What are the ingredients in thermal paper coatings?
Thermal coatings are very important in the production of thermal paper, and the chemicals used in thermal coatings are generally composed of more than a dozen kinds in a certain proportion. But each company's heat-sensitive paint formulations are proprietary and vary. Here is a brief introduction to the basic ratio of coatings.
In the formulation of heat sensitive coatings at least:
(1) Leuco dyes, accounting for a few percent, there are many varieties of dyes, and the most commonly used are fluorane compounds. Such as: 3-diethylamino-7-o-chlorobenzene fluorane, etc.
(2) Color developer, accounting for less than 20%, commonly used bisphenol A and paraben. Common color-developing agents include: p-phenylphenol; methylene bis-naphthol salicylate; aromatic sulfonic acids; aromatic sulfides; 2,4-dihydroxybenzoic acid.
(3) Sensitizers, accounting for less than 10%, such as benzenesulfonic acid amide compounds.
(4) Filler, accounting for less than 50%, calcium carbonate (fine particles) is commonly used. Function: Improve the opacity of the paper and improve the contrast between the image and the background color.
(5) Adhesive, below 10%, such as polyvinyl acetate. Function: The coating has good surface strength and printing performance, and 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 a few percent, such as dibenzoyl terephthalate.
(7) Lubricant, accounting for a few percent. It is generally a waxy substance, which can be used to prevent the thermal head from sticking.