Gas-generating agent molded article, method for producing same, and gas generator

Abstract

Provided are: a gas-generating agent molded article having a high bulk density; a method for producing the same; and a gas generator. This gas-generating agent molded article has a surface roughness Ra of at most 0.40 μm. This gas generator contains the gas-generating agent molded article. This method for producing a gas-generating agent molded article comprises: a step (A) for mixing a fuel component and an oxidant component to obtain a mixture; a step (B1) for molding the mixture and coating the surface of the molded article with a lubricant; and / or a step (B2) for molding the mixture and smoothing the surface of the molded article through a physical treatment.

Description

Gas generating agent molded product, its manufacturing method, and gas generator

[0001] The present invention relates to a gas generating agent molded product, a method for producing the same, and a gas generator.

[0002] 2. Description of the Related Art Airbag devices and seatbelt pretensioner devices are used as safety devices for protecting occupants in vehicle collisions, such as automobile collisions.

[0003] In the event of a vehicle collision, an airbag device sends an electrical signal from a collision detection sensor to a gas generator for deploying the airbag, which burns a gas generating agent loaded in the gas generator to generate gas, and the gas pressure deploys the airbag.

[0004] On the other hand, when a sensor detects a vehicle collision, a seatbelt pretensioner device uses an electrical signal to combust a gas generating agent loaded in a gas generator for the seatbelt pretensioner, generating gas, and the gas pressure activates the seatbelt retraction mechanism.

[0005] Various gas generating agents have been developed, which are important components in determining the performance of the gas generators employed in such airbag devices and the like.

[0006] For example, Patent Document 1 discloses a gas generating agent using graphite as a binder and a method for producing the same.

[0007] WO 2004 / 048296

[0008] In Example 3 of Patent Document 1, a gas generating agent molded product is obtained by mixing and kneading fuel, oxidizer, graphite, etc. However, the gas generating agent molded product obtained by this manufacturing method has poor slipperiness and a low bulk density because graphite is kneaded into the molded product. Therefore, when used in a gas generator having a specified volume, the filling amount of the gas generating agent molded product is reduced, making it difficult to satisfy the required characteristics.

[0009] The present invention has been made in view of the above circumstances, and has as its object to provide a gas generating agent molded product having a high bulk density, a method for producing the same, and a gas generator.

[0010] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the following invention meets the above object, thereby completing the present invention.

[0011] That is, the present invention relates to the following inventions. <1> A gas generant molded product having a surface roughness Ra of 0.40 μm or less. <2> The gas generant molded product according to <1>, which contains a fuel component and an oxidizer component. <3> The gas generant molded product according to <2>, wherein the fuel component is a nitrogen-containing organic compound, and the oxidizer component is one or more selected from the group consisting of potassium perchlorate and basic copper nitrate. <4> The gas generant molded product according to <2> or <3>, which further contains a binder, wherein the total content of the fuel component and the oxidizer component is 90.0% by weight or more and 99.0% by weight or less, the weight ratio of the fuel component:the oxidizer component is 60:40 to 45:55, the oxidizer component includes potassium perchlorate and basic copper nitrate, and the content of the basic copper nitrate is 0.5% by weight or more and 4.0% by weight or less. <5> The gas generant molded product according to any one of <2> to <4>, wherein the oxidizer component comprises potassium perchlorate and basic copper nitrate, and the content of the basic copper nitrate is 0.5% by weight or more and 2.0% by weight or less. <6> The gas generant molded product according to any one of <1> to <5>, wherein the surface is coated with a lubricant. <7> The gas generant molded product according to <6>, wherein the lubricant is one or more selected from the group consisting of graphite, magnesium stearate, zinc stearate, calcium stearate, sodium stearate, boron nitride, highly dispersed silica, and talc. <8> The gas generant molded product according to <6> or <7>, wherein the amount of the lubricant added is 0.05% by weight or more and 1.0% by weight or less based on the total amount of the gas generant molded product. <9> A gas generator containing the gas generant molded product according to any one of <1> to <8>. <10> A method for producing a gas generant molded product, comprising: a step (A) of mixing a fuel component and an oxidizer component to obtain a mixture; a step (B1) of molding the mixture and coating the surface of the molded product with a lubricant; and / or a step (B2) of molding the mixture and smoothing the surface of the molded product by physical treatment.

[0012] According to the present invention, it is possible to provide a gas generating agent molded product having a high bulk density, a method for producing the same, and a gas generator.

