Gas generating agent composition and gas generator

Abstract

This invention provides a gas generating agent composition with an adjusted oxygen balance that achieves both high heat output and high combustion speed. [Solution] A gas generating agent composition containing a fuel component, an oxidizer, and a carbon material, 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 having an oxygen balance of -0.13 g / g or more and -0.02 g / g or less.

Description

Technical Field

[0001] The present invention relates to a gas generant composition and a gas generator, and is suitably used for airbag devices and seatbelt pretensioner devices.

Background Art

[0002] Airbag devices and seatbelt pretensioner devices are employed as safety devices for protecting occupants in the event of a collision of vehicles typified by automobiles. In an airbag device, when a vehicle is involved in a collision, an electric signal is sent from a collision detection sensor to a gas generator for airbag deployment, which combusts the gas generant loaded inside the gas generator to generate gas, and the airbag is deployed by the gas pressure.

[0003] In a seatbelt pretensioner device, when a sensor detects a vehicle collision, an electric signal causes the gas generant composition loaded in the gas generator for a seatbelt pretensioner to combust, generate gas, and actuate the seatbelt retraction mechanism by the gas pressure.

[0004] Various gas generants have been developed as important components of the performance of gas generators employed in such airbag devices, seatbelt pretensioner devices and the like.

[0005] Conventionally, smokeless powder mainly composed of nitrocellulose has been employed for gas generant compositions used in gas generators for seatbelt pretensioner devices. However, since smokeless powder generates a large amount of CO gas and has low heat resistance, gas generant compositions other than smokeless powder have been demanded 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] One way to reduce the calorific value of the above-mentioned gas generating agent composition is to adjust the composition ratio of the raw materials used and control the combustion state. That is, by changing the composition ratio of the raw materials from the composition ratio that allows for complete combustion (i.e., a state where the oxygen balance is 0), the calorific value decreases due to incomplete combustion. However, since the amount of gas produced is also reduced, the combustion performance generally deteriorates.

[0008] Patent Document 1 discloses a gas generating agent consisting of ammonium nitrate as an oxidizer and activated carbon as a fuel. Gas generating agents containing ammonium nitrate deteriorate when installed in vehicles for long periods, and because deteriorated gas generating agents cause abnormal combustion, their use in vehicle safety devices is currently prohibited. Furthermore, it is stated that an oxygen balance close to 0 is ideal.

[0009] Patent Document 2 discloses a fuel selected from carbazoles, an oxidizing agent combining nitrates or nitrate esters, and a gas generating agent in which powdered microcrystalline carbon is part of the additive. However, the powdered microcrystalline carbon used here is intended to improve the combustion rate, and there is no description regarding oxygen balance or calorific value. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 11-92265 [Patent Document 2] Japanese Patent Publication No. 2006-306630 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention aims to provide a gas generating agent composition with an adjusted oxygen balance that achieves both high heat output and high combustion speed. [Means for solving the problem]

[0012] The present invention is as described in [1] to [5] below. [1] A gas generating agent composition containing a fuel component, an oxidizer, and a carbon material, 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 having an oxygen balance of -0.13 g / g or more and -0.02 g / g or less. [2] The gas generating agent composition according to the preceding paragraph [1], wherein the carbon material is activated carbon or graphite. [3] The gas generating agent composition according to item [1] or [2] above, wherein the average particle size D50 of the carbon material is 1.0 μm or more and 100 μm or less. [4] The gas generating agent composition according to any one of the preceding paragraphs [1] to [3], wherein the amount of carbon material 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 described in any one of the preceding paragraphs [1] to [4]. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a gas generating agent composition with an adjusted oxygen balance that achieves both high heat output and high combustion speed. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in detail below. The description of the constituent requirements set forth 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 of the present invention is changed. In the present invention, when the expression "~" is used, it is used as an expression including the numerical values before and after it.

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

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

[0017] The nitrogen-containing organic compound used as the fuel component is preferably one that has the physical property of thermally decomposing triggered by combustion and releasing nitrogen as a main component, and examples 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, 5,5'-azotetrazole diguanidinium salt, 5-oxo-1,2,4-triazole, trihydrazinotriazine, biuret, azodicarbonamide, biurea, azodicarbonamide, hydrazine metal complex nitrate, hydrazine nitrate complex, carbohydrazide, carbohydrazide transition metal complex nitrate, carbohydrazide nitrate complex, ammonium oxalate, oxalic acid monohydrazide, oxalic acid dihydrazide, sodium dicyanamide, bis(dicyandiamide) copper(I) nitrate, ammine complex dicyanamide, dicyandiamide, or salts thereof with alkali metals, alkaline earth metals or transition metals. These nitrogen-containing organic compounds may be used alone, and it is also a preferable example to use a mixture of two or more selected from the above group for the purpose of adjusting performance.

[0018] Among these, one or more selected from the group consisting of guanidine nitrate, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate, nitroguanidine, and aminonitroguanidine are preferable, and guanidine nitrate is particularly preferable.

[0019] The oxidizer component (hereinafter may be referred to as "component B") supplies oxygen necessary for combustion to combustible organic compound components. As the oxidizer, it is preferable to use one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates and chlorates, and it is more preferable when the oxidizer is a perchlorate or a basic metal nitrate. 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 a carbon material (hereinafter sometimes referred to as "component C") that can be used. The carbon material makes it possible to maintain combustion performance and reduce the amount of heat generated.

[0022] Examples of carbon materials include activated carbon, graphite, diamond, amorphous carbon, carbon black, Ketjenblack, carbon nanotubes, carbon nanohorns, graphene, and fullerene, with activated carbon or graphite being preferred.

