U.S. patent application number 13/637512 was filed with the patent office on 2013-06-20 for gas generant compositions.
The applicant listed for this patent is Sudhakar R. Ganta, Graylon K. Williams. Invention is credited to Sudhakar R. Ganta, Graylon K. Williams.
Application Number | 20130153098 13/637512 |
Document ID | / |
Family ID | 44673521 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130153098 |
Kind Code |
A1 |
Ganta; Sudhakar R. ; et
al. |
June 20, 2013 |
Gas Generant Compositions
Abstract
A fuel component for an airbag inflator, dinitrosalyicylic acid
and derivatives thereof, is used as a primary fuel in a gas
generating composition 12. A novel gas generating composition 12,
containing the primary fuel, and phase stabilized ammonium nitrate
is also provided. The fuel component may be contained within a gas
generant composition 12, within a gas generator 10. The gas
generator 10 may be contained within a gas generating system 200
such as an airbag inflator 10 or seat belt assembly 150, or more
broadly within a vehicle occupant protection system 180.
Inventors: |
Ganta; Sudhakar R.; (Troy,
MI) ; Williams; Graylon K.; (Warren, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ganta; Sudhakar R.
Williams; Graylon K. |
Troy
Warren |
MI
MI |
US
US |
|
|
Family ID: |
44673521 |
Appl. No.: |
13/637512 |
Filed: |
March 28, 2011 |
PCT Filed: |
March 28, 2011 |
PCT NO: |
PCT/US11/00560 |
371 Date: |
September 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61318138 |
Mar 26, 2010 |
|
|
|
Current U.S.
Class: |
149/56 ; 149/55;
149/67 |
Current CPC
Class: |
C06B 31/38 20130101;
C06B 31/42 20130101; C06D 5/06 20130101 |
Class at
Publication: |
149/56 ; 149/55;
149/67 |
International
Class: |
C06B 31/42 20060101
C06B031/42; C06B 31/38 20060101 C06B031/38 |
Claims
1. A gas generating composition comprising: a fuel having a
structural formula of or derived from the following structural
formula: ##STR00001## and phase stabilized ammonium nitrate as an
oxidizer.
2. The composition of item 1 comprising a fuel selected from a
metallic or nonmetallic salt of said structural formula.
3. The composition of item 1 comprising a fuel selected from an
adduct of said structure with another compound, wherein said adduct
with said other compound forms a hydrogen bonded complex.
4. The composition of item 2 wherein said metallic salt is an
alkali or alkaline earth metal salt.
5. A gas generating composition comprising: a fuel selected from
3,5-dinitrosalicylic acid, a metal or non-metal salt of 3,5
dinitrosalicylic acid, an adduct of 3,5-dinitrosalicylic acid and
mixtures thereof; and an oxidizer wet mixed with said fuel, said
oxidizer selected from ammonium nitrate and phase stabilized
ammonium nitrate.
6. A gas generating composition comprising: a primary fuel selected
from 3,5-dinitrosalicylic acid, a metal or non-metal salt of 3,5
dinitrosalicylic acid, an adduct of 3,5-dinitrosalicylic acid, and
mixtures thereof, said primary fuel provided at about 5-80 weight
percent of said composition; a second fuel selected from the group
consisting of tetrazoles and salts thereof; triazoles and salts
thereof azoles and salts thereof guanidines and salts thereof;
guanidine derivatives; imides; amides; aliphatic carboxylic acids
and salts thereof; aromatic carboxylic acids and salts thereof
nitro-aromatic carboxylic acids and salts thereof; nitrosalicylic
acids and salts thereof; amines; nitrophenols; pyrazoles;
imidazoles; azines; and mixtures thereof, said secondary fuel
provided at about 0-50 weight percent of said composition; and a
primary oxidizer selected from metal and nonmetal nitrates,
nitrites, chlorates, perchlorates, oxides, hydroxides, basic metal
nitrates, and mixtures thereof, said primary oxidizer provided at
about 20-80 weight percent of said composition.
7. The composition of claim 6 comprising an oxidizer selected from
phase stabilized ammonium nitrate, ammonium nitrate, strontium
nitrate, potassium nitrate, and mixtures thereof.
8. The composition of claim 6 wherein said second fuel is selected
from the group consisting of diammonium salt of 5,540
-bis-1H-tetrazole, monoammonium salt of bis tetrazole amine, and
mixtures thereof.
9. The composition of claim 6 wherein said primary fuel is selected
from dinitrosalicylic acid, ammonium dinitrosalicylic acid,
potassium dinitrosalicylic acid, strontium dinitrosalicylic acid,
copper dinitrosalicylic acid, and mixtures thereof
10. The composition of claim 6 wherein said primary fuel is
provided at about 25-80 weight percent of said composition; said
secondary fuel is provided at about 0.1-30 weight percent of said
composition; and said primary oxidizer is provided at about 25-75
weight percent of said composition.
