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US3049454A - Low density cellular explosive foam - Google Patents

Low density cellular explosive foam Download PDF

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US3049454A
US3049454A US580677A US58067756A US3049454A US 3049454 A US3049454 A US 3049454A US 580677 A US580677 A US 580677A US 58067756 A US58067756 A US 58067756A US 3049454 A US3049454 A US 3049454A
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explosive
foam
weight
percent
foamed
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US580677A
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Howard J Stark
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    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • C06B45/04—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive
    • C06B45/06—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component
    • C06B45/10—Compositions or products which are defined by structure or arrangement of component of product comprising solid particles dispersed in solid solution or matrix not used for explosives where the matrix consists essentially of nitrated carbohydrates or a low molecular organic explosive the solid solution or matrix containing an organic component the organic component containing a resin
    • C—CHEMISTRY; METALLURGY
    • C06—EXPLOSIVES; MATCHES
    • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
    • F42B12/02—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect
    • F42B12/20—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the warhead or the intended effect of high-explosive type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B22/00—Marine mines, e.g. launched by surface vessels or submarines

Definitions

  • Patent No. 2,768,072 dated (Pct. 23, 1956. Divided and this application Apr. 25, 1956, Ser. No. 580,677
  • Ciaims. (Cl. 149-92) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the pay ment of any royalties thereon or therefor.
  • This invention relates to low density explosives and in particular to a low density, cellular explosive foam.
  • the general object of the invention is to provide an explosive having a cellular foam structure which, because of such foam structure, is of relatively low density, is buoyant with respect to water, and of greater and more rapid shattering effect than the same weight of high density explosive.
  • FIG. 1 is a flow chart of the dynamic air-set method of this invention
  • FIG. 2 is a ow chart of the chemical blowing method of this invention
  • FIG. 3 is a diagrammatic transverse section through a conventional floating mine
  • FIG. 4 is a diagrammatic transverse section through a oating mine of the type illustrated by FIG. 3 but containing a relatively large quantity of the foamed explosive of this invention cast in situ;
  • FIG. 5 is a diagrammatic sectional-elevational View of a floating mine in which the shell is comprised of the molded foamed explosive of this invention encased in light weight metal or impregnated fabric and shows the increased high explosive charge possible with this type of construction;
  • FIG. 6 is a diagrammatic longitudinal section through a floating, harbor mine showing the combination in the explosive charge of the conventional high density explosive with the foamed explosive of this invention
  • FIG. 7 is a diagrammatic longitudinal sectional-elevational view of a torpedo carrying a charge of high density explosive and foamed explosive of this invention.
  • FIGS. 8 and 9 are a diagrammatic longitudinal sectional-elevational View and a transverse sectional view taken on line 9 9 of FIG. 8, respectively, of a radio controlled homing vessel showing the foamed explosive of this invention cast and molded within the structure of the double walled hull.
  • This inventor has met this requirement by providing a foam type explosive which resembles in physical appearance and characteristics cellular polystyrene or cellular acetate. It is relatively strong andtough and the density thereof can be varied by formulation Within the range of from about 5 to about 50 pounds per cubic foot.
  • the cells of the foamed and set structure of the explosive are substantially non-communicating and referred to as closed-cells in contradistiction to spongy open-cells. Therefore, a molded plate of this material is relatively impervious to gas and water. In comparison with balsa wood, which has a buoyancy of about twenty pounds per cubic foot after twenty-four hours immersion under a ten foot head of water, this cellular explosive has a buoyancy of from about 20 to about 50 pounds per culbic foot under similar conditions.
  • the following explosives can be prepared in foam or cellular form: (l) Trinitrotoluene (2) Nitrocellulose (tri, hexa and dodeca nitrocellulose) (3) Pentaerythritol (4) RDX (cyclo triemethylenetrinitramine)
  • the foamed explosive consists essentially of any one of the above explosives bonded by a foaming plastic.
  • a foaming plastic is a plastic which will be of solid cellular structure when it is allowed to set after being foamed either by chemically or mechanically blowing gas or air through it while in the liquid stage as will appear in the example set forth below.
  • polyesters of ethylene glycol-maleic anhydride intermixed with monomeric styrene is ideally suited as a resin in the carrying out of this invention.
  • This resin is shown and described along with other resins which also are suitable in Carleton Ellis Patent 2,255,313, which is incorporated by reference and forms a part of this specification.
  • Carleton Ellis Patent 2,255,313 which is incorporated by reference and forms a part of this specification.
  • a ller as used in the examples of Ellis is unnecessary and not used although such use would still fall within the scope of what is considered to be the present invention.
  • An example of one of these resins is that produced by heating 500 parts of maleic anhydride and 541 parts diethylene glycol in an oil bath at 220-225" C. for 7 hours while bubbling nitrogen gas therethrough to provide an inert atmosphere.
  • the diethylene glycol maleate formed is a light-colored viscous liquid of acid number 7.1. Eighty-tive parts of this liquid are mixed with 5 parts monomeric styrene in a glass container with a mechanically driven stirrer.
  • the resultant liquid is a satisfactory stock solution and has 3% (by weight) benzol peroxide (curing agent) and 31/2% (by weight) cobalt naphthanate (accelerator) added to it just prior to its use.
  • thermosetting polyester resins are well known in. the field of resin chemistry and their specific compositions form no part of this invention.
  • the requirernents thereof are that they be compatible with solutions ofthe explosives, that they gel at room tern- 1 sivel sui'cient to prevent the escape of air therefrom and yet be suliiciently fluid forefcient molding aud casting.
