Fire extinguishing microcapsule composition and method for preparing the same

Abstract

This invention discloses a fire extinguishing microcapsule composition and its preparation method, belonging to the field of microcapsule preparation technology. It includes an inner core-shell structured microcapsule and an outer layer of vinyl alcohol-based polymer resin coating the microcapsule. The microcapsule is composed of a core layer of volatile fluorinated fire extinguishing agent and a shell layer of cross-linked polymer material without vinyl alcohol units. The content of the vinyl alcohol-based polymer resin layer is 5-30% of the total weight of the fire extinguishing microcapsule composition. The fire extinguishing microcapsule composition prepared by this invention, through the synergistic effect of the microcapsule shell and the vinyl alcohol-based polymer resin, possesses both excellent processing shear resistance and thermal storage stability. Its outer layer uses a vinyl alcohol-based polymer with excellent airtightness and extremely high softening temperature, significantly improving the release temperature of the core fire extinguishing agent and effectively reducing leakage during storage, thereby greatly extending the product's storage life and service life.

Description

Technical Field

[0001] This invention relates to the field of microcapsule preparation technology, and in particular to a fire extinguishing microcapsule composition and its preparation method. Background Technology

[0002] Microencapsulation technology is a technique that encapsulates solid, liquid, or gaseous substances in polymer films. It is widely used in daily chemical products, food industry, biomedicine, and polymer material additives. In the field of fire protection, microencapsulating fire extinguishing agents can achieve stable storage and release triggered by target temperature, which is of great significance for automatic early fire suppression.

[0003] Currently, research has been conducted on microencapsulating fire extinguishing agents for initial fires in confined spaces (such as electrical distribution cabinets and energy storage stations). For example, in the invention patent with publication number CN118649393A and patent name "A Perfluorohexanone Fire Extinguishing Microcapsule and Its Preparation Method", a gelatin / montmorillonite / sodium polyphosphate composite is used as the inner shell layer and polyisocyanate / phenolic resin as the outer shell layer to encapsulate the low-boiling-point liquid perfluorohexanone core material. Although the mechanical properties of the fire extinguishing microcapsule are improved through the incorporation of inorganic materials and the double-shell structure, it begins to show obvious leakage of the fire extinguishing core material before 80°C, indicating insufficient thermal stability.

[0004] For example, in existing technologies, microcapsules encapsulating the low-boiling-point gas HFC-236fa with a P(AN-MMA) copolymer as the shell have been successfully prepared using suspension polymerization. Although this technology achieves the encapsulation of low-boiling-point gases, the airtightness and heat resistance of its shell material are limited, resulting in a low release temperature of the extinguishing agent. In high-temperature environments in summer (such as the internal temperature of vehicles and electrical boxes, which can reach above 70°C), the core material is prone to slow leakage, leading to a decrease in fire extinguishing capability. At the same time, during a fire, the excessively low release temperature will cause the extinguishing agent to be released prematurely before reaching the core area of ​​the flame, seriously affecting the fire extinguishing efficiency.

[0005] In addition, existing fire extinguishing microcapsules generally do not pay enough attention to processing shear resistance, which makes them easy to break during actual application processing such as dispersion and blending, thus limiting their universality of application scenarios.

[0006] Based on the above problems, a fire extinguishing microcapsule composition with high release temperature, excellent storage stability and good processing shear resistance is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a fire extinguishing microcapsule composition and its preparation method to solve the problems in the prior art.

[0008] To achieve the above objectives, the present invention provides a fire extinguishing microcapsule composition, comprising an inner layer of microcapsules with a core-shell structure and an outer layer of vinyl alcohol-based polymer resin coating the microcapsules; the microcapsules are composed of a core layer of volatile fluorinated fire extinguishing agent and a shell layer of cross-linked polymer material without vinyl alcohol units; the content of the vinyl alcohol-based polymer resin layer is 5-30% of the total weight of the fire extinguishing microcapsule composition.

[0009] Preferably, the vinyl alcohol-based polymer is one or more combinations of polyvinyl alcohol, vinyl alcohol-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer.

[0010] Preferably, the shell of the microcapsule is a thermoplastic polymer or a thermosetting polymer, and is one or more combinations of acrylate copolymers, methacrylate copolymers, acrylonitrile copolymers, styrene copolymers, melamine-formaldehyde resins, and melamine-urea-formaldehyde resins.

