Abstract
Great effort is conducted to reduce emission of carbon dioxide by developing energy-saving technology. Repeated reuse of used paper is effective to reduce emission of carbon dioxide in the field of printing industry for preventing the global warming, because paper is made from wood and the energy consumption of paper making requires great amount of energy. For reuse of paper, we only have to erase optionally the ink or toner on the surface of the paper after using it. Development of erasable ink and/or toner is effective to prevent the global warming with saving energy and wood resource for paper.
