CA2242468A1 - Fibers flash-spun from partially fluorinated polymers - Google Patents
Fibers flash-spun from partially fluorinated polymers Download PDFInfo
- Publication number
- CA2242468A1 CA2242468A1 CA002242468A CA2242468A CA2242468A1 CA 2242468 A1 CA2242468 A1 CA 2242468A1 CA 002242468 A CA002242468 A CA 002242468A CA 2242468 A CA2242468 A CA 2242468A CA 2242468 A1 CA2242468 A1 CA 2242468A1
- Authority
- CA
- Canada
- Prior art keywords
- partially fluorinated
- fluorinated hydrocarbon
- comprised
- pressure
- hydrocarbon polymers
- 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.)
- Abandoned
Links
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
- D01D5/00—Formation of filaments, threads, or the like
- D01D5/11—Flash-spinning
-
- 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
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D01F6/32—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising halogenated hydrocarbons as the major constituent
-
- 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
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
- D01F6/46—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polyolefins
-
- 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
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/44—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds
- D01F6/52—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds as major constituent with other polymers or low-molecular-weight compounds of polymers of unsaturated carboxylic acids or unsaturated esters
-
- 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
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
- D01F6/90—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyamides
-
- 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
- D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
- D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
- D01F6/92—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyesters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
Abstract
A flash-spun material comprised of at least 20 % partially fluorinated hydrocarbon polymers in which between 10 % and 70 % of the total number of hydrogen atoms in each hydrocarbon polymer are replaced by fluorine atoms. The partially fluorinated hydrocarbon polymers are preferably comprised of at least 80 % by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride. The flash-spun material may be a plexifilamentary strand or a microcellular foam. Also provided is a process for producing flash-spun material from partially fluorinated hydrocarbon polymers in a solvent and a solution from which such polymers may be flash-spun.
Description
W O 97125460 PCT~US97/00160 FIBERS FLASH-SPUN FROM
PARTIALLY FLUOR~NATED POLYMERS
BACKGROUND OF THE INVENTION
5This invention relates to fibers that are flash-spun from partially fluorinated hydrocarbon polymers and a solvent.
The art of flash-spinning strands of plexifilamentary film-fibrils from polymer in a solution or a dispersion is known in the art. The term "ple~cifil~m~ntary" means a three-dimensional integral network of a multitude of thin, ribbon-like, film-fibril o elements of random length and with a mean film thickness of less than about 4 microns and with a median fibril width of less than about 25 microns. In plexifil~mentary structures, the film-fibril elements are generally coextensively aligned with the longitudinal axis of the structure and they intermittently unite and separate at irregular intervals in various places throughout the length, width and thickness of the structure to 15 forrn a continuous three-dimensional network.
U.S. Patent 3,227,784 to Blades et al. (~.ci~ned to E. I. du Pont de Nemours &
Company ("DuPont")) describes a process wherein a polymer in solution is forwarded continuously to a spin orifice at a ten~l)e.dl~lre above the boiling point of the solvent, and at autcgenous pressure or greater, and is flash-spun into a zone of lower temperature and 2 o substantially lower pressure to generate a strand of plexifilamentary material. U.S.
Patent 5,192,468 to Coates et al. (~signed to DuPont) discloses another process for flash-spinning a plexifilamentary strand according to which a mechanically generated dispersion of melt-spinnable polymer, c~rbon dioxide and water under high pressure is flashed through a spin orifice into a zone of substantially lower lell,p~.dl~lre and pressure 2 5 to forrn a plexifil~rnent~ry strand.
U.S. Patent 3,227,794 to Anderson et al. (assigned to DuPont) teaches that plexifilamentary film-fibrils are best obtained from solution when fiber-forming polymer is dissolved in a solvent at a tel~p.,.dlLIre and at a pressure above which two liquid phases form. which pressure is generally known as the cloud point pressure at the given3 o temperature. This solution is passed to a pressure let-down chamber, where the pressure decreases below the cloud point pressure for the solution thereby causing phase separation. The resulting two phase dispersion of a solvent-rich phase in a polymer-rich phase is discharged through a spinneret orifice to form the plexifil~mentary strand.
U.S. Patent 3,484,899 to Smith (~ ign~d to DuPont) discloses an apparatus 3 5 wilh a horizontally oriented spin orifice through which a plexifil~ nentary strand can be ~lash-spun. The polymer strand is conventionally directed against a rotating lobed deflector baffle to spread the strand into a more planar web structure that the baf'fle alternatelv directs to the left and right as the web descends to a moving collection belt.
W O 97/25460 PCT~US97/00160 The fibrous sheet formed on the belt has plexifilamentary film-fibril networks oriented in an overlapping multi-directional configuration.
Many improvements to the basic nash-spinning process have been reported or patented over the years. Flash-spinning of olefin polymers to produce non-woven sheets is practiced cornmercially and is the subject of numerous patents including U.S. Patent 3,851,023 to Brethauer et al (assigned to DuPont). Flash-spinning of olefin polymers to produce pulp-like products from polymer solutions is disclosed in U.S. Patent 5,279,776 to Shah (assigned to DuPont). Flash-spinning of olefin polymers to produce microcellular and ultra-microcellular foam products from polymer solutions is disclosed 0 in U.S. Patent 3,227,664 to Blades et al. and 3,5~4,090 to Parrish (assigned to DuPont).
The commercial application for flash-spinning has been primarilv directed to the manufacture of polyolefin ple~ifil~ment~, especially of polyethylene and polvpropylene. However, experimental work directed to the flash-spinning of other polymers, has been reported. For example, U.S. Patent 3,227,784 to Blades et al.describes the flash-spinning of a solution of a perfluoroethylene/perfluoloplopylene (90:
lO) copolymer from a solution in p-bis(trifluoromethyl)benzene (Example 30).
Applicants are not aware of commercial flash-spinning of such fluoropolymers. U.S.
Patents 5,328,946 and 5,364,929 disclose solutions of tetrafluoroethylene polymers at superautogenous pressure in perfluorinated cycloalkane solvents.
2 o As used herein, "partially fluorinated hydrocarbon" refers to an organic compound that would be a hydrocarbon except that one or more of the compound's hydrogen atoms have been replaced by fluorine atoms Partially fluorinated hydrocarbon polymer and copolymer films exhibit a variety of outstanding characteristics such as excellent resi.~t~nce to acids, bases, and most organic liquids under normal temperature and pressure conditions; excellentdielectric properties; good tensile properties; good resistance to heat and weather; a relatively high melting point; and good fire retardance. Partially fluorinated hydrocarbon polymers and copolymer films are extensively used in high value applications such as insulation for high speed electrical tr~n~mi~ion cables. Flash-spun plexifilaments of 3 0 such polymers and copolymers should find wide use in other high value applications such as, for exarnple, hot gas filtration media, pump packings, gaskets, and protective apparel.
However, because of their relatively high melting points and outstanding chemical inertness, partially fluorinated hydrocarbon polymers are very difficult to dissolve, and therefore it had not been possible to flash-spin such polymers. Comrnercially available 3 5 spunbonded fabrics are all made from polyethylene, polypropylene, nylon, and polyester, which are highly combustible. Accordingly, there is a need for nonfl~mm~hle spunbonded fabric for protective garments and other critical end uscs. In ~Id~ iOIl, ~hcr~
is a need for partially fluorinated hydrocarbon polymer and copolymer plexifilaments that exhibit excellent heat and chemical resistance~ good dielectric properties, and good non-stick characteristics. There also is a need for a process suitable for use in commercial flash-spinning of partially fluorinated hydrocarbon polymers using conventional spinnin~
equipment under conventional commercial temperature and pressure conditions SUMMARY OF THE INVENTION
According to the present invention, there is provided a flash-spun material comprised of at least 20% partially fluorinated hydrocarbon polymers in which between 10% and 70% of the total number of hydrogen atoms in each hydrocarbon polymer are 0 replaced by fluorine atoms. Preferably, the partially fluorinated hydrocarbon polymers are comprised of at least 80% by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride. According to one pl~ c,d embodiment of ~e invention, 40% to 70% by weight of the hydrocarbon polymers are comprised of polymerized monomer units of5 tetrafluoroethylene and 10% to 60% of said hydrocarbon polymers are comprised of polymerized monomer units of ethylene. According to another preferred embodiment of the invention, 40% to 70% by weight of the hydrocarbon polymers are be comprised of polymerized monomer units of chlorotrifluoroethylene and 10% to 60% by weight of the hydrocarbon polymers comprised of polymerized monomer units of ethylene. According 2 o to other ~;Çell~d embodiments of the invention, at least 80% by weight of the hydrocarbon polymers are comprised of a homopolymer of either difluoroethylene or fluoroethylene.
The flash-sp~u~ material may be a plexifil~ment~ry strand having a a surface area, measured by the BET nitrogen adsorption method, greater than 2 m2~g. The 2 5 plexifil~ nt~ry strand comprises a three dimensional integral plexus of semicrystalline.
polymeric, fibrous elements that are co-extensively aligned with the axis of theple7~ifil~m~nt and have the structural configuration of oriented film-fibrils. The film-fibrils have a mean film thickness of less than abowt 4 microns and median fibril width of less than about 2S microns. Alternatively, the flash-spun material may be a microcellular 3 0 foam. The invention is also directed to a process for producing flash-sp~ln material from partially fluorinated hydrocarbon polymers in a solvent and a solution from which such polymers may be flash-spun.
The accompanying drawings, which are incorporated in and constitute a part ofthis specification, illustrate the presently preferred embodiments of'the invention allcl.
together with the description, serve to explain the principles of the invention.
Figure l is a plot of the cloud point data for a solution comprised of 25% of anethylene/tetrafluoroethylene copolymer in a solvent comprised of pentane and acetone at a number of different solvent ratios.
Figure 2 is a plot of the cloud point data for a solution comprised of an ethylene/tetrafluoroethylene copolymer at various concentrations in a solvent with a ratio of 70% pentane/ 30% acetone.
Figure 3 is a plot of the cloud point data for a solution of 30% polyvinylidene fluoride in a solvent with a ratio of 60% acetone/ 40% pentane.
Figure 4 is a plot of the cloud point .data for a solution of 35% polyvinyl 0 fluoride in solvents comprised of either 20% pentane and 80% acetone or 100% acetone.
Figure 5 is a plot of the cloud point data for a solution of a 30% copolymer of alternating monomer units of ethylene and chlorotrifluoroethylene in a solvent comprised of pent~ne/acetone at a nurnber of different solvent ratios.
Figure 6 is a plot of the cloud point data for an ethvlene/tetrafluoroethylene copolymer in a number of different solvents.
DETAILED DESCRIPTION
~eference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated below.
2 o The flash-spun partially fluorinated plexifilaments of the invention can be spun using the apparatus and flash-spinning process disclosed and iùlly described in U.S.
Patent 5,147,586 to Shin et al. It is anticipated that in commercial applications, partially fluorinated plexifil:~mentary sheets could be produced using the apparatus disclosed in U.S. Patent 3,851,023 to Brethauer et al.
2 5 The process for flash-spirming plexifilaments from a partially fluorinated hydrocarbon polymer and a solvent operates under conditions of elevated temperature and pressure. The polymeric starting m~teri~l iS norrnally not soluble in the selected solvent under normal temperature and pressure conditions but forms a solution at certain elevated temperatures and pr~ es. We have now found that partially fluorinated hydrocarbon 3 o polymers become soluble in certain types of solvents if high enough t~ ld~lres and pressures are applied. Surprisingly, partially fluorinated hydrocarbon polymers become soluble in certain polar solvents such as alcohols and ketones, and in certain types of chlorinated solvents and hydrofluorocarbons (HFC's) at high temperatures and pressures.
The HFC's are newly developed solvents which have become available recently as a3 5 replacement for ozone depleting fully halogenated chlorofluorocarbons ~CFC's).
As long as the pressure is m~int~ined above the cloud point pressure, ~he partially fluorinated hydrocarbon polymer remains in solution. In the flash-spillning process, pressure is decreased below the cloud point, just before the solution is passed W O 97t25460 PCT/US97/00160 through a spinneret. When the solution pressure is lowered below the cloud pointpressure, the solution phase separates into a polymer-rich phase and a solvent-rich phase.
Upon passing through the spinneret at very high speed into a zone of substantially lower pressure, the solvent flashes off quickly and the polymer material present in the polymer-rich phase freezes in an elongated plç~ifil~mentary form.
The morphology of fiber strands obtained by solution flash-spinning of partially fluorinated hydrocarbon polymer is greatly influenced by the type of solvent in which the polymer is dissolved, the concentration of the polymer in the spin solution, and the spin conditions. To obtain ple~ifil~ment.~, polymer concentration is kept relatively o low (e.g., less than about 3 5 weight percent), while spin temperatures and pressures are generally kept high enough to provide rapid fl~hing of the solvent. Microcellular foam fibers, on the other hand, are usually prepared at relatively high polymer concentrations and at lower spin temperatures and pressures.
