WO1998044876A1 - Composition thermoplastique contenant du bisulfure de molybdene et du polytetrafluorethylene (pfte) - Google Patents

Composition thermoplastique contenant du bisulfure de molybdene et du polytetrafluorethylene (pfte) Download PDF

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Publication number
WO1998044876A1
WO1998044876A1 PCT/US1997/005720 US9705720W WO9844876A1 WO 1998044876 A1 WO1998044876 A1 WO 1998044876A1 US 9705720 W US9705720 W US 9705720W WO 9844876 A1 WO9844876 A1 WO 9844876A1
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WO
WIPO (PCT)
Prior art keywords
elastomeric
thermoplastic
modifier
composition
polytetrafluoroethylene
Prior art date
Application number
PCT/US1997/005720
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English (en)
Inventor
William E. Peters
Original Assignee
Alphaflex Industries, L.L.C.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alphaflex Industries, L.L.C. filed Critical Alphaflex Industries, L.L.C.
Priority to AU26609/97A priority Critical patent/AU2660997A/en
Priority to PCT/US1997/005720 priority patent/WO1998044876A1/fr
Publication of WO1998044876A1 publication Critical patent/WO1998044876A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
    • A61L27/14—Macromolecular materials
    • A61L27/26—Mixtures of macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/12—Making granules characterised by structure or composition
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/30—Sulfur-, selenium- or tellurium-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • 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
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/32—Joints for the hip
    • 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
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/32—Joints for the hip
    • A61F2/36—Femoral heads ; Femoral endoprostheses
    • 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
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2/38—Joints for elbows or knees
    • 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
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/02—Prostheses implantable into the body
    • A61F2/30—Joints
    • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
    • A61F2002/30003—Material related properties of the prosthesis or of a coating on the prosthesis
    • A61F2002/3006—Properties of materials and coating materials
    • A61F2002/30065—Properties of materials and coating materials thermoplastic, i.e. softening or fusing when heated, and hardening and becoming rigid again when cooled
    • 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
    • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0071—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof thermoplastic
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/16—Fillers

Definitions

  • the present invention relates to modified non- elastomeric thermoplastic materials and particularly to non-elastomeric thermoplastic plastics modified by modifiers that include molybdenum disulfide, polytetrafluoroethylene, and an elastomeric binder, preferably an elastomeric block copolymer.
  • Non-elastomeric thermoplastic materials have been developed for use in a wide variety of applications.
  • Non-elastomeric thermoplastic materials include many high polymers, usually synthetic, that are substantially solid, with little or no cold flow and plasticity, and can be formed or molded under heat and pressure and, sometimes, machined to high dimensional accuracy.
  • Such non-elastomeric thermoplastic materials include those frequently referred to by the term "plastics" including, for example, polystyrene, polyurethane, polyethylene, polypropylene, acrylonitrile-butadiene-styrene, polyvinyl chloride, nylons, cellulosic resins, acrylic resins and the like.
  • polyethylene is a generally inexpensive and non-elastomeric material with generally acceptable mechanical properties at very low temperatures and reasonable heat resistance.
  • polyethylene has a low melting point and is not generally satisfactory for use in high temperature applications.
  • Polystyrene is a generally non- elastomeric thermoplastic material that is generally not resistant to outdoor weathering, but has good optical qualities and has chemical resistance to most household acids.
  • Other non-elastomeric thermoplastic materials generally have some advantageous properties, but also have disadvantageous properties, and many non-elastomeric thermoplastic materials have low resistance to impact, particularly at low temperatures .
  • modifiers have been added to non-elastomeric thermoplastic materials to modify or enhance the mechanical properties such as abrasion resistance, solvent resistance, useful life, strength, and the like.
  • Conventional modifiers typically include ethylene-propylene rubber (EPR) , ethylene- propylene diene monomer (EPDM) , nitrile-butadiene rubber (NBR) , natural rubber (NR) , ethylene-vinyl acetate copolymer (EVA) , thermoplastic polyolefin rubber (TPO) , as well as various other elastomers.
