High-barrier packaging is of interest to those packaging products in the food, pharmaceutical, medical, chemical and cosmetics industries. It is required to protect packaged products from the infiltration of unwanted gases, water vapor and flavors. High-barrier films are usually achieved by co-extrusion, lamination, coating and layering of polymer films. However, problems such as de-lamination and migration can limit the effectiveness and/or robustness of these barrier films, eventually compromising the barrier characteristics of the packaging. Furthermore, presently available barrier films have been found to be environmentally burdensome because they are not biodegradable. In addition to these shortcomings, there is a growing trend in the packaging industry towards utilizing sustainable materials to make films for various applications. This trend is driven by social, political, economical and environmental concerns motivating a desire to lessen dependency on petroleum-derived products. Hence, technologies are sought that will lessen the environmental burden and petroleum-based content of polymeric blends, while enabling more robust barrier packaging.
Description of Technology
This invention provides a bio-based, biodegradable-polymeric composition that can be used for high barrier packaging applications. The composition consists of a stiff polymer and a flexible polymer, compounded with clay. The stiff polymer is bio-based and is either polylactic acid (PLA) or polyhydroxybutyrate (PHB). The flexible polymer is poly-(butylene adipate-co-terephthalate) (PBAT), and the clay component is montmorillonite clay with nano-sized particles that have been modified with fatty acid quaternary ammonium cations to aid in dispersion. The mixture is reactively blended and has low permeability to water vapor and oxygen as a molded product or blown film. It also has a combination of strength, elongation, and toughness that makes it useful for high barrier packaging applications. The biodegradable blend can be extruded into a thin film that can be used for packaging food and other perishable items.
- Enables improved barrier packaging with a biodegradable film: The bio-based blend provided by this invention can be formed to make film for high barrier applications and will not be environmentally burdensome.
- Reinforced film has high performance characteristics: Polymer-clay nanocomposites have good dimensional stability; resist permeation of oxygen, water vapor, and carbon dioxide; have a higher heat distortion temperature; improved flame retardancy; and improved thermo-mechanical properties compared to polymers without reinforcements.
The high-barrier film provided by this invention is useful as a biodegradable alternative for packaging food and other perishable items, and may be useful for packaging pharmaceuticals, cosmetics, medical devices and sensitive electronics.
1 U.S. patent issued: 7,619,025
Amar Mohanty, Yashodhan Parulekar, Mariappan Chidambarakumar, Napawan Kositruangchai, Bruce Harte