Well fibrillated plexifilaments are usually obtained when the spin ternperature used is between the critical temperature of the spin liquid and 40~ C below the critical temperature, and when the spin ple~ure is slightly below the cloud point pressure. When the spin plc,S~eiS much greater than the cloud point pressure of the spin mixture, coarse plexifilamentary "yarn-like" strands are usually obtained. As the spin pressure is gradually decreased, the average distance between the tie points of the fibrils of the 2 o strands generally becomes shorter while the fibrils become progressively finer. When the spin pressure approaches the cloud point pressure of the spin mixture, very fine fibrils are normally obtained, and the distance between the tie points becomes very short. As the spin pressure is further reduced to below the cloud point pressure, the distance between the tie points becomes longer. Well fibrillated ple~cifil~ments, which are most suitable for 2 5 sheet formation. are usually obtained when spin pressures slightly below the cloud point pressure are used. The use of p~es~ es which are too much lower than the cloud point pressure of the spin mixture generally leads to a relatively coarse fiber structure. In some cases~ well fibrillated plexifilaments can be obtained even at spin pressures slightly higher than the cloud point pressure of the spin mixture.
3 o For flash-spinning of microcellular foam fibers, relatively strong solvents are used to obtain relatively low cloud point pressures that are above the cloud point pressure. Microcellular foarns are usually prepared at relatively high polymer concentrations in the spinning solution and at relatively low spinning temperatures and pressures that are above the cloud point pressure. Microcellular foam fibers may be 3 5 obtained rather than ple~ifil~m~nt.~, even at spinning pressures slightly below the cloud point pressure of the solution. Nucleating agents, such as fused silica and kaolin, may be added to the spin mix to facilitate solvent flashinf~ and to obtain unif'orm small si7.e cells.
Microcellular foams can be obtained in a collapsed form or in a fully or partially inllated form. For many polymer/solvent systems~ microcellular foams tend to collapse after exiting the spinning orifice as the solvent vapor condenses inside the cells andl or diffuses out of the cells. To obtain low density inflated foams, infl~ting agents are usually added to the spin liquid. Infl~tin~ agents to be used should have a permeability coefficient for diffusion through the cell walls that is less than that of air so that the agent can stay inside the cells for a long period of time while allowing air to diffuse into the cells to keep the cells infl~terl Osmotic pressure will cause air to diffuse into the cells.
Suitable infl~tin~ agents that can be used include low boiling temperature partially halogenated hydrocarbons and halocarbons such as hydrochlorofluorocarbons, 0 hydrofluorocarbons, chloroflùorocarbons, and perfluorocarbons; inert gases such as carbon dioxide and nitrogen; low boiling tenlp~.dlLIre hydrocarbon solvents such as butane and iso~ e; and other low boiling te,llpcla~u~e organic solvents and gases.
The atmospheric boiling points will be around room temperature or lower.
Microcellular foam fibers are normally spun from a round cross section spin orifice. However, an annular die similar to the ones used for blown films can be used to make microcellular foarn sheets. Fully inflated foams, as-sp~n fibers or as-extruded foam sheets can be post-inflated by immersing them in a solvent cont~ininf~ dissolvedinfl~t~nts Tnfl~t~ntc will diffuse into the cells due to the plasticizing action of the solvent. Once dried, the infl~t~nt~ will stay inside the cells and air will diffuse into the 2 o cells due to osmotic pressure to keep the microcellular foams inflated. Microcellular foarns have densities between 0.005 and 0.50 g/cc. Their cells are generally of a polyhedral shape and their average cell size is less than about 300 microns, and is preferably less than about 150 microns. Their cell walls are typically less than about 3 microns thick, and they are typically less than about 2 microns in thickness.
2 5 Plexifi~ ent~ry pulps of partially fluorinated hydrocarbon polymers can be produced by disc refining flash-spun ple~ifil~ments as disclosed in U.S. Patent 4,608,089 to Gale et al. (assigned to DuPont). Alternatively, such pulps can be prepared directly from polymer solutions by flash-spinning using a device similar to the one disclosed in U.S. Patent 5,279,776. These pulps are plexifil~mentary in nature and they can have a 3 ~ three dimensional network structure. However, the pulp fibers are relatively short in length and they have small dimensions in the transverse direction. The average fiber len~th is less than about 200 microns, and is preferably less than 50 microns. The pulp fibers have a relatively high surface area of greater than 2 m2/g.
Polymers that may be flash-spun to produce the partially fluorinated 3, hydrocarbon polymer plexifilaments of the invention are hydrocarbon polymers in which between 1 ~~/O and 70% of the total number of hydrogen atoms in the hydrocarbon polvmer are replaced by fluorine atoms. Preferably, the partially fluorinated h- drocarbon polymers are comprised of at least 80% by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride. A particularly preferred partially fluorinated hydrocarbon polymer is comprised of 40% to 70% by weight of polymerized monomer units of tetrafluoroethylene and 10% to 60% by weight of polymerized monomer units of ethylene, such as a copolymer comprised of substantially alternating units of ethylene and tetrafluoroethylene with the chemical structure -(CH2CH2)-(CF2CF2)-. Such ethylene/tetrafluoroethylene copolymers are disclosed, for exarnple, in U.S. Patents 3,624,250 to Carlson (assigned to DuPont),3,870,689 to Modena et al., and 4,677,175 to Ihara et al. Ethylene~tetrafluoroethylene copolymer resin is comrnercially available from 0 DuPont under the tradenarne TEFZEL(g1, which is a registered trademark of DuPont.
T~FZEL~) fluoropolymer resins have a melting points between 235~ and 280 ~C.
Another preferred polymer that may be flash-spun to produce the partially fluorinated hydrocarbon polymer plexifilaments of the invention is comprised of 40% to 70% by weight of polymerized monomer units of vinylidene fluoride. Polyvinylidene fluoride polymer resins with the chemical structure -(CH2CF2)- are col.lm~ .eially available from Elf Atochem under the tra~l~n~ KYNAR(~), which is a registered tr~-lem~rk of Elf Atochem. KYNAR~) fluoropolymer resins have a melting point of about 170 ~C.
Other polymers that may be flash-spun to produce the partially fluorinated 2 o hydrocarbon polymer ple~ifil~m~nt~ of the invention include ethylene/
chlorotrifluoroethylene copolymers and polvvinyl fluoride. Other monomer units that may be present in the flash-spun partially fluorinated hydrocarbon polymer plexifilaments include vinyl ethers or branched olefins, either unsubstituted or fluorinated such as, for example, perfluoro(propyl vinyl ether) and perfluoro(butyl vinyl ether).
2 5 While the tel.lpelalu.~ and p~s~u.e conditions that can be withstood by solution flash-spinning equipment are quite broad, it is generally preferred not to operate under extreme temperature and pl~.S:jUI~: conditions. The preferred tellll)el~ure range for flash-spinning the partially fluorinated hydrocarbon polymers flash-spun according to the invention is about 150~ to 300~ C while the preferred pressure range for flash-spinning is 3 o in the range of the autogenous pressure of the solution to 7250 psig (50 MPa), and more preferably from the autogenous pressure of the solution to 3625 psig (25 MPa). As used herein, "autogenous pressure" is the natural vapor pressure of the spin mixture at a given temperature. Therefore, if plexifil~ment.c are to be flash-spun from partially fluorinated hydrocarbon polymers in solution, the solvent should dissolve the partially fluorinated 3 s hydrocarbon polymers at pressures and temperatures within the preferred ranges. In order to generate the two phase solution that is needed for flash-spimling plexifilamentary film-fibrils, the solution must also have a cloud point pressure lllal i~ within the ~iesired pressure and temperature operating ranges. In addition, the solution must form the desired two phases at a pressure that is sufficiently high to ~enerate the explosive fl~hin required for the formation of ple~cifil~ments.
As discussed, partially fluorinated hydrocarbon polymers are not soluble in comrnon solvents under normal conditions. However, we have found that these polymers become soluble in certain types of organic solvents at high temperatures and pressures.
Solvents which are capable of dissolving partially fluorinated hydrocarbon polymers at elevated temperatures and pressures include: polar solvents such as l1alogenated or nonhalogenated alcohols (Cl to C3), ketones (C3 to C5), acetates and carbonates; certain types of hydrochlorocarbons, hydrofluorocarbons (HFC:'s), hydrofluoroethers (HFE's), 0 hydrochlorofluorocarbons (HCFC's) and perfluorinated solvents, and certain types of strong hydrocarbon solvents. It should be noted that not all of the partially fluorinated hydrocarbon polymers are soluble in all of these solvents. For example, poly (ethylene/
tetrafluoroethylene) is soluble in HFC-4310mee and also in cyclopentane at high temperatures and pressures, but polyvinylidene fluoride is not soluble in these solvents. at least up to 250~ C and 4000 psig (27.6 MPa). Suitable flash-spinning agents must be determined for each polymer from the types of solvents listed above.
Preferred solvents for flash-spinnin~ partially fluorinated hydrocarbon polymers will depend on the specific type of polymer to be flash-spun. However, acetone/hydrocarbon solvent (C5 to C6) mixtures, methylene chloride, and n-2 o pentafluorol,lopanol are generally good flash-spinning agents for these polymers. Other flash-spinning agents that can be used for flash-spinning partially fluorinated hydrocarbon polymers include HFC-4310mee, perfluoro-N-methylmorpholine (3M's PF5052), methyl (perfluorobutyl) ether (3M's HFE 7100), dichloroethylene, ethanol, propanols, methyl ethyl ketone, cyclopentane or mixtures of these solvents. In 2 s circumstances where it is desirable to raise the cloud point pressure, minor amounts of poor solvents or nonsolvents can be added to the above solvents in order to raise the cloud point pressure. In the case of mixed solvents, a proper solvent ratio has to be chosen so that cloud point pressures of the polymer solutions to be flash-spun are in the acceptable range (e.g. higher than autogenous pressure but less lower ~50 MPa).
3 o Preferred solvent systems to be used for each polymer will be further illustrated through specific examples.
The apparatus and procedure for det~rminin~ the cloud point pressures of a polymerlsolvent combination are those described in the above-cited U.S. Patent 5,147,586 to Shin et al. The cloud point pressures at different tel~ aLules of a number 3 5 of partially fluorinated hydrocarbons polymers in selected solvents or pairs of solvents are ~iven in ~igs. 1-6. These plots are used in determinin~ whether flash-spinning of a particular polymer/solvent combination is feasible. Above each curve, the copolyn1er is completely dissolved in the solvent system. Belo~ each curve. separation into a WO 97125460 PCT~US97/00160 polymer-rich phase and a solvent-rich phase takes place. At the boundary line, the separation into phases disappears when passing from lower pressures to higher pressures, or phase separation begins when passing from higher pressures to lower pressures.
Figure I is a plot of the cloud point pres~u,e at different temperatures for a solution of 25% by weight l ~G~;L~ fluoropolymer (copolymer of ethylene and tetrafluoroethylene) in a solvent comprised of pentane and acetone. Figure I provides this cloud point curve at three different solvent ratios: 70% pentane/30% acetone ("10");
60% pentane/40% acetone (" 11 "); and 50% pentanel50% acetone (" 12"). l ~ ;L(~ is a registered tr~lem~rk of DuPont.
0 Figure 2 is a plot of the cloud point pressure at dir~le-,t tel~lp~ldLures for a solution of TEFZEL(~\ fluoropolymer (copolymer of ethylene and tetrafluoroethylene) in a solvent at a ratio of 70% pentane/30% acetone. Figure 2 shows the cloud point curve at three different concentrations ofthe fluoropolymer: 20% ("IS"); 35% ("16"); and 40% (" 17") by weight in the solvent.
Figure 3 is a plot of the cloud point pressure at different temperatures for a soiution of 30% by weight KYNAR~) fluoropolymer (polyvinylidene fluoride) in a solvent with a ratio of 60% acetone/40% pentane. KYNAR~ is a registered tradern~rk of Elf Atochem.
Figure 4 is a plot of the cloud point pressure at different temperatures for a 2 o solution of 35% by weight TEDLAR(~ fluoropolymer (polyfluoroethylene) in a solvent with a ratio of 20% pentane/80% acetone ("20"). Figure 4 also shows the cloud point data for a solution of TEDLARt~) fluoropolymer in a solvent comprised of 100% acetone ("21 "). TEDLAR(~) is a registered tr~d~m~rk of DuPont.
Figure 5 is a plot of the cloud point ples~ule at different temperatures for a 2 5 solution of 30% by weight HALAR Z9 fluoropolymer (copolymer of alternating monomer units of ethylene and chlorotrifluoroethylene) in a solvent comprised of pentane and acetone. Figure 5 provides this cloud point data at two different solvent ratios: 70%
pentane/30% acetone ("25"); and 50% pentane/50% acetone ("26"). HALAR(~3 is a re~istered trademark of Ausimont.
3 o Figure 6 is a plot of the cloud point pressure at different temperatures for an ethyleneltetrafluoroethylene copolymer (Tefzel(~) 750 obtained from DuPont) in a number of different solvents. Curve 30 shows the cloud point pressures in a solution of 20%
copolymer in HFC-4310mee (CF3CHFCHFCF2CF3) solvent. Curve 31 shows the cloud point pressures in a solution of 20% copolymer in a solvent of 70% pentane and 30%
3 5 acetone. Curve 32 shows the cloud point pressures in a solution of 12% copolymer in pentafluoropropanol. Curve 33 shows the cloud point pressures in a solution of 20%
copolymer in 2-propanol. Curve 34 shows the cloud point pressures in a solution ol' 12~, copolymer in methylene chloride (CH2C12). Curve 35 shows the cloud point pressures in W O 97/25460 PCT~S97/00160 a solution of 20% copolymer in acetorle. Cur~e 36 shows the cloud point pressures in a solution of 20% cyclopentane(99%).