  • the rateA of setting of these resins is controlled by the addition thereto of a relatively' small proportionl (from about 2% to' about 4% by weight) of an approinclude: benzol peroxide, ditertiarybutyl peroxide, cumenehydro peroxide, methylisobutyl ketone peroxide,
  • the 'particular curing agent used dependsupony its compatibility with the solution of the1 resin'and the explosive andthe rate, of curing desired.
  • an accelerator such ascobalt naphthanate may be ⁇ added in a proportional amountl of from about 2%' to about 5% by weight to give additional 'control' on the rate of geliing and setting of the resin.
  • a solution of a foaming plastic such as polyester type resin, a curing agent or catalyst and an accelerator is prepared as shown at 12 in the proportionate amounts above indicated. From about to about 30% by volume of the liquid resin solution is mixed with the solution of the explosive as shown at 14.
  • the diethylene glycol maleate with monomeric styrene is mixed with benzol peroxide and cobalt naphthanate as specifically set forth above. About 20% by volume of this solution is mixed with a saturated solution of TNT dissolved in styrene.
  • the curing agent and accelerator will cause the resin to gel in about 15 minutes and to set permanently in about one hour.
  • the mixture of solutions of the explosive and resin is stirred for about 5 minutes as indicated at 15 and allowed to rest for about 5 minutes.
  • Compressed air from a source (not shown) is introduced into blowing chamber 18 and thence through yforaminous member 20 which may be a glass frit or metal screen of a mesh in the range of from 75 to 300 and through the mixture at 14 for about 3 minutes which will foam the said mixture.
  • the foamed mixture is then poured into molds or other containers within the remaining 2 minutes of the 15 at which time the foamed explosive gels or sets up and in one hour becomes a hard cellular mass.
  • the foaming plastic may be a poly-l ester type resin as above described or other foaming plastics set lforth below. In either casethey are adjusted to gel in about fifteen minutes and to set. in aboutl l one hour as in the process'a-bove described.
  • the solutions of. the lexplosive and the resin are conducted into mixing chamber Z8, the solution of the resin being added. in the proportion by volume of from 10% to 30%.
  • foaming plastics are set forth below and it will be understood by a chemist familiar with the art that such foaming plastics are capable of use with the dynamic air-set method as well as the chemical blowing method.
  • a chemically blown foamed explosive can be prepared by using toluene diisocyanate and alkyd resins to produce a composition referred to in the art as polyurethane foam resins. Carbon dioxide is liberated in the reaction to cause the plastic to foam and thus, in effect, the ingredients act as their own blowing agents.
  • alkyd resin having following composition is prepared:
  • Ratios of explosive to resin by weight range from 10% resin to explosive to 50% resin and 50% explosive.
  • Ingredients (A) and (B) are first mixed in a mechani# cal mixer such as a Hobart of suitable capacity. Then ingredient (C) is mixed therewith followed by ingredient (D) which is mixed therewith or stirred for about 20 minutes.
  • a mechani# cal mixer such as a Hobart of suitable capacity.
  • ingredient (C) is mixed therewith followed by ingredient (D) which is mixed therewith or stirred for about 20 minutes.
  • This mixture is then poured into a suitable metal mold calculated to produce the desired density which in this case is about l0 pounds per cubic foot.
  • the closed mold containing the mixture is then placed in a hot air oven at about 73 C. for about one hour after which the mold is removed from the hot air oven and cooled to room temperature and the explosive TNT foam is removed therefrom.
  • a polymerized material consisting of about 85% by weight of polyvinyl chloride and about by Weight of copolymers of vinyl chloride and vinyl acetate are mixed in a Hobart mixer with about 80 parts of tricresyl-phosphate (plasticizer) until the polymer is thoroughly dispersed.
  • About 25 parts of P.P'oxybis benzene sulfonyl hydrazide (chemical blowing agent) is then added and mixed thoroughly. (Diazoaminiobenzene or 40% dinitroso pentamethylenetriamine may also be used as chemical blowing agents.)
  • About 3 parts of lead stearate (stabilizer) is also added and mixed thoroughly.
  • TNT fine state of division
  • Standard Sieve No. 50 or 100 as delined by the American Society for Testing Materials Standards
  • a suitable charge or volume of this product is placed in a steel mold of desired shape.
  • a steel mold of desired shape Such an example would be a mold 6 x 6" x 1/2 of heavy steel wall construction as established in the art or industry for processing these products.
  • the mold cavity is completely illed, and the charged mold placed in between press platens at a temperature of about 160 C.
  • the press is then closed and about 5000 p.s.i. pressure applied to the mold and held for about minutes at this temperature. After this time the pressure is reduced to atmospheric and the mold removed from the press.
  • the mold is opened and the molded piece is removed. It is then placed in a hot air oven or chamber at about 120 C. for about 60 minutes when the piece will then grow or expand to about double its volume producing a density between 4 and 7 pounds per cubic foot.
  • the density can be considerably changed by varying the charge into the mold and the weight of explosive incorporated into the mold.
  • An epoxy resin can be used in carrying out the invention in a manner such as shown by the speciiic example below.
  • Explosive foam mixture is prepared using the following ingredients:
  • Epoxy resin as above is heated to the liquid stage at about 75 C.
  • the ammonium bicarbonate previously dispersed in diglycol laurate S is then added and stirred thoroughly.
  • the TNT is then added and stirred, followed by the piperidine which is then added and mixed for about 5 minutes.
  • the liquid phase life at this stage is limited to about 30 minutes; otherwise, polymerization or solidification sets in.
  • the mixture is then transferred to a heated metal mold or box held at about 75 C. for about 2 hours when the explosive foam is made.
  • the explosive completely fills the container.
  • the explosive foam mixtures may also be made from nitrocellulose, pentaerythritol, and cyclo trimethylenetrinitramine.
