A fast-response fire extinguishing disc and its manufacturing process

Abstract

This invention relates to the field of fire extinguishing technology and discloses a rapid-response fire extinguishing disc and its preparation process. The disc comprises strontium nitrate powder, dicyandiamide powder, ammonium heptamolybdate tetrahydrate powder, basic zinc carbonate powder, and a reactive crosslinking binder. The preparation process involves first reacting anhydrous ethanol, alcohol-soluble thermosetting phenolic resin, industrial-grade boric acid powder, and glacial acetic acid to obtain the reactive crosslinking binder. This binder is then sequentially kneaded with ammonium heptamolybdate tetrahydrate powder, basic zinc carbonate powder, strontium nitrate powder, and dicyandiamide powder to obtain a wet soft material. After granulation and drying using a stepped hot air drying program, it undergoes a two-stage gradient pressure holding and molding process for demolding. This invention utilizes the synergistic catalytic effect of ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder to shorten the ignition delay time and reduce burning rate fluctuations. Simultaneously, the reactive crosslinking binder crosslinks to form a network skeleton, giving the fire extinguishing disc compressive strength and heat resistance integrity, overcoming combustion collapse defects, and stabilizing gas generation.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing technology, specifically to a rapid-response fire extinguishing disc and its manufacturing process. Background Technology

[0002] Solid gas-generating fire extinguishing discs typically use agents that undergo an oxidation-reduction reaction upon ignition or heating, releasing gaseous products and solid extinguishing active particles—a multiphase extinguishing medium—to achieve cooling, dilution, and inhibition of the combustion chain reaction, thus creating a demand for firefighting applications. However, existing solid gas-generating fire extinguishing systems still exhibit response lag during the ignition and initiation phase, and the burning rate fluctuates during combustion.

[0003] In terms of molding, conventional binders added to traditional formulations undergo thermal degradation and failure during high-temperature combustion, resulting in a lack of compressive strength and heat resistance integrity in the molded body during combustion. This insufficient structural strength can cause the molded body to collapse or break apart under the impact of combustion gas flow, compromising the gas evolution stability of the extinguishing agent during combustion.

[0004] In existing manufacturing processes for solid gas-generating fire extinguishing propellants, the setup of the manufacturing process directly affects their molding structure and macroscopic properties. Traditional mixing and kneading processes typically involve mixing all powder raw materials and binders in a single step, resulting in uneven distribution of the catalytic components within the propellant and hindering their full catalytic activity at the interface between the bonding skeleton and the combustion zone. Simultaneously, during the tableting stage, the conventional single-pressing process traps gas within the gaps between material particles, generating internal residual stress. This residual stress can cause delamination defects in the tablets during unpressing and demolding, and the enclosed gas pores alter the reaction kinetics of the tablets at different combustion cross-sections, leading to unstable combustion reactions.

[0005] Furthermore, the main gas-generating system releases a large amount of heat during redox reactions. Existing reaction systems lack an effective balance between exothermic and endothermic processes, and excessively high local combustion temperatures can cause the molded body to crack due to heat. In the material drying process, conventional constant-temperature hot air drying causes rapid crusting on the surface of material particles, blocking the channels for moisture diffusion and making it difficult to completely remove internal moisture and volatiles. Residual internal moisture can cause deliquescence and degradation of the extinguishing agent during long-term storage. Therefore, developing a fire extinguishing pad with both rapid response capability and stable combustion structure, and reliable performance during preparation and storage, along with its preparation process, is a problem that needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a rapid-response fire extinguishing pad and its preparation process, which solves the problems of delayed response during the ignition stage, lack of structural strength during high-temperature combustion leading to collapse and cracking, and residual stress delamination and moisture decomposition failure during molding and storage of existing solid gas-generating fire extinguishing agents.

[0007] To address the above problems, the present invention provides the following technical solution: The first aspect of this invention provides a fast-response fire extinguishing disc, which adopts the following technical solution: A fast-response fire extinguishing disc comprises the following raw materials in parts by weight: Strontium nitrate powder: 50-60 parts; Dicyandiamide powder: 15-25 parts; Ammonium heptamolybdate tetrahydrate powder: 5.03–9.58 parts; Basic zinc carbonate powder: 3.47–5.42 parts; Reactive crosslinking adhesive: formed by pre-mixing and reacting 8-15 parts anhydrous ethanol, 4-8 parts alcohol-soluble thermosetting methyl phenolic resin, 0.4-1.2 parts industrial grade boric acid powder with glacial acetic acid, wherein the amount of glacial acetic acid satisfies the requirement that the pH value of the extract of the reactive crosslinking adhesive, as determined by water extraction, is 4.5-5.0.

[0008] By adopting the above technical solution, since the main gas generation system is constructed using the strontium nitrate powder and the dicyandiamide powder, and the ammonium heptamolybdate tetrahydrate powder and the basic zinc carbonate powder are combined to form a metal composite catalyst, a molybdenum-zinc synergistic catalytic effect is generated during combustion, which significantly shortens the ignition delay time and reduces the combustion rate fluctuation. In the pre-mixed reactive crosslinking adhesive, the alcohol-soluble thermosetting methyl phenolic resin forms a three-dimensional network framework under the crosslinking action of the industrial-grade boric acid powder. The glacial acetic acid adjusts the pH of the mixture to 4.5–5.0, providing a suitable slightly acidic catalytic environment for the crosslinking reaction and avoiding the risk of resin degradation due to excessive alkalinity or spontaneous combustion of the main gas-generating system due to excessive acidity. Due to the use of the above formula and the pre-crosslinked reactive crosslinking adhesive, the rapid-response fire extinguishing pad maintains a significant combustion response speed while also possessing compressive strength and thermal integrity, overcoming the technical defects of combustion collapse and achieving a stable gas generation effect.

