US20190218155A1 - Non-ammonium nitrate based generants - Google Patents
Non-ammonium nitrate based generants Download PDFInfo
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- US20190218155A1 US20190218155A1 US16/250,317 US201916250317A US2019218155A1 US 20190218155 A1 US20190218155 A1 US 20190218155A1 US 201916250317 A US201916250317 A US 201916250317A US 2019218155 A1 US2019218155 A1 US 2019218155A1
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- United States
- Prior art keywords
- airbag
- formulation
- gas generant
- gas
- generant formulation
- 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.)
- Abandoned
Links
- 239000000203 mixture Substances 0.000 claims abstract description 66
- 238000009472 formulation Methods 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 6
- 239000007789 gas Substances 0.000 claims description 73
- DHEQXMRUPNDRPG-UHFFFAOYSA-N strontium nitrate Chemical compound [Sr+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O DHEQXMRUPNDRPG-UHFFFAOYSA-N 0.000 claims description 29
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims description 23
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 17
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 17
- 229910052760 oxygen Inorganic materials 0.000 claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 14
- 239000001301 oxygen Substances 0.000 claims description 14
- IDCPFAYURAQKDZ-UHFFFAOYSA-N 1-nitroguanidine Chemical compound NC(=N)N[N+]([O-])=O IDCPFAYURAQKDZ-UHFFFAOYSA-N 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 229910001487 potassium perchlorate Inorganic materials 0.000 claims description 13
- AXZAYXJCENRGIM-UHFFFAOYSA-J dipotassium;tetrabromoplatinum(2-) Chemical compound [K+].[K+].[Br-].[Br-].[Br-].[Br-].[Pt+2] AXZAYXJCENRGIM-UHFFFAOYSA-J 0.000 claims description 11
- 229960004643 cupric oxide Drugs 0.000 claims description 10
- 230000015572 biosynthetic process Effects 0.000 claims description 8
- 239000002826 coolant Substances 0.000 claims description 8
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 7
- 239000000377 silicon dioxide Substances 0.000 claims description 7
- KQAGKTURZUKUCH-UHFFFAOYSA-L strontium oxalate Chemical compound [Sr+2].[O-]C(=O)C([O-])=O KQAGKTURZUKUCH-UHFFFAOYSA-L 0.000 claims description 7
- 239000005995 Aluminium silicate Substances 0.000 claims description 6
- 235000012211 aluminium silicate Nutrition 0.000 claims description 6
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 239000002893 slag Substances 0.000 claims description 6
- 239000003607 modifier Substances 0.000 claims description 2
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 13
- 239000007787 solid Substances 0.000 description 13
- 239000000446 fuel Substances 0.000 description 11
- 239000004615 ingredient Substances 0.000 description 11
- NDEMNVPZDAFUKN-UHFFFAOYSA-N guanidine;nitric acid Chemical group NC(N)=N.O[N+]([O-])=O.O[N+]([O-])=O NDEMNVPZDAFUKN-UHFFFAOYSA-N 0.000 description 9
- 239000007800 oxidant agent Substances 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 6
- 239000000945 filler Substances 0.000 description 5
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 4
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- GDDNTTHUKVNJRA-UHFFFAOYSA-N 3-bromo-3,3-difluoroprop-1-ene Chemical compound FC(F)(Br)C=C GDDNTTHUKVNJRA-UHFFFAOYSA-N 0.000 description 3
- 229910002651 NO3 Inorganic materials 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- ULRPISSMEBPJLN-UHFFFAOYSA-N 2h-tetrazol-5-amine Chemical compound NC1=NN=NN1 ULRPISSMEBPJLN-UHFFFAOYSA-N 0.000 description 2
- 101150004822 PSAN gene Proteins 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 102100023706 Steroid receptor RNA activator 1 Human genes 0.000 description 2
- 101710187693 Steroid receptor RNA activator 1 Proteins 0.000 description 2
- 230000005496 eutectics Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- YVEFKVZCXZXGBX-UHFFFAOYSA-N N=C(N)N[N+](=O)[O-].NC(N)=N[N+](=O)[O-] Chemical compound N=C(N)N[N+](=O)[O-].NC(N)=N[N+](=O)[O-] YVEFKVZCXZXGBX-UHFFFAOYSA-N 0.000 description 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical class O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- CUCSOENEIFDWBK-UHFFFAOYSA-N [N+](=O)([O-])NC(=N)N.[N+](=O)([O-])[O-].[K+] Chemical compound [N+](=O)([O-])NC(=N)N.[N+](=O)([O-])[O-].[K+] CUCSOENEIFDWBK-UHFFFAOYSA-N 0.000 description 1
