Why is the US anthraquinone market fully dependent on imports, and what role does China play?

Why is the US anthraquinone market fully dependent on imports, and what role does China play?
The US has completely ceased domestic anthraquinone production, relying on imports to meet all domestic demand, with China historically supplying over 80% of US anthraquinone imports. China's total anthraquinone capacity stands at roughly 110,000 t/a, split between 75,000 t/a via synthetic routes and 31,000 t/a via oxidation of anthracene oil. Global anthraquinone demand is estimated at 150,000 t/a, driven primarily by dyestuff intermediates. However, tightening environmental regulations in China are increasingly constraining synthetic anthraquinone production, which relies on phthalic anhydride and benzene feedstocks with higher pollution intensity. As more Chinese coal-tar processors expand anthracene oil deep-processing capacity, oxidation-based anthraquinone is expected to gain share, improving supply economics and reducing environmental compliance costs over the medium term.