11. The composition of claim 6 wherein said primary fuel is
potassium dinitrosalicylic acid at about 27 weight percent of said
composition, and ammonium nitrate at about 73 weight percent of
said composition.
12. The composition of claim 6 wherein said primary fuel is
ammonium dinitrosalicylic acid at about 10-20 weight percent, said
secondary fuel is diammonium salt of 5,5'-bis-1H-tetrazole at about
3-15 weight percent, and said oxidizer is ammonium nitrate at about
60-75 weight percent and potassium nitrate at about 5-10 weight
percent.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/318,138 filed on Mar. 26, 2010 and PCT
Application Serial No. PCT/US11/00560 filed Mar. 28, 2011.
TECHNICAL FIELD
[0002] The present invention relates generally to gas generating
systems, and to gas generating compositions employed in gas
generator devices for automotive restraint systems, for
example.
BACKGROUND OF THE INVENTION
[0003] The present invention relates to gas generating compositions
that upon combustion produce a relatively smaller amount of solids
and a relatively abundant amount of gas. It is an ongoing challenge
to reduce the amount of solids and increase the amount of gas
thereby decreasing the filtration requirements for an inflator. As
a result, the filter may be either reduced in size or eliminated
altogether thereby reducing the weight and/or size of the inflator.
Additionally, reduction of combustion solids provides relatively
greater amounts of gaseous products per gram or unit of gas
generating composition. Accordingly, less gas generant is required
when greater mols of gas are produced per gram of gas generant. The
result is typically a smaller and less expensive inflator due to
reduced manufacturing complexity.
[0004] In a related challenge, when increasing the amount of gas,
the effluent must be tailored to ensure that carbon monoxide or
other less-than-desirable gases are attenuated. For example, when
increasing the relative amounts of carbon in the gas generant, one
concern is whether the gas generant might produce more carbon
monoxide as a combustion product. As such, the effort to reduce
solids and increase gas production upon combustion, must be
balanced with combustion products that meet current effluent
standards.
[0005] Another challenge is providing gas generating compositions
that meet current USCAR requirements for chemical and thermal
stability. Chemical stability is indicative of a propellant
retaining its structural integrity over time. Dimensional stability
is indicative of chemical stability, the retention of density over
time for example. Components of the composition must be compatible
with each other with a minimum of interaction. Therefore, chemical
stability involves the mitigation of interaction of the various
constituents that are included in the gas generating
composition.
[0006] Thermal stability is the ability to retain structural
integrity when cycled between -40 C and 107-110 C, for example. For
example, the composition may be held at a temperature of -40 C for
a period of time and then quickly brought to a temperature of about
107 to 110 C and held there for a period of time. Accordingly,
retaining gas generant structural integrity while undergoing
periodic cycling between the two temperature regimes over time is
yet another challenge. Furthermore, USCAR requirements include
thermal testing by holding compositions at about 107 C for about
400 hours without a decomposition of the compositions. Certain
compositions containing phase stabilized ammonium nitrate, for
example, oftentimes present concerns with regard to thermal
stability.
[0007] Yet another concern is that the compositions must exhibit
burn rates that are satisfactory with regard to use in vehicle
occupant protection systems. In particular, compositions containing
phase stabilized ammonium nitrate may exhibit relatively lower burn
rates requiring various measures to improve the burn rate.
Accordingly, the development of energetic fuels is one ongoing
research emphasis whereby the less aggressive burn characteristics
of preferred oxidizers such as phase stabilized ammonium nitrate
are accommodated and compensated for by careful blending or
combining of new and useful constituents.
[0008] In sum, it has been found that oftentimes nitrated aromatic
compounds combined with ammonium nitrate or phase stabilized
ammonium nitrate are not clean burning and may form large amounts
of soot-like residues when combusted. Acidic nitro-aromatic
compounds provide some measure of catalytic impetus to ammonium
nitrate or phase stabilized ammonium nitrate compositions,
particularly in view of the ignitability and sustained combustion
concerns with some compositions containing ammonium nitrate
(stabilized or not).
[0009] In view of these concerns, would be an improvement in the
art to provide an ammonium nitrate or phase stabilized ammonium
nitrate based composition that meets or exceeds the relative gas
output of typical high-nitrogen fuels combined with an ammonium
nitrate or phase stabilized ammonium nitrate oxidizer while yet
retaining the performance of or improving upon the considerations
provided above.
