U.S. patent application number 10/323929 was filed with the patent office on 2003-08-07 for propellant for gas generators.
Invention is credited to Redecker, Klaus, Weuter, Waldemar.
Application Number | 20030145923 10/323929 |
Document ID | / |
Family ID | 6434491 |
Filed Date | 2003-08-07 |
United States Patent
Application |
20030145923 |
Kind Code |
A1 |
Redecker, Klaus ; et
al. |
August 7, 2003 |
Propellant for gas generators
Abstract
A propellant for gas generators, especially for lifesaving
systems, contains one or several tetrazole derivative(s) or
respectively one or several compounds from the groups of (A) cyanic
acid derivatives and their salts, (B) triazine and triazine
derivatives, (C) urea, its salts, derivatives, and compounds
evolved therefrom and their salts, wherein the aforementioned
compounds can also be present as mixtures; and an oxidizing agent
from the group of peroxides of zinc, calcium, strontium or
magnesium or such peroxides with nitrates of ammonium, sodium,
potassium, magnesium, calcium and iron, wherein it is possible to
add further gas generating components, coolants, reducing agents,
catalysts and/or porosity-producing media.
Inventors: |
Redecker, Klaus; (Nurnberg,
DE) ; Weuter, Waldemar; (Nurnberg, DE) |
Correspondence
Address: |
ANTONELLI TERRY STOUT AND KRAUS
SUITE 1800
1300 NORTH SEVENTEENTH STREET
ARLINGTON
VA
22209
|
Family ID: |
6434491 |
Appl. No.: |
10/323929 |
Filed: |
December 20, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10323929 |
Dec 20, 2002 |
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09524563 |
Mar 13, 2000 |
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09524563 |
Mar 13, 2000 |
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08354745 |
Dec 8, 1994 |
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08354745 |
Dec 8, 1994 |
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07901698 |
Jun 22, 1992 |
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Current U.S.
Class: |
149/36 |
Current CPC
Class: |
C06D 5/06 20130101; C06B
43/00 20130101 |
Class at
Publication: |
149/36 |
International
Class: |
C06B 047/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 1991 |
DE |
P 41 20 599.5 |
Claims
1. A propellant composition for producing reaction products not
having toxic gases in health-endangering concentrations in gas
generators, the components of the composition consisting
essentially of: at least one nitrogen-containing compound selected
from the group consisting of (A) a cyanic acid derivative selected
from the group consisting of sodium cyanate, cyanuric acid,
1-cyanoguanidine, disodium cyanamide and a salt of disodium
cyanamide, (B) triazine or triazine derivative selected from the
group consisting of cyanuric acid ester, cyanuric acid amide, and a
salt of disodium cyanamide, and (C) urea, its salts and a urea
derivative selected from the group consisting of biuret, guanidine,
nitroguanidine, guanidine nitrate, aminoguanidine, aminoguanidine
nitrate, aminoguanidine hydrogen carbonate, azodicarboxylic acid
diamide, dicyandiamidine nitrate, dicyandiamidine sulfate,
tetrazene, and semicarbizide nitrate; and an oxidizing agent
comprising an inorganic peroxide or comprising a mixture of an
inorganic peroxide and a nitrate; wherein the reaction products of
the propellant composition do not contain toxic gases in
health-endangering concentrations.
2. A propellant composition according to claim 1, wherein the
reaction products of the propellant composition do not contain
toxic gases in excess of at least one of MAK and TLV values.
3. A propellant composition for producing reaction products not
having the toxic gases in health-endangering concentrations in gas
generators, the components of the composition consisting
essentially of: (1) at least one nitrogen-containing compound
selected from the group consisting of (a) tetrazole or a tetrazole
derivative of the formulae IA or IB: 3 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, and (b) at least one compound selected from the group
consisting of (A) a cyanic acid derivative selected from the group
consisting of sodium cyanate, cyanuric acid, 1-cyanoguanidine,
disodium cyanamide and a salt of disodium cyananide, (B) triazine
or triazine derivative selected from the group consisting of
cyanuric acid ester, cyanuric acid amide, and their salts, and (C)
urea, its salts and a urea derivative selected from the group
consisting of biuret, guanidine, nitroguanidine, guanidine nitrate,
aminoguanidine, aminoguanidine nitrate, aminoguanidine hydrogen
carbonate, azodicarboxylic acid diamide, dicyandiamidine nitrate,
dicyandiamidine sulfate, tetrazene, and semicarbizide nitrate; and
(2) an oxidizing agent comprising a peroxide or comprising a
mixture of a peroxide and a nitrate; wherein the reaction products
of the propellant composition do not contain toxic gases in
health-endangering concentrations.