This invention will now be illustrated by the following non-limiting examples which are intended to illustrate the invention and not to limit the invention in any manner.
EXA~PLES
Test Methods 0 In the description above and in the non-limiting examples that follow, the following test methods were employed to determine various reported characteristics and properties. ASTM refers to the American Society of Testing Materials, and TAPPI refers to the Technical Association of the Pulp and Paper Industry.
The denier of the strand is determined from the weight of a 15 cm sample length of strand.
T~n~.ity, elon~tion and tol~hnf c.~ of the flash-spun strand are deterrnined with an Instron tensile-testing m~f lline. The strands are conditioned and tested at 70~F
and 65% relative humidity. The strands are then twisted to 10 turns per inch andmounted in the jaws of the Instron Tester. A two-inch gauge length was used with an 2 o initial elongation rate of 4 inches per minute. The tenacity at break is recorded in grams per denier (gpd). The elongation at break is recorded as a percentage of the two-inch gauge length of the sample. Toughness is a measure of the work required to break the sample divided by the denier of the sample and is recorded in gpd. Modulus corresponds to the slope of the stress/strain curve and is expressed in units of gpd.
2 5 Fiber qualitv in Examples 22 and 23 was evaluated using a subjective scale of 0 to 3, with a 3 being the highest quality rating. Under the evaluation procedure, a 10 inch length of a ple~cifil~m~ns~ry strand is removed f~om a fiber batt. The web is spread and mounted on a dark substrate. The fiber quality rating is an average of threesubjective ratings, one for fineness of the fibe; (finer fibers receive higher ratings), one 3 o for the continuity of the fiber strand (continuous plexifilamen~ry strands receive a higher rating), and the other for the fre~uency of the ties (more networked ple~ifil~rnenr~ry strands receive a higher rating).
Fiber fineness is measured using a technique similar to that disclosed in U.S.
Patent 5,371,810 to A. Ganesh Vaidyanathan dated 6 December 1994~ and which is 3 5 hereby incorporated by reference. This teclmique quantitatively analyzes fibril size in webs of fiber. The webs are opened up by hand and imaged using a microscopic lens.
The image is then digitized and computer analyzed to determine the mean fibril wid~h .l~
standard deviation. However, some smaller fibrils mav be so tightly bunched together W O 97125460 PCT~US97/00160 and have such short fibril length, that the fibrils appear as part of a large fibril and are counted as such. Tight fibril b1ln~hing and short fibril length (distance from tie point to tie point) can effectively prevent analysis of the finenes~ of individual fibrils in the bunched fibrils. Thus, the term "apparent fibril size" is used to describe or characterize fibers of plexifilamentary strands.
The surface area of the plexifilamentary film-fibril strand product is another measure of the degree and fineness of fibrillation of the flash-spun product. Surface area is measured by the 13ET nitrogen absorption method of S. Brunauer, P. H. Emmett and E.
Teller. J. Am. Chem. Soc.~ V. 60 p 309-319 (1938) and is reported as m2/g.
Test Apparatus for Examples 1 - 21 The apparatus used in the examples 1 - 21 is the spinning apparatus described in U.S. Patent 5,147,586. The apparatus consists of two high pressure cylindrical chambers, each equipped with a piston which is adapted to apply pressure to the contents of the chamber. The cylinders have an inside diameter of 1.0 inch (2.54 cm) and each has an internal capacity of 50 cubic centimeters. The cylinders are connected to each other at one end through a 3132 inch (0.~3 cm) diameter channel and a mixing chamber cont~ining a series of fine mesh screens that act as a static mixer. Mixing is accomplished by forcing the contents of the vessel back and forth between the two 2 o cylinders through the static mixer. A spinneret assembly with a quick-acting means for opening the orifice is attached to the channel through a tee. The spinneret assembly consists of a lead hole of 0.~5 inch (0.63 cm) diameter and about 2.0 inch (5.08 cm) length, and a spinneret orifice with both a length and a diameter shown in the tables below. Orifice measurements are expressed in mils [lmil = 0.0254 mm]. The pistons are 2 5 driven by high pressure water supplied by a hydrauiic system In the tests reported in Examples 1 - 21, the apparatus described above was charged with pellets of a partially fluorinated hydrocarbon polymer and a solvent. High pressure water was used to drive the pistons to generate a mixing ples~ule of between 1500 and 3000 psi (10,340 - 10,680 kPa). The polymer and solvent were next heated to 3 o mixing temperature and held at that temperature for about an hour during which time the pistons were used to alternately establish a differential pressure of about 50 psi (345 kPa) or higher between the two cylinders so as to repeatedly force the polymer and solvent through the mixing channel from one cylinder to the other to provide mixing and effect forrnation of a spin mixture. The spin mixture temperature was then raised to the final 3 5 spin temperature, and held there for about 15 minutes to equilibrate the temperature, durin_ which time mixing was continued. In order to simulate a pressure letdown chamber, the pressure of the spin mixture was reduced to a desired spinnin~ pressure j~lsl prior to spinning. This was accomplished by opening a valve between the spin cell and a much larger tank of high pressure water ("the accumulator") held at the desired spinning pressure. The spinneret orifice is opened about one to five seconds after the opening of the ~alve between the spin cell and the accumulator. This period roughly corresponds to the residence time in the letdown chamber of a commercial spinning apparatus. The 5 resultant flash-spun product is collected in a stainless steel open mesh screen basket. Tlle pressure recorded jUSt before the spinneret using a computer during spinning is entered as the spin pressure.
The experimental conditions and the results for Examples I - 21 are given below in the Tables 1 -5. All the test data not originally obtained in the Sl system of 10 units has been converted to the SI units.
In Examples l-7, a c~polymer of al~ tin~; monomer units of ethylene and tetrafluoroethyl~ne was flash-spun firom a number of solvents. The copolymer used in 15 Examples 1-7 was TEFZEL~) fluoropolymer obtained from DuPont in the following grades:
Name and Grade Melt Flow Rate Melting Point Tefzel 750 7 9/10 min -250~C
Tefzel HT 2129 7 9/10 min ~235~C
Tefzel 200 7 g/10 min -280~C
Tefzel 280 4 g/10 min -280~C
The solvents used include acetone, methy}ene chloride (CH2Cl2) and Vertrel ~45 (perfluoro(dimethylcyclobutane)) obtained from DuPont.
Table POLYMER SOLVENT MIXING SPNNING Properties @1 ~ExWt IISlIS2 ~Press Odfice Pmss~ IMcd Ten EETI
No. NAME % 1 ! 2 I Wrh ~C !MinlMPa DxLmils MPa C Denlgpd gpd E%l SAlType TEFZEL VERTREL
1 ~HT750) 12 CH2C12 245 SOt50 200 60 13.8 30X30 7.6 200 217 2~69 1.37 30.7lnmlplex TEFZEL
2 ~HT750) 25 PENTANE ACETONE 70130 220 17.2 30X30 9.7 220 285 O.9B 1.01 35 nm ~ plex TEFZEL
3 ~200) 35 PENTANE ACETONE 70130 250 60 20.7 30X30 11.7 250 448 0.97 1.21 29 22 I plex TEFZEL
PARTIALLY FLUOR~NATED POLYMERS
BACKGROUND OF THE INVENTION
5This invention relates to fibers that are flash-spun from partially fluorinated hydrocarbon polymers and a solvent.
The art of flash-spinning strands of plexifilamentary film-fibrils from polymer in a solution or a dispersion is known in the art. The term "ple~cifil~m~ntary" means a three-dimensional integral network of a multitude of thin, ribbon-like, film-fibril o elements of random length and with a mean film thickness of less than about 4 microns and with a median fibril width of less than about 25 microns. In plexifil~mentary structures, the film-fibril elements are generally coextensively aligned with the longitudinal axis of the structure and they intermittently unite and separate at irregular intervals in various places throughout the length, width and thickness of the structure to 15 forrn a continuous three-dimensional network.
U.S. Patent 3,227,784 to Blades et al. (~.ci~ned to E. I. du Pont de Nemours &
Company ("DuPont")) describes a process wherein a polymer in solution is forwarded continuously to a spin orifice at a ten~l)e.dl~lre above the boiling point of the solvent, and at autcgenous pressure or greater, and is flash-spun into a zone of lower temperature and 2 o substantially lower pressure to generate a strand of plexifilamentary material. U.S.
Patent 5,192,468 to Coates et al. (~signed to DuPont) discloses another process for flash-spinning a plexifilamentary strand according to which a mechanically generated dispersion of melt-spinnable polymer, c~rbon dioxide and water under high pressure is flashed through a spin orifice into a zone of substantially lower lell,p~.dl~lre and pressure 2 5 to forrn a plexifil~rnent~ry strand.
U.S. Patent 3,227,794 to Anderson et al. (assigned to DuPont) teaches that plexifilamentary film-fibrils are best obtained from solution when fiber-forming polymer is dissolved in a solvent at a tel~p.,.dlLIre and at a pressure above which two liquid phases form. which pressure is generally known as the cloud point pressure at the given3 o temperature. This solution is passed to a pressure let-down chamber, where the pressure decreases below the cloud point pressure for the solution thereby causing phase separation. The resulting two phase dispersion of a solvent-rich phase in a polymer-rich phase is discharged through a spinneret orifice to form the plexifil~mentary strand.
U.S. Patent 3,484,899 to Smith (~ ign~d to DuPont) discloses an apparatus 3 5 wilh a horizontally oriented spin orifice through which a plexifil~ nentary strand can be ~lash-spun. The polymer strand is conventionally directed against a rotating lobed deflector baffle to spread the strand into a more planar web structure that the baf'fle alternatelv directs to the left and right as the web descends to a moving collection belt.
W O 97/25460 PCT~US97/00160 The fibrous sheet formed on the belt has plexifilamentary film-fibril networks oriented in an overlapping multi-directional configuration.
Many improvements to the basic nash-spinning process have been reported or patented over the years. Flash-spinning of olefin polymers to produce non-woven sheets is practiced cornmercially and is the subject of numerous patents including U.S. Patent 3,851,023 to Brethauer et al (assigned to DuPont). Flash-spinning of olefin polymers to produce pulp-like products from polymer solutions is disclosed in U.S. Patent 5,279,776 to Shah (assigned to DuPont). Flash-spinning of olefin polymers to produce microcellular and ultra-microcellular foam products from polymer solutions is disclosed 0 in U.S. Patent 3,227,664 to Blades et al. and 3,5~4,090 to Parrish (assigned to DuPont).
The commercial application for flash-spinning has been primarilv directed to the manufacture of polyolefin ple~ifil~ment~, especially of polyethylene and polvpropylene. However, experimental work directed to the flash-spinning of other polymers, has been reported. For example, U.S. Patent 3,227,784 to Blades et al.describes the flash-spinning of a solution of a perfluoroethylene/perfluoloplopylene (90:
lO) copolymer from a solution in p-bis(trifluoromethyl)benzene (Example 30).
Applicants are not aware of commercial flash-spinning of such fluoropolymers. U.S.
Patents 5,328,946 and 5,364,929 disclose solutions of tetrafluoroethylene polymers at superautogenous pressure in perfluorinated cycloalkane solvents.
2 o As used herein, "partially fluorinated hydrocarbon" refers to an organic compound that would be a hydrocarbon except that one or more of the compound's hydrogen atoms have been replaced by fluorine atoms Partially fluorinated hydrocarbon polymer and copolymer films exhibit a variety of outstanding characteristics such as excellent resi.~t~nce to acids, bases, and most organic liquids under normal temperature and pressure conditions; excellentdielectric properties; good tensile properties; good resistance to heat and weather; a relatively high melting point; and good fire retardance. Partially fluorinated hydrocarbon polymers and copolymer films are extensively used in high value applications such as insulation for high speed electrical tr~n~mi~ion cables. Flash-spun plexifilaments of 3 0 such polymers and copolymers should find wide use in other high value applications such as, for exarnple, hot gas filtration media, pump packings, gaskets, and protective apparel.
However, because of their relatively high melting points and outstanding chemical inertness, partially fluorinated hydrocarbon polymers are very difficult to dissolve, and therefore it had not been possible to flash-spin such polymers. Comrnercially available 3 5 spunbonded fabrics are all made from polyethylene, polypropylene, nylon, and polyester, which are highly combustible. Accordingly, there is a need for nonfl~mm~hle spunbonded fabric for protective garments and other critical end uscs. In ~Id~ iOIl, ~hcr~
is a need for partially fluorinated hydrocarbon polymer and copolymer plexifilaments that exhibit excellent heat and chemical resistance~ good dielectric properties, and good non-stick characteristics. There also is a need for a process suitable for use in commercial flash-spinning of partially fluorinated hydrocarbon polymers using conventional spinnin~
equipment under conventional commercial temperature and pressure conditions SUMMARY OF THE INVENTION
According to the present invention, there is provided a flash-spun material comprised of at least 20% partially fluorinated hydrocarbon polymers in which between 10% and 70% of the total number of hydrogen atoms in each hydrocarbon polymer are 0 replaced by fluorine atoms. Preferably, the partially fluorinated hydrocarbon polymers are comprised of at least 80% by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride. According to one pl~ c,d embodiment of ~e invention, 40% to 70% by weight of the hydrocarbon polymers are comprised of polymerized monomer units of5 tetrafluoroethylene and 10% to 60% of said hydrocarbon polymers are comprised of polymerized monomer units of ethylene. According to another preferred embodiment of the invention, 40% to 70% by weight of the hydrocarbon polymers are be comprised of polymerized monomer units of chlorotrifluoroethylene and 10% to 60% by weight of the hydrocarbon polymers comprised of polymerized monomer units of ethylene. According 2 o to other ~;Çell~d embodiments of the invention, at least 80% by weight of the hydrocarbon polymers are comprised of a homopolymer of either difluoroethylene or fluoroethylene.
