Effects of Artificial Thermal Aging on Variations in Color of Commercial Papers

Effects of artificial thermal aging on color variations of various commercial papers (fine paper, coated paper, newsprint and filter paper) were investigated. With thermal aging at 105 o C, most of papers showed a special trend in a * -b * plane: the a * (red-green) values of the samples were initially reduced (heading to a * side) and after a turning point they increased to +a * side while the b * (blue-yellow) values were kept increased to +b * side (yellowing of paper). Different papers had different turning points for a * value. The filter paper consisted of a pure chemical pulp and the copy paper with OBA (optical brightening agent) showed the latest turing points. In addition, the papers without OBA showed less reduction in brightness compared with that with OBA, suggesting that OBA could adversely influence the brightness stability during thermal aging. Keywords: Thermal aging, brightness, optical brightening agent, color differences, CIE L * a * b * 1. 서 론 종이가 제조된 후, 시간의 흐름에 따라 종이의 노화가 발생한다. 종이가 노화됨에 따라 종이의 물리적, 화학적 성질이 어떻게 변화하는지는, 종이의 보존 측면에서 또는 종이를 재생하는 측면에서 여러 연구자들에 의해서 연구되어져 왔다.