[0009] Preferably, the ratio of the total molar amount of Mo to the total molar amount of Zn in the mixture of ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder is (0.9-1.1):1.

[0010] By adopting the above technical solution, Mo is used to promote the initiation of the redox reaction to improve responsiveness, while Zn undergoes endothermic decomposition at high temperatures to suppress excessively high local combustion temperatures. By controlling the ratio of total Mo molar content to total Zn molar content within the range of 0.9:1 to 1.1:1, the exothermic and endothermic processes of the reaction system are balanced. This molar ratio range achieves a synergistic effect of catalytic efficiency and temperature control, further improving the stability of the gas generation of the rapid-response fire extinguishing disc and avoiding fragmentation and explosion caused by local overheating.

[0011] A second aspect of this invention provides a manufacturing process for a rapid-response fire extinguishing disc, employing the following technical solution: A manufacturing process for a fast-response fire extinguishing disc includes the following steps: Anhydrous ethanol, alcohol-soluble thermosetting methyl phenolic resin, industrial-grade boric acid powder, and glacial acetic acid were mixed and reacted to obtain a reactive crosslinking adhesive liquid. The reactive crosslinking adhesive, ammonium heptamolybdate tetrahydrate powder, and basic zinc carbonate powder are kneaded together, followed by the addition of strontium nitrate powder and dicyandiamide powder and continued kneading to obtain a wet soft material. The wet soft material is subjected to wet coarse granulation, and then fed into a fluidized bed dryer with a stepped hot air drying program for drying. After cooling, the material is discharged to obtain granular material. The granular material is added into the mold cavity of a servo tablet press, and subjected to two-stage gradient pressure holding and stamping, followed by unstamping and demolding to obtain the fast-response fire extinguishing tablet.

[0012] By adopting the above technical solution, and through the step-by-step implementation of premixing, kneading, stepped hot air drying, and two-stage gradient pressure holding and stamping processes, the raw material components are evenly distributed. The premixed reactive crosslinking binder can coat the powder surface; Wet coarse granulation and fluidized bed drying avoid powder segregation and component migration; The two-stage gradient pressure holding and stamping reduces the residual stress inside the granular material and increases the density, making the resulting fast-response fire extinguishing tablet react smoothly during combustion.

[0013] Preferably, the step of preparing the reactive crosslinking adhesive includes: The anhydrous ethanol is added to a reaction vessel equipped with a mechanical stirrer and a temperature control jacket, and the alcohol-soluble thermosetting methyl phenolic resin is added. The mechanical stirrer is turned on until the alcohol-soluble thermosetting methyl phenolic resin dissolves in the anhydrous ethanol to form an alcohol-soluble system. The industrial-grade boric acid powder is slowly added to the alcohol-soluble system inside the reactor equipped with a mechanical stirrer and a temperature control jacket; The glacial acetic acid was added dropwise, and the water extraction method was used to determine the concentration multiple times during the addition process. The jacketed circulating water heating system of the reactor equipped with mechanical stirring and temperature control jacket is turned on to raise the temperature, and the reaction is stirred at a constant temperature. After naturally cooling to room temperature, the material is discharged.

[0014] By employing the above technical solution, the alcohol-soluble thermosetting methyl phenolic resin is first dissolved, and then the industrial-grade boric acid powder and glacial acetic acid are added, allowing the crosslinking components to be uniformly dispersed in the alcohol-soluble system. Heating in a slightly acidic environment induces a preliminary reaction in the alcohol-soluble thermosetting methyl phenolic resin, increasing the initial tack of the reactive crosslinking adhesive, which is beneficial for the subsequent preparation of the wet soft material. Simultaneously, it retains active groups to form a skeleton during the stamping stage, avoiding resin precipitation due to over-reaction.

[0015] Preferably, in the step of preparing the reactive crosslinking adhesive, the process parameters are controlled as follows: The stirring speed of the mechanical stirrer is set to 100-150 rpm; Add the glacial acetic acid dropwise until the pH of the extract, as determined by the water extraction method, stabilizes at 4.5–5.0; Heat to 50-55℃ and stir at a constant temperature of 50-55℃ for 30-40 minutes.

[0016] By adopting the above technical solution, setting the stirring speed to 100-150 rpm provides mass transfer conditions and prevents uneven cross-linking caused by local high concentrations of the industrial-grade boric acid powder. The temperature was raised to 50–55°C and the mixture was stirred at a constant temperature of 50–55°C for 30–40 minutes to control the degree of reaction, so that the prepared reactive crosslinking adhesive liquid had suitable rheological properties.

