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Our Monthly Roundup of Notable Patents.

Biodegradable Nonwoven Fabrics

U.S. Patent 9,573,308 (Feb. 21, 2017), "Melt-blown Method for Producing Nonwoven Fabrics with Hygroscopic Metastatic Feature," Wen- Tung Chou, Ming-Yi Lai, Kun-Shan Huang and Hsiao-Chi Tsai (Acelon Chemicals & Fiber Corp., Changhua County, Taiwan).

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In some respects, nonwoven fabrics are better than traditional fabrics owing to properties and low-cost fabrication. However, most nonwovens are insoluble and non-biodegradable, leading to environmental problems. Biodegradable, hydroscopic nonwoven fabrics with better air permeability, water absorbency and water repellency are needed. Chou et al produced hydroscopic nonwoven fabrics based on bio-polyamide and cellulose fibers. The bio-polyamides from castor bean plants are melt blown, forming a biodegradable mat. A dope of cellulose pulp in N-methylmorpholine N-oxide solvent is extruded, forming and depositing cellulose filaments on the bio-polyamide mat. The resulting hydroscopic, nonwoven fabrics can be finished by needle punching, drying and winding.

Grafted Polyethylene

U.S. Patent 9,574,040 (Feb. 21, 2017), "Disentangled Ultrahigh-Molecular-Weight Polyethylene Graft Copolymers and a Process for Preparation thereof, " Satya Srinivasa Rao Gandham, Ajit Behari Mathur, Uma Sankar Satpathy, Krishna Renganath Sarma and Raksh Vir jasra (Reliance Industries Ltd., Mumbai, India).

Expanding technology demands new polymeric materials with better properties. This requires new and imaginative approaches to modifying existing polymers as well as developing new polymers. Polyethylene is the most popular polymer by cost and availability but limited in the range of possible properties. Copolymerization and grafting can improve properties but usually involves costly and hazardous solvents, as well as high temperatures. Gandham et al developed a solid-state grafting process for disentangled ultrahigh-molecular-weight polyethylene. Disentangled PE powder is produced by single-site catalysts such as phenoxyimine-Ti compounds. This powder is mixed with reactive acrylic monomers and free radical initiators. Grafting reactions is carried out by high shear mixi ng below 150 [degrees]C. The graft copolymers show increased crystallization temperatures between 117 to 121 [degrees]C and increased decomposition temperatures of 460 to 480 [degrees]C.

Extrusion Without Degradation

U.S. Patent 9,579,838 (Feb. 28, 2017), "Method for Extruding a Polymer in the Presence of

Water," Frederic Malet, jean-jacques Flat, Francois Touchaleaume, Jacques Devaux, Patricia Krawczak, Michel Sclavons and jeremie Soulestin (Arkema France, Colombes, France, Universite Catholique De Louvain, Louvain el Neuve, Belgium, and Association Pour La Recherche Et Le Developpement Des Methodes Et Processus Industriels Armines, Paris, France).

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Thermoplastic elastomers such as copolyether-blockamides are extruded or injection molded. However, these materials tend to degrade during processing resulting in discoloration, depolymerization and accelerated aging. Malet et al reduced degradation by extruding in the presence of water. The candidate elastomeric thermoplastic polymers include copolymer block amides, copolyethers, copolyester block urethanes, copolyether block esters and copolyether block amides. Solid resin pellets and water are fed into a twin-screw extruder where the resin is melted and the water blended with the melt. Before leaving the extruder, the water vapor is vented from the extruder. Between 5 to 30 wt% water is added and the extrusion temperature is lowered by 10 to 60 [degrees]C.

On-Demand Degradation

US. Patent 9,580,553 (Feb. 28, 2017), 'Thermally Activated, Self-Immolative Materials," Andrew J. Boydston, Neal A. Yakelis, Ronald Jay Berenson, Derek C. Church, Gregory I. Peterson and Michael Larsen (University of Washington, Seattle, Wash., and Pacific Lutheran University, Tacoma, Wash.).

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Thermally unstable polymers normally degrade by uncontrolled random chain thermolysis. Self-immolating polymers are responsive polymers that undergo controlled head-to-tail depolymerization only by the release of a triggering group from the polymer. Different triggering groups for redox, nucleophile, acid/base, or photo-reactions have been developed. The trigger event releases a reactive group initiating a cascade of depolymerizing reactions destroying the polymer. Boydston et al developed a polymer self-controlled degradation using thermally activated trigger group. The trigger is a cycloaddition group containing carbamoylnitroso or azo groups and cyclic 1,3-dienes that are covalently coupled to the ends of the polymer chains. Heat releases the trigger group, which induces depolymerization by group elimination, cyclization and monomer formation. Applications include controlled drug release, sensors and controlled degradation.

