Pyrotechnic composition and method of manufacture thereof

Abstract

A pyrotechnic composition is provided herein. The pyrotechnic composition comprises potassium nitrate (KNO 3 ) and potassium perchlorate (KClO 4 ), an inorganic fuel containing boron, an organic fuel containing at least one of carbon, hydrogen, and oxygen, and one or more binders. The pyrotechnic composition has a heat of explosion (HEX) of about 5,000 J / g or more, a maximum flame temperature (T c ), and a gas yield of about 15 moles / kg or greater. Methods for preparing the pyrotechnic composition are also provided that include a wet granulation process.

Description

[Technical field]

[0001] This section provides background information that is related to the present disclosure, but this background information is not necessarily prior art.

[0002] Pyrotechnic compositions containing pyrotechnic materials are used in passive restraint systems, including inflators for airbag modules. Examples of such pyrotechnic compositions include ignition booster compositions (also referred to as igniters, initiators, and / or booster compositions), as well as conventional gas generants. The gas generant material burns to generate a majority of the gas products that are directed to the airbag to provide inflation. Airbag modules that use gas generants often use a squib or initiator that is electrically activated when a sudden deceleration and / or collision is sensed. A discharge from the squib / initiator can ignite the ignition agent or ignition material, which burns rapidly and exothermically, and in turn ignites the gas generant material. In many cases, the initiator may include several stages that may use one or more igniters or ignition booster compositions. Summary of the Invention [Problem to be solved by the invention]

[0003] Ignition booster materials are traditionally based on pyrotechnic formulations containing titanium hydride / potassium perchlorate (THPP) or boron / potassium nitrate (BKNO3) combinations. However, compositions containing THPP can be too explosive, resulting in undesirable destruction of the gas generant shape upon deployment and / or destruction of hardware critical to gas generation, thereby reducing the reliability of passive restraint systems. At the other end of the spectrum are compositions containing BKNO3, which may, for example, result in a charge that is too weak for some pyrotechnic applications, resulting in unreliable inflator initiation. It is therefore desirable to develop effective pyrotechnic compositions, such as ignition booster compositions, that can provide a secondary charge with an intermediate energy output capable of reliably initiating an inflator or other pyrotechnic vehicle safety device with minimal or no damage to critical components of the system.

[0004] This section provides a summary of the disclosure, but is not an exhaustive disclosure of its entire scope or all of its features.

[0005] The present disclosure provides, in certain variations, a pyrotechnic composition comprising potassium nitrate (KNO3), potassium perchlorate (KClO4), an inorganic fuel comprising boron, an organic fuel comprising one or more of carbon, hydrogen, and oxygen, and one or more binders. The pyrotechnic composition may meet one or more of the following: (i) a heat of explosion (HEX) of about 5,000 J / g or more; (ii) a maximum flame temperature (T c ) is about 2,500 K (2,227° C.) or greater, and (iii) the gas yield is about 15 moles / kg or greater.

[0006] In one embodiment, potassium nitrate (KNO3) may be present in an amount of from about 50% or more to about 70% or less by weight of the pyrotechnic composition.

[0007] In one embodiment, potassium perchlorate (KClO4) may be present in an amount of from about 10% or more to about 30% or less by weight of the pyrotechnic composition.

[0008] In one embodiment, boron may be present in an amount of from about 5% or more to about 15% or less by weight of the pyrotechnic composition.

[0009] In one embodiment, the organic fuel may be present in an amount of from about 3% or more to about 15% or less by weight of the pyrotechnic composition.

[0010] In one embodiment, the organic fuel may be selected from the group consisting of guanidine nitrate, diammonium 5,5'-bitetrazole (DABT), copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole, melamine oxalate compounds, and combinations thereof.

[0011] In one embodiment, the second organic fuel may include guanidine nitrate.

[0012] In one embodiment, the one or more binders may be selected from the group consisting of hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylates, mineral oil, and combinations thereof.

[0013] In one embodiment, the one or more binders may be present in an amount of from about 0.5% or more to about 10% or less by weight of the pyrotechnic composition.

[0014] In one embodiment, the one or more binders may include hydroxypropyl cellulose (HPC).

[0015] In one embodiment, the pyrotechnic composition satisfies one or more of the following: (i) a heat of explosion (HEX) of about 5,000 J / g or more and about 6,500 J / g or less; (ii) a maximum flame temperature upon combustion (T c ) is from about 2,500 K (2,227° C.) or more to about 3,500 K (3,227° C.) or less, and (iii) the gas yield is from about 15 mol / kg or more to about 30 mol / kg or less.

[0016] In one embodiment, the one or more binders may further comprise a mineral oil present in an amount of about 0.5% or more and 2% or less by weight of the pyrotechnic composition.

