US2744816A

US2744816A - Solid gas-generating charges

Info

Publication number: US2744816A
Application number: US373498A
Authority: US
Inventors: Alexander Cantlay Hutchison
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1947-10-10
Filing date: 1953-08-11
Publication date: 1956-05-08
Anticipated expiration: 1973-05-08
Also published as: DE909424C; ES184896A1; FR970531A; GB644073A; CH277311A; AT171721B

Description

INVENToR N 0 .b H c T U H M L T N A C R E D m L A A. C. HUTCHISON SOLID GAS-GENERATING CHARGES Filed Aug. ll, 1953 May 8, 1956 SOLID GAS-GENERATING CHARGES Application August 11, 1953, Serial No. 373,498

Claims priority, application Great Britain October 10, 1947 23 Claims. (Cl. 52-.5)

'Irhis v.invention relates to improvements in solid gasgeneratng charges. More particularly, it relates to charges of the relatively slow-burning kind capable of propagating through themselves a self-sustaining exothermic non-detonating gas-evolving decomposition when a merely local portion of the charge is heated from room temperature to the temperature at which its active decomposition begins. Such gas-generating charges have found application heretofore for a variety of purposes including, for instance, the actuation of gas pressure operated mechanical devices, safety (flameless) blasting operations, the dispersion of volatilizable pesticides, in. sect repellants and rodenticides, propulsion of-rockets and the expulsion of liquids from containers such vas lire extinguishers. y

In accordance with the present invention, gas-generating charge compositions of the foregoing general type and scope of utility are provided which, however, are characterized and distinguished essentially by the fact that they consist in major part of guanidine nitrate, together with a polynitro-phenol or a polynitroso-phenol United States atent g Cil 2,744,816 Patented lMay 8,

by there may be obtained, if desired, `charges capable of self-sustained decomposition even at.atmosphericJ pres-y sure when locally heated. Y, l Owing tothe nature or amount of the -residuethe hy-J pophosphites leave behind or because of .otherfdisadvantages attendant on their employment, these'` previous-f ly proposed charges have only a limited applicability. Hence it would be desirable to provide improvedfgas-generating charges based on guanidine nitrate and caplzlble of self-sustained'decomposition under conditions ofrnuch lower gas pressure than guanidinei nitrate alone. It is also Aknown that the pressure required to render possible the self-sustained decomposition of a, charge based on guanidine nitrate may be progressivelynrfeduced by making up the guanidine nitrate vinto chargesfwith progressively increasing amounts of colloided,nitrocellulosenas a binding agent, by mixing the guanidine nitrate with a solution of nitrocellulose in a vvolatileI solvent, formingthe resulting paste into the required shape and evaporating oft the volatile solvent. However, the. 'use' of a volatile solvent adds to the expense and necessitates' a drying operation, while the applicability of this method is also somewhat limited. `l

I have, now found that non-explosive gas-generating charges based on guanidine nitrate, suitable for' a Vvariety of purposes and free from the disadvantages attendant 'on in proportion which may vary considerably but is always much less than one-half that of the guanidine nitrate'component. The charge compositions of the invention are non-explosive and are not capable of being detonated by a blasting cap or other form of commercial detonator. Accordingly, they are to be sharply distinguished from compositions such, for example, as smokeless powders, and conventional blasting compositions which are essentially detonating explosives having a base of nitrocellulose, of nitrocellulose and nitrol glycerin, or of oxidizing salts, but which may sometimes include guanidine nitrate as an incidental component.

It is known that guanidine nitrate undergoes an exothermic gas-evolving decomposition when it is strongly heated, but under atmospheric pressure conditions the reaction does not sustain itself if a portion only of a quantityof the compound is heated from atmospheric temperature to the temperature at which decomposition begins, unless external heating is maintained. The decomposition leads Vto the production of steam, nitrogen, ammonia and oxides of carbon, but there is also formed a certain amount of a ditlicultly fusible yellow nitrogenous organic residue.

When the conditions are such that the prevailing gas pressurek is suciently high, namely of the order of 70 atmospheres, once the reaction has been locally initiated it will sustain itself throughout a mass of the guanidine nitrate, and under such gas pressure conditions the products are almost wholly gases and vapors.

