4 mm was lined by pressing the film against the steel plate at a pressure of 0 1 kg cm 2 at a temperature of 170 u00b0 c for 2 minutes in comparative example 2 modified polyethylene coating was directly applied onto the sand blasted steel plate without applying any primer coating composition in example 13 prior to applying the primer coating the steel plate was preheated to a temperature of 50 u00b0 60 u00b0 c coated with a chromate based conversion coating liquid prepared by mixing an aqueous solution of cro 3 with ethylene glycol sufficient to reduce 40 of cro 3 and further adding thereto colloidal silica having a particle size of 14 m u03bc and allowed to stand until the applied coating was dried by the latent heat of the plate the amount of coating was 1000 1200 mg m 2 after drying the resulting polyolefin coated plates were tested on adhesion strength and cathodic desbonding resistance according to the following methods the results obtained are shown in table ii the coating was scratched to form a plurality of parallel cut lines at a distance between lines of 10 mm to the full depth of the coating a section of cut polyethylene film was peeled from the steel plate and its peel strength adhesion strength at 180 u00b0 angle was measured at 20 u00b0 c and 60 u00b0 c respectively at a pulling speed of 10 mm minutes using tensilon tester the same test as above was repeated except that the scratched sample.