[0017] In one embodiment, the pyrotechnic composition may be in the form of granules having an average particle size (D50) of about 150 μm or more to about 850 μm or less.

[0018] In yet another variation, the present disclosure also provides a method of forming a pyrotechnic composition. The method includes mixing (i) potassium nitrate (KNO3), (ii) potassium perchlorate (KClO4), (iii) an inorganic fuel comprising boron, (iv) an organic fuel comprising one or more of carbon, hydrogen, and oxygen, and (v) one or more binders with a liquid to form a slurry. The method further includes removing at least a portion of the liquid from the slurry to form a plurality of granulated particles, sizing the plurality of granulated particles to form sized granulated particles having an average particle size (D50) of about 150 μm or more to about 850 μm or less, and drying the sized granulated particles to form a solid pyrotechnic composition. The pyrotechnic composition may satisfy one or more of the following: (i) a heat of explosion (HEX) of about 5,000 J / g or more, (ii) a maximum flame temperature (Tc) upon combustion of about 2,500 K (2,227° C.) or more, and (iii) a gas yield of about 15 moles / kg or more.

[0019] In one embodiment, the organic fuel may be selected from the group consisting of guanidine nitrate, diammonium 5,5'-bitetrazole (DABT), copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole, melamine oxalate compounds, and combinations thereof, and the organic fuel may be present in an amount of about 3% or more to about 15% or less by weight of the pyrotechnic composition, and the one or more binders may be selected from the group consisting of hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, mineral oil, and combinations thereof, and the one or more binders may be present in an amount of about 0.5% or more to about 10% or less by weight of the pyrotechnic composition.

[0020] In one embodiment, (i) potassium nitrate (KNO3) may be present in an amount of about 50% to about 70% by weight of the pyrotechnic composition, (ii) potassium perchlorate (KClO4) may be present in an amount of about 10% to about 30% by weight of the pyrotechnic composition, (iii) boron may be present in an amount of about 5% to about 15% by weight of the pyrotechnic composition, (iv) guanidine nitrite may be present in an amount of about 3% to about 15% by weight of the pyrotechnic composition, (v) hydroxypropyl cellulose (HPC) may be present in an amount of about 0.5% to about 10% by weight of the pyrotechnic composition, and (vi) mineral oil may be present in an amount of about 0.5% to about 2% by weight of the pyrotechnic composition.

[0021] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The exemplary embodiments are provided so that the disclosure is thorough and fully conveys the scope to those skilled in the art. Numerous specific details are described, such as examples of specific compositions, components, devices, and methods, in order to thoroughly understand the embodiments of the present disclosure. It will be apparent to those skilled in the art that the specific details are not necessary, and that the exemplary embodiments can be embodied in many different forms, neither of which should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0023] The terms used herein are for the purpose of describing certain exemplary embodiments only and are not intended to be limiting. As used herein, the singular forms "a," "an," and "the" may be intended to include the plural forms unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and thus specify the presence of stated features, elements, compositions, steps, integers, operations, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The open-ended term "comprising" should be understood as a non-limiting term used to describe and claim various embodiments described herein, although in certain aspects, this term may instead be understood to be a more restrictive and restrictive term, such as "consisting of" or "consisting essentially of." Thus, for any given embodiment reciting compositions, materials, components, elements, functions, integers, operations, and / or process steps, the present disclosure also specifically includes embodiments that consist of, or consist essentially of, such recited compositions, materials, components, elements, functions, integers, operations, and / or process steps. In the case of "consisting of," alternative embodiments exclude additional compositions, materials, components, elements, functions, integers, operations, and / or process steps, and in the case of "consisting essentially of," additional compositions, materials, components, elements, functions, integers, operations, and / or process steps that materially affect the basic and novel characteristics are excluded from such embodiments, but any compositions, materials, components, elements, functions, integers, operations, and / or process steps that do not materially affect the basic and novel characteristics may be included in the embodiments.

[0024] The steps, processes, and operations of the methods described herein should not be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as an order of performance. It is also understood that additional or alternative steps may be used, unless otherwise stated.

[0025] When a component, element, or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly engaged, connected, or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, intervening elements or layers may not be present. Other words used to describe relationships between elements should be construed in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0026] Terms such as first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers, and / or sections, but the steps, elements, components, regions, layers, and / or sections should not be limited by these terms unless otherwise specified. These terms may be used only to distinguish one step, element, component, region, layer, or section from another step, element, component, region, layer, or section. Terms such as "first", "second", etc., as used herein, and other numerical terms, do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer, or section discussed below can be referred to as a second step, element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0027] Spatial or temporal relative terms, such as "before," "after," "inner," "outer," "beneath," "below," "lower," "above," "upper," and the like, may be used herein to describe the relationship of one element or feature to another element or feature for ease of description, as shown in the figures. Spatial or temporal relative terms may be intended to encompass different orientations of a device or system in use or operation in addition to the orientation shown in the figures.

