Low-corrosion and low-temperature resistant marine water film forming foam extinguishing agent and preparation method thereof

Abstract

The application discloses a kind of low corrosion low temperature resistant ship water film forming foam extinguishing agent and preparation method thereof.The extinguishing agent is made of deionized water, 1,2-propanediol, sodium lignosulfonate, alkyl polyglycoside, polyether modified heptamethyltrisiloxane, sodium molybdate dihydrate, methyl benzotriazole, xanthan gum and triethanolamine.In the system, sodium molybdate dihydrate and sodium lignosulfonate are coordinated and crosslinked to form a three-dimensional skeleton under the buffer of triethanolamine, and the hydrophobic segment of the surfactant is intercalated and anchored in the hydrophobic microzone inside the skeleton.During preparation, 1,2-propanediol is used to pre-disperse polymer powder, the crosslinking rate is controlled by adding triethanolamine in batches, and the surfactant is added after the system is cooled to complete the cold intercalation.The application limits the self-aggregation and precipitation of surfactant at low temperature, avoids the problem of polymer water core and excessive crosslinking, maintains the stability of rheology, and effectively reduces the corrosion of ship metal equipment.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing materials technology, specifically to a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method. Background Technology

[0002] Aqueous film-forming foam (AFFO) is a commonly used extinguishing medium in ship firefighting systems. It primarily relies on forming a water film on the surface of fuel oil to isolate oxygen and inhibit the volatilization of flammable vapors. Existing extinguishing agent formulations typically require the compounding of multiple surfactants, polymers, and inorganic salts to meet the requirements for foaming, spreading, and stability.

[0003] However, conventional aqueous film-forming foam (AFCF) fire extinguishing agents face several mutually restrictive issues in practical application and preparation. Ships frequently operate in low-temperature sea conditions, where surfactants in the extinguishing agent are prone to molecular self-aggregation, leading to crystallization and phase separation. This directly affects the product's physical stability and actual fire extinguishing efficiency. Simultaneously, inorganic salt components used to assist foaming or antifreeze in the formulation are susceptible to charge transfer with the metal matrix during long-term storage and pipeline transportation, causing electrochemical corrosion of ship metal pipelines and storage tanks, increasing the maintenance costs of fire-fighting equipment.

[0004] Besides the limitations imposed by the usage environment, the manufacturing process of existing products also faces technological challenges. To impart suitable rheological properties to the extinguishing agent to ensure its adhesion, polymer powders are typically added to the formulation. When these polymer powders come into direct contact with the aqueous phase, their surfaces rapidly absorb water, forming a hydration layer that hinders further dissolution of the internal powder, resulting in undissolved particles encapsulated in powder clumps. Furthermore, in the process of introducing crosslinking agents to enhance the network structure strength, if the rate of the crosslinking reaction is not effectively controlled, localized over-crosslinking of polymer segments can easily occur. This instantaneous dead crosslinking generates insoluble gel particles, disrupting the homogeneity of the fluid system and deteriorating the shear-thinning properties of the finished product, making it difficult to form the required jet flow pattern when passing through the sprinkler heads of the fire protection system. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-corrosion, low-temperature resistant aqueous film-forming foam (AFCF) fire extinguishing agent for ships and its preparation method. This solves the problems of existing AFCF fire extinguishing agents where surfactants easily crystallize and precipitate at low temperatures, leading to phase separation, and the inorganic salt components causing corrosion to ship metal pipes. Furthermore, during the preparation process, the polymer molecules are prone to agglomeration, and the cross-linking reaction is difficult to control, often resulting in deterioration of rheological properties.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, wherein the fire extinguishing agent is made from components comprising the following parts by weight:

[0007] 34.9 to 53.6 parts of deionized water;

[0008] 35.0 to 45.0 parts of 1,2-propanediol;

[0009] Sodium lignosulfonate 5.0 to 9.0 parts;

[0010] Alkyl polysaccharide 4.0 to 6.0 parts;

[0011] 1.0 to 2.0 parts of polyether-modified heptamethyltrisiloxane;

[0012] Sodium molybdate dihydrate, 0.6 to 1.0 parts;

[0013] 0.2 to 0.5 parts of methylbenzotriazole;

[0014] Xanthan gum 0.3 to 0.8 parts;

[0015] Triethanolamine 0.3 to 0.8 parts;

[0016] The fire extinguishing agent has a three-dimensional cross-linked network skeleton structure inside. The three-dimensional cross-linked network skeleton is formed by the in-situ coordination and cross-linking of molybdate ions dissociated from sodium molybdate dihydrate and phenolic hydroxyl groups on the sodium lignin sulfonate molecular chain under the ligand replacement buffering effect of triethanolamine.

[0017] Hydrophobic segments of alkyl polysaccharides and polyether-modified heptamethyltrisiloxane are intercalated and anchored in hydrophobic microregions within a three-dimensional cross-linked network framework.

[0018] The extinguishing agent has a macroscopic initial cloud point of 68 degrees Celsius or greater at 20 degrees Celsius, and the ratio of its apparent viscosity at low shear rate to its apparent viscosity at high shear rate at 20 degrees Celsius is 11.92 to 13.97. The low shear rate is set to -1 second, and the high shear rate is set to -100 seconds.

[0019] By adopting the above technical solution, the molybdate ions dissociated from sodium molybdate dihydrate are used to perform in-situ coordination crosslinking with the phenolic hydroxyl groups on the sodium lignosulfonate molecular chain, and ligand substitution buffering is carried out with the participation of triethanolamine. At the same time, the hydrophobic segments of alkyl polysaccharide and polyether-modified heptamethyltrisiloxane are intercalated and anchored in the hydrophobic microregions of the crosslinking network, which effectively improves the physical stability and low-temperature resistance of the fire extinguishing agent and reduces the corrosivity of the system.

[0020] The construction of this structure mainly relies on polydentate coordination reactions in the aqueous system. Sodium molybdate dihydrate dissociates in water to generate molybdate ions. These ions, acting as central polyhedra, can react with the phenolic hydroxyl groups in the sodium lignosulfonate molecule to build the initial coordination compound framework.

[0021] To prevent the formation of insoluble gel particles from localized, transient cross-linking of polymer segments, triethanolamine was introduced into the system for regulation. Containing both hydroxyl and amino groups, triethanolamine can form transient complexes with molybdate ions, preferentially occupying coordination sites in the early stages of the reaction. As the reaction progresses, the phenolic hydroxyl groups of sodium lignosulfonate gradually replace triethanolamine through a ligand substitution mechanism. This competitive ligand substitution process effectively slows down the cross-linking rate, maintaining the apparent viscosity ratio of the cross-linked system between 11.92 and 13.97 under low and high shear conditions, thus forming a fluid network with stable shear-thinning properties.

[0022] Once the three-dimensional cross-linked network solidifies, localized hydrophobic microregions naturally form within it. As a nonionic surfactant, the hydrophobic carbon segments of alkyl polysaccharides and polyether-modified heptamethyltrisiloxane can be physically anchored within these microregions through non-covalent bonding. This spatial confinement prevents the self-aggregation of surfactant molecules under low-temperature conditions, raising the system's initial macroscopic cloud point to above 68 degrees Celsius, thus preventing crystallization. Simultaneously, free molybdate ions and methylbenzotriazole synergistically form a passivation film on the metal surface, hindering charge transfer and fundamentally reducing the corrosion rate of the fire extinguishing agent on metal equipment.

[0023] Preferably, the extinguishing agent is made from the following components in parts by weight: 43.0 parts deionized water, 40.0 parts 1,2-propanediol, 7.0 parts sodium lignosulfonate, 6.0 parts alkyl polysaccharide, 2.0 parts polyether-modified heptamethyltrisiloxane, 0.8 parts sodium molybdate dihydrate, 0.2 parts methylbenzotriazole, 0.5 parts xanthan gum, and 0.5 parts triethanolamine.

[0024] By adopting the above technical solution, the skeleton density of the cross-linked network and the solubilization amount of the surfactant can be better balanced, ensuring that the extinguishing agent maintains suitable rheological properties while taking into account foaming and spreading performance.

[0025] Preferably, sodium lignosulfonate is an anionic polymer compound with a weight-average molecular weight of 5,000 to 10,000 and a sulfonic acid group content of 1.0 to 2.5 mmol / g; and alkyl polysaccharide is a nonionic surfactant with an alkyl carbon chain length distribution of C8 to C10 and an average degree of polymerization of 1.3 to 1.5.

[0026] By adopting the above technical solution, sodium lignosulfonate with a specific molecular weight is used to make the molecular chain have a suitable extension state in the aqueous phase, making it easier to expose the phenolic hydroxyl groups that participate in coordination; combined with alkyl polysaccharides with specific carbon chain length and degree of polymerization, it is made to match the size of the hydrophobic microregions of the cross-linked network, so as to achieve stable intercalation at the spatial structure level.