[0011] Preferably, the volatile fluorinated fire extinguishing agent has a boiling point of not more than 120°C under normal pressure, and the volatile fluorinated fire extinguishing agent is one or more combinations of C3-C8 perfluoroketones, C3-C8 perfluoroalkanes, or methyl nonafluorobutyl ether.

[0012] The present invention also provides a method for preparing the above-mentioned fire extinguishing microcapsule composition, comprising the following steps:

[0013] S1. Microcapsules containing fluorine-containing core materials are prepared using suspension polymerization or interfacial polymerization techniques, using volatile fluorine-containing fire extinguishing agents and cross-linked polymers or polymerizable monomers without vinyl alcohol units as raw materials.

[0014] S2. Disperse the microcapsules obtained in S1 in a solution or melt of vinyl alcohol polymer to obtain a microcapsule dispersion, wherein the amount of vinyl alcohol polymer in the dispersion accounts for 5-30% of the total amount of microcapsules and vinyl alcohol polymer;

[0015] S3. The microcapsule dispersion is granulated using a screw extruder to obtain fire extinguishing microcapsule composition particles.

[0016] Preferably, in S1, the core material of the microcapsule accounts for 50-95 wt% of the total mass of the microcapsule, the fluorine content of the fluorine-containing core material is 50-80 wt%, and the shell thickness is 1-20 μm.

[0017] Preferably, the shell thickness of the microcapsule is 2~10μm. If the shell thickness is too high, the core material content will be insufficient and the fire extinguishing performance will be reduced. If the shell thickness is too low, the microcapsule strength will be insufficient. In the actual application of dispersion, blending and other processing, the microcapsule will be damaged and the core material will leak due to insufficient shear resistance.

[0018] Preferably, in S1, the fluorinated core material is one or more combinations of perfluoroacetone, perfluorobutanone, perfluoropentanone, perfluorohexanone, perfluoropropane, perfluorobutane, perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, hexafluoropropane, heptafluoropropane, and methylnonafluorobutyl ether.

[0019] Preferably, in S2, the vinyl alcohol polymer solution or melt contains water or an alcohol polar solvent, and the content of the polar solvent is 5-80 wt%.

[0020] Preferably, the polar solvent is one or a combination of water, methanol, ethanol, propanol, isopropanol, n-butanol, and tert-butanol.

[0021] Preferably, in step S3, the die temperature of the screw extruder is 60~130℃.

[0022] Preferably, the sodium content in the fire extinguishing microcapsule composition is 1~1000 ppm by mass; the particle size of the fire extinguishing microcapsules is 5~200 μm.

[0023] Preferably, after the fire extinguishing microcapsule composition is stored at 85°C and 65% relative humidity for 7 days, the loss of the core material is no more than 5 wt%.

[0024] Preferably, after the fire extinguishing microcapsule composition is subjected to high-speed shearing treatment in the aqueous dispersion, the core material loss is no more than 10 wt%.

[0025] Preferably, the fire extinguishing core material of the fire extinguishing microcapsule composition has a release temperature of not less than 150°C, and the water content of the fire extinguishing microcapsule composition is less than 1 wt%.

[0026] Preferably, the fire extinguishing microcapsule composition has high heat resistance. Thermogravimetric analysis is used to measure the change in mass of the composition with temperature under programmed temperature control at 20℃ / min. The change in mass of the fire extinguishing microcapsule composition with temperature can reflect the release rate and amount of the fire extinguishing agent core material. Specifically, the mass loss rate of the fire extinguishing microcapsule composition is 0-30wt% in the temperature range of 25~120℃; the temperature range with the fastest release rate of the fire extinguishing core material is 150~230℃.

[0027] Preferably, the mass loss rate of the fire extinguishing microcapsule composition is 0-20 wt% within the temperature range of 25-120°C; the temperature range with the fastest release rate of the fire extinguishing core material is 170-200°C.