SUMMARY OF THE INVENTION
[0010] The above-referenced concerns are resolved by gas generators
or gas generating systems containing a novel fuel constituent,
3,5-dinitrosalicylic acid (DNSA), a metallic of DNSA, a
non-metallic salt of DNSA, or an adduct of DNSA with another
compound that forms a hydrogen bonded complex. When combined with
phase stabilized ammonium nitrate (PSAN) (stabilized, for example
only, with potassium nitrate provided at 10-15% by weight of the
PSAN), one or more of the present fuels result in a gas generant
composition that exhibits optimum bum rates at relatively lower
operating combustion pressures, and optimum thermal and chemical
stability, notwithstanding the use of PSAN. Furthermore, one or
more of the present compositions combust readily at relatively
lower combustion pressures thereby resulting in relaxed
manufacturing and structural requirements for an associated gas
generator or airbag inflator. Yet further, one or more of the
present compositions when combusted result in relatively greater
amounts of gas and lower amounts of solids, and therefore improved
effluent quality.
[0011] An optional second fuel may be selected from tetrazoles and
salts thereof, triazoles and salts thereof, azoles and salts
thereof, guanidines and salts thereof, guanidine derivatives,
imides, amides, aliphatic carboxylic acids and salts thereof,
aromatic carboxylic acids and salts thereof, nitro-aromatic
carboxylic acids and salts thereof, nitrosalicylic acids and salts
thereof, amines, nitrophenols, pyrazoles, imidazoles, azines, and
mixtures thereof.
[0012] A primary oxidizer may be selected from metal and nonmetal
nitrates, nitrites, chlorates, perchlorates, oxides, other known
oxidizers and mixtures thereof.
[0013] If desired, other known constituents may also be utilized in
known effective amounts.
[0014] In further accordance with the present invention, a gas
generator or gas generating system, and a vehicle occupant
protection system incorporating the gas generant composition are
also included.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a cross-sectional side showing the general
structure of an inflator in accordance with the present
invention,
[0016] FIG. 2 is a schematic representation of an exempla vehicle
occupant restraint system containing a gas generant composition in
accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The above-referenced concerns are resolved by gas generators
or gas generating systems containing an acidic nitrated aromatic
compound as a primary fuel, the primary fuel including a member
selected from the group of 3,5-dinitrosalicylic acid (DNSA), a
metallic salt of DNSA, a non-metallic salt of DNSA, or an adduct of
DNSA with another pound that forms a hydrogen bonded complex.
Examples of salts of DNSA include ammonium dinitrosalicylic acid,
potassium dinitrosalicylic acid, strontium din salicylic acid, and
copper dinitrosalicytic acid. Examples of adducts include an duct
of DNSA and amino-triazole; of DNSA and melamine; and of DNSA and
alkyl amines. When combined with phase stabilized ammonium nitrate
(PSAN) (stabilized, for example only, with 10-15% by weight of the
PSAN with an alkali metal salt such as potassium nitrate), one or
more of the present fuels result in a gas generant composition that
exhibits optimum burn rates at relatively lower operating
combustion pressures, and optimum thermal and chemical stability,
notwithstanding the use of PSAN. Furthermore, one or more of the
present compositions combust readily at relatively lower combustion
pressures thereby resulting in relaxed manufacturing and structural
requirements for an associated gas generator or airbag inflator.
Yet further, one or more of the present compositions when combusted
result in relatively greater amounts of gas and lower amounts of
solids and therefore improved effluent quality. When used without
other fuels, the primary fuel may be provided at 20 wt % to 80 wt
%, 25 wt % to 75 wt %, or at 40 wt % to 60 wt % of the total
composition. All other percentages hereinafter make reference to
weight percents of the total composition.
[0018] Optional secondary fuels may be selected from tetrazoles
such as 5-aminotetrazole; metal salts of azoles such as potassium
5-aminotetrazole; nonmetal salts of azoles such as diammomium salt
of 5,5'bis-1H-tetrazole: nitrate salts of azoles such as
5-aminotetrazole; nitramine derivatives of azoles such as
5-aminotetrazole; metal salts of nitramine derivatives of azoles
such as potassium 5-aminotetrazole; nonmetal salts of nitramine
derivatives of azoles such as monoammonium 5-aminotetrazole; salts
of guanidines such as guanidine nitrate; nitro derivatives of
guanidines such as nitroguanidine; azoamides such as
azodicarbonamide; nitrate salts of azoamides such as
azodicarbonamidine dinitrate; aliphatic carboxylic acids such as
fumaric acid, tartaric acid, and succinic acid, and metal and
nonmetal salts thereof; aromatic carboxylic acids such as benzoic
acid, phtalic acid and isophthalic acid, and metal and nonmetal
salts thereof; nitro-aromatic carboxylic acids such as nitrobenzoic
acid, dinitrobenzoic acid, nitroisophthalic acid, and
4-hydroxydinitobenzoic acid, and metal and nonmetal salts thereof;
mono-nitrosalicylic acids such as 3-nitrosalicylic acid and
5-nitrosalicylic acid and metal and nonmetal salts thereof; amines
such as melamine; amides such as oxamide; imides; nitrophenols such
as nitrophenol, 2,4-dinitrophenol, and picric acid, and metal and
nonmetal salts thereof; triazoles such as 3-nitrotriazole and
nitrotriazolone (NTO); pyrazoles; imidazoles; azines; and mixtures
thereof The secondary fuel can be used within this system as
co-fuels to the primary fuel. U.S. Pat. Nos. 5,872,329 and
6,210,505 describes the use of these and provision of these fuels
and are both herein incorporated by reference in their entirety.
