EP0614863B1 - Process for producing metal powder containing water-based pyrotechnic agent, coated metal powder and use therof - Google Patents
Process for producing metal powder containing water-based pyrotechnic agent, coated metal powder and use therof Download PDFInfo
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- EP0614863B1 EP0614863B1 EP94103430A EP94103430A EP0614863B1 EP 0614863 B1 EP0614863 B1 EP 0614863B1 EP 94103430 A EP94103430 A EP 94103430A EP 94103430 A EP94103430 A EP 94103430A EP 0614863 B1 EP0614863 B1 EP 0614863B1
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- magnesium powder
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- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
- C06B45/18—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component
- C06B45/30—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an inorganic explosive or an inorganic thermic component
- C06B45/32—Compositions or products which are defined by structure or arrangement of component of product comprising a coated component the component base containing an inorganic explosive or an inorganic thermic component the coating containing an organic compound
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- the invention relates to a process for the production of metal-based pyrotechnic active substances on an aqueous basis, coated metal powder and the use thereof.
- pyrotechnic active materials often contain red phosphorus in combination with metal powder, in particular with aluminum or magnesium.
- active compositions have been produced by dissolving a binder in a chlorinated hydrocarbon, slurrying the magnesium powder or aluminum powder and the red phosphorus in this solution and granulating the slurry by evaporating off the solvent. This granulate could then be processed and metered well.
- Chlorinated hydrocarbons pose problems for environmental reasons and their use will be restricted over the next few years, so that they will have to be replaced by other solvents. Processing in an aqueous system which is easiest to handle in terms of safety, emission problems and toxicity problems would, of course, be advantageous.
- metal powders cannot easily be slurried in water, as this could lead to an explosive reaction with the formation of hydrogen and hydroxides. They are also partially inactivated by the formation of hydroxides.
- the metal powder such as magnesium powder or aluminum powder, must therefore be pretreated so that it cannot react with water.
- AT-B 236 729 and AT-B 240 128 are processes for Chemical oxidation of aluminum powder and magnesium powder, in which the granules forming the powder are coated with an oxide skin that protects the metal. Furthermore, it is known to provide metal powder with a coating, for example made of stearic acid. A disadvantage of these processes, however, is that either they do not provide adequate protection against water or the reactivity is reduced in such a way that the metal powders can no longer or not sufficiently react to the desired reaction.
- the object of the invention is now to provide a process for the preparation of pyrotechnic active compositions which, as an effective principle, contain, for example, red phosphorus in combination with metal powder in addition to other customary ingredients, in which the active composition can be processed in an aqueous system without the part the active powder forming metal powder is inactivated or can trigger an explosive reaction.
- This object is achieved by a process for producing pyrotechnic active compositions containing magnesium powder on an aqueous basis, which is characterized in that the magnesium powder is coated with a plastic which is insoluble for dilute acids and water and essentially impermeable to water and oxygen in a vacuum fluidized bed process, where the coating in one Mass of not more than 5 percent by weight, based on the total mass of the magnesium powder, is present, the powder obtained is suspended in water, mixed with the other constituents of the active composition and brought into the desired shape.
- magnesium powders by coating magnesium powders with a very thin layer of a plastic which is insoluble in water and dilute acids and is essentially impermeable to water and oxygen, the magnesium powder can be inactivated to such an extent that it becomes in storage during storage Processing in an aqueous slurry and the production of the pyrotechnic active compounds do not cause any undesirable reactions, although this coating does not have an adverse effect on the properties, in particular the reactivity, of the pyrotechnic active compound itself.
- the magnesium powder is provided with a coating of a plastic which is insoluble for dilute acids and water and essentially impermeable for water and oxygen.
- plastics are known to the person skilled in the art, and all plastics which have these properties and do not adversely affect the active composition are suitable here.
- Polymers or copolymers based on acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters are preferably used for the plastic coating. These polymers or copolymers are suitable for forming very thin coatings which nevertheless prevent the coated metal grain from reacting with water or acid.
- a methacrylic acid-methyl methacrylate copolymer is particularly preferably used.
- the coating on the magnesium particles must be very thin and must not be more than 5 percent by weight based on the total mass of the magnesium powder. If the coating becomes too thick, the reaction of the particles in the active mass is hindered, which is undesirable. Particularly good results are achieved with coatings which are applied in an amount which corresponds to 1 to 4 percent by weight, in particular 2.5 to 3.5 percent by weight, based on the total mass of the magnesium powder.
