The development of high-performance polymer-based packaging materials and structures has allowed the evolution of light-weight, flexible films and rigid containers, bottles and trays that protect the contents against the ingress or egress organic vapors, aromas, moisture, oxygen and other gasses. The goal is to make the underlying technologies transparent while minimizing the financial and environmental costs of these products to the final consumer. There is still a considerable need for polymer materials and packaging systems that provide longer shelf-life stability under a wide range of storage conditions and food products. The present invention relates to barrier structures for food packages that are useful in providing extended product shelf life.
The outright size of the packaging industry makes it an attractive market with incredible numbers of technical challenges, e.g., flavor losses by scalping, tainting by off-odors and flavors, oxygen ingress, odor control, photodegradation (loss of value due to light sensitivity), loss of moisture, source reduction/waste recycling and environmental/social considerations. As fundamental polymer science innovations increase, the applications for new packaging expand considerably as well as the complexity of the solutions, thereby providing an ever-growing market for innovations. Current estimates suggest that the dollar value of the polymers used to manufacture packaging alone will account for more than $19 billion in 2002. The exploitation of olefin polymers as a packaging material has provided substantial advantages to producers, retailers and consumers over traditional glass, aluminum and metal materials since their introduction in the 1950's. The driving force for innovation has been to develop convenient and transportable packaging consumer's demand, while continuing to improve the functional properties for protecting freshness, quality and safety at an affordable price by using more innovative technologies, complex materials and structures.
Globalization of the food industry and their packaging suppliers is presenting challenges from a regulatory standpoint as materials to be exported must meet the requirements of whatever country to which the product is to be shipped. For the packaging innovator introducing novel packaging technologies, this represents a massive, protracted and costly undertaking. The regulatory agencies require that the materials, which are being manufactured, meet stringent safety standards for both human exposure and the environment.
Packaging materials have been the target of environmental and consumer activist groups as being a major contributor to the solid waste stream; these materials make up over one-third of the total waste generated in the United States. In many cases, manufacturers want to achieve source reduction and cost reduction by combining polyolefin layers of different barrier materials (e.g., nylon, polyvinylidene chloride—PVDC, ethylene vinyl alcohol—EVOH, etc.) to achieve the desired barrier properties and gauge; metallization of packaging films is yet another technique. In some cases, these approaches create incompatibility problems for pre-consumer in-plant scrape recycle and for post-consumer plastic recycle streams. Environmental considerations clearly influence current packaging technologies and will certainly continue to do so in the future.
In today's competitive markets, all technology innovations are driven by intense competition and therefore must meet the costs constraints and targets of the industry. The principal cost drivers in today's packaging are the raw materials. The value new, innovative technology brings to the package must be weighed against the added cost.
The invention provides a polyolefin having a grafted cyclodextrin to diminish regulatory concerns because the cyclodextrin is covalently bonded to the polymer eliminating food safety concerns related to cyclodextrin migration. The present invention provides an innovative functional material with significant property improvements that is compatible with source reduction, in-plant scrape recycle and post-consumer recycling.
The invention forms compatible cyclodextrin (CD)/functionalized polyolefin composition by grafting a parent, unmodified cyclodextrin onto a polyolefin using extrusion processing to reduce both material, manufacturing and regulatory costs and to lessen the impact on the environment which otherwise takes the synthetic route to synthesize a compatible cyclodextrin derivative.
The invention also provides a commercial polyolefin material having greater crystallinity and lower surface energy to effectively change the partitioning of compounds in direct contact with the polymer especially nonpolar compounds (e.g., alkanes, aromatic, terpenes and sesquiterpenes).