It has been proposed to provide mixtures containing guanidine nitrate charges that are capable of decomposing with a high yield of permanent gases when lockallyj heated by a non-detonating element at a lower pressure than-is required for guanidine nitrate alone, said mixtures comprising guanidine nitrate with a proportion of a metallic hypophosphite or ammonium hypophosphite wherethe use of hypophosphites or gelatinized nitrocellul o se,v andcapable of self-sustained non -detonating decoufllpQ'S'if tion when merely locally heated,"with 'a 'high yield yof hot gases at relatively low pressure,v considerablylower than"l the 70Y atmospheres required for guanidine nitratealone, may be obtained by the use in'admixture with guanidine nitrate of a `polynitro-phenol or va p olynitroso-phenol," i.`e. a phenol which contains in addition to at'leas "on i phenol hydroxyl group a plurality ofg'subs'titunt'groups each consisting of a nitrogen atomkattachedexclusivly to 'at least one terminal oxygen atom v'and' to one ofthe" nuclear carbon atoms of the phenol. While no cointnit' ment is here intended as to the mechanism of the'acti'oii or reaction whereby thermal `decomposition ofthe guai nidine nitrate at atmospheric or relatively low superat-l mospheric pressures is facilitated by the Iadmixed polynitro-phenol or polynitroso-phenol, such a'dmixed c'o'rtlj-l pound is conveniently referred to as a" sensitizer `foi' such thermal decomposition. The sensitizing action of the' particular class of compounds employed for this purpose in the present invention is not general but'appears' to be speciic to guanidine nitrate. Thus, contrary tof'what might be expected from their action on guanidine r'iiti'ate,"L

it has been found that a compound of this class ha'ss'uba'. stantially no heat-sensitizing action on nitro-guanidine",4v

for example. Incidentally, it is to be noted that nitro'- guanidine is an explosive, whereas guanidine nitrate is not.' Among the many polynitroand polynitrosoderiva# tives of phenol that can be employed as thermal decomposition sensitizers in practicing the present invention, the following may be mentioned by way of example:f2':`4 dinitro-resorcinol, 2:4:6 trinitro-resorcinol, 2:4 dinitroso'- resorcinol, 4:6 dinitro-ortho-cresol, 3&5 'dinitro-catechol, 2:6'dinitro-paracresol, and 3:5 dinitro-salicylic acidu'Of these, 2:4 dinitro-resorcinol works particularly-*well and is presently regarded as most desirable. y'

- With regard to the proportion of polynitro-phenol for polynitroso-phenol sensitizer to be employedin the novel charges of the invention, this may varywidely depending upon such factors as the specic purpose and consequently the specific nature of the charge composition, and the conditions (particularly the pressure) under whichy the relatively slow, gas-generating thermal decomposition' is' intended to take place. The limiting considerations are (1) that enough sensitizer must be employed fto'e'nsure' and y(2) that the proportionmust not be so'y high Vas to render such decomposition explosive or detonating in character.

`'lf'hus," assumingthe charge composition not to include what can properly'be termed a ,di1uent,. i. e.,an. ingredient whichmerely absorbs heat suppliedbyrthe' aforesaid self-sustaining exothermic decomposition, and further assuming'that they decomposiition, once' it.- is' initiated by Iocaliedheating'fof'the charge, is to be self-sustaining under 'relativelylow Working pressures; e. g.y from superatmospheric pressures around l"atr`nospheres down even toordinai'y .atmosphericpressura a propottionof the aforesaid sensitiz'er .ranging .from about '.8fto` about 20 percent of'the weight ofthe g'uanidine nitrat'eordinarily sum es to renderthe composition .capable of self-.sustainedv dee mpositionfthe proportion being 'permissibly less as theiite'ndedworkingpressure increases.

`Whre` the-lwrking'pressure. conditions contemplated for self-sustained',.nn-detonating;exothermic decomposition ffthe" chargei are of. anA order of. magnitude higher vthan abo t`f101A afrnfospheres,y again assumingsubstantial ofdiluent wheat-absorbing.ingredients,:the,pro of lthe polynitro-phenol or polynitroso-phenol snsti'zerfcomponent.mayof course be reduced below. the In somerfinstances, `it may even be. as low asper cent. of the weight of the guanidine n t although .for optimum performance it is seldom deslrable.,that.less,than about. 5 percent of. saidweight beemnlcyfd,

" VOri vtherhand, .Where 4the charge. .does include Y with advantage to replace a portion of the phenol derivative sensitizer. -But since these-carboxylic -acids are-less powerful sensitizers than thes-phenal derivatives aforesaid, it is not desirable to carry such replacement so far that the gas-generating decomposition rate of the charge composition may become too fslovv;V In general, it may be taken that one part ofdinitroresorcinol (e. lg.)is.equiva lent, in so far as it can be equivalent, to two parts of tartaric.acid...(e. gf.). ciously employed, the aliphatic carboxylic #acids provide Y a means for adjusting or controlling-the lgas-generating decomposition of the novel charge compositions .within reasonable limits, as maybe desired. However, the use of sucha carboxylic 'acid in proportion-substantiallyexceeding about per cent-.of the weight of the guanidine nitratev is not ordinarilyto. be recommended for best results.

