EP1377534A2 - Gas generants containing silicone fuels - Google Patents
Gas generants containing silicone fuelsInfo
- Publication number
- EP1377534A2 EP1377534A2 EP00963598A EP00963598A EP1377534A2 EP 1377534 A2 EP1377534 A2 EP 1377534A2 EP 00963598 A EP00963598 A EP 00963598A EP 00963598 A EP00963598 A EP 00963598A EP 1377534 A2 EP1377534 A2 EP 1377534A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- gas generant
- silicone
- generant composition
- metal
- group
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 239000000203 mixture Substances 0.000 claims description 65
- 229920001296 polysiloxane Polymers 0.000 claims description 39
- 229910052751 metal Inorganic materials 0.000 claims description 27
- 239000002184 metal Substances 0.000 claims description 27
- 239000002826 coolant Substances 0.000 claims description 22
- 239000007800 oxidant agent Substances 0.000 claims description 15
- AXZAYXJCENRGIM-UHFFFAOYSA-J dipotassium;tetrabromoplatinum(2-) Chemical group [K+].[K+].[Br-].[Br-].[Br-].[Br-].[Pt+2] AXZAYXJCENRGIM-UHFFFAOYSA-J 0.000 claims description 14
- 229910001487 potassium perchlorate Inorganic materials 0.000 claims description 14
- BDAGIHXWWSANSR-NJFSPNSNSA-N hydroxyformaldehyde Chemical compound O[14CH]=O BDAGIHXWWSANSR-NJFSPNSNSA-N 0.000 claims description 11
- 229910000018 strontium carbonate Inorganic materials 0.000 claims description 11
- 239000000446 fuel Substances 0.000 claims description 10
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical class OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims description 9
- 229910052755 nonmetal Inorganic materials 0.000 claims description 8
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 6
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 6
- 150000003891 oxalate salts Chemical class 0.000 claims description 6
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 claims description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical class OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 5
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 4
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 claims description 4
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 3
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 3
- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 claims description 3
- 229910001486 lithium perchlorate Inorganic materials 0.000 claims description 3
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims description 3
- 239000001095 magnesium carbonate Substances 0.000 claims description 3
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims description 3
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 claims description 3
- 239000000347 magnesium hydroxide Substances 0.000 claims description 3
- 229910001862 magnesium hydroxide Inorganic materials 0.000 claims description 3
- 229910000000 metal hydroxide Inorganic materials 0.000 claims description 3
- 150000004692 metal hydroxides Chemical class 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 150000002823 nitrates Chemical class 0.000 claims description 3
- KQAGKTURZUKUCH-UHFFFAOYSA-L strontium oxalate Chemical compound [Sr+2].[O-]C(=O)C([O-])=O KQAGKTURZUKUCH-UHFFFAOYSA-L 0.000 claims description 3
- GDDNTTHUKVNJRA-UHFFFAOYSA-N 3-bromo-3,3-difluoroprop-1-ene Chemical compound FC(F)(Br)C=C GDDNTTHUKVNJRA-UHFFFAOYSA-N 0.000 claims description 2
- XTEGARKTQYYJKE-UHFFFAOYSA-M Chlorate Chemical class [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 claims description 2
- 150000002826 nitrites Chemical class 0.000 claims description 2
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 2
- 235000010333 potassium nitrate Nutrition 0.000 claims description 2
- 239000004323 potassium nitrate Substances 0.000 claims description 2
- 150000004679 hydroxides Chemical class 0.000 claims 3
- 229910052783 alkali metal Inorganic materials 0.000 claims 2
- 150000001340 alkali metals Chemical class 0.000 claims 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims 2
- 150000001342 alkaline earth metals Chemical class 0.000 claims 2
- QXDMQSPYEZFLGF-UHFFFAOYSA-L calcium oxalate Chemical compound [Ca+2].[O-]C(=O)C([O-])=O QXDMQSPYEZFLGF-UHFFFAOYSA-L 0.000 claims 1
- 238000002485 combustion reaction Methods 0.000 description 34
