U.S. patent application number 13/769481 was filed with the patent office on 2013-09-12 for gas generating composition and use thereof in pedestrian protection devices.
This patent application is currently assigned to TRW Airbag Systems GmbH. The applicant listed for this patent is TRW AIRBAG SYSTEMS GMBH. Invention is credited to Jorg Friedrich, Achim Hofmann, Karl-Heinz Rodig, Siegfried Zeuner.
Application Number | 20130233636 13/769481 |
Document ID | / |
Family ID | 49029292 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130233636 |
Kind Code |
A1 |
Friedrich; Jorg ; et
al. |
September 12, 2013 |
GAS GENERATING COMPOSITION AND USE THEREOF IN PEDESTRIAN PROTECTION
DEVICES
Abstract
The invention relates to gas generating compositions for use in
safety devices for vehicles. In particular, the invention relates
to said compositions based on guanidine nitrate used in pedestrian
protection devices. The composition substantially comprises 75 to
98% by weight of guanidine nitrate as fuel and 2 to 25% by weight
of a burn accelerator selected from the group of the transition
metal compounds, the metal nitrates, metal chlorates, metal
perchlorates, ammonium perchlorate and mixtures thereof, wherein
the transition metal compounds are selected from the compounds of
the transition metals Ti, Cr, Mn, Fe, Cu, Zn, Zr and Mo and wherein
the gas generating composition exhibits a burn rate of from 3 to 17
mm/s at 20 MPa.
Inventors: |
Friedrich; Jorg; (Munchen,
DE) ; Hofmann; Achim; (Tussling, DE) ; Rodig;
Karl-Heinz; (Kraiburg, DE) ; Zeuner; Siegfried;
(Munchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TRW AIRBAG SYSTEMS GMBH |
Aschau am Inn |
|
DE |
|
|
Assignee: |
TRW Airbag Systems GmbH
Aschau am Inn
DE
|
Family ID: |
49029292 |
Appl. No.: |
13/769481 |
Filed: |
February 18, 2013 |
Current U.S.
Class: |
180/274 ; 149/62;
149/78; 149/92 |
Current CPC
Class: |
C06B 31/12 20130101;
B60R 21/34 20130101; C06D 5/06 20130101; C06B 29/16 20130101; C06B
25/34 20130101; B60R 21/36 20130101 |
Class at
Publication: |
180/274 ; 149/92;
149/78; 149/62 |
International
Class: |
B60R 21/36 20060101
B60R021/36; C06B 29/16 20060101 C06B029/16; C06B 31/12 20060101
C06B031/12; C06B 25/34 20060101 C06B025/34 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2012 |
DE |
10 2012 004 468.2 |
Claims
1. A gas generating composition, especially for use in safety
devices for vehicles, having a gas yield of at least 85%, the
composition substantially comprising 75 to 98% by weight of
guanidine nitrate as fuel and 2 to 25% by weight of a burn
accelerator selected from the group of the transition metal
compounds, the metal nitrates, metal chlorates, metal perchlorates,
ammonium perchlorate and mixtures thereof, wherein the transition
metal compounds are selected from the compounds of the transition
metals Ti, Cr, Mn, Fe, Cu, Zn, Zr and Mo, and wherein the gas
generating composition has a burn rate of 3 to 17 mm/s at 20
MPa.
2. The composition according to claim 1, characterized in that the
molar gas yield of the gas generating composition amounts to at
least 0.035 mole/g.
3. The composition according to claim 1, wherein the volume-related
gas yield of the gas generating composition amounts to at least
0.059 mole/cm.sup.3.
4. The composition according to claim 1, wherein the burn rate is
within the range of from 7 to 16 mm/s at 20 MPa.
5. The composition according to claim 1, wherein the burn rate is
within the range of from 10 to 17 mm/s at 20 MPa.
6. The composition according to claim 1, wherein the gas generating
composition exhibits an oxygen balance of -10% to -27%.
7. The composition according to claim 6, wherein the oxygen balance
is within the range of from -14% to -24%.
8. The composition according to claim 1, wherein the composition is
shelf-stable at 120.degree. C. for 400 h.
