US 3467558 A
Description (OCR text may contain errors)
United States Patent O 3,467,558 PYROTECHNIC DISSEMINATING COMPOSITION CONTAINING AN AGENT TO BE DISSEMI- NATED Gary E. Wernette, Weidman, and Erwin M. Jankowiak,
Midland, Mich., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Filed Sept. 1, 1967, Ser. No. 664,919 Int. Cl. C06d 3/00; C06b; A01n 17/04 US. Cl. 149-19 6 Claims ABSTRACT OF THE DISCLOSURE A pyrotechnic disseminating formulation comprising an inorganic oxidizer which readily is combustible at atmospheric pressure, an epoxy resin binder as fuel and an effective quantity of an agent to be disseminated.
BACKGROUND OF THE INVENTION This invention relates to pyrotechnic dissemination and more particularly is concerned with a novel system for the thermal dissemination of chemical agents.
Pyrotechnic disseminating formulations are Widely employed for colored smoke production used as a signal or screen, for the distribution of plant growth regulating agents such as pesticides, fumigants, herbicides and the like and for the release and distribution of chemicals used in warfare and law enforcement such as tear gas, psychotomimetic incapacitating agents and the like.
The primary problem in disseminating such signalling and treating materials, hereinafter referred to as agents, by pyrotechnic means is in providing a combustible mixture evolving large quantities of gaseous combustion products which burn at a sufficiently low temperature such that the agent being disseminated is not detrimentally degraded or destroyed. In general, such compositions should provide large volumes of gaseous combustion products while undergoing complete burning at a low burning pressure, e.g. a maximum of about two atmospheres, and a maximum burning temperature of about 800 C. and preferably from about 300 to about 600 C. It is another criterion of operation that the agent to be disseminated must be compatible with the pyrotechnic composition to assure reliability of burning after storage as well as storage-ability without mix degradation.
Heretofore, pyrotechnic dissemination of smoke dyes, herbicides, chemical warfare materials, tear gas and other like agents has been carried out using compositions wherein substantial amounts of the agent to be disseminated are mixed with cool burning fuel-oxidizer combinations which provide copious quantities of water vapor and carbon dioxide as the principal gaseous exhaust products. In these formulations, many times undesirable high percentages of the agent are lost through degradation during the combustion dissemination process.
Empirically, it has been found that a mixture of carbohydrates or sulfur with potassium chlorate in the presence of minor amounts of certain additives, e.g. sodium bicarbonate with sulfur or kaolin with sugar, can be used as a pyrotechnic system for dissemination of colored smoke and chemical warfare agents. These systems can be classified as cool burning only because of the flame quenching additives employed therein. Polyvinyl acetate in dilute solutions has been used with these conventional pyrotechnic compositions to increase their physical strength and ease of consolidation. Such solutions reduce the amount of pressure needed to compact the formulation into a grain." This is of interest especially with those formulations containing sulfur as compaction of such formulations at high pressure is hazardous in that these compositions during fabrication are prone to ignition. Even when partially compacted, the resulting defiagration borders on detonation with respect to velocity. Oil, as a diluent, has been used to moisten and reduce friction sensitivity in such mixtures. This material, however, undesirably degrades the composition from the standpoint of efficiency of dissemination.
Dissemination of agents of the type set forth herein also has been realized using pyrochemical gas producers as the high volume gas source. To illustrate, self-sustained gas producing reactions as realized by the relatively low temperature catalytic decomposition of ammonium nitrate, guanidine nitrate and nitroguanidine utilizing chromates and dichromates as catalysts have been used to disperse benzene hexachloride, DDT and other pesticides. These formulations suffer from the disadvantage that they exhibit relatively low efliciency of dissemination and are not universally applicable.
As indicated hereinbefore, conventional munitions used for the thermal dissemination of various agents generally consist of dry powders which are intimately mixed and compacted into grains under high pressure using expensive, slow processes and equipment. Such fabrication techniques are hazardous in that the dry powders are susceptible to shock and friction. Further, with a number of the agents, particularly the tear gas and psychotomimet ic incapacitating agents, the dust associated with the manufacture in itself is toxic or at least a temporary health hazard or inconvenience to operators. Additionally, such pressed, dry grains are porous and have an undesirable low density.
It is a principal object of the present invention to provide a novel pyrotechnic composition for thermal dissemination of chemical agents.
It is also an object of the present invention to provide a pyrotechnic formulation which is safe to handle during mixing and other production operations when in admix ture with an agent to be disseminated.
It is a further object of the present invention to provide a pyrotechnic formulation containing a smoke dye chemical agent to be disseminated which exhibits compatibility during mixing and curing and wherein the resultant composition remains stable under prolonged storage even at relatively elevated temperatures of 70 C. or more and which gives high efliciences of gaseous combustion production and agent dissemination upon use.
It is also an object of the present invention to provide a cool-burning pyrotechnic composition for dissemination of agents which requires no coolant additives.
It is a further-object of the present invention to provide munitions for the thermal dissemination of agents which have a high density, good structural integrity and are substantially pore free.
