ENERGETIC COMPOSITIONS

Abstract: A process for making pyrotechnic, explosive, gas generating or propellant devices whereby particulate ingredients are blended in such proportions with a solution or dispersion of an elastomeric binders in an easily volatile solvent or mixture of solvents at least one of which is easily volatile as to provide a fluid or mouldable composition which on evaporation of the solvent or mixture of solvents after coating, extrusion or otherwise forming, shaping or pressing exhibits no adverse shrinkage, porosity or other defects detrimental to performance.

Description: Energetic Compositions This invention relates to pyrotechnic, explosive, gas producing and propellant compositions. It is particularly but not exclusively concerned with the manufacture of fireworks and devices for use in the entertainment industry. Conventional compositions used in the manufacture of fireworks and devices for use in the entertainment industry are most frequently in the form of powders or granules. In use, these are with few exceptions transferred into tubes or other containers where they may be retained in either their original loose form or consolidated by suitable means. Other conventional compositions are prepared in liquid or wet form. These are utilised by such processes as dipping, extrusion, moulding, printing, casting, coating, and consolidation by pressure followed usually by solvent removal and/or chemical reaction to increase molecular weight with or without the introduction of molecular cross-linking between some or all of the ingredients. The present invention provides for pyrotechnic, explosive, gas producing and propellant compositions which are capable of being made sufficiently fluid to be extrudable directly into paper tubes or other suitable containers and which on drying by evaporation of the solvent exhibit no significant shrinkage with the result that correct performance of filled devices on initiation is not compromised by separation of compositions from the inner surfaces of the paper tubes or other containers, or by the development of excessive porosity or other defects which will be known to those skilled in the art. In its broadest aspect the present invention provides energetic compositions comprising a pyrotechnic, explosive, gas generating or propellant substance or mixture blended with an elastomeric binder. These compositions can be fluidized for the preparation of combustible devices by addition of an easily volatile solvent. More specifically, the present invention provides a process for making pyrotechnic, explosive, gas generating or propellant devices whereby the particulate ingredient or ingredients are blended with a solution or dispersion of an elastomeric binder, or mixture of elastomeric binders, in an easily volatile solvent or mixture of solvents at least one of which is easily volatile, to provide a fluid or mouldable composition which on evaporation of the solvent or solvents after coating extrusion or otherwise forming, shaping or pressing, exhibits no adverse shrinkage, porosity or other defects detrimental to performance. As a modification of the present invention, the compositions may also be extruded into continuous lengths of bare cord or perforated cord to provide for the manufacture of fuses and detonating cords, or the extruded compositions may be further processed before or after drying to form a wide range of pyrotechnic, explosive, gas producing and propellant items such as stars, smoke pellets and blocks, detonatable explosive charges, gas producing pellets and granules, and active components for all manner of pyrotechnic and explosive devices including ammunition. As a further modification of the present invention, compositions may be produced which enable the direct production of granules without resort to the extrusion process. A yet further modification of the present invention provides for the manufacture of compositions which can be coated or printed onto suitable surfaces to which in the solid form they either adhere or can subsequently be removed to furnish pyrotechnic, explosive, gas producing or propellant sheets, films or any other shapes as may be desired. The compositions of the present invention may at any suitable time or stage be subjected to any other processes of manufacture as may be required such as cross-linking or other curing process brought about by chemical reaction or high energy radiation, pressing, squeezing, vibration, bumping, dropping, rolling, spreading, printing, machining, perforating and rendering porous by formation of cavities filled with gas. Advantages resulting from the use of compositions according to the present invention