JPH06199588A - Fireworks - Google Patents

Abstract

PURPOSE: To obtain a pyrotechnic material capable of the controlled combustion and consisting of an azide compound and an oxidizer.

CONSTITUTION: In the pyrotechnic material consisting of the oxidation-reduction pair components of the azide compound and the oxidizer compound, the oxidation-reduction pair causes exothermic reaction, the azide compound component has <8 μm average article diameter in the longest crystalline dimension and the oxidizer has <1.0 μm average particle diameter.

COPYRIGHT: (C)1994,JPO

Description

Detailed Description of the Invention

[0001]

This invention relates to a particular dimension for providing more efficient combustion.
The present invention relates to pyrotechnic bodies having nsion and a manufacturing method thereof.

[0002]

BACKGROUND OF THE INVENTION It is known in the art to combine certain pyrotechnic materials to provide combustion for a variety of applications. U.S. Pat.No. 3,931,040,
Compositions of sodium azide and metal oxides are described to form compositions that are found to be convenient for combustion applications. The invention described in that specification relates to the production of nitrogen for lasers. U.S. Pat.No. 4,021,275
The specification describes a similar combination of azides, oxides and nitrate compounds for producing a gas generated in a safety airbag, i.e. a safety airbag for passenger protection. ing. U.S. Pat.No. 4,37
No. 6,002 describes azide and metal oxide and residual control agents for producing nitrogen gas.
The combination consisting of t) is described.

A continuing problem in the art is the production of some pyrotechnic compositions in which the components of the pyrotechnic reaction proceed towards complete combustion. Traditionally, bodies with irregular and uncontrolled metal azide / metal oxide surface coverage have been produced by mixing methods. The product is generally disproportionan on the surface of the metal azide.
te) contained a metal oxide dispersion.

[0004]

[Means, Actions and Effects for Solving the Problems] The present finding is concerned with guiding a person skilled in the art to a means of arranging the reactants in an integrated juxtaposed manner in a combined body. Advance the technology. By properly placing the reactants around the fixed object,
The pyrotechnic of the present invention provides a pyrotechnic with controlled combustion. A pyrotechnic structure composed of the pyrotechnic of the present invention may then be burned at a desired burn rate by methods known to those skilled in the art.

The pyrotechnic article of the present invention is an air bag safety restraint system for occupant protection of automobiles, trucks, buses, and / or other vehicles in which safty air bags may be useful. Is found useful in the rapid production of gas for use in. In addition, gas generators for military applications such as ballast would be a useful application. The utility of the present invention will be appreciated for devices that require rapid production of gases such as those generated for lasers.

According to the gist of the present invention, an azide-oxidizing agent
(oxidizer) -redox couple (redox
in a pyrotechnic material consisting of couple)] components, wherein said redox couple undergoes an exothermic reaction and said azide component has an average particle size of less than about 8 microns in its longest crystal dimension. And a oxidizer having a mean particle size of less than about 1.0 micron in diameter. The azide component present in the pyrotechnic of the present invention comprises 40-90% by weight, preferably 60-70% by weight, most preferably 64-66% by weight of the pyrotechnic. The average particle size of the azide component is less than about 8 microns, preferably less than 5 microns, in the length of its longest crystal dimension,
Most preferably it is less than 3 microns. The azide is usually combined with a metal or metal salt. The metal is
An oxidant capable of interacting with an oxidant in a redox couple
nt). The metal is an alkali metal and /
Alternatively, it is preferably an alkaline earth metal. In particular, the metal azide combination consists essentially of sodium azide, potassium azide, lithium azide, calcium azide and / or barium azide, most preferably sodium azide.

