Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—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
  • C08F214/18—Monomers containing fluorine
  • C08F214/26—Tetrafluoroethene
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions based on 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; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions based on 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; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions based on 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; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C09D127/18—Homopolymers or copolymers of tetrafluoroethene
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/005—Shaping by stretching, e.g. drawing through a die; Apparatus therefor characterised by the choice of materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
  • B32B15/085—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
  • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—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
  • C08F214/18—Monomers containing fluorine
  • C08F214/22—Vinylidene fluoride
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—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
  • C08F214/18—Monomers containing fluorine
  • C08F214/24—Trifluorochloroethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—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
  • C08F214/18—Monomers containing fluorine
  • C08F214/26—Tetrafluoroethene
  • C08F214/262—Tetrafluoroethene with fluorinated vinyl ethers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F259/00—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00
  • C08F259/08—Macromolecular compounds obtained by polymerising monomers on to polymers of halogen containing monomers as defined in group C08F14/00 on to polymers containing fluorine
• • 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
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions 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; Compositions of derivatives of such polymers
  • C08L27/02—Compositions 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; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions 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; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C08L27/18—Homopolymers or copolymers or tetrafluoroethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
• • 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
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
  • B29C55/023—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets using multilayered plates or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
  • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
  • B29K2027/18—PTFE, i.e. polytetrafluoroethylene, e.g. ePTFE, i.e. expanded polytetrafluoroethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
  • B29K2995/0037—Other properties
  • B29K2995/0063—Density
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2009/00—Layered products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
• • 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
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2207/00—Properties characterising the ingredient of the composition
  • C08L2207/53—Core-shell polymer

Definitions

• the present invention relates generally to tetrafluoroethylene (TFE) core shell copolymers, and more specifically, to dense TFE copolymer films formed from TFE core shell copolymers. Dense articles including the dense TFE copolymer films and a process for making dense articles utilizing TFE core shell copolymers are also provided.
• TFE tetrafluoroethylene
• Barrier films are used in a wide variety of technologies, including medical and commercial devices.
• barrier films find use in short and long term implantable medical devices, seals, gaskets, blood contact surfaces, bags, containers, and fabric iiners. in addition to good barrier properties, barrier films should have good mechanical properties and be thermally stable.
• Monolithic, multi-component, and multilayered barrier films have been constructed as barrier materials, but have not provided a
• PTFE Polytetrafiuoroethylene
• barrier films are characterized by poor mechanical properties such as low tensile strength, poor cold flow resistance or creep resistance, poor cut-through and abrasion resistance, and a general poor mechanical integrity that precludes its consideration in many materials engineering applications.
• Low porosity PTFE articles have been made through the use of a skiving process in which solid PTFE films are split or shaved from a thicker preformed article. These PTFE articles are characterized by low strength, poor cofd flow resistance, and poor load bearing capabilities in both the length and width directions of the film. Processes such as ram extrusion of PTFE fine powder have also been used to produce low porosity PTFE articles; however, such films also possess relatively poor mechanical characteristics. Attempts have also been made to strengthen the low porosity PTFE films by stretching in the length dimension. However, strength gains are minimal and, by the nature of the process, are achieved in only a single dimension, thus greatly minimizing the utility of the film.
• An expanded poiytetrafluoroethyfene (ePTFE) film may be produced by a process taught in U.S. Patent No. 3,953,566, to Gore.
• the porous ePTFE formed by the process has a microstructure of nodes
• TFE-based barrier films Conventional processes for forming TFE-based barrier films involve expansion, compression, and subsequent thermal treatment with or without deformation. Additionally, high strength dense PTFE barrier films may be produced without the use of the expansion and compression processes by the deformation of dried PTFE paste at a temperature above the crystalline melt of PTFE. Although such processes may result in a high strength dense fluoropo!ymer film, crystallinity is greatly reduced, permeability is not optimized, and the process is limited in scale.
• TFE-based barrier film that demonstrates improved barrier performance, such as evidenced by a resistance to methane permeation, improved physical and mechanical performance, such as low creep, and high matrix tensile strength, as well as a simplified process for making the TFE-based barrier fiim.
