A pyrotechnic product based on transition metal hydroxide for regulating ignition temperature and a preparation method thereof

Abstract

The present application relates to the technical field of pyrotechnic products, and discloses a pyrotechnic product based on transition metal hydroxide for regulating ignition temperature and combustion reaction temperature and a preparation method thereof.The pyrotechnic product is composed of a binder, a water-soluble pyrotechnic oxidant, a functional additive and a combustible agent, wherein the functional additive is a transition metal hydroxide.The co-crystallization or mixed crystal of the pyrotechnic product components and trace transition metal hydroxide and the combustion catalysis of the water-soluble oxidant and the carbohydrate mixed system promote the reduction of the ignition temperature of the pyrotechnic product and realize the controllable combustion reaction temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of pyrotechnic products and relates to a pyrotechnic product with an ignition temperature controlled by a transition metal hydroxide and a preparation method thereof. Background Art

[0002] Colored smoke agents utilize the heat and gaseous products released by the combustion of oxidants and combustibles in the composition to sublime the dye and carry it into the air, producing smoke of varying colors. Traditional colored smoke agents typically use potassium chlorate as the oxidant and carbohydrates such as lactose, sucrose, and starch as combustibles. The combustion temperature of potassium chlorate and sucrose, the combustible components of the colored smoke agent, is controlled below 500°C to prevent the organic dye from carbonizing. Potassium chlorate decomposes rapidly at low temperatures, making it an ideal oxidant for colored smoke agents. However, potassium chlorate has poor antistatic properties, low energy storage stability, and high sensitivity, resulting in low safety. This poses significant safety risks during production, storage, and transportation, and has been banned from use in civilian fireworks.

[0003] Potassium perchlorate is used as an oxidant, which exhibits strong stability in anti-static and energy storage. However, potassium perchlorate has a high decomposition temperature and a slow decomposition rate, which results in a combustion system composed of potassium perchlorate and carbohydrates having a high ignition temperature, a slow reaction rate, and poor combustion persistence, affecting its application in colored smoke agents.

[0004] To overcome the drawbacks of potassium perchlorate in colored smoke agents, catalysts were introduced to increase its decomposition rate and enhance its reactivity with carbohydrates. Previous studies have reported the decomposition of potassium perchlorate using a single oxidant, but there have been no reports on the combustion catalysis of a mixture of potassium perchlorate and lactose, nor on its thermal reactivity.

[0005] In recent years, aerosol fire extinguishing agents have garnered widespread attention due to their high firefighting efficiency, low cost, and ease of use and maintenance. Compared to ozone-depleting halons, thermal aerosol fire extinguishing agents have near-zero ozone depletion potential (ODP) and global warming potential (GWP), making them environmentally friendly and harmless. Because they are mostly solid powders, they eliminate the use of pressure devices and extinguish fires through total flooding upon ignition. Therefore, they can be used in a variety of locations, including aircraft, tanks, electrical distribution boxes, kitchens, underground passages, and cinemas.

[0006] Thermal aerosol fire extinguishing agents use K-type and S-type extinguishing agents. K-type extinguishing agent uses potassium nitrate as its primary oxidant, but its combustion products are highly corrosive. To address this issue, S-type extinguishing agent was developed, using strontium nitrate as its primary oxidant. Researchers have conducted in-depth research on the formulation, extinguishing mechanism, and application of thermal aerosol extinguishing agents, achieving numerous outstanding results. However, both potassium nitrate and strontium nitrate still suffer from the problem of excessively high nozzle temperatures.

[0007] Therefore, it is particularly important to provide a pyrotechnic powder product and its preparation method that can control the ignition temperature and thus the combustion reaction temperature, has a simple preparation method, is safe to operate, and is environmentally friendly. Summary of the Invention

[0008] The present invention provides a pyrotechnic product with a transition metal hydroxide-based ignition reaction temperature control method and its preparation method. The pyrotechnic product comprises a binder, a water-soluble pyrotechnic oxidizer, a functional additive, and a combustible. The functional additive is a transition metal hydroxide. Through the co-crystallization of pyrotechnic components with trace amounts of transition metal hydroxide and the combustion catalysis of a mixed system of the oxidizer and carbohydrate, a pyrotechnic product with a low ignition temperature and a controllable combustion reaction temperature is produced.

[0009] To achieve the above-mentioned object, the present invention provides a pyrotechnic product for regulating the ignition reaction temperature based on a transition metal hydroxide, wherein the pyrotechnic product comprises a binder, a water-soluble pyrotechnic oxidant, a functional additive, and a combustible; the functional additive is a transition metal hydroxide; and the mass ratio of the binder, the water-soluble pyrotechnic oxidant, the functional additive, and the combustible is 1:(8.2-11.6):(0.1-0.2):(4.1-10.2).

