Patent US5019220A successfully refreshed from Google Patents.
US5019220A
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US
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Process for making an enhanced thermal and ignition stability azide gas generant
Assignee: Autoliv ASP Inc
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Filing: 1990-08-06
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Granted: 1991-05-28
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Expires: 2010-08-06
Abstract
Abstract Multiple processes and apparatuses for improving the prior system of making gas generant pellets or tablets made of sodium azide, molybdenum disulfide and sulfur wherein powdered ingredients thereof are slurried in water, subjected to wet grinding, spray dried to a powdered material which is molded into pellets or tablets which find use in vehicle crash bags or inflators. The first improvement to the old process and apparatus involves adjusting the basicity of the water to a pH of greater than 8.0 up to about 12.5 via the addition of sodium hydroxide, followed by the addition of sulfur and molybdenum disulfide and finally the sodium azide whereby azide addition is made to a basic mixture of the other ingredients thereby keeping hydrazoic acid concentration levels below about 3×10EXP(-3) moles per liter. The second improvement to the old process and apparatus involves (1) softening the water before its use in slurrying the powdered ingredients to remove undesirable Ca and Mg ions and/or (2) adding sodium sulfide and/or tri-sodium phosphate to the slurry to precipitate any remaining undesirable Ca, Mg, Pb, Fe, Mn and Cu ions as non-hazardous compounds. Each of these metal ions is reduced to no more about 25 ppm or less. Also these two improvements are joined together to form a system wherein even better safety results occur. The improvements not only extend to the final product produced, but to the intermediates at the slurry stage as well as at the spray dried state, which products differ due to significant elimination or minimization of hydrazoic acid and other contaminant metal ion species above mentioned.
Inventors
- 👤 Robert D. Taylor
- 👤 Gary L. Smith
- 👤 Ritchie Olsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:55
CPC Classifications
C; C06; C06B; C06B35/00; C06D; C06D5/00; C06D5/06
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
119 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement wherein the order of addition of the ingredients in the slurry stage comprises first adding a base to the water to adjust the pH to be within the range of greater than 8.0 up to about 12.5, then adding said oxidant/reactant and finally the azide whereby the azide addition is made to a basic mixture of the other ingredients thus prohibiting the formation of hydrazoic acid at hazardous concentration levels.
Claim 2
Dependent Claim
119 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement wherein the order of addition of the ingredients in the slurry stage comprises first adding a base to the water to adjust the pH to be within the range of greater than 8.0 up to about 12.5, then adding said oxidant/reactant and finally the azide whereby the azide addition is made to a basic mixture of the other ingredients thus prohibiting the formation of hydrazoic acid at hazardous concentration levels.
Claim 3
Dependent Claim
20 words
The process according to claim 1 wherein said pH is adjusted to the range of about 9.0 to about 11.0.
Claim 4
Dependent Claim
17 words
The process according to claim 2 wherein the base added to adjust the pH is sodium hydroxide.
Claim 5
Dependent Claim
14 words
The process according to claim 2 wherein said pH is adjusted to about 10.0.
Claim 6
Dependent Claim
17 words
The process according to claim 4 wherein the base added to adjust the pH is sodium hydroxide.
Claim 7
Dependent Claim
12 words
The process according to claim 1 wherein said base is sodium hydroxide.
Claim 8
Dependent Claim
20 words
The process according to claim 1 wherein the hydrazoic acid concentration level is kept below about 3×10EXP(-3) moles per liter.
Claim 9
Dependent Claim
20 words
The process according to claim 7 wherein the hydrazoic acid concentration level is kept below about 3×10EXP(-5) moles per liter.
Claim 10
Dependent Claim
15 words
The process according to claim 1 wherein the generant azide is an alkali metal azide.
Claim 11
Dependent Claim
12 words
The process according to claim 9 wherein said alkali metal is sodium.
Claim 12
Dependent Claim
13 words
The process according to claim 1 wherein the reactant/ oxidizer includes molybdenum disulfide.
Claim 13
Dependent Claim
13 words
The process according to claim 11 wherein the reactant/ oxidizer further includes sulfur.
Claim 14
Dependent Claim
109 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm thus prohibiting the formation of their corresponding unstable azide compounds in hazardous quantities.
Claim 15
Dependent Claim
109 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm thus prohibiting the formation of their corresponding unstable azide compounds in hazardous quantities.
Claim 16
Dependent Claim
25 words
The process according to claim 13 wherein the concentration level of each of said metal ions is kept to a range below about 15 ppm.