[0013] 1 shows a photograph of the appearance of a molded gas generating agent of Example 1. 2 shows the results of combustion performance test 1 of the molded gas generating agent. 3 shows the results of combustion performance test 2 of the molded gas generating agent.

[0014] 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 "~" is used in the present invention, it is used as an expression including the numerical values ​​before and after it.

[0015] <Gas Generant Molded Product> The present invention relates to a gas generant molded product having a surface roughness Ra of 0.40 μm or less (hereinafter, may be referred to as the "gas generant molded product of the present invention.") By having a specific surface roughness Ra, the gas generant molded product of the present invention has a high bulk density, excellent fillability into a gas generator, and can easily adjust the required performance of the gas generator.

[0016] Although there is no particular limitation on the lower limit of the surface roughness Ra, in reality it is about 0.15 μm. From the viewpoint of improving the filling property and improving the productivity, the surface roughness Ra of the gas generating agent molded product of the present invention is preferably 0.15 to 0.38 μm, more preferably 0.18 to 0.36 μm, and even more preferably 0.20 to 0.35 μm. With such a surface roughness Ra, the filling property into the gas generator is improved.

[0017] The surface roughness Rz of the gas generating agent molded product of the present invention is preferably 1.0 to 5.0 μm, more preferably 1.0 to 4.5 μm, even more preferably 1.3 to 4.0 μm, even more preferably 1.6 to 3.5 μm, and particularly preferably 2.0 to 3.3 μm. Such a surface roughness Rz improves the fillability into a gas generator.

[0018] Here, the "surface roughness Ra" of the gas generant molding of the present invention in this application refers to the arithmetic mean roughness, and is determined by the following method using a shape measuring laser microscope (Keyence VK-X100). 1) Using a 5x magnification lens, adjust the position and focus so that the center of the sample is at the center of the measurement image. 2) Adjust the focus using a 50x magnification lens. 3) Set the measurement mode to simple measurement, and measure the sample shape using automatic measurement. 4) Use analysis software to perform surface tilt correction (automatic) on the measurement data and correct the tilt. 5) Set the analysis mode to line roughness (line type: horizontal line) with cutoff λc = 0.08 mm, and measure the surface roughness Ra of a single horizontal line in the center of the measurement screen. 6) Perform the same operation three times to calculate the average Ra, and use this average as the "surface roughness Ra" of the gas generant molding of the present invention.

[0019] Furthermore, the "surface roughness Rz" of the gas generating agent molded product of the present invention refers to the maximum height roughness, and is determined in the same manner as the method for determining the surface roughness Ra described above, except that in 5) and 6) the surface roughness Rz is measured instead of the surface roughness Ra, and the average value of Rz is calculated.

[0020] The gas generating agent molded product of the present invention may have an average surface roughness Ra of 0.40 μm or less, and examples of such a gas generating agent molded product include those whose surfaces are coated with a lubricant and those whose surfaces are smoothed by physical treatment.

[0021] [Surface Coating] One preferred embodiment of the gas generant molded product of the present invention is one in which the surface is coated with a lubricant. Coating the surface with a lubricant can make the surface smooth. For example, the gas generant molded product may have a core containing a fuel component and an oxidizer component, and a coating layer covering the surface of the core.

[0022] (Lubricant) Examples of lubricants include graphite, magnesium stearate, zinc stearate, calcium stearate, sodium stearate, boron nitride, highly dispersed silica, and talc. Among these, graphite is preferred because it has low friction and excellent sliding properties, and its antistatic effect makes it less likely to cause filling inhibition due to electrostatic repulsion. When a lubricant is applied to the gas generant molded product of the present invention, the content of the lubricant in the total amount of the gas generant molded product of the present invention is preferably 0.05 to 1.0 wt %, more preferably 0.1 to 1.0 wt %, and even more preferably 0.2 to 0.5 wt %.

[0023] [Physical Treatment] Another preferred embodiment of the gas generant molded product of the present invention is one whose surface has been smoothed by physical treatment. For example, the gas generant molded product may be one that comprises a core containing a fuel component and an oxidizer component, and whose surface has been smoothed by physical treatment. The physical treatment will be described later.

[0024] Furthermore, the surface coating and the physical treatment may be used in combination. For example, a molded product containing a fuel component and an oxidizer component and a lubricant may be added to a device that performs the physical treatment, and the lubricant may be coated while the physical treatment is being performed.

[0025] From the viewpoint of improving filling properties and chemical stability, the gas generating agent molded product of the present invention is preferably coated with a lubricant, and more preferably coated with graphite.

