U.S. patent application number 10/990444 was filed with the patent office on 2005-07-21 for gas generating composition.
Invention is credited to Wu, Jianzhou.
Application Number | 20050155681 10/990444 |
Document ID | / |
Family ID | 34753484 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050155681 |
Kind Code |
A1 |
Wu, Jianzhou |
July 21, 2005 |
Gas generating composition
Abstract
There is provided a gas generating composition in which the
concentration of NOx and so on in the fuel gas is low. The gas
generating composition comprises a fuel, a metal hydroxide such as
aluminum hydroxide, and a binder, wherein the content of the metal
hydroxide in the composition is in the range of 0.5 to 15 mass %,
and the content of the binder in the composition is in the range of
1.0 to 4.5 mass %. Because the concentration of NOx and so on in
the fuel gas is low, in the case of use in an air bag gas
generator, passenger safety upon inflation of the air bag is
high.
Inventors: |
Wu, Jianzhou; (Himeji-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
34753484 |
Appl. No.: |
10/990444 |
Filed: |
November 18, 2004 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60525836 |
Dec 1, 2003 |
|
|
|
Current U.S.
Class: |
149/36 |
Current CPC
Class: |
C06B 23/02 20130101;
C06D 5/06 20130101 |
Class at
Publication: |
149/036 |
International
Class: |
C06B 047/08 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 21, 2003 |
JP |
2003-392152 |
Claims
1. A gas generating composition comprising a fuel, a metal
hydroxide and a binder, wherein the content of the metal hydroxide
in the composition is in the range of 0.5 to 15 mass % and the
content of the binder in the composition is in the range of 1.0 to
4.5 mass %.
2. The gas generating composition as claimed in claim 1, wherein
the metal hydroxide is at least one selected from the group
consisting of aluminum hydroxide, magnesium hydroxide, calcium
hydroxide, zirconium hydroxide, cobalt hydroxide and copper
hydroxide.
3. The gas generating composition as claimed in claim 1, wherein
the metal hydroxide is at least one selected from the group
consisting of aluminum hydroxide, magnesium hydroxide and a mixture
thereof.
4. The gas generating composition as claimed in claim 1 or 2,
wherein the mass ratio between the metal hydroxide to the binder is
in the range of 15/1 to 1/2.
5. The gas generating composition as claimed in claim 1 or 2,
wherein the binder is at least one selected from the group
consisting of carboxymethyl cellulose, sodium carboxymethyl
cellulose, potassium carboxymethyl cellulose, ammonium
carboxymethyl cellulose, cellulose acetate, cellulose acetate
butyrate, methyl cellulose, ethyl cellulose, hydroxyethyl
cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose,
carboxymethyl ethyl cellulose, microcrystalline cellulose,
polyacrylamide, aminated polyacrylamide, polyacrylhydrazide, an
acrylamide-metal acrylate copolymer, a polyacrylamide-polyacrylic
ester copolymer, polyvinyl alcohol, acrylic rubber, guar gum,
starch and silicone.
6. The gas generating composition as claimed in claim 1 or 2,
further comprising an oxidizing agent.
Description
TECHNICAL FIELD
[0001] The present invention relates to a gas generating
composition used in an air bag gas generator.
BACKGROUND ART
[0002] As gas generating agents used in air bag gas generators,
highly safe non-azide-based gas generating compositions comprising
any of various nitrogen-containing organic compounds have been
developed. There are various requirements on gas generating
compositions from the viewpoint of being used in air bag gas
generators. As one of these, from the viewpoint of securing
passenger safety, the combustion gas is required to be clean, i.e.
the amounts of nitrogen oxides (NOx), carbon monoxide, ammonia and
so on contained in the combustion gas are required to be as low as
possible.
[0003] JP-A No. 10-502610 discloses adding glass powder to a fuel
such as a tetrazole compound and strontium nitrate, thus lowering
the combustion temperature, resulting in a reduction in the amounts
of NOx and CO.
DISCLOSURE OF THE INVENTION
[0004] An object of the present invention is to provide a gas
generating composition, used in an air bag gas generator, in which
the amounts of NOx, carbon monoxide, ammonia and so on contained in
the combustion gas upon the gas generating composition being burned
are further reduced.
[0005] The present inventor discovered that when using a
combination of a well known metal hydroxide and binder as
components of a gas generating composition, by making the contents
thereof be within specific ranges, and further making the ratio
between these contents be within a specific range, the amounts of
NOx, carbon monoxide, ammonia and so on can be greatly reduced, and
hence passenger safety upon air bag inflation can be improved, thus
accomplishing the present invention.
[0006] As means for solving the problem, the present invention
provides a gas generating composition comprising a fuel, a metal
hydroxide and a binder, wherein the content of the metal hydroxide
in the composition is in the range of 0.5 to 15 mass %, and the
content of the binder in the composition is in the range of 1.0 to
4.5 mass %.
