Polyethylene terephthalate(PET) film laminated steel sheets have excellent properties such as formability, corrosion resistance and adhesion to steel sheets. They have been widely used for beverage cans. An earlier report described our development of a new PET film laminated steel sheet for use in food cans. Results show that a PET film laminated sheet coated with a mixture of polyester resin and fatty acid amides has excellent content release properties. As described herein, we used ethylene-bis-stearamide as fatty acid amides to study the effects of the amount of fatty acid amides in the polyester resin on content release properties. The behavior of fatty acid amides on the polyester resin surface was analyzed using ATR and XPS methods. Results showed that content release properties are improved stably when the amount of fatty acid amides exceeds 15 wt%. Results showed that surface free energy decreases concomitantly with increasing amounts of alkyl groups contained in the fatty acid amides. The surface free energy value of this material is 15-40 mN/m, which can be controlled by laminating conditions. The laminating temperature above the softening temperature of the polyester resin can change the surface concentration of fatty acid amides because of the uniform dispersion of fatty acid amides being promoted in the polyester resin. This material is useful for various applications by taking advantage of a wide range of the surface free energy.

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