US2537039A - Gelatinous explosive composition - Google Patents

Description

Patented Jan. 9, 1951 UNITED STATES PATENT OFFICE Hercules Powder Com corporation of Delaware pany, Wilmington, Del., a

7 No Drawing. Application June 12, 1947,

- Serial-No. 754,275

6 Claims.

This invention relates to explosives and more particularly to a gelatinous explosive and a method for manufacturing such an explosive.

Gelatinous and semigelatinous dynamites have been made for years using a nitrocellulose-nitroglycerin gel. As early as 1878', A. Nobel developed a dynamite of this type. For many years the lowest strength of gelatin dynamite: made was a forty per cent straight gelatin dynamite containing 35% of nitroglycerin In the development of economical gelatin dynamites which still retained good water resistance, the nitroglycerin content was gradually reduced to 25 %-27 while incorporatng large percentages of ammonium nitrate to maintain a high strength. This was about the minimum nitroglycerin content that could. be achieved while maintain ng a really plastic gelatinous consistency adapted to packing on the gelatin-type cartridging machine. However, subsequently, semiplastic explosives of high strength and good water resistance were obtained with as little as 20% of gelatinzed liquid explosive. These are called semigelatin dynamites, and are generally packed on a Hall-type packing machine which is more economical than using the gelatin-type cartridging machine.

Thus, the principal object of this invention is to produce a gelatinous explosive even lower in nitroglycerin content or even without nitroglycerin but of the same high strength.

Another object of this invention is to produce a low nitroglycerin content dynamite having the properties of anitrocellulose-nitroglycerin gelatinous dynamite.

Another object of this invention is to improve and maintain uniform'ty of the properties of nitrocellulose-nitroglycerin gelatinous dynamites.

Still another object of this invention is to provide a methmod of manufacturing a dynamite possessng the qualities set forth in the aforementioned objects.

Other objects of the invention will appear hereinaften. the novel featuresand comhinatitons being set forth in: the appended claims.

Now, in accordance with this invention, there is provided an improved gelatinous explosive comprising lrigh explosive material. and a small amount of a nonexplosive gel- Thenonexplosive gel comprises a. Water-soluble nonvolatile petr0l eum hydrocarbon base material, thickened and.

tackified with a petroleum-soluble elastomeric gelling agent. Also, in accordance with this invention, there is provided a method for incorporating the nonexpl'osive gel into a high explosi've composition to give a gelatinous explosive possessing good sensifivity and plasticity.

The objects and nature of the invention have been indicated in a general way. Preferred embodiments of the invention are specifically set forth in the followin tables and examples.

TABLE I Low NG Content Dyna- Low NG Content Dynamite Containmg Nonexplosive Gel Regular Semigelatin Dynamite Example 1 Nitroglycerim Dinitrotoluene (DNI Oil) N itrocellulose Count. 1%

Detonation Velocity, m./s Sensitlveness. in Water Resistance, Per Cent Good Plasticity Ingredients Heat Exchange Oil Polyisobutylene (M. W. 140,000) Oxygen Balance, ler Cent- 1 77 67 1 Excellent: I Excellent Examples shot with No. 6 sttengthblastingcap.

3 With reference to Table 1, it willbe seen that the regular semigelatin dynamite of Example 1 had excellent plasticity while the low nitroglycerin content dynamite of Example 2 had no plasticity and was unsuitable. In contrast thereto the low nitroglycerin content dynamites of Examples 3 and 4 containing a nonexplosive gel had excellent and good plasticity characteristics, re-

TABLE 3 The effect on properties of high ammonia dynamites when the percentage of nonemplosive gel 28 named Example 14 15 16 17 18 19 20 Ingredients Standard Plastic Plastic Plastic Plastic Plastic Plastic Nitroglycerin. .per cent 13. 4 14. 8 l4. 14. 0 14. 0 14. 8 13.0 Nitrocellulose 0. 1 0.2 0.2 0.2 0.2 0. 2 0.2 Nonexplosive Gel. 1 1.0 1 1.5 1 1.7 1 2.0 1 3.0 2 5.0 Ammonium Nitrate- 72. 71. 5 71. 5 71.5 71. 5 71.0 72.3 Sodium Nitrate--- 5.0 7.0 8. 8 8. 6 8. 3 10.0 8. 0