[0026] The gas generant molded product of the present invention can have an improved bulk density by having a specific surface roughness Ra. The bulk density of the gas generant molded product of the present invention can be, for example, 1.05 or more, such as 1.05 to 1.20, 1.07 to 1.15, or 1.08 to 1.13.

[0027] The composition of the gas generating agent molded product of the present invention is not particularly limited, but it is preferable that the molded product contains a fuel component and an oxidizer component, since this reduces the amount of CO in the exhaust gas and provides excellent heat resistance.

[0028] [Fuel Component] The fuel component (hereinafter sometimes referred to as "component (A)") is not particularly limited as long as it is a combustible organic compound, but 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 fuel component of the gas generant molded product of the present invention.

[0029] (Carbon-Based Organic Compounds) When a carbon-based organic compound with a high carbon content is used as a fuel component, a compound with a high oxygen content in the fuel component molecule is preferred in order to promote combustion and suppress the production of toxic carbon monoxide. Specific carbon-based organic compounds include pentaerythritol, glucose, sorbose, ascorbic acid or a salt thereof, citric acid or a salt thereof, lactose, sorbitose, gluconic acid or a salt thereof, glucuronic acid or a salt thereof, fructose, erythritol, xylitol, deltaic acid or a salt thereof, squaric acid or a salt thereof, croconic acid or a salt thereof, rhodizonic acid or a salt thereof, cyclohexanehexanone, 1,2,3,4,5-cyclohexanepentol, xylitol, adonitol, etc.

[0030] These carbon-based organic compounds may be used alone, but for the purpose of adjusting performance, it is also preferred to use a mixture of two or more selected from the above group. It is also preferred to use a mixture with a nitrogen-containing organic compound described below.

[0031] (Nitrogen-containing organic compound) The nitrogen-containing organic compound used as a fuel component is preferably one that has the physical property of being thermally decomposed 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.

[0032] 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 oxalic acid 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 alkali metal, alkaline earth metal or transition metal salts thereof.

[0033] Although these nitrogen-containing organic compounds may be used alone, it is also preferred to use a mixture of two or more selected from the above group for the purpose of adjusting performance, and it is also preferred to use a mixture with the above carbon-based organic compound.

[0034] Among these, component (A) preferably contains a nitrogen-containing organic compound, and is preferably one or more selected from guanidine nitrate, aminoguanidine nitrate, diaminoguanidine nitrate, triaminoguanidine nitrate, nitroguanidine, and aminonitroguanidine, with guanidine nitrate being particularly preferred.

[0035] The content of component (A) in the total amount of the gas generating agent molded product is preferably 40.0 to 58.0% by weight, more preferably 41.0 to 55.0% by weight, and even more preferably 42.0 to 50.0% by weight, in order to optimize combustion efficiency.

[0036] [Oxidizing Agent Component] The oxidizing agent component (hereinafter sometimes referred to as "component (B)") supplies oxygen necessary for combustion to the combustible organic compound component. As the oxidizing agent, it is preferable to use one or more selected from the group consisting of nitrates, basic metal nitrates, perchlorates, and chlorates.

[0037] (Nitrate) Examples of the nitrate include ammonium nitrate, phase-stabilized ammonium nitrate, and nitrates of alkali metals or alkaline earth metals. Examples of the nitrate of alkali metals or alkaline earth metals include sodium nitrate, potassium nitrate, strontium nitrate, magnesium nitrate, calcium nitrate, barium nitrate, etc. These nitrates may be used alone or in combination of two or more.

[0038] The method of phase stabilization for the phase-stabilized ammonium nitrate that can be used in this embodiment is not particularly limited. 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, oxidation ability, and the like, phase-stabilized ammonium nitrate stabilized with potassium perchlorate or potassium nitrate is particularly preferred.

[0039] (Basic Metal Nitrate) Examples of basic metal nitrates include basic copper nitrate, basic cobalt nitrate, basic zinc nitrate, basic magnesium nitrate, and basic iron nitrate. These basic metal nitrates may be used alone or in combination of two or more.

[0040] (Perchlorate / chlorate) As perchlorate / chlorate, ammonium salt, alkali metal salt, alkaline earth metal salt thereof can be enumerated.Specific perchlorate / chlorate can be exemplified as 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, barium chlorate etc.These perchlorate / chlorate can be used alone or in combination of two or more.

[0041] The above oxidizing agents may be used singly, but for the purpose of adjusting performance, it is also preferred to use a mixed oxidizing agent in which two or more oxidizing agents selected from the above group are mixed.

