Two-component adhesives are 100% solids systems whose storage stability is obtained by separating the reactive components. They are stored in separate containers as "resin" and "hardener". The two components are mixed together only shortly before application to form the adhesive, which cures at room temperature. When cured, two-part adhesives are generally tough and rigid, with good temperature and chemical resistance.

The four main types of two-component adhesives include:

.Epoxy resin

.Systems based on two-component epoxy resins are the most widely used structural adhesives. They can be formulated as fast cure systems with cure times of 2 to 5 minutes. Two-part epoxy adhesives are used to bond metal, plastic, fiber-reinforced plastic (FRP), glass and some rubbers.

.Methyl methacrylate

Methyl methacrylate (MMA) adhesives cure faster and stronger than epoxy adhesives and are more resistant to oils on the substrate. MMA adhesives are used for bonding metals, plastics, classic applications of this adhesive are the automotive industry and rail vehicle construction.

.Silicone adhesive

.Two-component siloxanes are commonly used in the electronics and electrical industry as well as in the production of household appliances, the automotive industry and window manufacture. The nature of the cure is similar to that of one-component moisture-cure silicones. Use two-part silicones instead of one-part silicones when adhesive film thicknesses in excess of 0.25 inches (6mm) are required or for large bond areas. This type of silicone adhesive is also used when the available humidity in the air is insufficient to fully cure the one-part silicone.

.Polyurethane

. Two-component polyurethane adhesives have a wide range of curing properties, from soft and flexible, tough and elastic, to hard and rigid. They are used to bond materials with different flexibility or different coefficients of thermal expansion, including glass to metal, fiber-reinforced plastic (FRP) to metal, and aluminum to steel.

The two-part adhesive can be mixed by hand and is suitable for small applications. However, inhomogeneous mixing is prone to occur during manual stirring and mixing, which in turn affects the curing effect of the adhesive. Therefore, the emergence of 2-part mixing nozzles has solved this problem very well.

The 2-part mixing nozzle is a plastic tube with alternating blades inside. It is usually divided into two types: dynamic 2-part mixing nozzles and static 2-part mixing nozzles. The two-component adhesive can be fully mixed when flowing through the nozzle, and there are many types of mixing nozzles to choose from depending on the viscosity of the adhesive.