வெப்ப காகிதத்தின் உற்பத்திக் கொள்கை என்ன?
When the thermal paper is placed in an environment above 70°C, the thermal coating begins to change color. The reason for its discoloration also starts from its composition.
There are two main thermal components in thermal paper coating: one is leuco dye or leuco dye; the other is color developer. This type of thermal paper is also called two-component chemical type thermal recording paper.
Commonly used as leuco dyes are: crystal violet lactone (CVL) of trityl phthalide system, fluoran system, leuco benzoylmethylene blue (BLMB) or spiropyran system and other substances.
Commonly used dispersants are: polyvinyl alcohol L-3266, polyvinyl alcohol GL-05, polyvinyl alcohol KL-03 (produced by Japan Synthetic Chemical).
Commonly used top coat and bottom coat additives are: gohsefimer Z-200, polyvinyl alcohol T-350, polyvinyl alcohol N-300.
Commonly used as color-developing agents are: para-hydroxybenzoic acid and its esters (PHBB, PHB), salicylic acid, 2,4-dihydroxybenzoic acid or aromatic sulfones and other substances.
When the thermal paper is heated, the leuco dye and the developer react chemically to produce color, so when the thermal paper is used to receive signals on a fax machine or print directly with a thermal printer, the graphics and text are displayed. Since there are many varieties of leuco dyes, the color of the handwriting displayed is different, including blue, purple, black and so on.