HUT76867A - Gas developing agent - Google Patents

Abstract

A gas developing agent, in particular for airbags, contains (A) at least one carbonate, hydrogen carbonate or nitrate of guanidine, aminoguanidine, diaminoguanidine or triaminoguanidine; (B) at least one alkaline or alkaline earth nitrate or ammonium nitrate as oxidising agent; and (C) at least one carrier selected among silicon dioxide, alkaline, alkaline earth or aluminosilicates, and/or at least one oxygen-supplying carrier selected among ferric oxide, cobalt oxides, manganese dioxide and cupric oxide, to moderate combustion and improve ash formation. This gas developing agent has improved combustion and ash formation.

Description

The present invention relates to solid gas generating agents based on guanidine compounds applied to suitable carriers.

JP H5-254977 discloses triaminoguanidine nitrate (TAGN) based gas generating agents for use in airbags which, in addition to TAGN, also contain oxidizing agents such as alkali metal and alkaline earth metal nitrates, nitrites, chlorates and perchlorates. may contain • ·

It does. As additional component, molybdenum sulfide may also be present. In contrast to the known sodium azide, TAGN has the advantage that it is non-toxic and has better stability, in addition, it does not form friction-sensitive salts and when combined with heavy metals it produces an impact. The burning rate of the gas generating agents can be controlled by varying the compression pressure of the pellets or tablets made from the blend of ingredients.

A further disadvantage of such gas generating agents is that their combustion, the formation of toxic gases during combustion, such as CO, and incineration due to incomplete combustion, cannot be properly controlled, resulting in a significant amount of dust that can enter the lungs.

In contrast to the solution disclosed in JP H5-254977, it is an object of the present invention to provide improved gas generating agents whose combustion properties are accurately controlled and the slag formed during combustion is easily retained and minimal amounts of toxic gas are produced. Such gas generating agents must have good thermal stability, be readily ignitable, be quick enough to store, even at low temperatures, and have a high gas generating capacity. In addition, these gas generating agents must be capable of reducing the size and, consequently, the weight of the gas generating device compared to known sodium azide-operated devices.

According to the invention, these objects are achieved by a gas generating agent which comprises (A) at least one guanidine, aminoguanidine, diaminoguanidine or triaminoguanidine carbonate, bicarbonate or nitrate, and (B) at least one oxidizing agent. an alkali metal or alkaline earth metal nitrate or ammonium nitrate and (C) at least one burn reducing and slagging agent selected from the group consisting of silica, alkali metal silicates, alkaline earth metal silicates, and aluminosilicates; or at least one oxygen generating carrier selected from the group consisting of iron (III) oxide, cobalt oxides, manganese dioxide and copper (II) oxide.

Component (A) may be guanidine, aminoguanidine, diaminoguanidine or triaminoguanidine carbonates, bicarbonates or nitrates, or mixtures thereof. Triaminoguanidine nitrate (TAGN) is preferably used. TAGN is virtually non-toxic (LD _5Q greater than 3500 mg / kg rat), non-hygroscopic, slightly soluble in water, heat-stable, low-temperature combustible, and slightly sensitive to friction and shock. TAGN combustion gas production is very high, generating large amounts of nitrogen gas. Optionally, TAGN may be substituted with 1-50% by weight of nitro-guanidine. This reduces the cost of the (A) kmponder and achieves advantageous combustion properties as the burning rate of nitroguanidine is lower than that of TAGN.

Alkali metal or alkaline earth metal nitrates, ammonium nitrate and mixtures thereof may be used as component (B) as oxidizing agent. Potassium nitrate is preferably used. Potassium nitrate is non-hygroscopic, non-toxic and has a high gas production and low combustion temperature during combustion.

In the mixture of components (A) and (B), the amount of component (A) is about 20-55% by weight, preferably about 50-55% by weight, the amount of component (B) is about 80-45% by weight, preferably about 50-45% by weight crowd%. Preferably, component (A) is present in an amount of about 50-55% by weight and component (B) is present in an amount of about 50-45% by weight (B).

