US3116188A - Desensitization of liquid explosives - Google Patents

Description

United States tary of the Navy No Drawing. Filed Aug. 3, 1960, Ser. No. 47,335 Claims. (Cl. 149-88) (Granted under Title 35, US. Code (1952), see. 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 payment of any royalties thereon or therefor.

This application relates generally to the ordnance art and is more particularly concerned with a new and improved mode of desensitizing liquid explosives to render them insensitive to detonation by accidental mechanical shock.

Prior to this invention those explosives which were considered to be dangerously sensitive to mechanical shock, e.g., nitroglycerin, were diluted with a non-explosive material which was compatible with the liquid explosives. This method of desensitization was subject to one disadvantage which detracted considerably from the usefulness of the desensitized explosive. That is, a rather large amount of desensitizing agent was required to produce an explosive of sufiiciently low sensitivity for safe handling and storage. Accordingly, explosives desensitized by this method were characterized by a marked reduction in the explosive power. Persons using these liquid explosives were faced with a dilemma which usually could be solved only by the unsatisfactory compromise of employing a minimum amount of desensitizer so that the explosive provided only marginal safety in its handling and use.

It is an object of this invention, therefore, to provide a mode of desensitizing liquid explosives which requires but a small amount of desensitizing agent to provide maximum safety.

Another object is the provision of a desensitized liquid explosive having high explosive power and providing maximum safety during handling and storage.

Another object of this invention is to provide a liquid explosive desensitized by a small quantity of a surface active agent.

These objects and many others will become more clearly apparent when the following specification is read and understood.

This invention is founded upon the discovery that the addition of small quantities of surface active agents to liquid explosives prevents the entry of shock and heat into the interior of the liquid explosive thereby preventing premature accidental detonation. By the term surface active is meant a substance which tends to concentrate in the surface phase of a mixture of itself and a liquid explosive or liquid propellant. Thus, a substance of this type, when mixed with a liquid propellant, will not be uniformly concentrated throughout the propellant but will be more concentrated at the surface of the mixture. The concentration of the surface active agent at the surface tends to prevent the entry of heat and shock into the body of the propellant or explosive.

These surface active agents are compounds of the type RCOOR R [COR and R R CO and R NO where: R is an alkyl containing from 2 to 5 carbons, R is an alkyl containing 4 to 6 carbons and R and R are alkyls containing from 4 to 8 carbons.

The class of surface active agents containing the nitro group does not, as might be expected, increase the sensitivity of a liquid explosive such as nitroglycerin or ethylene glycol dinitrate [EGDN]. On the other hand,

atent 3,115,188 Patented Dec. 31, 1963 EXAMPLE I 82 parts by weight of EGDN was poured into a beaker containing 18 parts by weight of tributyrin and the mixture was stirred gently. After complete mixing of the ingredients a five kilogram weight was dropped onto a small quantity of the explosive from a height of 60 centimeters. It was found that the explosive was insensitive to detonation upon impact by the weight.

Generally, an explosive used in military applications must also be insensitive to detonation by bullet impact. Accordingly, a second batch of EGDN was desensitized with tributyrate. It was found that in order to be insensitive to the passage of 30 caliber machine gun bullets through a container holding the desensitized explosive an additional amount of tributyrin was required. When 70 parts of EGDN was desensitized with 30' parts tributyrin, the mixture was insensitive to bullet impact.

EXAMPLE II parts by weight of nitroglycerin (NG) was poured with gentle stirring into 20 parts by weight of tributyrin. The resulting desensitized explosive was tested in the manner described in Example I and was found to be insensitive to impact by a 5 kilogram Weight at 60 centimeters.

A mixture of 30 parts tributyrin and 70 parts nitroglycerin was found to be insensitive to bullet impact.

EXAMPLE III 75 parts by weight nitroglycerin was poured with gentle stirring into 25 parts of tricaproin. The material was tested and found to be insensitive both to bullet impact and to detonation by a 5' kilogram weight falling from a height of 60* centimeters.

EXAMPLE IV 90 parts by weight of EGDN was added to 10 parts by weight of di-n-butyl sebacate in the manner of the immediately preceding example. The desensitized mixture was found to be insensitive to detonation by a 5 kilogram weight dropped from 60 centimeters. To provide a bullet impact insensitive mixture, 25 parts by weight of di-n-butyl sebacate to 75 parts by weight of EGDN Were required.