Oxygen Balance per cent +5. 9 +7.1 +7.7 +7.0 +5. 8 +6. 7 1.4 Coun 120 114 109 108 109 103 120 Detonation Velocity (BL/S60.) 3, 500 2, 920 2, 885 2, 820 2, 530 2, 440 Sensitiveness inches 24 36 16 8 3 Water Resistance, Per cent 00 57 67 71 77 -10 Plasticity None Good Excellent Excellent Good Excellent Excellent 1 Heavy heat exchange oil polyisobutylene 5% (M. W. 140,000). 1 Light lubricating oil 95%, polyisobutylene 5% (M. W. 80,000).

The examples in Table 3 show that a good degree of plasticity is obtained with as little as 1% of the nonexplosive oil gel, and indicate a preferred range of 1 to 3% for the gel content in spectively, and in addition had good gap sensitiveness. The dynamites of Examples 3 and 4 make excellent semigelatins despite their low nitroglycerin content.

TABLE 2 The efiect on properties of high ammonia dynamites containing nonexplosive gel when the nitroglycerin content is varied Example 5 6 v 7 i s 9 10 11 12 2 13 In redients gigi Special Special Special Special Special Special Special Special g gelatin Plastic Plastic Plastic Plastic Plastic Plastic Plastic Plastic Nitroglycerin percent 18. 0 16. s 14. 8 14. c 13. 4 13. o 9. 0 7. 0 5. 0

NT Oil 2.0

N1trocellulose 0.3 0. 2 0. 2 0. 2 0:1 0. 2

Nonexplosive Gel--- 1 2. 0 1 2.0 1 2. 0 1 2. 0 2 5. 0 3 3. 0 4 3. 0 3 3. 0

Ammonium Nitrate 65. 5 68. 6 71. 5 71. 5 72. 5 72. 3 80. 0 81. 5 86. 0

Sodium Nitrate 8.3 9. 5 8. 5 8. 3 8. 5 8. 0 7. 0 6. 5 5. 0

Wood Pulp 1. 0 1. 0 1. 0 1. 0 0. 5 1. 0 0. 5 1. 5 0. 5

Ivory Meal- 2. 4

Cornstarch 2. 0 1. 4 l. 5 1. 0 2. 5

Chalk 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5

Oxygen Balance +7. 0 +7. 1 +7. 1 +5. 8 +6. 9 1. 4 +7. 0 +6. 7 +7. 0

Count, 1 ,4 x 8 in 106 106 113 e 109 V 103 120 120 130 120 Detonation Velocity (m./sec.) 3, 3, 3, 230 2, 820 2, 765 2, 440 2, 200

Sensitiveness, in 14 16 24 8 24 1 l) 8 ghot 1 o. 8

Water Resistance, Per Cent Good 78 79 V 58 71 73 10 32 Plasticity Good Excel Very Good Very Excel- Excel- Excel- Good lent Good Good lent lent lent Examples shot with a No. 6 strength blasting cap unless otherwise noted. 1 Heavy heat exchange oil 95%, polyisobutylene 5% (M. W. 140,000).

2 Light lubricating oil 95%, polyisobutylene 5% (M. W. 80,000).

1 Petrolatum 95%, polyisobutylene 5% (M. W. 80,000).

4 Naphthenie lubricating oil 95%, polyiscbutylene 5% (M. W. 80,000).

With reference to Table 2 for dynamites containing nitrocellulose, it will be observed that semigelatin dynamites 6, '7, 8, and 9 can be made order to'secure good plasticity and water resistance without excessive loss in sensitiveness.

