The vulcanization reaction mechanism of addition molding sealing adhesive
Compared to other sealing adhesives, the two prominent features of additive sealing adhesive are its thermal conductivity and flame retardancy. It can be cured at room temperature or heated, and the higher the heating temperature, the faster the curing speed.
The packaging method of addition molding sealing adhesive is generally divided into two components A and B for packaging: catalyst and organic silicon polymer containing vinyl functional groups are used as one component; Hydrogen containing polysiloxane crosslinking agent is used as another component. The mixing ratio is generally based on A: B=1:1, and the ambient temperature has a certain impact on the applicability period of the mixed operation. When the ambient temperature is high, the reaction speed is faster and the operational applicability period is shortened.
The vulcanization reaction is carried out at room temperature or under heating conditions. Do not release by-products. Due to the absence of low molecular weight substances during the cross-linking process, addition molded silicone rubber does not undergo shrinkage during the vulcanization process. This type of vulcanized rubber is non-toxic, has high mechanical strength, excellent resistance to hydrolysis stability (even under high-pressure steam), good low-pressure shrinkage deformation, low flammability, can be deeply vulcanized, and the vulcanization rate can be controlled by temperature. Therefore, it is a type of silicone rubber that is currently vigorously developed domestically and internationally.
The two-component addition molding potting adhesive can be divided into elastic silicone gel and silicone rubber. The former has lower strength, while the latter has higher strength. Their vulcanization mechanism is based on an addition reaction (hydrosilylation reaction) between the ethylene (or propylene) group on the end group of organic silicone rubber and the silicon hydrogen group on the crosslinking agent molecule. In this reaction, polysiloxanes containing hydride functionalities are used as crosslinking agents, while chloroplatinic acid or other soluble platinum compounds are used as catalysts.
Precautions for use:
① When the addition molding sealing adhesive comes into contact with sulfur, sulfides, sulfur-containing rubber materials, amine compounds, amine containing materials, organic tin compounds, and silicone rubber containing machine tin, it can cause the sealing adhesive to not cure.
② When stored for a period of time before being taken out for use, the adhesive may become layered. However, stirring evenly before use will not affect the performance of the adhesive.
③ Glue should be sealed and stored. Mix as much glue as needed each time, and do not mix too much to avoid waste.
④ This product is not a hazardous material, but do not enter or look at it.
Note: Please avoid contact with the above-mentioned substances during use.