JPH08151288A - Gas generating agent for air bag - Google Patents

Abstract

PURPOSE: To obtain a gas generating agent having excellent combustion performances, nondangerousness and remarkably low concentrations of toxic components in generated gases by including an organic compound containing nitrogen as a gas generating base, an oxidizing agent and a combustion catalyst having a specified specific surface area therein. CONSTITUTION: This gas generating agent for air bags is obtained by mixing (A) 100 pts.wt. organic compound containing nitrogen as a gas generating base with (B) 10-400 pts.wt. oxidizing agent and (C) a metallic oxide having >=5m<2> /g BET specific surface area as a combustion catalyst in an amount of about 0.1-50 pts.wt. based on 100 pts.wt. total amount of the organic compound containing the nitrogen and the oxidizing agent and, as necessary, (D) a detonation preventing agent, (E) a combustion velocity regulating catalyst, (F) a combustion temperature regulator, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air bag gas generating agent. More specifically, the present invention relates to a gas generating agent for an airbag, which has excellent combustion performance, is not dangerous in handling, and has a significantly low concentration of toxic components in the generated gas.

[0002]

2. Description of the Related Art With the ever-increasing demand for safety of automobiles, the demand for airbag systems is increasing dramatically. The airbag system is designed to inflate a nylon bag (airbag) mounted inside the steering wheel, dashboard, etc. when a car collides at high speed.
It is intended to prevent an occupant from crashing into and injuring each part in the vehicle, and the gas generated by combustion or decomposition of the gas generant loaded in the system is used for inflating the bag. .

It is desirable that the gas generating agent for an air bag mainly satisfies four requirements. The first requirement is "to have a proper burning rate". If the burning speed is slow, the bag will not expand instantly, and the occupant cannot be protected. The second requirement is that "impact ignitability (ignition sensitivity to impact) is low". If the impact ignitability is high, explosion and detonation are likely to occur in the manufacturing process such as mixing and molding, and the handling risk is high. The third requirement is "the gas temperature is low". The bag is
In order to escape the occupant to the outside of the vehicle, gas is released and contracts after expansion, but if the gas temperature is high, the occupant may be burned or the like. In addition, a hole may be formed in the bag to deteriorate its function, or the bag may burn to cause a fire. The fourth requirement is "the concentration of toxic components such as CO in the gas is low". If the concentration of toxic components is high, the occupant may become gas poisoned during gas release.

The azide-based gas generating agent having sodium azide as a gas generating base, which is widely used at present, has an appropriate burning rate and a relatively low gas temperature, and most of the gas is nitrogen gas. However, it has a drawback that its impact ignitability is considerably high. In addition, sodium azide, which is a gas generating base, decomposes to cause a fire or emits toxic fumes, and further reacts with oxidizing agents to produce toxic components such as sodium oxide and sodium hydroxide. Strict attention is always required, and equipment for ensuring safety is essential. In addition, sodium azide has a lower combustion performance due to moisture absorption, so it is necessary to take measures. In addition, since sodium azide is highly toxic, sodium azide may leak from vehicles equipped with airbags that have fallen into rivers or the sea, causing serious environmental pollution.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
JP-A-6-32690 and JP-A-6-2
Japanese Patent No. 27884 discloses a non-azide gas generating agent containing a nitrogen-containing organic compound and an oxidizing agent as active ingredients, which is proposed by the present inventor. The gas generating agent generates a large amount of gas, has an appropriate burning rate, has a low gas temperature and impact ignitability, has extremely low explosion risk and toxicity, and is inexpensive. Thus, CO in the gas generated from the azide-based gas generating agent
Although the concentration of toxic components such as is low enough for practical use,
Further reduction is desired.

According to JP-A-5-238867, a metal oxide having a specific surface area of 5 m ² / g or more (in particular, an oxide having an atomic number of 21 (Sc) to 30 (Zn)) is used as a gas generating agent. Is proposed. However,
The invention described in this publication relates to a gas generating agent using sodium azide as a gas generating base, and the metal oxide is added mainly for the purpose of improving the burning rate and ignitability. Further, in this publication, Fe ₂ O _{3 is the} only metal oxide whose effect is specifically disclosed.

