JPH0987079A - Gas generating agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas generating agent compsn. capable of remarkably reducing the amt. of cyanides generated as harmful components in residue while maintaining satisfactory performance as an element of an air bag system for an automobile. SOLUTION: In a gas generating agent compsn. contg. dicyandiamide, an oxygen-contg. inorg. oxidizing agent and an inorg. compd. contg. at least one of groups I, II, III, IV, V, VI, VII and VIII elements of the Periodic Table as essential components, the weight ratio of the oxygen-contg. inorg. oxidizing agent to the dicyandiamide is regulated to 1.01-1.50 when the weight ratio of an oxygen-contg. inorg. oxidizing agent contg. the theoretical amt. of oxygen required to perfectly convert dicyandiamide into nitrogen, water and CO2 after burning to dicyandiamide is regulated to 1.00.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas generant composition, and more particularly to a non-azide type gas generant composition which is burned to supply a gas component in order to expand an airbag system for an automobile.

[0002]

2. Description of the Related Art When a vehicle such as an automobile collides at a high speed,
In order to prevent passengers from injuring or dying due to inertia causing collisions with hard or dangerous parts inside the vehicle such as the steering wheel and windshield, the gas generated from the gas generating agent rapidly inflates the bag. Airbag systems are being developed. The requirements for gas generants suitable for automotive airbag systems are very stringent. First, the bag inflation time is required to be very short, usually within 40 to 50 milliseconds. In addition, as the atmosphere inside the bag,
The atmosphere that corresponds to the air composition in the car is optimal. Alkali metal salts and alkaline earth metal salts of hydrazoic acid, which are generally used at present, particularly gas generating agents using sodium azide as a gas generating base are excellent ones satisfying the above conditions. is there. However, the gas generating agent has a serious drawback that sodium azide which is a main component and an alkaline component which is a by-product during gas generation have toxicity,
Environmental pollution due to mass disposal of vehicles equipped with airbag systems,
There is concern about health problems for passengers when gas is generated.

In order to solve the above problems, development of a non-azide type gas generating agent replacing the sodium azide type has been carried out. For example, in Japanese Patent Laid-Open No. 3-208878,
A composition containing a nitrogen-containing organic compound composed of tetrazole, triazole or a metal salt thereof and an oxygen-containing oxidizing agent of an alkali metal nitrate such as sodium nitrate as main components is disclosed. However, it is known that cyanide, which is extremely toxic to the human body, is generated by the reaction between cyanide generated from these nitrogen-containing organic compounds and alkali metal generated by thermal decomposition of alkali metal nitrate. On the other hand, JP-B-64-6156 and JP-B-64-6157 disclose gas generating agents containing a hydrogen-free metal salt of a bitetrazole compound as a main component. Furthermore,
JP-A-3-208878 discloses a gas generating agent containing a transition metal complex of aminoarazole as a main component. The non-azido compounds found in the above series of prior arts always have carbon and nitrogen atoms in their structure,
All of them produce a large amount of cyanide, which is harmful to the human body, and do not have satisfactory performance in terms of bag inflation time.

[0004]

In the combustion of a nitrogen-containing organic compound, the amount of an oxidant that generates the amount of oxygen necessary for the combustion of carbon, hydrogen and combustible elements in the nitrogen-containing organic compound, that is, the chemical equivalent amount. It is well known that undecomposed compounds are generated as incomplete combustion products even with the use of the above oxidants. In particular, compounds such as tetrazole compounds and dicyandiamide have a carbon-nitrogen double bond or triple bond in the structure, and can remain in an undecomposed state during combustion decomposition, that is, a free cyano group. It is highly likely. In addition, as the oxygen-containing inorganic oxidizer containing oxygen required for combustion, those used as compounds with relatively excellent combustibility and stability are similar to alkali metal nitrates such as NaNO ₃ and KNO ₃ and KClO ₄ . Is an alkali metal salt peroxide,
Most of them contain an alkali metal. Oxygen-containing inorganic oxidizer containing alkali metal decomposes during combustion and changes to alkali metal oxide or alkali metal salt, but since the combustion temperature is very high, it is considered that it is further decomposed and exists as the alkali metal simple substance. To be As a result, the cyano group that remains in an undecomposed state and the alkali metal simple substance that has been further decomposed react and become stable, and finally remain as a toxic residue. In the future, the demand for airbags will increase, and it can be said that the reduction of cyanide in the residue must be urgently solved in order to prevent environmental pollution caused by the large-scale disposal of vehicles equipped with airbag systems.

