Patent Application
20140352855
The present invention relates generally to gas generating systems, and to an improved gas generating compound that may constitute a monopropellant.
The present invention relates to vehicle occupant protection systems or other safety systems employing gas generators to actuate an inflatable cushion for example. U.S. Pat. Nos. 5,035,757, 5,872,329, 6,074,502, 6,210,505, 6,287,400, 7,959,749, 6,189,927, 5,062,367, and 5,308,588 exemplify known pyrotechnic gas generating compositions and/or known gas generators and their operating environments, whereby each patent is herein incorporated by reference in its entirety. The pyrotechnic means typically include an initiator or igniter, and a gas generating composition ignitable by the igniter once the actuator is activated.
There is an ongoing initiative to provide gas generating compositions that improve upon the amount of gas produced per gram of gas generating composition, while maintaining or improving the burn rate of the gas generating composition at ambient or other operating pressures.
In accordance with the present invention, a gas generating composition includes a compound that is produced from the substitution reaction of a nitro-aromatic compound and a metal hydroxyl nitrate. The reaction product may be selected from dinitrobenzoic acid substituted basic copper nitrate, dinitrosalicylic acid substituted basic copper nitrate, potassium salt of dinitrosalicylic acid substituted basic copper nitrate, isophthalic acid substituted basic copper nitrate, potassium salt of isophthalic acid substituted basic copper nitrate, hydroxy pyridine substituted basic copper nitrate, and mixtures thereof. An oxidizer may be selected from nonmetal and metal nitrate salts; chlorate salts; metal and nonmetal perchlorate salts; metal and nonmetal oxides; basic nitrate salts, and mixtures thereof. Finally, a fuel may be selected from derivatives of bis-(1(2)H-tetrazol-5-yl)-amine; tetrazoles, triazoles, and azoles; metal and nonmetal salts of tetrazoles, triazoles, and azoles; nitrate salts of tetrazoles, triazole, and azoles; nitramine derivatives of tetrazoles, triazoles, and azoles; metal and nonmetal salts of nitramine derivatives of azoles; salts and derivatives of guanidines; azoamides; nitrate salts of azoamides; and mixtures thereof.
The present invention relates to compounds formed by substitution reactions including a metal hydroxyl nitrate, such as basic copper nitrate, and a nitro aromatic, such as dinitrobenzoic acid, as reactants. When used herein, a metal hydroxyl nitrate contains at least one hydroxide ion and at least one nitrate as a basic metal nitrate. When used herein, a “nitro aromatic” may be defined as a compound that has nitro and aromatic character. When used herein, the term “compound” is given its normal meaning, which is to say that it means a single constituent such as a fuel, an oxidizer, or any other constituent of known gas generating compositions, for example. When used herein, the term “composition” is meant to convey a mixture of several compounds such as a fuel, an oxidizer, and any other constituent of known gas generating compositions, for example. The compounds formed by nitro aromatic substitution of a metal hydroxyl nitrate are useful as gas generant constituents, and certain of these compounds may be used as a monopropellant thereby reducing the cost and complexity of manufacturing related gas generants. Furthermore, manufacturing safety is enhanced because of the ability to use these novel compounds independent of any other typical gas generant constituents such as oxidizers, slag formers, coolants, and other known constituents.
The formation reactions may be generally stated as substituting metal hydroxyl nitrates with various nitro aromatics. The metal hydroxyl nitrates may be formed with transition metals, such as but not limited to, cobalt, zinc, manganese, iron, copper, and cerium. An exemplary metal hydroxyl nitrate includes basic copper nitrate. The nitro aromatics may be selected from the group including, but not limited to, nitro benzo derivatives such as nitrobenzoic acid and dinitrobenzoic acid, derivatives thereof, and metal and nonmetal salts thereof including 3,5-dinitrobenzoate substituted basic copper nitrate; nitro salicylic derivatives such as dinotrosalicylic acid and salts thereof such as the potassium salt of dinitrosalicylic acid, potassium 3,5-dinitrosalicylate substituted basic copper nitrate, and 3,5-dinitrosalicylate substituted basic copper nitrate; Isophthalic acid and derivatives and salts thereof including the potassium salt of isophthalic acid, 5-nitroisophthalate substituted basic copper nitrate, and potassium isophthalate substituted basic copper nitrate; and pyridine and derivatives thereof such as nitro pyridine(s), hydroxyl pyridine(s), and 3,5-dinitro hydroxyl pyridine substituted basic copper nitrate.