The oxidizer comprises one or more elements of the first, second and / or third transition series elements of the periodic table. The oxidant may be one of the aforementioned transition series elements, or some and / or combinations thereof.
Or some combination th
ereof and / or contract). The oxidizing agent and / or the slagging agent is an oxide of a metal selected from the first transition series and / or the second transition series, for example, iron oxide, nickel oxide, vanadium oxide, copper oxide, titanium oxide. , But not limited to manganese oxide, zinc oxide, tantalum oxide and / or niobium oxide, and other oxides such as silicon oxide and / or aluminum oxide. Most preferably, the metal is selected from iron oxide and / or silicon oxide. Preferred Genus of the Invention
Are metal oxides, but other general groups such as carbonates,
It is contemplated that sulfides, sulfites, oxalates, halides, especially chlorides, and nitrides can be used with the metal oxides and are within the scope of the invention. A limitation on the oxidant component when applying it to an azide is its solubility in aqueous solution.
However, the limitation on the operability of the oxidizer component in the combustion performance of said pyrotechnics lies in the acceleration of the reaction of the azide versus the companion component. The reason is that it is linked to the oxidant component (c
oupled). In essence, the scope of the invention is
Another reduction / oxidation interaction, known to those skilled in the art as a redox couple, is included, whereby an exothermic reaction is created by the azide / oxidant-redox pair, which exothermic reaction leads to combustion of the azide. Enough to maintain.

The oxidant component is generally spherically dimensionally
No sphere geometry is required. Of the geometrical dimensions produced as oxidizer components, the shortest dimension is on average 1.0 micron or less, preferably 0.
It is less than 5 microns, most preferably less than 0.2 microns. The longest dimension of the oxidant component is not critical to the invention. Geometric and variable geometries such as platelets, spheres, needles, fibres, and variable geometries may be conveniently associated with the azide component. The preferred geometric shape is a sphere.

Particle size is measured with a Brinkmann 2010 PSA instrument (particle size analyzer) from Sybron Corp. of Westbury, NY. The average size is 8
Approximately 0.5 while exhibiting an arithmetic mean (sub-micron)
The measured distribution was from microns to 30 microns. Generally, in a preferred embodiment, the average particle size of the azide component exhibits consistent particle size measurements within the range of 1-3 microns.

The oxidizer component is integrally juxtaposed and / or associated with the azide component. Juxtaposition and / or coordination (communi
cation) can be of various forms, such as core / shell shapes,
It can have a continuous and / or discontinuous phase that encloses the azide. The azide is preferably uniformly coated with the oxidant. Azides are usually core / shell conjugates.
on) is the core. In such a combination, the oxidizing agent and the azide form a pyrotechnic material. Pyrotechnics are small plates, balls,
It can take the form of needles, fibers and other geometric shapes. When the pyrotechnic material is formed, a plurality of pyrotechnic materials are combined by the forming means to prepare one structure. The structure can then be used as a final product.

Most of its general forms
In, at least one of the oxidants must be present. This requirement makes it easy to provide a complete redox couple and yet to provide a supplemental component for associating with the azide. Link (c
Ommunication means that the two components physically interact in such a way that there is a continuous reaction between the two components when initiating combustion. It has been recognized that a combination of metal oxides provides excellent pyrotechnic components for the production of usable and preferred pyrotechnics.
In particular, a combination of iron oxide and silicon oxide is a preferred embodiment of the oxidizer component. However, both iron oxide and / or silicon oxide may be used individually in the absence of the other in a preferred embodiment. The oxidizer component is about 10
~ 60% by weight, preferably 30-40% by weight, most preferably
It should be present at 34-36% by weight. Of the bound iron oxide and silicon oxide components, the range of iron oxide is preferably 0-60 wt%, most preferably 20-30 wt%. The range of silicon oxide is preferably 0 to 50% by weight, most preferably 5 to 15% by weight. Preferred combinations of the present invention, sodium azide (NaN ₃₎ from about 65 weight percent, of iron oxide (Fe 2 _{O 3)} 25 wt% and silicon dioxide (SiO ₂₎ 10
% By weight.

In its most general form, the method of combining the azide component and the oxidant component is by a wet chemistry technique. Wet chemistry is commonly known to those skilled in the art as co-precipitation.
The present invention actually provides a means of precipitating saturated dissolved components with colloidal suspensions, while subsequently taking advantage of the co-precipitation method, and subsequently combining the individual components into pyrotechnic shapes. . Specifically, the inventive step in the method of making a pyrotechnic of the present invention is a means of providing communication in the pyrotechnic. This means can be achieved by the chemical precipitation method and the dispersion can be achieved by mechanical mixing means to ensure the dispersion of the colloidal solution, followed by thorough mixing of the two-component system. Finally, precipitation is carried out by mixing the aqueous solution with alcohol. Further alcohols which can be used for the purposes of the present invention are ethanol, isopropanol, methanol, n-propyl alcohol. Ketones such as acetone, but not limited thereto, can be used sufficiently.