[0027] Preferably, the polyether-modified heptamethyltrisiloxane is a polymer obtained by hydrosilylation reaction of terminal allyl polyether and 1,1,1,3,5,5,5-heptamethyltrisiloxane at 80 to 100 degrees Celsius under the catalysis of chloroplatinic acid hexahydrate; wherein the weight average molecular weight of the terminal allyl polyether is 600.

[0028] By adopting the above technical solution, the ratio of siloxane backbone to polyether side chain in polyether-modified heptamethyltrisiloxane was strictly controlled. This allows its hydrophilic-lipophilic balance value to synergistically interact with other components in the system, further improving the foam's spreading coefficient on non-polar fuel surfaces.

[0029] Secondly, this invention provides a method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships, employing the following technical solution:

[0030] A method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships includes the following steps:

[0031] Step 1: In a premixing vessel, 1,2-propanediol, xanthan gum and sodium lignosulfonate are mixed and stirred to obtain a uniform multiphase suspension dispersion;

[0032] Step 2: Add deionized water to the main reactor, turn on the heating and keep it at a constant temperature, then add sodium molybdate dihydrate and the pre-prepared triethanolamine in sequence, and stir at a constant temperature.

[0033] Step 3: Keep the temperature of the main reactor constant and increase the stirring speed. Continuously pump the suspension dispersion obtained in step 1 into the main reactor. After the feeding is completed, continue stirring at a constant temperature to build a cross-linked network.

[0034] Step 4, Cooling: Cool the material in the main reactor. When the temperature drops to 30 to 35 degrees Celsius, slowly add alkyl polysaccharide, polyether-modified heptamethyltrisiloxane, methylbenzotriazole and triethanolamine in the later part in sequence, while slowing down the stirring and continuing to stir, to complete the cold intercalation of the surfactant.

[0035] Step 5: Filter and purify the fluid obtained in Step 4, and then fill it in a sealed container to obtain the final product.

[0036] By adopting the above technical solution, the different reaction stages are physically separated through a multi-step feeding process, which solves the problem of powder agglomeration and also achieves precise control over the crosslinking reaction rate and surfactant state.

[0037] At the operational level, xanthan gum and sodium lignosulfonate powder are first pre-dispersed using the non-aqueous polar solvent 1,2-propanediol.

[0038] Since the swelling rate of the polymer in 1,2-propanediol is much lower than that in pure water, this prevents water molecules from instantly contacting the powder surface to form an outer hydration gel film, thus avoiding the core-encapsulation phenomenon that easily occurs when the polymer comes into contact with water, laying the foundation for uniform dispersion in the aqueous phase.

[0039] Subsequently, during the construction of the crosslinking network, some triethanolamine was added to the main reactor in advance.

[0040] Upon dissolution, the crosslinking agent immediately forms a buffer complex, creating a coordination competition environment. Subsequently, during the continuous pumping of the suspension dispersion, by controlling the concentration gradient of the feed, the ligand replacement reaction is ensured to proceed in a dilute solution state, thus preventing the accumulation of network nodes caused by excessively high local concentrations.

[0041] To address the problem of surfactant demulsification in conventional processes, this solution employs a cooling cold intercalation process.

[0042] The surfactant is added only when the system temperature drops to 30 to 35 degrees Celsius, at which point the cross-linked network has essentially been fixed. The lower temperature environment weakens the thermal kinetic energy of the surfactant molecules, prompting them to spontaneously enter the pre-formed hydrophobic microdomains to complete intercalation through interfacial forces, thus completely avoiding the phase separation phenomenon that easily occurs at high temperatures.

[0043] Preferably, in step 1, 1,2-propanediol is added to a premixing vessel at room temperature of 20 to 25 degrees Celsius, the stirring speed is set to 60 to 80 revolutions per minute, xanthan gum and sodium lignosulfonate are slowly and evenly sprinkled in, and stirring is maintained for 15 to 20 minutes.

[0044] By adopting the above technical solution, maintaining low-speed shear and room temperature environment during the premixing stage is mainly to prevent local solvent evaporation caused by mechanical friction heating and to maintain the stability of the solid-liquid ratio of the suspension.

[0045] Preferably, in step 2, the system in the main reactor is kept at a constant temperature of 45 to 48 degrees Celsius, the stirring speed is set to 100 to 120 revolutions per minute, and the system is stirred at a constant temperature for 15 to 20 minutes.

[0046] In step 3, maintain the temperature of the main reactor at 45 to 48 degrees Celsius, increase the rotation speed to 150 to 200 revolutions per minute, control the total pumping time of the suspension dispersion to 20 to 30 minutes using a constant flow metering pump, and continue constant temperature stirring for 20 to 30 minutes after the feeding is completed.

[0047] By employing the above technical solution, a temperature range of 45 to 48 degrees Celsius provides the basic energy required for coordination bond formation. Furthermore, by increasing the rotation speed to enhance convective mass transfer, the added polymer suspension is rapidly diluted by the macroscopic fluid, ensuring the homogeneity of the reaction system's phase state.

[0048] Preferably, in step 4, after adding each component sequentially when the temperature of the material in the reactor drops to 30 to 35 degrees Celsius, the stirring speed is reduced to 50 to 70 revolutions per minute, and stirring is continued for 30 to 40 minutes.

[0049] By adopting the above technical solution, the rotation speed is reduced during the cooling and feeding stage, creating a relatively stable laminar flow field. This not only prevents high shear forces from damaging the surfactant intercalation structure after molding, but also meets the process requirement of uniform mixing of multiple components.

[0050] Preferably, triethanolamine is physically separated into a pre-fraction and a post-fraction and added in batches, wherein the mass ratio of the pre-fraction to the post-fraction is 1:2 to 3:5.

[0051] By adopting the above technical solutions, the separate use of triethanolamine has achieved different technical effects.

[0052] The pre-added portion mainly provides coordination buffering capacity to prevent the initial cross-linking reaction from being too fast; while the post-added portion plays a role after the cross-linking network is formed, regulating the final pH of the system and participating in maintaining the long-term physical stability of the internal rheological structure.

[0053] This invention provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method. It has the following beneficial effects:

[0054] 1. This invention, by intercalating and physically anchoring hydrophobic segments of alkyl polysaccharide and polyether-modified heptamethyltrisiloxane into hydrophobic microregions within a three-dimensional cross-linked network, combined with a cold intercalation feeding process at 30-35 degrees Celsius, spatially restricts the self-aggregation behavior of surfactant molecules at low temperatures. This design effectively prevents the crystallization and precipitation phase separation of surfactants in low-temperature environments, stabilizing the macroscopic initial cloud point of the system above 68 degrees Celsius, and improving the physical stability of the fire extinguishing agent under low-temperature storage conditions.

[0055] 2. This invention uses 1,2-propanediol to pre-disperse xanthan gum and sodium lignosulfonate, avoiding gel encapsulation caused by direct contact of water molecules with the powder surface. Simultaneously, triethanolamine, added separately, buffers the coordination reaction between sodium molybdate dihydrate and sodium lignosulfonate. This ligand substitution-based regulation mechanism controls the cross-linking reaction rate, preventing the formation of insoluble particles from localized instantaneous cross-linking of polymer segments, thus enabling the fire extinguishing agent to obtain and maintain stable shear-thinning rheological properties during long-term storage. Attached Figure Description

[0056] Figure 1 The graph shows the test results of macromolecular hydration uniformity and anti-agglomeration of Examples 1 to 5 and Comparative Example 1 of the present invention;

[0057] Figure 2 The graph shows the test results of macroscopic rheological properties and crosslinking degree of Examples 1 to 5 and Comparative Examples 2 and 3 of the present invention;

[0058] Figure 3 The graph shows the thermodynamic phase stability test results of Examples 1 to 5 and Comparative Example 4 of the present invention;

[0059] Figure 4 The figures show the test results of fire extinguishing efficiency and anti-reignition performance of Examples 1 to 5 and some comparative examples of the present invention;

[0060] Figure 5 The graph shows the macroscopic physical property test results under extreme low temperature conditions for Examples 1 to 5 and some comparative examples of the present invention;

[0061] Figure 6 These are test diagrams of the multi-metal low-corrosion protection effectiveness of Examples 1 to 5 and Comparative Example 5 of the present invention;

[0062] Figure 7 This is a flowchart of the steps of the present invention. Detailed Implementation

[0063] 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.

[0064] This invention provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method. The main raw materials and reagents used in the following examples and comparative examples are as follows. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0065] Deionized water with a conductivity of less than or equal to 5 μS / cm.

[0066] 1,2-Propanediol, CAS No. 57-55-6.

[0067] Sodium lignosulfonate, CAS No. 8061-51-6, is an anionic polymer with a weight-average molecular weight of 5,000 to 10,000, a sulfonic acid group content of 1.0 to 2.5 mmol / g, and a pH of 7.0 to 9.0 for a 1% aqueous solution.