4. A propellant composition according to claim 3, wherein the
reaction products of the propellant composition do not contain
toxic gases in excess of at least one of MAK and TLV values.
5. A propellant composition for producing reaction products not
having toxic gases in health-endangering concentrations in gas
generators, the components of the composition consisting
essentially of: (1) at least one nitrogen-containing compound
selected from the group consisting of (a) tetrazole or a tetrazole
derivative of the formulae 4 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, and
(b) at least one compound selected from the group consisting of (A)
a cyanic acid derivative selected from the group consisting of
sodium cyanate, cyanuric acid, 1-cyanoguanidine, disodium cyanamide
and a salt of disodium cyanamide, (B) triazine or triazine
derivative selected from the group consisting of cyanuric acid
ester, cyanuric acid amide and their salts, and (C) urea, its salts
and a urea derivative selected from the group consisting of biuret,
guanidine, nitroguanidine, guanidine nitrate, aminoguanidine,
aminoguanidine nitrate, aminoguanidine hydrogen carbonate,
azodicarboxylic acid diamide, dicyandiamidine nitrate,
dicyandiamidine sulfate, tetrazene, and semicarbizide nitrate; an
oxidizing agent comprising a peroxide or comprising a mixture of a
peroxide and a nitrate; and coolants, reducing agents and
catalysts; wherein the reaction products of the propellant
composition do not contain toxic gases in health-endangering
concentrations.
6. A propellant composition according to claim 5, wherein the
reaction products of the propellant composition do not contain
toxic gases in excess of at least one of MAK and TLV values.
7. A propellant composition for producing reaction products not
having toxic gases in health-endangering concentrations in gas
generators, the components of the composition consisting
essentially of: at least one nitrogen-containing compound selected
from the group consisting of (a) tetrazole or a tetrazole
derivative of the formulae IA or IB: 5 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, and (b) at least one compound selected from the group
consisting of (A) a cyanic acid derivative selected from the group
consisting of sodium cyanate, cyanuric acid, 1-cyanoguanidine,
disodium cyanamide and a salt of sodium cyanamide, (B) triazine or
triazine derivative selected from the group consisting of cyanuric
acid ester, cyanuric acid amide and their salts, and (C) urea, its
salts and a urea derivative selected from the group consisting of
biuret, guanidine, nitroguanidine, guanidine nitrate,
aminoguanidine, aminoguanidine nitrate, aminoguanidine hydrogen
carbonate, azodicarboxylic acid diamide, dicyandiamidine nitrate,
dicyan-diamidine sulfate, tetrazene, and semicarbizide nitrate; an
oxidizing agent comprising a peroxide or comprising a mixture of a
peroxide and a nitrate; and ferrocene as a catalyst; wherein the
reaction products of the propellant composition do not contain
toxic gases in health-endangering concentrations.
8. A propellant composition according to claim 7, wherein the
reaction products of the propellant composition do not contain
toxic gases in excess of at least one of MAK and TLV values.
9. A propellant composition for producing reaction products not
having toxic gases in health-endangering concentrations in gas
generators, the components of the composition consisting
essentially of: (1) at least one nitrogen-containing compound
selected from the group consisting of tetrazole or a tetrazole
derivative of the formulae IA or IB: 6 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, and (2) an oxidizing agent, wherein the oxidizing agent
is an inorganic peroxide or comprising a mixture of an inorganic
peroxide and a nitrate; wherein the reaction products of the
propellant composition do not contain toxic gases in
health-endangering concentrations.
10. A propellant composition according to claim 9, wherein the
reaction products of the propellant composition do not contain
toxic gases in excess of at least one of MAK and TLV values.
Description
BACKGROUND OF THE INVENTION
[0001] Gas generators have become of increasing interest for
lifesaving purposes, for example in vehicles. Worldwide, the most
popular mixture for gas generation contains sodium azide. However,
sodium azide is toxic, requiring special measures during the
manufacture of the raw material, during the preparation of the gas
charge composition, and during its processing, quality control, and
waste removal. This holds true, in particular, in connection with
the scrapping of vehicles.
[0002] There has been a large number of attempts to utilize
substances other than sodium azide. Thus, DE-A-2,142,578 describes
a press-molded propellant charge for the rapid inflation of a
hollow body by the reaction of tetrazylazene with oxygen carriers.