According to another aspect of the present invention, the following steps
(a)-(d): i.e. (a) combining the azide component in a saturated first solution and a suspension of one or more oxidant components by mechanical mixing in a vessel Process, (b)
Withdrawing the first solution as a regulated spray, (c) precipitating the bound azide and oxidant components with a second solution, and (d) a fire. There is provided a method for manufacturing a pyrotechnic product, which comprises the step of forming a craft.

Means for controlling the spray liquid, such as spray nozzles, atomizers or pressure devices, can be used in the process. Upon controlled mixing, the spraying means preferably achieves a particle size of less than about 12 microns and preferably up to about 7 microns. Particle size is measured by diameter. Preference is given to using spray nozzles. The second solution of the above method is preferably alcohol, most preferably isopropyl alcohol.

The pyrotechnics described above may be prepared into structures to produce the final product. Pressing or molding methods, such as hydraulic pressing methods, mechanical pressing methods, extrusion methods or means of pressing pyrotechnics into a unitary structure may be used.

[0016]

The following examples serve to illustrate the invention in more detail, but without limiting the scope of the invention.

Example 1 In Example 1, 1,800 g of analytical grade NaN ₃ per 2000 g of distilled water was combined with NaN _3.
To obtain a saturated solution of. Fe ₂ O ₃ (R-1599D grade, 0.2 micron particle size, Harcros Pigm, Toronto, Canada
ents) 134 g and Cab-O-Sil pyrogenic silica (particle size 0.014 micron, Shakerheig, Ohio, USA)
48 g (obtained from Cabot, Inc., hts) was mixed with the saturated solution and shaken in an ultrasonic bath to form a dispersed colloidal suspension. This solution was placed in a container and constantly stirred, then "Jetmixer" [the mixing method is described in US Pat.
No. 770, which is herein incorporated by reference) under a pressure of 20 psi.
6mm nozzle (Spraying, Wheaton, IL, USA)
Pumped into the mixing chamber at a rate of 0.5 liters per minute (from the Systems Company).
4 liters of isopropyl alcohol were pumped into the mixing chamber at a rate of 1 liter per minute to aqueous solution
/ Alcohol / mixture was obtained. The mixture was passed through a 1 micron glass fiber filter. The filtered cake was dried in a steel jacketed container to produce pyrotechnic powder. The accompanying drawings are representative scanning electron micrographs of the pyrotechnic material.

The above powder was mixed with 4% by weight of water [in the form of a mixture of Tullanox (obtained from Cabot Co., Shakerheights, Ohio, USA) and water]. The powder was pressed into a mold to form pellets of dimensions 6.4 mm x 6.4 mm x 25.4 mm, then dried. The pellets had a density of 1.93 g per cubic centimeter (cc). All sides except one side of the pellet were coated with thermoplastic epoxy. The pellets were placed in a high pressure vessel and pressurized with nitrogen to an initial pressure of 100 psi. The pellets were ignited with a squib at the uncoated end and the burn rate was measured. The burning rate was measured to be 47 mm / sec.

Example 2 In Example 2, except that the iron oxide was needle-shaped synthetic red iron oxide (Grade 403, average particle size 0.4 micron, obtained from Harcros Pigments, Toronto, Canada). Was prepared as described in Example 1. Burning rate is 44
It was measured in mm / sec.

Example 3 The slurry was mixed as described in Example 1 except that isopropyl alcohol was added directly into the slurry without pressure. The filtered cake was treated in the same manner as in Example 1 to obtain a powdered pyrotechnic material.

The resulting pellets are cubic centimeters (c
Pressed to a density of 2 g per c). The burning rate was measured.
The burning rate was measured to be 47 mm / sec.

