WO1999062993A1 - Matiere poreuse a base de polytetrafluorethylene de type poudre fine - Google Patents

Matiere poreuse a base de polytetrafluorethylene de type poudre fine Download PDF

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Publication number
WO1999062993A1
WO1999062993A1 PCT/GB1999/001750 GB9901750W WO9962993A1 WO 1999062993 A1 WO1999062993 A1 WO 1999062993A1 GB 9901750 W GB9901750 W GB 9901750W WO 9962993 A1 WO9962993 A1 WO 9962993A1
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Prior art keywords
ptfe
particles
fine powder
material according
porous
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PCT/GB1999/001750
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English (en)
Inventor
Norman Ernest Clough
Original Assignee
W.L. Gore & Associates (Uk) Ltd.
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Application filed by W.L. Gore & Associates (Uk) Ltd. filed Critical W.L. Gore & Associates (Uk) Ltd.
Priority to AU41570/99A priority Critical patent/AU4157099A/en
Publication of WO1999062993A1 publication Critical patent/WO1999062993A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/1213—Laminated layers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/24—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by surface fusion and bonding of particles to form voids, e.g. sintering
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F5/00—Orthopaedic methods or devices for non-surgical treatment of bones or joints; Nursing devices; Anti-rape devices
    • A61F5/44—Devices worn by the patient for reception of urine, faeces, catamenial or other discharge; Portable urination aids; Colostomy devices
    • A61F5/441—Devices worn by the patient for reception of urine, faeces, catamenial or other discharge; Portable urination aids; Colostomy devices having venting or deodorant means, e.g. filters ; having antiseptic means, e.g. bacterial barriers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1692—Other shaped material, e.g. perforated or porous sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0004—Organic membrane manufacture by agglomeration of particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0004—Organic membrane manufacture by agglomeration of particles
    • B01D67/00041—Organic membrane manufacture by agglomeration of particles by sintering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/30—Polyalkenyl halides
    • B01D71/32—Polyalkenyl halides containing fluorine atoms
    • B01D71/36—Polytetrafluoroethene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
    • B29C67/20—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 for porous or cellular articles, e.g. of foam plastics, coarse-pored
    • B29C67/205—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 for porous or cellular articles, e.g. of foam plastics, coarse-pored comprising surface fusion, and bonding of particles to form voids, e.g. sintering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/04—Characteristic thickness
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
    • C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
    • C08J2327/12—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
    • C08J2327/18—Homopolymers or copolymers of tetrafluoroethylene

Definitions

  • the present invention relates to a porous PTFE material formed from particles of fine powder-type polytetrafluoroethylene (PTFE) , articles composed of the material and a process of production thereof.
  • PTFE polytetrafluoroethylene
  • Porous PTFE material has been produced previously by fusing PTFE particles at a temperature above the melt (or sinter) temperature of the PTFE.
  • Patent specification GB2242431 describes a sintered porous PTFE structure used as a filter to filter solids from liquids.
  • the porous PTFE material is formed by fusing together particles of granular-type PTFE to form an integral network having voids between the interconnected particles.
  • the porous materials may be formed entirely from granular-type PTFE particles which have been presintered or from granular-type PTFE particles which have not been pre-sintered, or from a mixture of both. It is found that materials formed predominantly from sintered granular-type PTFE particles have a large pore size and high porosity, but tend to be relatively weak materials.
  • porous materials made from predominantly unsintered granular-type PTFE tend to have higher strength but have lower pore size and lower porosity.
  • a porous PTFE material having a combination of good strength and high pore size tend to have higher strength but have lower pore size and lower porosity.
  • Patent specification EP369466 describes the production of a porous film by drying and optionally sintering an aqueous dispersion of fine powder PTFE particles having a particular shape and size. The thin PTFE film produced was heated briefly to sinter temperature, whereupon it shrank to a large degree.
  • Patent specification JP48056580 discloses the formation of a thin film from an aqueous dispersion of fine power PTFE tetrafluoroethylene hexafluoropropylene copolymer, followed by heat treatment to give a membrane of sub-micron pore size intended for diffusion concentration and separation of gases.
  • the present invention provides a porous material formed of particles comprising presintered fine powder-type polytetrafluoroethylene (PTFE) particles, the particles being fused together to form a porous network.
