JP2009120424A - Granular firing powder composition for igniter and igniter using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a granular firing powder composition for igniters capable of reducing friction sensitivity while maintaining firing sensitivity. <P>SOLUTION: The granular firing powder composition for igniters comprises a metal powder, potassium perchlorate and potassium nitrate. The granular firing powder composition for igniters preferably comprises 40-80 mass% of the metal powder, 5-55 mass% of the potassium perchlorate and 5-30 mass% of the potassium nitrate. The metal powder preferably comprises zirconium powder or zirconium powder and tungsten powder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a pyrotechnic composition for a granular igniter and an igniter using the pyrotechnic composition, and more particularly to a pyrotechnic composition for a granular igniter with reduced friction sensitivity while maintaining ignition sensitivity. .

  Conventionally, various igniters have been developed as igniters mounted on gas generators used in automobile safety devices such as airbags and seat belt pretensioners. Such an igniter generally requires an explosive that can be ignited with minute energy. Specifically, a mixture of zirconium powder and potassium perchlorate (ZPP), zirconium powder, tungsten powder, and A technique using a mixture of potassium perchlorate (ZWPP) as an igniter composition for an igniter has been performed.

  For example, in Japanese Patent Laid-Open No. 9-227266, the corrosiveness to alkali metal perchlorate is improved by further adding a basic substance such as magnesium oxide to the pyrotechnic composition composed of ZPP or ZWPP. Technology is disclosed. JP-A-9-227266 describes the use of potassium nitrate as an oxidizing agent, but does not describe any use of alkaline perchlorate and potassium nitrate.

  Japanese Patent Application Laid-Open No. 2004-115001 discloses an inflator igniter that uses a pyrotechnic material slurry containing a fuel component and an oxidant component in a solvent and dried as a pyrotechnic material. ing. Here, examples of the oxidant component include powders selected from the group consisting of perchlorates such as potassium perchlorate, nitrates such as potassium nitrate, and mixtures thereof. Such an oxidant component is used by being uniformly dispersed in the pyrotechnic material slurry. Accordingly, in Japanese Patent Application Laid-Open No. 2004-115001, the fuel component and the oxidant component are dispersed in a solvent to increase the safety when handling a pyrotechnic material that is highly sensitive in a powder state. When zirconium is used as a combustion component, the powder is very sensitive and easily ignited. Therefore, filling the igniter in a state dispersed in a solvent can increase the safety during production. It is described. However, Japanese Patent Application Laid-Open No. 2004-115001 does not discuss safety during handling in a pyrotechnic material in a powder state, and describes a specific example in which potassium perchlorate and potassium nitrate are used in combination. Absent.

  By the way, it is known that the metal powder that can be used in the pyrotechnic composition for an igniter generally improves the ignition sensitivity as it is finer, but on the other hand, the risk of spontaneous ignition in handling during production increases. The decrease in safety was a problem. In particular, it is known that zirconium powder used as a suitable metal powder is excellent in ignition performance but has a high risk of spontaneous ignition in handling during production.

  With respect to such a problem, Japanese Patent Application Laid-Open No. 2001-348291 discloses a reduction in safety during handling while maintaining ignition sensitivity by making the shape of the metal particles forming the metal powder into a scale shape. Techniques for suppression are disclosed.

Japanese Patent Laid-Open No. 9-227266 JP 2004-115001 A JP 2001-348291 A

  However, the technique disclosed in Japanese Patent Laid-Open No. 2001-348291 has a drawback that the metal powder needs to have a special shape and the manufacturing cost is increased.

  Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a pyrotechnic composition for a granular igniter that can reduce the friction sensitivity while maintaining the ignition sensitivity. Another object of the present invention is to provide an igniter using such a pyrotechnic composition for a granular igniter.

  As a result of intensive studies to achieve the above object, the inventor of the present invention has added granulated powder by further adding potassium nitrate to the ignition agent composition containing metal powder and potassium perchlorate to form granules. The present inventors have found that the friction sensitivity can be reduced while maintaining the ignition sensitivity of the ignition igniter composition, and the present invention has been completed.

