Ball-point instruments writing with improved transitorially erasable trace and ink compositions therefor

摘要

The invention relates to a ball-point writing instrument capable of writing with an intense colored or black line which is easily visible and readable and as permanent and eventually non-erasable as the best customary ball-pen ink traces, but which, in addition, is easily erasable by mechanical means for an initial period of about two to four hours as a normal graphite pencil trace, without the use of bleaches or chemicals. These properties are attained by the provision of a novel ink composition containing stated rubbers and volatile solvents which control erasability.