[0068] Alkyl polyglycoside, abbreviated as APG0810, CAS number 68515-73-1, is a nonionic surfactant with an alkyl carbon chain length distribution of C8 to C10 and an average degree of polymerization of 1.3 to 1.5.

[0069] Xanthan gum, CAS No. 11138-66-2, is a polysaccharide macromolecule with a weight-average molecular weight of 2 million to 20 million.

[0070] Sodium molybdate dihydrate, CAS No. 10102-40-6.

[0071] Methylbenzotriazole, CAS No. 29385-43-1.

[0072] Triethanolamine, CAS No. 102-71-6.

[0073] 1,1,1,3,5,5,5-Heptamethyltrisiloxane, CAS No. 1873-88-7, purity greater than or equal to 99.0%.

[0074] Terminal allyl polyether is a polymer copolymerized from ethylene oxide and propylene oxide, with a weight-average molecular weight of 600.

[0075] Chloroplatinic acid hexahydrate, CAS No. 16941-12-1, with a platinum content greater than or equal to 37.5%.

[0076] Preparation Example 1:

[0077] See attached document Figure 7 This preparation example provides a method for preparing polyether-modified heptamethyltrisiloxane, including the following steps:

[0078] In a reactor equipped with a reflux condenser, thermometer, constant pressure dropping funnel, and mechanical stirrer, 1.1 moles of terminal allyl polyether are added. Nitrogen gas is introduced for protection, and stirring is started to heat the material in the reactor to 85 degrees Celsius.

[0079] Chloroplatinic acid hexahydrate was added to the reactor as a catalyst to achieve a final platinum concentration of 15 ppm. One mole of 1,1,1,3,5,5,5-heptamethyltrisiloxane was slowly added dropwise through a constant-pressure dropping funnel, controlling the dropping rate to maintain the reaction temperature in the reactor between 85 and 95 degrees Celsius. The dropping process took approximately 1.5 hours.

[0080] After the addition was complete, the reaction was continued at a constant temperature of 85 degrees Celsius for 2 hours. The reaction was then monitored using an infrared spectroscopy system until the sample reached 2150 cm⁻¹. -1 The reaction stops after the characteristic absorption peak of the Si-H bond disappears.

[0081] The reaction solution was transferred to a vacuum distillation apparatus to remove low-boiling-point volatiles under an absolute pressure of 10 kPa and a temperature of 110 degrees Celsius. After cooling to room temperature, polyether-modified heptamethyltrisiloxane was obtained.

[0082] Preparation Example 2:

[0083] This preparation example provides a method for preparing polyether-modified heptamethyltrisiloxane, including the following steps:

[0084] 1.2 moles of terminal allyl polyether were added to a reaction vessel equipped with a reflux condenser, thermometer, constant pressure dropping funnel and mechanical stirrer.

[0085] Nitrogen gas was introduced for protection and stirring was started to heat the material in the reactor to 90 degrees Celsius.

[0086] Chloroplatinic acid hexahydrate was added to the reactor as a catalyst to achieve a final platinum concentration of 10 ppm.

[0087] One mole of 1,1,1,3,5,5,5-heptamethyltrisiloxane was slowly added dropwise through a constant-pressure dropping funnel, with the dropping rate controlled to maintain the reaction temperature inside the vessel between 90 and 100 degrees Celsius. The dropping process took approximately one hour.

[0088] After the addition is complete, maintain a constant temperature of 90 degrees Celsius and continue the reaction for 2 hours.

[0089] Using an infrared spectroscopy detection system, at 2150cm -1 The reaction stops after the characteristic absorption peak of the Si-H bond disappears.

[0090] The reaction solution was transferred to a vacuum distillation apparatus to remove low-boiling-point volatiles under an absolute pressure of 10 kPa and a temperature of 110 degrees Celsius. After cooling to room temperature, polyether-modified heptamethyltrisiloxane was obtained.

[0091] Preparation Example 3:

[0092] This preparation example provides a method for preparing polyether-modified heptamethyltrisiloxane, including the following steps:

[0093] 1.15 moles of terminal allyl polyether were added to a reaction vessel equipped with a reflux condenser, thermometer, constant pressure dropping funnel and mechanical stirrer.

[0094] Nitrogen gas was introduced for protection and stirring was started to heat the material in the reactor to 80 degrees Celsius.

[0095] Chloroplatinic acid hexahydrate was added to the reactor as a catalyst to achieve a final platinum concentration of 20 ppm.

[0096] One mole of 1,1,1,3,5,5,5-heptamethyltrisiloxane was slowly added dropwise through a constant-pressure dropping funnel, with the dropping rate controlled to maintain the reaction temperature inside the reactor between 80 and 90 degrees Celsius. The dropping process took approximately 2 hours.

[0097] After the addition is complete, maintain a constant temperature of 80 degrees Celsius and continue the reaction for 2 hours.

[0098] Using an infrared spectroscopy detection system, at 2150cm -1 The reaction stops after the characteristic absorption peak of the Si-H bond disappears.

[0099] The reaction solution was transferred to a vacuum distillation apparatus to remove low-boiling-point volatiles under an absolute pressure of 10 kPa and a temperature of 110 degrees Celsius. After cooling to room temperature, polyether-modified heptamethyltrisiloxane was obtained.

[0100] Example 1:

[0101] This embodiment provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, including the following steps:

[0102] Taking the preparation of 100 kg of this fire extinguishing agent as an example, the following components were weighed according to the formula: 43.0 kg of deionized water, 40.0 kg of 1,2-propanediol, 7.0 kg of sodium lignosulfonate, 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane obtained in Preparation Example 1, 0.8 kg of sodium molybdate dihydrate, 0.2 kg of methylbenzotriazole, 0.5 kg of xanthan gum, and 0.5 kg of triethanolamine (physically separated into a pre-component of 0.2 kg and a post-component of 0.3 kg).

[0103] Step 1: In a premixing vessel equipped with a paddle stirrer, add 40.0 kg of 1,2-propanediol at room temperature of 25 degrees Celsius, turn on the stirrer and set the speed to 70 rpm, slowly and evenly sprinkle in 0.5 kg of xanthan gum and 7.0 kg of sodium lignosulfonate, and maintain stirring for 15 minutes to obtain a uniform multiphase suspension dispersion.

[0104] Step 2: In the main reactor equipped with a water bath jacket for heating and shear stirring, add 43.0 kg of deionized water, turn on the heating circulation to keep the system temperature constant at 46 degrees Celsius, add 0.8 kg of sodium molybdate dihydrate and 0.2 kg of triethanolamine from the pre-processed part in sequence, set the speed to 110 rpm, and stir at constant temperature for 15 minutes.

[0105] Step 3: Maintain the temperature of the main reactor at 46 degrees Celsius, increase the rotation speed to 180 rpm, and continuously pump the suspension dispersion obtained in step 1 into the main reactor through a constant flow metering pump. Control the total pumping time to be 25 minutes. After the addition is completed, continue to stir at a constant temperature for 25 minutes.

[0106] Step 4: Turn off the heating device of the main reactor and introduce cooling water for forced cooling. When the temperature of the material in the reactor drops to 32 degrees Celsius, slowly add 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane, 0.2 kg of methylbenzotriazole, and 0.3 kg of triethanolamine from the post-processing section. Reduce the stirring speed to 60 rpm and continue stirring for 30 minutes.

[0107] Step 5: Filter and purify the homogeneous fluid obtained in Step 4 through a 100-mesh filter, and finally seal and fill it to obtain the finished fire extinguishing agent concentrate.

[0108] Example 2:

[0109] This embodiment provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, including the following steps:

[0110] Taking the preparation of 100 kg of this fire extinguishing agent as an example, the following components were weighed according to the formula: 53.6 kg of deionized water, 35.0 kg of 1,2-propanediol, 5.0 kg of sodium lignosulfonate, 4.0 kg of alkyl polysaccharide (APG0810), 1.0 kg of polyether-modified heptamethyltrisiloxane obtained in Preparation Example 2, 0.6 kg of sodium molybdate dihydrate, 0.2 kg of methylbenzotriazole, 0.3 kg of xanthan gum, and 0.3 kg of triethanolamine (physically separated into a pre-component of 0.1 kg and a post-component of 0.2 kg).

[0111] Step 1: In a premixing vessel equipped with a paddle stirrer, add 35.0 kg of 1,2-propanediol at room temperature of 20 degrees Celsius, turn on the stirrer and set the speed to 60 rpm, slowly and evenly sprinkle in 0.3 kg of xanthan gum and 5.0 kg of sodium lignosulfonate, and maintain stirring for 15 minutes to obtain a uniform multiphase suspension dispersion.

[0112] Step 2: In the main reactor equipped with a water bath jacket for heating and shear stirring, add 53.6 kg of deionized water, turn on the heating circulation to keep the system temperature constant at 45 degrees Celsius, add 0.6 kg of sodium molybdate dihydrate and 0.1 kg of triethanolamine from the pre-processed part in sequence, set the speed to 100 rpm, and stir at constant temperature for 15 minutes.