TABLE 4 The efiecton the properties of czctra gelatin 'dyna'mites of substituting nonexpiosive gel for a portion of the nitroglycerin Example .4 21 22 23 24 25 26 27 Grade 60% 60% 60% 40% 40% 40% 40% Ingredients Standard Plastic Plastic Standard Plastic Plastic Plastic Nitroglyeerin 28.5 25. 23.5 22.0 i .20. 0 20. 0 Nitrocellulose w 0.45 0. 35 0.35 0. 30 0.30 0. 30 Ammonium Nitrate 30. 8 35. 8 37.8 15. 00 18.0 -18.1) Sodium Nitrate 28.25 29.85 29.35 49.'2 28. 2 28. 2 Ivory Meal 5. 0 2. 2.5 2. 5 Cornstarch 5. 0 5.0 '5. 0 7.0 7. 0 7.0 Wood Pulp 1.0 1.0 1.U 1J0 1. 0 2L0 Sulfur V Chalk 1.0 1.0 1.0 1. 0 1.0 1.0 Nonexplosive Gel. 2.0 .2.10 -2. 0 l 2. 0 9 2.0

Oxygen Ba1ance per cent +6. 5 +6. 3 +6. 7 +6.15 +6. 4 6. 4 Oount .100 100 l 95 90 88 Leakiness days at 120 F.)- None None None None None None Sensitivity, in 16 16 6 10 Detonation Velocity, m/sec- 4, 870 I 3:, 630 2, 850 2, 230 2, 500 2, 285 Plasticity and Packing Satisfacsatlsfac- Satnsfac- Satisiac- Satisfac- Satisfac Satisfactory. tory. 'tory. 'tory. tory. 'tory.

1 Petrolatum95%, polyisobutylene, 5% (M. W. 140

.000). 2 Heavy heat exchange/0i] 95%, polyisobutylene 5% (M. W. 140,000).

TABLE 5 With reference to Table .5, the examples show the use of gelling agents including polyisobutylene and others. Particular examples of other nonexplc-sive gels are petrolatum-natural rubber gels and petrolatum-synthetic rubber gels. These gels gave properties which were satisfactory, although not so good as the petrolatum-polyisobutylene gel.

The effect on the plasticity and water resistance of low nitroglycerin content dynamites containing noneznplosive gels with various tackifying agents Example 28 29 30 31 Ingredients Standard Plastic Plastic Plastic Nitroglycerim 13. 4 l3. 5 13. 5 l3. 5 Nitrocellulose 0. 1 I0. 2 0. 2 0. 2 Ammonium Nitrate 72. 5 73.0 73.0 73.0 Sodium Nitrate 5.0 8.'8 8.8 8.8 Wood Pulp 0.5 1. O 1.0 1.0 Starch 4.0 IVOry M'Pal 4. (l Chalk 0. 5 D. 5 0. 5 0.5 N onexplosive Gel: V

Polyisobutylene M. W. 80,000 (5%111 petrolatum) 3:0 Natural Rubber (10% in petrolatum)- 3.0 Synthetic Rubber 1 (10% in petrnla firm) 3. 0 Oxygen Balancem per :cent. +5. 9 +6. .0 +6. 0 +6. 0 Count v 120 1 20 1 120 Water Resistance, Per'Oent Good .4 54 81 74 Plasticity- None Very Good Fair Fair A butadiene-styrene copolymer designated as Buna S.