- 239000007789 gas Substances 0.000 description 29
- 230000002459 sustained effect Effects 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 5
- 229910052914 metal silicate Inorganic materials 0.000 description 5
- -1 oxides Chemical class 0.000 description 5
- 239000003380 propellant Substances 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- 239000000470 constituent Substances 0.000 description 4
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 125000005375 organosiloxane group Chemical group 0.000 description 2
- 125000004430 oxygen atom Chemical group O* 0.000 description 2
- 229920005573 silicon-containing polymer Polymers 0.000 description 2
- 229910052712 strontium Inorganic materials 0.000 description 2
- 239000002585 base Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910001960 metal nitrate Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 125000000962 organic group Chemical group 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 150000004760 silicates Chemical group 0.000 description 1
- 159000000008 strontium salts Chemical class 0.000 description 1
- 229910052917 strontium silicate Inorganic materials 0.000 description 1
- QSQXISIULMTHLV-UHFFFAOYSA-N strontium;dioxido(oxo)silane Chemical compound [Sr+2].[O-][Si]([O-])=O QSQXISIULMTHLV-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B33/00—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide
- C06B33/06—Compositions containing particulate metal, alloy, boron, silicon, selenium or tellurium with at least one oxygen supplying material which is either a metal oxide or a salt, organic or inorganic, capable of yielding a metal oxide the material being an inorganic oxygen-halogen salt
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B23/00—Compositions characterised by non-explosive or non-thermic constituents
- C06B23/04—Compositions characterised by non-explosive or non-thermic constituents for cooling the explosion gases including antifouling and flash suppressing agents
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06D—MEANS FOR GENERATING SMOKE OR MIST; GAS-ATTACK COMPOSITIONS; GENERATION OF GAS FOR BLASTING OR PROPULSION (CHEMICAL PART)
- C06D5/00—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets
- C06D5/06—Generation of pressure gas, e.g. for blasting cartridges, starting cartridges, rockets by reaction of two or more solids
Definitions
- the present invention generally relates to gas generant compositions for inflators of occupant restraint systems.
- High gas yield gas generants often lose large amounts of heat to the inflator body and surroundings during combustion, and thereby result in a lower generant burn rate and a reduced performance.
- Compositions provided in accordance with the present invention exhibit a rapid and sustained burn at ambient pressure.
- Other benefits may include a relatively lower combustion temperature and/or an increase in the moles of gas produced per gram of gas generant composition.
- compositions or propellants containing silicone and a perchlorate oxidizer exhibit a relatively rapid burn rate and sustainable combustion at ambient pressure. Nevertheless, to sustain combustion, the combustion temperature is quite hot. As a result, these compositions are not suitable for certain applications unless an adequate heat sink is also provided. Therefore, the manufacturing cost of the inflator or combustion vessel again increases.
- Silicone as a fuel is advantageous over other known nonazide fuels known to be useful in occupant restraint systems, for example. Because silicone does not contain nitrogen, undesirable nitrogen oxides are reduced or eliminated as combustion products. Additionally, silicone also provides elasticity to the gas generant composition thereby reducing the propensity for fracture of the gas generant over time. Finally, silicone aids in sustaining combustion at ambient pressure.
- gas generant compositions containing silicone as a fuel an oxidizer selected from the group including metal and nonmetal perchlorates such as potassium perchlorate, lithium perchlorate, and ammonium perchlorate; and, a coolant selected from the group including metal carbonates, metal bicarbonates, metal oxalates, and metal hydroxides.