[0007]

As a result of intensive studies to solve the above problems, the present inventor further blended a metal oxide having a specific BET specific surface area with the above non-azide gas generating agent. By doing so, it was found that the concentration of toxic components in the generated gas can be remarkably reduced while maintaining preferable properties as a gas generating agent, and the present invention has been completed here.

That is, according to the present invention, a gas generating agent containing a nitrogen-containing organic compound as a gas generating base and an oxidizing agent contains a metal oxide having a BET specific surface area of 5 m ² / g or more as a combustion catalyst. The present invention relates to a gas generating agent for an air bag.

The gas generating agent for an air bag of the present invention contains a nitrogen-containing organic compound as a gas generating base, an oxidizing agent, and a metal oxide having a BET specific surface area of 5 m ² / g or more as a combustion catalyst.

As the nitrogen-containing organic compound, an organic compound containing at least one nitrogen atom in the molecule is used.
Specifically, examples thereof include an amino group-containing organic compound, a nitramine group-containing organic compound, and a nitrosamine group-containing organic compound. Specific examples of the amino group-containing organic compound include, for example, azodicarbonamide, azodicarboxylic acid and its salts (alkali metal, alkaline earth metal, etc.), urea, hexamethylenetetramine, aminoguanidine bicarbonate, triaminoguanidine, biuret. , Cyanoguanidine, nitroguanidine, dicyandiamide, hydrazides and the like. Known hydrazides can be used here, for example, acetohydrazide, 1,2-diacetylhydrazide, lauric acid hydrazide, salicylic acid hydrazide, oxalic acid hydrazide, oxalic acid dihydrazide, carbohydrazide, adipic hydrazide, sebacic hydrazide. , Dodecanediohydrazide, isophthalic acid hydrazide, methyl carbazate, semicarbazide, form hydrazide, 1,2
-Diformyl hydrazine and the like. Specific examples of the nitramine group-containing organic compound include, for example, dinitropentamethylenetetramine, trimethylenetrinitroamine (RDX), tetramethylenetetranitroamine (H
Examples thereof include aliphatic compounds and alicyclic compounds having one to a plurality of nitramine groups as a substituent such as MX). Specific examples of the organic compound containing a nitrosamine group include, for example, one nitrosamine group as a substituent such as dinitrosopentamethylenetetramine (DPT).
Examples thereof include aliphatic compounds and alicyclic compounds having a plurality of compounds. Such nitrogen-containing organic compounds may be used alone or in combination of two or more. As the nitrogen-containing organic compound, a commercially available product may be used as it is. The shape, particle size, etc. of the nitrogen-containing organic compound are not limited, and may be appropriately selected according to various conditions such as the capacity of the airbag, the blending amount thereof, the blending ratio with each component, and the like.

The oxidizing agent is not particularly limited and may be appropriately selected from those conventionally used in the field.
Those capable of generating or supplying oxygen at a high temperature are preferable, and examples thereof include oxohalogenates, nitrates, nitrites, metal peroxides, superoxides and ozone compounds.

Known oxohalogenates can be used, and examples thereof include perhalogenates and halogenates. Specific examples of perhalogenates include, for example, lithium perchlorate, potassium perchlorate, sodium perchlorate, lithium perbromate, potassium perbromate, sodium perbromate, and other alkali metal salts, perchloric acid. Magnesium, barium perchlorate, calcium perchlorate, magnesium perbromate, barium perbromate, alkaline earth metal salts such as calcium perbromate, ammonium perchlorate, ammonium salts such as ammonium perbromate. To be Specific examples of the halogenate include, for example,
Lithium chlorate, potassium chlorate, sodium chlorate,
Alkali metal salts such as lithium bromate, potassium bromate, sodium bromate, etc., alkaline earth metal salts such as magnesium chlorate, barium chlorate, calcium chlorate, magnesium bromate, barium bromate, calcium bromate, chloric acid Examples thereof include ammonium salts such as ammonium and ammonium bromate. . Among these, alkali metal salts of halogen acids and perhalogen acids are preferable.