[0007] By using the gas generating composition of the present
invention in an air bag gas generator, the amounts of NOx, carbon
monoxide, ammonia and so on contained in the combustion gas
produced upon activation of the gas generator can be greatly
reduced, and hence passenger safety upon inflation of the air bag
by this combustion gas can be improved.
PREFERRED EMBODIMENT OF THE INVENTION
[0008] There are no particular limitations on the fuel used in the
present invention, with examples being ones used in well known gas
generating compositions. As the fuel, at least one selected from
tetrazole compounds, guanidine compounds, triazine compounds and
nitroamine compounds is preferable.
[0009] Examples of tetrazole compounds include 5-aminotetrazole and
ammonium bitetrazole; examples of guanidine compounds include
guanidine nitrate, mono-, di- and tri-aminoguanidine nitrate, and
nitroguanidine; examples of triazine compounds include melamine,
cyanuric acid, ammeline, ammelide and ammelande; examples of
nitroamine compounds include
cyclo-1,3,5-trimethylene-2,4,6-trinitramine.
[0010] The content of the fuel in the composition is preferably in
the range of 15 to 60 mass %, more preferably 20 to 50 mass %, yet
more preferably 25 to 50 mass %.
[0011] There are no particular limitations on an oxidizing agent
used in the present invention as required, with examples being ones
used in well known gas generating compositions. As such an
oxidizing agent, at least one selected from nitrates, perchlorates,
chloric acid, basic metal nitrates, ammonium nitrate, and so on is
preferable.
[0012] Examples of nitrates include alkali metal nitrates such as
potassium nitrate and sodium nitrate, and alkaline earth metal
nitrates such as strontium nitrate; examples of perchlorates
include potassium perchlorate, sodium perchlorate, magnesium
perchlorate and ammonium perchlorate; examples of basic metal
nitrates include basic copper nitrate.
[0013] The content of the oxidizing agent in the composition is
preferably in the range of 30 to 85 mass %, more preferably 35 to
70 mass %, yet more preferably 40 to 60 mass %.
[0014] An example of the metal hydroxide used in the present
invention is at least one selected from magnesium hydroxide,
aluminum hydroxide, calcium hydroxide, zirconium hydroxide, cobalt
hydroxide, and copper hydroxide; of these, magnesium hydroxide,
aluminum hydroxide, or a mixture thereof is preferable.
[0015] By adjusting the mean particle diameter of the metal
hydroxide, the overall dispersibility when mixing with the fuel and
so on can be improved; this is preferable, since then the mixing
operation becomes easy, and moreover the ignitability of the
composition obtained is improved.
[0016] The mean particle diameter of the metal hydroxide is
preferably in the range of 0.1 to 70 .mu.m, more preferably 0.5 to
50 .mu.m, yet more preferably 2 to 30 .mu.m. The mean particle
diameter is that measured by a particle size distribution method
using scattered laser light. The measurement sample used is
obtained by dispersing the metal hydroxide in water, and then
irradiating with ultrasound for 3 minutes; the 50% particle count
cumulative value (D.sub.50) is determined, and the mean value over
two measurements is taken as the mean particle diameter.
[0017] To achieve the object of the present invention, the content
of the metal hydroxide in the composition is in the range of 0.5 to
15 mass %, preferably 2 to 13 mass %, more preferably 5 to 11 mass
%.
[0018] There are no particular limitations on the binder used in
the present invention, with examples being ones used in well known
gas generating compositions. As the binder, at least one selected
from carboxymethyl cellulose, sodium carboxymethyl cellulose,
potassium carboxymethyl cellulose, ammonium carboxymethyl
cellulose, cellulose acetate, cellulose acetate butyrate, methyl
cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl
hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl
ethyl cellulose, microcrystalline cellulose, polyacrylamide,
aminated polyacrylamide, polyacrylhydrazide, an acrylamide-metal
acrylate copolymer, apolyacrylamide-polyacrylic ester copolymer,
polyvinyl alcohol, acrylic rubber, guar gum, starch and silicone is
preferable.
[0019] To achieve the object of the present invention, the content
of the binder in the composition is in the range of 1.0 to 4.5 mass
%, preferably 1.5 to 4.0 mass %, more preferably 2.0 to 3.5 mass
%.
[0020] To achieve the object of the present invention, the mass
ratio between the metal hydroxide and the binder (metal hydroxide
/binder) is preferably in the range of 15/1 to 1/2, more preferably
10/1 to 1/1, yet more preferably 7/1 to 1/1.
[0021] In the present invention, from the viewpoint of lowering the
combustion temperature of the gas generating composition,
regulating the burning rate, and reducing the amounts of toxic
nitrogen oxides and carbon monoxide produced after the combustion,
additives can be further included.