[0042] Among these, component (B) is preferably one or more selected from potassium perchlorate and basic copper nitrate, and more preferably potassium perchlorate and basic copper nitrate.

[0043] The content of component (B) in the total amount of the gas generating agent molded product is preferably 38.0 to 58.0% by weight, more preferably 39.0 to 55.0% by weight, and even more preferably 40.0 to 50.0% by weight, in order to optimize combustion efficiency.

[0044] In particular, it is preferable that component (B) contains potassium perchlorate and basic copper nitrate, and that the content of basic copper nitrate in the total amount of the gas generant molded product of the present invention is 0.5 to 4.0 wt %. In particular, the content of basic copper nitrate in the total amount of the gas generant molded product of the present invention is preferably 0.5 wt % or more but less than 3.0 wt %, more preferably 0.5 to 2.5 wt %, even more preferably 0.5 to 2.0 wt %, and even more preferably 0.8 to 2.0 wt %. Because basic copper nitrate has a lower melting point than, for example, potassium perchlorate, the inclusion of basic copper nitrate is thought to lower the temperature at which it reacts with the fuel, allowing for faster combustion initiation and improved ignition properties. Furthermore, it is thought that the copper contained in the basic copper nitrate acts as a spark, igniting the next gas generant. Furthermore, the inventors of the present invention have found that by setting the content of basic copper nitrate within the above-mentioned numerical range, the maximum pressure (Pmax) of the combustion curve can be improved and the combustion rate (the slope of the combustion curve) can be made gentler. Therefore, even when the filling amount is increased, the combustion rate does not become too fast, making it easier to design. For example, assuming use as a seatbelt pretensioner (particularly for a retractor), a combustion curve of the gas generant molded product with a higher maximum pressure is preferable because the seatbelt retraction performance improves. On the other hand, if the combustion rate is too fast, there is a risk that the seatbelt will not be able to be retracted. A gas generant molded product containing basic copper nitrate within the above-mentioned numerical range can increase the maximum pressure while adjusting the combustion rate to an appropriate level, making it suitable for use as a seatbelt pretensioner (particularly for a retractor).

[0045] [Other Additives] The gas generating agent molded product of the present invention may further contain an additive (hereinafter, may be referred to as "component (C)"). As the additive, a general additive that can be used in gas generating agents for gas generators can be used. For example, additives such as a binder for imparting moldability and shape retention ability, a slag former for enabling easy filtration of combustion residues, a combustion adjuster, etc. can be used. These can be used as additives either alone or in combination of two or more types.

[0046] (Binder) As the binder that can be used in the gas generating agent molded product of the present invention, binders that can generally be used as additives for gas generating agents for gas generators can be used, and the binder to be used should be considered depending on the molding method for the gas generating agent, specifically, whether a tablet molding method or an extrusion molding method is adopted.

[0047] 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.

[0048] The content of the binder in the gas generating agent molded product of the present invention is preferably 0.0 to 10.0% by weight, more preferably 1.0 to 10.0% by weight, even more preferably 2.0 to 8.0% by weight, and even more preferably 3.0 to 7.0% by weight.

[0049] (Slag-forming agent) The slag-forming agent that can be used in the gas generating agent molded product of the present invention can be any slag-forming agent that can generally be used as an additive in gas generating agents for gas generators, and is an additive that makes it possible to easily filter the combustion residue produced after combustion of the gas generating agent. Specific examples of slag-forming agents include silicon nitride, silicon carbide, silicon dioxide, aluminum oxide, titanium oxide, silicates, acid clay, clay, etc.

[0050] When the gas generant molded product of the present invention contains a slag-forming agent, the content of the slag-forming agent in the gas generant molded product of the present invention is preferably 0.0 to 10.0% by weight, more preferably 1.0 to 10.0% by weight, and even more preferably 2.0 to 5.0% by weight.

[0051] (Combustion Modifier) ​​A combustion modifier can be used in the gas generating agent molded product of the present invention. The combustion modifier is an additive for modulating the combustion of the gas generating agent. Usable combustion modifiers may be any that can modulate the combustion of the gas generating agent, 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.

[0052] When the gas generant molding of the present invention contains a combustion modifier, the content of the combustion modifier in the gas generant molding of the present invention is preferably 0.0 to 20.0% by weight, more preferably 0.5 to 20.0% by weight, and even more preferably 1.0 to 10.0% by weight.