- a vacuum fluidized bed process As is known per se, is used.
- the fluidized bed process must be carried out in such a way that moisture is excluded during the coating.
- the process is suitable for magnesium powder, which is used for pyrotechnic active materials and is to be processed in aqueous systems.
- the magnesium powder coated with the plastic can be stored in this form and is slurried in water to produce the pyrotechic active composition, mixed with the other constituents known per se, for example red phosphorus, and then brought into the desired shape.
- the stability of the coated magnesium powder during storage and during slurrying in water is excellent and the reactivity of the active mass is not significantly impaired.
- Another object of the invention is a magnesium powder with a coating of a plastic which is insoluble for dilute acids and water and essentially impermeable for water and oxygen, the coating making up no more than 5% by weight, based on the total mass of the magnesium powder.
- the magnesium powder coated according to the invention can be stored and transported in this form. It is stabilized against change due to water or oxygen or acid and can therefore be used in a variety of ways, in particular for processes in which aqueous slurries of magnesium powder are used.
- the magnesium powder coated according to the invention is particularly preferably used for the production of aqueous-based pyrotechnic active compositions.
- FIG. 1 shows a diagram in which the results are plotted for the hydrogen evolution m W / m E, based on the weight, for the magnesium powder coated with 1%, 2% and 3% and for the uncoated magnesium powder.
- 1% and 2% coating quantity there are only slight differences in the hydrogen evolution; however, there is a significant delay compared to the uncoated sample.
- a further improvement is made in the sample provided with a 3% coating.
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Description
Die Erfindung betrifft ein Verfahren zur Herstellung von Metallpulver enthaltenden pyrotechnischen Wirkmassen auf wäßriger Basis, beschichtete Metallpulver sowie deren Verwendung.The invention relates to a process for the production of metal-based pyrotechnic active substances on an aqueous basis, coated metal powder and the use thereof.
Pyrotechnische Wirkmassen enthalten als wirksames Prinzip häufig roten Phosphor in Kombination mit Metallpulver, insbesondere mit Aluminium oder Magnesium. Bisher erfolgte die Herstellung solcher Wirkmassen, indem ein Bindemittel in einem Chlorkohlenwasserstoff gelöst wurde, das Magnesiumpulver oder Aluminiumpulver und der rote Phosphor in dieser Lösung aufgeschlämmt wurde und die Aufschlämmung durch Abdampfen des Lösemittels granuliert wurde. Dieses Granulat konnte dann gut weiterverarbeitet und dosiert werden. Chlorkohlenwasserstoffe werfen jedoch aus Gründen des Umweltschutzes Probleme auf, und ihre Verwendung wird im Laufe der nächsten Jahre eingeschränkt werden, so daß sie durch andere Lösungsmittel ersetzt werden müssen. Vorteilhaft wäre natürlich die Verarbeitung in einem wäßrigen System, das in bezug auf Sicherheit, Emissionsprobleme und Toxizitätsprobleme am einfachsten zu handhaben ist. Metallpulver können jedoch nicht ohne weiteres in Wasser aufgeschlämmt werden, da dies zu einer explosionsartigen Reaktion unter Bildung von Wasserstoff und Hydroxiden führen könnte. Außerdem werden sie durch die Bildung von Hydroxiden teilweise inaktiviert. Das Metallpulver, wie Magnesiumpulver oder Aluminiumpulver, muß daher so vorbehandelt werden, daß es nicht mit Wasser reagieren kann.As an effective principle, pyrotechnic active materials often contain red phosphorus in combination with metal powder, in particular with aluminum or magnesium. Heretofore, such active compositions have been produced by dissolving a binder in a chlorinated hydrocarbon, slurrying the magnesium powder or aluminum powder and the red phosphorus in this solution and granulating the slurry by evaporating off the solvent. This granulate could then be processed and metered well. Chlorinated hydrocarbons, however, pose problems for environmental reasons and their use will be restricted over the next few years, so that they will have to be replaced by other solvents. Processing in an aqueous system which is easiest to handle in terms of safety, emission problems and toxicity problems would, of course, be advantageous. However, metal powders cannot easily be slurried in water, as this could lead to an explosive reaction with the formation of hydrogen and hydroxides. They are also partially inactivated by the formation of hydroxides. The metal powder, such as magnesium powder or aluminum powder, must therefore be pretreated so that it cannot react with water.