[0113] Step 3: Maintain the temperature of the main reactor at 45 degrees Celsius, increase the rotation speed to 150 rpm, and continuously pump the suspension dispersion obtained in step 1 into the main reactor through a constant flow metering pump. Control the total pumping time to be 20 minutes. After the addition is completed, continue to stir at a constant temperature for 20 minutes.

[0114] Step 4: Turn off the heating device of the main reactor and introduce cooling water for forced cooling. When the temperature of the material in the reactor drops to 30 degrees Celsius, slowly add 4.0 kg of alkyl polysaccharide (APG0810), 1.0 kg of polyether-modified heptamethyltrisiloxane, 0.2 kg of methylbenzotriazole, and 0.2 kg of triethanolamine in the post-processing section. Reduce the speed to 50 rpm and continue stirring for 30 minutes.

[0115] Step 5: Filter and purify the homogeneous fluid obtained in Step 4 through a 100-mesh filter, and finally seal and fill it to obtain the finished fire extinguishing agent concentrate.

[0116] Example 3:

[0117] This embodiment provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, including the following steps:

[0118] Taking the preparation of 100 kg of this fire extinguishing agent as an example, the following components were weighed according to the formula: 34.9 kg of deionized water, 45.0 kg of 1,2-propanediol, 9.0 kg of sodium lignosulfonate, 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane obtained in Preparation Example 3, 1.0 kg of sodium molybdate dihydrate, 0.5 kg of methylbenzotriazole, 0.8 kg of xanthan gum, and 0.8 kg of triethanolamine (physically separated into a pre-component of 0.3 kg and a post-component of 0.5 kg).

[0119] Step 1: In a premixing vessel equipped with a paddle stirrer, add 45.0 kg of 1,2-propanediol at room temperature of 25 degrees Celsius, turn on the stirrer and set the speed to 80 rpm, slowly and evenly sprinkle in 0.8 kg of xanthan gum and 9.0 kg of sodium lignosulfonate, and maintain stirring for 20 minutes to obtain a uniform multiphase suspension dispersion.

[0120] Step 2: In the main reactor equipped with a water bath jacket for heating and shear stirring, add 34.9 kg of deionized water, turn on the heating circulation to keep the system temperature constant at 48 degrees Celsius, add 1.0 kg of sodium molybdate dihydrate and 0.3 kg of triethanolamine from the pre-processed part in sequence, set the speed to 120 rpm, and stir at constant temperature for 20 minutes.

[0121] Step 3: Maintain the temperature of the main reactor at 48 degrees Celsius, increase the rotation speed to 200 rpm, and continuously pump the suspension dispersion obtained in step 1 into the main reactor through a constant flow metering pump. Control the total pumping time to be 30 minutes. After the feeding is completed, continue to stir at a constant temperature for 30 minutes.

[0122] Step 4: Turn off the heating device of the main reactor and introduce cooling water for forced cooling. When the temperature of the material in the reactor drops to 35 degrees Celsius, slowly add 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane, 0.5 kg of methylbenzotriazole, and 0.5 kg of triethanolamine from the post-processing section. Reduce the stirring speed to 70 rpm and continue stirring for 40 minutes.

[0123] Step 5: Filter and purify the homogeneous fluid obtained in Step 4 through a 100-mesh filter, and finally seal and fill it to obtain the finished fire extinguishing agent concentrate.

[0124] Example 4:

[0125] This embodiment provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, including the following steps:

[0126] Taking the preparation of 100 kg of this fire extinguishing agent as an example, the formula and weighing amount are exactly the same as in Example 1.

[0127] Step 1: In a premixing vessel equipped with a paddle stirrer, add 40.0 kg of 1,2-propanediol at room temperature of 22 degrees Celsius, turn on the stirrer and set the speed to 70 rpm, slowly and evenly sprinkle in 0.5 kg of xanthan gum and 7.0 kg of sodium lignosulfonate, and maintain stirring for 15 minutes to obtain a uniform multiphase suspension dispersion.

[0128] Step 2: In the main reactor equipped with a water bath jacket for heating and shear stirring, add 43.0 kg of deionized water, start the heating circulation to strictly control the system temperature at 45 degrees Celsius, add 0.8 kg of sodium molybdate dihydrate and 0.2 kg of triethanolamine from the pre-processed part in sequence, set the speed to 110 rpm, and stir at a constant temperature for 15 minutes.

[0129] Step 3: Maintain the temperature of the main reactor at 45 degrees Celsius, increase the rotation speed to 180 rpm, and continuously and rapidly pump the suspension dispersion obtained in step 1 into the main reactor using a constant flow metering pump. Control the total pumping time to be 20 minutes. After the addition is completed, continue to stir at a constant temperature for 20 minutes.

[0130] Step 4: Turn off the heating device of the main reactor and introduce cooling water for forced cooling. When the temperature of the material in the reactor drops to 30 degrees Celsius, slowly add 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane, 0.2 kg of methylbenzotriazole, and 0.3 kg of triethanolamine from the post-processing section. Reduce the stirring speed to 60 rpm and continue stirring for 30 minutes.

[0131] Step 5: Filter and purify the fluid obtained in Step 4 through a 100-mesh filter and then fill it in a sealed container to obtain the finished product.

[0132] Example 5:

[0133] This embodiment provides a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships and its preparation method, including the following steps:

[0134] Taking the preparation of 100 kg of this fire extinguishing agent as an example, the formula and weighing amount are exactly the same as in Example 1.

[0135] Step 1: In a premixing vessel equipped with a paddle stirrer, add 40.0 kg of 1,2-propanediol at room temperature of 25 degrees Celsius, turn on the stirrer and set the speed to 70 rpm, slowly and evenly sprinkle in 0.5 kg of xanthan gum and 7.0 kg of sodium lignosulfonate, and maintain stirring for 15 minutes to obtain a uniform multiphase suspension dispersion.

[0136] Step 2: In the main reactor equipped with a water bath jacket for heating and shear stirring, add 43.0 kg of deionized water, start the heating circulation to strictly control the system temperature at 48 degrees Celsius, add 0.8 kg of sodium molybdate dihydrate and 0.2 kg of triethanolamine from the pre-processed part in sequence, set the speed to 110 rpm, and stir at a constant temperature for 15 minutes.

[0137] Step 3: Maintain the temperature of the main reactor at 48 degrees Celsius, increase the rotation speed to 180 rpm, and continuously and slowly pump the suspension dispersion obtained in step 1 into the main reactor through a constant flow metering pump. Control the total pumping time to be 30 minutes. After the addition is completed, continue to stir at a constant temperature for 30 minutes.

[0138] Step 4: Turn off the heating device of the main reactor and introduce cooling water for forced cooling. When the temperature of the material in the reactor drops to 35 degrees Celsius, slowly add 6.0 kg of alkyl polysaccharide (APG0810), 2.0 kg of polyether-modified heptamethyltrisiloxane, 0.2 kg of methylbenzotriazole, and 0.3 kg of triethanolamine from the post-processing section. Reduce the stirring speed to 60 rpm and continue stirring for 30 minutes.

[0139] Step 5: Filter and purify the fluid obtained in Step 4 through a 100-mesh filter and then fill it in a sealed container to obtain the finished product.

[0140] Comparative Example 1:

[0141] Compared with Example 1, the difference is that the non-aqueous polar pre-dispersion in step 1 was not performed. Instead, deionized water and 1,2-propanediol were directly mixed, and xanthan gum and sodium lignosulfonate powder were added directly at room temperature. All other aspects were the same.

[0142] Comparative Example 2:

[0143] Compared with Example 1, the difference is that triethanolamine was not added in advance in step 2. Instead, all 0.5 kg of triethanolamine in the formula was added in step 4. The rest are the same.

[0144] Comparative Example 3:

[0145] Compared with Example 1, the difference is that thermal phase isothermal control was not performed in steps 2 and 3. Instead, the reaction temperature of these two steps was reduced to 25 degrees Celsius and operated at room temperature. The rest are the same.

[0146] Comparative Example 4:

[0147] Compared with Example 1, the difference is that the cooling and cold intercalation operation of the surfactant was not performed. Instead, the alkyl polysaccharide (APG0810) and the polyether-modified heptamethyltrisiloxane were added directly to the high-temperature (46 degrees Celsius) hot phase in step 2 in advance. All other aspects are the same.

[0148] Comparative Example 5:

[0149] Compared with Example 1, the difference is that the composite corrosion inhibitor component sodium molybdate dihydrate in the formulation is replaced in equal amounts with a common inorganic salt (such as sodium sulfate) that does not have coordination crosslinking ability; all other aspects are the same.

[0150] Test Example 1:

[0151] This test case mainly focuses on the quantitative evaluation of the macroscopic homogeneity and polymer hydration state of the primary pharmaceutical fluids prepared in Examples 1 to 5 and Comparative Example 1 but without filtration.