When used the secondary fuel in combination with the primary fuel
may constitute about 10-90 wt % of the gas generant composition.
Also, when the secondary fuel is employed, the primary fuel may be
provided from 5 wt % to 80 wt % of the total composition. By
itself, the optional secondary fuel may constitute 0.1-45 wt % when
used, and more preferably about 3-30 wt % when used.
[0019] An oxidizer is selected from metal and nonmetal nitrates,
nitrites, chlorates, perchlorates, oxides, hydroxides, other known
oxidizers, and mixtures thereof. The preferred primary oxidizer is
selected from ammonium nitrate and phase stabilized ammonium
nitrate, and most preferably phase stabilized ammonium nitrate. The
primary oxidizer may be provided at 20 wt % to 80 wt %, and more
preferably at 50 wt % to 80 wt % of the total composition. All
other percentages hereinafter make reference to weight percents of
the total composition.
[0020] A secondary oxidizer component is optionally selected from
at least one exemplary oxidizer selected from basic metal nitrates,
and, metal and nonmetal nitrates, chlorates, perchlorates nitrites,
and oxides, including such oxidizers as basic copper (II) nitrate,
strontium nitrate, potassium nitrite, iron oxide, and copper oxide.
Metal-containing oxidizers include those formed from alkali,
alkaline earth, and transition metal oxidizers. Other oxidizers as
recognized by one of ordinary skill in the art may also be
employed. The secondary oxidizer is generally provided at about
0-50 wt % of the gas generant composition.
[0021] If desired, other known constituents may also be utilized in
known effective amounts.
[0022] Metal and non-metal carbonates such as di-potassium
carbonate and ammonium carbonate may also be employed with an
oxidizer such as ammonium nitrate.
[0023] Processing aids such as fumed silica, boron nitride, and
graphite may also be employed. Accordingly, the gas generant may be
safely compressed into tablets, or slugged and then granulated. The
processing aid is generally provided at about 0-15 wt %, and more
preferably at about 0-5 wt %.
[0024] Slag formers may also be provided and are selected from
silicon compounds such as elemental silicon; silicon dioxide;
silicones such as polydimethylsiloxane; silicates such as potassium
silicates; natural minerals such as talc and clay, and other known
slag formers. The slag former is typically provided at about 0-10
wt %, and more preferably at about 0-5 wt %.
[0025] The compositions of the present invention may be formed from
constituents as provided by known suppliers such as Aldrich or
Fisher Chemical companies. The compositions may be provided in
granulated form and dry-mixed and compacted in a known manner, or,
wet-mixed and formulated as described in the examples, or otherwise
mixed as known in the art. The compositions may be employed in gas
generators typically found in airbag devices or occupant protection
systems, or in safety belt devices, or in gas generating systems
such as a vehicle occupant protection system, all manufactured as
known in the art, or as appreciated by one of ordinary skill.
EXAMPLES
Example 1
[0026] Wet Mix Method Including A Secondary Fuel
[0027] A composition was made by providing a jacketed mixing vessel
containing about two liters of ethanol. To this solution, about 753
grams of dinitrosalicylic acid (DNSA) was added while continuously
stilling. The solution was then heated slowly to about 105 C over
about thirty minutes and maintained throughout the remaining
process. Once the DNSA was completely dissolved, about 4352 grams
of ammonium nitrate, about 122 grams of potassium nitrate, about
227 grams of potassium carbonate (whereby potassium nitrate and
potassium carbonate taken together provide a potassium source for
phase stabilization of the ammonium nitrate), about 595 grams of
diammonium bitetrazole, and one liter of water are added together
into the vessel, while continuously and mechanically stirring. A
bright yellow precipitate forms immediately in a viscous,
paint-like consistency. After about one hour, the mix forms crumbly
solids. The mixing and heating is continued until the desired
dryness is obtained. If desired, the mix may be formed into desired
shapes such as pellets or tablets and then dried to a desired
moisture content, in an oven for example.
Example 2
[0028] Wet Mix Method
[0029] A composition was made by providing a jacketed mixing vessel
containing about two liters of water or ethanol, or any other
suitable solvent such as ethers or alcohols. To this solution, an
approximate stoichiometric amount of dinitrosalicylic acid (DNSA)
or a metal or nonmetal salt of DNSA was added while continuously
stirring. The solution was then heated slowly to about 105 C over
about thirty minutes and maintained throughout the remaining
process.
