The thermal paper,based on the base paper or film,is coating by the chromogenic layer on it, and sometimes there will be pre-coating and top coating in order to obtain an excellent printing clarity and various protective properties. The chromogenic layer is mainly composed of adhesives, chromogenic agents, colorless dyes (latent dyes) and sensitizers.
When the thermal paper meets the high temperature condition, or was heat by using the heating element, the chemical reaction will be happened between the chromogenic agent and the colorless dye to display the image. And the preinstall image could be imaged on the thermal paper by using the thermal printing terminal equipment.