Examples of nitrates include lithium nitrate,
Examples thereof include alkali metal salts such as sodium nitrate and potassium nitrate, alkaline earth metal salts such as magnesium nitrate, barium nitrate and strontium nitrate, and ammonium salts such as ammonium nitrate. Of these, alkali metal salts are preferable.

Examples of nitrites include alkali metal salts such as lithium nitrite, sodium nitrite and potassium nitrite, and alkaline earth metal salts such as magnesium nitrite, barium nitrite and calcium nitrite. .

Examples of the metal peroxide include alkali metal salts such as lithium peroxide, sodium peroxide and potassium peroxide, alkaline earth metal salts such as magnesium peroxide, calcium peroxide and barium peroxide. be able to.

Examples of the superoxide include alkali metal compounds such as sodium superoxide and potassium superoxide, alkaline earth metal compounds such as calcium superoxide, strontium superoxide and barium superoxide, rubidium superoxide, cesium superoxide and the like. Can be mentioned.

Examples of ozone compounds include those represented by the general formula M
Examples thereof include compounds represented by O ₃ (wherein M represents a Group Ia element such as Na, K, Rb and Cs).

In the present invention, metal sulfides such as molybdenum disulfide, bismuth-containing compounds and lead-containing compounds can also be used as the oxidizing agent.

Of these oxidizing agents, oxohalogenates, nitrates, nitrites, metal peroxides and the like are preferable,
Oxohalogenates, nitrates and the like are particularly preferable.

Such oxidizing agents may be used alone or in combination of two or more. The shape and particle size of the oxidizing agent are not particularly limited, and may be appropriately selected and used according to various conditions such as the capacity of the airbag, the blending amount thereof, the blending ratio with each component, and the like.

The amount of the oxidizing agent to be compounded is usually a stoichiometric amount that can completely oxidize and burn the nitrogen-containing organic compound based on the amount of oxygen, but the compounding ratio of the nitrogen-containing organic compound and the oxidizing agent is appropriately selected. By changing the burning rate, burning temperature,
Since the combustion gas composition and the like can be adjusted arbitrarily, it may be appropriately selected from a wide range. For example, the nitrogen-containing organic compound 100
About 10 to 400 parts by weight, preferably about 100 to 240 parts by weight, of the oxidizer is preferably added to the parts by weight.

The gas generating agent of the present invention is used as a combustion catalyst.
BET specific surface area (simply as long as the following otherwise specified as "specific surface area") is 5 m ² / g or more, preferably 10 m ² /
It is essential to use a metal oxide having a large specific surface area of at least g, more preferably at least 40 m ² / g. The specific surface area in the present invention is measured by using a BET specific surface area measuring device (manufactured by Shimadzu Corporation).

The reason why a metal oxide having a large specific surface area brings about a remarkable effect is not fully clear, but it is presumed as follows. That is, in a non-azide gas generating agent using a nitrogen-containing organic compound as a gas generating base, there is a large difference between the thermal decomposition temperature of the nitrogen-containing organic compound and that of the oxidizing agent. With the addition of oxides,
The thermal decomposition temperature of the oxidant decreases and approaches that of the nitrogen-containing organic compound, and a smooth reaction occurs near the stoichiometric amount of both, and the metal oxide itself decomposes and excess oxygen is supplied to the combustion reaction system. It is assumed that this is due to things. Therefore, it is considered that the metal oxide plays various roles such as an agent for controlling the burning rate and the burning temperature, an oxidizing agent, and the like.

In addition, it is known that metal oxides such as CuO are effective for removing CO in exhaust gas from automobiles, etc., but the conventional technical idea is to remove CO in the gas generated after the combustion reaction. Therefore, the CO concentration is not reduced while directly related to the reaction in the combustion reaction system.