Better Grinding Wheels

U.S. Patent 9,586,307 (March 7, 2017), "Microfiber Reinforcement for Abrasive Tools," Michael W. Klett, Karen Conley, Steven F. Parsons, Han Zhang and Arup K. Khaund (Saint-Gobain Abrasives Inc., Worcester, Mass., and Saint-Gobain Abrasifs, Conflans-Sainte-Honorine, France).

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Chopped fibers are used in resin-based grinding wheels to increase strength and impact resistance. Chopped fibers are added to a dry grinding wheel mixture and then molded and cured for a finished grinding wheel. Problems with uniform dispersion and non-uniform bonding leads to poor grinding performance as well as inadequate wheel life. Klett et al developed grinding wheel materials containing 1 to 59 vol% organic bonding material, 30 to 65 vol% dispersed abrasive, and 1 to 20 vol% uniformly dispersed microfibers. The microfibers have lengths of less than 1,000 microns and diameters less than 10 microns. Candidate fibers include mineral wool, slag wool, rock wool, stone wool, glass, ceramic, carbon, aramid and polyamide fibers. Bonding resins are epoxy or phenolic resins. Active inorganic fillers that bond with the microfibers may be used to further improve function. The critical step is the mixing time which must result in complete and uniform dispersion.

Extruding Varying Internal Capillaries

U.S. Patent 9,586,356 (March 7, 2017), "Device and Method for Dynamic Extrusion Molding of Plastic Article Having Variable Micro-Channel," Zhongbin Xu, )iapei Cao, Xin Fu, Xiaodong Ruan and Suxia Zheng (Zhejiang University, Hangzhou, China).

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Extrusion is widely used for producing plastic articles such as fibers, films, tubes, rods, plates and profiles, with the same cross-section. However, varying dimensions during processing is difficult. Especially difficult is varying internal dimensions such internal channels. Xu et al developed a device and method for dynamic extrusion molding of plastic articles having variable internal microchannels. The system consists of a single-screw extruder, a dynamic extrusion die, a fluid source, a water sink, a tractor and a winding device with a data acquisition and control system. The dynamic extrusion die contains a vibrating syringe. As the melt passes through the die, the vibrating syringe forms internal capillaries by injecting a fluid forming internal microchannels with controlled and varying diameters by the vibrations. The formed melt is pulled into the water sink by the tractor and the extrudate quickly solidifies with internal capillaries with precise diameters.

Scratch-Resistant Acrylics

U.S. Patent 9,587,058 (March 7, 2017), 'Transparent Thermoplastic Resin Composition," Kee Hae Kwon,Jin Hwa Chung,Jin Seong Lee, Man Suk Kim, Kwang 500 Park and Ja Kwan Koo (Samsung 501 Co. Ltd., Yongin-si, South Korea). Thermoplastic resins have excellent physical properties such as lower specific gravity, moldability and impact resistance compared to glass and metals. There is an increasing need for transparent materials with scratch resistance and flame retardancy. Scratch resistance is usually supplied by a hard coating, which adds cost and can lead to environmental problems. Kwon et al developed flame-retardant, transparent acrylics based on a phosphorus-containing acrylic copolymer. This material contains 0.1 to 99 parts by weight acrylic resin, and 0.1 to 40 parts acrylic impact modifier per 100 parts phosphorus acrylic copolymer. The phosophorus acrylics are based on acrylic phosphonates. This material has flame retardancy, heat resistance, good mechanical properties, and flowability, all while maintaining high transparency and scratch resistance.

Anti-Drip Polycarbonates

U.S. Patent 9,587,078 (March 7, 2077), "Processes for Enhancing Flame Retardance and Chemical Resistance of Polymers," jean-Francois Morizur, Paul Dean Sybert, Andrew Frazee, Amanda Marie Flores, Peter johnson and Thomas L. Evans (Sabic Global Technologies BV, Bergen op Zoom, Netherlands).

