US3714306A - Method of treating spherical powder grains - Google Patents

Method of treating spherical powder grains Download PDF

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Publication number
US3714306A
US3714306A US00762641A US3714306DA US3714306A US 3714306 A US3714306 A US 3714306A US 00762641 A US00762641 A US 00762641A US 3714306D A US3714306D A US 3714306DA US 3714306 A US3714306 A US 3714306A
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Prior art keywords
powder
weight
parts
powder grains
suspension
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US00762641A
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English (en)
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R Coffee
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Olin Corp
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Olin Corp
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    • CCHEMISTRY; METALLURGY
    • C06EXPLOSIVES; MATCHES
    • C06BEXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
    • C06B21/00Apparatus or methods for working-up explosives, e.g. forming, cutting, drying
    • C06B21/0091Elimination of undesirable or temporary components of an intermediate or finished product, e.g. making porous or low density products, purifying, stabilising, drying; Deactivating; Reclaiming

Definitions

  • Propellant powder grains made by the globular powder process have been used extensively for casting solid rocket propellants.
  • the use of propellants in the form of a rod, a rod with internal star, hollow rod, multiple port rod, and the like is well known in the art for the purpose of controlling thrust throughout the combustion period.
  • powder grains produced by the globular powder process have a skin present on their outer surface. It is theorized that this skin is caused by the retention by strong adsorption at the surface of protective colloids of animal origin which are used in the process. This skin adversely affects the propellant-inhibitor bond strength, as well as the tensile strength, of propellants cast from such powder grains.
  • a more specific object of this invention is to provide a method for treating globular powder which results in an increase in the propellant-inhibitor bond strength and tensile strength of a propellant cast from such powder.
  • Yet another object of this invention is to provide a method for removing the skin from globular powder grains caused by the adsorption of animal origin colloids.
  • the invention contemplates treating globular powder grains with an enzyme which will hydrolyze either protein or fats. Since this skin is of animal origin and may contain a wide variety of fats and proteins, this invention further contemplates a mixture of enzymes including proteolytic enzymes which are substances which have the ability to attack proteins and effect hydrolysis to amino acids and lipases which are enzymes that effect the hydrolysis of fat.
  • the powder grains to be treated are prepared in accordance with the conventional globular powder process.
  • a lacquer is prepared consisting of a suitable powder base, such as nitrocellulose, dissolved in a solvent.
  • suitable powder base such as nitrocellulose
  • solvents suitable for use with nitrocellulose include methyl ethyl ketone, ethyl formate, isopropyl acetate, diethyl ketone, ethyl acetate and mixtures thereof.
  • the lacquer prepared in accordance with the above.- identified procedure may be presized if desired and then admixed with a non-solvent suspending material.
  • a non-solvent suspending material may be any liquid that is substantially immiscible with the lacquer, an aqueous medium is generally preferred.
  • the non-solvent material also contains a protective colloid and/or other additives which are described more fully below.
  • the protective colloids are preferably of animal origin such as the type derived from animal protein, animal bone glue, or the like. Chemically each of these protective colloids is a collagen which by definition is an albuminoid comprising the major portion of the white fiber in the connectivetissues of the animal body, particularly in the skin, bones and tendons. This colloid may be present in the non-solvent material in a proportion equivalent to between about 0.1 and about 0.5 percent by weight.
  • Liquid high energy compounds such as triethylene glycol dinitrate, diethylene glycol dinitrate, and nitroglycerin may be added with the lacquer to the suspending material in a proportion up to about 50 percent by weight of the powder base in order to increase the burning rate of the solid powder grains ultimately produced and to serve as a plasticizer when the powder is used as a component of solid propellants.
  • a crystalline high explosive composition in finely divided form may be added to the lacquer or solvent material prior to or during mixing. Any crystalline high explosive composition which is substantially insoluble in the water immisciblesolvent used in preparing the lacquer of nitrocellulose can be used in thepreparation of the novel rocket cast granules of this invention.
  • Suitable explosive compositions include HMX (cyclotetramethylenetetranitramine), RDX (cyclotrimethylenetrinitramine), PETN (pentaerythritol tetranitrate), 2,4,6-trinitrophenylmethylnitramine, and mixtures thereof.
  • Any suitable mixing vessel provided with a mechanical agitator or other mixing device may beemployed.
  • the mixture is kept under agitationsufficient to maintain the state of suspension until the suspended presized bodies of lacquer become rounded under the force of interfacial tension.
  • Mixing of the lacquer and suspending material, and the formation of the globules may be carried out ata temperature between about 10C and about C, or any temperature above the freezing point of the mixture and below the boiling point of the volatile solvent. Pressures above atmospheric pressure may be employed during mixing to inhibit evaporation of the solvent at higher temperatures.
  • Agitation of the lacquer in the suspending material for a period of at least about one-half hour, and as long as 1 hours or more, is generally necessary to form globules of the desired size and shape and, if utilized, to effect substantially complete dispersion of the particles of highly explosive composition or other solid additives in the lacquer globules.
  • an additional amount of solvent for the nitrocellulose may be slowly added for agitation with the suspension. This addition of solvent causes a breakdown in the lacquer globules and additional lacquer globules are formed having a diameter substantially less than the original globules.
  • the solvent may then be evaporated from the lacquer globules by increasing the temperature of the suspension up to the distillation temperature by bubbling air or other inert gas through the suspension. If the specific gravity and porosity of the individual powder grains are not critical, the evaporation may be continued until complete solidification of the lacquer globules is obtained whereupon the resulting solids are then separated from the non-solvent material for further processing in accordance with this invention. If the specific gravity and porosity of the powder grains is critical, additional processing may be performed prior to the final evaporation and complete solidification of the globules.
  • powder grains produced by the globular powder process are further treated with an enzyme or mixture of enzymes which will hydrolize proteins and/or fats which are in the skin of the powder particles due to the protective colloid.
  • an enzyme or mixture of enzymes which will hydrolize proteins and/or fats which are in the skin of the powder particles due to the protective colloid.
  • any proteolytic enzymes, any of the lipases, or combinations of the two types may be used.
  • the enzymes which are particularly effective are pepsin, papain, those enzymes produced by aerobic bacteria, trypsin, and pancreatin.
  • Serizyme which is a trademark for a standardized bacterial proteolytic enzyme preparation of the Wallerstein Co. may be used.
  • the powder grains to be treated may be loaded into a vessel equipped with an agitator along with suitable quantity of water.
  • the agitation is started and run at a sufficient speed to keep the powder grains in suspension in the water.
  • the proportion of water in relation to the powder grains may vary widely with the only requirement being that there must be enough water present to suspend the powder grains.
  • one part by weight powder grains to three parts by weight water is used.
  • l00 parts by weight of powder grains produced by the globular powder process were loaded into a vessel equipped with an agitator along with 300 parts by weight of water.
  • Swift Colloid No. l was used as the protective colloid.
  • the agitation was started and continued at a sufficient speed to keep the powder grains in suspension.
  • the enzyme Serizyme in the proportion of nine parts by weight enzyme to parts by weight powder grains, was added to the vessel and the temperature raised to 40C. The agitation was continued for 4 hours, after which the powder was separated from the treatment material in a centrifuge, washed with clear water to remove the residual material, and dried.
  • Test specimens were prepared by mixing the treated powder grains with a solution of 60 parts by weight nitroglycerin and 40 parts by weight dimethyl sebacate in a ratio of approximately 69 parts by weight of powder to 31 parts by weight of the solution. The resulting slurry was cast into a cylindrical mold, cured at F for 48 hours, and then machined to produce a dumbbell-shaped specimen. The average of standard tensile tests performed on the specimens was a tensile strength of 620 p.s.i.
  • powder grains produced by the same globular powder process and treated with the enzyme Serizyme in the manner described above were mixed with a solution of 60 parts by weight nitroglycerin and 40 parts by weight dimethyl sebacate. The mixture was approximately 69 parts by weight powder to 31 parts by weight solution.
  • the mixture was cast into a mold having a cellulose acetate inhibitor and cured to bond the propellant thereto. After curing, the propellant with the cellulose acetate inhibitor was mounted in a testing machine and the propellant peeled from the inhibitor. The average of the tests performed was 35.7 pounds per inch.
  • specimens prepared from powder grains produced by the globular powder process, but untreated with an enzyme were tested to provide a comparison.
  • the results of the tests performed upon such specimens were 17 pounds per inch, less than half that exhibited by the specimens prepared with grains treated in accordance with this invention.
  • a method of treating powder granules that have a skin present on their outer surface due to a protective colloid of animal origin being present during the formation thereof comprising suspending said powder granules in a mixture of an aqueous solution and a proteolytic enzyme, agitating said suspension until substantially all of said skin is removed, and
  • suspension comprises one part by weight powder grains to 3 parts by weight water and 9 parts by weight enzyme to 100 parts by weight powder grains.
  • a method of treating globular powder granules that have been produced by suspending droplets of lacquer of a smokeless powder base and a solvent in a non-solvent medium and a protective colloid of animal origin and then solidified into granules of a globular shape, having a skin on their outer surface, said method comprising suspending said solidified globular powder granules in a mixture of an aqueous solution and a proteolytic enzyme, agitating said suspension until substantially all of said skin is removed, and thereafter separating said powder granules from the remainder of the materials.
  • suspension comprises one part by weight powder grains to 3 parts by weight water and 9 parts by weight enzyme to I parts by weight powder grains.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Cosmetics (AREA)
  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
US00762641A 1968-09-25 1968-09-25 Method of treating spherical powder grains Expired - Lifetime US3714306A (en)