relate to their application to mechanical mixing and filling, and include the use of simple and safe one pot mixing processes coupled with easy machine filling with simple equipment. These and other advantages will be clear to those skilled in the art of explosives manufacture. Such other advantages are for example the elimination of the need to use priming compositions in some of those instances where an essential purpose of priming compositions is to retain dry powder fillings in firework bodies as can be the case with lances, portfires and bengal lights, a useful reduction in the sensitivity to water, either combined or free as liquid or vapour, of materials such as magnesium, iron, aluminium and hygroscopic ingredients, and the easy ability to work with materials that are readily soluble in water in cases where a fluid, wet or damp composition is required. Compositions according to the present invention are produced by including as a component at least one natural or synthetic elastomeric binder or a combination of natural and synthetic elastomeric binders dissolved or dispersed in an easily volatile solvent or a mixture of solvents at least one of which is easily volatile, such easily volatile solvent being allowed to evaporate after the final stage of processing the wet composition. By easily volatile solvent is meant a solvent for the elastomeric binder or mixture of such binders which evaporates substantially completely within 24 hours from a 6mm thick cord or layer of wet composition at a temperature of up to 50 υ C. Ideally, but not always essentially, the easily volatile solvent or mixture of such solvents is not a solvent for the ingredients of the composition other than the elastomeric binder or mixture of such binders. The proportions of elastomeric binder and solvent included in any particular composition are inter-related and must be balanced between the lower limit required to ensure sufficient cohesion between the particles in the dry composition to retain the desired structure and an upper limit defined by the need to avoid the development during evaporation of the solvent of significant shrinkage, porosity or other defects detrimental to correct performance of the device being produced. Examples of elastomeric binders which may be used in carrying out the present invention but to which it is in no way limited are natural rubbers, synthetic rubbers, plasticised chlorinated rubbers, plasticised polymeric chlorinated and/or fluorinated hydrocarbons, polymeric chlorinated and/or fluorinated hydrocarbons, polyurethanes, silicones and plasticised nitrocellulose. Some proprietary articles of commerce, for example some adhesive preparations, which may be used as prepared or with solvent addition or removal, are also suitable for use as the elastomeric binder. The elastomeric binders which have proven particularly attractive in carrying out the present invention are the natural and synthetic rubbers, although the invention is not limited to these materials. Elastomeric binders for use in the present invention may be produced by the incorporation of plasticising materials in polymers which would normally be too rigid for direct application. In this case the plasticising materials and polymers may be introduced separately as individual ingredients of the main explosive compositions. Elastomeric binders suitable for use in the present invention may also be the products of reaction of appropriate starting materials within the pyrotechnic, explosive, gas producing or propellant compositions. In carrying out this invention the natural or synthetic elastomeric binders may be combined with light stabilisers, anti-oxidants, anti-static agents, heat stabilisers and modifiers, and also with any other natural or synthetic polymeric materials whether or not elastomeric such as polyurethanes or the components of polyurethanes, chlorinated hydrocarbon polymers, cellulose ethers and esters, phenol- aldehyde resins, resorcinol-aldehyde resins or other resins prepared from one or more than one aromatic hydroxy compound and one or more than one aldehyde. These additional materials may be introduced into the composition in the same solvent as used for the natural or synthetic elastomeric binder or in a different solvent but which is preferably but not necessarily essentially miscible with that used for the natural or synthetic elastomeric binder. Combustible and non-combustible fibres may also be included to improve mechanical and thermal properties. To prepare compositions according to the present invention the elastomeric binder may be dispersed or dissolved in a suitable easily volatile solvent with or without antioxidants, plasticisers