Derived From Ethylene Patents (Class 522/161)
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Patent number: 6818020Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed contained by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin in transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: GrantFiled: June 13, 2003Date of Patent: November 16, 2004Assignee: Howmedica Osteonics Corp.Inventors: Deh-Chuan Sun, Casper F. Stark
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Patent number: 6803014Abstract: The present invention relates to a method for making a heat-resistant elastic article and a heat-resistant elastic article. The invention especially relates to a method of making elastic fibers and polymeric elastic fibers wherein the elastic fibers are capable of withstanding dyeing and heat-setting processes that typically are conducted at elevated temperatures (such as 110-230° C. and especially at greater than or equal to 130° C. for minutes). The inventive method comprises radiation crosslinking an article (or plurality of articles) under an inert or oxygen limited atmosphere (for example, in N2, argon, helium, carbon dioxide, xenon and/or a vacuum) wherein the article (or articles) comprises at least one amine stabilizer and preferably another optional stabilizer additive. More preferably, the radiation crosslinking is performed at a low temperature (−50 to 40° C.).Type: GrantFiled: July 10, 2002Date of Patent: October 12, 2004Assignee: Dow Global Technologies Inc.Inventors: Thoi H. Ho, Selim Bensason, Rajen M. Patel, Kimberly S. Houchens, Rona L. Reid, Pak-Wing S. Chum, Leonie K. Walsh
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Patent number: 6800670Abstract: The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.Type: GrantFiled: February 26, 2001Date of Patent: October 5, 2004Assignees: Orthopaedic Hospital, University of Southern CaliforniaInventors: Fu-Wen Shen, Harry A. McKellop, Ronald Salovey
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Patent number: 6794423Abstract: The present invention relates to a tough, wear resistant Ultra High Molecular Weight Polyethylene (UHMWPE) prepared by the cross linking of a UHMWPE shaped article with irradiation doses higher than 4 Mrads, preferably higher than 5 Mrads, and most preferably less than 10 Mrads. The invention particularly provides total joint replacement devices and methods of making them for the hip, knee, elbow and shoulder.Type: GrantFiled: July 26, 2000Date of Patent: September 21, 2004Inventor: Stephen Li
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Patent number: 6774156Abstract: A process for producing a propylene copolymer having increased melt strength, the process comprising irradiating a copolymer of propylene and ethylene which has been polymerised using a Ziegler-Natta catalyst with an electron beam having an energy of at least 5 MeV and a radiation dose of at least 10 kGray and melting and mechanically processing the melt of the irradiated ethylene propylene copolymer to form long chain branches on the ethylene propylene copolymer molecules.Type: GrantFiled: September 2, 2003Date of Patent: August 10, 2004Assignee: ATOFINA Research S.A.Inventors: Guy Debras, Marc Dupire, Jacques Michel
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Patent number: 6774155Abstract: The invention is directed to methods for fabricating devices from polymer precursors, along with devices so fabricated. The methods of the invention include the steps of plasma treating a polymer based resin, paste, preform billet, or extrudate, and employing the treated polymer in the fabricated device. According to one embodiment, the fabricated device can include implantable prosthetics such as heart valves, sutures, vascular access devices, vascular grafts, shunts, catheters, single layered membranes, double layered membranes, and the like. Devices fabricated according to one embodiment of the invention include regions having selected porosity, permeability and/or chemistry characteristics.Type: GrantFiled: July 16, 2002Date of Patent: August 10, 2004Assignee: Atrium Medical CorporationInventors: Paul Martakos, Thomas M. Swanick, Theodore Karwoski
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Patent number: 6762215Abstract: Unsintered poly(tetrafluoroethylene) resin feeds are treated with ionizing radiation in an absorbed dose of no more than 1,000 Gy at room temperature in air so that only the melting temperature of the resin feeds is shifted toward the lower end without changing the quantities of heat of fusion and crystallization.Type: GrantFiled: February 25, 2002Date of Patent: July 13, 2004Assignee: Japan Atomic Energy ResearchInventors: Akira Udagawa, Akihiro Oshima
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Publication number: 20040132856Abstract: A medical prosthesis for use within the body which is formed of radiation treated ultra high molecular weight polyethylene having substantially no detectable free radicals, is described. Preferred prostheses exhibit reduced production of particles from the prosthesis during wear of the prosthesis, and are substantially oxidation resistant. Methods of manufacture of such devices and material used therein are also provided.Type: ApplicationFiled: October 30, 2003Publication date: July 8, 2004Inventors: Edward W. Merrill, William H. Harris, Murali Jasty, Charles R. Bragdon, Daniel O. O'Connor, Premnath Vonugopalan