  • EPR ethylene-propylene rubber
  • EPDM ethylene- propylene diene monomer
  • NBR nitrile-butadiene rubber
  • NR natural rubber
  • EVA ethylene-vinyl acetate copolymer
  • TPO thermoplastic polyolefin rubber
  • such modifiers have achieved only limited success, particularly in improving flame retardancy, hot and cold flow, chemical inertness, impact resistance, and resistance to ozone (0 3 ) and ultraviolet light (UV) .
  • such conventional modifiers are typically blended with the thermoplastic in relatively high concentrations, that is, more than 10 percent by volume. These high concentrations of modifier increase the cost of the modified thermoplastic material and, therefore, a finished product.
  • manufacturers of the modified thermoplastic compounds are limited to less than 5 percent fillers and extenders, such as reground tires, which can reduce the cost of the finished product.
  • non- elastomeric thermoplastic materials of the type generally referred to with the term "plastics".
  • non- elastomeric thermoplastic materials or “non- elastomeric thermoplastics”
  • I mean high polymer plastics, usually synthetic, that are substantially solid, with minimal plasticity and cold flow at normal atmospheric temperatures, and can be formed or molded with heat and pressure and, in some high polymer plastics, machined to high dimensional accuracy, including such high polymer plastics as polystyrene, polyurethane, polypropylene, polyethylene, acrylonitrile-butadiene-styrene, polyvinyl chloride, nylons, cellulose resins, acrylic resins and the like.
  • Such improved non-elastomeric thermoplastics are modified with a modifier comprising an elastomer composition, polytetrafluoroethylene (PTFE) , and molybdenum disulfide (MoS 2 ) , and can provide greatly improved physical properties, such as impact resistance, flame retardancy, flow characteristics, chemical inertness, and improved weatherability (such as resistance to 0 3 and UV) , and can achieve such improvements at lower percentages of modifier, while permitting the non-elastomeric thermoplastic material to be loaded with increased percentages of fillers and extenders.
  • a modifier comprising an elastomer composition, polytetrafluoroethylene (PTFE) , and molybdenum disulfide (MoS 2 )
  • PTFE polytetrafluoroethylene
  • MoS 2 molybdenum disulfide
  • thermoplastic elastomeric composition comprising PTFE, MoS 2 and an elastomeric block copolymer.
  • Thermoplastic elastomeric block copolymers differ in molecular structure from typical plastic and commercial rubbers, which are generally ho opolymers or random copolymers. That is, thermoplastic elastomeric block copolymers generally comprise two incompatible polymers, a thermoplastic end block polymer, typically polystyrene, chemically joined with one of several elastomeric mid block polymers.
  • the block copolymers tend to provide an elastic lattice structure interconnected by domains formed by their thermoplastic end blocks. Since the lattice structure is the result of physical rather than chemical forces, it may be destroyed either by dissolving the copolymer in a solvent or by heating it beyond the glass transition temperature of its thermoplastic end blocks. Upon evaporation of the solvent or cooling below the glass transition temperature of its thermoplastic end blocks, a structure may be re-imparted to the block copolymer. Such block copolymers are thus recyclable.
  • Thermoplastic block copolymers can include styrene-butadiene-styrene copolymers (SBS) , styrene- isoprene-styrene copolymers (SIS) and styrene- ethylene/butylene-styrene copolymers (SEBS) .
  • SBS styrene-butadiene-styrene copolymers
  • SIS styrene- isoprene-styrene copolymers
  • SEBS styrene- ethylene/butylene-styrene copolymers
  • the polystyrene domains soften and permit flow and after cooling, then reform to lock the interconnecting elastomeric network in place.
  • the styrene domains can impart high tensile strength to the resulting structure and the elastomeric mid block polymers can impart elasticity, cold flow flexibility and fatigue resistance.
  • thermoplastic elastomeric compositions disclosed in the '270 patent are useful in modifying the properties of asphalt, as disclosed in U.S. Patent NO. 5,393,819.
  • the present invention provides improved non- elastomeric thermoplastics with substantially improved physical properties, particularly increased impact resistance and flame retardancy.
  • a modifier comprising fibrillated PTFE, MoS 2 and a non-vulcanized elastomeric material is blended with a non-elastomeric thermoplastic to improve physical properties of the non-elastomeric thermoplastic material.
