It's important to differentiate between hangers used throughout the processing sequence for sheet film, and devices used to hang film sheets to dry.
The term "hangers" usually refers to stainless steel frames used to hold film sheets through the entire processing sequence - presoak, developer, stop, fixer, wash, etc. Hangers hold film on all four edges and can be used to hold film as it is repeatedly dipped into processing chemicals. Hangers attach rigidly to a rack that cause the hangers (and therefore the film sheets) to remain parallel for processing.
Binder clips are one option to hold processed film for drying. Binder clips attach only to a corner of the sheet, and would not be a wise choice for repeated dipping because there would be no way to force the film to remain parallel, and it is likely that the sheets would touch each other causing either scratches or areas of incomplete processing. Also, conventional binder clips are ordinary steel and are likely to corrode when exposed to processing chemicals.
Binder clips are just one option for hanging film to dry. Other options include clothespins (plastic is better than wood because it won't absorb chemicals), and purpose-made film clips from suppliers such as Patterson or FR.
Or you can use a small hole punch to create a hole in the corner of each sheet, and then hang the sheets from hooks that you permanently install on a rack in your darkroom.