TABLE 6 .Gelatinons explosives without nitroglycerin Example 32 33 34 35 '36 37 38 39 Ingredients 'Trim'trotoluene (fiaked)-. per cent 11. 5 Nitrostarch d0 30.0 Pentaerythritol Tetranitratedo E5 25 30 Oyclonite. don Ammonium Nitrate do 4750 86. 5 '97. 0 I 63 Sodium Nitrate..-" do. 19. 0 Aluminum (flaked)- do 1. 0 i j Nonexplos'ive Gel do '3. 0 1 2. 0 350 2 5:0 '10 7 i 5. 0 1 7. 0 Oxygen Balance..." do 3. l7 7 0 +7.34 26. 9 25.3 15..8 379 19. 2 Count 141 142 120 117 118 117 121 Sensitivity N 0. 6 No. 6 Detonation Velocity, m./sec 4, .730 7 4,880 5.140 Plasticity Good Very Very Very EXcBlf Excel- Excl- Excellent Good Good Good lent lent lent 1 Petrolatum :polyisobutylene 5% (M. W. 80,000). No. 81% in. byBin. paper. 2 Light lubricating oil 95%, no'lyisobutylene 5% (M. W. 80,000). 6 5 g. PETN 2 in. 'by8 in. can.

' Medium lubricating oil 92%, polyisobutylene 8% (M. W. 140,000). 4 Shows strcngthoficap or booster required to detonate charge and diameter of'package which is 1% in. by 8 inwithpapcrwiapper unless otherwise indicated.

' 5 g. PE'IN. l 5 haArmy cap.

The data in Table 6 show that explosives with good plasticity and varying degrees of sensitivity 7 can be prepared with explosives other than nitroglycerin by addition of the nonexplosive gel.

The foregoing examples show that a variety of gelatinous explosive compositions may be made in accordance with the present invention including dynamites low in nitroglycerin content, high ammonia dynamites, and explosives without nitroglycerin. The examples-further show that improved gelatinous explosive compositions may be formulated comprising high explosive ingredients, such as nitroglycerin or a mixture of nitric esters,such as nitroglycerin-nitroglycol, to obtain low freezing characteristics, dinitrotoluene, nitrocellulose, ammonium nitrate, sodium nitrate, trinitrotoluene nitrostarch, pentaerythritol tetranitrate, cyclonite, and equivalentmaterials, by incorporating in the composition a small proportion of a nonexplosive gel. Miscellaneous ingredients, such as wood pulp, cornstarch, ivory meal, chalk, aluminum (flaked or powdered), sulfur, and the like, may be included as conventionally utilized for the various types of explosives.

The nonexplosive gel in accordance with this invention is present in an amount from about 1 to about 10% by weightof the explosive composition. The gel comprises a water-insoluble,

, nonvolatile petroleum hydrocarbon base material,

such as petrolatum, paraffin-base oils, naph--v thene-base oils, and mixed or intermediate-base oils, anda petroleum-soluble elastomeric gelling agent, such as polyisobutylene, natural rubber, and synthetic rubber. Cylinder oil and the socalled bright stock, obtained in .the distillation, of petroleum into fractions, which is used in the manufacture of lubricating oils have also given good results. Amber petrolatum having a melt ing point in the order of 49 C. and oils having a viscosity of from about 200 to about 5000 centipoises at 25 C. have given good results. The

8 tate discharging the mix. This composition was then cut into small pieces and added to 18 pounds of the same oil in which it dissolved'during 8 hours stirring at 400-4=20 F. This mixture after cooling can be used in the preparation of the dynamite. quite sticky and, to facilitate handling, the cooled mixture was added to a Werner- Pfleiderer mixerand mixed with 10 pounds of cornstarch and 10 pounds of wood flour. This gave a dough which- This dough (nonexplosive An example for preparation of a semigelatin dynamite is as follows: A' 140 pound charge of nitroglycerin was placed in-a Talley'mix'bowl, 3%;

pounds of nitrocellulose was added, and the'mixpreferred base material is a naphthene-base oil having a viscosity of from about 1000 to about 2000 centipoises at 25 C. The preferred gelling agent is polyisobutylene having a molecular weight (M. W.) range of from about 80,000 to about 140,000. Itwill, of course, be understood that in combination with a given base, as the molecular weight of the polyisobutylene utilized is 7 increased, a lesser amount is necessary to give a desired degree of thickening and tack. It has been found that good results are obtained when the gelling agent is present in an amount of from about 2% to about 12% by weight of the non explosive gel. A I