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Patent number: 6726727Abstract: The present invention relates to the prevention and decrease of osteolysis produced by wear of the ultrahigh molecular weight polyethylene (UHMWPE). Methods are disclosed for the isolation of wear particles, preparation of implants exhibiting decreased wear in comparison to conventional UHMWPE and preparation of implants that cause decreased biological response in comparison to conventional UHMWPE. The implants created by these methods are also included in the present invention.Type: GrantFiled: October 16, 2002Date of Patent: April 27, 2004Assignee: Smith & Nephew, Inc.Inventors: Marcus L. Scott, Shilesh C. Jani
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Patent number: 6710098Abstract: The present invention relates to a method for reforming the surface of polymer, especially to a method for providing hydrophilicity or increasing hydrophobicity by reforming the surface of polymer or polymer membrane. The present invention is a method for reforming the surface of polymer membrane by irradiating it with energized ionic particles under the vacuum condition. The method including the steps of: a) manufacturing polymer membrane, including a surface activated, by inserting polymer membrane into a vacuum chamber, and by irradiating energized ionic particles on the surface of polymer membrane with an ion beam under a high vacuum; and b) manufacturing polymer membrane treated with a reactive gas on the surface of membrane, including the activated surface of step a), by infusing the reactive gas into a vacuum chamber after energized ionic particles of step a) have been irradiated.Type: GrantFiled: July 31, 2000Date of Patent: March 23, 2004Assignee: LG Chemical Ltd.Inventors: Sang-Young Lee, Byeong-In Ahn, Heon-Sik Song, Myung-Man Kim
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Patent number: 6699919Abstract: Polypropylene having improved long chain branching increased melt strength obtained by irradiating polypropylene with an electron beam having an energy of at least 5 MeV and with a radiation dose of from 5 to 100 kGray in the presence of a grafting agent, the branching index of the obtained polypropylene being lower than 0.7.Type: GrantFiled: January 4, 2002Date of Patent: March 2, 2004Assignee: Atofina ResearchInventor: Yves Charlier
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Patent number: 6693142Abstract: The objective of the present invention is to provide a production method by which a polymer of a functional group-terminated vinyl monomer can be easily and practically produced. Further, it is another object of the present invention to provide a functional group-terminated vinyl polymer which is useful as a material for the production of various functional products. The first aspect of the present invention is concerned with a production method of a functional group-terminated vinyl polymer comprising a step of synthesizing a halogen atom-terminated vinyl polymer by the radical polymerization reaction of a vinyl monomer in the presence of a halogen compound and a step of introducing a functional group to a terminus by substituting a functional group-containing group for the terminal halogen atom of said vinyl polymer.Type: GrantFiled: June 24, 2002Date of Patent: February 17, 2004Assignee: Sekisui Chemical Co., Ltd.Inventors: Takeshi Wakiya, Takamaro Kakehi
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Patent number: 6680144Abstract: A method for producing a battery separator is disclosed. The method comprises applying a coating of an ethylenically unsaturated monomer to the fibers of a non-woven sheet and polymerizing the monomer in situ on the fiber surfaces. The non-woven sheet is from 50 to 3000 microns thick, and is composed of polyolefin fibers having an average fiber diameter from 0.5 to 5 microns and a surface area from 0.2 to 30 square meters per gram.Type: GrantFiled: May 6, 2002Date of Patent: January 20, 2004Assignee: KVG Technologies, Inc.Inventor: Wai M. Choi
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Patent number: 6673867Abstract: A heat-resistant engineering-plastic composition that satisfies a soldering-heat resistance of 260° C. for 10 to 60 secs., that is less costly, that is free of problems in injection molding process, and that is excellent in heat-aging resistance. A heat-resistant molded product made with the heat-resistant engineering-plastic composition, such as a connector mounted on printed circuit board. The heat-resistant molded product is produced by (a) melt-kneading (a1) an engineering plastic either having or introduced an active site for reacting with a specific functional group and (a2) either an organic compound that has both the said specific functional group and a polymerizing functional group in the same molecule or polyolefin that has the said specific functional group described in (a1) to obtain a resin composition, (b) melt-molding the resin composition comprising of (a), and (c) irradiating the melt-molded resin composition with ionizing radiation.Type: GrantFiled: November 13, 2001Date of Patent: January 6, 2004Assignee: Sumitomo Electric Fine Polymer, Inc.Inventors: Hiroshi Hayami, Shinya Nishikawa