Example 4 40 g of sodium azide, 16.4 g of iron oxide (R-1599D),
5.6 g of silicon oxide (Cab-O-Sil pyrogenic silica) was mechanically bonded and ball-milled. The pellets obtained by pressing the ball-milled powder had a density of 2.0 g / cc. The burning rate obtained was 39 mm / s.

Example 5 In Example 5, the same amounts of sodium azide, iron oxide and silicon oxide as in Example 4 were used in Example 4 using 110 ml of water.
Mixed as described in. The mixture was then dried in a steam jacketed container. The pellets obtained by pressing the dry powder had a density of 1.93 g / cc. The burning rate obtained was 29 mm / s.

The linear burn rate indicates the efficiency of the combustion process. The higher the burn rate per mm / s, the more efficient the combustion process. It is noted that the present invention exhibits a 62% increase in burn rate.

[Brief description of drawings]

1 is a representative scanning electron micrograph of the pyrotechnic material of the present invention.

Claims (21)

[Claims] 1. A pyrotechnic comprising an azide-oxidizer / redox pair component, wherein the redox couple causes an exothermic reaction, and the azide component is less than about 8 microns in its longest crystal dimension. A pyrotechnic material characterized in that the oxidizer has an average particle size of about 1.0 micron and the oxidizer has an average particle size of less than about 1.0 micron in diameter. 2. A metal and / or metal selected from the group consisting of alkali metal, alkaline earth metal and / or some combination thereof and / or some combination therebetween. The pyrotechnic material according to claim 1, which is bound to those salts. 3. The pyrotechnic material according to claim 2, wherein the metal is sodium. 4. The oxidizer component is iron, silicon, nickel, vanadium, copper, titanium, manganese, aluminum, zinc, tantalum, niobium, some combination thereof and / or some combination therebetween. The pyrotechnic according to claim 1, which is bound to a metal selected from the group consisting of: 5. The pyrotechnic material of claim 1, wherein the oxidizer component comprises iron oxide, silicon oxide, and / or some combination thereof and / or some combination therebetween. . 6. The dimension of the azide component is 5
The pyrotechnic according to claim 1, which is less than micron. 7. The dimension of the azide component is 3
The pyrotechnic according to claim 1, which is less than micron. 8. The dimension of the oxidizer component is 0.5.
The pyrotechnic according to claim 1, which is less than micron. 9. The dimension of the oxidizer component is 0.2.
The pyrotechnic according to claim 1, which is less than micron. 10. The pyrotechnic material according to claim 1, wherein the azide component accounts for 40 to 90% by weight and the oxidant component accounts for 10 to 60% by weight. 11. The pyrotechnic material according to claim 1, wherein the azide component accounts for 60 to 70% by weight, and the oxidizer component accounts for 30 to 40% by weight. 12. The pyrotechnic material according to claim 1, wherein the azide component accounts for 64-66% by weight, and the oxidant component accounts for 34-36% by weight. 13. The pyrotechnic material of claim 1, wherein the oxidizer component is associated with the azide component. 14. The oxidizer component is 0-60% by weight iron oxide or 0-50% by weight silicon dioxide, some of their combinations and / or some of their combinations. Fireworks described in 11. 15. The pyrotechnic material according to claim 11, wherein the oxidizer component is 20 to 30% by weight of iron oxide and 5 to 15% by weight of silicon dioxide. 16. The pyrotechnic according to claim 1, wherein a plurality of the pyrotechnics are combined to form one structure. 17. The pyrotechnic material according to claim 1, wherein the structure is combined with an airbag safety restraint device for protecting an occupant. 18. The following steps (a) to (d): ie (a) a saturated azide component in a saturated first solution and a suspension of one or more oxidant components in a container. Binding by mechanical mixing, (b) withdrawing the first solution as a controlled spray, (c) second solution of the bound azide and oxidizer components A method for producing a pyrotechnic material, which comprises a step of precipitating the same by using (d) and a step of forming a pyrotechnic material. 19. The method of claim 18, wherein the conditioned spray liquid is formed by a nozzle. 20. The method of claim 18, wherein the second solution is isopropyl alcohol. 21. The adjusted spray liquor achieves a particle size of from about 7 microns to about 12 microns.
The described method.