JPH0761885A - Gas generating agent composition - Google Patents

Abstract

PURPOSE:To obtain a gas generating agent composition which increases a formed amount of a gas, can reduce an amount of a gas generating agent in a gas generator and miniaturize the gas generator, is a composition not containing sodium azide and dose not substantially form carbon monoxide. CONSTITUTION:This gas generating agent composition comprises cellulose acetate and a perchlorate such as potassium perchlorate as main components and contains a nitrogen-containing nonmetallic compound which is composed of at least nitrogen and hydrogen and contains >=11wt.% of hydrogen. Nitroguanidine or guanidine nitrate is used as the nitrogen-containing nonmetallic compound. The amount of nitrogen in the nitrogen-containing nonmetallic compound is preferably 10-83wt.% and the amount of the nitrogen-containing nonmetallic compound mixed is preferably 10-45wt.%. The amount of cellulose acetate is preferably 8-26wt.% and that of potassium perchlorate is preferably 45-87.

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 for use in a gas generator of an airbag device mounted on an automobile as a safety device in the event of a collision.

[0002]

2. Description of the Related Art An air bag is mounted on, for example, a steering wheel inside a vehicle and inflates in a collision to protect an occupant. As a gas generating agent used to inflate this airbag, one containing sodium azide and various oxidizing agents as main components is known, and by burning this, nitrogen gas is generated to generate an airbag. Inflate.

A gas generating agent containing sodium azide as a main component produces a clean nitrogen gas as a gas component by combustion and is therefore preferable as a gas generating agent.
However, sodium azide is highly toxic and easily forms a sensitive explosive substance when it comes into contact with an acid or a heavy metal. Therefore, it is necessary to pay particular attention during production and disposal. Further, since the gas generating agent containing sodium azide as a main component produces a large amount of corrosive sodium and sodium compounds after combustion, it is necessary to carry out these treatments at the time of disposal.

In order to solve this problem, gas generant compositions which do not use sodium azide have been studied in various fields. For example, Japanese Patent Publication No. 58-20919 discloses a composition comprising the following (a), (b) and (c). That is, the composition is (a) 78 to 92% by weight of an oxidizing agent which is a chlorate or perchlorate of an alkali metal or an alkaline earth metal, (b) cellulose acetate 7.9 to 17.2% by weight, (C) It is composed of a mixed explosive having 0.1 to 0.8% by weight of a combustion control agent containing carbon.

As carbon-containing combustion control agents, for example acetylene black or graphite are used. Then, this composition does not substantially produce carbon monoxide, and produces a product gas consisting of water, carbon dioxide and oxygen in a standard state at about 0.36 liter / g.

[0006]

However, the above-mentioned gas generant composition has a very high combustion temperature, and when it is used by being incorporated in a gas generator, the generated gas composition is used to prevent burnout of an airbag. There was a problem in that it was necessary to cool it sufficiently. Therefore, a large amount of coolant is required inside the gas generator, which is a problem in reducing the size of the gas generator.

[0007] In general, in order to reduce the size and weight of a gas generator, the required amount of the gas generating agent per gas generator is reduced by increasing the amount of gas generated per unit weight of the gas generating agent. Will be achieved at a higher level. However, there has been a problem that such a reduction in size and weight has not been sufficiently achieved.

Further, it is inappropriate to contain toxic carbon monoxide in the gas generated when the gas generant composition used for airbag deployment burns. The present invention has been made by paying attention to such problems of the conventional technology. The purpose is to increase the amount of generated gas and lower the combustion temperature to reduce the amount of gas generating agent in the gas generator, and to reduce the size of the gas generator. Another object of the present invention is to provide a gas generant composition that can be used. Another object is to provide a composition that does not contain sodium azide and that does not substantially produce carbon monoxide.

[0009]

In order to achieve such an object, in the gas generant composition of the invention described in claim 1, cellulose acetate and perchlorate are main components and at least nitrogen is used. , Hydrogen and oxygen, and a nitrogen-containing nonmetallic compound containing 11% by weight or more of nitrogen. Further, in the invention described in claim 2, in the invention described in claim 1, the nitrogen-containing nonmetallic compound is selected from the group consisting of a guanidine compound, an oxime, an amide, a tetrazole derivative, an aromatic nitro compound and ammonium nitrate. And at least one compound.