  • the modifier portion of the non-elastomeric thermoplastic material comprises a fibrillatable PTFE, which has been preassociated with MoS 2 , combined with a thermoplastic elastomeric material, preferably an elastomeric block copolymer, in relative amounts, for example, from as low as about 1.5 parts per hundred rubber (pphr) to as high as about 10 pphr of thermoplastic elastomeric copolymer.
  • the modifier portion can further include an unpolymerized PTFE residue of the fibrillated PTFE.
  • such a modifier is blended with a non-elastomeric thermoplastic in the range of about 1.5 percent to about 10 percent modifier, with the balance of non- elastomeric thermoplastic and fillers.
  • the invention includes a method for making a modified non-elastomeric thermoplastic composition.
  • the method includes the steps of forming a modifier including MoS 2 and fibrillatable PTFE and a non- vulcanized elastomeric material, pelletizing the modifier, blending the pelletized modifier with pelletized non-elastomeric thermoplastic material, and pelletizing the blended modifier and non-elastomeric thermoplastic material to form a modified non- elastomeric thermoplastic composition.
  • the pelletized modified non-elastomeric thermoplastic composition can be loaded with fillers, such as reground tires by blending the modified non- elastomeric thermoplastic material and fillers and extruding them with an extrusion temperature elevated about 10° F. above the temperature recommended by the thermoplastic material manufacturer.
  • fillers such as reground tires
  • the forming step includes the steps of preassociating the MoS 2 and fibrillatable PTFE and combining the preassociated MoS 2 and fibrillatable PTFE with a quantity of thermoplastic elastomeric copolymer in a high shear mixer that provides sufficient shear to fibrillate the polytetrafluoroethylene.
  • the blending step includes the step of combining the pelletized modifier and the pelletized non-elastomeric thermoplastic in a high shear mixer that provides sufficient shear to thoroughly blend the modifier and non-elastomeric thermoplastic to form the modified non-elastomeric thermoplastic composition. After blending, the modified non-elastomeric thermoplastic composition is pelletized.
  • composition ingredients are expressed in percentages, it is to be understood that the expressed percentage is the percent by weight of the resulting composition, unless otherwise stated. Where compositions are expressed in parts, it is to be understood that they are expressed in parts per hundred rubber by weight.
  • the present invention provides improved non- elastomeric thermoplastic materials including non- elastomeric thermoplastics such as polystyrene, polyurethane prepolymer, polypropylene, aerylonitrile- butadiene-styrene, polyvinyl chloride, nylons, cellulosic resin and acrylic resin.
  • non- elastomeric thermoplastics such as polystyrene, polyurethane prepolymer, polypropylene, aerylonitrile- butadiene-styrene, polyvinyl chloride, nylons, cellulosic resin and acrylic resin.
  • the improved non- elastomeric thermoplastics can be used in diverse applications and products, such as electrical insulators, aircraft canopies, gears, plumbing fixtures, football helmets, battery cases, toys, telephones, fabric coating, bearing surfaces, squeeze bottles, packaging films, trash containers, auto parts and construction materials.
  • non-elastomeric thermoplastics are modified by the addition of a non-vulcanite elastomeric binder, i.e., a thermoplastic elastomeric copolymer, combined with fibrillatable PTFE, MoS 2 to greatly enhance mechanical properties of the non- elastomeric thermoplastic.
  • a non-vulcanite elastomeric binder i.e., a thermoplastic elastomeric copolymer
  • fibrillatable PTFE i.e., MoS 2
  • thermoplastic elastomeric copolymers used in the modifiers preferably comprise thermoplastic elastomeric block copolymers.
  • the elastomeric block copolymers generally comprise at least two incompatible polymers that react to form a two-phase copolymer including thermoplastic polymer end blocks and an elastomeric polymer mid block.
  • the thermoplastic polymer end blocks form, as one phase, discrete thermoplastic "domains" that are separate from interconnecting elastomeric "chains", as the second phase, formed by the elastomeric mid block polymers.
  • Thermoplastic elastomeric copolymers that may be used include the thermoplastic elastomers sold by the Shell Chemical Company of Houston, Texas, as their KRATON D-grades and KRATON G-grades, the thermoplastic elastomers sold by EniChem Elastomeri Sri of Milano, Italy, and EniChem Elastomers Ltd. of South Hampton, Great Britain as their EUROPRENE products, and synthetic thermoplastics sold by Firestone Synthetic Rubber and Latex Company of Akron, Ohio, under the brand name of Stereon.