[0005]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, surprisingly,
It was found that the cyanide in the generated residue can be reduced while maintaining the inflator combustion performance by adjusting the addition amount of the oxygen-containing inorganic oxidizing agent in the gas generating composition to a certain range, and the present invention Completed That is, the present invention provides a dicyandiamide, an oxygen-containing inorganic oxidizing agent, and a periodic table group I, group II, group III, group IV, group V, group
In a gas generant composition containing an inorganic compound containing at least one element of Group VI, Group VII, and Group VIII as an essential component, after dicyandiamide is burned, it is completely changed to nitrogen, water, and carbon dioxide. When the weight ratio of the oxygen-containing inorganic oxidant containing the stoichiometric amount of oxygen required for dicyandiamide is 1.00, the weight ratio of the oxygen-containing inorganic oxidant to dicyandiamide in the composition is 1.01.
There is provided a gas generant composition characterized by being in the range of 1.50.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The gas generating composition of the present invention comprises a dicyandiamide, an oxygen-containing inorganic oxidizing agent, and a periodic table group I, group II.
Group, Group III, Group IV, Group V, Group VI, Group VII, Group
An inorganic compound containing at least one element of Group VIII elements is an essential component.

As the oxygen-containing inorganic oxidizing agent used in the present invention, conventionally known ones such as nitrates, nitrites and oxyhalogenates can be widely used. Specifically, potassium nitrate, sodium nitrate, strontium nitrate, potassium nitrite, sodium nitrite, sodium perchlorate, potassium perchlorate, strontium perchlorate, sodium chlorate, potassium chlorate and the like, Preferred are potassium nitrate, sodium nitrate, strontium nitrate, sodium perchlorate, potassium perchlorate, and strontium perchlorate. These oxygen-containing inorganic oxidizing agents can be used alone or in combination.

Periodic Table Group I, Group II used in the present invention
Group, Group III, Group IV, Group V, Group VI, Group VII, Group
The inorganic compound containing at least one element of the group VIII elements includes copper, calcium, barium, zinc, boron, cerium, ytterbium, titanium, lead, vanadium, antimony, molybdenum, manganese, iron, cobalt and nickel. Inorganic compounds containing at least one element selected from the group are mentioned, and specifically, CuO, C
u ₂ O, CaO ₂ , Ba ₂ O ₃ , ZnO, ZnCO ₃ , B ₂ O ₃ , CeO ₂ , Yb ₂ O ₃ , T
iO ₂ , Pb ₃ O ₄ , PbO ₂ , PbO, V ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , MnO ₂ , F
Examples include eCl ₃ , Co ₃ O ₄ , and NiO. Among these inorganic compounds, inorganic compounds containing at least one element selected from the group consisting of copper, lead and molybdenum, specifically CuO, Cu ₂ O, Pb ₃ O ₄ , PbO ₂ , PbO ₂ and MoO. ₃ is preferred.

Regarding the mixing ratio of the dicyandiamide and the oxygen-containing inorganic oxidant in the gas generant composition of the present invention, the stoichiometry required to completely convert the dicyandiamide into nitrogen, water and carbon dioxide after combustion. When the weight ratio of the oxygen-containing inorganic oxidizing agent containing oxygen to dicyandiamide is 1.00, the weight ratio of the oxygen-containing inorganic oxidizing agent to dicyandiamide in the composition is in the range of 1.01 to 1.50,
It should preferably be in the range of 1.05 to 1.30. When the weight ratio is less than 1.01, the amount of cyanide generated increases rapidly, and when it exceeds 1.50, the combustion performance required for airbag deployment is not reached.