The metal oxide having a large specific surface area is not particularly limited as long as the specific surface area is in accordance with the above-mentioned regulation, but for example, copper oxide, nickel oxide, cobalt oxide, iron oxide, chromium oxide, magnesium oxide. , Aluminum oxide, zinc oxide, manganese oxide, and the like, oxides of elements of the 3rd to 4th periods of the periodic table, and among these, Group VIII elements such as copper oxide, nickel oxide, and cobalt oxide, and Group Ib elements are preferred, and copper oxide is particularly preferred. The metal oxides having a large specific surface area can be used alone or in combination of two or more. In the present invention, when two or more kinds of metal oxides are mixed and used, the mixed metal oxides have a specific surface area of 5 m ² / g or more, preferably 10 m ² / g.
Above, more preferably 40 m ² / g or more may be used.

The metal oxide having a large specific surface area can be produced by a known method. Taking copper oxide as an example, basic copper nitrate is added with warm water at 60 ° C. or higher to obtain fine particles of basic copper nitrate, which are crushed and then calcined at about 300 to 500 ° C. (JP-A-1-301513) Japanese Patent Laid-Open No. 2-145422), the copper nitrate particles produced by neutralizing an aqueous solution of copper nitrate by adding an alkaline agent are filtered, dried, and baked at about 200 to 500 ° C. (JP-A-2-145422). Etc.
A method using copper nitrate as a raw material can be mentioned. Also,
It can also be obtained by subjecting a metal hydroxide or carbonate to a low-temperature plasma treatment (JP-A-2-26810).

The shape, particle size and the like of the metal oxide having a large specific surface area are not particularly limited and may be appropriately selected according to various conditions such as the capacity of the airbag, the blending amount thereof and the blending ratio with each component. You can use it.

The compounding amount of the metal oxide having a large specific surface area is not particularly limited, and depends on various conditions such as the kind of the nitrogen-containing organic compound and the oxidizing agent, the compounding amount and the compounding ratio thereof, the air bag capacity and the like. Although it can be appropriately selected from a wide range, it is usually about 0.1 to 50 parts by weight, preferably 0.5 to 10 parts by weight based on 100 parts by weight of the total amount of the nitrogen-containing organic compound and the oxidizing agent.
It may be about part by weight.

In the present invention, the above-mentioned metal oxides having a specific surface area of less than 5 m ² / g can be used as a simple oxidizing agent or a burning rate controlling catalyst described later.

In the present invention, the gas generating agent for an air bag is compounded with an anti-detonation agent, a combustion speed control catalyst, a combustion temperature control agent, etc., in addition to the above essential components, within the range where the performance is not impaired. May be.

The detonation preventive agent is used to prevent the gas generating agent from being detonated by being caught in a flame or receiving a strong impact in the steps of manufacturing, transportation, storage and the like. . The addition of the detonation preventive agent can further enhance the safety in the steps of production, transportation, storage and the like. Known detonation inhibitors can be used, and examples thereof include bentonite, alumina, diatomaceous earth, oxides such as silicon dioxide, Na, K, Ca, Mg, and the like.
Examples thereof include carbonates and bicarbonates of metals such as Zn, Cu and Al. The compounding amount of the detonation inhibitor is not particularly limited and can be appropriately selected from a wide range, but it is usually about 5 to 30 parts by weight based on 100 parts by weight of the total amount of the nitrogen-containing organic compound and the oxidizing agent.

The burning rate control catalyst is used to control the burning rate. Examples of the combustion rate control catalyst include (a) zinc oxide, zinc carbonate, manganese oxide, iron chloride, lead oxide, titanium oxide, vanadium oxide, cerium oxide, holmium oxide, calcium oxide, ytterbium oxide, etc. To organic compounds such as oxides, chlorides, carbonates, sulfates of (6-periodic elements), (b) carboxymethyl cellulose, its ethers, cellulose compounds such as hydroxymethyl cellulose, (c) soluble starch, polyvinyl alcohol, partially saponified products thereof, etc. Polymer compounds and the like can be mentioned. The particle size of the catalyst is not particularly limited and may be appropriately selected and used. The above catalysts may be used alone or in combination of two or more. The amount of the above-mentioned catalyst is not particularly limited and can be appropriately selected from a wide range, but is usually about 0.1 to 50 parts by weight, preferably 0.2 to about 10 parts by weight based on 100 parts by weight of the total amount of the nitrogen-containing organic compound and the oxidizing agent. It may be about 10 parts by weight.