[0053] In the gas generant molded product of the present invention, the total content of the fuel component and the oxidizer component is usually 80.0% by weight or more, preferably 90.0% by weight or more, more preferably 90.0 to 99.0% by weight, even more preferably 92.0 to 98.0% by weight, and even more preferably 93.0 to 97.0% by weight.

[0054] In the gas generant molded product of the present invention, the weight ratio (A:B) of component (A) to component (B) is preferably 70:30 to 45:55, more preferably 60:40 to 45:55, even more preferably 58:42 to 46:54, and even more preferably 55:45 to 47:53.

[0055] When component (C) is used in the gas generant molded product of the present invention, the weight ratio of the content of component (C) (component (C) / total amount of gas generant molded product) is preferably 1.0 to 10.0 wt %, more preferably 3.0 to 7.0 wt %, and particularly preferably 4.0 to 6.0 wt %.

[0056] In one embodiment, the gas generant molded product of the present invention has a surface roughness Ra of 0.40 μm or less, preferably 0.15 to 0.38 μm, more preferably 0.18 to 0.36 μm, and even more preferably 0.20 to 0.35 μm; the gas generant molded product comprises a fuel component, an oxidizer component, and a binder; the total content of the fuel component and the oxidizer component is 90.0 to 99.0 wt %, and preferably 93.0 to 97.0 wt %; the weight ratio of the fuel component:the oxidizer component is 60:40 to 45:55, preferably 58:42 to 46:54, more preferably 55:45 to 47:53, and even more preferably 53:47 to 48:52; the fuel component is a nitrogen-containing organic compound; the oxidizer component includes basic copper nitrate, and preferably includes potassium perchlorate and basic copper nitrate; The gas generant molded product may have a basic copper nitrate content of 0.5 to 4.0 wt %, preferably 0.5 wt % or more and less than 3.0 wt %, more preferably 0.5 to 2.5 wt %, and even more preferably 0.5 to 2.0 wt %; a binder content of 1.0 to 10.0 wt %, preferably 3.0 to 7.0 wt %; and a surface coating of preferably a lubricant, more preferably graphite. Such a gas generant molded product is preferable because it has excellent packing properties and can increase the Pmax (maximum pressure) of the combustion curve. Furthermore, the combustion rate can be easily adjusted by adjusting the packing amount; for example, by increasing the packing amount, the slope of the combustion curve can be made closer to that of smokeless powder, making it possible to use it as a substitute for smokeless powder and facilitating the design of gas generators.

[0057] The gas generating agent molded product of the present invention can be molded into various shapes according to the combustion performance and combustion characteristics of the gas generator. The shape of the gas generating agent molded product is not particularly limited, and examples thereof include pellet-shaped, disk-shaped, spherical, rod-shaped, columnar, cylindrical, confetti-shaped, and tetrapod-shaped products. The molded product may be non-porous or may have holes such as a single hole or multiple holes (for example, a single-hole cylindrical shape or a multi-hole cylindrical shape). Furthermore, pellet-shaped and disk-shaped molded products may be provided with one or more protrusions on one or both sides. The shape of the protrusions is not particularly limited, and examples thereof include a columnar shape, a cylindrical shape, a conical shape, and a polygonal pyramid shape.

[0058] For example, the shape of the gas generating agent molded product of the present invention may be a columnar shape having a diameter of 0.3 to 3.0 mm and a length (height) of 0.1 to 4.0 mm.

[0059] <Method for producing gas generant molded products of the present invention> The method for producing gas generant molded products of the present invention is not particularly limited, but the gas generant molded products of the present invention can be obtained, for example, by a production method comprising the following steps (A) and (B1) and / or (B2): Step (A): Mixing a fuel component and an oxidizer component to obtain a mixture Step (B1): Molding the mixture and coating the surface of the molded product with a lubricant Step (B2): Molding the mixture and smoothing the surface of the molded product by physical treatment

[0060] Step (A) may involve mixing at least a fuel component and an oxidizer component, and may involve mixing other additives in addition to the fuel component and the oxidizer component. The types and proportions of the fuel component, oxidizer component, and other additives are as described above, and preferred embodiments are also the same. For example, step (A) may involve mixing the fuel component, oxidizer component, and other additives, and then adding water or an organic solvent to obtain a kneaded mixture.

[0061] The molding in steps (B1) and (B2) can be carried out by a conventional method, such as extrusion molding or tablet molding.

[0062] The coating method in step (B1) is not particularly limited, but examples thereof include a method of kneading the molded mixture with a lubricant using a mixer or the like, a method of dissolving the lubricant in a solvent as needed, and then spray coating or dipping, etc. When a solvent is used, the solvent is volatilized using a dryer or the like.

