Polyester Film
“In packaging food materials oriented polyester films "OPET" (Orientd PET) as pouches or thermoformed dual ovenable trays made from "CPET" (Crystalline PET) are nowadays very common. The use of such polyester containers need a cover, lid or seal which can both seal the container to prevent leakage of the contents during storage and as well protect the contents from external atmosphere. The top layer or seal should be easily peeled without tear from the container. The lid or seal normally comprises a flexible composite polymeric film consisting of a base polymer layer and a sealable layer of another polymer or a coating layer of another polymer. A strong seal with easy peeling properties is required at both low, e.g ambient and high temperatures. Also the heat seal layer should be transparent, haze free and optically clear.” (Tammaji et al, US Patent 7,820,756; 10/26/2010)
Recent US Patents
10/26/2010
7,820,756
Polymeric composition suitable for manufacturing heat sealable films or sheets
Tammaji et al of Futura Polyesters, India have developed a heat sealable polyester. It consists of 80 to 90 wt% polyethylene terephthalate (PET), 5 to 20 wt% Polyethylene Naphthalate (PEN), Polytrimethylene Naphthalate (PTN), in-situ formed Polyethylene Naphthalate (PEN) and in situ formed Polytrimethylene Naphthalate (PTN) 200 to 1500 ppm nucleating, 30 to 300 ppm polycondensation catalyst, 10 to 30 ppm clear fast reheat (CFRH) additive ; 0.75 to 25 ppm a color toner and 20 to 55 ppm heat stabilizer. The key ingredient is the PEN materials which reduce the melting temperatures of the materials.(RDC 2/18/2011)