[0022] Examples of such additives are at least one from metal
oxides such as copper oxide, iron oxide, zinc oxide, cobalt oxide,
manganese oxide, molybdenum oxide, nickel oxide, bismuth oxide,
gallium oxide, silica and alumina, metal carbonates or basic metal
carbonates such as cobalt carbonate, calcium carbonate, magnesium
carbonate, basic zinc carbonate and basic copper carbonate,
composite compounds of a metal oxide or a hydroxide such as
Japanese acid clay, kaolin, talc, bentonite, diatomaceous earth and
hydrotalcite, metal acid salts such as sodium silicate, mica
molybdate, cobalt molybdate and ammonium molybdate, molybdenum
disulfide, calcium stearate, silicon nitride and silicon
carbide.
[0023] The gas generating composition of the present invention can
be molded into a desired shape, and thus made into a molded article
having the form of a single-perforated cylinder, a porous cylinder,
or pellets. Such a molded article can be manufactured using a
method in which water or an organic solvent is added to the gas
generating composition and mixing is carried out, and then
extrusion molding is carried out (for a molded article having the
form of a single-perforated cylinder or a porous cylinder), or a
method in which compression-molding is carried out using a
pelletizer or the like (for a molded article having the form of
pellets).
[0024] The gas generating composition of the present invention can
be used, for example, in any of various vehicles in a driver air
bag gas generator, a front passenger air bag gas generator, a side
air bag gas generator, an inflatable curtain gas generator, a knee
bolster gas generator, an inflatable seat belt gas generator, a
tubular system gas generator, or a pretensioner gas generator.
[0025] Moreover, a gas generator using the gas generating
composition of the present invention may be either a pyrotechnic
type in which gas is supplied from the gas generating composition
only, or a hybrid type in which gas is supplied from both the gas
generating composition and a compressed gas such as argon.
[0026] Furthermore, the gas generating composition of the present
invention can also be used as an igniting agent called an enhancer
(or a booster) for transferring energy from a detonator or a squib
to a gas generating agent.
EXAMPLES
Examples 1 to 6
[0027] A total of 5,000 g of the various components of each
composition shown in Table 1 and 737 g of water were put into a
mixer and mixing was carried out. The mixture was extruded using an
extruder, and cutting and drying were carried out, thus obtaining a
gas generating composition in a single-perforated shape having an
outside diameter of approximately 4.2 mm, an inside diameter of
approximately 1.1 mm, and a length of approximately 4.1 mm. There
was no problem with the moldability for any of the compositions. A
prescribed amount of each of the gas generating compositions (the
mass shown in Table 1) was put into a chamber of inside diameter 57
mm and height 32 mm, and the chamber was sealed, thus forming a
test gas generator.
[0028] Using each gas generator, a 2800 liter tank exhaust gas test
was carried out. In the 2800 liter tank test, the inflator was set
in an iron tank having an internal volume of 2800 liters, ignition
was carried out, the concentrations of NO, NO.sub.2, CO and
NH.sub.3 in the tank after 3 minutes, 15 minutes and 30 minutes
were measured using a detector tube, and the mean value of the gas
concentrations after 3 minutes, 15 minutes and 30 minutes was taken
as the concentration for the gas in question.
[0029] The results are shown in Table 1. In Table 1, `GN` is
guanidine nitrate, `BCN` is basic copper nitrate, and `CMCNa` is
sodium carboxymethyl cellulose.
1TABLE 1 Gas generating Amount of composition composition
(composition; mass %) (g) NO NO.sub.2 CO NH.sub.3 Example 1
GN/BCN/Al(OH).sub.3/CMCNa 39.4 7.6 0.0 95.8 24.1 (40.71/49.29/5/5)
Example 2 GN/BCN/Al(OH).sub.3/CMCNa 40.8 6.8 0.0 70.0 12.7
(36.98/48.02/10/5) Example 3 GN/BCN/Al(OH).sub.3/CMCNa 39.2 5.0 0.0
58.3 5.8 (42.78/44.72/10/2.5) Example 4 GN/BCN/Al(OH).sub.3/CMCNa
38.5 6.0 0.0 66.7 6.7 (45.1/43.4/10/1.5) Example 5
GN/BCN/Al(OH).sub.3/CMCNa 38.8 5.3 0.0 60.0 7.7
(43.94/44.06/10/2.0) Example 6 GN/BCN/Al(OH).sub.3/CMCNa 39.5 7.7
0.0 55.0 6.7 (41.62/45.38/10/3.0) The gas concentrations in the
table show the proportions in ppm in terms of mass out of the whole
gas.
[0030] The NO, NO.sub.2, CO and NH.sub.3 concentrations shown in
Table 1 are extremely low, and hence it was confirmed that
passenger safety upon inflation of an air bag through combustion of
the gas generating composition will be high.
* * * * *