According to the adhesion (bonding force) of plastics and coating film, plastics can be divided into three categories: easy to adhere, difficult to adhere and non-adhesive.
1. Easy to adhere to plastic substrates: such as ABS and PMMA plastics, which can be treated without primer, and can be directly coated with topcoat paint for plastics , which belongs to this type.
2. Difficult-to-adhesive plastic substrates: For example, RIM-PU modified PP requires special treatment (including special primer treatment) before it can be adhered, which is a difficult-to-adhesive plastic.
3. Does not adhere to plastic substrates: If unmodified PP has extremely poor surface activity, without strong treatment , the primer cannot adhere. (Related instrument: adhesion Tester)
ABS, PMMA, PC, PBT and other easy-adhesive primers that do not require primer have relatively high surface energy, and modified PP, RIM-PU, and unmodified PP are difficult-adhesive and non-adhesive primers Low surface energy (see Table, 3-1-5).
