JP2009137819A - Gas generating agent composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas generating agent composition needless to additionally blending a phase stabilizer because a potassium salt of a water soluble polymer acts as both of the phase stabilizer of ammonium nitrate and a binder. <P>SOLUTION: The gas generating agent composition contains ammonium nitrate and the binder, wherein the binder contains the potassium salt of the water soluble polymer acting as the phase stabilized of ammonium nitrate. The potassium salt of the water soluble polymer to become the binder is selected from a potassium salt of polyacrylic acid, a potassium salt of an acryl amide-acrylic acid copolymer, a potassium salt of an acryl amide-acrylic acid-acrylic ester copolymer, a potassium salt of carboxyl methyl cellulose and a potassium salt of xanthan gum is used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas generant composition that can be used in an inflator for an airbag device.

  Ammonium nitrate is known as a component of the gas generant shaped body. However, ammonium nitrate has a phase transition at the operating temperature of the gas generator, and there is a problem that cracks are generated in the molded body due to volume change (expansion and contraction) accompanying the phase transition. For this reason, in the gas generant molding containing ammonium nitrate, an inorganic potassium salt such as potassium nitrate or potassium perchlorate or an organic potassium salt such as potassium oxalate is conventionally blended as a phase stabilizer (patent document). 1-3).

Moreover, when obtaining a gas generating agent molded object, although a water-soluble binder is mix | blended, since the said inorganic and organic potassium salt cannot become a binder, it is necessary to mix | blend both the said potassium salt and a water-soluble binder.
JP 2002-338241 A JP-T-2006-520312 Japanese Patent Laid-Open No. 10-259085

  The present invention provides a gas generating composition that can eliminate the use of inorganic and organic potassium salts even when ammonium nitrate is blended, and has excellent moldability and performance as a gas generating agent. Let it be an issue.

  The invention according to claim 1 is a gas generating composition comprising a fuel containing ammonium nitrate and a binder, wherein the binder contains a potassium salt of a water-soluble polymer that acts as a phase stabilizer for the ammonium nitrate. provide.

  In the invention of claim 2, the water-soluble polymer potassium salt serving as the binder is a potassium salt of polyacrylic acid, a potassium salt of an acrylamide-acrylic acid copolymer, or potassium of an acrylamide-acrylic acid-acrylic acid ester copolymer. The gas generating composition according to claim 1, which is selected from a salt, a potassium salt of carboxymethyl cellulose, and a potassium salt of xanthan gum.

  Invention of Claim 3 provides the gas generating composition of Claim 1 or 2 whose 1 mass% aqueous solution viscosity is 1000-15000 mPa * s of potassium salt of the water-soluble polymer used as the said binder. .

  According to a fourth aspect of the present invention, in the potassium salt of the acrylamide-acrylic acid copolymer, the ratio of acrylamide / acrylic acid (molar ratio when charged) is 3/7 to 7/3. A gas generant composition according to any one of the above is provided.

  Although the gas generant composition of the present invention contains ammonium nitrate, inorganic and organic potassium salts for phase stabilizing the ammonium nitrate can be dispensed with. For this reason, it is possible to increase the output by increasing the fuel containing ammonium nitrate. Further, by reducing the mass of the inorganic and organic potassium salt, the mass of the necessary gas generant composition can be reduced, thereby contributing to the mass reduction of the entire airbag device inflator.

<Fuel>
In the present invention, ammonium nitrate is contained as a fuel, and other known fuels can be contained as required. The content of ammonium nitrate in the fuel is 30% by mass or more, preferably 40% by mass or more, and more preferably 50% by mass or more.

  Ammonium nitrate may be powdery or granular, which is used in known gas generating agents, and porous prill ammonium nitrate may also be used.

  Examples of other fuels include guanidine nitrate, nitroguanidine, 5-aminotetrazole, ammonium nitrate, melamine, and others described in JP-A Nos. 2002-12493 and 2001-226188.

  10-90 mass% is preferable, and, as for content of the fuel in a composition, 20-85 mass% is more preferable.

<Binder>
The binder used in the present invention contains a potassium salt of a water-soluble polymer, and may contain other known binders as necessary. The potassium salt of the water-soluble polymer is a component that acts to enhance moldability and to act as a phase stabilizer for ammonium nitrate.

  In the binder, the content of the potassium salt of the water-soluble polymer is 50% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more.

  Examples of the potassium salt of the water-soluble polymer include polyacrylic acid potassium salt, acrylamide-acrylic acid copolymer potassium salt, acrylamide-acrylic acid-acrylic acid ester copolymer potassium salt, carboxymethylcellulose potassium salt, xanthan gum Those selected from potassium salts are preferred.

  The potassium salt of the water-soluble polymer preferably has a 1% by weight aqueous solution viscosity of 1000 to 15000 mPa · s, more preferably 3000 to 13000 mPa · s, and still more preferably 4000 to 12000 mPa · s. The viscosity is measured by the method described in the examples.

  The potassium salt of the water-soluble polymer is particularly preferably a potassium salt of an acrylamide-acrylic acid copolymer, and the potassium salt of the acrylamide-acrylic acid copolymer is a ratio of acrylamide / acrylic acid (mole at the time of preparation during synthesis). The ratio is preferably 3/7 to 7/3, more preferably 4/6 to 6/4.

  Examples of other binders include those described in JP-A-2002-12493.

  5-30 mass% is preferable and, as for content of the binder in a composition, 10-25 mass% is more preferable.