Es ist bereits bekannt, Metallpulver durch chemische Oxidation oder physikalische Verfahren so zu verändern, daß bei Kontakt mit Wasser keine schädlichen Reaktionen auftreten. So sind beispielsweise aus AT-B 236 729 und AT-B 240 128 Verfahren zur chemischen Oxidation von Aluminiumpulver und Magnesiumpulver bekannt, bei denen die das Pulver bildenden Körnchen mit einer Oxidhaut überzogen werden, die das Metall schützt. Weiterhin ist es bekannt, Metallpulver mit einem Überzug, beispielsweise aus Stearinsäure, zu versehen. Ein Nachteil dieser Verfahren ist es jedoch, daß entweder kein ausreichender Schutz gegenüber Wasser gewährt oder daß die Reaktionsfähigkeit derart vermindert wird, daß die Metallpulver die gewünschte Reaktion nicht mehr oder nicht mehr genügend eingehen können.It is already known to change metal powder by chemical oxidation or physical processes so that no harmful reactions occur when in contact with water. For example, AT-B 236 729 and AT-B 240 128 are processes for Chemical oxidation of aluminum powder and magnesium powder is known, in which the granules forming the powder are coated with an oxide skin that protects the metal. Furthermore, it is known to provide metal powder with a coating, for example made of stearic acid. A disadvantage of these processes, however, is that either they do not provide adequate protection against water or the reactivity is reduced in such a way that the metal powders can no longer or not sufficiently react to the desired reaction.
Aus DE-A 36 26 861 war ein Verfahren zur Herstellung von handhabungssicherem Treibladungspulver auf Basis von kristallinen Sprengstoffen bekannt, bei dem die einzelnen Kristalle des Sprengstoffs mit einem Harz in einem Wirbelschichtverfahren umhüllt wurden. Weiterhin ist aus der US-A 3 706 611 ein Verfahren zur Herstellung einer pyrotechnischen Kunststoffzusammensetzung bekannt, die aus einem flüssigen Polysulfidpolymer, einem kautschukbildenden Mittel, einem Metallpulver, einem organischen Oxidationsmittel und Farbstoff besteht, wobei zuerst das Metallpulver und das flüssige Polymer bei sehr niedrigem Druck vermischt werden und dann nach und nach das Oxidationsmittel und die Farbstoffe zugegeben werden.From DE-A 36 26 861 a process for the manufacture of handling-safe propellant powder based on crystalline explosives was known, in which the individual crystals of the explosive were coated with a resin in a fluidized bed process. Furthermore, US Pat. No. 3,706,611 discloses a process for producing a pyrotechnic plastic composition which consists of a liquid polysulfide polymer, a rubber-forming agent, a metal powder, an organic oxidizing agent and a dye, the metal powder and the liquid polymer being very low first Pressure are mixed and then gradually the oxidizing agent and dyes are added.
Aus DE-B 12 34 195 ist ein Verfahren zur Herstellung beschichteter fester Teilchen mit einer polymeren Überzugsschicht in einer Dispersion bekannt. Dieses Verfahren wird entweder zum Überziehen von Pigmenten angewendet, wobei der Überzug auf Dauer völlig undurchlässig bleiben soll, oder zum Überziehen von reaktionsfähigen Substanzen, wie Pestiziden oder Düngemitteln, wobei die eingekapselte Substanz nach und nach abgegeben werden soll.From DE-B 12 34 195 a process for the production of coated solid particles with a polymeric coating layer in a dispersion is known. This process is used either to coat pigments, which should remain completely impermeable in the long term, or to coat reactive substances, such as pesticides or fertilizers, in which the encapsulated substance is to be gradually released.
Aufgabe der Erfindung ist nun die Bereitstellung eines Verfahrens zur Herstellung von pyrotechnischen Wirkmassen, die als wirksames Prinzip zum Beispiel roten Phosphor in Kombination mit Metallpulver neben anderen üblichen Inhaltsstoffen enthalten, bei dem die Wirkmasse in einem wäßrigen System verarbeitet werden kann, ohne daß das einen Teil der Wirkmasse bildende Metallpulver inaktiviert wird oder eine explosionsartige Reaktion auslösen kann.The object of the invention is now to provide a process for the preparation of pyrotechnic active compositions which, as an effective principle, contain, for example, red phosphorus in combination with metal powder in addition to other customary ingredients, in which the active composition can be processed in an aqueous system without the part the active powder forming metal powder is inactivated or can trigger an explosive reaction.
