Classifications

• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06B—EXPLOSIVES OR THERMIC COMPOSITIONS; MANUFACTURE THEREOF; USE OF SINGLE SUBSTANCES AS EXPLOSIVES
  • C06B25/00—Compositions containing a nitrated organic compound
  • C06B25/34—Compositions containing a nitrated organic compound the compound being a nitrated acyclic, alicyclic or heterocyclic amine
• • 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 invention relates to solid gas generator fuel compositions (gas-generating mixtures), mainly for gas generator propellants for airbags and belt tensioners, the gas generator fuel compositions having very good long-term thermal stability.
• An airbag essentially consists of a gas generator housing, which is usually connected to the gas generator drive unit. in tablet form, is filled, and an initial igniter (Squib) for igniting the gas generator propellant, and a gas bag.
• Suitable detonators are described, for example, in US Pat. No. 4,931,111.
• the initially small-folded gas bag is filled after the initial ignition with the gases generated when the gas generator propellant burns up and reaches its full volume in a period of about 10-50 ms.
• the escape of hot particles or melts from the gas generator into the gas bag must be largely prevented, since it could damage the gas bag or injure vehicle occupants. This is achieved by binding and filtering the slag that is produced when the gas generator propellant is burned.
• gas generator fuel compositions based on guanidine compounds on suitable carriers which essentially have improved combustion behavior and improved slag formation.
• the gas generator fuel composition described in DE-4435790 A comprises (A) at least one carbonate, hydrogen carbonate or nitrate of guanidine, aminoguanidine, diaminoguanidine or triaminoguanidine in an amount of about 20-55% by weight, based on the total amount of the components (A) and (B), (B) at least one alkali or alkaline earth nitrate or ammonium nitrate as an oxidizing agent in an amount of about 80-45% by weight, based on the total amount of components (A) and (B) and to moderate the burnup and to improve the formation of slag in an amount of 5-45% by weight, based on the total amount of components (A) and (B), (Cl), at least one carrier substance selected from silicon dioxide, alkali metal, alkaline earth metal or Aluminum si
• DE-4435790 A refers to the Holland test, in which the gas generator fuel composition was heated to 105 ° C. for 72 hours.
• the Holland test is a method developed in 1927 to determine the chemical see resistance of blowing agents. The weight loss that occurs after heating for only 72 hours at 105 ° C (polybasic blowing agent) or 110 ° C (single-blowing agent) is determined. The loss that occurs here, minus the weight loss that occurred in the first eight hours, may not exceed 2% (see J. Köhler and R. Meyer, Explosivstoffe, 9th revised and expanded edition 1998, Verlag iley-VCH, page 170).
• nidiniumbicarbonat at least one fuel selected from the group comprising guanidine nitrate, dicyandiamide, Ammoniumdicyanamid, sodium dicyanamide, Kupferdicyanamid, Zinndicyanamid, Calciumdicyanamid, Guanidiniumdicyanamid, Ammoniumgua-, Ammoniumguanidiniumnitrat, noguanidiniumnitrat Triami-, nitroguanidine, dicyandiamide, azo dicarbonamide and tetrazole, 5-aminotetrazole , 5-nitro-1, 2, 4-triazol-3-one, their salts and their mixtures,
• At least one slag former selected from alkali and alkaline earth metal carbonates and oxides, silicates, aluminates and aluminum silicates, iron (III) oxide and silicon nitride, which supplies nitrogen and silicon dioxide for further reaction when burned up and optionally
• Part of the highly disperse slag trap can serve as a carrier for catalyst metals. This publication therefore does not deal with the long-term stability of the gas generator fuel compositions under hot storage.
• the present invention is therefore based on the object of providing gas generator fuel compositions which meet the increasingly stringent requirements for stability in hot storage for at least 400 hours at 110 ° C. while maintaining the functionality, which are increasingly required by the automotive industry.
• This object of the invention is achieved by a gas generator fuel composition comprising:
• the present invention thus provides a gas generator fuel composition which can withstand hot storage at 110 ° C. for at least 400 hours and thus meets the increasing demands of the automotive industry for gas generator fuel compositions for gas generator propellants in airbags.
• Gas generator fuel compositions based on nitroguanidine as fuel and the specified oxidizing agents or oxidizing agent mixtures in conjunction with one or more stabilizers of the type mentioned can surprisingly be used to formulate gas generator fuel compositions which are stored at 110 ° C. over a storage period of 400 hours , preferably 1000 hours and especially 3000 hours, have a weight loss of less than 1%, preferably less than 0.5% and in particular less than 0.2%, while maintaining the functionality of the gas generator fuel compositions.
• the stability results obtained apply in both open and closed systems used in practice in the same way.