<Oxidizing agent>
In the present invention, ammonium nitrate itself functions as a fuel and an oxidant, but may contain other known oxidizers as necessary.

  Examples of other oxidizing agents include basic copper nitrate, basic copper carbonate, sodium nitrate, strontium nitrate, sodium perchlorate, and ammonium perchlorate.

  When the oxidizing agent contains a fuel other than ammonium nitrate, it can contain about 10 to 50 parts by mass with respect to 100 parts by mass of the fuel.

[Other ingredients]
In the composition of the present invention, known additives for gas generating agents can be blended within a range in which the problems of the present invention can be solved.

  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; Cobalt, calcium carbonate, basic zinc carbonate; metal oxide or hydroxide complex compound containing acid clay, kaolin, talc, bentonite, diatomaceous earth, hydrotalcite; sodium silicate, mica molybdate, cobalt molybdate And metal acid salts such as ammonium molybdate; silicone, molybdenum disulfide, calcium stearate, silicon nitride, silicon carbide, and the like.

  The 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.

  These molded products are prepared by adding water or an organic solvent to the composition, mixing and extruding (single-hole cylindrical or porous cylindrical molded body) or compression-molding using a tableting machine (pellet-like). ). 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 composition of the present invention or a molded body obtained from the same is, 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 inflatable curtain, an inflator for a knee bolster, It can be applied to inflators for inflatable seat belts, inflators for tubular systems, and gas generators for pretensioners.

  The inflator using the composition of the present invention or a molded product obtained from the composition is either a pyro-type gas supply 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 used. But you can.

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

Examples 1-4, Comparative Example 1
Ammonium nitrate and a water-soluble polymer shown in Table 1 were weighed, and 30 ml of ion-exchanged water was added and dissolved, and the mixture was evaporated to dryness at 80 ° C. to obtain a gas generating composition for phase stabilization test. The compositions of Examples and Comparative Examples were subjected to differential thermal analysis under the following conditions, and the presence or absence of the endothermic peak accompanying the phase transition of ammonium nitrate (if the endothermic peak was extinguished, it means that the phase was stabilized. Confirmed).

Measuring device TGDTA6300 (manufactured by Seiko Epson)
Measurement conditions Gas flow rate: Ar100ml / min
Temperature increase rate: 10 ° C / min
Temperature range: 30-500 ° C

Water-soluble polymer (1): Potassium salt of acrylamide-acrylic acid copolymer (acrylamide / acrylic acid molar ratio = 5/5, 1 mass% aqueous solution viscosity = 10,700 mPa · s)
Water-soluble polymer (2): Potassium salt of acrylamide-acrylic acid copolymer (acrylamide / acrylic acid molar ratio = 5/5, 1 mass% aqueous solution viscosity = 6,040 mPa · s)
Water-soluble polymer (3): Potassium salt of acrylamide-acrylic acid copolymer (molar ratio of acrylamide / acrylic acid = 6/4, 1% by weight aqueous solution viscosity = 11,220 mPa · s)
Water-soluble polymer (4): Potassium salt of acrylamide-acrylic acid copolymer (acrylamide / acrylic acid molar ratio = 4/6, 1 mass% aqueous solution viscosity = 10,120 mPa · s)
Water-soluble polymer (5): acrylamide-acrylic acid copolymer (molar ratio of acrylamide / acrylic acid = 6/4, 1 mass% aqueous solution viscosity = 12,700 mPa · s).

(Measurement method of viscosity)
A potassium salt of a water-soluble polymer is sufficiently dissolved in pure water to prepare a 1% aqueous solution. Attach a rotor to the B-type viscometer and set the sample aqueous solution after stirring. The rotor was operated at a rotational speed of 6 rpm at 25 ° C., and the viscosity was determined by reading the scale on the viscometer after 5 minutes.

Examples 5 and 6, Comparative Examples 2 and 3
After adding 1500 parts by mass of ion exchange water to the total mass of ammonium nitrate and water-soluble polymer shown in Table 2 and dissolving, it was evaporated to dryness. The dried product was pulverized and passed through a sieve having an opening of 300 μm. 100 g of the sieved material was weighed, 20 ml of ion-exchanged water was added thereto, mixed with an extruder, and then extruded into a strand shape through a die (pore diameter 2 mm) to obtain a molded article of the gas generant composition of the present invention. In the extruded state, the moldability was evaluated according to the following criteria.
○: The strand could be extruded without breaking 1 m or more (a level at which industrially stable extrusion can be performed)
X: Strand cut at less than 0.5 m (industrially unsuitable)

Claims (4)

  A gas generating composition comprising a fuel containing ammonium nitrate and a binder, wherein the binder contains a potassium salt of a water-soluble polymer that acts as a phase stabilizer for the ammonium nitrate.   The potassium salt of the water-soluble polymer used as the binder is potassium salt of polyacrylic acid, potassium salt of acrylamide-acrylic acid copolymer, potassium salt of acrylamide-acrylic acid-acrylic acid ester copolymer, potassium salt of carboxymethyl cellulose The gas generant composition according to claim 1, which is selected from potassium salts of xanthan gum.   The gas generating composition according to claim 1 or 2, wherein the water-soluble polymer potassium salt serving as the binder has a 1% by mass aqueous solution viscosity of 1000 to 15000 mPa · s.   The gas according to any one of claims 1 to 3, wherein the potassium salt of the acrylamide-acrylic acid copolymer has an acrylamide / acrylic acid ratio (molar ratio at the time of preparation) of 3/7 to 7/3. Generator composition.