IL32928A - Cartridge-less moulded propellant charge - Google Patents

Description

moulded propellant charge NOBEL 31074 The invention relates to a moulded propellant charge of an explosive which is or decomposes by deflagration without tending to such as olyvinyl erythritol tetranitrate or the or mixtures particularly for apparatus in commercial such as nail driving impact control quick break switches and the While such moulded propellant charges have great advantages owing to the absence of the conventional ridge they have the considerable disadvantage that the surface of the mouldings is unprotected and consequently so that the mouldings can catch fire or even be unintentionally owing to the high inflammability of the explosives of which they are Accordingly the storage and use of these mouldings require certain because of the absorptivity of the materials used and the substantially porous structure of the their unprotected surface tends to admit water or other liquids as well as such as in addition to the particularly careful handling of these moulded charges from the point of view of safety they must also be carefully manipulated in the course of their usually rough handling in practical It is the of the present invention to ate the above mentioned According to the invention this is achieved by providing the moulded charges with a firmly 5 preferably protective layer which protects the charges unintentional ignition or combustio and from nation and absorption of an advantageous embodiment of the invention this protective layer is created by denitration of the moulding by the of the nitro or nitrate groups in the of the nitro or nitrate groups in surface of the starting material can be carried in a simple by the treatment of the moulded charges in a bath containing suitable such as sulfides or and the followed by the removal of the split products by In addition to this surface or in its there may be according to another ment of the a protective of synthetic for polyglycidyl ethers and the or of soluble resins such as polyvinyl acetate and mixed polyacrylates or of dispersions of polyvinyl Yet another embodiment of Invention provides the use of such as methyl cellulose glycolate or the in forming the protective The protective layer may be formed by painting or precipitation from a depending on the nature of the starting material Suitable for cation by immersion or painting are polyurethane which may be used either as prepolymerisates with subsequent as finished as well tional aromatic glyeidyl mixed vinyl acetate polyacrylle dispersions of polyvinyl mixed polymerisates of or of for cellulose colatee are advantageously used for application by Where a this too ma be and possibly secured in its by the protective Since the porous structure of the moulded charge is not altered in the method according to invention and the protective coating may accordingly be made very of the mouldings is not while the danger in handling the mouldings is reduced to an able deeply penetrating contaminations are largely and lastly the resistance to mechanical stresses is improved and the wear by friction is All this without significant residue Pellets of 6 diamete and thickness were prepared in a die by means of a hydraulic press from a wet fibrous nitrocellulose having a nitrogen content of and being covered with of eentralite and o One surface of these pellets had a slanting upper depression of 2 mm depth and pellets had smooth surfaces and were sufficiently strong mechanicall not to in Their porous structure was still evident by the ct that of liquids were pellets dried before being further then of a moist detonato was into the depression and the pellets were from al moisture by fhe pellets were t passed through bath a mixture parts by weight of a of molecular weight 1200 parts of diisocyanate 3 parts of phtha and 70 parts of methylene On the surface there remained a liquid the solvent evaporated very coating fied by subsequent warming and formed a firmly thin layer which protected the body of the charge on sides and not impai the of the Ho formation of residue detonation resulted insufficientOCRQuality

Claims (6)

1. , A cartridge-leas moulded propellant charge of an explosive material such aa nitrocellulose, polyvinyl nitrate, nitroguanldine, pentaerythrltol tetranitrate and the like, o of mixtures thereof, particularly for use in commercial apparatus such as nail driving tools, impact tools, control elements, quick break switches and the like, which charge is provided on its surface with a firmly adhering, preferably thin layer protecting it from unintentional ignitio or combustion and from contamination and absorption of moisture,

2. A cartridge-less moulded propellant charge according to Claim 1, wherein the protective layer is created by the splitting-otf of the nitro or nitrate groups in the surface of the moulding*

3. · A cartridge-less moulded propellant charge according to Claim 1 or 2, wherein a protective coating is formed rom synthetic resins, e.g., polyurethanes, polyglyeidyl ethers and the like, or soluble resins such as polyvinyl acetate and mixed polymerisates, polyacrylates or dispersions based on polybutadiene, polyvinyl acetate and polyacrylates.

4. A cartridge-less moulded propellant charge according to Claim 1 or 2, wherein a protective layer is formed from methyl cellulose, cellulose glycolates or the like,

5. * A process for the manufacture of cartridge-less moulde propellent charges according to Claims 3 or 4» wherein the protective coating is applied by immersion, painting or precipitation from a solution.

6. A process for the manufacture of cartridge-less moulded propellant charges according to Claims 3 or 4» wherein the protective coating is formed by prior spraying, painting or similar treatment of the press-die with a lacquer component, or by the insertion of the lacquer component in the form of a foil into the die in the moulding operation. For the Applicants PARTNERS iffi/rb