- XNSFIKDEWKLKOZ-UHFFFAOYSA-N [N+](=O)([O-])[O-].[K+].Cl(=O)(=O)(=O)O Chemical compound [N+](=O)([O-])[O-].[K+].Cl(=O)(=O)(=O)O XNSFIKDEWKLKOZ-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000002860 competitive effect Effects 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- SFDJOSRHYKHMOK-UHFFFAOYSA-N nitramide Chemical compound N[N+]([O-])=O SFDJOSRHYKHMOK-UHFFFAOYSA-N 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-M perchlorate Inorganic materials [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 description 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-N perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 description 1
- 235000010333 potassium nitrate Nutrition 0.000 description 1
- 239000004323 potassium nitrate Substances 0.000 description 1
- 239000003380 propellant Substances 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 238000005382 thermal cycling Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C06—EXPLOSIVES; MATCHES
- C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
- C06B31/00—Compositions containing an inorganic nitrogen-oxygen salt
- C06B31/02—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate
- C06B31/12—Compositions containing an inorganic nitrogen-oxygen salt the salt being an alkali metal or an alkaline earth metal nitrate with a nitrated organic compound
Definitions
- ammonium nitrate based generants With ammonium nitrate based generants becoming unacceptable for usage in automotive airbag inflator applications regardless whether they are used in pyrotechnic or hybrid type inflators, alternate or non-ammonium nitrate containing generants are highly desirable. Even in a hybrid inflator where the generant is stored in a high-pressure inert gas atmosphere making moisture intrusion nearly impossible, ammonium nitrate based generants are still considered unacceptable.
- the gas generant may be used as an airbag gas generant formulation.
- This document discloses a number of gas generant formulations and it is understood that “formulation” or “the formulation” unless otherwise stated, may refer to any gas generant formulation(s) or airbag gas generant formulation(s) of this document. That is any non-ammonium nitrate based generants of this disclosure.
- the airbag gas generant formulation (see, e.g., as claimed) can be optimized for airbag inflators, specifically hybrid airbag inflators.
- One aspect is an airbag gas generant formulation comprising the following: 40 wt % to 50 wt % strontium nitrate; 35 wt % to 45 wt % nitroguanidine; 3 wt % to 7 wt % potassium perchlorate; 3 wt % to 6 wt % w/w polyvinyl alcohol; and 2 wt % to 6 wt % w/w strontium oxalate.
- the ingredients may be adjusted to reach 100 wt % without any additional ingredients.
- a filler may be used to adjust the ingredients to 100 wt %.
- wt % refers to “weight percent” which is the weight of one chemical relative to the weight of the total airbag gas generant formulation. Where the wt % is less than 100%, an optional filler known to one of ordinary skill in the art may be added.
- the filler can be an inert filler such as clay, chalk, and the like.
- Inert filler refers to a chemical or ingredient that does not react with the other ingredients in the formulation in an environment where the formulation is usually found. Such an environment may be, for example, in an airbag inflator, in a warehouse, or in a car. Each of these locations may be subjected to the conditions expected of an airbag inflator, of a car or of a warehouse which include subfreezing to very hot conditions of a car, for example, in the sun and in a desert.
- the gas generant formulations and airbag gas generant formulations of the disclosure has many desirable properties.
- One aspect is directed to a formulation which has at least one property selected from the group consisting of: a gas yield of greater than 1.57 grams of per cubic centimeter (g/cc); a constant volume flame temperature of 2700° K to 2800° K; and an overall oxygen balance of the formulation ⁇ 2% to +2%.
- the formulation comprises two of these properties.
- the formulation comprises all of these properties.