[0017] Preferably, the kneading step for obtaining the wet soft material includes: The reactive crosslinking binder is pumped into a two-position kneader with forced water cooling. The ammonium heptamolybdate tetrahydrate powder and the basic zinc carbonate powder are added. The two-position kneader with forced water cooling is started, and the material temperature is kept below 40°C. High shear kneading is performed at a speed of 30-50 rpm for 20-30 minutes. The strontium nitrate powder and the dicyandiamide powder are added sequentially to the two-position kneader equipped with forced water cooling, and the kneading is continued at a speed of 30-50 rpm for 40-50 minutes until the material is in the form of a wet soft material.

[0018] By adopting the above technical solution and employing a step-by-step kneading process, the ammonium heptamolybdate tetrahydrate powder and the basic zinc carbonate powder are added to the reactive crosslinking binder, allowing them to be wetted and coated by the reactive crosslinking binder. Subsequently, the strontium nitrate powder and the dicyandiamide powder are mixed in. This coating method allows the catalytic components to be distributed close to the resin skeleton, improving the catalytic activity at the combustion interface. Forced water cooling keeps the material temperature below 40°C, inhibiting the volatilization of the anhydrous ethanol and preventing premature reactions caused by heat generation during kneading.

[0019] Preferably, the total amount of the ammonium heptamolybdate tetrahydrate powder and the basic zinc carbonate powder added is 8.5 to 15 parts.

[0020] By adopting the above technical solution, the catalytic efficiency and the strength of the molded part skeleton are balanced. When the total addition amount is less than 8.5 parts, there are insufficient catalytic active sites, resulting in a slower ignition response of the fire extinguishing plate. When the amount exceeds 15 parts, the excessive inorganic salt particles will destroy the linkage structure of the alcohol-soluble thermosetting methyl phenolic resin, causing a significant decrease in the physical strength of the rapid-response fire extinguishing pad.

[0021] Preferably, the stepped hot air drying process includes: In the first stage, the inlet air temperature of the fluidized bed dryer is set to 40-45°C and maintained for 30-40 minutes. In the second stage, the inlet air temperature of the fluidized bed dryer is raised to 75-85°C and maintained for 20-30 minutes until the moisture and volatile matter content of the particulate material drops to ≤0.5%, and then the material is discharged after cold air fluidization.

[0022] By adopting the above technical solution, stepped hot air drying reduces the crusting phenomenon on the particle surface. The inlet air temperature of 40-45°C removes the residual anhydrous ethanol on the surface of the particulate material, maintaining the unobstructed flow of the internal outward diffusion channels; An inlet air temperature of 75–85°C drives internal moisture to migrate outward. By controlling the moisture and volatile matter content of the granular material to ≤0.5%, the deliquescence and inactivation of the agent caused by moisture during storage are avoided.

[0023] Preferably, the two-stage gradient pressure holding stamping includes a pre-pressing stage and a main pressure stage, wherein the pre-pressing stage applies a pressure of 5 to 8 MPa and holds the pressure for 1 to 2 seconds.

[0024] By adopting the above technical solution, the pre-compression section applies a pressure of 5-8 MPa and a pressure holding operation of 1-2 seconds, which can discharge the gas in the gap between the granular materials, avoid air sealing caused by stamping and internal stress concentration, and prevent delamination defects during demolding.

[0025] Preferably, the main pressure section continues to apply a pressure of 25-30 MPa, and performs a constant pressure holding operation for 3-5 seconds at the maximum stroke of the servo tablet press.

[0026] By employing the above technical solution, the main pressure section applies a pressure of 25–30 MPa, causing the material particles to undergo plastic deformation and bond together. The constant pressure holding operation for 3–5 seconds further compresses and adheres the resin network at the particle interface, improving the mechanical strength after molding. The resulting rapid-response fire extinguishing disc exhibits high density, which is beneficial for maintaining a stable gas generation rate.

[0027] This invention provides a fast-response fire extinguishing disc and its manufacturing process. It has the following beneficial effects: 1. This invention utilizes strontium nitrate powder and dicyandiamide powder in combination with ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder to generate a molybdenum-zinc synergistic catalytic effect during combustion, thereby shortening the ignition delay time and reducing combustion rate fluctuations. Simultaneously, a reactive crosslinking binder is used, which is formed by pre-mixing and reacting anhydrous ethanol, alcohol-soluble thermosetting methyl phenolic resin, industrial-grade boric acid powder, and glacial acetic acid, and the pH value of the extract is limited by water extraction. This allows the alcohol-soluble thermosetting methyl phenolic resin to crosslink and form a network skeleton in a slightly acidic environment. As a result, the prepared rapid-response fire extinguishing disc maintains the combustion response speed while possessing compressive strength and heat resistance integrity, overcoming the defects of combustion collapse and achieving stable gas generation.

[0028] 2. This invention employs a stepwise feeding process, in which reactive cross-linking binder, ammonium heptamolybdate tetrahydrate powder, and basic zinc carbonate powder are kneaded together, followed by the addition of strontium nitrate powder and dicyandiamide powder for further kneading. This process ensures that the catalytic components are coated by the reactive cross-linking binder and distributed close to the resin skeleton, thereby enhancing the catalytic activity at the combustion interface. Furthermore, the particulate material is added to the mold cavity of a servo tablet press for a two-stage gradient pressure holding and stamping process, including a pre-pressing section and a main pressing section. This process removes gas from the gaps between the particles and reduces internal residual stress, thereby improving the molding density and preventing delamination defects during unpressing and demolding. This ensures that the rapid-response fire extinguishing tablet reacts stably across all combustion sections.

