A gas generator is provided, the gas generator having a propellant cushion that prevents movement of propellant wafers, tablets, or grains by providing a bias thereagainst. Furthermore, the cushion may be formed from a polyurethane-based foam material and if desired, a known oxidizer combined within the foam. Channels inherent within the polyurethane-based foam enhance the combustion of the main gas generant. Alternatively, the substituted polyurethane polymer combined with an oxidizer may be formed as a monolithic grain that provides autoignition and gas generant function in lieu of a primary gas generant or in lieu of an igniter composition, for example.

TECHNICAL FIELD

The present invention relates generally to pyrotechnic gas generators for inflatable restraint devices, and more particularly to such a gas generator having a propellant cushion for biasing a resistance against the main propellant bed to prevent fracture of propellant grains, tablets, and/or wafers therein.

Alternatively, the present compositions may also be formed monolithically to supplant a typical main propellant bed, thereby eliminating the need to press distinct propellant wafers, for example.

BACKGROUND OF THE INVENTION

Inflatable restraint systems or “airbag” systems have become a standard feature in many new vehicles. These systems have made significant contributions to automobile safety, however, as with the addition of any standard feature, they increase the cost, manufacturing complexity and weight of most vehicles. Technological advances addressing these concerns are therefore welcomed by the industry. In particular, the gas generator or inflator used in many occupant restraint systems tends to be the heaviest, most complex component. Thus, simplifying the design and manufacturing of airbag inflators to reduce its size and complexity, while retaining optimal function, has long been a goal of automotive engineers.

Yet another concern is repeatability of performance of the gas generator. Metallic or ceramic cushions may be employed to prevent fracture of the propellant thereby maintaining a relatively constant propellant surface area of combustion. Even though useful in preventing the fracture of propellant, springs or known cushions made from ceramic or metal add to the manufacturing complexity and cost, and to the weight of the overall inflator.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a gas generator having a propellant cushion that prevents movement of the main propellant wafers or grains by providing a bias thereagainst. Furthermore, the cushion is formed from a polyurethane and a suitable oxidizer as indicated herein.

In accordance with the foregoing and other objects of the invention, a first exemplary passenger-side inflator having a lightweight propellant cushion formed from polyurethane and at least one suitable oxidizer is provided. An exemplary passenger-side inflator (PSI) preferably may include an elongate inflator body having a first and a second end and a plurality of inflation apertures. The inflator (PSI) body defines a first combustion chamber wherein a first propellant charge is positioned. In the exemplary dual-chambered inflator described above, A partitioning assembly is nested within the inflator body, and positioned proximate the second end, the partitioning assembly defining a second combustion chamber wherein a second propellant charge is positioned. The exemplary passenger-side inflator further includes a first and a second initiator, the initiators operably associated with the first and second propellant charges, respectively. The initiators are selectively operable to ignite the propellant charges, thereby supplying an inflation gas via the first chamber to an inflatable restraint cushion.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIG. 1, there is shown an exemplary passenger side inflator (PSI), or gas generator or inflator10, according to a first embodiment of the present invention. Inflator10is designed for use with an inflatable restraint system in an automobile, supplying inflation gas for inflation of a conventional airbag cushion, a function well known in the art. Inflator10utilizes two propellant charges, described herein, that are ignited in separate combustion chambers, and discharge inflation gas via a common plenum21. Exemplary inflator10further provides independently operable initiators for igniting the respective propellant charges, imparting significant variation to the available operating schemes for the inflator. For instance, both sequential and serial firing of the two charges is possible, depending on the optimal deployment of the associated airbag. It is contemplated that inflator10will find greatest utility in passenger-side airbag systems; however, other applications are possible without departing from the scope of the present invention. All the components of the present invention are formed from known materials that are readily available commercially.

Inflator10includes an elongate pressure vessel or inflator body11, preferably a hollow steel cylinder. Inflator body11is characterized by a first end15and a second end17, and defines a plurality of inflation apertures40that allow fluid communication between the exterior of the inflator body and plenum21. A first end closure13is positioned at first end15of inflator body11, preferably creating a fluid seal therewith. A second end closure34is preferably positioned at second end17, also preferably creating a fluid seal with inflator body11. Closures13and34are preferably metallic, however, they might be made from another suitable material such as a plastic, a ceramic, or a composite material. First end15and second end17are preferably crimped inwardly to hold first and second closures13and34in place, however, some other suitable method such as welding or mating threads on inflator body11and the respective closures might be used. In addition, rubber O-rings may be snap-fit around closures13and34, creating or enhancing seals with inflator body11.

Inflator10includes a first combustion chamber25, within which a quantity of gas generant material or first propellant charge28is placed. In a preferred embodiment, chamber25comprises a significant proportion of the interior of inflator body11, defined in part by longitudinal walls of inflator body11, and in part by first end closure13. Plenum21is the region of inflator body11whereby inflation gas is passed to apertures40. Thus, chamber25and plenum21are at least partially coextensive. Stated another way, plenum21may be loosely defined as an annular portion of chamber25that occupies a radially outer part of the middle region of the interior of inflator body11. The phrase “at least partially coextensive” should be understood to include designs wherein chamber25is subdivided by foils, burst shims, etc., as described herein, as well as designs wherein chamber25is uninterrupted by such features. First end closure13preferably includes a cylindrical extension16wherein a perforated disk18is positioned, separating chamber25into two sub-chambers25aand25b. An initiator assembly12, preferably including a conventional igniter or squib, is positioned at first end15, and preferably mounted in first end closure13such that it can ignite compositions in chamber25. A second initiator assembly9, also preferably including a conventional igniter or squib, is positioned at second end17.

Propellant charge or primary gas generating composition28may be any suitable gas generant composition known in the art, preferably a non-azide composition containing phase stabilized ammonium nitrate. Other gas generating compositions or auto-ignition compositions contained within the gas generator may contain perchlorate and chlorate containing oxidizers as known in the art. Exemplary, but not limiting formulations are described in U.S. Pat. Nos. 5,872,329, 5,756,929, 5,035,757, 8,273,199, 7,714,143 (e.g. compositions containing basic copper nitrate and guanidine nitrate), and U.S. Pat. No. 5,386,775, and are herein incorporated by reference in their entireties. In a preferred embodiment, propellant charge28is provided in both tablet28aand wafer28bforms, both of which are illustrated inFIG. 1. The tablets28aand wafers28bmay be different compositions, but are preferably the same material in different, commercially available forms. In a preferred embodiment, a retainer disk32separates tablets28afrom wafers28b. Disk32may be made from a relatively porous material such that a flame front or heat from ignition of tablets28acan ignite wafers28b, or it may be made from a known material that allows ignition of wafers28bby heat convection from the burning of tablets28a. A quantity of booster propellant14is preferably placed in sub-chamber25a, and is ignitable via initiator12in a conventional manner to ignite and enhance the burn characteristics of the first propellant charge28aand28b.

