I assume you have no problem with "embossed". That one is easy
"Noiseless" probably really meant "low noise compared to the other chips available on the market at the time these were being made"
"Unbreakable" is a relative statement because no substance is truly unbreakable. Probably meant that these are not brittle like some clay chips etc. and will bend vs simply snapping or something under extreme pressure.
I have some similar chips. If they are like what I have they are made of a pressed "cardboard" like material. As such they do not make much noise if splashed and as mentioned will bend and not break.