[0029] 3. This invention limits the ratio of total molar amount of Mo to total molar amount of Zn in the mixture of ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder. By utilizing the combination of Mo promoting the initiation of the reaction and Zn's endothermic decomposition, the exothermic and endothermic processes of the reaction system are balanced to avoid fragmentation and cracking caused by local overheating. In the preparation process, a stepped hot air drying program is set in a fluidized bed dryer for drying. The staged heating keeps the internal diffusion channels open and drives the internal moisture to migrate outward, thereby controlling the moisture and volatile content of the particulate material and avoiding the deliquescence and failure of the agent caused by moisture during storage. Attached Figure Description

[0030] Figure 1 This is a comparison of the infrared spectra of combustion residues in the test examples of this invention; Figure 2 This is a power spectrum of internal pressure fluctuations during the combustion injection process in the test example of this invention; Figure 3 This is the logarithmic amplitude spectrum of the flame radiation pulsation signal in the test example of this invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Preparation Examples 1-3: Preparation Example 1: This preparation example provides a reactive crosslinking adhesive for fire extinguishing discs, comprising the following steps: Eight parts of anhydrous ethanol were added to a reaction vessel equipped with a mechanical stirrer and a temperature control jacket. Then, four parts of alcohol-soluble thermosetting methyl phenolic resin were added. The mechanical stirrer was turned on and set to a stirring speed of 100 rpm. The stirring was continued until the resin was completely dissolved in the anhydrous ethanol to form a homogeneous alcohol-soluble system.

[0033] While maintaining the above stirring state, slowly add 0.4 parts of industrial-grade boric acid powder to the alcohol-soluble system in the reactor to make the solid boric acid uniformly dispersed in the mixture.

[0034] The apparent acidity was adjusted by adding a trace amount of glacial acetic acid dropwise to the system using a dropping funnel. Multiple samples were taken during the addition process, and the pH of the extract was determined using a water extraction method until the pH of the extract stabilized at 4.5. The jacketed circulating water heating system of the reactor was then activated to raise the temperature of the material inside the reactor to 50°C. The mixture was then stirred and reacted at this temperature for 30 minutes. After naturally cooling to room temperature, the material was discharged, yielding the reactive crosslinking adhesive liquid.

[0035] Preparation Example 2: This preparation example provides a reactive crosslinking adhesive for fire extinguishing discs, comprising the following steps: 12 parts of anhydrous ethanol were added to a reaction vessel equipped with a mechanical stirrer and a temperature control jacket. Then, 6 parts of alcohol-soluble thermosetting methyl phenolic resin were added. The mechanical stirrer was turned on and the stirring speed was set to 125 rpm. The stirring was continued until the resin was completely dissolved in the anhydrous ethanol to form a homogeneous alcohol-soluble system.

[0036] While maintaining the above stirring state, slowly add 0.75 parts of industrial-grade boric acid powder to the alcohol-soluble system in the reactor to make the solid boric acid uniformly dispersed in the mixture.

[0037] The apparent acidity was adjusted by adding a trace amount of glacial acetic acid dropwise to the system using a dropping funnel. Multiple samples were taken during the addition process, and the pH of the extract was determined using a water extraction method until the pH of the extract stabilized at 4.8. The jacketed circulating water heating system of the reactor was then activated to raise the temperature of the material inside the reactor to 52°C. The mixture was then stirred and reacted at this temperature for 35 minutes. After naturally cooling to room temperature, the material was discharged, yielding the reactive crosslinking adhesive liquid.

[0038] Preparation Example 3: This preparation example provides a reactive crosslinking adhesive for fire extinguishing discs, comprising the following steps: Add 15 parts of anhydrous ethanol to a reaction vessel equipped with a mechanical stirrer and a temperature control jacket, then add 8 parts of alcohol-soluble thermosetting methyl phenolic resin, turn on the mechanical stirrer, set the stirring speed to 150 rpm, and continue stirring until the resin is completely dissolved in the anhydrous ethanol to form a homogeneous alcohol-soluble system.

[0039] While maintaining the above stirring state, slowly add 1.2 parts of industrial-grade boric acid powder to the alcohol-soluble system in the reactor to make the solid boric acid uniformly dispersed in the mixture.

[0040] The apparent acidity was adjusted by adding a trace amount of glacial acetic acid dropwise to the system using a dropping funnel. Multiple samples were taken during the addition process, and the pH of the extract was determined using a water extraction method until the pH of the extract stabilized at 5.0. The jacketed circulating water heating system of the reactor was then activated to raise the temperature of the material inside the reactor to 55°C. The mixture was then stirred and reacted at this temperature for 40 minutes. After naturally cooling to room temperature, the material was discharged, yielding the reactive cross-linking adhesive liquid.