There are mainly two reasons why the amount of cyanide generated is reduced by the present invention. One is that the amount of oxygen-containing inorganic oxidant added was increased to increase the amount of oxygen generated during combustion and to accelerate the oxidative decomposition reaction of dicyandiamide, resulting in a decrease in free cyano groups. The other is reduction of cyanide to alkali metal. In this combustion reaction, a simple metal itself derived from the oxygen-containing inorganic oxidant is generated due to high temperature combustion, and it has a function of stabilizing the cyano group generated as an undecomposed product of dicyandiamide as an alkali metal cyanide. On the other hand, in the composition of the present invention, the proportion of dicyandiamide in the total amount of the gas generant is reduced as compared with the stoichiometric composition, the heat of decomposition and decomposition per a certain amount of the composition is reduced, and the combustion temperature is significantly lowered. Generation of a simple substance is suppressed and the metal oxide or metal salt is stabilized in the state. Therefore, the free cyano group does not stabilize as cyanide and is oxidatively decomposed to reduce the amount of cyanide.

Periodic Table I in the composition of the present invention
Group, Group II, Group III, Group IV, Group V, Group VI, Group VI
An inorganic compound containing at least one element of Group I and Group VIII acts as a catalyst. The content of these inorganic compounds in the composition of the present invention is not particularly limited, 1-30
% By weight, preferably 3 to 20% by weight, more preferably 3 to
It is in the range of 10% by weight. Inorganic compound content is 30% by weight
If the amount is larger, the amount of gas generated per unit weight of the gas generant composition decreases, which is not preferable. On the other hand, if the content is less than 1% by weight, it affects combustion performance and generation of cyanide compound, which is not preferable.

The composition of the present invention may further contain a binder, silica or the like for the purpose of improving the molding strength of the gas generating composition. As the binder, for example, microcrystalline cellulose binder such as trade name Avicel,
Polymer binders such as Poval, organic binders such as starch, and inorganic binders such as silica sol, alumina sol and zirconia sol can also be used. The composition of the present invention is produced by mixing the above components. The obtained mixture may be used as it is as a gas generating agent, but it is preferably formulated and used. A usual known method can be applied for formulation, and a binder can be appropriately selected. The shape of the preparation is not particularly limited, and for example,
Examples include pellets, disks, spheres, sucrose, tetrapots, and the like. Further, the preparation may be non-porous or porous (for example, briquette-like or ring-like).

[0013]

EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which are not intended to limit the present invention. Unless otherwise specified, the compounding ratios shown in Examples and Comparative Examples are all by weight.

Example 1 24 parts of dicyandiamide, 76 parts of potassium nitrate, and 10 parts of copper oxide were mixed well, and a 5% aqueous solution of Poval was added in an amount of 0.2 parts to further mix to obtain a wet powder. It was The weight ratio of potassium nitrate to dicyandiamide in the composition is such that after the dicyandiamide is completely burned, nitrogen, water,
It was 1.12 when the weight ratio of potassium nitrate containing the stoichiometric amount of oxygen required for conversion to carbon dioxide to dicyandiamide was 1.00. Next, after adjusting the fineness and moisture content convenient for molding, press with a hydraulic tablet molding machine at a pressure of about 800 kg / cm ² into pellets (5.0 mmφ ×
(1.5 mm), put it in a combustor with a filter and coolant together with an igniter, fix it in a 60 liter non-expandable metallic tank, seal the tank, ignite the composition to burn. Then, the combustion pressure and the combustion time were measured. The combustion pressure and the combustion time showed desired values. Regarding the cyanide concentration, disassemble the inflator after combustion, immerse all parts in a container containing 5 liters of pure water, immerse the container in an ultrasonic cleaner for 30 minutes, and then sonicate for 24 hours. I left it. 500 ml of this inflator wash water
Was collected and quantitatively analyzed for the total amount of cyanide ions according to the JIS KO102 factory drainage test method. As a result, a value of 0.19 ppm was shown.

