JP2000226292A - Airbag gas-generating agent composition and formed body both for reducing injuriousness to crew and passenger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a cost and to simplify a structure by adopting a consolidate propellant-like gas-generating agent formed body where mild combustion occurs at the start and then furious combustion follows after that. SOLUTION: This formed body is adjusted so as to have a tank pressure of <=0.20×P kPa after 0.25×T milliseconds and of >=0.70×P kPa after 0.80×T milliseconds in the tank combustion test in a gas generator using the formed body, wherein P (kPa) is a preferred maximum tank pressure and T milliseconds is the period of time required from the start of a tank pressure to the arrival at the pressure of P (kPa). A nonazide-based gas-generating agent composition employed in the formed body is preferably the one comprising a nitrogen- including compound and an oxide and if needed, a binder and a slag-forming agent. The nitrogen-including compound is e.g. a tetrazole derivative, a guanidine derivative, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article of a gas generating composition which burns and supplies a gas component to inflate an air bag system, and a gas generator system for an air bag using the molded article. More specifically, the present invention relates to a novel molded article of a gas generating composition serving as a working gas in an airbag system provided for protecting a human body mounted on an automobile, an aircraft, and the like, and an air using the molded article. The present invention relates to a gas generator system for a bag.

[0002]

2. Description of the Related Art When a vehicle such as an automobile collides at a high speed, an occupant crashes into a hard part inside the vehicle, such as a steering wheel or a front glass, due to inertia, resulting in injury or death. To prevent this, airbag systems have been developed that rapidly inflate the bag with gas to prevent occupants from hitting dangerous places. The demands on the gas generating agent used in this airbag system are very severe, such as that the bag inflation time is very short, usually within 40 to 50 milliseconds, and that the gas after combustion is harmless to the human body. .

At present, as a gas generating base generally used for an air bag system, an inorganic azide compound, particularly sodium azide can be mentioned. Sodium azide is excellent in terms of flammability, but an alkali component by-produced during gas generation is toxic, and does not satisfy the above requirements in terms of safety for passengers. Also,
Since the substance itself is toxic, there is a concern about the environmental impact of disposal.

[0004] In order to compensate for these drawbacks, some so-called non-azide gas generating agents have been developed in place of sodium azide. For example, JP-A-3-2088878 discloses a composition containing, as main components, tetrazole, triazole or a metal salt thereof and an oxygen-containing oxidizing agent such as an alkali metal nitrate. In addition,
JP-A-6156 and JP-B-64-6157 disclose a gas generating agent containing a metal salt of a bitetrazole compound containing no hydrogen as a main component.

Further, Japanese Patent Publication No. 6-57629 discloses a gas generating agent containing a transition metal complex of tetrazole and triazole. JP-A-5-254977 discloses a gas generating agent containing triaminoguanidine nitrate, JP-A-6-239683 discloses a gas generating agent containing carbohydrazide, and JP-A-7-61885 discloses acetic acid. A gas generant comprising cellulose and a nitrogen-containing non-metallic compound such as nitroguanidine is disclosed. Further, U.S. Pat. No. 5,125,684 discloses the use of nitroguanidine as an energetic material coexisting with 15-30% of a cellulosic binder. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent No. 265292 discloses a gas generating composition in which a tetrazole or triazole derivative is combined with an oxidizing agent and a slag forming agent.

[0006] Regarding the gas generation behavior and bag inflation behavior according to these prior arts, particularly on the driver's seat (hereinafter abbreviated as D seat) side, the seating position of the occupant is relatively fixed, so that the conventional inflation behavior performance is sufficiently safe. Has been believed to be. However, as the airbag system is widely used and approaches standard equipment, there are hundreds and hundreds of people with high or low sitting heights, people who are holding on to the steering wheel, etc. even on the D seat side, and passengers such as passenger seats There are various types of seats (hereinafter abbreviated as P seats), such as when a child or the like is to be boarded, and thus there has been a demand for the development of a safer airbag system.

[0007] That is, although the conventional inflation behavior performance can be used, in order to make the airbag system safer, the initial inflation speed, for example, from the start of gas generation on the D seat side.
The expansion rate during 10 milliseconds is made slower than before,
Eliminate the harm caused by the initial bag inflation
A technique for maintaining sufficient occupant restraint after about 70 milliseconds has been desired, and a technique for similarly controlling the gas generation behavior on the P seat side has been desired.