9. The composition according to claim 1, wherein the gas generating
composition exhibits a combustion temperature of not more than 1650
K.
10. The composition according to claim 9, wherein the combustion
temperature is within the range of from 1420 to 1630 K.
11. The composition according to claim 1, wherein the transition
metal compound is selected from the group of the transition metal
oxides, transition metal hydroxides, transition metal carbonates,
basic transition metal carbonates and basic transition metal
nitrates.
12. The composition according to claim 1, wherein the transition
metal compound has a mean grain size of not more than 5 .mu.m and a
specific surface of at least 1 m.sup.2/g.
13. The composition according to claim 1, wherein the burn
accelerator is selected from the group consisting of TiO.sub.2,
Cr.sub.2O.sub.3, MnO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, CuO,
Cu.sub.2O, ZnO, ZrO.sub.2, MoO.sub.3, FeOOH, Cu(OH).sub.2,
ZnCO.sub.3, MnCO.sub.3, FeCO.sub.3, CuCO.sub.3, basic zinc
carbonate, basic copper carbonate, basic copper nitrate, basic zinc
nitrate, and mixtures thereof.
14. The composition according to claim 1, wherein the burn
accelerator is a mixture of at least one compound from the group of
the metal nitrates, metal chlorates, metal perchlorates and
ammonium perchlorate as well as additionally at least one
transition metal compound of Ti, Cr, Mn, Fe, Cu, Zn, Zr and Mo.
15. The composition according to claim 14, wherein the compound is
selected from the group of the metal nitrates, metal chlorates and
metal perchlorates of the group consisting of NaNO.sub.3,
KNO.sub.3, Sr(NO.sub.3).sub.2, NaClO.sub.3, KClO.sub.3,
NaClO.sub.4, KClO.sub.4, NH.sub.4ClO.sub.4 and mixtures
thereof.
16. The composition according to claim 14, wherein the transition
metal compound is selected from the group consisting of TiO.sub.2,
Cr.sub.2O.sub.3, MnO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, CuO,
Cu.sub.2O, ZnO, ZrO.sub.2, MoO.sub.3, FeOOH, Cu(OH).sub.2,
ZnCO.sub.3, MnCO.sub.3, FeCO.sub.3, CuCO.sub.3, basic zinc
carbonate, basic copper carbonate, basic copper nitrate, basic zinc
nitrate and mixtures thereof.
17. The composition according to claim 1, wherein the gas
generating composition additionally comprises up to 5% by weight of
burn moderators and/or coolants based on the total composition.
18. The composition according to claim 1, wherein the burn
moderators and/or coolants are selected from the group consisting
of B.sub.2O.sub.3, Al.sub.2O.sub.3, SiO.sub.2, MgO, Mg(OH).sub.2,
MgCO.sub.3, basic magnesium carbonate, CaCO.sub.3 and mixtures
thereof.
19. The composition according to claim 1, wherein the gas
generating composition additionally comprises up to 3% by weight of
processing aids from the group of anti-caking agents, pressing aids
and anti-blocking agents, based on the total composition.
20. The composition according to claim 1, wherein the processing
aids are selected from the group consisting of polyethylene glycol,
cellulose, methyl cellulose, graphite, wax, calcium stearate,
magnesium stearate, zinc stearate, boron nitride, talcum,
bentonite, silica and molybdenum sulfide as well as mixtures
thereof.
21. A pedestrian protection device for a vehicle comprising an
inflator and means for pedestrian protection adapted to be
activated by gas, wherein the inflator contains a gas generating
composition according to claim 1.
22. The pedestrian protection device according to claim 21, wherein
the inflator is arranged outside a passenger compartment of the
vehicle.
23. The pedestrian protection device according to claim 21, wherein
the inflator interacts with an inflatable airbag.
24. The pedestrian protection device according to claim 21, wherein
the inflator drives a hood stay of the vehicle.
25. Use of a gas generating composition according to claim 1 in an
inflator of a safety device in a vehicle, the inflator being
arranged outside a passenger compartment of the vehicle.
