MXPA99001982A - Eutectic mixtures of ammonium nitrate and amino guanidine nitrate - Google Patents

Abstract

An eutectic solution of ammonium nitrate and either aminoguanidine nitrate (AGN) or guanidine nitrate (AN) in the form of a present pellet is used to generate a particulate-free, non-toxic, odorless and colorless gas that is useful wherever an immediate source of such gas is required, such as the inflation of an occupant restraint air bag. The use of the material in the form of an eutectic totally eliminates pellet cracking. Moreover, the addition of a minor amount of potassium nitrate to the eutectic solution eliminates the ammonium nitrate phase change due to temperature cycling without adversely affecting the pressed pellets'freedom from cracking due to said temperature cycling.

Description

EUTECTIC ME2CLAS OF AMMONIUM NITRATE AND AMINO NITRATE. * - GUANIDINE FIELD OF THE INVENTION The present invention relates to a mixture forming a solution eutéctisa of ammonium nitrate (AN) and either aminoguanidine nitrate (AGN) or guanidine nitrate (GN), and optionally potassium nitrate (KN), which will generate a particle-free, non-toxic, colorless and odorless gas, for various purposes, such as inflating a restriction for the occupant of a vehicle, i.e., an airbag for a motor vehicle.

BACKGROUND OF THE INVENTION The present invention relates generally to solid composite propellant compositions, and more particularly, to solid composite propellant compositions useful as gas generators. Recently, there has been a great demand for propellants that generate gas, novel, which are cold burned, non-corrosive and produce a high volume of gas and few "solid particles," because attempts to improve existing gas generating compositions For example, while the addition of certain modifiers has decreased the flame temperature and increased gas production, these same modifiers have contributed to the production of undesirable corrosive products. , other modifiers used in the past, although they do not produce corrosive materials, have not succeeded in decreasing the temperature of the flame significantly, or increasing the evolution of gas.The usual gas generating composition, known in generation technology of gas as a propellant, is comprised of an ammonium nitrate oxidant with rubber-like binders oe n pressed loads. Several chemicals, such as guanidine nitrate, scrub and melamine, are used in the propellant to aid in ignition, give a uniform burn, modify burn rates and give lower flame temperatures. Ammonium nitrate is the most commonly used oxidant, since it is exceptionally effective per unit weight and provides non-toxic, non-corrosive exhaust at low flame temperatures. In addition, it contributes to burn speeds lower than those of other oxidants. Ammonium nitrate is cheap, easily available and safe to handle. The main objection to ammonium nitrate is that it undergoes certain phase changes during temperature variations, which causes fractures and voids, if some associated binder is not strong enough and flexible enough to keep the composition together. The . Ammonium nitrate compositions are hygroscopic and difficult to burn, particularly if small amounts of moisture have been absorbed. Since said compositions do not support combustion at low pressures, several combustion catalysts are added to promote ignition and low pressure combustion, as well as to achieve stable, uniform burning. The gas generating compositions used for the air bags should not contain metallic additives or even oxidants, such as ammonium perchlorate, because they give erosive and corrosive exhaust gases, respectively. The commonly used additives, such as ammonium dichromate, copper chromite, etc., are disadvantageous, since they all produce solids in the exhaust gases. The gas generating compositions are usually manufactured, by pressing, or by an extrusion and compression molding technique. The solid particles are formed and the composition is broken into pieces (* granulate "), with an appropriate granulator type equipment.After granulation, the composition is loaded into molds of the required shapes and pressed at approximately 7,000 psi (492.1). kg / cm2) With certain types of binders, the molds are heated to approximately 180 ° F (82 ° C), until the composition is cured or vulcanized.The granulate is packed in the gas generating boxes., mills and extrusion equipment are expensive, the long process time additionally increases manufacturing costs. It is especially difficult to produce large granules by this technique. The art is replete with examples of compositions containing a compound of the guanidine type, together with an oxidant, such as ammonium nitrate. For example, in U.S. Patent 3,031,347, guanidine nitrate and ammonium nitrate are listed together in column 2, as well as in Examples 3 and 5. However, compared to the present invention, not only the guanidine compound it lacks an amino group, as in the aminoguanidine nitrate modality, but the composition described in the patent is not a mixture that forms a eutectic solution. Similarly, see U.S. Patent 3,739,547, col. 2, in the Table. On the other hand, US Pat. No. 3,845,970, in column 3, describes a list of solid compositions for generating gas in a shock absorption system. Among the components of the varied compositions are ammonium nitrate, and aminoguanidine nitrate. The two materials are not described in a mixture and, obviously, are not in a eutectic composition.