  • PTFE polytetrafluoroethylene
  • the invention also extends to sintered fine powder- type polytetrafluoroethylene particles as a novel material.
  • the PTFE under consideration have been heated under conditions of time and temperature such as to partially or fully sinter the PTFE and to thereby give an integrity to the particle which results in formation of a strong porous network.
  • PTFE is produced in two distinct types which are so-called “granular” PTFE and so-called “fine powder” PTFE. These materials have quite different properties.
  • fine powder type PTFE refers to that type of PTFE produced by the emulsion polymerisation technique. This technique produces a resin that cannot be RAM extruded but which must be extruded by the paste extrusion method where the resin is first mixed with a lubricant.
  • fine powder is a term of art in the PTFE field and refers to the type of PTFE. It has no relationship to particle size. "Granular-type” and fine powder-type” PTFE are produced by two distinct procedures.
  • the porous material may be composed entirely of presintered fine powder-type PTFE or may include a proportion of other types of PTFE, such as unsintered fine powder-type PTFE.
  • the unsintered material may be included in a wide range of proportions, for example from 0-70%, preferably 0-50%, more preferably 0-30% by weight based on the total weight of the porous material. The inclusion of a proportion of unsintered material tends to produce a porous material having a greater specific strength than when 100% presintered material is employed.
  • the porous material may also include a proportion of granular-type PTFE which may be sintered or unsintered (in proportions of 0-100% respectively) .
  • the granular material may be present in from 0-80% by weight, preferably 0-60%, and especially 0-30% by weight based on the total weight of the porous material.
  • one or more of sintered granular, unsintered granular and unsintered fine powder PTFE may be used to form the porous material in conjunction with the presintered fine powder-type PTFE.
  • Both the "granular type” and "fine powder-type” PTFE include both homopolymer tetrafluoroethylene and modified PTFE.
  • the homopolymer is modified by co- polymerisation with a co-polymerisable ethylenically unsaturated comonomer in a small amount typically of less than 2% by weight of copolymer.
  • These copolymers are called "modified” because they do not change the basic character of homopolymer PTFE, and the copolymer remains non-melt processable just as the homopolymer.
  • comonomers examples include alkenes such as ethylene and propylene; halogenated alkenes such as hexafluoropropylene (HFP) , vinylidene fluoride and chlorofluoroethylene; or perfluoroalkylvinyl ethers such as perfluoropropylvinyl ether (PPVE) .
  • alkenes such as ethylene and propylene
  • halogenated alkenes such as hexafluoropropylene (HFP) , vinylidene fluoride and chlorofluoroethylene
  • perfluoroalkylvinyl ethers such as perfluoropropylvinyl ether (PPVE) .
  • porous material particles of a thermoplastic tetrafluoroethylene copolymer in an amount of between 0 and 30% by weight of solids, preferably 3-20%, based on the total weight of the porous material .
  • thermoplastic fluorinated tetrafluoroethylene polymers include copolymers of tetrafluoroethylene and hexafluoropropylene (commonly called fluorinated ethylene-propylene copolymer or FEP) , and of tetrafluoroethylene and perfluoroalkyl vinyl ether (when the ether is perfluoropropyl vinyl ether the copolymer is commonly called PFA) . These fully fluorinated polymers are preferred.
  • the porous material generally has a density in the region 0.5 to 1.5 typically 0.75 to 1.40, and especially 0.85 to 1.30 g/cm 2 .
  • the pore size of the porous material is dependent to an extent on the particle size of the PTFE particles used to form the porous material.
  • the mean pore size is generally in the range 1- 50 microns, particularly 2-20 microns, especially 3-10 microns .
  • the porous material of the present invention shows particularly good strength.
  • the specific strength of the material (measured as described herein) varies from about 15 to 500N/cm 2 , particularly 50-300N/cm 2 , and especially 100-200N/cm 2 .
  • the porous material shows excellent dimensional stability and does not tend to shrink substantially at high temperatures (e.g. less than 5% after 2 hrs at 200°C) . It also does not shrink substantially (e.g. less than 5%, typically less than 2%) when wetted with liquids such as isopropanol .