Example 2 The cyan concentration in the residue in the inflator container after combustion was evaluated in exactly the same manner as in Example 1 except that the addition amounts were changed to 25.5 parts of dicyandiamide and 74.5 parts of potassium nitrate. The weight ratio of potassium nitrate to dicyandiamide in the present composition is 1 to the weight ratio of potassium nitrate to dicyandiamide containing a stoichiometric amount of oxygen necessary to completely convert dicyandiamide into nitrogen, water and carbon dioxide. At that time, it was 1.03. The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitatively analyzing the total amount of cyanide ions in the same manner as in Example 1, it was 0.27.
The value of ppm is shown.

Example 3 The cyan concentration in the residue in the inflator container after combustion was evaluated in exactly the same manner as in Example 1 except that the addition amounts were changed to 20 parts of dicyandiamide and 80 parts of potassium nitrate. The weight ratio of potassium nitrate to dicyandiamide in the present composition is 1 to the weight ratio of potassium nitrate to dicyandiamide containing a stoichiometric amount of oxygen necessary to completely convert dicyandiamide into nitrogen, water and carbon dioxide. At that time, it was 1.41. The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitatively analyzing the total amount of cyanide ions in the same manner as in Example 1, it was
Values below m were shown.

Comparative Example 1 The cyan concentration in the residue in the inflator container after combustion was evaluated in exactly the same manner as in Example 1 except that copper oxide was not added. The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitative analysis of the total amount of cyanide ions by the same method as in Example 1, a value of 21.0 ppm was shown.

Comparative Example 2 The cyan concentration in the residue in the inflator container after combustion was evaluated in the same manner as in Example 1 except that the addition amounts were changed to 26 parts of dicyandiamide and 74 parts of potassium nitrate. The weight ratio of potassium nitrate to dicyandiamide in the composition was a stoichiometric amount of oxygen required to completely convert nitrogen, water, and carbon dioxide after burning dicyandiamide, that is, 1. . The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitatively analyzing the total amount of cyanide ions in the same manner as in Example 1, 5.80 ppm
The value of was shown.

Example 4 The cyan concentration in the residue in the inflator container after combustion was evaluated in the same manner as in Example 1 except that 76 parts of potassium perchlorate was used instead of 76 parts of potassium nitrate. The weight ratio of potassium perchlorate to dicyandiamide in the composition is the weight ratio of potassium perchlorate containing oxygen necessary for completely converting nitrogen, water, and carbon dioxide after burning dicyandiamide to dicyandiamide. When it was set to 1, it was 1.29. The combustion pressure and the combustion time are the same as in Example 1.
The values are similar to those of. As a result of quantitative analysis of the total amount of cyanide ions in the same manner as in Example 1, a value of 0.47 ppm was shown.

Comparative Example 3 Except that the amount of dicyandiamide added was increased to 29 parts and 76 parts of potassium nitrate was used instead of 71 parts of potassium perchlorate.
The cyan concentration in the residue in the inflator container after combustion was evaluated in exactly the same manner as in Example 1. The weight ratio of potassium perchlorate to dicyandiamide in the present composition is the amount ratio containing stoichiometric amount of oxygen necessary for completely converting nitrogen, water and carbon dioxide after burning dicyandiamide,
That is, it was 1. The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitatively analyzing the total amount of cyanide ions by the same method as in Example 1, a value of 13.00 ppm was shown.

Example 5 The cyan concentration in the residue in the inflator container after combustion was evaluated in the same manner as in Example 1 except that 10 parts of molybdenum trioxide was added instead of 10 parts of copper oxide. The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitative analysis of the total amount of cyanide ions by the same method as in Example 1, a value of 0.36 ppm was shown.

