Gas generating agent composition and gas generator

Abstract

The present invention provides a gas generating agent composition that has a low calorific value and produces little CO gas. [Solution] A gas generating agent composition containing fuel components, an oxidizer, and activated carbon, The aforementioned fuel component is a nitrogen-containing organic compound. The oxidizing agent component is one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates. A gas generating agent composition in which the raw material for the activated carbon is coconut shell.

Description

[Technical Field]

[0001] The present invention relates to a gas generating agent composition and a gas generator, which are suitably used in airbag systems and seat belt pretensioner systems. [Background technology]

[0002] Airbag systems and seat belt pretensioners are used as safety devices to protect occupants in collision accidents involving vehicles, such as automobiles. In the case of an airbag system, when a vehicle is involved in a collision, an electrical signal is sent from a collision detection sensor to an airbag deployment gas generator. This gas generator burns a gas generating agent composition and generates gas, which then causes the airbag to deploy due to the resulting gas pressure.

[0003] The seat belt pretensioner device works by using an electrical signal to activate a gas generating agent composition loaded into a seat belt pretensioner gas generator when a vehicle collision is detected by a sensor. This gas is then used to activate the seat belt retraction mechanism.

[0004] Various gas generating agent compositions have been developed as important components of the performance of gas generators used in such airbag systems and seat belt pretensioner systems.

[0005] Traditionally, gas generating agent compositions used in seat belt pretensioner devices have primarily employed smokeless powder, mainly composed of nitrocellulose. However, because smokeless powder generates a large amount of CO gas and has low heat resistance, there has been a growing demand for gas generating agent compositions other than smokeless powder in recent years.

[0006] Gas generating agent compositions using nitrogen-containing organic compounds as fuel and perchlorates or basic metal nitrates as oxidizers can suppress CO gas generation compared to smokeless powders, but generally have a slower combustion rate and higher calorific value. Therefore, they have been difficult to use in applications requiring a fast combustion rate and low calorific value, such as seat belt pretensioner devices.

[0007] Patent Document 1 discloses a gas generating agent composition comprising ammonium nitrate as an oxidizing agent and activated carbon as a fuel. However, gas generating agents containing ammonium nitrate deteriorate when installed in vehicles for extended periods, and the deteriorated gas generating agent composition causes abnormal combustion. Therefore, its use in vehicle safety devices is currently prohibited.

[0008] Patent Document 2 discloses a gas generating agent composition comprising a fuel selected from triazine compounds and guanidine compounds, an oxidizing agent combining a basic metal nitrate and a basic metal carbonate, a binder, and an adsorbent. However, Patent Document 2 only discloses activated carbon as an adsorbent for the generated gas, and does not describe any specific examples of its use. Furthermore, it does not describe the effect of the gas generating agent composition on the calorific value. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2000-86378 [Patent Document 2] Japanese Patent Publication No. 2014-80339 [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention aims to provide a gas generating agent composition that has a low calorific value and produces little CO gas. [Means for solving the problem]

[0011] The present invention relates to the following items [1] to [5]. [1] A gas generating composition comprising a fuel component, an oxidizing agent and activated carbon, wherein the fuel component is a nitrogen-containing organic compound, the oxidizing agent component is at least one selected from the group consisting of nitrates, basic metal nitrates, perchlorates and chlorates, and the raw material of the activated carbon is coconut shell. [2] A gas generating composition comprising a fuel component, an oxidizing agent and activated carbon, wherein the fuel component is a nitrogen-containing organic compound, the oxidizing agent component is at least one selected from the group consisting of nitrates, basic metal nitrates, perchlorates and chlorates, and the specific surface area of the activated carbon is 1000 m 2 / g or more and 2500 m 2 / g or less. [3] The gas generating composition according to the above [1] or [2], wherein the activated carbon has an average particle diameter D50 of 1.0 µm or more and 100 µm or less. [4] The gas generating composition according to any one of the above [1] to [3], wherein the added amount of the activated carbon is 1.0% by weight or more and 5.0% by weight or less based on the total amount of the gas generating composition. [5] A gas generator comprising the gas generating composition according to any one of the above [1] to [4]. Effects of the Invention