[0028] Throughout this disclosure, numerical values ​​represent approximate measures or limits for given values ​​and embodiments for the stated values ​​as well as ranges that encompass slight deviations from embodiments with precisely stated values. Except for the examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., amounts or conditions) in this specification, including the appended claims, should be understood to be modified in all cases by the term "about", regardless of whether "about" actually appears before the numerical value. "About" indicates that the stated numerical value allows for some imprecision (approximately or reasonably close to the value, with an approach to precision in the value). When the imprecision provided by "about" is not otherwise understood in the art in its ordinary sense, "about" as used herein at least indicates the variation that may result from ordinary methods of measuring and using such parameters. For example, "about" may include variations of 5% or less, optionally 4% or less, optionally 3% or less, optionally 2% or less, optionally 1% or less, optionally 0.5% or less, and in certain embodiments, optionally 0.1% or less.

[0029] Additionally, disclosure of a range includes disclosure of all values ​​and further divided ranges within the entire range, including the endpoints and subranges given in the range.

[0030] As used herein, the terms "composition" and "material" are used interchangeably to refer broadly to a substance that contains at least a desired chemical component, element, or compound, but may also contain additional elements, compounds, or substances, including trace amounts of impurities, unless otherwise specified.

[0031] As used herein, unless otherwise specified, amounts expressed in weight and mass are used interchangeably but should be understood to reflect the mass of a given component.

[0032] The present disclosure provides pyrotechnic compositions, which may also be referred to as igniter compositions, initiator compositions, or booster compositions. In certain variations, such pyrotechnic compositions provide one or more of the following advantages: slower burning but sufficient heat output, medium energy output, ease of ignition, high combustion flame temperature, efficient combustion at low pressure, and / or effective transfer of energy to the acceptor composition (e.g., the main gas generant material, as described further below). Although the general attributes of each of the above categories of components may vary, it is understood that some common attributes may exist and any given material may serve multiple purposes within two or more of such enumerated classes or categories. For example, guanidine nitrate may function as an organic fuel and binder in a pyrotechnic composition.

[0033] In various aspects, pyrotechnic compositions provided in accordance with the present disclosure can function as effective ignition booster compositions that are relatively safe to handle and manufacture for use in automobiles and other pyrotechnic devices, and can be handled and processed in a manner more similar to that of conventional gas generants.

[0034] A pyrotechnic composition may include a combination of one or more oxidizers, one or more fuels, and one or more binders. In certain variations, a pyrotechnic composition may include a combination of multiple oxidizers, for example, whereby an oxidizer may be nominally considered a primary oxidizer, a secondary oxidizer, etc. The one or more oxidizers are selected, along with a high-temperature burning inorganic fuel component, to form an igniter material that effectively achieves a high burn rate and energy transfer to the gas generant material upon combustion.

[0035] Oxidizers suitable for the pyrotechnic compositions of the present disclosure generally include, by way of non-limiting example, alkali metals (e.g., elements in Group 1 of the IUPAC (International Union of Pure and Applied Chemistry) Periodic Table, including Li, Na, K, Rb, and / or Cs), alkaline earth metals (e.g., elements in Group 2 of the IUPAC Periodic Table, including Be, Ng, Ca, Sr, and / or Ba), as well as ammonium nitrates, nitrites, and perchlorates, metal oxides (including Cu, Mo, Fe, Bi, La, etc.), basic metal nitrates (e.g., elements in the fourth row of the IUPAC Periodic Table, including Mn, Fe, Co, Cu, and / or Zn), transition metal complexes of ammonium nitrate (e.g., elements selected from Groups 3-12 of the IUPAC Periodic Table), metal ammine nitrates, metal hydroxides, and combinations thereof.

[0036] In certain variations, the oxidizer in the pyrotechnic composition may be selected from the group consisting of alkali metals, alkaline earth metals, and nitrates and perchlorates. For example, the one or more oxidizers may include potassium nitrate (KNO3, also nominally referred to as KP), potassium perchlorate (KClO4), or a combination of potassium nitrate (KNO3) and potassium perchlorate (KClO4). In certain variations, the oxidizer may include potassium nitrate (KNO3) and potassium perchlorate (KClO4). In such embodiments, this combination of oxidizers may provide good reactivity due to the inclusion of potassium perchlorate and advantageously reduced handling sensitivity to moisture due to the presence of nitrate-containing oxidizers. In certain aspects, potassium nitrate is used as the nitrate oxidizer because it has low moisture sensitivity and does not impart moisture sensitivity to the final ignition composition.