[0041] Examples 1-3: Example 1:

[0042] This embodiment provides a manufacturing process for a fast-response fire extinguishing disc, including the following steps: The reactive crosslinking adhesive prepared in Example 1 was pumped into a two-position kneader with forced water cooling. Then, 5.03 parts of ammonium heptamolybdate tetrahydrate powder and 3.47 parts of basic zinc carbonate powder were added, and the total amount of both was controlled to be 8.5 parts. At this time, the ratio of the total molar amount of Mo to the total molar amount of Zn in the mixture was 0.9:1. The kneader was started, and the material temperature was kept below 40°C. High shear kneading was performed at a speed of 30 rpm for 20 minutes. Add 50 parts of strontium nitrate powder and 15 parts of dicyandiamide powder to the kneader in sequence, and continue kneading at the same speed for 40 minutes until the material is a uniform wet soft material. The obtained wet soft material is wet coarsely granulated by a gyratory pellet mill, and then fed into a fluidized bed dryer. A stepped hot air drying program is set for drying. In the first stage, the inlet air temperature is set to 40℃ and maintained for 30 minutes. In the second stage, the inlet air temperature is raised to 75℃ and maintained for 20 minutes until the moisture and volatile matter content of the particles are reduced to ≤0.5%. The material is then discharged after cold air fluidization. The dried granular material is added into the mold cavity of the servo tablet press and subjected to two-stage gradient pressure holding and punching. The pre-compression stage applies a pressure of 5MPa and holds the pressure for 1 second to expel air from the gaps between the granules. The main compression stage continues to apply a high pressure of 25MPa and performs a constant pressure holding operation for 3 seconds at the maximum stroke. The press is then unpressed and demolded to obtain a macroscopically dense fire extinguishing tablet.

[0043] Example 2:

[0044] This embodiment provides a manufacturing process for a fast-response fire extinguishing disc, including the following steps: The reactive crosslinking adhesive liquid prepared in Example 2 was pumped into a two-position kneader with forced water cooling. Then, 7.40 parts of ammonium heptamolybdate tetrahydrate powder and 4.60 parts of basic zinc carbonate powder were added, and the total amount of both was controlled to be 12 parts. At this time, the ratio of the total molar amount of Mo to the total molar amount of Zn in the mixture was 1:1. The kneader was started, and the material temperature was kept below 40°C. High shear kneading was performed at a speed of 40 rpm for 25 minutes. Add 55 parts of strontium nitrate powder and 20 parts of dicyandiamide powder to the kneader in sequence, and continue kneading at the same speed for 45 minutes until the material is a uniform wet soft material. The obtained wet soft material is wet coarsely granulated by a gyratory pellet mill, and then fed into a fluidized bed dryer. A stepped hot air drying program is set for drying. In the first stage, the inlet air temperature is set to 42℃ and maintained for 35 minutes. In the second stage, the inlet air temperature is raised to 80℃ and maintained for 25 minutes until the moisture and volatile matter content of the particles are reduced to ≤0.5%. The material is then discharged after cold air fluidization. The dried granular material is added into the mold cavity of the servo tablet press and subjected to two-stage gradient pressure holding and punching. The pre-compression stage applies a pressure of 6MPa and holds the pressure for 1.5 seconds to expel air from the gaps between the granules. The main compression stage continues to apply a high pressure of 28MPa and performs a constant pressure holding operation for 4 seconds at the maximum stroke. After unloading and demolding, a macroscopically dense fire extinguishing tablet is obtained.

[0045] Example 3:

[0046] This embodiment provides a manufacturing process for a fast-response fire extinguishing disc, including the following steps: The reactive crosslinking adhesive liquid prepared in Preparation Example 3 was pumped into a two-position kneader with forced water cooling. Then, 9.58 parts of ammonium heptamolybdate tetrahydrate powder and 5.42 parts of basic zinc carbonate powder were added, and the total amount of both was controlled to be 15 parts. At this time, the ratio of the total molar amount of Mo to the total molar amount of Zn in the mixture was 1.1:1. The kneader was started, and the material temperature was kept below 40°C. High shear kneading was performed at a speed of 50 rpm for 30 minutes. Add 60 parts of strontium nitrate powder and 25 parts of dicyandiamide powder to the kneader in sequence, and continue kneading at the same speed for 50 minutes until the material is a uniform wet soft material. The obtained wet soft material is wet coarsely granulated by a gyratory pellet mill, and then fed into a fluidized bed dryer. A stepped hot air drying program is set for drying. In the first stage, the inlet air temperature is set to 45℃ and maintained for 40 minutes. In the second stage, the inlet air temperature is raised to 85℃ and maintained for 30 minutes until the moisture and volatile matter content of the particles are reduced to ≤0.5%. The material is then discharged after being cooled by cold air fluidization. The dried granular material is added into the mold cavity of the servo tablet press and subjected to two-stage gradient pressure holding and punching. The pre-compression stage applies a pressure of 8MPa and holds the pressure for 2 seconds to expel air from the gaps between the granules. The main compression stage continues to apply a high pressure of 30MPa and performs a constant pressure holding operation for 5 seconds at the maximum stroke. The press is then unpressed and demolded to obtain a macroscopically dense fire extinguishing tablet.

[0047] Comparative Examples 1-4: Comparative Example 1: Compared with Example 2, the difference is that ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder were not added, and the missing parts were compensated by weight of the oxidant and reducing agent in equal proportion. That is, the strontium nitrate powder added to the kneader was adjusted to 63.8 parts and the dicyandiamide powder was adjusted to 23.2 parts. All other parameters and steps are the same.

