What attention should be paid bonding plastic?
Attention:
(1) Ensure the types of plastic. According to the properties, plastics are divided into thermoplastic and thermosetting plastic. The thermoplastic can melt and dissolve. But thermosetting plastic can not. The thermoplastic and thermosetting plastic can be distinguished through heating and combustion or solvent dissolution. The bonding method of thermoplastic is very different from thermosetting plastic. There are four methods to bond thermoplastic, such as hot-melting, solvent dissolution, solution(combining solvent, plastic powder itself and other auxiliary agent) and gum adhesive. However the thermosetting plastic can be bonded only by adhesives. It is difficult to bond some substrates, such as PTFE, polythene and polypropylene, which need to be treated respectively. The necessary surface treatments always adopt chemical treatment in case of ineffective bonding. Some substrates can be bonded together directly because of their easy-bonding property. For example, the perspex can be bonded by chloroform, while the spectacle frames (cellulose acetate) can be bonded by acetone well.
(2) Choose the appropriate adhesive to bond different plastics.
(3) It is important to choose the reasonable bonding process. Because some plastic surfaces need solvent degreasing treatment. Some need roughening treatment. And some need chemical treatment. Users can finish the bonding process at room temperature. But some adhesives of bonding plastic-metals must cure after heating. On one hand, users need to notice the requirements of thermal curing, the same as cooling process after thermal curing. On the other hand, users need to ensure whether the substrates could stand high temperature.