Gas generating agent composition

Abstract

To provide a gas generating agent composition that ignites at a relatively low-temperature phase in which a gas generator does not rupture.SOLUTION: A gas generating agent composition comprises a fuel component and an oxidizing agent component. The gas generating agent composition further comprises, as the fuel component, a compound having a lactone structure and having a melting point or a decomposition point of 90°C or higher but lower than 250°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a gas generating composition, which is suitable for use in airbags. [Background technology]

[0002] When a car detects a collision, an electrical signal is sent to the gas generator, which activates a squib inside the gas generator. The resulting heat causes the gas generating agent to burn, generating gas that inflates the airbag. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-089347 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, Patent Document 1 describes a gas generant composition comprising a fuel and an oxidizer selected from plastic and rubber materials having a melting point or decomposition point of 250°C or higher in order to improve the heat resistance of the gas generant. However, if the melting point or decomposition point of the gas generant is high, the ignition temperature of the gas generant also tends to be high, and when the gas generator is exposed to high temperatures due to a vehicle fire or the like and the gas generant burns, the container may burst because it cannot withstand the combustion pressure, potentially killing or injuring the occupants and those around it.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide a gas generating composition that ignites at a relatively low temperature so that the gas generator will not explode. [Means for solving the problem]

[0006] That is, the present invention is as set forth in the following [1] to [6]. [1] A gas generant composition containing a fuel component and an oxidizer component, A gas generating composition comprising, as the fuel component, a compound having a lactone structure and having a melting point or decomposition point of 90°C or higher and lower than 250°C. [2] The gas generating composition according to the above item [1], wherein the content of the fuel component is 10 to 80 wt % and the content of the oxidizer component is 20 to 90 wt % of the total amount of the fuel component and the oxidizer component. [3] The gas generant composition according to the above item [1] or [2], wherein the compound having a lactone structure is a compound having a 2-pyrone structure. [4] The gas generant composition according to any one of the preceding items [1] to [3], wherein the oxidizer component is one or more selected from the group consisting of nitrates, metal nitrates, perchlorates, and chlorates. [5] The gas generant composition according to any one of the preceding items [1] to [4], further comprising guanidine nitrate as the fuel component. [6] The gas generating composition according to any one of the preceding items [1] to [5], which has spontaneous ignition properties. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a gas generant composition that ignites at a relatively low temperature. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes in detail an embodiment of the present invention, but the following description of the constituent elements is one example (typical example) of an embodiment of the present invention, and the present invention is not limited to the following content unless the gist of the present invention is changed. Note that when the expression "to" is used in the present invention, it is used as an expression including the numerical values ​​before and after it.

[0009] The gas generant composition of this embodiment contains a fuel component and an oxidizer component, and contains, as the fuel component, a compound having a lactone structure and a melting point or decomposition point of 90°C or higher and lower than 250°C.

[0010] The compound having a lactone structure refers to lactone, a compound having a group obtained by removing a hydrogen atom from a lactone, and a compound having a ring structure containing a lactone structure. Specific examples include 4,5-dicarboxy-γ-pentadecanolactone, 2,3-O-isopropylidene-D-ribonic acid γ-lactone, homogentisic acid γ-lactone, 5-hydroxynorbornane 2,6-lactone, D-(+)-glucono-1,5-lactone, D-glucurono-6,3-lactone, and a compound having a 2-pyrone structure.

[0011] Specific examples of the compound having a 2-pyrone structure include 4-hydroxy-6-methyl-2-pyrone, coumaric acid, 4-hydroxycoumarin, umbelliferone, 3-hydroxycoumarin, 6-hydroxy-4-methylcoumarin, 4-ethoxycoumarin, 6-methoxy-4-methylcoumarin, xanthotoxin, 6,7-dimethoxy-4-methylcoumarin, 4-hydroxy-3-nitrocoumarin, etc. The compound having a 2-pyrone structure is preferably represented by the following formula (1):

[0012] [ka]

[0013] In the above formula (1), R1 to R4 each independently represent a hydrogen atom, a hydroxy group, or an alkyl group, or two or more selected from R1 to R4 may be bonded to form a ring structure. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably has 1 to 5 carbon atoms.

[0014] The compound having a lactone structure preferably has a hydroxy group in the molecule.

[0015] The method for measuring the melting point or decomposition point of the compound having a lactone structure is not particularly limited, and can be determined, for example, using a commercially available differential scanning calorimeter (DSC). A melting point or decomposition point of 90°C or higher can prevent the gas generating agent from unintentionally burning when the temperature inside the automobile becomes high. Furthermore, a melting point or decomposition point of less than 250°C can enable the gas generator to ignite at a relatively low temperature where it will not explode. The melting point or decomposition point is more preferably 130°C or higher but lower than 210°C, and particularly preferably 150°C or higher but lower than 200°C.