- an oxidizer selected from the group including metal and nonmetal perchlorates such as potassium perchlorate, lithium perchlorate, and ammonium perchlorate
- a coolant selected from the group including metal carbonates, metal bicarbonates, metal oxalates, and metal hydroxides the addition of a coolant to a composition containing a perchlorate oxidizer and a silicone fuel results in a composition that combusts at rapid and sustained burn rates at ambient pressure. Additionally, the combustion temperature is substantially lower than other state of the art compositions.
- Preferred gas generant compositions contain coolants having more negative heats of formation. Stated another way, preferred coolants of the present invention will preferably exhibit a relatively greater negative heat of formation. Accordingly, dissociation of the coolant upon combustion of the gas generant composition results in an endothermic combustion reaction thereby resulting in a cooler combustion temperature. Furthermore, when coolants such as strontium carbonate are employed, strontium silicate is formed thereby forming an insulation around the propellant as it burns. As a result, the heat that is released upon combustion is conserved by the insulating effect of the metal silicate. Although strontium carbonate is the most preferred coolant, other metal salts also exhibit similar characteristics.
- compositions containing at least one silicone polymer (organosiloxane polymers) as a fuel, at least one oxidizer, and at least one coolant component containing a metallic salt and/or base combust at ambient pressure at acceptable combustion temperatures.
- Silicone is defined as any of a large group of siloxane polymers based on a structure consisting of alternate silicon and oxygen atoms with various organic radicals (or functional groups) attached to the silicon. Radicals include, but are not limited by the group including methyl, methoxy, and amino.
- silicone organosiloxane
- Hawley describes silicone (organosiloxane) as any of a large group of siloxane polymers based on a structure consisting of alternate silicon and oxygen atoms with various organic radicals attached to the silicon:
- Formula 2 Silicone Example Note, "n" in the Formulas indicates a multiple of the polymeric group or portion of the molecule given within the brackets, to include the organic groups attached to the silicon.
- Exemplary silicones include those disclosed in U.S. Patent Nos.
- compositions of the present invention contain silicone as a fuel.
- the fuel component is provided at 1 0-25% by weight of the gas generant composition.
- the gas generant compositions of the present invention contain one or more primary oxidizers selected from the group including metal and nonmetal perchlorates.
- exemplary secondary oxidizers include but are not limited to phase stabilized ammonium nitrate, ammonium nitrate, potassium nitrate, and strontium nitrate. Stated another way, secondary oxidizers may be selected from the group including metal and nonmetal chlorates, oxides, nitrates, and nitrites, or other well known oxidizers.
- a coolant is selected from the group including metal carbonates, metal oxalates, metal bicarbonates, and metal hydroxides.
- Metal is defined as alkali, alkaline earth, and transitional metals.
- Exemplary coolants include but are not limited to strontium carbonate, magnesium carbonate, calcium carbonate, potassium carbonate, strontium oxalate, and magnesium hydroxide.
- An additional benefit of the coolant is that upon combustion, the resulting metal and silicate ions formed during combustion will form metal silicates. As a result, a coating will form within the combustion chamber and insulate the propellant within the pressure vessel thereby conserving the heat of reaction and contributing to a strong and sustained burn rate at ambient pressure.
- compositions include silicone, a metal perchlorate oxidizer, and an alkaline earth carbonate.
- a most preferred composition contains silicone, potassium perchlorate, and strontium carbonate. This composition results in the formation of strontium silicates. The substantial negative heat of formation of strontium carbonate results in an endothermic combustion reaction. As a result the combustion temperature is reduced. counters the heat loss that generally results from high gas yield gas generants.
- Metal silicates are formed upon combustion of the gas generant compositions containing silicone and metal salts as coolants.
- Strontium silicates or other metal silicates
- the gas generant composition contains 10-25% by weight of silicone, 30-85% by weight of a primary oxidizer, and 1 -30% by weight of a coolant. If desired, one or more secondary oxidizers are employed at 30-50% by weight of the gas generant composition.
