Four specific kinds of imaging chemical substances are used in thermal paper Roll touchy papers: leuco dyes, developers, sensitizers and stabilizers.
The leuco dyes used in direct thermal paper Rollr are typically triaryl methane phthalide dyes , such as Yamamoto Blue 4450, or fluoran dyes, such as Pergascript Black 2C. A 1/3 extensively used leuco dye is Crystal violet lactone. Red or magenta shade can be finished with dyes such as Yamamoto Red forty Yellow can be produced through the protonation of a triaryl pyridine, such as Copikem Yellow 37. These dyes have a colorless leuco structure when crystalline or when in a pH impartial environment, however emerge as coloured when dissolved in a soften and uncovered to an acidic environment.
Leuco dyes, in general, grant little shade when melted except they are melted in conjunction with one or extra natural acids. Examples of natural acids appropriate for thermochromic papers are phenols such as Bisphenol A (BPA) and Bisphenol S (BPS). Other appropriate acidic substances are sulfonyl ureas such as BTUM and Pergafast 201. Zinc salts of substituted salicylic acids, such as zinc di-tert-butylsalicylate have additionally been commercially used as builders .
A leuco dye and a developer, when melted together, are sufficient to produce color. However, the thermal threshold of the lined layer containing the colorizing aspects is decided by using the lowest melting thing of the layer. Furthermore, builders and leuco dyes regularly combine poorly upon melting. To optimize the colorization temperature and to facilitate mixing, a 1/3 chemical known as a sensitizer is frequently introduced to the imaging layer. Sensitizers are frequently easy ether molecules such as 1,2-bis-(3-methylphenoxy)ethane or 2-benzyloxynapthalene. These two substances soften at about 100°C, which is a realistic decrease restriction for thermal coloration. These lower priced ethers are magnificent low viscosity solvents for leuco dyes and developers, and this helps shade formation at a well-defined temperature and with minimal electricity input.
Dyes in thermally touchy paper are frequently unstable and return to their authentic colorless, crystalline types when saved in warm or humid conditions. To stabilize the metastable glass fashioned by way of the leuco dye, developer and sensitizer, a fourth kind of fabric known as a stabilizer is frequently delivered to thermal paper Roll. Stabilizers regularly share similarities with builders and are frequently complicated multifunctional phenols that inhibit recrystallization of the dye and developer, thereby stabilizing the printed image.