On January 9, the phthalic anhydride market in Shandong region showed a strong consolidation trend. The mainstream negotiated prices for ortho-xylene-based phthalic anhydride were 5,900–6,150 yuan/ton, while those for naphthalene-based phthalic anhydride were 5,600–5,850 yuan/ton. The price of raw material ortho-xylene fluctuated upward, while industrial naphthalene prices stabilized. The cost of phthalic anhydride increased, and downstream plasticizer market conditions rose strongly. Phthalic anhydride plant equipment operation declined, leading to a decrease in the operating rate of phthalic anhydride enterprises. The supply of phthalic anhydride in the market remained sufficient, and the operating load of plasticizer enterprises decreased. Despite this, rigid demand for phthalic anhydride persisted, and the market outlook is expected to remain strong and stable.