- the gas generant constituents in similarly sized granular or smaller particulates are added to a tumble blender at 100°C and homogeneously blended, preferably for at least two hours. Silicone is preferably added as a resin that is previously blended with a curing agent. In general, the order in which the constituents are added is not critical so long as they are homogeneously blended. Other known wet and dry blending methods may also be used. Once blending is complete, the gas generant constituents may be extruded or formed into specific shapes such as elongated extrusions, pellets, sheets, or granules.
- Table 1 exemplifies the present invention. As shown in the table, compositions consisting of silicone and a perchlorate oxidizer have rapid and sustained burn rates (at 3000 psi) greater than or equal to one inch per second. These combustion properties have been observed at ambient pressure wherein the burn rate is approximately 0.4 inches per second or greater. Nevertheless, the combustion temperatures are relatively high. See Examples 2 and 3. However, when a coolant such as a metal carbonate is added, the temperatures (Celsius) in certain cases are notably reduced. See Examples 1 7, 21 , and 24, for example.
- compositions containing ammonium nitrate and/or other metal nitrates or secondary oxidizers in amounts greater than 50% by weight of the gas generant composition did not exhibit sufficient burn rates (.4 inches per second or greater) at ambient pressure.
- Strontium salts that are not oxidizers are preferred given the greater cooling effect.
- certain compositions exhibit relatively higher temperatures than a preferred embodiment containing silicone, strontium carbonate and potassium perchlorate, for example, but still sustained rapid combustion at ambient pressure. As a result, these compositions are still desirable from the perspective that a less robust inflator is required.
- Combustion properties may be tailored by adding known ballistic modifiers and catalysts if desired.
- the gas generant constituents of the present invention are available from well-known sources such as Fisher Chemical or Aldrich.
- the silicone polymers may be purchased, for example, from General Electric in Waterford, New York.
- compositions of the present invention are useful in many applications requiring gas generation. These compositions have particular utility as gas generant compositions that may be combusted to inflate an airbag in a vehicle occupant protection system, for example.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Combustion & Propulsion (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
- Air Bags (AREA)
Abstract
Gas generating compositions are provided containing silicon, a metal or nonmetal perchlorate oxidizer, and a coolant selected from the group including metal carbonates, metal bicarbonates, metal oxalates, and metal hydroxides. These compositions exhibit rapid and sustained burn rates at ambient pressure while maintaining acceptable combustion temperatures.
Description
GAS GENERANTS CONTAINING SILICONE FUELS CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application Serial Nos. 60/1 54,242 and 60/1 54,293 filed September 1 6, 1 999.
BACKGROUND OF THE INVENTION Field of the Invention The present invention generally relates to gas generant compositions for inflators of occupant restraint systems. High gas yield gas generants often lose large amounts of heat to the inflator body and surroundings during combustion, and thereby result in a lower generant burn rate and a reduced performance. Compositions provided in accordance with the present invention exhibit a rapid and sustained burn at ambient pressure. Other benefits may include a relatively lower combustion temperature and/or an increase in the moles of gas produced per gram of gas generant composition.
Certain applications incorporating gas generation require a relatively fast burn at ambient pressure, as compared to known nonazide gas generant compositions. Many known nonazide compositions simply cannot sustain a combustion burn rate, adequate for inflation of an airbag for example, under ambient conditions. To overcome this disadvantage, combustion must occur in pressurized conditions. As a result, the combustion vessel (an airbag gas generator for example) must be manufactured to accommodate pressures of 1000 pounds per square inch (psi) or greater. The need to pressurize the combustion vessel during combustion requires a more robust inflator and therefore increases the manufacturing costs.
