Before World War II, the main use of fluorine and its compounds was in etching glass. The most important fluorine compound for this was, and is, hydrogen fluoride.
Until WWII, when the development of the atom bomb, and other nuclear energy projects, made it necessary to produce large quantities, there was no commercial production of fluorine.
The element is used to make uranium hexafluoride: ‘Production of uranium hexafluoride’ (note the filing date and publication date); this is needed by the nuclear power industry to separate uranium isotopes: ‘Uranium isotope separation – using liquid hexafluoride’ (1971).
Fluorine is also used to make sulfur hexafluoride, the insulating gas for high-power electricity transformers: ‘Transformer sealed with Sulfur Hexafluoride Gas’ (1980).
Fluorine is used in many fluorochemicals, including solvents and high-temperature plastics, such as Teflon (poly(tetrafluoroethene), PTFE). The invention of PTFE is often wrongly credited to space programmes, but it was invented much earlier: ‘Tetrafluoroethylene polymers’ (1941).
A word of warning for patent searchers; “fluorine” or derivatives, is often misspelled as “flourine” or derivatives. You will have to take account of both spellings in your searches.