[0008] As such a technique, Japanese Patent Application Laid-Open No. 8-207 is disclosed.
No. 696 discloses a technique in which gas is generated in two stages, the bag is inflated relatively slowly in the initial stage of operation, and rapid gas generation is performed in the second stage. In general, such a system is called a dual output system or a smart airbag system, and has attracted attention as a system for reducing harm to occupants, and is currently being developed. However, this type of technology requires two ignition mechanisms, so two expensive electric detonators and the like are required, which increases the cost.In addition, the structure inside the gas generator becomes complicated and the size of the container becomes large. However, there is a disadvantage that the size becomes larger.

[0009]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by using a consolidate propellant-like gas generating agent molded article. The invention has been completed.

That is, the present invention relates to a molded article of a consolidate propellant-like gas generating agent, characterized in that the combustion starts gently at first and then burns violently, and the molding thereof. It provides the body.

The present invention also relates to a gas generator system for an air bag using such a molded product, wherein a desired tank maximum pressure is set to P (K) in a tank combustion test using the gas generator.
Pa), tank maximum pressure P (K
When the time to reach (Pa) is T milliseconds, the tank pressure after 0.25 × T milliseconds is 0.20 × P (KPa) or less and 0.80
An object of the present invention is to provide a gas generator system for an air bag, wherein the tank pressure after × T milliseconds is 0.70 × P (KPa) or more.

[0012]

Embodiments of the present invention will be described below in detail.

The molded article of the gas generating composition for an airbag of the present invention is characterized in that the tank maximum pressure is set to P (KPa) in a tank combustion test by a gas generator using the molded article, and the pressure is measured from the start of the tank pressure rise. When the time to reach the ink maximum pressure P (KPa) is T milliseconds, the tank pressure after 0.25 × T milliseconds is 0.20 × P (KPa) or less, and the tank pressure after 0.80 × T milliseconds is 0.70 X P (KPa) or more.

The tank pressure after 0.25 × T milliseconds is 0.20 × P
(KPa), the initial momentum of the inflation of the bag may be too large, causing harm to the occupant.If the tank pressure after 0.80 × T milliseconds is less than 0.70 × P (KPa), The safety of the occupant in the event of a collision cannot be ensured.

The molded article of the present invention has the above-mentioned features, and this can be realized by using a consolidated propellant-like gas generating agent molded article.

The consolidate propellant is obtained by pressing and compressing a normal grain propellant into an apparent block shape. This is described in, for example,
As disclosed in 139578, it is a propellant having the characteristics of suppressing the rise of the initial burning rate and pressure and increasing the bulk density and compressive strength, and is a propellant used only in defense relations. is there. If this combustion characteristic is used for a gas generator for an airbag, occupant harmfulness can be reduced.

Heretofore, pellets have been generally used for molded articles of gas generating agents for airbags. When the pellets are burned, they have the characteristic that the surface area in the initial stage of combustion is the largest, the surface area is reduced as the burning progresses, and the pellets are burned out at the end. Therefore, a relatively large amount of gas is generated when the pellet is ignited, and the gas has a combustion characteristic that the gas amount decreases as the combustion approaches the end. This means that the airbag pops out violently in the early stage of inflation of the airbag, which is not a problem for an occupant sitting in an appropriate seating position, but is not a problem for an occupant or body sitting in an inappropriate seating position. Could be harmed to small occupants of the country.

In order to reduce such harmful effects, it can be said that the combustion surface area of the molded article of the gas generating composition should be controlled so as to increase as the combustion proceeds.
That is, this means that the amount of gas generated relatively increases as the combustion proceeds.

In practice, this can be realized by using the consolidate propellant-like gas generating agent molded product described above. Since such a molded body is compacted, the combustion surface area is initially small, and the propagation of the flame is also poor, so that the desired combustion characteristics are exhibited.

Therefore, it is possible to control only the initial ignition stage without a time delay until the maximum pressure is reached. It should be appreciated that the technique of the present invention is fundamentally different in this respect from the so-called depower technique in which the overall gas generation output is slightly reduced and the initial stages are controlled.

The molded article of the gas generating agent according to the present invention is characterized in that it is in the form of a consolidate propellant, and can be produced basically by the same method as that for producing a consolidate propellant. The drawn medicine (non-porous, single-hole, porous) manufactured by extrusion using a drawing machine (extrusion molding machine) is further pressed and compacted to form a consolidate propellant.

The bulk density of the consolidate propellant gas generating agent molded article of the present invention is preferably 1.0 to 1.5 g / cm3.