- One aspect relates to an airbag gas generant formulation wherein the formulation comprises 48.2 wt % strontium nitrate; 36.8 wt % nitroguanidine; 5 wt % potassium perchlorate; 5 wt % strontium oxalate; and 5 wt % polyvinyl alcohol.
- the formulation further comprises 1 wt % to 5 wt % cupric oxide as a burning rate modifier.
- the airbag gas generant formulation may comprise 44.1 wt % strontium nitrate; 39.9 wt % nitroguanidine; 5 wt % potassium perchlorate; 4 wt % strontium oxalate; 4 wt % polyvinyl alcohol; and 3 wt % cupric oxide.
- the airbag gas generant formulation can further comprise 2 wt % to 6 wt % Kaolin.
- the kaolin may be for slag formation and as a coolant.
- the airbag gas generant formulation can further comprise 2 wt % to 6 wt % aluminum oxide.
- the aluminum oxide may be for slag formation and as a coolant.
- the airbag gas generant formulation can further comprise 2 wt % to 6 wt % silicon dioxide.
- the silicon dioxide may be for slag formation and as a coolant.
- the airbag gas generant formulation can further comprise 2 wt % to 6% wt % of at least one ingredient.
- the one ingredient may be one, two, or all three of the following: kaolin; aluminum oxide; and silicon dioxide.
- Vehicles may include a variety of airbags that can deploy during vehicle impacts to absorb energy from occupants of the vehicles during the impact.
- the airbag may be a component of an airbag module comprising an airbag inflator in communication with the airbag for inflating the airbag from an uninflated position to an inflated position.
- One aspect is directed to an airbag inflator comprising an airbag gas generant formulation described in this disclosure.
- Another aspect is directed to an airbag module or airbag comprising an airbag gas generant formulation described in this disclosure.
- Another aspect is directed to a method of inflating an airbag.
- the method comprises the steps of igniting an airbag gas generant of any airbag gas generant formulation described in this disclosure to generate a gas; and inflating an airbag with the gas.
- This disclosure describes non-ammonium nitrate based generants that are optimized as a replacement and improvement for ammonium nitrate based hybrid inflator generants.
- Hybrid inflators contain both stored gas and pyrotechnic materials.
- the stored gas vessel contains both high-pressure gas and pyrotechnic materials.
- the pyrotechnic materials are used for gas generation and heating of the stored gas.
- Ammonium nitrate based generants worked well due to their high gas yield and relatively high combustion temperature compared to that needed for a pyrotechnic inflator.
- Ammonium nitrate based hybrid generants were formulated near stoichiometric such that they did not generant unacceptable levels of carbon monoxide or nitrogen oxide compounds; they had oxygen balances near zero. In this type of hybrid inflator the stored gas is inert.
- Some hybrid inflator designs use a highly negative oxygen balance formulation that generate carbon monoxide (CO) and hydrogen (H 2 ) requiring oxygen to be added to the stored gas to combust the CO and H 2 to CO 2 and H 2 O, respectively.
- CO carbon monoxide
- H 2 hydrogen
- Such a formulation is described in U.S. Pat. No. 7,942,990. The formulation described here requires no oxygen to be included in the stored gas.
- Ammonium nitrate based generants also have a high gas yield to volume of solid generant.
- the ammonium nitrate based generants described in U.S. Pat. Nos. 5,850,053 and 6,136,113 have a theoretical density of 1.66 g/cc with a gas yield of 1.57 grams of gas per cubic centimeter (cc) of solid generant.
- These formulations have a constant pressure flame temperature of 2240K and a constant volume flame temperature of 2700° K.
- a replacement generant to work in the same hybrid inflator, it is preferred to have the same or equivalent gas yield per solid volume and flame temperatures.
- Example 1 Gas Mass per Volume of Solid Generant with Guanidine Nitrate, ⁇ 1% Oxygen Balance Grams Gas % PVA per cc Solid Oxidizer % Oxidizer % GN Binder Generant Sr(NO 3 ) 2 39.4 60.6 1.46 Sr(NO 3 ) 2 49.1 46.9 4 1.45 BCN 44.9 55.1 1.48 KClO 4 34.8 65.2 1.37 KClO 4 44.8 55.2 4 1.35
- Table 1 lists some fuels used or proposed to be used in airbag gas generants. In order to meet the criteria of 1.57 grams of gas per cc of solid volume low-density ingredients in general like guanidine nitrate can be rejected as a candidate. Also, fuels with a high oxygen demand like 5-aminotetrazole can be rejected due to the low gas yield of such a system with a metal-containing oxidizer.