[0010] Preferably, the water-soluble pyrotechnic oxidant is potassium perchlorate.

[0011] Preferably, the transition metal hydroxide is any one or more of copper hydroxide, iron hydroxide, cobalt hydroxide, and manganese oxyhydroxide.

[0012] Preferably, the combustible agent is lactose.

[0013] Preferably, the binder is any one or more of synthetic resin, polyvinyl alcohol, dextrin, nitrocellulose, and gelatin.

[0014] The present invention also provides a method for preparing a pyrotechnic product based on regulating the ignition reaction temperature using a transition metal hydroxide, comprising:

[0015] Dissolve a transition metal hydroxide in deionized water, and add an acid solution or an alkaline solution to completely dissolve it to obtain a solution A;

[0016] The water-soluble pyrotechnic oxidant and the combustible agent are mixed uniformly and completely dissolved in deionized water by ultrasonic treatment to obtain a solution B;

[0017] Solution A and solution B are mixed and then ultrasonically dispersed to obtain solution C;

[0018] The resulting solution C was freeze-dried and crystallized for 30-35 hours. The freeze-dried material was evenly mixed with a binder and placed in an oven for aging for 6-7 hours to obtain a pyrotechnic product with an ignition reaction temperature controlled by a transition metal hydroxide.

[0019] The present invention first utilizes the water solubility of transition metal hydroxides in weakly acidic or weakly alkaline conditions, as well as the water solubility of some of the main materials of the pyrotechnic composition. This allows for molecular contact between the transition metal hydroxide and the water-soluble main materials in the aqueous solution. Next, the uniformly mixed solution is suddenly frozen in a freeze-drying device, and the water is then vacuum-evacuated to form a highly uniform composite eutectic or mixed crystal material. Finally, the transition metal hydroxide is thermally decomposed into a transition metal oxide through high-temperature drying, thereby utilizing the transition metal oxide to catalyze the combustion reaction of the pyrotechnic composition.

[0020] Preferably, the mass ratio of the deionized water to the transition metal hydroxide is 1:(0.01-0.02).

[0021] Preferably, the mass ratio of the deionized water to the mixture of the water-soluble pyrotechnic oxidant and the combustible agent is 1:(0.18-0.2).

[0022] Preferably, the alkaline solution is any one or more of ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate, and the acid solution is any one or more of formic acid, acetic acid, phosphoric acid, and hypochlorous acid.

[0023] Preferably, the freeze-dried crystals are covered with a thin film, which is pierced and placed in a vacuum freeze dryer. The film can ensure that the material remains in the watch glass while the solvent sublimates smoothly.

[0024] Preferably, the oven drying temperature is 80-100° C., and aging can dehydrate copper hydroxide to generate copper oxide.

[0025] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0026] (1) The present invention uses a mixed system consisting of a water-soluble pyrotechnic oxidant and a carbohydrate as a combustion catalyst. Potassium perchlorate, as a strong oxidant, provides oxygen to the system during the combustion process, accelerating the oxidation reaction of organic matter. However, the decomposition of potassium perchlorate requires a relatively high temperature. Lactose, as an organic matter, can release a large amount of heat energy during decomposition, providing additional energy for the decomposition of potassium perchlorate, thereby increasing the reaction rate and lowering the ignition temperature at which the system begins to burn. The gaseous products (such as water vapor and carbon dioxide) generated by the decomposition of lactose increase the local temperature, further promoting the decomposition of potassium perchlorate, thereby releasing more oxygen, improving the combustion continuity, avoiding temperature fluctuations during the reaction process, and making the combustion more stable.

[0027] (2) The present invention uses co-crystallization or mixed crystals of transition metal hydroxides and pyrotechnic components. Co-crystallization or mixed crystals refers to two or more chemical substances forming a uniform composite crystal structure during the crystallization process. The particle size of the co-crystallization or mixed crystals can be controlled, so that these crystals have a larger specific surface area and can be in zero-distance contact with the combustible. Since the contact area between the reactants is increased, the reaction rate is increased. At the same time, particles with smaller particle sizes can react at lower temperatures, reducing the ignition temperature. In summary, by controlling the component ratio and structure of the co-crystallization or mixed crystals to adjust the crystal particle size, the temperature of the combustion reaction can be controlled, the reaction heat release rate can be accurately controlled, and the combustion process can be ensured to proceed within the ideal temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of thermal decomposition of a pyrotechnic product prepared in Example 1 based on regulating the ignition reaction temperature by a transition metal hydroxide.

[0029] Figure 2 Schematic diagram of thermal decomposition of a pyrotechnic product prepared in Comparative Example 1 without a transition metal hydroxide to regulate the ignition reaction temperature.