In accordance with one embodiment of the present invention, a cushion33is formed from a polyurethane-based propellant foam or composition and is positioned between propellant wafers28band a cap29, thereby inhibiting fracture of the wafers28bby virtue of its anti-rattle/vibration matrix. It is believed that the microcellular structure of the foam provides combustion channels inherent therein, thereby facilitating the complete combustion or consumption of the main propellant bed upon actuation of the inflator10. In further accordance of the present invention, the cushion33is formed from a composition containing one or more substituted polyurethane polymers. For example, it may be a chemical reaction between hydroxyl-containing molecules (or polyols) and the NCO-group of di-isocyanates resulting in the following polyurethane foams as detailed immediately below in the formula:

Yet further, the reaction may be more fully expressed as:

As indicated in the above reactions, R1 is an aliphatic group that when combined with an —OH or hydroxyl group represents a member from the group of aliphatic diols, triols, and other polyols; aliphatic ether diols and polyols; and monosaccharides and polysaccharides. The aliphatic group may for example be ethyl, propyl, butyl, pentyl, and so forth. Preferably, the resultant polyol contains five or less hydroxyl (—OH) groups. More preferably, the polyol contains two to four hydroxyl functionality. Further, as also indicated, R2 may be an aliphatic such as hexamethylene di-isocyanate (HDI) or an aromatic group selected from methylene diphenyl di-isocyanate, (MDI), Toluene di-isocyanate (TDI), and Isophorone di-isocyanate (IPDI)), that when R2 is reacted with the polyol it thereby forms the polyurethane foam or composition.

One or more substituted polyurethane polymers may be mixed with one or more oxidizers selected from metal perchlorates and nitrates, non-metal perchlorates, basic metal nitrates, transition metal oxides, and mixtures thereof. In particular, an oxidizer may be selected from non-metal, alkali metal, and transition metal perchlorates and nitrates including potassium perchlorate, ammonium perchlorate, basic copper nitrate, and mixtures thereof, for example. Polymeric foam is preferably provided at about 10-90 weight percent of the total weight of the composition of the cushion composition. An oxidizer(s) is preferably provided at about 10-90 weight percent of the total weight of the composition of the cushion composition. If added, a transitional metal oxide is added at about 1.0 to 10.0 weight percent of the total oxidizer component.

If desired, an additive may also be added. For example, an additive may include aliphatic or aromatic compounds selected from carboxylic acids, nitro compounds, nitrate salts, five and six membered heterocycles, tetrazoles and their derivatives, and metal hydrides. The additive may be provided at about 5-25 wt. % of the total pyrotechnic foam. Exemplary additives may include Bis tetrazole, bis tetrazole methane & titanium hydride.

The chemical reactants and constituents of the present invention may be manufactured as described herein, or, may be purchased from companies such as Aldrich, Fisher, and so forth.

The density of the foam may be iteratively determined or modified by altering the weight percent of the polyol and isocyanate fractions of the polyurethane system and/or by altering the weight percent of the oxidizer. It is believed that altering the density of foam is believed to provide an improved burn rate propagation throughout the bed, while yet utilizing the interstitial space defined between the discrete propellant shapes (e.g. wafers, pellets, tablets, asymmetric shapes, and so forth). As a result, a smaller inflator can deliver more gas per unit volume of the inflator or gas generator.

If desired, and as shown inFIGS. 3B-3D, the foam-in-place pyrotechnic system may be used to create a monolithic grain that supplants or at least partially supplants the need for a main gas generant bed. Stated another way, monolithic grains of the present invention may be formed to not only function as an autoignition compound, but also as the main gas generating source. It is believed that maximizing the interface between the inflator housing114and the monolithic grain142,144,146provides an auto-ignition advantage and therefore a safety enhancement, in that the monolithic grain is more efficiently ignited in the event of a bonfire for example.

In one embodiment, pyro foams were made by reacting 2:1 wt. ratios of polyol to di-isocyanate to form polyurethane, and then combined with varying weight ratios of oxidizers and fuels. A polyol is an alcohol containing multiple hydroxyl groups such as exemplary diols (e.g. polyethylene glycol, polypropylene glycol, and poly(tetramethylene ether) glycol), triols (e.g. glycerin), and so forth.

Other polyols contemplated include sugar alcohols such as maltitol, sorbitol, xylitol, erythritol, and isomalt.

A process of forming the pyrotechnic or propellant foam is as follows and as illustrated in the above-referenced formula: a 2:1 wt. ratio of polyol to di-isocyanate were added to a 250 ml plastic vial for mixing. Varying wt. ratios of oxidizer or oxidizer/fuel mix, depending upon the formulation, was added to the mixing vial, and then the mix was stirred at room temperature for less than a minute to yield a flexible pyro foam. In most cases the foam cure time is less than a minute. The polyol, isocyanate, and oxidizer are all preferably mixed together for a cure time of about 1 minute. A glass stir rod may be used to mix the material. In larger quantities, a larger, industrial mixer may be used as known in the art. The materials may be mixed on the inflator assembly line and then the resultant foam may be injected into the inflator before it cures, thereby allowing the extruded mixture to cure on the tablet bed and even seep into the void volume or interstitial cavities that are typically defined around the tablets, wafers, or pellets, thereby providing better and more intimate cushioning of the primary propellant bed. Or, the foam may be injected/extruded into the inflator as the only source of main generant, and as such replacing the tablets or wafers. In that embodiment, the foam would fill most if not all of the entire void volume of the combustion chamber. Yet further, as shown in certain examples, the foam may be pre-formed in the shape of a discoid cushion or in the shape of a booster tube, for example, and then inserted into the gas generator as appropriate.

Referring back to the inflator10ofFIG. 1, partitioning assembly26is positioned proximate second end17, and preferably comprises a substantially cylindrical base member27and a cap29. Base member27and cap29define a second combustion chamber35, which at least partially encases a second quantity of propellant38, preferably in both tablet and wafer form. Base member27and second end closure34may be the same piece, as in one preferred embodiment, or a plurality of separate, attached pieces might be used. In a preferred embodiment, partitioning assembly26is formed structurally independent from inflator body11. Partitioning assembly26is an independent piece having no physical attachment with the longitudinal sidewall of inflator body11. During assembly of inflator10, partitioning assembly26is slid into position in inflator body11, and second end17is crimped inwardly to secure assembly26therein. Thus, other than securing second end closure34, no modifications are made to inflator body11to accommodate or otherwise secure the components defining second combustion chamber35.