  • the density of the explosive foam is controlled by varying the percentage of explosive going into the composition and the weight of mix going into the heated mold cavity or box as described above.
  • This particular explosive foam composition may also be cured using other amine reagents such as diamines, triamines or quaternary amines such as, diethylenetriamine and triethylenetetramine.
  • Commercial resins such as Shell Chemical Company Epon resins such as Epon 834, Epon 864, and Epon 1001 and mixtures of these various resins may also be used. Cure or hardening is accomplished by using any one of the amines stated above.
  • FIG. 3 a conventional iloating mine is shown diagrammatically and generally at 40.
  • the mine comprises a metallic case 4Z, contact elements 44 which are in electric circuits 46 with the detonating or exploding device 48.
  • This exploding device detonates the charge of high explosive 50 when any one of the elements 44 is actuated by contact with an object in the water.
  • the interior volume of this type of mine is comprised of about 50% air space as shown at 52.
  • FIG. 4 the air space of the mine shown in FIG. 3 is filled with the foamed explosive of this invention as shown at 54 which has been cured and set in place.
  • This foamed or cellular explosive not only gives an additive eect to the brisance of the high explosive, but in the event of leakage through metallic shell 42 due to erosion or corrosion thereof, the buoyancy of the mine will be maintained substantially as that existing when the mine is in leakproof condition.
  • FIG. 5 is illustrative of an embodiment of this invention in which the shell of the mine is comprised of molded cellular explosive 56 covered on the exterior and interior faces with a relatively thin layer of metal or impregnated fabric 58.
  • the increased buoyancy of this type of construction over the conventional, heavy metallic case mine is readily apparent. in fact, the buoyancy is so much greater that substantially the entire interior space of the mine may be lled with high density explosive thereby producing a mine of greatly increased shattering effect when also considered in the light of the additive explosive elfect of the cellular explosive comprising the shell.
  • FIG. 6 is a sectional illustration of a floating harbor mine showing the arrangement of a metallic casing 60, a high density explosive charge 62, detonating or exploder device 64, actuating contact element 66 and foamed explosive of this invention 68 surrounding the high explosive charge and exploder device and filling the air space normally present within the casing of this type of mine.
  • the foamed explosive prevents loss of buoyancy and the normally resultant loss of the mine.
  • FIG. 7 is a sectional-elevational view of a torpedo shown generally at 70 in which the foamed explosive 72 of this invention fills the normally present air-space within the shell 74.
  • the legends in this figure are believed to be self-explanatory.
  • the overall buoyancy of the torpedo is less than that of the torpedo having the conventional air space. But the total shattering effect of the explosion is much increased by this additional quantity of foamed high explosive.
  • the foamed explosive is poured into this space immediately prior to the gelling thereof. The space is completely filled and upon the curing and setting of the resin component the cellular explosive becomes rigid and reinforces the sidewalls of the shell.
  • FIGS. 8 and 9 show the application of the foamed high explosive of this invention to the structure of an electronically controlled homing vessel in sectional-elevational views.
  • the double walled hull 90 is shown provided with radio control 92 for motor drive mechanism 94.
  • High density high explosive 96 substantially fills the interior of hull 90 surrounding the exploder device 98.
  • the detonating contact element is shown at 99.
  • T he space within the double wall structure of the hull is filled with the foamed high explosive of this invention as shown at 100.
  • the foamed explosive is poured into this hull wall spaced irnmediately prior to the gelling and after setting the foamed cellular explosive mechanically reinforces the structure.
  • the advantage of this type of construction of these homing vessels is that the shattering effect of the explosion is greatly increased and that in the event of leakage through the outer wall of the hull due to corrosion or to any other cause the buoyancy of the vessel is maintained.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and impervious to the passage of fluid, said foam being a homogeneous mixture of about 90 percent to about 70 percent by weight of an explosive from the group consisting of trinitrotoluene, nitrocellulose, pentaerythritol, and cyclo trimethylenetrinitramine and a binder of about 10 percent to about 30 percent by weight of a thermosetting polyester resin.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of uid, said foam being a homogeneous mixture of about 8S percent to about 67 percent by weight of trinitrotoluene and from about 12 percent to about 33 percent by weight of a thermosetting bonding polyester resin.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about 85 percent to about percent by weight of nitrocellulose and from about 15 percent to about 40 percent by weight of a thermosetting bonding polyester resin.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about 85 per cent to -about 75 percent by weight of pentaerythritol and from about 15 percent to about 2.5 percent by weight of a thermosetting bonding polyester resin.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about percent to about 55 percent by weight of cyclo trimethylenetrinitramine and from about 35 percent to about 45 percent by weight of a thermosetting bonding polyester resin.
  • An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and impervious to the passage of uid said foam being a homogeneous mixture of about 90 percent to about percent by weight of trinitrotoluene and from about 10 percent to 30 percent of an alkyd resin.

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Description

Aug. 14, 1962 H. .L STARK Low DENSITY CELLULAR ExPLosIvE FOAM 3 Sheets-Sheet l Original Filed Aug. 15, 1955 mmmcomm @2 0402 .AI
mmmOOm-A 025402 INVENToR. HOWARD J. STARK A T TOYRNE Y Aug. 14, 1962 H. J. STARK 3,049,454
LOW DENSITY CELLULAR EXPLOSIVE FOAM Original Filed Aug. 15, 1955 3 Sheets-Sheet 2 '.FoAMEo l l xPLoSnvraY l DETONATUR EXPTSSIVE $0 66 XDETONAT R W ExPLoslvE o FIG. 6`.
