(1) a reactive adhesive in two components after mixing, crosslinking reaction, produce curing products.
(2) When preparing, the composition and molecular weight of the two components can be adjusted to make it have appropriate viscosity at room temperature, and it can be made into high solid content or solve-free two-component adhesive.
(3) usually can be cured at room temperature, by selecting the raw materials for the preparation of adhesives or adding catalysts can be reduced curing rate. In general, two-component polyurethane adhesive has a greater initial adhesion force, called heating curing, and its final bonding strength is greater than that of one-component adhesive, which can meet the requirements of structural adhesive.
(4) The dosage of the two components can be adjusted in a certain range, and generally there is a certain tolerance. The NCO/OH molar ratio of the two components is generally greater than or equal to L. When curing, part of the NCO group participates in the curing reaction of the adhesive, resulting in chemical bonding force. When the excess NC0 group is heated and cured, it can also produce urea-based formate ester, biuret, etc., which increases the crosslinking degree and improves the cohesion strength and heat resistance of the adhesive layer. For solvent free two-component polyurethane adhesives, because the initial molecular weight of each component is not large, generally speaking, the NCO/OH molar ratio is equal to or slightly greater than L, which is beneficial to complete curing, especially when bonding seals, pay attention to the NCO component can not be too much. For the solvent type two component adhesive, the main agent molecular weight is large, the initial viscosity can be good, the amount of two components can be adjusted in a wide range, NCO/OH molar ratio can be less than 1 or more than 1 several times. When the NCO component (curing agent) is too much, the polyisocyanate self-polymerization forms a tough adhesive layer, which is suitable for the bonding of hard materials. In the case of less NCO components, the rubber layer is soft and can be used for the bonding of soft materials such as leather and fabric.
Since the advent of the two-component polyurethane adhesive, due to its adjustable performance, high bonding strength, wide bonding range and other advantages, has become the most variety of polyurethane adhesive products, the largest output.