DE-A-1,806,550 proposes a propellant charge which generates
pressure gas, yielding cool gases, based on ammonium nitrate,
activated carbon, and a compound that is subject to endothermal
decomposition or sublimation. However, this system produces a large
proportion of steam, representing a drawback since water leads to a
strong increase in temperature due to its high heat of
condensation.
[0003] DE-A-1,222,418 discloses mixtures generating pressurized
gas, based on inorganic perchlorate oxidizers, polymeric fuel
binders, and a coolant. Preparations having high proportions of
chlorate or perchlorate, however, lead to chlorine components in
the reaction gases. Thus, EP-A-372,733 likewise yields an
unsatisfactory mixture inasmuch as the propellant charge for the
proposed airbag contains about 40% ammonium perchlorate. Even
nitrocellulose and nitroglycerin compositions can be found in the
literature. Such suggestions cannot be considered for use in
lifesaving systems. Nitrocellulose and nitroglycerin mixtures, or
also other energetic compounds rich in carbon must be eliminated on
account of carbon monoxide formation.
[0004] The propellant charges in DE-A-1,250,318, containing
aminotetrazole, potassium dichromate, calcium resinate, and
metallic silicon, do not meet up-to-date safety requirements,
either. The same holds true for DE-C-2,004,620 wherein the
compressed gas-producing charges contain azotetrazole and/or
ditetrazole and chlorates or perchlorates. The propellant charges
of U.S. Pat. No. 3,734,789 which contain 5-aminotetrazole nitrate
and polyisoprene birders, although burning up rapidly, also
generate carbon monoxide owing to the carbon-rich binder
proportion, in health-endangering concentrations.
SUMMARY OF THE INVENTION
[0005] Accordingly, the invention is based on the object of making
available gas compositions, the manufacture and processing and/or
handling of which are harmless and the reaction products of which
are nontoxic.
[0006] This object has been attained by a propellant or gas
generating composition for gas generators containing, as the
nitrogenous compound, (a) tetrazole or one or more tetrazble
derivative(s) of the following formula I 1
[0007] wherein R.sub.2 and R.sub.2 or R.sub.3 can be identical or
different (but either R.sub.2 or R.sub.3 is present) and can be:
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 optionally
substituted by one or several substituents which can be identical
or different, selected from the amino group, the nitro group, the
alkyl residues of 1-4 carbon atoms, or an arylamino residue wherein
the aryl residue can be optionally substituted, or their sodium,
potassium, and guanidinium salts, or containing, as the nitrogenous
compounds,
[0008] (b) respectively one or several compounds from the groups
of
[0009] (A) cyanic acid derivatives and their salts,
[0010] (B) triazine and triazine derivatives,
[0011] (C) urea, its salts, derivatives, and compounds evolved
therefrom and their salts,
[0012] wherein the compounds recited under (a) and (b) can also be
present as mixtures,
[0013] and containing an oxidizing agent from the group of the
peroxides, or from the group of the peroxides together with
oxidizing agents from the group of the nitrates.
DETAILED DESCRIPTION OF THE INVENTION
[0014] By the formula I, applicants are referring to tetrazole or
derivatives of tetrazole of either the 1-H or 2-H tautomeric forms
as shown in the following formulae IA and IB, respectively: 2
[0015] The nitrogen-containing compounds to be used according to
this invention are those forming, in a mixture with oxidizing
agents, during their thermal-chemical reaction, primarily CO.sub.2,
N.sub.2 and H.sub.2O, but not releasing any gases, such as CO or
NO.sub.X in health-endangering concentrations. An especially
significant feature resides in that the addition of binders is not
absolutely necessary.
[0016] R.sub.1 preferably is hydrogen, amino, hydroxy, carboxy, a
methyl, ethyl, propyl or isopropyl, butyl, isobutyl or tert-butyl,
n-pentyl, n-hexyl or n-heptyl residue, a methylamino, ethylamino,
dimethylamino, n-heptylamino, n-octylamino or n-decylamino residue,
a phenylamino residue, or a phenyl or aminophenyl residue.
[0017] R.sub.2 or R.sub.3 is preferably hydrogen, a methyl or ethyl
residue, or a phenyl or aminophenyl residue.