[0037] Each individual oxidizer may be present in the pyrotechnic composition in an amount of about 5% or more, about 10% or more, about 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 70% or more, or about 75% by weight of the pyrotechnic composition, or in an amount of about 5% or more to about 75% or less, about 10% or more to about 70% or less, about 20% or more to about 70% or less, about 40% or more to about 70% or less, about 50% or more to about 70% or less, about 5% or more to about 40% or less, or about 10% or more to about 30% by weight. In any embodiment, the cumulative total amount of all oxidizers in the pyrotechnic composition may be from about 60% to about 95% by weight, optionally from about 70% to about 90% by weight, or optionally from about 80% to about 90% by weight based on the weight of the pyrotechnic composition. Additionally or alternatively, an oxidizer such as potassium nitrate (KNO3) may be present in the pyrotechnic composition in an amount of from about 50% to about 70% by weight, or from about 60% to about 70% by weight, based on the weight of the pyrotechnic composition. In addition to potassium nitrate (KNO3), a further oxidizer such as potassium perchlorate (KClO4) may be present in the pyrotechnic composition in an amount of from about 10% to about 30% by weight, or from about 20% to about 30% by weight, based on the weight of the pyrotechnic composition.

[0038] In any embodiment, the pyrotechnic composition may include a first fuel and a second fuel. The first fuel may be an inorganic fuel that is a high-temperature burning fuel, such as boron. As used herein, the term "boron" is intended to include elemental boron as well as boron-containing compounds. The first fuel or inorganic fuel (e.g., boron) may be present in the pyrotechnic composition in an amount of about 2.5% or more, about 5% or more, about 10% or more, about 20% or less, or 15% or less, or about 2.5% or more to about 20% or less, about 5% or more to about 15% or less, or about 10% or more to about 15% or less, by weight, based on the weight of the pyrotechnic composition. It is also contemplated herein that the first fuel may further include an additional inorganic fuel. The additional inorganic fuel may include elemental metals (e.g., titanium (Ti), silicon (Si), aluminum (Al), magnesium (Mg), iron (Fe), and combinations thereof), or metal hydrides (e.g., titanium hydride (TiH2)).

[0039] The second fuel may be any suitable organic fuel containing one or more of carbon, hydrogen, oxygen, and nitrogen that upon combustion produces gases such as CO2, N2, and / or H2O to pressurize the combustion chamber, which improves the ignition of the igniter and gas generant through pressurization and distribution of hot particulates to the pyrotechnic charge to be ignited. Examples of suitable organic fuels include, but are not limited to, guanidine nitrate, 5,5'-bitetrazole diammonium (DABT), copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole, melamine oxalate compounds, and combinations thereof. In various aspects, the organic fuel may be guanidine nitrate. The organic fuel may be present in the pyrotechnic composition in an amount of about 1% or more, about 3% or more, about 5% or more, about 20% or less, about 15% or less, or about 10% or less, or in an amount of about 1% or more to about 20% or less, about 3% or more to about 15% or less, or about 5% or more to about 15% or less by weight, based on the weight of the pyrotechnic composition.

[0040] In various embodiments, the ignition composition according to certain embodiments of the present disclosure also includes one or more binders, such as a polymeric binder. Binders are commonly used in pyrotechnic compositions to increase adhesion / bonding and retain the shape of various pyrotechnic solid components, especially when they are formed by extrusion and / or molding, as well as to prevent destruction during storage and use. Typically, pyrotechnic compositions cannot be tableted or formed into pellets due to the sensitivity of the raw materials. However, as further described below, the present disclosure contemplates a method of making an igniter composition that includes a binder suitable for pyrotechnic compositions that may be in the form of tablets, pellets, or granules, and thus (e.g., have a high burn rate to maintain effective ballistic properties of the igniter). Although the binder used in the pyrotechnic composition may have some fuel value (may be considered to be a fuel in a conventional gas generant) and therefore may be considered to be a co-fuel, such binders generally do not have a high enough burn rate to function as a primary fuel in pyrotechnic compositions that require high burn rates and rapid reaction. Thus, in certain variations, a dry blend mixture of various pyrotechnic components may be mixed with a liquid binder to form granules as further described below. Alternatively, solid binder particles may be dissolved in a solvent or heated to melting point and then mixed with other pyrotechnic components to form granules as further described below. According to certain variations of the present disclosure, the binder may contribute to the ignition composition as a slower burning fuel. Suitable binders according to the present disclosure may include, but are not limited to, hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, mineral oil, or combinations thereof. The term "mineral oil" refers to a clear, colorless, nearly odorless, and tasteless liquid obtained from the distillation of petroleum containing a mixture of higher alkanes (e.g., C9 or higher alkanes). It may also be referred to as white oil, white mineral oil, liquid petrolatum, liquid paraffin, or white paraffin oil. For example, pyrotechnic compositions according to the present disclosure may include a polymeric binder, such as hydroxypropyl cellulose (HPC), and optionally an additional binder, such as mineral oil.

