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Biodegradable Blends for ISBM

U.S. Patent 9,206,305 (December 8, 2015), “Polypropylene and Polylactic Acid Blends of Injection Stretch Blow Molding Applications,” Fengkui Li, Luyi Sun, John Ashbaugh, David Rauscher, Leland Daniels, and Robert Dotter (Fina Technology, Inc., Houston, Texas, USA). 

Synthetic polymeric materials like polyethylene terephthalate (PET) and polypropylene (PP) are widely used in injection stretch blow molding (ISBM) for containers. Disposal is a problem. These materials degrade very slowly in a natural environment such as a landfill. Additives such as polylactic acid accelerate degradation, but they also degrade mechanical and other physical properties. There’s a need for biodegradable blends for ISBM with adequate impact strength as well as other desirable properties.

Li et al. developed a biodegradable material consisting of 65 to 95 wt% polypropylene with 35 to 5 wt% polylactic acid and 1 to 10 wt% impact modifier. This material can be injection molded and stretch-blown with the desired properties. The modifier can be epoxy-functionalized polyolefins, PP-g-nylon, ethylene-methacrylate copolymer, styrene ethylene butylene styrene (SEBS), maleated SEBS, and maleated polyolefins.

Wear-Resistant Molds

U.S. Patent 9,199,400 (December 1, 2015), “Methods of Injection Molding an Article,” Robert Keith Judd and Terry Mitchell Lewis (US Synthetic Corp., Orem, Utah, USA).

Injection molding is an efficient process to produce a wide variety of parts. Typical molds are typically metals, such as steel, aluminum, brass, and copper. However, mold wear often limits process lifetimes and productivity.

Judd and Lewis used “superhard” materials for surfacing the molds, decreasing wear and improving productivity (“superhard” refers to any material having a hardness that’s at least equal to the hardness of tungsten carbide). The superhard material forming the wear-resistant surface may be diamond, polycrystalline cubic boron nitride, silicon carbide, or diamond grains bonded together with silicon carbide. Fabrication includes high pressure and temperature sintering or chemical vapor deposition. 

Antimicrobial Foam

U.S. Patent 9,193,820 (November 24, 2015), “Antimicrobial Polyurethane Foam and Process to Make the Same,” Bhalchandra M. Karandikar and Bruce L. Gibbins (Avent, Inc., Alpharetta, Georgia, USA).

The versatility and economics of flexible polyurethane foams are attractive for absorbent wound dressings. These dressings must remain in place for several days to absorb the wound exudate, and be antimicrobial. 

Karandikar and Gibbins developed an antimicrobial polyurethane foam that is formed from a multi-functional isocyanate, an aqueous polyol, an antimicrobial metal, and a complexing agent. The complexing agent forms a stable blend of the antimicrobial metals with the polyol. Complexing agents include amine compounds, ammonium-containing compounds, and ammonia. The antimicrobial metals can be silver, zinc, or copper compounds, such as silver saccharinate. 

Fluoropolymer Foams

U.S. Patent 9,193,811 (November 24, 2015), “Expandable TFE Copolymers, Method of Making, and Porous, Expanded Articles Thereof,” Lawrence A. Ford (W. L. Gore & Associates, Inc., Newark, Delaware, USA).

Stable polytetrafluoroethylene resins are difficult to foam for many applications. Ford developed an expandable tetrafluoroethylene (TFE) copolymer powder containing 1 wt% or more co-monomer. This material can be expanded to form strong, stable foams consisting of nodes connected by fibrils.

The foams are formed by powder extrusion and stretching above 250°C. The copolymer is produced by free-radical polymerization with 0.005 to 0.05 mol% co-monomer. The co-monomers may be fluorinated monomers or olefins such as ethylene, propylene, and isobutylene. Articles made from the expandable copolymer may include tapes, membranes, films, and fibers, and are suitable in a variety of end applications such as medical devices.

Telechelic Polyolefins

U.S. Patent 9,187,581 (November 17, 2015), “Methods for Producing Telechelic Polyolefins from Terpene Initiators,” Casey D. Stokes and Young Chang (Chevron Oronite Company LLC, San Ramon, California, USA).

Telechelic polymers are polymers with reactive functional end groups enabling copolymerization. These are used to form high-performance polymers such as fuel or lube oil additives, network polymers, star-branched polymers, and block co-polymers. Present methods for synthesizing telechelic polymers rely on post-polymerization functionalization, which is inefficient and costly. 

Stokes and Chang prepared telechelic polyolefin polymerization with a terpene initiator with functional groups that survive polymerization. A hydroxyl terpenoid initiator results in a telechelic polyolefin with hydroxyl groups and molecular weights from 300 to more than 1,000,000 g/mol.

Domain Orientation

U.S. Patent 9,181,426 (November 10, 2015), “Method of Controlling Orientation of Domains in Block Copolymer Films,” Joy Cheng, Ho-Cheol Kim, Daniel P. Sanders, and Linda Sundberg (Global Foundries Inc., Grand Cayman, Kentucky, USA).

Block copolymer films can be used as a part of an assembly system in which nanoscale structures form when blocks of the copolymer phase separate into microdomains. One problem in block copolymer patterning is controlling orientation of the assembled microdomains. 

Cheng et al. developed a method of orienting microphase-separated domains using an orientation control component. With a neutral orientation control coating, the block copolymer domains form at the interface and extend vertically from the surface of the substrate.

These coatings are formed spin coating, spray coating, doctor blading, and dip coating followed by baking. The orientation control consists of a crosslinked epoxy. The block copolymer can be di-block copolymers as well as multi-block copolymers.

Note: The above patents were selected from 100 to 400 plastics-related patents found each week by reviewing 3,000 to 7,000 U.S. patents published each Tuesday. A complete list of plastics-related patents is listed by week and topic at www.plasticspatents.com. Readers are invited to visit this site to see the latest patents, without charge.