[0030] Once the DNSA was completely dissolved, an approximate
stoichiometric amount of ammonium nitrate was added and stirred
into the solution. A potassium source such as potassium nitrate was
then added in about 10-15% by weight with regard to the total
amount of ammonium nitrate added. The mixture was continually
stirred and the heat maintained as a solid formed. The mixing and
heating is continued until the desired dryness is obtained. If
desired, the mix may be formed into desired shapes such as pellets
or tablets and then dried to a desired moisture content an oven for
example. The resultant solid included stoichiometric amounts of
phase stabilized ammonium nitrate (PSAN) and ammonium
dinitrosalicylic acid (ADNSA). The resultant ADNSA crystals are
comparatively small and therefore form an intimate co-precipitation
with the ammonium nitrate.
Example 3
[0031] Wet Mix Method Including A Secondary Fuel
[0032] A composition was made by providing a stainless steel
jacketed mixing vessel containing about two liters of water. To
this solution, about 753 grams of dinitrosalicylic acid (DNSA) was
added while continuously stirring. The solution was then heated
slowly to about 105 C over about thirty minutes and maintained
throughout the remaining process. Once the DNSA was completely
dissolved, about 4352 grams of ammonium nitrate, about 122 grams of
potassium nitrate, about 227 grams of potassium carbonate (whereby
potassium nitrate and potassium carbonate taken together provide a
potassium source for phase stabilization of the ammonium nitrate),
about 595 grams of diammonium bitetrazole, and one liter of water
are added together into the vessel, while continuously and
mechanically stirring. A bright yellow precipitate forms
immediately in a viscous, paint-like consistency. After about one
hour, the mix forms crumbly solids. The mixing and heating is
continued until the desired dryness is obtained. If desired, the
may be formed or extruded into desired shapes such as pellets or
tablets and then dried to a desired moisture content, in an oven
for example.
Example 4
[0033] A composition containing about 73% ammonium nitrate and
about 27 wt % monopotassium dinitrosalicylic acid was wet mixed and
formed into a homogeneous composition in accordance with the
present invention. The resultant composition included phase
stabilized ammonium nitrate at about 75.20 wt % (the PSAN
containing 64.95 of ammo nitrate and 10.25 wt % potassium nitrate)
and ammonium dinitrosalicylic acid at about 24.80 wt %.
Example 5
[0034] A composition containing about 76.39 wt % phase stabilized
ammonium nitrate (containing about 7.64 wt % potassium nitrate as a
phase stabilizer); about 10 wt % diammonium salt of
5,5'-bis-1H-tetrazole; and about 13.61 wt % ammonium
dinitrosalicylic acid was dry mixed and formed into a homogeneous
composition in accordance with the present invention.
Example 6
[0035] A composition containing about 68.75 wt % ammonium nitrate;
about 7.64 wt % potassium nitrate; about 10 wt % di-ammonium salt
of 5.5'-bis-1H-tetrazole: and about 13.61 wt % ammonium
dinitrosalicylic acid was dry mixed and formed into a homogeneous
composition in accordance with the present invention.
Example 7
[0036] A composition containing about 67.58 ammonium nitrate; about
7.51 wt % potassium nitrate; about 7.0 wt % di-ammonium salt of
5,5'-bis-1H-tetrazole; about 3.0 wt % of dipotassium tartaric acid
and about 14.91 w ammonium dinitrosalicylic acid was dry mixed and
formed into a homogeneous composition in accordance with the
present invention.
[0037] Example 8
[0038] A composition containing about 68.4 wt % ammonium nitrate;
about 7.6 wt % potassium nitrate; about 5 wt % di-ammonium salt of
5,5'-bis-1H-tetrazole; and about 20.5 wt % ammonium
dinitrosalicylic acid was mixed and formed into a homogeneous
composition in accordance with the present invention.
Example 9
[0039] Comparative Example (PSAN-Tetrazole)
[0040] A composition containing about 73.5 wt % phase stabilized
ammonium nitrate and about 26.5 wt % ammonium salt of
5,5'-bis-tetrazole amine was dry mixed and formed into a
homogeneous composition in accordance with methods known in the
art.
Example 10
[0041] Comparative Example (PSAN-Tetrazole)
[0042] A composition/gas generant formed as provided in Example 9
was evaluated based on gaseous effluent. A given mass of the
composition contained about 3.9% carbon and when combusted in a
single-stage one mole inflator (that is containing one mole of gas
generant and operating at about 33-35 MPa), the parts per million
of the following gaseous products were measured from a 100 cubic
foot tank: 126 ppm carbon monoxide; 41 ppm ammonia; 13 ppm nitrogen
oxide; and 0 ppm nitrogen dioxide. The same mass of the same fuel
was also combusted in a double stage one mole inflator (that is
containing one mole of gas generant and operating at about 40 MPa),
and resulted in the following gaseous products as also measured
from a 100 cubic foot tank: 129 ppm carbon monoxide; 35 ppm
ammonia; 11 ppm nitrogen oxide; and 0 ppm nitrogen dioxide.