Diese Aufgabe wird gelöst durch ein Verfahren zur Herstellung von Magnesiumpulver enthaltenden pyrotechnischen Wirkmassen auf wäßriger Basis, das dadurch gekennzeichnet ist, daß das Magnesiumpulver mit einem für verdünnte Säuren und Wasser unlöslichen und für Wasser und Sauerstoff im wesentlichen undurchlässigen Kunststoff in einem Vakuumwirbelschichtverfahren beschichtet wird, wobei die Beschichtung in einer Masse von nicht mehr als 5 Gewichtsprozent, bezogen auf die Gesamtmasse des Magnesiumpulvers, vorhanden ist, das erhaltene Pulver in Wasser aufgeschlämmt, mit den anderen Bestandteilen der Wirkmasse vermischt und in die gewünschte Form gebracht wird.This object is achieved by a process for producing pyrotechnic active compositions containing magnesium powder on an aqueous basis, which is characterized in that the magnesium powder is coated with a plastic which is insoluble for dilute acids and water and essentially impermeable to water and oxygen in a vacuum fluidized bed process, where the coating in one Mass of not more than 5 percent by weight, based on the total mass of the magnesium powder, is present, the powder obtained is suspended in water, mixed with the other constituents of the active composition and brought into the desired shape.
Überraschenderweise wurde gefunden, daß durch Beschichten von Magnesiumpulvern mit einer sehr dünnen Schicht aus einem Kunststoff, der in Wasser und verdünnten Säuren unlöslich und für Wasser und Sauerstoff im wesentlichen undurchlässig ist, das Magnesiumpulver so weit inaktiviert werden kann, daß es während der Lagerung, der Verarbeitung in wäßriger Aufschlämmung und der Herstellung der pyrotechnischen Wirkmassen keine unerwünschten Reaktionen eingeht, wobei diese Beschichtung jedoch keine nachteilige Wirkung auf die Eigenschaften, insbesondere die Reaktivität, der pyrotechnischen Wirkmasse selbst hat.Surprisingly, it has been found that by coating magnesium powders with a very thin layer of a plastic which is insoluble in water and dilute acids and is essentially impermeable to water and oxygen, the magnesium powder can be inactivated to such an extent that it becomes in storage during storage Processing in an aqueous slurry and the production of the pyrotechnic active compounds do not cause any undesirable reactions, although this coating does not have an adverse effect on the properties, in particular the reactivity, of the pyrotechnic active compound itself.
Wesentlich für das erfindungsgemäße Verfahren ist die Behandlung des Magnesiumpulvers. Erfindungsgemäß wird das Magnesiumpulver mit einer Beschichtung aus einem für verdünnte Säuren und Wasser unlöslichen und für Wasser und Sauerstoff im wesentlichen undurchlässigen Kunststoff versehen. Derartige Kunststoffe sind dem Fachmann bekannt, und alle Kunststoffe, die diese Eigenschaften aufweisen und die Wirkmasse nicht nachteilig beeinflussen, sind hier geeignet. Bevorzugt werden für die Kunststoffbeschichtung Polymere oder Copolymere auf Basis von Acrylsäure, Methacrylsäure, Acrylsäureestern und/oder Methacrylsäureestern verwendet. Diese Polymere oder Copolymere eignen sich zur Bildung sehr dünner Beschichtungen, die trotzdem eine Reaktion des umhüllten Metallkorns mit Wasser oder Säure verhindern. Besonders bevorzugt wird ein Methacrylsäure-Methylmethacrylat-Copolymer verwendet. Beim Beschichten des Magnesiumpulvers kann es zu einer Agglomerierung der Teilchen kommen, was sich jedoch nicht nachteilig auf die Eigenschaften auswirkt, da die Agglomerate bei der Verarbeitung zu Wirkmassen wieder auseinanderbrechen.The treatment of the magnesium powder is essential for the method according to the invention. According to the invention, the magnesium powder is provided with a coating of a plastic which is insoluble for dilute acids and water and essentially impermeable for water and oxygen. Such plastics are known to the person skilled in the art, and all plastics which have these properties and do not adversely affect the active composition are suitable here. Polymers or copolymers based on acrylic acid, methacrylic acid, acrylic acid esters and / or methacrylic acid esters are preferably used for the plastic coating. These polymers or copolymers are suitable for forming very thin coatings which nevertheless prevent the coated metal grain from reacting with water or acid. A methacrylic acid-methyl methacrylate copolymer is particularly preferably used. When the magnesium powder is coated, the particles can agglomerate, but this does not have a disadvantageous effect on the properties, since the agglomerates break apart again when they are processed into active materials.
