Fire extinguishing microcapsule composition and preparation method thereof

Abstract

The invention discloses a fire extinguishing microcapsule composition and a preparation method thereof, and belongs to the technical field of microcapsule preparation, the fire extinguishing microcapsule composition comprises an inner microcapsule with a core-shell structure and a vinyl alcohol polymer resin layer coating the microcapsule; the microcapsule is composed of a volatile fluorine-containing fire extinguishing agent on a core layer and a cross-linked polymer material which is on a shell layer and does not contain a vinyl alcohol unit. And the content of the vinyl alcohol polymer resin layer is 5-30% of the total weight of the fire-extinguishing microcapsule composition. According to the fire-extinguishing microcapsule composition prepared by the invention, through the synergistic effect of the microcapsule shell layer and the vinyl alcohol polymer resin, the fire-extinguishing microcapsule composition has excellent processing shear resistance and heat storage stability; the outer layer is made of the vinyl alcohol polymer with excellent air tightness and extremely high softening temperature, the release temperature of the core material fire extinguishing agent is remarkably increased, the leakage rate in the storage process is effectively reduced, and therefore the storage life and the service life of the product are greatly prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microcapsule preparation, and in particular to a fire extinguishing microcapsule composition and a preparation method thereof. BACKGROUND

[0002] Microcapsule technology is a technology of wrapping solid, liquid or gas substances in a polymer film, which is widely used in daily chemicals, food industry, biomedical and polymer material additives, etc. In the field of fire fighting, microencapsulating fire extinguishing agents can realize stable storage and target temperature triggered release, which is of great significance for automatic extinguishing of early fire.

[0003] At present, for the initial fire in a narrow and closed space (such as a power distribution cabinet or an energy storage station), some studies have tried to microencapsulate fire extinguishing agents. For example, in the invention patent with the patent name of “Perfluorohexanone fire extinguishing microcapsule and preparation method thereof” and the publication number of CN118649393A, a gelatin / montmorillonite / sodium polyphosphate complex is used as the inner shell layer, and a polyisocyanate / phenolic resin is used as the outer shell layer to wrap the low-boiling liquid perfluorohexanone core material. Although the mechanical properties of the fire extinguishing microcapsule are improved by the inorganic material doping and the double-shell structure, the fire extinguishing core material begins to leak obviously before 80℃, and the thermal stability is insufficient. For example, in the prior art, P(AN-MMA) copolymer is used as the shell layer to successfully prepare microcapsules wrapping low-boiling gas HFC-236fa by the suspension polymerization method. Although this technology realizes the encapsulation of low-boiling gas, the gas tightness and heat resistance of the shell material are limited, resulting in a low release temperature of the fire extinguishing agent. In a high-temperature environment in summer (such as the internal temperature of a vehicle or a power distribution box can reach more than 70℃), the core material is prone to slow leakage, resulting in a decrease in fire extinguishing capacity. At the same time, when a fire occurs, the excessively low release temperature causes the fire extinguishing agent to be released too early before reaching the core area of the flame, which seriously affects the fire extinguishing efficiency.

[0004] In addition, the existing fire extinguishing microcapsules generally lack attention to the resistance to processing shear, which leads to easy damage during actual application processes such as dispersion and blending, thereby limiting the universality of the application scenarios.

[0005] Based on the above problems, a fire extinguishing microcapsule composition with high release temperature, excellent storage stability and good resistance to processing shear is proposed. SUMMARY

[0006] The purpose of the present application is to provide a fire extinguishing microcapsule composition and a preparation method thereof to solve the problems in the background art.

[0007] To achieve the above object, the present application provides a fire extinguishing microcapsule composition, comprising a microcapsule with a core-shell structure in an inner layer and a vinyl alcohol-based polymer resin layer coated on the outside of the microcapsule; the microcapsule is composed of a volatile fluorine-containing extinguishing agent in a core layer and a cross-linked polymer material without vinyl alcohol units in a shell layer; the content of the vinyl alcohol-based polymer resin layer is 5-30% of the total weight of the fire extinguishing microcapsule composition.

[0008] Preferably, the vinyl alcohol-based polymer is one or a combination of polyvinyl alcohol, vinyl alcohol-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer.

[0009] Preferably, the shell layer of the microcapsule is a thermoplastic polymer or a thermosetting polymer, which is one or a combination of acrylate copolymer, methacrylate copolymer, acrylonitrile copolymer, styrene copolymer, melamine formaldehyde resin, and melamine urea formaldehyde resin.

[0010] Preferably, the volatile fluorine-containing extinguishing agent has a boiling point of not higher than 120°C at normal pressure, and is one or a combination of C3-C8 perfluoroketone, C3-C8 perfluoroalkane, or methyl nonafluorobutyl ether.

[0011] The present application also provides a preparation method of the fire extinguishing microcapsule composition, comprising the following steps: S1, using a volatile fluorine-containing extinguishing agent and a cross-linked polymer or a polymerizable monomer without vinyl alcohol units as raw materials, a microcapsule containing fluorine-containing core material is prepared by using suspension polymerization or interfacial polymerization technology; S2, dispersing the microcapsule obtained in S1 in a vinyl alcohol-based polymer solution or melt to obtain a microcapsule dispersion, and the amount of the vinyl alcohol-based polymer in the dispersion is 5-30% of the total amount of the microcapsule and the vinyl alcohol-based polymer; S3, granulating the microcapsule dispersion through a screw extruder to form fire extinguishing microcapsule composition particles.

[0012] Preferably, in S1, the mass of the core material in the microcapsule accounts for 50-95wt% of the total mass of the microcapsule, the mass of fluorine in the fluorine-containing core material accounts for 50-80wt%, and the thickness of the shell layer is 1-20μm.