[0018] The following tetrazole derivatives are especially
preferred:
[0019] 5-Aminotetrazole, sodium, potassium or calcium
5-aminotetrazolate, 1-(4-aminophenyl)tetrazole,
1-methyl-5-dimethylaminotetrazole,
1-methyl-5-methyl-aminotetrazole, 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.
[0020] Cyanic acid derivatives used with preference are sodium
cyanate, cyanuric acid, 1-cyanoguanidine and/or disodium cyanamide;
triazine derivatives used with preference are 1,3,5-triazine,
cyanuric acid esters and/or cyanuric acid amide (melamine); and
urea derivatives used with preference are biuret, guanidine,
nitroguanidine, guanidine nitrate, aminoguanidine, aminoguanidine
nitrate, triaminoguanidine nitrate, aminoguanidine hydrogen
carbonate, azodicarboxylic acid diamide, dicyandiamidine nitrate,
dicyandiamidine sulfate, tetrazene and/or semicarbazide
nitrate.
[0021] Besides being acceptable from health viewpoints, the
mixtures according to this invention exhibit a high thermal and
weather stability, which is a prerequisite for perfect action even
after long-term storage.
[0022] Suitable oxidizing agents are nitrates of ammonium, sodium,
potassium, magnesium, calcium or iron, preferably sodium nitrate,
or peroxides of zinc, calcium, strontium or magnesium.
[0023] The peroxides are used with an oxygen value as obtainable
from stable compounds. For zinc peroxide, this value is about 11 to
14% by weight. The corresponding molar ratio of nitrogen-containing
compound to peroxide is in a range from 1:2 to 5.5. Calcium
peroxide can exhibit an active oxygen value of, for example, 18.26%
by weight, and grain sizes of 15.5 .mu.m and is advantageously
utilized in a molar ratio of nitrogen-containing compound/peroxide
of 1:3. In general, the aforementioned peroxides can be used in a
molar ratio of nitrogen-containing compound to peroxide in a range
of 1:1 to 20.
[0024] Calcium peroxide and/or zinc peroxide is used with
preference. It is also possible to employ mixtures of the peroxides
with one another or mixtures with other oxidizing agents. Other
oxidizing agents are, for example, the above-mentioned nitrates of
ammonium, sodium, potassium, magnesium, calcium or iron, preferably
sodium nitrate.
[0025] When using magnesium peroxide and, in particular, calcium or
strontium peroxide, the alkaline-acting hydrolysis products may
evoke reactions with the other components of the mixture. In this
case, coating of the peroxides with inorganic or organic materials
in accordance with conventional methods is suitable. Such a coating
offers, moreover, the advantage of improved handling ability since
the thus-treated propellant will no longer be dusty.
[0026] The mixtures to be utilized according to this invention of
the tetrazole and/or its derivatives with the compounds from groups
(A), (B) and/or (C) permit a finely graded staggering of the
propellants with regard to their reaction rate and the thus-formed
vapors and gases. This is a staggering needed for providing a
maximum variety of uses for the propellant charges of this
invention. Depending on the given structure of the generator
housing of an airbag, for example, or of a belt tightening device,
the propellant charges of this invention must be blended in a
controlled fashion. Only in this way is it possible to attain an
effect that is at an optimum in each case. The degree of efficiency
of the propellant charges according to this invention is, after
all, affected not only by the composition, but furthermore by the
ignition, and also by the tamping resulting from the construction,
and by the flow-off behavior of the thus-evolving vapors and gases.
Evaluation of the degree of efficiency can be accomplished, for
example, by determination of the gas pressure rise gradient of the
respective mixture in the given external environment in each case
dependent on the structure, and the type of ignition selected. The
thus-formed gas concentrations, especially those of the toxic
gases, must not exceed specific maximum values. These values result
from the MAK (maximale Arbeitsplatzkonzentration=maximum working
site concentration) values (or TLV (threshold-limit value) values
in the United States). Technical requirements are derived from
these values in conjunction with the exposure times permitted and
must be met by the respective propellant charges. When determining
these requirements, the differing passenger cells, for example,
also enter into the consideration. In order to fulfill these
demands, the respective propellant charge must be mixed in
controlled fashion.
[0027] The values indicated in the tables were determined by
igniting, in a cup in a loose bulk, 4 g of the respective
propellant charge by means of a hot wire in a pressurized bomb tube
having a volume of 25 ml. After ignition, a pressure-time curve was
recorded. The thus-obtained values were evaluated as follows:
[0028] (1) Maximum pressure (bar): with the weighed-in amounts
being the same, differences can be ascribed directly to the
thus-produced gas volumes. These are determined by gas yield and
thermal content of the reaction.