dilueiit .orlheateabsorbing' material such,.for example, as

smolreformingagent, a. pesticide orotheriller. which ity maybe desired to. disperse. with minimum decomposition.thereof,..it isffrequently. necessary or desirablek to employ ,alargenproportion of` the aforesaid vsensitizer cbtuimnenLthanthe above-indicated maximum of 20 per cent, theweight of the guanidne'nitrate, in

' to.ensure.satisfactoryself-sustained exothermicgdecomposition. ,off.the latter, especially, under the working conditions.of.relatively-.low temperature and pressure most advantageously.characterizingutilization of such diluted charge.compositions.v l-Iowever, the fundamental consideretion :that gasfgenerating charge compositions of the invention.l must be; non-.explosive and non-detonating .in exothermic 'decomposition imposes apositive upper. limit -uponp-therproportionfofpolynitroor polynitrosophenol derivative :permissible .to employrtherein. .v-Sinc'e someoof these .derivatives (e. g. dinitroresorcinol);=are

themselvesexplosives,y lthe higherthe proportion of. suchv explosive derivativepresentin. the charge.. composition, thegreaterthe possibility-.that said composition mayfap'- proachabeingexplosivefor detonatable, .especially ify the chargeaalso'fincludesnanunonium nitrate. or ammonium perchlorate in'zthe '.restrictedzsmall proportions which, as presently ffai'apeal;'mayA be desirable.l and .permissible to. vemploys---in.rsomei circumstances. thereforeritzieadesirableto keep the proportionof ythe phenol' sensitizendown low -enough toexcludelthatpossibilityisxccordingly saidvproportion should" in no' event exceed...v per eent'ofrthe-weight of the guanidineninate atethelmostpeven. in the absence of oxidizing. salts like ammonilmL'nitratte-orfperchlorate, and it isvgenerally betlftohholdoitl down4 to' not substantially above 30 per cent.

=I"desi`red;. the `charges according toy the invention may include ian iraliphaticrcarboxylic vacid. selected from fthe grdupeconsistin'gfoftartaric,A maleic, citricA and fumarie acids.; :jiThe :presence of.: an aliphatic carboxylic acid permits less 'ofthe .polynitrorphenol or Apolynitroso-phenol to be.: present: '"aThis.' is because the aliphatic carboxylic acids are 'factasensitizing agents for the decomposition of` guanidinenitratet Being cheaper than the polynitroandv polynitros-phmolspthey can therefore. sometimesbe used Generally speaking,

to about l'atmospheres," their decomposition into gaseous productsis not quite' complete, and they leave a certain amount-(usually l5 to 20%), of the dicultly fusible nitrogenousorganic residue already referred to; At such pressures, moreover, the generated gases contain Aappreciable'quantities ofvaporized condensable organic matef rials, the presence of which 'may be` undesirable initier`v tain applications' -of the charges e. g. if they are yto'be usedas power gases in driving enginesor operating 4other mechanical devices where these organic vapors Vcan condense and cause fouling of pipes or moving parts.

It is found however that the inclusion of a. small pro-` portion of a promoter, such as vanadium pentoxide, amounting forv example to about 0.2 toll per cent ofthe weight .of the guanidine nitrate, has the veect .Ofcompleting the decomposition of the guanidine nitrate, thus. obviating the formation of the aforesaid yellow difficulty fusible- 'organic residue and correspondinglyA increasing thje yield of hot `gases at working pressures at which this residue would otherwisebe formed; and, especially where power gases are torbe produced, itis therefore best to includein the charge a small proportion of vanadium pentoxide or of a chemically equivalent vanadium compound decomposable on heating to yield a vanadium .oxide, such for example as ammonium` vanadate. Vanadiumftetroxide 'may also be used. It has also been foundy that metallic "molybdcnum or a compound of molybdenum, le. g. molybdic Yacid, molybdic oxide, ammonium molybdate, may be usedin place cfa vanadium compound as a promoter or catalyst for' the same purpose. These materials, or 'the residual' thermal. decomposition products thereof,'as well as the surface contact materialsv tob'e presently mentioned, may Vbe broadly termednonvolatile heat-resistant' materials vcapable of acting cata lyticall'y to promote maximum production of gases .in the selfsustaining decomposition `of the charge. ,y