[0152] 500 mL of primary reagent fluid that was not filtered and purified in step 5 was extracted from the reaction vessel of Examples 1 to 5 and Comparative Example 1 respectively as test samples. During sampling, the vessel was kept under low-speed stirring to ensure the representativeness of the sample.

[0153] Prepare a constant pressure filtration device equipped with a vacuum pump, and place a 200-mesh standard industrial stainless steel filter screen that has been dried to constant weight at 60°C and accurately weighed in the Buchner funnel.

[0154] Turn on the vacuum pump and set the system vacuum pressure to a stable -0.05MPa. Pour 500mL of test sample into the Buchner funnel at once. Use a stopwatch to record the total time taken from when the liquid is poured into the funnel until there are no more continuous droplets falling to the bottom of the funnel. This value is the constant pressure filtration time.

[0155] After filtration, the stainless steel filter screen containing the retained material is carefully removed and placed in a vacuum drying oven at 60°C for 4 hours until constant weight is achieved. The total weight of the dried filter screen is weighed using an analytical balance, and the absolute dry weight of the retained undissolved polymer gel blocks and dry powder clumps is obtained by subtracting the initial weight of the filter screen.

[0156] Weigh the actual mass of the 500mL test sample, or pre-determine the sample density and convert the sample volume into sample mass accordingly, and further calculate the theoretical total mass of xanthan gum and sodium lignosulfonate powder in the sample; divide the dry weight of the retained material by the theoretical total mass of the powder to calculate the filter residue rate.

[0157] Table 1. Test data on macromolecular hydration homogeneity and constant pressure filtration.

[0158] Examples / Comparative Examples Constant pressure filtration time (s) Filter residue rate (%) Example 1 124.3 0.12 Example 2 108.7 0.08 Example 3 142.1 0.15 Example 4 128.6 0.13 Example 5 119.4 0.11 Comparative Example 1 687.5 8.46

[0159] Based on the data in Table 1 and the appendix Figure 1The change in the method of adding polymer powders led to a fundamental difference in the macroscopic physical state of the agent. In the conventional preparation of water-based fire extinguishing agents, directly adding powder to the aqueous phase is a common practice. Comparative Example 1 used this traditional direct water mixing method, and its data feedback showed typical industrial failure characteristics. When large molecules like xanthan gum and sodium lignosulfonate, which contain abundant hydrophilic groups, come into contact with water, the powder surface rapidly hydrates and expands, forming a dense, viscous gel film. This film blocks further contact between the internal dry powder and the water solvent. A large amount of undissolved powder forms stubborn micro and macro agglomerates within the system, causing the filter pores to be rapidly blocked within tens of seconds. The abnormal filtration time of 687.5 seconds and the high dry matter residue of 8.46% reflect a serious loss of effective ingredients. If this fluid is forcibly pushed into the ship's fire-fighting pipeline network, it can easily cause fatal and irreversible blockages at the sprinkler heads.

[0160] The data from Examples 1 to 5, distributed within a time range of 100 to 150 seconds and an extremely low residue rate of less than 0.2%, demonstrate that the non-solvent polar pre-dispersion process completely alters the hydration kinetics of the powder. Actual observations revealed that when a suspension containing 1,2-propanediol was pumped into the reactor, the large molecular chains were in a completely coiled, non-swollen state in the pure alcohol medium, creating a physical isolation layer between the powder particles formed by alcohol molecules. As the suspension entered the continuously shearing hot water environment, 1,2-propanediol rapidly diffused into the outer aqueous phase due to its excellent miscibility with water, allowing the previously encapsulated powder to be uniformly and independently exposed to the water environment at a mesoscopic scale. This phase transfer process decomposes the concentrated hydration of large powder particles into the simultaneous hydration of countless tiny particles, spatially eliminating concentration polarization. Even when the polymer composition ratio was increased to the upper limit in Example 3, or the high-shear pumping time was shortened as in Example 4, the system still maintained highly smooth filtration performance. This indicates that alcohol pre-dispersion is not only an effective means of preventing core encapsulation, but also provides a wide range of process tolerance for industrial-scale mass production, ensuring material uniformity during the subsequent construction of metal complex crosslinking networks.

[0161] Test Example 2:

[0162] This test case mainly focuses on the rheological properties analysis of Examples 1 to 5 and Comparative Examples 2 and 3, which disrupted the crosslinking time and temperature conditions, in order to quantitatively evaluate the construction quality and structural uniformity of the in-situ dynamic crosslinking network in macroscopic fluids.

[0163] 1. Extract 100 mL of the finished drug products of Examples 1 to 5, Comparative Examples 2 and 3 after standing and maturing at room temperature for 24 hours as test samples. The standing process is intended to ensure that the coordination crosslinking network inside the system reaches a thermodynamically stable state.

[0164] 2. The measurement was performed using an advanced rotational rheometer equipped with a coaxial cylindrical test rotor. Before the test, the temperature of the sample cell was precisely kept constant at 20 degrees Celsius using a Peltier temperature control system.

[0165] 3. Perform steady-state shear scan test, setting the shear rate from 0.1 s. -1 Increase continuously to 100s -1 Record the results for each sample at low shear rates (1 s). -1 ) and high shear rate (100s) -1 The apparent viscosity value is calculated at ( ), and the ratio of low shear viscosity to high shear viscosity is calculated as the shear thinning index, which is used to evaluate the network skeleton strength and pumpability of the fluid.

[0166] 4. Perform transient constant shear test, fixing the shear rate of the rheometer at 50s. -1 The system was run continuously for 300 seconds. Continuous apparent viscosity readings were taken from 100 to 300 seconds, and the standard deviation of the viscosity data within this time period was calculated to quantify the uniformity of the cross-linked microstructure within the fluid.

[0167] Table 2. Test data for evaluating the rheological properties and dynamic crosslinking degree of fire extinguishing agents

[0168] Sample Name Low shear viscosity (mPa·s) High shear viscosity (mPa·s) Shear thinning index Standard deviation of viscosity fluctuation (mPa·s) Example 1 1845.2 142.6 12.94 2.15 Example 2 1530.7 128.4 11.92 1.89 Example 3 2106.3 161.8 13.02 3.02 Example 4 1798.5 148.1 12.14 2.67 Example 5 1912.8 136.9 13.97 1.74 Comparative Example 2 3450.6 280.3 12.31 145.8 Comparative Example 3 420.5 95.2 4.41 1.12

[0169] Based on the data in Table 2 and the appendix Figure 2 The control of the crosslinking reaction kinetics largely determines the final rheological characteristics and engineering usability of the system. Conventional formulation development often assumes that as long as a crosslinking agent and a corresponding polymer substrate are present in the system, a network structure will spontaneously and uniformly form. However, feedback from the test of Comparative Example 2 reveals the dangers of this assumption in scale-up production. Due to the removal of the pre-buffering effect of triethanolamine as a weak ligand, molybdate ions and the phenolic hydroxyl groups on the sodium lignin sulfonate molecular chain undergo unimpeded thermodynamic spontaneous complexation upon contact. This strong coordination reaction, which completes in an extremely short time, directly leads to local crosslinking density overload, forming a large number of microscopic "dead crosslinked" gel clumps that are difficult to distinguish with the naked eye but impossible to hide in a rheometer. (50s) -1 During the constant shear test phase, these high-strength microgel particles triggered a strong abrupt change in fluid resistance as they passed through the narrow rotor gap of the rheometer, causing the standard deviation of the viscosity reading to soar to 145.8 mPa·s. Such drastic phase fluctuations would translate into unpredictable surges in friction resistance within the piping network in practical fire protection applications, easily leading to negative pressure suction failure of the proportioning mixer.

[0170] The fluids in Examples 1 to 5 exhibited near-ideal pseudoplastic fluid behavior, with a difference of more than tenfold between their low-shear viscosity and high-shear viscosity. During the formulation mechanism verification phase, we observed that the system with pre-constituted triethanolamine did not show an instantaneous increase in surface viscosity during the isothermal feeding period; the fluid maintained a smooth and uniform thickening rhythm as stirring time progressed. The ligand substitution mechanism acted as a brake here; the large lignin molecules needed to accumulate sufficient thermal energy to gradually displace the triethanolamine molecules attached to the molybdate ions. This deliberately delayed kinetic process provided a time window for the polymer chains to fully extend and disperse in the shear field. The final constructed three-dimensional weakly cross-linked network provided strong skeletal support when stationary, ensuring that the agent would not easily collapse when spread on the fuel surface, while rapidly undergoing chain segment slippage and dissociation under the high shear forces of pumping and injection, exhibiting a low flow resistance of only about 140 mPa·s. The data from Comparative Example 3 clearly confirm this. At room temperature (25°C), although the components were uniformly mixed, the low-shear viscosity of the system was only 420.5 mPa·s, and the shear thinning index dropped to 4.41. This indicates that without the activation energy provided by the set temperature, the macromolecules were unable to overcome the energy barrier of the triethanolamine ligand, the crosslinking network construction completely failed, and the entire system degenerated into a common viscous mixture, unable to provide a structural basis for subsequent film formation and flame retardation resistance.