It is another object of the present invention to provide a novel thermal disseminating system which before curing is readily castable or easily extrudable without requiring high forming pressures.
These and other objects and advantages readily will become apparent from the detailed description of the invention presented hereinafter.
SUMMARY The present invention comprises a pyrotechnic disseminating formulation employing inorganic oxidizers which readily are combustible at atmospheric pressure, liquid epoxy based resins with an organic amine curing agent as binder-fuel, and effective quantities of a chemical agent to be disseminated.
More particularly the present invention comprises from about 25 to about 35 weight percent of an alkali metal or ammonium nitrate, -chlorate, -perchlorate or mixtures thereof as oxidizer, from about 20 to about 40 weight percent cured epoxy resin binder-fuel and balance agent to be disseminated.
By effective quantities of an agent to be disseminated is meant those amounts whereby a predetermined level of treatment or activity is realized as is understood by one skilled in the art of pyrotechnic dissemination.
The fluid formulations readily can be fabricated into compacts or grains using casting procedures and low pressure extrusion techniques. Blends usually are made by mixing the components, placing as by casting, for example, the resulting substantially homogeneous mix into a container and curing the so-formed mass into a grain. Ignition of the grain is achieved by contacting the formulation with an ignition system and igniter as conventionally employed in thermal disseminating munitions.
Both end burning and internal burning grains can be fabricated using the present novel system.
A principal advantage of the present formulation is that after blending and before curing the mixture is a wet flowable mass which is readily processed and handled in casting and extrusion forming procedures. Further the solid and liquid mix components are bound and/or cemented together into a strong cohesive or adhesive grain upon curing. An additional advantage is that the cured binder resin itself serves as a cool burning fuel which in conjunction with the oxygen of the oxidizer burns at a desirable low temperature and controlled burning rate to give satisfactory agent dissemination and return, e.g. smoke color, in terms of efliciency and yield.
DESCRIPTION OF PREFERRED EMBODIMENTS A preferred embodiment of the present invention comprises about 30 weight percent potassium chlorate oxidizer, about 30 weight percent of an epoxy resin-amine curing agent binder-fuel system and about 40 weight percent of an agent to be disseminated.
This composition has been found to be particularly effective in the fabrication of a munition wherein a red smoke dye, e.g. l-methyl'aminoanthraquinone (hereinafter referred to as MAAQ) or l-methylaiminoanthraquinone blended with about 15 weight percent dextrin as a flowing agent (hereinafter referred to as MAAQ-D) is the chemical agent to be disseminated. With the present formulation, castability, mix stability, and compatability, log term storageability and good yields and elficiencies of agent dissemination with cool burning temperature are realized.
In the preferred embodiment usually the binder-fuel is comprised of a fluid aromatic disulfide containing epoxy resin or an epoxy-polysulfide copolylmer resin system employing benzyldimethyl amine, triethylenetetramine, diethylenetriamine, tris(dimethylaminomethylphenol) and the like amines as a curing agent. The quantities of the amine curing agent to epoxy resin to be employed are greater than those conventionally employed in resin curing operations. The quantities of curing agent used range from about 15.5 to about 50 parts or more per hunderd parts of resin and preferably from about 25 to about 50 parts per hundred parts of resin. These large quantities of curing agent have been found to promote wetness and fluidity in the original blend as well as any curability and smoke dissemination upon combustion of the cured grain.
Liquid epoxy resins which contain sulfide groupings, e.g. aromatic disulfide containing diglycidyl ethers or such ethers which have been copolymerized with liquid low molecular weight polysulfide resins have been found to give the optimum in castability, efficiency of combustion and agent dissemination. However, other liquid non-sulfur containing epoxy resins, e.g. aliphatic glycerine glycidyl ethers also can be employed in conjunction with the liquid sulfide containing resins. The liquid polysulfide polymers serve to reduce the viscosity of the binder blend during mixing and casting operations. Generally, if used, the polysulfide polymer is included up to a maximum of about 10 percent, preferably up to a maximum of about 5 percent, of the total formulation weight.
A particularly effective binder-fuel system has been prepared using a copolymer of from about 12 to about 14 weight percent of an aromatic disulfide containing epoxy resin in combination with from about 2 to about 4 weight percent of glycerine glycidyl ether, from about 2 to about 4 weight percent of a liquid low molecular polysulfide polymer produced by the chemical reaction between dichlorodiethylformal and an alkali polysulfide and having from about 9 to 'about 11 weight percent benzyldimethylamine as curing agent.
Additional viscosity reducing agents as conventionally employed can be incorporated into the mix if desired.
In the actual preparation of a munition utilizing the composition of the present invention, the liquid components of the formulation usually first are mixed followed by addition of the chemical agent. Ordinarily, the chemical agent is added slowly while continuing the mixing operation. After thorough dispersion of the chemical agent in the liquid mixture of binder components, the oxidizer is added with stirring and the final mixture agitated until homogeneity and castability are achieved. Alternatively, if desired, the solid and liquid components can be introduced together into a blender. The actual mixing operation is carried out over a temperature of from about room temperature up to about 35 C. and usually about room temperature.