Similarly, U.S. Patent 3,954,528 describes solid, novel, composite gas generating compositions. Among the ingredients mentioned are ammonium nitrate and triaminoguanidine nitrate. See Examples 2 to 5. However, neither the specified components of the available aminoguanidine nitrate compositions, nor any eutectic composition, are disclosed therein. In U.S. Patent 4,111,728, the inventor describes ammonium nitrate with small amounts of guanidine nitrate. See column 2 and the table in columns 3-4. However, the compositions do not include the aminoguanidine nitrate and do not characterize any composition as forming a eutectic solution. Patent 5,125,684, also discloses propellant compositions containing dry aminoguanidine nitrate, and an oxidizing salt containing a nitrate anion. However, the description is deficient with respect to the present invention, since it fails to describe the specific combination of the components of the present invention and does not mention eutectics. Finally, US Pat. No. 5,336,439 relates to compositions of salts and concentrates used in explosive emulsions. As described in columns 37 and 38, ammonium nitrate is one of the ingredients to form the composition of the patent licensee, while in column 20, line 51, aminoguanidine is indicated as being also an appropriate component . However, like the other descriptions mentioned, the patent fails to describe a specific composition that includes the same nitrates as described herein, and clearly, does not teach a eutectic composition containing said components.

BRIEF DESCRIPTION OF THE INVENTION The present invention involves eutectic mixtures of ammonium nitrate and guanidine nitrate (GN), or aminoguanidine nitrate, as well as a method for generating a particle-free, non-toxic, odorless and colorless gas for various purposes , such as for inflating an airbag in a motor vehicle. In the generation of a particle-free, non-toxic, odorless and colorless gas, a closed pressure chamber is provided, which has an exit door; a solid eutectic solution, comprising ammonium nitrate and either aminoguanidine nitrate or guanidine nitrate (GN), is placed inside the chamber; then means are provided for igniting the eutectic solution in response to a sudden deceleration, detected by a detection device in the pressure chamber, where the gas is generated instantaneously and conducted through the exit door of the chamber of pressure to fulfill a desired function, such as inflating an airbag of a motor vehicle. It has been found that eutectic mixtures of ammonium nitrate and aminoguanidine nitrate or guanidine nitrate, eliminate the breakdown of the granulate and substantially reduce the phase change of ammonium nitrate, due to the temperature cycle. In addition, the addition of up to about 10% potassium nitrate (KN) to the aforementioned eutectic, stabilizes the ammonium nitrate (AN), completely eliminates the phase change of the ammonium nitrate and maintains the freedom of rupture of the pressed granulate with the temperature cycle.

