JP5058540B2 - Gas generant composition - Google Patents

Description

  The present invention relates to a gas generant composition that can be used in an inflator for an air bag and the like.

  Gas generators generally use a binder together with a fuel and an oxidizer, and have good moldability and flammability. Therefore, water-soluble organic binders (carboxymethylcellulose, guar gum, starch, polyvinyl alcohol, etc.), organic solvent bases Organic binders (HTPB: terminal hydroxyl group polybutadiene, GAP: glycidyl acid polymer, etc.) are used.

  However, when an organic binder is used, there is a problem that gas (carbon monoxide, nitrogen oxide, ammonia, etc.) harmful to the human body derived from carbon and nitrogen as constituent elements of the binder is generated ( Patent Document 1). Moreover, since the purifying action by the secondary chemical reaction of the generated trace gas, which should be expected, is suppressed, there is a concern about the increase of harmful gas generated.

  Even when an organic binder that does not contain nitrogen is used, not only the generation of carbon monoxide derived from carbon, but also the amount of oxygen consumed for the generation of carbon dioxide by the combustion of carbon (reaction formula I) increases. When considering the reaction in the generated gas including the combustion of fuel, the purification action (reaction formula II) due to the reaction of nitric oxide, ammonia and oxygen is suppressed, and the generation of nitric oxide is also considered to increase. It is done.

CH _X + (1+ (x / 4)) O ₂ → CO ₂ + (x / 2) H ₂ O (I)
2NO + 2NH ₃ + (1/2) O ₂ → 2N ₂ + 3H ₂ O (II)
If it is an inorganic binder, there is no problem due to the use of the organic binder as described above, but compared to the case where an organic binder is used, it has been widely used in the production of conventional gas generant compositions. There is a problem that the extrusion moldability is inferior in the production by the present drawing method (Patent Documents 2 to 5).
USP 5,608,183 USP 6,143,102 JP-A-5-879 WO97 / 005087 JP 11-310490 A

  The present invention solves the problems in the case of using an organic binder as a component of the gas generating composition, and has improved the extrusion moldability while taking advantage of the inorganic binder. The issue is to provide goods.

As a means for solving the problems, the present invention
A gas generant composition containing a binder selected from a fuel, an oxidant and an inorganic sol;
The gas generant composition according to claim 1, wherein the inorganic sol is a metal oxide sol;
The gas generant composition according to claim 1 or 2, wherein the metal oxide sol is one or more selected from aluminum oxide sol, silicon oxide sol, titanium oxide sol, and antimony oxide sol;
Gas generating agent composition in any one of Claims 1-3 containing 10-70 mass% of fuel, oxidizing agent 25-85, and binder 0.1-20 mass%;
I will provide a.

  Since the gas generating composition of the present invention contains a material selected from inorganic sols as a binder, the problem of generating gas harmful to the human body as in the case of using an organic binder is solved. The problem of poor extrudability when using an inorganic binder is also eliminated.

  Examples of the fuel used in the present invention include those used in known gas generating agents, and among these, nitrogen-containing organic compounds are preferable. Examples of the nitrogen-containing organic compound include one or more selected from guanidine nitrate, nitroguanidine, 5-aminotetrazole, ammonium nitrate, and melamine.

  Examples of the oxidizing agent used in the present invention include those used in known gas generating agents. Among them, basic copper nitrate, basic copper carbonate, potassium nitrate, sodium nitrate, strontium nitrate, peroxynitrate, The 1 type (s) or 2 or more types chosen from potassium chlorate, sodium perchlorate, and ammonium perchlorate can be mentioned.

The binder used in the present invention is an inorganic sol, and water may be used as a dispersion medium, or an organic solvent may be used as a dispersion medium. The inorganic sol is preferably a metal oxide sol, and examples of the metal oxide sol include one or more selected from aluminum oxide sol, silicon oxide sol, titanium oxide sol, and antimony oxide sol. .