[0048] Comparative Example 2: Compared with Example 2, the difference is that when preparing the reactive crosslinking adhesive, no industrial-grade boric acid powder was added and no glacial acetic acid was added to adjust the apparent acidity. Instead, 6 parts of alcohol-soluble thermosetting methyl phenolic resin were dissolved in 12 parts of anhydrous ethanol to obtain a pure resin solution to replace the original reactive crosslinking adhesive. All other parameters and steps are the same.

[0049] Comparative Example 3: Compared with Example 2, the difference is that the stoichiometric matching constraint was broken. Four parts of ammonium heptamolybdate tetrahydrate powder and eight parts of basic zinc carbonate powder were added to the kneader. At this time, the ratio of the total molar amount of Mo to the total molar amount of Zn in the mixed system deviated to 0.45:1. All other parameters and steps were the same.

[0050] Comparative Example 4: Compared to Example 2, the difference lies in that the reactive crosslinking binder was not prepared separately and the step drying and gradient tableting process was not used. Instead, the corresponding weight parts of ammonium heptamolybdate tetrahydrate, basic zinc carbonate, strontium nitrate, dicyandiamide, and dry powdered methyl phenolic resin and boric acid were directly placed into a high-speed mixer and dry-mixed evenly. Then, 12 parts of anhydrous ethanol were sprayed on to wet and form a soft material. The fluidized bed drying stage was changed to direct single-stage high-temperature drying with 80°C hot air until the moisture content was ≤0.5%. The pre-compression and degassing section was eliminated in the tableting process; instead, 28 MPa was directly applied for single-pass stamping. All other parameters and steps remained the same.

[0051] Test Example 1-3: Test Example 1: Macroscopic Morphology and Porosity Assessment of Combustion Residue Experimental description: This test case was used to verify the effectiveness of the formulation system in preventing the continuous sintering of strontium-containing residues. By evaluating the macroscopic volume expansion rate of the combustion residue and the peak resistance of the penetration probe, the degree of high-temperature densification and molten slagging of the residue was visually reflected.

[0052] Experimental steps: Equal masses of fire extinguishing disc samples prepared in each embodiment and comparative example were weighed out, and the samples were fixed inside a standard open combustion fixture. An electric pulse ignition signal was used to trigger the ignition signal to make it burn completely. After the combustion is over and the residue has cooled to room temperature, carefully collect the complete residue clumps on the base. The apparent volume of each group of residues was determined using the sand removal method, and the proportion of macroscopic apparent volume was calculated in combination with the initial volume of the sample. A digital push-pull force gauge with a cylindrical flat-bottomed probe was used to conduct multiple uniform-speed penetration tests at different positions on the cross-section of the residue, and the peak resistance during the probe penetration process was recorded. Small amounts of internal residue from each embodiment and comparative example were ground into powder and subjected to infrared spectroscopy scanning tests using the potassium bromide tableting method.

[0053] Experimental data: Table 1. Test data of macroscopic physical properties of combustion residue Experimental conclusion: As can be seen from the test data in Table 1, the apparent volume ratio of the combustion residues in Examples 1 to 3 increased significantly, the peak resistance of the penetration probe remained at a low level, and the combustion products exhibited a loose and porous morphology. The residues in Comparative Examples 1 to 4 showed varying degrees of volume shrinkage, higher penetration resistance, and exhibited dense, glassy sintering characteristics. This indicates that, under stoichiometric matching and the action of a boron-oxygen fluxing phase, a high-melting-point zinc molybdate multiphase microcrystalline framework can be synthesized in situ, suppressing high-temperature shrinkage and densification.

[0054] See attached document Figure 1 The spectral curves of Examples 1 to 3 at a wavenumber of 950 cm⁻¹ -1 Up to 800cm -1 Distinct characteristic vibrational absorption peaks appeared within the range, corresponding to the bridging bonding structure within the zinc molybdate lattice. Comparative Example 1 showed a smooth, continuous absorption band, exhibiting characteristics of amorphous glassy slag; Comparative Examples 2 and 4 showed weakened characteristic bridging peaks due to component segregation; Comparative Example 3 showed almost no absorption peaks due to component imbalance. The in-situ generated microcrystalline framework disrupted the continuous sintering structure between residues, undermining the basis for residue volume shrinkage and ensuring unobstructed jet channels during the release phase.

[0055] Test Example 2: Test of Nozzle Clogging Rate and Peak Internal Pressure of Fire Extinguishing Device Experimental description: This test case is used to evaluate the smoothness and safety of the release of extinguishing media when the formulation is burning within a closed fire extinguishing device. By monitoring the dynamic pressure changes and effective mass ejection rate inside the device, it reflects the degree of blockage of the ejection orifice by combustion residue and the risk of abnormal overpressure.

[0056] Experimental steps: The samples of each embodiment and comparative example were accurately weighed and filled into a standard stainless steel sealed test fixture with a fixed internal volume. A standard-diameter sizing nozzle is installed on the top of the test fixture, and a high-frequency dynamic pressure sensor is rigidly connected to a pre-set hole on the side wall. The ignition signal is triggered by an electrical pulse, and the high-frequency data acquisition system is simultaneously started to record the dynamic pressure data of the entire combustion injection process. After the eruption ends and the tooling cools down naturally, the solid particles ejected into the collection chamber and the bottom slag remaining inside the tooling are collected, weighed, and the effective mass ejection rate is calculated based on the initial mass of the sample.

