U.S. patent application number 11/561128 was filed with the patent office on 2007-05-10 for gas-producing mixtures.
This patent application is currently assigned to DELPHI TECHNOLOGIES, INC.. Invention is credited to Ulrich Bley, Klaus Redecker, Waldemar Weuter.
Application Number | 20070102076 11/561128 |
Document ID | / |
Family ID | 7754364 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070102076 |
Kind Code |
A1 |
Redecker; Klaus ; et
al. |
May 10, 2007 |
Gas-producing mixtures
Abstract
The subject of the present invention is gas-producing agents for
gas generators which contain, as nitrogen-containing compound
(fuel), a compound from the group tetrazole, triazole, triazine,
cyanic acid, urea, their derivatives or salts thereof, as oxidants,
compounds from the group of the peroxides, nitrates, chlorates or
perchlorates, and also combustion moderators which are capable of
influencing, by heterogeneous or homogeneous catalysis, the
combustion and its rate, as well as, optionally, additions capable
of affecting the proportion of the toxic gases.
Inventors: |
Redecker; Klaus; (Nurnberg,
DE) ; Weuter; Waldemar; (Nurnberg, DE) ; Bley;
Ulrich; (Furth, DE) |
Correspondence
Address: |
DELPHI TECHNOLOGIES, INC.
M/C 480-410-202
PO BOX 5052
TROY
MI
48007
US
|
Assignee: |
DELPHI TECHNOLOGIES, INC.
5725 Delphi Drive
Troy
MI
48007
|
Family ID: |
7754364 |
Appl. No.: |
11/561128 |
Filed: |
November 17, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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08894351 |
Oct 27, 1997 |
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PCT/EP96/00605 |
Feb 13, 1996 |
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11561128 |
Nov 17, 2006 |
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Current U.S.
Class: |
149/36 |
Current CPC
Class: |
C06B 43/00 20130101;
C06D 5/06 20130101 |
Class at
Publication: |
149/036 |
International
Class: |
C06B 47/08 20060101
C06B047/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 1995 |
DE |
19505 568.3 |
Claims
1. Gas-producing composition for gas generators, wherein said gas
producing composition comprises: a fuel; an oxidant; a combustion
moderator; and an additive capable of reducing nitrogen oxides
and/or carbon monoxide, the additive selected from the group
consisting of urea, urea derivatives, ferrocene, ferrocene
derivatives, or sulphur.
2. The gas-producing composition of claim 1 wherein the additive is
urea or a derivative thereof.
3. The gas-producing composition of claim 1 wherein the additive is
ferrocene or a derivative thereof.
4. The gas-producing composition of claim 1 wherein the additive is
sulphur.
5. The gas-producing composition of claim 1 wherein the fuel
includes at least one nitrogen-containing compound selected from
the group consisting of tetrazole, triazole, triazine, cyanic acid,
urea, or their derivatives or their salts, and wherein the additive
and the fuel are not the same.
6. The gas-producing composition of claim 1 wherein the oxidant
includes a combination of zinc peroxide, potassium perchlorate, and
at least one nitrate.
7. The gas-producing composition of claim 1 wherein the combustion
moderator is selected from the group consisting of metals, metal
oxides, metal carbonates, metal sulphides, or mixtures thereof.
8. The gas-producing composition of claim 1 wherein the combustion
moderator is present in an amount up to 8%.
9. Gas-producing composition for gas generators, wherein said gas
producing composition comprises: a fuel; an oxidant including a
combination of zinc peroxide, potassium perchlorate, and at least
one nitrate; and an additive capable of reducing nitrogen oxides
and/or carbon monoxide, the additive selected from the group
consisting of urea, urea derivatives, ferrocene, ferrocene
derivatives, sulphur, or metal sulphides.
10. The gas-producing composition of claim 9 wherein the additive
is urea or a derivative thereof.
11. The gas-producing composition of claim 9 wherein the additive
is ferrocene or a derivative thereof.
12. The gas-producing composition of claim 9 wherein the additive
is sulphur or a metal sulphide.
13. The gas-producing composition of claim 9 wherein the fuel
includes at least one nitrogen-containing compound selected from
the group consisting of tetrazole, triazole, triazine, cyanic acid,
urea, or their derivatives or their salts, and wherein the additive
and the fuel are not the same.
14. The gas-producing composition of claim 9 further including a
combustion moderator selected from the group consisting of metals,
metal oxides, metal carbonates, metal sulphides, or mixtures
thereof.
15. The gas-producing composition of claim 14 wherein the
combustion moderator is present in an amount up to 8%.
16. The gas-producing composition of claim 14 wherein the fuel
includes at least one nitrogen-containing compound selected from
the group consisting of tetrazole, triazole, triazine, cyanic acid,
urea, or their derivatives or their salts, and wherein the additive
and the fuel are not the same.
17. A method for reducing nitrogen oxides and/or carbon monoxide in
gas mixtures from pyrotechnic reactions, comprising: carrying out a
pyrotechnic reaction of a gas generating substance to generate a
gas mixture, the gas generating substance including a fuel, an
oxidizer, and an additive capable of reducing nitrogen oxides
and/or carbon monoxide, the additive selected from the group
consisting of urea, urea derivatives, ferrocene, ferrocene
derivatives, or sulphur; vaporizing the additive by heat released
in the pyrotechnic reaction; and converting nitrogen oxides and/or
carbon monoxide in the gas mixture to non-toxic compounds in a gas
phase reaction by reaction with the vaporized additive.
18. The method of claim 17 wherein the additive is urea or a
derivative thereof.