  • thermoplastic non-vulcanite elastomers include linear styrene-butadiene-styrene copolymers, branch styrene- butadiene copolymers, linear styrene-isoprene-styrene copolymers, branch styrene isoprene copolymers, linear styrene-ethylene/butylene-styrene copolymers, and di- block styrene ethylene-propylene copolymers.
  • Compositions of the invention can also combine non-elastomeric thermoplastic materials, and fibrillatable PTFE and MoS 2 with conventional modifiers such as non-vulcanized ethylene-propylene rubber (EPR) , ethylene-propylene diene monomer (EPDM) , nitrile-butadiene rubber (NBR) , natural rubber (NR) , ethylene-vinyl acetate copolymer (EVA) , thermoplastic polyolefin rubber (TPO) , as well as various elastomers.
  • EPR non-vulcanized ethylene-propylene rubber
  • EPDM ethylene-propylene diene monomer
  • NBR nitrile-butadiene rubber
  • NR natural rubber
  • EVA ethylene-vinyl acetate copolymer
  • TPO thermoplastic polyolefin rubber
  • the elastomeric binder portion of the modifiers used in the invention can also include polyester, polyurethane and polyamide block copolymers, and polypropylene/ethylene-propylene copolymers, and some compatible monomers, polymers and terpolymers.
  • thermoplastic binders are combined with fibrillatable PTFE particles and MoS 2 particles, which are preferably preassociated.
  • the fibrillatable PTFE preferred for use in the invention is a coagulated dispersion polymer such as FLUON CD1 made by ICI Americas, DF11X made by Ausimont, or TEFLON K-10 made by E.I. duPont de Nemours.
  • FLUON CD1 is a preferred fibrillatable PTFE in the invention because it can be dispersed more readily in the elastomer and fibrillates with a greater length-to-diameter ratio than other fibrillatable PTFE.
  • fibrillatable PTFE preferably used in my invention should be exposed to lower temperatures in drying the particulate resin material to obtain fibrillatable PTFE particles capable of fibrillation to achieve very high length- to-diameter ratios.
  • fibrillatable PTFE is accompanied by an unpolymerized PTFE residue.
  • Preferred coagulated dispersions can be extruded through a small orifice (e.g., orifice with a cross section of about 1/4 inch or less) by a hydraulic ram with pressures of only about 12,000 psi, while non- preferred resins require markedly higher ram pressures of, for example, 15,000 psi.
  • a small orifice e.g., orifice with a cross section of about 1/4 inch or less
  • a hydraulic ram with pressures of only about 12,000 psi
  • non- preferred resins require markedly higher ram pressures of, for example, 15,000 psi.
  • the manner in which the coagulated dispersion polymers that comprise fibrillatable PTFE are processed during their manufacture affects the structure of the fibrillatable PTFE particles and the ease with which they may be fibrillated into fibers having a high ratio of fiber length to fiber diameter.
  • altering manufacturing processes to reduce dense or hard layers on the outside of the PTFE polymer particles permits the particles to be drawn into longer and thinner fibers.
  • coagulated dispersions that may increase the surface hardness of the coagulated dispersion PTFE particles are the processing steps used to avoid further agglomeration of the coagulated dispersion PTFE particles and to remove anti-agglomeration agents and water from, and dry, the coagulated dispersion particles.
  • Use of high temperatures, for example, to remove lubricants and water and dry the coagulated dispersion particles may tend to make the surface of coagulated dispersion particles harder or more dense and render them more difficult to fibrillate.
  • the preferred MoS 2 is technical grade powder such as that sold by Amax, Inc. as its technical grade.
  • Such powdered MoS 2 generally has, in technical grade, about 85 percent of its particles smaller than 44 microns and may be provided with small average particle sizes (e.g., less than ten microns), and is characterized by substantial purity with over 98 percent comprising MoS 2 and less than 2 percent comprising such materials as insoluble acids, minerals, carbon, water and oil.
  • Molybdenum disulfide withstands pressures exceeding 500,000 psi and is serviceable through temperatures of -375° F. to 750° F.
