Waterproof Modified Silicone Adhesive
Author: Zhe-Yong, Lin
There are lots types of RTV1 products on the market, and the obvious advantages of most used silicone adhesive are working temperature(-40~200oC) and great water repellency. However, there are both advantages and disadvantages: The binding ability of silicone is weak in common, and the binding ability for mentals and plastics is less than 20kgf/cm2 in average, so derived from modified silicone which shows great binding ability (>20kgf/cm2). However, the drawback is the water absorption ratio of modified silicone polymers is higher than silicone, so that we have developed modified silicone adhesive: FS332BL67 with waterproof purpose and high binding ability.
As Figure1, the tensile strength test on the PC vs PC specimen of tensile strength resin socking at 80oC for 5 days; as a result, after socking in warm water, it turns up that the tensile force of many products has dropped. There are three reasons: (1) Water will migrate between resin and substrates binding interface that replaces the bonding of resin and substrates originally. (2) Modified silicone polymers design will lose the strength due to breaking chain hydrolytic reaction of ester group. (3) Resin will swell and become soft that leads the strength of resin itself dropped so as the tensile force dropped. However, with formula modification, the binding ability of FS332BL67 remains constant that do not drop like other products. As Figure2, compared with competitive products on the market, it can be observed that FS332BL67 remains great binding ability and low water absorption. Among them, even though 709X silicone has the characteristic of low water absorption, but the binding ability cannot meet the need of high binding ability for precise electronics and electrical industry. As Figure 3, modified silicone FS332BL67 has great binding ability on extensive substrates, and this product is tin-free catalyst added, working temperature is -40~100oC, and has Ti(1rpm/10rpm)=(2~3) which can apply on seal ring grooves in optical electronics industry. If you are interested, please contact us.