• the fuel is nitroguanidine (NIGU; NQ). Nitroguanidine is practically non-toxic, non-hygroscopic, not very soluble in water, thermally stable, burns at low temperatures and is not sensitive to impact and friction. The gas yield during combustion is high, with a large proportion of nitrogen gas being generated.
• a particularly preferred nitroguanidine according to the present invention is a nitroguanidine which contains 0.1 to 0.5% nitroguanidinium hydrogen sulfate and nitroguanidinium nitrate.
• Such an acid-stabilized nitroguanidine is referred to below as stabilized nitroguanidine.
• the pH of an aqueous extract (5 g nitroguanidine per 200 ml water; 20 ° C) of this stabilized nitroguanidine is 3.5 to 4.4.
• Such a stabilized nitroguanidine is e.g. available as NIGU LBD SS from NIGU CHEMIE GmbH, Waldkraiburg, Germany.
• Conventional NIGU has a pH of 4.5-7.0 (5g nitroguanidine per 200 ml water; 20 ° C).
• alkali metal and alkaline earth metal nitrates such as lithium nitrate, sodium nitrate, potassium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate or barium nitrate
• alkali metal or alkaline earth metal chlorates and perchlorates such as lithium, sodium, potassium, magnesium, Calcium, strontium or barium chlorate and lithium, sodium, potassium, magnesium, calcium, strontium or barium perchlorate
• ammonium nitrate, ammonium perchlorate oxidizing copper compounds (such as Cu (N0 3 ) 2 - 3Cu (OH ) 2 or Cu 2 (OH) 3 N0 3 , CuC0 3 and CuO), and their mixtures are used.
• Potassium nitrate, potassium perchlorate, strontium nitrate, ammonium nitrate, ammonium perchlorate and Cu (N0 3) 2 are preferred - 3Cu (OH) 2 (copper (II) trihydroxynitrat).
• Inorganic and organic acids can be used as stabilizers, component (C).
• a particularly preferred inorganic acid is boric acid.
• Particularly preferred organic acids are citric acid, tartaric acid, cyanuric acid, terephthalic acid and fumaric acid.
• Another suitable stabilizer is hydrophobic SiO 2 (available, for example, as Aerosil R812S from Degussa AG, Germany; water repellent: hexamethyldisilazane) if stabilized NIGU is used as fuel.
• Hydrophobic Si0 2 is a material that is not wetted by water, ie it floats on the surface of the water (see infra, Pigments series, No. 11, page 55ff.). Hydrophobic SiO 2 is preferably present in combination with a further stabilizer.
• gaseous products resulting from the combustion of the gas generator fuel compositions according to the invention essentially consist of carbon dioxide, nitrogen and water vapor. Any toxic gaseous combustion products, such as CO, NO x and NH 3 , are below the required limit values.
• Nitroguanidine, component (A), is in the gas generator fuel compositions according to the invention in an amount of from about 33 to about 60% by weight, preferably from about 40 to about 60% by weight and in particular from about 45 to about 55% by weight.
• the oxidizing agent, component (B) is present in an amount from about 35 to about 55% by weight, preferably from about 38 to about 52% by weight and in particular from about 40 to about 48% by weight and the stabilizer, component (C), is in an amount of up to about 5% by weight, preferably up to about 3% by weight, particularly preferably up to about 1.6% by weight and in particular of about 0.5 to about 1.6% by weight.
• the gas generator fuel compositions according to the invention contain further components to adjust the combustion behavior and the gas yield and to improve the formation of slag.
• the gas generator fuel compositions according to the invention optionally contain, as component (D), at least one burn-off stabilizer or burn-off moderator, which can also act as a slag former or slag catcher.
• component (D) at least one burn-off stabilizer or burn-off moderator, which can also act as a slag former or slag catcher.
• these are Al 2 0 3 , in particular highly disperse A1 2 0 3 with a BET surface area (based on DIN 66131) of 100 ⁇ 15 m 2 / g (for example available as aluminum oxide C from Degussa AG, Germany), Fe 2 0 3 , Si0 2 , iron acetylacetonate, mixtures thereof and mixtures of highly disperse A1 2 0 3 and Si0 2 , for example a mixture of about 16% of highly disperse A1 2 0 3 and about 84% of highly disperse Si0 2 (for example available as Aerosil COK 84 from Degus
• Highly disperse aluminum oxide with a primary particle size of about 13 nm acts as a slag catcher, ie as an internal filter in the gas generator fuel composition itself.
• These pyrogenic oxides are produced by high-temperature hydrolysis (flame hydrolysis) of the gaseous metal chloride (A1C1 3 ) under the influence of the oxyhydrogen reaction water and at the characteristic temperature for such a reaction (4 A1C1 3 + 6 H 2 + 3 0 2 ⁇ 2 A1 2 0 3 + 12 HC1) (cf. series of pigments, "highly disperse metal oxides according to the Aerosil ® process", No. 56, 4th edition 1989, Degussa AG).