[0171] Test Example 3:

[0172] This test case mainly focuses on the thermodynamic phase stability analysis of Examples 1 to 5 and Comparative Example 4, which disrupted the surfactant addition timing and temperature conditions, in order to quantitatively evaluate the decisive influence of the cold intercalation process on the cloud point and long-term anti-stratification performance of nonionic surfactants in high-concentration alcohol phase systems.

[0173] 1. Take 200 mL of each of the prepared and purified finished reagents of Examples 1 to 5 and Comparative Example 4 as test samples, dispense them into standard stoppered glass centrifuge tubes with graduation markings, and seal them to prevent volatilization.

[0174] 2. To determine the initial macroscopic cloud point, place a glass tube containing 50 mL of sample in a temperature-controlled transparent water bath equipped with a precision mechanical stirrer and a photoelectric transmittance detection probe. Set the initial temperature to 20 degrees Celsius and slowly increase it at a constant rate of 0.5 degrees Celsius per minute. Continuously monitor the transmittance using the photoelectric probe. When the transmittance of the system suddenly drops by more than 10% of the initial value, and the system is observed to change from homogeneous transparent or translucent to significantly turbid with the naked eye, and micron-sized oil droplets precipitate, record the water bath temperature at this point as the initial macroscopic cloud point of the sample.

[0175] 3. Conduct extreme hot and cold alternating cycle tests. Place the stoppered centrifuge tubes containing the remaining 150 mL of sample into a high and low temperature alternating damp heat test chamber. Set the cycle program as follows: freeze at -30 degrees Celsius for 12 hours, then bake at 60 degrees Celsius for 12 hours. This is one complete cycle. Run 10 cycles continuously to simulate extreme storage and transportation environments.

[0176] 4. After the thermal cycling is completed, the sample is removed and allowed to stand at 25 degrees Celsius for 24 hours to recover. Then, it is transferred to a constant-temperature centrifuge and centrifuged at 3000 rpm for 15 minutes. The phase distribution of the liquid surface in the centrifuge tube is observed, and the volume of the upper precipitated oil phase or the lower flocculent sediment phase is accurately read. The ratio of this volume to the total sample volume is calculated as the phase separation volume ratio after thermal cycling.

[0177] Table 3. Thermodynamic phase stability and macroscopic cloud point test data of the pharmaceutical preparation

[0178] Sample Name Macroscopic initial cloud point (degrees Celsius) Phase separation volume ratio after thermal cycling (%) Example 1 72.4 0.12 Example 2 68.9 0.18 Example 3 75.1 0.09 Example 4 71.3 0.14 Example 5 73.8 0.11 Comparative Example 4 41.5 12.76

[0179] Based on the data in Table 3 and the appendix Figure 3 The timing of surfactant addition constitutes the core watershed for the thermodynamic stability of this formulation. In complex solvent systems containing 35% to 45% by mass of 1,2-propanediol, the phase behavior of nonionic surfactants such as polyether-modified heptamethyltrisiloxane exhibits extreme environmental sensitivity. Comparative Example 4, which employed a conventional industrial operation of directly adding surfactants to a 46°C hot phase, thoroughly exposed the limitations of this process in specific alcohol-water systems. At higher temperatures, the hydrogen bonding between polyether segments and water molecules rapidly weakens, and the hydrophobic siloxane backbone undergoes intense intramolecular coiling and intermolecular association driven by intensified thermal motion, causing the surfactant to directly exceed its solubility limit in this system. Tests showed that the macroscopic cloud point of Comparative Example 4 plummeted to 41.5°C, indicating that irreversible microphase separation had already occurred during the reagent preparation stage. After undergoing 10 cycles of harsh alternating hot and cold shocks, these free-precipitated siloxane droplets rapidly merge and grow due to the Oswald ripening effect, eventually separating into an independent phase layer of up to 12.76% by centrifugation. This significant phase detachment of the effective film-forming components will cause the fire extinguishing agent to completely lose its spreading coefficient on the fuel surface during actual combat application.

[0180] The test results of Examples 1 to 5 verified that the cooling intercalation process reshaped the phase equilibrium of the system through multi-scale steric hindrance effects. When the material in the reactor was cooled to the range of 30°C to 35°C, the lignin-molybdate three-dimensional macromolecular framework constructed in advance through thermal phase reaction had matured and its structure was stable. At this time, the added alkyl polysaccharide and polyether-modified siloxane molecules did not face the risk of hydrogen bond dissociation at high temperatures, and their hydrophobic hydrocarbon tail chains and siloxane segments could be easily intercalated and anchored into the hydrophobic microregions inside the macromolecular crosslinking network. The huge network framework, like a physical lock, completely restricted the free migration and aggregation of surfactant molecules from a steric perspective. The macroscopic cloud point of the example group was generally pushed up to above 68°C, and it maintained an excellent transparent homogeneous state even under normal storage and transportation temperatures and even high-temperature baking at 60°C. Even when subjected to intense thermal expansion and contraction, the surfactant molecules, firmly anchored by the microscopic network, failed to macroscopically aggregate, and the phase separation volume ratio was strictly suppressed to an extremely low level of less than 0.2%. By avoiding direct collisions in high-temperature environments and instead utilizing the pre-existing macromolecular network to provide spatial anchors, this preparation process forcibly fuses components that would otherwise easily repel each other into a highly stable thermodynamic equilibrium state, providing a reliable material basis for subsequent long-term fluorine-free film-forming fire extinguishing.

[0181] Test Example 4:

[0182] This test case mainly focuses on the actual fire extinguishing and foam layer burn resistance evaluation of the finished fire extinguishing agent concentrates of Examples 1 to 5 and Comparative Examples 2, 3 and 4, in order to macroscopically verify the effectiveness of the lignin-molybdate crosslinking network in replacing the traditional fluorocarbon water film-forming mechanism in the fluorine-free system.

[0183] 1. Take the finished fire extinguishing agents prepared in each example and comparative example, mix them with fresh water at a volume ratio of 3:97, and prepare 3% premixed liquid as the standard fire extinguishing fluid for this test.

[0184] 2. In an indoor windless test field, a circular steel anti-burning test pan with an inner diameter of 1.1 meters and an area of ​​approximately 0.95 square meters was set up. A 20-millimeter-thick layer of clean water was injected into the pan, and then 50 liters of commercial 92-octane gasoline was added on top as a combustion carrier.

[0185] 3. Ignite the surface of gasoline and allow it to burn freely for 60 seconds to simulate the high-temperature heat radiation environment of a fire. Using a standard foam spray gun with a calibrated flow rate of 11.4 liters / minute, spray the foaming fluid into the fire at a fixed elevation angle from 1 meter away from the edge of the oil pan. Record the time taken from the start of spraying until the open flames in the pan are completely extinguished as the extinguishing time.

[0186] 4. After the open flame is extinguished, immediately collect the standard foam overflowing from the edge of the oil pan and place it in a special liquid separation measuring cylinder. Record the time required for the volume of the separated liquid to reach 25% of the theoretical volume of the liquid phase in the initial foam. This time is used as the 25% liquid separation time. This parameter characterizes the thermodynamic water-holding stability of the foam network skeleton.

[0187] 5. After the fire is extinguished and the foam layer has been left to stand for 15 minutes, carefully place a standard fire-resistant canister with an inner diameter of 300 mm into the center of the oil pan. Add a small amount of gasoline to the canister and ignite it. Record the duration from the start of ignition until the fire overflows from the fire-resistant canister, burns through the foam layer, and the ignition area on the surface of the oil pan reaches 25% of the total area. This duration is recorded as the fire-resistant time.

[0188] Table 4. Extinguishing agent physical fire suppression and foam network burn resistance test data

[0189] Sample Name Firefighting time (s) 25% precipitation time (min) Burn resistance time (min) Example 1 42.5 8.4 18.2 Example 2 48.1 7.6 16.5 Example 3 39.2 9.1 20.1 Example 4 44.3 8.1 17.8 Example 5 41.7 8.6 18.9 Comparative Example 2 85.6 3.2 6.4 Comparative Example 3 74.2 2.5 4.8 Comparative Example 4 92.4 4.1 5.2

[0190] Based on the data in Table 4 and the appendix Figure 4 Traditional fluorine-free foams based on short-chain hydrocarbon surfactants or polymer additives often exhibit slow fire extinguishing and a high risk of reignition when facing light fuel fires due to their inability to form a low-surface-tension aqueous film. The core of this technical solution lies in replacing the ultra-low surface tension of fluorocarbon chains with the rigid support of a three-dimensional cross-linked network framework. In actual combustion tests, it was observed that the foam fluids generated in Examples 1 to 5 did not liquefy and collapse rapidly upon contact with the high-temperature fuel surface, unlike ordinary foams. Due to the natural heat resistance imparted by the abundant phenylpropane structure in the lignin molecular framework, the metal coordination bonds formed by molybdate groups shrink in situ and slightly carbonize under high-temperature radiation, forming a dense, continuous liquid film barrier layer with a certain mechanical strength at the interface between the fuel and the foam. This framework not only effectively traps moisture, significantly extending the 25% separation time to over 7.5 minutes, but also, through physical barrier effects, cuts off the evaporation and dissipation path of fuel vapor within approximately 40 to 50 seconds, achieving an anti-burning time of over 16 minutes, with most exceeding 17 minutes. A moderate increase in crosslinking density, as in Example 3, further enhances the network density under thermal shock, achieving an excellent burn resistance index of 20.1 minutes.

