Acrylic latex film formation in the critical temperature range

A shear wave of 15 megacycle frequency and four microsecond duration was made to impinge on the under-side of a series of ethyl acrylate-methyl methacrylate copolymer films on fused quartz. Reduction in the reflection coefficient of the pulse provided a direct measure of the increased viscosity and elasticity of the film as it dried, as well as the loss in adhesion which occurred in some cases. Upon reducing the minimum film-forming temperature (MFT) from 54 to 32°C. by increasing the ethyl acrylate content from 35 to 50%, the adhesion loss was reduced, eventually to zero, depending on the drying rate. Despite the fact that elasticity of the latex particles is the controlling parameter in film quality, a dependence on their viscosity was revealed by this work.