• the burn-off stabilizers or moderators, component (D) cause, among other things, a linear burn-up, ie an exponential increase in pressure and temperature during the burn-off is prevented.
• Fe 2 0 3 can also serve as an oxygen supplier under certain combustion conditions.
• these compounds can also be used as slag formers to prevent the formation of dusty combustion products.
• Component (D) is present in an amount of up to about 7% by weight, preferably in an amount of up to about 5% by weight and in particular in an amount of about 0.4 to about 5% by weight Gas generator fuel composition.
• Highly disperse A1 2 0 3 is present in the gas generator fuels of the present invention preferably in an amount of up to 5% by weight, preferably in an amount between 0.5-3% by weight and in particular 2-3% by weight , This low content of A1 2 0 3 ensures a high gas yield.
• the gas generator fuel compositions of the present invention may contain at least one binder as component (E).
• suitable binders are cellulose compounds, polymers of one or more polymerizable olefinically unsaturated monomers, a metal salt of stearic acid and graphite which is insoluble in water at room temperature. Graphite is particularly preferred.
• cellulose compounds are cellulose ethers, such as carboxymethyl cellulose, methyl cellulose ether, in particular Methylhydroxyethyl cellulose, a usable methyl hydroxyethyl cellulose is CULMINAL ® MHEC 30000 PR from Aqualon, suitable polymers with a binding effect are polyvinyl pyrrolidone, polyvinyl acetate, polyvinyl alcohol and polycarbonates.
• the binder (E) serves as a desensitizing agent and as a processing aid in the production of granules or tablets from the gas generator fuel composition. It also serves to reduce the hydrophilicity of the gas generator fuel compositions.
• Component (E) is present in an amount of up to about 5% by weight, preferably up to about 3% by weight, particularly preferably up to 1% by weight and in particular from about 0.2 to about 0, 5% by weight.
• Preferred gas generator fuel compositions according to the present invention include nitroguanidine, in particular according to the invention stabilized nitroguanidine as a fuel (component (A)), Cu (N0 3) 2 - 3Cu (OH) 2, Sr (N0 3) 2, KN0 3 or a mixture of KN0 3 and NH 4 C10 4 as an oxidizing agent (component (B)), at least one stabilizer selected from the group consisting of hydrophobic Si0 2 , and boric acid, citric acid, tartaric acid, cyanuric acid, terephthalic acid and fumaric acid, optionally in a mixture with hydrophobic Si0 2 (component (C)), highly disperse A1 2 0 3 , optionally in a mixture with iron (III) oxide as component (D) and graphite as component (E).
• the object is achieved by a gas generator fuel composition
• a gas generator fuel composition comprising: (A) stabilized nitroguanidine as fuel, (B) Sr (N0 3 ) 2 or a mixture of KN0 3 or NaN0 3 and NH 4 C10 4 as an oxidizing agent, and if appropriate
• a gas generator fuel composition which contains stabilized NIGU as fuel and Sr (N0 3 ) 2 or a mixture of NaN0 3 or KN0 3 with NH 4 C10 4 as oxidizing agent, even in the presence of burn-off stabilizers / moderators and slag formers / scavengers has good or excellent long-term stability when stored at 110 ° C. It is not necessary to add a stabilizer (component (C)) to stabilize the gas generator fuel composition.
• gas generator fuel compositions and gas generator propellants were produced according to the following procedure:
• the output components (A), (B), (C), if necessary. (D) and optionally (E) were mixed and ground or pre-compacted using a ball mill.
• Granulating the gas generator The fuel was mixed in a vertical mixer by adding approx. 20% water while stirring and at a temperature raised to approx. 40 ° C. After briefly flashing off or after predrying, the mixture obtained was rubbed at room temperature through a grinder with an 1 mm sieve. The granules obtained in this way were dried in a drying oven at about 80 ° C. for about 2 hours.
• the finished granulate of the gas generator fuel composition (grain size 0-1 mm) was then compressed into tablets (pellets) using a rotary press. These gas generator propellant pellets were post-dried at 80 ° C in a drying oven.
• the starting components (A), (B), (C), optionally (D) and optionally (E) are mixed dry and then compacted under pressure, e.g. using a gear compactor.
• the compact is then broken up into granules and tableted with a rotary press.
• the tablets or pellets from the gas generator fuel composition used in the gas generators can be produced by known processes, for example by extrusion, in rotary presses or tableting machines.
• the size of the pellets or tablets depends on the desired burning time in the respective application.
• the gas generator fuel composition according to the invention consists of non-toxic, easily manufactured and inexpensive components, the processing of which is unproblematic.
• the mixtures are easy to ignite. They burn quickly and deliver large gas yields with very low CO, NO x and NH 3 contents, which are below the permissible maximum limit.