[0063] The surface roughness Ra is preferably reduced by 30% or more, more preferably 50% or more, by coating with a lubricant compared to before coating. The surface roughness Rz is preferably reduced by 30% or more, more preferably 50% or more, by coating with a lubricant compared to before coating. Furthermore, the bulk density is preferably increased by 5% or more, more preferably 10% or more, by coating with a lubricant.

[0064] Whether the surface of the gas generating agent molded article is coated with a lubricant can be confirmed by surface analysis, appearance observation, color analysis, surface roughness measurement, bulk density measurement, etc. of the gas generating agent molded article.

[0065] The physical treatment in step (B2) is not particularly limited as long as it can smooth the surface of the molded product, and examples thereof include ball mill treatment, mixer treatment, and blast treatment. The production of gas generant molded products usually includes a step called mixing, in which burrs are removed and performance is made uniform by physical treatment. The physical treatment in step (B2) may be performed by performing this mixing treatment for a longer time than usual.

[0066] When only step (B2) is performed without step (B1), the physical treatment is performed to reduce the surface roughness Ra of the molded product to 0.40 μm or less. In this case, the physical treatment of step (B2) preferably reduces the surface roughness Ra of the molded product to 0.15 to 0.38 μm, more preferably 0.18 to 0.36 μm, and even more preferably 0.20 to 0.35 μm.

[0067] When step (B2) alone is performed without step (B1), the physical treatment time is preferably 0.25 to 24 hours, more preferably 0.25 to 6 hours, and even more preferably 0.25 to 2 hours to obtain a smoother surface. The lower limit may be extended, such as 0.5 to 24 hours, 0.65 to 6 hours, or 0.75 to 2 hours. The treatment time and other conditions are appropriately determined within a range that allows the surface roughness Ra of the molded product to be 0.40 μm or less. The physical treatment time is not limited to the above time, depending on the type and size of the equipment used.

[0068] In addition, either step (B1) or step (B2) may be performed, or both may be performed. When step (B1) and step (B2) are used in combination, step (B2) may be performed after step (B1), step (B2) may be performed after step (B1), or step (B1) and step (B2) may be performed simultaneously.

[0069] An example of a manufacturing method having steps (B1) and (B2) is a method in which a molded mixture and a lubricant are added to a mixing device and mixed. When mixing is performed while coating with a lubricant, the lubricant can smooth the surface of the molded product, so the mixing time can be short, for example, 0.05 to 1 hour. Alternatively, after mixing for a certain period of time, a lubricant can be added and further mixed while coating with the lubricant.

[0070] <Gas Generator> The gas generator of the present invention uses the gas generating agent molded product of the present invention described above. The gas generator of the present invention 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 seatbelt pretensioners.

[0071] The gas generator of the present invention can have the same configuration as a conventionally known gas generator, except for the gas generating agent molded product of the present invention, and is not particularly limited to a specific configuration, and any inflator having a structure that is normally mounted on a vehicle can be employed without any particular limitation. A typical gas generator is configured by providing an ignition device and, if necessary, a filter material inside an outer shell having an internal volume, and also filling it with a gas generating agent molded product.

[0072] The gas generator of the present invention may be either a pyrotype in which gas is supplied only from a gas generating agent, or a hybrid type in which both a compressed gas such as argon and a gas generating agent are supplied.

[0073] 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.

[0074] Example 1: 51 parts by weight of guanidine nitrate (GN), 44 parts by weight of potassium perchlorate (PP), and 5 parts by weight of hydroxypropyl methylcellulose (HPMC) were mixed in a ball mill, and then 14 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded to obtain a mixture. The mixture was then extruded into a predetermined shape by applying a predetermined pressure to an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 2.6 mm and dried to obtain a cylindrical gas generant composition. Subsequently, 0.5 parts by weight of graphite (C) was added during mixing to achieve uniform performance, and the gas generant composition was coated to obtain a molded gas generant. Mixing was performed for 5 minutes using a ball mill.

[0075] Comparative Example 1: 51 parts by weight of guanidine nitrate, 44 parts by weight of potassium perchlorate, 5 parts by weight of hydroxypropyl methylcellulose, and 5 parts by weight of graphite were mixed, and 14 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded. The mixture was then extruded into a predetermined shape by applying a predetermined pressure in an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 2.6 mm and dried to obtain a cylindrical gas generant composition. Subsequently, in order to achieve uniform performance, the mixture was mixed for 5 minutes using a ball mill to obtain a gas generant molded product.