26. Use of a gas generating composition according to claim 1 in a
pedestrian protection device for vehicles.
Description
BACKGROUND
[0001] The invention relates to gas generating compositions,
especially for use in safety devices for vehicles. In particular,
the invention relates to such compositions based on guanidine
nitrate used in pedestrian protection devices.
[0002] Gas generating compositions based on guanidine nitrate are
known, for example, from EP-A 1 006 096 and U.S. Pat. No.
6,143,102. Almost all manufacturers of vehicle occupant restraint
systems make use of such compositions in series production of
pyrotechnical inflators for airbag modules of occupant protection
devices, especially for driver and passenger airbags. The
compositions comprising guanidine nitrate as fuel commonly used for
said applications have a mass-related gas yield of approx. 65 to
75%, burn rates of approx. 20 to 30 mm/s and combustion
temperatures of about 1700 to 2000 K. The share of guanidine
nitrate in these compositions frequently is within the range of
from 40 to 50% by weight.
[0003] For the use of airbag modules in the interior of the vehicle
increased requirements to the generated propellant are applicable,
because the latter can enter into the passenger compartment via
discharge orifices in the airbag. The limits of gas components such
as CO, NH.sub.3 and NO.sub.x required in the specifications of the
car manufacturers can only be reached by fuel mixtures having a
substantially balanced oxygen balance. Therefore the percentage of
guanidine nitrate in the gas generating compositions for airbag
modules is limited to approx. 65% by weight, and apart from
guanidine nitrate considerable percentages of oxidizing agents have
to be employed. Since the oxidizing agents usually do not
completely contribute to the gas generation, the possible gas yield
of those compositions is reduced. Also for compositions having low
burn temperatures which positively influence the noxious gas
composition a higher percentage of non-gas generating additives has
to be accepted, which equally affects the gas yield. The gas yields
that can be obtained by the gas generating compositions comprising
guanidine nitrate as fuel common so far thus do not amount to more
than 75%.
[0004] U.S. Pat. No. 6,893,517 describes gas generating
compositions based on guanidine nitrate having a gas yield of about
80%. These compositions contain further organic fuels and are
formulated for use in belt tensioners. The compositions therefore
have a definitely higher burn temperature of more than 2000 K and a
high burn rate of more than 40 mm/s at 20 MPa.
[0005] Pure guanidine nitrate shows no self-retaining and complete
disintegration after ignition. Therefore U.S. Pat. No. 2,604,391
suggests improving the ignition behavior and the burn
characteristics of guanidine nitrate by appropriate additives. By
the addition of copper and copper compounds to guanidine nitrate,
gas generating compositions having a burn rate of about 1 mm/s at
0.9 MPa are obtained. By adding vanadium pentaoxide the burn rate
is intended to be increased. However, vanadium pentaoxide is toxic
and is excluded from applications in the automotive industry.
[0006] The burn rates required for gas generating compositions for
occupant protection systems (driver, passenger and side impact
systems) in general are within >20 mm/s. As a result, in the
commonly used fabric thicknesses of the propellant members (in
general tablets) of 1 to 2 mm the burning is completed after a
maximum of 100 ms. In this case, by the fabric thickness the layer
thickness of a propellant member is understood which is passed
during burning of the propellant member until complete consumption
thereof. For example, a cylindrical tablet having a diameter of 6
mm and a height of 3 mm has a fabric thickness of 1.5 mm, as in the
case of even burning from all sides after burning of a layer
thickness of 1.5 mm the entire tablet is consumed.
[0007] However, for pedestrian protection applications at the
exterior of the vehicle to protect the pedestrian against impacting
on the hood or the windscreen, gas delivery times of more than 100
ms are desired. Moreover the inflated airbag is intended to have an
as long durability as possible. For this purpose, it is
advantageous when the temperature of the gas generated for
inflating the airbag is as low as possible so as to keep the
pressure loss due to cooling of the gas low.
SUMMARY
[0008] It is the object of the invention to provide gas generating
compositions by which longer gas delivery times and an improved
durability of the protective devices activated by the release of
gas can be achieved and which are suited for pedestrian protection
applications.