19. The method of claim 17 wherein the additive is ferrocene or a
derivative thereof.
20. The method of claim 17 wherein the additive is sulphur.
21. The method of claim 17 wherein the fuel includes at least one
nitrogen-containing compound selected from the group consisting of
tetrazole, triazole, triazine, cyanic acid, urea, or their
derivatives or their salts, and wherein the additive and the fuel
are not the same.
22. The method of claim 17 wherein the oxidant includes a
combination of zinc peroxide, potassium perchlorate, and at least
one nitrate.
23. The method of claim 17 wherein the combustion moderator is
selected from the group consisting of metals, metal oxides, metal
carbonates, metal sulphides, or mixtures thereof.
24. The method of claim 17 wherein the combustion moderator is
present in an amount up to 8%.
25. A method for reducing nitrogen oxides and/or carbon monoxide in
gas mixtures from pyrotechnic reactions, comprising: carrying out a
pyrotechnic reaction of a gas generating substance to generate a
gas mixture, the gas generating substance including a fuel, an
oxidant including a combination of zinc peroxide, potassium
perchlorate, and at least one nitrate, a combustion moderator, and
an additive capable of reducing nitrogen oxides and/or carbon
monoxide, the additive selected from the group consisting of urea,
urea derivatives, ferrocene, ferrocene derivatives, sulphur, or
metal sulphides; vaporizing the additive by heat released in the
pyrotechnic reaction; and converting nitrogen oxides and/or carbon
monoxide in the gas mixture to non-toxic compounds in a gas phase
reaction by reaction with the vaporized additive.
26. The method of claim 25 wherein the additive is urea or a
derivative thereof.
27. The method of claim 25 wherein the additive is ferrocene or a
derivative thereof.
28. The method of claim 25 wherein the additive is sulphur or a
metal sulphide.
29. The method of claim 25 wherein the fuel includes at least one
nitrogen-containing compound selected from the group consisting of
tetrazole, triazole, triazine, cyanic acid, urea, or their
derivatives or their salts, and wherein the additive and the fuel
are not the same.
30. The method of claim 25 further including a combustion moderator
selected from the group consisting of metals, metal oxides, metal
carbonates, metal sulphides, or mixtures thereof.
31. The method of claim 30 wherein the combustion moderator is
present in an amount up to 8%.
32. The method of claim 30 wherein the fuel includes at least one
nitrogen-containing compound selected from the group consisting of
tetrazole, triazole, triazine, cyanic acid, urea, or their
derivatives or their salts, and wherein the additive and the fuel
are not the same.
33. Gas-producing composition for gas generators, wherein said
gas-producing composition comprises: a) as fuel, at least one
nitrogen-containing compound selected from the group consisting of
tetrazole, triazole, triazine, cyanic acid, urea, and their
derivatives or their salts; b) as oxidant, a combination of zinc
peroxide, potassium perchlorate and at least one nitrate.
34. Gas-producing composition according to claim 33, wherein said
nitrogen-containing compound is one or more tetrazole derivatives
of the formulae IA or IB: ##STR2## wherein R.sub.1 and R.sub.2 or
R.sub.3 are identical or different and are hydrogen, hydroxy,
amino, carboxy, an alkyl residue of 1-7 carbon atoms, an alkenyl
residue of 2-7 carbon atoms, an alkylamino residue of 1-10 carbon
atoms, an aryl residue, an arylamino residue, a substituted aryl
residue or a substituted arylamino residue, the substituted aryl
residue or substituted arylamino residue being substituted by one
or several substituents which are identical or different, and which
are selected from the group consisting of an amino group, a nitro
group and an alkyl group of 1-4 carbon atoms or a sodium, a
potassium or a guanidinium salt of said tetrazole or tetrazole
derivative.
35. Gas-producing composition according to claim 34, wherein
R.sub.1, is selected from the group consisting of hydrogen, amino,
hydroxy, carboxyl, a methyl, ethyl, propyl, isopropyl, butyl,
isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, methylamino,
ethylamino, dimethylamino, n-heptylamino, n-octylamino,
n-decylamino, tetrazole, phenylamino, phenyl, nitrophenyl, and
aminophenyl; and R.sub.2 or R.sub.3 is selected from the group
consisting of hydrogen, a methyl, ethyl, phenyl, nitrophenyl, and
aminophenyl radical.
36. Gas-producing composition according to claim 33, wherein the
nitrogen-containing compound is a tetrazole derivative selected
from the group consisting of 5-aminotetrazole; lithium, sodium,
potassium, zinc, magnesium, strontium or calcium
5-aminotetrazolate; 5-aminotetrazole nitrate, sulphate, or
perchlorate; 1-(4-aminophenyl)-tetrazole,
1-(4-nitrophenyl)-tetrazole, 1-methyl-5-dimethylaminotetrazole,
1-methyl-5-methylamino-tetrazole, 1-methyltetrazole,
1-phenyl-5-aminotetrazole, 1-phenyl-5-hydroxytetrazole,
1-phenyltetrazole, 2-ethyl-5-aminotetrazole,
2-methyl-5-aminotetrazole, 2-methyl-5-carboxyltetrazole,
2-methyl-5-methylaminotetrazole, 2-methyltetrazole,
2-phenyltetrazole, 5-(p-tolyl)tetrazole, 5-diallylaminotetrazole,
5-dimethylaminotetrazole, 5-ethylaminotetrazole,
5-hydroxytetrazole, 5-methyltetrazole, 5-methylaminotetrazole,
5-n-decylaminotetrazole, 5-n-heptylaminotetrazole,
5-n-octylaminotetrazole, 5-phenyltetrazole, 5-phenylaminotetrazole,
bis-(aminoguanidine)-azotetrazole and
diguanidinium-5,5'-azo-tetrazolate, 5,5'-bitetrazole and
5,5'-bi-1H-tetrazoleammonium compounds.
