JPH0753293A - Gas generating agent composition - Google Patents

Abstract

PURPOSE:To provide a gas generating agent composition, with which the amount of the coolant in a gas generator and the size of the gas generator can be reduced by controlling the burning temp. at a lower level and which contains no sodium azide and generates substantially no carbon monoxide. CONSTITUTION:This composition consists essentially of a perchlorate such as potassium perchlorate, etc., and cellulose acetate and also contains 5 to 40wt.% metal oxide such as manganese dioxide, copper oxide or iron oxide, etc. The blending ratios of the potassium perchlorate and the cellulose acetate are preferably 50 to 87wt.% and 8 to 26wt.% respectively.

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 A gas generating agent is usually formed in a pellet shape or a rod shape, and is incorporated in a gas generator case made of metal such as stainless steel or aluminum. This airbag is attached to, for example, a steering wheel inside a vehicle, and is used for protecting an occupant from a collision. This gas generant composition is particularly suitable for automobiles, but can be used for those that require a large amount of gas, such as a boat that is inflated with air.

Further, it is known in the art to utilize airbags for high speed vehicles such as boats and airplanes to protect passengers in the event of a collision or crash. At this time, the shape of the gas generating agent is a rod shape, a rod shape with various holes, or a pellet shape, depending on the required performance.

As the gas generating composition, a gas generating agent containing sodium azide and various oxidizing agents as main components is known. Sodium azide is a highly toxic substance and is easily hydrolyzed to produce hydrogen azide. This hydrogen azide is also highly toxic and easily explosive. Furthermore, both sodium azide and hydrogen azide readily react with heavy metals such as copper and lead to form extremely unstable explosive solids.

In order to safely handle the gas generant composition comprising such an azide compound, it is necessary to specially handle the production, storage and final disposal. Furthermore, the gas generant composition comprising sodium azide and an oxidant produces harmful sodium and sodium compounds upon combustion.

From such a point of view, there is known a means for achieving the above object by using a gas generant composition containing no sodium azide. For example, Japanese Patent Publication 58-20919
The publication discloses a gas generating composition comprising three components of an oxidizing agent, cellulose acetate, and a combustion control agent containing carbon. Alkali metal perchlorates or alkaline earth metal perchlorates are shown as oxidizing agents, and acetylene black and graphite are shown as combustion modifiers.

[0007]

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. On the other hand, the gas generant composition should not contain harmful gases such as carbon monoxide.

The present invention has been made by paying attention to such a problem of the prior art. The purpose is to
It is an object of the present invention to provide a gas generant composition that can reduce the amount of the coolant in the gas generator by suppressing the combustion temperature to a lower level and can reduce the size of the gas generator. 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, the gas generant composition of the present invention comprises perchlorate and cellulose acetate as main components and contains 5% by weight of a metal oxide. It is characterized by containing more than 40% by weight.

Next, the respective constituents of the present invention will be described in detail in order. Perchlorate is an oxidizing agent, and has a large amount of oxygen released per unit weight among the oxidizing agents, and is excellent in thermal stability. Examples of this perchlorate include potassium perchlorate, ammonium perchlorate, sodium perchlorate, etc. Among them, potassium perchlorate has no hygroscopicity, and most of the residue after combustion is corrosive. There is no potassium chloride. Therefore, potassium perchlorate is the most preferable as the oxidizing agent to be added to the gas generating composition.

The particle size of potassium perchlorate is 5 to 300.
Although not particularly limited as long as it is within the range of μm, it is preferable to mix two or more kinds of powders having different particle diameters so as to have a close-packed structure. As the amount of perchlorate compounded, substantially without producing carbon monoxide,
Moreover, the range of 50 to 87% by weight is suitable for blending 8% by weight or more of cellulose acetate.

Next, 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 metal oxide, and is preferably 26% by weight. Therefore, the preferable blending amount of cellulose acetate is in the range of 8 to 26% by weight.

Next, the metal oxide used in the present invention is copper oxide, manganese dioxide, iron oxide, nickel oxide or the like.
Metal oxides have excellent thermal stability, and when burned,
It releases oxygen and acts as an oxidant. The residue after burning is preferable because a simple metal is produced and a corrosive residue is not produced.

Further, the metal oxide is reduced to a simple metal during combustion. The reaction in which the metal oxide releases oxygen is an endothermic reaction, and the endothermic reaction has a function of suppressing the combustion temperature. Furthermore, since the reaction of melting the generated metal is also an endothermic reaction, it has a function of suppressing the combustion temperature.

The particle size of the metal oxide is not particularly limited, but in order to obtain good combustion characteristics, it is 30
A particle size of less than or equal to μm is preferred. The gas generant composition of the present invention is formed by mixing a perchlorate and cellulose acetate with a predetermined amount of a metal oxide, and molded into a desired shape such as a pellet shape, a rod shape, or a disk shape.