  That is, the pyrotechnic composition for a granular igniter according to the present invention is characterized by containing a metal powder, potassium perchlorate and potassium nitrate.

  In a preferred example of the pyrotechnic composition for a granular igniter of the present invention, the metal powder contains zirconium powder, or zirconium powder and tungsten powder.

  The pyrotechnic composition for a granular igniter according to the present invention preferably contains 40 to 80% by mass of the metal powder, 5 to 55% by mass of the potassium perchlorate, and 5 to 30% by mass of the potassium nitrate.

  In the pyrotechnic composition for a granular igniter of the present invention, when the metal powder contains zirconium powder, or zirconium powder and tungsten powder, the content of zirconium powder in the total of the zirconium powder and tungsten powder is 15 to It is 99 mass%, and it is preferable that the content rate of tungsten powder is 1-85 mass%.

  The igniter of the present invention is characterized by using the above-mentioned pyrophoric composition for a granular igniter.

  ADVANTAGE OF THE INVENTION According to this invention, the ignition agent composition for granular igniters which can reduce a friction sensitivity, maintaining an ignition sensitivity by mix | blending potassium nitrate with a metal powder and potassium perchlorate is provided. be able to. Moreover, the igniter using such an ignition agent composition for granular igniters can be provided.

<Pyrophoric composition for granular igniter>
Below, the ignition agent composition for granular igniters of this invention is demonstrated in detail. The pyrotechnic composition for a granular igniter according to the present invention is characterized by containing metal powder, potassium perchlorate and potassium nitrate. Usually, in order to improve the safety in handling when producing a pyrotechnic composition for a granular igniter, friction sensitivity is reduced and the pyrotechnic composition for a granular igniter is desensitized. However, when the friction sensitivity of the granular igniter composition is reduced, the ignition sensitivity is also a problem. In order to solve such a problem, the pyrotechnic composition for granular igniter according to the present invention uses a metal powder as a fuel component, a component system using potassium perchlorate as an oxidizing agent, and further contains potassium nitrate as an oxidizing agent. Thus, the friction sensitivity can be reduced while maintaining the ignition sensitivity. For this reason, the pyrotechnic composition for granular igniters of the present invention can prevent accidents during production, which has been a problem with improved ignition sensitivity. Moreover, since the pyrotechnic composition for granular igniters of this invention contains potassium nitrate as an oxidizing agent, it can reduce the content of potassium perchlorate and suppress the discharge of chlorine.

  The metal powder used in the pyrotechnic composition for granular igniters of the present invention functions as a fuel component, and specific examples include zirconium powder, tungsten powder, aluminum powder, magnesium powder, titanium powder and the like. These metal powders may be used alone or in a combination of two or more. In addition, from the viewpoint of excellent ignition performance, it is preferable to use zirconium powder alone, and from the viewpoint of reducing friction sensitivity and facilitating handling during production, the metal powder is a mixture of zirconium powder and tungsten powder. Are preferably used. In addition, a metal powder is formed by a well-known method, for example, the spherical shape obtained by a gas atomizing method is used suitably.

  The content of the metal powder used in the pyrotechnic composition for granular igniters of the present invention is preferably in the range of 40 to 80% by mass, and in the range of 55 to 70% by mass in the pyrotechnic composition for granular igniters. More preferably. If the content of the metal powder is less than 40% by mass, the ignition sensitivity may be reduced. On the other hand, if it exceeds 80% by mass, the ignition sensitivity may be reduced.

  Further, when the metal powder used in the pyrotechnic composition for a granular igniter of the present invention contains zirconium powder, or zirconium powder and tungsten powder, the content of zirconium powder in the total of zirconium powder and tungsten powder is 15 to 99 mass%, the content of tungsten powder is preferably 1 to 85 mass%, the content of zirconium powder in the total of zirconium powder and tungsten powder is 15 to 90 mass%, and the content of tungsten powder The rate is more preferably 10 to 85% by mass. When the content of the zirconium powder exceeds 99% by mass (when the content of the tungsten powder is less than 1% by mass), the bulk density is lowered and the filling property is deteriorated. On the other hand, when the content of the zirconium powder is less than 15% by mass (when the content of the tungsten powder exceeds 85% by mass), the power may be reduced.

