Pyrotechnic solid substance for generating gas, pyrotechnic composition and gas generator

Abstract

The invention relates to a pyrotechnic solid substance for generating gas, a pyrotechnic composition and a gas generator, comprising an effective composition, the effective composition comprising, by weight, 40%-50% of guanidine nitrate, 6%-48% of basic copper nitrate, 1%-5% of alumina and 5%-15% of at least one coolant prepared from hydrated oxalate, and the pyrotechnic solid substance does not contain a binder component. The pyrotechnic solid substance has the beneficial effects that the pyrotechnic solid substance capable of generating gas, which is composed of the effective compositions, has the characteristics of high gas production rate, high combustion rate, low combustion temperature, low pressure index, small toxicity of released gas and the like, and is particularly suitable for an in-vehicle safety airbag as a passenger protection system.

Description

Technical Field

[0001] The invention relates to the technical field of pyrotechnics, in particular to a pyrotechnic solid material for generating gas, a pyrotechnic agent and a gas generator. Background Art

[0002] In order to achieve miniaturization and lightness of automotive gas generators, when a coolant (an additive used to reduce the combustion temperature) is added to the gas generator, the combustion temperature of the gas generator is lowered, the slagging rate is increased, and the cooler and filter in the gas generator can be removed.

[0003] JP-A 2004-155645 discloses a gas generant composition containing aluminum hydroxide as a component for lowering combustion temperature and improving ignition properties, and states that the average particle size (D50) of the aluminum hydroxide is preferably 0.1-70 μm, more preferably 0.5-50 μm, and further preferably 2-30 μm.

[0004] JP-A 9-165287 discloses a gas generant composition containing iron oxide as a coolant, wherein 50% by weight or more of the iron oxide is particles having an average particle size of more than 100 μm.

[0005] CN-101990526A describes guanidine nitrate type (GN, 35-45 weight percent, as fuel) + basic copper nitrate (BCN, 40-50 weight percent, as oxidant) + coolant (1-10 weight percent) + binder (CMCNa, 2-8 weight percent), and discloses a coolant containing at least one of aluminum hydroxide, magnesium hydroxide, calcium hydroxide, zirconium hydroxide, magnesium carbonate, copper carbonate, calcium carbonate, copper oxalate, magnesium oxalate, iron oxalate, and calcium oxalate, wherein the average particle size (D50) of the coolant is recorded to be 10-70μm, preferably 15-60μm, and more preferably 20-50μm, and the 10% volume cumulative particle size (D10) is 5μm or more, preferably 5.5μm or more, and more preferably 6.0μm.

[0006] US631630 describes the use of a relatively large amount (15-25 weight percent) of an endothermic agent (coolant) selected from alkali metal or alkaline earth metal formates, alkali metal or alkaline earth metal oxalates, and mixtures thereof in a composition of guanidine nitrate type (GN, 15-35 weight percent, as reducing agent) + strontium nitrate (Sr(NO3)2, 30-50 weight percent, as oxidizing agent). The document actually only describes the use of calcium formate in the composition, which, in addition to the guanidine nitrate + strontium nitrate, also contains an explosive component (HMX type) for increasing the burning rate and a binder (polyethylene / butylene-polystyrene block copolymer type binder), and the composition is obtained by a dry process.

[0007] CN-110325492A describes a guanidine nitrate type (GN, 35-50 weight percent, as a reducing agent) + basic copper nitrate (BCN, 35-50 weight percent, as an oxidizing agent) + anhydrous oxalate (5-18 weight percent, as a coolant), and discloses a coolant containing sodium oxalate, tin oxalate, strontium oxalate, iron oxalate, copper oxalate and a mixture thereof, wherein the oxalate is in anhydrous form, and the composition further contains aluminum oxide or an inorganic titanate having a melting point above 2100K.