and any of the other aforementioned materials. The remaining ingredients are then mixed into the liquid in a manner and order determined by the normal considerations appropriate to explosives manufacture. Alternatively, the solvent may either be blended together with all of the ingredients including the elastomeric binder or with the ingredients including the elastomeric binder in any order as may be desired. The proportions of elastomeric binder and solvent are chosen such that after evaporation of the solvent, shrinkage detrimental to performance is substantially absent. Care usually has to be exercised in selecting the types and in balancing the proportions of elastomeric polymer and solvent to arrive at a composition that will develop little or no porosity detrimental to correct and reproducible combustion or explosion of the finished device. Compositions according to the present invention may be used in the manufacture of fireworks such as rockets, shells, roman candles, mines, fountains, drivers, pin wheels, lances, portfires, smokes, coloured lights, flares, showers and waterfalls. Compositions according to the present invention are not limited to the manufacture of fireworks but may, as already indicated, be used in the manufacture of detonatable explosive devices, gas generators and propellants. The present invention is illustrated by the following examples all percentages being by weight: Example 1 A composition suitable for making red lances was prepared by blending together in a single operation the following ingredients in the quantities given. Potassium perchlorate 1550.Og Strontium carbonate 232.5g Acaroid resin 232.5g Polyvinyl chloride powder 77.5g Dunlop adhesive L107 1 201.5g Pentane 300.Og The fluid composition resulting from the blending process was extruded into paper lance tubes having an internal diameter of 8.0mm and a length of 90.0mm. The petroleum spirit solvent in the Dunlop adhesive and the pentane were allowed to evaporate at room temperature through the paper walls of the lance tubes. When evaporation was complete ten lances were sectioned lengthwise and inspected. No defects such as shrinkage or significant porosity were observed. Twenty lances were conditioned to a emperature of 21°C and ignited individually. The lances bu t steadily with a red flame for an average time of 58 seconds. Example 2 Using the procedure described in example 1 red lances were made from the following composition, the proportions being expressed as percentages. Potassium perchlorate 59.0 Strontium carbonate 9.0 Acaroid resin 8.8 Polyvinyl chloride powder 3.0 Synthetic rubber BUNA R AP147 3 1.2 Heptane 19.0 Example 3 Using the procedure described in example 1 yellow lances were made from the following composition, the proportions being expressed as percentages. Potassium perchlorate 57.0 Sodium oxalate 11.5 Acaroid resin 5.7 Polyvinyl chloride 2.9 Natural rubber 3.0 Pentane 19.9 Example 4 Using the procedure described in example 1 green lances were made from the following composition, the proportions being expressed as percentages. Potassium chlorate 24.8 Barium chlorate 49.4 Acaroid resin 6.0 Dunlop adhesive L107 1 19.8 Example 5 Using the procedure described in example 1 white lances were made from the following composition, the proportions being expressed as percentages. Potassium perchlorate 52 Barium nitrate 16 Strontium carbonate 2 Acaroid resin 8 Polyvinyl chloride powder 2 Dunlop adhesive L107 1 20 Example 6 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, aerial effects or rockets were made from the following composition, the proportions being expressed as percentages. Potassium perchlorate 54.2 Potassium benzoate 20.8 Titanium metal 8.4 Dunlop adhesive L107 1 16.6 Ex mple 7 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, rockets were made from the following composition, the proportions being expressed as percentages. Potassium perchlorate 75.0 Dibutyl phthalate 10.2 Polyvinyl chloride 6.8 Aluminium powder blown 200 mesh 8.0 Tetrahydrofuran as required Example 8 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, green stars and flares were made from the following composition, the proportions being expressed as percentages. Magnesium grade 0 32.0 Potassium perchlorate 16.0 Polyvinyl chloride 6.4 Barium nitrate 25.6 Dunlop adhesive L107 1 20.0 Example 9 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, strobe flares and strobe stars were made from the following composition, the proportions being expressed as percentages. Guanidine nitrate 31.0 Barium nitrate 31.0 Magnesium-aluminium alloy (50/50) 18.0 Dunlop adhesive L107 1 7.5 Heptane 12.5 Example 10 Using the procedure described in