  • Gurley number The air flow measured as the Gurley number is also inversely proportional to the mean pore size, lower Gurley numbers indicating a higher air flow through the material. Gurley numbers are generally in the range 0.4 to lOs/lOOcm 3 , especially l-5s/100cm 3 .
  • the porous material may include various fillers as known in the art for inclusion in PTFE products. Suitable fillers include carbon, activated carbon, glass particles, chromium oxide, titanium oxide, aluminium nitride, silica, and chopped expanded PTFE. The amount of filler can be up to 80% by weight of the porous material. The high strength of the porous material enables relatively large amounts of filler to be included.
  • the porous material is in the form of a sheet, a tube, a fibre etc.
  • the porous material may also be employed as a coating material on a substrate to form a composite article.
  • the porous material of the present invention may be applied as one or a multiple of layers onto expanded porous PTFE membrane. Similar composite materials having a coating layer formed of granular-type PTFE are disclosed in our patent application PCT/GB96/01340.
  • the porous material of the present invention shows excellent adhesion to the expanded PTFE membrane.
  • one or more layers of the porous material are applied onto one side of the expanded PTFE membrane.
  • one or more layers are applied to both sides of the expanded PTFE membrane.
  • the thickness of the coating of porous material is generally in the range 50-2000 microns, particularly 150- 1000 microns.
  • the expanded PTFE membrane can be made using a number of processes, including the formation of an expanded network of polymeric nodes and fibrils in accordance with the teachings of US patents 3,953,566, 3,962,153, 4,096,227 and 4,187,390.
  • expanded PTFE membrane is made by blending a dispersion of so-called fine powder PTFE with hydrocarbon mineral spirits.
  • the lubricated PTFE is compacted and RAM extruded to form a tape.
  • the tape can then be rolled down to a desired thickness and subsequently dried by passing over heated drying drums.
  • the dried tape can then be expanded both longitudinally and transversely at elevated temperatures.
  • the expanded PTFE membrane is formed into a fabric by twisting tapes of the membrane and weaving these into a fabric (such a material is available from W.L. Gore & Associates Inc., under the RASTEX trademark) .
  • This fabric may be laminated (e.g. by heat bonding) to an expanded PTFE membrane to give improved mechanical properties.
  • the porous material of the present invention may be applied (e.g. formed in situ) onto the fabric or the laminate, on one or both sides thereof.
  • Another aspect of the present invention provides a process for the production of a porous material, which comprises; presintering particles of fine powder-type polytetrafluoroethylene (PTFE) ; and
  • the particles During the presintering step, the particles generally become fused into a solid mass, which is then usually subjected to a milling step to produce presintered particles of the required particle size (see patent specification W096/40510) .
  • the unsintered fine powder-type PTFE resin is soft and not capable of being milled.
  • the particles On sintering, the particles become hard and the solid material produced becomes millable.
  • the degree of sintering can be determined by carrying out differential scanning calorimetry (DSC) on the PTFE material and is generally greater than 90% sintered.
  • DSC differential scanning calorimetry
  • the DSC peak of modified fine powder PTFE in the unsintered state is around 340°C and in the fully sintered state is around 325°C. Partially sintered materials exhibit both peaks. In this way, the degree of sintering can be monitored.
  • the particles of fine powder PTFE will be presintered at around 345-355°C from 1-10 hours, typically 2
  • the presintered material is then preferably milled to a desired particle size, which will determine the pore size of the porous material produced.
  • the presintered material is milled to a mean particle size in the range 20-300 microns, typically 50-200 microns.
  • Higher particle size materials tend to result in a relatively large mean pore size but a lower specific strength.
  • Higher specific strength porous materials are produced employing lower particle sizes and result in lower mean pore sizes.
  • the porous material is generally formed by applying a liquid dispersion comprising the presintered fine powder-type particles and baking at an elevated temperature such as to form the porous network.
  • the liquid dispersion can be applied by any suitable liquid coating technique, such as roller coating or by using a doctor blade. However, in a preferred embodiment, the liquid dispersion is applied onto the substrate by spraying.
  • the dispersion may contain suitable surfactants and thickening agents to enable it to wet the substrate and provide a continuous coating.
  • a particularly preferred thickening agent particularly for large size presintered particles which have a marked tendency to sediment, is a polyetherpolyol such as a RHEOLATE (trademark) obtainable from Rhoex Ine, Hightstown, NJ08520, USA.