37. Gas-producing composition according to claim 33, wherein as
triazine derivatives, 1,3,5-triazine, as triazole derivatives,
1,2,4-triazole-5-one, 3-nitro-1,2,4-triazole-5-one, as cyanic acid
derivatives, sodium cyanate, cyanuric acid, cyanuric acid esters,
cyanuric acid amide (melamine), 1-cyanoguanidine, sodium
dicyanamide, disodium cyanamide, dicyanodiamidine nitrate,
dicyanodiamidine sulphate, and as urea derivatives biuret,
guanidine, nitroguanidine, guanidine nitrate, aminoguanidine,
aminoguanidine nitrate, thiourea, triaminoguanidine nitrate,
aminoguanidine hydrogen carbonate, azodicarbonamide, tetracene,
semicarbazide nitrate, urethanes, and ureides, and derivatives
thereof.
38. Gas-producing composition according to claim 33, wherein the
ratio of the oxidants in the gas-producing mixture is 1:2:10, with
a total content of 60% by wt.
39. Gas-producing composition according to claim 33, wherein the
ratio of the nitrogen-containing compound to the oxidants is
balanced such that on combustion of the gas-producing composition,
oxygen is formed in excess.
40. Gas-producing composition according to claim 33, wherein the
composition further contains a combustion moderator in an amount up
to 8%.
41. Gas-producing composition according to claim 33, wherein the
composition further contains a combustion moderator selected from
the group consisting of metals, metal oxides, metal carbonates,
metal sulphides, and mixtures thereof.
42. Gas-producing composition according to claim 33, wherein the
composition further contains a combustion moderator selected from
the group consisting of sulphur, ferrocene and its derivatives.
43. Gas-producing composition according to claim 33, wherein the
composition further contains an addition capable of reducing the
content of the noxious gases nitrogen oxides and/or carbon
monoxide.
44. Gas-producing composition according to claim 33, wherein said
gas-producing composition further comprises an additional substance
selected from the group consisting of combustion moderators, noble
metals, mixtures of these compounds, basically reacting substances
selected from the group consisting of oxides, hydroxides,
carbonates of alkali and alkaline earth metals, zinc, mixtures of
these compounds, urea, guanidine compounds having NH.sub.2 groups
selected from the group consisting of amidosulphonic acids, amido
complexes, amides, and mixtures of these compounds.
45. Gas-producing composition according to claim 33, wherein the
amount of additions is about 10% by wt. in the charge and up to 75%
by wt. in the outlet passages, the amounts being based on the gas
charge.
46. Gas-producing composition for gas generators comprising
nitrogen-containing compounds, wherein said gas-producing
composition comprises: a) as nitrogen-containing compound, a
combination of aminotetrazole and calcium, magnesium or zinc salts,
of aminotetrazole; b) as oxidant, at least three compounds selected
from the group consisting of peroxides, nitrates, chlorates and
perchlorates; and c) combustion moderators which are capable of
influencing combustion and its rate by heterogeneous or homogeneous
catalysis selected from the group consisting of zinc oxide and
carbonates of zinc and calcium.
47. Gas-producing composition for gas generators, comprising
nitrogen-containing compounds, wherein said gas-producing
composition comprises: a) as nitrogen-containing compound (fuel),
urea, its salts, its derivatives and their salts, biuret,
guanidine, nitroguanidine, guanidine nitrate, aminoguanidine,
aminoguanidine nitrate, thiourea, triaminoguanidine nitrate,
aminoguanidine hydrogen carbonate, azodicarbonamide,
dicyanodiamidine nitrate, dicyanodiamidine sulphate, tetracene
and/or semicarbazide nitrate, urethanes, ureides, and their
derivatives; b) as oxidants, at least two compounds from the group
of peroxides, nitrates, chlorates or perchlorates; c) combustion
moderators selected from the group consisting of zinc oxide and
carbonates of zinc and calcium, the combustion moderator being
capable of influencing the combustion and its rate by heterogeneous
or homogeneous catalysis.
48. Gas-producing composition according to claim 47, wherein as
oxidants: peroxides of alkali and alkaline earth metals, zinc
peroxide, and peroxodisulphates of the said elements and ammonium
peroxodisulphate, or mixtures of these compounds; ammonium nitrate,
nitrates of alkali and alkaline earth metals, in particular lithium
nitrate, or mixtures of these compounds; halogen oxycompounds of
alkali or alkaline earth metals or of ammonium, or mixtures of
these compounds, wherein the combustion moderator is present an
amount up to 8%.
49. Gas-producing composition according to claim 46, wherein as
oxidants: peroxides of alkali and alkaline earth metals, zinc
peroxide, and peroxodisulphates of the said elements and ammonium
peroxodisulphate, or mixtures of these compounds; ammonium nitrate,
nitrates of alkali and alkaline earth metals, in particular lithium
nitrate, or mixtures of these compounds; halogen oxycompounds of
alkali or alkaline earth metals or of ammonium, or mixtures of
these compounds, wherein the combustion moderator is present an
amount up to 8%.
50. The gas-producing composition according to claim 33, further
comprising additions which are capable of reducing the proportion
of toxic gases.