[0041] The binder may be present in pyrotechnic compositions according to certain embodiments of the present disclosure in an amount of about 0.5% or more, about 1% or more, about 2.5% or more, about 10% or less, about 7.5% or less, or about 5% or less, based on the weight of the pyrotechnic composition, or in an amount of about 0.5% to 10% by weight, 1% to about 7.5% by weight, or about 1% to about 5% by weight. For example, pyrotechnic compositions according to the present disclosure may include a polymeric binder such as hydroxypropyl cellulose (HPC) in an amount of about 0.5% to about 10% by weight, or about 1% to about 5% by weight, based on the weight of the pyrotechnic binder, and optionally an additional binder such as mineral oil in an amount of about 0.5% to about 1% by weight, or about 2% by weight or less (e.g., 0.5% to about 2% by weight, or about 1% to about 2% by weight) based on the weight of the pyrotechnic composition. In some embodiments, mineral oil may be substantially absent from the pyrotechnic composition (eg, 0.1% or less, or 0 (zero)% by weight).

[0042] In certain variations of the present disclosure, the pyrotechnic composition comprises: (i) potassium nitrate (KNO3) in an amount of about 50% or more by weight, e.g., about 50% or more by weight to about 70% or less by weight of the pyrotechnic composition; (ii) potassium perchlorate (KClO4) in an amount of about 10% or more by weight, e.g., about 10% or more by weight to about 30% or less by weight of the pyrotechnic composition; (iii) boron-containing inorganic fuel in an amount of about 5% or more by weight, e.g., about 5% or more by weight to about 15% or less by weight of the pyrotechnic composition; (iv) guanidine nitrate, 5,5'-bitetrazole in an amount of about 3% or more by weight, e.g., about 3% or more by weight to about 15% or less by weight of the pyrotechnic composition. and (v) an organic fuel selected from the group consisting of hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, mineral oil, and combinations thereof, in an amount of about 0.5% or more by weight of the pyrotechnic composition, e.g., from about 0.5% or more to about 10% or less by weight of the pyrotechnic composition.

[0043] In certain variations of the present disclosure, the pyrotechnic composition comprises: (i) potassium nitrate (KNO3) in an amount of about 50% or more, e.g., about 50% or more to about 70% or less, by weight of the pyrotechnic composition; (ii) potassium perchlorate (KClO4) in an amount of about 10% or more, e.g., about 10% or more to about 30% or less, by weight of the pyrotechnic composition; (iii) an inorganic fuel comprising boron in an amount of about 5% or more, e.g., about 5% or more to about 15% or less, by weight of the pyrotechnic composition; (iv) an organic fuel comprising guanidine nitrate in an amount of about 3% or more, e.g., about 3% or more to about 15% or less, by weight of the pyrotechnic composition; (v) hydroxypropyl cellulose (HPC) in an amount of about 0.5% or more, e.g., about 0.5% or more to about 10% or less, by weight of the pyrotechnic composition; and (vi) mineral oil in an amount of about 0.5% or more, e.g., about 0.5% or more to about 2% or less, by weight of the pyrotechnic composition.

[0044] In various aspects, the combination of the above-mentioned oxidizers (e.g., potassium nitrate (KNO3), potassium perchlorate (KClO4)), inorganic fuels (e.g., boron), organic fuels (e.g., guanidine nitrate), and binders (e.g., hydroxypropyl cellulose (HPC), mineral oil) in the pyrotechnic composition advantageously results in a less explosive combustion that may still provide sufficient gas production and energy output for reliable initiation of the inflator. Violence is generally understood to be an expression of the tendency of a given material to react in large quantities, or the vigor of the reaction. The reduced violence in the pyrotechnic compositions provided by the present disclosure aids in sufficient gas production to pressurize the inflator combustion chamber, resulting in improved ignition performance, as well as reduced damage to the receiver gas generator charge. The combination of properties, including heat of explosion, flame temperature, and / or gas yield, for the pyrotechnic compositions according to the present disclosure, along with sufficient gas production, contribute to this desired reduced violence.

[0045] For example, the pyrotechnic compositions described herein may have a heat of explosion (HEX) of about 3,000 J / g or more, about 4,000 J / g or more, about 5,000 J / g or more, about 8,000 J / g or less, about 7,000 J / g or less, about 6,500 J / g or less, or about 6,000 J / g or less, or from about 3,000 J / g to about 8,000 J / g or less, from about 4,000 J / g to about 7,000 J / g or less, from about 5,000 J / g to about 6,500 J / g or less, or from about 5,000 J / g to about 6,000 J / g or less.

[0046] Additionally or alternatively, the pyrotechnic compositions described herein can have a temperature of about 1500 K (1,227° C.) or more, about 2000 K (1,727° C.) or more, about 2500 K (2,227° C.) or more, about 3000 K (2,727° C.) or more, about 4500 K (4,227° C.) or less, about 4000 K (3,727° C.) or less, about 3500 K (3,227° C.) or less, or , Maximum flame temperature during combustion (T c ).