Die Beschichtung auf den Magnesiumteilchen muß sehr dünn sein und darf nicht mehr als 5 Gewichtsprozent, bezogen auf die Gesamtmasse des Magnesiumpulvers, betragen. Wenn die Beschichtung zu dick wird, wird die Reaktion der Teilchen in der Wirkmasse behindert, was unerwünscht ist. Besonders gute Ergebnisse werden mit Beschichtungen erzielt, die in einer Menge aufgetragen werden, welche 1 bis 4 Gewichtsprozent, insbesondere 2,5 bis 3,5 Gewichtsprozent, bezogen auf die Gesamtmasse des Magnesiumpulvers, entspricht.The coating on the magnesium particles must be very thin and must not be more than 5 percent by weight based on the total mass of the magnesium powder. If the coating becomes too thick, the reaction of the particles in the active mass is hindered, which is undesirable. Particularly good results are achieved with coatings which are applied in an amount which corresponds to 1 to 4 percent by weight, in particular 2.5 to 3.5 percent by weight, based on the total mass of the magnesium powder.
Um derartig dünne Beschichtungen auf das Magnesiumpulver gleichmäßig aufbringen zu können, wird ein Vakuum-Wirbelschichtverfahren, wie es an sich bekannt ist, verwendet. Das Wirbelschichtverfahren muß so durchgeführt werden, daß während der Beschichtung Feuchtigkeit ausgeschlossen ist. Das Verfahren eignet sich für Magnesiumpulver, das für pyrotechnische Wirkmassen verwendet werden und in wäßrigen Systemen verarbeitet werden soll.In order to be able to apply such thin coatings evenly to the magnesium powder, a vacuum fluidized bed process, as is known per se, is used. The fluidized bed process must be carried out in such a way that moisture is excluded during the coating. The process is suitable for magnesium powder, which is used for pyrotechnic active materials and is to be processed in aqueous systems.
Das mit dem Kunststoff beschichtete Magnesiumpulver kann in dieser Form gelagert werden und wird zur Herstellung der pyrotechischen Wirkmasse in Wasser aufgeschlämmt, mit den übrigen an sich bekannten Bestandteilen, zum Beispiel rotem Phosphor, vermischt und dann in die gewünschte Form gebracht.The magnesium powder coated with the plastic can be stored in this form and is slurried in water to produce the pyrotechic active composition, mixed with the other constituents known per se, for example red phosphorus, and then brought into the desired shape.
Die Stabilität des beschichteten Magnesiumpulvers während der Lagerung und während der Aufschlämmung in Wasser ist ausgezeichnet, und die Reaktivität der Wirkmasse wird nicht nennenswert beeinträchtigt.The stability of the coated magnesium powder during storage and during slurrying in water is excellent and the reactivity of the active mass is not significantly impaired.
Ein weiterer Gegenstand der Erfindung ist ein Magnesiumpulver mit einer Beschichtung aus einem für verdünnte Säuren und Wasser unlöslichen und für Wasser und Sauerstoff im wesentlichen undurchlässigen Kunststoff, wobei die Beschichtung nicht mehr als 5 Gewichtsprozent, bezogen auf die Gesamtmasse des Magnesiumpulvers, ausmacht.Another object of the invention is a magnesium powder with a coating of a plastic which is insoluble for dilute acids and water and essentially impermeable for water and oxygen, the coating making up no more than 5% by weight, based on the total mass of the magnesium powder.
Das erfindungsgemäß beschichtete Magnesiumpulver kann in dieser Form gelagert und transportiert werden. Es ist stabilisiert gegenüber einer Veränderung durch Wasser oder Sauerstoff oder Säure und kann daher vielfältig eingesetzt werden, insbesondere für Verfahren, in denen wäßrige Aufschlämmungen von Magnesiumpulver verwendet werden. Besonders bevorzugt wird das erfindungsgemäß beschichtete Magnesiumpulver zur Herstellung von pyrotechnischen Wirkmassen auf wäßriger Basis eingesetzt.The magnesium powder coated according to the invention can be stored and transported in this form. It is stabilized against change due to water or oxygen or acid and can therefore be used in a variety of ways, in particular for processes in which aqueous slurries of magnesium powder are used. The magnesium powder coated according to the invention is particularly preferably used for the production of aqueous-based pyrotechnic active compositions.
