Yellowing Causes of Flame-Retardant ABS

Compared with pure ABS raw materials, flame-retardant ABS inherently tends to have a yellowish tint, a phenomenon closely related to the addition of flame retardants. To achieve flame-retardant effects, brominated flame retardants—such as tetrabromobisphenol A (TBBPA), decabromodiphenylethane (DBDPE), and brominated triazine—are commonly added to flame-retardant ABS. Some of these flame retardants are pale yellow in their original form, while others degrade to a pale yellow color during use. Additionally, flame retardants are prone to decomposition under high-temperature conditions. If the temperature is improperly controlled during injection molding, excessively high temperatures will accelerate material degradation, further exacerbating product yellowing.

To address the yellowing issue of flame-retardant ABS products, it is necessary to first accurately identify the cause and then take targeted measures:

1. Yellowing Caused by the Intrinsic Color of Flame Retardants

Solve this from two aspects: raw material selection and formula adjustment.

• Formula adjustment: Add an appropriate amount of colorants (such as titanium dioxide or blue powder) during the modification process to neutralize the pale yellow tint through color matching, improving the material’s appearance.
• Raw material selection: Prioritize flame retardants with lighter color and higher whiteness to minimize their impact on the material’s color at the source and reduce the probability of yellowing.

2. Yellowing Caused by Material Degradation from Excessively High Processing Temperature or Prolonged Material Residence Time

Optimize injection molding process parameters:

• Based on the material’s characteristics, reasonably lower the processing temperature to avoid local overheating that triggers flame retardant decomposition and material degradation.
• Control the residence time of materials in the barrel to reduce repeated heating, thereby suppressing yellowing through process optimization.

3. Yellowing Caused by Insufficient Antioxidant and Anti-Aging Additives in the Formula

Adjust the material formula:The butadiene component in ABS contains unsaturated double bonds, which are prone to oxidation during processing and use, forming chromophores such as conjugated double bonds that lead to yellowing. Therefore, during modification, appropriately increase the addition of additives such as antioxidants and light stabilizers to enhance the material’s oxidation resistance and anti-aging performance, slowing down the yellowing process.