[0076] Example 2: 47.8 parts by weight of guanidine nitrate (GN), 2.0 parts by weight of basic copper nitrate (BCN), 44.5 parts by weight of potassium perchlorate (PP), 1.1 parts by weight of polyacrylamide (PAA), and 4.5 parts by weight of hydroxypropyl methylcellulose (HPMC) were mixed, and 16 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded to obtain a mixture. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 1.5 mm and dried to obtain a cylindrical gas generant composition. Subsequently, 0.5 parts by weight of graphite (C) was added during mixing to achieve uniform performance, and the gas generant composition was coated to obtain a molded gas generant. Mixing was performed for 5 minutes using a ball mill.

[0077] Example 3: 47.8 parts by weight of guanidine nitrate, 2.0 parts by weight of basic copper nitrate, 44.5 parts by weight of potassium perchlorate, 1.1 parts by weight of polyacrylamide, and 4.5 parts by weight of hydroxypropyl methylcellulose were mixed, and 16 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded to obtain a mixture. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 1.5 mm and dried to obtain a cylindrical gas generant composition. Thereafter, in order to achieve uniform performance and a smooth surface, the mixture was mixed in a ball mill for 125 minutes to obtain a gas generant molded product.

[0078] Example 4: 47.8 parts by weight of guanidine nitrate, 2.0 parts by weight of basic copper nitrate, 44.5 parts by weight of potassium perchlorate, 1.1 parts by weight of polyacrylamide, and 4.5 parts by weight of hydroxypropyl methylcellulose were mixed, and 16 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded to obtain a mixture. The mixture was then extruded into a predetermined shape by applying a predetermined pressure in an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 1.5 mm and dried to obtain a cylindrical gas generant composition. Next, in order to achieve uniform performance and surface smoothing, the mixture was mixed in a ball mill for 125 minutes. Thereafter, 0.5 parts by weight of graphite was added, and the mixture was mixed in a ball mill for 5 minutes. The mixture was then coated onto the gas generant composition to obtain a molded gas generant.

[0079] Comparative Example 2: 47.8 parts by weight of guanidine nitrate, 2.0 parts by weight of basic copper nitrate, 44.5 parts by weight of potassium perchlorate, 1.1 parts by weight of polyacrylamide, and 4.5 parts by weight of hydroxypropyl methylcellulose were mixed, and 16 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and uniformly kneaded to obtain a mixture. Next, the mixture was extruded into a predetermined shape by applying a predetermined pressure in an extruder and passing through a die with a diameter of 1.5 mm. The extruded molded body of the gas generant composition was cut into a length of 1.5 mm and dried to obtain a cylindrical gas generant composition. Thereafter, in order to achieve uniform performance, the mixture was mixed for 5 minutes using a ball mill to obtain a gas generant molded product.

[0080] Example 5 A gas generating agent molded product of Example 5 was obtained in the same manner as in Example 3, except that the mixing time was changed from 125 minutes to 95 minutes.

[0081] Example 6 A gas generating agent molded product of Example 6 was obtained in the same manner as in Example 3, except that the mixing time was changed from 125 minutes to 65 minutes.

[0082] Example 7 A gas generating agent molded product of Example 7 was obtained in the same manner as in Example 3, except that the mixing time was changed from 125 minutes to 50 minutes.

[0083] [Observation of Appearance] A photograph of the appearance of the gas generating agent molded product obtained in Example 1 is shown in FIG.

[0084] [Surface Roughness Measurement] The surface roughness Ra and Rz of the gas generant molded articles obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were measured using a laser microscope (Keyence VK-X100). The gas generant molded articles were set on the microscope so that the major axis side (length direction) was in the X-axis direction and the minor axis side (radial direction) was in the Y-axis direction, and the surface roughness Ra and Rz were measured using the method described above. The results are shown in Table 1.

[0085] [Bulk Density Measurement Method] The bulk densities of the gas generating agent molded products obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were measured using an A.B.D. powder property measuring instrument (A.B.D. 72 model, manufactured by Tsutsui Rikagaku Co., Ltd.). The results are shown in Table 1.

[0086]

[0087] [Combustion Performance Test 1] 1000 mg of the gas generant molded products obtained in Examples 3 and 4 and Comparative Example 2 were filled into a 10 cc sealed combustion container. A cushion was placed in the bottom of the container to adjust the distance from the top of the container to the gas generant molded product so that the distance was the same. Next, the gas generant was burned, and the maximum pressure reached and the time it took to reach the maximum pressure were measured. The results are shown in Figure 2.