As component (C), the carrier may be silica, alkali metal silicates, alkaline earth metal silicates or aluminum silicates, or mixtures thereof. Examples are Aerosil 200 and Aerosil 300, high dispersion silica and diatomaceous earth. A preferred carrier is silica having a pH of about 7.

Component (C) may also be iron (III) oxide, cobalt oxides, manganese dioxide and copper (II) oxide or mixtures thereof. The preferred oxygen carrier is iron (III) oxide.

Based on the total amount of components (A) and (B), component (C) is from about 5 to about 45% by weight, preferably about

8-20% by weight. When used as oxygen carrier (C), iron (III) oxide is present in an amount of about 20-40% by weight, preferably about 25-35% by weight, based on the total amount of components (A) and (B).

Component (C) serves to reduce combustion, i.e. to adjust the burning rate. At the same time it improves slag and melt formation. Slag formation is essential, for example in airbags.

The air bag consists essentially of a gas generator, usually in the form of a tablet, and an ignition device (explosive charge) for starting the combustion of the gas generator, and a gas bag. Suitable ignition devices are described, for example, in U.S. Patent No. 4,931,111. The initially small-sized gas bag is filled during the combustion of the gas generating agent after the start of combustion and is produced in a total volume of about 10-50 ms. We must prevent hot sparks, molten material and solids from entering the gas bag from the gas generator as this may result in the gas bag being damaged or injuring persons in the vehicle. This is achieved by slag formation.

At the same time, the formation of slag reduces the formation of powder-type components that may be liberated from the airbag gas generator. Powder-like particles entering the lungs have a diameter of about 6 μτη or less. In addition, oxygen replacement carriers inhibit the formation of toxic gases such as carbon monoxide during combustion.

Optionally, the gas generating agent may also comprise a water soluble binder as component (D) at room temperature. Preferred binders are cellulose compounds or one or more polymerizable, unsaturated olefin monomeric polymers. Examples of cellulose compounds are cellulose esters such as carboxymethyl cellulose, methyl cellulose ether, in particular methyl hydroxyethyl cellulose. Suitable methylhydroxyethylcellulose available from Aqualon is CULMINAl / ^R ) MHEC 30000 PR. Suitable binder polymers include polyvinylpyrrolidone, polyvinyl acetate, polyvinyl alcohol and polycarbonates.

The amount of component (D), based on the total weight of components (A) and (B), is from about 0.1 to about 5% by weight, preferably from about 1.5 to about 2.5% by weight.

Component (D) serves as a desensitizing agent and as an excipient in the manufacture of granules and tablets from a gasifier. Furthermore, it reduces and stabilizes the hydrophilic nature of the gas generating agent.

Tablets or pellets of gasifier used in the gasifier may be prepared by known methods, such as hot pressing, extrusion, rotary press or tabletting. The size of the pellet or tablet will depend on the burning time required for the particular application.

The invention is illustrated by the following examples.

Calculated amounts of triaminoguanidine nitrate (TAGN), optionally nitroguanidine, potassium nitrate and optionally cellulose ether are dissolved in as little water as possible at 90 ° C and iron oxide and / or about 1 μτη silica having an average particle size is added to the solution. After pre-drying at 60 ° C and 16 hPa by mechanical agitation, the mixture is still pulverized in the wet state and then dried at 60 ° C to a tablet having a diameter of 6 mm and a thickness of 2 mm.

The mixtures tested are listed in Table I. Mixture 1 does not contain silica and Mixture 5 does not contain iron (III) oxide. Mixture 6, used as a reference mixture, contains neither silica nor ferric oxide. In the table, the composition of the mixtures is given by weight.

Table I

1 2 3 4 5 6 member 39.1 39.1 39.1 29.1 47.3 53.0 Nitroguanidine - - - 10.0 - - kno ₃ 30.9 30.9 30.9 30.9 40.7 47.0 ^Re 2®3 30.0 20.0 14.0 14.0 - - SiO ₂ - 10.0 14.0 14.0 12.0 - Cellulose ether - - 2.0 2.0 - -

II. Table 4 shows the calculated values of the reaction parameters. A high reaction temperature is obtained for mixture 5 and especially for mixture 6.

