JP4969837B2 - Extruded product of gas generating agent for automobile airbag inflators - Google Patents

Description

  The present invention relates to a gas generant molded article made of a gas generant composition suitable for an air bag restraint system such as an automobile.

  As a gas generating agent for an air bag as an occupant protection device in an automobile, a safer so-called non-azide gas generating agent has been developed in place of toxic sodium azide.

  The gas generant is often used as a molded body, and it is generally known that the relationship of the following formula is established for the gas generant molded body.

v = L / t (I) [v: average burning rate of the gas generant molded product (mm / sec), L: maximum thickness (mm) of the gas generant molded product, t: L is the maximum thickness. (Combustion completion time of gas generant compact)
In general, a gas generant molded body used for a gas generator for an air bag is required to complete combustion in 30 to 100 milliseconds. As a guideline for obtaining such a combustion time (t). The following formula derived from the above formula (I): t = L / v (II) is adopted. In order to make t a numerical value within a predetermined range, it is conceivable to increase v in the above expression or decrease L.

  Patent Document 1 discloses that aluminum oxide is added to a gas generant composition composed of guanidine nitrate and basic copper nitrate in order to improve the combustion rate (v). However, when aluminum oxide is added, mist generated after combustion [refers to a solid component (for example, a metal component) in the gas generating agent generated by the combustion of the gas generating agent]. ], The amount of use of the filter needs to be increased, and the cost of the gas generator increases.

  Patent Document 2 discloses a gas generant molded product (tablet) that is compression-molded without using a binder. However, in the compression molding method in which a gas generating agent is charged into a mortar-shaped device and molded with a bowl-shaped molding tool, if the thickness (L) of the molded body is reduced, the metal bowl and mortar come into contact during molding. Since the gas generating agent may ignite and burn, the thickness (L) cannot be made too small.

In Patent Document 3, since a relatively large amount of perchlorate is used, the amount of mist generated increases, and there is a problem similar to that of Patent Document 1. In Patent Documents 4 and 5, copper oxide is an optional component.
USP 6143102 EP1006096B DE201111410 JP 2004-155645 A JP-A-2005-119926

  In the present invention, by adjusting the combustion speed and the maximum thickness in a well-balanced manner, the combustion completion time obtained from the formula (II) can be adjusted to a desired range, mist can be easily caught, and an inexpensive gas generant molding is performed. The challenge is to provide a body.

  The present invention provides, as means for solving the problems, a gas generant molded article comprising the following gas generant composition and obtained by extrusion molding.

(A) Nitrogen-containing fuel 25-45 mass%
(B) Copper oxide 30-70 mass%
(C) Perchlorate 0-15% by mass
(D) Binder 1-10% by mass

  When the gas generating agent molded body of the present invention is used in an air bag gas generator, the combustion completion time can be easily adjusted, the generated mist can be easily caught, the exhaust gas is clean and inexpensive.

<Gas generating composition>
[(A) component]
As the nitrogen-containing fuel of component (a), it is preferable to use one kind selected from tetrazole compounds, guanidine compounds, triazine compounds and nitroamine compounds, or a combination of two or more kinds.

  The tetrazole compounds include tetrazole, 5-aminotetrazole, 5,5′-bi-1H-tetrazole, 5-nitroaminotetrazole, zinc salt of 5-aminotetrazole, copper salt of 5-aminotetrazole, bitetrazole, Examples include tetrazole potassium salt, bitetrazole sodium salt, bitetrazole magnesium salt, bitetrazole calcium salt, bitetrazole diammonium salt, bitetrazole copper salt and bitetrazole melamine salt.

  Examples of guanidine compounds include guanidine, mono-, di- or triaminoguanidine nitrate, guanidine nitrate, guanidine carbonate, nitroguanidine, dicyandiamide, and nitroaminoguanidine nitrate.

  Examples of triazine compounds include melamine, cyanuric acid, ammelin, ammelide, and ammeland. Examples of nitroamine compounds include cyclo-1,3,5-trimethylene-2,4,6-trinitramine. it can.

  The content ratio of the nitrogen-containing fuel as the component (a) in the gas generant composition is 25 to 45% by mass, preferably 28 to 42% by mass, and more preferably 30 to 40% by mass.