Example 11
[0043] A composition/gas generant formed as provided in Example 4
was evaluated based on gaseous effluent. A given mass of the
composition contained about 8.5% carbon and when combusted in a
single-stage one mole inflator (the same model inflator as used in
Example 10, and one that contained one mole of gas generant and
operated at about 33-35 MPa), the parts per million of the
following gaseous products were measured from a 100 cubic foot
tank: 173 ppm carbon monoxide; 14 ppm ammonia; 12 ppm nitrogen
oxide; and 0 ppm nitrogen dioxide. In accordance with the present
invention, the results illustrate that although this example had
more than twice the amount of carbon content in the gas generant
composition as compared to Example 10, there was only about a 37%
increase in the amount carbon monoxide produced upon combustion.
Furthermore, the ammonia content was about one third or about 33%
of the amount of ammonia produced in the composition Example 10.
The results were unexpected and counterintuitive in that the
expectation had been to see, a linear and increased amount of
carbon monoxide produced upon combustion. Instead, useful amounts
of carbon dioxide and nitrogen were produced while attenuating the
production of carbon monoxide as analyzed from the pre-combustion
content of carbon in the gas generant. Accordingly, the present
invention supplants less desirable gases such as ammonia with
acceptable gases such as carbon dioxide, while surprisingly
mitigating the production of carbon monoxide.
Example 12
[0044] A composition/gas generant formed as provided in Example 4
was evaluated based on gaseous effluent. A given mass of the
composition contained about 6.0% carbon and when combusted in a
single-stage one mole inflator (the same model inflator as used in
Example 10, and one that contained one mole of gas generant and
operated at about 33-35 MPa), the parts per million of the
following gaseous products were measured from a 100 cubic foot
tank: 122 ppm carbon monoxide; 11 ppm ammonia; 20 ppm nitrogen
oxide; and 0 ppm nitrogen dioxide. In accordance with the present
invention, the results illustrate that although this example had
more than 150% if the amount of carbon content in the gas generant
composition a compared to Example 10, there was less carbon
monoxide (96.8% as compared to Example 10) produced upon
combustion. Furthermore, the ammonia content was about 268% of the
amount of ammonia produced in the composition of Example 10. The
results were unexpected and counterintuitive in that the
expectation had been to see a linear amount of carbon monoxide
produced upon combustion. Instead, useful amounts of carbon dioxide
and nitrogen were produced while attenuating the production of
carbon monoxide as analyzed from the pre-combustion content of
carbon in the gas generant. Accordingly, the present invention
supplants less desirable gases such as ammonia with acceptable
gases such as carbon dioxide, while surprisingly mitigatin the
production of carbon monoxide.
[0045] The same mass of the same fuel as also combusted in a double
stage one mole inflator (the same model inflator as used in Example
10 and one that contained one mole gas generant and operated at
about 40 MPa), and resulted in the following gaseous products as
also measured from a 100 cubic foot tank: 135 ppm carbon monoxide:
14 ppm ammonia; 12 ppm nitrogen oxide; and 0 ppm nitrogen dioxide.
Again, the present invention supplants less desirable gases such as
ammonia with acceptable gases such as carbon dioxide, while
surprisingly mitigating the production of carbon monoxide.
Example 13
[0046] Comparative Example (PSAN-Tetrazole)
[0047] A composition/gas generant formed as in Example 10 was
combusted within a single stage one mole inflator as employed in
Example 10. The peak inflator chamber pressure attained in
sustained combustion was about 37 MPa at about 0.015 seconds after
combustion began. Gas outputs within a 60-liter ballistic tank were
measured from the beginning of combustion at T.sub.0 through 0.1
seconds after combustion. The ballistic tank pressure steadily
increased up through 0.05 seconds after combustion began, and then
leveled off at a sustained pressure of about 31-32 MPa through 0.1
seconds after combustion began. Sustained pressure indicates
suitable gas generating properties that accommodate the sustained
pressure utilized in vehicle occupant protection systems.
Example 14
[0048] A composition/gas generant formed in accordance with the
present invention and as described in Example 4, was combusted
within a single stage one mole inflator as employed in Example 10.
the peak inflator chamber pressure attained in sustained combustion
was about 32 MPa at about 0.013 seconds after combustion began. Gas
outputs within a 60-liter ballistic tank were measured from the
beginning of combustion at T.sub.0 through 0.1 seconds after
combustion. The ballistic tank pressure steadily increased up
through 0.05 seconds after combustion began, and then leveled off
at a sustained pressure of about 28-31 MPa through 0.1 seconds
after combustion began. Sustained pressure indicates suitable gas
generating properties that accommodate the sustained pressure
utilized in vehicle occupant protection systems. Quite
unexpectedly, it has been discovered that compositions provided in
accordance with the present invention operate at a peak inflator
pressure that is 5 MPa lower than the inflator of Example 13, and
yet provide substantially equivalent amounts of sustained pressure
in the ballistic tank. Accordingly, it can be seen that the present
compositions can sustainably combust at a lower inflator pressure
thereby relaxing the structural requirements of the inflator while
yet providing similar performance from the standpoint of gas
generation over time.
