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Bio-Heat Sealing

U.S. Patent 9,181,010 (November 10, 2015), “Heat-Sealable Biodegradable Packaging Material, a Method for its Manufacture, and a Product Package Made from the Material,” Tapani Penttinen, Kimmo Nevalainen, Jurkka Kuusipalo, Tapio Koskinen, and Sami Kotkamo (Stora Enso OYJ, Helsinki, Finland).

Cardboard packaging is often coated with a barrier to water vapor and oxygen. An outer polyolefin layer makes the material heat-sealable; however, these coatings are not biodegradable.

Penttinen et al. developed a multilayer, heat-sealable, biodegradable coating for cardboard based on a polylactide and a biodegradable polyester. The inner layer has more polylactide than the outer layer. Both have a small amount of acrylic copolymer that improves adhesion and heat-sealing ability. These coatings can be extruded onto cardboard structures.

Cyanurate Networks

U.S. Patent 9,175,137 (November 3, 2015), “Method for Producing Cyanurate Networks via Inductive Heating of Silica-Coated Magnetic Nanoparticles,” Christopher Sahagun, Andrew Guenthner, and Joseph Mabry (The U.S. Air Force, Washington, D.C., USA).

Thermosets with cyanurate crosslinks have outstanding thermal resistance; good flame, smoke, and toxicity properties; low cost; mechanical toughness; and processability. However, forming the crosslinked networks requires high temperatures. Catalysts can lower the required temperature, but they lead to runaway chemical reactions. There’s a need for better temperature control. 

Sahagun, Guenthner, and Mabry developed a method for curing a macromolecular cyanurate network using functionalized silica-coated magnetic nanoparticles in a resin mixture which includes cyanate ester monomers and oligomers. A 1 kHz to 10 MHz alternating magnetic field is applied on top of a static magnetic field to complete curing under controlled temperature conditions. The induction heating of the silica-coated, magnetic nanoparticles induces cyanate ester crosslinking.

Paper Powder Fillers

U.S. Patent 9,174,370 (November 3, 2015), “Fine Paper Powder-Containing Resin Molded Object and Manufacturing Method Thereof,” Michio Komatsu and Takamichi Matsushita (Eco Research Institute Ltd., Tokyo, Japan).

Fine powder from pulverized waste paper is an effective filler for many polymers, such as polyolefins (as in polypropylene chopsticks). High paper content also improves incineration for disposal. However, high paper content reduces flowability, making injection molding difficult.

Komatsu and Matsushita incorporated 1 to 400 parts of paper powder per 100 parts of resin by weight by adding and injecting the resin in a supercritical state. After injection, the pressure is reduced and the mixture foams. The paper particle size ranges from 25 to 200 microns. The foam cell sizes range from 5 to 500 microns. The resin can be polyethylene, polypropylene, polyester, polylactic acid, thermoplastic elastomer, polystyrene, or ABS. 

Electromagnetic Shielding

U.S. Patent 9,169,395 (October 27, 2015), “Polycarbonate Composition and Articles Formed Therefrom,” Constant Peek, Robert Dirk van de Grampel, Andries J. P. van Zyl, and Adrianus A. M. Kusters (SABIC Global Technologies, B.V., Netherlands).

Polycarbonates are synthetic engineering thermoplastic polymers with high impact strength as well as many other good properties. Recent demands for thinner and thinner walls and large display panels require better flowability, as well as impact properties with enhanced electromagnetic shielding. 

Peek et al. developed a candidate material based on a mixture of poly(aliphatic ester)-polycarbonate copolymer, a polysiloxane-polycarbonate copolymer, and electromagnetic shielding agents such as metal fibers. The composition exhibits excellent impact properties and electromagnetic shielding properties when formed into an article. Another composition includes the same resins with carbon fibers. The copolymers provide improved flowabilty and impact strength, while the metal fiber provides the shielding properties. 

Natural Reinforcing Fibers

U.S. Patent 9,163,357 (October 20, 2015), “Process for Providing and Processing Natural Fibres,” Michael Ludwig Gass (Biowert AG, Aarau, Switzerland).

Natural fibers such as hemp, flax, or wood fibers can reinforce plastics such as polyethylene. Such natural fibers are fully biodegradable with a low density. However, these natural fibers often degrade rather than enhance mechanical properties. 

Gass processed natural fibers for reinforcement rather than for degradation. A water dispersion of biomass was macerated, producing fibers containing 20 to 30 wt% alpha cellulose and 15 to 25 wt% hemicellulose, without the use of chemicals. The alpha cellulose provides mechanical stability, while the hemicellulose improves processability. Both types are necessary in the fibers, but there should be more alpha cellulose than hemicellulose in each fiber. A variety of additives can then be added to the fibers for improved mechanical strength, coloring, light fastness, adhesion, and finishing, and reduced flammability.

Corn Syrup Additives

U.S. Patent 9,163,142 (October 20, 2015), “Multifunctional Biocomposite Additive Compositions and Methods,” Michael J. Riebel and Jeffrey L. Tate (GS Cleantech Corp., Alpharetta, Georgia, USA).