In this gas generating composition, if necessary, a part of the cellulose acetate can be replaced with a plasticizer having a good affinity with cellulose acetate such as triacetin, diethyl phthalate and dimethyl phthalate. Of these plasticizers, dimethyl phthalate is preferable because of its thermal stability and compatibility with cellulose acetate. If necessary, a combustion modifier such as 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 the amount of generated gas is large, the airbag can be surely deployed. In addition, since the combustion temperature of the gas generating agent can be kept low, it is possible to reduce the amount of the coolant in the gas generating apparatus, and it is possible to reduce the size of the gas generating apparatus.

[0020]

The gas generant composition of the present invention is a composition containing perchlorate and cellulose acetate as main components and a metal oxide compounded therein, and produces a large amount of non-toxic gas upon combustion.
Moreover, since the metal oxide is blended, the combustion temperature is lowered. That is, since the reaction of releasing oxygen of the metal oxide is an endothermic reaction, the combustion temperature can be suppressed, and the melting reaction of the reduced metal alone is an endothermic reaction, which suppresses the increase of the combustion temperature. can do.

[0021]

【Example】

(Embodiment 1) Hereinafter, an embodiment embodying the present invention will be described with reference to FIG.

First, a gas generant composition was prepared as follows. 11% by weight of cellulose acetate (manufactured by Teijin Ltd.) having a degree of acetylation of about 53% as a raw material mixture, and dimethyl phthalate (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as a plasticizer.
4% by weight, 55% by weight of potassium perchlorate (manufactured by Japan Carlit Co., Ltd.) having an average particle size of 17 μm, and an average particle size of 8 μm
25% by weight of copper oxide (manufactured by Mitsui Kinzoku Co., Ltd.) 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 compander. 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.

Next, as shown in FIG. 1, a gas generator 1 formed in a cylindrical shape has an ignition chamber 2 arranged in the center thereof and a combustion chamber 3 formed concentrically in the gas generator 1. When,
Further, a cooling and collecting chamber 4 formed concentrically around the outer periphery thereof is provided. The electric igniter 5 and the ignition charge 6 are in the ignition chamber 2
It is placed inside and ignites when energized. The pelletized gas generating agent 7 is loaded into the combustion chamber 3 and burns with a flame generated by ignition of the ignition charge 6 to generate a gas such as carbon dioxide gas.
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 collection chamber 4, respectively, and the flame generated by the 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 on the basis of a signal at the time of a vehicle collision or the like, 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 1.

Separately from this, a cylindrical molded product (hereinafter referred to as a strand) having a diameter of 4 mm and a length of 80 mm was prepared as the gas generating agent 7 and used for measuring the burning rate. For the burning rate, after coating the side surface of the strand with epoxy resin to prevent the entire surface burning, use a drill with a diameter of 0.5 mm to open two small holes at appropriate intervals in the lateral direction. A blowout fuse for measuring the burning time was passed through each hole. This strand sample was set on a predetermined fixed table, and a nichrome wire was ignited from one end of the strand under a pressure of 30 atm, and the moment when the fuse was blown when the combustion surface passed was measured electrically, and 2 points were measured. The burning velocity was obtained as a linear burning velocity by dividing the distance between them by the time difference. The results are shown in Table 1 below. (Examples 2 to 5) 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 by the same method. The results are shown in Table 1. (Comparative Example 1) A gas generant composition having the composition shown in Table 1 was produced by the same method as in Example 1, and evaluated by the same method. The results are also shown in Table 1.

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.

[0030]

[Table 1]

From the results in Table 1, comparing Example 1 with Comparative Example 1, it can be seen that the gas temperature in the tank is lowered by adding copper oxide while maintaining the combustion temperature. In addition, comparing Example 2 with Comparative Example 1, it can be seen that the gas temperature in the tank is lowered by adding iron oxide.

Further, comparing Example 3 with Comparative Example 2, when the compounding amount of copper oxide exceeds 40% by weight, the gas temperature in the tank is lowered, but the combustion speed is rapidly lowered and It turns out to be suitable. From this, the amount of the metal oxide blended varies depending on the type of the metal oxide, but is 40
It needs to be less than or equal to wt%.

Further, comparing Example 4 with Comparative Example 3,
It can be seen that when the content of the metal oxide is 5% by weight or less, the temperature inside the tank is not sufficiently cooled. From this, the amount of the metal oxide blended varies depending on the type of the metal oxide, but it is necessary to exceed 5% by weight.

In addition, the gas in the tank can be reduced even when dimethyl phthalate is not contained as in Example 5. Moreover, the gas generant compositions of each example do not substantially generate harmful carbon monoxide.

The present invention is not limited to the above 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 generating agent 7 of the present invention is loaded into a gas generator used in an airbag apparatus for a passenger seat as well as an airbag apparatus for a driver seat mounted on a vehicle. (3) The gas generating agent 7 is loaded into a gas generator of an airbag device other than a vehicle such as a life-saving bag, a rubber boat, or an escape chute, and developed by combustion gas.

[0036]

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

That is, the combustion temperature of the gas generating agent can be suppressed to a lower level, the amount of the coolant in the gas generating apparatus can be reduced, and therefore the gas generating apparatus can be downsized. 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 generating agent.

Claims (1)

[Claims] 1. A gas generant composition comprising a perchlorate and cellulose acetate as main components and containing more than 5% by weight and 40% by weight or less of a metal oxide.