The development of two-component polyurethane sealant is relatively early. Since its appearance, it has become a product with many varieties and large output due to its advantages such as adjustable performance, large bonding strength and wide bonding range.

The category of two-component polyurethane sealant can be divided according to the presence or absence of solvents, including solvent-based two-component polyurethane sealant, solvent-free polyurethane sealant and water-based two-component polyurethane adhesives. In terms of application, there are many varieties, such as universal polyurethane adhesives, two-component polyurethane sealant for composite films, two-component polyurethane sealant for shoes, two-component polyurethane sealant, polyurethane potting sealant, polyurethane structural sealant, etc. The following are the characteristics of two - component polyurethane sealant.

1. Reactive sealant. After the two components are mixed, a chemical reaction occurs to produce a cured product.

2. Flexible formula, wide range of application, a variety of sealant products.

3. Generally, it can be cured at room temperature, and can be accelerated by heating. The initial and final adhesion strength of two-component polyurethane adhesives is usually higher than that of single-component wet curing sealant, which can meet the requirements of structural sealant.

4. The dosage of two components can be adjusted within a certain range, generally there is a certain degree of tolerance. In general, the molar ratio of two components of NCO/OH is greater than 1 or equal to 1. For solute two-component adhesives, the molecular weight of the main agent is large, the initial viscosity is good, the dosage of two components can be adjusted in a large range, the isocyanate component can be greatly excessive. Even the molar ratio of NCO to OH can be less than 1. In the case of excessive NCO components, polyisocyanates self-polymerization to form a tough adhesive layer, suitable for the bonding of hard materials; In the case of less NCO component, the adhesive layer is soft and can be used for adhesion of soft materials such as leather and fabric.