- HMX and RDX tend to have high flame temperatures; besides HMX and RDX generants are sensitive and tend to fall under export control laws. So candidates like HMX and RDX are not considered as being viable; they also would require significant amounts of coolant (flame temperature reducing material) to be added to such a formulation.
- coolant flame temperature reducing material
- AZODN while being the ideal fuel is not commercially available so the preferred fuel is nitroguanidine.
- Example 2 lists ⁇ 1% oxygen balance two-component systems with oxidizers from Tablet combined with nitroguanidine; PSAN-GN formulations are also listed for comparison purposes. Potassium nitrate-nitroguanidine formulations have a low gas yield making them unable to meet the 1.57 g/cc requirement. Potassium perchlorate and ammonium perchlorate containing formulations tend to have too high of a combustion temperature. Strontium nitrate and BCN are the remaining oxidizers to be considered.
- Example 2 ⁇ 1% O/B Constant Volume Flame Temperature at 0.08 loading volume (cc-solid/cc-total volume) Gas Yield Const. Vol. Oxidizer Density Flame Temp Oxidizer % Fuel Fuel % (g/cc) (K) PSAN (AN-KP-GN 50.8 GN 49.2 1.543 2693 Eutectic) PSAN AN-KN-GN 52.9 GN 47.1 1.542 2623 Eutectic) Strontium Nitrate 43.4 NQ 56.6 1.693 3057 BCN 49.0 NQ 51.0 1.712 2645 Potassium 38.7 NQ 61.3 1.584 3344 Perchlorate Potassium Nitrate 42.3 NQ 57.7 1.350 2776 SNAP 42.3 NQ 57.7 1.655 3223 SRAP 44.7 NQ 55.3 1.669 3236
- Airbag generants have to be cost competitive so these formulations preferably use low-bulk-density (LBD) nitroguanidine which consists of long fibers which do not thermal cycle well.
- LBD low-bulk-density
- nitroguanidine which consists of long fibers which do not thermal cycle well.
- LBD needs to be ground.
- U.S. Pat. No. 6,547,900 describes a method using vibratory ball-mills to break up the Nitroguanidine needles. It is preferred to have minimal grinding of the NQ to break up the needle bundles plus the addition of polyvinyl alcohol (PVA) as a binder allows NQ formulations to withstand thermal cycling and heat age environment conditioning.
- PVA is a preferred binder because it is water soluble. Binders that require organic solvents to dissolve them can add high production costs to the generant.
- strontium nitrate and BCN with NQ and PVA can achieve an ideal flame temperature
- BCN and PVA do not heat age well together. Since PVA is the preferred binder, this eliminates BCN as a candidate.
- the general replacement generant formulation for an ammonium nitrate formulation is strontium nitrate, nitroguanidine, and polyvinyl alcohol as the binder plus a coolant to reduce the combustion temperature.
- strontium nitrate and NQ with PVA as a binder are shown. These combinations all meet the minimum gas weight per volume of solid generant and flame temperature.
- Sr(NO 3 ) 2 —NQ formulations can have low burning rates potassium perchlorate (KP) and copper(II) oxide (CuO) or combinations thereof can be added to increase the burning rate.
- KP potassium perchlorate
- CuO copper(II) oxide
- Examples 6 through 8 show cases where KP and CuO are included in the formulation. These cases also meet the gas yield and flame temperature requirements for a hybrid inflator application. Potassium perchlorate and CuO both act as burning rate catalysts.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Inorganic Chemistry (AREA)
- Air Bags (AREA)
Abstract
Description
- This application claims the priority and benefit of U.S. provisional application 62/618,269 filed Jan. 17, 2018, entitled “Airbag Propellant”, which is incorporated herein by reference in its entirety.
- With ammonium nitrate based generants becoming unacceptable for usage in automotive airbag inflator applications regardless whether they are used in pyrotechnic or hybrid type inflators, alternate or non-ammonium nitrate containing generants are highly desirable. Even in a hybrid inflator where the generant is stored in a high-pressure inert gas atmosphere making moisture intrusion nearly impossible, ammonium nitrate based generants are still considered unacceptable.
