Canning and Fish Packaging Technology

Unit 12 - Additives in plastics

12.1.3.Anti-static additives
Because all plastics are good electrical insulators they will retain electrostatic changes on the surface. Such charges may be developed by friction between different layers of plastics or between the plastics and processing equipment or by electroionization from dust or radiations. These electrostatic charges on plastics can cause problems during processing or during end use.
The two main problems in processing are

• Adhesion between individual plastics or layers of plastics or between the plastics and processing equipments.
• Discharging to earth by sparking, this can lead to electric shocks to operators, pinholes in the film may be formed and local overheating and in extreme cases it can cause a fin hazard.

The two main properties an electrical antistatic agent should have are,

• A degree of electrical conductivity.
• Tendency to migrate to the surface of the film.

The commonly used antistatic agents are,

• Glycol derivatives
• Quaternary ammonium compounds.