[0088] [Combustion Performance Test 2] A 10 cc sealed combustion container was filled with molded gas generants up to a position 8.9±0.2 mm from the top surface, and the gas generants were burned to measure the maximum pressure and the time it took to reach the maximum pressure. The amounts of molded gas generants filled were 1,455 mg for Example 2, 1,445 mg for Example 3, 1,540 mg for Example 4, and 1,290 mg for Comparative Example 2. The measured combustion curves are shown in Figure 3.

[0089] The results in Figure 2 show that the gas generant molded products of the present invention maintain their combustion performance even when the surface is coated with a lubricant. Furthermore, the results in Figure 3 show that the gas generant molded products of the present invention can be increased in charge amount, thereby increasing the maximum pressure of the combustion curve. Furthermore, the slope of the combustion curve from 0 to 3 ms in Examples 2 and 4 was comparable to the combustion curve of smokeless powder (charge amount: 1,245 mg) in a similar experiment. Thus, even when the charge amount is increased, the slope of the combustion curve of the gas generant molded products of the present invention does not become too steep, and the maximum pressure can be increased, approaching the combustion curve of smokeless powder.

[0090] Comparative Examples 3 and 4 Gas generant molded products of Comparative Examples 3 and 4 were obtained using the same composition as in Comparative Example 2, but the mixing time was adjusted so that the surface roughness Ra exceeded 0.40 μm. The surface roughness Ra, Rz, and bulk density of the obtained gas generant molded products were measured. The results are shown in Table 2.

[0091]

[0092] <Reference Example> A gas generating agent molded product was obtained in the same manner as in Comparative Example 2, except that guanidine nitrate, basic copper nitrate, potassium perchlorate, polyacrylamide, and hydroxypropyl methylcellulose were mixed in the proportions shown in Table 3, and 16 parts by weight of ion-exchanged water and 3 parts by weight of ethanol were added in a kneader and kneaded uniformly to obtain a mixture.

[0093] [Combustion Performance Test 3] 1000 mg of the gas generating agent molded product obtained in the reference example was filled into a 10 cc closed combustion container, and the gas generating agent was burned, and the maximum pressure reached and the time required to reach the maximum pressure were measured. The results are shown in Figure 4.

[0094]

[0095] As shown in Figure 4, when BCN is 2 wt%, the combustion starts faster than when BCN is 0 wt%. Also, when BCN is 5 wt% and 10 wt%, the slope of the combustion curve up to the maximum pressure is similar, whereas when BCN is 2 wt%, the slope of the combustion curve up to the maximum pressure is gentler.

Claims

1. A gas generating agent molded product having a surface roughness Ra of 0.40 μm or less.

2. The gas generating agent molded product according to claim 1, which contains a fuel component and an oxidizer component.

3. The gas generating agent molded product according to claim 2, wherein the fuel component is a nitrogen-containing organic compound, and the oxidizer component is one or more selected from the group consisting of potassium perchlorate and basic copper nitrate.

4. A gas generant molded product according to claim 3, further comprising a binder, wherein the total content of the fuel component and the oxidizer component is 90.0% by weight or more and 99.0% by weight or less, wherein the weight ratio of the fuel component to the oxidizer component is 60:40 to 45:55, wherein the oxidizer component comprises potassium perchlorate and basic copper nitrate, and the content of the basic copper nitrate is 0.5% by weight or more and 4.0% by weight or less.

5. A gas generating agent molded product according to claim 3, wherein the oxidizer component contains potassium perchlorate and basic copper nitrate, and the content of the basic copper nitrate is 0.5% by weight or more and 2.0% by weight or less.

6. The gas generating agent molded product according to claim 1, the surface of which is coated with a lubricant.

7. The gas generant molded product according to claim 6, wherein the lubricant is one or more selected from the group consisting of graphite, magnesium stearate, zinc stearate, calcium stearate, sodium stearate, boron nitride, highly dispersed silica, and talc.

8. A gas generant molded product according to claim 6, wherein the amount of said lubricant added is 0.05% by weight or more and 1.0% by weight or less of the total amount of said gas generant molded product.

9. A gas generator containing the gas generating agent molded product according to any one of claims 1 to 8.

10. A method for producing a gas generant molded product, comprising: a step (A) of mixing a fuel component and an oxidizer component to obtain a mixture; a step (B1) of molding the mixture and coating the surface of the molded product with a lubricant; and / or a step (B2) of molding the mixture and smoothing the surface of the molded product by physical treatment.

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