  The metal powder preferably has a particle size of 1 to 5 μm. If the particle size of the metal powder is less than 1 μm, the ignition sensitivity is increased more than necessary, and the safety during handling of the pyrotechnic composition for granular igniters may be reduced. May decrease.

  The potassium perchlorate used in the pyrotechnic composition for granular igniters of the present invention functions as an oxidizing agent. The content of potassium perchlorate is preferably 5 to 55% by mass, more preferably 20 to 40% by mass in the pyrotechnic composition for a granular igniter. If the content of potassium perchlorate is less than 5% by mass, the ignition sensitivity may be lowered. On the other hand, if it exceeds 55% by mass, the ignition sensitivity may be lowered.

  Potassium nitrate used in the pyrotechnic composition for granular igniters of the present invention functions as an oxidant and further reduces the reactivity with metal powder, so that the ignition sensitivity of the pyrotechnic composition for granular igniters is maintained. However, friction sensitivity can be reduced. Further, the content of potassium nitrate is preferably 5 to 30% by mass in the granular igniter composition. If the content of potassium nitrate is less than 5% by mass, the friction sensitivity may be increased. On the other hand, if it exceeds 30% by mass, the ignition sensitivity may be decreased.

  The pyrotechnic composition for granular igniters of the present invention contains potassium perchlorate and potassium nitrate, but the mass ratio (A / B) of potassium perchlorate (A) to potassium nitrate (B) is 1/10 to A range of 10/1 is preferred. When the mass ratio (A / B) is smaller than 1/10 (that is, when the ratio of potassium perchlorate is reduced), the ignition sensitivity may be lowered. On the other hand, the mass ratio (A / B) is 10 / When it is larger than 1 (that is, when the proportion of potassium perchlorate increases), the effect of suppressing the discharge of chlorine cannot be sufficiently obtained.

  The pyrotechnic composition for a granular igniter according to the present invention may contain other oxidizing agent in addition to potassium perchlorate and potassium nitrate. Specific examples of the other oxidizing agent include sodium chlorate, sodium perchlorate, potassium chlorate, ammonium perchlorate, and sodium nitrate. These other oxidizing agents may be used alone or in combination of two or more. In addition, as for the content rate of another oxidizing agent, 1-5 mass% is preferable in the ignition agent composition for granular igniters.

  The pyrotechnic composition for granular igniters of the present invention preferably further contains a basic substance. In the pyrotechnic composition for a granular igniter of the present invention, corrosion of the metal portion of the igniter can be suppressed by blending a basic substance. Specific examples of basic substances that can be used in the pyrotechnic composition for granular igniters of the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, magnesium hydroxide, Metal hydroxides such as calcium hydroxide, strontium hydroxide, barium hydroxide, aluminum hydroxide; lithium oxide, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, oxidation Metal oxides such as zinc, thallium oxide, cesium oxide; lithium peroxide, sodium peroxide, potassium peroxide, rubidium peroxide, cesium peroxide, magnesium peroxide, calcium peroxide, strontium peroxide, barium peroxide, etc. Metal peroxide; lithium carbonate, charcoal Sodium, potassium carbonate, rubidium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, metal carbonates such as barium carbonate. Among these, magnesium oxide is particularly preferred. These basic substances may be used individually by 1 type, and 2 or more types may be mixed and used for them. Further, these basic substances may be water-soluble or water-insoluble. In addition, it is preferable that the content rate of a basic substance is 0.01-10 mass% in a pyrotechnic composition for granular igniters, and it is still more preferable that it is 0.05-5 mass%.

  It is preferable that the pyrotechnic composition for a granular igniter of the present invention further contains a binder. In the pyrotechnic composition for granular igniters of the present invention, by incorporating a binder, the fracture strength and other mechanical properties can be improved when forming the pyrotechnic composition for granular igniters into a molded body. Specific examples of binders that can be used in the pyrotechnic composition for granular igniters of the present invention include metal salts of carboxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, guar gum, Examples thereof include polysaccharide binders such as polyvinyl alcohol, polyacrylamide and starch, and organic binders such as stearate, fluororubber and SBS rubber. These binders may be used individually by 1 type, and 2 or more types may be mixed and used for them. In addition, it is preferable that the content rate of a binder is 0.05-5 mass% in the ignition agent composition for granular igniters.