Claim 17
Dependent Claim
19 words
The process according to claim 14 wherein said concentration level is kept to a range below about 5 ppm.
Claim 18
Dependent Claim
36 words
The process according to claim 13 wherein the lowering or removing of said impurity metals is accomplished (a) before slurrying the generant raw materials and/or (b) selectively precipitating same as non-hazardous compounds in the slurry mix.
Claim 19
Dependent Claim
40 words
The process according to claim 16 wherein the lowering or removing of impurity metals under (a) is accomplished by supplying the oxidizer/reactant in purified condition and/or by treating said ingredient in situ or on line to remove the impurity metals.
Claim 20
Dependent Claim
25 words
The process according to claim 17 wherein the oxidizer/ reactant comprises molybdenum disulfide which is treated on line by chemical washing/leaching to remove impurity metals.
Claim 21
Dependent Claim
47 words
The process according to claim 16 wherein the impurity metal lowering or removal operation under (a) is performed by supplying the water in a pre-softened condition to the system and/or softening the water in situ or on line prior to being utilized to prepare the slurry mixture.
Claim 22
Dependent Claim
18 words
The process according to claim 19 wherein the slurry water supplied is softened in situ or on line.
Claim 23
Dependent Claim
19 words
The process according to claim 20 wherein the water is softened by a conventional ion exchange or zeolite-type system.
Claim 24
Dependent Claim
35 words
The process according to claim 16 wherein the precipitation operation under (b) is achieved (1) by the addition of small quantities of sodium sulfide, and/or tri-sodium phosphate, and/or (2) by the addition of sodium hydroxide.
Claim 25
Dependent Claim
31 words
The process according to claim 22 wherein sodium sulfide and/or tri-sodium phosphate is added in the form of their hydrates and in amounts up to about 1 wt. % of each.
Claim 26
Dependent Claim
25 words
The process according to claim 23 wherein said hydrated sulfide and/or phosphate is added in amounts of about 0.030 and about 0.050 wt. %, respectively.
Claim 27
Dependent Claim
15 words
The process according to claim 13 wherein the generant azide is an alkali metal azide.
Claim 28
Dependent Claim
11 words
The process according to claim 25 wherein said metal is sodium.
Claim 29
Dependent Claim
13 words
The process according to claim 13 wherein the reactant/ oxidizer includes molybdenum disulfide.
Claim 30
Dependent Claim
12 words
The process according to claim 27 wherein the reactant/oxidizer further includes sulfur.
Claim 31
Dependent Claim
184 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement (a) wherein the order of addition of the ingredients in the slurry stage comprises first adding a base to the water to adjust the pH to be within the range of greater than 8.0 up to about 12.5, then adding said oxidant/reactant and finally the azide so that the azide addition is made to a basic mixture of the other ingredients thus minimizing the formation of hydrazoic acid at hazardous concentration levels and (b) wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm thus avoiding the formation of the more unstable azide compounds therefrom in hazardous quantities.
Claim 32
Dependent Claim
184 words
In a process of making gas generant pellets or tablets wherein powdered ingredients of a generant azide and an oxidizer and/or reactant therefor are slurried in water, subjected to wet grinding, dried to a powder material which is then further processed to produce the pellets or tablets, the improvement (a) wherein the order of addition of the ingredients in the slurry stage comprises first adding a base to the water to adjust the pH to be within the range of greater than 8.0 up to about 12.5, then adding said oxidant/reactant and finally the azide so that the azide addition is made to a basic mixture of the other ingredients thus minimizing the formation of hydrazoic acid at hazardous concentration levels and (b) wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm thus avoiding the formation of the more unstable azide compounds therefrom in hazardous quantities.
Claim 33
Dependent Claim
20 words
The process according to claim 29 wherein said pH is adjusted to the range of about 9.0 to about 11.0.
Claim 34
Dependent Claim
17 words
The process according to claim 30 wherein the base added to adjust the pH is sodium hydroxide.
Claim 35
Dependent Claim
14 words
The process according to claim 30 wherein said pH is adjusted to about 10.0.
Claim 36
Dependent Claim
17 words
The process according to claim 32 wherein the base added to adjust the pH is sodium hydroxide.
Claim 37
Dependent Claim
12 words
The process according to claim 29 wherein said base is sodium hydroxide.
Claim 38
Dependent Claim
20 words
The process according to claim 29 wherein the hydrazoic acid concentration level is kept below about 3×10EXP(-3) moles per liter.