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Patent number: 6667351Abstract: The present invention relates to elastic articles comprising a crosslinked or crosslinkable ethylene polymer and a method for making the same. In particular, the invention relates to a shaped article (e.g. film or fiber) characterized by improved elasticity at elevated temperatures and comprising a substantially cured, irradiated, or crosslinked (or curable, irradiated or crosslinkable) homogeneously branched ethylene polymer. The improved elastic article of the present invention is particularly suitable for use in applications where good elasticity must be maintained at elevated temperatures such as, for example, personal hygiene items and disposable infection-control garments at body temperatures of about 100° F. (38° C.).Type: GrantFiled: February 28, 2002Date of Patent: December 23, 2003Assignee: Dow Global Technologies Inc.Inventors: Michael F. Langohr, Rajen M. Patel, Selim Bensason, Jill M. Martin, Thoi H. Ho, Nancy J. Schrock
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Patent number: 6664317Abstract: Certain essentially phenol antioxidant-free stabilizer systems that comprise either a binary hindered amine/hydroxylamine or nitrone or amine oxide or benzofuranone system or a ternary hindered amine/hydroxylamine or nitrone or amine oxide or benzofuranone/organic phosphite or phosphonite system are especially effective towards protecting polyolefins against the deleterious effects of gamma irradiation. Polyolefin articles such as medical packaging, hospital garments, draperies, woven and non-woven fiber products, surgery utensils, blow-molded I.V. bottles, hypodermic syringes, needle shields, laboratory ware such as trays, funnels, Petri dishes and filters, and hygiene related articles may be sterilized with gamma irradiation and are stabilized according to the present invention.Type: GrantFiled: February 14, 2001Date of Patent: December 16, 2003Assignee: Ciba Specialty Chemicals CorporationInventor: Roswell E. King, III
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Patent number: 6664308Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed contained by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin in transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: GrantFiled: January 8, 2002Date of Patent: December 16, 2003Assignee: Stryker Technologies CorporationInventors: Deh-Chuan Sun, Casper F. Stark
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Publication number: 20030212161Abstract: The present invention presents methods for making oxidation-resistant and wear-resistant polyethylenes and medical implants made therefrom. Preferably, the implants are components of prosthetic joints, e.g., a bearing component of an artificial hip or knee joint. The resulting oxidation-resistant and wear-resistant polyethylenes and implants are also disclosed.Type: ApplicationFiled: October 25, 2002Publication date: November 13, 2003Inventors: Harry A McKellop, Fu-Wen Shen
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Publication number: 20030207957Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed contained by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin in transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: ApplicationFiled: June 13, 2003Publication date: November 6, 2003Inventors: Deh-Chuan Sun, Casper F. Stark
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Patent number: 6641398Abstract: Dental material containing a polymerizable component and a component applied superficially to the polymerizable component, which can be removed after the curing of the polymerizable material with accompanying formation of a rough surface.Type: GrantFiled: August 20, 2001Date of Patent: November 4, 2003Assignee: Ivoclar Vivadent AGInventors: Konrad Hagenbuch, Gerhard Zanghellini
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Patent number: 6630518Abstract: The present invention relates to a sulfonated polymer membrane and to a process for the preparation thereof. According to the process, a polymer film is irradiated, and the irradiated polymer film is sulfonated in order to link sulfonic acid groups thereto. According to the invention, the sulfonation is continued until the total concentration of sulfonic acid groups in the membrane is 0.4-3.0 meq/g and they are homogeneously distributed in the membrane material in such a manner that their concentration in the middle of the membrane is at minimum 0.2 meq/g. With the help of the invention, it is possible by a rapid and simple process to prepare membranes the chemical and mechanical properties of which can be regulated by means of the selection of the initial film, by irradiation and by the sulfonation process.Type: GrantFiled: September 17, 2001Date of Patent: October 7, 2003Inventor: Mikael Paronen