Cap29preferably includes a plurality of apertures30that can connect second chamber35with plenum21(as well as first chamber25, since plenum21and chamber25are fluidly connected and partially coextensive). In a preferred embodiment, a foil or burst shim (not shown) is placed across apertures30to block fluid communications between the two chambers. It should be appreciated, however, that the foil or burst shim is positioned and/or manufactured such that it will not burst inwardly, i.e. in the direction of second end17during combustion of propellant in chamber25. Combustion of propellant in second chamber35, on the other hand, is capable of bursting the foil or shim outwardly, allowing the combustion products in chamber35to escape to plenum21/first chamber25, and thereby discharge from inflator body11. The preferred foils and shims, and the described methods of mounting them are all known in the art. By fluidly isolating first and second chambers25and35, sympathetic ignition of the propellant in chamber35during combustion of the propellant in chamber25can be avoided, as described herein. The outer diameter of base member27is preferably substantially equal to the inner diameter of inflator body11, such that base member27is nested therein, i.e. fits relatively snugly. Because both second end closure34and inflator body11are preferably substantially cylindrical, the two components are preferably axially aligned. One or more auto-ignition tablets50may be placed in inflator10, allowing ignition of the gas generant materials upon external heating in a manner well known in the art.

In one embodiment ofFIG. 1, wafers28bare positioned in a stack in a primary combustion chamber25. Again, the cushion33, is positioned adjacent the stack28b, and biases the entire stack28btoward first end15. Wafers28b, in turn, preferably bias disk32against tablets28a, preventing tablets28afrom being jostled while the inflator is idle for long periods, helping avoid mechanical degradation of tablets28a.

The inflator10described herein may be altered in design depending on application requirements. Nevertheless, the cushion or propellant restraint33, in accordance with the present invention is provided in any inflator design, and biased against at least one propellant thereby providing a cushioning effect as formally realized by metallic cushions for example.

In a typical inflatable restraint system design, inflator10is connected to an electrical activation system that includes a crash sensor, of which there are many well-known suitable types. In addition, various sensing systems may be incorporated into the vehicle electronics, including seat weight sensors, occupant detection systems, etc. During a typical deployment scenario, an impact or a sudden vehicle deceleration, an activation signal is sent from an onboard vehicle computer to inflator10. The signal may be sent to either or both of the initiator assemblies housed with inflator10. Because chamber25preferably contains the larger, main charge, the activation signal is typically directed initially to the initiator assembly operably associated with first chamber25. In certain scenarios, for example with larger occupants, or where occupants are out of a normal seated position in the vehicle, it may be desirable to activate both propellant charges simultaneously. Other scenarios may call for different activation schemes. For instance, certain conditions may make it desirable to fire only the first propellant charge, or sequentially fire both charges, with varying time delays between the two events. Once an electrical activation signal is sent to the initiator associated with first chamber25, combustion of booster propellant14in sub-chamber25ais initiated. The flame front and/or hot combustion gases from booster14subsequently traverse disk18, initiating combustion of propellant tablets28ain chamber25b. The burning of tablets28aproduces inflation gas that flows rapidly out inflation apertures40, initiating filling of an associated airbag. A cylindrical, metallic mesh filter20is preferably positioned in inflator body11and as shown in the current embodiment in plenum21, whereby filter20filters slag produced by the combustion of the compounds therein, and also serves as a heat sink to reduce the temperature of the inflation gas. Combustion of tablets28ainitiates combustion of wafers28b, preferably made from the same or similar material as tablets28a, providing a sustained burn that delivers a relatively constant supply of gas to the associated airbag via plenum21and apertures40. When desired, an electrical activation signal is sent to the initiator operably associated with second chamber35, containing a gas generant composition38that is preferably similar to the composition in chamber25. Rapid creation of gas in chamber35causes a rapid rise in the gas pressure therein, outwardly bursting the foil or shim (not shown) that covers apertures30, in cap29. The gas is subsequently discharged from inflator10via plenum21and apertures40. Activation of the gas generant in chamber35can take place before, during, or after an activation signal is sent to initiator assembly12, operably associated with chamber25.

Because both chambers25and35discharge inflation gas through plenum21, the present invention provides different operating advantages over many earlier designs wherein separate plenums are used for each combustion chamber. By discharging inflation gases from both combustion chambers25and35through plenum21, the inflation profile characteristics across the length and width of an associated airbag can be improved as compared to earlier multi-chamber designs wherein the combustion chambers discharge via separate plenums. In addition, the use of a partitioning assembly structurally independent from the inflator body sidewalls allows the inflator to be constructed without crimping or otherwise modifying the inflator body itself. Moreover, because inflator10utilizes a plenum that is coextensive with a first of the combustion chambers, inflator10has a simpler design than multi-chamber inflators utilizing combustion chambers that are both partitioned from a common plenum. Inflator body11utilizes no attached internal partitions, and can therefore be manufactured without the need for strengthening to compensate for weakening caused by partition attachment. These and other advantages reduce the cost, manufacturing complexity, size and weight of the inflator.

Referring now toFIG. 2, the exemplary inflator10described above may also be incorporated into an airbag system200. Airbag system200includes at least one airbag202and an inflator10containing a pyrotechnic or propellant foam composition33,142,144,146,148, and/or150in accordance with the present invention, coupled to airbag202so as to enable fluid communication with an interior of the airbag. Airbag system200may also include (or be in communication with) a crash event sensor210. Crash event sensor210includes a known crash sensor algorithm that signals actuation of airbag system200via, for example, activation of airbag inflator10in the event of a collision.

Referring again toFIG. 2, airbag system200may also be incorporated into a broader, more comprehensive vehicle occupant restraint system180including additional elements such as a safety belt assembly150.FIG. 2shows a schematic diagram of one exemplary embodiment of such a restraint system. Safety belt assembly150includes a safety belt housing152and a safety belt100extending from housing152. A safety belt retractor mechanism154(for example, a spring-loaded mechanism) may be coupled to an end portion of the belt. In addition, a safety belt pretensioner156may be coupled to belt retractor mechanism154to actuate the retractor mechanism in the event of a collision. Typical seat belt retractor mechanisms which may be used in conjunction with the safety belt embodiments of the present invention are described in U.S. Pat. Nos. 5,743,480, 5,553,803, 5,667,161, 5,451,008, 4,558,832 and 4,597,546, incorporated herein by reference. Illustrative examples of typical pretensioners with which the safety belt embodiments of the present invention may be combined are described in U.S. Pat. Nos. 6,505,790 and 6,419,177, incorporated herein by reference.