Next, the respective constituent elements of the present invention will be sequentially described in detail. Cellulose acetate is a combustible substance composed of carbon, hydrogen and oxygen, and when mixed with an oxidant and burned, it produces a large amount of carbon dioxide, water and oxygen. Cellulose acetate is soluble in a specific solvent and, when dissolved, exhibits a paste-like form. Therefore, when mixed with a powder such as an oxidizer, it enters the gap between the powders and acts as a binder. It has the action of.

At this time, in order to fully exert the action as a binder, the blending amount of cellulose acetate is preferably 8% by weight or more. 8% by weight of cellulose acetate
If it is less than the above, cellulose acetate is unsuitable because it becomes difficult to completely cover the powder component such as the oxidizing agent. On the other hand, the upper limit of the blending amount of cellulose acetate is determined by the condition that carbon monoxide is not substantially generated when the gas generating composition is burned.

Here, the condition that carbon monoxide is not substantially produced is that the concentration of carbon monoxide in the produced gas is 50.
It means that it is not more than 00 ppm. The upper limit of the blending amount of cellulose acetate for satisfying this condition varies depending on the blending ratio of the perchlorate and the nitrogen-containing nonmetallic compound.
6% by weight is preferred. Therefore, the preferable blending amount of cellulose acetate is in the range of 8 to 26% by weight.

[0013] Perchlorate is an oxidant. Among the oxidants, the amount of oxygen released per unit weight is large and the thermal stability is excellent. As this perchlorate, potassium perchlorate,
Examples thereof include ammonium perchlorate and sodium perchlorate. Among them, potassium perchlorate has no hygroscopicity, and most of the residue after combustion is potassium chloride, which is not corrosive. Therefore, potassium perchlorate is the most preferable as the oxidizing agent to be added to the gas generating composition.

The particle size of the perchlorate salt is not particularly limited as long as it is within the range of 5 to 300 μm, but two or more kinds of powders having different particle sizes should have a close packing structure. It is preferable to mix them. The amount of perchlorate to be added is 45 to 8 in order to produce 8% by weight or more of cellulose acetate without substantially producing carbon monoxide.
A range of 7% by weight is suitable.

Next, the nitrogen-containing nonmetallic compound used in the present invention comprises at least nitrogen and hydrogen, and nitrogen
A compound containing not less than wt% and further containing oxygen or carbon is also used. As the nitrogen-containing non-metal compound, at least one compound selected from the group consisting of guanidine compounds, oximes, amides, tetrazole derivatives, aromatic nitro compounds and ammonium nitrate is preferable.

As guanidine compounds, nitroguanidine (CH ₄ N ₄ O ₂ , nitrogen content 53.8%), triaminoguanidine nitrate (CH ₉ N ₇ O ₃ , nitrogen content 58.6%), guanidine nitrate. (CH ₆ N ₄
O ₃ , nitrogen content 45.9%) and the like are used. Hydroxyglyoxime (C ₂ H ₄ O ₄ N as oximes
₂ , nitrogen content 23.3%) and the like are used. Oxamide (C ₂ H ₄ N ₂ O ₂ , nitrogen content 3 as amides
1.8%). Aminotetrazole as a tetrazole derivative (N ₅ H ₃ C, nitrogen content 82.4
%). Nitrotoluene (NH ₇ O ₂ C ₇ , nitrogen content 11.6%) and the like are used as the aromatic nitro compound. In addition, ammonium nitrate (NH ₄ NO
₃ , nitrogen content 23.3%) is used. These compounds are solid or liquid at room temperature.

When the nitrogen content of the nitrogen-containing non-metal compound is low, carbon monoxide is not substantially generated.
Since a large amount of oxidizing agent is required, the amount of the nitrogen-containing nonmetallic compound cannot be increased. Therefore, the nitrogen content of the nitrogen-containing non-metal compound needs to be 11% by weight or more. Further, the higher the content, the more preferable. However, since it is a compound that actually exists and it is necessary to be easy to handle, the upper limit is preferably 83% by weight. Then, the nitrogen-containing non-metallic compound produces a large amount of nitrogen, carbon dioxide, water and oxygen when it is mixed with perchlorate and burned. Moreover, since it does not contain metallic elements, it has the advantage that no residue is generated after combustion.

