Study on the Method of Predicting Service Life of Coated Steel Sheets (V)

X-ray Deterioration Behavior of Polyvinyl Chloride Resin Film

Abstract

In order to develop a method of predicting the service life of the steel sheet coated with polyvinyl chloride resin within a short time, the deterioration of the coating of polyvinyl chloride resin by continuous X-ray radiation was studied. The results show that
(1) The coating, when radiated with X-ray, is blackened although the surface conditions and gloss thereof substantially remain unchanged. This phenomenon does not happen at the dew cycle weatherometer test.
(2) The dew cycle weatherometer test and the X-ray radiation test are accompanied by extremely different discoloring of coating, leaching of the plasticizer and generation of the coating crack.
(3) The stabilizer of inorganic lead group is different in effect from the stabilizer of organic tin group in that in the case of the former, the hydrogen chloride which is a byproduct of decomposition of the polyvinyl chloride resin is entrapped.
(4) In respect of the dechlorination of polyvinyl chloride resin, decomposition of lead stabilizer and generation of lead chloride, the X-ray radiation test and the dew cycle weatherometer test have a correlationship, the acceleration effect of the X-ray radiation test being much higher. These changes are also affected by X-ray radiation energy and have relations of an exponential function or quadratic function.