Printing of parking tickets and receipts has to be easy, reliable, cheap, material- and energy-efficient. The devices are maintenance-free; only thermal paper has to be refilled.

 

 

1. What is Thermal Paper?

 

 

Bisphenol A (BPA) is used for thermal paper developer because of its stability and heat-resistance. During use of the thermal paper, BPA can get in contact with the skin and during recycling BPA can get into the cycle of paper production and cause contamination of other types of paper products. BPA is considered to be an endocrine disruptor and to cause heart disease, type II diabetes, breast cancer, prostate cancer, infertility, and neurological development disorders.

 

 

2. How is the Color Generated?

 

 

Stabilizers are added to prevent the dyes from returning too easily to an uncolored state. They prevent the dyes from separating from the developers and returning to their ring-closed, colorless form. Polar protic solvents are often used.

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• Wie Thermopapier funktioniert, (in German)
  Isabel Rubner, Albert Jonas, Marco Oetken,
  Nachr. Chem. 2019.
  https://doi.org/10.1002/nadc.20194086861
• Video: How Does Thermal Paper Work?