Environmental factors have obvious influence on the curing properties of silicone structural adhesive

2021-02-01 17:00:20

Environmental factors have obvious influence on the curing properties of silicone structural adhesive. The first is the influence of temperature. The higher the temperature, the faster the curing reaction. The phenomenon is that the surface drying and debonding are relatively fast. If the temperature is very low, such as below 5 ℃, the curing of sealant will be very slow.

If the temperature is too high, such as above 40 ℃, the sealant will be too fast to use. Humidity also has a significant impact on the curing performance of sealant, because the curing reaction of sealant needs water in the air, so too dry weather such as relative humidity below 40 ℃ is unfavorable for the curing of sealant.

But it is not that the higher the humidity is, the better, because the volatile small molecules are released when the sealant is cured. If the air humidity is too high, the small molecules are not easy to volatilize, which is not conducive to the curing of sealant. Experiments have proved that when the relative humidity is higher than 80 ℃, the sealant debonding and deep curing will be affected, sometimes after 2-3 days, the surface of the sealant is still sticky. The standard conditions of sealant performance specified in national standard are temperature (23 ± 2) ℃, relative humidity (50 ± 5) ℃.

The curing time of glass adhesive increases with the increase of bonding thickness. For example, it may take 3-4 days for acid glass adhesive with 12mm thickness to set, but the outer layer of 3mm has been cured within 24 hours. Bonding glass, metal, or most wood has a peel strength of 20 pounds per inch after 72 hours at room temperature.

If the place where glass glue is used is partially or completely sealed, then the curing time is determined by the tightness of the sealing. In a closed place, it is possible to remain uncured forever. If the temperature is raised, the glass glue will become soft. The gap between metal and metal bonding surface shall not exceed 25 mm. In all kinds of bonding occasions, including closed cases, the bonding effect should be comprehensively checked before using the bonded equipment.