1. How can a single component silicone product achieve optimal curing performance?
One-component condensation-cured silicone rubber products are cured using moisture in the air. When cured, from the surface and inside, usually at 25 ° C and 50% RH, condensation-cured silicone rubber can be cured for 3 hours; it takes 7 days to reach the inherent physical properties.
2. Why are there differences in the dry time between winter and summer?
The surface dryness and curing speed of the one-component condensation-cured silicone rubber product has a great relationship with the ambient temperature. The humidity and temperature in winter are low, the dry surface of the glue is dry, the curing speed is slow, the humidity is high in summer, the temperature is high, and the glue surface is dry and solidified quickly.
3. Why is the viscosity different in winter and summer?
The viscosity of the glue changes with temperature, and the high viscosity in summer is reduced. In winter, the opposite is true, but it will be within the acceptable range.
4. How to increase the curing speed?
When the curing thickness is greater than 6mm, it is recommended to use 2 times of filling; increasing the temperature and humidity can accelerate the curing speed of the product, but the temperature should not exceed 50 °C, and the effect of increasing the humidity is better than increasing the temperature.
5. Why is white silica gel easy to yellow?
The ketone oxime cross-linking agent, aminosilane-based tackifier and catalyst contained in the ketoxime-type silica gel may be oxidized by an amino group or some chemical reaction of the catalyst under long-term ultraviolet light irradiation or a high temperature environment of 80 ° C or higher. Yellowing on the surface. To improve the yellowing phenomenon, special formulas such as solar silica gel have good anti-yellowing properties. In the case where the dealcoholized silica gel is not completely cured, the titanate catalyst which does not participate in the reaction is displayed under heat conditions because of its own yellow color, which causes the colloid to turn yellow.
6. What is the temperature resistance of silica gel?
Generally, the temperature of silica gel is in the range of -40 ° C - 200 ° C, the long-term use temperature does not exceed 150 ° C, the special high temperature resistant glue such as iron red silica gel temperature range is -40 ° C -250 ° C, the long-term use temperature does not exceed 180 ° C. The temperature resistance is greatly related to whether the gel is completely cured. When the uncured temperature is completely heated, bubbles, cracks, smoke and other undesirable phenomena may occur.
7. How is the "aerosol" phenomenon of the ketoxime-type silica gel in a closed system?
Deketoxime silica gel is used in closed systems. For example, in lighting, lamp and other industries, it sometimes produces a similar "aerosol" on the inner surface of the glass, which greatly reduces the transparency of the glass and affects the transmittance and aesthetics of the glass. degree. This is due to the fact that in the closed system sizing, the ketone oxime released during the curing of the deodorized silica gel cannot be discharged into the atmosphere in time and accumulates and adheres to the surface of the glass; it is easier to avoid such an aerosol phenomenon by using a dealcoholized silica gel. Because the product released by curing is an alcohol substance, it is a gas at normal temperature and does not aggregate and adhere to the surface of the glass.
8. How to remove silica gel?
Before the silica gel is cured: the uncured paste is scraped off with a putty knife and then the residue is washed with petroleum ether (kerosene). After curing the silica gel: First, mechanically scrape as much silica as possible with a knife or razor, then remove any oil residue or silica gel with a solvent (kerosene or acetone), soak the silica gel in this solvent overnight. It is swollen and then cleaned.