[0023] 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 1.0 to 50 μm, and particularly preferably in the range of 1.0 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.

[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 a certain amount ( / g), the combustion rate tends to slow down.

[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, magnesium stearate, calcium stearate, and polyvinyl alcohol. Examples of binders for extrusion include metal salts of carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, 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, polyacrylamide, and stearic acid. 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 oxygen balance calculated based on the components in the gas generating agent composition is preferably -0.13 g / g or more and -0.02 g / g or less, more preferably -0.13 g / g or more and -0.05 g / g or less, and particularly preferably -0.13 g / g or more and -0.07 g / g or less. The oxygen balance refers to the excess or deficiency of oxygen necessary to completely oxidize the gas generating agent composition; a positive value indicates an excess of oxygen, and a negative value indicates an oxygen deficiency. This oxygen balance can be calculated from the oxidation-reduction reaction of the gas generating agent composition (the entire gas generating composition). Normally, an oxygen balance of 0 is considered to be the state of maximum combustion efficiency, but the amount of heat generated is also maximum. The present invention has found the optimal conditions for oxygen balance in order to maintain the combustion rate while reducing the amount of heat generated.

[0033] The specific method for calculating the oxygen balance assumes that all C and H are oxidized to CO2 and H2O. The amount of raw material used in 1g of the gas generating agent composition (in grams) is divided by the molecular weight of the raw material, and this is multiplied by the number of moles of oxygen generated / consumed during the complete combustion of the raw material to calculate the oxygen balance for one raw material. The same calculation is performed for all raw materials, and the sum of the obtained oxygen balances is multiplied by the molecular weight of 16 per mole of oxygen to calculate the oxygen balance.

[0034] 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, tablet molding, etc., and then a lubricant can be added to coat the surface.

[0035] The coating method is not particularly limited, but examples include mixing the molded mixture and lubricant in a mixer, 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 similar device.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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 a compressed gas such as argon and the gas generating agent composition. [Examples]

[0040] 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.

[0041] The methods for measuring the average particle size and specific surface area shown in the examples and comparative examples are described below. 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. 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 obtained curve by BET analysis using the multipoint method in the region of relative pressure P / P0 = 0.01 to 0.10, and the specific surface area was calculated from this straight line.

[0042] <Example 1> Guanidine nitrate 47.8% by weight, potassium perchlorate 44.5% 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 A mixed powder with an oxygen balance of -0.078 g / g (average particle size 22.1 μm) at 3.0 wt% was mixed in a ball mill, and 14 wt% 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.

[0043] <Example 2> Guanidine nitrate 47.8% by weight, potassium perchlorate 44.5% 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 A mixed powder with an oxygen balance of -0.078 g / g (average particle size 14.0 μm) at 3.0 wt% was mixed in a ball mill, and 14 wt% 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.

[0044] <Comparative Example 1> A mixed powder with an oxygen balance of 0, consisting of 47.8% by weight of guanidine nitrate, 44.5% by weight of potassium perchlorate, 2.0% by weight of basic copper nitrate, 1.1% by weight of polyacrylamide, and 4.6% by weight of hydroxypropyl methylcellulose, was mixed in a ball mill, and then 14% by weight of deionized water was added in a kneader and the mixture was 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 extruded gas generating agent composition was cut into 2.0 mm lengths and dried to obtain a gas generating agent composition with a cylindrical shape and a hole in the center.

[0045] <Comparative Example 2> A mixed powder consisting of 58.5% by weight guanidine nitrate, 33.8% by weight potassium perchlorate, 2.0% by weight basic copper nitrate, 1.1% by weight polyacrylamide, and 4.6% by weight hydroxypropyl methylcellulose, with an oxygen balance of -0.078 g / g, 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 extruded gas generating agent composition was cut into 2.0 mm lengths and dried to obtain a gas generating agent composition with a cylindrical shape and a hole in the center.

[0046] Table 1 shows the composition ratios of the molded bodies of the gas generating agent compositions for Examples 1 and 2 and Comparative Examples 1 and 2.

[0047] [Heat generation measurement] The calorific value of the gas generating agent compositions of Examples 1 and 2 and Comparative Examples 1 and 2 was measured. The calorific value was measured using a bomb calorimeter. 1.0 g of the gas generating agent compositions obtained in Examples 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 compositions obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were filled into a 10 cc sealed combustion container, and the gas generating agent compositions were burned. The time to half the time to reach the maximum achievable pressure (Pt50%) was measured. The results are shown in Table 1.

[0049] [Table 1]

[0050] As is clear from the results above, the gas generating agent compositions of Examples 1 and 2 of this application had lower calorific values ​​than the gas generating agent composition of Comparative Example 1, and the decrease in combustion performance (increase in numerical value) was suppressed. The gas generating agent composition of Comparative Example 2, which did not contain carbon material, had a lower calorific value, but a significant decrease in combustion performance (increase in numerical value) occurred. Gas generating agents with a combustion performance of 2.5 ms or higher cannot be used because they cannot satisfy the combustion performance required for gas generators.

Claims

1. A gas generating agent composition containing a fuel component, an oxidizer, and a carbon material, 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 having an oxygen balance of -0.13 g / g or more and -0.02 g / g or less.

2. The gas generating agent composition according to claim 1, wherein the carbon material is activated carbon or graphite.

3. The gas generating agent composition according to claim 1 or 2, wherein the average particle size D50 of the carbon material 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 carbon material 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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