  • the MoS 2 particles are an important part of this invention. Fibrillatable PTFE alone tends to sheet rather than fibrillate when an attempt is made to mix it with thermoplastic elastomeric copolymer. It is believed that the MoS 2 permits more intimate engagement of the fibrillated PTFE and thermoplastic elastomeric copolymer structure through its reaction with the surfaces of the PTFE and thermoplastic elastomeric copolymer. In manufacturing the modifier used in this invention, the particles of fibrillatable PTFE and MoS 2 are preferably preassociated.
  • particulate fibrillatable PTFE and particulate MoS 2 are preferably placed together in a mixing apparatus, such as a rotating mixing barrel, and intermixed together.
  • a mixing apparatus such as a rotating mixing barrel
  • the particle size of the MoS 2 particles is generally many times smaller than the particle size of the fibrillatable PTFE.
  • Fibrillatable PTFE can have median particle sizes as large as 450 to 600 microns, although average particle sizes substantially smaller than 450 to 600 microns can be used.
  • the MoS 2 used in the invention is preferably technical grade and has a substantial majority of particles with sizes less than about 45 microns, with average particle sizes as small as about four microns and less.
  • the average particle size of the MoS 2 can be one-twentieth that of the fibrillatable PTFE and smaller.
  • the particulate matter is mixed together for a sufficient time that the MoS 2 particles are generally adherent to the fibrillated PTFE particles, and the mixture particles become uniformly grey-black in appearance.
  • 150 pounds of additive material was obtained with 15 minutes of agitation and mixing.
  • the adherence of the MoS 2 particles to the particulate PTFE is due to an electrostatic charge differential between the PTFE particles and the MoS 2 particles.
  • the electrostatic charge differential is developed by rolling the PTFE in a mixing barrel to impart to a negative charge to the PTFE.
  • the mixing barrel is made of polypropylene, or similar material, and includes wooden paddles for agitating the PTFE in the barrel.
  • MoS 2 is added to the PTFE and the mixture is rolled.
  • the natural diamagnetic positive charge of the MoS 2 combines with the negative charge imparted to the PTFE to provide the electrostatic charge differential.
  • the prior association of MoS 2 particles with fibrillatable PTFE particles greatly assists the fibrillation and uniform combination of the fibrillated PTFE with the thermoplastic elastomer copolymer in this invention.
  • the MoS 2 particles associated with the surface of the fibrillatable PTFE particles it is believed, enhance the combination of the fibrillated PTFE particles with the elastomeric polymer phase of the thermoplastic copolymer and deter an adherent association of the PTFE particles with themselves.
  • the coating of MoS 2 particles on the fibrillatable PTFE particles interacts with the surrounding thermoplastic elastomeric copolymer upon mixing and assists in the fibrillation of the PTFE.
  • One component of the modifier used in the invention comprises fibrillatable PTFE, preferably FLUON CD1 from ICI Americas, Inc., which is soft as a result of lower temperature drying of the PTFE particles during manufacture and capable of extrusion through a small orifice by a hydraulic ram at pressures of 12,500 psi plus or minus 500 psi, and a technical grade MoS 2 powder, such as that sold by Amax, Inc., and Cyprus Industrial Minerals Company, generally adherent to the fibrillatable PTFE particles.
  • the ratio of fibrillatable PTFE to MoS 2 in the additive is preferably from about 3 to 1 to about 6 to 1 by weight.
  • the preassociated PTFE and MoS 2 combine more easily with some thermoplastic elastomeric copolymers than with others, and it may be possible and advisable to produce the preassociated PTFE and MoS 2 components with ratios other than as set forth above.
  • thermoplastic elastomeric copolymer preferably in crumb-like or powder-like form and, preferably, the preassociated fibrillatable PTFE and the MoS 2 particles are combined in a high shear mixer such as, preferably, a twin screw extruder or any other mixing and/or extruding apparatus which may provide sufficient shear to fibrillate the fibrillatable PTFE particles, for example, a Banbury mixer.
  • a high shear mixer such as, preferably, a twin screw extruder or any other mixing and/or extruding apparatus which may provide sufficient shear to fibrillate the fibrillatable PTFE particles, for example, a Banbury mixer.
  • the thermoplastic elastomeric copolymer, PTFE and MoS 2 are mixed under high shear until the mixture becomes uniform in appearance.