II. spreadsheet

O ₂ equilibrium % +2.13 +1.13 -1.84 - • 1.57 + 0.25 +0.84 Volume cm ³ 1000 1000 1000 1000 1000 1000 Fill density g / cm -1 0.1 0.1 0.1 0.1 0.1 Pressure bar 427 444 470 457 654 810 Temperature K 1973 2116 2116 2116 2468 2666 The employee molar number of gases mol / kg 21.1 22.6 23.9 23.4 27.5 28.8 Heat blast J / g 3369 3092 2998 2913 3852 4566 In III. Table A burn in, 298 ° K resulting shows reaction products and their quantities, Hangs

temperature 1500 K.

III. spreadsheet Compound 1 2 3 4 5 6 (crowd%) co ₂ 3.604 10.086 11.538 13.228 12.408 3.768 h ₂ ° 18.952 18.817 18.828 17.711 22.935 26.692 ^N 2 27.219 27.219 27.217 26.735 33.383 37.596 CO 0,000 0.134 1,283 1,223 0,000 0,000 ^H 2 0,000 0,017 0.139 0.109 0,000 0,000 WOMAN 0,001 0,000 0,000 0,000 0,009 0,018 ° 2 0,001 0,000 0,000 0,000 0.248 0.826 HCN 0,000 0,000 0,000 0,000 0,000 0,000 nh ₃ 0,000 0,000 0,003 0,002 0,000 0,000 KOH 0.086 0,000 0,003 0,003 0.053 0.101 ^{K 2} C ° 3 21.014 0,000 0,000 0,000 0,150 31.997 FeO - - 12.597 12.597 - - ^Fe 2 ° 3 3,726 0,000 0,000 0,000 - - ^Fri 3 ° 4 25.396 19.331 0,000 0,000 - 0,000 R ^ SiO ^ - 23.572 23.572 23.572 30.813 - SiO ₂ - 0.820 4.820 4.820 - -

The IV. Table II shows the results of tests for the degradation, stability, slagging and burning behavior of the various mixtures. The combustion properties of the mixtures shown are from good to very good, especially at constant high burning rates. Only Comparative Mixture 6, which contained no silica or iron (III) oxide as component (C), showed inadequate slag formation and inadequate burning properties.

• · • · ·

ARC. spreadsheet

Mix 1 2 3 4 5 6 Decomposition temperature ° C *) 207 178 203 - Measuring conditions: Decomposition temperature under Starting from 15 ° C a acceleration speed 2 ° C / min Stability: Dutch test

Weight of sample: 2.5 g

Test temperature: 105 ° C

Examination duration: 72 hours Weight Loss (% by weight) - 0.28 0.40 0.13 - Slag formation ++ ++ + + + + ++ combustibility +++ + + + + + Note: ++ is very good; + good; - inadequate

*) Other stability tests were also performed on Mixture 1:

1. Mixture stability studies

1. Differential thermal analysis

Equipment: HERAEUS - FUS-O-MAT

Heating rate: 10 ° C / min, sample starting weight 10 mg

Result: KNO ^ conversion: 129/130 ° C

Exothermic onset: 168 ° C

2. Differential thermogravimetry

Equipment: LINSEIS - Simultan DTA / TG

Heating rate: 5 ° C / min, sample starting weight 20 mg

Result: KNO ^ conversion: 127 ° C

Exothermic onset: 135 ° C

Flash point: 158 ° C

Combustion test 1

The combustion test of Mixture 1 is performed in a standard aluminum gas generator, equipped with a hole for the application of a pressure gauge in a 60-liter tank, fitted with a hole for the pressure gauge. The test temperature for test 1 is -35 ° C and the gas generator weighs 51.0 g. The gas generator filling is a tablet of 6 mm diameter and 2 mm thick.

Figure 1 shows the pressure in the combustion chamber after the burst in 10 ⁵ Pa as a function of time (ms).

The pressure is set within about 1.5 ms and is reduced to half of the maximum pressure within about 27 ms. The maximum pressure develops in 1.88-10 ⁷ Pa and 12.3 ms.