Certain gas generant compositions or propellants containing silicone and a perchlorate oxidizer (compositions containing silicone and potassium perchlorate, for example) exhibit a relatively rapid burn rate and sustainable combustion at ambient pressure. Nevertheless, to sustain combustion, the
combustion temperature is quite hot. As a result, these compositions are not suitable for certain applications unless an adequate heat sink is also provided. Therefore, the manufacturing cost of the inflator or combustion vessel again increases. Silicone as a fuel is advantageous over other known nonazide fuels known to be useful in occupant restraint systems, for example. Because silicone does not contain nitrogen, undesirable nitrogen oxides are reduced or eliminated as combustion products. Additionally, silicone also provides elasticity to the gas generant composition thereby reducing the propensity for fracture of the gas generant over time. Finally, silicone aids in sustaining combustion at ambient pressure.
Therefore, a gas generant composition utilizing silicone as a primary fuel and yet exhibiting a rapid and sustained burn rate along with an acceptable combustion temperature would be an improvement in the art.
SUMMARY OF THE INVENTION
The above-referenced problems are resolved by gas generant compositions containing silicone as a fuel; an oxidizer selected from the group including metal and nonmetal perchlorates such as potassium perchlorate, lithium perchlorate, and ammonium perchlorate; and, a coolant selected from the group including metal carbonates, metal bicarbonates, metal oxalates, and metal hydroxides. In accordance with the present invention, the addition of a coolant to a composition containing a perchlorate oxidizer and a silicone fuel results in a composition that combusts at rapid and sustained burn rates at ambient pressure. Additionally, the combustion temperature is substantially lower than other state of the art compositions.
Preferred gas generant compositions contain coolants having more negative heats of formation. Stated another way, preferred coolants of the present invention will preferably exhibit a relatively greater negative heat of
formation. Accordingly, dissociation of the coolant upon combustion of the gas generant composition results in an endothermic combustion reaction thereby resulting in a cooler combustion temperature. Furthermore, when coolants such as strontium carbonate are employed, strontium silicate is formed thereby forming an insulation around the propellant as it burns. As a result, the heat that is released upon combustion is conserved by the insulating effect of the metal silicate. Although strontium carbonate is the most preferred coolant, other metal salts also exhibit similar characteristics.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
In accordance with the present invention, compositions containing at least one silicone polymer (organosiloxane polymers) as a fuel, at least one oxidizer, and at least one coolant component containing a metallic salt and/or base, combust at ambient pressure at acceptable combustion temperatures. Silicone is defined as any of a large group of siloxane polymers based on a structure consisting of alternate silicon and oxygen atoms with various organic radicals (or functional groups) attached to the silicon. Radicals include, but are not limited by the group including methyl, methoxy, and amino.
The term "silicone" as used herein will be understood in its generic sense. Hawley describes silicone (organosiloxane) as any of a large group of siloxane polymers based on a structure consisting of alternate silicon and oxygen atoms with various organic radicals attached to the silicon:
CH, CH, CH
-OSi- [-O— Si ]n OSi-
I I I
CH3 CH3 CH3
Formula I: Silicone Example
Or, silicone can be more generically represented as shown in Formula 2:
CxH2x+ 1 CxH2x+ 1 CxH2x+ 1
I I I -OSi-[-O Si ]n OSi-
I I I
CxH2x+ 1 CxH2x+ 1 xH2x+ 1
Formula 2: Silicone Example Note, "n" in the Formulas indicates a multiple of the polymeric group or portion of the molecule given within the brackets, to include the organic groups attached to the silicon.
Exemplary silicones include those disclosed in U.S. Patent Nos.
5,589,662, 5,610,444, and 5,700,532, and, in TECHNOLOGY OF POLYMER COMPOUNDS AND ENERGETIC MATERIALS, Fraunhofer-lnstitut fur Chemische
Technologie (ICT), 1 990, each reference and document herein incorporated by reference.
The compositions of the present invention contain silicone as a fuel. The fuel component is provided at 1 0-25% by weight of the gas generant composition.
The gas generant compositions of the present invention contain one or more primary oxidizers selected from the group including metal and nonmetal perchlorates.