[0008] Experiments have found that the cooling effect and gas production of coolant carbonates (such as magnesium carbonate, copper carbonate, and calcium carbonate) are lower than those of their corresponding oxalates such as magnesium oxalate, copper oxalate, and calcium oxalate. The addition of coolant hydroxides and iron oxides reduces the gas production rate of the gas generator and increases the smoke released. In addition, some substances such as magnesium hydroxide and calcium hydroxide are alkaline, while the basic nitrates in the gas generator components are acidic, resulting in the thermal stability and chemical stability of the gas generator failing to meet the requirements. Sodium oxalate and basic copper nitrate (BCN) react under high temperature (107°C) to produce oxidation, showing thermochemical instability and causing the gas generator to fail. Tin oxalate and iron oxalate cause component incompatibility problems in the formula. Copper oxalate without crystalline water, calcium oxalate without crystalline water, and magnesium oxalate without crystalline water are difficult to obtain raw materials. Strontium oxalate without crystalline water is sensitive to moisture and easily absorbs moisture at room temperature to transform into strontium oxalate monohydrate. Summary of the invention

[0009] The object of the present invention is to overcome the deficiencies of the prior art and to provide a pyrotechnic solid material, a pyrotechnic agent and a gas generator for generating gas, which have low combustion temperature, high slagging rate, high gas production rate, high burning speed, low concentration of harmful gases, and good thermal stability and chemical stability.

[0010] The present invention relates to a gas-generating pyrotechnic solid material, comprising an effective composition, wherein the effective composition, expressed in weight percentage, comprises: 40%-50% guanidine nitrate; 6%-48% basic copper nitrate; 1%-5% alumina; and 5% to 15% of at least one coolant prepared from hydrated oxalate, Furthermore, the pyrotechnic solid material does not contain any binder component.

[0011] Furthermore, the coolant is at least one of copper oxalate hemihydrate, strontium oxalate monohydrate, magnesium oxalate dihydrate and a mixture thereof.

[0012] Furthermore, the purity of the effective composition is 98%-100% by weight.

[0013] Furthermore, the D50 of the guanidine nitrate, basic copper nitrate, aluminum oxide and aqueous oxalate is less than or equal to 20 μm.

[0014] Furthermore, the D50 of the guanidine nitrate is less than or equal to 15 μm.

[0015] Furthermore, the D50 of the basic copper nitrate is less than or equal to 8 μm.

[0016] Furthermore, D50 of the alumina and the hydrated oxalate is less than or equal to 5 μm.

[0017] Furthermore, the effective composition is obtained by a dry approach method, which includes the following steps: compacting a powdery mixture containing the powdery components of the object, and then granulating and forming.

[0018] The present invention also provides a pyrotechnic composition comprising the effective composition.

[0019] The present invention also provides a gas generator containing a pyrotechnic solid substance for generating gas, comprising the above-mentioned effective composition.

[0020] The advantages of the present invention are as follows: guanidine nitrate (GN) accounting for 40%-50% is used as a reducing agent, which has large gas production, good compression performance and good safety performance; basic copper nitrate (BCN) accounting for 36%-48% is used as an oxidant, which can control the combustion rate, and it itself contains copper elements and has slagging performance; aluminum oxide with a content of 1%-5% and a melting point greater than 2300K is used as a slagging agent, which has a significant agglomeration and slagging effect on combustion residues; oxalate containing crystal water is used to reduce the temperature of the combustion product, and at the same time, non-toxic carbon dioxide and water vapor are generated, the gas production is increased, the decomposition temperature is not lower than 110°C, and the oxalate containing crystal water itself is non-toxic and harmless and easy to obtain.

[0021] The pyrotechnic solid material that generates gas formed by the above effective combination has the characteristics of high gas production, fast burning rate, low burning temperature, low pressure index and low toxicity of released gas, and is particularly suitable for in-vehicle airbags as a passenger protection system.

[0022] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a composition diagram of the effective composition in the examples and comparative examples.

[0025] Figure 2 Graph showing the combustion characteristics of the pyrotechnic compositions of the examples and the comparative example.