• One embodiment of the invention relates to a dense article that includes a dense TFE copolymer fiim that possesses a first endotherm between about 5Q°C and about 300°C, a second endotherm between about 320°C and about 35Q 0 C, and a third endotherm between about 350°C and about 400°C.
• the TFE copolymer film includes at least 50% TFE monomer and contains at least 3.0% by weight polymerized units of at least one comonomer based on a total weight of the dense TFE copolymer film.
• the dense TFE copolymer film has a methane permeability less than about 20 pg*micron/cm 2 /min.
• the dense articles have a void volume of less than about 20%,
• the dense articles exhibit improved physical and mechanical properties, including both adhesion and barrier properties.
• the dense TFE copolymer film may be produced directiy from a dried preform without increasing the porosity of the dried preform, as would conventionally be done in expansion processes.
• a second embodiment of the invention relates to a process of forming a dense article that includes stretching a dried preform of a TFE copolymer tape at a temperature no greater than about 335X to form a dense TFE copolymer film.
• the dense TFE copolymer fiim has a first endotherm from about 50°C to about 300°C, a second endotherm between about 320X and about 350°C, and a third endotherm between about 350°C and about 400 e C.
• Stretching the dried preform may be conducted at a temperature no less than the first endotherm. In another embodiment, stretching the dried preform occurs at a temperature between the first endotherm and the second endotherm.
• the dried preform may be stretched at a temperature within the second endotherm. !n a further embodiment, the dried preform may be stretched at a temperature from about 350°C to about 40.0°C.
• the process may further include forming the dried preform, which includes lubricating a TFE core shell copolymer, subjecting the iubricated TFE copolymer to pressure at a temperature below the second endotherm to form a lubricated TFE copoiymer tape, and drying the lubricated TFE copolymer tape to substantially remove the lubricant and form the dried preform.
• the dense TFE copolymer film has a methane permeability less than about 20
• the dense article has a void volume of less than about 20%
• FIG. 1 is a differential scanning calorimetry scan (DSC) depicting three endotherm peaks of a TFE-VDF dense article according to at least one embodiment of the invention
• FIG. 2 is a differentia! scanning calorimetry scan (DSC) depicting three endotherm peaks of a TFE-CTFE dense article in accordance with another embodiment of the invention
• FIG. 3 is a differential scanning calorimetry scan (DSC) depicting three endotherm peaks of a TFE-VDF dense article according to at least one embodiment of the invention.
• FIG. 4 is a differential scanning calorimetry scan (DSC) depicting three endotherm peaks of a TFE-CTFE dense article in accordance with at least one embodiment of the invention.
• comonomer as used herein is meant to denote any comonomer present within the core shell tetrafiuoroethyfene copolymer other than the tetrafluoroethylene monomer.
• the phrase "substantially only TFE monomer” is meant to denote that the shell portion in the core shell TFE copolymer contains (1) TFE monomer or (2) TFE monomer and an unquantifiable amount (trace amount) of comonomer.
• copolymer Is meant to describe a reaction product of TFE monomer and at least one comonomer where the comonomer is present in the copolymer in an amount of at least 3.0% by weight polymerized units based on the total weight of the TFE copolymer.
• the term "dense” is meant to describe an article that has a void volume less than about 20%.
• width and length are analogous to the x-direction and y-direction, respectively.
• lubricant is meant to describe a processing aid that includes, and in some embodiments, consists of, an incompressible fluid that is not a solvent for the polymer at processing conditions.
• the fluid-polymer surface interactions are such that it is possible to create an homogenous mixture.
• TFE copolymer TFE core shell copolymer
• core shell TFE copolymer core shell TFE copolymer
• the present invention relates to dense tetrafluoroethylene (TFE) copolymer films and dense articles formed from TFE core shell copolymers.
• the dense TFE copolymer films may be advantageously produced directly from a dried preform without increasing the porosity of the dried preform, as would conventionally be done in expansion processes.
