lämpöpaperi

Lämpöpaperi, often translated as thermal paper or heat-sensitive paper, is a special type of paper treated with a dye and a developer that react when exposed to heat. This reaction causes the paper to change color, typically from white or light gray to black or a dark hue.

The primary application of lämpöpaperi is in thermal printers, which are commonly found in point-of-sale systems, such as cash registers and credit card terminals, as well as in fax machines and some label printers. The thermal print head in these devices contains tiny heating elements that selectively heat areas of the lämpöpaperi. When the heated areas reach a specific temperature, the dye and developer interact, creating the printed image or text.

The composition of lämpöpaperi is crucial to its function. It typically consists of a paper substrate coated with a layer containing a leuco dye, a developer, and a sensitizer. The leuco dye is colorless in its solid state but becomes colored upon chemical reaction. The developer, often a weak acid, facilitates this reaction. The sensitizer lowers the melting point of the mixture, allowing the reaction to occur at lower temperatures and with less energy.

While convenient and widely used for its speed and quiet operation, lämpöpaperi has some drawbacks. The printed information can fade over time, especially when exposed to heat, light, or certain chemicals. This makes it less suitable for long-term archival purposes compared to traditional ink-based printing methods.