Safety belt assembly150may also include (or be in communication with) a crash event sensor158(for example, an inertia sensor or an accelerometer) including a known crash sensor algorithm that signals actuation of belt pretensioner156via, for example, activation of a pyrotechnic igniter (not shown) incorporated into the pretensioner. U.S. Pat. Nos. 6,505,790 and 6,419,177, previously incorporated herein by reference, provide illustrative examples of pretensioners actuated in such a manner.

It should be appreciated that safety belt assembly150, airbag system200, and more broadly, vehicle occupant protection system180exemplify but do not limit vehicle occupant protection systems contemplated in accordance with the present invention.

In yet another embodiment of the present invention shown inFIGS. 3A-3F, the polyurethane polymer and oxidizer blend may be provided in the same manner within a driver side inflator (DSI). As shown inFIGS. 3A-3F, the DSI110contains a housing112. A perforated base114and a cap116are nested and joined together to form the housing112. An igniter118is sealed within a complementary igniter orifice120within the cap116, in a known way. For example, the igniter118may be provided in a body bore seal assembly119as known in the art. At least one igniter assembly124containing the igniter118and a perforated igniter tube126may be provided centrally within the housing112, in a known manner. For example, the igniter tube126may be press fit to the body bore seal assembly119and to the base114, whereby an ignition chamber128is thereby provided within the igniter tube126. Igniter chamber orifices130provide fluid communication from the igniter tube chamber128to a combustion chamber132, and may or may not be sealed with burst shims, tape seals, or other seals as known in the art.

As shown in the drawings, the combustion chamber132is formed within the housing112for combustion of an associated gas generating composition134.

An annular filter136is provided within the combustion chamber132, and is made in a known manner, from metallic mesh for example. Upon combustion of the gas generant134(formed in a known manner as described above), the effluent is filtered as it passes through the filter136.

As shown in a known configuration ofFIG. 3A, a ceramic cushion140may be used as a typical cushion for protecting the integrity of the gas generating composition tablets134.

As shown inFIG. 3B, and in accordance with the present invention, the ceramic cushion140ofFIG. 3Amay be replaced with a polyurethane/polymeric cushion142, whereby the cushion142is injected into the inflator110and then cured therein, as described above in the Example, for instance.

As shown inFIG. 3C, and in accordance with the present invention, the ceramic cushion140ofFIG. 3Aand a portion of the gas generating composition134may be replaced by a polyurethane/polymeric charge144, whereby the cushioning function and a portion of the gas generating function is provided by the charge144. Again, the charge144may be injected into the inflator or gas generator110and then cured therein, as described above in the Example, for instance.

As shown inFIG. 3D, and in accordance with the present invention, the ceramic cushion140ofFIG. 3Aand all of the known gas generating composition134may be replaced with a polyurethane/polymeric monolithic charge146, whereby the cushioning function and substantially all of the gas generating function are provided by the monolithic charge146. Again, the monolithic charge146may be injected into the inflator or gas generator110and then cured therein, as described above in the Example, for instance.

As shown inFIG. 3E, and in accordance with the present invention, the ceramic cushion140and the known primary gas generating composition134may be retained while still utilizing the advantages of the present invention. As shown inFIG. 3A, a known ignition composition, such as that described in U.S. Pat. No. 5,035,757 for example only, may be provided in a known manner. In the embodiment ofFIG. 3E, however, the ignition composition is completely replaced by a monolithic charge148. Again, the monolithic ignition charge148may be injected into the inflator or gas generator110during the manufacturing process, and then cured within the inflator110, as described above in the Example, for instance.

Gas exit orifices138are formed in the housing112or base114, and may or may not be sealed with burst shims, tape seals, or other seals as known in the art.

As shown inFIG. 3F, and in accordance with the present invention, the pyro foam150occupies at least a portion of the interstitial cavities152that are defined between the propellant shapes154. As described above, the pyro foam150may be mixed in an uncured state, including an oxidizer, and then injected or extruded into the cavities prior to the pyro foam setting or curing in place. As the pyro foam150is injected it migrates into the open areas or interstitial cavities152defined between the propellant shapes154, thereby providing a more intimate cushioning between at least some of the propellant tablets or shapes154. Additionally, as can be seen inFIG. 3F, the ability to maximize the efficient use of space within the combustion chamber facilitates the ability to produce more gas with a relatively smaller amount of volume, presenting a more efficient “mols of gas per unit volume”.

As described just above and as exemplified in the reaction, a mixture containing a 2:1 (weight) wt. ratio of polyol (nominal hydroxyl functionality of from 2 to 4) to di-isocyanate (Methylene diphenyl di-isocyanate) was added to a combustion chamber to form a mixture. Next, oxidizer component(s) at twice the weight of the mixture of the polyol and the di-isocyanate were added to a combustion chamber (effectively a mixing chamber) and the mix was then stirred, using a glass rod, for less than a minute to yield a monolithic pyrotechnic or propellant foam of the desired shape and size. The total weight percent of the polyol combined with di-isocyanate is 10-90 weight percent, and the total weight percent of the oxidizer ingredients is 10-90 weight percent.

As described just above and as exemplified in the reaction, a mixture containing a 2:1 (weight) wt. ratio of polyol (nominal hydroxyl functionality of from 2 to 4) to di-isocyanate (Methylene diphenyl di-isocyanate) was added to an injector or extruding tool. Next, an oxidizer component(s) at twice the weight of the mixture of the polyol and the di-isocyanate was added to the injector or extruding tool (effectively a mixing chamber) and the mix was stirred or agitated. The mixture was retained briefly in the injector in an uncured state and then injected into an inflator as shown inFIG. 3F, and more specifically into a propellant bed having interstitial cavities defined between the discrete primary propellant shapes, tablets, or wafers. The uncured mixture permeated at least a portion of the propellant bed and migrated into at least a portion of the interstitial cavities thereby providing localized cushioning areas within the propellant bed. When cured, the injected mixture formed a secondary propellant along with providing the cushioning benefit. Upon combustion of the first and second propellants within the inflator, a greater amount of gas was produced as compared to combustion of a propellant bed containing only the primary propellant.

