2013 Volume 99 Issue 4 Pages 288-293
The influence of volatile elements on the popping of polyester resin solutions on the substrate steel sheet was investigated by heating substrate with various patterns of rising temperature. The results were as follows.
1) When using the resin solution which did not include any hardener, the bubbles which were generated at comparatively low temperature were deleted with the rise of the temperature. This is because the diffusion barrier for the volatile elements in the resin solution film was very low. On the other hand, in the case where the hardener exists, the bubbles were not deleted. Therefore, for the purpose of the popping prevention of thermal hardening type-polyester resin solutions, it is necessary not to generate any bubbles into the film during the heating process within all ranges of the temperature.
2) In the heating process of the resin solution film, the temperature range where the bubble occurs existed. When this range was heated at low-speed, the popping was controlled. This temperature range was almost corresponding to the evaporation temperatures of the volatile elements (solvents and reaction products) of the resin solution inside. However, when strictly seeing, this range was being shifted a little to the low temperature side than the evaporation temperatures. It is thought that the diffusion of the volatile elements was obstructed along with the rising of viscosity of the resin solution, and the partial pressures of the volatile elements were relatively risen in the resin solution.