[0047] Additionally or alternatively, the pyrotechnic compositions described herein may have a gas yield of about 7.5 mol / kg or more, about 10 mol / kg or more, about 15 mol / kg or more, about 20 mol / kg or more, about 40 mol / kg or less, about 35 mol / kg or less, about 30 mol / kg or less, or about 25 mol / kg or less, or from about 7.5 mol / kg or more to about 40 mol / kg or less, from about 10 mol / kg or more to about 35 mol / kg or less, from about 15 mol / kg or more to about 30 mol / kg or less, or from about 15 mol / kg or more to about 25 mol / kg or less.

[0048] In various embodiments, the pyrotechnic compositions described herein may have one or more, two or more, or all of the following properties: (i) a heat of explosion (HEX) of about 5,000 J / g or more, e.g., from about 5,000 J / g or more to about 6,500 J / g or less; (ii) a maximum flame temperature upon combustion (T c ) is about 2500 K (2,227° C.) or more, for example, from about 2,500 K (2,227° C.) or more to about 3,500 K (3,227° C.) or less; (iii) the gas yield is about 15 mol / kg or more, for example, from about 15 mol / kg or more to about 30 mol / kg or less.

[0049] The pyrotechnic composition may also include minor amounts of other suitable pyrotechnic additives known to those skilled in the art, such as pressing aids, anti-caking agents, slugging agents, dispersing aids, flow aids, viscosity modifiers, blunting agents, etc. Generally, such pyrotechnic additives may be included in the igniter composition in amounts of from greater than zero (0) up to about 5% by weight.

[0050] In any embodiment, the pyrotechnic composition of the present disclosure may be advantageously formed into granules or particles by wet granulation techniques as further described below. In such cases, extrusion and molding processes are not required to form the pyrotechnic composition provided herein. For example, the pyrotechnic composition may have an average particle size (D50) of about 50 μm or more, about 100 μm or more, about 150 μm or more, about 250 μm or more, about 300 μm or more, about 400 μm or more, about 500 μm or more, about 1000 μm or less, about 900 μm or less, about 850 μm or less, about 800 μm or less, about 700 μm or less, about 600 μm or less, or about 50 μm or more to about 1000 μm or less, about 100 μm or more to about 900 μm or less, about 150 μm or more to about 850 μm or less, or about 200 μm or more to about 800 μm or less. In any embodiment, the pyrotechnic composition of the present disclosure may have an average particle size (D50) of from about 150 μm or more to about 850 μm or less.

[0051] In various aspects, provided herein is a method of forming a pyrotechnic composition according to the present disclosure. The method may be a wet granulation method for forming a solid pyrotechnic composition in the form of granules having the above-mentioned average particle size (D50). In any embodiment, the method may include mixing one or more oxidizers described herein (e.g., potassium nitrate (KNO), potassium perchlorate (KClO), an inorganic fuel described herein (e.g., boron), an organic fuel described herein (e.g., guanidine nitrate, 5,5'-bitetrazole diammonium (DABT), copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole, melamine oxalate compounds), and one or more binders described herein (e.g., hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, mineral oil) with a liquid to form a slurry. For example, in the mixture, (i) potassium nitrate (KNO) is about 50% or more by weight of the pyrotechnic composition, e.g., about 50% by weight of the pyrotechnic composition, (ii) potassium perchlorate (KClO4) may be present in an amount of about 10% by weight or more of the pyrotechnic composition, such as from about 10% by weight to about 30% by weight or less of the pyrotechnic composition; (iii) boron may be present in an amount of about 5% by weight or more of the pyrotechnic composition, such as from about 5% by weight to about 15% by weight or less of the pyrotechnic composition; (iv) an organic fuel, such as guanidine nitrate, may be present in an amount of about 3% by weight or more of the pyrotechnic composition, such as from about 3% by weight to about 70% by weight or less of the pyrotechnic composition; (v) one or more binders, such as hydroxypropyl cellulose (HPC), may be present in an amount of about 0.5% by weight or more of the pyrotechnic composition, such as about 0.5% by weight or more of the pyrotechnic composition, such as about 0.5% by weight or more of the pyrotechnic composition, and (vi) mineral oil may optionally be present in an amount of ...

