What is the thermal coating component of color thermal label paper?

The thermal coating components of color thermal label paper mainly contain the following chemical substances, which work together to make the thermal paper show a specific color after heating:

1.Colorless dye (leuco dye) : This is a very key component in the thermal coating, it is itself colorless, but can produce color after a chemical reaction with the color developer. There are many varieties of these dyes, the most commonly used are fluorane compounds, such as 3,3' -diethylamino-6, 7-dichlorofluorane. Different colorless dyes can produce different color effects, such as blue, purple, black and so on.

2.Color developing agent: Color developing agent is another important component in the heat sensitive coating, which chemically reacts with colorless dyes when heated, so that colorless dyes show color. Commonly used color developing agents include p-phenylphenol, methylene dinaphthol salicylate, aromatic sulfonic acid, aromatic sulfide and bisphenol A. The choice and proportion of these color developers will directly affect the final color effect and stability.

3.Sensitizer: The role of the sensitizer in the thermal coating is to improve the sensitivity of the thermal reaction, so that the color change can occur at a lower temperature. Commonly used sensitizers include benzene sulfonamide compounds. The amount of sensitizer added is usually small, but it has a significant effect on the performance of thermal paper.

4.Fillers: Fillers are mainly used to improve the opacity, smoothness and printing performance of paper. Common fillers include inorganic particles such as calcium carbonate. The amount of filler added is large, which can account for a considerable part of the total mass of the thermal sensitive coating.

5.Adhesives: Adhesives play a role in bonding various components together in thermal coatings, while giving the coating a certain surface strength and printing properties. Common adhesives include polymer compounds such as polyvinyl acetate. The addition of moderate amount of adhesive can ensure the stability of the coating and maintain a good printing effect.

6.Stabilizers: Stabilizers are used to improve the color stability and light resistance of thermal paper to prevent the color from changing during a long time of light or storage. Commonly used stabilizers include compounds such as dibenzoyl terephthalate. The addition of stabilizers is small but critical to the long-term performance of thermal paper.

7.Lubricating oil: Lubricating oil is mainly used to prevent the thermal print head from sticking together with the thermal paper during the printing process. Common lubricants include waxy materials. The amount of lubricating oil added is also small but has an important impact on the smoothness of the printing process.

It should be noted that since the formulation of thermal coatings by each manufacturer is a patented product and varies, the above ingredients and their proportions may vary from manufacturer to manufacturer. In addition, with the continuous progress of technology and the improvement of environmental protection requirements, the composition of thermal coatings is also constantly optimized and improved.