[0028] Therefore, the fire extinguishing microcapsule composition and its preparation method of the present invention have the following beneficial effects:

[0029] (1) The microcapsule composition consists of an inner fire extinguishing microcapsule and an outer vinyl alcohol polymer resin. The fire extinguishing microcapsule contains a low-boiling-point gaseous or liquid fluorinated fire extinguishing agent core material. After the microcapsule shell is heated and softened or broken, the core material fire extinguishing agent can be released to extinguish the fire. The vinyl alcohol polymer coating on the surface of the fire extinguishing microcapsule has extremely high barrier properties, which can significantly reduce the leakage loss of the core material during high-temperature storage and use, and improve the storage and service life of the microcapsule composition.

[0030] (2) By coating the outer layer with an ethylene alcohol polymer resin with excellent airtightness, extremely high softening temperature and high degree of alcoholysis, the present invention significantly improves the release temperature of the core material fire extinguishing agent (not less than 150°C), so that the core material can be released at a higher temperature, effectively avoiding the premature release of the fire extinguishing agent in non-target high temperature areas, ensuring that the fire extinguishing agent can accurately act on the core area of ​​the flame, thereby greatly improving the fire extinguishing efficiency.

[0031] (3) The outer layer of the vinyl alcohol polymer provides extremely high gas barrier properties, which works synergistically with the shell of the microcapsule to significantly reduce the leakage of the core material in high temperature and high humidity storage environment and greatly extend the storage life of the product; and it can withstand high-speed shearing treatment, making it less prone to damage in actual application processing (such as dispersion and blending), thus broadening its processing adaptability and application scenarios in various polymer matrices.

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0033] Figure 1 The thermogravimetric curve and the derivative thermogravimetric curve are shown in Embodiment 1 of the present invention. Detailed Implementation

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] This invention provides a specific method for preparing a fire extinguishing microcapsule composition, comprising the following steps:

[0037] S1. Microcapsules containing fluorinated core materials are prepared using suspension polymerization or interfacial polymerization techniques, with the volatile fluorinated fire extinguishing agent and cross-linked polymers without vinyl alcohol units as raw materials, or with the volatile fluorinated fire extinguishing agent and polymerizable monomers as raw materials. The core material accounts for 50-95 wt% of the total mass of the microcapsules, the fluorine content in the fluorinated core material is 50-80 wt%, and the shell thickness is 1-20 μm.

[0038] 1) When using volatile fluorinated fire extinguishing agents and polymerizable monomers as raw materials, the specific steps are as follows (the following parts are by weight):

[0039] 100 parts of polymerizable monomer, 0.01-1 part of crosslinking agent and 0.05-5 parts of free radical initiator are thoroughly mixed and dissolved to obtain an oil phase, which is added to 200-2000 parts of aqueous phase, and then 200-800 parts of fluorine-containing fire extinguishing agent are added; then 8-150 parts of acidic silica sol are added as a dispersant and dispersed at high speed to obtain an oil-in-water suspension; the polymerization reaction is carried out at 40-80℃ for 5-30 hours under stirring and mixing, the resulting suspension is filtered and rinsed with deionized water, and dried at 50-80℃ for 1-5 hours.

[0040] 2) When using volatile fluorinated fire extinguishing agents and cross-linked polymers without vinyl alcohol units as raw materials, the specific steps are as follows (the following parts are by weight):

[0041] Add 200-1000 parts of fluorinated fire extinguishing agent to 600-1200 parts of deionized water, add an emulsifier, and stir to obtain a fire extinguishing agent emulsion; add 800-2100 parts of a crosslinked polymer solution without vinyl alcohol units dropwise to the fire extinguishing agent emulsion, raise the temperature to 30-50℃, and simultaneously slowly add acid to adjust the pH to 3.0. 1. Slowly heat to 40~70℃, cure for 1~10 hours, filter, wash, and dry at 50~80℃ for 1~5 hours.

[0042] S2. Disperse the microcapsules obtained in S1 in a vinyl alcohol polymer solution or melt to obtain a microcapsule dispersion. The amount of vinyl alcohol polymer in the dispersion accounts for 5-30% of the total amount of microcapsules and vinyl alcohol polymer. The vinyl alcohol polymer solution or melt contains water or an alcohol polar solvent, and the content of the polar solvent is 5-80 wt%. The polar solvent is one or a combination of water, methanol, ethanol, propanol, isopropanol, n-butanol, and tert-butanol.