vIt has further beerifound that the condensable lvapor?y ized organic compounds that'would otherwisebe formed atatniospheric or relatively low superatmospheric presf sure and carried off by the hot gases can be destroyed by causing them to undergo an exothermic reaction while in mixture with the 'gases proper, in the presence of catalytic surface contact material, whereby at the Sametime. the 'total hot gas yield is increased.A '1."his may be done by causing `the mixture of gases and vapors, beforeicool.-

ing takes' place, to 4pass over suitable. heat-resisting cata'- lytic solid surfaces'that'are larnentary in character, such as those of iron,;s.t'eel or platinum wire` gauze,or asbestos,

which-.are herein'generically designated asIgas-permeabler bodies of refractory material; .or by including; in the l composition `of* the charge asmall percentage." ofr' asbestos about 2%. When such large-surface refractorymaterial is actually incorporated in the charge, the proportion thereof should of course be kept down to a minimum consistent with effective action. So employed, it also steadies the self-supporting characteristics of the reaction and holds together the ash of the charge. It may be desirable to include a small percentage of potassium nitrate in thecharge amounting, for instance, to about 0.25 to 1% thereof, since the potassium nitrate assists the reaction between the gases and vapors on the solid catalytic surface. The use of the potassium nitrate is especially desirable if the charge is in an unusually cold condition before it is locally ignited, or in an environment such that the gases and vapors are at a lower temperature than that at which they would normally be generated. Using as much as 5% potassium nitrate is permissable, but is virtually never necessary. Therefore since it would increase the quantity of residual slag and also correspondingly reduce the proportion of guanidine nitrate in the charge, the use of as much as 5% is virtually never resorted to in practice.

i Charges made in accordance with the invention may be used for instance for actuating gas pressure operated mechanical devices, e. g. for driving engines, or for operating pneumatic tools, for operating re extinguishers, for propulsion of rockets and other gas escape reaction propelled devices, for dispersing insecticidal or the like substances, for making colored smokes, or for safety blasting operations by means of blasting assemblies in which the charge is caused to undergo decomposition in a pressure resisting container adapted to vent the gases once a predetermined pressure has been built up within the container. It will be understood that according to the purpose for which the charge is required it may be in powder, granular or compact form of any required shape, and may or may not include ingredients for reducing or raising the temperature of the gases it generates. The hereinafter mentioned thermally volatilizable fumigating or smoke producing materials are examples of ingredients which reduce the temperature of the said gases and, by way of example, ammonium perchlorate and ammonium nitrate are reagents which raise the temperature of the said gases.

Where charges embodying the invention are not for power-gas production but include insecticidal or other substances to be dispersed, such substances may be thermally volatilizable materials as, for instance, insect repellants, insecticides, fungicides, bactericides andother pesticides; 4as well as smoke-producing compounds, includng colored dyestuis. In this case the charge will usually be required to decompose under atmospheric pressure conditions. Moreover, if any of the aforesaid materials is an organic compound it will be understood that, if the charge is to include asbestos bre or other material of large-surface characteristics, such surfacecontact'material must be employed in such manner that the l'gases and vapors will not undergo to any extent a4 reaction on its surface so intense as to destroy a large proportion of the volatilizable compound in the gas stream. The volatilization of the organic compound has in, itself a cooling etect so that if suiicient of such compound is used the temperature will be too low for any such undesirably intense surface reaction to take place. For example, 4:6 dinitro-ortho-cresol is a polynitrophenol that has itself marked insecticidalv and arachnicidal properties, a fact which may be taken advantage of toa certain extent if the charge contains an excess of the amount of this polynitro-phenol over that recommended hereinbcfore for a charge to be used solely for power-gas generating purposes. When an excess of this material is present, not all of it will be decomposed by the" gas producing reaction and the excess will be volatilized and available for effecting fumigation. Normally, however,

considered preferable to incorporate a specicreagent, such -as DBT or Gammexane as illustrated in certain of the following-examples, for producing a fumigating device of the type proposed. Generally speaking, the amount of insecticidal or other volatilizable or dispersible material thus included in the charge should not materially exceed about 20 per cent by weight of the entire charge.

Another way of reducing the temperature of the gases generated by the guanidine nitrate decomposition is to include in the charge a small proportion, not exceeding about 10 per cent', of a carbonate, e. g. calcium carbonate, decomposable at the temperatures involved, e. g. on the order of l000 C. The amount of such inclusion should ordinarily not exceed about 10 per cent of the charge as a maximum.