[0191] In contrast, the control group, which lacked effective cross-linking, experienced a precipitous decline in extinguishing performance. In Comparative Example 3, the lack of thermal phase activation led to complete failure of coordination cross-linking; the agent was essentially just a simple physical mixture of polymers and surfactants. This structure offered no resistance to flames at 1000 degrees Celsius, with extremely fragile foam bubble walls and a 25% separation time of only 2.5 minutes. The dehydrated, shriveled bubbles rapidly collapsed under the pressure of gasoline vapors, shortening its fire resistance time to less than 5 minutes. Similarly, the dead cross-linked clumps formed in Comparative Example 2 failed to spread evenly on the oil surface, and the gaps between the blocky gels became channels for fuel vapor escape and flame penetration. In Comparative Example 4, due to the release of surfactants during storage and transportation, the overall foaming ability and spreading coefficient of the agent were severely weakened, resulting in an extinguishing time of 92.4 seconds, far exceeding the tolerance limit in actual combat. The experimental phenomena clearly reveal the decisive significance of kinetic delayed crosslinking and cold intercalation stabilization processes in reshaping the hydrodynamic properties of fluorine-free fire extinguishing fluids. Simple component stacking cannot cope with the extreme thermodynamic challenges of oil fires; it is necessary to rely on precise spatiotemporal process control to construct specific microscopic spatial topologies.

[0192] Test Example 5:

[0193] This test case mainly focuses on the quantitative evaluation of the extreme freezing crystallization temperature and low-temperature foaming ability of the finished products of Examples 1 to 5 and Comparative Examples 1, 3 and 4, in order to verify the applicability of in-situ crosslinking network and cold intercalation process to macroscopic antifreeze and eruption in the polar or cold sea environment of ships.

[0194] 500 mL of each of the prepared and purified finished reagents from Examples 1 to 5 and Comparative Examples 1, 3 and 4 were extracted as test samples and dispensed into polytetrafluoroethylene sampling bottles with good sealing properties.

[0195] A dedicated low-temperature freezing point analyzer equipped with mechanical stirring and a high-precision temperature sensor was used to inject 50 mL of the reagent to be tested into the sample tube. The cooling bath was activated to force cooling at a constant rate of 1 degree Celsius per minute, while the sample was continuously stirred at 120 rpm. The phase changes of the fluid within the tube were closely observed. When the temperature sensor reading showed a temperature rise due to the release of latent heat of crystallization (i.e., the supercooling critical point), or when the stirring motor torque suddenly overloaded due to the complete loss of macroscopic fluidity, the system temperature at this point was recorded as the ultimate freezing point of the sample.

[0196] The remaining 450 mL of test sample, along with the standard micro foaming gun, was placed in a large constant-temperature cold storage room with the ambient temperature set at -30 degrees Celsius and left to stand for 48 hours to allow the Brownian motion of the molecular chain segments inside the drug to be fully reduced and reach a low-temperature thermodynamic equilibrium state.

[0197] After the storage period expires, an in-situ foaming test is conducted directly inside the cold storage. The frozen agent is connected to a micro foaming gun and sprayed into a collection tank with volume markings at a standard working pressure of 0.7 MPa. After spraying, the foam on the surface of the collection tank is quickly scraped off and the total volume of the generated foam is read. This volume is divided by the actual volume of the original agent consumed to calculate the foaming ratio at -30 degrees Celsius.

[0198] Table 5. Macroscopic property test data under extreme low temperature conditions

[0199] Sample Name Limiting freezing point (degrees Celsius) Foaming ratio at -30 degrees Celsius Example 1 -42.3 7.4 Example 2 -38.6 6.8 Example 3 -46.1 8.1 Example 4 -41.2 7.2 Example 5 -43.8 7.6 Comparative Example 1 -31.4 3.2 Comparative Example 3 -35.2 4.5 Comparative Example 4 -27.8 1.9

[0200] Based on the data in Table 5 and the appendix Figure 5 Macroscopic antifreeze performance depends not only on the absolute amount of antifreeze added, but also on the integrity of the system's microscopic topology and its ability to maintain a homogeneous phase. In past field surveys of fire-fighting systems for polar routes on ocean-going vessels, a phenomenon was observed: even formulations containing more than 30% alcohol-based antifreeze would still experience localized freezing and even nozzle blockage at around -25 degrees Celsius. The test data from Comparative Example 4 visually reproduced this failure process. Due to microscopic phase separation caused by the early precipitation of surfactants in the hot phase, a severe imbalance occurred in the solute distribution between the aqueous and alcohol phases. The alcohol-poor aqueous phase region reached its freezing point first during cooling, and the precipitated tiny ice crystals rapidly engulfed surrounding free water molecules, causing the overall fluid's ultimate freezing point to rise significantly to -27.8 degrees Celsius. With the loss of a large amount of surfactant, the sample essentially lost its ability to reduce the interfacial tension of the gas-liquid interface at -30 degrees Celsius, and the ejected material appeared as a thin liquid mixed with ice crystals, with the foaming ratio collapsing to 1.9, which had no fire extinguishing value. In Comparative Example 1, the undispersed dry powder clumps acted as natural seed crystals for heterogeneous nucleation during the cooling and deceleration process, causing ice crystals to adhere to their surface and grow rapidly at a higher temperature (-31.4 degrees Celsius), which also led to a dual decline in antifreeze and foaming performance.

[0201] The lignin-molybdate three-dimensional cross-linked network constructed within Examples 1 to 5 provides a structural pathway to solving the low-temperature phase transition problem. The uniformly distributed, weakly cross-linked framework forms microscopic mechanical barriers within the fluid, these interlaced macromolecular segments strictly severing the growth path of water molecules arranged in an orderly manner into a large ice crystal lattice from a three-dimensional spatial perspective. Even when the temperature approaches or even falls below -40 degrees Celsius, water molecules are still forcibly confined within the mesoscopic network constructed by alcohols and polymers, maintaining a deeply supercooled liquid state. This structural effect has a strong positive synergy with the thermodynamic freezing point reduction mechanism of 1,2-propanediol, forcibly lowering the freezing point of Example 3 to -46.1 degrees Celsius. The polyether-modified heptamethyltrisiloxane molecules, firmly anchored within the cross-linked network by the cold intercalation process, did not undergo any aggregation or release after extreme freezing at -30 degrees Celsius. When the agent is sprayed under a shear pressure of 0.7 MPa in an extremely cold environment, the siloxane branches, in a low-molecular-weight thermal motion state, can still achieve rapid interfacial spreading by smoothly slipping through the cross-linked skeleton, ensuring the efficiency of the mixed fluid in capturing and encapsulating air, and maintaining a foaming ratio of over 6.8 throughout the entire series. This microscopic skeleton, which is not damaged by extreme cold, provides a very high margin of error for deck firefighting operations on ships in high-latitude sea areas without insulation measures.

[0202] Test Example 6:

[0203] This test case mainly focuses on the metal strip immersion test of Examples 1 to 5 and Comparative Example 5, which destroyed the coordination corrosion inhibitor composite system, to evaluate the static corrosion of typical ship pipelines and tank materials under long-term constant temperature storage.

[0204] Prepare standard Q235 carbon steel test pieces and H62 brass test pieces. Use metallographic sandpaper of different grits to polish the surface step by step until there are no scratches and a smooth metallic luster is exposed. Place the test pieces in anhydrous ethanol and acetone media for ultrasonic degreasing and cleaning. After drying with cold air, place them in a vacuum desiccator and let them stand for 24 hours. Take them out and use an analytical balance with an accuracy of 0.01% to accurately weigh the initial mass of each test piece.

[0205] Measure 400 mL of the finished pharmaceutical products from Examples 1 to 5 and Comparative Example 5 and pour them into 500 mL wide-mouth glass bottles with sealed caps.

[0206] Using polytetrafluoroethylene insulated thin wire, the treated carbon steel test piece and brass test piece are suspended and completely immersed in the liquid in each bottle. During the suspension process, it is necessary to ensure that the two metal test pieces in the same container do not touch each other and are suspended in the middle of the liquid without touching the bottle wall. Then, tighten the inner stopper and outer cap to complete the seal.