The flash-sp~u~ material may be a plexifil~ment~ry strand having a a surface area, measured by the BET nitrogen adsorption method, greater than 2 m2~g. The 2 5 plexifil~ nt~ry strand comprises a three dimensional integral plexus of semicrystalline.
polymeric, fibrous elements that are co-extensively aligned with the axis of theple7~ifil~m~nt and have the structural configuration of oriented film-fibrils. The film-fibrils have a mean film thickness of less than abowt 4 microns and median fibril width of less than about 2S microns. Alternatively, the flash-spun material may be a microcellular 3 0 foam. The invention is also directed to a process for producing flash-sp~ln material from partially fluorinated hydrocarbon polymers in a solvent and a solution from which such polymers may be flash-spun.
The accompanying drawings, which are incorporated in and constitute a part ofthis specification, illustrate the presently preferred embodiments of'the invention allcl.
together with the description, serve to explain the principles of the invention.
Figure l is a plot of the cloud point data for a solution comprised of 25% of anethylene/tetrafluoroethylene copolymer in a solvent comprised of pentane and acetone at a number of different solvent ratios.
Figure 2 is a plot of the cloud point data for a solution comprised of an ethylene/tetrafluoroethylene copolymer at various concentrations in a solvent with a ratio of 70% pentane/ 30% acetone.
Figure 3 is a plot of the cloud point data for a solution of 30% polyvinylidene fluoride in a solvent with a ratio of 60% acetone/ 40% pentane.
Figure 4 is a plot of the cloud point .data for a solution of 35% polyvinyl 0 fluoride in solvents comprised of either 20% pentane and 80% acetone or 100% acetone.
Figure 5 is a plot of the cloud point data for a solution of a 30% copolymer of alternating monomer units of ethylene and chlorotrifluoroethylene in a solvent comprised of pent~ne/acetone at a nurnber of different solvent ratios.
Figure 6 is a plot of the cloud point data for an ethvlene/tetrafluoroethylene copolymer in a number of different solvents.
DETAILED DESCRIPTION
~eference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated below.
2 o The flash-spun partially fluorinated plexifilaments of the invention can be spun using the apparatus and flash-spinning process disclosed and iùlly described in U.S.
Patent 5,147,586 to Shin et al. It is anticipated that in commercial applications, partially fluorinated plexifil:~mentary sheets could be produced using the apparatus disclosed in U.S. Patent 3,851,023 to Brethauer et al.
2 5 The process for flash-spirming plexifilaments from a partially fluorinated hydrocarbon polymer and a solvent operates under conditions of elevated temperature and pressure. The polymeric starting m~teri~l iS norrnally not soluble in the selected solvent under normal temperature and pressure conditions but forms a solution at certain elevated temperatures and pr~ es. We have now found that partially fluorinated hydrocarbon 3 o polymers become soluble in certain types of solvents if high enough t~ ld~lres and pressures are applied. Surprisingly, partially fluorinated hydrocarbon polymers become soluble in certain polar solvents such as alcohols and ketones, and in certain types of chlorinated solvents and hydrofluorocarbons (HFC's) at high temperatures and pressures.
The HFC's are newly developed solvents which have become available recently as a3 5 replacement for ozone depleting fully halogenated chlorofluorocarbons ~CFC's).
As long as the pressure is m~int~ined above the cloud point pressure, ~he partially fluorinated hydrocarbon polymer remains in solution. In the flash-spillning process, pressure is decreased below the cloud point, just before the solution is passed W O 97t25460 PCT/US97/00160 through a spinneret. When the solution pressure is lowered below the cloud pointpressure, the solution phase separates into a polymer-rich phase and a solvent-rich phase.
Upon passing through the spinneret at very high speed into a zone of substantially lower pressure, the solvent flashes off quickly and the polymer material present in the polymer-rich phase freezes in an elongated plç~ifil~mentary form.
The morphology of fiber strands obtained by solution flash-spinning of partially fluorinated hydrocarbon polymer is greatly influenced by the type of solvent in which the polymer is dissolved, the concentration of the polymer in the spin solution, and the spin conditions. To obtain ple~ifil~ment.~, polymer concentration is kept relatively o low (e.g., less than about 3 5 weight percent), while spin temperatures and pressures are generally kept high enough to provide rapid fl~hing of the solvent. Microcellular foam fibers, on the other hand, are usually prepared at relatively high polymer concentrations and at lower spin temperatures and pressures.
Well fibrillated plexifilaments are usually obtained when the spin ternperature used is between the critical temperature of the spin liquid and 40~ C below the critical temperature, and when the spin ple~ure is slightly below the cloud point pressure. When the spin plc,S~eiS much greater than the cloud point pressure of the spin mixture, coarse plexifilamentary "yarn-like" strands are usually obtained. As the spin pressure is gradually decreased, the average distance between the tie points of the fibrils of the 2 o strands generally becomes shorter while the fibrils become progressively finer. When the spin pressure approaches the cloud point pressure of the spin mixture, very fine fibrils are normally obtained, and the distance between the tie points becomes very short. As the spin pressure is further reduced to below the cloud point pressure, the distance between the tie points becomes longer. Well fibrillated ple~cifil~ments, which are most suitable for 2 5 sheet formation. are usually obtained when spin pressures slightly below the cloud point pressure are used. The use of p~es~ es which are too much lower than the cloud point pressure of the spin mixture generally leads to a relatively coarse fiber structure. In some cases~ well fibrillated plexifilaments can be obtained even at spin pressures slightly higher than the cloud point pressure of the spin mixture.
3 o For flash-spinning of microcellular foam fibers, relatively strong solvents are used to obtain relatively low cloud point pressures that are above the cloud point pressure. Microcellular foarns are usually prepared at relatively high polymer concentrations in the spinning solution and at relatively low spinning temperatures and pressures that are above the cloud point pressure. Microcellular foam fibers may be 3 5 obtained rather than ple~ifil~m~nt.~, even at spinning pressures slightly below the cloud point pressure of the solution. Nucleating agents, such as fused silica and kaolin, may be added to the spin mix to facilitate solvent flashinf~ and to obtain unif'orm small si7.e cells.
Microcellular foams can be obtained in a collapsed form or in a fully or partially inllated form. For many polymer/solvent systems~ microcellular foams tend to collapse after exiting the spinning orifice as the solvent vapor condenses inside the cells andl or diffuses out of the cells. To obtain low density inflated foams, infl~ting agents are usually added to the spin liquid. Infl~tin~ agents to be used should have a permeability coefficient for diffusion through the cell walls that is less than that of air so that the agent can stay inside the cells for a long period of time while allowing air to diffuse into the cells to keep the cells infl~terl Osmotic pressure will cause air to diffuse into the cells.
Suitable infl~tin~ agents that can be used include low boiling temperature partially halogenated hydrocarbons and halocarbons such as hydrochlorofluorocarbons, 0 hydrofluorocarbons, chloroflùorocarbons, and perfluorocarbons; inert gases such as carbon dioxide and nitrogen; low boiling tenlp~.dlLIre hydrocarbon solvents such as butane and iso~ e; and other low boiling te,llpcla~u~e organic solvents and gases.
The atmospheric boiling points will be around room temperature or lower.
Microcellular foam fibers are normally spun from a round cross section spin orifice. However, an annular die similar to the ones used for blown films can be used to make microcellular foarn sheets. Fully inflated foams, as-sp~n fibers or as-extruded foam sheets can be post-inflated by immersing them in a solvent cont~ininf~ dissolvedinfl~t~nts Tnfl~t~ntc will diffuse into the cells due to the plasticizing action of the solvent. Once dried, the infl~t~nt~ will stay inside the cells and air will diffuse into the 2 o cells due to osmotic pressure to keep the microcellular foams inflated. Microcellular foarns have densities between 0.005 and 0.50 g/cc. Their cells are generally of a polyhedral shape and their average cell size is less than about 300 microns, and is preferably less than about 150 microns. Their cell walls are typically less than about 3 microns thick, and they are typically less than about 2 microns in thickness.
2 5 Plexifi~ ent~ry pulps of partially fluorinated hydrocarbon polymers can be produced by disc refining flash-spun ple~ifil~ments as disclosed in U.S. Patent 4,608,089 to Gale et al. (assigned to DuPont). Alternatively, such pulps can be prepared directly from polymer solutions by flash-spinning using a device similar to the one disclosed in U.S. Patent 5,279,776. These pulps are plexifil~mentary in nature and they can have a 3 ~ three dimensional network structure. However, the pulp fibers are relatively short in length and they have small dimensions in the transverse direction. The average fiber len~th is less than about 200 microns, and is preferably less than 50 microns. The pulp fibers have a relatively high surface area of greater than 2 m2/g.
Polymers that may be flash-spun to produce the partially fluorinated 3, hydrocarbon polymer plexifilaments of the invention are hydrocarbon polymers in which between 1 ~~/O and 70% of the total number of hydrogen atoms in the hydrocarbon polvmer are replaced by fluorine atoms. Preferably, the partially fluorinated h- drocarbon polymers are comprised of at least 80% by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride. A particularly preferred partially fluorinated hydrocarbon polymer is comprised of 40% to 70% by weight of polymerized monomer units of tetrafluoroethylene and 10% to 60% by weight of polymerized monomer units of ethylene, such as a copolymer comprised of substantially alternating units of ethylene and tetrafluoroethylene with the chemical structure -(CH2CH2)-(CF2CF2)-. Such ethylene/tetrafluoroethylene copolymers are disclosed, for exarnple, in U.S. Patents 3,624,250 to Carlson (assigned to DuPont),3,870,689 to Modena et al., and 4,677,175 to Ihara et al. Ethylene~tetrafluoroethylene copolymer resin is comrnercially available from 0 DuPont under the tradenarne TEFZEL(g1, which is a registered trademark of DuPont.
T~FZEL~) fluoropolymer resins have a melting points between 235~ and 280 ~C.
Another preferred polymer that may be flash-spun to produce the partially fluorinated hydrocarbon polymer plexifilaments of the invention is comprised of 40% to 70% by weight of polymerized monomer units of vinylidene fluoride. Polyvinylidene fluoride polymer resins with the chemical structure -(CH2CF2)- are col.lm~ .eially available from Elf Atochem under the tra~l~n~ KYNAR(~), which is a registered tr~-lem~rk of Elf Atochem. KYNAR~) fluoropolymer resins have a melting point of about 170 ~C.
Other polymers that may be flash-spun to produce the partially fluorinated 2 o hydrocarbon polymer ple~ifil~m~nt~ of the invention include ethylene/
chlorotrifluoroethylene copolymers and polvvinyl fluoride. Other monomer units that may be present in the flash-spun partially fluorinated hydrocarbon polymer plexifilaments include vinyl ethers or branched olefins, either unsubstituted or fluorinated such as, for example, perfluoro(propyl vinyl ether) and perfluoro(butyl vinyl ether).
2 5 While the tel.lpelalu.~ and p~s~u.e conditions that can be withstood by solution flash-spinning equipment are quite broad, it is generally preferred not to operate under extreme temperature and pl~.S:jUI~: conditions. The preferred tellll)el~ure range for flash-spinning the partially fluorinated hydrocarbon polymers flash-spun according to the invention is about 150~ to 300~ C while the preferred pressure range for flash-spinning is 3 o in the range of the autogenous pressure of the solution to 7250 psig (50 MPa), and more preferably from the autogenous pressure of the solution to 3625 psig (25 MPa). As used herein, "autogenous pressure" is the natural vapor pressure of the spin mixture at a given temperature. Therefore, if plexifil~ment.c are to be flash-spun from partially fluorinated hydrocarbon polymers in solution, the solvent should dissolve the partially fluorinated 3 s hydrocarbon polymers at pressures and temperatures within the preferred ranges. In order to generate the two phase solution that is needed for flash-spimling plexifilamentary film-fibrils, the solution must also have a cloud point pressure lllal i~ within the ~iesired pressure and temperature operating ranges. In addition, the solution must form the desired two phases at a pressure that is sufficiently high to ~enerate the explosive fl~hin required for the formation of ple~cifil~ments.
As discussed, partially fluorinated hydrocarbon polymers are not soluble in comrnon solvents under normal conditions. However, we have found that these polymers become soluble in certain types of organic solvents at high temperatures and pressures.