[0030] Figure 3 Schematic diagram of thermal decomposition of a pyrotechnic product prepared in Comparative Example 2 without adding lactose and based on regulating the ignition reaction temperature by using a transition metal hydroxide. DETAILED DESCRIPTION

[0031] The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide comprises the following steps:

[0034] (1) Weigh 0.1 g of copper hydroxide and add it to 10 mL of deionized water. Ultrasonicate for 10–20 min. Then, add ammonia solution dropwise to adjust the pH to a weak alkaline state. Let it stand until it is completely dissolved or forms a blue flocculent precipitate, obtaining solution A. Weigh 1.16 g of potassium perchlorate and 0.68 g of lactose and add them to 10 mL of deionized water. Ultrasonicate for 10–20 min until they are completely dissolved, obtaining solution B. Mix solutions A and B and ultrasonicate for 30–40 min until they are completely dissolved, obtaining solution C.

[0035] (2) Place solution C in a watch glass, cover it with a thin film, poke holes in it, and place it in a vacuum freeze dryer. Vacuum freeze-dry for more than 30 to 35 hours until the solvent is completely sublimated and a uniformly mixed freeze-dried material is obtained.

[0036] (3) Mix 2 g of freeze-dried material with 0.1 g of phenolic resin, place it in an oven at 80-100 °C, and let it stand for 6-7 h (the purpose of high-temperature aging is to dehydrate copper hydroxide to form copper oxide), and obtain a pyrotechnic product based on the ignition reaction temperature controlled by transition metal hydroxide.

[0037] Example 2

[0038] A method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide comprises the following steps:

[0039] (1) Weigh 0.2 g of copper hydroxide and add it to 10 mL of deionized water. Ultrasonicate for 10–20 min. Then, add ammonia solution dropwise to adjust the pH to a weak alkaline state. Let it stand until it is completely dissolved or forms a blue flocculent precipitate, obtaining solution A. Weigh 1.33 g of potassium perchlorate and 0.41 g of lactose and add them to 10 mL of deionized water. Ultrasonicate for 10–20 min until they are completely dissolved, obtaining solution B. Mix solution A and solution B and ultrasonicate for 30–40 min until they are completely dissolved, obtaining solution C.

[0040] (2) Place solution C in a watch glass, cover it with a thin film, poke holes in it, and place it in a vacuum freeze dryer. Vacuum freeze-dry for more than 30 to 35 hours until the solvent is completely sublimated and a uniformly mixed freeze-dried material is obtained.

[0041] (3) Mix 2 g of freeze-dried material with 0.1 g of phenolic resin, place it in an oven at 80-100 °C, and let it stand for 6-7 h (the purpose of high-temperature aging is to dehydrate copper hydroxide to form copper oxide), and obtain a pyrotechnic product based on the ignition reaction temperature controlled by transition metal hydroxide.

[0042] Example 3

[0043] A method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide comprises the following steps:

[0044] (1) Weigh 0.1 g of copper hydroxide and add it to 10 mL of deionized water. Ultrasonicate for 10–20 min. Then, add ammonia solution dropwise to adjust the pH to a weak alkaline state. Let it stand until it is completely dissolved or forms a blue flocculent precipitate, obtaining solution A. Weigh 0.82 g of potassium perchlorate and 1.02 g of lactose and add them to 10 mL of deionized water. Ultrasonicate for 10–20 min until they are completely dissolved, obtaining solution B. Mix solutions A and B and ultrasonicate for 30–40 min until they are completely dissolved, obtaining solution C.

[0045] (2) Place solution C in a watch glass, cover it with a thin film, poke holes in it, and place it in a vacuum freeze dryer. Vacuum freeze-dry for more than 30 to 35 hours until the solvent is completely sublimated and a uniformly mixed freeze-dried material is obtained.

[0046] (3) Mix 2 g of freeze-dried material with 0.1 g of phenolic resin, place it in an oven at 80-100 °C, and let it stand for 6-7 h (the purpose of high-temperature aging is to dehydrate copper hydroxide to form copper oxide), and obtain a pyrotechnic product based on the ignition reaction temperature controlled by transition metal hydroxide.

[0047] Comparative Example 1

[0048] A method for preparing a pyrotechnic product based on regulating the ignition reaction temperature by using a transition metal hydroxide, which differs from Example 1 in that copper hydroxide is not added in step (1).

[0049] Comparative Example 2

[0050] A method for preparing a pyrotechnic product based on regulating the ignition reaction temperature by using a transition metal hydroxide, which differs from Example 1 in that lactose is not added in step (1).