The following examples of various species within the broader groups described above exemplify or blueprint various substitution reactions within the broader group. In general, stoichiometric amounts of the metal hydroxyl nitrate, such as basic copper nitrate, combined with the desired nitro-aromatic such as dinitrobenzoic acid yield the novel substituted metal hydroxyl nitrates.
1) Dinitrobenzoic acid substituted Basic copper nitrate:
2) Dinitrosalicylic acid substituted Basic copper nitrate:
3) Potassium salt of dinitrosalicylic acid substituted Basic copper nitrate:
4) Isophthalic acid substituted Basic copper nitrate:
5) Potassium salt of Isophthalic acid substituted Basic copper nitrate:
6) Hydroxy pyridine substituted Basic copper nitrate:
As exemplified in the examples, nitro-aromatic substituted metal hydroxyl nitrates are synthesized by reacting the metal hydroxyl nitrate (e.g. basic copper nitrate) with nitro aromatic acid in the presence of water to yield novel nitro-aromatic substituted metal hydroxyl nitrate molecules.
It is contemplated that if desired, other typical gas generating constituents such as, but not limited to the following, may be combined with the novel compounds described above, thereby forming novel gas generating compositions. These constituents include: fuels selected from tetrazoles, triazoles, triazines, and guanidines, and salts and derivatives of each type of fuel; oxidizers selected from nonmetal or metal (alkali, alkaline earth, and/or transitional metal) nitrates, nitrites, chlorates, perchlorates, and oxides; coolants, slag formers, and/or additives such as clay, talc, mica, silica, and so forth.
For example, gas generating compositions of the present invention may contain a nitro-aromatic substituted metal hydroxyl nitrate as defined herein. More preferably, the nitro-aromatic substituted metal hydroxyl nitrate may be provided at about 1-15 weight percent of the total composition. Yet further, the nitro-aromatic substituted metal hydroxyl nitrate may be provided at about 5-15 weight percent of the total composition. A first oxidizer selected from the group including nonmetal and metal nitrate salts such as ammonium nitrate, phase-stabilized ammonium nitrate, potassium nitrate, strontium nitrate; nitrite salts such as potassium nitrite; chlorate salts such as potassium chlorate; metal and nonmetal perchlorate salts such as potassium or ammonium perchlorate; oxides such as iron oxide and copper oxide; basic nitrate salts such as basic copper nitrate and basic iron nitrate, and mixtures thereof is provided. The first oxidizer is generally provided at about 0.1-80 wt % of the gas generant composition, and more preferably at about 10-70 wt %.
Further, gas generating compositions formed in accordance with the present invention may contain a secondary fuel selected from the group containing derivatives of bis-(1(2)H-tetrazol-5-yl)-amine (BTA), including its anhydrous acid and its acid monohydrate, mono-ammonium salt of bis-(1(2)H-tetrazol-5-yl)-amine, metal salts of bis-(1(2)H-tetrazol-5-yl)-amine including the potassium, sodium, strontium, copper, and zinc salts of BTA, and complexes thereof; azoles such as 5-aminotetrazole; metal salts of azoles such as potassium 5-aminotetrazole; nonmetal salts of azoles such as mono-or di-ammonium salt of 5,5′-bis-1H-tetrazole; nitrate salts of azoles such as 5-aminotetrazole nitrate; nitramine derivatives of azoles such as 5-nitraminotetrazole; metal salts of nitramine derivatives of azoles such as dipotassium 5-nitraminotetrazole; nonmetal salts of nitramine derivatives of azoles such as mono- or di-ammonium 5-nitraminotetrazole and; guanidines such as dicyandiamide; salts of guanidines such as guanidine nitrate; nitro derivatives guanidines such as nitroguanidine; azoamides such as azodicarbonamide; nitrate salts of azoamides such as azodicarbonamidine dinitrate; and mixtures thereof, and is generally provided at about 0.1-50 wt %, more preferably 0.1-30 wt %.
