Pressure Sensitives of Fumed Silica

Significant improvements have been observed in cohesive shear strength and thermo-mechanical properties of waterborne pressure-sensitive adhesives (PSAs) due to the incorporation of highly dispersed fumed silica. Adhesive films with fumed silica content ranging from 0 to 15 weight % (dry weight) were formulated from water-based acrylic emulsions designed for PSA applications. The films were formed by drawing down the emulsions on Mylar backing and drying the wet films in a ~ 110°C oven for 20-40 minutes. The dry films were cooled at room temperature, backed with waxed release paper, rolled with a 17-lb weight at a controlled rate, and then incubated for 24 hours at room temperature before the test. The dry films were 1-1.3 microns dry film thickness (DFT). Film shear strength was measured as a function of shear force (1.1 to 4.4 psi) and temperature (room temperature to 100°C) in a two-bank, eight-position shear oven (see Figure 4). Four or more adhesive samples from a given drawdown were typically evaluated, yielding relative standard deviations in time to failure of ~ 15% or less. The film shear strength enhancement was calculated as the mean time to failure of the film normalized by the mean time to failure of the films without particle reinforcement. Shear measurements show significant increases in shear strength enhancement with fumed silica loading as low as a few weight %. For example, at four weight % in the room temperature evaluation, the adhesive shear strength is increased 8-20 times, depending on the shear force. At higher weight % (e.g., 8-15%) and higher temperatures (e.g., 100°C). If you are looking for high quality, high purity and cost-effective Fumed Silica, or if you require the latest price of Fumed Silica, please feel free to email contact mis-asia.

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