Die Erfindung wird durch die folgenden Beispiele erläutert.The invention is illustrated by the following examples.
Magnesiumpulver wurde mit einer stabilisierenden Beschichtung versehen. Es wurde ein Magnesiumpulver mit einer durchschnittlichen Teilchengröße von 90 bis 140 µm verwendet. 9,0 kg dieses Magnesiumpulvers wurden in einer Vakuumwirbelschicht verwirbelt. Es wurde eine Lösung von 3,5% Methacrylsäure-Methylmethacrylat-1:2-Copolymer in Aceton/Methanol (12%:88%) aufgesprüht. Dabei wurden die folgenden Prozeßbedingungen eingehalten:
- Systemdruck:
- etwa 250 mbar
- Gaseintrittstemperatur:
- etwa 90°C
- Sprühdruck:
- etwa 40 bar
- Sprührate:
- etwa 80 g/min
- Temperatur der Sprühlösung:
- etwa 60°C
- Kondensationstemperatur:
- etwa -35°C
- System pressure:
- about 250 mbar
- Gas inlet temperature:
- about 90 ° C
- Spray pressure:
- about 40 bar
- Spray rate:
- about 80 g / min
- Spray solution temperature:
- about 60 ° C
- Condensation temperature:
- about -35 ° C
Nach Versprühen von 2,57 kg, 5,14 kg und 7,71 kg Lösung wurden ohne Prozeßunterbrechung Proben entnommen. Dies entsprach einem Filmauftrag von 1%, 2% und 3%.After spraying 2.57 kg, 5.14 kg and 7.71 kg of solution, samples were taken without interrupting the process. This corresponded to a film order of 1%, 2% and 3%.
Mit diesen Proben wurden Stabilitätsprüfungen durchgeführt, wobei jeweils 300 mg unbeschichtetes Magnesium und mit 1%, 2% und 3% beschichtetes Magnesium untersucht wurden. Das Probenmaterial wurde dazu in einen 500 ml Zweihalskolben gebracht, der bis zum Schliffansatz in einem auf 25°C thermostatisierten Wasserbad stand. Der mit einem 100 ml Tropftrichter versehene Zweihalskolben war über eine Schlauchverbindung mit einer thermostatisierten Bürette verbunden. Diese war wiederum mit einem Druckausgleichsgefäß versehen. Als Sperrflüssigkeit in der Bürette und dem Druckausgleichsgefäß diente Wasser. Vor Beginn der Messung wurde der Bürettenstand nivelliert. Nach Temperaturangleichung der gesamten Apparatur auf 25°C wurden 50,0 ml einer 0,1 n Salzsäure aus dem Tropftrichter schnell zur vorgelegten Probe gegeben. Die zeitabhängige Wasserstoffentwicklung wurde dann durch einfaches Ablesen des in der Bürette verdrängten Wasservolumens ermittelt. Das Ergebnis wird als Quotient mW/mE aus der Wasserstoffentwicklung mW (D25 = 0,1 mg/ml) und der Einwaage mE angegeben.Stability tests were carried out on these samples, 300 mg of uncoated magnesium and 1%, 2% and 3% of magnesium being examined. For this purpose, the sample material was placed in a 500 ml two-necked flask in a water bath thermostatted to 25 ° C. The two-necked flask equipped with a 100 ml dropping funnel was connected to a thermostatted burette via a hose connection. This was in turn provided with a pressure compensation vessel. Water was used as the barrier liquid in the burette and the pressure compensation vessel. The burette level was leveled before starting the measurement. After the temperature of the entire apparatus had been brought to 25 ° C., 50.0 ml of 0.1N hydrochloric acid from the dropping funnel were quickly added to the sample. The time-dependent evolution of hydrogen was then determined by simply reading the volume of water displaced in the burette. The result is given as the quotient m W / m E from the hydrogen evolution m W (D 25 = 0.1 mg / ml) and the initial weight m E.