[0043] S3. The microcapsule dispersion is granulated using a screw extruder to obtain fire extinguishing microcapsule composition particles; the die temperature of the screw extruder is 60~130℃.

[0044] The above method will be further explained below with reference to specific embodiments.

[0045] Example 1

[0046] This embodiment prepares a fire extinguishing microcapsule composition, and the specific steps are as follows:

[0047] S1. Using volatile fluorinated fire extinguishing agents and crosslinkable monomers without vinyl alcohol units as raw materials, microcapsules containing fluorinated core materials are prepared by suspension polymerization; specifically:

[0048] Add 1500g of sodium chloride to 12000g of deionized water and dissolve completely to obtain the aqueous phase; add 300g of methyl methacrylate, 1200g of acrylonitrile and 15g of azobisisobutyronitrile and dissolve completely to obtain the oil phase.

[0049] The aqueous phase and oil phase were poured into a high-pressure reactor in sequence, and then 4500g of hexafluoropropane gas was introduced. Then, 800g of acidic silica sol (25wt% solid content) was added as a dispersant and dispersed at 1500rpm for 25min to obtain an oil-in-water suspension emulsion.

[0050] Nitrogen gas was introduced into the above reaction vessel and pressurized to 1 MPa. The polymerization reaction was carried out at a constant temperature of 60°C and a rotation speed of 300 rpm for 20 h. The resulting fire extinguishing microcapsule suspension was filtered and rinsed three times with deionized water. The sample was then placed in a 60°C oven and dried for 2 h to obtain the fire extinguishing microcapsules.

[0051] The obtained fire extinguishing microcapsules were found to have a particle size of 51 μm and a hexafluoropropane content of 66 wt%.

[0052] S2. Mix 670g of fire extinguishing microcapsules, 250g of ethylene-vinyl alcohol copolymer and 50g of water using a mixer to obtain a microcapsule dispersion.

[0053] S3. The microcapsule dispersion is added to a single-screw extruder for melt mixing, extrusion, and granulation. The melt temperature of the screw extruder is 135℃, and the die temperature is 115℃. The resulting water-containing fire extinguishing microcapsule composition particles are dried at 100℃ for 15 hours to obtain the fire extinguishing microcapsule composition. The fire extinguishing microcapsule composition contains 27.2 wt% vinyl alcohol polymer resin and 0.05 wt% water.

[0054] The core material content and release temperature of the product in Example 1 were detected using thermogravimetric analysis (TGA). A thermogravimetric curve was obtained. Based on the relationship between sample weight and temperature, the mass loss in the 30–250°C range was taken as the mass of the extinguishing agent core material. The derivative thermogravimetric curve was obtained by differentiating the thermogravimetric curve, and the temperature corresponding to the peak value was taken as the release temperature of the core material. The results are as follows: Figure 1 As shown.

[0055] Example 2

[0056] This embodiment prepares a fire extinguishing microcapsule composition, and the specific steps are as follows:

[0057] S1. Using volatile fluorinated fire extinguishing agents and crosslinkable monomers without vinyl alcohol units as raw materials, microcapsules containing fluorinated core materials are prepared by suspension polymerization; specifically:

[0058] Add 1500g of sodium chloride to 12000g of deionized water and dissolve completely to obtain the aqueous phase; add 500g of methyl methacrylate, 1000g of trifluoroethyl methacrylate, 4500g of perfluorohexanone and 15g of azobisisobutyronitrile to a glass bottle and dissolve completely to obtain the oil phase.

[0059] The aqueous and oil phases were sequentially poured into a high-pressure reactor, and then 500g of silica sol (25wt% solid content) was added as a dispersant. The mixture was dispersed at 2000rpm for 25min to obtain an oil-in-water suspension. Nitrogen gas was introduced into the reactor to pressurize it to 0.5MPa, and polymerization was carried out at a constant temperature of 60℃ and a rotation speed of 300rpm for 20h. The pressure was then released and the mixture was cooled to room temperature to obtain a fire extinguishing microcapsule suspension. The resulting fire extinguishing microcapsule suspension was filtered and washed three times with deionized water. The sample was then dried in a 60℃ oven for 2h to obtain fire extinguishing microcapsules.

