Crosslinking: Patent Titles
Patents with Abstracts
5. U.S. Patent 8,568,883 (October 29, 2013). “Superabsorbent Polymer Particles with Improved Surface Cross-Linking and Improved Hydrophilicity and Method of Making Them Using Vacuum UV Radiation,” Andreas Flohr, and Torston Lindner (Procter & Gamble Company, Cincinnati, Ohio, USA).
Superabsorbent polymers (SAPs) are well known. Gel blocking reduces absorbent capacity. Swollen SAP particles become very soft and deform easily. Upon deformation the void spaces between the SAP particles are blocked increasing liquid flow resistance. Flohr, and Lindner produced superabsorbent polymer particles of poly(meth)acrylic acid and salts. These particles are irradiated with vacuum 100 to 200 nm UV radiation. Crosslinking covalent bonds are formed on the particle surface and not within the particles. The particles retain their rigidity during absorption reducing gel blocking.
4. U.S. Patent 8,541,491 (September 24, 2013), “In-situ Methods of Generating Water through the Dehydration of Metal Salt Hydrates for Moisture Crosslinking of Polyolefins,” Eric P. Wasserman, Bharat I. Chaudhary, and Michael B Biscoglio (Dow Global Technologies LLC, Midland, Michigan, USA).
Cables, pipes, footwear and foams often use crosslinked melt blended polymers. A useful crosslinking agent is a silane-functionalized resin with a catalyst. Some silane crosslinking is triggered by moisture. However, the needed moisture must diffuse through the material to the reaction site making crosslinking very slow. Wasserman et al developed materials based on copolymers with hydrolyzable groups, a water-generating metal salt hydrate, and a metal catalyst. The compositions are melt mixed to promote the dehydration and start the crosslinking process during the mixing step. The crosslinking is regulated by the silane content of the resin and water generating compound. Sodium L-tartrate dehydrate and dibutyltin dilaurate form a water generating mixture for an ethylene vinyltrimethoxysilane copolymer.
Enzyme-medicated cross-linking of silicone polymers
Zelisko, Arnelien and Frampton of Canada, cross-linked silicone polymers by contacting a silicone polymer and a cross-linking agent with a hydrolytic enzyme under conditions for the cross-linking of the silicone polymer, wherein the silicone polymer has been modified to comprise functional groups that react with the hydrolytic enzyme. Trypsin and pepsin effectively catalyzed the cross-linking of .alpha.,.omega.-(triethoxysilyl)ethyl-polydimethylsiloxane (TES-PDMS), similar to dibutyltin dilaurate. Studies showed little difference between the products of the dibutyltin dilaurate- and trypsin-catalyzed systems. (RDC 3/6/2013)
Polyolefin treatment process for uniform crosslinking
Sun, Taiwan, produced a block of polyolefin material with uniform crosslinking by uniform heating in steps to at least 30 degrees above the melting temperature. The materials is cooled to room temperature under an inert gas; and the oxidized material removed from surface of the block. Optional steps include: subjecting the block to radiation before placing the block into the oven; removing the gases from the oven on a continuous or stepwise basis; controlling the purge gas flow out of the oven; and determining a heating time period for the block by subjecting control blocks to the same process and analyzing them after various heating times. (RDC 1/9/2013)
Method and apparatus for curing a thermosetting material
Inston of Airbus, Great Britain, developed a method for curing a thermosetting material by heating the material with a liquid heating medium; measuring an electrical or optical property of the material with a cure sensor; and regulating the temperature of the liquid heating medium in accordance with the measured property of the material. (RDC 7/5/2012)
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Roger D. Corneliussen
Maro Polymer Links
Tel: 610 363 9920
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Copyright 2012 by Roger D. Corneliussen.
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** Date of latest addition; date of first entry is 7/5/2012.