[0012] According to the present invention, a gas generating composition having a low calorific value and generating a small amount of CO gas can be provided. Brief Description of Drawings

[0013] [Figure 1] shows the results of combustion performance tests of Example 1 and Comparative Example 1. Mode for Carrying Out the Invention

[0014] Embodiments of the present invention will be described in detail below. The description of the constituent requirements described below is an example (representative example) of embodiments of the present invention, and the present invention is not limited to the following content unless the gist thereof is changed. In addition, when the expression "~" is used in the present invention, it is used as an expression including the numerical values before and after it.

[0015] The gas generating agent composition of the present embodiment contains a fuel component, an oxidizing agent and activated carbon.

[0016] As the fuel component (hereinafter sometimes referred to as "component A"), a nitrogen-containing organic compound is preferably used as the gas generating agent composition of the present embodiment.

[0017] The nitrogen-containing organic compound used as the fuel component is preferably one having physical properties that thermally decomposes upon being triggered by combustion and releases nitrogen as a main component, and examples thereof include guanidine derivatives, tetrazole derivatives, triazole derivatives, bitriazole derivatives, bitetrazole derivatives, azodicarbonamide derivatives, bishydrazine derivatives, and hydrazide derivatives. Specific examples of these include guanidine, nitroguanidine, guanidine nitrate, aminoguanidine nitrate, cyanoguanidine, triaminoguanidine, triaminoguanidine nitrate, tetrazole, 5-aminotetrazole, aminotetrazole nitrate, nitroaminotetrazole, metal salts of aminotetrazole, copper complexes of 5-aminotetrazole, metal salts of bitetrazole, monoammonium salts of bitetrazole, diammonium salts of bitetrazole, bitetrazole (5,5'-bi-1H-tetrazole), 5,5'-bi-1H-tetrazole diammonium salt, azobistetrazole, and 5,5'-azotetrazole Examples include diguanidium hydroxypropyl alcohol salts, 5-oxo-1,2,4-triazole, trihydrazinotriadin, biuret, azodicarbonamide, biurea, azodicarbonamide, hydrazine metal complex nitrates, hydrazine nitrate complexes, carbohydrazides, carbohydrazide transition metal complex nitrates, carbohydrazide nitrate complexes, ammonium oxalate, monohydrazide oxalate, dihydrazide oxalate, sodium dicyanamide, bis(dicyandiamide)copper(I) nitrate, ammine complex dicyanamide, dicyandiamide, or salts of these alkali metals, alkaline earth metals, or transition metals. These nitrogen-containing organic compounds may be used individually, but it is also preferable to use a mixture of two or more selected from the above group for the purpose of adjusting performance.

[0018] Among these, it is preferable that one or more be selected from guanidine nitrate, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate, nitroguanidine, and aminonitroguanidine, with guanidine nitrate being particularly preferred.

[0019] The oxidizing agent component (hereinafter sometimes referred to as "component B") supplies the oxygen necessary for combustion to the flammable organic compound component. Preferably, one or more oxidizing agents are selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates, and it is more preferable that perchlorates or basic metal nitrates are used. Examples of nitrates include ammonium nitrate, phase-stabilized ammonium nitrate, and alkali metal or alkaline earth metal nitrates. Examples of alkali metal or alkaline earth metal nitrates include sodium nitrate, potassium nitrate, strontium nitrate, magnesium nitrate, calcium nitrate, and barium nitrate. Examples of basic metal nitrates include basic copper nitrate, basic cobalt nitrate, basic zinc nitrate, basic magnesium nitrate, and basic iron nitrate. Examples of perchlorates and chlorates include ammonium salts, alkali metal salts, or alkaline earth metal salts. Specific examples of perchlorates and chlorates include ammonium perchlorate, sodium perchlorate, potassium perchlorate, strontium perchlorate, magnesium perchlorate, calcium perchlorate, barium perchlorate, ammonium chlorate, sodium chlorate, potassium chlorate, strontium chlorate, magnesium chlorate, calcium chlorate, and barium chlorate. These oxidizing agents may be used individually, but it is also preferable to use a mixed oxidizing agent, which is a mixture of two or more types selected from the aforementioned group, for the purpose of adjusting performance.

