Injection Molding
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ASA rubber particle orientation blooming
Problem Phenomenon
ASA product surface shows directional patterns and gloss differences, appearance inconsistent between high-speed filling areas and low-speed areas, especially obvious on dark-colored parts.
Cause Analysis
Excessive injection shear makes acrylate rubber particles orient and deform along the flow direction, and the anisotropy of rubber phase distribution appears as surface gloss and texture differences; shear is most severe in the gate area.
Solution
①Adopt moderate injection speed to avoid rubber particle orientation caused by excessive shear (Toray recommendation); ②multi-stage injection with speed reduction in gate area; ③optimize gate form to reduce shear concentration; ④appropriately raise mold temperature to improve surface.
Key Takeaway
The essence of ASA surface blooming is rubber phase orientation; moderate injection speed is an official recommendation rather than conservative; the balance point between high speed and surface quality needs to be determined by mold trial.
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