example 1, with lance tubes replaced by paper portfire tubes internal diameter 8mm and length 250mm, portfires were made from the following composition, the proportions being expressed as percentages. Potassium chlorate 23.25 Barium nitrate 46.50 Acaroid resin 11.65 Tivolan 1121 5 18.60 The portfires burnt smoothly for an average time of 4 minutes 5 seconds . Example 11 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, smokeless fountains for indoor use were made from the following composition, the proportions being expressed as percentages. Xyllokol R 76.9 Zirconium metal, 0.04-0.20mm 6.0 Dunlop adhesive L107 1 17.1 Petroleum ether as required Example 12 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, detonatable items were made from the following composition, the proportions being expressed as percentages. RDX 80.0 Dunlop adhesive L107 1 20.0 Example 13 Using the procedure described in example 1 for making the composition the following ingredients in the percentage proportions given were processed to give a coatable or extrudable mass suitable for producing pyrotechnic fuses. Potassium perchlorate 80 Polyvinyl chloride 5 Rubber type NN4 ADA 2 15 Petroleum spirit as required After coating or extrusion and removal of the solvent the composition was vulcanised at a temperature of 120°C for 1 hour. Example 14 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, yellow smokes were made from the following composition, the proportions being expressed as percentages. Potassium chlorate 26.0 Lactose 22.0 Solvent yellow dye 26.0 Dunlop adhesive L107 1 26.0 Example 15 Using the procedure described in example 1, with lance tubes replaced by other suitable paper tubes, fuse and detonator elements were made from the following composition, the proportions being expressed as percentages. Lead styphnate 80.0 Dunlop adhesive L107 1 20.0 Petroleum ether as required Example 16 A composition suitable for making portfires was obtained by firstly preparing a pre-mixture by passing the following ingredients in the quantities given three times through a 25 British Standard mesh sieve. Potassium chlorate 800g Barium nitrate 1600g Acaroid resin 400g The whole of this pre-mixture was then blended with 800g of Dunlop adhesive L107 1 . The resultant fluid composition was extruded into paper portfire tubes of internal diameter 8.0mm, external diameter 10.0mm and length 280.0mm. The tubes were filled from one end to a length of approximately 265mm. The unfilled part at the other end enabled wooden dowel handles to be fitted after the petroleum spirit solvent in the Dunlop adhesive had been allowed to evaporate at room temperature through the paper walls of the portfire tubes. When evaporation was complete ten portfires were sectioned lengthwise and inspected. No defects such as shrinkage or significant porosity were observed. Twenty portfires complete with handles were then conditioned at 21 ϋ C and ignited in such manner that their burning times could be determined. The portfires burnt smoothly with an average burning time of 3 minutes 47 seconds. Example 17 Using the procedure described in example 16, with portfire tubes replaced by other suitable paper tubes, waterfalls were made from a composition produced by blending a pre-mixture of the solids listed below with the fluid adhesive, the proportions being expressed as percentages. Barium nitrate 42.6 Potassium nitrate 6.5 Aluminium dark pyro 13.1 Aluminium flitters 17.3 Dunlop adhesive L107 1 20.5 Example 18 A composition in granular form for making stars waε produced by mixing in a blender-granulator the following ingredients in the weights given. Meal powder 1614g Aluminium powder flake 200 mesh 198g Antimony sulphide 348g Strontium carbonate 198g Aerosil R 300 51g Dunlop adhesive L107 1 588g Due to the presence of the Aerosil R 300 the mixture formed into stable granules during the mixing process. The granules were poured into moulds and compressed in the solvent wet condition to form stars . The stars were removed from the moulds and the solvent allowed to evaporate at a temperature of 50°C. When evaporation was complete stars were examined for shrinkage and porosity. No significant shrinkage or porosity was found. The stars ignited easily and produced a brilliant effect in the air when released from shells and rockets. Example 19 Stars were made using the composition and method of example 18 except that the granular material was poured into paper tubes of 12.5mm internal diameter and 25.0mm length and therein compressed. After evaporation of the solvent stars were sectioned and examined for shrinkage and porosity. No such defect was observed. Example 20 A composition suitable for making