[0009] This object is achieved by a gas generating composition
according to claim 1.
[0010] The subject matter of the invention also is a pedestrian
protection device in vehicles in which the gas generating
composition according to the invention is contained as well as the
use of the gas generating compositions according to the invention
in pedestrian protection devices of vehicles.
[0011] Advantageous embodiments of the invention which can be
optionally combined with each other are stated in the
subclaims.
DESCRIPTION
[0012] The gas generating composition according to the invention
serves for use in safety devices for vehicles and exhibits a gas
yield of at least 85%. The composition substantially comprises 75
to 98% by weight of guanidine nitrate as fuel and 2 to 25% by
weight of a burning accelerator selected from the group of the
transition metal compounds, metal nitrates, metal chlorates, metal
perchlorates, ammonium perchlorate and mixtures thereof. The burn
rate of the composition is within the range of from 3 to 17 mm/s at
20 MPa.
[0013] Transition metal compounds in accordance with the invention
are the compounds, preferably the oxides, hydroxides, carbonates,
basic carbonates and basic nitrates, of the metals of the first
series of the transition metals, namely of titanium, chromium,
manganese, iron, copper and zinc, as well as of zirconium and
molybdenum of the second transition metal series.
[0014] The compounds of the metals vanadium, cobalt and nickel as
well as cadmium and mercury, which are undesired because of their
toxicological characteristics, are not in accordance with the
invention and are expressly excluded. Equally undesired are the
compounds of the hexavalent chromium. The use of said metals and
the compounds thereof is explicitly excluded in most specifications
of the car manufacturers anyway.
[0015] Metal nitrates, metal chlorates and metal perchlorates are
especially those compounds of the alkali metals and earth alkali
metals.
[0016] In accordance with a preferred embodiment, the molar gas
yield of the gas generating composition amounts to at least 0.035
mole/g (moles of generated gas 1 g of fuel), especially preferred
to 0.039 to 0.043 mole/g, and the volume-related gas yield (moles
of generated gas/volume of fuel) amounts to at least 0.059
mole/cm.sup.3, especially preferred to 0.059 to 0.062
mole/cm.sup.3.
[0017] The theoretic molar gas yield for pure guanidine nitrate is
0.042 mole/g; the theoretical volume-related gas yield is 0.061
mole/cm.sup.3 calculated each for a pressure of 30 MPa. Slightly
higher molar or volume-related gas yields can be achieved by
appropriate burning accelerators which reduce the molar weight of
the generated gas and/or increase the density of the gas generating
composition.
[0018] The burn rate of the gas generating compositions used in
airbag modules for pedestrian protection devices outside the
passenger compartment preferably is within the range of from 7.0 to
16.0 mm/s at 20 MPa. If the gas generating compositions in micro
inflators are used to activate stays for hoods and similar
pedestrian protection devices in which the gas released from the
composition actuates a cylinder-piston mechanism, the burn rate
preferably is within the range of from 10 to 17 mm/s at 20 MPa. For
quick applications small tablets having a diameter of 1-4 mm or
else granules can be employed.
[0019] The joint grinding of the components for example in a ball
mill, vibration ball mill or rocker mill has turned out to be an
efficient method of increasing the burn rate of a given
composition. With the aid of the grinding bodies, on the one hand
the particle size of the components used is reduced and, on the
other hand, high homogeneity is achieved by intimately mixing and
pressing the individual parts into each other. Both factors promote
an increase in reactivity of the components used and thus also in
the burn rate. Through the duration of the joint grinding and
homogenizing as well as the grain size of the initial compounds the
burn rate of the mixtures can be widely controlled. Thus definitely
higher burn rates than in the propellants described in U.S. Pat.
No. 2,604,391 can be reached even with a nominally equal
composition.
[0020] Further the use of a fine-particle quality of the transition
metal compound having a medium grain size of not more than 5 .mu.m
and a specific surface of at least 1 m.sup.2/g is preferred.