[Component (b)]
The content ratio of the component (b) copper oxide in the gas generant composition is 30 to 70% by mass, preferably 35 to 67% by mass, and more preferably 40 to 62% by mass.

[Component (c)]
(C) Component perchlorate is a component to be blended as necessary, and one type selected from ammonium perchlorate, potassium perchlorate, and sodium perchlorate is used, or two or more types are used. It is preferable to use in combination.

  The content ratio of the perchlorate of component (c) in the gas generant composition is 0 to 15% by mass, preferably 0.5 to 10% by mass, and more preferably 1 to 7% by mass.

[Component (d)]
The binder of component (d) is carboxymethyl cellulose, carboxymethyl cellulose sodium salt, carboxymethyl cellulose potassium salt, carboxymethyl cellulose ammonium salt, cellulose acetate, cellulose acetate butyrate, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl cellulose, carboxy Methyl ethyl cellulose, microcrystalline cellulose, polyacrylamide, polyacrylamide amination, polyacryl hydrazide, acrylamide / metal acrylate copolymer, polyacrylamide / polyacrylate copolymer, polyvinyl alcohol, acrylic rubber, Use one selected from guar gum, starch, and silicone Luke, or it is preferable to use a combination of two or more.

  The content ratio of the binder of component (d) in the gas generant composition is 1 to 15% by mass, preferably 2 to 10% by mass, and more preferably 2.5 to 7.5% by mass.

  The gas generating agent composition used in the present invention can be blended with known oxidizing agents other than the above-described components (b) and (c) as long as the problems of the present invention can be solved. The content of the other oxidizing agent in the composition is preferably less than 30% by mass, and more preferably 20% by mass or less.

  The gas generant composition used in the present invention can contain known additives blended in the gas generant for various purposes.

  Examples of the additive include iron oxide, zinc oxide, cobalt oxide, manganese oxide, molybdenum oxide, nickel oxide, bismuth oxide, silica, metal oxide containing alumina, cobalt hydroxide, metal hydroxide containing iron hydroxide; Metal carbonate or basic metal carbonate containing cobalt, calcium carbonate, basic zinc carbonate, basic copper carbonate; metal oxide or hydroxide containing acid clay, kaolin, talc, bentonite, diatomaceous earth, hydrotalcite Compound salts of: metal silicates such as sodium silicate, mica molybdate, cobalt molybdate, ammonium molybdate; silicone, molybdenum disulfide, calcium stearate, silicon nitride, silicon carbide and the like.

<Method for producing gas generant molded article>
The gas generant molded product of the present invention can be obtained by extrusion molding using the gas generant composition described above.

  The gas generant shaped product of the present invention can be formed into a desired shape such as a columnar shape, a single-hole columnar shape, a porous columnar shape, or a disk shape (tablet shape). In the case of a single-hole columnar shape or a porous columnar shape, the hole may be a through-hole or a non-through-hole (dent).

  In the gas generant molded article of the present invention, the burning rate (v) at a pressure of 6.86 MPa is preferably 5 to 15 mm / sec, more preferably 6 to 14 mm / sec, and still more preferably 7 to 14 mm / sec. A burning rate is calculated | required by the method as described in an Example.

  In the gas generating agent molded body of the present invention, the maximum thickness (L) is preferably from 0.5 to 3 mm, more preferably from 0.6 to 2.5 mm, still more preferably from 0.7 to 2 in the above-mentioned combustion rate range. .3 mm.

  The maximum thickness (L) is a diameter in the case of a columnar shape (no holes), and in the case of a single-hole columnar shape, the maximum thickness (L) is obtained by the following formula: (diameter-hole diameter) / 2. In the case of a cylindrical shape, it is the maximum thickness portion of the thickness between the outer surface and the hole or the thickness between two adjacent holes.

  The gas generant molded product of the present invention is obtained by extrusion molding using the gas generant composition described above, so that the combustion rate (v) and the maximum thickness (L) can be easily adjusted in association with each other. The combustion completion time (t) obtained from the formula (II): t = L / v can be adjusted to a desired time range.

Examples and Comparative Examples A total of 5000 g of each component of the example compositions shown in Table 1 and 1250 g of water were charged into a mixer and mixed. This mixture is extruded with an extruder, cut, and dried to obtain various gas generant molded bodies having an outer diameter of 2.0 to 4.5 mm, an inner diameter of 0.5 to 1.3 mm, and a length of 1.8 to 5 mm. It was.