If desired, exemplary secondary oxidizers include but are not limited to phase stabilized ammonium nitrate, ammonium nitrate, potassium nitrate, and strontium nitrate. Stated another way, secondary oxidizers may be selected from the group including metal and nonmetal chlorates, oxides, nitrates, and nitrites, or other well known oxidizers.
A coolant is selected from the group including metal carbonates, metal oxalates, metal bicarbonates, and metal hydroxides. "Metal" is defined as alkali, alkaline earth, and transitional metals. Exemplary coolants include but are
not limited to strontium carbonate, magnesium carbonate, calcium carbonate, potassium carbonate, strontium oxalate, and magnesium hydroxide.
An additional benefit of the coolant is that upon combustion, the resulting metal and silicate ions formed during combustion will form metal silicates. As a result, a coating will form within the combustion chamber and insulate the propellant within the pressure vessel thereby conserving the heat of reaction and contributing to a strong and sustained burn rate at ambient pressure.
Preferred compositions include silicone, a metal perchlorate oxidizer, and an alkaline earth carbonate. A most preferred composition contains silicone, potassium perchlorate, and strontium carbonate. This composition results in the formation of strontium silicates. The substantial negative heat of formation of strontium carbonate results in an endothermic combustion reaction. As a result the combustion temperature is reduced. counters the heat loss that generally results from high gas yield gas generants.
Metal silicates are formed upon combustion of the gas generant compositions containing silicone and metal salts as coolants. Strontium silicates (or other metal silicates) function as ceramic insulators. Therefore, the metal silicates formed upon combustion insulate the propellant chamber thereby maintaining sufficient heat proximate to the burning surface of the propellant and improving combustion characteristics. As such, the heat of combustion is endothermically minimized by the negative heat of formation of the coolant, and is then retained during combustion by the additional insulating benefit. The gas generant composition contains 10-25% by weight of silicone, 30-85% by weight of a primary oxidizer, and 1 -30% by weight of a coolant. If desired, one or more secondary oxidizers are employed at 30-50% by weight of the gas generant composition. The gas generant constituents in similarly sized granular or smaller particulates are added to a tumble blender at 100°C and homogeneously blended, preferably for at least two hours. Silicone is preferably added as a resin that is previously blended with a curing agent. In
general, the order in which the constituents are added is not critical so long as they are homogeneously blended. Other known wet and dry blending methods may also be used. Once blending is complete, the gas generant constituents may be extruded or formed into specific shapes such as elongated extrusions, pellets, sheets, or granules.
Table 1 exemplifies the present invention. As shown in the table, compositions consisting of silicone and a perchlorate oxidizer have rapid and sustained burn rates (at 3000 psi) greater than or equal to one inch per second. These combustion properties have been observed at ambient pressure wherein the burn rate is approximately 0.4 inches per second or greater. Nevertheless, the combustion temperatures are relatively high. See Examples 2 and 3. However, when a coolant such as a metal carbonate is added, the temperatures (Celsius) in certain cases are notably reduced. See Examples 1 7, 21 , and 24, for example.
Table 1
In general, compositions containing ammonium nitrate and/or other
metal nitrates or secondary oxidizers in amounts greater than 50% by weight of the gas generant composition did not exhibit sufficient burn rates (.4 inches per second or greater) at ambient pressure. Strontium salts that are not oxidizers are preferred given the greater cooling effect. Compare Examples 1 9 and 24. Furthermore, in accordance with the present invention, certain compositions exhibit relatively higher temperatures than a preferred embodiment containing silicone, strontium carbonate and potassium perchlorate, for example, but still sustained rapid combustion at ambient pressure. As a result, these compositions are still desirable from the perspective that a less robust inflator is required.
Combustion properties may be tailored by adding known ballistic modifiers and catalysts if desired.
The gas generant constituents of the present invention are available from well-known sources such as Fisher Chemical or Aldrich. The silicone polymers may be purchased, for example, from General Electric in Waterford, New York.