  • a polyetherpolyol such as a RHEOLATE (trademark) obtainable from Rhoex Ine, Hightstown, NJ08520, USA.
  • the liquid coating is then dried and baked at elevated temperature, so as to fuse the presintered particles.
  • a preliminary step involves heating slowly at a relatively low temperature e.g. 50-100°C to dry off water and any other volatiles. Thereafter, the temperature is raised progressively up to 330-385°C (e.g. 340-370°C) in order to allow sintering and fusion of the PTFE particles to occur.
  • a particular benefit of the process of the present invention is that it is conducted at atmospheric pressure and elevated pressure conditions are avoided.
  • the porous material of the present invention finds many applications where a combination of high pore size leading to good flux of liquids or gases through the material, together with good strength is required.
  • Particular applications include gas and liquid filter materials, vents including sterilisable vents, oiling wicks and webs for plain paper copying machines and fabrics. It can also be used to produce an ostomy filter for colostomy or ileostomy bags.
  • CD509 which has previously been heat treated at 350°C for
  • FSN-100 surfactant solution 16g of a thickening agent - Rheolate 310 and 500g of distilled water are blended together in a Waring blender for 60 seconds to form a suspension.
  • CD509 is a fine powder PTFE resin copolymerised with a minor amount believed to be less than 2% by weight of hexafluoropropylene (HFP) . Milling was carried out using a Morehouse mill (available from Jamar Associates, Lake City, Florida 32055, USA) .
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • Rheolate 310 is a polyether polyol solution (32% by weight active) .
  • the resulting aqueous suspension was suitable for spray application. The suspension was sprayed onto a ceramic tile using a Binks BBR gun. The spray coated plate was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the tile.
  • the physical properties of this material are shown as follows:
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a ceramic tile using a Binks BBR gun.
  • the spray coated plate was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the tile.
  • the physical properties of this material are shown as follows:
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the CD509-based material has a significantly higher tensile strength than that of the FPD6304-based material but also has a larger mean pore size.
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alochol (by weight) .
  • Rheolate 300 is a polyether polyol solution (32% by weight active) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the physical properties of this material are as follows:
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • Rheolate 300 is a polyether polyol solution (32% by weight active) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the 100% CD509 material has a much greater air flow and a larger pore size distribution/mean than that of the XG204/CD509 blend whilst these materials have similar tensile properties.
  • comparing the 100% fine powder CD509 material with a similar density material composed of 100% granular resin DuPont unsintered PTFE resin grade 7A, previously milled to a mean particle size of 25 microns
  • a similar density material composed of 100% granular resin (DuPont unsintered PTFE resin grade 7A, previously milled to a mean particle size of 25 microns) surprisingly produces very different physical properties in terms of pore size, air flow and specific strength characteristics .
  • Triethanolamine This mixture is known as the "surfactant concentrate”.
  • Carboxymethyl cellulose is a thickening agent.
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene/polyoxypropylene block copolymer.
  • the FSN- 100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 115°C for 60 minutes. The temperature was then increased over several hours, up to 340°C and held at this temperature for 10 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the material may be used as an ostomy filter for colostomy or ileostomy bags (see our PCT/GB93/00232) .
  • the protocol for measuring deodorisation (H ; S removal) is described herein.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • An expanded PTFE membrane having a nodes and fibril morphology of nominal pore size 0.2 microns with an approximate thickness of 60 microns was held under tension in an aluminium frame (21.5inch 2 outside, l ⁇ inch 2 inside).
  • the frame contains a "tongue and groove" arrangement between the top and bottom plates to ensure that the membrane is held under tension throughout the process.
  • the frames are held together using toggle clamps.
  • the tensioned membrane contained within the internal dimensions of the frame is not in contact with any other surface.
  • the aqueous suspension was sprayed onto one side of the membrane using a Binks BBR spray gun.
  • the spray coated membrane held within the frame was dried in an oven at 50°C for 1 hour. The temperature was then increased to 350°C and held at this temperature for 30 minutes to complete the baking process. After cooling, the toggle clamps are released and the 2-layer porous composite material removed. The thickness of the composite was measured at 280 microns and therefore by subtraction, the layer of sintered porous PTFE sheet on the expanded membrane was 220 microns.