Solvents which are capable of dissolving partially fluorinated hydrocarbon polymers at elevated temperatures and pressures include: polar solvents such as l1alogenated or nonhalogenated alcohols (Cl to C3), ketones (C3 to C5), acetates and carbonates; certain types of hydrochlorocarbons, hydrofluorocarbons (HFC:'s), hydrofluoroethers (HFE's), 0 hydrochlorofluorocarbons (HCFC's) and perfluorinated solvents, and certain types of strong hydrocarbon solvents. It should be noted that not all of the partially fluorinated hydrocarbon polymers are soluble in all of these solvents. For example, poly (ethylene/
tetrafluoroethylene) is soluble in HFC-4310mee and also in cyclopentane at high temperatures and pressures, but polyvinylidene fluoride is not soluble in these solvents. at least up to 250~ C and 4000 psig (27.6 MPa). Suitable flash-spinning agents must be determined for each polymer from the types of solvents listed above.
Preferred solvents for flash-spinnin~ partially fluorinated hydrocarbon polymers will depend on the specific type of polymer to be flash-spun. However, acetone/hydrocarbon solvent (C5 to C6) mixtures, methylene chloride, and n-2 o pentafluorol,lopanol are generally good flash-spinning agents for these polymers. Other flash-spinning agents that can be used for flash-spinning partially fluorinated hydrocarbon polymers include HFC-4310mee, perfluoro-N-methylmorpholine (3M's PF5052), methyl (perfluorobutyl) ether (3M's HFE 7100), dichloroethylene, ethanol, propanols, methyl ethyl ketone, cyclopentane or mixtures of these solvents. In 2 s circumstances where it is desirable to raise the cloud point pressure, minor amounts of poor solvents or nonsolvents can be added to the above solvents in order to raise the cloud point pressure. In the case of mixed solvents, a proper solvent ratio has to be chosen so that cloud point pressures of the polymer solutions to be flash-spun are in the acceptable range (e.g. higher than autogenous pressure but less lower ~50 MPa).
3 o Preferred solvent systems to be used for each polymer will be further illustrated through specific examples.
The apparatus and procedure for det~rminin~ the cloud point pressures of a polymerlsolvent combination are those described in the above-cited U.S. Patent 5,147,586 to Shin et al. The cloud point pressures at different tel~ aLules of a number 3 5 of partially fluorinated hydrocarbons polymers in selected solvents or pairs of solvents are ~iven in ~igs. 1-6. These plots are used in determinin~ whether flash-spinning of a particular polymer/solvent combination is feasible. Above each curve, the copolyn1er is completely dissolved in the solvent system. Belo~ each curve. separation into a WO 97125460 PCT~US97/00160 polymer-rich phase and a solvent-rich phase takes place. At the boundary line, the separation into phases disappears when passing from lower pressures to higher pressures, or phase separation begins when passing from higher pressures to lower pressures.
Figure I is a plot of the cloud point pres~u,e at different temperatures for a solution of 25% by weight l ~G~;L~ fluoropolymer (copolymer of ethylene and tetrafluoroethylene) in a solvent comprised of pentane and acetone. Figure I provides this cloud point curve at three different solvent ratios: 70% pentane/30% acetone ("10");
60% pentane/40% acetone (" 11 "); and 50% pentanel50% acetone (" 12"). l ~ ;L(~ is a registered tr~lem~rk of DuPont.
0 Figure 2 is a plot of the cloud point pressure at dir~le-,t tel~lp~ldLures for a solution of TEFZEL(~\ fluoropolymer (copolymer of ethylene and tetrafluoroethylene) in a solvent at a ratio of 70% pentane/30% acetone. Figure 2 shows the cloud point curve at three different concentrations ofthe fluoropolymer: 20% ("IS"); 35% ("16"); and 40% (" 17") by weight in the solvent.
Figure 3 is a plot of the cloud point pressure at different temperatures for a soiution of 30% by weight KYNAR~) fluoropolymer (polyvinylidene fluoride) in a solvent with a ratio of 60% acetone/40% pentane. KYNAR~ is a registered tradern~rk of Elf Atochem.
Figure 4 is a plot of the cloud point pressure at different temperatures for a 2 o solution of 35% by weight TEDLAR(~ fluoropolymer (polyfluoroethylene) in a solvent with a ratio of 20% pentane/80% acetone ("20"). Figure 4 also shows the cloud point data for a solution of TEDLARt~) fluoropolymer in a solvent comprised of 100% acetone ("21 "). TEDLAR(~) is a registered tr~d~m~rk of DuPont.
Figure 5 is a plot of the cloud point ples~ule at different temperatures for a 2 5 solution of 30% by weight HALAR Z9 fluoropolymer (copolymer of alternating monomer units of ethylene and chlorotrifluoroethylene) in a solvent comprised of pentane and acetone. Figure 5 provides this cloud point data at two different solvent ratios: 70%
pentane/30% acetone ("25"); and 50% pentane/50% acetone ("26"). HALAR(~3 is a re~istered trademark of Ausimont.
3 o Figure 6 is a plot of the cloud point pressure at different temperatures for an ethyleneltetrafluoroethylene copolymer (Tefzel(~) 750 obtained from DuPont) in a number of different solvents. Curve 30 shows the cloud point pressures in a solution of 20%
copolymer in HFC-4310mee (CF3CHFCHFCF2CF3) solvent. Curve 31 shows the cloud point pressures in a solution of 20% copolymer in a solvent of 70% pentane and 30%
3 5 acetone. Curve 32 shows the cloud point pressures in a solution of 12% copolymer in pentafluoropropanol. Curve 33 shows the cloud point pressures in a solution of 20%
copolymer in 2-propanol. Curve 34 shows the cloud point pressures in a solution ol' 12~, copolymer in methylene chloride (CH2C12). Curve 35 shows the cloud point pressures in W O 97/25460 PCT~S97/00160 a solution of 20% copolymer in acetorle. Cur~e 36 shows the cloud point pressures in a solution of 20% cyclopentane(99%).
This invention will now be illustrated by the following non-limiting examples which are intended to illustrate the invention and not to limit the invention in any manner.
EXA~PLES
Test Methods 0 In the description above and in the non-limiting examples that follow, the following test methods were employed to determine various reported characteristics and properties. ASTM refers to the American Society of Testing Materials, and TAPPI refers to the Technical Association of the Pulp and Paper Industry.
The denier of the strand is determined from the weight of a 15 cm sample length of strand.
T~n~.ity, elon~tion and tol~hnf c.~ of the flash-spun strand are deterrnined with an Instron tensile-testing m~f lline. The strands are conditioned and tested at 70~F
and 65% relative humidity. The strands are then twisted to 10 turns per inch andmounted in the jaws of the Instron Tester. A two-inch gauge length was used with an 2 o initial elongation rate of 4 inches per minute. The tenacity at break is recorded in grams per denier (gpd). The elongation at break is recorded as a percentage of the two-inch gauge length of the sample. Toughness is a measure of the work required to break the sample divided by the denier of the sample and is recorded in gpd. Modulus corresponds to the slope of the stress/strain curve and is expressed in units of gpd.
2 5 Fiber qualitv in Examples 22 and 23 was evaluated using a subjective scale of 0 to 3, with a 3 being the highest quality rating. Under the evaluation procedure, a 10 inch length of a ple~cifil~m~ns~ry strand is removed f~om a fiber batt. The web is spread and mounted on a dark substrate. The fiber quality rating is an average of threesubjective ratings, one for fineness of the fibe; (finer fibers receive higher ratings), one 3 o for the continuity of the fiber strand (continuous plexifilamen~ry strands receive a higher rating), and the other for the fre~uency of the ties (more networked ple~ifil~rnenr~ry strands receive a higher rating).
Fiber fineness is measured using a technique similar to that disclosed in U.S.
Patent 5,371,810 to A. Ganesh Vaidyanathan dated 6 December 1994~ and which is 3 5 hereby incorporated by reference. This teclmique quantitatively analyzes fibril size in webs of fiber. The webs are opened up by hand and imaged using a microscopic lens.
The image is then digitized and computer analyzed to determine the mean fibril wid~h .l~
standard deviation. However, some smaller fibrils mav be so tightly bunched together W O 97125460 PCT~US97/00160 and have such short fibril length, that the fibrils appear as part of a large fibril and are counted as such. Tight fibril b1ln~hing and short fibril length (distance from tie point to tie point) can effectively prevent analysis of the finenes~ of individual fibrils in the bunched fibrils. Thus, the term "apparent fibril size" is used to describe or characterize fibers of plexifilamentary strands.
The surface area of the plexifilamentary film-fibril strand product is another measure of the degree and fineness of fibrillation of the flash-spun product. Surface area is measured by the 13ET nitrogen absorption method of S. Brunauer, P. H. Emmett and E.
Teller. J. Am. Chem. Soc.~ V. 60 p 309-319 (1938) and is reported as m2/g.
Test Apparatus for Examples 1 - 21 The apparatus used in the examples 1 - 21 is the spinning apparatus described in U.S. Patent 5,147,586. The apparatus consists of two high pressure cylindrical chambers, each equipped with a piston which is adapted to apply pressure to the contents of the chamber. The cylinders have an inside diameter of 1.0 inch (2.54 cm) and each has an internal capacity of 50 cubic centimeters. The cylinders are connected to each other at one end through a 3132 inch (0.~3 cm) diameter channel and a mixing chamber cont~ining a series of fine mesh screens that act as a static mixer. Mixing is accomplished by forcing the contents of the vessel back and forth between the two 2 o cylinders through the static mixer. A spinneret assembly with a quick-acting means for opening the orifice is attached to the channel through a tee. The spinneret assembly consists of a lead hole of 0.~5 inch (0.63 cm) diameter and about 2.0 inch (5.08 cm) length, and a spinneret orifice with both a length and a diameter shown in the tables below. Orifice measurements are expressed in mils [lmil = 0.0254 mm]. The pistons are 2 5 driven by high pressure water supplied by a hydrauiic system In the tests reported in Examples 1 - 21, the apparatus described above was charged with pellets of a partially fluorinated hydrocarbon polymer and a solvent. High pressure water was used to drive the pistons to generate a mixing ples~ule of between 1500 and 3000 psi (10,340 - 10,680 kPa). The polymer and solvent were next heated to 3 o mixing temperature and held at that temperature for about an hour during which time the pistons were used to alternately establish a differential pressure of about 50 psi (345 kPa) or higher between the two cylinders so as to repeatedly force the polymer and solvent through the mixing channel from one cylinder to the other to provide mixing and effect forrnation of a spin mixture. The spin mixture temperature was then raised to the final 3 5 spin temperature, and held there for about 15 minutes to equilibrate the temperature, durin_ which time mixing was continued. In order to simulate a pressure letdown chamber, the pressure of the spin mixture was reduced to a desired spinnin~ pressure j~lsl prior to spinning. This was accomplished by opening a valve between the spin cell and a much larger tank of high pressure water ("the accumulator") held at the desired spinning pressure. The spinneret orifice is opened about one to five seconds after the opening of the ~alve between the spin cell and the accumulator. This period roughly corresponds to the residence time in the letdown chamber of a commercial spinning apparatus. The 5 resultant flash-spun product is collected in a stainless steel open mesh screen basket. Tlle pressure recorded jUSt before the spinneret using a computer during spinning is entered as the spin pressure.
The experimental conditions and the results for Examples I - 21 are given below in the Tables 1 -5. All the test data not originally obtained in the Sl system of 10 units has been converted to the SI units.
In Examples l-7, a c~polymer of al~ tin~; monomer units of ethylene and tetrafluoroethyl~ne was flash-spun firom a number of solvents. The copolymer used in 15 Examples 1-7 was TEFZEL~) fluoropolymer obtained from DuPont in the following grades:
Name and Grade Melt Flow Rate Melting Point Tefzel 750 7 9/10 min -250~C
Tefzel HT 2129 7 9/10 min ~235~C
Tefzel 200 7 g/10 min -280~C
Tefzel 280 4 g/10 min -280~C
The solvents used include acetone, methy}ene chloride (CH2Cl2) and Vertrel ~45 (perfluoro(dimethylcyclobutane)) obtained from DuPont.
Table POLYMER SOLVENT MIXING SPNNING Properties @1 ~ExWt IISlIS2 ~Press Odfice Pmss~ IMcd Ten EETI
No. NAME % 1 ! 2 I Wrh ~C !MinlMPa DxLmils MPa C Denlgpd gpd E%l SAlType TEFZEL VERTREL
1 ~HT750) 12 CH2C12 245 SOt50 200 60 13.8 30X30 7.6 200 217 2~69 1.37 30.7lnmlplex TEFZEL
2 ~HT750) 25 PENTANE ACETONE 70130 220 17.2 30X30 9.7 220 285 O.9B 1.01 35 nm ~ plex TEFZEL
3 ~200) 35 PENTANE ACETONE 70130 250 60 20.7 30X30 11.7 250 448 0.97 1.21 29 22 I plex TEFZEL
4 ~2g0) 35 PENTANE ACETONE 70130 250 45 20.7 30X30 t1.7 250 36910.96 1.6 27 nm I plex TEFZEL ~ i I
S ~(HT2129) 35 PENTANE ACETONE B0120 230 45 20.7 30X30 12.4 230 418i l.S9 1.3 1 28 I nm plex ,TEFZEL
6 i(H750) 40 PENTANE ACETONE B0120 220 60 20.7 30X30 1 10.3 220 8521 1.0 1.26i 2B i 30 plex TEFzEL ' ' 7 (HT750) SS ACETONEINONE j10010 220 60 13.8 4X4 13.8!223 3018.38 1.341 25 1 67 .foaml 2 o ,~oo~note nm = not rneasured ~
W O ~7125460 PCT/US97/00160 EXA MPLES 8-1?.
