Polycarbonate (PC) and PC/ABS resins are common in automotive parts and high-performance electronics, but they're often exposed to high heat during manufacturing. That heat can cause discoloration or degrade the material, which affects the finished product's quality.
What heat does to engineering plastics
High processing temperatures degrade the polymer matrix, which shows up as yellowing or other color shifts, especially in white and light-colored parts. Pigments themselves can lose tinting strength, gloss, or hiding power under heat, and particles that clump or disperse unevenly leave the color inconsistent.
The GEOLOR® ST series
Wooshin Pigment built GEOLOR® ST to address this: a surface-treated titanium dioxide pigment based on high-quality rutile TiO2 made through the chloride process. Its proprietary surface treatment, using Al2O3, SiO2, and organic compounds, optimizes how the pigment particles interact with the polymer matrix at high temperatures. TiO2 content runs above 92%.
GEOLOR® ST holds the color of PC resin steady in sustained high-temperature conditions, keeping the initial whiteness and blue tone intact. It also blends and disperses easily during PC compounding, which keeps color consistent and limits the drop in mechanical properties.
Where it's used
GEOLOR® ST is suited to automotive interiors, electronics housings, and other high-performance parts that go through high-temperature processing, where it helps hold color stability and cut rejection rates.
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