The surface treatment of stainless steel with silane coupling agents was investigated. Surface treatment with γ-glycidoxypropyltrimethoxy silane (GPS) remarkably improved the adhesion durability of stainless steel in wet environments. The improvement resulting from surface treatment with γ-aminopropyltrimethoxy silane (APS) was however not so great. XPS results gave strong evidence of protonated amino groups of APS which hinder the formation of polysiloxane structures at the stainless steel / APS interface. However, XPS and, μ-AES results indicated thick polysiloxane structures at the interface, which can improve the adhesion durability in wet environments. From these results the difference between GPS and APS as promoters of the adhesion durability of stainless steel could be explained.
The organic-inorganic hybrid polymer network was obtained by platinum-catalyzed hydrosilylation, as a thermally crosslinking reaction, of poly (oxyvinyl-1, 2- cyclohexylene) (POVCH) / poly (phenylmethylhydrogensiloxane) (PMHS). From the 29Si-NMR analysis of the product as a model reaction of POVCH/PMHS, hydrosilylation was found to occur selectively. The thermally cured films of POVCH/PMHS had glass transition temperatures in the range of 106 to 118°C and showed excellent alkali resistance (0.1 mol/1 KOH ethyl alcohol solution). Compatibility between POVCH and PMHS was excellent. From XPS measurement, the cured films were found to be uniform in composition. The gloss of the cured film of POVCH/PMHS remained stable after the fluorescent UV-condensation cycle test for as long as 2000h. Outdoor exposure was carried out on two kinds of coatings of POVCH/PMHS and acrylic/melamine for three years in Neyagawa. It was found that color change (_??_E) of the unwashed panel of POVCH/ PMHS was 1.2, whereas that of the unwashed panel of acrylic/melamine was 12.0.
Internal stress in organic coatings has been commonly measured by the bending beam technique. In this study, a new method for the measurement of internal stress, TFD (thin foil deflection) method is proposed. In a strip of coated thin aluminium foil, the deflection appeared sidways. The TFD method derived internal stress from the deflection. The coated thin foil can be considered as a bimetallic strip. The deformation of the common surface occurs in such a manner that foil layer is compressed and coatings layer is extended. The calculation of internal stress was based on the equilibrium of the bending moment in the cross section. Using the TFD method, internal stresses in epoxy-phenolic coatings were measured under various thermosetting temperatures. Internal stress values obtained by the TFD method agreed closely with those obtained by FSB (free film stretch back) method.