As the amount of the nitrogen-containing non-metallic compound added is increased, the amount of produced gas can be increased, and the ratio of nitrogen gas in the produced gas is increased, whereby a cleaner gas can be produced. However, the blending amount is such that carbon monoxide is not substantially produced, and the blending amount of cellulose acetate is 8% by weight or more, and as described above, the cellulose acetate completely covers the powder component. The amount must be such that it can be done. Therefore, the blending amount is preferably in the range of 10 to 45% by weight.

The gas generant composition of the present invention comprises cellulose acetate and perchlorate mixed with a predetermined amount of a nitrogen-containing non-metallic compound, and is molded into a desired shape such as pellet, rod or disk. To be done.

This gas generating composition may contain a part of cellulose acetate as triacetin (C ₃ H) if necessary.
₅ (OCOCH ₃ ) ₃ ), diethyl phthalate, dimethyl phthalate, and the like, and cellulose acetate can be substituted with a plasticizer having a good affinity with cellulose acetate. Of these plasticizers, triacetin is preferable because it has the highest oxygen content and does not require a large amount of oxidizing agent. If necessary, a combustion modifier such as metal powder or carbon black can be added.

Since the gas generant composition thus constructed does not contain sodium azide, it is easy to handle and there is no risk of producing corrosive sodium or sodium compounds. Further, since substantially no carbon monoxide is produced in the produced gas, the safety is high, and since the produced gas amount is large, the amount of the gas generating agent is small and the gas generator can be downsized. .

[0022]

The gas generating composition of the present invention is a composition containing cellulose acetate and a perchlorate as main components, and a specific nitrogen-containing non-metal compound. The nitrogen-containing non-metallic compound contains 11% by weight or more of nitrogen. Therefore, the nitrogen-containing nonmetallic compound reacts with the perchlorate to produce a large amount of nontoxic gas such as nitrogen gas.

[0023]

EXAMPLE 1 Example 1 embodying the present invention will be described below with reference to FIG.

First, a gas generant composition was prepared as follows. As a raw material mixture, as shown in Table 1, 8% by weight of cellulose acetate having a degree of acetylation of 53% (manufactured by Teijin Ltd.), 2% by weight of triacetin (manufactured by Daihachi Chemical Industry Co., Ltd.) as a plasticizer, 55% by weight of potassium perchlorate (manufactured by Japan Carlit Co., Ltd.) having an average particle size of 17 μm, and nitroguanidine (manufactured by China Explosives Co., Ltd.) as a nitrogen-containing nonmetallic compound.
A composition consisting of 35% by weight was prepared. A proper amount of a mixed solvent of acetone and methyl alcohol was added to this and mixed uniformly to prepare a drug mass.

Next, this drug mass was loaded into a companding machine. A die with a diameter of 4 mm is attached to the compander in advance.
The drug mass is extruded by being passed through this die by pressure and is shaped into a rod. The molded product was cut into a length of 2 mm and dried to obtain a pelletized gas generant composition.

This gas generating composition was prepared by Shimadzu Corporation
Gas chromatograph with a pyrolysis device (model: GC-1
4A) was used to determine the composition of the produced gas during combustion at 800 ° C. and the amount of produced gas in the standard state.

Next, the gas generator will be described. Figure 1
As shown in FIG. 1, a gas generator 1 formed in a cylindrical shape has an ignition chamber 2 arranged in the center thereof, a combustion chamber 3 formed concentrically in the gas generator 1, and a concentric circle formed in the outer periphery thereof. The cooling and collecting chamber 4 formed in the above. The electric igniter 5 and the ignition charge 6 are arranged in the ignition chamber 2 and are ignited when energized. The pelletized gas generant 7 is used in the combustion chamber 3
It is loaded inside and burns with a flame caused by ignition of the ignition charge 6 to generate a gas such as carbon dioxide. In this example, the above-mentioned gas generating agent 7 was loaded into the combustion chamber 3 so that the amount of generated gas in the standard state was about 30 liters. The cooling and collecting materials 8 and 9 are arranged in the combustion chamber 3 and the cooling and collecting chamber 4, and cool the produced gas and collect the solid combustion residue by filtration.