Example 15
[0049] A composition/gas generant formed in accordance with the
present invention and as described in Example 4, was combusted
within a single stage one mole inflator similar or equivalent to
the one employed in Example 10. The peak inflator chamber pressure
attained in sustained combustion was about 26 MPa at about 0.015
seconds after combustion began. Gas outputs within a 60-liter
ballistic tank were measured from the beginning of combustion at
T.sub.0 through 0.1 seconds after combustion. The ballistic tank
pressure steadily increased up through 0.05 seconds after
combustion began, and then leveled off at a sustained pressure of
about 30-28 MPa through 0.1 seconds after combustion began.
Sustained pressure indicates suitable gas generating properties
that accommodate the sustained pressure utilized in vehicle
occupant protection systems. Quite unexpectedly, it has been
discovered that compositions provided in accordance with the
present invention operate at a peak inflator pressure that is about
11 MPa lo than the inflator of Example 13, and yet provide
substantially equivalent amounts of sustained pressure in the
ballistic tank. Accordingly, it can be seen that the present
compositions can sustainably combust at a lower inflator pressure
thereby relaxing the requirements of the inflator while yet
providing similar performance from the standpoint of gas generation
over time.
Example 16
[0050] A composition/gas generant formed in accordance with the
present invention and as described in Example 4, was combusted
within a single stage one mole inflator similar or equivalent to
the one employed in Example 10. The peak inflator chamber pressure
attained in sustained combustion was about 22.5 MPa at about 0.013
seconds after combustion began. Gas outputs a 60-liter ballistic to
ere measured from the beginning of combustion at T.sub.0 through
0.1 seconds after combustion. The ballistic tank pressure steadily
increased up through 0.05 seconds after combustion began, and then
leveled off at a sustained pressure of about 30-28 Pa through 0.1
seconds after combustion began. Sustained pressure indicates
suitable gas generating properties that accommodate the sustained
pressurized in vehicle occupant protection systems. Quite
unexpectedly, it has been discovered that compositions provided in
accordance with the present invention operate at a peak inflator
pressure that is about 14.5 MPa lower than the inflator of Example
13, and yet provide substantially equivalent amounts of sustained
pressure in the ballistic tank. Accordingly, it can be seen that
the present compositions can sustainably combust at a lower
inflator pressure thereby relaxing the structural requirements of
the inflator while yet providing similar performance from the
standpoint of gas generation over time.
Example 17
[0051] A composition/gas generant formed in accordance with the
present invention and as described in Example 4, was combusted
within a single stage one mole inflator similar or equivalent to
the one employed in Example 10. The peak inflator chamber pressure
attained in sustained combustion was about 20 MPa at about 0.015
seconds after combustion began. Gas outputs within a 60-liter
ballistic tank were measured from the beginning of combustion at
T.sub.0 through 0.1 seconds after combustion. The ballistic tank
pressure steadily increased up through 0.05 seconds after
combustion began and then leveled off at a sustained pressure of
about 28-30 MPa through 0.1 seconds a combustion began. Sustained
pressure indicates suitable gas generating properties that
accommodate the sustained pressure utilized in vehicle occupant
protection systems. Quite unexpectedly, it has been discovered that
compositions provided in accordance with the present invention
operate at a peak inflator pressure that is about 17 MPa lower than
the inflator of Example 13, and yet provide substantially
equivalent amounts of sustained pressure in the ballistic tank.
Accordingly, it can be seen that the present compositions can
sustainably combust at a lower inflator pressure thereby relaxing
the structural requirements of the inflator while yet providing
similar performance from the standpoint of gas generation over
time.
Example 18
[0052] A composition gas generant formed in accordance with the
present invention and as described in Example 4, was combusted
within a single stage one mole inflator similar or equivalent to
the one employed in Example 10. The peak inflator chamber pressure
attained in sustained combustion was about 7.5 MPa at about 0.015
seconds after combustion began. Gas outputs within a 60-liter
ballistic tank were measured from the beginning of combustion at
T.sub.0 through 0.1 seconds after combustion. The ballistic tank
pressure steadily increased up through 0.05 seconds after
combustion began, and then leveled off at a sustained pressure of
about 28-27 MPa through 0.1 seconds after combustion began.