The compositions of the present invention are useful in many applications requiring gas generation. These compositions have particular utility as gas generant compositions that may be combusted to inflate an airbag in a vehicle occupant protection system, for example.
While specific embodiments have been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of any claims which are derivable from the description herein, and any and all equivalents thereof.
Claims
1 . A gas generant composition comprising: silicone as a fuel; an oxidizer selected from the group consisting of metal and nonmetal perchlorates; and a coolant selected from the group consisting of alkali, alkaline earth, and transitional metal carbonates, bicarbonates, oxalates, and hydroxides.
2. The gas generant composition of claim 1 further comprising: a secondary oxidizer selected from the group consisting of metal and nonmetal nitrates.
3. The gas generant composition of claim 1 wherein said oxidizer is selected from the group consisting of potassium perchlorate, ammonium perchlorate, and lithium perchlorate.
4. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and strontium carbonate.
5. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and strontium oxalate.
6. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and calcium oxalate.
7. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and calcium carbonate.
8. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and magnesium hydroxide.
9. The gas generant composition of claim 1 wherein said composition comprises: silicone; potassium perchlorate; and magnesium carbonate.
10. The gas generant composition of claim 1 wherein said composition comprises: silicone; lithium perchlorate; and a coolant selected from the group consisting of strontium carbonate, calcium carbonate, strontium oxalate, magnesium carbonate, magnesium hydroxide, and potassium carbonate.
1 1 . A gas generant composition comprising: silicone at 10-25%; a primary oxidizer selected from the group consisting of metal and nonmetal perchlorates at 30-85%; and a coolant selected from the group consisting of alkali, alkaline earth, and transitional metal carbonates, oxalates, bicarbonates, and hydroxides at 1 -30%, said percentages stated by weight of said gas generant composition.
12. The gas generant composition of claim 1 1 further comprising: at least one secondary oxidizer selected from the group consisting of nonmetal, alkali metal, alkaline earth metal, and transitional metal chlorates, nitrates, nitrites, and oxides at 30-50% by weight of said gas generant composition.
13. The gas generant composition of claim 1 2 wherein said at least one secondary oxidizer is selected from the group consisting of phase stabilized ammonium nitrate, ammonium nitrate, strontium nitrate, and potassium nitrate.
14. A method of inflating an airbag comprising the step of: combusting a gas generant composition comprising silicone, an oxidizer selected from the group consisting of metal and nonmetal perchlorates, and a coolant selected from the group consisting of metal carbonates, metal oxalates, metal bicarbonates, and metal hydroxides.
1 5. The method of claim 14 wherein said silicone is provided at 10-25%, said oxidizer at 30-85%, and said coolant at 1 -30%, said percentages stated by weight of said gas generant composition.
1 6. A gas generant composition comprising: silicone at 10-25%; potassium perchlorate at 30-85%; and a coolant selected from the group consisting of alkali metal, alkaline earth metal, and transitional metal carbonates, oxalates, and hydroxides at 1 -30%, said percentages stated by weight of said gas generant composition.
7. The gas generant composition of claim 1 6 wherein said coolant is strontium carbonate.
8. A gas generant composition comprising: silicone at 10-25%; potassium perchlorate at 30-85%; and strontium carbonate at 1 -30%, said percentages stated by weight of said gas generant composition.