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Patent number: 6627673Abstract: The present invention relates to shape deformable materials, which are capable of (1) being deformed, (2) storing an amount of shape deformation, and (3) recovering at least a portion of the shape deformation when exposed to a humid environment. The shape deformable materials can advantageously be in the form of films, fibers, filaments, strands, nonwovens, and pre-molded elements. The shape deformable materials of the present invention may be used to form products, which are both disposable and reusable. More specifically, the shape deformable materials of the present invention may be used to produce products such as disposable diapers, training pants, incontinence products, and feminine care products.Type: GrantFiled: July 24, 2001Date of Patent: September 30, 2003Assignee: Kimberly-Clark Worldwide, Inc.Inventors: Vasily A. Topolkaraev, Dave A. Soerens
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Patent number: 6573311Abstract: The invention is directed to methods for fabricating devices from polymer precursors, along with devices so fabricated. The methods of the invention include the steps of plasma treating a polymer based resin, paste, preform billet, or extrudate, and employing the treated polymer in the fabricated device. According to one embodiment, the fabricated device can include implantable prosthetics such as heart valves, sutures, vascular access devices, vascular grafts, shunts, catheters, single layered membranes, double layered membranes, and the like. Devices fabricated according to one embodiment of the invention include regions having selected porosity, permeability and/or chemistry characteristics.Type: GrantFiled: September 22, 1999Date of Patent: June 3, 2003Assignee: Atrium Medical CorporationInventors: Paul Martakos, Thomas M. Swanick, Theodore Karwoski
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Patent number: 6562540Abstract: A medical implant of ultrahigh molecular weight polyethylene having an improved balance of wear properties and oxidation resistance is prepared by irradiating a preform of ultrahigh molecular weight polyethylene, annealing the irradiated preform in the absence of oxygen to a temperature at or above the onset of melting temperature, and forming an implant from the stabilized cross-linked polymer. Implants prepared according to the process of the present invention have comparable oxidation resistance and superior wear performance compared to unirradiated ultrahigh molecular weight polyethylene.Type: GrantFiled: October 29, 2001Date of Patent: May 13, 2003Assignee: DePuy Orthopaedics, Inc.Inventors: Kenneth Ashley Saum, William Michael Sanford, William Gerald Dimaio, Jr., Edward George Howard, Jr.
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Patent number: 6518327Abstract: Graft copolymers are prepared, in a non-oxidizing atmosphere, by (1) irradiating a particulate olefin polymer material with high energy ionizing radiation, (2) treating the irradiated olefin polymer material with at least one grafting monomer that is capable of forming side chains on the olefin polymer material, in the presence of at least one additive to control the molecular weight of the side chains of the polymerized grafting monomer selected from (a) at least one hydroxylamine derivative polymerization inhibitor, and (b) at least one thio-, nitro-, or halogen-substituted aliphatic or aromatic compound or an aliphatic or aromatic phosphine derivative, and (3) deactivating the residual free radicals in the resulting grafted olefin polymer material and removing any unreacted vinyl monomer from the material. Graft copolymers with low molecular weight side chains are produced that are easier to process and have improved internal and surface morphology.Type: GrantFiled: November 2, 2000Date of Patent: February 11, 2003Assignee: Basell Poliolefine Italia S.p.A.Inventors: Vu A. Dang, Tam T. M. Phan, Jeanine A. Smith, Cheng Q. Song
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Patent number: 6517910Abstract: In one aspect the invention provides an energy efficient polymerization method comprising irradiating a polymerizable composition and a photoinitiator with a source of essentially monochromatic radiation where the photoinitiator and the wavelength of the radiation source are selected such that the extinction coefficient of the photoinitiator at the peak wavelength of the source is greater than about 1000 M−1 cm−1 and such that the photoinitiator absorbs at least two percent of the actinic radiation incident on the coating. In another aspect the invention provides energy efficient methods of polymerizing polymerizable compositions and crosslinking crosslinkable compositions by irradiating the respective compositions with a low power source of essentially monochromatic radiation. The low power energy sources have an input power of less than about 10 W/cm.Type: GrantFiled: February 6, 2001Date of Patent: February 11, 2003Assignee: 3M Innovative Properties CompanyInventors: Robin E. Wright, George F. Vesley