EXAMPLE V A mixture of 30 parts of tricaprylin and 70 parts nitroglycerin was formed in the manner of the tests described in Examples I-IV. This desensitized mixture was found to be insensitive to detonation by the falling weight and by bullet impact.

EXAMPLE VI To 15 parts of tricaproin was added with gentle stirring 85 parts of EGDN. The desensitized mixture was insensitive to impact by a falling 5 kilogram weight from a height of 60 centimeters.

The following table indicates the comparative sensitivities of nitroglycerin desensitized by the prior art method of adding an inert [diethyleneglycol or triacetin] and nitroglycerin desensitized according to the principles of this invention with a surface active agent. The height indicated in millimeters is that height at which a falling 5 kilogram weight will detonate the explosive 50% of the time and is a standard test for evaluating sensitivities of explosives. A higher number indicates a less sensitive explosive; that is, one that is more safe since it takes greater energy to detonate it.

Table 1 Percent desensitizer added to nitroglycerin Height (5 kilogram weight) mm.

Not surface active:

It is apparent that, by employing a surface active agent, the sensitivity of the liquid explosive is reduced to a safe level with a comparatively small amount of desensitizing agent. For example, 14.92% of the surface active agent tricaproin added to nitroglycerin results in a sensitivity of 600 millimeters while to produce the same sensitivity with the conventional desensitizer, diethylene glycol, 22% desensitizer is required. The resulting explosive employing a surface active desensitizer selected accordingly to the principles of this invention will result in an explosive composition which is safe to handle and yet contains a large percentage of the explosive thereby increasing the explosive power of the desensitized composition. Conversely, an explosive of any given power can be made much more insensitive to accidental detonation by employing a surface active desensitizer.

The invention is not to be construed as limited in any manner by the foregoing illustrative examples but is susceptible of many modifications and alterations without departing from the spirit or scope thereof. Accordingly, the invention is to be defined only by the scope of the appended claims.

What is claimed is:

1. A composition consisting essentially of a liquid lower alkyl nitrate explosive and from about 10% to about 30% of a liquid lower aliphatic polybasic acid ester in which each esterifying portion of each molecule has from three to seven carbon atoms in the chain.

2. A composition consisting essentially of a liquid lower alkyl polynitrate explosive and from about 10% to about 30% of a liquid lower aliphatic polybasic acid ester in which each esterifying portion of each molecule has from three to seven carbon atoms in the chain.

3. A composition consisting essentially of a liquid lower alkyl polynitrate explosive and from about 10% to about 30% of a liquid lower aliphatic polybasic acid ester having from 3 to 8 carbons in the acidportion exclusive of esterified acid groups, and in which each esterifying portion of each molecule has from three to seven carbon atoms in the chain.

4. A composition consisting essentially of a liquid lower alkyl polynitrate having from 2 to 3 carbon atoms in the chain and from about 10% to about 30% of a liquid lower aliphatic polybasic acid ester having from 3 to 8 carbon atoms in the acid portion exclusive of esterified acid groups and in which each esterifying portion of each molecule has from three to seven carbon atoms in the chain.

5. A composition consisting essentially of component [a] and from about 10% to about 30% of component [[2]; component [a] being a member selected from the group consisting of nitroglycerin and ethylene glycol dinitrate; and component [b] being a member selected from the group consisting of tributyrin, tricaproin,, trica-prylin and di-n-butyl sebacate.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,828 Wiggam Apr. 30, 1935 2,096,451 Parodi-Delfino Oct. 19, 1937 2,668,102 Fisher et a1 Feb. 2, 1954

Claims (1)

1. A COMPOSITION CONSISTING ESSENTIALLY OF A LIQUID LOWER ALKYL NITRATE EXPLOSIVE AND FROM ABOUT 10% TO ABOUT 30% OF A LIQUID LOWER ALIPHATIC POLYBASIC ACID ESTER IN WHICH EACH ESTERIFYING PORTION OF EACH MOLECULE HAS FROM THREE TO SEVEN CARBON ATOMS IN THE CHAIN.