[0207] All sealed glass bottles were transferred into a computer-controlled constant temperature chamber and continuously immersed in the solution at an ambient temperature of 40 degrees Celsius for 30 days. This step was used to simulate the long-term high-temperature immersion state when a ship passes through the equatorial route or is stored in an environment near the engine room.

[0208] After the soaking period, each test piece was removed and subjected to delamination and rust removal using a prepared chemical cleaning solution. Carbon steel test pieces were cleaned with a dilute hydrochloric acid solution containing an appropriate amount of hexamethylenetetramine, while brass test pieces were cleaned with a dilute sulfuric acid solution to remove surface corrosion products and the film layer. After rinsing with deionized water and complete drying, the test pieces were weighed again at the final mass. The average corrosion rate of each group of test pieces was calculated based on the mass difference and surface area, with the unit being mg / d·dm³. 2 .

[0209] Table 6. Test data on metal corrosion rate under chemical immersion conditions

[0210] Sample Name <![CDATA[Corrosion rate of Q235 carbon steel (mg / d·dm 2 )]]> <![CDATA[Corrosion rate of H62 brass (mg / d·dm 2 )]]> Example 1 2.14 1.05 Example 2 3.42 1.83 Example 3 1.87 0.94 Example 4 2.58 1.21 Example 5 2.01 1.12 Comparative Example 5 24.63 8.45

[0211] Based on the data in Table 6 and the appendix Figure 6 The molecular structure and reaction state of the anti-corrosion components determine the electrochemical weight loss process of the ship's multi-metal pipe network. The inner walls of ship fire-fighting pipes are constantly immersed in liquid, facing the tendency for galvanic corrosion caused by dissolved oxygen and impurity ions. Whether a single-mechanism anti-corrosion additive can cope with the charge transfer problem at the multiphase interface is a direct challenge for the formulation. Comparative Example 5 eliminated the participation of transition metal oxyacids by replacing sodium molybdate dihydrate with sodium sulfate. The test data showed that this material-level replacement caused a systemic protective failure. Sulfate is corrosive, penetrating the original oxide layer on the metal surface in the early stages of immersion, initiating anodic dissolution of Q235 carbon steel. A corrosion rate of 24.63 mg / (d·dm2) indicates that the carbon steel substrate was in an unprotected exposed state. Although the system retained methylbenzotriazole, a dedicated organic corrosion inhibitor for protecting copper, the H62 brass sample still showed an abnormal mass decay of 8.45 mg / (d·dm2). In heterogeneous metal hybrid systems, if there is a lack of an overall anodic passivation basis provided by inorganic materials, the expansion of localized corrosion microcells will disrupt the physical adsorption structure of organic molecule monolayers.

[0212] Examples 1 to 5 achieved simultaneous protection against two metals. Data feedback showed that the corrosion rates of both Q235 carbon steel and H62 brass were in a low range. In the actual testing process, it was observed that the immersion solution in the examples did not change its transmittance after 30 days of constant-temperature immersion, and no visible metal oxide patches formed on the surface of the test pieces. This phenomenon confirms the derivation effect of the coordination cross-linking network at the metal interface. Most molybdate ions in the formulation participated in the construction of the coupling network with the sodium lignin sulfonate ligand. This weak coordination bond, controlled by the chemical equilibrium constant, established an adaptive dissociation mechanism in solution. Free molybdate ions could migrate to the surface of the carbon steel substrate to form an amorphous iron-molybdenum heteropolyacid passivation film. Triethanolamine and methylbenzotriazole molecules underwent secondary adhesion at the micropores of this inorganic barrier film, forming a composite physical barrier with a gradient distribution from the inside out. Relying on the trace amounts of active ions released by the dissociation of macromolecules, the metal surface has a chemical self-repair mechanism to cope with changes in electrochemical potential, thus suppressing the risk of perforation in the internal pipes under long-term liquid storage conditions.

[0213] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships, characterized in that, The extinguishing agent is made of components comprising the following parts by weight: 34.9–53.6 parts deionized water; 35.0–45.0 parts of 1,2-propanediol; Sodium lignosulfonate 5.0–9.0 parts; Alkyl polysaccharide 4.0–6.0 parts; 1.0–2.0 parts of polyether-modified heptamethyltrisiloxane; Sodium molybdate dihydrate, 0.6–1.0 parts; 0.2–0.5 parts of methylbenzotriazole; Xanthan gum 0.3–0.8 parts; Triethanolamine 0.3–0.8 parts; The fire extinguishing agent has a three-dimensional cross-linked network skeleton structure inside. The three-dimensional cross-linked network skeleton is formed by the in-situ coordination and cross-linking of molybdate ions dissociated from sodium molybdate dihydrate and phenolic hydroxyl groups on the ligand displacement buffering action of sodium lignosulfonate molecular chain under the action of triethanolamine ligand displacement buffering. The alkyl polysaccharide and the hydrophobic segments of the polyether-modified heptamethyltrisiloxane are intercalated and anchored in the hydrophobic microregions inside the three-dimensional cross-linked network framework; the macroscopic initial cloud point of the fire extinguishing agent at 20°C is greater than or equal to 68°C, and the ratio of the apparent viscosity at low shear rate to the apparent viscosity at high shear rate at 20°C is 11.92 to 13.

97.

2. The low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 1, characterized in that, The extinguishing agent is made from the following components in parts by weight: 43.0 parts deionized water, 40.0 parts 1,2-propanediol, 7.0 parts sodium lignosulfonate, 6.0 parts alkyl polysaccharide, 2.0 parts polyether-modified heptamethyltrisiloxane, 0.8 parts sodium molybdate dihydrate, 0.2 parts methylbenzotriazole, 0.5 parts xanthan gum, and 0.5 parts triethanolamine.

3. The low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 1, characterized in that, The sodium lignosulfonate is an anionic polymer compound with a weight-average molecular weight of 5,000 to 10,000 and a sulfonic acid group content of 1.0 to 2.5 mmol / g; the alkyl polysaccharide is a nonionic surfactant with an alkyl carbon chain length distribution of C8 to C10 and an average degree of polymerization of 1.3 to 1.

5.

4. The low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 1, characterized in that, The polyether-modified heptamethyltrisiloxane is a polymer obtained by hydrosilylation reaction of terminal allyl polyether and 1,1,1,3,5,5,5-heptamethyltrisiloxane at 80-100°C under the catalysis of chloroplatinic acid hexahydrate; wherein the weight average molecular weight of the terminal allyl polyether is 600.

5. A method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships, according to any one of claims 1-4, characterized in that... Includes the following steps: Step 1: In a premixing vessel, the 1,2-propanediol, xanthan gum and sodium lignosulfonate are mixed and stirred to obtain a uniform multiphase suspension dispersion; Step 2: Add the deionized water to the main reactor, turn on the heating and keep it at a constant temperature, then add sodium molybdate dihydrate and the triethanolamine from the previous part in sequence, and stir at a constant temperature. Step 3: Keep the temperature of the main reactor constant and increase the stirring speed. Continuously pump the suspension dispersion obtained in step 1 into the main reactor. After the feeding is completed, continue stirring at a constant temperature to build a cross-linked network. Step 4, Cooling: Cool the material in the main reactor. When the temperature drops to 30-35°C, slowly add alkyl polysaccharide, polyether-modified heptamethyltrisiloxane, methylbenzotriazole and triethanolamine in the later part in sequence, while slowing down the stirring and continuing to stir, to complete the cold intercalation of the surfactant. Step 5: Filter and purify the fluid obtained in Step 4, and then fill it in a sealed container to obtain the final product.

6. The method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 5, characterized in that, In step 1, 1,2-propanediol is added to the premixing vessel at room temperature of 20-25°C. The stirring speed is set to 60-80 rpm. Xanthan gum and sodium lignosulfonate are slowly and evenly sprinkled in, and stirring is maintained for 15-20 minutes.

7. The method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 5, characterized in that, In step 2, the system in the main reactor is kept at a constant temperature of 45-48°C, and the stirring speed is set to 100-120 rpm. The system is stirred at this constant temperature for 15-20 minutes.

8. The method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 5, characterized in that, In step 3, maintain the temperature of the main reactor at 45-48°C, increase the rotation speed to 150-200 rpm, control the total pumping time of the suspension dispersion to 20-30 minutes using a constant flow metering pump, and continue constant temperature stirring for 20-30 minutes after the feeding is completed.

9. The method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 5, characterized in that, In step 4, when the temperature of the material in the reactor drops to 30-35°C, add each component in sequence, reduce the stirring speed to 50-70 rpm, and continue stirring for 30-40 minutes.

10. The method for preparing a low-corrosion, low-temperature resistant aqueous film-forming foam fire extinguishing agent for ships according to claim 5, characterized in that, The triethanolamine is physically split into a pre-phase and a post-phase and added in batches, wherein the mass ratio of the pre-phase to the post-phase is 1:2 to 3:5.

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