• this disclosure relates to methods for producing dense articles that exhibit improved physical and mechanical properties, including both adhesion and barrier properties.
• Dense articles including the dense TFE copolymer films have a void volume of less than about 20%.
• the TFE copolymer film has a methane permeability less than about 20 pg*micron/cm 2 /min.
• a tetraf!uoroethylene (TFE) copolymer having a core shell configuration is formed by a process in which tetrafluoroethylene monomers are copolymerized with at least one comonomer other than TFE.
• the term "comonomer” is meant to describe a monomer within the TFE copolymer other than tetrafluoroethylene.
• the comonomer may be an ethylenically unsaturated monomer having a reactivity with TFE so as to enable polymerization with the TFE monomer.
• the comonomer may be a perfiuoroalky!
• ethylene monomer such as perfluorobutylefhylene (PFBE), perfluorohexylethyiene (PFHE), and perfluoro-octylethyiene (PFOE), or it may be a perfiuoroalky! vinyl ether monomer such perfluoro(methyi vinyl ether) (P!vlVE), perfluoro(ethyl vinyl ether) (PEVE), and perf!uoro(propyl vinyl ether) (PPVE).
• PFBE perfluorobutylefhylene
• PFHE perfluorohexylethyiene
• PFOE perfluoro-octylethyiene
• PPVE perfiuoroalky! vinyl ether monomer
• the comonomer may alternatively, or also, be an olefin such as ethylene, propylene or isobutylene, a fluorinated monomer such as
• CTFE chlorotrifiuoroethylene
• HFP hexafluoropropylene
• VDF vinylidene fiuoride vinylidene difluoride
• HFIB hexafluoroisobutyiene
• Ri and R2 F or a 1-3 carbon alkyi group containing at teast fluorine, and X, Y may be F and/or H;
• Ri is a perfluoroalkyi carbon of 1-5 atoms
• R1 /R2 may be F and/or
• Ri, R2 may be F and/or a perfluoroalkyi carbon of 1-5 atoms.
• the core shell TFE copoiymer is produced by a polymerization process that includes placing TFE monomer and at least one comonomer in a pressurized reactor, initiating the polymerization reaction with a free radical initiator, feeding TFE monomer and comonomer into the reaction vessel during the polymerization reaction, stopping the addition of comonomer at a point in the polymerization reaction prior to completion of the polymerization reaction, and continuing the polymerization reaction by feeding only TFE monomer into the reaction vessel until the reaction is complete, it is to be appreciated that more than one comonomer may be fed into a pressurized reactor to produce multi- component copolymers, such as. for example, terpo!ymers,
• TFE monomer and comonomer may be introduced into the reactor vessel as a precharge.
• the comonomer and TFE monomer may be sequentially added, for example, with the comonomer being added prior to the TFE monomer.
• the TFE monomer and comonomer may be simultaneously added to the reaction vessel.
• the TFE monomer and comonomer may be introduced incrementally or intermittently to the reaction vessel during the polymerization reaction. Higher concentrations of
• comonomer in the TFE copolymer produced are achieved by adding the comonomer to the reaction vessel at higher concentration levels.
• Comonomer may be added to the reaction vessel in an amount of at least about 1.0% by weight, at least about 2.0% by weight, at least about 3.0% by weight, at least about 3.5% by weight, at least about 4.0% by weight, at least about 4.5% by weight, or at least about 5.0% by weight. It is to be noted that the % by weight described herein with reference to the addition of the TFE monomer and/or comonomer to the reaction vessel are based upon total weight of TFE monomer and comonomer fed into the reactor vessel.
• addition of the comonomer to the reaction vessel is stopped.
• the comonomer addition is stopped at about the mid-point of the polymerization reaction, e.g., at a point from about 30% to about 60% to completion.
• the polymerization reaction is then permitted to continue by adding only TFE monomer until the reaction is complete. Excess comonomer may be removed (e.g. , evacuated) from the reactor, as needed, prior to completion of the reaction.
• substantially non-telogenic dispersing agents may be used.