[0016] The gas generant composition of this embodiment may contain, as a fuel component, a compound other than a compound having a lactone structure and having a melting point or decomposition point of 90°C or higher and lower than 250°C. The fuel component is not particularly limited as long as it is a combustible organic compound, and carbon-based organic compounds with a high carbon content or nitrogen-containing organic compounds with a high nitrogen content are widely used in gas generants and are preferably used as the gas generant of this embodiment.

[0017] When using a carbon-based organic compound with a high carbon content as a fuel component, a compound with a high oxygen content in the fuel component molecule is preferred to promote combustion and suppress the production of toxic carbon monoxide. Specific carbon-based organic compounds include pentaerythritol, glucose, sorbose, ascorbic acid or its salt, citric acid or its salt, lactose, sorbitose, gluconic acid or its salt, glucuronic acid or its salt, fructose, erythritol, xylitol, deltaic acid or its salt, squaric acid or its salt, croconic acid or its salt, rhodizonic acid or its salt, cyclohexanehexanone, 1,2,3,4,5-cyclohexanepentol, xylitol, arabitol, and adonitol. While these carbon-based organic compounds may be used alone, a mixture of two or more compounds selected from the above group is also preferred for performance adjustment. It is also preferred to use them in combination with the nitrogen-containing organic compounds described below.

[0018] The nitrogen-containing organic compound used as a fuel component is preferably one that has the physical property of thermally decomposing upon combustion and releasing nitrogen as a main component, and examples thereof include guanidine derivatives, tetrazole derivatives, triazole derivatives, bitriazole derivatives, bitetrazole derivatives, azodicarbonamide derivatives, bidrazine 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, bitetrazole metal salts, 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 Examples of suitable nitrogen-containing organic compounds include hydrazine diguanidinium salts, 5-oxo-1,2,4-triazole, trihydrazinotriazine, biuret, azodicarbonamide, biurea, azodicarbonamide, hydrazine metal complex nitrates, hydrazine nitrate complexes, carbohydrazides, carbohydrazide transition metal complex nitrates, carbohydrazide nitrate complexes, ammonium oxalate, oxalic acid monohydrazide, oxalic acid dihydrazide, sodium dicyanamide, bis(dicyandiamide)copper(I) nitrate, ammine complex dicyanamide, dicyandiamide, and alkali metal, alkaline earth metal, or transition metal salts thereof. While these nitrogen-containing organic compounds may be used alone, it is also preferred to use a mixture of two or more compounds selected from the above group to adjust performance. It is also preferred to use them in combination with the carbon-based organic compounds.

[0019] Among these, one or more selected from guanidine nitrate, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate, nitroguanidine, and aminonitroguanidine are preferred, with guanidine nitrate being particularly preferred.

[0020] When guanidine nitrate is added and mixed in an amount of 10 to 30% by weight based on the total weight of the gas generant composition, the time until ignition when the gas generant composition is placed in a furnace at a constant temperature is shortened. Therefore, by adding and mixing guanidine nitrate as a fuel component, the melting initiation temperature becomes lower than that of the fuel alone, and the contact area between the fuel and the oxidizer becomes larger, thereby shortening the ignition time.

[0021] The oxidizer component used in the gas generant composition of this embodiment supplies oxygen necessary for combustion to the combustible organic compound component. As the oxidizer, it is preferable to use one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates. Nitrates include ammonium nitrate, phase-stabilized ammonium nitrate, and alkali or alkaline earth metal nitrates, which include sodium nitrate, potassium nitrate, strontium nitrate, magnesium nitrate, calcium nitrate, barium nitrate, and the like.

[0022] The phase-stabilized ammonium nitrate that can be used in the gas generant composition of this embodiment is not particularly limited by the method of phase stabilization. A known technique is to add a potassium salt to ammonium nitrate. In this embodiment, ammonium nitrate that has been phase-stabilized by adding a small amount of potassium perchlorate, potassium nitrate, potassium chlorate, potassium nitrite, potassium sulfate, potassium chloride, or potassium oxalate to ammonium nitrate is preferred. In terms of thermal stability, oxidizing ability, and the like, phase-stabilized ammonium nitrate stabilized with potassium perchlorate or potassium nitrate is particularly preferred.

[0023] Examples of basic metal nitrates include basic copper nitrate, basic cobalt nitrate, basic zinc nitrate, basic magnesium nitrate, and basic iron nitrate.

[0024] Examples of perchlorates and chlorates include ammonium salts, alkali metal salts, and alkaline earth metal salts thereof.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.