[0020] Among these, it is preferable that one or more selected from potassium perchlorate and basic copper nitrate be used.

[0021] This embodiment contains activated carbon (which may be referred to as "component C" below) that can be used in this embodiment. The activated carbon makes it possible to adjust combustion performance and calorific value, and to reduce exhaust gas.

[0022] Starting materials for activated carbon include coconut shells, coal, and wood powder, with coconut shells being preferred among these.

[0023] Furthermore, there are two main methods for activating activated carbon: gas activation using water vapor, carbon dioxide, and air, and chemical activation using zinc chloride and calcium chloride. While there are no particular restrictions on which of these activation methods is used, gas activation, which reduces the pore size, is more preferable.

[0024] The average particle size D50 of activated carbon is preferably in the range of 1.0 to 100 μm, more preferably in the range of 5.0 to 50 μm, and particularly preferably in the range of 10.0 to 30 μm, considering the gas generating agent composition and combustion performance. When the average particle size exceeds 100 μm, the combustion rate tends to be slower. On the other hand, when the average particle size is less than 1.0 μm, the manufacturing stability tends to be poor. The average particle size D50 mentioned above is the value measured by the method described in the examples below.

[0025] Furthermore, the specific surface area of ​​activated carbon is 500-2500 m². 2 It is preferable that the range is in the range of / g, and considering the mechanical properties and combustion performance of the gas generating agent composition, it is 1000 to 2500 m 2 It is even more preferable that the specific surface area is in the range of / g. This specific surface area is 1000-1500 m². 2 A range of / g is particularly preferred. Specific surface area of ​​2500 m² 2 When the amount exceeds / g, manufacturing stability tends to deteriorate. On the other hand, when the specific surface area is 500m² 2 Below 1g, the combustion rate tends to be slower. The specific surface area values ​​mentioned above were measured using the method described in the examples below.

[0026] In this embodiment, the gas generating agent composition preferably has a weight ratio (A:B) of component (A) to component (B) of 30:70 to 60:40.

[0027] In the gas generating agent composition of this embodiment, the amount of component (C) added is preferably 1.0 to 10.0% by weight of the total amount of the gas generating agent composition, more preferably 1.0 to 5.0% by weight, and particularly preferably 2.0 to 4.0% by weight.

[0028] The gas generating agent composition in this embodiment may further contain additives. These additives can be general additives usable in gas generating agent compositions for gas generators. For example, binders to provide moldability and shape retention, slag-forming agents to facilitate the filtration of combustion residues, and lubricants can be used. These can be used individually or in combination of two or more.

[0029] In this embodiment, binders that can be used are generally binders that can be used as additives to gas generating agent compositions for gas generators, and the binder to be used should be considered depending on the method of molding the gas generating agent composition, specifically whether a tablet molding method or an extrusion molding method is adopted. Specific examples of binders for tableting include inorganic binders such as synthetic hydrotalcite, acid clay, talc, bentonite, diatomaceous earth, molybdenum disulfide, silica, alumina, and graphite, as well as organic binders such as crystalline cellulose and polyvinyl alcohol. Examples of binders for extrusion include metal salts of carboxymethylcellulose, methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, polysaccharide derivatives such as guar gum and starch, and organic binders such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylamide. Alternatively, mixtures thereof can be used.