- One aspect of this disclosure is directed to a gas generant formulation. The gas generant may be used as an airbag gas generant formulation. This document discloses a number of gas generant formulations and it is understood that “formulation” or “the formulation” unless otherwise stated, may refer to any gas generant formulation(s) or airbag gas generant formulation(s) of this document. That is any non-ammonium nitrate based generants of this disclosure.
- The airbag gas generant formulation (see, e.g., as claimed) can be optimized for airbag inflators, specifically hybrid airbag inflators. One aspect is an airbag gas generant formulation comprising the following: 40 wt % to 50 wt % strontium nitrate; 35 wt % to 45 wt % nitroguanidine; 3 wt % to 7 wt % potassium perchlorate; 3 wt % to 6 wt % w/w polyvinyl alcohol; and 2 wt % to 6 wt % w/w strontium oxalate. In this case, the ingredients may be adjusted to reach 100 wt % without any additional ingredients. Alternatively, in any aspects of this disclosure, where the ingredients do not add up to 100 wt %, a filler may be used to adjust the ingredients to 100 wt %.
- Unless otherwise specified, wt % refers to “weight percent” which is the weight of one chemical relative to the weight of the total airbag gas generant formulation. Where the wt % is less than 100%, an optional filler known to one of ordinary skill in the art may be added. For example, the filler can be an inert filler such as clay, chalk, and the like. Inert filler refers to a chemical or ingredient that does not react with the other ingredients in the formulation in an environment where the formulation is usually found. Such an environment may be, for example, in an airbag inflator, in a warehouse, or in a car. Each of these locations may be subjected to the conditions expected of an airbag inflator, of a car or of a warehouse which include subfreezing to very hot conditions of a car, for example, in the sun and in a desert.
- The gas generant formulations and airbag gas generant formulations of the disclosure has many desirable properties. One aspect is directed to a formulation which has at least one property selected from the group consisting of: a gas yield of greater than 1.57 grams of per cubic centimeter (g/cc); a constant volume flame temperature of 2700° K to 2800° K; and an overall oxygen balance of the formulation −2% to +2%. In a preferred aspect, the formulation comprises two of these properties. In another preferred aspect, the formulation comprises all of these properties.
- One aspect relates to an airbag gas generant formulation wherein the formulation comprises 48.2 wt % strontium nitrate; 36.8 wt % nitroguanidine; 5 wt % potassium perchlorate; 5 wt % strontium oxalate; and 5 wt % polyvinyl alcohol.
- Another aspect relates to any of the formulations in this disclosure wherein the formulation further comprises 1 wt % to 5 wt % cupric oxide as a burning rate modifier. As an example, the airbag gas generant formulation may comprise 44.1 wt % strontium nitrate; 39.9 wt % nitroguanidine; 5 wt % potassium perchlorate; 4 wt % strontium oxalate; 4 wt % polyvinyl alcohol; and 3 wt % cupric oxide.
- In another aspect, the airbag gas generant formulation can further comprise 2 wt % to 6 wt % Kaolin. The kaolin may be for slag formation and as a coolant. In another aspect, the airbag gas generant formulation can further comprise 2 wt % to 6 wt % aluminum oxide. The aluminum oxide may be for slag formation and as a coolant. In another aspect, the airbag gas generant formulation can further comprise 2 wt % to 6 wt % silicon dioxide. The silicon dioxide may be for slag formation and as a coolant. As another aspect, the airbag gas generant formulation can further comprise 2 wt % to 6% wt % of at least one ingredient. The one ingredient may be one, two, or all three of the following: kaolin; aluminum oxide; and silicon dioxide.
- Vehicles may include a variety of airbags that can deploy during vehicle impacts to absorb energy from occupants of the vehicles during the impact. The airbag may be a component of an airbag module comprising an airbag inflator in communication with the airbag for inflating the airbag from an uninflated position to an inflated position.
- One aspect is directed to an airbag inflator comprising an airbag gas generant formulation described in this disclosure.
- Another aspect is directed to an airbag module or airbag comprising an airbag gas generant formulation described in this disclosure.