[0021] With a mixture of 94.5% of guanidine nitrate, 5% of copper
oxide and 0.5% of calcium stearate a burn rate of 6.2 mm/s at 20
MPa could be obtained in this way. The copper oxide quality used as
starting material had a mean grain size of 0.8 .mu.m and a specific
surface of 10 m.sup.2/g. The guanidine nitrate used had a mean
grain size of 6.5 .mu.m. However, it turned out that the grain size
of the guanidine nitrate used as starting material is of minor
significance, as a coarser grain size can be compensated by a
longer grinding time.
[0022] The gas generating composition preferably has an oxygen
balance of -10% to -27%, especially preferred of -14 to -24. The
low oxygen balance contributes to a high gas yield and a low
burning temperature. An unfavorable influence on the carbon
monoxide parts can be tolerated, as the gases released during
burning of the composition do not enter into the passenger
compartment.
[0023] The oxygen balance is understood to be the oxygen quantity
in percent by weight which is freed in the case of complete
conversion of a compound or a mixture into CO.sub.2, H.sub.2O,
N.sub.2, Al.sub.2O.sub.3, B.sub.2O.sub.3 etc. (oxygen
over-balancing). If the oxygen present is not sufficient for this
purpose, the missing quantity required for the complete conversion
is indicated with negative sign (oxygen under-balancing).
[0024] In accordance with an especially preferred embodiment, the
compositions according to the invention are thermally shelf-stable
at 120.degree. C. for 400 h. The loss of weight in the hot storage
test in the afore-mentioned conditions preferably is less than 2%,
especially preferred less than 1%. Thus the compositions according
to the invention also satisfy the specifications of the car
manufacturers for applications in the engine compartment.
[0025] The compositions according to the invention preferably
exhibit a burning temperature of no more than 1650 K. Preferably
the burning temperature is within the range of from 1370 to 1650 K,
especially preferred within the range of from 1420 to 1630 K. The
provision of cold gases is equally advantageous to applications in
the area outside the passenger compartment and promotes a longer
durability of the inflated airbag or the safety device activated by
gas pressure.
[0026] The burning accelerator is preferably selected from the
group consisting of TiO.sub.2, Cr.sub.2O.sub.3, MnO.sub.2,
Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, CuO, Cu.sub.2O, ZnO, ZrO.sub.2,
MoO.sub.3, FeOOH, Cu(OH).sub.2, ZnCO.sub.3, MnCO.sub.3, FeCO.sub.3,
CuCO.sub.3, basic zinc carbonate, basic copper carbonate, basic
copper nitrate, basic zinc nitrate, NaNO.sub.3, KNO.sub.3,
Sr(NO.sub.3).sub.2, NaClO.sub.3, KClO.sub.3, NaClO.sub.4,
KClO.sub.4, NH.sub.4ClO.sub.4 and mixtures thereof.
[0027] According to an especially preferred embodiment of the
composition according to the invention the burning accelerator is a
mixture of at least one compound from the group of the metal
nitrates, metal chlorates, metal perchlorates and ammonium
perchlorate as well as additionally of at least one transition
metal compound of Ti, Cr, Mn, Fe, Cu, Zn, Zr and Mo. By this
embodiment a high gas yield is obtained at a sufficient burn rate
and a simultaneously low burning temperature.
[0028] Preferably the compound is selected from the group of the
metal nitrates, metal chlorates and metal perchlorates from the
group consisting of NaNO.sub.3, KNO.sub.3, Sr(NO.sub.3).sub.2,
NaClO.sub.3, KClO.sub.3, NaClO.sub.4, KClO.sub.4 and mixtures
thereof. The use of ammonium perchlorate is also provided in this
embodiment.
[0029] In the described embodiment the transition metal compound is
preferably selected from the group consisting of TiO.sub.2,
Cr.sub.2O.sub.3, MnO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, CuO,
Cu.sub.2O, ZnO, ZrO.sub.2, MoO.sub.3, FeOOH, Cu(OH).sub.2,
ZnCO.sub.3, MnCO.sub.3, FeCO.sub.3, CuCO.sub.3, basic zinc
carbonate, basic copper carbonate, basic copper nitrate, basic zinc
nitrate and mixtures thereof.