A tabletted primary composition was prepared as in U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic foam was then mixed and injected into at least a portion of the interstitial cavities of 10 grams of the aforementioned tablets. The tablets generally settled into the bottom and middle regions of the injected foam. Upon curing, the pyrotechnic foam exhibited a flexible nature. The combined primary and secondary compositions exhibited an auto-ignition temperature of about 210-220 C as measured by hot plate.

A powdered primary composition was prepared as in U.S. Pat. No. 8,273,199 and as in Example 3 (except that it is powdered), the teachings of which are herein incorporated by reference. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic foam was then mixed with 15 grams of the aforementioned powdered primary composition and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition contributed to a pyrotechnic foam that was formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A powdered primary composition was prepared as in Example 4 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic or propellant foam was then mixed with 15 grams of the aforementioned powdered primary composition and 30 g of potassium perchlorate, and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition and the pyrotechnic foam was hard and stiff, and formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A powdered primary composition was prepared as in Example 4 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic foam was then mixed with 3 grams of the aforementioned powdered primary composition, and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition and the pyrotechnic foam formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A powdered primary composition was prepared as in Example 4 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic foam was then mixed with 5 grams of the aforementioned powdered primary composition, and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition and the pyrotechnic foam formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A powdered primary composition was prepared as in Example 4 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic or propellant foam was then mixed with 7.5 grams of the aforementioned powdered primary composition, and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition and the pyrotechnic foam was formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A powdered primary composition was prepared as in Example 4 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The uncured pyrotechnic foam was then mixed with 15 grams of the aforementioned powdered primary composition, and then injected into an inflator such as the inflator ofFIG. 3C-3E. The powdered primary composition and the pyrotechnic foam formed as more of a monolithic grain type. The combined primary and secondary compositions did not exhibit auto-ignition behavior at or below 250 C.

A tabletted primary composition was prepared as in Example 3 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference.

The tablets were then added to a combustion chamber as shown inFIG. 3F, at about 30 grams. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The mixture was retained briefly in the injector in an uncured state and then injected into an inflator as shown inFIG. 3F, and more specifically into a propellant bed having interstitial cavities defined between the discrete primary propellant shapes or tablets. The uncured mixture permeated the propellant bed and migrated into at least a portion of the interstitial cavities thereby providing localized cushioning areas within the propellant bed. In essence, the tablets were well-embedded in the foam. When cured, the injected mixture formed a secondary propellant along with providing the cushioning benefit. Upon combustion of the first and second propellants within the inflator, a greater amount of gas was produced as compared to combustion of a propellant bed containing only the primary propellant. The combined primary and secondary compositions exhibited an auto-ignition temperature of about 210-220 C as measured by hot plate.

A tabletted primary composition was prepared as in Example 3 and U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference.

The tablets were then added to a combustion chamber as shown inFIG. 3F, at about 45 grams. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The mixture was retained briefly in the injector in an uncured state and then injected into an inflator as shown inFIG. 3F, and more specifically into a propellant bed having interstitial cavities defined between the discrete primary propellant shapes or tablets. The uncured mixture permeated the propellant bed and migrated into at least a portion of the interstitial cavities thereby providing localized cushioning areas within the propellant bed. In essence, the tablets were well-embedded in the foam. When cured, the injected mixture formed a secondary propellant along with providing the cushioning benefit. Upon combustion of the first and second propellants within the inflator, a greater amount of gas was produced as compared to combustion of a propellant bed containing only the primary propellant. The combined primary and secondary compositions exhibited an auto-ignition temperature of about 210-220 C as measured by hot plate.

A powdered primary composition containing guanidine nitrate, strontium nitrate, ammonium perchlorate, and maleic hydrazide was prepared as described in U.S. Pat. No. 8,783,188, herein incorporated by reference in its entirety.

The powdered primary gas generating composition was then added to a combustion chamber as shown inFIG. 3F, at about 12 grams. A pyrotechnic or propellant foam (secondary composition) was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. The primary gas generating composition was added to the secondary composition and stirred. The resultant mixture was retained briefly in the injector in an uncured state and then injected into an inflator as shown inFIG. 3C-3Eas a monolithic grain. When cured, the injected mixture formed a monolithic grain. Upon combustion of the first and second propellants within the inflator, a greater amount of gas was produced as compared to combustion of a propellant bed containing only the primary propellant. The combined primary and secondary compositions auto-ignited at temperatures equal to or less than 250 C, as measured by hot plate.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.5314% by weight. The foam was slightly discolored to a brownish color. When initiating combustion within an exemplary inflator ofFIG. 3B-3F, the combustion behavior is similar for both baseline and certain aged materials—gases are melted off and then the composition combusts. The microstructure of this compound, as provided by a scanning electron microscope (SEMS), exhibits open and closed cells, and well-interconnected micro pores. In contrast, the density of this polyurethane compound is less than other elastomers such as silicone and therefore, on a comparative basis, the pyrotechnic foam compositions of the present invention unexpectedly provide enhanced and superior combustion propagation as compared to other elastomers such as silicone when similarly employed such as inFIGS. 3B-3F. See the Examples described herein relative to support for those unexpected and superior results correlating the pyrotechnic or propellant foams of the present invention.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Potassium nitrate, at about 30 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium nitrate mixture was about 1:2 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.4113% by weight. The foam was off-white in color. When initiating combustion within an exemplary inflator ofFIG. 3C-3E, the combustion behavior is similar for both baseline and certain aged materials—gases are melted off and then the composition combusts.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Potassium perchlorate, at about 15 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:1 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.4025% by weight. The foam was light brown in color.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Potassium perchlorate, at about 45 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:3 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.2883% by weight. The foam was off-white in color. The microstructure of the present pyrotechnic foam/composition (and Example 15), as provided by a scanning electron microscope (SEMS), indicates a microcellular microstructure with a relatively greater intimately mixed oxidizer (potassium perchlorate), as compared to other known compositions defined in Example 24 for instance, that facilitates a gas generating composition or propellant with improved burning properties such as a burn rate greater than 0.25 inches per second at 1-10 psi.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Basic copper nitrate, at about 15 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to basic copper nitrate mixture was about 1:1 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 2.04% by weight. The foam was blue to dark green in color. The composition did not pass heat aging tests.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Potassium perchlorate at about 15 grams, and copper oxide at about 30 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to copper oxide mixture was about 1:1:2 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.3213% by weight. The foam was black in color. When initiating combustion within an exemplary inflator ofFIG. 3C-3E, this composition combusted well and sustained the combustion. The microstructure of the present pyrotechnic foam/composition, as provided by a scanning electron microscope (SEMS), indicates a microcellular microstructure with a relatively greater interconnected microcellular structure, resulting in a relatively higher thermal conductivity as compared to other gas generating compositions, as compared to other compositions defined in Example 24 for instance, that results in a relatively lower temperature burning propellant thereby reducing the need to cool the gas combustion products to the same extent as other known gas generating compositions.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 10 grams, twice the amount of di-isocyanate provided at 5 grams. Potassium perchlorate at about 30 grams, and titanium hydride at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to titanium hydride mixture was about 1:2:1 by weight ratio. The resultant foam was heat aged at 107 C for 17 days. The foam or composition lost 0.03057% by weight. The foam was gray in color. This composition exhibited the best resistance to heat aging. When initiating combustion within an exemplary inflator ofFIG. 3C-3E, this composition combusted well and sustained the combustion.