[0030] The slag-forming agent that can be used in this embodiment is a slag-forming agent that can be used as an additive in gas generator compositions for gas generators, and is an additive that makes it possible to easily filter the combustion residue generated after the combustion of the gas generator composition. Specific examples of slag-forming agents include silicon nitride, silicon carbide, silicon dioxide, aluminum oxide, titanium oxide, silicates, acid clay, and clay. The slag-forming agent content in the gas generator composition is 0 to 10% by weight, more preferably 2 to 5% by weight.

[0031] Examples of lubricants that can be used in this embodiment include graphite, magnesium stearate, zinc stearate, calcium stearate, sodium stearate, boron nitride, highly dispersed silica, and talc, with graphite being preferred. When a lubricant is applied to the gas generating agent, the lubricant content is 0.1 to 1.0% by weight, more preferably 0.2 to 0.5% by weight, of the total amount of the gas generating agent composition.

[0032] The method for producing the gas generating agent composition of this embodiment is not particularly limited, but for example, fuel components, oxidizing agents, additives, etc., can be mixed, molded by extrusion molding, tableting, etc., and then a lubricant can be added to coat the surface.

[0033] The coating method is not particularly limited, but examples include mixing the molded mixture and lubricant in a mixer or the like, or dissolving the lubricant in a solvent as needed and then spray coating or dipping. If a solvent is used, the solvent should be evaporated using a dryer or the like.

[0034] The shape of the gas generating agent composition can be molded into various shapes to suit the combustion performance and combustion characteristics of the gas generator. The shape of the molded body is not particularly limited and examples include pellets, discs, spheres, rods, cylinders, cylindrical shapes, konpeito (sugar candy) shapes, tetrapod shapes, etc. Furthermore, the molded body may be non-porous or porous (e.g., single-hole cylindrical or porous cylindrical). In addition, pellet-shaped and disc-shaped molded bodies may have one or more protrusions on one or both sides. The shape of the protrusions is not particularly limited and examples include cylinders, cylindrical shapes, cones, polygonal pyramidal shapes, etc.

[0035] The gas generator of this embodiment uses the gas generating agent composition described above. The gas generator of this embodiment is suitable as a gas generator for various vehicles, including automobiles. Examples of gas generators for vehicles include gas generators for airbags and gas generators for pretensioners.

[0036] In the gas generator of this embodiment, the configuration can be the same as that of conventionally known gas generators, except for the gas generating agent composition of this embodiment. It is not particularly limited to any specific configuration, and any inflator with a structure typically mounted on a vehicle can be used without any particular limitations. A typical gas generator is constructed by equipping an ignition device and, if necessary, a filter material inside an outer shell with internal volume, and filling it with the gas generating agent composition.

[0037] The gas generator in this embodiment may be either a pyrotype, where the gas supply is solely from the gas generating agent composition, or a hybrid type, where the gas supply is both compressed gas such as argon and the gas generating agent composition. [Examples]

[0038] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless its essence is changed.

[0039] The methods for measuring the average particle diameter and specific surface area shown in the examples and comparative examples are as follows. <Average particle size> The average particle size was measured using a Microtrac particle size analyzer (MT3300EXII). In this patent, the average particle size refers to the 50% particle size based on the number of measured particles, and the average particle size was obtained by a wet method using acetone as the solvent. <Specific surface area> The specific surface area was measured using a specific surface area / pore distribution analyzer (BELSORP®-miniII (product name) manufactured by Microtrac-Bell Co., Ltd.). Specifically, the carbonaceous material was heated at 250°C for 3 hours under reduced pressure (vacuum level: 0.1 kPa or less), and then the nitrogen adsorption isotherm of the carbonaceous material at -196°C was measured. Using the obtained nitrogen adsorption isotherm, a straight line was obtained from the resulting curve using the multipoint method in the region where the relative pressure P / P0 = 0.01 to 0.10, and the specific surface area was calculated from this straight line.