  • the air flow rate (Gurley) and pore size distribution of the composite was determined and compared to the expanded membrane alone after similar temperature processing. The results are as follows:
  • the sintered porous PTFE layer (100%CD509) of the composite has little effect on the air flow rate of the material.
  • the dimensional stability of the composite to thermal treatment (2 hours at 200°C) is much greater than that of the membrane as shown by the very low % shrinkage values.
  • the porous material is useful as gas or liquid filter and as a fabric.
  • EXAMPLE 8 (3-Layer Composite of Porous Material and Expanded PTFE Membrane . lkg of I.C.I, modified PTFE fine powder resin grade CD509 which has previously been heat treated at 350°C for 5 hours and then milled to an average particle size of 50 microns, 25g of Zonyl FSN-100 surfactant solution, 25g of Pluronic (trademark) L121, and 600g of distilled water are blended together in a Waring blender for 60 seconds to form a suspension. The resulting aqueous suspension was suitable for spray application.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • An expanded PTFE membrane having a nodes and fibril morphology of nominal pore size 0.2 microns with an approximate thickness of 60 microns was held under tension in an aluminium frame (21.5inch 2 outside, l ⁇ inch 2 inside).
  • the frame contains a "tongue and groove" arrangement between the top and bottom plates to ensure that the membrane is held under tension throughout the process.
  • the frames are held together using toggle clamps.
  • the tensioned membrane contained within the internal dimensions of the frame is not in contact with any other surface.
  • the aqueous suspension was sprayed onto both sides of the membrane using a Binks BBR spray gun.
  • the spray coated membrane held within the frame was dried in an oven at 50°C for 1 hour. The temperature was then increased to 350°C and held at this temperature for 30 minutes to complete the baking process. After cooling, the toggle clamps are released and the 3-layer porous composite material removed. The thickness of the composite was measured at 1040 microns and therefore by subtraction, the layer of sintered porous PTFE sheet on the expanded membrane was 980 microns.
  • the air flow rate (Gurley) and pore size distribution of the composite was determined and compared to the expanded membrane alone after similar temperature processing. The results are as follows:
  • the sintered porous PTFE layer (100%CD509) of the composite has little effect on the air flow rate of the material.
  • the dimensional stability of the composite to thermal treatment (2 hours at 200°C) is much greater than that of the membrane as shown by the very low % shrinkage values.
  • the material is useful as a sterilisable vent material for sterilisation apparatus.
  • Pluronic (trademark) L121 25g of a Zonyl (trademark) FSN-100 surfactant solution
  • 500g of distilled water are blended together in a Waring blender for 60 seconds to form a suspension.
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • I.C.I PTFE unmodified fine powder resin grade CD1 which has previously been heat treated at 350°C for 5 hours and then milled to an average particle size of 58 microns
  • 12.5g of Pluronic (trademark) L121, 12.5g of a Zonyl (trademark) FSN-100 surfactant solution and 650g of distilled water are blended together in a Waring blender for 60 seconds to form a suspension.
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 60 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the CD-based fine powder PTFE material has a similar tensile strength to that of the 9B/7A granular PTFE material, the air flow of the fine powder material is significantly greater with a much more open pore structure.
  • EXAMPLE 11 (100% Sintered Unmodified Fine Powder PTFE) lOOOg of I.C.I, unmodified fine powder PTFE resin grade CDl which has previously been heat treated at 350°C for 5 hours and then milled to an average particle size of 58 microns, 25g of Pluronic (trademark) L121, 25g of a Zonyl (trademark) FSN-100 surfactant solution and 1.3kgs of distilled water are blended together in a Waring blender for 60 seconds to form a suspension.
  • Pluronic (trademark) L121 surfactant is a polyoxyethylene, polyoxypropylene block copolymer.
  • the FSN-100 surfactant is a non-ionic perfluoroalkyl ethoxylate mixture.
  • the Zonyl FSN-100 surfactant solution consisted of a mixture of four parts FSN-100, three parts distilled water and three parts isopropyl alcohol (by weight) .
  • the resulting aqueous suspension was suitable for spray application.