[0025] These oxidizing agents may be used singly, but for the purpose of adjusting performance, a mixed oxidizing agent in which two or more oxidizing agents selected from the above group are mixed can also be used as a preferred example.

[0026] The oxidizing agent component is preferably one or more selected from basic copper nitrate, potassium nitrate, strontium nitrate, potassium perchlorate, and ammonium perchlorate.

[0027] In the gas generant composition of this embodiment, the content of the fuel component in the total amount of the fuel component and the oxidizer component is preferably 10 to 80 wt %, more preferably 40 to 60 wt %. Furthermore, the content of the oxidizer component in the total amount of the fuel component and the oxidizer component is preferably 20 to 90 wt %, more preferably 40 to 60 wt %. By being in the above range, desired properties can be obtained.

[0028] The gas generant composition of this embodiment may further contain an additive. Typical additives that can be used in gas generants for gas generators can be used as the additive. For example, additives such as binders for imparting moldability and shape retention, slag formers for enabling easy filtration of combustion residues, combustion adjusters, catalysts, lubricants, etc. can be used. These additives can be used alone or in combination of two or more.

[0029] As the binder that can be used in the gas generant composition of this embodiment, binders that can generally be used as additives for gas generants for gas generators can be used, and the binder to be used should be considered depending on the method for molding the gas generant, specifically, whether a tablet molding method or an extrusion molding method is adopted.

[0030] 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, and organic binders such as crystalline cellulose, magnesium stearate, calcium stearate, and polyvinyl alcohol. Examples of binders for extrusion molding include metal salts of carboxymethylcellulose, methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methylcellulose, hydroxypropyl methylcellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, and polysaccharide derivatives such as starch, and organic binders such as polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, and stearic acid. Alternatively, mixtures of these may be used.

[0031] The slag-forming agent that can be used in the gas generant composition of this embodiment can be any slag-forming agent that can generally be used as an additive in gas generants for gas generators, and is an additive that makes it possible to easily filter the combustion residue generated after combustion of the gas generant. Specific examples of slag-forming agents include silicon nitride, silicon carbide, silicon dioxide, aluminum oxide, titanium oxide, silicates, acid clay, clay, etc. The content of the slag-forming agent in the gas generant is 0 to 10 wt %, more preferably 2 to 5 wt %.

[0032] The combustion modifier that can be used in the gas generant composition of this embodiment is an additive for modulating the combustion of the gas generant. Usable combustion modifiers may be any that can modulate the combustion of the gas generant, and specific examples include metal oxides such as iron oxide, nickel oxide, copper oxide, zinc oxide, manganese oxide, chromium oxide, cobalt oxide, molybdenum oxide, vanadium oxide, and tungsten oxide; metal hydroxides such as copper hydroxide, cobalt hydroxide, zinc hydroxide, and aluminum hydroxide; and carbons such as activated carbon powder, graphite, and carbon black. The content of the combustion modifier in the gas generant is 0 to 20% by weight, and more preferably 0 to 10% by weight.

[0033] The gas generant composition of this embodiment not only ignites when an igniter is activated, but also preferably ignites at a relatively low temperature where the gas generator will not explode even in the event of a vehicle fire, etc., regardless of the activation of the igniter (i.e., has automatic ignition properties).

[0034] When a gas generator is exposed to flames due to a vehicle fire or the like and the explosive composition inside burns, the container cannot withstand the combustion pressure and breaks, scattering fragments into the surrounding area, which may injure or kill the occupants and people nearby. Therefore, there is a need for a gas generant composition that ignites at a temperature lower than the temperature at which the strength of the gas generator decreases. When the gas generator has an aluminum container, the ignition temperature is preferably 130°C or higher and lower than 210°C, in consideration of the strength of aluminum, and more preferably 130°C or higher and lower than 170°C. Substances that ignite at temperatures below 130°C have problems with long-term storage stability. [Example]

[0035] 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 as long as the gist of the present invention is not changed.

[0036] <Examples 1 to 4, Comparative Example 1> 4-hydroxy-6-methyl-2-pyrone (decomposition point: 190°C) and guanidine nitrate (melting point: 214°C) as fuel components, and basic copper nitrate as oxidizer component were placed in a mortar in the proportions shown in Table 1, and dry mixed with a pestle to obtain a mixed powder of the gas generant composition.

[0037] <Ignition wait test> In order to examine the spontaneous ignition properties of the gas generant compositions obtained in Examples 1 to 4 and Comparative Example 1, the following ignition wait test was conducted. The temperature of the ignition pot of a Krupp-type ignition point tester (manufactured by Kuramochi Scientific Instruments Manufacturing Co., Ltd., model number: KRS-RG-9000) was kept at 170°C, and the time from when 0.02 g of the gas generant composition was placed in the ignition pot until smoke was generated or ignition occurred was measured. If smoke generation or ignition was not confirmed after 3 minutes, the composition was deemed to have failed to ignite. The measurement results are shown in Table 1.

