May 20, 2005. /Lesprom Network/. Sonoco (NYSE:SON) will increase prices on uncoated recycled paperboard by $30 to $40 per ton, depending on grade, effective with shipments on June 13, 2005, it was announced today by Marty Pignone, vice president - Paper North America. "We continue to experience rising costs, especially for energy, freight and petroleum-based chemicals. While our continued aggressive productivity and cost reduction initiatives have helped, we cannot continue to absorb these increases," said Pignone.