Multilayer plastic food containers with

Because of their carcinogenicity, amines have to be monitored. For example, primary aromatic amines (PAAs) are substances that can be transferred from food packaging materials into foodstuffs. In the production of multilayer plastic materials it is common to use reactive adhesive mixtures containing aromatic isocyanate monomers. In cases of incomplete curing, residues of the aromatic isocyanates react with water to produce PAAs. Some of these amines, including... 

MAJOR APPLICATIONS Homopolymer and copolymers—usually with vinyl chloride (VC), or methyl acrylate (MA)—used in solvent-based or latex barrier coatings on cellophane, paperboard, plastic film, and rigid food containers. Films of copolymer used as household cling wrap. Also used with other polymers in multilayer barrier films or containers mostly in packaging applications. Also used in fibers and adhesives. 

Extrusion. Sheet, film, and profiled articles are made by extrusion (20). The resin is melted and forced through a die plate or head. Variations include multilayer and blown film applications. In multilayer coextrusions, different combinations of plastics are separately but concurrently extruded to form layered sheet or film. In the packaging industry, specialty resins such as high barrier ethylene—vinyl alcohol copolymers are combined with heat- and impact-resistant thermoplastics for food packages. The properties of each resin layer are additive, as opposed to the "averaging of property" in blends. Multilayers are also used for blow-molded containers, films, and sheet products (see also Film AND sheeting materials). 

Technologies, such as coextrusion and coinjection, allow PET and other plastics to package foods and other products.225 226> 227 Care must be taken to control the process so that the melt when blown will not have micro-voids in the container walls or will delaminate. Coextrusion and coinjection (or multilayer processes) are essential technique in the production of high performance BM products (Chapters 4 and 5). The parison or preform is coextruded with a number of different layers, each of which contributes an important property to the finished product. Increasingly, a mid layer may consist of recycled material which is encapsulated between inner and outer layers of virgin plastics. 

American Can pioneered the concept of multilayer squeezable plastic bottles with the introduction of its Gamma bottle. Another such product is Continental Plastic Containers Lamicon bottle. The bottles are being used for food products such as ketchup, jelly, mayonnaise, and barbecue sauce. In a new development, polycarbonate has been used by Holmicon Plast as the outer layer, rather than polyolefin, which is normally used. Polycarbonate gives the bottle a more shiny appearance. 

A variety of processes have received official non-objection from the U.S. FDA for use of mechanically recycled PET in food packaging. The earliest processes relied on insensitive uses or on imposition of a physical barrier between the food and the recycled plastic. For example, the first approval was in 1989 for use of recycled PET in egg cartons. Continental PET Technologies received approval in 1993 for a coinjected multilayer PET bottle with a l-rml (O.OOl-in) layer of virgin PET between the core layer of recycled PET and the container contents. The approach was used initially for soft drink bottles in Australia, New Zealand, and Switzerland. In 1994 and 1995, Wellman, Inc., obtained approval for use of mechanically recycled PET in multilayer packaging for a variety of food products. ... 

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