• Ammonium perfluoro octanoic acid is one non-limiting example of a suitable dispersing agent for the polymerization reaction.
• Programmed addition may be utilized to add the dispersing agent to the reaction vessel.
• ingredient purity is needed to achieve the desired properties in the dense articles described herein.
• Ionic impurities which can increase ionic strength, in addition to soluble organic impurities, which can cause chain transfer or termination, are minimized or even eliminated.
• ultra-pure water is employed.
• the TFE core shell copolymer produced by the process described herein contains a core portion that includes copolymer units and a shell portion that contains substantially only TFE monomer.
• substantially only TFE monomer as used herein is meant to denote that the shell contains (1) TFE monomer only or (2) TFE monomer and a trace amount (e.g. , an unquantifiable amount) of comonomer.
• the TFE core shell copolymer may contain comonomer in an amount of at Ieast about i .0% by weight, at least about 2.0% by weight, at least about 3.0% by weight, at Ieast about 3.5% by weight, at Ieast about 4.0% by weight, at ieast about 4.5% by weight, at Ieast about 5.0% by weight, at Ieast about 5.5% by weight, at Ieast about 6% by weight, at least about 7% by weight, at least about 8% by weight, at Ieast about 9% by weight, or at least about 10% by weight.
• the amount of tetrafluoroethylene (e.g., TFE monomer) that may be present in the TFE copolymer may be less than about 99% by weight, less than about 98% by weight, less than about 97% by weight, less than about 98.5% by weight, less than about 96% by weight, less than about 95,5% by weight, or less than about 95% by weight.
• Percent by weight as it pertains to the TFE core shell copolymer is based upon the total weight of the TFE copolymer, In some embodiments, the TFE copolymer includes at Ieast 30% by weight TFE monomer, at least 40% by weight, at least 50% by weight, at Ieast about 60% by weight, at Ieast about 70% by weight, at Ieast about 80% by weight, or at Ieast 90% by weight. [0033] The TFE copolymers are produced in the form of fine particles dispersed within an aqueous medium.
• the TFE copolymer may be blended or combined, either by coagulation or by dry blending, with at least 5% by weight, at least about 5.5% by weight, at least about 6% by weight, at least about 6.5% by weight, at least about 7% by weight, at least about 7.5% by weight, at least about 8% by weight, at least about 8.5% by weight, at least about 9% by weight, at least about 9.5% by weight, or at least about 10% by weight of a TFE homopo!ymer, a thermoplastic polymer, a TFE copolymer, and combinations thereof.
• % by weight as used with respect to blending an additional polymer is based on the total weight of the polymer blend.
• suitable thermoplastic polymers include, but are not limited to, f!uorinated ethylene propylene (FEP),
• PVDF polyviny!idene fluoride
• PAVE perf!uoro(alkyl vinyl) ethers
• FFKM perfluoroeiastomeric materials
• TSV vinylidene fluoride
• PFA perfluoroalkoxy alkane
• ETFE ethylene and tetrafluoroethylene
• PCTFE polychiorotrifluoroethene
• the TFE core shell copolymers are produced In the form of fine particles dispersed within an aqueous medium and may be processed into a dense TFE copolymer film without any heat treatment above the crystalline melt temperature of poiytetrafiuoroethylene (PTFE).
• the dense TFE copolymer film is produced directly from dried extrudate at a deformation temperature less than or equal to about 400°C and greater than or equal to about 300°C without increasing the porosity of the dried preform, as would conventionally be done in expansion processes.
• the TFE copoiymer may be subjected to a ram extrusion process where the TFE copolymer is combined with a suitable lubricant (e.g., Isopar ® K), blended, compressed into a pellet, and extruded through a die to form a tape.
• a suitable lubricant e.g., Isopar ® K
• the direction of extrusion is referred to as the y- direction or longitudinal direction.
• the TFE copolymer tape is then dried to remove or substantially remove the lubricant and form a dried extrudate or dried preform.
• lubricant is meant to describe a processing aid that includes, and in some embodiments, consists of, an incompressible fluid that is not a sumble for the polymer at processing conditions. Additionally, the fluid-polymer surface interactions are such that it is possible to create an homogenous mixture.
