One-component elastic epoxy adhesive research results

Epoxy resin toughening to improve its brittleness and development of latent curing systems, especially medium-temperature curing latent curing agents are important topics in this field. A large number of researchers in China have done a lot of work and achieved Fruitful results.

Epoxy resin is a thermosetting resin with excellent chemical stability, electrical insulation, and good adhesive properties. It is widely used in adhesives, coatings, and other fields as a resin substrate. However, it is brittle after curing, and its internal stress is relatively large. Moreover, commercially available epoxy adhesives are mostly two-component packaging, which has a higher requirement for construction sites. These defects also impose many restrictions on the application of epoxy adhesives. The medium temperature curing latent curing agent can better solve this problem. The latent medium temperature curing epoxy adhesive with excellent domestic properties has certain elasticity after curing, good adhesion performance and heat and humidity aging resistance, and storage temperature at room temperature ( About 3 months at 25°C, it is equivalent to the same kind of adhesive in Japan.

Toughening systems for epoxy resins include the following types: Elastomer toughened epoxy resins. Including nitrile rubber, polyurethane, acrylic rubber, silicone elastomer; thermoplastic resin toughening epoxy; expansion monomer copolymerized modified epoxy resin, the application of some of the system has been basically mature, but the research is still in the toughening carry on. Medium-temperature curing epoxy resin system should meet several requirements: First, suitable activity, general medium temperature curing system curing temperature around 120 °C, at this temperature for a period of time, the reaction should be carried out to a sufficient extent, so that the cured product Has good performance; Second, excellent latent, medium-temperature curing system activity is higher than the high-temperature curing system, so the storage stability has a higher requirement, which is one of the key and difficult to solve, generally requires medium temperature curing The activity of the system should be maintained at room temperature 25 °C for more than one month; fourth, it has excellent water resistance and temperature resistance. According to experts, for latent medium-temperature curing epoxy resins, the choice of curing system is very important. At present, the main approach is to activate some curing agents that can act as curing agents at high temperatures, reduce the curing temperature, or cure some low-temperature and medium-temperature temperatures. The agent is passivated so that it does not function at low temperatures, latent properties are obtained, and the curing agent is released at higher temperatures. The use of the former is more common.

The performance of the domestic latent medium-temperature curing epoxy resin adhesive basically meets several requirements for the medium-temperature curing epoxy resin system. At the same time, through the modification of the epoxy resin, it overcomes its brittleness and it has a certain degree of elasticity, which expands the application range of the epoxy resin adhesive and achieves the performance of the imported similar adhesive.