WARHEAD FOAMED EXPLOSIVE 74 ENGNE HIGH EXPLOSIVE 70 FIG. Z
JNVENTOR. H0 WARD .l STARK Aug. 14, 1962 H. J. STARK LOW DENSITY CELLULAR EXPLOSIVE FOAM 3 Sheets-Sheet 3 Original Filed Aug. l5, 1955 FIGB.
FIG. 9.
FOAMED EXPLOSIVE JNVENTOR. HOWARD J STARK BY E ATTORNEY 3,049,454 Patented Aug. 14, 1962 ice LOW DENSITY CELLULAR EXPLOSIVE FAJW Howard J. Stark, 920 N. Lebanon St., Arlington, Va. Original application Aug. 15, 1955, Ser. No. 528,566, now
Patent No. 2,768,072, dated (Pct. 23, 1956. Divided and this application Apr. 25, 1956, Ser. No. 580,677
6 Ciaims. (Cl. 149-92) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the pay ment of any royalties thereon or therefor.
This invention relates to low density explosives and in particular to a low density, cellular explosive foam.
This is a related application to claim the subject matter required to be divided out of copend-ing application Serial No. 451,723, liled August 23, 1954, no-W Patent No. 2,845,025 issued July 29, 1958, and entitled Low Density Cellular Explosive Foam and Products Made Therefrom, and which was a continuation application of then copending and now abandoned application Serial No. 185,900, tiled September 20, 1950, and entitled Low Density Cellular Explosive Foam. This is a divisional application of copending application Serial No. 528,566, filed August 15, 1955, now Patent No. 2,768,072 issued October 23, 1956, and entitled Method of Producing a Low Density Explosive which was a continuationinpart application of then copending and now abandoned application Serial No. 300,367, filed June 30, 1952, and entitled Low Density Cellular Explosive Foam which was a divisional application of Serial No. 185,900, supra.
The general object of the invention is to provide an explosive having a cellular foam structure which, because of such foam structure, is of relatively low density, is buoyant with respect to water, and of greater and more rapid shattering effect than the same weight of high density explosive.
It is also an object of the invention to provide an explosive having a cellular foam structure which is set and rigid and which is relatively strong and tough.
It is a further object of the invention to provide an explosive having a cellular foam structure which may be cast or molded into a particular shape prior to the setting or assumption of rigidity.
Other objectives will be apparent from the following description and from the drawings, hereto attached, which are illustrative of the method of making the cellular explosive and of the preferred embodiments of the invention.
In these drawings:
FIG. 1 is a flow chart of the dynamic air-set method of this invention;
FIG. 2 is a ow chart of the chemical blowing method of this invention;
FIG. 3 is a diagrammatic transverse section through a conventional floating mine;
FIG. 4 is a diagrammatic transverse section through a oating mine of the type illustrated by FIG. 3 but containing a relatively large quantity of the foamed explosive of this invention cast in situ;
FIG. 5 is a diagrammatic sectional-elevational View of a floating mine in which the shell is comprised of the molded foamed explosive of this invention encased in light weight metal or impregnated fabric and shows the increased high explosive charge possible with this type of construction;
FIG. 6 is a diagrammatic longitudinal section through a floating, harbor mine showing the combination in the explosive charge of the conventional high density explosive with the foamed explosive of this invention;
FIG. 7 is a diagrammatic longitudinal sectional-elevational view of a torpedo carrying a charge of high density explosive and foamed explosive of this invention; and
FIGS. 8 and 9 are a diagrammatic longitudinal sectional-elevational View and a transverse sectional view taken on line 9 9 of FIG. 8, respectively, of a radio controlled homing vessel showing the foamed explosive of this invention cast and molded within the structure of the double walled hull.
Heretofore, it has been the practice, in the manufacture of explosive, to produce them with a relatively high density in order to have a great explosive effect in a given volume. Now a requirement has arisen in which it is desirable to have an explosive which is buoyant and which may have a greater explosive effect which may be additive to that of the conventional high density explosive. This requirement is present not only in oating mine structures, but also in the guided surface (the Socalled homing) vessels.
This inventor has met this requirement by providing a foam type explosive which resembles in physical appearance and characteristics cellular polystyrene or cellular acetate. It is relatively strong andtough and the density thereof can be varied by formulation Within the range of from about 5 to about 50 pounds per cubic foot.
The cells of the foamed and set structure of the explosive are substantially non-communicating and referred to as closed-cells in contradistiction to spongy open-cells. Therefore, a molded plate of this material is relatively impervious to gas and water. In comparison with balsa wood, which has a buoyancy of about twenty pounds per cubic foot after twenty-four hours immersion under a ten foot head of water, this cellular explosive has a buoyancy of from about 20 to about 50 pounds per culbic foot under similar conditions.
The following explosives, as well as others, can be prepared in foam or cellular form: (l) Trinitrotoluene (2) Nitrocellulose (tri, hexa and dodeca nitrocellulose) (3) Pentaerythritol (4) RDX (cyclo triemethylenetrinitramine) The foamed explosive consists essentially of any one of the above explosives bonded by a foaming plastic.
A foaming plastic is a plastic which will be of solid cellular structure when it is allowed to set after being foamed either by chemically or mechanically blowing gas or air through it while in the liquid stage as will appear in the example set forth below.
This inventor has found that polyesters of ethylene glycol-maleic anhydride intermixed with monomeric styrene is ideally suited as a resin in the carrying out of this invention. This resin is shown and described along with other resins which also are suitable in Carleton Ellis Patent 2,255,313, which is incorporated by reference and forms a part of this specification. Of course a ller as used in the examples of Ellis is unnecessary and not used although such use would still fall Within the scope of what is considered to be the present invention.