[0060] The obtained fire extinguishing microcapsules were found to have a particle size of 22 μm and a perfluorohexanone content of 72 wt%.

[0061] S2. Mix 670g of fire extinguishing microcapsules, 250g of ethylene-vinyl alcohol copolymer and 80g of water using a mixer to obtain a microcapsule dispersion.

[0062] S3. The microcapsule dispersion is added to a single-screw extruder for melt mixing, extrusion, and granulation. The melt temperature of the screw extruder is 120℃, and the die temperature is 102℃. The resulting water-containing fire extinguishing microcapsule composition particles are dried at 100℃ for 15 hours to obtain the fire extinguishing microcapsule composition. The fire extinguishing microcapsule composition contains 27.0 wt% vinyl alcohol polymer resin and 0.06 wt% water.

[0063] Example 3

[0064] This embodiment prepares a fire extinguishing microcapsule composition, and the specific steps are as follows:

[0065] S1. Using volatile fluorinated fire extinguishing agents and polymers without vinyl alcohol units as raw materials, microcapsules containing fluorinated core materials are prepared using interfacial polymerization technology; specifically:

[0066] 100g melamine, 400g urea, 1500g formaldehyde solution (37wt%), and 1500g deionized water were dissolved and stirred evenly in a reactor. The pH of the solution was adjusted to 9.5 using ammonia. The temperature was slowly raised to 75℃, and the reaction was carried out for 1 hour with stirring at 200 rpm. After cooling, the solution was diluted with 6000g deionized water to obtain a melamine-urea-formaldehyde resin prepolymer solution. 2400g perfluorohexanone was added to 3000g deionized water, along with 3g sodium dodecyl sulfate. The mixture was stirred at 500 rpm for 10 minutes to obtain a perfluorohexanone emulsion.

[0067] The above melamine-urea-formaldehyde resin prepolymer solution was added dropwise to the above perfluorohexanone emulsion, and the temperature was slowly raised to 35°C while hydrochloric acid was slowly added dropwise to adjust the pH to 3.0. 0.5. Slowly heat to 50℃ and cure for 4 hours. Filter, wash, and dry in a 60℃ forced-air drying oven for 3 hours to obtain fire extinguishing microcapsules.

[0068] The obtained fire extinguishing microcapsules were found to have a particle size of 105 μm and a perfluorohexanone content of 85 wt%.

[0069] S2. Mix 670g of fire extinguishing microcapsules, 200g of ethylene-vinyl alcohol copolymer, 150g of water, and 25g of methanol using a mixer to obtain a microcapsule dispersion.

[0070] S3. The microcapsule dispersion is added to a single-screw extruder for melt mixing, extrusion, and granulation. The melt temperature of the screw extruder is 105℃, and the die temperature is 85℃. The resulting water-containing fire extinguishing microcapsule composition particles are dried at 100℃ for 15 hours to obtain the fire extinguishing microcapsule composition. The fire extinguishing microcapsule composition contains 22.5 wt% vinyl alcohol polymer resin and 0.03 wt% water.

[0071] The performance of the fire extinguishing microcapsules prepared in step S1 of Examples 1-3 was tested (using conventional testing methods in the art), and the results are shown in Table 1 below.

[0072] Table 1: Performance Test Results

[0073]

[0074] It can be seen that the fire extinguishing microcapsules prepared in step S1, before the addition of vinyl alcohol polymers, have a high shear core material loss of 13~22wt%, a high heat storage core material loss of 21~33wt%, and a release temperature of 110~132℃, all of which are below 150℃.

[0075] Comparative Example 1

[0076] This comparative example prepares a fire extinguishing microcapsule composition. The specific steps are the same as in Example 1, except that the amount of ethylene-vinyl alcohol copolymer in step S2 is changed to 500g and the amount of water is changed to 150g. All other substances, conditions, and parameters are the same as in Example 1.

[0077] Comparative Example 2

[0078] This comparative example prepares a fire extinguishing microcapsule composition. The specific steps are the same as in Example 1, except that the drying temperature in step S3 is changed to 90°C. All other substances, conditions, and parameters are the same as in Example 1.