- Another aspect is directed to a method of inflating an airbag. The method comprises the steps of igniting an airbag gas generant of any airbag gas generant formulation described in this disclosure to generate a gas; and inflating an airbag with the gas.
- This disclosure describes non-ammonium nitrate based generants that are optimized as a replacement and improvement for ammonium nitrate based hybrid inflator generants.
- Hybrid inflators contain both stored gas and pyrotechnic materials. In some hybrid inflator designs the stored gas vessel contains both high-pressure gas and pyrotechnic materials. In hybrid inflators the pyrotechnic materials are used for gas generation and heating of the stored gas. Ammonium nitrate based generants worked well due to their high gas yield and relatively high combustion temperature compared to that needed for a pyrotechnic inflator. Ammonium nitrate based hybrid generants were formulated near stoichiometric such that they did not generant unacceptable levels of carbon monoxide or nitrogen oxide compounds; they had oxygen balances near zero. In this type of hybrid inflator the stored gas is inert. Some hybrid inflator designs use a highly negative oxygen balance formulation that generate carbon monoxide (CO) and hydrogen (H2) requiring oxygen to be added to the stored gas to combust the CO and H2 to CO2 and H2O, respectively. Such a formulation is described in U.S. Pat. No. 7,942,990. The formulation described here requires no oxygen to be included in the stored gas.
- Ammonium nitrate based generants also have a high gas yield to volume of solid generant. For example, the ammonium nitrate based generants described in U.S. Pat. Nos. 5,850,053 and 6,136,113 have a theoretical density of 1.66 g/cc with a gas yield of 1.57 grams of gas per cubic centimeter (cc) of solid generant. These formulations have a constant pressure flame temperature of 2240K and a constant volume flame temperature of 2700° K. For a replacement generant to work in the same hybrid inflator, it is preferred to have the same or equivalent gas yield per solid volume and flame temperatures.
- Due to the preceding constraints of high gas yields per volume of solid gas generant and non-ammonium nitrate containing generants, this makes metal containing oxidizers and high-density fuels attractive. These types of generants have a lower gas yield per weight but due to having a high solid density can produce the same amount of gas per solid volume as the ammonium nitrate based generants. It is also desirable for a gas generant to use commonly available or lowest cost ingredients. For pyrotechnic inflators, the fuel of choice today is guanidine nitrate (GN). Example 1 shows GN with various oxidizers. As this example shows when GN is used as the fuel, the 1.57 grams of gas per cc solid generant cannot be met.
- The following chemicals components recited in the claims are individually well-known to one of ordinary skill in the art. They include at least strontium nitrate (Sr(NO3)2); potassium perchlorate (KClO4); polyvinyl alcohol; strontium oxalate (SrC2O4); cupric oxide (CuO); Kaolin; aluminum oxide (Al2O3); and silicon dioxide (SiO2). Nitroguanidine ((NH2)2CNNO2) or NO2NHC(═NH)NH2) is commercially available and also well-known. It exists in two tautomeric forms, as a nitroimine (left) or a nitroamine (right).
- In solution and in the solid state, the nitroimine form predominates (resonance stabilized).
- All publications, patent applications, and patents mentioned anywhere in this disclosure are hereby incorporated by reference in their entirety as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. In case of conflict, the present application, including any definitions herein, will control.
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Example 1: Gas Mass per Volume of Solid Generant with Guanidine Nitrate, −1% Oxygen Balance Grams Gas % PVA per cc Solid Oxidizer % Oxidizer % GN Binder Generant Sr(NO3)2 39.4 60.6 1.46 Sr(NO3)2 49.1 46.9 4 1.45 BCN 44.9 55.1 1.48 KClO4 34.8 65.2 1.37 KClO4 44.8 55.2 4 1.35 - Table 1 lists some fuels used or proposed to be used in airbag gas generants. In order to meet the criteria of 1.57 grams of gas per cc of solid volume low-density ingredients in general like guanidine nitrate can be rejected as a candidate. Also, fuels with a high oxygen demand like 5-aminotetrazole can be rejected due to the low gas yield of such a system with a metal-containing oxidizer.