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Patent number: 6503989Abstract: A monolayer polyolefin-based printable article includes 0.1 to 5% by weight of at least one polyaminoalkylene, and is characterized in that it has been treated by means of an oxidative surface treatment, such as a corona treatment. A process for the manufacture of a polyolefin-based printable article, according to which at least one surface region of the article, including at least one polyolefin and from 0.1 to 5% by weight of at least one polyaminoalkylene, involves subjecting the region to an oxidative surface treatment. A printing process, according to which a polyolefin-based article, including from 0.1 to 5% by weight of at least one polyaminoalkylene and treated by means of an oxidative surface treatment, utilizes an electrophotography technique to print on the article.Type: GrantFiled: July 24, 2000Date of Patent: January 7, 2003Assignee: Solvay (Societe Anonyme)Inventor: Zdenek Hruska
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Patent number: 6503439Abstract: Disclosed is a method of producing a shaped article suitable for use as the load bearing component of a prosthetic device formed from ultrahigh molecular weight polyethylene. polyethylene.Type: GrantFiled: June 15, 2000Date of Patent: January 7, 2003Inventor: Albert H. Burstein
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Patent number: 6451386Abstract: A process using acrylate monomers and ultraviolet light permits modification of porous polymeric materials without the use of a free radical initiator is described as is the material so modified. The modified polymeric material exhibits new properties such as wetability and advantageous flow characteristics that are useful in filtration.Type: GrantFiled: August 30, 2000Date of Patent: September 17, 2002Assignee: PTI Advanced Filtration, Inc.Inventor: John A. Simonetti
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Patent number: 6444722Abstract: Graft copolymers with low molecular weight side chains are prepared by (1) irradiating a propylene polymer material in the absence of oxygen, (2) adding a controlled amount of oxygen to the irradiated polymer material so that the polymer is exposed to an amount of oxygen greater than 0.004% but less than 15% by volume at a temperature of 40° C. to 140° C., to produce an oxidized propylene polymer material containing greater than 1 mmol total peroxide per kilogram of propylene polymer material, (3) optionally, heating the oxidized propylene polymer material in a non-oxidizing atmosphere to a temperature of at least 80° C.Type: GrantFiled: November 2, 2000Date of Patent: September 3, 2002Assignee: Basell Poliolefine Italia S.p.A.Inventors: Vu A. Dang, Cheng Q. Song
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Patent number: 6437014Abstract: The present invention relates to a method for making a heat-resistant elastic article and a heat-resistant elastic article. The invention especially relates to a method of making elastic fibers and polymeric elastic fibers wherein the elastic fibers are capable of withstanding dyeing and heat-setting processes that typically are conducted at elevated temperatures (such as 110-230° C. and especially at greater than or equal to 130° C. for minutes). The inventive method comprises radiation crosslinking an article (or plurality of articles) under an inert or oxygen limited atmosphere (for example, in N2, argon, helium, carbon dioxide, xenon and/or a vacuum) wherein the article (or articles) comprises at least one amine stabilizer and preferably another optional stabilizer additive. More preferably, the radiation crosslinking is performed at a low temperature (−50 to 40° C.).Type: GrantFiled: July 28, 2000Date of Patent: August 20, 2002Assignee: The Dow Chemical CompanyInventors: Thoi H. Ho, Selim Bensason, Rajen M. Patel, Kimberly S. Houchens, Rona L. Reid, Pak-Wing S. Chum, Leonie K. Walsh
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Publication number: 20020107299Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed contained by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin in transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: ApplicationFiled: January 8, 2002Publication date: August 8, 2002Inventors: Deh-Chuan Sun, Casper F. Stark
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Publication number: 20020107300Abstract: A medical implant of ultrahigh molecular weight polyethylene having an improved balance of wear properties and oxidation resistance is prepared by irradiating a preform of ultrahigh molecular weight polyethylene, annealing the irradiated preform in the absence of oxygen to a temperature at or above the onset of melting temperature, and forming an implant from the stabilized cross-linked polymer. Implants prepared according to the process of the present invention have comparable oxidation resistance and superior wear performance compared to unirradiated ultrahigh molecular weight polyethylene.Type: ApplicationFiled: October 29, 2001Publication date: August 8, 2002Inventors: Kenneth Ashley Saum, William Michael Sanford, William Gerald Dimaio, Edward George Howard
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Patent number: 6423760Abstract: The present invention provides a fully vulcanized powdery rubber having a particle size of from 20 to 2000 nm, its preparation and use. The vulcanized powdery rubber is obtained by irradiating a rubber latex having a particle size of from 20 to 2000 nm with a high-energy irradiation. The vulcanized powdery rubber is very easily to be dispersed into various plastics, and thus can be mixed with various plastics to prepare toughened plastics and fully valcanized thermoplastic elastomers.Type: GrantFiled: October 30, 2000Date of Patent: July 23, 2002Assignees: China Petro-Chemical Corporation, Beijing Research Institute of Chemical Industry, SinopecInventors: Jinliang Qiao, Genshuan Wei, Xiaohong Zhang, Shijun Zhang, Jianming Gao, Wei Zhang, Yiqun Liu, Jiuqiang Li, Fengru Zhang, Renli Zhai, Jingbo Shao, Kunkai Yan, Hua Yin
