Post-forming Properties of Paint Films. II.

Abstract

Post-forming properties of paint films are important for pre-finished metals. In the previous paper, the results of measurement of elongation on T bend tests were reported. According to the results, the elongation of paint films on T bend tests is higher than ultimate elongation of free films which are peeled off from the substrates. Results of measurement of elongation and hardness of peeled paint films do not relate to post-forming properties of the paint films. Because post-forming properties change with the adhesive properties.
In this paper the relations between post-forming properties and mechanical properties of paint films were investigated. Polyester films coated with the paint were elongated. Ultimate elongation of paint films and the double refraction of elongated paint films removed from the polyester films were measured. T bend tests were practised in conditions of good adhesion.
These results fix the relations between post-forming properties and mechanical properties (elongation, hardness, adhesion and so on) of the paint films. When the adhesion is strong, hard and brittle paint films show high elongation and double refraction. Good adhesion reduce higher elongation than yield point and orientation, which increase elongation.