[0030] The transition metal compounds preferably have a mean grain
size of not more than 5 .mu.m, especially preferred of not more
than 3 .mu.m and a specific surface of at least 1 m.sup.2/g,
especially preferred at least 3 m.sup.2/g.
[0031] In addition to guanidine nitrate as fuel and the
afore-mentioned burn accelerators, the composition according to the
invention may comprise up to 5% by weight of further additives from
the group of burn moderators and/or coolants. The afore-mentioned
additives have a stabilizing effect on the burning and keep the
combustion temperature low. Simultaneously the slagging of
combustion residues is improved, thereby the residues being
prevented from dusting.
[0032] Examples of appropriate burn moderators and/or coolants are
B.sub.2O.sub.3, Al.sub.2O.sub.3, MgO, SiO.sub.2, Mg(OH).sub.2,
basic magnesium carbonate, CaCO.sub.3 and mixtures thereof.
[0033] Further the compositions may include up to 3% of processing
aids such as pressing aids, anti-caking agents and/or anti-blocking
agents which in the given amount do not substantially influence the
burn rate of the composition.
[0034] Examples of appropriate processing aids are polyethylene
glycol, cellulose, methyl cellulose, graphite, wax, calcium
stearate, magnesium stearate, zinc stearate, boron nitride, talcum,
bentonite, silica and molybdenum sulfide as well as mixtures
thereof.
[0035] A subject matter of the invention further is a pedestrian
protection device for a vehicle comprising an inflator and means
for pedestrian protection adapted to be activated by gas such as an
inflatable airbag or a piston-cylinder system for propping up the
hood in which the inflator contains a gas generating composition
according to the invention in accordance with one or more of the
afore-described embodiments.
[0036] The inflator of the pedestrian protection device is
preferably disposed outside a passenger compartment of the vehicle,
for example in the engine compartment. In such embodiment
especially the improved hot shelf life of the composition according
to the invention is advantageous.
[0037] According to a special embodiment of the pedestrian
protection device according to the invention, the inflator
interacts with an inflatable airbag. In the case of collision of
the vehicle with a pedestrian, the risk of injury of the pedestrian
can be considerably reduced by the inflated airbag.
[0038] According to a further embodiment of the pedestrian
protection device, the inflator drives the piston-cylinder system
of a hood stay. Thus an impact of the pedestrian on the windscreen
of the vehicle can be prevented and the risk of cuts due to the
breakage of glass can be reduced.
[0039] Finally, a subject matter of the invention also is the use
of the gas generating compositions according to the invention in
accordance with one or more of the afore-described embodiments in
an inflator of a safety device in a vehicle, wherein the inflator
is disposed outside a passenger compartment of the vehicle.
[0040] Especially preferred is the use of the gas generating
compositions in a pedestrian protection device for vehicles.
[0041] The advantages of the gas generating compositions according
to the invention especially reside in the fact that high gas yields
can be achieved with simultaneously low combustion temperatures and
moderate burn rates ensuring a long gas delivery time and a longer
durability of the safety devices activated by gas. The burn rates
obtained by the compositions according to the invention are below
the burn rates of compositions previously used for airbag modules
in the field of occupant protection, but at the same time still
within a range suited for the use in pedestrian protection
devices.
[0042] The high thermal stability of the compositions according to
the invention furthermore also permits the use thereof in the
engine compartment of vehicles where temperatures of up to
120.degree. C. can easily be reached in operating conditions.
[0043] Finally the compositions according to the invention resort
to tested and non-toxic components which are available on the
market at reasonable prices.
[0044] The invention shall now be described by way of preferred
embodiments which are not to be understood in a limiting sense,
however.
Embodiments 1 Through 18
[0045] Guanidine nitrate having a mean particle size of from 6.5 to
35 .mu.m, transition metal compounds having a mean particle size
between 0.5 and 2 .mu.m and a specific surface between 4 and 25
m.sup.2/g, metal nitrates and perchiorates having a mean grain size
of about 50 .mu.m as well as pyrogenic aluminum oxide, silicon
oxide and/or calcium stearate were mixed in the parts by weight
listed in the following table 1, were ground together in a
vibration ball mill and pressed into tablets.
