An immediate improvement filed by Seth Wheeler, which was granted on December 22, 1891, as patent number US465588A. In Wheeler's improved patent for toilet paper he described the idea of perforated toilet paper on a roll.
The five primary requirements for patentability are: (1) patentable subject matter; (2) utility; (3) novelty; (4) non-obviousness; and (5) enablement. Like trademarks, patents are territorial, meaning they are enforceable in a specific geographic area.
Utility patent application: may be filed by anyone who invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof.
I would suggest you file a Provisional Patent Application (PPA) on your own for about $60 with the US Patent Office. Once you have filed the PPA (which is never examined and isn't a real patent), you have 1 year to claim ``patent pending'' before you must file your utility patent (maybe $5000 or more).