Where, on the other hand, it may be desired to increase the temperature of the evolved gases above what it would otherwise be, minor proportions of an oxidizing salt, such as ammonium nitrate or ammonium perchlorate, may be included, but always with due care that the charge composition shall nevertheless remain non-explosive and nondetonating in character. Thus the charge may safely include up to 20 per cent ammonium nitrate, or up to l0 per cent ammonium perchlorate, provided that with these maximum proportions the charge does not contain more than about 10 per cent of the polynitroor polynitroso-phenol, and provided the mixture is compressed to a density of not less than 1.4 cc. per gram.

In order to make still clearer the principles underlying the invention, typical desirable embodiments thereof are illustrated hereinafter by means of specific examples, certain of said examples including structural details of gas-generating charge arrangements which are desirable practically and which are further illustrated in the accompanying drawings, wherein Fig. l is a cross section in elevation of one type of cartridge containing a charge `embodying the invention; and

Fig. 2 is a cross section in elevation of another type of cartridge illustrating a typical use of a slightly modied charge.

l In the aforesaid specific examples now to be set forth, it is to be understood that the stated percentages are by weight.

Example 1 In this instance, the charge composition is intended primarily for production of power-gases, with virtually complete decomposition of the guanidine nitrate base, and substantial absence from the gases of organic material condensable in the apparatus utilizing said gases. v To this end, a mixture of the composition:

Percent Guanidine nitrate 88.75 2:4 dinitro-resorcinol 10.0 Asbestos bre 0.5 Vanadium pentoxide 0.5 Potassium nitrate 0.25

is subjected to ball milling until the composition is well` mixed and pulverized. 3 lbs. of the mixture is then loaded in four equal increments into a 3 diameter open-ended steel tube 10 lined with compressed asbestos libre sheeting 11, as illustrated in Fig. 1, each increment being pressed for l minute at 700011?. per square inch, the compressed composition 12 occupying all but one inch at each end of the length of the tube.A `A hole 13 of 1 inch diameter is then drilled axially through the length of the compressed composition. Four or tive circular disks 14 of iron wire gauze, each of 3 diameter and of a mesh ranging from l0 to 50 to the inch (BSS) are fitted into one end of the tube and an electrical ignition system, indicated generally at 15, including a rod of cordite 16 weighing 20 grams, is arranged at the otherend of the tube with the cordite' extending into the drilled channel 13.

The tube containing the composition is used to operate amante a motonoi rotary ,blower design at a progressivelyin-l creasing speed at aconstant working pressurea ofi about 120 lbs. per square inch. .The charge leaves/an incom-A bustiblerskeletonamounting to less than l.2-%-of the material in the apparatus.

` Example 2 In this case also, production of power gases substantiallyv freefrom condensable components is the objective. A mixture of the composition:

is subjected to ball mixing until the ingredients are well mixed into the form of a tine powder. 20 grams of the mixture are pressed in a tubular mould 0.95 inch in ldiameter lined with asbestos paper undera pressure suflicient to give a well consolidated pellet. In this instance, as shown in Fig. 2, the pellet 20 with its asbestos sheath 21 is ejected from the mould and fitted into a cylindrical container (not shown) of approximately l diameter closed at one end and fitted withy ascrew-on cap at the other end carrying a jet 0.055 inch in diameter. The ignition system, indicated generally at 22, for the pellet at the open .end consists of a sliver of cordite 23 heldfon the surface of the composition by means of a tightly tting circular disk of 60-mesh BSS stainless Ysteel wire cloth 24 with a length of thin black-powder fuse 25 runningy from the cordite to the exterior through the jet in the cap of the container.

This miniature jet motor forms thepropulsion unit. of a model racing car. The ignition is brought about byigniting the fuse with a match which ignites the cordite, which in turn locally heats the composition of the 'charge to the tmperature at which the evolutionof the gases becomes active, the decomposition then sustaining, itself through the charge. In this manner a thrust of 3 oz. weight lasting for 20 seconds is exerted on the model racing car. The ash is a coherent skeleton of the pellet and amounts to, about 1% of its weight.

Example 3.

The specific embodiment of the invention. to which this presentexample is directed, like those illustrated inthe succeding examples as well, diifers from those of Examples 1 and 2 primarily in that a diluent material that is to be dispersed as such, in this instance an insecticide or an in.- sectifuge,^is a substantial componentV of the mixture; and

that self-sustained decomposition of the guanidine vnitrate at ordinary atmospheric pressure isdesired; 'With thisA in-view, amixture of the composition:

Percent Guanidine'nitrate 67 4:6 dinitro-o-cresol 1.8 Alpha-alpha-bis- (parachloro-phenyl) -beta-beta-betatrichloroethan'e (DDT) 15 is preparedby .grinding the ingredients together until. they are well mixed in the form of a tine powder. 2O grams of the mixturev are consolidated into the form of a pellet 1 inch. indiameter by compression. in a moldand ejected.