The examples directed at heat aging were found to be satisfactory with less than 1.0% by weight of mass loss.

A pyrotechnic or propellant foam was substantially prepared as described in Examples 15 and 16. However, in this example, the weight ratio of polyurethane to potassium perchlorate was 1:1. The oxygen balance was −71. Upon combustion in an inflator exemplified inFIGS. 3C-3E, the gas yield was 4.87 mol/100 g. The gas conversion was about 73 weight percent of the combustion products. The solids produced upon combustion were about 23 weight percent, the weight percents taken with regard to the total weight of the combustion products. In this composition, the mols of nitrogen were 7.6, the mols of carbon dioxide were 13, and the mols of water were 72.

The gas molecular weight in grams per mol was 38.

A pyrotechnic or propellant foam was substantially prepared as described in Examples 15 and 16. However, in this example, the weight ratio of polyurethane to potassium perchlorate was 1:2. The oxygen balance was −33.7. Upon combustion in an inflator exemplified inFIGS. 3C-3E, the gas yield was 3.77 mol/100 g. The gas conversion was about 65 weight percent of the combustion products. The solids produced upon combustion were about 35 weight percent, the weight percents taken with regard to the total weight of the combustion products. In this composition, the mols of nitrogen were 6, the mols of carbon dioxide were 100, and the mols of water were 53. The gas molecular weight in grams per mol was 36.

A pyrotechnic or propellant foam was substantially prepared as described in Examples 15 and 16. However, in this example, the weight ratio of polyurethane to potassium perchlorate was 1:3. The oxygen balance was −12.5. Upon combustion in an inflator exemplified inFIGS. 3C-3E, the gas yield was 3.16 mol/100 g. The gas conversion was about 60 weight percent of the combustion products. The solids produced upon combustion were about 40 weight percent, the weight percents taken with regard to the total weight of the combustion products. In this composition, the mols of nitrogen were 4, the mols of carbon dioxide were 80, and the mols of water were 41. The gas molecular weight in grams per mol was 34.6.

A pyrotechnic or propellant foam was substantially prepared as described in Examples 15 and 16. However, in this example, the weight ratio of polyurethane to potassium perchlorate was 1:4. The oxygen balance was −0.8. Upon combustion in an inflator exemplified inFIGS. 3C-3E, the gas yield was 2.81 mol/100 g. The gas conversion was about 57 weight percent of the combustion products. The solids produced upon combustion were about 43 weight percent, the weight percents taken with regard to the total weight of the combustion products. In this composition, the mols of nitrogen were 4, the mols of carbon dioxide were 63, and the mols of water were 33. The gas molecular weight in grams per mol was 34.8.

Each of the examples in Examples 20-23 exhibited the following: a heat of reaction of about 2500 calories per gram; a PEP combustion temperature of 2900 C; a softening point greater than 275 C; an impact sensitivity greater than 15 inches; a friction sensitivity greater than 360N; and, a burning rate at 1-10 psi greater than 0.25 inches per second. Accordingly, the burn rate of these compositions indicated a very robust burn even at relatively low pressures.

A first gas generating composition was made according to U.S. Pat. No. 5,035,757, the teachings of which are herein incorporated by reference. A second gas generating composition was made according to U.S. Pat. No. 8,273,199, the teachings of which are herein incorporated by reference. A third gas generating composition was made according to U.S. patent application Ser. No. 11/789,756, the teachings of which are herein incorporated by reference. A pyrotechnic foam (PF) was made as described in Example 16. The respective heats of combustion (calories/gram) for each of these compositions was as follows: first composition—775; second composition—1200; third composition—888; and the heat of combustion for the pyrotechnic foam was 2500. The need to provide a more robust inflator able to accommodate higher operating/combustion pressures is reduced as the heat of combustion increases, thereby facilitating a more robust burn rate even at lower operating pressures. See for example, Examples 20-23.

A compound as prepared in Example 13, polyurethane, was found to have a greater propensity to adsorb moisture, or a relatively greater hygroscopicity wherein the following moisture gains at the humidity indicated (at 23 C) were recorded:(1) 30% relative humidity for twenty-four hours resulted in 0.06609 weight percent gain with regard to the pre-humidification of the sample;(2) 40% relative humidity for twenty-four hours resulted in 0.259 weight percent gain with regard to the pre-humidification of the sample;(3) 50% relative humidity for twenty-four hours resulted in 0.6344 weight percent gain with regard to the pre-humidification of the sample;(4) 60% relative humidity for twenty-four hours resulted in 0.811 weight percent gain with regard to the pre-humidification of the sample;(5) 70% relative humidity for twenty-four hours resulted in 1.2425 weight percent gain with regard to the pre-humidification of the sample;(6) 80% relative humidity for twenty-four hours resulted in 1.7765 weight percent gain with regard to the pre-humidification of the sample; and(7) 90% relative humidity for twenty-four hours resulted in 2.5273 weight percent gain with regard to the pre-humidification of the sample.

A pyrotechnic or propellant foam as prepared in Example 14, was found to have a relatively greater resistance to adsorb moisture, or a relatively lesser hygroscopicity, wherein the following relatively lower moisture gains at the humidity indicated (at 23 C) were recorded:(1) 30% relative humidity for twenty-four hours resulted in 0.032 weight percent with regard to the pre-humidification of the sample;(2) 40% relative humidity for twenty-four hours resulted in 0.08008 weight percent with regard to the pre-humidification of the sample;(3) 50% relative humidity for twenty-four hours resulted in 0.1921 weight percent with regard to the pre-humidification of the sample;(4) 60% relative humidity for twenty-four hours resulted in 0.2082 weight percent with regard to the pre-humidification of the sample;(5) 70% relative humidity for twenty-four hours resulted in 0.3111 weight percent with regard to the pre-humidification of the sample;(6) 80% relative humidity for twenty-four hours resulted in 0.4299 weight percent with regard to the pre-humidification of the sample; and(7) 90% relative humidity for twenty-four hours resulted in 0.6315 weight percent with regard to the pre-humidification of the sample.

