US2103698A - Safety ignition composition containing semi-pyrophoric metal - Google Patents

Description

Patented Dec. 28, 1937 UNITED STATES PATENT OFFICE SAFETY IGNITION COMPOSITION CONTAIN- ING SEMI-PYROPHORIC METAL Alfred Schmid, Berlin-Dahlem, Germany 4 Claims.

This forms a continuation-in-part from my copending application Ser. No. 700,147 filed November 28, 1933 which in turn is a division from my application 630,702 filed August 27, 1932. 5 This invention relates to safety ignition mixtures and to their manufacture and has for its main object to provide for a safety ignition mixture, the combustion of which takes place with out flame and without the production of poisonous and bad smelling gases.

The known ignition mixtures used for starting combustion processes generally consist of the following constituents: I

(a) Easily decomposable substances yielding oxygen by decomposition, such as chlorates, nitrates, chromates, peroxides, and the like.

(1)) Substances easily inflammable at low temperatures such as phosphorus, sulphur or compounds of the same.

(0) Additions of hard and chemically inert substances increasing friction, such as quartz, clay, pumice stone and the like.

(d) Binding agents such as glue, starch, gum arabic and the like.

(e) Substances preventing an explosive combustion such as zinc oxide, iron oxide and the like. I

Due to the presence of the substances mentioned under (b) all known ignition mixtures are combusted with flames and evolution of poisonous and evil smelling gases. Their use is therefore impossible in all those cases, where open flames of the evolved gases are dangerous or noxious.

The present invention provides for a safety ignition mixture which may easily be ignited on the usual friction surfaces for safety matches and are combusted without flame and without evolution of noxious or evil smelling gases. Self- 40 ignition of the new ignition mixtures is impossible. The new ignition mixtures are especially suitable as igniting head for cigars, cigarettes and matches, which are safely and efiiciently lighted by mere friction on one of the usual fric- 45 tion surfaces for matches, which surfaces are preferably arranged on or in the packages for the cigars, cigarettes or matches.

According to the invention the phosphorus, sulphur or the like present in the known ignition 50 mixtures is replaced by metals with a sufiiciently low ignition temperature such as magnesium, aluminium, Zinc, cobalt and the like, which on combustion do not furnish volatile combustionproducts but solid oxides in form of a powder.

55 The main feature of the new ignition mixtures is the absence of phosphorus, sulphur or their compounds, the inflammability of the mixture being solely due to the combination of oxygen yielding substances with easily ignitable metals.

The ignition temperature of ordinary metals is too high for the purpose, to serve for ignition mixture. 7

It is known that certain metals such as iron or cobalt may be obtained in the pyrophoric form by reducing at relatively low temperatures suitable compounds of those metals with streaming hydrogen. These pyrophoric metals are, however, ignited and combusted by contact with oxygen or air at room temperature. This pyrophoric form of metals is not suitable for the purpose of the invention and the invention therefore has for its further object, to provide for a method, which enables the manufacture of metals in such a form, that they may be ignited with air at temperatures above atmospheric temperature, preferably above 50 C., but below 300 C. I have named this form of metals, which is -an intermediate form between pyrophoric and normal form, semipyrophoric. This method for making semipyrophoric metals consists in a reduction of metal compounds suitable for the manufacture of pyrophoric metals under such modified reducing conditions that neither the pyrophoric nor the normal form is obtained or in treatment of pyrophoric metal which makes them more difficultly ignitable. The reduction of the metal compounds may be carried out by thermal decomposition in presence of gases free of oxygen or by treatment with hydrogen at raised temperatures. of these treatments must be kept within limits, outside of which pyrophoric or normal metals are obtained. Starting materials for the method according to the invention are inorganic or organic metal compounds such as oxides, nitrates, carbonates, sulfates, oxalates, tartrates or the like. Suitable metals of semi-pyrophoric form are for instance cobalt, nickel, manganese, lead, chrome, molybdenum, tungsten and other metals, selected mainly from groups IV, VI, VII and VIII of the periodic system.