  • the suspension was sprayed onto a flat steel sheet using a Binks BBR gun.
  • the spray coated sheet was dried in an oven at 50°C for 60 minutes. The temperature was then increased over several hours, up to 350°C and held at this temperature for 30 minutes to complete the baking process. After cooling, the resulting film can be removed from the steel sheet.
  • the physical properties of this material are shown as follows:
  • Gurley densometer ASTM D72658
  • W. & L. E. Gurley & Sons Results are reported in terms of Gurley number which is the time in seconds for 100cm 3 of air to pass through one square inch of the sample under a pressure of 4.88 inch of water head pressure. This measurement can be converted into metric permeability units (cm 3 cm/sec. cm- cm. Hg) by the following formula: thickness of sample xO .0432/Gurley number.
  • Thickness was measured using a dial guage according to ASTM D461.
  • the density of the PTFE is determined by weighing a sample thereof in two different media, viz; air and water at room temperature. Water is a non-wetting medium for PTFE and consequently, the resulting density measurements refer to the porous PTFE. The weights were determined using an Avery VA124 analytical balance. The porous PTFE density is calculated as shown below:
  • Particle size of PTFE was determined as follows: using a magnetic stirrer and ultrasonic agitation, 2.5 grams of PTFE powder were dispersed in 60ml isopropyl alcohol. (Ultrasonic Probe Model W-385, manufactured by Heat Systems-Ultrasonics, Inc.).
  • the pore size of the materials is determined by a COULTER POROMETER II (trademark) which uses a liquid displacement technique.
  • the sample is thoroughly wetted with a liquid of low surface tension and low vapour pressure e.g. COULTER POROFIL (trademark) such that all the pores have been filled with the liquid.
  • the wetted sample is subjected to increasing pressure, applied by a gas source. As the pressure is increased, the surface tension of the liquid is finally overcome and the liquid is forced out of the pores.
  • a "wet" run is obtained.
  • the sample is then tested “dry” without liquid in the pores and a “dry” run is obtained.
  • the maximum also called the bubble point
  • minimum and mean pore size can be calculated by the porometer using the Washburn equation.
  • the sample gas pressure will be regulated by the material of smallest pore diameter which will effectively act as a pressure restrictor. Consequently, for composites of expanded PTFE membrane and porous sintered PTFE, the pore size measurements will closely resemble that of the smallest pore diameter layer i.e. the expanded membrane.
  • Samples of the present invention were tested using a modified Suter test apparatus, which is a low water entry pressure challenge. Water was forced against the underside of a sample of 11.25cm diameter sealed by two circular rubber gaskets in a clamped arrangement. It is important that a leakproof seal is formed by the clamp mechanism, gaskets and sample.
  • the sample was overlaid by a reinforcing scrim (e.g. an open non-woven fabric) clamped over the sample.
  • the upper side of the sample was open to the atmosphere and visible to the operator.
  • the water pressure on the underside of the sample was increased by a pump connected to a water reservoir, as indicated by a pressure guage and regulated by an in-line valve. The upper side of the sample was visually observed for a period of one minute for the appearance of any water which might be forced through the sample.
  • the water entry pressure was the pressure at which water became forced through the membrane.
  • test gas comprised 80% nitrogen, 20% methane and 25ppm H 2 S, and the flow rate was 250ml/min.
  • the test apparatus comprised a sample holder, a test gas inlet, an H 2 S detector and read-out unit.
  • the gas is allowed to flow to the centre of the filter sample, which is clamped in position in the holder.
  • the gas flow through the sample may be axial or radial (for an increased path) .
  • the H 2 S detector attached to the other side of the sample monitors the efficiency of the filter in removing the hydrogen sulphide. Once this efficiency begins to fall below 100% the detector reading is noted against time. The results are expressed at the time the electrochemical detector takes to reach 2ppm.
  • Pre-cut discs (109mm diameter) of the materials were placed in an air-circulating oven at 50°C and the temperature increased to 200°C; and held at this temperature for 2 hours. After cooling to 50°C, the average diameter of the discs was noted and the % area shrinkage calculated.

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Abstract

L'invention se rapporte à une matière poreuse que l'on fabrique en fondant des particules de polytétrafluoréthylène (PTFE) de type poudre fine pré-frittée de manière à constituer un réseau poreux.