Bei den angegebenen Bedingungen erfolgte eine Agglomeration von Partikeln unter Bildung stabiler Sekundäragglomerate. Die mittlere Korngröße wurde dadurch von etwa 120 µm auf etwa 310 µm angehoben. Dadurch wurden die Fließeigenschaften des beschichteten Magnesiumpulvers wesentlich verbessert. Für die Auswertung wurden die Proben nicht gesiebt.Under the specified conditions, particles agglomerated to form stable secondary agglomerates. The average grain size was increased from about 120 microns to about 310 microns. This significantly improved the flow properties of the coated magnesium powder. The samples were not sieved for evaluation.
Beim nicht beschichteten Magnesiumpulver war die Wasserstoffentwicklung so stark, daß in der ersten Minute nach Zugabe der 0,1 n Salzsäure die Meßkapazität der Bürette (50 ml) überschritten wurde.In the case of the uncoated magnesium powder, the evolution of hydrogen was so strong that the measuring capacity of the burette (50 ml) was exceeded in the first minute after the addition of 0.1N hydrochloric acid.
Die Figur 1 zeigt ein Diagramm, in dem die Ergebnisse eingezeichnet sind für die auf die Einwaage bezogene Wasserstoffentwicklung mW/mE für das mit 1%, 2% und 3% beschichtete und für das nicht beschichtete Magnesiumpulver. Bei 1% und 2% Beschichtungsmenge bestehen nur geringe Unterschiede in der Wasserstoffentwicklung; es besteht jedoch eine deutliche Verzögerung im Vergleich zur nicht beschichteten Probe. Eine weitere Verbesserung erfolgt bei der mit 3% Beschichtung versehenen Probe.FIG. 1 shows a diagram in which the results are plotted for the hydrogen evolution m W / m E, based on the weight, for the magnesium powder coated with 1%, 2% and 3% and for the uncoated magnesium powder. With 1% and 2% coating quantity there are only slight differences in the hydrogen evolution; however, there is a significant delay compared to the uncoated sample. A further improvement is made in the sample provided with a 3% coating.
Claims (7)
- Process for preparing water-based pyrotechnical active substances containing magnesium powder, characterised in that in a vacuum fluidised bed process, the magnesium powder is coated with a synthetic material which is insoluble in dilute acids and water and substantially impermeable to water and oxygen, with the coating being present in an amount of not more than 5% by weight with respect to the total amount of the magnesium powder, the resulting powder is suspended in water, mixed with the other components of the active substance and brought into the desired shape.
- Process according to claim 1, characterised in that polymers or copolymers based on acrylic acid, methacrylic acid, acrylic acid esters and/or methacrylic acid esters are used as the synthetic material.
- Process according to one of the preceding claims, characterised in that the magnesium powder is coated with a methacrylic-acid-methyl-methacrylate copolymer, dissolved in a solvent.
- Process according to one of the preceding claims, characterised in that the magnesium powder is coated with the synthetic material in such an amount that a coating of 1 to 4 % by weight with respect to the total amount of the magnesium powder is achieved.
- Magnesium powder having a coating made of a synthetic material which is insoluble in dilute acids and water and substantially impermeable to water and oxygen, prepared by a process according to one of the claims 1 to 4.
- Magnesium powder according to claim 5, characterised in that the coating comprises a polymer or copolymer based on acrylic acid, methacrylic acid, acrylic acid esters and/or methacrylic acid esters.