As a method of consolidating (compacting), as is conventionally known, a drawn medicine is impregnated with a solvent, swollen and then consolidated, and then the solvent is removed in a drying step. There is a way to do that. However, since a solvent is always used at the time of producing a drawn medicine, a method of consolidating immediately after cutting is completed, and then drying may be used.

Further, a method of mixing a non-volatile binder solution dissolved in a solvent with a drawing agent and removing the solvent after consolidation can be used. The non-volatile binder used at this time may be at least one selected from organic binders such as sodium salt of carboxymethyl cellulose, guar gum, polyvinyl alcohol, and polyacrylamide; and plastic resins such as polystyrene and polybutadiene.

Next, the non-azide gas generating composition used in the present invention will be described.

The non-azide gas generating composition used in the present invention preferably comprises a nitrogen-containing compound and an oxidizing agent. Further, a binder and a slag forming agent can be contained.

The nitrogen-containing compounds used in the present invention include guanidine derivatives, tetrazole derivatives, bitetrazole derivatives, triazole derivatives, hydrazine derivatives, triazine derivatives, azodicarbonamide derivatives,
One or two selected from the group consisting of dicyanamide derivatives
Mixtures of more than one species. Specific examples of these include nitroguanidine, guanidine nitrate, 5-aminotetrazole, bitetrazole diammonium salt, 5-oxo-1,2,4-triazole, cyanoguanidine,
Examples thereof include triaminoguanidine nitrate, trihydrazinotriazine, biuret, azodicarbonamide, biurea, carbohydrazide, carbohydrazide nitrate complex, oxalic acid dihydrazide, hydrazine nitrate complex, and sodium dicyanamide.

Among these nitrogen-containing compounds, one or two or more selected from the group consisting of a tetrazole derivative and a guanidine derivative are preferable, and particularly, nitroguanidine,
Guanidine nitrate, cyanoguanidine, and 5-aminotetrazole are preferred.

The mixing ratio of the nitrogen-containing compound in the gas generating composition according to the present invention varies depending on the number of carbon elements, hydrogen elements and other oxidizable elements in the molecular formula. The range is preferable, and the range of 12 to 50% by weight is particularly preferable.

Various oxidizing agents can be used for the gas generating composition according to the present invention.

Examples of the oxidizing agent include one or more selected from oxyacid salts, metal oxides and metal double oxides.

Examples of the oxyacid salt include ammonium, alkali metal, alkaline earth metal, alkaline earth metal complex, transition metal and nitrate, nitrite, chlorate or perchlorate of the transition metal complex. .

Examples of such oxyacid salts include ammonium nitrate, alkali metal salt or alkaline earth metal salt such as ammonium nitrate, sodium nitrate, potassium nitrate, magnesium nitrate and strontium nitrate; ammonium nitrite, sodium nitrite; Potassium nitrite,
Ammonium nitrite, alkali metal salt or alkaline earth metal salt such as magnesium nitrite and strontium nitrite; ammonium chlorate such as ammonium chlorate, sodium chlorate, potassium chlorate, magnesium chlorate and barium chlorate Salt, alkali metal salt or alkaline earth metal salt; ammonium perchlorate such as ammonium perchlorate, sodium perchlorate, potassium perchlorate, magnesium perchlorate, barium perchlorate, alkali metal salt or alkali Earth metal salt; Mg (N2H4) 2 (NO3) 2, Mg (N2
Nitrates and perchlorates of alkaline earth metal complexes such as H4) 2 (ClO4) 2; Cu (NO3) 2.3Cu (OH) 2, Cu2 (OH) 3 (NO3), Co2 (OH) 3
(NO3), nitrates of transition metals such as Mn (OH) 2 (NO3); Co (NH3) 3
(NO3) 3, Co (NH3) 6 (NO3) 3, Cu (NH3) 2 (NO3) 2, Co (NH3) 3 (N
Examples include nitrates, nitrites, and perchlorates of transition metal complexes such as O2) 3 and Co (NH3) 6 (ClO4) 3.

As the metal oxide and the metal double oxide,
Oxides or double oxides of copper, cobalt, iron, manganese, nickel, zinc, molybdenum and bismuth.

Examples of such metal oxides and metal double oxides include CuO, Cu2O, Co2O3, and Co2O3.
O, Co3O4, Fe2O3, FeO, Fe3O4, M
nO2, Mn2O3, Mn3O4, NiO, ZnO, M
oO3, CoMoO4, Bi2MoO6 or Bi2O3
Can be mentioned.