  The pyrotechnic composition for granular igniters of the present invention includes conventional metal powders, potassium perchlorate, potassium nitrate, other oxidizing agents, basic substances, and binders as long as they do not impair the object of the present invention. From the above, the compounding agent used for the explosive can be appropriately selected and blended. As these compounding agents, commercially available products can be suitably used. The pyrotechnic composition for a granular igniter according to the present invention is manufactured by mixing, granulating, and the like by mixing various powders appropriately selected as necessary with metal powder, potassium perchlorate and potassium nitrate. Can do.

  In the method for producing a pyrotechnic composition for a granular igniter according to the present invention, as an example of a mixing method, a binder, a solvent, and a metal powder are mixed in a mixer, and then potassium perchlorate and potassium nitrate are added and further mixed. Thus, a method of obtaining a mixture of these can be mentioned. Moreover, as an example of the granulation method, there is a method in which the mixture obtained through the mixing step is taken on a pallet and air-exposed and then passed through a mesh to obtain granules. The particle size of the obtained granules is determined by the size of the mesh, but in the pyrotechnic composition for a granular igniter of the present invention, the particle size is preferably in the range of 1.0 mm or less, in the range of 0.7 mm or less. More preferably. Moreover, when measuring a granule to a certain volume, it is preferable that the particle size is uniform, but if the mesh is too coarse, the particle size is not uniform, and if the mesh is too fine, the mixture is difficult to pass. Therefore, the mesh size should be determined taking this into account.

<Ignition device>
The igniter of the present invention is characterized by using the above-described pyrotechnic composition for granular igniter. The igniter of the present invention is not particularly limited except that the above-mentioned granular igniter composition is used, and can be produced by a known method.

  Hereinafter, the igniter of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view of an example of a gas generator for a seat belt pretensioner using the igniter of the present invention. A gas generator 1 in the illustrated example includes a cup body 3 that stores a gas generating agent 2 that generates gas by combustion, an igniter 4 that is disposed inside the cup body 3 and ignites the gas generating agent 2 by energization, A cup body 3 and a holder 5 for fixing the igniter 4 are provided. In addition, the gas generator 1 can further be equipped with well-known components normally used for a gas generator. The illustrated igniter 4 includes a cup body 7 for storing the pyrotechnic composition 6, an embolus 10 in which an electrode pin 8 for electrical connection to the outside is fixed by an insulator 9, and each electrode pin. And a bridge line 11 connected between 8 and in contact with the pyrotechnic composition 6. In addition, the igniter of this invention can be further equipped with the well-known components normally used for an igniter. Here, the igniter of the present invention requires the use of the above-described pyrotechnic composition for granular igniter of the present invention as the pyrotechnic composition 6.

  The operation of the illustrated gas generator 1 will be described. When a sensor (not shown) senses a collision, a signal is sent to a control unit (actuator) (not shown), and the electrode pin 8 is energized from the control unit that has sensed this signal. Joule heat is generated, the pyrotechnic composition 6 is ignited by this heat, and the gas generating agent 2 is combusted by this flame to generate a large amount of gas. A large amount of the generated gas is introduced into a seat belt pretensioner (not shown), and the pressure in the seat belt pretensioner is increased to operate the seatbelt pretensioner and tighten the seatbelt.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

Example 1
A binder (manufactured by BNC, HIG-120) was dissolved in isoamyl acetate to prepare an isoamyl acetate solution having a binder concentration of 2% by mass. Next, 1.1 cc of the above-mentioned isoamyl acetate solution (binder concentration: 2% by mass) was added to a mixture of 6 g of zirconium powder (particle size: 2 μm) and 7 g of tungsten powder (particle size: 0.7 μm). cc was added and mixed in a mixer. Thereafter, 5.6 g of potassium perchlorate, 1.4 g of potassium nitrate and 0.1 g of magnesium oxide were added to the obtained mixture, and 2.4 cc of isoamyl acetate was further added, and the mixture was mixed again. After mixing was completed, the resulting mixture was spread on a pallet and air-exposed. After air exposure, granulation was carried out through a mesh, and the granulated product was put into a dryer and dried at 60 ° C. to obtain a pyrotechnic composition for a granular igniter (about 20 g, particle size 0.6 mm).