[0052] It is contemplated herein that the one or more oxidizers, inorganic fuel, organic fuel, and one or more binders may be in a dry form, such as a powder, and may be dry blended together before mixing with the liquid to form the slurry. The liquid may be any suitable carrier. Suitable carriers include aqueous solutions that may be mostly water, however, the carrier may also contain one or more organic solvents or alcohols. In some embodiments, the carrier may include an azeotrope, which refers to a mixture of two or more liquids, such as water and a particular alcohol, that desirably evaporates in a certain stoichiometric proportion at a particular temperature and pressure. The carrier is selected for compatibility with the fuel and oxidizer components to avoid adverse reactions and also maximize the solubility of some of the components that form the slurry. Non-limiting examples of suitable carriers include water, isopropyl alcohol, n-propyl alcohol, ethanol, and combinations thereof. In some embodiments, the slurry has a liquid content of about 5% or more, about 10% or more, optionally about 15% or about 20% by weight, based on the weight of the slurry. In some embodiments, the liquid content of the slurry ranges from about 10% to 15% by weight of the slurry. In some embodiments, the slurry has a viscosity in the range of about 50,000 to 250,000 centipoise. Such a viscosity is believed to be desirable to provide suitable rheological properties that allow the slurry to flow under pressure, but also allow the slurry to remain stable.

[0053] After forming the slurry, at least a portion of the liquid may be removed from the slurry to form a plurality of granulated particles. For example, the liquid content from the slurry may be reduced by about 1% by weight or more, about 2% by weight or more, about 3% by weight or more, or about 5% by weight. For example, if the slurry has a liquid content of about 15% by weight, after removing a portion of the liquid, the plurality of granulated particles may have a liquid content of 2% by weight less than the liquid content of the slurry (i.e., the plurality of granulated particles has a liquid content of 13% by weight). The removal of the liquid may be performed by any suitable method, including introducing air into the container in which the slurry is mixed.

[0054] The plurality of granulated particles may be subjected to a sizing step to form sized granulated particles having an average particle size (D50) as described herein, for example, from about 150 μm or more to about 850 μm or less, or from about 200 μm or more to about 800 μm or less. The sizing step may be carried out using any suitable device for sizing granulated particles. For example, a screen having openings of a suitable diameter may be used, and the plurality of granulated particles may be forced through the screen to form sized granulated particles. Once sized, the sized granulated particles may be subjected to further drying to form the solid pyrotechnic composition as described herein. If necessary, the solid pyrotechnic composition may be optionally subjected to further sizing.

[0055] In various embodiments, the solid pyrotechnic composition may have one or more, two or more, or all of the following properties: (i) a heat of explosion (HEX) of about 5,000 J / g or more, e.g., from about 5,000 J / g or more to about 6,500 J / g or less; (ii) a maximum flame temperature upon combustion (T c ) is about 2,500 K (2,227° C.) or more, e.g., from about 2,500 K (2,227° C.) or more to about 3,500 K (3,227° C.) or less; (iii) the gas yield is about 15 moles / kg or more, e.g., from about 15 moles / kg or more to about 30 moles / kg or less. As discussed above, pyrotechnic compositions prepared according to various aspects of the present disclosure may have advantageous safety characteristics, including reduced vigorousness.

[0056] Various embodiments of the present technology can be further understood by the specific examples contained herein, which are provided for the purpose of illustrating how to make and use the compositions, devices, and methods according to the present teachings.

[0057] Examples 1 to 4 The following Examples 1-4 in Table 1 were presented by first weighing each of the ingredients listed in Table 1 according to the weight percent listed. The ingredients were then added to a mixing vessel and blended for approximately 3 minutes to obtain a homogenous mixture of the ingredients. The blending time may be longer or shorter than 3 minutes, but should be sufficient to ensure that a homogenous mixture is produced.

[0058] After blending the ingredients, a first granulation step is performed in which at least one processing liquid is added to the mixture of dry ingredients at a controlled flow rate. When the processing liquid is added, the mixture of ingredients begins to form granules. The rate at which the processing liquid is added to the mixture, as well as the amount of processing liquid added to the mixture, can help control the formation of granules. After the first granulation step, in which granules begin to form, the mixture is subjected to a second granulation step, and the first granule size is performed in the mixing vessel. In this regard, the temperature and pressure of the air surrounding the mixing vessel, the mixing speed, the mixing time, and the temperature of the mixture may be monitored and controlled during the second granulation step. It should be understood that for safety purposes, the total amount (i.e., mass) of the mixture that can be added to the mixing vessel can be controlled and / or limited by the volume of the mixing vessel and the size of the vent of the mixing vessel.

[0059] After the second granulation step, the wet granules may be removed from the mixing vessel and subjected to a first sizing process. Sizing of the granules may include passing the wet granules through a number of screens having openings with different preselected sizes to collect granules having a desired size (e.g., average particle diameter (D50) of 50 μm or more to 1000 μm or less). Sizing processes using equipment other than the above-mentioned screens are contemplated, but the present disclosure should not be limited to the use of screens.

[0060] After the first sizing process, the collected granules may be subjected to a weathering process. Weathering the collected granules may include at least partially drying the collected granules. Other weathering processes known to those skilled in the art may also be used without limitation. The weathered granules may then be subjected to a second sizing process to obtain granules having a particular size. The second sizing process may be similar to the first sizing process, but may use a different screen or device to obtain a desired average particle size (D50) of the granules (e.g., 200 μm or more to 800 μm or less).