Applications Claiming Priority (1)

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US76264168A 1968-09-25 1968-09-25

Publications (1)

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US3714306A true US3714306A (en) 1973-01-30

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US (1) US3714306A (https=)
BE (1) BE739375A (https=)
DE (1) DE1946824A1 (https=)
FR (1) FR2018832A1 (https=)
GB (1) GB1233295A (https=)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2496757C1 (ru) * 2012-04-10 2013-10-27 Федеральное казенное предприятие "Государственный научно-исследовательский институт химических продуктов" (ФКП "ГосНИИХП") Способ получения сферического пороха для стрелкового оружия

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2027114A (en) * 1932-03-12 1936-01-07 Western Cartridge Co Manufacture of smokeless powders
US3400026A (en) * 1967-01-16 1968-09-03 Du Pont Thickened aqueous inorganic oxidizer salt explosive composition containing dissolvedproteinaceous material

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2027114A (en) * 1932-03-12 1936-01-07 Western Cartridge Co Manufacture of smokeless powders
US3400026A (en) * 1967-01-16 1968-09-03 Du Pont Thickened aqueous inorganic oxidizer salt explosive composition containing dissolvedproteinaceous material

Also Published As

Publication number Publication date
GB1233295A (https=) 1971-05-26
FR2018832A1 (https=) 1970-06-26
DE1946824A1 (de) 1970-08-20
BE739375A (https=) 1970-03-25

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