The mixing ratio of the oxidizing agent in the gas generating composition according to the present invention varies in absolute value depending on the kind and amount of the gas generating compound used, but is preferably in the range of 40 to 90% by weight, more preferably 50 to 88% by weight. Is particularly preferred.

As the binder in the gas generating composition according to the present invention, any binder can be used as long as it does not significantly affect the combustion behavior of the composition. Specific examples of the binder used in the present invention include metal salts of carboxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, polyvinyl alcohol, polyacrylamide, starch and the like. And organic binders such as calcium stearate.

In the present invention, it is very effective to add an appropriate amount of a binder to the gas generating composition. When the binder is added, the compounding ratio is preferably in the range of 3 to 15% by weight. The larger the amount, the stronger the breaking strength of the molded body. However, the larger the amount, the greater the number of carbon elements and hydrogen elements in the composition, and a small amount of C, which is an incomplete combustion product of carbon elements.
It is not preferable because the concentration of the O gas increases and the quality of the generated gas deteriorates. In particular, when the amount exceeds 15% by weight, the relative proportion of the oxidizing agent must be increased, and the relative proportion of the gas generating compound decreases, making it difficult to establish a practical gas generator system.

The function of the slag forming agent in the gas generant composition according to the present invention is as follows. The slag forming agent in the gas generant composition, in particular, the oxide of alkali metal or alkaline earth metal generated by the decomposition of the oxidant component is used as a mist. It is a function to change from liquid to solid and stop it in the combustion chamber in order to avoid discharge to the outside of the inflator. It is possible to select a slag forming agent optimized by the difference in metal components.

Specific examples of the slag forming agent include naturally occurring clay mainly composed of aluminosilicates such as acid clay, silica, bentonite and kaolin; and artificial clays such as synthetic mica, synthetic kaolinite and synthetic smectite. Slag forming agent selected from at least one of alumina clay, ceramic fiber, glass fiber, etc .; Among them, acidic clay, alumina and silica are preferred.

In the present invention, a slag forming agent is not essential, but adding an appropriate amount to the gas generating composition is very effective. The mixing ratio when adding a slag forming agent is 1-2.
0% by weight, but preferably 3%.
-15% by weight. If the amount is too large, the linear burning rate and the gas generation efficiency will decrease. If the amount is too small, the slag forming ability cannot be sufficiently exhibited.

Next, a gas generator system for an air bag according to the present invention will be described.

The gas generator system of the present invention uses the molded body obtained as described above, sets the desired tank maximum pressure to P (KPa) in the tank combustion test using the gas generator, and sets the tank pressure from the start of the tank pressure rise. When the time to reach the maximum pressure P (KPa) is T milliseconds, the tank pressure after 0.25 × T milliseconds is 0.20 × P (KPa) or less, and the tank pressure after 0.80 × T milliseconds is 0.70 × P (KPa) or more.

Although the structure of the gas generator system according to the present invention is not particularly limited, a housing having a plurality of gas discharge ports, an ignition means provided in the housing, and an ignition means provided by the ignition means Gas generating means for generating combustion gas, a combustion chamber containing the gas generating means, and a filter means for cooling the combustion gas and collecting combustion residues, the outer periphery of the filter means of the housing It is preferable to be installed so as to face the inner surface of the outer peripheral wall and form a gap between the two.

In the gas generator system according to the present invention, the tank maximum pressure P (KPa) and the time T milliseconds from the start of the rise of the tank pressure to the arrival of the tank maximum pressure P (KPa) are the tank maximum pressure P (KPa). (KPa) is 110-220 (KPa), and the time T from the start of tank pressure rise to the arrival of the tank maximum pressure P (KPa) is 30-50 milliseconds. This technology is described in
It is not limited to the seating system. For example, the maximum pressure P (KPa) is 350 to 500 (KPa), and the time T from the start of the rise of the tank pressure to the arrival of the tank maximum pressure P (KPa) is 50 to 70.
It can be applied to the gas generator system for P (passenger) seat which is millisecond.

[0046]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0047]

[Comparative Example 1] Nitroguanidine (55.1 parts) (parts shown below are parts by weight) and strontium nitrate (44.9 parts) with openings of 300 μm
m using a sieve. Using a hand press, this mixed powder was 9.6 m in outer diameter under a pressure of 100 kg / cm2.
m, a pellet having a length of 3.6 mm was prepared.

The obtained gas generating agent molded body was attached to a small tank having a capacity of 1.04 liter, and at room temperature under a pressure of 100 kg / c.
It was burned in a nitrogen atmosphere at m2. Pressure obtained in the test ~
The time curve is shown in FIG.