PCT/GB1999/001750 1998-06-04 1999-06-03 Matiere poreuse a base de polytetrafluorethylene de type poudre fine WO1999062993A1 (fr)

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AU41570/99A AU4157099A (en) 1998-06-04 1999-06-03 Fine powder-type porous ptfe material

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GB9811894.6 1998-06-04
GB9811894A GB2337991A (en) 1998-06-04 1998-06-04 Fine powder type PTFE material

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CN103180035A (zh) * 2010-09-10 2013-06-26 W.L.戈尔及同仁股份有限公司 熔融热塑性颗粒的多孔制品
EP3133681A1 (fr) 2015-08-19 2017-02-22 Commissariat à l'Energie Atomique et aux Energies Alternatives Pile à combustible à couche de gestion d'eau intégrée et son procédé de réalisation
CN113045788A (zh) * 2021-04-14 2021-06-29 深圳市富程威科技有限公司 一种微孔薄膜及其制备方法和应用
CN113088018A (zh) * 2021-04-14 2021-07-09 深圳市富程威科技有限公司 一种聚四氟乙烯透气膜及其制备方法和应用
CN113105659A (zh) * 2021-04-14 2021-07-13 深圳市富程威科技有限公司 一种聚四氟乙烯微孔薄膜及其制备方法和应用

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US7795346B2 (en) 2003-11-03 2010-09-14 Porex Corporation Sintered porous high melt-flow index materials and methods of making same
US7498392B2 (en) 2005-01-19 2009-03-03 Nelson Kevin G Methods and compositions for dielectric materials
US9040646B2 (en) 2007-10-04 2015-05-26 W. L. Gore & Associates, Inc. Expandable TFE copolymers, methods of making, and porous, expanded articles thereof
US8637144B2 (en) 2007-10-04 2014-01-28 W. L. Gore & Associates, Inc. Expandable TFE copolymers, method of making, and porous, expended articles thereof
US9650479B2 (en) 2007-10-04 2017-05-16 W. L. Gore & Associates, Inc. Dense articles formed from tetrafluoroethylene core shell copolymers and methods of making the same
US8628843B2 (en) 2008-10-24 2014-01-14 Porex Corporation Composite PTFE materials and applications thereof
EP2657290B1 (fr) * 2010-12-21 2017-10-04 Daikin Industries, Ltd. Produit mélangé de polytétrafluoroéthylène
US9644054B2 (en) 2014-12-19 2017-05-09 W. L. Gore & Associates, Inc. Dense articles formed from tetrafluoroethylene core shell copolymers and methods of making the same
CN109603570A (zh) * 2018-10-26 2019-04-12 德蓝水技术股份有限公司 聚四氟乙烯中空纤维微孔膜亲水改性的方法

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Publication number Priority date Publication date Assignee Title
CN103180035A (zh) * 2010-09-10 2013-06-26 W.L.戈尔及同仁股份有限公司 熔融热塑性颗粒的多孔制品
CN103180035B (zh) * 2010-09-10 2016-03-09 W.L.戈尔及同仁股份有限公司 熔融热塑性颗粒的多孔制品
EP3133681A1 (fr) 2015-08-19 2017-02-22 Commissariat à l'Energie Atomique et aux Energies Alternatives Pile à combustible à couche de gestion d'eau intégrée et son procédé de réalisation
US10193171B2 (en) 2015-08-19 2019-01-29 Commissariat à l'Energie Atomique et aux Energies Alternatives Fuel cell with integrated water management layer and fabrication method thereof
CN113045788A (zh) * 2021-04-14 2021-06-29 深圳市富程威科技有限公司 一种微孔薄膜及其制备方法和应用
CN113088018A (zh) * 2021-04-14 2021-07-09 深圳市富程威科技有限公司 一种聚四氟乙烯透气膜及其制备方法和应用
CN113105659A (zh) * 2021-04-14 2021-07-13 深圳市富程威科技有限公司 一种聚四氟乙烯微孔薄膜及其制备方法和应用
CN113045788B (zh) * 2021-04-14 2022-01-18 深圳市富程威科技有限公司 一种微孔薄膜及其制备方法和应用

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AU4157099A (en) 1999-12-20
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