How does thermal label paper work?

The working principle of thermal label paper is mainly based on physical and chemical reactions, the specific process is as follows:

First, basic principles

Thermal label paper, also known as thermal paper, is coated with a special layer of "thermal paint" (thermochromic layer), which is the key to the thermal paper being able to print out text or graphics. This coating mainly contains two components: colorless dye (or leuco dye) and color development agent. At room temperature, colorless dyes are colorless, making thermal paper look indistinguishable from ordinary paper.

Second, the printing process

1.Heating: When the thermal paper is fed into the thermal printer, there are many tiny semiconductor components on the surface of the print head that heat specific areas of the paper according to the text or graphics that need to be printed.

2.Chemical reaction: As the temperature increases, the colorless dye and color developer on the surface of the thermal paper begin to melt into a liquid, and chemical reactions occur. This reaction causes the colorless dye to change into a colored substance that produces text or graphics on the paper.

3.Cooling curing: Once the print head is removed, the heated area cools rapidly, the chemical reaction of the dye and color developer is completed and cured, and the text or figure is preserved for a long time (although fading may occur under certain conditions, as described below).

Third, influencing factors

1.The quality of the thermal coating: the uniformity and chemical formulation of the thermal coating directly affect the print quality and storage time. If the coating is not uniform, it may lead to different shades of color when printing; If the chemical formula is not reasonable, the storage time of the printing paper may be greatly shortened.

2.The role of the protective layer: Some thermal paper also contains a protective layer, located on top of the thermal coating, to protect the thermal layer from chemical corrosion, contamination, and prevent the label from damaging the print head during the printing process. The uniformity of the protective layer is also important, and an uneven protective layer may affect its protective effect on the heat-sensitive coating, and may even fall off and damage the print head.

3.Environmental conditions: Text or graphics printed on thermal paper may be affected by environmental conditions during preservation, such as contact with chemicals, sun exposure or high temperatures, which may cause the dye to return to a colorless state, thus fading the text or graphics.

Fourth, application and precautions

Thermal label paper because of its no need to print consumables, printing speed, low cost advantages, widely used in supermarket shopping receipts, logistics labels, medical records and other fields. However, it is necessary to pay attention to its storage conditions and time limits when using it to avoid fading of text or graphics. At the same time, when selecting thermal label paper, select the appropriate material and specifications according to the specific application scenarios and requirements.

In summary, the working principle of heat-sensitive label paper is to show text or graphics by heating the colorless dye on the surface of the paper and chemical reaction with the color developer. This process is affected by many factors such as the quality of the thermal sensitive coating, the action of the protective layer and environmental conditions.