  In the present invention, it is desirable not to include an organic binder as a binder, but a small amount of an organic binder is included for reasons such as the relationship with an inflator using a gas generant composition and higher extrudability. You can also. In this case, the organic binder can be contained in a proportion of 5% by mass or less in the total amount of the solid content of the inorganic sol and the organic binder.

  As organic binders, carboxymethylcellulose, carboxymethylcellulose sodium salt, carboxymethylcellulose potassium salt, carboxymethylcellulose ammonium salt, cellulose acetate, cellulose acetate butyrate, methylcellulose, ethylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, carboxymethylethylcellulose , Microcrystalline cellulose, polyacrylamide, aminated product of polyacrylamide, polyacryl hydrazide, acrylamide / metal acrylate copolymer, copolymer of polyacrylamide / polyacrylate compound, polyvinyl alcohol, acrylic rubber, guar gum, What is selected from starch and silicone It can gel.

  In the gas generant composition of the present invention, the content ratios of the fuel, the oxidant and the binder are as follows. The inorganic sol (metal oxide sol) serving as the binder is a ratio based on the mass of the solid content excluding the dispersion medium.

  The fuel is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and still more preferably 30 to 50% by mass.

  The oxide is preferably 25 to 85% by mass, more preferably 35 to 70% by mass, and still more preferably 40 to 60% by mass.

  0.1-25 mass% of a binder is preferable, More preferably, it is 1-20 mass%, More preferably, it is 3-15 mass%.

  The gas generant composition of the present invention can contain various additives contained in known gas generants as long as the problems of the present invention are not impaired in addition to the fuel, the oxidant, and the binder. Examples of the additive include copper oxide, iron oxide, zinc oxide, cobalt oxide, manganese oxide, molybdenum oxide, nickel oxide, bismuth oxide, silica, alumina, and other metal oxides; cobalt carbonate, calcium carbonate, basic zinc carbonate, Metal carbonates such as basic copper carbonate or basic metal carbonates; complex compounds of metal oxides or hydroxides such as acid clay, kaolin, talc, bentonite, diatomaceous earth, hydrotalcite; aluminum hydroxide, hydroxide Magnesium; metal salts such as sodium silicate, mica molybdate, cobalt molybdate, and ammonium molybdate, one or more selected from molybdenum disulfide, calcium stearate, silicon nitride, and silicon carbide. .

  Although content of an additive is suitably selected according to the kind of additive, about 0.1-20 mass parts is preferable with respect to 100 mass parts of total amounts of a fuel, an oxidizing agent, and a binder.

  As a method for producing the gas generant composition of the present invention, a fuel, an oxidant, a binder and, if necessary, an additive are mixed with a kneader to obtain a mixture, and then extruded with a drawing machine. Can be applied. The gas generating composition of the present invention uses an inorganic sol having water or an organic solvent as a dispersion medium. Therefore, when mixing with a kneader, water or an organic solvent is added as necessary. That's fine.

  In the mixing step of the production method of the present invention, when a fuel, an oxidant, a binder, one kind or two or more kinds of additives are used as components of the gas generant composition, It is also possible to apply a two-stage mixing method in which a primary mixture is obtained by mixing parts of the components and the binder, and then the remaining components are added and mixed to obtain the final mixture.

  The gas generant composition of the present invention can be molded into a desired shape, and can be formed into a single-hole cylindrical, porous cylindrical, or pellet-shaped molded body. The single-hole columnar shape and the porous columnar shape may be either those in which the hole penetrates in the length direction or those in which the hole does not penetrate and forms a recess.

  The gas generating composition of the present invention includes, for example, an inflator for an airbag of a driver seat of various vehicles, an inflator for an airbag of a passenger seat, an inflator for a side airbag, an inflator for an inflator pull curtain, an inflator for a knee bolster, an inflator pull It can be applied to seat belt inflators, tubular system inflators, and pretensioner gas generators.

  The inflator using the gas generant composition of the present invention is a hybrid type in which the gas supply is a pyro type only from the gas generant composition and a compressed gas such as argon and the gas generant composition. Either of these may be used.