[0029] (2) Rise in gas pressure for the range of 40-60% of maximum
pressure: In this region, the curve is no longer falsified by the
ignition and/or the cooling-off characteristic of the vapors by the
inner surface of the bomb tube. The indicated times in milliseconds
(ms) represent the pressure rise and signify differing reaction
rates. Such values are also obtained in the respective cases of
application, for example in the diverse, structurally modified, gas
generator housings. They permit a precise tuning of the propellant
charges of this invention with a view toward the efficiency
requirements. By the indication of the pressure rise times in a
range of 40-60% of the maximum pressure, the reaction rate of the
propellant charges of the invention is adequately characterized.
The time periods for the reaction until the occurrence of maximum
pressure serve as additional information.
[0030] The gas temperature can be kept low in a controlled fashion
by addition of diammonium oxalate, oxalic acid diamide,
dicyandiamide, or carbonates and, respectively, bicarbonates. If
thermal stability is not a factor, and smoke formation upon
addition of inorganic carbonates or bicarbonates is to be avoided,
it is possible to use aminoguanidine bicarbonate as the organic
bicarbonate. Other additives can be constituted by oxalic acid or
urea, generally added in an amount of up to 5% by weight, based on
the mixture.
[0031] Suitable reducing agents are metal powders of iron,
magnesium, zirconium or titanium which, in contrast to the
nonmetallic compound boron, have no strong effect on the
deflagration velocity, but in case of the latter do have an
influence on the heat production of the reaction and on the
reaction products. The proportion of the reducing agents can amount
to up to 5% by weight.
[0032] Suitable catalysts for a mixture of such heterogeneous
composition are compounds having an effect on the decomposition of
peroxides, such as, for example, metals or their oxides, e.g.
manganese dioxide. Additions of vanadium pentoxide or cerium
dioxide lead to an increase in the reaction velocity. When adding
up to 5% by weight of molybdenum(VI) oxide, the velocity is only
slightly changed, and this also applies in the presence of
cerium(III) nitrate hexahydrate. These additives are effective in
amounts of up to a few percent by weight. Further catalysts are
metal complexes, of which ferrocene can here be cited as an
example; the addition of this compound with up to about 3% by
weight markedly raises the reaction velocity.
[0033] The gas compositions described in accordance with this
invention are manufactured by mixing the components according to
conventional methods, optionally with the preparation of a harmless
premix to which additional components are added. This mixture can
already be utilized in powdered form. Unmixing on account of
varying densities of the components can be counteracted by
granulation of the mixture.
[0034] In the majority of applications by far, the mixture will be
formed by press-molding or similar measures. To simplify this
procedure, press-molding aids can be added to the mixture. Suitable
as such are graphite, molybdenum disulfide, "Teflon", talc, zinc
stearate or boron nitride. These agents have an effect even in
minimum quantities and affect the properties and deflagration
behavior either not at all or only to a minor extent.
[0035] It may be advantageous in some cases to influence the
deflagration characteristic of the press-molded item by producing
porosity. Such a method resides in admixing additives, such as
salts, to the mixture prior to the actual shaping step; these
additives can be removed again after molding by extraction with
water or solvents. Another method resides in adding materials of
low thermal resistance which decompose when the molded item is
heated. The surface of the mixture can also be enlarged by adding
to the mixture, prior to press-molding, hollow microspheres of
glass or synthetic resins. The density of the press-molded article
that can be attained thereby can deviate by approximately up to 20%
from that of the untreated press-molded article; in this
connection, this value is to be merely a roughly governing value
and does not represent a limitation. This treatment leads to an
extreme acceleration of the deflagration process.
[0036] A further treatment of the molded articles can consist in
surface coating. In this case, besides achieving an effect on the
deflagration characteristic, protection against environmental
influences is obtained, in particular. Such a measure can also be
suitable for increasing the strength of the molded item. In extreme
cases, the use of suitable fibers for stabilization purposes would
have to be additionally provided for. A side effect of the coating
procedure is a decreased abrasion of the items during transport
stresses.
[0037] The thus-treated molded articles can be introduced in loose
bulk or in oriented fashion into appropriate pressure-proof
containers. They are ignited according to conventional methods with
the aid of initiator charges or thermal charges wherein the
thus-formed gases, optionally after flowing through a suitable
filter, lead to inflation of the lifesaving system within fractions
of a second.