  • the copolymer can be combined with the fibrillatable PTFE and MoS 2 particles separately.
  • fibrillatable PTFE particles and MoS 2 particles are then added to the apparatus as mixing is effected.
  • the amount of MoS 2 used in the invention to effect a more uniform and effective combination of the fibrillated PTFE and the thermoplastic elastomeric copolymer may be easily determined by adding the MoS 2 to the fibrillatable PTFE-copolymer mixture until the fibrillatable PTFE becomes uniformly fibrillated and mixed with the copolymer.
  • fibrillatable PTFE particles are converted to fibrils, that is, elongated, solid PTFE fiber-like elements, with shear.
  • fibrillatable PTFE is a coagulated dispersion, and may include as much as 10 percent (by weight) of non-solid "binder" which is not converted into fibrils. This binder is unpolymerized PTFE.
  • the unpolymerized PTFE acts like a chemically inert coating for the thermoplastic copolymer structure, and the fibrillated PTFE mechanically combines with the elastomeric mid block polymers, that is, the elastomeric polymer portion of the molecular structure formed by the lattice of thermoplastic elastomeric copolymer. It is also theorized that it is the unpolymerized PTFE binder that provides fluoridation of the modified non-elastomeric thermoplastic compositions of the invention to enhance their flame retardancy.
  • modifier used in the invention comprises 100 parts rubber of EniChem linear SBS copolymer SOL T6302 combined with two parts (per hundred rubber) of preassociated fibrillatable PTFE and molybdenum disulfide particles sold by Alphaflex Industries, Inc. under their tradename Alphaflex 101.
  • Alphaflex 101 includes a preassociation of FLUON CD1 fibrillatable PTFE particles having diameters in the range of about 100 to about 600 microns, and MoS 2 particles having an average particle size in the range of about one to about ten microns being largely adherent to the fibrillatable PTFE particles.
  • the modifier results from mixing the linear SBS T6302 copolymer and Alphaflex 101 additive together in a twin screw extruder until substantially all of the fibrillatable PTFE is fibrillated and uniformly mixed with the linear SBS T6302 copolymer and extruded as a modifier for use in the invention.
  • the modifier is pelletized during the extrusion process.
  • the pelletized modifier is mechanically blended with pelletized non- elastomeric thermoplastic, and the intermixed pellets are extruded to form a modified non-elastomeric thermoplastic composition of the invention.
  • the pelletized modifier and non-elastomeric thermoplastic are combined in a production extruder.
  • the modified non-elastomeric thermoplastic composition can be pelletized during the extrusion process.
  • the temperature increase improves the viscosities of the modifier and the non-elastomeric thermoplastic components and permits more thorough blending of those components by the extruder. Without the temperature increase, the modifier and thermoplastic may not blend together acceptably, but, rather, exit the extruder as an unmixed, lumpy agglomeration of the components. Of course, for any particular modified non-elastomeric thermoplastic, a greater or lesser temperature change may be required.
  • the present invention has a dramatic effect on the properties of non-elastomeric thermoplastics. Modified non-elastomeric thermoplastic compositions of the invention exhibit increased chemical inertness, better weatherability and ozone resistance, improved cold temperature toughness, greater impact resistance and increased flame retardancy.
  • the flame retardancy of a modified non-elastomeric thermoplastic composition of the invention improved from a UL V-2 rating to a UL V-0 rating.
  • high density polyethylene (HDPE) modified with a modifier comprising PTFE, MoS 2 and an elastomeric block copolymer is inert, with improved wear characteristics, permanent plastic deformation and no cold flow, which make it well suited for use in human joint replacement parts such as hips and knees.
  • the present invention adds a non-amorphous material to an amorphous material, thereby enhancing the flame retardancy and dimensional stability, as well as other physical properties of the non-amorphous material.
  • the effect of the present invention on flame retardancy of non-elastomeric thermoplastics can be especially important.
  • Recent tests have achieved a UL V-0 flame retardancy rating, whereas previous efforts had only achieved a UL V-2 rating.
  • the improved flame retardancy, and an improved resistance to melting and dripping can be especially important in the consumer electronics industry. For example, when a circuit board inside a TV or computer overheats or ignites, conventional thermoplastic components or cases can melt and drip, essentially feeding the flames.
