processible fluoropolymer particles having a weight in the intermediate fiber structure that may be from 3 to 20 times that of the matrix polymer.
  • the spinning compositions used in the process of the present invention are made by mixing an aqueous dispersion of fluorinated polymer particles with a solution of the matrix polymer.
  • Aqueous dispersions of perfluoroalkoxy particles and non-melt processible polytetrafluoroethylene particles, such as those described above are used in the present process.
  • the solutions of matrix polymer should be clear and of a viscosity that assures good mixing with the dispersion.
  • the concentration of matrix polymer in the solution is from 3 to 10% by weight.
  • low shrink fluoropolymer fibers including, by weight, 75% PTFE and 25% PFA, were prepared as further described in Table 1.
  • the spin mix was prepared from an aqueous dispersion of fluoropolymer particles containing PTFE dispersion obtained from by E. I. duPont de Nemours & Co. and the Dupont Company's PFA TE7233 dispersion.
  • the matrix polymer utilized in the spin mix was CS Polymer (Hydroxypropyl Cellulose) obtained from Shin Etsu Chemical Industry Co. Tokyo, Japan.
  • a portion of the fluoropolymer fibers were processed into floe, and the melting behavior of the fluoropolymer fiber floe at the second heat was observed using a differential scanning calorimeter (DSC).
  • the DSC scan results for the fluoropolymer fiber floe were compared to the melting behavior of a 100% dispersion spun PTFE fiber floe.
  • FIG. 1 the DSC curve shows that the fluoropolymer fiber exhibited a PFA endotherm at 301
  • FIG. 2 which depicts the DSC scan showing the melting behavior of a 100% PTFE dispersion spun fiber, exhibits a single endoderm at 327 °C. An endoderm at 301 °C is absent.
  • a cool down DSC scan of the fluoropolymer fiber is depicted at FIG. 3. The cool down scan shows that the fluoropolymer fiber exhibits a noticeable PFA exotherm at 284.7 °C and a PTFE exotherm at 311.08 °C. The PFA exotherm is absent in FIG. 4, which depicts a cool down DSC scan of the 100% PTFE fiber.
  • the bonding strength of the fluoropolymer fibers was tested and compared to the bonding strength of dispersion spun 100% PTFE fibers.
  • Each fluoropolymer fiber sample was twisted and then cut longer than the platen press. The fibers samples were twisted to avoid having the samples being encapsulated by the film laminate and providing erroneous results. Weight was added to each end of the samples to maintain tension.
  • a PFA film was laid beneath the samples and another film was laid on top. The platen press was closed and heated until the two films laminate. At this point the press was opened, and the sample were cooled. Once cooled, one end of the samples was trimmed to remove the exposed fibers. The remaining sample was put into an instron, and the force to remove the fibers from the film laminate was measured. The force required to remove the fibers from between the PFA laminates was higher for the PTFE/PFA blended fiber than the 100% PTFE fiber.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Artificial Filaments (AREA)

Abstract

L'invention concerne une fibre de fluoropolymère filée par dispersion préparée à partir de particules de polytétrafluoroéthylène non transformable à l'état fondu et de particules de perfluoroalcoxy.
PCT/US2013/037418 2012-04-19 2013-04-19 Fibre de fluoropolymère filée par dispersion préparée à partir de polytétrafluoroéthylène non transformable à l'état fondu et de perfluoroalcoxy WO2013159020A1 (fr)

Applications Claiming Priority (2)

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US201261635521P 2012-04-19 2012-04-19
US61/635,521 2012-04-19

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WO2013159020A1 true WO2013159020A1 (fr) 2013-10-24

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3433401A4 (fr) * 2016-03-23 2019-10-09 Toray Fluorofibers (America) Inc. Matériau en fibre de fluoropolymère mouillable
CN112501713A (zh) * 2020-11-24 2021-03-16 江苏川羽高分子材料科技有限责任公司 一种含氟聚合物复合纤维的制备方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998012255A1 (fr) * 1996-09-19 1998-03-26 W.L. Gore & Associates Gmbh Melange co-continu d'un polymere fluore et d'un thermoplastique et procede
US6647237B2 (en) * 2000-11-29 2003-11-11 Xerox Corporation Three layer seamless transfer component
EP1699955B1 (fr) * 2003-12-31 2007-10-31 E.I.Du pont de nemours and company Filetage par dispersion de fluoropolymeres a noyau-enveloppe
WO2008157307A1 (fr) * 2007-06-14 2008-12-24 Toray Fluorofibers (America), Inc. Fibre de polytétrafluoroéthylène thermiquement stable et procédé pour sa fabrication
US20090317553A1 (en) * 2008-05-30 2009-12-24 Whitford Corporation Blended fluoropolymer compositions

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998012255A1 (fr) * 1996-09-19 1998-03-26 W.L. Gore & Associates Gmbh Melange co-continu d'un polymere fluore et d'un thermoplastique et procede
US6647237B2 (en) * 2000-11-29 2003-11-11 Xerox Corporation Three layer seamless transfer component
EP1699955B1 (fr) * 2003-12-31 2007-10-31 E.I.Du pont de nemours and company Filetage par dispersion de fluoropolymeres a noyau-enveloppe
WO2008157307A1 (fr) * 2007-06-14 2008-12-24 Toray Fluorofibers (America), Inc. Fibre de polytétrafluoroéthylène thermiquement stable et procédé pour sa fabrication
US20090317553A1 (en) * 2008-05-30 2009-12-24 Whitford Corporation Blended fluoropolymer compositions

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3433401A4 (fr) * 2016-03-23 2019-10-09 Toray Fluorofibers (America) Inc. Matériau en fibre de fluoropolymère mouillable
CN112501713A (zh) * 2020-11-24 2021-03-16 江苏川羽高分子材料科技有限责任公司 一种含氟聚合物复合纤维的制备方法

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