The resulting insecticidal pellet when strongly-heated` atA contacted b y it, Ithusrendering themlethal .to houseies (e. g.) for some time. The pellet leaves. anion-volatiley residue amounting tol about 10% of its weight.V In this example, because of the diluting and-heat-absorbing effect of the added :specific-.insecticide ingredient thatzis-to be dispersed by thermal Ydecomposition of the charge proper, withresultant cooling of the generated gases,..th e poly-Y nitrophenyl-is employed in much larger proportion than in Examplesl` and2. Thus, in the present example, the quantityl of 4this material employed amounts` to 26.3% `by weight of the guanidine nitratewhich latter, however, still remains the greatlypreponderating or major ingredient of said charge.: ,The 10% residue left bythe pelletcon` sistsin-part of the before-mentioned diicultly fusible yellow nitrogeneous.- organic material, due tojomissiontfrom this charge. of vanadium pentoxide .or an equivalent pro-A moter necessary to ensure complete decomposition of the guanidine A.nitrate at atmospheric pressure. The .omis. sion also of asbestos or other large-surface:heat-resistant contactmaterials; from this type of charge has the advantage of permitting a larger proportion. of the organicim secticidal material carried by the generated gasesto escape destructive ,decomposition and to perform its intended, function.

Example 4 Example 5 A mixtureof'the composition:

' Per cent Guanidine` nitrate v Dinitroso-resorcinol 15 Gammexane 20V is ground thoroughly until` mixed in the form vof ane powder. In this case, the proportion of polynitrosophenol -sensitizing agent employed is approximately 23 per cent of the weight of the guanidine nitrate.

A 20 gram insecticide pellet of the compositioniisv pressedas/described in Example 3 andits'decomposition,

is initiated lin similar fashion. A dense white smoke containingGammexane is produced without any llamen.` Here also, the non-volatile residue amounts to about l0% of the weight of the pellet.y

From the foregoing it is apparent that, in accordance Withthe present invention, a gas-generating charge 'em-i bodying the invention consists in major part,` most desir-l ahly at least 60 per cent, of guanidine nitrate heat-sensitized by avariable but always much smaller quantity of a lphenolof the character specified, never exceeding 35. per cent by weight of the guanidine nitrate and beingI usually less vthan 30 per cent thereof; also` that said` charge may include the hereinabove indicated small per centages of decomposition-assisting orfc'atalyzing agents adapted to promote maximum gas yield and .minimize objectionable ,residue formation, as well `as of agentsV effective to lowerv or` raise the temperature of the gener-y ated gases. It is further apparent that the proportion of the phenol sensitizer relative to the guanidine nitrate may vary widely depending upon various factors such, for example, as therworking pressure at which the charge.

is intended to operate, the presence or absence. of` decomfv positionfassisting or promoting agents, how` much (if any); diluentor heat-absorbing volatilizable. material isL employed in combination vwith the kgas-generating. .chargeIl p'b'per Afor d'is'p'ersioxi thereby, and so on, the proportion offs'e'nsitizer increasing with lowering of such working pressure, and being also necessarily greater where such vlatilizable material is associated with said charge proper. "It is an advantage of the invention that the novel compositions maybe made by simple admixture of the ingredients, and that when the charge is required to be ofcompact structure'andv predetermined form so that it will react only on its exposed external surface, it may be made by compressing the mixture into a mold of the desired shape. Moreover, ifit is required to protect a portion ofthe surface of the compact charge from the hot -gases evolved by means of an adherent covering of heat-insulating material, this may if desired be done in the course of they pressing operation of applying protective material to the surface of the charge after it has been shaped.

- The gas-producing mixtures of the present invention undergo decomposition much more slowly than do blackpowder compositions, for example, and henceare safer to handle. Moreover, the gases can be produced at temperatures on the order of 1000 C., which is relatively low for propellent compositions, rendering them particularlyt well suited for use in driving engines. Undercomparable conditions, gases generated from guanidine nitrate sensitized by nitrocellulose (as heretofore proposed) are much hotter than this, sometimes too hot to use for driving engines. A

It is also to be' observed that the compositionsof the invention can be pressed into tubes and therebyiobtain layer-by-layer combustion, without any danger 4of the .compressed charges breaking up and exposing uncontrolled burning surfaces. Again, as hereinabove illustrated, 99% of the charge can be converted into gaseous products, leaving behind only about l per cent residue which, moreover, is not entrained in the gases. Furthermore, although the temperature of propellent gases can be higher for rockets than for engines, the invention provides novel charge compositions that can be advantageously employed in rockets because said compositions can be used at relatively low pressures, thus requiring only light casings for such rockets.