DESCRIPTION OF THE PREFERRED MODE To obtain the advantages of using ammonium nitrate, for example, low cost, availability and safety, while avoiding the disadvantages, for example, cracks and gaps in the pressed granulate when subjected to the temperature cycle, it is proposed to mix the ammonium nitrate oxidant with aminoguanidine nitrate or guanidine nitrate, and then form a eutectic solution, which avoids some of the problems encountered and discussed previously. Thus, the provision of ammonium nitrate / aminoguanidine nitrate or AN / GN co or a eutectic in the form of a pressed granulate, provides a generator to produce a particle-free, nontoxic, odorless and colorless gas to inflate an air pocket, but without the tendency of the granulate to break and with a reduced phase change of the AN, due to the temperature cycle. In addition, the hygroscopicity of the mixture is reduced to some degree. By adding small amounts of potassium nitrate, such as up to about 10% by weight, the freedom for rupture of the pressed granulate is still maintained, with the temperature cycle, and the phase change of the AN is completely eliminated. . When equal amounts of ammonium nitrate and aminoguanidine nitrate are fused together, a low melting point solution is formed. The respective melting points are 169, 148 and 108 ° C for the ammonium nitrate, aminoguanidine nitrate and the 50/50 mixture thereof, respectively. When 33 grams of ammonium nitrate / 50/50 aminoguanidine nitrate are fixed with 159 grams of argon in a 60 mm (diameter) gas generator, for a passenger-side air bag, the pressure in a tank of 60 liters is 84 psi (5.90 kg / cm2). The effluent is free of particles, is non-toxic, odorless and colorless. In addition, it has been discovered that the same eutectic used to generate the gases, can also be used as the ignitor in the inflator device. By using the same eutectic in this way to burn the propellant, the inventors are able to eradicate the smoke that could otherwise be present in the exhaust. For charging the ignitor, the eutectic is provided as a powder, granulate, monolithic compound or in any other form, which can be conveniently placed in the generator. In some cases, small amounts (up to about 5% by weight) of polyvinyl alcohol (PVA), as a binder, are employed in the above compositions. Also, to increase the stabilization of ammonium nitrate, up to about 5% by weight of zinc oxide (ZnO) can be added to the compositions. By using combinations of potassium nitrate and zinc oxide, stability at temperatures can be achieved. up to 107 ° C.

THE DRAWINGS To demonstrate the effectiveness of the present propellant system, attention is drawn to Figure 1 of the present drawings, wherein the heat flux DSC (Yes / g) produced by the ammonium nitrate (AN) and the eutectic of ammonium nitrate / aminoguanidine nitrate (AN / AGN), and a mixture of AN, AGN and potassium nitrate (KN), are compared. It will be noted that the composition of three components provides a uniform heat flux of up to 98.96 ° C. On the other hand, the composition of two components decreases slightly at 52.75 ° C, and subsequently continues at 86.60 ° C. Ammonium nitrate, by itself, exhibits a precipitous drop at 52.75 ° C, followed by a slight increase and a second fall at 8 .25 ° C. In Figure 2, small variations in the concentration of potassium nitrate are compared in AN / GN / KN compositions. At 1% KN, the composition exhibits a slight decline at 53.07 ° C, and continues without any major variation to 966.07 ° C. On the other hand, when the concentration of potassium nitrate is increased to 1.5%, the heat flow continues at a constant speed up to 97.13 ° C. By increasing the concentration of potassium nitrate up to 1.75%, the inventors extend the uniform heat flux to 98.84 ° C. • • In a further comparison, similar to that shown in Figure 2, but with AGN instead of GN, Figure 3 shows essentially the same pattern of heat flow. Although larger differences are reported between compositions containing 1.75% KN, as opposed to the compositions containing 1.5% KN and 1.25% KN, compared to the results in Figure 2, the general graph represents essentially the same type of data. Figure 4 represents a comparison like that ^ 2; of Figure 1, but exemplifying the phase change of a guanidine nitrate / ammonium nitrate composition (GN / AN), instead of an AGN / AN composition. Although the specific values for the depressions vary somewhat, the general results follow the same pattern shown for the corresponding composition containing aminoguanidine nitrate, instead of guanidine nitrate, as here. Figure 5 provides an analysis of the exhaust gas, provided with a propellant of aminoguanidine nitrate / ammonium nitrate. The exhaust gas is collected in a 60-liter tank and indicates 1300 ppm of carbon dioxide, with a smaller amount of 530 ppm of carbon monoxide. The exhaust gas also contains small amounts of hydrogen cyanide, formaldehyde, ammonia and nitrogen oxides. In Figure 6, a conventional apparatus for use in generating gas for inflating an airbag for a motor vehicle is described. As is easily seen from the drawing, exit doors are provided at the right end of the device. The following formulations within the scope of the present invention provide very good results: Example 1 47% by weight of guanidine nitrate; 47% by weight of ammonium nitrate; 3% by weight of potassium nitrate; and 3% by weight of zinc oxide Example 2 47.5% by weight of guanidine nitrate; 47.5% by weight of ammonium nitrate; and 5% by weight of zinc oxide Example 3 31.3% by weight of guanidine nitrate; 54.2% by weight of ammonium nitrate; 9.5% by weight of potassium nitrate; and 5% by weight of polyvinyl alcohol Example 4 40% by weight of guanidine nitrate; 53.5% by weight of ammonium nitrate; 1.5% by weight of potassium nitrate; and 5% by weight of polyvinyl alcohol.