[0026] Figure 3 It is a graph showing the actual test results of the pyrotechnic composition in the embodiment. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0028] A gas-generating pyrotechnic solid material comprises an effective composition, wherein the effective composition, expressed in weight percentage, comprises: 47% guanidine nitrate; 44% basic copper nitrate; 1.0% alumina; and 8% magnesium oxalate dihydrate, Furthermore, the pyrotechnic solid material does not contain any binder component.

[0029] In the above embodiments, the purity of the effective composition is 98%-100% by weight.

[0030] In the above embodiment, the content of guanidine nitrate is 43.8%, sold by German Ali Group, 10-14 μm grade, D50≈12 μm.

[0031] In the above embodiment, the content of basic copper nitrate is 38.5%, sold by Sheppard Chemical Company of the United States, 1-6 μm grade, D50≈5 μm.

[0032] In the above embodiment, the content of aluminum oxide is 1%, sold by Evonik Industries, Germany, with a diameter of 10-100 nm and a specific surface area of ​​100 m 2 / g.

[0033] In the above embodiment, the content of magnesium oxalate dihydrate is 8%, sold by Anhui Yalong Company of China, 2-6 μm, D50≈5 μm. Example 2

[0034] Its main features are the same as those of Example 1, except that: the effective composition, expressed in weight percentage, comprises: 44.1% guanidine nitrate; 41.9% basic copper nitrate; 2.5% alumina; and 11.5% strontium oxalate monohydrate, Furthermore, the pyrotechnic solid material does not contain any binder component.

[0035] In the above embodiment, the content of strontium oxalate monohydrate is 11.5%, sold by French ISALIS company, 2-8 μm, D50≈5 μm. Example 3

[0036] Its main features are the same as those of Example 1, except that: the effective composition, expressed in weight percentage, comprises: 43.8% guanidine nitrate; 38.5% basic copper nitrate; 2.7% alumina; and 15% copper oxalate hemihydrate, Furthermore, the pyrotechnic solid material does not contain any binder component.

[0037] In the above embodiment, the content of the copper oxalate hemihydrate is 15%, sold by Anhui Yalong Company of China, with a grade of 1-6 μm and D50≈5 μm.

[0038] In the above embodiment, the effective composition is obtained by a dry approach method, which includes the following steps: compacting a powdery mixture containing the powdery components of the object, and then granulating it. Example 4

[0039] 46.5% guanidine nitrate; 40.8% basic copper nitrate; 2.7% alumina; and 10% copper oxalate hemihydrate, Furthermore, the pyrotechnic solid material does not contain any binder component. Example 5

[0040] 49.2% guanidine nitrate; 43.1% basic copper nitrate; 2.7% alumina; and 5% copper oxalate hemihydrate, Furthermore, the pyrotechnic solid material does not contain any binder component.

[0041] Comparative Example 1 The effective composition is expressed in weight percentage and comprises: 52% guanidine nitrate; 44% basic copper nitrate; 4% strontium titanate.

[0042] Comparative Example 2 The effective composition is expressed in weight percentage and comprises: 52.7% guanidine nitrate; 44.6% basic copper nitrate; 2.7% alumina.

[0043] Comparative Example 3 The effective composition is expressed in weight percentage and comprises: 47% guanidine nitrate; 44% basic copper nitrate; 1% alumina; 8% magnesium oxalate.

[0044] Comparative Example 4 44.1% guanidine nitrate; 41.9% basic copper nitrate; 2.5% alumina; 11.5% strontium oxalate.

[0045] Comparative Example 5 The effective composition is expressed in weight percentage and comprises: 43.8% guanidine nitrate; 38.5% basic copper nitrate; 2.7% alumina; 15% Copper Oxalate Each example and comparative example is directed to the effective composition obtained in the examples and comparative examples.