51. The gas-producing composition according to claim 34, wherein
said at least one nitrate is sodium nitrate or strontium
nitrate.
52. The gas-producing composition according to claim 41, wherein
the metals are selected from the group consisting of boron,
silicon, copper, iron, titanium, zinc and molybdenum.
53. The gas-producing composition according to claim 44, wherein
the noble metal is selected from the group consisting of palladium,
ruthenium, rhenium, platinum, rhodium and oxides of the noble
metals.
54. The gas-producing composition according to claim 46, wherein
the aminotetrazone and salts of aminotetrazole are a combination of
5-aminotetrazole and salts of 5-aminotetrazole.
55. The gas-producing composition of claim 33, wherein the at least
one nitrate is sodium nitrate or strontium nitrate.
Description
[0001] Gas generators are being used to an increasing extent, for
example in motor vehicles for life-saving purposes. The
gas-producing mixture usually contains sodium azide. Sodium azide
as such is poisonous, and it can readily react with heavy metals,
e.g. copper and lead, to form extremely dangerous and vigorously
reacting compounds. Special precautions must therefore be taken in
the production of the raw material and of the gas charge mixture,
in its processing and in quality control. For this reason the
disposal of the sodium azide, for example when exchanging defective
gas generators or when scrapping vehicles, also presents a
particular problem. Improper use must also be reliably
prevented.
[0002] There has been no lack of attempts to use other substances
in place of sodium azide. A common feature of all proposed
replacements for sodium azide is that they contain organic carbon
compounds, and as a rule also organic nitrogen compounds. EP 0 519
485 describes the use of tetrazole or a derivative or derivatives
of tetrazole, or the use of one or more compounds from the group
consisting of cyanic acid derivatives and their salts, one or more
compounds from the group consisting of triazine and triazine
derivatives, the use of urea, its salts, derivatives and salts of
these compounds: these compounds can also be present as mixtures.
Ammonium nitrate and nitrates of sodium, potassium, magnesium,
calcium and iron, and/or peroxides of zinc, calcium, strontium or
magnesium, can be used as oxidants. Other gas-producing components,
cooling agents, reducing agents, catalysts and/or porosity
producing agents can be added.
[0003] EP 0 438 851 describes a non-toxic, non-azide pyrotechnic
composition which is suitable for use in the production of
substantially non-toxic combustion products that include a gas in
order to fill an accident cushion. The composition includes a
mixture of at least one tetrazole or tetrazole compound containing
hydrogen in its molecule, at least one oxygen-containing oxidant
and at least one metal oxide selected from cobalt oxide, nickel
oxide, chromium oxide, aluminium oxide and boron oxide. In the
combustion a substantially non-toxic primary gas mixture and
filterable solids are produced. Aminotetrazole, together with
oxidants which can contain perchlorates as well as nitrates, is
employed, by way of example.
[0004] A similar formulation is disclosed in European patent EP 0
372 733: the use of tetrazoles and triazoles in mixtures with
ammonium perchlorate and alkali nitrate as oxidants, in combination
with an additive to control combustion.
[0005] PCT application WO 94/01381 describes a gas-producing agent
for airbags consisting of organic nitrocompounds and halogenates.
By halogenates are to be understood, for example, alkali metal
chlorates, bromates and their per-compounds. The following are
mentioned, inter alia, as combustion-controlling catalysts: oxides,
chlorides, carbonates, sulphonates of the 4th to 6th series of the
periodic classification.
[0006] When the above-mentioned gas charges undergo reaction to
inflate airbags for motor vehicle safety, proportions of toxic
gases such as, for example, carbon monoxide or nitrogen oxides can
be present besides non-toxic working gases such as nitrogen, carbon
dioxide and hydrogen. Limits such as, for example, the maximum
allowable concentration (MAC) in the workplace, are set having
regard to peak loads for these gases. Their formation is
thermodynamically and kinetically connected, and in the case of
carbon monoxide is controlled e.g. by the producer gas equilibrium.
It has further been found that mixtures which contain nitrogen- and
carbon-containing compounds and evolve small proportions of
NO.sub.x during combustion evolve large proportions of CO, and vice
versa. The establishment of these equilibria is temperature and
pressure-dependent. It is known that a sufficiently effective
influencing of the composition of the reaction gases towards the
formation of non-toxic products cannot be achieved solely by
physical measures, for example control of the reaction by pressure
and/or temperature.
[0007] Processes are known from the literature which have the
object of reducing these components of the reaction gases. Thus,
for example, the equilibrium can be displaced at the expense of
carbon monoxide formation by the formation of carbonates by the
addition of alkaline slag-forming agents to the gas charge. At the
same time nitrogen oxides are converted into nitrates or
nitrites.
[0008] However, these measures have the disadvantage that the yield
of gas is made substantially worse by the high proportion of slag.
In addition, the slag must be separated at some expense from the
gaseous constituents by filters or other retaining systems before
the working gases can be used, for example for the inflation of the
airbag.
[0009] While the use of nitrogen-free systems does lead to the
formation of nitrogen-free gases, this is at the expense of a lower
yield of gas. The reason for this is that, to displace the producer
gas equilibrium in the direction of CO.sub.2, an excess of
slag-forming oxygen-carrying agent must be used. Hence hybrid
systems have already been proposed in which the reactions described
above are brought about by compressed air instead of by
slag-forming oxidants. However, these concepts suffer from the
disadvantage of the high weight of the system and the need to
control or supplement the compressed air.