rockets was prepared from the following ingredients in the quantities given. Potassium perchlorate 291.2g Potassium benzoate 28.6g Iron filings, 25 mesh 83.2g Dunlop adhesive L107 1 57.2g Resorcinol formaldehyde resin syrup 4 52.Og Paraformaldehyde 7.8g The paraformaldehyde was thoroughly mixed with the resorcinol formaldehyde resin syrup and this mixture was blended with the Dunlop adhesive. The remaining ingredients which had previously been mixed together were then blended into the resin/Dunlop adhesive combination and the fluid composition so formed was extruded into plain cylindrical paper tubes fitted with coaxial spindles to form a long cavity in the composition in known manner. Solvent was allowed to evaporate through the walls of the tubes for 18 hours at room temperature. The spindles were then removed to expose the cavities and the rocket bodies were heated at 100°C for 1 hour to effect a final cure of the resorcinol formaldehyde resin. The rockets were examined for shrinkage of the composition and other defects such as porosity and found satisfactory in these respects. The rocket bodies performed normally when subjected to burning tests . 1 L107 adhesive is a natural rubber adhesive preparation in petroleum spirit solvent and is manufactured by Dunlop Adhesives, Silvertown House, Vincent Square, London, SW1 2PL. 2 Rubber type NN4 ADA is manufactured by Gummiwerk Krailburg GmbH & Co., Waldkraiburg, Germany. R 3 BUNA AP147 is a synthetic rubber manufactured by Bayer AG, Leverkusen, Germany. 4 The resorcinol formaldehyde resin syrup is type 374 FC manufactured by Catalin Limited, Waltham Abbey, Essex, England. 5 Tivolan 1121 is a rubber based solution manufactured by Tivoli Werke AG, Hamburg, Germany.

Claims: Cla ms 1. A process for making pyrotechnic, explosive, gas generating or propellant devices whereby particulate ingredients are blended in such proportions with a solution or dispersion of an elastomeric binder or mixture of elastomeric binders in an easily volatile solvent or mixture of solvents at least one of which is easily volatile as to provide a fluid or mouldable composition which on evaporation of the solvent or mixture of solvents after coating, extrusion or otherwise forming, shaping or pressing exhibits no adverse shrinkage, porosity or other defects detrimental to performance. 2. A process according to Claim 1 in which the elastomeric binder is natural rubber. 3. A process according to Claim 1 in which the elastomeric binder is synthetic rubber. 4. A process according to Claim 1 in which the elastomeric binder is any of the classes of materials hereinbefore described. 5. A process according to Claim 1 in which the elastomeric binder is combined with light stabilisers, anti-oxidants, heat stabilisers, modifiers, and natural or synthetic polymeric materials as hereinbefore described. 6. A pyrotechnic, explosive, gas generating or propellant composition as produced in any one of Claims 1-5. 7. Any device constructed using a composition as claimed in Claim 6. 8. An energetic composition comprising a pyrotechnic, explosive, gas generating or propellant substance or mixture blended with an elastomeric binder. 9. A composition according to Claim 8 in which the elastomeric binder is present in an amount up to 20% by weight. 10. A composition according to Claim 8 in which the elastomeric binder is present in an amount up to 15% by weight. 11. A composition according to Claim 8 in which the elastomeric binder is present in an amount up to 4% by weight. 12. A composition according to Claims 8-11 in which the elastomeric binder is natural rubber or a synthetic rubber. 13. A flowable or mouldable composition for making a pyrotechnic, explosive, gas generating or propellant device comprising a pyrotechnic, explosive, gas generating or propellant substance or mixture blended with an elastomeric binder and fluidized with an easily volatile solvent. 14. A combustible device in which a composition as claimed in any one of Claims 8 to 13 is coated on or impregnated in a supporting substrate or loaded in a container or casing. 15. A process according to Claim 1 substantially as described in any one of Examples 1 to 20. 16. A composition according to Claim 8 substantially as deεcribed as in any one of Examples 1 to 20. 17. A composition according to Claim 13 substantially as described in any one of Examples 1 to 20. 18. A device according to Claim 14 substantially as described in any one of Examples 1 to 20.

Inventors: WRAIGE JOHN DOUGLAS MICHAEL, WRAIGE, JOHN, DOUGLAS, MICHAEL
Applicants: WRAIGE JOHN DOUGLAS MICHAEL, WRAIGE, JOHN, DOUGLAS, MICHAEL
Application year: 1997
Main classification: C06B21
IPC codes: C06B21