A plurality of vent holes 10 and 11 are provided in the partition wall 12 between the ignition chamber 2 and the combustion chamber 3 and the partition wall 13 between the combustion chamber 3 and the cooling and collecting chamber 4, respectively, and the flame generated by ignition of the ignition charge 6 is provided. And the distribution of generated gas. The gas outflow hole 14 is provided through the peripheral wall 15 of the cooling / collecting chamber 4 so that the gas cooled in the cooling / collecting chamber 4 is ejected into the airbag 16.

When the ignition charge 6 is ignited by the igniter 5 based on a signal at the time of a vehicle collision, the flame is propagated to the combustion chamber 3 through the ventilation hole 10, and the combustion chamber 3
The gas generating agent 7 therein burns to generate gas. This gas is introduced into the cooling collection chamber 4 via the cooling collection material 8 and the ventilation hole 11. This gas is further ejected from the gas outflow hole 14 via the cooling and collecting material 9.

Next, the temperature inside the tank when this gas generator 1 was attached to a tank of 60 liters and operated was measured by an almelochromel thermocouple having a wire diameter of 50 μm. The results are shown in Table 2. In Table 2, the amount of produced gas indicates the total volume of carbon dioxide, water, oxygen and nitrogen produced when 1 g of the gas generant composition is burned in the standard state. (Examples 2 to 9) With the composition shown in Table 1, a gas generant composition was produced in the same manner as in Example 1, and the characteristics were evaluated in the same manner. The results are shown in Table 2. (Comparative Examples 1 and 2) With the composition shown in Table 1, a gas generant composition was produced by the same method as in Example 1 and evaluated by the same method. The results are also shown in Table 2.

The gas temperature in the tank changes depending on the combustion temperature of the gas generant composition. The higher the combustion temperature, the higher the gas temperature in the tank.

[0032]

[Table 1]

[0033]

[Table 2]

From the results shown in Table 1, in each Example, cellulose acetate was 8 to 26% by weight and potassium perchlorate was 4%.
5 to 87 wt% and a nitrogen-containing non-metallic compound are blended at 10 to 42 wt%. Therefore, it is possible to substantially prevent generation of harmful carbon monoxide concentration in the produced gas when the gas generating agent is burned.

In addition, as compared with Comparative Example 1 containing no nitrogen-containing non-metallic compound, the amount of produced gas was increased and the temperature of gas in the tank was lowered in all Examples.
Further, as shown in Comparative Example 2, when the nitrogen content of the nitrogen-containing non-metallic compound was 9.4%, almost no increase in the produced gas amount and no decrease in the tank gas temperature were observed. In addition, even when triacetin is not included as a plasticizer (Example 9), all the properties are well balanced and well maintained.

The present invention is not limited to the above-described embodiments, but may be embodied by arbitrarily changing the configuration as follows, for example, within the scope not departing from the spirit of the invention. (1) In the examples, use of cellulose acetate having different acetylation degrees. (2) The gas generant composition 7 of the present invention is loaded into a gas generator used in an airbag device for a passenger seat as well as an airbag device for a driver seat mounted on a vehicle. (3) The gas generant composition 7 is loaded into a gas generator of an airbag device such as a life-saving bag other than that for a vehicle, a rubber boat, an escape chute, and is developed by combustion gas.

[0037]

As described above in detail, the gas generating composition of the present invention has the following excellent effects.

In other words, it is possible to increase the amount of generated gas and lower the combustion temperature, so that it is possible to reduce the amount of the gas generating agent in the gas generator and to reduce the size of the gas generator. Can be planned. Further, since the composition does not contain sodium azide, there is substantially no risk of producing carbon monoxide.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a gas generator loaded with a gas generant composition according to an embodiment of the present invention.

[Explanation of symbols]

 7 ... Pelletized gas generant composition.

Claims (2)

[Claims] 1. A cellulose acetate and a perchlorate as main components, which is composed of at least nitrogen and hydrogen, and nitrogen of 11
A gas generant composition comprising a nitrogen-containing non-metallic compound in an amount of at least wt%. 2. The nitrogen-containing nonmetallic compound is a guanidine compound, an oxime, an amide, a tetrazole derivative,
The gas generant composition according to claim 1, which is at least one compound selected from the group consisting of an aromatic nitro compound and ammonium nitrate.