[0010] According to U.S. Pat. No. 3,910,595, to improve the yield
the gas forming in the reaction is passed through a venturi nozzle
so that ambient air can be drawn in to assist in the inflation of
the airbag. Here, however, it must be taken into account that this
ambient air greatly cools the hot gases. Particularly at low
ambient temperatures the resulting loss in volume for inflating the
gasbag must be compensated for by the pyrotechnic mixture. The
resulting increased proportion of toxic reaction gases in the
interior of the vehicle can no longer be sufficiently reduced by
dilution.
[0011] The present invention provides non-toxic, azide-free
mixtures for the production of gas by combustion. These
gas-producing mixtures can be used, inter alia, in safety devices,
for example in airbag systems for inflation of airbags in motor
vehicles and aircraft. However, they are also suitable for lifting
heavy loads by inflation of bags placed under them, or for
expulsion of e.g. fire extinguishing powder, or for other measures
where the performance of work requires rapid formation of
gases.
[0012] The mixtures in accordance with the invention contain:
[0013] a) as nitrogen-containing compound (fuel) at least one
compound from the group: tetrazole, triazole, triazine, cyanic
acid, urea, their derivatives or their salts; [0014] b) as oxidant,
at least three compounds from the group of the peroxides, nitrates,
chlorates or perchlorates; [0015] c) combustion moderators which
are capable of influencing the combustion and its rate by
heterogeneous or homogeneous catalysis; and optionally also [0016]
d) additions which are capable of reducing the proportion of the
toxic gases.
[0017] The mixtures in accordance with the invention are not toxic,
and in contrast to azide-containing mixtures are easy to handle.
They therefore require less outlay on safety in the production of
the raw materials and mixtures and in their shaping, storage or
disposal.
[0018] The nitrogen-containing compounds to be used according to
the invention are those which, in the mixture with oxidants, mainly
form in their thermal/chemical reaction CO.sub.2, N.sub.2, O.sub.2
and H.sub.2O, but do not evolve any gases such as CO or NO.sub.x in
concentrations that could endanger health.
[0019] The mixtures according to the invention preferably contain
as nitrogen-containing compounds (fuels) one or more tetrazole
derivatives of the formula: ##STR1## in which R.sub.1 and R.sub.2
or R.sub.3 can be the same or different, with either R.sub.2 or
R.sub.3 being present, and standing for hydrogen, hydroxy, amino,
carboxyl, an alkyl radical with 1 to 7 carbon atoms, an alkenyl
radical with 2 to 7 carbon atoms, an alkylamino radical with 1 to
10 carbon atoms, an aryl radical, optionally substituted with one
or more substituents which can be the same or different and are
selected from the amino group, the nitro group, alkyl radicals with
1 to 4 carbon atoms or an arylamino radical in which the aryl
radical can optionally be substituted, or the sodium, potassium and
guanidinium salts of the said tetrazole derivatives.
[0020] In these compounds:
[0021] R.sub.1 preferably stands for hydrogen, amino, hydroxy,
carboxyl, a methyl, ethyl, propyl or isopropyl, butyl, isobutyl or
tert-butyl, n-pentyl, n-hexyl, or n-heptyl radical, a methylamino,
ethylamino, dimethylamino, n-heptylamino, n-octylamino or
n-decylamino radical, a tetrazole radical, a phenylamino radical, a
phenyl, nitrophenyl or aminophenyl radical; and
[0022] R.sub.2 or R.sub.3 preferably stands for hydrogen, a methyl
or ethyl radical, a phenyl, nitrophenyl or aminophenyl radical.
[0023] Particularly preferred compounds are the tetrazole
derivatives 5-aminotetrazole, lithium, sodium, potassium, zinc,
magnesium, strontium or calcium 5-aminotetrazolate,
5-aminotetrazole nitrate, sulphate, perchlorate and similar
compounds, 1-(4-aminophenyl)-tetrazole,
1-(4-nitrophenyl)-tetrazole, 1-methyl-5-dimethylaminotetrazole,
1-methyl-5-methylaminotetrazole, 1-methyltetrazole,
1-phenyl-5-aminotetrazole, 1-phenyl-5-hydroxytetrazole,
1-phenyltetrazole, 2-ethyl-5-aminotetrazole,
2-methyl-5-aminotetrazole, 2-methyl-5-carboxytetrazole,
2-methyl-5-methylaminotetrazole, 2-methyltetrazole,
2-phenyltetrazole, 5-(p-tolyl)tetrazole, 5-diallylaminotetrazole,
5-dimethylaminotetrazole, 5-ethylaminotetrazole,
5-hydroxytetrazole, 5-methyltetrazole, 5-methylaminotetrazole,
5-n-decylaminotetrazole, 5-n-heptylaminotetrazole,
5-n-octylaminotetrazole, 5-phenyltetrazole, 5-phenylaminotetrazole
or bis-(aminoguanidine)-azotetrazole and
diguanidinium-5,5'-azotetrazolate, as well as 5,5'-bitetrazole and
its salts, such as the 5,5'-bi-1H-tetrazole ammonium compounds.
[0024] The mixtures may contain: as triazine derivatives,
1,3,5-triazine, as triazole derivatives, 1,2,4-triazole-5-one,
3-nitro-1,2,4-triazole-5-one, as cyanic acid derivatives, sodium
cyanate, cyanuric acid, cyanuric acid esters, cyanuric acid amide
(melamine), 1-cyanoguanidine, sodium dicyanamide, disodium
cyanamide, dicyanodiamidine nitrate, dicyanodiamidine sulphate, and
as urea derivatives biuret, guanidine, nitroguanidine, guanidine
nitrate, aminoguanidine, aminoguanidine nitrate, thiourea;
triaminoguanidine nitrate, aminoguanidine hydrogen carbonate,
azodicarbonamide, tetracene, semicarbazide nitrate, as well as
urethanes, ureides such as barbituric acid, and derivatives
thereof.