[0038] The propellants of this invention are especially suited for
so-called airbags, impact bags which are utilized in automotive
vehicles or airplanes for occupants' protection. In case of vehicle
impact, the airbag must fill up within a minimum time period with
gas quantities of about 50 to 300 liters, depending on system and
automobile size. The propellants of this invention are likewise
suitable for use in belt-tightening devices.
[0039] Lifesaving systems containing the propellants of this
invention likewise form the subject matter of the present
invention.
EXAMPLE 1
[0040] 167 g of 5-aminotetrazole (5-ATZ) (produced from
aminoguanidine sulfate, sodium nitrite and nitric acid) is
recrystallized from about 600 ml of water under continuous
agitation, dried at 110.degree. C. after filtration, ground up, and
separated from coarse proportions with a 250 gm screen (5-ATZ
specification: mp/decomp.: >203.degree. C., average grain size
80 .mu.m and H.sub.2O proportion <0.05%). From
ZnSO.sub.4.times.7H.sub.2O and hydrogen peroxide in aqueous
ammonia, ZnO.sub.2 is produced, washed with dilute acetic acid as
well as water, and dried at 60.degree. C. (specification of
ZnO.sub.2: 13.47% by weight of active oxygen, average grain size
20.3 .mu.m).
[0041] 5-ATZ and ZnO.sub.2, as the components for nontoxic gas
charges, are homogenized together in a weight ratio of 1 to 7
(corresponding to a molar ratio of about 1:5) in plastic containers
in a tumbler mixer for 1-2 hours. Of this sample, 3.0 g is made to
react in bulk in a 25 ml size stainless steel bomb tube by means of
an electrically heatable Fe wire, and the pressure-time curve is
recorded by means of a piezoelectric measuring device. After about
30 ms, a maximum gas pressure of about 200 bar is produced, due
primarily to the formation of CO.sub.2, N.sub.2, O.sub.2 and
H.sub.2O. The reaction has a strongly exothermal character of about
471 cal/g (about 1970 J/g). ZnO remains as the reaction residue.
The CO proportion corresponds to requirements. The deflagration
point is at 219.degree. C., the friction sensitivity is at 240 N,
the impact sensitivity is at 20 J.
EXAMPLES 2-24
[0042] The use of 5-ATZ and ZnO.sub.2 as components in nontoxic gas
charges corresponds to Example 1 with the use of further additives.
Examples 2-24 below describe the reaction of other mixtures
produced by conventional procedures. The results are compiled in
Tables 1-4.
[0043] In the Tables, the first comment in the column labeled
"Reaction Velocity" refers to Example No. 2, the second to Example
No. 3 and so on.
1 TABLE 1 Reaction Velocity Organic Additives (Noles) (as Measured
in Example No. 2 3 4 5 6 7 8 9 10 Example 1) 5-Aminotetrazole 1 1 1
1 1 1 1 1 1 Zinc peroxide 3 3 3 3 3 3 3 3 3 Ammonium nitrate 2.5
2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Rose as compared with 1
Aminoguanidine nitrate 1 Rose as compared with 2 Urea 1 Dropped as
compared with 2 Oxalic acid dihydrate 1 Dropped as compared with 2
Oxalic acid diamide 1 Dropped as compared with 2 Diammonium oxalate
1 Dropped as compared monohydrate with 2 Semicarbazide nitrate 1
Rose as compared with 2 Aminoguanidine bicarbonate 1 Dropped as
compared with 2 Ferrocene 1 .times. 10.sup.-3 Rose as compared with
2
[0044]
2 TABLE 2 Reaction Velocity Inorganic Additives (Moles) (as
Measured in Example No. 11 12 13 14 15 16 Example 1)
5-Aminotetrazole 1 1 1 1 1 1 Zinc peroxide 3 3 3 3 3 1.5 Ammonium
nitrate 1.5 2.5 2.5 2.5 Iron nitrate nonahydrate 1.6 .multidot.
10.sup.-2 Dropped as compared with 2 Zinc carbonate 2 .multidot.
10.sup.-3 Dropped as compared with 2 Molybdenum(VI) oxide 3
.multidot. 10.sup.-3 Comparable to 2 Sodium nitrate 1 Dropped as
compared with 2 Strontium nitrate 1 Dropped as compared with 2
Calcium peroxide 1.5 Comparable to 2
EXAMPLE 25
[0045] The gas charge mixtures described in Examples 1-24 can also
be utilized in press-molded form. A mixture of 10 g of 5-ATZ
(H.sub.2O proportion <0.1%, mp [decomposition]>203.degree.
