Thermal paper is a that is coated with a chemical that changes color when exposed to
heat. It is used in and particularly in inexpensive or lightweight devices such as
machines,registers, and .
The surface of the paper is coated with a mixture of a dye and a suitable matrix; a combination of a
dye and As an example. When the matrix is heated above its melting point,
thedye reacts withthe acid, shifts to itscolored form, and the changed form is then conserved in a metastable
state when the matrix solidifies back quickly enough.
Usually, the coating will turn black when heated, but coatings that turn blue or red are sometimes used. While
an open heatsource, such as a flame, can discolor the paper, a fingernail swiped quickly across the paper will
also generate enough heat from friction to produce a mark on such paper.
Most direct thermal papers require a protective top-coating to:
¡ì reduce fading of the thermal image caused by exposure to UV light, water, oils, grease, lard, fats,
plasticizers, and similar causes
¡ì provide improved printhead wear
¡ì reduce or eliminate residue from the thermal coating on the thermal printheads
¡ì provide better anchorage of flexographic printing inks applied to the thermal paper
(For more info,you can visit )