[0025] 5-aminotetrazole is used as a particularly preferred
component. When this component is used in the mixture the preferred
proportion is 10-40% by wt. As derivatives of 5-aminotetrazole, its
salts in which the acidic hydrogen atoms in 5-aminotetrazole are
replaced in salt-like manner by toxicologically acceptable elements
such as calcium, magnesium or zinc, are used. However, compounds in
which the cation is ammonium, guanidinium and its amino derivatives
can also be used.
[0026] Oxidants which may be used according to the invention are:
[0027] peroxides of alkali and alkaline earth metals, zinc
peroxide, and the peroxodisulphates of the said elements and
ammonium peroxodisulphate; [0028] ammonium nitrate, nitrates of
alkali and alkaline earth metals, in particular lithium, sodium or
potassium nitrate, and strontium nitrate; [0029] halogen
oxycompounds of the alkali or alkaline earth metals or of ammonium,
particularly preferably potassium perchlorate or ammonium
perchlorate.
[0030] The oxidants can be used singly or in mixtures. In order to
reduce the proportion of nitrogen oxides in the reaction mixture as
far as possible, it is advantageous to keep the proportion of
nitrate in the oxidant mixture as small as possible, since part of
the nitrate can undergo thermal decomposition.
[0031] A preferred combination of the oxidants consists of zinc
peroxide, potassium perchlorate and at least one nitrate,
preferably sodium nitrate or strontium nitrate, mixed in the ratio
1:2:10 and in a total amount of about 60% by wt. in the
gas-producing mixture. The chlorine-containing compounds then react
during the combustion to form harmless sodium/potassium chloride.
Ammonium perchlorate can also be considered as perchlorate, alone
or mixed with another halogen oxycompound, but an excess must be
avoided in order to prevent the formation of corrosive hydrochloric
acid. If ammonium perchlorate is used, the simultaneous presence of
zinc compounds is particularly advantageous, since the risk of
hydrochloric acid being formed can thereby be avoided. An excess of
sodium and potassium compounds is acceptable, since these compounds
react with the reaction gases to form harmless carbonates. The
partial or complete replacement of the alkali nitrate by strontium
nitrate leads to a marked reduction in the amount of slag.
[0032] The ratio of the nitrogen-containing compounds, for example
the tetrazoles and triazoles, to the oxidants in the mixture is
balanced so that, on combustion of the gas charge mixture, an
excess of oxygen is formed. This excess of oxygen displaces the
CO/CO.sub.2 equilibrium in the direction of carbon dioxide.
[0033] Substances or mixtures thereof which are capable by
heterogeneous or homogeneous catalysis of influencing the
combustion and its rate are used as combustion moderators.
Moderators which intervene in the reaction through heterogeneous
catalysis are metals, metal oxides and/or metal carbonates and/or
metal sulphides. Preferred metals to use are boron, silicon,
copper, iron, titanium, zinc or molybdenum. Calcium carbonate can
also be used. Mixtures of these moderators can likewise be
used.
[0034] Moderators which intervene in the reaction through
homogeneous catalysis are, for example, sulphur, boron, silicon or
ferrocene and its derivatives. These moderators are vapourized into
the vapour phase as a result of the temperatures occurring in the
reaction, and thus can intervene in the reaction either as such or
as after-products. The proportion of these substances in the
mixture can amount to up to about 8%
[0035] Furthermore the mixture according to the invention can
contain gas-producing additions which are capable of reducing the
proportion of the noxious gases such as nitrogen oxides and/or
carbon monoxide. The proportion of these noxious gases in the gas
mixture produced is determined by [0036] the stoichiometric
composition of the mixture, [0037] the temperature and pressure of
the reaction, [0038] additives for influencing the reaction or the
after-reaction, and by the [0039] design of the generator in which
the reaction takes place.
[0040] While in a closed system, such as, for example, a pressure
bomb, it is relatively easy to reach the composition of the gas
mixture which approximates to the thermodynamic calculations, this
can no longer be achieved under the actual operating conditions in
the generator, since during the few milliseconds duration of the
reaction the equilibrium cannot be established. According to the
invention, therefore, suitable substances which can bring about a
catalytic effect are introduced into the mixture or into the region
of the outflowing gases. For this purpose the combustion moderators
described above and oxides of precious metals can be used. Further
possibilities consist in the use of noble metals such as palladium,
ruthenium, rhenium, platinum or rhodium, which employ the excess
oxygen in the reaction gases in a subsequent reaction to convert
the carbon monoxide. A preferred mode of use contemplates applying
the additive materials on ceramic or electrodepositing them on
metal grids as a support. Using this method it is possible in
particular to reduce the proportion of carbon monoxide in the gas
mixture.
[0041] To reduce the proportion of NO.sub.x, additional substances
are used whose chemical properties catalyse in particular the
conversion of nitrogen oxides, for example nitrogen dioxide, to
nitrates or nitrites. In principle, all more or less strongly
basically reacting substances are suitable.
