感熱紙之耐熱性

Heat Fastness of Thermal Paper

感熱紙係於表面塗佈特殊感熱塗料之特種塗佈紙，遇熱部份可呈色。感熱紙塗料之配方及製造均相當複雜。為符合需要，其塗料配方中可含14種以上之化學成份。本試驗以50~70°C溫度之老化條件，評估比較6種市售感熱紙之耐熱性，結果顯示：環境溫度愈高，印刷區及非印刷區之色變情形愈嚴重。市售感熱紙之耐熱性均不佳。此外，本試驗以微量（5~10 g/m2）絕緣材料如：MgCO3, CaSiO3及低融點明膠（gelatin）塗佈於感熱紙表面，以改善其耐熱性。試驗結果顯示，列印感熱紙之耐熱性雖有改善，但效果並不顯著。綜合試驗之結果，可知於感熱紙之表面塗佈微量絕熱材料，可以改善其印刷圖文之熱安定性，便於長期儲存。惟絕熱材料之選擇需十分慎重，除具保護作用外應不影響感熱紙對熱之敏感性為要。 A thermal paper is a special paper coated with a heat sensitive coating. It undergoes a color change (to black) when heated. The thermal paper coming is complex both in its composition and method of manufacture. There can be a combination of up to 14 different chemical components to achieve the desired effect. In aging test (50-70°C), printed images of 6 commercial thermal papers proved less resistant to heat and then faded gradually. In other words, the higher the surrounding temperature was the more color reversion of the printed and non-printed areas occurred. Based on the results observed in this study, we surface treated the coated side of 60 g/m2 thermal papers with small amounts (5-10 g/m2) of heat insulating materials such as MgCO3 and CaSiO3 and a low melting point gelatin. It was found that heat fastness of the printed thermal papers could be improved slightly, however, no marked effects were observed. In conclusion, the problem of image stability of thermal papers might be solved by the application of a top (or barrier) coating. We deduced that this should be a transparent, film-forming layer which when coated onto the surface of the thermal coating, acts as a non-penetrable protective layer, but one which will not impair the heat sensitive characteristics of the main coating.

A thermal paper is a special paper coated with a heat sensitive coating. It undergoes a color change (to black) when heated. The thermal paper coming is complex both in its composition and method of manufacture. There can be a combination of up to 14 different chemical components to achieve the desired effect. In aging test (50-70°C), printed images of 6 commercial thermal papers proved less resistant to heat and then faded gradually. In other words, the higher the surrounding temperature was the more color reversion of the printed and non-printed areas occurred. Based on the results observed in this study, we surface treated the coated side of 60 g/m2 thermal papers with small amounts (5-10 g/m2) of heat insulating materials such as MgCO3 and CaSiO3 and a low melting point gelatin. It was found that heat fastness of the printed thermal papers could be improved slightly, however, no marked effects were observed. In conclusion, the problem of image stability of thermal papers might be solved by the application of a top (or barrier) coating. We deduced that this should be a transparent, film-forming layer which when coated onto the surface of the thermal coating, acts as a non-penetrable protective layer, but one which will not impair the heat sensitive characteristics of the main coating.