  • Components or cases made from non-elastomeric thermoplastics modified according to the present invention demonstrate a dramatic resistance to melting and dripping, thereby providing an additional measure of protection.
  • Another improvement to non-elastomeric thermoplastics, resulting from the fibril network formed by the modifier, includes an increased ability to accommodate fillers and extenders, such as reground tires or recycled plastic.
  • fillers and extenders such as reground tires or recycled plastic.
  • injection molded specimens of unmodified linear low density polyethylene are only able to accommodate less than 5 percent fillers.
  • Linear low density polyethylene specimens modified according to the present invention were able to accommodate up to 40 percent reground tire. Samples containing 20 percent reground tires have been tested and showed increased impact resistance and increased rigidity as compared to unmodified compositions.
  • the increased ability to accommodate reground tires (or other fillers) directly affects the cost of the final product by reducing the cost of materials.
  • Modified injection moldable polypropylene compositions of the invention have also demonstrated significantly improved flame retardancy. It is believed that the unpolymerized portion of the PTFE, which is mostly fluorine, encapsulates and coats the plastic domains of the elastomeric block copolymer of the modifier prior to the melt flow of the plastic domain. It is also believed that the fluorine in the unpolymerized portion of the PTFE is also responsible for the improved chemical inertness imparted to the modified compositions of the invention.
  • Example 1 The invention is illustrated by the following examples : Example 1
  • a conventional modifier of SBS rubber was added to a sample of virgin polypropylene in a composition comprising 7 percent modifier and the balance polypropylene.
  • a similar composition was formed using the invention, where the fibrillated PTFE and MoS 2 were added to the same SBS rubber used in the conventional modifier.
  • the physical properties of both modified compositions were measured and compared to the physical properties of unmodified polypropylene. The comparison results, indicated below, show that both modifiers slightly reduce the flexural modulus and the flexural strength.
  • the modifier of the invention dramatically improved the notched IZOD impact test value over the improvement by the conventional modifier.
  • HIPS high impact polystyrene
  • 7 percent modifier including fibrillated PTFE, MoS 2 and 840A Stereon with 2.25 pphr PTFE, .75 pphr MoS 2 , and the balance HIPS.
  • the physical properties of the modified HIPS composition were measured and compared to manufacturer-specified values for the unmodified HIPS material.
  • the notched izod test value for the invention modifier was almost twice that for the natural HIPS.
  • composition of the invention comprising 5 percent modifier, including fibrillatable PTFE, MoS 2 and 840A Stereon with 2.25 pphr PTFE, .75 pphr MoS 2 , and the balance acrylic.
  • the measured physical properties of the resulting composition of the invention were compared with the properties of conventionally-modified acrylic.
  • Acrylic composition of the invention exhibited a four fold increase in impact strength over a conventionally modified sample.
  • a linear low density polyethylene was combined in a composition of the invention comprising 5 percent modifier, including 2.25 pphr fibrillatable PTFE, .75 pphr MoS 2 and the balance 840A Stereon, with the following test results. It should be noted that the unmodified test sample was unable to accommodate as a filler 5 percent reground tires, whereas the test sample with the modifier of the present invention included as a filler 20 percent reground tires. In separate tests, the modified composition of the invention allowed an accommodation of 40 percent reground tires as filler. This dramatic improvement in accommodation of reground tires can provide a substantial cost advantage as well as a positive environmental impact.
  • modified non-elastomeric thermoplastic compositions of the present invention exhibit enhanced physical properties. Moreover, the enhanced properties can be achieved while permitting increased loading of reground tires as filler into non-elastomeric thermoplastics. Thus, the invention provides an enhanced thermoplastic composition with a considerable cost saving advantage.
  • compositions of the invention frequently have higher melt flows, but compositions of the invention can be molded at higher temperatures to achieve comparable production rates. In many cases, satisfactory molding of compositions of the invention can be achieved by increasing the molding temperatures only 10 - 15° F. over the manufacturer's recommended molding temperature for the unmodified plastic.

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  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Dermatology (AREA)
  • Mechanical Engineering (AREA)
  • Engineering & Computer Science (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Transplantation (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
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Abstract

L'invention concerne une composition thermoplastique non élastomère modifiée comprenant un thermoplaste non élastomère modifié par disulfure de molybdène, polytétrafluoréthylène et un liant élastomère.
