thermal paper

=chemistry =suggestion =chemical safety

 

 

You might not want to touch receipts. But that can be hard to avoid.

 

The standard thermal paper used for typical receipts has enough free Bisphenol A that even handling it is somewhat bad. The "BPA-free" thermal paper uses Bisphenol S instead, which is just as bad.

 

Inkjet printers can be used instead. Inkjet receipt printers do exist, and red or black ink for them is cheaper than usual but still somewhat overpriced. However, stores already have thermal printers, inkjet ink is currently more expensive than thermal paper, and ink doesn't dry instantly.

 

The EPA had a project to find alternatives to BPA. Their list of candidates was basically "random things that look like BPA" which meant the whole project was a waste of time.

 

BPA is used in thermal paper because:

- it has a certain acidity

- it has a certain melting point

- it's not too soluble in water

- it's not too volatile

- it's not too expensive

 

Salicylamide is a less biologically problematic chemical that also meets those criteria. It can even be made from phenol and urea over ZnO catalyst.

 


 

 



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