[0079] Comparative Example 3

[0080] This comparative example prepares a fire extinguishing microcapsule composition. The specific steps are the same as in Example 1, except that the ethylene-vinyl alcohol copolymer used in step S2 is changed to 30g and the water is changed to 15g. All other substances, conditions, and parameters are the same as in Example 1.

[0081] Comparative Example 4

[0082] This comparative example prepares a fire extinguishing microcapsule composition. The specific steps are the same as in Example 1, except that the ethylene-vinyl alcohol copolymer used in step S2 is changed to 500g, the polypropylene emulsion with a solid content of 50% is changed to 0g, and the water is changed to 0g. All other substances, conditions, and parameters are the same as in Example 1.

[0083] Comparative Example 5

[0084] This comparative example prepares a fire extinguishing microcapsule composition. The specific steps are the same as in Example 1, except that the ethylene-vinyl alcohol copolymer used in step S2 is changed to 500g, the polyurethane emulsion with 50% solid content is changed to 0g, and the water is changed to 0g. All other substances, conditions, and parameters are the same as in Example 1.

[0085] The composition and performance of the microcapsule compositions obtained in Examples 1-3 and Comparative Examples 1-5 were tested, and the results are shown in Table 2 below.

[0086] Table 2: Performance Test Results

[0087]

[0088] After coating the surface of the fire extinguishing microcapsules with vinyl alcohol-based polymers, the shear loss and high-temperature heat storage loss of the core material of the fire extinguishing microcapsule compositions in Examples 1-3 were significantly better than those of fire extinguishing microcapsules without vinyl alcohol-based polymers. The shear loss of the core material was 1-3 wt%, the heat storage loss of the core material was 0.9-1.5 wt%, and the core material release temperature was 175-185°C.

[0089] By comparing Example 1 and Comparative Example 1, it can be seen that although adding too much vinyl alcohol polymer to the fire extinguishing microcapsule composition results in lower core material loss and a higher release temperature of 183°C after shearing and heat storage, the vinyl alcohol polymer content in the composition reaches 41 wt%, and the fire extinguishing microcapsule component in the composition is 59 wt%. The excessively high vinyl alcohol polymer content leads to insufficient content of the corresponding fire extinguishing core material, which is detrimental to the fire extinguishing effect.

[0090] By comparing Example 1 and Comparative Example 2, it can be seen that moisture has a significant impact on the performance of the fire extinguishing microcapsule composition. The water content of the fire extinguishing microcapsule composition in Comparative Example 2 was 1.2 wt%, the core material loss after heat storage was 10 wt%, and the core material leakage was significantly higher than that in Example 1 (0.9 wt).

[0091] Comparing Example 1 and Comparative Example 3, it can be seen that when the content of ethylene alcohol polymer in the fire extinguishing microcapsule composition is too low (4%), the shear loss of the core material is higher than 10 wt%, the core material loss after heat storage is greater than 5 wt%, and the release temperature of the fire extinguishing agent is lower than 150°C.

[0092] Comparing Example 1 with Comparative Examples 4 and 5, it can be seen that when the ethylene alcohol polymer in the fire extinguishing microcapsule composition is replaced with acrylate or polyurethane resin, the shear loss of the core material is higher than 10 wt%, and the core material loss after heat storage is greater than 1 wt%, resulting in a weaker protective effect on the fire extinguishing core material. The fire extinguishing agent release temperature is 130°C. Due to the limited softening temperature of the resin itself, the improvement on the heat resistance of the microcapsule composition is limited.