The most preferred formulations, based on the present evaluation, are those of Examples 3 and 4. However, it is contemplated that other formulations containing the described eutectic composition, together with one or both stabilizers and, optionally, a binder, such as a polyvinyl alcohol binder, will also prove to be of equivalent efficiency. Similarly, corresponding results are expected from the compositions in which the guanidine nitrate is replaced with a counterpart amount of aminoguanidine nitrate. Only the preferred embodiment of the invention and few examples of its versatility are shown and described in the present description. It will be understood that the invention is capable of being used in various other combinations and means, and that is capable of changes or modifications within the scope of the inventive concept as expressed herein. The additional objects and advantages of the present invention will become readily apparent to those skilled in the art, from the description. As will be understood, the invention is capable of other and different modalities, and its various details are capable of modifications in several obvious respects, all without departing from the invention. Accordingly, the drawings and description should be considered as illustrative in nature, and not as restrictive.

Claims (29)

1. CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following RELGVINDIC? CIQNES 1. A composition for generally a non-toxic, odorless and colorless substantially particle-free gas, characterized in that it comprises: a eutectic solution of ammonium nitrate and either aminoguanidine nitrate or guanidine nitrate, together with a minor amount of potassium nitrate, a polyvinyl alcohol binder and an optional amount of zinc oxide.
2. 2. The composition of claim 1, characterized in that the mixture comprises equal parts by weight of ammonium nitrate and either aminoguanidine nitrate or guanidine nitrate.
3. 3. The composition according to claim 1, characterized in that the mixture comprises 40% to 60% by weight of ammonium nitrate and 40% to 60% by weight of either aminoguanidine nitrate or guanidine nitrate.
4. 4. The composition according to claim 1, characterized in that the amount of potassium nitrate present is up to 10% by weight.
5. 5. The composition according to claim 4, characterized in that the amount of potassium nitrate is present in the range of about 1 to about 2% by weight. ,
6. 6. A eutectic solution characterized in that it consists of ammonium nitrate and either aminoguanidine nitrate or guanidine nitrate.
7. 7. The eutectic solution according to claim 1, characterized in that it is in the form of a pressed granulate, which is resistant to rupture, when subjected to the temperature cycle.
8. 8. A method for generating a particle-free, non-toxic, odorless and colorless gas, characterized in that it comprises the steps of: a) providing a closed pressure chamber, having an exit door, b) placing inside the chamber, a solid eutectic solution, comprising ammonium nitrate and either aminoguanidine nitrate or guanidine nitrate, and c) providing means for burning the eutectic solution with detection of the pressure chamber subjected to a sudden deceleration, where the gas is generated instantaneously and driven through the exit door of the pressure chamber.
9. 9. The method in accordance with the claim 8, characterized in that it is driven in a motor vehicle equipped with at least one air bag, wherein the generated gas, conducted through the outlet door, subsequently enters the air bag, which is inflated instantaneously.
10. 10. The method of compliance with the claim 9, characterized in that the eutectic solution also includes an amount of potassium nitrate of up to 10% by weight.
11. The method according to claim 10, characterized in that the potassium nitrate is present in the range from about 1 to about 2% by weight.
