| 摘要 |
642,754. Pyrotechnic compositions. HALL, F. K. KNUTSSON-. Nov. 7, 1947, No. 29764. Convention date, Nov. 13,1946. [Class 9 (ii)] [Also in Group XII] A repeatedly ignitible rod comprises a mixture of a combustible main mass, an oxygen yielding agent and a combustible ignition promoting agent, the combustion temperature of the mixture of the oxygen yielding agent and ignition promoting agent being so related to the evaporative cooling effect capable of being exerted by the main mass that both the oxygen yielding agent and the ignition promoting agent become enriched in the burning portion of the rod. The combustible main mass of the rod is an aldehyde such as metaldehyde mixed or not with cellulose waste. The oxygen yielding agent may be, for example, potassium chlorate. The ignition promoting agent is preferably phthalic acid or one of its derivatives such as phthalic anhydride or a phthalein. Acetanilide or adipic acid may also be used separately, together or in conjunction with salicylic or benzoic acids. To bind these substances, gum, gelatine, synthetic resins &c. with or without a softening agent such as esters of phosphoric acid, are used and the completed rod may be varnished or lacquered. The rod may be struck on a phosphorous containing surface. When the rod is burning the evaporative cooling effect of the metaldehyde keeps the temperature of the lower part of the flame below that required to initiate the reaction between the phthalic acid and the potassium chlorate and these substances therefore become enriched and are thus available to facilitate subsequent ignitions of the rod. Initially the rod must be provided with a match head produced, for example, by burning off the end during manufacture, to make it possible to ignite it for the first time. |