TABLE-US-00001 TABLE 1 Example Components [%] No. GuN bCN
KClO.sub.4 KNO.sub.3 Sr(NO.sub.3).sub.2 CuO Al.sub.2O.sub.3
SiO.sub.2 Fe.sub.2O.sub.3 Ca stearate 1 87.5 10.0 2.0 0.5 2 92.5
5.0 2.0 0.5 3 92.5 5.0 2.0 0.5 4 89.5 5.0 2.0 3.0 0.5 5 87.5 10.0
2.0 0.5 6 92.5 5.0 2.0 0.5 7 94.5 5.0 0.5 8 89.5 10.0 0.5 9 87.0
7.5 2.0 3.0 0.5 10 87.0 7.5 2.0 3.0 0.5 11 89.5 5.0 2.0 3.0 0.5 12
92.5 5.0 2.0 0.5 13 89.5 5.0 2.0 3.0 0.5 14 87.5 5.0 5.0 2.0 0.5 15
81.0 10.0 5.0 2.5 1.0 0.5 16 76.0 15.0 5.0 2.5 1.0 0.5 17 92.5 5.0
2.0 0.5 18 89.5 5.0 5.0 0.5
[0046] The abbreviations used in table 1 mean as follows: [0047]
GuN=guanidine nitrate [0048] bCN=basic copper nitrate
[0049] The burn rate (BR) of the compositions according to the
examples 1 through 18 was determined by bombarding 10 grams of
propellant at a time within a closed 100 cm.sup.3 bomb. The test
results as well as further calculated characteristics of the
compositions are listed in table 2.
TABLE-US-00002 TABLE 2 Characteristics BR T O.sub.2 balance GA
density GA Example No [mm/s] [K] GA [%] [%] [mole/g] [g/ccm]
[mole/ccm] 1 5.3 1427 92.6 -21.3 0.039 23.71 0.060 2 11.4 1500 95.6
-22.9 0.041 23.49 0.061 3 15.9 1447 94.9 -23.2 0.040 23.51 0.060 4
10.8 1432 93.6 -22.4 0.040 23.63 0.059 5 5.7 1427 92.6 -21.3 0.039
23.71 0.060 6 11.9 1500 95.6 -22.9 0.041 23.49 0.061 7 6.2 1379
95.9 -25.1 0.040 23.73 0.060 8 6.2 1384 91.9 -22.8 0.039 23.79
0.060 9 15.3 1559 91.3 -20.3 0.039 23.38 0.059 10 7.2 1498 90.1
-20.9 0.039 23.38 0.059 11 9.7 1426 93.0 -22.4 0.039 23.63 0.059 12
4.3 1370 93.9 -24.6 0.040 23.73 0.060 13 10.1 1483 93.0 -22.1 0.040
23.5 0.060 14 10.5 1499 91.2 -21 0.039 23.53 0.060 15 11.2 1573
88.7 -17.3 0.038 23.53 0.062 16 11.7 1625 85.8 -14.5 0.037 23.2
0.059 17 13.5 1516 96.4 -23.3 0.041 23.7 0.061 18 15.1 1503 93.5
-22.5 0.039 23.71 0.060
[0050] The further abbreviations used in table 2 mean as follows:
[0051] T=combustion temperature, calculated in Kelvin [0052] GA
[%]=mass-related gas yield [0053] GA [mole/ccm]=volume-related gas
yield [0054] GA [mole/g]=molar gas yield
[0055] The compositions according to the examples 1 through 18
furthermore were submitted to an aging test for 400 hours at
120.degree. C. After this test in general a loss of weight of less
than 2% was determined. For the composition according to example
16a loss of weight of merely 0.36% was determined. Thus all
compositions satisfy the increased requirements to the aging
stability of inflator propellants for applications in the engine
compartment.
[0056] The afore-described burn tests moreover show the suitability
of the compositions according to the invention for use in
pedestrian protection devices.
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