The gas generating compositions of the present invention may be mixed in a known manner. For example, the primary fuel formed by the substitution reaction of the nitro aromatic and the metal hydroxyl nitrate may be mixed with an oxidizer, and any other desired constituent, such as a secondary fuel described above. Other gas generating constituents known in the art, such as coolants, slag formers, desiccants, and so forth, may also be provided in known effective amounts.
For example, a gas generating compositions of the present invention may also contain an optional additive selected from the group including silicone compounds; elemental silicon; silicon dioxide; fumed silica; silicones such as polydimethylsiloxane; silicates such as potassium silicates; natural minerals such as talc and clay; lubricants such as graphite powder or fibers, magnesium stearate, boron nitride, molybdenum sulfide; fumed alumina; polyethylene; paraffin; and mixtures thereof. When included, the optional additive is generally provided at about 0.1-10%, and more preferably at about 0.1-5%.
An optional binder may be included in the gas generant composition and is selected from the group of cellulose derivatives such as cellulose acetate, cellulose acetate butyrate, carboxymethycellulose, salts of carboxymethylcellulose, carboxymethyl cellulose acetate butyrate; silicone; polyalkene carbonates such as polypropylene carbonate and polyethylene carbonate; and mixtures thereof, and when included is generally provided at about 0.1-10%, and more preferably at about 0.1-5%.
The substitution reactants and the various typical gas generant constituents described herein, may be provided by companies such as Aldrich Chemical Company or Fisher, for example. Various exemplary salts were manufactured by basic acid/base chemistry resulting in salts of nitro aromatics as described herein. In accordance with the present invention, the novel nitro-aromatic substituted metal hydroxyl nitrates of the present invention may be dry-mixed or wet-mixed with the oxidizers, secondary fuels, and other constituents of the gas generating compositions described herein to form a uniform or homogeneous mixture of the gas generating composition containing the novel compounds. The following examples illustrate the present invention, but not by way of limitation. More specifically, the examples illustrate the unexpected and surprising results of adding a nitro-aromatic substituted metal hydroxyl nitrate to compositions containing an oxidizer such as a basic metal nitrate, and a fuel such as a guanidine-based derivative.
A mixing vessel containing 2000 ml of distilled water, heated to 105 C, was provided. Gas generating constituents were provided that collectively weighed 5000 grams. Basic copper nitrate (BCN) at about 2520.40 grams (50.41 weight percent of the total constituents) and ammonium dinitrosalicylic acid (ADNSA) at about 250.00 grams (5.00 weight percent of the total constituents) were both added to the mixing vessel. The mixture was mixed, for example with a planetary mixer, for about 1-5 minutes, at a nominal speed setting of 400 rpms. Water, in an amount of 500 ml, was added as a rinse. Guanidine nitrate (GN) at about 2229.60 (44.59 weight percent of the total constituents) was then added to the mixture. The mixture was maintained at 105 C and stirred (at about 400 rpm) for about ten minutes while adding an additional 500 ml of water as a second rinse. A uniform or homogeneously mixed precipitate formed. The precipitate was dried for about 90 minutes in a temperature range of 90 C to 105 C.
A composition containing 46.6 grams of basic copper nitrate and 53.4 grams of guanidine nitrate was mixed and formed as described in Example 1. The composition was compacted and formed as a tablet. A gas generator formed as described in U.S. Pat. No. 7,537,241, herein incorporated by reference in its entirety, was loaded with 26.3 grams of the composition. Upon combustion, over a period of 0.1 seconds of combustion time, the chamber pressure peaked at about 21.5 MPa at about 0.003 seconds. A pressure trough was presented in the combustion profile from 0.02 to 0.025 seconds wherein the chamber pressure measured about 3.5 to 4.0 MPa. The chamber pressure then increased slightly from 4.0 to about 5.25 MPa from about 0.025 to about 0.035 seconds. Thereafter, the chamber pressure linearly decreased over time to a chamber pressure of about 2.5 at 0.1 seconds of combustion.
A sample of the composition formed as described in Example 2A and loaded in the same type of inflator as 2A, was inserted in a 60 L tank, wherein combustion of the composition was initiated and conducted over a period of 0.1 seconds. The combustion profile exhibited a slight combustion lag or trough from about 0.01 to about 0.03 seconds. The combustion profile then exhibited substantially linear growth to a maximum tank pressure of about 120 kPa at 0.1 seconds.
