Tetramethylcyclotetrasiloxane (H-4) was deposited on mica by chemical vapor deposition. As a result, weight and volume of mica increased with increasing reaction time. The results of infrared spectroscopy of H-4 treated mica showed that H-4 was polymerized by catalytic activity of mica and polymethylsiloxane (PMS) network was formed on the surface and between the layers of mica. Moreover, X-ray diffraction of H-4 treated mica indicated that the PMS films were formed between layers of mica and mica was considered to be cleaved by the PMS films.

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Mechanism for the transfer of surface textures of waterborne basecoats to surfaces of powder clearcoats has been studied using laser-textured dull steel sheets as a model for basecoat surfaces. An automotive powder clearcoat was applied at final thicknesses of 60 and 80μm to the steel sheets. The surface textures of clearcoat films and steel sheets were measured with a profilometer. The surface profiles were analyzed by fast Fourier transformation to obtain amplitude spectra. Transfer ratio, that is the ratio of the amplitude spectrum for the film to the one for the sheet was determined for 13 wavelengths in the range of 89 to 2925μm.
The film surface textures depended on the sheet ones and the transfer ratio increased with increase in the wavelength and with decrease in the film thickness. These results indicate that surface textures of waterborne basecoats transfer to surfaces of powder clearcoats, when the clearcoat viscosity increases during baking and the difference of the shrinkage volume of powder clearcoats between the uneven and flat parts is not compensated by the flow of powder clearcoats. This can be explained in terms of the velocities of the shrinkage and the flow of powder clearcoats, since the shrinkage volume velocity is proportional to the square of the wavelength and the flow velocity is proportional to the product of the wavelength and the film thickness.

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A waterborne basecoat was sprayed onto aluminum strips and stainless steel sheets with a mirror-like surface, and heated at 80°C for 0, 1, 2, 3, 4, 10, and 20 min, respectively. Contents of N, N-dimethylaminoethanol (DMAE) and N-methylmor-pholine (NMM) in the heated waterborne basecoats on the strips were measured by pyrolysis-gaschromatography. An automotive powder clearcoat formulated with a glycidyl functional acrylic resin and dodecanedioic acid was applied to the basecoats on the sheets, baked at 150°C for 30min, and orange peel, that is the film unevenness with about 1-5mm wavelength was ranked by two human inspectors. The powder clearcoat was exposed to DMAE vapor and NMM vapor at room temperature for a week, and flow behavior during baking was determined with an oscillating rheometer.
Both the contents of DMAE and NMM in the basecoat and the film unevenness were reduced with increase in heated flash time. The magnitude of complex viscosity of powder clearcoats treated with amines increased with increase in amounts of amines. This result is explained in terms of the base catalysis of amines for the crosslinking reaction of glycidyl group of acrylic resin and dodecanedioic acid. It is concluded that amines in heated waterborne basecoats migrate into the powder clearcoat layer during baking and promote the crosslinking reaction which raises the viscosity, to make the film surface uneven.

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