A pyrotechnic or propellant foam as prepared in Examples 15 or 16, but with the potassium perchlorate being provided at about twice the weight of the polyurethane (2:1 weight ratio of potassium perchlorate to polyurethane), was found to have a relatively greater resistance to adsorb moisture, or a relatively lesser hygroscopicity, wherein the following relatively lower moisture gains at the humidity indicated (at 23 C) were recorded:(1) 30% relative humidity for twenty-four hours resulted in 0.06506 weight percent with regard to the pre-humidification of the sample;(2) 40% relative humidity for twenty-four hours resulted in 0.121 weight percent with regard to the pre-humidification of the sample;(3) 50% relative humidity for twenty-four hours resulted in 0.2405 weight percent with regard to the pre-humidification of the sample;(4) 60% relative humidity for twenty-four hours resulted in 0.2933 weight percent with regard to the pre-humidification of the sample;(5) 70% relative humidity for twenty-four hours resulted in 0.4251 weight percent with regard to the pre-humidification of the sample;(6) 80% relative humidity for twenty-four hours resulted in 0.5643 weight percent with regard to the pre-humidification of the sample; and(7) 90% relative humidity for twenty-four hours resulted in 0.7928 weight percent with regard to the pre-humidification of the sample.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Potassium nitrate, at about 7.7 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium nitrate mixture was about 3:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, and exhibited an open cell structure that the oxidizer occupied. The micropores were well-interconnected, thereby facilitating excellent thermal conductivity and burn rate propagation. The composition was well-suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Potassium nitrate, at about 15.4 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium nitrate mixture was about 1.5:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, and exhibited an open cell structure that the oxidizer occupied. The micropores were well-interconnected, thereby facilitating excellent thermal conductivity and burn rate propagation. The composition was well-suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Potassium nitrate, at about 23.1 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium nitrate mixture was about 1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, and exhibited an open cell structure that the oxidizer occupied. The micropores were well-interconnected, thereby facilitating excellent thermal conductivity and burn rate propagation. The composition was well-suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Potassium nitrate, at about 46 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium nitrate mixture was about 1:2 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam exhibited an open cell structure that the oxidizer occupied. The micropores were well-interconnected, thereby facilitating excellent thermal conductivity and burn rate propagation. The composition was still suited for cushion application. Even so, as the oxidizer amount increases, the cushioning effect decreases.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Potassium perchlorate, at about 23.1 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, and exhibited an open cell structure. The micropores were well-interconnected, thereby facilitating excellent thermal conductivity and burn rate propagation. The composition was well-suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Basic copper nitrate, at about 23.1 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to basic copper nitrate mixture was about 1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was stiff, with an open cell structure and well interconnected micropores. However, a uniform mixture was not obtained. The composition was not suited for cushion application. The composition functioned as a main gas generant and presented a relatively cool-burning foam.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Basic copper nitrate, at about 7.7 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to basic copper nitrate mixture was about 3:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, with an open cell structure and well interconnected micropores. The composition was suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 15.4 grams, twice the amount of di-isocyanate provided at 7.7 grams. Basic copper nitrate, at about 23.1 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to basic copper nitrate mixture was about 1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, with an open cell structure and well interconnected micropores. The composition burned slowly but sustained the combustion. The composition was suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate, at about 21 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:2 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, with an open cell structure and well interconnected micropores. The composition was suited for cushion application, ignited well, sustained combustion, and may function as a main gas generant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate, at about 31.5 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:3 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was less flexible, with an open cell structure and well interconnected micropores. The composition was not suited for cushion application, but ignited well, sustained combustion, burns relatively very fast, and may function as a main gas generant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate, at about 42 grams, was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate mixture was about 1:4 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was hard and stiff, with an open cell structure and well interconnected micropores. The composition was not suited for cushion application, but ignited well, sustained combustion, burns relatively very fast, and may function as a main gas generant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate at about 21 grams, and, copper oxide at about 10 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to copper oxide mixture was about 1:2:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was less flexible, with an open cell structure and well interconnected micropores. The composition was suited for cushion application, and ignited well and sustained combustion. The composition was black in color.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate at about 10 grams, and, copper oxide at about 21 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to copper oxide mixture was about 1:1.5:1.5 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was flexible, with an open cell structure and well interconnected micropores. The composition was suited for cushion application, and ignited well and sustained combustion. The composition was black in color.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate at about 15 grams, and, basic copper nitrate at about 15 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to basic copper nitrate mixture was about 1:1.5:1.5 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was hard, with an open cell structure and well interconnected micropores. The composition was not well-suited for cushion application, but sustained combustion. The composition was blue in color.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate at about 15 grams, molecular sieve (13×) at about 7.5 grams, and, copper oxide at about 7.5 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to molecular sieve to copper oxide mixture was about 1.5:2:1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was hard, with an open cell structure and well interconnected micropores. The composition was not well-suited for cushion application, but sustained combustion. The composition was blue in color.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7 grams, twice the amount of di-isocyanate provided at 3.5 grams. Potassium perchlorate at about 10.5 grams, and molecular sieve (13×) at about 10.5 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to potassium perchlorate to molecular sieve mixture was about 1:1:1 by weight ratio. Based on scanning electron microscope (SEMS) analysis, the resultant foam was hard, with an open cell structure and well interconnected micropores. The composition was not well-suited for cushion application, and did not sustain combustion.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Sodium nitrate at about 24 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to sodium nitrate was about 1:2 by weight ratio. The composition functions as a slow-burning propellant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Strontium nitrate at about 24 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to strontium nitrate was about 1:2 by weight ratio. The composition functions as a slow-burning propellant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Ammonium polyvinyl-tetrazole (A-PVT) at about 6 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to A-PVT was about 2:1 by weight ratio. The composition functions as a slow-burning fuel.

A pyrotechnic or propellant grain was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Ammonium polyvinyl-tetrazole (A-PVT) at about 12 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing, wherein the polyurethane to A-PVT was about 1:1 by weight ratio. The composition formed as a grain and functions as a slow-burning fuel.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Iron (III) oxide at about 12 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition functions as a slow-burning propellant.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 8 grams, twice the amount of di-isocyanate provided at 4 grams. Potassium perchlorate at about 12 grams and Bis-1H-tetrazole (acidic) at about 12 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition functions as a fast-burning propellant.