Analysis of the toxic gas components formed, expressed in ppm

CO 300 NH ₃ 70 ΝΟ _χ 60

Combustion Test 2

The combustion test for Mixture 2 was performed in an aluminum Euro gas generator with a hole for the use of a pressure gauge, used for a 35 liter air bag in a 60 liter tank. Test temperature for test 2 is -35 ° C and test temperature for test 3 is + 20 ° C. The amount of gassing agent fill was 41.0 g in Test 2 and 30.0 g in Test 3. The gas generator filling is a tablet of 6 mm diameter and 2 mm thick.

Figure 2 in Test 2 after the burst • · • · • · ·

- depicts 10 pressures occurring in 10 ⁵ Pa units as a function of time (ms).

The pressure is set within about 1.5 ms and the pressure drops to about half its maximum value in about 27 ms. The maximum pressure develops in 1.45-10 Pa and 15.7 ms.

Figure 3 depicts the post-burst pressure in Test 3 in units of 10 ⁵ Pa as a function of time (ms).

The pressure is set within about 1.5 ms and the pressure drops to about half its maximum value in about 27 ms. The maximum pressure develops in 1.33-10 Pa and 7.5 ms.

The gas generating agent of the present invention consists of non-toxic, readily obtainable, and inexpensive components that are easy to process. Their thermal stability results in good shelf life. Despite their low flash point, the flammability of the mixtures is good. They burn quickly and have a high gas yield, and the gas produced contains very few CO and NO components. The mixtures according to the invention are therefore particularly suitable for use as a gas generating agent in various airbag systems and as a fire extinguisher or propellant. In addition, gas generating agents can be easily recycled.

Claims (12)

Claims A gas generating agent, characterized in that (A) 20-55% by weight of at least one guanidine, aminoguanidine, diaminoguanidine or triaminoguanidine carbonate, bicarbonate or nitrate, (B) 80-45% by weight of at least one alkali metal or alkaline earth metal nitrate or ammonium nitrate as oxidizing agent and based on the total amount of components (A) and (B) to reduce combustion and improve slag formation 5 to 45% by weight (Cl) of at least one carrier selected from the group consisting of silica, alkali metal silicates, alkaline earth metal silicates or aluminum silicates, and / or (C2) at least one oxygenating agent selected from iron (III) oxide, cobalt oxides, manganese dioxide and copper (II) oxide. A gas generator according to claim 1, characterized in that 50-55% by weight of component (A), 50-45% by weight of component (B) and 8-20% by weight based on the total weight of components (A) and (B) It consists of (Cl) and / or (C2) components. Gas generator according to claim 1 or 2, characterized in that component (A) is triaminoguanidine nitrate. A gas generating agent according to any one of claims 1 to 3, characterized in that component (B) is potassium nitrate. A gas generator according to any one of claims 1 to 4, characterized in that the silica has a pH of about 7 around component (Cl). A gas generator according to any one of claims 1 to 5, characterized in that component (A) is 99-50% by weight of triaminoguanidine nitrate and 1-50% by weight of nitroguanidine, based on the total weight of component (A). available. A gas generator according to any one of claims 1 to 6, characterized in that component (C2) is iron (III) oxide. The gas generator according to claim 7, characterized in that it contains from 20 to 40% by weight, preferably 25 to 35% by weight, of iron (III) oxide, based on the total weight of the components (A) and (B). A gasifier according to any one of claims 1 to 8, further comprising a water-soluble (D) binder at room temperature. 10. A gas generator according to claim 9, characterized in that the binder is a monomeric polymer of cellulose ether such as carboxymethylcellulose, methylcellulose ether and especially methylhydroxyethylcellulose or one or more polymerizable unsaturated olefins. Gas generator according to Claim 9 or 10, characterized in that it contains from 0.1 to 5% by weight, preferably from 1.5 to 2.5% by weight, based on the total weight of the components (A) and (B). Use of a gas generating agent according to any one of claims 1 to 11 as a gas generating agent in air bags, as a vaccine or as a propellant.