The burn rate of the composition of Example 2A was evaluated by coating a 2.5 gram cylinder of the composition with epoxy except for a top portion. The sample was then placed within a pressurized container and upon ignition, the burn rate and pressure were monitored over time. At 5 MPa, the burn rate of the sample was about 0.275 inches per second (ips). At 20 MPa, the burn rate of the sample was about 0.500 ips. At about 36 MPa, the burn rate of the sample was about 0.675 ips.
A composition containing 46.2 grams of basic copper nitrate, 43.5 grams of guanidine nitrate, and 10.3 grams dinitrobenzoic acid substituted basic copper nitrate (BCN-DNBA) (formed from the substitution reaction of basic copper nitrate (metal hydroxyl nitrate) and dinitrobenzoic acid (DNBA, nitro aromatic) as described herein), was mixed and formed as described in Example 1. The composition was compacted and formed as a tablet. A gas generator as described in Example 2A was loaded with 28.3 grams of this composition. Upon combustion, over a period of 0.1 seconds of combustion time, the chamber pressure peaked at about 20.5 MPa at about 0.003 seconds. After peak combustion, the combustion profile exhibited a regressive logarithmic curve throughout the combustion time of 0.1 seconds wherein the terminal chamber pressure at 0.1 seconds was about 1.5 MPa. The chamber pressure from 0.01-0.03 seconds ranged from about 12.5 MPa to about 5.5 MPa.
A sample of the composition formed as described in Example 3A (28.3 grams) and loaded in the same type of inflator as 2A, was inserted in a 60 L tank, wherein combustion of the composition was initiated and conducted over a period of 0.1 seconds. The combustion profile exhibited a progressive logarithmic growth to a maximum tank pressure of about 127 kPa at 0.1 seconds.
The burn rate of the composition of Example 3A was evaluated by coating a 2.5 gram cylinder of the composition with epoxy except for a top portion. The sample was then placed within a pressurized container and upon ignition, the burn rate and pressure were monitored over time. At 5 MPa, the burn rate of the sample was about 0.335 inches per second (ips). At 20 MPa, the burn rate of the sample was about 0.570 ips. At about 36 MPa, the burn rate of the sample was about 0.725 ips.
A composition containing 45.7 grams of basic copper nitrate, 44.8 grams of guanidine nitrate, and 9.2 grams of dinitrosalicylic acid substituted basic copper nitrate (BCN-DNSA) (formed from the substitution reaction of basic copper nitrate (metal hydroxyl nitrate) and ammonium dinitrosalicylic acid (nitro aromatic) as described herein), was mixed and formed as described in Example 1. The composition was compacted and formed as a tablet. A gas generator as described in Example 2A was loaded with 27.9 grams of this composition. Upon combustion, over a period of 0.1 seconds of combustion time, the chamber pressure peaked at about 23.0 MPa at about 0.003 seconds. After peak combustion, the combustion profile exhibited a regressive logarithmic curve throughout the combustion time of 0.1 seconds wherein the terminal chamber pressure at 0.1 seconds was about 1.0 MPa. The chamber pressure from 0.01-0.03 seconds ranged from about 14.8 MPa to about 7.4 MPa.
A sample of the composition formed as described in Example 4A (27.9 grams) and loaded in the same type of inflator as 2A, was inserted in a 60 L tank, wherein combustion of the composition was initiated and conducted over a period of 0.1 seconds. The combustion profile exhibited a progressive logarithmic growth to about 145 kPa at 0.1 seconds. The maximum tank pressure was about 146 kPa at about 0.09 seconds.
The burn rate of the composition of Example 4A was evaluated by coating a 2.5 gram cylinder of the composition with epoxy except for a top portion. The sample was then placed within a pressurized container and upon ignition, the burn rate and pressure were monitored over time. At 5 MPa, the burn rate of the sample was about 0.325 inches per second (ips). At 20 MPa, the burn rate of the sample was about 0.615 ips. At about 36 MPa, the burn rate of the sample was about 0.800 ips.
