Thermal-sensitive coatings are very important in the production of thermal paper. The chemicals used in thermal coatings are generally composed of more than a dozen chemicals in a certain ratio. However, each company's heat-sensitive coating formula is proprietary and different. Here is a brief introduction to the basic paint ratios. In the formula of heat-sensitive paint, there are at least: (1) Colorless dye, accounting for a few percent. There are many varieties of this dye, and the most commonly used one is fluoran compound. Such as: 3-diethylamino-7-o-chlorophenylfluorane, etc. (2) Color developer, accounting for less than 20%. Commonly used ones include bisphenol A and parabens. Common color developers include: p-phenylphenol; salicylic acid methylenebisnaphthol; aromatic sulfonic acid; aromatic sulfide; 2,4-dihydroxybenzoic acid. (3) Sensitizer, accounting for less than 10%, such as benzenesulfonamide compounds. (4) Filler, accounting for less than 50%, commonly used is calcium carbonate (particles). Function: Increase the opacity of the paper and improve the contrast between the image and the background color. (5) Adhesive, less than 10%, such as polyvinyl acetate. Function: The coating has good surface strength and printing performance. The adhesive also forms a colloidal protective film between the dye and the developer to isolate the two to prevent premature reaction. (6) Stabilizer, accounting for several percent, such as diphenyl terephthalate. (7) Lubricant, accounting for several percent. It is generally a waxy substance that can be used to prevent the hot head from sticking to dirt.
To sum up the lubricants in the formula mentioned above, let me add: There are generally two types of lubricants currently used by domestic thermal paper companies. One is emulsion, which mainly relies on imports and has a higher cost. . It can be replaced by the water-based zinc stearate emulsion produced by Guangzhou Zhenghao New Material Technology Co., Ltd., which reduces the cost per ton by about 10,000 yuan. The other is in powder form and needs to be ground. The grinding fineness is difficult to control and is prone to white spots. It can be used in thermal paper with low requirements.