PCT/US1997/005720 1997-04-08 1997-04-08 Composition thermoplastique contenant du bisulfure de molybdene et du polytetrafluorethylene (pfte) WO1998044876A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU26609/97A AU2660997A (en) 1997-04-08 1997-04-08 Thermoplastic composition containing molybdenum disulfide and polytetrafluoroethylene (ptfe)
PCT/US1997/005720 WO1998044876A1 (fr) 1997-04-08 1997-04-08 Composition thermoplastique contenant du bisulfure de molybdene et du polytetrafluorethylene (pfte)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1997/005720 WO1998044876A1 (fr) 1997-04-08 1997-04-08 Composition thermoplastique contenant du bisulfure de molybdene et du polytetrafluorethylene (pfte)

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WO1998044876A1 true WO1998044876A1 (fr) 1998-10-15

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005066278A1 (fr) * 2003-12-30 2005-07-21 General Electric Company Composition polymere, leur procede fabrication et articles formes a partir de cette composition
US7557154B2 (en) * 2004-12-23 2009-07-07 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
US8034866B2 (en) 2003-12-30 2011-10-11 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
US8067493B2 (en) 2003-12-30 2011-11-29 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
CN110938236A (zh) * 2019-12-13 2020-03-31 中国民用航空飞行学院 Dopo功能化二硫化钼阻燃剂及其制备方法
US11339263B2 (en) 2015-03-16 2022-05-24 Shpp Global Technologies B.V. Fibrillated polymer compositions and methods of their manufacture

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Publication number Priority date Publication date Assignee Title
JPS505748B1 (fr) * 1969-10-27 1975-03-06
JPS5832655A (ja) * 1981-08-19 1983-02-25 Daicel Chem Ind Ltd プラスチツク組成物
JPS6076566A (ja) * 1983-09-30 1985-05-01 Toyoda Gosei Co Ltd 塗料組成物
US4735982A (en) * 1986-07-25 1988-04-05 The B. F. Goodrich Company Thermoplastic-rubber polymer alloys and method for producing the same
US4767818A (en) * 1987-03-23 1988-08-30 General Electric Company Low gloss, flame retardant polycarbonate compositions
JPH01110558A (ja) * 1987-10-23 1989-04-27 Nok Corp 摺動材用樹脂組成物
US5418270A (en) * 1994-04-12 1995-05-23 Alphaflex Industries, Inc. Modified thermoplastic elastomeric compositions

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS505748B1 (fr) * 1969-10-27 1975-03-06
JPS5832655A (ja) * 1981-08-19 1983-02-25 Daicel Chem Ind Ltd プラスチツク組成物
JPS6076566A (ja) * 1983-09-30 1985-05-01 Toyoda Gosei Co Ltd 塗料組成物
US4735982A (en) * 1986-07-25 1988-04-05 The B. F. Goodrich Company Thermoplastic-rubber polymer alloys and method for producing the same
US4767818A (en) * 1987-03-23 1988-08-30 General Electric Company Low gloss, flame retardant polycarbonate compositions
JPH01110558A (ja) * 1987-10-23 1989-04-27 Nok Corp 摺動材用樹脂組成物
US5418270A (en) * 1994-04-12 1995-05-23 Alphaflex Industries, Inc. Modified thermoplastic elastomeric compositions

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005066278A1 (fr) * 2003-12-30 2005-07-21 General Electric Company Composition polymere, leur procede fabrication et articles formes a partir de cette composition
US8034866B2 (en) 2003-12-30 2011-10-11 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
US8067493B2 (en) 2003-12-30 2011-11-29 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
US7557154B2 (en) * 2004-12-23 2009-07-07 Sabic Innovative Plastics Ip B.V. Polymer compositions, method of manufacture, and articles formed therefrom
US11339263B2 (en) 2015-03-16 2022-05-24 Shpp Global Technologies B.V. Fibrillated polymer compositions and methods of their manufacture
CN110938236A (zh) * 2019-12-13 2020-03-31 中国民用航空飞行学院 Dopo功能化二硫化钼阻燃剂及其制备方法

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Publication number Publication date
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