One-component silicone sealant operation process guide and common problems solution
Deketoxime products will corrode copper and hard PC in a sealed environment, which should be paid attention to when choosing.
1. Application process
1. When bonding new materials, applicability experiments must be done to determine whether they can be bonded.
2. Before sizing, be sure to clean up the dirt on the bonded substrates.
3. When using automatic dispensing machine, water vapor isolation is needed for the outlet when dispensing stops for a short time.
4. The curing speed of the adhesive is closely related to the environmental temperature. If the curing speed needs to be accelerated, it can be heated and humidified appropriately according to its own conditions.
2 Notes
1. For unused glue at one time, tighten the tip and extrude a suitable amount of glue for air isolation.
2. Before the glue is completely solidified, it can not be operated in high temperature environment. It also causes bubbles and no adhesion.
3. When it is necessary to dilute the glue, the solvent product must be selected according to the product description, and the operation in a good ventilated environment must be ensured.
4. Due to the limited storage life of products, the principle of first-in-first-out glue is recommended.
3 Common problems and Solutions
1. How can one-component products achieve the best curing performance?
One-component condensation cured silicone rubber products are cured by moisture in the air. The curing time is from the surface to the inside, usually at 25 C and 50% R. H., the condensation cured silicone rubber can be cured for 24 h for 3 mm, and it takes 7 days to reach the inherent physical properties.
2. Why is the surface drying time different in winter and summer?
The surface drying and curing speed of one-component condensation cured silicone rubber products have a great relationship with environmental temperature. In winter, the humidity and temperature are low, the surface drying and curing speed are slow, the humidity and temperature are high in summer, and the surface drying and curing speed are fast.
3. Why are the viscosities different in winter and summer?
The viscosity of the glue varies with temperature. The high viscosity of the glue decreases in summer, but in winter it is the opposite, but it will be within the qualified range.
4. How to improve the curing speed?
When the curing thickness is greater than 6mm, it is suggested to use twice gel filling. Raising temperature and humidity can accelerate the curing speed of the product, but the temperature should not exceed 50C. The effect of increasing humidity is better than increasing temperature.
5. Why does white silica gel yellowing?
The ketoxime silica gel contains ketoxime crosslinking agent, aminosilane tackifier and catalyst. Under long-term ultraviolet irradiation or high temperature environment above 80 C, the surface of ketoxime silica gel may yellowing due to the oxidation of amines or some chemical reactions of catalysts. In order to improve yellowing phenomenon, special formulations are needed, such as solar silica gel, which has good yellowing resistance. Common 737, KE45W and so on in the market, have more serious yellowing phenomenon. In the absence of complete curing of dealcoholic silica gel, the titanate catalyst which did not participate in the reaction would show up under heating conditions because of its yellow color, thus making the colloid yellow.
6. How about the temperature resistance of silica gel?
Generally, the temperature range of silica gel is - 40 C - 200 C, the long-term use temperature is not more than 150 C, the temperature range of special high-temperature resistant rubber such as iron red silica gel is - 40 C - 250 C, and the long-term use temperature is not more than 180 C. Temperature resistance is closely related to whether the colloid is completely solidified. When the colloid is not completely solidified, heating will produce bad phenomena such as bubbles, cracks and smoke.
7. How does the "aerosol" phenomenon of deketoxime silica gel in closed system come into being?
When deketoxime silica gel is used in closed systems, such as lighting, car lights and other industries, it sometimes produces a phenomenon similar to "mist" on the inner surface of glass, which greatly reduces the transparency of glass and affects the transparency and aesthetics of glass. This is due to the fact that butanone oxime released during curing of deoxime silica gel can not be discharged into the atmosphere in time and accumulated on the surface of glass due to the sizing in closed system; the dealcoholic silica gel can be used to avoid such aerosol phenomena more easily, because the products of curing are alcohols, which are gases at room temperature, and will not. Aggregation adheres to the surface of glass.
8. How to remove silica gel?
Before solidification of silica gel: scrape the uns