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Patent number: 6407144Abstract: A process and resulting product is provided in which a vulcanized solid particulate, such as vulcanized crumb rubber, has select chemical bonds altered by biotreatment with thermophillic microorganisms selected from natural isolates from hot sulfur springs. Following the biotreatment, microwave radiation is used to further treat the surface and to treat the bulk interior of the crumb rubber. The resulting combined treatments render the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels and sizes of the treated crumb rubber can be used in new rubber mixtures and good properties obtained from the new recycled products.Type: GrantFiled: April 4, 2000Date of Patent: June 18, 2002Assignee: Westinghouse Savannah River Company, LLCInventors: Carl B. Fliermans, George G. Wicks
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Patent number: 6399671Abstract: This invention relates to rubber polymers based on polymerizable monomers and having an elevated gel content together with an elevated degree of swelling, to the production of the stated rubber polymers and to the use thereof for the production of moldings of all kinds.Type: GrantFiled: July 22, 1999Date of Patent: June 4, 2002Assignee: Bayer AktiengesellschaftInventors: Martin Hoch, Hermann Meisenheimer, Lothar Sesterhenn
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Patent number: 6395799Abstract: A process for reducing or quenching free radical concentration in irradiated ultra high molecular weight polyethylene (UHMWPE) using electromagnetic or mechanical wave energy.Type: GrantFiled: February 21, 2000Date of Patent: May 28, 2002Assignee: Smith & Nephew, Inc.Inventor: Russell A. Johnson
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Patent number: 6372814Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the steps of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: GrantFiled: June 28, 2000Date of Patent: April 16, 2002Assignee: Stryker Technologies CorporationInventors: Deh-Chuan Sun, Casper F. Stark
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Patent number: 6340717Abstract: The invention relates to a process for producing foamed polyolefin-based plastics blocks by first crosslinking a matrix comprising a) from 51 to 97% by weight of one or more polyolefins, selected from the group consisting of polyethylene and ethylene copolymer, b) from 3 to 20% by weight of a foaming agent, using &bgr;-radiation of energy >6 MeV. The thickness of the matrix is from 25 to 45 mm. The radiation dose is from 20 to 150 kJ/kg. During the irradiation, atmospheric oxygen is at least substantially prevented from reaching the surface of the matrix. After crosslinking, the crosslinked matrix is foamed by heating to a temperature >160° C. and decomposing the blowing agent.Type: GrantFiled: February 26, 2001Date of Patent: January 22, 2002Assignees: HT Troplast AG, Studer Draht-und KabelwerkInventors: Werner Hargarten, Hans Jörg Hartmann, Burkhard Voss
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Patent number: 6339112Abstract: The present invention relates to radiation curable compositions comprising at least one metallocene polyolefin. The radiation curable compositions are useful for a variety of applications, particularly as coatings and adhesives. The radiation curable composition may comprise a single metallocene polyolefin, or blend thereof. The ultraviolet curable compositions further comprise at least one photoinitiator and/or at least one photoinduced coupling agent. For pressure sensitive adhesive applications, the radiation curable composition also preferably comprises other ingredients such as a tackifying resins and plasticizers.Type: GrantFiled: November 13, 1998Date of Patent: January 15, 2002Assignee: H.B. Fuller Licensing & Financing Inc.Inventors: Thomas F. Kauffman, John P. Baetzold, Margarita Acevedo
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Patent number: 6316158Abstract: A medical implant of ultrahigh molecular weight polyethylene having an improved balance of wear properties and oxidation resistance is prepared by irradiating a preform of ultrahigh molecular weight polyethylene, annealing the irradiated preform in the absence of oxygen to a temperature at or above the onset of melting temperature, and forming an implant from the stabilized cross-linked polymer. Implants prepared according to the process of the present invention have comparable oxidation resistance and superior wear performance compared to unirradiated ultrahigh molecular weight polyethylene.Type: GrantFiled: October 16, 2000Date of Patent: November 13, 2001Assignee: DePuy Orthopaedics, Inc.Inventors: Kenneth Ashley Saum, William Michael Sanford, William Gerald DiMaio, Jr., Edward George Howard, Jr.