In Exarnples 8-12~ the following K~r~AR~) fluoropolymer resin obtained from Elf Atochem. comprised of polymerized monomer unils of vinylidene fluoride, was flash-spun from a number of solvents:
Name and Grade Melt Flow Rate Melting Point Kynar 760 2~ gl10 min 165-1 70~C
The solvents used include acetone~ ethanol, pentane, 2-propanol, methylene chloride (CH2C12). and HFC-4310mee (CF3CHFCHFCF2CF3).
Table 2 POLYMER OLVENT UIX1~ SPI~NING ¦ Pro~-erties @10Pi Ex. Wt SllS2 Press Orifice Press Mod Ten I E I EET ¦
No. NAME ~/0 1 2 Wl~h ~C Mh MPa D~Lmils MPa ~C Den gpd gpd~%l SAIType 8 KYNAR(760)12 CH2C12 HFC-43-10mee 75125 200 45 17.2 30X30 10.7 200 224 0.93 1.11iB41 nm Iplex 9 KYNAR(760)30 2-PROPANOL NONE ,100/0 23G 60 13.8 30X30 5.5 232 328 3.6 1 56i62110.41 pbx 10 KYNAR(7tQ)30 ACETONE PENTANE 601401210 60 17.21 30%30 11 210 407 0.88 1.15 60 nm ,plex 11 KYNAR(760)130 ETHANOL I NONE 100/0i250 60 17.2 30X30 9.0 248 259 2.7 1.25 73 7.56iplex 12 KYNAR(760)145 ACETONE I NONE 100/0i220 60 13.B I 4X4 13.8 224 18.4 3.96 1.64 68 61.11bam In Examples 13 and 14, the following HALAR~) fluoropolymer resin obtained from Ausimont, and comprised of a copolymer of polymerized monomer units of 5 ethylene and chlorotrif~uoroethylene, was flash-spun from a number of solvents identified in the examples above.
Name and Grade Melt Index Meltin~ Point Halar 200 0.7 240~C
The solvents include pentane, acetone, and methylene chloride (CHC12).
2 o Table 3 POLYMER SOLVENT U KING SPINNING Propenies @10tpi EI. W S11S2 ¦ Press Orifice iPress Mod Ten I i EET
No. NAME % 1 ' 2 Wt~6 ~C Minl MPa DxLmilslMPa ~C Den gpd gpdlE%~ SA Type l3 I HALAR(200~ 30 PENTANE ACETONE 50/50 220-230 75 20.7 1 30X30 12.7 240 496 3.7911.44 24 117.6 plex ~4, HALAR(200) 38, CH2C12 NONE 100/0 160 30 10.3 . 30x30 4.7 159 nm nm I nm nm I nm bam In Example 15, the following TEDLAR(g) fluoropolymer resin obtained from 5 DuPont, and comprised of polymerized monomer units of vinyl fluoride, was flash-spun from an acetone/pentane solvent system:
Name and Grade Melting Poin~
Tedlar PV318 190~C
(High MW grade) Table 4 PO~YMER SOLVENT MIXNG SPI~NING I Proper~es @10tpi Ex. Wt S1/S2 Press Orifice Press I Mod Ten l6ET
No. NAME % 1 2 Wt% ~C Min MPa OxLmils MPa ~C.Dem gpd gpd E% SA Type ,5 Tedlar 40 ACETONE ! PENTANE B0120 i 160 60 1S00 30x30 1 1125 160 ~ nm nm, nm nm nm Pulp The solvents include acetone and pentane.
In Exarnples 16-21, polymer blends of ALATHON~ polyethylene obtained from Lyondell Petrochemical Company and KYNAR~ polyvinylidene fluoride obtained 0 from Elf Atochem were flash-spun from di~ferent solvents. The Kynar described above with Examples 8-12. The polyethylene was the following high density polyethylene:
Polvmer Name and Grade Melt Index Density AvQ. Molecular Weight PE Alathon -0.7~ -0.957 -125,000 Table 5 POLYME~ SOLVENT MIXING SPI~NING Proper(iese10TPI
Orifioe Ex. W S1/S2 Pness DxL Press Mod Ten E BET
No. Name % 1 2 Wt% ~C Min MPa mils MPa ~C Den gpd gpd % SA Type PE Alalhon C,;'~
16 Kynar(760) 30 99% Acebne 60140 250 45 13.8 30X30 6.7 200 345 4.7 2.9 74 nm plex PE Alathon HFC43-17 Kynar(760) 12CH2CI2 10mee a0120 200 60 17.2 30X30 11.0 200 2B2 6.1 2.3 76 nm plex PE Ala~on HFC 43-18 Kynar(760) 12CH2CI2 10mee 80120 200 60 17.2 30X30 10.3 200 283 5.9 2.3 99 8.2 plex PE Alathon HFC43-19 Kynar(760) 12CH2C12 10mee 80120 200 60 17.'' 30X30 10.2 199 299 3.8 1.6 102 nrn plex PE AlaU~on HFC43-Kynar(760) 12CH2CI2 10mee B0120 200 60 17.2 30X30 110 202 279 8.6 3.6 88 12 plex PE Alathon HFC43-21 Kynar(760) 12CH2CI2 10mee 80120 200 60 17.2 30X30 11.0 202 252 9.2 3.8 86 nm plex The solvents include cyclopentane. acetone and HFC-43 1 Omee (CF3 CHFCHFCF2CF3 ) .
W O 97/25460 PCT~US97tO0160 Test ~pparatus for F.~ ples 22 and 23 In Examples 22 and 23, plexifil~mçnts were spun from a spin mixture that comprised a partially fluorinated hydrocarbon polymer or copolymer dispersed in a spin agent. The spin mixture, was generated in a continuous rotary mixer, as described in U.S.
Patent Application Serial No. 60/005,875. The mixer operated at tenl,v~.d1ures up to 300~
C and at pressures up to 41,000 kPa. The mixer had a polymer inlet through which a polymer melt blend was continuously introduced into the mixer. The mixer also had a C~2 inlet through which supercritical CO2 was continuously introduced into the polymer stream entering the mixer ~efore the polymer entered the mixing chamber of the 0 mixer. The mixer had a mixing chamber where polymer and CO2 were thoroughly sheared and mixed by a combination of rotating and fixed cutting blades. The mixer further included an injection port through which water was introduced into the mixing charnber at a point downstrearn of where the polymer and CO2 were initially mixed in the mixing charnber. At least one additional set of rotating and fixed cutting blades in the 5 mixing chamber further mixed the polymer, CO2 and water before the mixture wascontinuously discharged from the mixer's mixing chamber. The volume of the mixer's mixing chamber between the point where the polymer first contacts C~2 plasticizing agent and the mixer outlet was 495 cm3.
The mixer was operated at a rotational rate of approximately 1200 rpm with 2 o power of between 7 and 10 kW. Polymer was injected into the mixer by a polymer screw extruder and gear pump. Supercritical CO2 plasticizing agent from a pressurized storage tank and distilled water from a closed storage tank were both injected into the mixer by double acting piston pumps. A dispersion of polymer, supercritical CO2 and water was generated in the mixer's mixing chamber. The spin mixture was discharged from the 2 5 mixer and passed through a heated transfer line to a 31 mil diameter round spin orifice from which the mixture was flash-spun into a zone m~int~ined at atmospheric pressure and room temperature. The residence time of the polymer in the mixer's mixing chamber was generally between 7 and 20 seconds. Unless stated otherwise, the spinning temperature was approximately 240~ C and the spinning pressure was approximately3 o ~ 8,900 kPa. The spin products were collected on a moving belt from which samples were removed for e~c~mins3tion and testing.
The polymers that were flash-spun in Examples 22 and 23 were blends of TEFZEL~) 2129 fluoropolymer (described above) and 4GT polyester. One 4GT
polyester used in the following examples was CRASTIN(~ 6131 obtained from DuPont3 5 of Wilmington, Delaware. CRASTINt~ is a registered trademaric of DuPont.
CRASTlN(g) 6131 was formerly sold under the name RYNITE~) 61 31 . CR~STIN(i~
6131 is a non-reinforced low molecular wei~ht 4GT polycsl~r. C'RA~; I'lN~ G 13 1 h.~s .
melt flow rate of 42g/10 min by standard techniques at a temperature of 250~C with a W O 97/2~460 PCTAUS97/00160 2.16 kg weight, and has a melting point of 225~C (hereinafter "4GT-6131 "). A second 4GT polyester used in the following examples was CRASTIN~) 6130 obtained from DuPont of Wilmington, Delaware. CRASTIN(~ 6130 is a non-reinforced 4GT polyesterwith a higher molecular weight than CRASTIN~ 6131. CRASTIN(~) 6130 has a melt flow rate of 12.~ g/10 min by standard techniques at a temperature of 250~C with a 2.16 kg weight, and has a melting point of 225~C. ("4GT-6130") EXAM~'LE 22 A melted blend of 35% 4GT-6131, 35% 4GT-613(), and 30% Tefzel 2129 was o injected into a continuous mixer and was mixed with CO2 and wa~er as described above.
The polymer/CO2 ratio in the mixer was 1.25 and the polymerlwater ratio in the mixer was 2.86. The mixture was subsequently flash-spun from a 31 mil (0.787 mm) diameter spinning orifice for approximately 15 minutes. A plexifilamentary fiber strand was obtained that had a tenacity of 0.58 gpd, an elongation of 31.8%, a toughness of 0.11 gpd, î 5 a surface area of 9.9 gm2, and a fiber quality rating of I .5.
A melted blend of 40% 4GT-6131, 40% 4GT-6130, and 20% Tefzel 2129 was injected into a continuous mixer and was mixed with CO2 and water as described above.
2 o The polymer/CO2 ratio in the mixer was 1.25 and the polymerlwater ratio in the mixer was 2.86. The mixture was subsequently flash-spun from a 31 mil (0.787 mm) diameter spinning orifice for approximately 15 minl~tes A ple~cifil~ment~ry fiber strand was obtained that had a tenacity of 0.52 gpd, an elongation of 30.1 %, a tol-~hn~ss of 0.09 gpd, a surface area of 14.5 glm2, and a fiber quality rating of 1.~.
It will be apparent to those skilled in the art that modifications and variations can be made in the flash-spinning apparatus and process of this invention. The invention in its broader aspects is, therefore, not limited to the specific details or the illustrative examples described above. Thus, it is intended that all matter contained in the foregoin~
3 o description, drawings and examples shall be inte~preted as illustrative and not in a limiting sense.
S ~(HT2129) 35 PENTANE ACETONE B0120 230 45 20.7 30X30 12.4 230 418i l.S9 1.3 1 28 I nm plex ,TEFZEL
6 i(H750) 40 PENTANE ACETONE B0120 220 60 20.7 30X30 1 10.3 220 8521 1.0 1.26i 2B i 30 plex TEFzEL ' ' 7 (HT750) SS ACETONEINONE j10010 220 60 13.8 4X4 13.8!223 3018.38 1.341 25 1 67 .foaml 2 o ,~oo~note nm = not rneasured ~
W O ~7125460 PCT/US97/00160 EXA MPLES 8-1?.
In Exarnples 8-12~ the following K~r~AR~) fluoropolymer resin obtained from Elf Atochem. comprised of polymerized monomer unils of vinylidene fluoride, was flash-spun from a number of solvents:
Name and Grade Melt Flow Rate Melting Point Kynar 760 2~ gl10 min 165-1 70~C
The solvents used include acetone~ ethanol, pentane, 2-propanol, methylene chloride (CH2C12). and HFC-4310mee (CF3CHFCHFCF2CF3).
Table 2 POLYMER OLVENT UIX1~ SPI~NING ¦ Pro~-erties @10Pi Ex. Wt SllS2 Press Orifice Press Mod Ten I E I EET ¦
No. NAME ~/0 1 2 Wl~h ~C Mh MPa D~Lmils MPa ~C Den gpd gpd~%l SAIType 8 KYNAR(760)12 CH2C12 HFC-43-10mee 75125 200 45 17.2 30X30 10.7 200 224 0.93 1.11iB41 nm Iplex 9 KYNAR(760)30 2-PROPANOL NONE ,100/0 23G 60 13.8 30X30 5.5 232 328 3.6 1 56i62110.41 pbx 10 KYNAR(7tQ)30 ACETONE PENTANE 601401210 60 17.21 30%30 11 210 407 0.88 1.15 60 nm ,plex 11 KYNAR(760)130 ETHANOL I NONE 100/0i250 60 17.2 30X30 9.0 248 259 2.7 1.25 73 7.56iplex 12 KYNAR(760)145 ACETONE I NONE 100/0i220 60 13.B I 4X4 13.8 224 18.4 3.96 1.64 68 61.11bam In Examples 13 and 14, the following HALAR~) fluoropolymer resin obtained from Ausimont, and comprised of a copolymer of polymerized monomer units of 5 ethylene and chlorotrif~uoroethylene, was flash-spun from a number of solvents identified in the examples above.
Name and Grade Melt Index Meltin~ Point Halar 200 0.7 240~C
The solvents include pentane, acetone, and methylene chloride (CHC12).