[0061] Whether or not a second sizing process is performed, the weathered granules may then be subjected to a drying process to remove the processing liquid to a desired extent. Methods for drying the granules may include drying the granules using a blower or subjecting the granules to a temperature for a sufficient time to dry the granules. After drying, the granules may then be subjected to a sorting step in which a plurality of granules having different average particle sizes (D50) are collected in a desired distribution. For example, some of the granules may have a large average particle size (D50) and some of the granules may have a smaller average particle size (D50). The distribution of the amount of each average particle size may be modified and adjusted to meet any particular requirements.

[0062] [Table 1]

[0063] Each of the above examples includes an oxidizer (e.g., KNO3 and KClO4), a fuel (e.g., guanidine nitrate and boron), and a binder (e.g., HPC and mineral oil). Although not included in the above exemplary compositions, it should be understood that the compositions may include some degree of additional ingredients, such as processing aids, that are not completely removed during granulation.

[0064] The foregoing description of the embodiments is provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but may be interchangeable, where applicable, and may be used in selected embodiments even if not specifically shown or described. The same may also be modified in many ways. Such variations should not be considered as departures from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

1. 1. A pyrotechnic composition comprising: Potassium nitrate (KNO), present in an amount of from about 50% to about 70% by weight of the pyrotechnic composition. ３ )and, Potassium perchlorate (KClO), present in an amount of from about 10% to about 30% by weight of the pyrotechnic composition. ４ )and, an inorganic fuel containing boron present in an amount of from about 5% to about 15% by weight of the pyrotechnic composition; an organic fuel comprising one or more of carbon, hydrogen, and oxygen; one or more binders, The composition comprises: (i) the heat of explosion (HEX) is about 5,000 J / g or more; (ii) Maximum flame temperature during combustion (T ｃ ) is equal to or greater than about 2,500 K (2,227° C.); and (iii) a gas yield of about 15 moles / kg or greater.

2. Potassium nitrate (KNO ３ 2. The pyrotechnic composition of claim 1, wherein said pyrotechnic composition is characterized in that said pyrotechnic composition is provided with an amount of from about 60% to about 70% by weight of said pyrotechnic composition.

3. Potassium perchlorate (KClO ４ 2. The pyrotechnic composition of claim 1, wherein said pyrotechnic composition is characterized in that said pyrotechnic composition is provided with an amount of from about 20% to about 30% by weight of said pyrotechnic composition.

4. 2. The pyrotechnic composition of claim 1, wherein the boron is present in an amount of from about 10% to about 15% by weight of the pyrotechnic composition.

5. 2. The pyrotechnic composition of claim 1, wherein the organic fuel is present in an amount of from about 3% to about 15% by weight of the pyrotechnic composition and is selected from the group consisting of guanidine nitrate, diammonium 5,5'-bitetrazole (DABT), copper bisguanylurea dinitrate, hexamine cobalt (III) nitrate, copper diammine bitetrazole, melamine oxalate compounds, and combinations thereof.

6. 2. The pyrotechnic composition of claim 1, wherein the second organic fuel comprises guanidine nitrate.

7. 10. The pyrotechnic composition of claim 1, wherein the one or more binders are selected from the group consisting of hydroxypropyl cellulose (HPC), polyvinyl acetate, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyacrylate, mineral oil, and combinations thereof, and wherein the one or more binders are present in an amount of from about 0.5% to about 10% by weight of the pyrotechnic composition.

8. The composition comprises: (i) the heat of explosion (HEX) is from about 5,000 J / g to about 6,500 J / g; (ii) The maximum flame temperature during combustion (T ｃ ) is from about 2,500 K (2,227° C.) to about 3,500 K (3,227° C.); and 2. The pyrotechnic composition of claim 1, wherein the composition satisfies one or more of the following: (iii) the gas yield is from about 15 moles / kg or more to about 30 moles / kg or less.

9. 2. The pyrotechnic composition of claim 1, wherein the composition is in the form of granules having an average particle size (D50) of about 150 μm to about 850 μm.

10. 10. A method for forming a pyrotechnic composition as claimed in claim 1, said method comprising: (i) The potassium nitrate (KNO ３ ), (ii) the potassium perchlorate (KClO ４ (iii) the boron-containing inorganic fuel, (iv) the organic fuel, and (v) the one or more binders, with a liquid to form a slurry; removing at least a portion of the liquid from the slurry to form a plurality of granulated particles; sizing the plurality of granulated particles to form sized granulated particles having an average particle size (D50) of from about 150 μm to about 850 μm; and drying the sized granulated particles to form a solid pyrotechnic composition.

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