The blended composition usually is cast into a mold of predetermined configuration or extruded and maintained at a predetermined temperature to effect curing. The actual cure temperature employed ranges from about room temperature to about C. and preferably at from about 40 to about 70 C. The time of cure ranges from several minutes to 48 hours or more.
The following examples will serve to illustrate the present invention but are not meant to limit it thereto.
Example 1 About 12.9 parts by weight of an aromatic disulfide diglycidyl ether, 3.5 parts by weight of a glycerine glycidyl ether, 3.5 parts by weight of Thiokol Liquid Polymer LP-3 polysulfide polymer and 10.1 parts by weight of benzyldimethylamine were mixed until homogeneous. About 30 parts by weight KClO and 40 parts by weight of MAAQ-D red dye were added with stirring and the mix agitated until a visually homogeneous blend was obtained. The entire mixing operation was carried out at room temperature, i.e. -20 C.
The resulting fluid mix was cast into 300 gram endburning munition grains in cylindrical molds and cured at about 70 C. for one hour.
The resulting grains were rubber-like in appearance. Sectioning of a sample indicated the grain to be substantially pore-free. Also the solid particles were found to be strongly bonded to and encased by the binder.
Combustion studies were carried out on the grains. These indicated a burning time of about 60-65 seconds/inch. The combustion product temperature was about 440 C. with large volumes of a deep red colored smoke being produced. The percent of agent dissemination efficiency was 77.5%; percent yield was 26.2% and residual slag was 17.0%. The sensitivity to deflagration by impact was greater than 300 kilograms cm.
Samples of the grains were stored under normal atmospheric conditions and the chemical and physical stability as determined from combustion characteristics measured at periodic intervals. Table I summarizes the results of these combustion tests.
For purposes of comparison a standard 300 gram M18 pressed smoke grenade as presently used by the armed forces for red smoke dissemination was tested. This pressed grain had a burning time of about 70-74 seconds/inch. The color of smoke, smoke volume and combustion pressure were substantially identical with that of the munition of the present invention.
Example 2 A number of formulations wherein binder-fuel components were varied were prepared following the procedure described in Example 1. In each grain, the MAAQ-D dye level was about 40 percent and KClO oxidizer was about 30% of the total weight of the formulation. These mixes as blended all were fluid and castable. They cured into rubbery, substantially void-free grains. Table II summarizes the binder composition and combustion performance for a number of cured munition grains.
TABLE II (c) an agent selected from the group consisting of smoke-producing agents, pesticides, fumigants, herbicides, tear gas, and psychotomimetic incapacitating agents.
2. The formulation as defined in claim 1 and comprising from about 25 to about 35 weight percent potassium chlorate oxidizer, from about 20 to about 40 weight percent of an epoxy resin-amine curing agent binder-fuel system, and from about 45 to about 55 weight percent agent to be disseminated.
3. The formulation as defined in claim 2 wherein the binder-fuel comprises a fluid aromatic disulfide containing epoxy resin and benzyldimethylamine as curing agent, the amount of said curing agent ranging from about 15.5 to about 50 parts per hundred parts by weight of said resin.
4. The formulation as defined in claim 2 wherein up to a maximum of about 10 weight percent of the binderfuel component, based on total formulation weight consists of a liquid low molecular weight polymeric sulfide.
5. The formulation as defined in claim 2 wherein the agent is 1-methylaminoanthraquinone.
6. The formulation as defined in claim 2 and comprising about weight percent potassium chlorate, about 30 weight percent of a binder-fuel which on the total formulation weight consists of from about 12 to about 14 percent aromatic disulfide containing epoxy resin,
Binder Composition (Percent of total formulation) Combustion Results l Aromatic disulfide diglycidyl ether.
1 Thiokol liquid LP-3 polysulfide resin.
I Glyeerine glycidyl ethers.
Various modifications can be made in the present invention without departing from the spirit or scope thereof for it is understood that we limit ourselves as defined in the appended claims.
1. A pyrotechnic disseminating formulation compris- 8;
(a) from about 25 to about weight percent of a member selected from the group consisting of alkali metalor ammonium nitrates, -chlorates, -perchlorates or mixtures thereof as oxidizer,
(b) from about 20 to about weight percent of a non-halogenated epoxy based resin cured with an amine as binder-fuel, wherein the epoxy resin is selected from the group consisting of aromatic disulfide-containing diglycidyl ethers and copolymers thereof with liquid low molecular weight polysulfide resins, and copolymers of aliphatic glycerine glycidyl ethers with liquid low molecular weight polysulfide resins, and
References Cited UNITED STATES PATENTS 3,042,580 7/1962. Jacobi et al. l4961 X 3,130,096 4/1964 Pruitt et al. 14960 X 3,335,049 8/1967 Niles 14983 X CARL D. QUARFORTH, Primary Examiner S. J. LECHERT, Assistant Examiner US. Cl. X.R.