Here, the tank maximum pressure was set to 100%, and the time from the start of the tank pressure rise to the arrival of the tank maximum pressure was set to 100% so that the characteristics of the combustion curve could be easily seen.

As is clear from FIG. 1, in this test,
It can be seen that the initial pressure rise speed is high and the combustion curve is highly harmful.

[0051]

Example 1 To 31 parts of nitroguanidine, 54 parts of strontium nitrate, 5 parts of acid clay and 10 parts of sodium carboxymethylcellulose, water equivalent to 18 parts with respect to the total amount of the composition was added and mixed and kneaded. Next, the kneaded mixture is passed through a mold having an outer diameter of 2.5 mmφ and an inner diameter of 0.80 mmφ, and a pressure of 80 kg / cm2.
Under the pressurized condition of above, a single-hole cylindrical string was extruded.
Further, the string was cut into a length of 3.0 mm by a cutting machine.

Then, 3.9 g of this single-hole drawn product was placed in a plastic container having small holes at several locations, covered under pressure, and stored in a desiccator containing silica gel for one day. The consolidated molded body from which water was partially removed was taken out and sufficiently dried with a dryer at 80 ° C.

The molded body after drying is 3.4 g and has a diameter of 20 mm.
φ, height 8 mm. The bulk density is 1.3 g / cm
It was 3.

The obtained molded article of the gas generating agent was burned under the same conditions as in Comparative Example 1. The pressure-time curve obtained in the test is shown in FIG.

As is clear from FIG. 1, the initial tank pressure rise rate is gentler than that in Comparative Example 1, and it is understood that the combustion curve has a low aggressiveness.

[Brief description of the drawings]

FIG. 1 is a pressure-time curve obtained in the tests of Comparative Example 1 and Example 1.

Claims (10)

[Claims] 1. An airbag gas generant composition comprising a consolidate propellant-like gas generant, wherein the composition starts burning gently at first and burns violently thereafter. 2. A molded article of a gas generating composition for an airbag, wherein a desired tank maximum pressure is P (KPa) in a tank combustion test by a gas generator using the molded article, When the time to reach the tank maximum pressure P (KPa) is T milliseconds, the tank pressure after 0.25 × T milliseconds is 0.20 × P (KPa) or less, and the tank pressure after 0.80 × T milliseconds is 2. The molded article of the gas generating composition for an airbag according to claim 1, wherein the pressure is adjusted so as to be 0.70 * P (KPa) or more. 3. The molded article according to claim 1, wherein the gas generating composition comprises a nitrogen-containing compound and an oxidizing agent. 4. The molded article according to claim 3, further comprising a binder. 5. The molded article according to claim 3, further comprising a slag forming agent. 6. The nitrogen-containing compound is at least one member selected from the group consisting of guanidine derivatives, tetrazole derivatives, bitetrazole derivatives, triazole derivatives, hydrazine derivatives, triazine derivatives, azodicarbonamide derivatives and dicyanamide derivatives. The molded article according to claim 3, wherein 7. A gas generator system for an airbag using the molded product according to claim 1, wherein
In a tank combustion test using a gas generator, when the desired tank maximum pressure is P (KPa), and the time from the start of tank pressure rise to the tank maximum pressure P (KPa) is T milliseconds,
The tank pressure after 0.25 × T milliseconds is 0.20 × P (KPa) or less, and the tank pressure after 0.80 × T milliseconds is 0.70 × P (KPa)
A gas generator system for an airbag characterized by the above. 8. A gas generator, comprising: a housing having a plurality of gas discharge ports; ignition means disposed in the housing; gas generation means ignited by the ignition means to generate combustion gas; A combustion chamber accommodating the gas generating means, and a filter means for cooling the combustion gas and collecting combustion residues, an outer periphery of the filter means opposing an inner surface of an outer peripheral wall of the housing; The gas generator system for an airbag according to claim 7, wherein the gas generator system is installed so as to form a gap therebetween. 9. The maximum tank pressure P (KPa) is 110 to 220 (KPa).
The tank maximum pressure P (KP
9. The gas generator system for an air bag according to claim 7, wherein a) a time T until arrival is 30 to 70 milliseconds. 10. The maximum tank pressure P (KPa) is 350 to 500 (KPa).
The tank maximum pressure P (KP
9. The gas generator system for an air bag according to claim 7, wherein a) the time T until arrival is 50 to 90 milliseconds.