The method for preparing the gelatinous explosive of this invention comprises mixing the nonexplosive water-insoluble base material andv the nonexplosive gelling agent to form a gel, reducing the gel into individual units, and mixing the units with explosive ingredients. In a preferred embodiment of the invention the car bonaceous ingredients of the explosive composition are premixed with the gel. The gel mixture is then reduced to individual units and then mixed culated through the jacket of the mixer to faciliture stirred for 5 minutes. Then the ammonium nitrate and carbonaceous ingredients (dope ingredients) were added, followed immediately by the dough (nonexplosive gel), which was added in four 10 pound loaf-shaped masses. Mixing was continued for 5 minutes longer. The mixed dynamite was then packed on a Hall packin machine in standard size cartridges.

Although cornstarch and Wood flour are specifically set forth as desirable constituents to latitude for incorporation of the ingredients of a specific explosive composition is afforded. Procedures other than the example given above which'were tried with'good results include the following: The gel and dry ingredients were mixed and then added to the nitroglycerin-nitrocellu- .lose pregel; the gel and dry ingredients were mixed and then the nitroglycerin and nitrocellulose were added at the same time and the mixing completed; and the nitroglycerin and nitrocellulose were gelled in a mixing bowl, the dry ingredients were then added and mixed, and then the gel was added and the mixing completed.

Thus it is seen that the method of this invention may be carried out with various modifica- 'tions without departing from its spirit and scope. 1

using a nonexplosive gel in addition to the nitrocellulose-nitroglycerin colloid the gelatinous properties and water resistance of the dynamite are improved and consistency remains uniform from batch to batch. Due to the decrease in nitroglycerin content,-less high nitroglycerin- .absorbent carbonaceous material is required.

One pound of a naphthenic oil was I smaller negative oxygen balance.

The removal of a portion of these absorbent materials makes way for an increased percentage of ammonium nitrate which is needed to maintain the original percentage weight strength of the dynamite. At the same time the addition of the nonexplosive gel which has a large negative oxygen balance makes up for the loss of the absorbent ingredients which have a somewhat The particle size and type of the dry ingredients may be conventionally selected to produce the required oxygen balance, density and absorbency. Moreover,

However, since the mixture is 9 the nonexplosive gel may be used as a binding agent with dry powdery dynamites and with granular or crystalline explosives or explosive mixtures to insure easy packaging and handling. Moreover, the method for manufacturing the gelatinous explosives of this invention insures uniformity and enhanced characteristics of the finished explosives.

In the foregoing examples the initiating device used was a No. 6 blasting cap unless otherwise noted. Where the explosive was too insensitive to be fired by such a cap, a No. 8 cap or an Army Engineer Corps special cap was used, as indicated. The No. 8 cap has about twice the strength of the No. 6 cap and the special Army cap has about twice the strength of the No. 8 cap. In examples where the explosive was formulated to be quite insensitive, a cap containing a charge of g. of PETN was used, as indicated.

The sensitivity of the explosive, as given in the tables, was determined by the halved-cartridge gap test. In this test, a 1%; inch by 8 inch cartridge is cut transversely in half. The two halves are separated at various distances until the separation at which propagation will just take place from one half of the cartridge to the other half is obtained. This distance is given in inches.

The count of the explosive, as given in the tables, is the number of 1 inch by 8 inch cartridges contained per fifty pounds of the explosive.

The water resistance of the explosive, as given in the tables, was determined by filling a Gooch crucible with the explosive and immersing it in water for a period of 24 hours. After immersion, the percentage of dry explosive was determined. This is designated as per cent good followed by the numerical percentage of dry explosive. All ammonium nitrate used in the examples was coated with a rosin-paraifin mixture.

