TDI、维生素D3价格涨幅居前，建议关注TDI和有机硅板块

Investment Rating - The report maintains a recommendation for the chemical industry, indicating a positive outlook for the sector [7]. Core Insights - The report highlights significant price increases in TDI and Vitamin D3, suggesting a focus on the TDI and organic silicon sectors [1][5]. - The chemical sector outperformed the market, with a weekly increase of 1.77%, surpassing the Shanghai A-share index by 1.08 percentage points [2][15]. - Key stocks that performed well include Dongcai Technology (+33.16%) and Cangzhou Dahua (+28.47%), while stocks like Guangxin Materials (-9.26%) and Ando A (-9.05%) saw declines [2][15]. Industry Performance - In the third week of July, 20 sub-industries within the chemical sector saw increases, with the top five being modified plastics (+7.42%) and phosphate chemicals (+7.41%) [3][19]. - The dynamic PE ratio for the chemical sector is reported at 25.83 times, which is lower than the average PE of 30.02 times since 2015 [2][15]. Price and Spread Trends - The report lists the top five products with the highest weekly price increases: liquid chlorine (+21.78%), TDI (+18.83%), and Vitamin D3 (+10%) [4][22]. - The report also notes significant changes in price spreads, with the ethylene spread increasing by 81.82% and PTA spread decreasing by 357.81% [4][43]. Inventory Changes - Notable inventory changes include an increase in epoxy propane (+11.97%) and a decrease in ethylene (-8.57%) [5][61]. Recommendations - The report suggests monitoring companies such as Cangzhou Dahua and Wanhua Chemical due to the significant rise in TDI prices [5]. - Attention is also drawn to organic silicon producers like Xin'an Chemical and Xinfeng Group, following a fire incident affecting supply [5].