• substantially all the lubricant is meant to denote that the lubricant is nearly or completely removed from the TFE copolymer tape to form the dried preform.
• the dried preform may then be deformed or stretched in at least one direction at a temperature less than or equal to about 400°C (e.g., from about 300°C to about 400°C) to form a dense TFE copolymer film.
• a temperature less than or equal to about 400°C e.g., from about 300°C to about 400°C
• the term "dense” is meant to describe a TFE copolymer film or article that possesses a void volume less than about 20%.
• the dense TFE copolymer film may possess a void volume less than about 20%, less than about 15%, less than about 10%, less than about 8%, less than about 5%, less than about 3%, or less than about 1 %.
• the dried preform is simultaneously deformed in the longitudinal and transverse directions (e.g. , both the x- and y- directions) to form a dense TFE copolymer film.
• the deformation in the longitudinal (y-direction) may occur at a stretch rate of about 10%/sec or lower, about 1 ,000%/sec or higher, or between about 10%/second and about
• the deformation in the transverse (x-direction) may occur at a stretch rate of about 10%/sec or lower, about 1 ,000%/sec or higher, or between about 10%/second to about 1 ,000%/sec.
• the deformation of the dried preform may be conducted in either the x-or y- direction or both the x-, y-directions, either sequentially or simultaneously, utilizing a pantograph machine or continuously in a tenter frame or similar machine.
• Suitable stretch ratios may vary significantly, such as from 1 : 1 to 1 : 1 ,000 or from 1 :1 to 1 ; 10,000 or greater and at varying stretch rates.
• the dense TFE copolymer films possess at least three separate endotherms.
• a first endotherm occurs below about 300°C. In at least one embodiment, a first endotherm occurs between about 50°C and about 300°C.
• a second endotherm occurs between about 32Q°C and about 35CTC
• a third endotherm occurs at a temperature between about 350 " C to about 400 t, C. In exemplary embodiments, the third endotherm occurs at about 380°C.
• blends can be made with the TFE core shell copolymer by blending with another TFE homopoiymer, a thermoplastic polymer, and/or another TFE copolymer, such as described herein, which may create an additional endotherm.
• the dense TFE copolymer films are thin and may have a thickness less than about 250 microns, less than about 150 microns, less than about 100 microns, less than about 50 microns, less than about 30 microns, less than about 10 microns, less than about 5 microns, or less than about 1 micron,
• the dried preform may be stretched in at least one direction as discussed above at a temperature at or above the first endotherm ⁇ i.e. , 300°C) to form: a dense TFE copolymer film.
• the dried preform may be deformed in at least one direction as discussed above at a temperature between the first endotherm and the second endotherm ⁇ i.e. , from about 300°C to about 320°C).
• the dried preform may be stretched in at least one direction as discussed above at a temperature within the second endotherm ⁇ i.e. from about 320°C to about 350°C) form a dense TFE copolymer film.
• the dried preform may be stretched at a temperature from about 350 U C to about 400°C. In at least one other embodiment, the dried preform may be deformed in at least one direction at a temperature from about 300°C to about 335°C, In another embodiment, the dried preform may be deformed at a temperature less than or equal to about 400° C to form a dense TFE copolymer film. In further embodiments, the dried preform may be deformed at a temperature less than or equal to about 370°C, less than or equal to about 335°C, or less than or equal to about 320°C to form a dense TFE copolymer film. In exemplary embodiments, the deformation occurs at a temperature at or above 300°C.
• the dried preform may optionally be heated to the deformation temperature (e.g., pre-heated and/or post-heated) prior to and/or after stretching or deforming the dried preform into a dense TFE copolymer film.
• the dried preform is heated to a temperature at or above 300X prior to and/or after stretching the dried preform.
• the dried preform is heated to a temperature between the first endotherm and the second endotherm (i.e. , from about 300°C to about 320°C) prior to and/or after stretching.
