Solid rocket propellant

Details Solid rocket propellant Solid rocket propellant

1999-07-16

2001-05-29

Carone, Michael J. (Department: 3641)

Explosive and thermic compositions or charges

Structure or arrangement of component or product

Solid particles dispersed in solid solution or matrix

C149S019100, C149S019600, C528S279000

Reexamination Certificate

active

06238499

ABSTRACT:

TECHNICAL FIELD
The present invention is directed to a solid rocket propellant.
BACKGROUND ART
Solid rocket propellants typically comprise an oxidizer, a fuel, a variety of additives, and a binder that holds the propellant together. Typical oxidizers include ammonium nitrate, ammonium dinitramide, ammonium perchlorate, potassium perchlorate, and other compounds known in the art. Typical fuels include aluminum powder, boron, and beryllium. Typical binders include nitrocellulose, hydroxy terminated polybutadiene, butadiene terpolymer, polybutadiene-acrylic acid-acrylonitrile, carboxyl terminated polybutyidiene, polyesters, polyethylene glycol, poly tetramethylene glycol and other compounds known in the art. Typical additives include plasticizers such as n-butyl nitratoethyl nitramine, trimethylolethane trinitrate and isodecyl pelargonate, dioctyl adipate; burning rate modifiers such as iron oxide and carbon; combustion stabilizers such as zirconium oxide; anti-oxidants such as n-methyl nitroaniline and 2,2′-Methylene-Bis-(4-Methyl6-Tert-Butylphenol) (available as AO-2246 from American Cyanamid Company, Parsippany, NJ); curing agents such as dimeryl diisocyante, isophorone diisocyanate, and Desmodur® N-100 (available from Bayer Corporation, Pittsburgh, PA); curing catalysts such as triphenyl bismuth and dibutyltin dilaurate; and acoustic suppressants such as silicon carbide.
Solid rocket propellants can be tailored to specific applications by varying their formulations. Although preliminary work on new formulations can be done in a laboratory with small quantities, testing and large scale demonstrations are typically required before a new formulation is accepted for military or commercial use. As a result, propellant development programs often generate considerable excess inventory of propellant. Production programs also generate excess inventory or off specification material. Finally, excess propellant is generated when rocket motors are periodically remanufactured to replace aging propellant with fresh propellant. In all cases, the excess inventory or off-specification material must be disposed of safely. Historically, open air incineration was the preferred disposal method. Increasingly, however, open air incineration is becoming environmentally unacceptable. Therefore, what is needed in the industry is a solid rocket propellant that can be disposed of with environmentally acceptable techniques.
DISCLOSURE OF THE INVENTION
The present invention is directed towards a solid rocket propellant that can be disposed of with environmentally acceptable techniques. As a side benefit, main components of the propellant can be recovered for reuse.
One aspect of the invention includes a solid rocket propellant that includes a hydroxy-terminated caprolactone ether binder.
Another aspect of the invention includes a method of disposing of a solid rocket propellant. A solid rocket propellant that includes a hydroxy-terminated caprolactone ether binder and one or more solid compounds disposed in the binder is contacted with a solution capable of hydrolyzing the binder to binder to form hydrolyzed caprolactone and poly(tetramethylene ether),. Solids remaining in the solution after the binder hydrolyzes are removed.
These and other features and advantages of the present invention will become more apparent from the following description.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention includes a full range of solid rocket propellant formulations, including minimum smoke propellants, reduced smoke propellants, and metalized propellants. The common element in all aspects of the present invention is the use of a hydroxy-terminated caprolactone ether (HTCE) polymer as a binder to hold the solid constituents of the propellant of the present invention together. As a result, the propellant of the present invention comprises at least one solid compound, for example an oxidizer, dispersed in an HTCE binder. For purposes of this application, HTCE is a linear block co-polymer of caprolactone and tetramethylene ether. Preferably, HTCE will have a molecular weight of about 2000 units to about 4200 units. At typical HTCE may have an OH value of about 56 mg KOH/g, an acid value of less than about 0.1 mg KOH/g, and a melting range of about 86° F. to about 95° F. The preferred HTCE is a waxy solid at room temperature and is a liquid at typical propellant processing temperatures of 120° F. to 140° F. HTCE is commercially available from Solvay Interox, Inc. (Houston TX) as part of Solvay's CAPA® line of polycaprolactones. The HTCE binder may make up about 4 weight % to about 10 weight % of the propellant of the present invention.
Minimum smoke propellants of the present invention include an HTCE binder and a chlorine-free oxidizer. Suitable chlorine-free oxidizers include ammonium nitrate (AN), ammonium dinitramide (ADN), nitramines such as cyclotrimethylene trinitramine (RDX) and cyclotetramethylene tetranitramine (HMX), and other chlorine-free oxidizers known in the art. A minimum smoke propellant may comprise about 45 weight % to about 75 weight % of the oxidizer. If desired, the propellant also may include one or more nitrate ester plasticizers such as n-butyl nitratoethyl nitramine (BuNENA), trimethylol ethane trinitrate (TMETN), triethylene glycol dinitrate (TEGDN), and other nitrate ester plasticizers known in the art for additional energy. Plasticizers may make up about 6 weight % to about 18 weight % the minimum smoke propellant. Minimum smoke propellants of the present invention may have a theoretical specific impulse of more than 230 lb
f
sec/lb
m
with an AN oxidizer and more than 260 lb
f
sec/lb
m
with an ADN oxidizer. Such propellants may be useful in tactical applications where a visible exhaust is undesirable because it would expose a rocket's firing position.
Reduced smoke propellants of the present invention include an HTCE binder and a chlorinated oxidizer. Suitable chlorinated oxidizers include ammonium perchlorate (AP), which may make up about 65 weight % to about 86 weight % of a reduced smoke propellant. If desired, the propellant also may include one or more energetic plasticizers such as BUNENA, TMETN, and TEGDN or fuel plasticizers such as dioctyl adipate (DOA) or isodecyl pelargonate (IDP). Plasticizers may make up about 5 weight % to about 12 weight % of the reduced smoke propellant. Reduced smoke propellants of the present invention may have a theoretical specific impulse of more than 244 lb
f
sec/lb
m
with an AP oxidizer. Such propellants may be useful in tactical applications, such a air-to-air applications, where a small amount of visible exhaust is tolerable as long as the exhaust does not obscure an operator's field of view.
Metalized propellants of the present invention include an HTCE binder, metal fuel, and an oxidizer. Suitable metal fuels include aluminum, boron, and other metal fuels known in the art. The preferred metal fuel is aluminum. The metal fuel may make up about 15 weight % to about 24 weight % of the metalized propellant. Suitable oxidizers include AP, AN, ADN, HMX, RDX, and other oxidizers known in the art. The oxidizer may make up about 45 weight % to about 75 weight % of the metalized propellant. If desired, the propellant also may include one or more energetic plasticizers, such as TMETN or TDGDN, or fuel plasticizers, such as DOA or IDP. Plasticizers may make up about 5 weight % to about 12 weight % of metalized propellants of the present invention. Metalized propellants of the present invention may have a theoretical specific impulse of more 263 lb
f
sec/lb
m
with AP oxidizer and 268 lb
f
sec/lb
m
with ADN or HMX oxidizer. Such propellants may be useful in applications for which high energy content is desirable and for which visible exhaust is not a problem.
The HTCE binder of the present invention can be cured with a variety of curing agents including di-functional isocyanates such as isophorene diisocyante (IPDI), dimeryl diisocyanate (DDI), bis-(4,isocyanatocyclohexyl) methane (Desmodur®-W, available from Bayer C

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