Claim 39
Dependent Claim
20 words
The process according to claim 35 wherein the hydrazoic acid concentration level is kept below about 3×10EXP(-5) moles per liter.
Claim 40
Dependent Claim
15 words
The process according to claim 29 wherein the generant azide is an alkali metal azide.
Claim 41
Dependent Claim
12 words
The process according to claim 37 wherein said alkali metal is sodium.
Claim 42
Dependent Claim
13 words
The process according to claim 29 wherein the reactant/ oxidizer includes molybdenum disulfide.
Claim 43
Dependent Claim
13 words
The process according to claim 39 wherein the reactant/ oxidizer further includes sulfur.
Claim 44
Dependent Claim
107 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement wherein sodium hydroxide is first added to the water to adjust the pH to a range of greater than 8 to about 12.5, then the sulfur and molybdenum disulfide are added, and finally the sodium azide whereby the azide addition is made to a basic mixture of the other ingredients thus prohibiting the formation of hydrazoic acid at hazardous concentration levels above about 3×10EXP(-3) moles per liter.
Claim 45
Dependent Claim
107 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement wherein sodium hydroxide is first added to the water to adjust the pH to a range of greater than 8 to about 12.5, then the sulfur and molybdenum disulfide are added, and finally the sodium azide whereby the azide addition is made to a basic mixture of the other ingredients thus prohibiting the formation of hydrazoic acid at hazardous concentration levels above about 3×10EXP(-3) moles per liter.
Claim 46
Dependent Claim
155 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm by (a) passing the water through a softening system before being used to slurry the ingredients to remove Ca and Mg, and/or (b) by adding sodium sulfide and/or tri-sodium phosphate and/or sodium hydroxide to the slurry to precipitate any remaining Ca, Mg, Pb, Fe, Mn and Cu ions as non-hazardous compounds thus avoiding the formation of the more unstable and dangerous azide compounds formable therefrom in hazardous amounts.
Claim 47
Dependent Claim
155 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement wherein the concentration level of impurity or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm by (a) passing the water through a softening system before being used to slurry the ingredients to remove Ca and Mg, and/or (b) by adding sodium sulfide and/or tri-sodium phosphate and/or sodium hydroxide to the slurry to precipitate any remaining Ca, Mg, Pb, Fe, Mn and Cu ions as non-hazardous compounds thus avoiding the formation of the more unstable and dangerous azide compounds formable therefrom in hazardous amounts.
Claim 48
Dependent Claim
226 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement (a) wherein sodium hydroxide is first added to the water to adjust the pH to a range of greater than 8 to about 12.5, then the sulfur and molybdenum disulfide are added, and finally the sodium azide so that the azide addition is made to a basic mixture of the other ingredients thus minimizing the formation of hydrazoic acid, and keeping said acid below about 3×10EXP(-3) moles per liter, and (b) wherein the concentration level of soluble or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm by (1) passing the water through a water softening system prior to being used to slurry in order to remove Ca and Mg ions, and/or adding (2) sodium sulfide and/or tri-sodium phosphate and/or sodium hydroxide to the slurry to precipitate any remaining Ca, Mg, Pb, Fe, Mn and Cu ions as non-hazardous compounds, thus avoiding the formation of the more unstable azide compounds formable therefrom in hazardous amounts.
Claim 49
Dependent Claim
226 words
In a process of making gas generant tablets wherein powdered ingredients of sodium azide, sulfur and molybdenum disulfide are slurried in water, subjected to wet grinding, spray dried to a powder material which is then molded into tablets, the improvement (a) wherein sodium hydroxide is first added to the water to adjust the pH to a range of greater than 8 to about 12.5, then the sulfur and molybdenum disulfide are added, and finally the sodium azide so that the azide addition is made to a basic mixture of the other ingredients thus minimizing the formation of hydrazoic acid, and keeping said acid below about 3×10EXP(-3) moles per liter, and (b) wherein the concentration level of soluble or contaminant metal ions selected from the group consisting of Ca, Mg, Pb, Fe, Mn, Cu and mixtures thereof inherent in the slurry mixture is minimized significantly by lowering or removing each of them to a range below about 25 ppm by (1) passing the water through a water softening system prior to being used to slurry in order to remove Ca and Mg ions, and/or adding (2) sodium sulfide and/or tri-sodium phosphate and/or sodium hydroxide to the slurry to precipitate any remaining Ca, Mg, Pb, Fe, Mn and Cu ions as non-hazardous compounds, thus avoiding the formation of the more unstable azide compounds formable therefrom in hazardous amounts.
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