An example of one of these resins is that produced by heating 500 parts of maleic anhydride and 541 parts diethylene glycol in an oil bath at 220-225" C. for 7 hours while bubbling nitrogen gas therethrough to provide an inert atmosphere. The diethylene glycol maleate formed is a light-colored viscous liquid of acid number 7.1. Eighty-tive parts of this liquid are mixed with 5 parts monomeric styrene in a glass container with a mechanically driven stirrer. The resultant liquid is a satisfactory stock solution and has 3% (by weight) benzol peroxide (curing agent) and 31/2% (by weight) cobalt naphthanate (accelerator) added to it just prior to its use.
' priate curing agent.
to as settingk agents. f
` blowingk method. These These bonding thermosetting polyester resins are well known in. the field of resin chemistry and their specific compositions form no part of this invention. The requirernents thereof are that they be compatible with solutions ofthe explosives, that they gel at room tern- 1 sivel sui'cient to prevent the escape of air therefrom and yet be suliiciently fluid forefcient molding aud casting. The rateA of setting of these resins is controlled by the addition thereto of a relatively' small proportionl (from about 2% to' about 4% by weight) of an approinclude: benzol peroxide, ditertiarybutyl peroxide, cumenehydro peroxide, methylisobutyl ketone peroxide,
'and dibenzaldeperoxide. yThe choice ofthe 'particular curing agent used dependsupony its compatibility with the solution of the1 resin'and the explosive andthe rate, of curing desired. Also an accelerator, such ascobalt naphthanate may be `added in a proportional amountl of from about 2%' to about 5% by weight to give additional 'control' on the rate of geliing and setting of the resin.
These curing agents and accelerators are herein referred Commercially available resins which have been foundk to be suitable as a bond for the foamed explosives of this l invention are yMR-28C' and 29C by Marco Chemicals,
Inc., Selectron 5003 and 5016 produced and-marketed l 'by the Pittsburgh Plate Glass Company, Laminac 4128, 4129 and 41116 produced and marketed by the American Such agents have been found to Cyanamid Company, and Paraplex P-43 by Rohm andy f Haas Company.
Two methods of the preparation of foamed explosive are preferred by this inventor. 'Ihese are (l) the soealled dynamic air-set method, and (2) the chemical methods differ from each other mainly in the methodof introduction of the resinous solution of the explosive.. In the dynamic air-set method (reference being had to FIG. lof the drawings), a solution of the explosive'in styrene, ether, acetone, or a mixture of some of these or other solvents is made as indicated at 110. Only as much explosive may be dissolved as Will go into the solution with or without the -application of a moderate heat, and with staying below the decomposition temperature of the cxplosive, A solution of a foaming plastic such as polyester type resin, a curing agent or catalyst and an accelerator is prepared as shown at 12 in the proportionate amounts above indicated. From about to about 30% by volume of the liquid resin solution is mixed with the solution of the explosive as shown at 14.
As an example, the diethylene glycol maleate with monomeric styrene is mixed with benzol peroxide and cobalt naphthanate as specifically set forth above. About 20% by volume of this solution is mixed with a saturated solution of TNT dissolved in styrene.
The curing agent and accelerator will cause the resin to gel in about 15 minutes and to set permanently in about one hour. The mixture of solutions of the explosive and resin is stirred for about 5 minutes as indicated at 15 and allowed to rest for about 5 minutes. Compressed air from a source (not shown) is introduced into blowing chamber 18 and thence through yforaminous member 20 which may be a glass frit or metal screen of a mesh in the range of from 75 to 300 and through the mixture at 14 for about 3 minutes which will foam the said mixture. The foamed mixture is then poured into molds or other containers within the remaining 2 minutes of the 15 at which time the foamed explosive gels or sets up and in one hour becomes a hard cellular mass. By a proper control of the viscosity of the mixture, above referred to, air bubbles do not appreciably escape therefrom after the completion of the blow or during the period that the mixture is in the mold prior air or gas into f addition of a curing agent and an accelerator to a foaming plastic in the proportionate amounts above indicated and as shown at 26. The foaming plastic may be a poly-l ester type resin as above described or other foaming plastics set lforth below. In either casethey are adjusted to gel in about fifteen minutes and to set. in aboutl l one hour as in the process'a-bove described. The solutions of. the lexplosive and the resin are conducted into mixing chamber Z8, the solution of the resin being added. in the proportion by volume of from 10% to 30%. In this chamber there is added to the mixture from 10% to 30% by volume of 1a chemical blowing agent such as diazoaminobenzene or toluene diisocyanate. The mixture is stirred, as indicated at 30 for from tive to ten .minutes and is then poured or cast into molds as indicated at 32. The molds are thenl heated as indicated at 33 toa temperature of about 120 C. but not above decomposition temperature of the explosive atk which temperature the blowing agent evolves a relatively large rvolume yof gas which causes the massto expand forming a cellular structure. 1 1 1 1 The range inA composition, .ony a percentage weight 1 f basisy at various temperaturesof for-mation, of the foarned explosives of this invention is givenk inthe following table:
PRei-eent Plrceut Ircent ange ange ange C. Temp. Solvent in Explosive in in Comp. Comp Comp.
ofRcsin 20T acetone 10-30 10-30 10-30 10-30 10-30 10-30 10-30 5 10 10 25 eyclohexal0 none. 60 acetone 15 cyelohexa- 15 none. do 78 HBX-l & 2 12 10 acetone 67 HBX-l &2 18 15 cyclohexa- 60 HBX-l dz 2..- 25 15 none.
Other examples using different foaming plastics are set forth below and it will be understood by a chemist familiar with the art that such foaming plastics are capable of use with the dynamic air-set method as well as the chemical blowing method.
