What factors will cause polyurethane potting glue to become sticky after curing?

1. The inner wall of the base material has heavy moisture

A user consulted the editor. After the polyurethane potting glue was completely cured according to the technical requirements, it was tested at double 85 for a week. After taking it out and observing, it was found that there was a separation phenomenon between the colloid and the inner shell of the product, and it was found that there was a separation phenomenon between the colloid and the inner shell of the product. All the surfaces in contact with the inner shell will stick to the hands, and the untouched surfaces will not stick to the hands. The user thought that the potting glue would melt to a liquid state at high temperature after curing. After some technical analysis, the user’s R&D personnel dehumidified the base material. Re-do the reliability test and find that there is no detachment. Cut it open and observe that the colloid is firmly attached to the inner wall.

2. Storage of electronic potting glue

Polyurethane potting glueDuring the storage process of the two components A and B, if the storage environment is not paid attention to, such as the sealing is not tight after use, and the environment is too humid, in this case, component A ( The main agent) absorbs moisture and is mixed with component B (curing agent) for solidification. Partial curing will occur in areas in contact with moisture, causing local stickiness. In severe cases, it will expand and foam. If component B (curing agent) Agent) is improperly stored and absorbs moisture. As a result, the curing activity of component B is weakened. The final mixed curing phenomenon leads to the phenomenon that the whole body cannot achieve a complete curing effect. It is sticky from the outside to the inside, and the application of polyurethane potting glue appears. Whether it is partially sticky or overall sticky can be checked and analyzed from the moisture content of glue A and B. The curing effect of polyurethane potting glue is very sensitive to moisture, and storage requirements must be strictly followed.

3.Electronic potting glueExpired product

Part Users think that potting glue products can be used for a long time as long as the AB two-component products do not come into contact and are not polluted, but this is not true. What the editor wants to tell you here is the knowledge of potting glue curing. Curing is subdivided into thickening stage, preliminary curing stage, hardness stage, and complete curing. All application performance of the product are fully cured, not just molding. , so when the product expires, the activity of the additives in the product decreases. As time goes by, the application activity becomes weaker, and the surface of the cured colloid that cannot achieve the complete curing effect will naturally become sticky. Although some products have expired, they can still be mixed and cured. However, the performance will definitely not meet the initial technical requirements.