Combustion temperature modifiers are generally used to reduce combustion temperature and thus gas temperature. Specific examples of the combustion temperature adjusting agent include carbonates and bicarbonates of alkali metals and alkaline earth metals such as Na, K, Ca and Mg. The blending amount of the regulator is not particularly limited and may be appropriately selected from a wide range, but is usually within the range of not more than 50 parts by weight, preferably 20 parts by weight, based on 100 parts by weight of the total amount of the nitrogen-containing organic compound and the oxidizing agent. The range should not exceed the limit.

Further, in the present invention, various additives conventionally used for this purpose may be blended within a range that does not impair the preferable properties of the gas generating agent for an air bag.

The composition of the present invention can be produced by mixing a nitrogen-containing organic compound, an oxidizing agent, a metal oxide having a specific surface area and, if necessary, other components by a conventional method.

The composition of the present invention thus obtained can be further formulated into a suitable shape. For example, an appropriate amount of the composition of the present invention and a binder may be mixed, compressed and dried. At that time, it is particularly preferable for safety to add an appropriate amount of a solvent such as water. As the binder, those commonly used in this field may be used. The form of the preparation is not particularly limited, and examples thereof include pellets, discs, spheres, rods, hollow cylinders, sucrose, tetrapots, and the like. It may be a thing (for example, briquette-like thing).

The formulation of the composition of the present invention can be safely stored and transported by filling it in a bottle made of synthetic resin such as polyethylene.

In using the composition of the present invention, it goes without saying that the composition of the present invention can be used in accordance with a usual method, but each component of the composition of the present invention is formulated individually. However, these may be mixed and used.

The gas generating agent for an air bag of the present invention is not limited to automobiles and can be suitably used as a gas source for an air bag system mounted in various transportation equipment.

[0040]

According to the present invention, a gas generating agent for a non-azide type air bag, which uses a nitrogen-containing organic compound as a gas generating base, is prepared by adding a metal compound having a specific specific surface area. The preferable characteristics of the above non-azide type gas generating agent such as burning rate and gas generation amount equal to or higher than that of the generating agent, gas temperature and impact ignitability equal to or lower than that, high safety, low toxicity, and low cost. The concentration of toxic components such as CO in the generated gas can be remarkably reduced while maintaining it.

[0041]

EXAMPLES The present invention will be specifically described with reference to Examples and Comparative Examples below.

Example 1 45 parts by weight of azodicarbonamide, 5 parts of potassium perchlorate
Powders of 5 parts by weight, 10 parts by weight of copper oxide (specific surface area 48 m ² / g, average particle size of about 7.4 μm, manufactured by JGC Chemical Co., Ltd.) and 1.1 parts by weight of silicon dioxide were mixed well and mixed with this. 1 of soluble starch so that the starch content is 1.5 parts
A 0% aqueous solution was added and further mixed to produce a wet powder.
The wet powder is granulated by a granulator, the obtained wet granules are dried, and further pressed by a hydraulic tablet molding machine, and pellets of a gas generating agent (diameter 6 mm, thickness 3 mm, weight 0. 15
g) was produced.

30 g of the above-mentioned gas generant pellets were placed in the combustion chamber of an inflator equipped with gas ejection holes having a hole diameter of 6 mm and charged with 0.8 g of boron / potassium nitrate as a transfer charge.
Was filled. This inflator was set in a 60 liter tank and operated by passing an electric current, and then the gas in the tank was sampled from a sampling hole into a 1 liter Tedlar bag. When the CO concentration of this gas was measured using a detector tube, it was 0.8%.

Comparative Example 1 Specific surface area of 0.77 m ² / g and average particle size of about 4.5 μm
In the same manner as in Example 1 except that the general copper oxide used as the gas generating agent was used, pellets of the gas generating agent were produced.

