Application of Olivine Powder as a Filler for Silicone Pressure-Sensitive Adhesives

Abstract

In this work, new self-adhesive materials were obtained based on cross-linked silicone self-adhesives obtained by modifying the composition with the addition of a silicon filler, olivine. Silicone pressure-sensitive resin DOWSIL 7358 was used as a basis and modified with various amounts of olivine. New materials (self-adhesive tape samples) were characterized in terms of peel adhesion, tack, cohesion at room and elevated temperatures, SAFT test (shear adhesion failure temperature), pot life (storage stability), and shrinkage (dimensional stability). During the tests, an increase in thermal resistance (>225 °C) and a drastic reduction in shrinkage values (below 0.5%) were noted for all modified samples tested. All tests were performed in compliance with international standards, e.g., FINAT FTM 1, FINAT FTM 8, FINAT FTM 9, FINAT FTM 14, and GTF 6001. This allows us to conclude that the new material has significant application potential due to the good performance results. The results of adhesion and tack were in ranges accepted in the PSA industry, cohesion was kept at an unchanged level (above 72 h), and a great increase in the thermal resistance was observed (from 147 °C for pure resin to high above 225 °C for even the smallest additions of the olivine powder. Moreover, the shrinkage of prepared adhesive films was reduced significantly. In the available literature, there are no references to the modification of adhesives using powdered silicon minerals of natural origin, which is a novelty due to their higher bulk density compared to commercial powdered silicon fillers.