Methods of manufacturing monolithic generant grains
First Claim
1. A method for forming a monolithic gas generant grain comprising:
- admixing a pre-formed gas generant material comprising a water-soluble fuel with a ballistic performance modifier to form a mixture;
granulating said mixture; and
forming a pressed monolithic gas generant grain by applying pressure to said granulated mixture, wherein said water-soluble fuel incorporates said performance modifier into the monolithic gas generant grain, wherein said pressed monolithic gas generant grain has an actual density of at least about 95% of the maximum theoretical density of the gas generant.
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Accused Products
Abstract
Methods for making a pressed monolithic gas generant for an inflatable restraint device (for example, an airbag system for a vehicle) are provided. The methods include admixing a gas generant material with a ballistic performance modifier to form a mixture. The mixture is granulated. Then, a pressed monolithic gas generant grain is formed by applying pressure to the granulated mixture, where the grain has an actual density of at least about 95% of the maximum theoretical density. The pressure may be applied in a controlled manner to both side of the gas generant material in a die cavity, and removing formed grain from die cavity while maintaining some pressure to both sides of the grain, thereby further improving various pyrotechnic properties. The methods of the disclosure provide pyrotechnic compositions that are economical to manufacture, have improved burn rate, combustion profile, effluent quality, strength, durability, and integrity of the grain, while having a consistent shape between different production lots.
103 Citations
26 Claims
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1. A method for forming a monolithic gas generant grain comprising:
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admixing a pre-formed gas generant material comprising a water-soluble fuel with a ballistic performance modifier to form a mixture; granulating said mixture; and forming a pressed monolithic gas generant grain by applying pressure to said granulated mixture, wherein said water-soluble fuel incorporates said performance modifier into the monolithic gas generant grain, wherein said pressed monolithic gas generant grain has an actual density of at least about 95% of the maximum theoretical density of the gas generant. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 24)
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15. A method for forming a monolithic gas generant comprising:
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introducing a gas generant material into a die cavity, wherein the gas generant material in the die cavity has a first side and a second side opposite to said first side; applying pressure to said gas generant material along said first side and said second side to form a pressed monolithic grain that has an actual density of greater than or equal to about 95% of the maximum theoretical mass density of the gas generant material; and ejecting said pressed monolithic grain from said die by applying a greater pressure on said first side than on said second side to force said grain from the die, while maintaining an applied pressure on said second side during a portion of said ejecting, wherein said applied pressure is greater than or equal to about 3,000 psig (about 21 MPa). - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for forming a monolithic gas generant comprising:
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admixing a pre-formed gas generant material comprising a water-soluble fuel with a ballistic performance modifier selected from the group consisting of;
a coolant, a pressure sensitivity modifying agent, and combinations thereof, to form a mixture;compacting said mixture with an applied pressure of at least about 40,000 psig (about 275 MPa); granulating said mixture; and forming a pressed monolithic gas generant grain by applying pressure of greater than about 70,000 psi (about 480 MPa) to said granulated mixture, wherein said water-soluble fuel incorporates said performance modifier into said pressed monolithic gas generant grain, wherein said pressed monolithic gas generant grain has an initial surface area of less than about 13,000 mm2, wherein a product of a mass density and a gas yield of the gas generant is greater than or equal to about 5.0 moles/100 cm3, wherein the gas generant grain is substantially free of polymeric binder and has an actual density of at least about 95% of the maximum theoretical density of the gas generant.
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25. A method for forming a monolithic gas generant grain comprising:
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forming a gas generant material comprising a water-soluble fuel via a process selected from the group consisting of;
spray drying, dry blending, wet granulation, and combinations thereof;after said gas generant material is formed, admixing said gas generant material with a ballistic performance modifier to form a mixture; granulating said mixture; and forming a pressed monolithic gas generant grain by applying pressure to said granulated mixture, wherein said water-soluble fuel incorporates said performance modifier into said pressed monolithic gas generant grain, wherein said pressed monolithic gas generant grain has an actual density of at least about 95% of the maximum theoretical density of the gas generant. - View Dependent Claims (26)
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Specification