Self-extinguishing cigarettes

Abstract

This invention concerns the identification of additives and methods of their incorporation as applied to cigarettes, having for its purpose a predictable reduced free burning time. Of those additives disclosed in this specification, boric acid and benzenephosphonic acid are preferred used within a range of 2.5 to 5.5 weight percent based on the weight of the tobacco. Of the methods of incorporation disclosed, including those of direct addition via aqueous and isopropanol solutions of the additives into the tobacco of assembled cigarettes, treatment separately of both the tobacco and the paper housing prior to assembly, and treatment of the paper housing only prior to assembly, that of immersion of the assembled cigarettes into aqueous solutions of the additives for controlled periods of time is preferred. Within a range of 3.+-.1.5 g. boric acid, benzenephosphonic acid, and mixed boric acid-benzenephosphonic acid per 100 ml. aqueous solution, an immersion time of 1 to 4 seconds (as a inverse function of additive concentration) provides an adequate range to meet the varying existing conditions of cigarette sizes and tobacco contents. Using the preferred additives and the preferred method of incorporation, a self-extinguishing time of 1 to 3 minutes can be expected and is considered to meet the objective of this disclosure.

Dependencies are inferred from the claim text.