C., grain size 200-250 gm), 43.9 g of ZnO.sub.2 (12.85% by weight
of active oxygen, grain size about 14 .mu.m) and 23.5 g of
NH.sub.4NO.sub.3 (mp 167-169.degree. C., grain size 250-315 .mu.m),
molar ratio 1:3:2.5, is blended in accordance with Example 1 and
pressed into tablets (diameter=6 mm, height=2.77 mm, density=2.18
g/CM.sup.3, radial pressure force=155.5.+-.28.4 N) with a pressure
of 4 tons. The deflagration behavior of the press-molded items, as
tested in correspondence with Example 1, is slower than that of the
bulk material and requires 0.1 g of B/KNO.sub.3 or Ti/ZnO.sub.2 as
initiating mixture. The reaction velocity rises with a drop in the
pressing force and drops with the size of the pressed material. The
residue from the reactions remains extensively preserved in the
form of the pressed items.
EXAMPLES 26-32
[0046] As described in Example 1, further mixtures were prepared
from gas-generating components and oxygen-yielding compounds, such
as zinc peroxide, with an active oxygen proportion of 13.07% by
weight and an average grain size of 11.8 .mu.m or, in case of
sodium nitrate, with an average grain size of <45 .mu.m.
[0047] Table 4 below contains additional data on the mixtures.
3 TABLE 4 Melting Point Molar Ratios or Mixture Component (.degree.
C.) 26 27 28 29 30 31 32 5-Aminotetrazole 206-208 1 Potassium
5-aminotetrazolate 269 1 Bis (aminoguanidine)- 224-226 1
azotetrazole Nitroguanidine 252 1 Guanidine nitrate 210-214 1
Semicarbazide nitrate 115-119 1 1-Cyanoguanidine 208-210 1 Zinc
peroxide 200 (decomp.) 2.48 2.48 10.64 1.42 1.42 0.71 4.25 Sodium
nitrate -- 0.83 0.83 3.55 0.47 0.47 0.24 1.42
[0048] The components were homogenized in containers of plastic for
a 1/2 hour with a tumbler-mixer, a 1/2 hour with a vibrator, and
again for a 1/2 hour with a tumbler-mixer.
[0049] Of the thus-homogenized mixture, 4 g was introduced as
described in Example 1 into a stainless steel pressure bomb tube
and, under seal, made to react upon ignition with an incandescent
wire. The following items were measured:
[0050] the arising pressure (bar) up to the maximum value,
[0051] the time (milliseconds, ms) up to maximum pressure
value,
[0052] the pressure increase gradient (dp/dt) between a pressure
reaching 40-60% of the maximum pressure value. The rise time served
as the yardstick.
[0053] Table 5 below shows the values for the maximum pressure
(bar) and the time in ms up to maximum pressure, ranging within
regions as described in Example 1 for a gas charge of
5-aminotetrazole and zinc peroxide. In addition, the time between
40 and 60% of maximum pressure was determined.
4 TABLE 5 Max. Time (ms) Example Pressure to Max. to 40-60% of No.
(bar) Pressure Max. Pressure 26 359 30 1.2 27 217 123 13.1 28 352
29 1.5 29 473 39 1.3 30 549 14 0.5 31 917 7 0.2 32 148 220 20.1
[0054] By adaption of the parameters and admixture of further
components, it is possible to set the specifications required for
the respective gas charge.
[0055] Another sample of the previously recited mixtures was
studied with regard to physical and safety properties. The results
are set forth in Table 6.
5TABLE 6 Deflagration Friction Impact Heat of Ex Point
Sensitivities Explosion No. (.degree. C.)* (N) (J) (J/g) 26 180
>360 7.5 2451 27 207 >360 10 2293 28 197 >360 4 2411 29
215 >360 20 2964 30 364 >360 15 2777 31 210 >360 2 3128 32
194 >360 30 2101 *Determination took place according to the
method of "Bundesanstalt fuer Materialpruefung" (BAM) [Federal
Institute for Testing Materials] in Berlin.
[0056] The components are suitable for the production of gas
charges on account of their miscibility, processability,
press-molding ability for shaping, as well as compatibility with
one another and with other additives, as well as due to their
characteristic safety data.