Comparative Example 4 The cyan concentration in the residue in the inflator container after combustion was evaluated in exactly the same manner as in Example 5 except that the addition amounts were changed to 26 parts of dicyandiamide and 74 parts of potassium nitrate. The weight ratio of potassium nitrate to dicyandiamide in the composition was a stoichiometric amount of oxygen required to completely convert nitrogen, water, and carbon dioxide after burning dicyandiamide, that is, 1. . The combustion pressure and the combustion time showed values similar to those of Example 1. As a result of quantitatively analyzing the total amount of cyanide ions by the same method as in Example 1, 7.50 ppm
The value of was shown.

[0023]

INDUSTRIAL APPLICABILITY According to the present invention, dicyandiamide, an oxygen-containing inorganic oxidizing agent, and a periodic table group I, group II, group III.
A gas generant composition containing, as an essential component, an inorganic compound containing at least one element selected from the group IV, IV, V, VI, VII and VIII elements It is possible to significantly reduce the amount of cyanide, which is a harmful component in the generated residue, while maintaining satisfactory system performance.

Claims (6)

[Claims] 1. A dicyandiamide, an oxygen-containing inorganic oxidizing agent,
And Periodic Table Group I, Group II, Group III, Group IV, Group V
In a gas generant composition containing, as an essential component, an inorganic compound containing at least one element of Group III, Group VI, Group VII, and Group VIII, after completely burning dicyandiamide, nitrogen, water, carbon dioxide When the weight ratio of the oxygen-containing inorganic oxidant containing a stoichiometric amount of oxygen required to change to dicyandiamide is 1.00, the weight ratio of the oxygen-containing inorganic oxidant to dicyandiamide in the composition is 1.01.
To 1.50, the gas generant composition. 2. The oxygen-containing inorganic oxide is potassium nitrate, sodium nitrate, strontium nitrate, potassium nitrite,
The gas generant composition according to claim 1, which is at least one selected from the group consisting of sodium nitrite, sodium perchlorate, potassium perchlorate, strontium perchlorate, sodium chlorate, and potassium chlorate. 3. Periodic table Group I, Group II, Group III, Group
An inorganic compound containing at least one element of Group IV, Group V, Group VI, Group VII, and Group VIII is copper, calcium, barium, zinc, boron, cerium, ytterbium, titanium, lead, The gas generant composition according to claim 1, which is an inorganic compound containing at least one element selected from the group consisting of vanadium, antimony, molybdenum, manganese, iron, cobalt, and nickel. 4. The periodic table group I, group II, group III, group
Inorganic compounds containing at least one element of Group IV, Group V, Group VI, Group VII, and Group VIII are CuO, Cu
₂ O, CaO ₂ , Ba ₂ O ₃ , ZnO, ZnCO ₃ , B ₂ O ₃ , CeO ₂ , Yb ₂ O ₃ , T
iO ₂ , Pb ₃ O ₄ , PbO ₂ , PbO, V ₂ O ₅ , Sb ₂ O ₃ , MoO ₃ , MnO ₂ , Fe
The gas generant composition according to claim 1, which is at least one compound selected from the group consisting of Cl ₃ , Co ₃ O _4, and NiO. 5. The oxygen-containing inorganic oxidizing agent comprises potassium nitrate, sodium nitrate, strontium nitrate, potassium nitrite, sodium nitrite, sodium perchlorate, potassium perchlorate, strontium perchlorate, sodium chlorate and potassium chlorate. At least one selected from the group, and the inorganic compound is copper, calcium, barium, zinc, boron, cerium, ytterbium, titanium, lead, vanadium, antimony, molybdenum, manganese, iron, cobalt and nickel. An inorganic compound containing at least one element selected from the group consisting of:
The gas generant composition according to. 6. The oxygen-containing inorganic oxidant is at least one selected from the group consisting of potassium nitrate, sodium nitrate, strontium nitrate, sodium perchlorate, potassium perchlorate and strontium perchlorate, and
The gas generant composition according to claim 1, wherein the inorganic compound is an inorganic compound containing at least one element selected from the group consisting of copper, lead and molybdenum.