MEASURING METHOD FOR DETERIORATION OF FILM

PURPOSE:To decide whether the weather resistance of resin is good or not in an extremely short time without taking any long-period natural exposure test by irradiating a film of a coating material with light and producing an alloxyle radical. CONSTITUTION:A compound which produces an alloxyle radical by light irradiation is added to the resin whose weather resistance is to be compared. The obtained coating material is applied to the outside of a sample pipe for electron spin resonance measurement by dip coating, spray coating, etc., and left at room temperature or heated to form a cured film. This obtained cured film is inserted into the cavity of an electron spin resonance measuring instrument. While light is irradiated, the alloxyle radical produced by the light irradiation is measured as the height of a spectrum. The light irradiation is carried out only until the amount of the alloxyle radical has a difference. The larger the amount of the alloxyle radical produced in every film to be measured, i.e. the value of the height of the spectrum is, the lower the weather resistance is.