• the dried preform is heated to a
• the dried preform may be heated to a temperature from about 350°C to about 400°C prior to and/or after stretching,
• the dense TFE copolymer films and dense articles may be utilized as barrier materials.
• the dense TFE copolymer films exhibit a methane permeability of less than about 20 pg*micron/cm 2 /min, less than about 15 pg*micron/em 2 /min, less than about 10 pg*mtcron/cm 2 /min ! less than about 5 pg*micron/cm 2 /min, less than about 1.0 pg * micron/cm 2 /min, or less than about 0.5 pg*micron/cm 2 /min.
• the dense TFE copolymer films have a matrix tensile strength in at least one direction that is greater than or equal to about 5,000 psi, greater than or equal to about 25,000 psi, greater than or equal to about 50,000 psi, greater than or equal to about 75,000 psi or greater than or equal to about 100,000 psi, or higher.
• the dense TFE copolymer films and dense articles that include the dense TFE copolymer films exhibit adhesion characteristics that cannot be achieved in conventional polytetrafluoroethy!ene (PTFE) homopolymers. That is, the dense TFE copolymer film and dense article can be adhered to itself or to other materials after subjecting it to lower temperature and/or shorter time and/or lower pressure than what is required for adhering a PTFE homopolymer to itself or to other substrates, such as, for example, adhesion promoting substrates, polymeric substrates, or metal substrates.
• adhesion characteristics enable barrier materials to be formed without the need to adhere other substrates, which per unit volume, possess less barrier and mechanical performance. As a result, barrier properties associated with the dense TFE copolymer films and dense articles are maximized,
• the dense TFE copolymer films and dense articles including the dense TFE copolymer films may be laminated, adhered, or otherwise bonded (e.g., thermally, mechanically, or chemically) to a substrate.
• suitable substrates include, but are not limited to, fluorinated ethylene propylene (FEP), peril uoroalkoxy alkane (PFA),
• PTFE polytetrafluoroethylene
• the substrate may also be a metallic sheet, an inorganic sheet, or pressure sensitive adhesive. Such laminated structures may facilitate or enhance further bonding to additional layers, such as textiles.
• the apparatus used to measure methane permeation comprised of a stainless steel test cell with a top half, a bottom half, an inlet for methane gas, and an inlet for zero air.
• zero air refers to compressed air passing through a catalyst bed to remove any hydrocarbons in the air so that the methane is the only hydrocarbon the FID detector measures.
• the bottom half of the test ceil was first purged with zero air. The testing film is
• a tight sea! Is formed by two o-rings.
• Methane gas and zero air were then introduced into the test sample by way of the inlets.
• the flow of the methane gas and zero air were controlled using a needle valve and a mass flow controller (Model No, Brooks 5850E), respectively.
• Methane gas came in from the bottom inlet and came out through the bottom exhaust outlet, which ensured that there is no back pressure on the test sample.
• the methane gas which permeated through the test sample was carried in zero air and fed in to the FID detector (Model 880GB, Baseitne- Mocon, inc.).
• the FID detector continuously measured the concentration of the methane gas, which permeated through the test sample.
• the detector was connected to a data acquisition system to acquire voltage signals which were then converted to methane concentration (Cmethane) values using a known three point calibration curve.
• test duration lasted at !east until the methane concentration reached a steady state.
• the test duration typically ranged from about 15 minutes to about 40 minutes.
• the average of the data (Cmethane) collected during the last two minutes of the test duration was reported.
• Cmethane is tnhee average methane concentration in ppm
• R is the flow rate of zero air in cnVVmin
• A is the area of the test sample in cm 2 .
• Methane permeation was measured in duplicate and the average value of methane flux based on two samples was reported.
• Void (%) of the sample was estimated by the difference between bulk density (pbulk) and skeletal density (pskeleton) of the sample.
• the test sample was die-cut into coupons shaped into a circle with a diameter of about 20.3 mm. Four coupons were cut from different locations of the test sample. The thickness was measured at four different locations of each coupon by using the Mitutoyo Litematic VL-50A contact gauge. The average value of thickness was calculated for each coupon. The thickness of the test sample was reported based on the average value for the four coupons. The weight of each coupon was measured using a microbaiance (Mettler Toledo Model AT20). The weight of the test sample was reported based on the average value for the four coupons.