  Furthermore, the gas generant composition of the present invention can also be used as an ignition agent called an enhancer agent (or booster) for transmitting the energy of the detonator or squib to the gas generant composition.

Examples and Comparative Examples Each component of Examples and Comparative Examples shown in Table 1 and water of 16% by weight of the outer split were mixed using a kneader. Next, the obtained mixture (bulky gas generant composition) was extruded using a drawing machine at a pressure of 80 kg / cm ² , and what was successfully extruded was further cut and dried. A gas generant composition having an outer diameter of 6.5 mm and a length of 10 mm (pellet shape without an inner diameter hole) was obtained.

(1) Evaluation of extrusion moldability The state of the extruded gas generant composition formed by the above method was visually observed and judged according to the following evaluation criteria.
○: The gas generator composition molded body has sufficient strength and can be stably extruded (a level at which the extruded body can be stably extruded without cutting the extruded body over a length of 1 m or more in the above extrusion molding) )
X: The level of the gas generant composition molded body is insufficient and stable extrusion molding is impossible (the above-mentioned extrusion molding cuts the extruded molded body with a length of less than 1 m, and stable extrusion molding. Level that can not be)
(2) Preparation of gas concentration measurement test strand The gas generant compositions of Examples and Comparative Examples obtained in the above (1) were dried at 110 ° C. for 16 hours. Thereafter, the mixture was pulverized and passed through a SUS sieve twice through a 300 μm mesh to make the particle diameters uniform. 2.00 g of the mixture having the adjusted particle size is filled in the die side of a predetermined mold, and after being compressed and held at a pressure of 14.7 MPa by a hydraulic pump for 5 seconds from the heel side end surface, it is taken out and an outer diameter of 9.55 mm is obtained. A cylindrical strand was molded as a test sample. In addition, the gas concentration measurement is not implemented about the thing of x evaluation by evaluation of extrusion moldability.

(3) Measurement of gas concentration The cylindrical strand of the test sample was placed in an SUS sealed bomb having an internal volume of 1 L, and the pressure was stabilized to 7 MPa while the inside of the bomb was completely replaced with nitrogen. Thereafter, a predetermined current was passed through the nichrome wire brought into contact with the end face of the strand, and the energy was ignited and burned. After waiting 60 seconds and the gas in the bomb becomes uniform, the opening part of the tedlar bag with a predetermined stopper is connected to the bomb gas discharge part, and sampling is performed by introducing the combustion gas in the bomb. ) made of a gas detecting tube (NO ₂ and NO detection: No.1, NH ₃ detection: No.3L, CO detection: by _Nanba1L), was measured _{NO 2, NO, NH 3,} CO concentration . The results are shown in Table 1. About the gas concentration of Example 1, it was set as the relative display when the gas concentration of the comparative example 1 was set to 100%. The results are shown in Table 1.

* Content of each component is expressed in mass% * The raw material composition ratios of Example 1 and Comparative Examples 1 and 2 were determined so that the oxygen balance of the gas generant composition was almost the same value (the oxygen balance here) Is the excess or deficiency of oxygen necessary to fully oxidize the gas generant composition).

  As is apparent from Table 1, the extrusion moldability of Example 1 using an aluminum oxide sol binder is equivalent to that of Comparative Example 1 using an organic binder, and compared with Comparative Example 2 to which an aluminum oxide powder was added. If found, it was clearly superior. That is, even when the metal oxide sol of the present invention is used as a binder, it may be possible to produce a gas generant composition by an extrusion molding method as in the case of using a conventional organic binder. I understood.

  As compared with Comparative Example 2, the NO and CO gas concentrations of Example 1 were significantly suppressed. That is, it has been found that the gas generating agent composition is effective in suppressing the generation of gas harmful to the human body during combustion.

Claims (2)

Contains a binder selected from fuels, oxidants and inorganic sols ,
A gas generating composition in which the binder selected from the inorganic sols is an aluminum oxide sol, and the binder content is 1 to 20% by weight . 10 to 70 wt% fuel, oxidant 25 to 85 wt%, the gas generating composition according to claim 1 containing 20 1 to 20 wt% binder.