A composition containing 45.7 grams of basic copper nitrate, 45.1 grams of guanidine nitrate, and 9.2 grams of dinitrosalicylic acid substituted basic copper nitrate (BCN-DNSA) (formed from the substitution reaction of basic copper nitrate (metal hydroxyl nitrate) and potassium dinitrosalicylic acid (nitro aromatic) as described herein), was mixed and formed as described in Example 1. The composition was compacted and formed as a tablet. A gas generator as described in Example 2A was loaded with 28.0 grams of this composition. Upon combustion, over a period of 0.1 seconds of combustion time, the chamber pressure peaked at about 21.5 MPa at about 0.003 seconds. After peak combustion, the combustion profile exhibited a regressive logarithmic curve throughout the combustion time of 0.1 seconds wherein the terminal chamber pressure at 0.1 seconds was about 0.5 MPa. The chamber pressure from 0.01-0.03 seconds ranged from about 13.0 MPa to about 5.0 MPa.
A sample of the composition formed as described in Example 5A (28.0 grams) and loaded in the same type of inflator as 2A, was inserted in a 60 L tank, wherein combustion of the composition was initiated and conducted over a period of 0.1 seconds. The combustion profile exhibited a progressive logarithmic growth to about 153 kPa at 0.1 seconds. The maximum tank pressure was about 160 kPa at about 0.062 seconds.
The burn rate of the composition of Example 5A was evaluated by coating a 2.5 gram cylinder of the composition with epoxy except for a top portion. The sample was then placed within a pressurized container and upon ignition, the burn rate and pressure were monitored over time. At 5 MPa, the burn rate of the sample was about 0.335 inches per second (ips). At 20 MPa, the burn rate of the sample was about 0.600 ips. At about 36 MPa, the burn rate of the sample was about 0.780 ips.
A composition containing 46.2 grams of basic copper nitrate, 45.3 grains of guanidine nitrate, and 10.3 grams of dinitrobenzoic acid substituted basic copper nitrate (BCN-DNBA) (formed from the substitution reaction of basic copper nitrate (metal hydroxyl nitrate) and potassium dinitrobenzoic acid (KDNBA, nitro aromatic) as described herein), was mixed and formed as described in Example 1. The composition was compacted and formed as a tablet. A gas generator as described in Example 2A was loaded with 28.3 grams of this composition. Upon combustion, over a period of 0.1 seconds of combustion time, the chamber pressure peaked at about 18.0 MPa at about 0.003 seconds. After peak combustion, the combustion profile exhibited a regressive logarithmic curve throughout the combustion time of 0.1 seconds wherein the terminal chamber pressure at 0.1 seconds was about 0.5 MPa. The chamber pressure from 0.01-0.03 seconds ranged from about 12.0 MPa to about 4.8 MPa.
A sample of the composition formed as described in Example 6A (28.3 grams) and loaded in the same type of inflator as 2A, was inserted in a 60 L tank, wherein combustion of the composition was initiated and conducted over a period of 0.1 seconds. The combustion profile exhibited a progressive logarithmic growth to about 146 kPa at 0.1 seconds. The maximum tank pressure was about 150 kPa at about 0.060 seconds.
The burn rate of the composition of Example 6A was evaluated by coating a 2.5 gram cylinder of the composition with epoxy except for a top portion. The sample was then placed within a pressurized container and upon ignition, the burn rate and pressure were monitored over time. At 5 MPa, the burn rate of the sample was about 0.300 inches per second (ips). At 20 MPa, the burn rate of the sample was about 0.520 ips. At about 36 MPa, the burn rate of the sample was about 0.680 ips.
As shown in
Referring now to
Referring again to
Safety belt assembly 150 may also include (or be in communication with) a crash event sensor 158 (for example, an inertia sensor or an accelerometer) including a known crash sensor algorithm that signals actuation of belt pretensioner 156 via, for example, activation of a pyrotechnic igniter (not shown) incorporated into the pretensioner. U.S. Pat. Nos. 6,505,790 and 6,419,177, previously incorporated herein by reference, provide illustrative examples of pretensioners actuated in such a manner.
It should be appreciated that safety belt assembly 150, airbag system 200, and more broadly, vehicle occupant protection system 180 exemplify but do not limit gas generating systems contemplated in accordance with the present invention.
The present description is for illustrative purposes only, and should not be construed to limit the breadth of the present invention in any way. Thus, those skilled in the art will appreciate that various modifications could be made to the presently disclosed embodiments without departing from the scope of the present invention as defined in the appended claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/830,616 filed on Jun. 3, 2013.
| Number | Date | Country | |
|---|---|---|---|
| 61830616 | Jun 2013 | US |