[0051] The pyrotechnic product prepared in Example 1, based on transition metal hydroxide-controlled ignition reaction temperature, was placed in an aluminum crucible and subjected to differential scanning calorimetry (DSC). Under argon, the temperature was gradually increased from room temperature (25°C) to 800°C at a rate of 10°C / min. Samples prepared in Comparative Examples 1 and 2 were tested under the same conditions.

[0052] according to Figure 1 and Figure 2As shown, the combustion and decomposition temperature of the pyrotechnic product prepared in Example 1 with copper hydroxide co-crystallization was 544.1℃, and the combustion and decomposition temperature of the pyrotechnic product prepared in Comparative Example 1 without copper hydroxide was 616.5℃. The reaction peak temperature of Example 1 decreased by 72.4℃ compared with Comparative Example 1. The experiment proved that after adding copper hydroxide co-crystallization, the contact area between the reactants was expanded, and the particles with smaller particle size could react and decompose at a lower temperature, and the ignition and reaction temperature of the pyrotechnic product decreased significantly. According to the Arrhenius equation, the reaction rate constant k is inversely proportional to the reaction activation energy Ea, and the reaction activation energy Ea is inversely proportional to the reaction temperature. Therefore, the reaction rate constant k of the pyrotechnic product prepared in Example 1 is 1.5 times that of the pyrotechnic product prepared in Comparative Example 1. Figure 1 and Figure 3 As shown, the combustion and decomposition temperature of the pyrotechnic product prepared in Example 1 with potassium perchlorate and lactose mixed catalyst system as catalyst was 51.2℃ lower than that of Example 2. The experiment proved that the decomposition of lactose provided additional heat energy for the decomposition of potassium perchlorate, promoted the decomposition and release of oxygen, improved the catalytic activity of potassium perchlorate in the reaction, and improved the overall reaction rate.

[0053] In summary, the mixed catalyst system of potassium perchlorate and lactose co-crystallized or mixed with transition metal hydroxides can significantly reduce the ignition temperature and reaction temperature of the pyrotechnic product, improve the reaction rate, and achieve adjustable ignition temperature and combustion reaction temperature of the pyrotechnic product.

[0054] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the technical principles of the present application, several improvements and modifications can be made, and these improvements and modifications should be considered as the protection scope of the present application.

Claims

1. A pyrotechnic product based on a transition metal hydroxide to control the ignition reaction temperature, characterized in that: The pyrotechnic product includes an adhesive, a water-soluble pyrotechnic oxidant, a functional additive and a combustible; the functional additive is a transition metal hydroxide; the mass ratio of the adhesive, water-soluble pyrotechnic oxidant, functional additive and combustible is 1:(8.2~11.6):(0.1~0.2):(4.1~10.2); the water-soluble pyrotechnic oxidant is potassium perchlorate; the transition metal hydroxide is any one or more of copper hydroxide, iron hydroxide, cobalt hydroxide and manganese oxyhydroxide; and the combustible is lactose.

2. A pyrotechnic product based on controlling the ignition reaction temperature of a transition metal hydroxide according to claim 1, characterized in that: The adhesive is any one or more of synthetic resin, polyvinyl alcohol, dextrin, nitrocellulose, and gelatin.

3. The method for preparing a pyrotechnic product based on controlling the ignition reaction temperature of a transition metal hydroxide according to any one of claims 1 or 2, characterized in that: include: Dissolve a transition metal hydroxide in deionized water, and add an acid solution or an alkaline solution to completely dissolve it to obtain a solution A; The water-soluble pyrotechnic oxidant and the combustible agent are mixed uniformly and subjected to ultrasonic treatment to completely dissolve them in water to obtain a solution B; Solution A and solution B are mixed and then ultrasonically dispersed to obtain solution C; The resulting solution C was freeze-dried and crystallized for 30-35 hours. The freeze-dried material was evenly mixed with a binder and placed in an oven for aging for 6-7 hours to obtain a pyrotechnic product with an ignition reaction temperature controlled by a transition metal hydroxide.

4. The method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide according to claim 3, characterized in that: The mass ratio of the deionized water to the transition metal hydroxide is 1:(0.01-0.02); the mass ratio of the deionized water to the mixture of the water-soluble pyrotechnic oxidizer and the combustible agent is 1:(0.18-0.2); the alkaline solution is any one or more of ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate; and the acid solution is any one or more of formic acid, acetic acid, phosphoric acid, and hypochlorous acid.

5. The method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide according to claim 3, characterized in that: The freeze-dried crystals are covered with a thin film, pierced with holes, and then placed in a vacuum freeze dryer.

6. The method for preparing a pyrotechnic product based on regulating the ignition reaction temperature of a transition metal hydroxide according to claim 3, characterized in that: The oven drying temperature is 80-100°C.

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