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Patent number: 6291542Abstract: A method and apparatus for selectively curing a sheet of ethylene-propylene diene termonomer (EPDM) material to form a roofing membrane for installation on a roof deck. The method includes the steps of providing a sheet formed of ethylene-propylene diene termonomer, the sheet having a field and longitudinal edge areas bordering the field; and then simultaneously shielding at least one edge area of the EPDM sheet and exposing at least the field to a source of radiation to cure at least the field of the EPDM sheet and provide a selectively cured EPDM roofing membrane. Also disclosed is the product formed by the method of the present invention.Type: GrantFiled: November 20, 1998Date of Patent: September 18, 2001Assignee: Omnova Solutions Inc.Inventors: Michael J. Hubbard, Walter J. Kelly, Anthony Verrocchi, Raymond J. Weinert
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Patent number: 6242507Abstract: A medical implant of ultrahigh molecular weight polyethylene having an improved balance of wear properties and oxidation resistance is prepared by irradiating a preform of ultrahigh molecular weight polyethylene, annealing the irradiated preform in the absence of oxygen to a temperature at or above the onset of melting temperature, and forming an implant from the stabilized cross-linked polymer. Implants prepared according to the process of the present invention have comparable oxidation resistance and superior wear performance compared to unirradiated ultrahigh molecular weight polyethylene.Type: GrantFiled: October 22, 1999Date of Patent: June 5, 2001Assignee: Depuy Orthopaedics, Inc.Inventors: Kenneth Ashley Saum, William Michael Sanford, William Gerald DiMaio, Jr., Edward George Howard, Jr.
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Patent number: 6231804Abstract: A high molecular weight polyethylene prepared by preliminary polymerization is added at the time of main polymerization of an olefin, for example, propylene, to prepare an olefin (co)polymer composition comprising the above high molecular weight polyethylene finely dispersed as fine particles in the polyolefin, such as polypropylene, and a cross-linked structure is formed in the olefin (co)polymer composition. This process can provide a modified olefin (co)polymer composition improved in the strength in a molten state in terms of melt tension or the like and in crystallization temperature and excellent in moldability such as high-speed producibility, and a molded modified olefin (co)polymer composition excellent in properties such as heat resistance and rigidity.Type: GrantFiled: October 1, 1999Date of Patent: May 15, 2001Assignee: Chisso CorporationInventors: Akira Yamauchi, Shingo Kikukawa, Jun Saito, Hitoshi Sato
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Patent number: 6228900Abstract: The present invention discloses methods for enhancing the wear-resistance of polymers, the resulting polymers, and in vivo implants made from such polymers. One aspect of this invention presents a method whereby a polymer is irradiated, preferably with gamma radiation, then thermally treated, such as by remelting of annealing. The resulting polymeric composition preferably has its most oxidized surface layer removed. Another aspect of the invention presents a general method for optimizing the wear resistance and desirable physical and/or chemical properties of a polymer by crosslinking and thermally treating it. The resulting polymeric compositions is wear-resistant and may be fabricated into an in vivo implant.Type: GrantFiled: January 6, 1999Date of Patent: May 8, 2001Assignee: The Orthopaedic Hospital and University of Southern CaliforniaInventors: Fu-Wen Shen, Harry A. McKellop, Ronald Salovey
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Patent number: 6177190Abstract: The present invention relates to pressure-sensitive adhesive compositions. The compositions comprise a poly(1-alkene) pressure-sensitive adhesive component, a non-pressure-sensitive adhesive component, and a radiation-activatable curing agent. The invention further provides pressure-sensitive adhesive tapes and methods for making the compositions and tapes.Type: GrantFiled: May 29, 1998Date of Patent: January 23, 2001Assignee: 3M Innovative Properties CompanyInventors: Mark David Gehlsen, Chad Everett Brown, Patrick Darby Hyde, Eugene Gregory Joseph, Vasant Venugopal Kolpe