2 o Table 3 POLYMER SOLVENT U KING SPINNING Propenies @10tpi EI. W S11S2 ¦ Press Orifice iPress Mod Ten I i EET
No. NAME % 1 ' 2 Wt~6 ~C Minl MPa DxLmilslMPa ~C Den gpd gpdlE%~ SA Type l3 I HALAR(200~ 30 PENTANE ACETONE 50/50 220-230 75 20.7 1 30X30 12.7 240 496 3.7911.44 24 117.6 plex ~4, HALAR(200) 38, CH2C12 NONE 100/0 160 30 10.3 . 30x30 4.7 159 nm nm I nm nm I nm bam In Example 15, the following TEDLAR(g) fluoropolymer resin obtained from 5 DuPont, and comprised of polymerized monomer units of vinyl fluoride, was flash-spun from an acetone/pentane solvent system:
Name and Grade Melting Poin~
Tedlar PV318 190~C
(High MW grade) Table 4 PO~YMER SOLVENT MIXNG SPI~NING I Proper~es @10tpi Ex. Wt S1/S2 Press Orifice Press I Mod Ten l6ET
No. NAME % 1 2 Wt% ~C Min MPa OxLmils MPa ~C.Dem gpd gpd E% SA Type ,5 Tedlar 40 ACETONE ! PENTANE B0120 i 160 60 1S00 30x30 1 1125 160 ~ nm nm, nm nm nm Pulp The solvents include acetone and pentane.
In Exarnples 16-21, polymer blends of ALATHON~ polyethylene obtained from Lyondell Petrochemical Company and KYNAR~ polyvinylidene fluoride obtained 0 from Elf Atochem were flash-spun from di~ferent solvents. The Kynar described above with Examples 8-12. The polyethylene was the following high density polyethylene:
Polvmer Name and Grade Melt Index Density AvQ. Molecular Weight PE Alathon -0.7~ -0.957 -125,000 Table 5 POLYME~ SOLVENT MIXING SPI~NING Proper(iese10TPI
Orifioe Ex. W S1/S2 Pness DxL Press Mod Ten E BET
No. Name % 1 2 Wt% ~C Min MPa mils MPa ~C Den gpd gpd % SA Type PE Alalhon C,;'~
16 Kynar(760) 30 99% Acebne 60140 250 45 13.8 30X30 6.7 200 345 4.7 2.9 74 nm plex PE Alathon HFC43-17 Kynar(760) 12CH2CI2 10mee a0120 200 60 17.2 30X30 11.0 200 2B2 6.1 2.3 76 nm plex PE Ala~on HFC 43-18 Kynar(760) 12CH2CI2 10mee 80120 200 60 17.2 30X30 10.3 200 283 5.9 2.3 99 8.2 plex PE Alathon HFC43-19 Kynar(760) 12CH2C12 10mee 80120 200 60 17.'' 30X30 10.2 199 299 3.8 1.6 102 nrn plex PE AlaU~on HFC43-Kynar(760) 12CH2CI2 10mee B0120 200 60 17.2 30X30 110 202 279 8.6 3.6 88 12 plex PE Alathon HFC43-21 Kynar(760) 12CH2CI2 10mee 80120 200 60 17.2 30X30 11.0 202 252 9.2 3.8 86 nm plex The solvents include cyclopentane. acetone and HFC-43 1 Omee (CF3 CHFCHFCF2CF3 ) .
W O 97/25460 PCT~US97tO0160 Test ~pparatus for F.~ ples 22 and 23 In Examples 22 and 23, plexifil~mçnts were spun from a spin mixture that comprised a partially fluorinated hydrocarbon polymer or copolymer dispersed in a spin agent. The spin mixture, was generated in a continuous rotary mixer, as described in U.S.
Patent Application Serial No. 60/005,875. The mixer operated at tenl,v~.d1ures up to 300~
C and at pressures up to 41,000 kPa. The mixer had a polymer inlet through which a polymer melt blend was continuously introduced into the mixer. The mixer also had a C~2 inlet through which supercritical CO2 was continuously introduced into the polymer stream entering the mixer ~efore the polymer entered the mixing chamber of the 0 mixer. The mixer had a mixing chamber where polymer and CO2 were thoroughly sheared and mixed by a combination of rotating and fixed cutting blades. The mixer further included an injection port through which water was introduced into the mixing charnber at a point downstrearn of where the polymer and CO2 were initially mixed in the mixing charnber. At least one additional set of rotating and fixed cutting blades in the 5 mixing chamber further mixed the polymer, CO2 and water before the mixture wascontinuously discharged from the mixer's mixing chamber. The volume of the mixer's mixing chamber between the point where the polymer first contacts C~2 plasticizing agent and the mixer outlet was 495 cm3.
The mixer was operated at a rotational rate of approximately 1200 rpm with 2 o power of between 7 and 10 kW. Polymer was injected into the mixer by a polymer screw extruder and gear pump. Supercritical CO2 plasticizing agent from a pressurized storage tank and distilled water from a closed storage tank were both injected into the mixer by double acting piston pumps. A dispersion of polymer, supercritical CO2 and water was generated in the mixer's mixing chamber. The spin mixture was discharged from the 2 5 mixer and passed through a heated transfer line to a 31 mil diameter round spin orifice from which the mixture was flash-spun into a zone m~int~ined at atmospheric pressure and room temperature. The residence time of the polymer in the mixer's mixing chamber was generally between 7 and 20 seconds. Unless stated otherwise, the spinning temperature was approximately 240~ C and the spinning pressure was approximately3 o ~ 8,900 kPa. The spin products were collected on a moving belt from which samples were removed for e~c~mins3tion and testing.
The polymers that were flash-spun in Examples 22 and 23 were blends of TEFZEL~) 2129 fluoropolymer (described above) and 4GT polyester. One 4GT
polyester used in the following examples was CRASTIN(~ 6131 obtained from DuPont3 5 of Wilmington, Delaware. CRASTINt~ is a registered trademaric of DuPont.
CRASTlN(g) 6131 was formerly sold under the name RYNITE~) 61 31 . CR~STIN(i~
6131 is a non-reinforced low molecular wei~ht 4GT polycsl~r. C'RA~; I'lN~ G 13 1 h.~s .
melt flow rate of 42g/10 min by standard techniques at a temperature of 250~C with a W O 97/2~460 PCTAUS97/00160 2.16 kg weight, and has a melting point of 225~C (hereinafter "4GT-6131 "). A second 4GT polyester used in the following examples was CRASTIN~) 6130 obtained from DuPont of Wilmington, Delaware. CRASTIN(~ 6130 is a non-reinforced 4GT polyesterwith a higher molecular weight than CRASTIN~ 6131. CRASTIN(~) 6130 has a melt flow rate of 12.~ g/10 min by standard techniques at a temperature of 250~C with a 2.16 kg weight, and has a melting point of 225~C. ("4GT-6130") EXAM~'LE 22 A melted blend of 35% 4GT-6131, 35% 4GT-613(), and 30% Tefzel 2129 was o injected into a continuous mixer and was mixed with CO2 and wa~er as described above.
The polymer/CO2 ratio in the mixer was 1.25 and the polymerlwater ratio in the mixer was 2.86. The mixture was subsequently flash-spun from a 31 mil (0.787 mm) diameter spinning orifice for approximately 15 minutes. A plexifilamentary fiber strand was obtained that had a tenacity of 0.58 gpd, an elongation of 31.8%, a toughness of 0.11 gpd, î 5 a surface area of 9.9 gm2, and a fiber quality rating of I .5.
A melted blend of 40% 4GT-6131, 40% 4GT-6130, and 20% Tefzel 2129 was injected into a continuous mixer and was mixed with CO2 and water as described above.
2 o The polymer/CO2 ratio in the mixer was 1.25 and the polymerlwater ratio in the mixer was 2.86. The mixture was subsequently flash-spun from a 31 mil (0.787 mm) diameter spinning orifice for approximately 15 minl~tes A ple~cifil~ment~ry fiber strand was obtained that had a tenacity of 0.52 gpd, an elongation of 30.1 %, a tol-~hn~ss of 0.09 gpd, a surface area of 14.5 glm2, and a fiber quality rating of 1.~.
It will be apparent to those skilled in the art that modifications and variations can be made in the flash-spinning apparatus and process of this invention. The invention in its broader aspects is, therefore, not limited to the specific details or the illustrative examples described above. Thus, it is intended that all matter contained in the foregoin~
3 o description, drawings and examples shall be inte~preted as illustrative and not in a limiting sense.
Claims (13)
1. A flash-spun material comprised of at least 20% partially fluorinated hydrocarbon polymers wherein between 10% and 70% of the total number of hydrogenatoms in each of said partially fluorinated hydrocarbon polymers are replaced by fluorine atoms.
2. The material of claim 1 wherein said partially fluorinated hydrocarbon polymers are comprised of at least 80% by weight of polymerized monomer units selected from ethylene, tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride and vinyl fluoride.
3. The material of claim 2 wherein 40% to 70% by weight of said partially fluorinated hydrocarbon polymers are comprised of polymerized monomer units of tetrafluoroethylene and 10% to 60% of said partially fluorinated hydrocarbon polymers are comprised of polymerized monomer units of ethylene.
4. The material of claim 2 wherein 40% to 70% by weight of said partially fluorinated hydrocarbon polymers are comprised of polymerized monomer units of chlorotrifluoroethylene and 10% to 60% by weight of said partially fluorinated hydrocarbon polymers are comprised of polymerized monomer units of ethylene.
5. The material of claim 2 wherein at least 80% by weight of said partially fluorinated hydrocarbon polymers are comprised of a homopolymer of vinylidene fluoride.
6. The material of claim 2 wherein at least 80% by weight of said partially fluorinated hydrocarbon polymers are comprised of a homopolymer of vinyl fluoride.
7. The material of claim 1, 2, 3, 4, 5 or 6 wherein said material is a plexifilamentary strand having a surface area, measured by the BET nitrogen adsorption method, greater than 2 m2/g comprising a three dimensional integral plexus of semicrystalline, polymeric, fibrous elements, said elements being co-extensively aligned with the network axis and having the structural configuration of oriented film-fibrils, said film-fibrils having a mean film thickness of less than 4 microns and a median width of less than 25 microns.
8. A plexifilamentary pulp material comprised of the plexifilamentary strand of Claim 7 wherein each of said film-fiorils has an average length of less than 3 mm.
9. The fiber of claim 1, 2, 3, 4, 5 or 6 wherein said material is a microcellular foam comprising substantially polyhedral cells of polymeric material having thinfilm-like cell walls with a mean thickness of less than 4 microns between adjoining cells.
10. A process for the production of flash-spun material comprised of at least 20% partially fluorinated hydrocarbon polymers wherein between 10% and 70% of the total number of hydrogen atoms in each of said partially fluorinated hydrocarbonpolymers are replaced by fluorine atoms, which comprises the steps of:
forming a Spill solution of said partially fluorinated hydrocarbon polymers in asolvent, said spin solution having a cloud point pressure of less than 50 MPa attemperatures in the range of 150°C to 280°C, said solvent having an atmospheric boiling point between 0°C and 150°C, and being selected from the group consisting of alcohols, ketones, acetates, carbonates, chlorinated hydrocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers, perfluoroethers, and cyclic hydrocarbons having five to twelve carbon atoms; and spinning said spin solution at a pressure that is greater than the autogenous pressure of the spin solution into a region of substantially lower pressure and at a temperature at least 50°C higher than the atmospheric boiling point of the solvent.
forming a Spill solution of said partially fluorinated hydrocarbon polymers in asolvent, said spin solution having a cloud point pressure of less than 50 MPa attemperatures in the range of 150°C to 280°C, said solvent having an atmospheric boiling point between 0°C and 150°C, and being selected from the group consisting of alcohols, ketones, acetates, carbonates, chlorinated hydrocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers, perfluoroethers, and cyclic hydrocarbons having five to twelve carbon atoms; and spinning said spin solution at a pressure that is greater than the autogenous pressure of the spin solution into a region of substantially lower pressure and at a temperature at least 50°C higher than the atmospheric boiling point of the solvent.
11. The process of claim 10 wherein said spin solution is spun at a pressure below the cloud point pressure of the spin solution to form plexifilamentary film-fibril strands.
12. The process of Claim 10 wherein said spin solution is spun at a pressure above the cloud point pressure of the spin solution to form a foam.