[0057] Experimental data: Table 2. Test Data of Combustion Emission Performance of Closed Fire Extinguishing Devices Experimental conclusion: As can be seen from the test data in Table 2, the effective mass ejection rate of Examples 1 to 3 remained above 95%, and the maximum internal peak pressure was at a low level, indicating that the combustion products could be smoothly released within the sealed fixture. Comparative Examples 1 to 4 showed a significant decrease in effective mass ejection rate and an abnormally high internal peak pressure, confirming that the high-temperature molten slag blocked the ejection channel, leading to obstructed gas flow. The molybdenum and zinc sources in the formulation generated zinc molybdate microcrystalline phases in situ during combustion, interrupting the continuous melt at the mesoscale. The microcrystalline structure maintained the final residue in a loose and porous morphology, preventing the formation of dense agglomerates and ensuring the effective flow area of ​​the sizing nozzle.

[0058] See attached document Figure 2 The power spectrum of the internal pressure fluctuations in Example 2 is plotted as a solid line, while that of Comparative Example 1 is plotted as a dashed line. In Example 2, the pressure fluctuation energy is mainly concentrated in the low-frequency region. The solid line curve decreases steadily with increasing frequency and remains stable in the high-frequency range, indicating that the airflow channel remains unobstructed. In Comparative Example 1, the power spectrum shows obvious high-frequency broadband excitation peaks in the mid-to-high frequency range, with the dashed line curve exhibiting multiple energy jump peaks near 180Hz, 420Hz, and 750Hz. This corresponds to the internal deflagration impact triggered by the high-temperature dense residue blocking the channel, confirming from the perspective of frequency domain characteristics that the molybdenum-containing microcrystalline phase can prevent high-temperature slag blockage of the injection channel.

[0059] Test Example 3: Response Time and Fire Extinguishing Efficiency Test Experimental description: This test case is used to evaluate the fire suppression capability of extinguishing agents in a standard space. By recording the response delay time from triggering the ignition signal to agent release and the extinguishing time to completely extinguish a standard oil pan fire, the catalytic decomposition rate and continuous extinguishing efficiency of the formulation are reflected.

[0060] Experimental steps: The internal volume is 1m³ 3 A steel oil pan of specified dimensions is placed in the center of the standard sealed test chamber, and a fixed amount of n-heptane fuel and a water pad are added. The samples of each embodiment and comparative example were respectively loaded into a standard sizing injection fixture, fixed to the center of the top of the test chamber, and connected to an electric pulse triggering device and a high-speed camera system. Ignite the fuel in the fuel pan, pre-ignite for a certain period of time, then trigger an electrical pulse ignition signal, and record the response delay time from the issuance of the electrical signal to the large-scale release of the extinguishing medium from the nozzle; The flame radiation signal and temperature change are continuously monitored by photoelectric sensors and thermocouples installed in the test chamber, and the time required for the flame to be completely extinguished is counted as the extinguishing time. The flame radiation pulsation signal recorded by the photoelectric sensor in the test chamber was extracted, and Fourier transform processing was performed to obtain the logarithmic amplitude spectrum data of each group during the fire extinguishing response phase.

[0061] Experimental data: Table 3. Test Data on Space Fire Extinguishing Efficiency and Response Time Experimental conclusion: As can be seen from the test data in Table 3, the response delay time of Examples 1 to 3 was significantly shortened, and the extinguishing time remained at a low value. This indicates that the molybdenum source and other components added to the formulation increased the initial decomposition rate of the agent. Comparative Example 1 showed a longer response delay time and a significantly increased extinguishing time, reflecting a relatively sluggish initial reaction. The extinguishing times of Comparative Examples 2 to 4 were prolonged to varying degrees, confirming that high-temperature residue clogging the ejection channels leads to insufficient release of extinguishing particles, thereby weakening the overall extinguishing efficiency. The microcrystalline framework generated in the formulation inhibited the densification and shrinkage of the residue, ensuring that extinguishing particles continuously entered the fire scene and quickly interrupted the combustion chain reaction of the flame.

[0062] Combined with appendix Figure 3 The logarithmic amplitude spectrum of the flame radiation pulsation signal was analyzed. In the figure, the signal curve of Example 2 is plotted as a solid line, while the signal curve of Comparative Example 1 is plotted as a dashed line. During the extinguishing phase, the solid line curve of Example 2 showed a generally low amplitude level across all frequency bands. Its logarithmic amplitude decreased steadily with increasing frequency and tended to level off and stabilize within the frequency band above 100Hz, indicating that the extinguishing agent rapidly filled the test chamber and effectively suppressed the flame pulsation. The dashed line curve of Comparative Example 1 exhibited multiple distinct amplitude peaks within the 50Hz to 250Hz frequency band. This frequency domain characteristic indicates that the extinguishing agent's spray was obstructed due to channel blockage, the flame failed to extinguish quickly, and continuous turbulent combustion occurred on the oil pan surface. These data differences indirectly confirm the positive role of the molybdenum-containing microcrystalline phase in improving extinguishing efficiency and preventing channel slagging.

