How does thermal label paper work?

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

First,Basic structure

Heat-sensitive label paper is generally divided into three layers: the bottom layer is the paper base to provide support; The second layer is the thermal sensitive coating, which is the key layer to achieve the printing effect; The third layer is a protective layer (some thermal paper labels may not have a protective layer), which is designed to protect the thermal layer, resist chemical corrosion, prevent label contamination, and protect the print head.

Second, the working principle

1.Thermal coating components: Thermal coating mainly contains two main components - colorless dye (or dark dye) and color development agent. These two components are in a stable state when not heated and do not show color.

2.Heating process: When the thermal label paper passes through the thermal printer, there are many tiny semiconductor components on the surface of the print head, which heat specific areas of the paper according to the text or graphics that need to be printed.

3.Chemical reaction: At the moment of heating, the colorless dye in the thermal coating reacts chemically with the color developer, causing the color of the local area to change, thereby showing the required text or graphics. This color change is permanent (although it may fade gradually under certain conditions), but is visible immediately after printing is complete.

Third,Influencing factors

1.Uniformity of thermal coating: If the thermal coating is not uniform, it will lead to dark color in some places and light color in some places when printing, thereby reducing the print quality.

2.Chemical formula of heat-sensitive coating: Reasonable chemical formula can extend the storage time of printing paper. Good printing paper can be stored for several years at room temperature, while unreasonable formulations may only be stored for a few months.

3.The role of the protective layer: The protective layer can absorb part of the light that causes the chemical reaction of the thermal coating, slow down the deterioration of the printing paper, and protect the thermal components of the printer from damage. If the protective layer is not uniform or poor quality, it may affect its protective effect and even cause damage to the print head.

Fourth,Application and precautions

Thermal label paper is widely used in supermarket shopping receipts, logistics labels, medical records and other fields because of its advantages of no ink, fast printing speed and low cost. However, because its writing is prone to fading (especially in direct sunlight or high temperatures), it should be used with caution in documents that require long-term storage.

In summary, the working principle of thermal label paper is the process of heating the colorless dye in the thermal coating to react chemically with the color developer to show the text or graphics. This process is influenced by many factors such as the uniformity of the thermal sensitive coating, the chemical formulation, and the quality of the protective layer.