On February 5th, the phthalic anhydride market in Shandong region exhibited a weak consolidation trend. The mainstream negotiated prices for orthoxylene-based phthalic anhydride were between 6,000 and 6,200 yuan per ton, while naphthalene-based phthalic anhydride was quoted between 5,550 and 5,900 yuan per ton. The price of raw material orthoxylene remained stable, whereas industrial naphthalene prices fluctuated downward, leading to a decline in phthalic anhydride production costs. Downstream plasticizer market conditions also experienced a downward fluctuation. Phthalic anhydride production facilities maintained stable operations, with plant operating rates remaining low but steady. The supply of phthalic anhydride tightened, while plasticizer enterprises maintained stable operating loads. The support from rigid demand for phthalic anhydride weakened, indicating a continued weak consolidation trend in the phthalic anhydride market outlook.