As a result of operating in the same manner as in Example 1 using the pellets of this gas generating agent, the CO concentration was 1.5%.

From the above results, CuO having a large specific surface area
Clearly shows a significant effect in reducing the CO concentration in the gas.

Example 2 45 parts by weight of azodicarbonamide, 5 parts of potassium perchlorate
5 parts by weight, 10 parts by weight of a combustion catalyst having the composition shown in Table 1 below,
Powders of 1.1 parts by weight of silicon dioxide and 0.55 parts by weight of soluble starch were mixed well, and 0.2 g of this powder was mixed with a powder having a diameter of 6
mm die, 40kg / with a manual hydraulic press
The pellets of the gas generating agent of the present invention (diameter 6 mm, weight 0.2 g) were produced by pressing with a pressure of cm ² .

[0048]

[Table 1]

A combustion test was conducted on the obtained gas generating agent using the combustion test apparatus shown in FIG.

(1) A pellet of the gas generating agent is placed on the nichrome wire, and the device is assembled as shown in the figure.

(2) The inside of the Tedlar bag and the test tube is replaced with helium (300 ml / min for 10 minutes).

(3) Helium gas in the Tedlar bag is pushed out and discharged into the test tube, and the cock (not shown) of the bag is closed.

(4) Further, the helium gas remaining in the Tedlar bag is extracted with a gas syringe (not shown).

(5) The glass tube of the test tube is closed, and the three-way cock is adjusted so that the gas generated after combustion is discharged into the Tedlar bag.

(6) Stop the supply of helium gas and open the cock of the bag.

(7) An ignition busbar (not shown) is connected to the nichrome wire, and a pellet of the gas generating agent is ignited by a slider tag (not shown) and burned.

(8) The gas discharged into the Tedlar bag is analyzed by gas chromatography.

(9) Measure the amount of gas in the Tedlar bag with a gas syringe.

The results are shown in Table 2.

Comparative Example 2 Same as Example 2 except that copper oxide as a general gas generating agent having a specific surface area of 0.77 m ² / g and an average particle size of about 4.5 μm was used alone as a combustion catalyst. To produce pellets of the gas generant.

The pellets thus obtained were subjected to the same combustion test as in Example 2 and only the CO concentration was measured. Table 2 shows the results.

[0062]

[Table 2]

It can be seen from Table 2 that the combustion catalyst of the present invention and the combination thereof with other oxidants have a remarkable effect in reducing the CO concentration.

Example 3 No. 2 of Example 2. Example 1 except that the content of potassium perchlorate was increased by 5, 10 or 15% by weight and the content of soluble starch was 0.55 parts by weight using the combustion catalyst of No. 2
In the same manner as described above, pellets of the gas generating agent of the present invention were produced.

The obtained pellets were subjected to the same burning test as in Example 2. The results are shown in Table 3.

[0066]

[Table 3]

From Table 3, it can be seen that the CO concentration is further reduced by slightly increasing the amount of potassium perchlorate.

[Brief description of drawings]

FIG. 1 is a drawing showing an outline of an apparatus used for a combustion test of a gas generating agent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Onishi 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd.In the Tokushima Factory (72) Inventor Shigeru Oka, 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Tokushima Factory Co., Ltd.

Claims (4)

[Claims] 1. A gas generating agent comprising a nitrogen-containing organic compound as a gas generating base and an oxidizing agent, wherein a metal oxide having a BET specific surface area of 5 m ² / g or more is contained as a combustion catalyst. A gas generating agent for airbags. 2. The gas generating agent for an air bag according to claim 1, wherein the nitrogen-containing organic compound is at least one selected from an amino group-containing organic compound, a nitramine group-containing organic compound and a nitrosamine group-containing organic compound. . 3. The oxidizing agent is oxohalogenate, nitrate,
The gas generating agent for an airbag according to claim 1, which is at least one selected from nitrites and metal peroxides. 4. The metal oxide has a BET specific surface area of 5 m ² /
The gas generating agent for an airbag according to claim 1, which is at least one selected from g or more of copper oxide, nickel oxide and cobalt oxide.