EXAMPLES 33-44
[0057] As described in Examples 26-32, the mixtures of Examples
33-44 were produced from zinc peroxide (active oxygen proportion
12.0% by weight, average grain size 4.8 .mu.m), aminotetrazole
(average grain size.ltoreq.125 .mu.m), sodium nitrate (grain
size.ltoreq.45 .mu.m), and the listed components with a grain size
of <125 .mu.m.
[0058] The friction sensitivity, measured according to the method
of BAM, was in all cases >360 N. The additionally listed
components are disclosed in the literature.
[0059] Tables 7 and 8 below contain additional data on the
mixtures.
6TABLE 7 % by Molar Formulations Wt. Proportions Ex.No. 33 5-ATZ
29.8 1.4 Zinc peroxide 23.4 0.75 Sodium nitrate 46.8 2.2 Ex.No. 34
5-ATZ 19.5 1.0 Dicyandiamidine nitrate 15.2 0.4 Zinc peroxide 21.5
0.75 Sodium nitrate 43.8 2.24 Ex.No. 35 5-ATZ 18.1 1.0
Dicyandiamidine sulfate 12.8 0.2 zinc peroxide 19.8 0.75 Sodium
nitrate 49.3 2.73 Ex.No. 36 5-ATZ 19.5 1.0 1-Cyanoguanidine 7.7 0.4
Zinc peroxide 21.4 0.75 Sodium nitrate 51.4 2.64 Ex.No. 37 5-ATZ
16.9 1.0 Melamine 10.0 0.4 Zinc peroxide 18.6 0.75 Sodium nitrate
54.5 3.22 Ex.No. 38 5-ATZ 20.2 1.0 Azodicarboxylic acid 11.0 0.4
diamide Zinc peroxide 22.2 0.75 Sodium nitrate 46.6 2.31 Ex.No. 39
5-ATZ 19.6 1.0 Cyanuric acid 11.9 0.4 Zinc peroxide 21.4 0.75
Sodium nitrate 47.1 2.41 Ex.No. 40 5-ATZ 22.5 1.0 Urea 6.4 0.4 Zinc
peroxide 24.7 0.75 Sodium nitrate 46.4 2.06 Ex.No. 41 5-ATZ 20.2
1.0 Biuret 9.8 0.4 Zinc peroxide 22.2 0.75 Sodium nitrate 47.8 2.37
Ex.No. 42 5-ATZ 21.0 1.0 Aminoguanidine nitrate 13.5 0.4 Zinc
peroxide 23.0 0.75 Sodium nitrate 42.5 2.03 Ex.No. 43 5-ATZ 20.5
1.0 Sodium dicyanamide 8.6 0.4 Zinc peroxide 22.5 0.75 Sodium
nitrate 48.4 2.37 Ex.No. 44 5-ATZ 23.9 1.0 Sodium cyanate 7.3 0.4
Zinc peroxide 26.2 0.75 Sodium nitrate 42.6 1.79
[0060]
7TABLE 8 Gas Pressure Rise for Range of Heat of Impact Mixture
Components Zinc 5-Amino- Sodium 40-60% P.sub.max Maximum Explosion
Sensitivity Deflagration Example in Molar Proportions Peroxide
tetrazole Nitrate (ms) Pressure (bar) (J/g) (J) point (.degree. C.)
No. 0.75 1.4 2.2 0.38 683 3528 5 >400 33 Dicyandiamidine nitrate
0.4 0.75 1.0 2.24 0.40 761 3142 6 >400 34 Dicyandiamidine
sulfate 0.2 0.75 1.0 2.73 1.04 656 2883 7.5 395 35 1-Cyanoguanidine
0.4 0.75 1.0 2.64 0.36 661 3038 10 367 36 Melamine 0.4 0.75 1.0
3.22 1.16 652 3187 10 >400 37 Azodicarboxylic acid 0.4 0.75 1.0
2.31 0.36 706 3191 6 >400 38 diamide Cyanuric acid 0.4 0.75 1.0
2.41 0.80 582 2732 7.5 >400 39 Urea 0.4 0.75 1.0 2.06 0.40 654
3053 10 >400 40 Biuret 0.4 0.75 1.0 2.37 0.56 663 2982 7.5 363
41 Aminoguanidine nitrate 0.4 0.75 1.0 2.03 0.30 693 3190 7.5 256
42 Sodium dicyanamide 0.4 0.75 1.0 2.37 0.36 486 3226 7.5 356 43
Sodium cyanate 0.4 0.75 1.0 1.79 0.34 458 3005 10 349 44
* * * * *