  About the obtained gas generating agent molded object, the combustion rate, the combustion temperature, the gas generation efficiency, the friction drop sensitivity, and the density of the gas generating agent molded object were calculated | required.

(1) Burning speed and strand density Powder of the composition of the example (mixed powder for molding) is filled on the mortar side of a predetermined mold, and 5 seconds at a pressure of 14.7 MPa with a hydraulic pump from the end face of the flange side. After being compressed and held, it was taken out and formed into a cylindrical strand having an outer diameter of 9.6 mm and a length of 12.70 mm. The molded body was dried at 110 ° C. for 16 hours, and then the strand density was calculated from the strand weight, strand diameter, and height. Furthermore, after applying “bond quick 30” manufactured by Konishi Co., Ltd., an epoxy resin chemical reaction adhesive on the side surface and one end surface of this cylindrical molded body, it is cured at room temperature for 2 hours or more and used as a sample.

  A cylindrical strand as a sample was placed in a SUS sealed bomb having an internal volume of 1 L, and pressure was stabilized to 6.86 MPa while the bomb was completely purged 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. The time-dependent pressure behavior in the bomb is confirmed on the chart of the recorder, the elapsed time from the start of combustion to the pressure rise peak is confirmed from the scale on the chart, and the strand length before combustion is divided by this elapsed time. The calculated value was taken as the burning rate.

(2) Combustion temperature and gas generation efficiency Calculated by theoretical calculation.

(3) Gas concentration measurement method Cylindrical strand (mass: 2.00 g) as a sample is placed in a 1 L SUS sealed bomb and pressurized to 7 MPa while the bomb is completely purged with nitrogen. Stabilized. Thereafter, a predetermined current was passed through the nichrome wire brought into contact with the end face of the strand, and the ignition energy was burned and burned by the fusing energy. After waiting for 60 seconds and the gas in the bomb becomes uniform, sampling is performed by connecting the opening part of the tedlar bag with a predetermined stopper to the bomb gas discharge part and introducing the combustion gas in the bomb. ) made of a gas detecting tube (NO ₂ and NO detection: No.10, NH ₃ detection: No.3L, CO detection: by _Nanba1L), was NO 2, NO, CO, and NH ₃ concentration was measured .

NQ: nitroguanidine, SrN: strontium nitrate, BCN: basic copper nitrate, GN: guanidine nitrate, CuO: copper oxide, CMCNa: carboxymethyl cellulose sodium salt, KClO _4: Potassium perchlorate, NH ₄ ClO _4: perchlorate Ammonium From the results of Table 1, the gas generant molded body of the present invention has a lower gas generation efficiency per weight than the comparative example, but the density is high, so the generation efficiency per volume does not change so much, and the NO of exhaust gas , CO reduction effect was better than the comparative example.

Claims (5)

A gas generant molded article comprising the following gas generant composition and obtained by extrusion molding.
(A) Nitrogen-containing fuel 25-45 mass%
(B) Copper oxide 30-70 mass%
(C) 1-7 % by mass of at least one selected from ammonium perchlorate, potassium perchlorate, and sodium perchlorate
(D) Binder 1-10% by mass   The gas generant molded article according to claim 1, wherein the nitrogen-containing fuel as component (a) is at least one selected from tetrazole compounds, guanidine compounds, triazine compounds, and nitroamine compounds. The gas generant molded article according to claim 1 or 2, wherein the content of component (c) is 1 to 5 mass% .   (D) Component binder is carboxymethylcellulose, carboxymethylcellulose sodium salt, carboxymethylcellulose potassium salt, carboxymethylcellulose ammonium salt, cellulose acetate, cellulose acetate butyrate, methylcellulose, ethylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, carboxy Methyl ethyl cellulose, microcrystalline cellulose, polyacrylamide, polyacrylamide amination, polyacryl hydrazide, acrylamide / metal acrylate copolymer, polyacrylamide / polyacrylate copolymer, polyvinyl alcohol, acrylic rubber, At least selected from guar gum, starch and silicone Is one, the gas generating agent molded article according to claim 1.   The gas generating agent molded body according to any one of claims 1 to 4, wherein a maximum thickness of the gas generating agent molded body is 0.5 to 3 mm.