When the rate of gas evolution is not to be controlled, as may often be the case where a diluent to be dispersed l(e. g. a pesticide). is included in the charge, the novel kcompositions may be employed in loose powder form instead of being compressed into pellets. The ingredients of the novel compositions are all dry materials except that a small amount of liquid, on the order of 1 per cent or thereabouts, may be included, for example mineral oil (see' Example 2 hereinabove), to reduce dusting where some or all of the ingredients are in nely powdered form.

In the most desirable embodiments of the invention, the two indispensable components of the novel gas-generating charges, namely, guanidine nitrate and the decomposition-assisting phenol, together constitute at least 75 to 80 per cent of the whole charge, whether or not the charge includes diluent material of the character hereinabove pointed out. Where such diluent is absent, these two components most desirably constitute at least 90 to 95 per cent or more of the charge. In Examples 1 and 2 given hereinabove which represent charge compositions that are highly satisfactory where maximum production of clean power gases is the primary objective, somewhat more than 98 per cent of each of the described charges consists of said two components, the proportion of the phenol approximating l per cent of the charge in both instances.

This application is a continuation-impart of the present applicants prior application Serial No. 42,948, now abandoned, filed August 6, 1948, and copending herewith. All subject matter contained in said prior application is to be regarded as included herein by reference.

. l0 V What is clairned'is: l'

' 1. A non-explosive gas-generating charge consisting in major part of guanidine nitrate and comprising admixed therewith, in proportion not exceeding 35 per cent by 2. A non-explosive gas-generating charge as claimed in claim 1, wherein guanidine nitrate constitutes at least 60 per cent of the charge by weight.

3. A non-explosive gas-generating charge as claimed in claim 2, wherein the proportion of the phenol employed is from about 5 per cent to about 30 per cent by weight of the 'guanidine nitrate.

4. A non-explosive gas-generating charge as claimed in claim 1, wherein the guanidine nitrate constitutes at least a'bout 65 per cent of the charge by weight and wherein the proportion of the phenol employed is from about 5% to about 30% by weight of the guanidine nitrate.

5. A non-explosive gas-generating charge as claimed in claim 4, wherein the guanidine nitrate and the phenol together constitute at least about 75 per cent of the charge.

l 6. A non-explosive gas-generating charge as claimed in claim 1, wherein the guanidine nitrate and the phenol together constitute at least per cent of the charge, and` which further includes not to exceed 5` per cent of non volatile material capable of acting catalytically to promote maximum production of gases in said decomposition, said non-volatile material being selected from the group consisting of vanadium oxides and vanadium compounds thermally decomposable to yield vanadium oxides, metallic molybdenum, molybdic acid, molybdic oxide and ammonium molybdate.

7. A non-explosive gas-generating charge as claimed in claim 6, wherein the guanidine nitrate and phenol together constitute approximately 98 per cent of the charge.

8. A non-explosive gas-generating charge as claimed in claim 7, wherein the phenol is 2:4 dinitroresorcinol and constitutes approximately 10 per cent of the charge, said charge also including up to 1 per cent each of vanadium pentoxide and asbestos fibre.

9. A non-explosive gas-generating charge capable of self-sustained, exothermic non-detonating, tlameless, decomposition at relatively low pressure upon heating a localized portion thereof to incipient active decomposition temperature, which charge consists in major part of guanidine nitrate and further includes an admixed compound selected from the group consisting of 2:4 dinitroresorcinol, 2:4:6 trinitro-resorcinol, 2:4 dinitroso-resorcinol, 4:6 dinitro-orthocresol, 3:5 dinitro-catechol, 2:6 dinitro-paracresol, and 3:5 dinitro-salicylic acid, the proportion of such admixed compound being from about 3 to about 35 per cent by weight of the guanidine nitrate component.