• the bulk density (ptutk) was then computed by dividing the weight of the test sample by the product of test sample area and test sample thickness.
• the coefficient of variance (CV) for the bulk density measurement was typically less than 5% with a mean CV of about 3.6%.
• Skeletal density (pskeieion) or the true density of the test sample was measured using a standard helium pycnometer (Model AccuPyc 1340 with a sample cup of 1 cm 3 in volume). The test sample mass was kept above 0,2g, which was the minimum weight required to get within 99% of the skeletal density value.
• MTS (maximum load/cross-section area)*(in ⁇ rinsic density of
• the intrinsic density of PTFE is taken to be 2.2 g/cc.
• VDF and TFE were added after the first added 1 kg of TFE was consumed. VDF and TFE were then added sequentially such that for each 0.5 kg of consumed TFE was followed by 0.5 kg of VDF until 2 kg of TFE and 2 kg of VDF were consumed. The polymerization continued by only feeding TFE untii the end of the polymerization.
• the polymerization reaction stopped after 14 kg of TFE had been added to the reactor.
• the weight of the dispersion produced was 48.90 kg containing 33.21 % solids.
• the dispersion was coagulated with nitric acid and dried at 13QX.
• the raw dispersion particle size (RDPS) of the polymer particle was 0.321 microns.
• the VDF concentration in the copolymer was determined to be 27,9 mol% (19.9 wt %), as measured by nuclear magnetic resonance (NMR) spectroscopy.
• a dense article using the above described fine powder resin including the core shell copolymer of TFE and VDF was prepared as follows.
• the resin was mixed with Isopar K® (Exxon Mobil Corp., Fairfax, Va.) at a concentration of 0.201 g/g of resin and formed into a pellet approximately 10.2 cm in diameter at a pressure of about 2758 kPa.
• the pellet was heated to about 49°C and ram extruded into a tape having dimensions of about 0.064 cm in thickness and about 20,32 cm in width, through a die which affected a reduction ratio of about 63 to 1 , at an average extrusion pressure of about 72678 kPa.
• the reduction ratio is the ratio of the cross sectional area of the extruder barrel to the cross sectional area of the extruded tape.
• the tape was dried by heating at 130°C in order to remove the lubricant. The width of the dried tape was 19.05 cm.
• DSC differential scanning ca!orimetry
• the reactor was heated to 83°C and agitated at 60 rpm.
• the KMn0 4 solution was added at 4.6 ml/min for the next 1 Kg of TFE.
• the KMnO 4 solution was then added at 50 ml/min until 1 Kg more of TFE was consumed.
• the KMn0 4 solution was then added at 30 mL/min until 1 kg more of TFE was consumed.
• the KMn0 4 solution was then added at 40 mL/min until 1 kg more of TFE was consumed.
• the KMnCU solution was then added at 50 ml/min until 1 kg more of TFE was consumed.
• the KMn0 4 solution was then added at 25 ml/min until 1 kg more of TFE was consumed.
• the KMn0 4 solution was then added at 2 ml/min until 1 kg more of TFE was consumed.
• the total amount of KMN04 solution added was 5,725 kg.
• CTFE was pumped into the reactor via liquid feed using a syringe pump. CTFE and TFE were added after the first added 1 kg of TFE was consumed. CTFE and TFE were then added continuously such that for each 1 kg of consumed TFE there was Q.8L of CTFE consumed. This continued until a total of 3 kg of TFE was consumed and 1.6 L of CTFE was consumed. The polymerization continued by only feeding TFE until the end of the
• the polymerization reaction stopped after 14.1 kg of TFE had been added to the reactor.
• the weight of the dispersion produced was 51.78 kg containing 35.61% solids.
• the dispersion was coagulated with nitric acid and dried at 130°C.
• the raw dispersion particle size (RDPS) of the polymer particle was 0.266 microns.
