ALEXANDRIA, Va., Dec. 31 -- United States Patent no. 12,509,601, issued on Dec. 30, was assigned to MITSUBISHI PENCIL COMPANY Ltd. (Shinagawa-ku, Japan).
"Aqueous ink composition for writing instruments" was invented by Hisato Haga (Shinagawa-ku, Japan) and Kensuke Inoue (Fujioka, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "An aqueous ink composition for writing instruments containing an aqueous dispersion of colored resin fine particles, the colored resin fine particles containing at least a cyclohexyl (meth)acrylate monomer and a basic dye or an oil-soluble dye, the cyclohexyl (meth)acrylate monomer being contained in an amount of 30 mass % or greater relative to an amount of a polymerizable polym...