Sustained pressure indicates suitable gas generating properties
that accommodate the sustained pressure utilized in vehicle
occupant protection systems. Quite unexpectedly, it has been
discovered that compositions provided in accordance with the
present invention operate at a peak inflator pressure that is about
19.5 MPa lower than the inflator of Example 13, and yet provide
substantially equivalent amounts of sustained pressure in the
ballistic tank. Accordingly, it can be seen that the present
compositions can sustainably combust at a lower inflator pressure
thereby relaxing the structural requirements of the inflator while
yet providing similar performance from the standpoint of gas
generation over time.
Example 19
[0053] A composition formed as described in Example 4 exhibited
burn rates in inches per second (ips) of about: 0.64 at 1000 pounds
per square inch gauge (psig); 0.82 at 2000 psig 0.98 at 2500 psig;
1.02 at 3500 psig; 1.12 at 4500 psig; and 1.22 at 5500 psig.
Example 20
[0054] Comparative Example (PSAN-Tetrazole)
[0055] A composition formed as described in Example 10 exhibited
burn rates in inches per second (ips) of about: 0.48 at 1000 pounds
per square inch gauge (psig); 0.82 at 2000 psig; 0.92 at 2500 psig;
1.02 at 3500 psig; 1.08 at 4500 psig; and 1.12 at 5500 psig.
[0056] When compared to Example 19, it can be seen that
compositions of the present invention exhibit suitable burn rates
substantially equivalent to another state-of-the-art gas generant
composition as described in Example 10.
Example 21
[0057] A composition formed to contain a primary fuel of ammonium
dinitrosalicylic acid at about 10-20 weight percent, a secondary
fuel of diammonium salt of 5,5'-bis-1H-tetrazole at about 3-15
weight percent, and phase stabilized ammonium nitrate containing
ammonium nitrate and potassium nitrate as an oxidizer with the
ammonium nitrate at about 60-75 weight percent and potassium
nitrate at about 5-10 weight percent.
[0058] As illustrated above, gas generating compositions of the
present invention including salts of dinitrosalicylic acid combined
with phase stabilized ammonium nitrate result in low combustion
solids, with reduced levels of less desirable combustion gases
compared to other state of-the-art gas generants while operating at
reduced combustion pressures. Other benefits may include reduced
manufacturing costs, improved thermal stability, improved chemical
ability, and/or reduced processing costs.
[0059] As shown in FIG. 1, an exemplary inflator or generating
system 10 incorporates a dual chamber design containing a primary
gas generating composition 1 formed as described herein, that may
be manufactured as known in the art. U.S. Pat. Nos. 6,422,601,
6,805,377, 6,659,500, 6,749,219, and 6,752,421 exemplify typical
airbag inflator designs and are each incorporated herein by
reference in their entirety.
[0060] Referring now to FIG. 2, the exemplary inflator or gas
generating system 10 described above may also be incorporated into
an airbag system 200. Airbag system 200 includes at least one
airbag 202 and an inflator 10 containing a gas generant composition
12 in accordance with the present invention, coupled to airbag 202
so as to enable fluid communication with an interior of the airbag.
Airbag system 200 may also include (or be in communication with) a
crash event sensor 210. Crash event sensor 210 includes a known
crash sensor algorithm that signals actuation of bag system 200
via, for example, activation of airbag inflator 10 in the event of
a collision
[0061] Referring again to FIG. 2, airbag system 200 may also be
incorporated into a broader; more comprehensive vehicle occupant
restraint system 180 including additional elements such as a safety
belt assembly 150. FIG. 2 shows a schematic diagram of one
exemplary embodiment of such a restraint system. Safety belt
assembly 150 includes a safety belt housing 152 and a safety belt
100 extending from housing 152. A safety belt or mechanism 154 (for
example, a spring-loaded mechanism) may be coupled to an end
portion of the belt. In addition, a safety belt pretensioner 156
containing gas generating composition 12 may be coupled to belt
retractor mechanism 154 to actuate the retractor mechanism in the
event of a collision. Typical seat belt retractor mechanisms which
may be used in conjunction with the safety belt embodiments of the
present invention are described in U.S. Pat. Nos. 5,743,480,
5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597 546,
incorporated herein by reference. Illustrative examples of typical
tensioners with which the safety belt embodiments of the present
invention may be combined are described in U.S. Pat. Nos. 6,505,790
and 6,419,177, incorporated herein by reference.
[0062] 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.
[0063] It should be appreciated that safety belt assembly 150,
airbag system 200, and re broadly, vehicle occupant protection
system 180 exemplify but do not limit gas generating systems
contemplated in accordance with the present invention.
[0064] It should further be understood that the preceding is merely
a detailed description of various embodiments of this invention and
that numerous changes to the disclosed embodiments can be made in
accordance with the disclosure herein without departing from the
scope of the invention. The preceding description, therefore, is
not meant to the scope of the invention. Rather, the scope of the
invention is to be determined only by the appended claims and their
equivalents.
* * * * *