On January 29, the price trend of phthalic anhydride in East China fluctuated and consolidated. The mainstream quotation for ortho-xylene-based phthalic anhydride in the market ranged from 6,100 to 6,300 yuan per ton, while the price of naphthalene-based phthalic anhydride ranged from 5,800 to 6,100 yuan per ton. The price of industrial naphthalene fluctuated and stabilized, and the price of ortho-xylene also stabilized, leading to stable production costs for phthalic anhydride. Downstream, the plasticizer market experienced fluctuating price increases. Plasticizer manufacturers maintained low but stable equipment operating rates, with downstream demand driven by rigid procurement needs. Phthalic anhydride was primarily purchased based on demand, and demand support for phthalic anhydride remained. Phthalic anhydride manufacturers maintained stable equipment operating rates, ensuring sufficient supply. Phthalic anhydride inventories were low. It is expected that the phthalic anhydride market will continue to fluctuate and consolidate in the near future.