What are the differences between PU Adhesive and Epoxy Resin

Polyurethane adhesives are mainly composed of ammonium isocyanate, polyols, hydrocarbon-containing polyethers, polyesters and epoxy resins, fillers, catalysts and solvents. It has many excellent properties such as high reactivity, curing at room temperature, and impact resistance.

 

Polyurethane adhesives are generally divided into two basic types: one-component and two-component. One-component is moisture-curing type, and two-component is reaction-curing type. One-component glue is easy to construct, and two-component glue has the characteristics of fast curing and good performance, but it needs to be prepared when used, and the process is relatively complicated. Both have their own development prospects.

 

Polyurethane adhesives have slightly lower bonding strength and are prone to yellowing, but have higher wear resistance and toughness. One-component polyurethane adhesives can be moisture-cured at room temperature, requiring relatively low conditions. Epoxy adhesive has high bonding strength and shear strength, and has a wide range of applications. It can bond most materials except polyolefin materials, so it is called all-purpose adhesive. One-component epoxy adhesives require higher temperatures and may require heating or special handling.

Both polyurethane adhesive raw materials and epoxy resin adhesive raw materials are actually toxic. For example, polyurethane curing agents are mostly isocyanates, which have high activity and are relatively harmful to human kidneys. The organo-a tin in the catalyst belongs to poisonous or highly toxic chemical raw materials. The amine curing agent in the epoxy resin adhesive is also toxic, and the reactive diluent is a poisonous or highly toxic chemical raw material. However, these two adhesives are basically non-toxic after curing, so it is not clear which type is less toxic, only that the application is slightly different.

There are differences between polyurethane adhesives and epoxy adhesives, but there are also many cross-cutting fields, such as the bonding of wood, stone, metal and fiberglass in building materials. The former can be used for those with high toughness requirements, such as the bonding of filter paper for high-efficiency filters in the air purification industry and aluminum frames. For those with high strength requirements, epoxy adhesive can be used.