[0040] <Example 1> Guanidine nitrate 34.8% by weight, potassium perchlorate 54.5% by weight, basic copper nitrate 2.0% by weight, polyacrylamide 1.1% by weight, hydroxypropyl methylcellulose 4.6% by weight, activated carbon (Osaka Gas Chemical Co., Ltd.: Shirasagi DO-2, coconut shell, specific surface area 1037 m²) 2 3.0% by weight of ( / g, average particle size 22.1 μm) was mixed in a ball mill, and 14% by weight of ion-exchanged water was added in a kneader and kneaded uniformly. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and extruding it with a die with an inner diameter of 1.8 mm and an inner hole pin with an outer diameter of 0.5 mm at the outlet. The molded body of the extruded gas generating agent composition was cut to a length of 2.0 mm and dried to obtain a gas generating agent composition with a hole in the center of a cylinder.

[0041] <Comparative Example 1> 47.8 wt% of guanidine nitrate, 44.5 wt% of potassium perchlorate, 2.0 wt% of basic copper nitrate, 1.1 wt% of polyacrylamide, and 4.6 wt% of hydroxypropyl methyl cellulose were mixed in a ball mill, and 14 wt% of ion-exchanged water was added and uniformly kneaded by a kneader. Next, a predetermined pressure was applied to the mixture with an extruder, and the mixture was extruded into a predetermined shape by being extruded through an outlet provided with a die having an inner diameter of 1.8 mm and an inner hole pin having an outer diameter of 0.5 mm. The extruded molded article of the gas generant composition was cut to a length of 2.0 mm and dried to obtain a gas generant composition having a hollow at the center of a cylindrical shape.

[0042] <Comparative Example 2> 34.8 wt% of guanidine nitrate, 54.5 wt% of potassium perchlorate, 2.0 wt% of basic copper nitrate, 1.1 wt% of polyacrylamide, 4.6 wt% of hydroxypropyl methyl cellulose, activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd.: Shirasagi DO-5, coal, specific surface area 964 m 2 / g, average particle diameter 29.1 μm) 3.0 wt% were mixed in a ball mill, and 14 wt% of ion-exchanged water was added and uniformly kneaded by a kneader. Next, a predetermined pressure was applied to the mixture with an extruder, and the mixture was extruded into a predetermined shape by being extruded through an outlet provided with a die having an inner diameter of 1.8 mm and an inner hole pin having an outer diameter of 0.5 mm. The extruded molded article of the gas generant composition was cut to a length of 2.0 mm and dried to obtain a gas generant composition having a hollow at the center of a cylindrical shape.

[0043] <Comparative Example 3> 34.8 wt% of guanidine nitrate, 54.5 wt% of potassium perchlorate, 2.0 wt% of basic copper nitrate, 1.1 wt% of polyacrylamide, 4.6 wt% of hydroxypropyl methyl cellulose, activated carbon (manufactured by Osaka Gas Chemicals Co., Ltd.: Shirasagi DO-11, wood powder, specific surface area 824 m 23.0% by weight of ( / g, average particle size 25.7 μm) was mixed in a ball mill, and 14% by weight of ion-exchanged water was added in a kneader and kneaded uniformly. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and extruding it through an outlet equipped with a die with an inner diameter of 1.8 mm and an inner hole pin with an outer diameter of 0.5 mm. The molded body of the extruded gas generating agent composition was cut to a length of 2.0 mm and dried to obtain a gas generating agent composition with a hole in the center of a cylinder.

[0044] <Comparative Example 4> Guanidine nitrate 34.8% by weight, potassium perchlorate 54.5% by weight, basic copper nitrate 2.0% by weight, polyacrylamide 1.1% by weight, hydroxypropyl methylcellulose 4.6% by weight, graphite (manufactured by Nippon Graphite Co., Ltd.: ACP-1000, specific surface area 4.5 m²) 2 3.0% by weight of (14.0 μm / g, average particle size) was mixed in a ball mill, and 14% by weight of deionized water was added in a kneader and kneaded uniformly. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and extruding it through an outlet equipped with a die with an inner diameter of 1.8 mm and an inner hole pin with an outer diameter of 0.5 mm. The molded body of the extruded gas generating agent composition was cut to a length of 2.0 mm and dried to obtain a gas generating agent composition with a hole in the center of a cylinder.