[0046] Figure 2 It shows that the combustion temperature of control example 1 and control example 2 is not much different, the combustion temperature of embodiment 1 is reduced by 164°C compared with control example 1, the combustion temperature of embodiment 2 is reduced by 168°C compared with control example 1, and the combustion temperature of embodiment 3 is reduced by 169°C compared with control example 1. It can be seen from the results that the addition of hydrated oxalate can significantly reduce the combustion temperature.

[0047] Reference Figure 2Compared with the control example 1, the combustion temperature of the embodiment 4 is reduced by 110°C, and the combustion temperature of the embodiment 5 is reduced by 52°C compared with the control example 1. It can be seen from the results that the higher the proportion of hydrated oxalate, the more obvious the cooling effect.

[0048] Reference Figure 2 Compared with control example 3, the combustion temperature of Example 1 was reduced by 34°C and the gas production increased by 2.6%; compared with control example 4, the combustion temperature of Example 2 was reduced by 44°C and the gas production increased by 2.1%; compared with control example 5, the combustion temperature of Example 3 was reduced by 25°C and the gas production increased by 1.3%. The results show that hydrated oxalate not only has a more obvious cooling effect than anhydrous oxalate, but also produces more gas.

[0049] Reference Figure 3 The actual measurement results show that the addition of hydrated oxalate significantly reduces the combustion heat of the composition, and the combustion rate at 20MPa is greater than 15mm / s, which meets the gas production rate requirements of the gas generator. The pressure index of the embodiment is less than 0.3, indicating that the embodiment composition can stably burn and produce gas. The skeleton appearance of the combustion residues of Example 2 and Example 3 is more complete. In particular, the technical solution in Example 2 not only has high combustion efficiency (18.3mm / s), less heat generated by combustion (2375J / g), low pressure index (0.22), and a complete skeleton of the combustion residue with good morphology, that is, the pyrotechnic solid material obtained in Example 2 has the best comprehensive gas production effect and is suitable for preparing pyrotechnic agents and gas generators.

[0050] Figure 2 The heat of combustion is calculated strictly according to the formula ratio theory, without the participation of oxygen. Figure 3 The heat of combustion is determined by referring to GJB5891.29-2006 Test Methods for Explosive Agents Part 29: Constant Temperature Method for Determination of Heat of Combustion and Explosion Heat. In actual testing, it is necessary to add excess oxygen to make the sample burn fully. Therefore, the heat of combustion of the samples in Table 3 is higher than Figure 2 According to the actual implementation data, it can be The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A gas-generating pyrotechnic solid material, characterized in that: The invention comprises an effective composition, which is expressed in weight percentage and comprises: 40%-50% guanidine nitrate; 6%-48% basic copper nitrate; 1%-5% alumina; and 5% to 15% of at least one coolant prepared from hydrated oxalate, Furthermore, the pyrotechnic solid material does not contain any binder component.

2. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The coolant is at least one of copper oxalate hemihydrate, strontium oxalate monohydrate, magnesium oxalate dihydrate and a mixture thereof.

3. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The purity of the effective composition is 98%-100% by weight.

4. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The D50 of the guanidine nitrate, basic copper nitrate, aluminum oxide and aqueous oxalate is less than or equal to 20 μm.

5. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The D50 of the guanidine nitrate is less than or equal to 15 μm.

6. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The D50 of the basic copper nitrate is less than or equal to 8 μm.

7. The gas-generating pyrotechnic solid material according to claim 1, characterized in that The D50 of the alumina and the hydrated oxalate is less than or equal to 5 μm.

8. A gas-generating pyrotechnic solid material according to any one of claims 1 to 7, characterized in that The effective composition is obtained by a dry route method, which comprises the following steps: compacting a powdery mixture containing the powdery components of the object, and then granulating and forming.

9. A pyrotechnic composition, characterized in that: The invention comprises the effective composition according to any one of claims 1 to 7.

10. A gas generator containing a pyrotechnic solid substance for generating gas, characterized in that An effective composition comprising any one of claims 1 to 7.

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