Vinyl flips are made with a chemical stiffener. PVC. Over the long term, this produces gases and acids that will destroy your chips. The colors will fade, run and oxidize. There is a type of vinyl flip that is supposed to be PVC free. But the safest storage container is a 2 1/2 X 2 1/2 white cardboard holder with a mylar window. Of course air-tites are great also.
CHEERS!!!!
Burt