[0045] [Evaluation of manufacturing stability] The manufacturing stability of the gas generating agent compositions in Example 1 and Comparative Examples 1-4 was evaluated. When the gas-generating molded product was extruded using an extruder, a ○ was used if continuous operation for 1 hour was possible, and a × was used if the extruder stopped due to an increase in extrusion pressure (i.e., could not operate continuously for 1 hour). The results are shown in Table 1.

[0046] To ensure uniform performance, 0.5% by weight of graphite was added to the gas generating agent compositions obtained in Example 1 and Comparative Examples 1-4, and the compositions were coated with this mixture. After that, calorific value measurements, combustion performance measurements, and exhaust gas measurements were performed using the methods described below.

[0047] [Heat generation measurement] The calorific value of the gas generating agent compositions of Example 1 and Comparative Examples 1-4 was measured. The calorific value was measured using a bomb calorimeter. 1.0 g of the gas generating agent composition obtained in Example 1 and Comparative Examples 1-4 was weighed into a sealed stainless steel container, and the lid was closed with a nichrome wire in contact with it. This was then placed in an insulated container filled with water, and the nichrome wire was energized to ignite it, causing the composition to burn completely. The calorific value was calculated from the rising water temperature and specific heat. The results are shown in Table 1.

[0048] [Combustion performance measurement] 1000 mg of the gas generating agent composition obtained in Example 1 and Comparative Examples 1-4 was filled into a 10 cc sealed combustion container, and the gas generating agent composition was burned. The time to half the time to reach the maximum achievable pressure (Pt50%) was measured. The results are shown in Table 1. Graphs for Example 1 and Comparative Example 1 are shown in Figure 1.

[0049] [Exhaust gas measurement] The composition of the generated gases from the gas generating agent compositions of Example 1 and Comparative Examples 1-4 was measured. 1640 mg of each gas generating agent composition was filled into a gas generator. The gas generators filled with each gas generating agent were placed in a 60-liter tank and operated at room temperature (23°C). The CO concentration of the generated gas discharged into the tank was measured using a Gastec gas detector tube (for CO detection: No. 1L) with a Gastec GV-100 gas sampling device manufactured by Gastec Co., Ltd. The concentration values ​​were obtained 5 minutes after operation. The results are shown in Table 1.

[0050] [Table 1]

[0051] As is clear from the above results, the gas generating agent composition of the present invention exhibited low calorific value, a fast combustion rate, low CO emission, and good manufacturing stability.

Claims

1. A gas generating agent composition containing fuel components, an oxidizer, and activated carbon, The aforementioned fuel component is a nitrogen-containing organic compound. The oxidizing agent component is one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates. A gas generating agent composition in which the raw material for the activated carbon is coconut shell.

2. A gas generating agent composition containing fuel components, an oxidizer, and activated carbon, The aforementioned fuel component is a nitrogen-containing organic compound. The oxidizing agent component is one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates. The specific surface area of ​​the activated carbon is 1000 m². ２ / g or more 2500m ２ A gas generating agent composition having a concentration of less than or equal to / g.

3. The gas generating agent composition according to claim 1 or 2, wherein the average particle size D50 of the activated carbon is 1.0 μm or more and 100 μm or less.

4. The gas generating agent composition according to claim 1 or 2, wherein the amount of activated carbon added is 1.0% by weight or more and 5.0% by weight or less of the total amount of the gas generating agent composition.

5. A gas generator containing the gas generating agent composition according to claim 1 or 2.

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