A chemically blown foamed explosive can be prepared by using toluene diisocyanate and alkyd resins to produce a composition referred to in the art as polyurethane foam resins. Carbon dioxide is liberated in the reaction to cause the plastic to foam and thus, in effect, the ingredients act as their own blowing agents.
For purposes of this invention an alkyd resin having following composition is prepared:
7.6 parts by weight glycerol 5.0 parts by Weight adipic acid 1.0 part by weight phthalic anhydride These ingredients are refluxed in a glass lined container in an atmosphere of carbon dioxide and at a temperature of about 165 C. until an acid number of about 55 and hydroxyl number of about 415 are reached. The alkyd resin thus formed is then cooled to room temperature for further use as described below.
Ratios of explosive to resin by weight range from 10% resin to explosive to 50% resin and 50% explosive.
Optimum results are obtained where to 30% of resin is used with 90 to 70% of explosive. The following composition is prepared in the following manner to produce a polyurethane explosive foam:
(A) 150 parts by weight of alkyd resin as prepared above.
(B) 1350 parts by weight of TNT contained in warm acetone (about 30 C.).
(C) 140 parts by weight 2-4 M-toluene diisocyanate.
(D) 58 parts by weight-of water.
Ingredients (A) and (B) are first mixed in a mechani# cal mixer such as a Hobart of suitable capacity. Then ingredient (C) is mixed therewith followed by ingredient (D) which is mixed therewith or stirred for about 20 minutes.
This mixture is then poured into a suitable metal mold calculated to produce the desired density which in this case is about l0 pounds per cubic foot. The closed mold containing the mixture is then placed in a hot air oven at about 73 C. for about one hour after which the mold is removed from the hot air oven and cooled to room temperature and the explosive TNT foam is removed therefrom.
Another example of a manner of practicing the invention, which in this case utilizes a polyvinyl chloride resin with a copolymer of vinyl chloride and vinyl acetate, follows:
About 100 parts of a polymerized material consisting of about 85% by weight of polyvinyl chloride and about by Weight of copolymers of vinyl chloride and vinyl acetate are mixed in a Hobart mixer with about 80 parts of tricresyl-phosphate (plasticizer) until the polymer is thoroughly dispersed. About 25 parts of P.P'oxybis benzene sulfonyl hydrazide (chemical blowing agent) is then added and mixed thoroughly. (Diazoaminiobenzene or 40% dinitroso pentamethylenetriamine may also be used as chemical blowing agents.) About 3 parts of lead stearate (stabilizer) is also added and mixed thoroughly.
About 80 parts by weight of TNT in a fine state of division such as will pass through a Standard Sieve No. 50 or 100 (as delined by the American Society for Testing Materials Standards) is then added to the above composition and the mixture worked to a uniform consistency with a stiff blade mechanical mixer. About 10% by weight of the combined ingredients of acetone is then added slowly and the mass mixed to uniform consistency.
A suitable charge or volume of this product is placed in a steel mold of desired shape. Such an example would be a mold 6 x 6" x 1/2 of heavy steel wall construction as established in the art or industry for processing these products. The mold cavity is completely illed, and the charged mold placed in between press platens at a temperature of about 160 C. The press is then closed and about 5000 p.s.i. pressure applied to the mold and held for about minutes at this temperature. After this time the pressure is reduced to atmospheric and the mold removed from the press. rThe mold is opened and the molded piece is removed. It is then placed in a hot air oven or chamber at about 120 C. for about 60 minutes when the piece will then grow or expand to about double its volume producing a density between 4 and 7 pounds per cubic foot. The density can be considerably changed by varying the charge into the mold and the weight of explosive incorporated into the mold.
An epoxy resin can be used in carrying out the invention in a manner such as shown by the speciiic example below.
About 110 parts of a diphenol such as bisphenol A is dissolved in 80 parts thereof of a 20% Water solution of sodium hydroxide. About 188 parts of epichlorohydrin is slowly added to the mixture at about 75 C. over approximately a 30 minute period. The resulting resin melts at about 65 C.
Explosive foam mixture is prepared using the following ingredients:
Parts Epoxy resin as above 98.0 Ammonium bicarbonate (blowing agent) 10.0 Diglycol laurate S (wetting agent) 3.5 Piperidine (curing agent) 2.0
TNT 400.0
Epoxy resin as above is heated to the liquid stage at about 75 C. The ammonium bicarbonate previously dispersed in diglycol laurate S is then added and stirred thoroughly. The TNT is then added and stirred, followed by the piperidine which is then added and mixed for about 5 minutes. The liquid phase life at this stage is limited to about 30 minutes; otherwise, polymerization or solidification sets in. The mixture is then transferred to a heated metal mold or box held at about 75 C. for about 2 hours when the explosive foam is made. The explosive completely fills the container. Of course the explosive foam mixtures may also be made from nitrocellulose, pentaerythritol, and cyclo trimethylenetrinitramine. The density of the explosive foam is controlled by varying the percentage of explosive going into the composition and the weight of mix going into the heated mold cavity or box as described above.
This particular explosive foam composition may also be cured using other amine reagents such as diamines, triamines or quaternary amines such as, diethylenetriamine and triethylenetetramine. Commercial resins such as Shell Chemical Company Epon resins such as Epon 834, Epon 864, and Epon 1001 and mixtures of these various resins may also be used. Cure or hardening is accomplished by using any one of the amines stated above.
Referring further to the drawings, in FIG. 3 a conventional iloating mine is shown diagrammatically and generally at 40. The mine comprises a metallic case 4Z, contact elements 44 which are in electric circuits 46 with the detonating or exploding device 48. This exploding device detonates the charge of high explosive 50 when any one of the elements 44 is actuated by contact with an object in the water. The interior volume of this type of mine is comprised of about 50% air space as shown at 52.
