On January 4, the phthalic anhydride market in Shandong region showed an upward trend. The mainstream negotiated prices for phthalic anhydride produced via the ortho-xylene method ranged from 5,800 to 6,000 yuan/ton, while those produced via the naphthalene method ranged from 5,500 to 5,750 yuan/ton. The price of raw material ortho-xylene rose sharply, while the price of industrial naphthalene remained stable. The cost of phthalic anhydride increased, and the downstream plasticizer market experienced a strong upward trend. The operating rates of phthalic anhydride production facilities declined, leading to a decrease in the overall operating rate of phthalic anhydride enterprises. Despite sufficient supply in the phthalic anhydride market, the operating load of plasticizer enterprises increased. The rigid demand for phthalic anhydride remains supportive, and the market outlook is expected to show strong consolidation.