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Patent number: 6174934Abstract: A medical implant made of polymeric material having an increased oxidation resistance is formed by a method including the step of placing a resin powder in a sealed container. A substantial portion of the oxygen is removed from the sealed container by either a vacuum, an oxygen absorbent or by flushing with inert gas. The container is then repressurized with a gas such as nitrogen, argon, helium or neon so that long term storage may be possible. On use, the resin is transferred to a forming device which both melts and forms the resin in an oxygen reduced atmosphere to produce a polymeric raw material such as a rod or bar stock. The medical implant is then formed from this raw material annealed and sealed in an airtight package in an oxygen reduced atmosphere. The implant is then radiation sterilized and thereafter annealed in the package for a predetermined time and temperature sufficient to form cross-links between any free radicals in neighboring polymeric chains.Type: GrantFiled: January 23, 1998Date of Patent: January 16, 2001Assignee: Stryker Technologies CorporationInventors: Deh-Chuan Sun, Casper F. Stark
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Patent number: 6168626Abstract: An ultra high molecular weight polyethylene molded article for artificial joints has molecular orientation or crystal orientation in the molded article, and is low in friction and is superior in abrasion resistance, and therefore is available as components for artificial joints. Further, the ultra high molecular weight polyethylene molded article for artificial joints can be used as a component for artificial hip joints (artificial acetabular cup), a component for artificial knee joints (artificial tibial insert) and the socket for artificial elbow joints, and in addition to the medical use, it can be applied as materials for various industries by utilizing the characteristics such as low friction and superior abrasion resistance.Type: GrantFiled: May 6, 1996Date of Patent: January 2, 2001Assignee: BMG IncorporatedInventors: Suong-Hyu Hyon, Masanori Oka
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Patent number: 6160031Abstract: A process for decomposing a polymer which is capable of undergoing thermal depolymerization to its monomer or monomers, such as for example poly(methylmethacrylate), and for the recovery of at least one of the monomers, includes the steps of subjecting the polymer in solid, gel, partially molten or molten form to microwave heating for a time and at a temperature sufficient to decompose the polymer to produce the monomer or monomers in gaseous, liquid or solid form, without substantial decomposition of the monomer or monomers, and recovering at least one of the monomer or monomers. The monomer or monomers may then be reused for plymerisation.Type: GrantFiled: May 19, 1999Date of Patent: December 12, 2000Assignee: AECI LimitedInventors: Ian Douglas Poree, Karol Paula Cameron, Janine Alison Bloem, Fritz Dieter Schlosser, Alison McGowan
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Patent number: 6127433Abstract: Separation functional fibers are produced by exposing fibers with a core/sheath structure to an ionizing radiation and then grafting a polymerizable monomer to the fibers. Ion-exchange fibers are produced by introducing, through radiation-initiated graft polymerization, ion-exchange groups into the sheath of each of composite fibers the core and the sheath of which are composed of different kinds of high-polymer components. The separation functional fibers and the ion-exchange fibers are useful in various applications such as the production of pure water in electric power, nuclear, electronic and pharmaceutical industries and the demineralization of high-salt content solutions in the production of foods and chemicals. The fibers are also useful in removing harmful components from gases, as well as odorous components such as ammonia.Type: GrantFiled: March 13, 1998Date of Patent: October 3, 2000Assignees: Ebara Corporation, Japan Atomic Energy Research InstituteInventors: Takanobu Sugo, Toshihiko Yamada, Hiroyuki Shima, Kunio Fujiwara