Introduction To The Characteristics of Epoxy Resin Adhesives

Epoxy resin adhesives are widely used due to their excellent bonding properties and chemical stability. They are suitable for bonding a variety of substrates and feature high strength, low curing shrinkage, corrosion resistance, good thermal stability, and good electrical insulation properties. Furthermore, they offer advantages such as simple construction processes, high efficiency, low energy consumption, and low cost, significantly reducing labor intensity and saving labor costs.

One characteristic of epoxy resin adhesives is that the presence of hydroxyl and ether bonds in the structure of epoxy resin gives it high adhesiveness. Due to these polar groups, electromagnetic forces can be generated at adjacent interfaces. During the curing process, along with the chemical reaction of the curing agent, hydroxyl and ether bonds can be further generated, resulting in not only high cohesive force but also strong adhesive force. Therefore, epoxy adhesives have strong bonding strength to many materials such as metals, plastics, glass, wood, and fibers, and are commonly known as "universal adhesives".

The second characteristic of epoxy resin adhesives is that epoxy resins contain a variety of polar groups and highly active epoxy groups, thus exhibiting strong adhesion to various polar materials such as metals, glass, cement, wood, and plastics, especially materials with high surface activity. At the same time, the cohesive strength of epoxy cured products is also very high, resulting in high adhesive strength.

The third characteristic of epoxy resin adhesives is that epoxy resin has good comprehensive mechanical properties, especially high adhesion, very low shrinkage, good stability, and excellent electrical insulation properties, which provides a material basis for adhesives, composite material matrices, powder coatings and other products.

Fourthly, epoxy resin adhesives produce virtually no low-molecular-weight volatiles during curing. The volume shrinkage rate of the adhesive layer is low, approximately 1% to 2%, making it one of the thermosetting resins with the lowest curing shrinkage rate. Adding fillers can further reduce this to below 0.2%. The coefficient of linear expansion of cured epoxy is also very small, resulting in low internal stress and minimal impact on bond strength. Furthermore, the creep of cured epoxy is low, leading to good dimensional stability of the adhesive layer.

Fifthly, epoxy adhesives can be cured at room temperature, medium temperature, or high temperature, depending on the type of curing agent used. Generally, only a contact pressure of 0.1–0.5 MPa is required for curing. Most epoxy adhesives are solvent-free, making them easy to handle. The pot life and curing speed can be adjusted through the formulation to meet various requirements, which not only ensures bonding quality but also simplifies the curing process and equipment.