[0038] [Table 1]

[0039] In all of Examples 1 to 4, the ignition waiting time was within 60 seconds, confirming that they had spontaneous ignition properties. It was also confirmed that the ignition waiting time was shortened by using guanidine nitrate as a fuel component. On the other hand, in Comparative Example 1, which did not use 4-hydroxy-6-methyl-2-pyrone, neither smoke nor fire was generated even after the ignition waiting time had elapsed for 3 minutes, confirming that they did not have spontaneous ignition properties.

[0040] <Examples 5 and 6, Comparative Examples 2 and 3> The fuel components, 4-hydroxy-6-methyl-2-pyrone (decomposition point: 190°C), D-glucurono-6,3-lactone (melting point: 178°C), guanidine nitrate (melting point: 214°C), and 40% by weight of 7,8-dihydroxycoumarin (decomposition point: 256°C), and the oxidizer component, 60% by weight of basic copper nitrate, were placed in a mortar and dry-mixed with a pestle to obtain a mixed powder of the gas generant composition.

[0041] <Ignition wait test> To examine the spontaneous ignition properties of the gas generant compositions obtained in Examples 5 and 6 and Comparative Examples 2 and 3, the following ignition wait test was conducted. The temperature of the ignition pot of a Krupp-type ignition point tester (manufactured by Kuramochi Scientific Instruments Manufacturing Co., Ltd., model number: KRS-RG-9000) was kept at 180°C, and the time from when 0.02 g of the gas generant composition was placed in the ignition pot until smoke was generated or ignition occurred was measured. If smoke generation or ignition was not confirmed after 3 minutes, the composition was deemed to have failed to ignite. The measurement results are shown in Table 2.

[0042] [Table 2]

[0043] In Examples 5 and 6, the ignition waiting time was within 60 seconds, confirming that they had spontaneous ignition properties. On the other hand, in Comparative Examples 2 and 3, no smoke was generated or ignition occurred even after the ignition waiting time had elapsed for 3 minutes, confirming that they did not have spontaneous ignition properties.

[0044] <Examples 7 and 8, Comparative Examples 4 to 7> The fuel components, 4-hydroxy-3-nitrocoumarin (decomposition point: 171°C), guanidine nitrate (melting point: 214°C), and 40% by weight of 7,8-dihydroxycoumarin (decomposition point: 256°C), and the oxidizer components, 60% by weight of potassium nitrate and potassium perchlorate, were placed in a mortar and dry-mixed with a pestle to obtain a mixed powder of the gas generant composition.

[0045] <Ignition wait test> To examine the spontaneous ignition properties of the gas generant compositions obtained in Examples 7 and 8 and Comparative Examples 4 to 7, the following ignition wait test was conducted. The temperature of the ignition pot of a Krupp ignition point tester (manufactured by Kuramochi Scientific Instruments Manufacturing Co., Ltd., model number: KRS-RG-9000) was kept at 180°C, and the time from when 0.02 g of the gas generant composition was placed in the ignition pot until smoke was generated or ignition occurred was measured. If smoke generation or ignition was not confirmed after 3 minutes, the composition was deemed to have failed to ignite. The measurement results are shown in Table 3.

[0046] [Table 3]

[0047] In Example 8, the ignition waiting time was within 60 seconds, and it was confirmed that the product had spontaneous ignition properties. In Example 7, smoke generation was confirmed when the waiting time was 9 seconds, but ignition was not confirmed visually. On the other hand, in Comparative Example 1, which did not use 4-hydroxy-6-methyl-2-pyrone, neither smoke nor ignition occurred even after the ignition waiting time had passed 3 minutes, and it was confirmed that the product did not have spontaneous ignition properties.

Claims

1. A gas generant composition containing a fuel component and an oxidizer component, The gas generating composition contains, as the fuel component, a compound having a lactone structure and having a melting point or decomposition point of 90°C or higher and lower than 250°C.

2. 2. The gas generant composition according to claim 1, wherein the content of the fuel component is 10 to 80 wt % and the content of the oxidizer component is 20 to 90 wt % of the total amount of the fuel component and the oxidizer component.

3. 2. The gas generant composition according to claim 1, wherein the compound having a lactone structure is a compound having a 2-pyrone structure.

4. 2. The gas generant composition according to claim 1, wherein the oxidizer component is one or more selected from the group consisting of nitrates, metal nitrates, perchlorates, and chlorates.

5. 2. The gas generant composition according to claim 1, further comprising guanidine nitrate as the fuel component.

6. The gas generant composition according to any one of claims 1 to 5, which has spontaneous ignition properties.

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