• the CTFE concentration in the copolymer was determined to be 13 mol% (15 wt %), as measured by nuclear magnetic resonance (NMR) spectroscopy.
• a dense article using the above described core shell copolymer of TFE and CTFE was prepared as follows.
• the resin was mixed with Isopar K ® (Exxon Mobil Corp.. Fairfax, Va.) at a concentration of 0.252 g/g of resin and formed info a peliet approximately 10.2 cm in diameter at a pressure of about 2758 kPa.
• the peliet was heated to about 49°C and ram extruded into a tape having dimensions of about 0.051 cm in thickness and about 20.32 cm in width, through a die which affected a reduction ratio of about 79 to 1, at an average extrusion pressure of about 38804 kPa.
• the reduction ratio is the ratio of the cross sectional area of the extruder barrel to the cross sectional area of the extruded tape.
• the tape was dried by heating at 180°C in order to remove the lubricant. The width of the dried tape was 18.1 cm.
• the tape was heated at 300°C for 480 seconds and then stretched in the longitudinal direction and transverse directions simultaneously at a ratio of about 4 7:1 while maintaining a temperature of about 3GG°C.
• the average engineering strain rate was calculated to be about 700%/second.
• FIG. 2 depicts a differential scanning calorimetry (DSC) scan showing the melt transition temperature peaks (endotherms) of the dense article, clearly indicating the presence of three peaks, the first peak at 223,3°C, the second peak at 332.52X, and the third peak at 368.57°C.
• DSC differential scanning calorimetry
• a dense article using the fine powder resin of Example 1 was prepared as follows.
• the resin was mixed with Isopar K ® (Exxon Mobil Corp., Fairfax, Va.) at a concentration of 0.201 g/g of resin and formed into a pellet 10.2 cm in diameter at a pressure of 2758 kPa.
• the pellet was heated to 49°C and ram extruded into a tape having dimensions of 0.064 cm in thickness and about 20.32 cm in width, through a die which affected a reduction ratio of about 63 to 1, at an average extrusion pressure of about 72678 kPa.
• the reduction ratio is the ratio of the cross sectional area of the extruder barrel to the cross sectional area of the extruded tape.
• the tape was dried by heating at 130°C in order to remove the lubricant. The width of the dried tape was 19.05 cm.
• the tape was heated at 370°C for 480 seconds and then stretched in the longitudinal direction and transverse directions simultaneously at a ratio of 3.3:1 while maintaining a temperature of about 370°C.
• the average engineering strain rate was calculated to be about 700%/second,
• FIG. 3 depicts a differential scanning calorimetry (DSC) scan showing the melt transition temperature peaks (endotherms) of the dense article, clearly indicating the presence of three peaks, the first peak at
• a dense article using the fine powder resin of Example 2 was prepared as follows.
• the resin was mixed with isopar K® (Exxon Mobii Corp., Fairfax, Va.) at a concentration of 0.252 g/g of resin and formed into a pellet 10.2 cm in diameter at a pressure of 2758 kPa.
• the pellet was heated to 49°C and ram extruded into a tape having dimensions of 0.051 cm in thickness and about 20.32 cm in width, through a die which affected a reduction ratio of 79 to 1 , at an average extrusion pressure of 36804 kPa.
• the reduction ratio is the ratio of the cross sectional area of the extruder barrel to the cross sectional area of the e.
• the tape was dried by heating at 180°C in order to remove the lubricant.
• the width of the dried tape was 18.1 cm.
• the tape was then thermally conditioned at 370°C for 240 seconds while constrained in the x-y plane.
• the tape was heated at 370°C for 10 seconds and then stretched in the longitudinal direction and transverse directions simultaneously at a ratio of 4.6:1 while maintaining a temperature of about 370°C.
• the average engineering strain rate was calculated to be about 700%/second.
• FIG. 4 depicts a differential scanning calorimetry (DSC) scan showing the melt transition temperature peaks (endotherms) of the dense article, clearly indicating the presence of three peaks, the first peak at 224.81 °C, and the second peak at 334.83°C, and the third peak at 368.2°C.
• DSC differential scanning calorimetry

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