- The flame temperature of compositions tend to increase with fuel heat-of-formation so generants containing HMX and RDX tend to have high flame temperatures; besides HMX and RDX generants are sensitive and tend to fall under export control laws. So candidates like HMX and RDX are not considered as being viable; they also would require significant amounts of coolant (flame temperature reducing material) to be added to such a formulation. Of the two other ingredients listed in Table 1, AZODN while being the ideal fuel is not commercially available so the preferred fuel is nitroguanidine.
-
TABLE 1 Density Oxygen Heat of Formation Fuel (g/cc) Balance % (kcal/kg) HMX 1.91 −21.61 60.54 RDX 1.816 −21.61 75.64 Nitroguanidine 1.77 −30.75 −216.97 Azodicarbonamidine 1.70 −13.33 −366. Dinitrate (AZODN) 5-Aminotetrazole 1.65 −65.83 587.77 Guanidine Nitrate 1.436 −26.21 −746.21
Table 2 lists oxidizers that have been used or proposed to be used in airbag gas generant formulations. -
TABLE 2 Gas Den- Oxygen Percent Post Heat of Yield sity Balance Combustion Formation Density Oxidizer (g/cc) % Condensable (kcal/kg) (g/cc) Strontium Nitrate 2.986 37.8 48.96 −1104.76 1.524 Basic Copper 3.394 29.98 52.93 −866. 1.598 Nitrate (BCN) Potassium 2.52 46.19 53.81 −742. 1.164 Perchlorate (KP) Potassium Nitrate 2.109 39.56 68.35 −1169. 0.667 (KN) Sodium Nitrate + 2.069 39.51 28.86 −901. 1.472 Ammonium Perchlorate (SNAP) Strontium Nitrate + 2.334 35.82 35.5 −840. 1.505 Ammonium Perchlorate (SRAP) - Example 2 lists −1% oxygen balance two-component systems with oxidizers from Tablet combined with nitroguanidine; PSAN-GN formulations are also listed for comparison purposes. Potassium nitrate-nitroguanidine formulations have a low gas yield making them unable to meet the 1.57 g/cc requirement. Potassium perchlorate and ammonium perchlorate containing formulations tend to have too high of a combustion temperature. Strontium nitrate and BCN are the remaining oxidizers to be considered.
-
Example 2: −1% O/B Constant Volume Flame Temperature at 0.08 loading volume (cc-solid/cc-total volume) Gas Yield Const. Vol. Oxidizer Density Flame Temp Oxidizer % Fuel Fuel % (g/cc) (K) PSAN (AN-KP-GN 50.8 GN 49.2 1.543 2693 Eutectic) PSAN AN-KN-GN 52.9 GN 47.1 1.542 2623 Eutectic) Strontium Nitrate 43.4 NQ 56.6 1.693 3057 BCN 49.0 NQ 51.0 1.712 2645 Potassium 38.7 NQ 61.3 1.584 3344 Perchlorate Potassium Nitrate 42.3 NQ 57.7 1.350 2776 SNAP 42.3 NQ 57.7 1.655 3223 SRAP 44.7 NQ 55.3 1.669 3236 - Airbag generants have to be cost competitive so these formulations preferably use low-bulk-density (LBD) nitroguanidine which consists of long fibers which do not thermal cycle well. As mentioned in the literature LBD needs to be ground. U.S. Pat. No. 6,547,900 describes a method using vibratory ball-mills to break up the Nitroguanidine needles. It is preferred to have minimal grinding of the NQ to break up the needle bundles plus the addition of polyvinyl alcohol (PVA) as a binder allows NQ formulations to withstand thermal cycling and heat age environment conditioning. PVA is a preferred binder because it is water soluble. Binders that require organic solvents to dissolve them can add high production costs to the generant.
- While a two oxidizer combination of strontium nitrate and BCN with NQ and PVA can achieve an ideal flame temperature, BCN and PVA do not heat age well together. Since PVA is the preferred binder, this eliminates BCN as a candidate. The general replacement generant formulation for an ammonium nitrate formulation is strontium nitrate, nitroguanidine, and polyvinyl alcohol as the binder plus a coolant to reduce the combustion temperature. In examples 3 through 8 various combinations of strontium nitrate and NQ with PVA as a binder are shown. These combinations all meet the minimum gas weight per volume of solid generant and flame temperature.
