Effects of the lamination temperature on the properties of poly(ethylene terephthalate-co-isophthalate) in polyester-laminated tin-free steel can - I. Characterization of poly(ethylene terephthalate-co-isophthalate)

The effects of lamination temperature on the properties of poly(ethylene te rephthalate-co-isophthalate) (co-PET), such as thermal, mechanical, and bar rier properties, have been investigated in co-PET laminated steel. The vari ation of the degree of crystallinity and the orientation of the co-PET film during the lamination process was examined using DSC, X-ray diffraction, a nd birefringence, and water vapor permeability was also measured with varyi ng lamination temperature. Both the degree of crystallinity and the orienta tion of the co-PET film decreased and water vapor permeability increased wi th increasing lamination temperature. The stress-strain curves of the co-PE T films were different, depending on the lamination temperature. The stress in the co-PET film laminated at higher temperature was lower at a given st rain, due to the increase of the amorphous region. The effects of annealing temperature and the extent of drawing on the residual stress in co-PET/tin -free steel (TFS) joints were investigated by examining the stress relaxati on behavior of co-PET. It was necessary to heat co-PET/TFS joints at more t han 150 degrees C in order to eliminate the residual stress.