[0042] These include, for example, oxides, hydroxides or carbonates
of non-toxic elements such as, for example, those of the alkali and
alkaline earth metals, those of zinc, and mixtures of these
compounds. When these compounds are used, nitrates and nitrites of
the elements are mainly formed. Further suitable materials for
reaction with NO.sub.2 are urea, guanidine and its derivatives,
compounds having NH.sub.2 groups, such as, for example,
amidosulphonic acids, amido complexes and the like, and amides. A
particularly preferred embodiment contemplates the use of peroxides
in the outlet openings of the generator. A particular advantage of
this is that, beside the reduction of the nitrogen oxides by the
reaction described above, oxygen is also formed for the following
catalytic reaction with carbon monoxide.
[0043] The additions according to the invention, either alone or
together, can either be introduced directly into the gas-producing
charge or be placed in the outflow passages of the generator. For
use in the outlet passages of the generator the additions are
suitably used in a compacted form, for example in the form of
tablets, pellets or granules. The quantity of the additions used in
the charge amounts to about 10% by wt. In the outlet channels the
quantity of the additions can be as much as 75% by wt., based on
the gas charge.
[0044] A reduction in the CO content can surprisingly also be
achieved if part of the fuel consists of the salts, particularly
the calcium, magnesium or zinc salts, of the aminotetrazole,
preferably of the corresponding salts of 5-aminotetrazole, or of
urea derivatives. In these cases it suffices to use only two
oxidants.
[0045] To influence the rate and temperature of reaction further
additives can be added. Such additives can for example be boron or
metal powders, for example titanium, aluminium, zirconium, iron,
copper, molybdenum, as well as their stable hydrides. Their
proportion in the additions is of the order of 5% by wt.
[0046] The production of the gas charge mixtures according to the
invention is carried out in known manner. For example, the
components are mixed dry, sieved, divided into portions and pressed
to tablets. The adjustment of the rate of combustion can be
achieved through the shape and size of the grains of the bulk
material obtained by breaking and sieving out the fragments. The
bulk material can be produced in large quantities and adapted to
meet particular combustion requirements by mixing fractions with
different dynamic liveliness. To improve the safety or improve the
results of mixing, premixtures of 2 or 3 components can also be
used. A mixture of oxidant and additions may, for example, be made
before it comes into contact with the nitrogen-containing
compounds.
[0047] However, the mixture can also be produced by kneading
water-moistened components, followed by granulating, e.g. by
passage through sieves, extrusion or the like. In this case
binders, for example waterglass, "inorganic rubber" (phosphorus
chloronitrile) or even small proportions of organic binders such as
acrylic resin, PTFE, or guar gum, can be used. Since the components
employed are neither toxic nor particularly reactive, and can only
be caused to react in the enclosed space with the aid of special
igniters, no special safety precautions are necessary.
[0048] The bulk material thus obtained can be used directly. To
avoid abrasion of the loose material in contact with the
generators, which would lead to changes in the combustion
characteristics and would represent a safety risk through its
vigorous combustion, the bulk material can be surface-coated. This
can be done through a varnish coating, which can optionally be
provided with ignition-promoting additions to assist in the
ignition. Ignition-promoting additions that come into consideration
are oxidants such as zinc peroxide and metal powders such as
titanium and zirconium. The application can be effected by
spraying-on the solvent-containing coating agent, e.g. in a drum
while evaporating off the solvent.
[0049] For special fields of application porous grain structures in
the grains can be used. The production of such porous structures
can be effected by conventional methods, for example by adding
soluble salts and subsequently dissolving them out with suitable
solvents or by addition of thermally decomposable substances such
as, for example, ammonium bicarbonate, acetone dicarboxylic acid,
blowing agents, peroxides or azo-bisisobutyronitrile, which can
then be removed again in a subsequent process step by heating and
tempering at elevated temperature. The characteristic is determined
by quantity, grain size and distribution. Such gas charges can, for
example, be used where gas charges which react in a strongly
progressive manner are required.
[0050] The ignition of the tailor-made gas charge can be effected
by the conventional methods. In doing so it is important that no
additional toxic reaction gas components are set free from the
igniter after the reaction.
[0051] The gas charge mixture is insensitive in respect of its
safety characteristics, for example to the effects of abrasion,
shock and impact or to ignitability by flame or cerium/iron sparks
under normal pressure. In an enclosure, however it burns vigorously
when suitably ignited. This provides increased safety in
manufacture and handling.
[0052] The mixtures according to the invention can, for example, be
used in gas generators for motor vehicle safety with the
electrically initiated ignition systems conventionally employed
there.
[0053] In contrast to generators based on an azide charge,
expensive filtering of the slag can be dispensed with, since the
slag contains no toxic constituents. It consists mainly of
carbonates and chlorides of potassium and sodium, along with very
little nitrates/nitrites and zinc oxide. The discharge of such
non-toxic constituents is therefore generally only limited by the
limits set for the emission of dust.
[0054] The following examples are intended to explain the invention
in more detail, but without limiting it.
[0055] The specified components for the gas charges according to
the invention are homogenised for 30 minutes in the stated
proportions by weight in plastic containers in an eccentric
tumbling mixer. Tabletting of the mixtures to blanks with a
diameter of about 6 mm is then effected. 3.5 g of the tabletted
samples are caused to react using 0.2 g boron/potassium nitrate
(25:75 parts by wt.) as an igniting mixture and an electrically
heatable iron wire in a 25 ml stainless steel pressure bomb. The
pressure-time curve of the reaction is recorded using a
piezoelectric measuring device. Combustion gases which are composed
mainly of H.sub.2O, CO.sub.2, N.sub.2 and O.sub.2 and meet the
toxicological requirements set are formed in the exothermic
reaction.