A pyrotechnic or propellant grain was prepared as in Example 1, wherein the polyol was provided at 6 grams, twice the amount of di-isocyanate provided at 3 grams. Potassium perchlorate at about 12 grams and Bis-1H-tetrazole (acidic) at about 12 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition formed as a grain and functions as a fast-burning propellant and if desired, a main gas generating composition.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 4 grams, twice the amount of di-isocyanate provided at 2 grams. Potassium perchlorate at about 12 grams and titanium hydride at about 6 grams were mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition functions as a fast-burning sparkle propellant (or gas generating composition) and booster.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7.5 grams, twice the amount of di-isocyanate provided at 7.5 grams. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The cured composition was hard and stiff. Excess di-isocyanate is attributed to the stiffness of the composition. The composition is not suitable as a cushion.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at 7.5 grams, and the amount of di-isocyanate is provided at about 15 grams. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The cured composition was hard and stiff wherein the top and bottom surfaces were much harder than the middle section of the foam. Excess di-isocyanate is attributed to the stiffness of the composition. The composition is not suitable as a cushion.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at about 15 grams, and the amount of di-isocyanate is provided at about 7.5 grams. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The cure rate of the composition was accelerated, and a higher foam volume occurred with flexibility in the foam well-suited for cushion application. The component weight ratios of this composition are strongly preferred for foam formation.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at about 22.5 grams, and the amount of di-isocyanate is provided at about 7.5 grams. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition remained sticky and did not cure. Unreacted and excess polyol make the foam sticky and not suited for cushion application.

A pyrotechnic or propellant foam was prepared as in Example 1, wherein the polyol was provided at about 7.5 grams, and the amount of di-isocyanate is provided at about 22.5 grams. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 15 grams was mixed into the uncured polyol/di-isocyanate mixture (polyurethane) prior to curing. The composition cured to a hard and brittle consistency. The composition was unsuited for cushion application.

Example 57 Standard Ceramic Cushion

A primary pyrotechnic composition was prepared as described in U.S. patent application Ser. No. 13/637,552, the teachings of which are herein incorporated by reference. The primary composition contained the following substantially uniform mixture: ammonium nitrate at about 66.6 wt. % phase stabilized with about 10.0 wt. % potassium nitrate, ammonium di-nitro salicylic acid at about 13.9 wt. %, and di-ammonium salt of bis-1H-tetrazole at about 10.0 wt. %. This composition was coated with paraffin at about 0.2 wt. % of the total composition as mixed and described above.

An inflator or gas generator as described herein and shown inFIG. 3A(e.g. with a ceramic cushion126) was loaded with 24 grams of the composition described herein. Upon actuation of the inflator, a maximum chamber pressure of about 32 MPa occurred, and a maximum tank pressure (one cubic foot volume) of about 190 kPa occurred.

A primary pyrotechnic composition weighing 23.5 grams was prepared as described in Example 61. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 1.5 grams was also provided. A pyrotechnic or propellant cushion was prepared as described in Example 36.

An inflator or gas generator as described herein and shown inFIG. 3Bwas loaded with a pyrotechnic or propellant foam cushion142was loaded with the compositions and cushion described above. Upon actuation of the inflator, a maximum chamber pressure of about 40 MPa occurred, and a maximum tank pressure (one cubic foot volume) of about 78 kPa occurred.

A pyrotechnic or propellant cushion was prepared as described in Example 36. An inflator or gas generator as described herein and shown inFIG. 3B or 3C(e.g. with a pyrotechnic or propellant foam cushion142/144weighing 3.83 grams) was loaded with the cushion described above. Upon actuation of the inflator, a maximum chamber pressure of about 56 MPa occurred, and a maximum tank pressure (one cubic foot volume) of about 240 kPa occurred.

A primary pyrotechnic composition weighing 23.0 grams was prepared as described in Example 61. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 1.0 grams was also provided. A pyrotechnic or propellant cushion was prepared as described in Example 36.

An inflator or gas generator as described herein and shown inFIG. 3B or 3C(e.g. with a pyrotechnic or propellant foam cushion142/144weighing 2.5 grams was loaded with the compositions and cushion described above. Upon actuation of the inflator, a maximum chamber pressure of about 27.5 MPa occurred, and a maximum tank pressure (one cubic foot volume) of about 180 kPa occurred.

A primary pyrotechnic composition weighing 23.0 grams was prepared as described in Example 61. An auto-ignition and booster composition as formed in U.S. Pat. No. 8,273,199, at about 1.5 grams was also provided. A pyrotechnic or propellant cushion was prepared as described in Example 36. However, the cushion had 4 parts of potassium perchlorate per 1 part of polyurethane.

An inflator or gas generator as described herein and shown inFIG. 3B or 3C(e.g. with a pyrotechnic or propellant foam cushion142/144weighing 3.9 grams was loaded with the compositions and cushion described above. Upon actuation of the inflator, a maximum chamber pressure of about 47.5 MPa occurred, and a maximum tank pressure (one cubic foot volume) of about 220 kPa occurred.

Example 62 Booster Tube Pyrotechnic Cushion

A pyrotechnic or propellant cushion/booster tube was formed from polyurethane and potassium perchlorate at a 1:2 weight ratio, and was prepared as described in Example 36.

An inflator or gas generator as described herein and shown inFIG. 3E(e.g. with a pyrotechnic or propellant foam cushion148weighing 3.9 grams was loaded into the inflator as shown. This completely supplanted the need for a metal booster tube and booster composition therein. Upon actuation of the inflator, a maximum tank pressure (one cubic foot volume) of about 190 kPa occurred with a relatively high average output of about 180 kPa tank pressure over 0.225 seconds. A maximum chamber pressure (in the inflator) was measured at about 63 mPa.

It is further understood that the ballistic behavior of the booster tube may be modified by altering its shape, increasing its porosity by boring holes through the structure, and in general, increasing or altering the surface area to modify the burn rate.

With regard to the pyrotechnic or propellant foam (secondary gas generating composition) containing polyurethane and at least one oxidizer, the total weight percent of the polyol combined with di-isocyanate, that is the polyurethane, is 10-90 weight percent; with regard to the oxidizer component containing one or more oxidizers, the total weight percent of the oxidizer ingredients is 10-90 weight percent, again with the weight percents taken with regard to the total weight of the secondary gas generating composition.

The present description is for illustrative purposes only, and should not be construed to limit the breadth of the present invention in any way. Thus, those skilled in the art will appreciate that various modifications could be made to the presently disclosed embodiments without departing from the intended spirit and scope of the present invention. Other aspects, features and advantages will be apparent upon an examination of the attached drawing figures.