Recycled mixed plastics from domestic and commercial wastes are generally incompatible. Available compatibilizers are usually toxic and expensive chemicals. Hence, there’s a need for compatibility and melt agents that are inexpensive as well as non-toxic. Foaming also requires expensive equipment and/or materials.

Riebel and Tate developed biocomposite compositions using dried distiller’s solubles (DDS), which includes condensed distillers solubles (CDS) or corn syrup from alcohol processing and other additives. This DDS consists of 30 to 90 wt% CDS, 5 to 20 wt% metal oxide and 5 to 50 wt% fibers. 

The DDS biocomposite additive can be also used as a foaming agent; as an agent to lower the melting and glass-transition temperatures of a thermoplastic, thermoset, or adhesive material; and as a compatibilizing agent for mixtures of thermoplastics, thermosets, and adhesives.

Polycarbonate Nanocomposites

U.S. Patent 9,163,125 (October 20, 2015), “Method of Preparing a Transparent Polymer Material Comprising a Thermoplastic Polycarbonate and Surface-Modified Mineral Nanoparticles,” Anne Christmann, Jean-Francois Hochepied, Jose-Marie Lopez-Cuesta, Laure Meynie, Alexandra Roos, Nathalie Cornet, Karine Cavalier, Didier Sy, and Marc Lacroix (Armines and Essilor International (Compagnie Generale D’Optique), Paris, France, and Solvay SA, Brussels, Belgium).

Polycarbonate has excellent transparency, shock resistance, high refractive index, and relatively low density. But it tends to be too flexible and sensitive to scratching and abrasion. Mineral nanoparticles can improve these properties, but particle aggregation remains a problem.

Christmann et al. avoided this problem using mineral nanoparticles coated with a monomer and a polymer for optimizing interactions with the polymer and preventing aggregation. Binding of the monomer and polymer is promoted using chlorosilane or organosilane coupling agents. Alkaline-earth metal carbonates, alkaline-earth metal sulfates, metallic oxides, oxides of metalloids, and/or siloxanes particles of 10- to 70-nm size can be added without aggregation by extrusion at up to 15 wt% loading. 

This material can be thermoformed, extruded, calendered, drawn, injection molded, injection-compression molded, or blow molded without loss of mechanical and optical properties.

High-Pressure Composite Molding 

U.S. Patent 9,162,385 (October 20, 2015), “Closed Mold Composite Material Manufacturing Methods, Devices, and Systems,” Eric Escribano and Eric S. Escribano (ESE Industries Inc., Miami, Florida, USA).

Closed-mold composite tooling must be able to sustain very high cavity pressures with long cycles for complete laminate saturation and curing. There’s a need for reducing composite manufacturing cycle time while maintaining high quality.

Escribano and Escribano developed a molding system in which the injection and distribution systems are placed within the pressure chamber. This reduces the pressure differences between the outside and inside of the intricate injection and distribution systems. This also enables higher molding pressure on the final product without damage to the injection system. These higher pressures also eliminate bubbles and surface imperfections. Constant flow rates lead to shorter cycle times.

PHA from Wastewater

U.S. Patent 9,150,445 (October 6, 2015), “Polyhydroxyalkanoate Production during Wastewater Treatment,” Hsin-Ying Liu and Michael Wayne Falk, Jr. (Sacramento, California, USA).

Polyhydroxyalkanoates (PHAs) are biologically derived polymers synthesized as intracellular storage materials by microorganisms metabolizing renewable organic carbon sources. Their properties are similar to conventional plastics. Biomass-derived PHAs are 100% biodegradable, and experts within the field consider PHAs as a potential “green” substitute to conventional plastics. 

Liu and Falk, Jr. developed a wastewater treatment using microorganisms to convert a waste stream to PHA. A waste stream capable of producing enhanced levels of PHA is selected based on short-chain fatty acid, protein, and polysaccharide concentrations, as well as total suspended solids. The waste stream is introduced into an aeration basin for the microorganism synthesis. The PHA-laden biomass is then separated for use.

Packaging with Nanocomposites

U.S. Patent 9,169,389 (October 27, 2015), “Modified Phyllosilicate,” Susana Aucejo Romero, Maria Jorda Beneyto, Jose Maria Alonso Soriano, Miriam Gallur Blanca, Jose Maria Berm dez Saldana, and Mercedes Hortal Ramos (Instituto Tecnológico del Embalaje, Transporte y Logista (Itene), Paterna, Spain). 

Modified phyllosilicates are used as fillers for high-temperature packaging. However, these fillers can be unstable at high temperatures, leading to unpredictable behavior.

Aucejo Romero et al. developed polymer nanocomposites for packaging consisting of polylactic acid filled with a modified phyllosilicate. This silicate is modified by intercalating hexadecyl trimethyl ammonium cations between the layers of the phyllosilicate. This is done by ultrasonically treating water suspensions of the silicate with choline, acetyl choline, and hexadecyl trimethyl ammonium salts between 20 and 120°C. After drying and milling, the nanoparticles can be dispersed in a variety of polymers ranging from polyethylene to polyvinylidene chloride. The polymer nanocomposites are particularly useful for high-temperature packaging of food or drink.

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.