What I claim and desire to protect by Letters Patent is:

1. A gelatinous explosive comprising high explosive material of the group consisting of liquid explosive nitric esters, nitrocellulose, nitrostarch,

and crystalline high explosives, and from about 1 to about 10% of a nonexplosive gel containing at least one substantially nonvolatile, water-insoluble petroleum hydrocarbon of the group consisting of petrolatum, parafiin base oils, naphthene base oils, intermediate base oils, cylinder oil, and bright stock, and at least one petroleum-soluble elastomeric gelling agent of the group consisting of natural rubber, petroleum-soluble synthetic rubber, and polyisobutylene.

2. A gelatinous explosive according to claim 1 in which the nonexplosive gel essentially comprises a naphthene base oil and natural rubber.

3. A gelatinous explosive according to claim 1 in which the nonexplosive gel essentially comprises a naphthene base oil and a petroleum-soluble synthetic rubber.

4. A gelatinous explosive according to claim 1 in which the nonexplosive gel essentially comprises a naphthene base oil and polyisobutylene.

5. A gelatinous explosive according to claim 1 in which the nonexplosive gel essentially comprises a naphthene base oil having a viscosity of 1000 to 2000 centipoises at 25 C. and from 2% to 12% by weight of the gel of polyisobutylene.

6. A gelatinous explosive according to claim 1 in which the nonexplosive gel essentially comprises petrolatum and polyisobutylene.

JACK M. DOWNARD.

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

UNITED STATES PATENTS Number Name Date 1,700,085 Scott Jan. 22, 1929 2,004,436 Jaeger June 11, 1935 2,067,213 Snelling June 1'7, 1935 2,383,906 Zinimer et al Aug. 28, 1945 FOREIGN PATENTS Number Country Date 39,388 Germany Jan. 13, 1866 6,258 Great Britain of 1892 8,470 Great Britain of 1898 24,702 Great Britain of 1913 Certificate of Correction Patent No. 2,537,039 January 9, 1951 JACK M. DOWNARD It is hereby certified that error appears in the printed specification of the above numbered patent requn'mg correction as follows:

Column 2, line 9, for methmod read method; line 13, for combinatitons read combinations; line 19, for Water-soluble read water-insoluble; columns 5 and 6, Table 6, footnote thereto, for 5 h. Army cap. read Sp. Army Gap;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 20th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oommz'ssz'oner of Patents.

Certificate of Correction Patent No. 2,537,039 7 January 9, 1951 JACK M. DOWNARD It is hereby certified that error appears in the printed specification of the above numbered patent requlrlng correction as follows:

Column 2, line 9, for methmod read method; line 13, for combinatitons read combinations; line 19, for water-soluble read water-insoluble; columns 5 and 6, Table 6, footnote 8 thereto, for 5 h. Army cap. read Sp. Army Gap;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 20th day of March, A. D. 1951.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents.

Claims (1)

1. A GELATINOUS EXPLOSIVE COMPRISING HIGH EXPLOSIVE MATERIAL OF THE GROUP CONSISTING OF LIQUID EXPLOSIVE NITRIC ESTERS, NITROCELLULOSE, NITROSTARCH, AND CRYSTALLINE HIGH EXPLOSIVES, AND FROM ABOUT 1 TO ABOUT 10% OF A NONEXPLOSIVE GEL CONTAINING AT LEAST ONE SUBSTANTIALLY NONVOLATILE, WATER-INSOLUBLE PETROLEUM HYDROCARBON OF THE GROUP CONSISTING OF PETROLATUM, PARAFFIN BASE OILS, NAPHTHENE BASE OILS, INTERMEDIATE BASE OILS, CYLINDER OIL, AND BRIGHT STOCK, AND AT LEAST ONE PETROLEUM-SOLUBLE ELASTOMERIC GELLING AGENT OF THE GROUP CONSISTING OF NATURAL RUBBER, PETROLEUM-SOLUBLE SYNTHETIC RUBBER, AND POLYISOBUTYLENE.