9. The gas generant composition of claim 1 8 comprising: silicone at 20%; potassium perchlorate at 60%; and strontium carbonate at 20%, said percentages stated by weight of said gas generant composition.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US15424299P | 1999-09-16 | 1999-09-16 | |
| US15429399P | 1999-09-16 | 1999-09-16 | |
| US154242P | 1999-09-16 | ||
| US154293P | 1999-09-16 | ||
| PCT/US2000/025584 WO2001019757A2 (en) | 1999-09-16 | 2000-09-18 | Gas generants containing silicone fuels |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP1377534A2 true EP1377534A2 (en) | 2004-01-07 |
Family
ID=26851277
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP00963598A Withdrawn EP1377534A2 (en) | 1999-09-16 | 2000-09-18 | Gas generants containing silicone fuels |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP1377534A2 (en) |
| JP (1) | JP2003529515A (en) |
| WO (1) | WO2001019757A2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2005014507A2 (en) * | 2003-05-23 | 2005-02-17 | Autoliv Asp, Inc. | Flexible inflator with co-extruded propellant and moisture barrier and gas generating propellant compositions for use therewith |
| JP4672974B2 (en) * | 2003-10-22 | 2011-04-20 | ダイセル化学工業株式会社 | Gas generant composition |
| JP2009137820A (en) * | 2007-12-11 | 2009-06-25 | Daicel Chem Ind Ltd | Gel transfer powder for inflator |
| AU2012214899B2 (en) * | 2011-02-07 | 2016-10-27 | Nederlandse Organisatie Voor Toegepast- Natuurwetenschappelijk Onderzoek Tno | Chemical carbon dioxide gas generator |
| DE102012217718A1 (en) | 2011-09-30 | 2013-04-04 | Diehl Bgt Defence Gmbh & Co. Kg | Cold-gas pyrotechnic generator useful e.g. in fire-fighting-, driving-, or underwater rescue systems, comprises first chamber, which contains hot combustive gas generator propellant, and a second chamber containing a coolant |
| WO2019143784A1 (en) * | 2018-01-17 | 2019-07-25 | Arc Automotive Inc. | Non-ammonium nitrate based generants |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL121978C (en) * | 1964-03-23 | |||
| DE2150465C3 (en) * | 1971-10-09 | 1978-05-24 | Bayern-Chemie Gesellschaft Fuer Flugchemische Antriebe Mbh, 8261 Aschau | Solid gas generator of an impact protection system for the occupants of a motor vehicle |
| FR2190776B1 (en) * | 1972-07-05 | 1976-10-29 | Poudres & Explosifs Ste Nale | |
| FR2213254B1 (en) * | 1972-10-17 | 1977-08-05 | Poudres & Explosifs Ste Nale | |
| US4309229A (en) * | 1975-12-31 | 1982-01-05 | Allied Chemical Corporation | Method of generating water vapor free gas |
| US5656793A (en) * | 1994-05-09 | 1997-08-12 | Eiwa Chemical Ind. Co., Ltd. | Gas generator compositions |
| US5486248A (en) * | 1994-05-31 | 1996-01-23 | Morton International, Inc. | Extrudable gas generant for hybrid air bag inflation system |
| FR2728562B1 (en) * | 1994-12-22 | 1997-01-24 | Poudres & Explosifs Ste Nale | METHOD FOR THE CONTINUOUS MANUFACTURING OF PYROTECHNICAL CHARGERS WITH A SILICONE BINDER AND COMPOSITIONS LIKELY TO BE IMPLEMENTED BY THIS METHOD |
| FR2730965B1 (en) * | 1995-02-23 | 1997-04-04 | Livbag Snc | PYROTECHNIC GAS GENERATOR FOR INFLATABLE CUSHION OF A MOTOR VEHICLE |
| US5847311A (en) * | 1996-10-22 | 1998-12-08 | Trw Vehicle Safety Systems Inc. | Hybrid inflator with crystalline and amorphous block copolymer |
-
2000
- 2000-09-18 EP EP00963598A patent/EP1377534A2/en not_active Withdrawn
- 2000-09-18 JP JP2001523340A patent/JP2003529515A/en active Pending
- 2000-09-18 WO PCT/US2000/025584 patent/WO2001019757A2/en not_active Ceased
Non-Patent Citations (1)
| Title |
|---|
| See references of WO0119757A3 * |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003529515A (en) | 2003-10-07 |
| WO2001019757A2 (en) | 2001-03-22 |
| WO2001019757A3 (en) | 2003-10-23 |
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