Author: Zhe-Yong, Lin
There are many types of one component liquid moisture curing products (RTV1) on the market. The prominent advantage in silicone field that it has good adhesion to various substrates, wide range of working temperatures (-40~200 oC), and long-term weather resistance. We have designed different formulations for different customers. Our moisture curing products can be divided into acetic acid type, ketoxime type, amide type, acetone type, and dealcoholization type, but most of them may cause some problems, such as pungent odor, corrosion and degradation on substrates, excessive volatile organic compounds (VOCs). The dealcoholized silicone type is less harmful, but the problem is that exhibits lower storage stability, lower curing rates, and poor adhesion. However, Our new products FX191/FX195 series have overcome these challenges.
As shown in Figure 1, the adhesive strength is up to 45%, after the high-temperature curing at 200 degrees for 500 hours. This phenomenon could be explained by two factors: (1) Cohesion: the strength of the adhesive resin, (2) Adhesion: Adhesion between resin and substrate. In the environmental testing, the temperature and UV radiation may promote resin formulation to generate free radicals. Due to the free radicals attack the resin, it may cause the material to become brittle and yellowing. Finally, the cohesive force is reduced. The above conditions are common expected results. On the other hand, the temperature is a factor that helps molecular chains to rearrange it, because molecular chains can move easily and rearrange densely stacked under high temperature. Let's take annealing as an example, the cohesion is increased after returning to room temperature. Therefore, the stable formula provides high temperature which will further promote the dhesion strength within the allowable operating temperatures. As shown in Figure 2, the adhesive strength under the high temperature test has declined but still maintained 70% of the initial adhesive strength. As shown in Figure 3, we evaluate the stability of the product during long-term storage by curing at 300 hours high temperature. We can find out that the changing rats of viscosity only shows 7%. The surface drying time remains stable, which can ensure that the product storage stability is excellent. As shown in Figure 4, we have developed many types of adhesives that they can meet customer requirements. We could be adjusted to customer's needs, including viscosity, sag resistance, curing time, and strength. You are welcome to contact us if you have any questions.