[0093] Therefore, this invention provides a fire extinguishing microcapsule composition and its preparation method. The composition comprises fire extinguishing microcapsules and a vinyl alcohol-based polymer resin. The fire extinguishing microcapsules contain a core material of a low-boiling-point gaseous or liquid fluorinated fire extinguishing agent. After the microcapsule shell softens or breaks upon heating, the core material fire extinguishing agent can be released to extinguish the fire. The vinyl alcohol-based polymer component coats the surface of the fire extinguishing microcapsule and has extremely high barrier properties, which can significantly reduce leakage loss of the core material during high-temperature storage and use, and improve the storage and service life of the microcapsule composition. At the same time, by using a vinyl alcohol-based polymer resin with a high degree of alcoholysis to coat the outer layer of the fire extinguishing microcapsule, the heat resistance of the fire extinguishing microcapsule can be significantly improved, allowing the core material to be released at higher temperatures.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fire extinguishing microcapsule composition, characterized in that: The composition comprises an inner core-shell microcapsule and an outer vinyl alcohol-based polymer resin layer. The microcapsule consists of a core layer of volatile fluorinated fire extinguishing agent and a shell layer of cross-linked polymer material without vinyl alcohol units. The vinyl alcohol-based polymer resin layer comprises 22.5% to 30% of the total weight of the fire extinguishing microcapsule composition. The shell layer of the microcapsule is one or more combinations of acrylate copolymers, acrylonitrile copolymers, styrene copolymers, melamine-formaldehyde resin, and melamine-urea-formaldehyde resin. The volatile fluorinated fire extinguishing agent is one or more combinations of C3-C8 perfluoroketones, C3-C8 perfluoroalkanes, or methyl nonafluorobutyl ether. The ethylene alcohol-based polymer is an ethylene-ethylene alcohol copolymer; the fire extinguishing microcapsule composition has a fire extinguishing core material release temperature of not less than 150°C, and a water content of less than 1 wt%; The mass loss rate of the fire extinguishing microcapsule composition is 0-20 wt% in the temperature range of 25-120℃; the temperature range with the fastest release rate of the fire extinguishing core material is 170-200℃. The preparation method of the above-mentioned fire extinguishing microcapsule composition includes the following steps: S1. Microcapsules containing fluorinated core materials are prepared using suspension polymerization or interfacial polymerization techniques, with volatile fluorinated fire extinguishing agents and cross-linked polymers without vinyl alcohol units as raw materials, or with volatile fluorinated fire extinguishing agents and polymerizable monomers as raw materials; the core material accounts for 50~95wt% of the total mass of the microcapsules, the fluorine content in the fluorinated core material is 50~80wt%, and the shell thickness is 1~20μm; 1) When using volatile fluorinated fire extinguishing agents and polymerizable monomers as raw materials, the following proportions are calculated by weight, and the specific steps are as follows: 100 parts of polymerizable monomer, 0.01-1 part of crosslinking agent and 0.05-5 parts of free radical initiator are thoroughly mixed and dissolved to obtain an oil phase, which is then added to 200-2000 parts of aqueous phase, followed by 200-800 parts of fluorinated fire extinguishing agent; then 8-150 parts of acidic silica sol are added as a dispersant and dispersed at high speed to obtain an oil-in-water suspension; the polymerization reaction is carried out at 40-80℃ for 5-30 hours under stirring and mixing, the resulting suspension is filtered and rinsed with deionized water, and then dried at 50-80℃ for 1-5 hours. 2) When using volatile fluorinated fire extinguishing agents and cross-linked polymers without vinyl alcohol units as raw materials, the following proportions are calculated by weight, and the specific steps are as follows: Add 200-1000 parts of fluorinated fire extinguishing agent to 600-1200 parts of deionized water, add an emulsifier, and stir to obtain a fire extinguishing agent emulsion; add 800-2100 parts of a crosslinked polymer solution without vinyl alcohol units dropwise to the fire extinguishing agent emulsion, raise the temperature to 30-50℃, and simultaneously slowly add acid to adjust the pH to 3.

0.

1. Slowly heat to 40~70℃, cure for 1~10 hours, filter, wash, and dry at 50~80℃ for 1~5 hours; S2. Disperse the microcapsules obtained in S1 in a vinyl alcohol polymer solution or melt to obtain a microcapsule dispersion; the vinyl alcohol polymer solution or melt contains water or an alcohol polar solvent, the content of which is 5~80wt%; the polar solvent is one or more combinations of water, methanol, ethanol, propanol, isopropanol, n-butanol, and tert-butanol. S3. The microcapsule dispersion is granulated by a screw extruder to obtain fire extinguishing microcapsule composition particles. The die temperature of the screw extruder is 60~130℃. After the fire extinguishing microcapsule composition is stored at 85°C and 65% relative humidity for 7 days, the loss of the core material is no more than 5 wt%; after the fire extinguishing microcapsule composition is subjected to high-speed shearing treatment in an aqueous dispersion, the loss of the core material is no more than 10 wt%.

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