Recently I have been researching on a new way of powder coating on plastic products. In the current manifactung industry, a minor portion (trade secret) of Tri-Glycidyl Iso-Cyanurate (TGIC) is often added to powders by manufacturers as a crossing-linking agent to enchance durability and finish. TGIC is only required for plastic parts as powder bonding on metal parts would be created by static charge.
However, the risks of the application of TGIC is high:
It is known to increase the sensitivity of the skin and respiratory tract
It is toxic by ingestion and inhalation
It may cause serious eye damage
It is also genotoxic, whereby exposure may cause heritable genetic damage.
Workers may come into contact with TGIC during the filling of hoppers, spraying and touch up spraying, emptying and cleaning extraction ventilation and the cleaning of booths.
Furthermore, according to the Code of Practice of SafeWork Australia, the use of TGIC-free powders is recommended where practical, with the following guidelines:
Follow requirements as per “Spray Painting Code of Practice”
Training to workers using TGIC powders on the health effects of TGIC
Use respiratory protective & personal protective equipment
Conduct spraying in a well ventilated booth
Follow AS 3754 – Safe application of powder coatings by electrostatic spraying for more information
Ensure good hygiene and powder handling methods that minimize dust
Use air purifying respirator
As things stand, there is no current issues of the purchase of powder with TGIC encountered by the manufacturers. And the majority of the local suppliers in Australia do not foresee TGIC getting banned in Australia in the near future. Nevertheless, it is reasonable to have contingency plans for the possible change in policy of the use of TGIC or potential non-availaility of powder with TGIC, which will have a huge impact on varies of plastic products. Therefore, it is crucial for manufacturers to have future readiness on the ability to modify powder coating process using existing equipment (Spray booth, Oven, Spray gun, Temp etc.) to powder coat the plastic parts with regular powder. On the other hand, manfacturers should finalize the design and estimate a realistic cost or real estate to set up dedicated production line for TGIC-free powder coating for plastic products.
Me and my colleagues have decided to carry out a series of testing to discover the limitations and difficulties on this process. And from the test we have concluded that the following part selection criteria to be developed base on for the new powder-coating and cure method.
Shape/profile of the part
Thickness of the part
Physical size of the part
Surface temperature of the part
Heat sink
Scratch test was carried out with the folowing results, with y-axis representing different plastic parts in the market.
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