Pyrophoric metals may be converted into semipyrophoric metals by a shorter or longer heat treatment in presence of gases free of oxygen, such as nitrogen, hydrogen and the like or by mixing or combining them with substances, not self-ignitable by contact with air, such as oxides.

In both cases for the manufacture of semipyrophoric metals the duration of the treatment is a function of the temperature. Moreover tem- Temperature and duration 3 perature and duration of the treatment are different for different metals, gases and pressures employed. It is therefore not possible to give general data for temperature and duration of the treatment, but the following example may lead the expert in finding the conditions for making semi-pyrophoric metals other than iron or semi-pyrophoric iron from other starting materials or by a modified method.- I

(1) 10 gr. of ferrous oxalate are heated to about 400 C. in streaming hydrogen, which has been dried by passing it through concentrated sulfuric acid before entering the reaction zone and which passes this zone at a moderate rate corresponding to about two gas bubbles leaving the sulfuric acid per second.

When the amount of gases leaving the reaction zone decrease, which is the case after about one hour, the reaction is finished. The heating is stopped and a rapid cooling is effected by passing hydrogen through the reaction zone. When room temperature has been reached a black powder is obtained not ignitable by contact with air, at room temperature, but ignitable, when contacting it with air at about 180 C.

(2) Nickel oxalate is heated at about 400 C. in streaming hydrogen as long as the entire oxalate is converted into greyish black nickel. After the reaction is finished the nickel oxalate is further heated during twenty minutes in streaming hydrogen. After cooling in streaming hydrogen a soft metal powder remains, which is not ignitable by itself, but slowly glimmering, when heat is supplied.

(3) Cobalt oxalate is heated in streaming hydrogen at temperatures between 380 C. and 400 C. as long as the development of carbonic acid and carbonic oxide is running. Thereupon the cobalt oxalate is heated during about twenty minutes at the same temperature and is cooled in streaming hydrogen. A black metal powder remains not ignitable by contact with air, at room temperature, but glimmering by heat supply from 80 parts of a 4% organic solvents, some ether and alcohol being added to the pappy mixture if necessary. The mixture is placed on the top of a cigar or cigarette in any convenient manner, thus obtaining a firmly adhering ignition head on the article after evaporation of the volatile solvent into the air.

' The igniting mixture described above may contain-other substances, such as fillers and the like, or may be combined with other pyrotechnic mixtures. It may be arranged on any inflammable carrier and thus serve to light any combustible substance.

The solution of collodion employed as binding agent in the above example may be replaced by solutions of other binders, such as acetyl cellulose and the like, in volatile organic solvents, such as alcohol, ether, acetone, amyl acetate and the like. Also aqueous solutions of glue, starch, gum arabic and the like may be employed, although binders containing volatile organic solvents are preferred, as the solidification of the ignition mixtures on. their carriers is accelerated, when the binder contains volatile liquids as solvent. The amount of binder used is kept as low as possible and preferably such binders are employed, which are easily and completely combusted Without the evolution of noxious and bad smelling gases.

I claim:

1. Safety ignition mixture ignitable by friction on friction surfaces, consisting of a mixture of substances yielding oxygen, semi-pyrophoric metals, abrasive substances and binding agents.

2. Safety ignition mixture ignitable by friction on friction surfaces, consisting of a mixture of substances yielding oxygen, semi-pyrophoric metals, abrasive substances and binding agents, said semi-pyrophoric metals being selected from group IV of the periodic system.

3. Safety ignition mixture ignitable by friction on friction surfaces, consisting of a mixture of substances. yielding oxygen, semi-pyrophoric metals, abrasive substances and binding agents, saidsemi-pyrophoric metals being selected from group VI of the periodic system.

4. Safety ignition mixture ignitable by friction on friction surfaces, consisting of a mixture of substances yielding oxygen, semi-pyrophoric metals, abrasive substances and binding agents, said semi-pyrophoric metals being selected from group VIII of the periodic system.

ALFRED SCHMID.

solution of collodion in volatile