• the gas generator fuels of the present invention have very good stability when stored at 110 ° C. for more than 400 hours.
• the mixtures according to the invention are therefore particularly suitable for use as gas generants in the various airbag systems, but also as extinguishing agents or propellants.
• T4x2 tablets 4 mm in diameter and 2 mm in height
• T3xl 5 tablets 3 mm in diameter and 1.5 mm in height
• T6x2 tablets 6 mm in diameter and 2 mm in height
• GuN0 3 is the abbreviation for guanidinium nitrate and serves as a low-energy auxiliary fuel.
• NIGU stabilized is nitroguanidine, which is stabilized with a total of 0.2% nitroguanidinium hydrogen sulfate and nitroguanidinium nitrate.
• Comparative Examples 1 to 5 demonstrate the usual stability of gas generator fuel compositions based on conventional nitroguanidine as a fuel.
• Comparative examples 1 to 3 show the increasing instability of the gas generator fuel composition with increasing content of highly disperse A1 2 0 3 .
• the gas generator fuel composition contains no A1 2 0 3 and has satisfactory long-term stability with a storage period of 400 hours or 1000 hours.
• such a gas generator fuel composition is unsuitable for practical use because the combustion behavior is insufficient.
• With increasing content of Al 2 0 3 the combustion behavior improves, but the stability of the gas generator fuel composition decreases rapidly.
• Comparative Example 2 there is already a weight loss of 1.47% after a storage period of 400 hours and at a content of 5.0% by weight Al 2 0 3 , the weight loss is 3.76% after a storage time of 400 hours. These values are unacceptable for practical use.
• Comparative Example 7 shows the instability of a gas generator fuel composition which contains stabilized nitroguanadine in the presence of Cu (N0 3 ) 2 - 3Cu (OH) 2 .
• Comparative Examples 8 and 9 an oxidizer mixture of Sr (N0 3 ) 2 and Cu (N0 3 ) 2 * 3Cu (OH) 2 was used.
• the A1 2 0 3 additionally present in the formulation according to Comparative Example 9 in turn causes a decrease in stability.
• comparative examples 10 and 11 the stability of stabilized nitroguanidine in the presence of CuC0 3 and CuO was investigated.
• Example 1 of the present invention (Table II), a very good stabilization is obtained in a gas generator fuel composition which contains A1 2 0 3 as component (D) by the combination of stabilized NIGU as fuel and hydrophobic Si0 2 as stabilizer (cf. Example 1 with comparative examples 4 and 6).
• KN0 3 was used as the oxidizing agent (component (B)) in combination with A1 2 0 3 in highly disperse form and iron (III) oxide as component (D).
• Example 11 very good stability is also achieved in combination with Aerosil COK 84 and iron (III) acetylacetonate as component (D).
• the formulation according to Example 12 contains KC10 4 as an oxidizing agent (component (B)) and Aerosil COK 84 as component (D).
• component (B) KC10 4 as an oxidizing agent
• Aerosil COK 84 as component (D).
• Examples 13 to 15 show that a stable gas generator fuel composition can be obtained even in the presence of A1 2 0 3 (see Example 14) without the addition of a stabilizer if a mixture of KN0 3 and NH 4 C10 4 in is used as the oxidizing agent Combination with stabilized NIGU is used as fuel.
• a comparison with comparative example 5 shows that such good stability cannot be obtained with conventional nitroguanidine as fuel and KN0 3 as oxidizing agent in the presence of A1 2 0 3 .
• Example 15 demonstrates the good stability of gas generator fuel compositions which, in addition to nitroguanidine as fuel, also contain guanidinium nitrate (GuN0 3 ) as a low-energy auxiliary fuel.
• Sr (N0 3 ) 2 was used as the oxidizing agent. This showed an excellent stability of stabilized nitroguanidine in the presence of Sr (N0 3 ) 2 and A1 2 0 3 . The addition of boric acid as a stabilizer further improves this.
• Examples 21 and 22 demonstrate the stabilizing effect of boric acid in compositions which contain Sr (N0 3 ) 2 and Cu (N0 3 ) 2 '3Cu (OH) 2 as oxidizing agents (cf. Comparative Examples 8 and 9).
• Examples 23 and 24 show the stabilizing effect of boric acid in compositions which contain CuC0 3 and CuO as oxidizing agents (cf. Comparative Examples 10 and 11).

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Air Bags (AREA)
• Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 2000
  • 2000-12-22 DE DE10064285A patent/DE10064285C1/de not_active Expired - Fee Related
• 2001
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  • 2001-12-17 US US10/451,436 patent/US20040108031A1/en not_active Abandoned
  • 2001-12-17 WO PCT/EP2001/014901 patent/WO2002051773A1/de active IP Right Grant
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