[0056] The gas charge mixtures described in the examples are
investigated, for example in a measuring apparatus comprising a
combustion chamber, gas flow diversion and filter chamber, using
specific mechanical constructional conditions, to determine its
combustion characteristics. The gaseous reaction products are
collected and characterised in a 60 l volume vessel (main
constituents: H.sub.2O, CO.sub.2, N.sub.2 and O.sub.2).
TABLE-US-00001 Composition (wt. %) Example No. 1 2 3 4 5
5-aminotetrazole 33.1 33.1 34.0 33.1 34.2 sodium nitrate 52.3 52.3
61.5 52.3 64.8 potassium 10.1 10.1 -- 10.1 -- perchlorate zinc
oxide 4.0 3.0 1.0 -- -- zinc peroxide -- 1.0 3.0 4.0 -- graphite
0.5 0.5 0.5 0.5 1.0 Heat of Friction Impact explosion sensitivity
sensitivity Example (kJ/g) (N) (J) 1 3.61 >360 10 2 3.69 >360
10 3 3.70 >360 10 4 3.82 >360 7.5 5 3.82 >360 10 Results
of measurements in the ballistic pressure bomb Time Maximum
difference.sup.1) pressure 40-60% p(max) Cold gas.sup.2) CO Example
(bar) (ms) (l/g) (ppm) 1 715 6.7 0.41 1800 2 707 5.9 0.38 1100 3
729 6.1 0.41 2000 4 660 6.5 0.40 1800 5 730 6.7 0.41 3300
.sup.1)duration of the reaction at between 40 and 60% of the
maximum pressure, in milliseconds .sup.2)measured after cooling to
room temperature.
[0057] Example 1 describes the reaction of 5-aminotetrazole (5-ATZ)
with a binary mixture of oxidants. The reaction gas composition
shows a content of 1800 ppm CO in the reaction gases after
combustion in a closed pressure bomb. In Example 2 the addition of
only 1% by wt. of zinc peroxide surprisingly leads to a marked
reduction in the proportion of CO to 1100 ppm with otherwise
unchanged test parameters. The changes in the composition of the
mixtures in Examples 3 to 5 lead to poorer results. TABLE-US-00002
Composition (wt. %) Example No. 6 (=1) 7 8 9 5-aminotetrazole 33.1
25.4 16.6 10.7 sodium nitrate 52.3 52.7 52.7 52.7 potassium
perchlorate 10.1 10.2 10.2 10.2 Zn (5-ATZ).sub.2 -- 11.2 -- -- Ca
(5-ATZ).sub.2 -- -- 20.0 -- Mg (5-ATZ).sub.2 -- -- -- 25.9 zinc
oxide 4.0 -- -- -- graphite 0.5 0.5 0.5 0.5 Heat of Friction Impact
explosion sensitivity sensitivity Example (kJ/g) (N) (J) 6 (=)1
3.61 >360 10 7 3.64 >360 10 8 3.46 >360 15 9 2.74 >360
20 Results of measurements in the ballistic pressure bomb (25 ml):
Time Maximum difference.sup.1) pressure 40-60% p(max) Cold
gas.sup.2) CO Example (bar) (ms) (l/g) (ppm) 6 (=1) 715 6.7 0.41
1800 7 662 6.8 0.39 250 8 602 6.6 0.40 140 9 81 39.2 0.33 100
Results of measurements in the 60 l test canister: Example CO
reduction.sup.3) (%) Maximum pressure.sup.4) (bar) 6 (=1) 0 2.2 7
10 2.1 8 40 1.7 9 95 <1.5 .sup.1)duration of the reaction
between 40 and 60% of the maximum pressure in milliseconds
.sup.2)measured after cooling to room temperature .sup.3)based on
the test canister results, Example 1 or 6 .sup.4)mass of charge 40
g.
[0058] Examples 6 to 9 show that the addition of the Zn, Ca and Mg
salts of 5-aminotetrazole (Me(5-ATZ).sub.2) has a favourable effect
on the reaction gas composition. A marked reduction is found in the
proportion of CO. The rate of reaction is also affected.
TABLE-US-00003 Composition (wt. %) Example No. 10 11 12 13
5-aminotetrazole 33.0 31.6 30.8 28.9 guanidine nitrate 8.3 8.0 7.8
7.3 sodium nitrate 53.2 39.0 27.1 -- strontium nitrate -- 20.9 33.8
63.3 graphite 0.5 0.5 0.5 0.5 Heat of Friction Impact Mass of
explosion sensitivity sensitivity residue.sup.3) Example (kJ/g) (N)
(J) (g) 10 4.06 >360 20 1.5 11 3.90 >360 15 1.2 12 3.61
>360 20 1.0 13 3.41 >360 15 0.8 Results of measurements in
the ballistic pressure bomb (25 ml): Time Maximum difference.sup.1)
pressure 40-60% p(max) Cold gas.sup.2) Example (bar) (ms) (l/g) 10
779 6.1 0.46 11 767 7.0 0.41 12 723 7.3 0.42 13 620 8.6 0.39
.sup.1)duration of reaction at between 40 and 60% of the maximum
pressure, in milliseconds .sup.2)measured after cooling to room
temperature .sup.3)mass of solids in the 60 l test canister after
combustion of 30 g gas charge in the experimental generator.
[0059] Examples 10 to 13 differ in the proportion of sodium
nitrate/strontium nitrate used as oxidant. With increasing
proportions of strontium nitrate, the mass of the slag emerging
into the canister decreases. This means that the filterability of
the slag is improved by the addition of strontium nitrate--after
the reaction--to the filter of the generator. At the same time the
proportion of CO in the reaction gas can be favourably
influenced.
* * * * *