13. A solution comprising:
a solvent selected from the group consisting of alcohols, ketones, acetates, carbonates, chlorinated hydrocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers, perfluoroethers, cyclic hydrocarbons having five to twelve carbon atoms and blends thereof, said solvent having an atmospheric boiling point of less than 200°C, and a polymer comprised of at least 20% partially fluorinated hydrocarbon polymers wherein between 10% and 70% of the total number of hydrogen atoms in each of said partially fluorinated hydrocarbon polymers are replaced by fluorine atoms, wherein the solution is at a pressure between the autogenous pressure and 50 MPa and at a temperature of between 150° to 200°C.
a solvent selected from the group consisting of alcohols, ketones, acetates, carbonates, chlorinated hydrocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, hydrofluoroethers, perfluoroethers, cyclic hydrocarbons having five to twelve carbon atoms and blends thereof, said solvent having an atmospheric boiling point of less than 200°C, and a polymer comprised of at least 20% partially fluorinated hydrocarbon polymers wherein between 10% and 70% of the total number of hydrogen atoms in each of said partially fluorinated hydrocarbon polymers are replaced by fluorine atoms, wherein the solution is at a pressure between the autogenous pressure and 50 MPa and at a temperature of between 150° to 200°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US973996P | 1996-01-11 | 1996-01-11 | |
| US60/009,739 | 1996-01-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2242468A1 true CA2242468A1 (en) | 1997-07-17 |
Family
ID=21739430
Family Applications (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002242469A Abandoned CA2242469A1 (en) | 1996-01-11 | 1997-01-09 | Plexifilamentary strand of blended polymers |
| CA002242470A Abandoned CA2242470A1 (en) | 1996-01-11 | 1997-01-09 | Fibers flash-spun from blends of polyolefin polymers |
| CA002242468A Abandoned CA2242468A1 (en) | 1996-01-11 | 1997-01-09 | Fibers flash-spun from partially fluorinated polymers |
Family Applications Before (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002242469A Abandoned CA2242469A1 (en) | 1996-01-11 | 1997-01-09 | Plexifilamentary strand of blended polymers |
| CA002242470A Abandoned CA2242470A1 (en) | 1996-01-11 | 1997-01-09 | Fibers flash-spun from blends of polyolefin polymers |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US6004672A (en) |
| EP (3) | EP0876520B1 (en) |
| JP (3) | JP3839489B2 (en) |
| KR (3) | KR19990077167A (en) |
| CA (3) | CA2242469A1 (en) |
| DE (3) | DE69702115T2 (en) |
| ES (3) | ES2146982T3 (en) |
| WO (3) | WO1997025460A1 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2759090B1 (en) * | 1997-02-04 | 1999-03-05 | Atochem Elf Sa | CLEANING OR DRYING COMPOSITIONS BASED ON 1,1,1,2,3,4,4,5,5,5-DECAFLUOROPENTANE |
| US5985196A (en) * | 1998-01-20 | 1999-11-16 | E. I. Du Pont De Nemours And Company | Flash spinning process and flash spinning solution |
| US6153134A (en) * | 1998-12-15 | 2000-11-28 | E. I. Du Pont De Nemours And Company | Flash spinning process |
| US7179413B1 (en) * | 1999-08-20 | 2007-02-20 | E. I. Du Pont De Nemours And Company | Flash-spinning process and solution |
| EP1222326B1 (en) * | 1999-10-18 | 2005-10-12 | E.I. Du Pont De Nemours And Company | Flash-spun sheet material |
| US6458304B1 (en) | 2000-03-22 | 2002-10-01 | E. I. Du Pont De Nemours And Company | Flash spinning process and solutions of polyester |
| GB0030182D0 (en) * | 2000-12-11 | 2001-01-24 | Univ Brunel | Material processing |
| US7435369B2 (en) | 2001-06-06 | 2008-10-14 | Bpb Plc | Method for targeted delivery of additives to varying layers in gypsum panels |
| US6524679B2 (en) | 2001-06-06 | 2003-02-25 | Bpb, Plc | Glass reinforced gypsum board |
| US20050029695A1 (en) | 2002-09-25 | 2005-02-10 | Weinberg Mark Gary | Surface-modified plexifilamentary structures, and compositions therefor |
| BRPI0409518B1 (en) * | 2003-04-03 | 2014-08-19 | Du Pont | Process, rotational spinning apparatus and fibrous nonwoven sheet |
| US7943699B2 (en) | 2003-10-21 | 2011-05-17 | E. I. Du Pont De Nemours And Company | Ethylene copolymer modified oriented polyester films, tapes, fibers and nonwoven textiles |
| EP1730332B1 (en) * | 2004-04-01 | 2012-08-08 | E.I. Du Pont De Nemours And Company | Rotary process for forming uniform material |
| US20070202764A1 (en) * | 2005-04-01 | 2007-08-30 | Marin Robert A | Rotary process for forming uniform material |
| CN102186921B (en) | 2008-10-16 | 2014-01-15 | 旭硝子株式会社 | Fluorine-containing copolymer composition and process for production thereof |
| JP5673532B2 (en) | 2009-07-01 | 2015-02-18 | 旭硝子株式会社 | Fluorine-containing copolymer composition and method for producing the same |
| EP2559729A4 (en) | 2010-04-16 | 2015-03-25 | Asahi Glass Co Ltd | Fluorine-containing copolymer composition and production method for same |
| EP3091038B1 (en) | 2010-12-21 | 2019-09-18 | Dow Global Technologies LLC | Olefin-based polymers and dispersion polymerizations |
| US10920028B2 (en) * | 2014-06-18 | 2021-02-16 | Dupont Safety & Construction, Inc. | Plexifilamentary sheets |
| US11261543B2 (en) * | 2015-06-11 | 2022-03-01 | Dupont Safety & Construction, Inc. | Flash spinning process |
Family Cites Families (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1106307A (en) * | 1953-05-11 | 1955-12-16 | Thomson Houston Comp Francaise | Process for manufacturing chlorotrifluoroethylene into fibers |
| BE625998A (en) * | 1960-11-08 | 1900-01-01 | ||
| US3227664A (en) * | 1961-12-07 | 1966-01-04 | Du Pont | Ultramicrocellular structures of crystalline organic polymer |
| US3081519A (en) * | 1962-01-31 | 1963-03-19 | Fibrillated strand | |
| NL300881A (en) * | 1962-11-23 | |||
| US3484899A (en) * | 1967-04-06 | 1969-12-23 | Du Pont | Spinneret pack for flash extrusion |
| US3851023A (en) * | 1972-11-02 | 1974-11-26 | Du Pont | Process for forming a web |
| IT995549B (en) * | 1973-10-02 | 1975-11-20 | Anic Spa | PROCEDURE FOR THE PRODUCTION OF FIBROUS STRUCTURES |
| US4127623A (en) * | 1974-08-03 | 1978-11-28 | Sumitomo Chemical Company, Limited | Process for producing polyolefin short fibers |
| DE3308626C2 (en) * | 1983-03-11 | 1986-02-20 | Dynamit Nobel Ag, 5210 Troisdorf | Process for the production of fibrids from thermoplastics |
| CA2029550C (en) * | 1989-11-22 | 2001-07-31 | Don Mayo Coates | Process for flash spinning polyolefins |
| US5147586A (en) * | 1991-02-22 | 1992-09-15 | E. I. Du Pont De Nemours And Company | Flash-spinning polymeric plexifilaments |
| US5328946A (en) * | 1991-08-29 | 1994-07-12 | E. I. Du Pont De Nemours And Company | Solvents for tetrafluoroethylene polymers |
| US5371810A (en) * | 1991-09-27 | 1994-12-06 | E. I. Du Pont De Nemours And Company | Method of determining the interior points of an object in a background |
| US5290846A (en) * | 1992-08-28 | 1994-03-01 | E. I. Du Pont De Nemours And Company | Solvents for fluorinated polymers |
| US5364929A (en) * | 1993-01-13 | 1994-11-15 | E. I. Du Pont De Nemours And Company | Dissolution of tetrafluoroethylene polymers at superautogenous pressure |
| JPH06257011A (en) * | 1993-03-04 | 1994-09-13 | Unitika Ltd | Polyolefinic grid fiber |
| WO1994024347A1 (en) * | 1993-04-08 | 1994-10-27 | Unitika Ltd | Fiber with network structure, nonwoven fabric constituted thereof, and process for producing the fiber and the fabric |
| US5786284A (en) * | 1993-04-08 | 1998-07-28 | Unitika, Ltd. | Filament having plexifilamentary structure, nonwoven fabric comprising said filament and their production |
| JPH08113858A (en) * | 1994-10-12 | 1996-05-07 | Unitika Ltd | Nonwoven fabric comprising antistatic network structure fiber and its production |
| JPH08113859A (en) * | 1994-10-12 | 1996-05-07 | Unitika Ltd | Nonwoven fabric comprising antistatic network structure fiber and its production |
| JPH08113890A (en) * | 1994-10-12 | 1996-05-07 | Unitika Ltd | Antistatic wet nonwoven fabric and its production |
| JPH08113819A (en) * | 1994-10-12 | 1996-05-07 | Unitika Ltd | Netlike structure-having antistatic fiber and its production |
| US5816700A (en) * | 1995-10-26 | 1998-10-06 | E. I. Du Pont De Nemours And Company | Process and apparatus for mechanically mixing polymers and lower viscosity fluids |
-
1997
- 1997-01-09 DE DE69702115T patent/DE69702115T2/en not_active Expired - Fee Related
- 1997-01-09 KR KR1019980705305A patent/KR19990077167A/en not_active Application Discontinuation
- 1997-01-09 WO PCT/US1997/000160 patent/WO1997025460A1/en not_active Application Discontinuation
- 1997-01-09 DE DE69704343T patent/DE69704343T2/en not_active Expired - Lifetime
- 1997-01-09 WO PCT/US1997/000157 patent/WO1997025459A1/en not_active Application Discontinuation
- 1997-01-09 ES ES97905560T patent/ES2146982T3/en not_active Expired - Lifetime
- 1997-01-09 EP EP97905560A patent/EP0876520B1/en not_active Expired - Lifetime
- 1997-01-09 DE DE69701673T patent/DE69701673T2/en not_active Expired - Fee Related
- 1997-01-09 JP JP52532897A patent/JP3839489B2/en not_active Expired - Fee Related
- 1997-01-09 US US09/101,088 patent/US6004672A/en not_active Expired - Lifetime
- 1997-01-09 KR KR1019980705306A patent/KR19990077168A/en not_active Application Discontinuation
- 1997-01-09 EP EP97902841A patent/EP0877835B1/en not_active Expired - Lifetime
- 1997-01-09 ES ES97901926T patent/ES2156355T3/en not_active Expired - Lifetime
- 1997-01-09 JP JP52532797A patent/JP3953107B2/en not_active Expired - Fee Related
- 1997-01-09 CA CA002242469A patent/CA2242469A1/en not_active Abandoned
- 1997-01-09 ES ES97902841T patent/ES2148928T3/en not_active Expired - Lifetime
- 1997-01-09 CA CA002242470A patent/CA2242470A1/en not_active Abandoned
- 1997-01-09 EP EP97901926A patent/EP0877834B1/en not_active Expired - Lifetime
- 1997-01-09 KR KR1019980705307A patent/KR19990077169A/en not_active Application Discontinuation
- 1997-01-09 CA CA002242468A patent/CA2242468A1/en not_active Abandoned
- 1997-01-09 JP JP9525329A patent/JP2000503078A/en not_active Ceased
- 1997-01-09 WO PCT/US1997/000161 patent/WO1997025461A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| DE69702115T2 (en) | 2001-02-01 |
| DE69704343D1 (en) | 2001-04-26 |
| US6004672A (en) | 1999-12-21 |
| EP0877834A1 (en) | 1998-11-18 |
| JP2000503078A (en) | 2000-03-14 |
| ES2156355T3 (en) | 2001-06-16 |
| EP0877835A1 (en) | 1998-11-18 |
| JP2000505154A (en) | 2000-04-25 |
| JP3953107B2 (en) | 2007-08-08 |
| WO1997025461A1 (en) | 1997-07-17 |
| DE69701673D1 (en) | 2000-05-18 |
| EP0876520B1 (en) | 2000-04-12 |
| DE69701673T2 (en) | 2000-11-30 |
| EP0877834B1 (en) | 2001-03-21 |
| EP0877835B1 (en) | 2000-05-24 |
| KR19990077167A (en) | 1999-10-25 |
| EP0876520A1 (en) | 1998-11-11 |
| WO1997025460A1 (en) | 1997-07-17 |
| ES2148928T3 (en) | 2000-10-16 |
| KR19990077168A (en) | 1999-10-25 |
| JP3839489B2 (en) | 2006-11-01 |
| CA2242469A1 (en) | 1997-07-17 |
| CA2242470A1 (en) | 1997-07-17 |
| WO1997025459A1 (en) | 1997-07-17 |
| JP2000503731A (en) | 2000-03-28 |
| DE69704343T2 (en) | 2001-10-31 |
| KR19990077169A (en) | 1999-10-25 |
| ES2146982T3 (en) | 2000-08-16 |
| DE69702115D1 (en) | 2000-06-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2242468A1 (en) | Fibers flash-spun from partially fluorinated polymers | |
| US5192468A (en) | Process for flash spinning fiber-forming polymers | |
| EP1049821B1 (en) | Flash spinning process and flash spinning solution | |
| US6458304B1 (en) | Flash spinning process and solutions of polyester | |
| US6096421A (en) | Plexifilamentary strand of blended polymers | |
| JP2756489B2 (en) | Flash spinning | |
| EP1141452B1 (en) | Flash spinning process and flash spinning solution with azeotropes | |
| US6136911A (en) | Fibers flash-spun from partially fluorinated polymers | |
| EP0951591B1 (en) | Fibers flash-spun from fully halogenated polymers | |
| US6352773B2 (en) | Flash spinning polymethylpentene process and product | |
| EP0482882A1 (en) | A process for flash spinning fiber-forming polymers | |
| AU643329B2 (en) | A process for flash spinning fiber-forming polymers | |
| KR20000069977A (en) | Fibers Flash-Spun from Fully Halogenated Polymers |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |