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
  • C06B45/00—Compositions or products which are defined by structure or arrangement of component of product
• • C—CHEMISTRY; METALLURGY
  • C06—EXPLOSIVES; MATCHES
  • C06C—DETONATING OR PRIMING DEVICES; FUSES; CHEMICAL LIGHTERS; PYROPHORIC COMPOSITIONS
  • C06C9/00—Chemical contact igniters; Chemical lighters

Definitions

• the present disclosure relates to passive restraint systems, and more particularly to gas generant pyrotechnic materials and methods of making such materials for use in passive restraint systems.
• the solid body defines one or more void regions.
• a second pyrotechnic composition is introduced into at least one of these void regions. Additionally, the first pyrotechnic composition is distinct from the second composition.
• Figure 4 is a cross-sectional view of an exemplary pretensioning system microgas generator (MGG) for use with a pretensioner for a safety restraint or seatbelt system;
• MMG microgas generator
• Figure 5 is a plan view of a multi-composition pyrotechnic material in accordance with the principles of certain aspects of the present disclosure;
• Figure 6 shows a cross-sectional view along line 6 to 6' of Figure 5;
• Figure 7 shows an exemplary pressure versus time curve for combustion of a multi-composition pyrotechnic material;
• Figure 10 is an exemplary multi-composition pyrotechnic material where the second region can promote disintegration and accelerated burning of the pyrotechnic material in the primary regions in accordance with some aspects of the disclosure. DESCRIPTION OF VARIOUS ASPECTS
• Inflatable restraint devices preferably generate gas in situ from a reaction of a pyrotechnic gas generant contained therein.
• pyrotechnic materials are provided that comprise multiple compositions in a single grain structure, which enable tailoring of the pyrotechnic material behavior to have superior performance characteristics in an inflatable restraint device.
• the disclosure provides a pyrotechnic material for use in a passive restraint system.
• pyrotechnic materials include igniter and/or initiator materials, micro gas generants, and conventional gas generants.
• Figure 3 shows a simplified exemplary driver side airbag module 60 with a covered compartment 62 to store an airbag 64.
• a squib 66 is centrally disposed within an igniter material 68 that burns rapidly and exothermically, in turn, igniting a gas generant material 70.
• Filters 72 are provided to reduce particulate in effluent gases entering the airbag 64 as it inflates.
• Other pyrotechnic materials can also be employed in safety systems for vehicle passengers.
• the lower part of the base 90 typically includes one or more recessed regions 98 to engage a portion of a wiring harness of the automobile, which carries trigger wires from the sensor circuit to pin 82.
• the pretensioning generator system 80 is placed into a seatbelt pretensioner, such as 26 generally shown in Figure 1.
• the pyrotechnic material for use in a passive restraint system comprises a first region having a first pyrotechnic composition and a second region having a second pyrotechnic composition that is distinct from the first pyrotechnic composition.
• the first region defines one or more void regions.
• the first region is a solid body or grain formed of the first pyrotechnic composition.
• the second pyrotechnic composition is introduced to and disposed within at least one of the one or more void regions, thereby forming the second region of an integrated unitary multi-component pyrotechnic material.
• a solid of the first region has an area of internal bulk and at least one of the void regions extends into and optionally is substantially disposed within the internal bulk of the first region solid.
• these second regions are also substantially disposed within the internal bulk of the solid.
• a surface of the first region contacts and preferably is substantially adhered to a surface of the second region.
• the surface of the first region is integrated with surface of the second region to provide a physical bond at the interface between the materials which permits storage and use of the pyrotechnic material without separation of the first region from the second region.
• the pyrotechnic material comprises a first and a second region, however, as appreciated by those of skill in the art, a plurality of regions having different compositions are contemplated.
• the first region defines one or more void regions that are capable of being filled with various pyrotechnic material compositions.
• each of these void regions can be filled with a plurality of distinct compositions (for example, two or more distinct pyrotechnic compositions) that form a multi-composition pyrotechnic material.
• the first region of the multi-composition pyrotechnic (“MCP”) material can be formed by pressing or extruding a perforated grain in a conventional manner, forming a concentric or eccentric grain having an adjustable inner core or a primary shape surrounded by an outer shape.
• Typical pyrotechnic materials are formed into disks, tablets, wafers, grains and the like.
• the first region can be further processed and oven dried prior to loading with a slurry pyrotechnic composition.
• the first and second regions can be formed concurrently.
• the first and second regions of the pyrotechnic material can be formed in either a batch or continuous process.
• the first region defines one or more void regions that can be filled with a second pyrotechnic composition that will solidify to form a second region structurally integrated with the first region.
• void regions include cavities, perforations, apertures, grooves, holes, pockets, channels, and the like, which can be in a variety of shapes within the first region including cylinders, rectangles, cones, pyramids, and the like, as will be described in more detail below.
• the void regions can also have irregular shapes.
• the solid body of the first region can be formed in a variety of shapes including centric or eccentric, round, square, star, cross, or having multiple pockets.
• the one or more void regions are defined by the shape of the first region.
• the second region of the pyrotechnic material comprising the second pyrotechnic composition thus forms a portion of the body of the pyrotechnic material and is structurally integrated within the pyrotechnic material body, in contrast to a mere coating on the surface of the pyrotechnic material.
• the incorporation of several distinct pyrotechnic compositions into a single multi-composition grain permits freedom to tailor or tune the pyrotechnic behavior without the need for various separate materials.
• the multi-component pyrotechnic material eliminates the need for dry mixing of two or three loose pyrotechnic materials or different shapes of pyrotechnic materials ⁇ e.g., discs or multiple-perforation grains) to achieve unique output characteristics (tailored or tunable rates) for state of the art automotive initiators and micro gas generators.
• Methods of forming such multi-composition pyrotechnic materials provide a substantially homogenous and uniform mixture of the materials. Sometimes variability occurs when loose granular shapes are mixed or various material combinations are provided. As described previously, loose materials may classify or separate potentially leading to variable burn characteristics.
• the methods of disclosure reduce such variability and provide the benefits of certain types of grains, for example, extruded or pressed grains, which enable a sustained output with a slower or more progressive burn rate.
• This design also allows for cost reductions by process simplification, due to the loading of a single multi-composition grain versus various combinations of loose pyrotechnic materials thereby reducing labor and overhead, while further having safety benefits, including reduced storage and handling of loose dry pyrotechnics.
• This process also reduces inspection requirements, individual weight verification for each combination and ratio integrity, thus leading to improved output/process capability.
• the multi-composition pyrotechnic grain can be continuously processed, eliminating complicated drying and slower line speed of current redundant steps of manufacturing processes.
• a method for making a multi-composition pyrotechnic material.
• the multi-component pyrotechnic material is formed by making the first region of the pyrotechnic material with a first pyrotechnic composition and making the second region of the pyrotechnic material with a second pyrotechnic composition.
• the first pyrotechnic composition is distinct from the second pyrotechnic composition, and the second region occupies one or more void regions defined by the first region.
• the making of the first region and the making of the second region can occur concurrently, for example, where the first region and the second region are co-extruded with one another and then subsequently dried.
• methods of making the first region and second regions are sequential, where the first region is formed first, for example, into a solid form, which occurs prior to making the second region. Then, a second region can be made by introducing the second pyrotechnic composition to void regions defined by the first region.
• a method of forming a multi- component pyrotechnic material includes filling one or more void regions defined by a first solid region with a slurry.
• the first solid region comprises a first pyrotechnic composition and the slurry comprises a second pyrotechnic composition that is distinct from the first pyrotechnic composition.
• the slurry disposed within one or more void regions is dried to form a second solid region, thereby forming the multi-composition pyrotechnic material.
• Slurry refers to a flowable or pumpable mixture of fine (relatively small particle size) substantially insoluble particle solids suspended in a vehicle or carrier. Mixtures of solid materials suspended in a carrier are also contemplated.
• the slurry comprises particles having an average maximum particle size of less than about 500 ⁇ m, optionally less than or equal to about 200 ⁇ m, and in some aspects, less than or equal to about 100 ⁇ m.
• the slurry preferably contains flowable and/or pumpable suspended pyrotechnic solids and other materials in a carrier.
• Suitable carriers include conventional organic solvents as well as aqueous solvents.
• the carrier may include an azeotrope which refers to a mixture of two or more liquids, such as water and certain alcohols that desirably evaporate in constant stoichiometric proportion at specific temperatures and pressures.
• the carrier should be selected for compatibility with the components selected for inclusion in the second pyrotechnic composition to avoid adverse reactions and further to maximize solubility of the several pyrotechnic components of the second composition forming the slurry.
• suitable carriers include water, isopropyl alcohol, n-propyl alcohol, or combinations thereof.
• the viscosity of the slurry of the second pyrotechnic composition is such that it can be injected, pumped, extruded, doctor bladed, or smoothed when introduced into the void regions defined by the first region.
• the viscosity will be relatively high, having a thick or paste-like consistency to retain the slurry in the void regions.
• the viscosity is not required to be high, for instance, the void regions may optionally be filled with a thinner more liquid-like slurry and then dried within the void regions, in circumstances where the void regions can retain the slurry without undesired leaking or drainage, either by intentional blockage or sealing of the void regions or by the nature or shape of the void regions within the first region (for example, where the void regions do not extend entirely through the bulk of the solid first region).
• Examples of introducing the slurry to void regions include pumping the slurry, injecting the slurry by application of pressure, extruding the slurry into the desired void regions, filling the void regions with slurry via doctor blade and the like.
• the slurry typically has a water content of greater than or equal to about 15% by weight; preferably greater than or equal to about 20% by weight; in certain aspects greater than or equal to about 30% by weight; and in some aspects greater than or equal to about 40% by weight.
• the water content of the slurry is about 15% to about 85% by weight. As the water content increases, the viscosity of the slurry decreases, thus pumping and handling become easier, while the retention of the slurry in the void spaces potentially becomes more difficult.
• a slurry introduced to the void regions has a suitable viscosity ranging from about 50,000 to about 250,000 centipoise. Such viscosities are believed to be desirable to provide suitable rheological properties that allow the slurry to flow under applied pressure, but also permit the slurry to remain stable and in position once applied to the one or more void regions prior to drying. [0058]
• the slurry (second composition) occupying the one or more void regions is then dried, where the slurry forms a second region within the first region, as described above.
• the first region (solid body) having the first pyrotechnic composition has a preliminary loading density of less than about 70% prior to introduction of the second pyrotechnic composition into the one or more void regions.
• a loading density is an actual volume of pyrotechnic material (here the first pyrotechnic composition forming the first region) divided by the total volume available for the shape.
• a preliminary loading density should less than 100%, preferably significantly less than 100%, indicating that there are sufficient void regions within the body shape for the second regions to be formed therein.
• the preliminary loading density of the first region of the pyrotechnic material is less than or equal to about 65%, optionally less than or equal to about 50%, and optionally less than or equal to about 40%.
• the second region of the pyrotechnic material optionally occupies greater than or equal to about 5% of a total volume of the pyrotechnic material shape, preferably greater than about 10%. In some aspects, the second region of the pyrotechnic material occupies greater than or equal to about 15% of a total volume, optionally greater than about 25% of the total volume of the pyrotechnic material.
• the ballistic properties of a pyrotechnic material, such as gas generants 50, 70, or 94 shown in Figures 2, 3, and 4 are typically controlled by the pyrotechnic material composition, shape and surface area, as well as the burn rate of the material.
• the pyrotechnic material can take a variety of shapes and configurations, as recognized by those of skill in the art.
• FIG. 8 shows another alternate configuration comprising a pyrotechnic material 150.
• the first region 152 has a first external surface 154 and a second external surface 156.
• a plurality of void regions 158 are defined by the first region 152.
• a primary void region 160 creates a central aperture that extends from the first external surface 154 to the second external surface 156.
• a second pyrotechnic composition is disposed therein and forms a second region 164.
• Figure 9 depicts a single pressed monolithic gas generant grain shape 210 similar to that disclosed in U.S. Patent Application Serial No. 11/472,260 entitled “Monolithic Gas Generant Grains” filed on June 21 , 2006 to Mendenhall, et al., which is herein incorporated by reference in its entirety.
• each aperture 214 has a diameter "d" of about 3 mm.
• the first region grain 210 as shown has 30 apertures 214, although different configurations, dimensions, and quantities of the apertures 214 are contemplated.
• the number, size, and position of the apertures 214 may be varied, as they relate to the desired initial surface area and specific burn rate of the gas generant material.
• the dimensions (a, b, and c) of the disk can also be varied, as appreciated by skilled artisans. For example, where multiple disks are employed as gas generant, the height "c" can be reduced.
• the gas generant monolithic grain shown in Figure 9 has a ratio of the length of the each aperture to the diameter (L/D) of preferably from about 3.5 to about 9.
• the L/D ratio of each aperture is about 7.3.
• the ratio of L/D of the plurality of apertures relates to the surface area progression and overall burning behavior of the gas generant.
• the number of apertures and the ratio of L/D of each aperture relate to the shape or profile of the combustion pressure curve of the gas generant material.
• a monolithic shape of the first region gas generant grain 210 similar to that shown in Figure 9, provides a controlled combustion pressure that provides longer, controlled, and sustained combustion pressure at desired levels which is important for improving inflator effluent properties and for occupant safety during deployment of the airbag cushion.
• the first region has a first pyrotechnic composition that comprises a pyrotechnic component selected from the group consisting of: fuel, oxidizing agents, auto-ignition materials, binders, slag forming agents, coolants, flow aids, viscosity modifiers, dispersing aids, phlegmatizing agents, excipients, burning rate modifying agents, and mixtures and combinations thereof.
• a pyrotechnic component selected from the group consisting of: fuel, oxidizing agents, auto-ignition materials, binders, slag forming agents, coolants, flow aids, viscosity modifiers, dispersing aids, phlegmatizing agents, excipients, burning rate modifying agents, and mixtures and combinations thereof.
• the substituted basic metal nitrate can include a reaction product formed by reacting an acidic organic compound with a basic metal nitrate. The reaction is believed to occur between acidic hydrogen and a basic metal nitrate, such that the hydroxyl groups of the nitrate compound are partially replaced, however, the structural integrity of the basic metal nitrate is not compromised by the substitution reaction.
• This gas generant optionally comprises a material including a substituted basic metal nitrate that is a reaction product of a nitrogen-containing heterocyclic acidic organic compound and a basic metal nitrate.
• the desirability of use of various co-fuels, such as guanidine nitrate, as a portion of the fuel in a pyrotechnic composition is generally based on a combination of factors, such as burn rate, cost, stability (e.g., thermal stability), availability and compatibility (e.g., compatibility with other standard or useful pyrotechnic composition components).
• the gas generant compositions include about 5 to about 95 weight % of the substituted basic metal nitrate compound.
• an enhanced burn rate gas generant composition may include about 5 to about 95 weight % 5-amino tetrazole substituted basic copper nitrate.
• the pyrotechnic gas generant compositions include about 5 to about 60 weight % co-fuel.
• One specific gas generant composition includes about 5 to about 60 weight % of guanidine nitrate co-fuel and about 5 to about 95 weight % substituted basic metal nitrate.
• pyrotechnic fuels such as any of those discussed above, can be present in either the first or second pyrotechnic compositions in an amount of greater than about 5% to about 95% by weight of the respective pyrotechnic composition.
• Certain pyrotechnic fuels have a more rapid burn time, higher rate of reaction, and/or lower ignition temperature and are regarded as initiator or booster fuels. In certain aspects, such initiator or booster fuels are particularly suitable for inclusion in the second pyrotechnic composition of the multi- composition pyrotechnic material.
• Suitable oxidizers include potassium perchlorate, ammonium perchlorate or perchlorate-free oxidizing agents, such as a basic metal nitrate like basic copper nitrate.
• Basic copper nitrate has a high oxygen to metal ratio and good slag forming capabilities.
• Such oxidizing agents can be present in an amount of less than or equal to about 50 weight % of the respective first or second pyrotechnic compositions of the pyrotechnic material.
• a 5-amino tetrazole substituted basic copper nitrate fuel for the gas generant is formed by representative substitution reaction (1 ) set forth above. 72.7 Ib of 5-amino tetrazole is charged to 42 gallons of hot water to form a 5-amino tetrazole solution. 272.9 Ib of basic copper nitrate is slowly added to the 5-amino tetrazole solution. 5-aminotetrazole and basic copper nitrate are allowed to react at 90 0 C until the reaction is substantially complete. To the reaction mixture are added 139.95 Ib of guanidine nitrate and 14.45 Ib of silicon dioxide. The slurried mixture is then spray dried.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Crystallography & Structural Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Air Bags (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=40260844

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (4)

Family Cites Families (15)

• 2008
  • 2008-08-07 EP EP08795096A patent/EP2190801A2/de not_active Withdrawn
  • 2008-08-07 WO PCT/US2008/009472 patent/WO2009023119A2/en active Application Filing
  • 2008-08-07 JP JP2010520991A patent/JP5641934B2/ja not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events