In FIG. 4 the air space of the mine shown in FIG. 3 is filled with the foamed explosive of this invention as shown at 54 which has been cured and set in place. This foamed or cellular explosive not only gives an additive eect to the brisance of the high explosive, but in the event of leakage through metallic shell 42 due to erosion or corrosion thereof, the buoyancy of the mine will be maintained substantially as that existing when the mine is in leakproof condition.
FIG. 5 is illustrative of an embodiment of this invention in which the shell of the mine is comprised of molded cellular explosive 56 covered on the exterior and interior faces with a relatively thin layer of metal or impregnated fabric 58. The increased buoyancy of this type of construction over the conventional, heavy metallic case mine is readily apparent. in fact, the buoyancy is so much greater that substantially the entire interior space of the mine may be lled with high density explosive thereby producing a mine of greatly increased shattering effect when also considered in the light of the additive explosive elfect of the cellular explosive comprising the shell.
FIG. 6 is a sectional illustration of a floating harbor mine showing the arrangement of a metallic casing 60, a high density explosive charge 62, detonating or exploder device 64, actuating contact element 66 and foamed explosive of this invention 68 surrounding the high explosive charge and exploder device and filling the air space normally present within the casing of this type of mine. In the event of leakage of water through the casing due to corrosion thereof or otherwise, the foamed explosive prevents loss of buoyancy and the normally resultant loss of the mine.
FIG. 7 is a sectional-elevational view of a torpedo shown generally at 70 in which the foamed explosive 72 of this invention fills the normally present air-space within the shell 74. The legends in this figure are believed to be self-explanatory. In this embodiment of the invention, the overall buoyancy of the torpedo is less than that of the torpedo having the conventional air space. But the total shattering effect of the explosion is much increased by this additional quantity of foamed high explosive. In charging this cellular explosive into this air space in the torpedo, the foamed explosive is poured into this space immediately prior to the gelling thereof. The space is completely filled and upon the curing and setting of the resin component the cellular explosive becomes rigid and reinforces the sidewalls of the shell.
FIGS. 8 and 9 show the application of the foamed high explosive of this invention to the structure of an electronically controlled homing vessel in sectional-elevational views. Here the double walled hull 90 is shown provided with radio control 92 for motor drive mechanism 94. High density high explosive 96 substantially fills the interior of hull 90 surrounding the exploder device 98. The detonating contact element is shown at 99. T he space within the double wall structure of the hull is filled with the foamed high explosive of this invention as shown at 100. As in the case of the torpedo above-described, the foamed explosive is poured into this hull wall spaced irnmediately prior to the gelling and after setting the foamed cellular explosive mechanically reinforces the structure. The advantage of this type of construction of these homing vessels is that the shattering effect of the explosion is greatly increased and that in the event of leakage through the outer wall of the hull due to corrosion or to any other cause the buoyancy of the vessel is maintained.
It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.
I claim:
1. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and impervious to the passage of fluid, said foam being a homogeneous mixture of about 90 percent to about 70 percent by weight of an explosive from the group consisting of trinitrotoluene, nitrocellulose, pentaerythritol, and cyclo trimethylenetrinitramine and a binder of about 10 percent to about 30 percent by weight of a thermosetting polyester resin.
2. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of uid, said foam being a homogeneous mixture of about 8S percent to about 67 percent by weight of trinitrotoluene and from about 12 percent to about 33 percent by weight of a thermosetting bonding polyester resin.
3. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about 85 percent to about percent by weight of nitrocellulose and from about 15 percent to about 40 percent by weight of a thermosetting bonding polyester resin.
4. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about 85 per cent to -about 75 percent by weight of pentaerythritol and from about 15 percent to about 2.5 percent by weight of a thermosetting bonding polyester resin.
5. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and are impervious to the passage of fluid, said foam being a homogeneous mixture of about percent to about 55 percent by weight of cyclo trimethylenetrinitramine and from about 35 percent to about 45 percent by weight of a thermosetting bonding polyester resin.
6. An explosive whose density is less than that of water which comprises a foam wherein substantially all the cells are closed and impervious to the passage of uid said foam being a homogeneous mixture of about 90 percent to about percent by weight of trinitrotoluene and from about 10 percent to 30 percent of an alkyd resin.
References Cited in the file of this patent UNITED STATES PATENTS 2,062,011 Norman Nov. 24, 1936 2,165,263 Holm July 11, 1939 2,171,379 Wahl Aug. 29, 1939 2,334,149 Ripper Nov. 9, 1943 2,349,048 Mackey May 16, 1944 FOREIGN PATENTS 674,447 Great Britain June 25, 1952

Claims (1)

1. AN EXPLOSIVE WHOSE DENSITY IS LESS THAN THAT OF WATER WHICH COMPRISES A FOAM WHEREIN SUBSTANTIALLY ALL THE CELLS ARE CLOSED AND IMPERVIOUS TO THE PASSING OF FLUID, SAID FOAM BEING A HOMOGENEOUS MIXTURE OF ABOUT 90 PERCENT TO ABOUT 70 PERCENT BY WEIGHT OF AN EXPLOSIVE FROM THE GROUP CONSISTING OF TRINITROTOLUENE, NITROCELLULOSE, PENTAERYTHRITOL, AND CYCLO TRIMETHYLENETRINITRAMINE AND A BINDER OF ABOUT 10 PERCENT TO ABOUT 30 PERCENT BY WEIGHT OF A THERMOSETTING POLYESTER RESIN.