12. 12. The method according to claim 11, characterized in that the eutectic solution is present in the form of a pressed granulate, which is resistant to rupture, when subjected to the temperature cycle.
13. 13. The method according to the claim 8, characterized in that the means for burning the propellant eutectic solution comprises an effective amount of a eutectic solution of essentially the same components.
14. 14. The method according to the claim 9, characterized in that the means for burning the propellant eutectic solution comprises an effective amount of a eutectic solution of essentially the same components.
15. 15. The method in accordance with the claim 10, characterized in that the means for burning the eutectic propellant solution comprises an effective amount of a eutectic solution of essentially the same components.
16. 16. The method of compliance with the claim 11, characterized in that the means for burning the propellant eutectic solution comprises an effective amount of a eutectic solution of essentially the same components.
17. 17. The composition according to claim 1, characterized in that it also includes up to 5% by weight of zinc oxide.
18. 18. The composition according to claim 4, characterized in that it also includes up to 5% by weight of zinc oxide.
19. 19. The method according to claim 10, characterized in that up to 5% by weight of zinc oxide is also present in the composition.
20. The composition according to claim 1, characterized in that it comprises equal parts of guanidine nitrate and ammonium nitrate and equal parts of potassium nitrate and zinc oxide.
21. 21. A composition for generating a particle-free, non-toxic, odorless and colorless gas, characterized in that it consists of a eutectic solution of: a) 47% by weight of guanidine nitrate; b) 47% by weight of ammonium nitrate; c) 3% by weight of potassium nitrate; and d) 3% by weight of zinc oxide.
22. 22. A composition for generating a particle-free, non-toxic, odorless and colorless gas, characterized in that it consists of a eutectic solution of: a) 47.5 wt% guanidine nitrate; b) 47.5% by weight of ammonium nitrate; and (c) 5% by weight of syn. oxide.
23. 23. The composition according to claim 1, characterized in that it consists of: a) 31.3% by weight of guanidine nitrate; b) 54.2% by weight of ammonium nitrate; and C f 9.5% by weight of potassium nitrate; and d) 5% by weight of polyvinyl alcohol.
24. 24. The composition according to claim 1, characterized in that it consists of: a) 40% by weight of guanidine nitrate; b) 53.5% by weight of ammonium nitrate; c) 1.5% by weight of potassium nitrate; and d) 5% by weight of polyvinyl alcohol.
25. 25. The method according to claim 10, characterized in that it also includes a polyvinyl alcohol binder and up to 5% by weight of zinc oxide.
26. 26. The method according to claim 1, characterized in that the composition consists of: a) 47% by weight of guanidine nitrate; b) 47% by weight of ammonium nitrate; c) 3% by weight of potassium nitrate; and d) 3% by weight of zinc oxide.
27. 27. The method according to claim, characterized in that the composition consists of: a) 47.5% by weight of guanidine nitrate; b) 47.5% by weight of ammonium nitrate; and c) 5% by weight of zinc oxide.
28. 28. The method according to claim -s 0, characterized in that the composition consists of: a) 31.3% by weight of guanidine nitrate; b) 54.2% by weight of ammonium nitrate; c) 9.5% by weight of potassium nitrate; and d) 5% by weight of polyvinyl alcohol.
29. 29. The method according to claim 0, characterized in that the composition consists of: a) 40% by weight of guanidine nitrate; b) 53.5% by weight of ammonium nitrate; c) 1.5% by weight of potassium nitrate; and d) 5% by weight of polyvinyl alcohol.