Bonding technology of polyurethane adhesive (I)

2.Clean and degrease

 

The surfaces of some metal and plastic substrates are often easily polluted by sweat, oil and dust. In addition, there is a release agent on the plastic surface. Therefore, only a weak adhesive interface can be formed between such plastics and the adhesive layer.

For polyurethane adhesive, the compatibility between the grease on the surface of metal or plastic and polyurethane adhesive is poor, and the existing water will react with the-－NCO group in polyurethane adhesive to generate bubbles, which will greatly reduce the contact surface area between polyurethane adhesive and adhesive substrate and reduce the cohesion of adhesive layer. Therefore, the surface cleaning and drying treatment of adhesive base layer must be carried out before using polyurethane adhesive for bonding. The common cleaning and drying methods are as follows: first, clean the bonding surface of the substrate with alkaline water containing surfactant and organic solvent, and then wash and dry it with water. Or use organic solvent (such as acetone, carbon tetrachloride, ethanol, etc.) for direct cleaning. For the metal with rust on the surface, it is generally necessary to remove the rust on the surface with sandpaper and wire brush first, and then clean and dry it.