造纸板块9月18日跌1.09%，太阳纸业领跌，主力资金净流出1.72亿元

Market Overview - The paper sector experienced a decline of 1.09% on September 18, with Sun Paper leading the drop [1] - The Shanghai Composite Index closed at 3831.66, down 1.15%, while the Shenzhen Component Index closed at 13075.66, down 1.06% [1] Individual Stock Performance - Zhi Xing Paper (002067) saw a significant increase of 9.98%, closing at 7.16, with a trading volume of 294,200 shares and a turnover of 211 million yuan [1] - Qingshan Paper (600103) increased by 6.83%, closing at 4.85, with a trading volume of 7,151,400 shares and a turnover of 3.337 billion yuan [1] - Sun Paper (002078) declined by 3.57%, closing at 14.59, with a trading volume of 282,100 shares and a turnover of 415 million yuan [2] Capital Flow Analysis - The paper sector experienced a net outflow of 172 million yuan from institutional investors, while retail investors saw a net inflow of 145 million yuan [2] - The capital flow for individual stocks indicates that Songyang Resources (603863) had a net inflow of 28.8254 million yuan from institutional investors, while Zhi Xing Paper (002067) had a net outflow of 15.9420 million yuan [3]