10. A gas-generating charge as claimed in claim 9, wherein said admixed compound is 2:4 dinitro-resorcinol.

11. A gas-generating charge as claimed in claim 9, wherein said admixed compound is 2:4 dinitro-catechol.

12. A gas-generating charge as claimed in claim 9, wherein said admixed compound is 2:4 dinitroso-resorcinol.

13. A gas-generating charge as claimed in claim 9, wherein said admixed compound is 4:6 dinitro-orthocresol.

14. A gas-generating charge as claimed in claim 9, wherein said admixed compound is 3:5 dnitro-salicylic acid.

15. A non-explosive gas-generatingfv :.zltargeas@ claimed in= claim 1,.-.wherein` aportiononly ofj-"suehlphenol' is replaced :by an aliygahatic': carboxylic `acid yin. amount: .not exceeding 1.0.,per-cent1of` the chargezfby. weight, said `car-- boitylic acidlbeingselected;from the gronpfconsistingrot'y tartaric,.maleic, .citric-and v.fumarie acids. .v

16. A. non-explosive. -gas-.generatingecharge .as claimed in claim.1, wherein `theguanidine nitrate. constitutswatleast` about` 60 per cent -gby weight fot .the charge, yand the proportion offthe phenol is -fromrabout per .cent to about 30 per'centlby-weightof.the guanidine nitrate; which charge. further. includeszznot more. thanabout 5. per fcent. of non-volatile .heatfresistant solide-materiali capableV .of acting catalytically yto lpromote1maximumproduction.of gasesin. s aid.decomposition,..said solid materialfbeing selected'from the gronp 4,consistingof-f vanadium oXidesand vanadium compoundsr-thermally,decomposable to yield Vanadium .oxides,umetall i :J molybdenum, .molybdic acid, molybdic .oxide :and ammonium.molybdate.A

i 17. vA..non-explosive gars-generatingtcharge claimed in claim `-16, wherein the charge further includes. `a small. proportion. of potassiumznitrate` not excecdingS ,per cent byweights. .r l

`1.8.,'1he combination, with the chargedened in claim 1, of `la container coniiningsaid` charge Vand provided with a gas-dischargey outlet, of a.:gaspermeable body of nonvolatile, solid, heat resistant..lamentaryscatalytically active large-.surface contact material interposed between said chargefandvsaidoutlet, through'.whichgases:resultingiromt decomposition of said charge are compelled to passzen route. to saidcutletn 19. The combinationclaimed in claim 18, wherein-said.

material is selectedy from the group consistingoffironfsteel,

platinum, asbestos.

20. -A nonfexplosive :gas generatingcharle as claimedl in claim 1,: wherein -the vguandine nitrategand .thqphnolg togethenconstitute at least 90%` of'the charge,.a nd further includesznot more-.than 2% .by weightof the charge:

of anon-volatile heat-.resistant catalytically. active lamentary, .large-surface. 'contact material.

. 2'14. A non-,explosive gas-generating charge in claim-.20, wherein saidlarge surface contact material, is selectedtrom the group `consistingfoi iron, steel, .platty num,- .and asbestos;

2,2. A non-explosive gas generating rchargeas clm'modk iny claim 1, `wherein the guanidiruev nitrate andgthe phenol. together constitute. at 1east-9.0.%of the charge, whichffur-; ther includes not more ethan 2% `:by weight of' chargeI of a.. nonvolatile ,heat-resistant -catalyticallyvt active. vilamentary,.1large.surface contact materiaLandf-a .smalljlrop portion of potassium nitrate not exceeding 5% by weight...

23, A non-explosive gas generating` chargefas claimed in claim- .22 whereinrthe `proportion :potassiumbnitrate:

lReferences Ctedt-in-:the vile of this patent UNITED STATES PATENTS i'.

Claims

1. A NON-EXPLOSIVE GAS-GENERATING CHARGE CONSISITING IN MAJOR PART OF GUANIDINE NITRATE AND COMPRISING ADMIXED THEREWITH, IN PORTION NOT EXCEEDING 35 PER CENT BY WEIGHT THEREOF, A PHENOL CONTAINING IN ADDITION TO AT LEAST ONE PHENOL HYDROXYL GROUP A PLURALITY OF SUBSTITUENT GROUPS EACH CONSISTING OF A NITROGEN ATOM ATTACHED EXCLUSIVELY TO AT LEAST ONE TERMINAL OXYGEN ATOM AND TO ONE OF THE NUCLEAR CARBON ATOMS OF THE PHENOL; SAID CHARGE BEING NON-DETONATABLE BY A BLASTING CAP AND BEING CAPABLE, WHEN A LOCALIZED PORTION THEREOF IS HEATED SUFFICIENTLY HOT TO INITIATE DECOMPOSITION, OF SELF-SUBSTAINING, NON-DETONATING, GAS-EVOLVING, EXOTHERMIC DECOMPOSITION AT PRESSURES LOWER THAN 70 ATMOSPHERES.