- Because Sr(NO3)2—NQ formulations can have low burning rates potassium perchlorate (KP) and copper(II) oxide (CuO) or combinations thereof can be added to increase the burning rate. Examples 6 through 8 show cases where KP and CuO are included in the formulation. These cases also meet the gas yield and flame temperature requirements for a hybrid inflator application. Potassium perchlorate and CuO both act as burning rate catalysts.
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Const. Gas Vol. Stron- Stron- Yield Flame tium tium Density Temp Example Nitrate NQ Oxalate PVA KP CuO (g/cc) (K) 3 53.9% 36.6% 4.5% 5% 1.585 2716. 4 51.6% 39.4% 5.0% 4% 1.594 2700. 5 49.4% 42.6% 5.5% 3% 1.608 2700. 6 45.8% 39.7% 5.5% 4% 5% 1.575 2708. 7 43.7% 40.8% 5.5% 4% 6% 1.574 2720. 8 43.9% 39.6% 4.5% 4% 5% 3.0 1.587 2720. - While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (13)
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US16/250,317 US20190218155A1 (en) | 2018-01-17 | 2019-01-17 | Non-ammonium nitrate based generants |
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Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US5486248A (en) * | 1994-05-31 | 1996-01-23 | Morton International, Inc. | Extrudable gas generant for hybrid air bag inflation system |
US20090211671A1 (en) * | 1998-09-14 | 2009-08-27 | Yo Yamato | Gas generating composition |
Family Cites Families (13)
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US5850053A (en) | 1995-03-31 | 1998-12-15 | Atlantic Research Corporation | Eutectic mixtures of ammonium nitrate, guanidine nitrate and potassium perchlorate |
US6527886B1 (en) * | 1996-07-22 | 2003-03-04 | Daicel Chemical Industries, Ltd. | Gas generant for air bag |
DE69824907T2 (en) * | 1997-03-24 | 2004-11-04 | Daicel Chemical Industries, Ltd., Sakai | Gas generating tablets and gas generator |
US6136113A (en) | 1998-08-07 | 2000-10-24 | Atlantic Research Corporation | Gas generating composition |
JP2003529515A (en) * | 1999-09-16 | 2003-10-07 | オートモーティブ システムズ ラボラトリー インコーポレーテッド | Gas generating agent containing silicone fuel |
US6547900B2 (en) | 2001-01-24 | 2003-04-15 | Breed Automotive Technology, Inc. | Method of stabilizing the density of gas generant pellets containing nitroguanidine |
JP2002302010A (en) * | 2001-04-04 | 2002-10-15 | Daicel Chem Ind Ltd | Reduction method of nitrogen oxides for hybrid inflator |
US20040025991A1 (en) * | 2002-08-07 | 2004-02-12 | Canterberry Jb | Nitroguanidine based gas generant containing mica |
JP4302442B2 (en) * | 2002-09-12 | 2009-07-29 | ダイセル化学工業株式会社 | Gas generant composition |
EP1932817A1 (en) * | 2006-12-12 | 2008-06-18 | Nitrochemie Wimmis AG | Nitratoethyl nitroamine propellant for automobile safety systems |
US7942990B2 (en) | 2006-12-18 | 2011-05-17 | Daicel Chemical Industries, Ltd. | Hybrid inflator |
CN101823927B (en) * | 2010-04-16 | 2012-03-28 | 陕西庆华汽车安全系统有限公司 | Aerogenic composition of pretensioner of automobile safety belt and preparation method thereof |
JP6443882B2 (en) * | 2015-03-13 | 2018-12-26 | 株式会社ダイセル | Aerosol fire extinguisher composition. |
-
2019
- 2019-01-17 CN CN201980006212.1A patent/CN111433172A/en active Pending
- 2019-01-17 US US16/250,317 patent/US20190218155A1/en not_active Abandoned
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5486248A (en) * | 1994-05-31 | 1996-01-23 | Morton International, Inc. | Extrudable gas generant for hybrid air bag inflation system |
US20090211671A1 (en) * | 1998-09-14 | 2009-08-27 | Yo Yamato | Gas generating composition |
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