US2487906A

US2487906A - Ignition composition

Info

Publication number: US2487906A
Application number: US682155A
Authority: US
Inventors: William D Trevorrow
Original assignee: Atlas Powder Co
Current assignee: Atlas Powder Co
Priority date: 1946-07-08
Filing date: 1946-07-08
Publication date: 1949-11-15
Anticipated expiration: 1966-11-15

Description

Patented Nov. 15, 1949 STATES orrice 6 Claims.

'Thepresent invention relates tobcmp'csitions of matter for the preparation of ignition devices.

An object of the present invention is the provision of a composition of matter of the type specified which does not tend to jell.

Another ob ect of the invention is the provision of a composition of matter of the type specified which has desirable viscosity characteristics.

other ob'jects orthe invention will be apparent from the following description:

Ignition-devices are customarily prepared by surrounding hea'table elements such as an electric bridge wire with a coating composition carrying a heat-sensitive ignition compound.

One'conunon type 'ofigniteris-the bridge plug type u'S'ed -in" some forms of'elec'tric detonators. A bridge plug comprises a plug of material separating two leg wires connected together by a fine, high resistance, bridge wire. A coating composition, admixed with an ignition compound, is spread around the bridge wire. The spreading operation is called buttering because of the viscous consistency of the composition containing the ignition compound. The buttered material dries hard on evaporation of the solvent, and subsequent heating of the bridge wire as by passage of an electric current fires the ignition material with the production of a burst of flame.

Another form of igniter, also commonly used in detonators, is the electric match which is composed of two insulated metal plates or foils connected together by a bridge wire and dipped in a coating composition containing an ignition compound. The dipping operation forms, around the bridge wire, a drop of ignition material which hardens on drying. Electric matches also may be fired by passage of an electric current through the bridge wire.

While many difierent materials are used for ignition compounds, lead salts of nitrophenols have been found particularly desirable in many instances. Examples of lead nitrophenols which are particularly useful in accordance with the present invention are lead styphnate, monobasic lead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate, lead nitrato-bis-basic-lead 4:6 dinitro-orthocresylate, normal lead 2 nitro-resorcinate and monobasic lead 2 nitro-resorcinate.

The coating composition which is used to carry the ignition compound is usually of the lacquer type composed of a highly combustible nitrocarbohydrate such as nitrostarch or nitrocellulose and a volatile solvent such as esters of the type of butyl acetate and amyl acetate, aromatic hydrocarb'ons such as'benz'ene, and the like. De pending -on the viscosity or volatility characteris tics=desired, d'ififerent' solvents or mixtures of solvents a're used as is well understood in the art.

A difiiculty which has been found to occur wheii' lead salts of nitroph'enols are used in lacquer'sdfthis type'has been that the composition tends to setup into a' gel prior to use, andin'a gelfo'rm it" is diflicult-to apply. According to'tlie present invention, it has been discovered that compositions of'the present type do? not: exhibit this gelling phenomenon when acetone or acetonyl acetone are-includedin thein. Either or both of these-materials has been found to be successful.

Acetonyl acetone is usually somewhat to be preferred; particularly when the compositions are to be used for operations of the buttering type. When buttering mixtures are prepared, it is customary to originally prepare them in thin form and then to evaporate them to the desired viscous consistency which makes for easy buttering. When acetone is used in such mixtures it sometimes volatilizes away before the composition is thick enough for use. Acetonyl acetone does not show this disadvantage.

When the compositions can be used in less viscous form, as for dipping, acetone is found to be entirely satisfactory.

While acetone and acetonyl acetone may be used as sole solvents, it is usually preferred that they be used in proportions of from about 1 to about 20% by volume based on the total volume of the composition excluding ignition compounds.

The following example is illustrative of a specific embodiment of the invention:

A lacquer was made up by adding 2.4% by weight of nitrostarch to a solvent which was composed of 95% butyl acetate and 5% benzene. 180 cc. of this lacquer were mixed with 200 grams of lead styphnate and 20 cc. of acetonyl acetone. This mixture was partially dried until it became viscous and then was buttered on to the bridge wires of bridge plugs. At no time did the composition exhibit any jelling tendency and it buttered readily. After drying, the igniters produced were found to be entirely satisfactory.

A composition particularly suitable for the preparation of match heads may be made by using a lacquer composed of nitrocotton dissolved in amyl acetate and by substituting acetone for acetonyl acetone. As is well understood in the art, it is usually desirable to protect match heads by dips of protective coating. A first protective dip of a 6 oz. ether alcohol nitrocotton lacquer, and

about 1 to about 20% by volume of the composi- I tion exclusive of ignition compound.

2. A composition of matter comprising nitrocotton, a volatile solvent therefor, an anti-gelling agent selected from the class consisting of acetone and acetonyl acetone, and an ignition compound selected from the group consisting of lead styphnate, monobasic lead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate, lead nitrato-bis-basic-lead 4:6 dinitro-ortho-cresylate, normal lead 2 nitroresorcinate and monobasic lead 2 nitro-resorcinate, said anti-gelling agent comprising from about 1 to about 20% by volume of the composition exclusive of ignition compound.

3. A composition of matter comprising lead styphnate, butyl acetate, benzene, acetonyl acetone, and nitrostarch.

'4. A composition of matter comprising a nitrocarbohydrate in solution, acetonyl acetone as an anti-gelling agent and an ignition compound selected from the group consisting of lead styphnate, monobasic lead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate, lead nitrato-bis-basic-lead 4:6 dinitro-ortho-cresylate, normal lead 2 nitroresorcinate and monobasic lead 2 nitro-resorcinate, said anti-gelling agent comprising from about 1 to about 20% by volume of the composition exclusive of ignition compound.

5; A composition of matter comprising a combustible nitrocarbohydrate, a volatile solvent therefor, an anti-gelling agent selected from the class consisting of acetone and acetonyl acetone, and an ignition compound selected from the group consisting of lead styphnate, monobasic lead 4:6 dinitro-ortho-cresylate, monobasic lead picramate, monobasic lead 3:5 dinitro-benzoate, lead nitrato-bis-basic-lead 4:6 dinitro-orthocresylate, normal lead 2 nitro-resorcinate and monobasic lead 2 nitro-resorcinate, said antigelling agent comprising from about 1 to about 20% by volume of the composition exclusive of ignition compound.

6. A composition of matter according to claim 5 in which said anti-gelling agent is acetonyl acetone.

WILLIAM D. TREVORROW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,045,012 Flurscheim Nov. 19, 1912 1,964,077 Piccard June 26, 1934 2,159,229 Rubenstein May 23, 1939