Claims

1. A rapid-response fire extinguishing disc, characterized in that, Raw materials comprising the following parts by weight: Strontium nitrate powder: 50-60 parts; Dicyandiamide powder: 15-25 parts; Ammonium heptamolybdate tetrahydrate powder: 5.03–9.58 parts; Basic zinc carbonate powder: 3.47–5.42 parts; Reactive crosslinking adhesive: formed by pre-mixing and reacting 8-15 parts anhydrous ethanol, 4-8 parts alcohol-soluble thermosetting methyl phenolic resin, 0.4-1.2 parts industrial grade boric acid powder with glacial acetic acid, wherein the amount of glacial acetic acid satisfies the requirement that the pH value of the extract of the reactive crosslinking adhesive, as determined by water extraction, is 4.5-5.

0.

2. The rapid-response fire extinguishing disc according to claim 1, characterized in that, The ratio of the total molar amount of Mo to the total molar amount of Zn in the mixture of ammonium heptamolybdate tetrahydrate powder and basic zinc carbonate powder is (0.9-1.1):

1.

3. A manufacturing process for a rapid-response fire extinguishing disc as described in claim 1 or 2, characterized in that, Includes the following steps: Anhydrous ethanol, alcohol-soluble thermosetting methyl phenolic resin, industrial-grade boric acid powder, and glacial acetic acid were mixed and reacted to obtain a reactive crosslinking adhesive liquid. The reactive crosslinking adhesive, ammonium heptamolybdate tetrahydrate powder, and basic zinc carbonate powder are kneaded together, followed by the addition of strontium nitrate powder and dicyandiamide powder and continued kneading to obtain a wet soft material. The wet soft material is subjected to wet coarse granulation, and then fed into a fluidized bed dryer with a stepped hot air drying program for drying. After cooling, the material is discharged to obtain granular material. The granular material is added into the mold cavity of a servo tablet press, and subjected to two-stage gradient pressure holding and stamping, followed by unstamping and demolding to obtain the fast-response fire extinguishing tablet.

4. The preparation process according to claim 3, characterized in that, The steps for preparing the reactive crosslinking adhesive include: The anhydrous ethanol is added to a reaction vessel equipped with a mechanical stirrer and a temperature control jacket, and the alcohol-soluble thermosetting methyl phenolic resin is added. The mechanical stirrer is turned on until the alcohol-soluble thermosetting methyl phenolic resin dissolves in the anhydrous ethanol to form an alcohol-soluble system. The industrial-grade boric acid powder is slowly added to the alcohol-soluble system inside the reactor equipped with a mechanical stirrer and a temperature control jacket; The glacial acetic acid was added dropwise, and the water extraction method was used to determine the concentration multiple times during the addition process. The jacketed circulating water heating system of the reactor equipped with mechanical stirring and temperature control jacket is turned on to raise the temperature, and the reaction is stirred at a constant temperature. After naturally cooling to room temperature, the material is discharged.

5. The preparation process according to claim 4, characterized in that, In the step of preparing the reactive crosslinking adhesive, the process parameters are controlled as follows: The stirring speed of the mechanical stirrer is set to 100-150 rpm; Add the glacial acetic acid dropwise until the pH of the extract, as determined by the water extraction method, stabilizes at 4.5–5.0; Heat to 50-55℃ and stir at a constant temperature of 50-55℃ for 30-40 minutes.

6. The preparation process according to claim 3, characterized in that, The kneading step for obtaining the wet soft material includes: The reactive crosslinking binder is pumped into a two-position kneader with forced water cooling. The ammonium heptamolybdate tetrahydrate powder and the basic zinc carbonate powder are added. The two-position kneader with forced water cooling is started, and the material temperature is kept below 40°C. High shear kneading is performed at a speed of 30-50 rpm for 20-30 minutes. The strontium nitrate powder and the dicyandiamide powder are added sequentially to the two-position kneader equipped with forced water cooling, and the kneading is continued at a speed of 30-50 rpm for 40-50 minutes until the material is in the form of a wet soft material.

7. The preparation process according to claim 6, characterized in that, The total amount of ammonium heptamolybdate tetrahydrate powder and zinc carbonate basic powder added is 8.5 to 15 parts.

8. The preparation process according to claim 3, characterized in that, The stepped hot air drying process includes: In the first stage, the inlet air temperature of the fluidized bed dryer is set to 40-45°C and maintained for 30-40 minutes. In the second stage, the inlet air temperature of the fluidized bed dryer is raised to 75-85°C and maintained for 20-30 minutes until the moisture and volatile matter content of the particulate material drops to ≤0.5%, and then the material is discharged after cold air fluidization.

9. The preparation process according to claim 3, characterized in that, The two-stage gradient pressure holding stamping includes a pre-pressing stage and a main pressure stage. The pre-pressing stage applies a pressure of 5 to 8 MPa and holds the pressure for 1 to 2 seconds.

10. The preparation process according to claim 9, characterized in that, The main pressure section continues to apply a pressure of 25-30 MPa, and performs a constant pressure holding operation for 3-5 seconds at the maximum stroke of the servo tablet press.

Images