- Use of a magnesium powder according to one of the claims 5 or 6, for preparing pyrotechnical active substances containing magnesium powder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4307237 | 1993-03-08 | ||
| DE4307237A DE4307237C1 (en) | 1993-03-08 | 1993-03-08 | Water-based prodn of active pyrotechnic materials - by coating aluminium@ or magnesium@ powder with methacrylic acid]-methyl methacrylate] copolymer, mixing in aq slurry with other components, and moulding |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0614863A1 EP0614863A1 (en) | 1994-09-14 |
| EP0614863B1 true EP0614863B1 (en) | 1997-08-13 |
Family
ID=6482223
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP94103430A Expired - Lifetime EP0614863B1 (en) | 1993-03-08 | 1994-03-07 | Process for producing metal powder containing water-based pyrotechnic agent, coated metal powder and use therof |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5541009A (en) |
| EP (1) | EP0614863B1 (en) |
| CA (1) | CA2117157A1 (en) |
| DE (2) | DE4307237C1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19605346C1 (en) * | 1996-02-14 | 1997-07-24 | Fraunhofer Ges Forschung | Phlegmatised energy carrier |
| US6077372A (en) * | 1999-02-02 | 2000-06-20 | Autoliv Development Ab | Ignition enhanced gas generant and method |
| DE10138745A1 (en) | 2001-08-07 | 2010-09-30 | Buck Neue Technologien Gmbh | Surface flare, useful to generate an artificial target for the defense of infrared controlled steering flight body, comprises a carrier foil and a pyrotechnical active mass, where a part of the foil is formed from a propellant powder |
| DE102010022983A1 (en) * | 2010-06-08 | 2011-12-08 | Rheinmetall Waffe Munition Gmbh | Two-shell explosive charge |
Family Cites Families (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1180530A (en) * | 1957-08-02 | 1959-06-04 | Le Secretaire D Etat A La Defe | Improvements to explosive mixtures containing aluminum or other metals or alloys and their manufacture |
| GB1025694A (en) * | 1962-02-19 | 1966-04-14 | North American Aviation Inc | Polymer coating of solid particles |
| AT240128B (en) * | 1963-10-03 | 1965-05-10 | Walter Marx & Co K G | Process for the chemical oxidation of aluminum powders or aluminum alloy powders |
| AT236729B (en) * | 1962-12-13 | 1964-11-10 | Walter Marx & Co K G | Process for the chemical oxidation of magnesium powder |
| US3706611A (en) * | 1965-08-26 | 1972-12-19 | Secr Defence | Method of making pyrotechnic composition containing a polysulphide polymer |
| NL6911554A (en) * | 1968-08-01 | 1970-02-03 | ||
| DE2337524A1 (en) * | 1973-07-24 | 1975-04-03 | Dynamit Nobel Ag | PYROTECHNICAL FUEL |
| US3903219A (en) * | 1973-12-18 | 1975-09-02 | Fluid Energy Process Equip | Process for mixing, pulverizing and grinding black powder |
| US4092383A (en) * | 1977-08-15 | 1978-05-30 | The United States Of America As Represented By The Secretary Of The Navy | Modification of ballistic properties of HMX by spray drying |
| US4434009A (en) * | 1981-12-03 | 1984-02-28 | Toyo Aluminium Kabushiki Kaisha | Polymer-coated metallic pigments |
| JPS58223437A (en) * | 1982-06-18 | 1983-12-26 | Tdk Corp | Inorganic powder having improved dispersibility |
| US4981535A (en) * | 1982-09-30 | 1991-01-01 | General Technology Applications, Inc. | Process for making finely divided solids |
| NO153804C (en) * | 1984-02-08 | 1986-05-28 | Dyno Indusrtrier A S Nitroglyc | PROCEDURE FOR THE COATING OF CRYSTALLINE HEAD EXPLOSIVES. |
| JPS61151551A (en) * | 1984-12-25 | 1986-07-10 | 関東電化工業株式会社 | Carrier for electrophotographic developer |
| DE3515166A1 (en) * | 1985-04-26 | 1986-10-30 | Buck Chemisch-Technische Werke GmbH & Co, 7347 Bad Überkingen | THROWING BODY FOR THE DISPLAY OF AN INFRARED SURFACE SPOTLIGHT |
| DE3626861A1 (en) * | 1986-08-08 | 1988-02-11 | Dynamit Nobel Ag | Process for producing granulated propellant charges with crystalline explosives |
| US4828882A (en) * | 1987-03-16 | 1989-05-09 | Canadian Patents & Developments Limited | Particle encapsulation technique |
| SE460848B (en) * | 1987-09-29 | 1989-11-27 | Bofors Ab | SET TO MAKE PYROTECHNICAL PRE-DRAWING AND RUNNING KITS |
-
1993
- 1993-03-08 DE DE4307237A patent/DE4307237C1/en not_active Expired - Fee Related
-
1994
- 1994-03-07 EP EP94103430A patent/EP0614863B1/en not_active Expired - Lifetime
- 1994-03-07 DE DE59403687T patent/DE59403687D1/en not_active Expired - Lifetime
- 1994-03-07 CA CA002117157A patent/CA2117157A1/en not_active Abandoned
-
1995
- 1995-07-27 US US08/513,683 patent/US5541009A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| DE59403687D1 (en) | 1997-09-18 |
| EP0614863A1 (en) | 1994-09-14 |
| US5541009A (en) | 1996-07-30 |
| DE4307237C1 (en) | 1994-04-07 |
| CA2117157A1 (en) | 1994-09-09 |
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