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Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3198677A (en) * 1962-07-27 1965-08-03 Atlantic Res Corp Foamed polyurethane gas-generating compositions containing inorganic oxidizer
US3206341A (en) * 1962-02-12 1965-09-14 Onera (Off Nat Aerospatiale) Fuel blocks, in particular for use in rocket engines
US3288661A (en) * 1965-10-08 1966-11-29 Hercules Inc Aerated aqueous explosive composition with surfactant
US3288658A (en) * 1965-07-20 1966-11-29 Hercules Inc Aerated explosive compositions
US3376176A (en) * 1964-11-17 1968-04-02 Atlas Chem Ind Aqueous inorganic nitrate salt slurry containing nitric acid and entrapped air
US3382117A (en) * 1967-01-06 1968-05-07 Intermountain Res And Engineer Thickened aqueous explosive composition containing entrapped gas
US3447980A (en) * 1967-01-20 1969-06-03 Us Army Castable explosive containing tnt and a reaction product of a diisocyanate and 1,4-butyleneoxide polyglycol
US3457126A (en) * 1967-05-16 1969-07-22 Ici Australia Ltd Aqueous explosive composition containing a porous water insoluble synthetic organic polymeric cellular material
US3710573A (en) * 1967-07-05 1973-01-16 Us Army Hydrazine monopropellant process using a gas generating bed
US3730093A (en) * 1966-12-27 1973-05-01 North American Rockwell Explosive apparatus
US4025369A (en) * 1971-02-08 1977-05-24 The United States Of America As Represented By The Secretary Of The Navy Deflagrative epoxy foam material
US4063508A (en) * 1976-03-09 1977-12-20 The United States Of America As Represented By The Secretary Of The Air Force Munition dispersion by interstitial propelling charges
DE3309045A1 (en) * 1982-03-13 1983-09-15 Kabushiki Kaisha Nippon Kanko Shikiso Kenkyusho, Okayama DICHROITIC DYES FOR LIQUID CRYSTALS AND LIQUID CRYSTAL COMPOSITIONS
US4722280A (en) * 1986-11-19 1988-02-02 Sri International Molded low density controlled pressure solid explosive material and method of making same
EP0340761A3 (en) * 1988-05-06 1990-09-12 Dynamit Nobel Aktiengesellschaft Propulsive charges for big calibre projectiles

Citations (6)

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US2062011A (en) * 1933-09-13 1936-11-24 Hercules Powder Co Ltd Explosive
US2165263A (en) * 1939-07-11 Macfie holm
US2171379A (en) * 1938-09-28 1939-08-29 Du Pont Ammonium nitrate explosive
US2334149A (en) * 1938-02-18 1943-11-09 American Cyanamid Co Explosive
US2349048A (en) * 1940-09-04 1944-05-16 Du Pont Smokeless powder
GB674447A (en) * 1950-04-18 1952-06-25 Nobel Francaise Soc Improvements in and relating to an explosive containing urea-formaldehyde resin foam

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2165263A (en) * 1939-07-11 Macfie holm
US2062011A (en) * 1933-09-13 1936-11-24 Hercules Powder Co Ltd Explosive
US2334149A (en) * 1938-02-18 1943-11-09 American Cyanamid Co Explosive
US2171379A (en) * 1938-09-28 1939-08-29 Du Pont Ammonium nitrate explosive
US2349048A (en) * 1940-09-04 1944-05-16 Du Pont Smokeless powder
GB674447A (en) * 1950-04-18 1952-06-25 Nobel Francaise Soc Improvements in and relating to an explosive containing urea-formaldehyde resin foam

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3206341A (en) * 1962-02-12 1965-09-14 Onera (Off Nat Aerospatiale) Fuel blocks, in particular for use in rocket engines
US3198677A (en) * 1962-07-27 1965-08-03 Atlantic Res Corp Foamed polyurethane gas-generating compositions containing inorganic oxidizer
US3376176A (en) * 1964-11-17 1968-04-02 Atlas Chem Ind Aqueous inorganic nitrate salt slurry containing nitric acid and entrapped air
US3288658A (en) * 1965-07-20 1966-11-29 Hercules Inc Aerated explosive compositions
US3288661A (en) * 1965-10-08 1966-11-29 Hercules Inc Aerated aqueous explosive composition with surfactant
US3730093A (en) * 1966-12-27 1973-05-01 North American Rockwell Explosive apparatus
US3382117A (en) * 1967-01-06 1968-05-07 Intermountain Res And Engineer Thickened aqueous explosive composition containing entrapped gas
US3447980A (en) * 1967-01-20 1969-06-03 Us Army Castable explosive containing tnt and a reaction product of a diisocyanate and 1,4-butyleneoxide polyglycol
US3457126A (en) * 1967-05-16 1969-07-22 Ici Australia Ltd Aqueous explosive composition containing a porous water insoluble synthetic organic polymeric cellular material
US3710573A (en) * 1967-07-05 1973-01-16 Us Army Hydrazine monopropellant process using a gas generating bed
US4025369A (en) * 1971-02-08 1977-05-24 The United States Of America As Represented By The Secretary Of The Navy Deflagrative epoxy foam material
US4063508A (en) * 1976-03-09 1977-12-20 The United States Of America As Represented By The Secretary Of The Air Force Munition dispersion by interstitial propelling charges
DE3309045A1 (en) * 1982-03-13 1983-09-15 Kabushiki Kaisha Nippon Kanko Shikiso Kenkyusho, Okayama DICHROITIC DYES FOR LIQUID CRYSTALS AND LIQUID CRYSTAL COMPOSITIONS
US4722280A (en) * 1986-11-19 1988-02-02 Sri International Molded low density controlled pressure solid explosive material and method of making same
EP0340761A3 (en) * 1988-05-06 1990-09-12 Dynamit Nobel Aktiengesellschaft Propulsive charges for big calibre projectiles

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