(Examples 2 to 4 and Comparative Example 1)
Except having changed the usage-amount of potassium perchlorate and potassium nitrate, it carried out similarly to Example 1, and prepared the ignition agent composition for granular igniters of the mixing | blending prescription shown in Table 1. In addition, a compounding quantity is the mass% on the whole composition basis.

  Next, the friction sensitivity test and the ignition sensitivity test were performed by the following method with respect to the obtained granular igniter composition. The results are shown in Table 2.

(1) Friction sensitivity test (JIS K 4810)
A friction sensitivity test was conducted by sandwiching a small amount of sample between a friction rod made of porcelain attached to a BAM type friction sensitivity tester and a friction plate, and moving the friction plate horizontally with a load applied. The degree of friction sensitivity is examined based on the relationship between the load and the success or failure of the explosion. The degree of friction sensitivity is estimated to be exploded only once or explode only once after six consecutive tests at the same load. Judgment was made by obtaining the load at the 1/6 explosion point.

(2) Ignition sensitivity test As a statistical method for calculating the minimum ignition current and the maximum misfire current, the bluestone method was used to evaluate the ignition sensitivity. Briefly, a plurality of levels divided at equal intervals are set for the energization current, and the level of the energization current is changed according to the ignition or non-ignition of the sample by energization. This is performed 40 times, and finally, statistical processing is performed to calculate the average value and standard deviation of the minimum ignition current and the maximum misfire current, and the minimum ignition current and the maximum misfire current at a desired reliability are obtained therefrom. (The confidence level of the minimum ignition current value and the maximum non-ignition current value was 95%, and the reliability was 99.9999%.)

* 1 Since two explosions occurred at a load of 75 gf and no explosion occurred at a load of 50 gf, it was judged that there was a 1/6 explosion point load between the loads of 50 and 75 gf.

  From Table 2, since the pyrotechnic composition for granular igniters of Examples 1 to 4 contains potassium nitrate, the load at 1/6 explosion point is larger than the pyrotechnic composition for granular igniters of Comparative Example 1. It can be seen that the friction sensitivity is lowered and shifted to insensitivity. Moreover, since the ignition agent composition for granular igniters of Examples 1 and 3-4 contains 5-30 mass% of potassium nitrate, it turns out that friction sensitivity can be reduced significantly.

  On the other hand, regarding the ignition sensitivity, although there are changes in the values of the minimum ignition current and the maximum non-ignition current, it can be seen that the granule igniter compositions for Examples 1 to 4 are at a level at which there is no problem in use. .

It is sectional drawing of an example of the gas generator for seatbelt pretensioners using the igniter of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas generator 2 Gas generating agent 3 Cup body 4 Igniter 5 Holder 6 Igniter composition 7 Cup body 8 Electrode pin 9 Insulator 10 Embolization 11 Telephone bridge wire

Claims (5)

  A pyrotechnic composition for a granular igniter comprising metal powder, potassium perchlorate and potassium nitrate.   2. The pyrotechnic composition for a granular igniter according to claim 1, wherein the metal powder contains zirconium powder, or zirconium powder and tungsten powder.   2. The granular igniter according to claim 1, comprising 40 to 80 mass% of the metal powder, 5 to 55 mass% of the potassium perchlorate, and 5 to 30 mass% of the potassium nitrate. Igniter composition.   The granule according to claim 2, wherein the content of the zirconium powder in the total of the zirconium powder and the tungsten powder is 15 to 99 mass%, and the content of the tungsten powder is 1 to 85 mass%. -Shaped igniter composition.   An igniter using the granular igniter composition according to any one of claims 1 to 4.

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