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Polycarbonate materials have high impact strength and toughness, heat resistance, weather and ozone resistance, and good ductility. Polycarbonates are flame retardant but drip when exposed to a flame, especially with decreasing wall thickness. This behavior inhibits their use in thin-wall applications. These polymers also have poor chemical resistance. Morizur et al increased the drip and chemical resistance using photoactive additives based on reactive ketones. Ultraviolet light induces crosslinking ofthe photoactive additive, resulting in a crosslinked surface. This additive is based on a photoactive ketone that will form stable covalent bonds to the phenolic part of the additive when exposed to ultraviolet light. Example additives are dihydroxyphenone and dihydroxyphenyl-phenylmethanone.

Blow Molding Fuel Tanks

U.S. Patent 9,592,637 (March 74, 2077), "Blow Molding Process and Apparatus," Albert j. Boecker, Andreas W. Dobmaier, Alex Ehler, Patrick Gmuend, Peter Grauer, Gerrit A. Michaelis and Matthias B. Olbrich (TI Automotive Technology Center GmbH, Rastatt, Germany).

Blow molding is used for forming hollow plastic products such as containers, including fuel tanks. In the case of fuel tanks there often is a need to install special components inside the tank such as a fuel pump, a fuel filter, baffles and even hoses and electrical connections. This poses serious practical challenges. Boecker et al developed a blow molding process in which parts of the parison are clamped adjacent to grooved blow molded sections. When the blow mold is opened after blowing, the parison is torn apart into two or more sections. Components are then placed in contact with these separated sections. After assembly, the parts are evacuated or pressurized and reassembled in the mold, the mold closed and the walls fused together. The finished product is removed and further processed as needed.

Polyamide Aerogels

U.S. Patent 9,593,225 (March 74, 2077), "Multifunctional Porous Aramids (Aerogels), Fabrication thereof, and Catalytic Compositions derived therefrom," Nicholas Leventis, Chariklia Sotiriou-Leventis and Malik Adnan Saeed (University of Missouri, Columbia, Mo.).

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Polymeric foams greatly reduce convective heat transfer, combining low density with low thermal conductivity for thermal insulation. Polymeric aerogels with extremely low density are needed with sufficient strength and structural integrity from readily available starting materials. Leventis, Sotiriou-Leventis and Saeed developed porous polyamide aerogels from multifunctional aromatics that combine the high mechanical strength of aramids with the pore structure of aerogels. The polyamides with a hyper-branched structure, low-density and high-porosity are derived from functionalized monomers having more aromatic groups than functional groups. An aromatic multifunctional carboxylic acid or a ferrocene multifunctional carboxylic acid is reacted with a polyfunctional aromatic isocyanate and dried with liquid carbon dioxide. These aerogels can be used to generate precious metal catalysts. These materials can produce carbon-supported Fe, Au, Pt, Pd, Co, Ni, Ru, and Rh catalysts by pyrolysis and transmetalation via galvanic replacement.

Improved Polyethylene Foams

U.S. Patent 9,592,642 (March 14,2017), "Method for Producing Multilayer Polyethylene Resin Foam Sheet," Kazuhiko Morita, Hirotoshi Kakuta and Ryuichi Taniguchi (JSP Corp., Tokyo, Japan).

Polyethylene foam sheets are used in many applications such as shock-absorbing packaging and partitions because of its flexibility and cushioning properties. However, environmental stress cracking remains a problem. Morita, Kakuta and Taniguchi produced a multilayer foam sheet by coextruding a foamable, low-density polyethylene (LOPE) with a physical blowing agent and a foamable blend of 80 to 20 wt% ethylene-propylene random copolymer and 20 to 80 wt% polyethylene homopolymer. This multilayer foam sheet is resistant to environmental stress cracking with excellent aesthetics. The LOPE resin foam layer has a closed-cell structure with strong adhesion to the copolymer layer.

By Roger Corneliussen

ABOUT THE AUTHOR

Dr. Roger Corneliussen is Professor Emeritus of Materials Engineering of Drexel University In Philadelphia. He has been an SPE member since 1962 and an active member of the Philadelphia Section, serving as president and national councilman for several years. The above patents are selected from the 100 to 400 plastics related patents found by reviewing 3,000 to 7,000 U.s. patents published each Tuesday. Readers can review the complete list of plastics-related patents by week at www.plasticspatents com

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Title Annotation:INDUSTRY PATENTS
Comment:Our Monthly Roundup of Notable Patents.(INDUSTRY PATENTS)
Author:Corneliussen, Roger
Publication:Plastics Engineering
Geographic Code:1USA
Date:Jun 1, 2017
Words:1937
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