[0013] Preferably, the thickness of the shell layer in the microcapsule is 2-10μm, and a too high thickness of the shell layer will result in insufficient core material content and reduced fire extinguishing performance; a too low thickness of the shell layer will result in insufficient strength of the microcapsule, and the microcapsule will be damaged and the core material will leak due to insufficient shear resistance in the actual application of dispersion, blending, and other processes.

[0014] Preferably, in the S1, the fluorine-containing core material is one or more of perfluoroacetone, perfluorobutanone, perfluoropentanone, perfluorohexanone, perfluoropropane, perfluorobutane, perfluoropentane, perfluorohexane, perfluoroheptane, perfluorooctane, hexafluoropropane, heptafluoropropane and methyl nonafluorobutyl ether.

[0015] Preferably, in the S2, the ethylene vinyl alcohol polymer solution or melt contains water or an alcohol polar solvent, and the content of the polar solvent is 5-80wt%.

[0016] Preferably, the polar solvent is one or more of water, methanol, ethanol, propanol, isopropanol, n-butanol and tert-butanol.

[0017] Preferably, in the S3, the die temperature of the screw extruder is 60-130℃.

[0018] Preferably, the mass content of sodium in the fire extinguishing microcapsule composition is 1-1000ppm, and the particle size of the fire extinguishing microcapsule is 5-200μm.

[0019] Preferably, after the fire extinguishing microcapsule composition is stored at 85℃ and 65% relative humidity for 7 days, the loss of the core material is not more than 5wt%.

[0020] Preferably, after the fire extinguishing microcapsule composition is subjected to high-speed shearing treatment in a water dispersion, the loss of the core material is not more than 10wt%.

[0021] Preferably, the release temperature of the fire extinguishing core material of the fire extinguishing microcapsule composition is not lower than 150℃, and the water content of the fire extinguishing microcapsule composition is less than 1wt%.

[0022] Preferably, the fire extinguishing microcapsule composition has high heat resistance, and the relationship between the mass of the fire extinguishing microcapsule composition and temperature is measured by thermogravimetric analysis at a temperature program of 20℃ / min. The release speed and release amount of the fire extinguishing agent core material can be reflected by the change of the mass of the fire extinguishing microcapsule composition with temperature, specifically: the mass loss rate of the fire extinguishing microcapsule composition in the temperature range of 25-120℃ is 0-30wt%; and the temperature range with the fastest release rate of the fire extinguishing core material is 150-230℃.

[0023] Preferably, the mass loss rate of the fire extinguishing microcapsule composition in the temperature range of 25-120℃ is 0-20wt%; and the temperature range with the fastest release rate of the fire extinguishing core material is 170-200℃.

[0024] Therefore, the fire extinguishing microcapsule composition and the preparation method thereof have the following beneficial effects: (1) The microcapsule composition is composed of inner layer fire extinguishing microcapsules and outer layer ethylene vinyl alcohol polymer resin, the fire extinguishing microcapsules contain low boiling point gas or liquid fluorine-containing fire extinguishing agent core material, which can release the core material fire extinguishing agent after the microcapsule shell softens or is damaged under heat, so as to achieve fire extinguishing, the ethylene vinyl alcohol polymer is coated on the surface of the fire extinguishing microcapsule and has extremely high barrier property, 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.

[0025] (2) The present application significantly improves the release temperature (not less than 150 DEG C) of the core material fire extinguishing agent by coating the outer layer with ethylene vinyl alcohol polymer resin with excellent air tightness, extremely high softening temperature and high alcoholysis degree, so that the core material can be released at a higher temperature, effectively avoiding the premature release of the fire extinguishing agent in the non-target high temperature area, ensuring that the fire extinguishing agent can accurately act on the core area of the flame, thereby greatly improving the fire extinguishing efficiency.

[0026] (3) The outer layer of ethylene vinyl alcohol polymer provides extremely high gas barrier property, which cooperates with the shell layer of the microcapsule to significantly reduce the leakage amount of the core material in high temperature and high humidity storage environment, greatly prolonging the storage life of the product; and can withstand high speed shearing treatment, so that it is not easy to be damaged in actual application process (such as dispersion, blending), widening its processing adaptability and application scene in various polymer matrices.

[0027] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The thermogravimetric curve and derivative thermogravimetric curve of the present application example 1. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and examples.

[0030] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments.

[0031] The present application provides a specific preparation method of fire extinguishing microcapsule composition, including the following steps: S1, using volatile fluorine-containing extinguishing agent and cross-linked polymer without vinyl alcohol unit as raw materials or using volatile fluorine-containing extinguishing agent and polymerizable monomer as raw materials, microcapsules containing fluorine-containing core material are prepared by using suspension polymerization or interfacial polymerization technology, the mass of the core material in the microcapsules accounts for 50-95wt% of the total mass of the microcapsules, the mass of fluorine element in the fluorine-containing core material accounts for 50-80wt%, and the shell thickness is 1-20μm.

[0032] 1) when using volatile fluorine-containing extinguishing agent and polymerizable monomer as raw materials, the specific steps are as follows (the following parts are by weight): 100 parts of polymerizable monomer, 0.01-1 parts of cross-linking agent and 0.05-5 parts of free radical initiator are fully mixed and dissolved to obtain an oil phase, which is added to 200-2000 parts of water phase, then 200-800 parts of fluorine-containing extinguishing agent is added; then 8-150 parts of acidic silica sol is added as a dispersant, and high-speed dispersion is carried out to obtain an oil-in-water suspension; under stirring and mixing, polymerization reaction is carried out at 40-80℃ for 5-30h, the obtained suspension is filtered and washed with deionized water, and then dried at 50-80℃ for 1-5h.

[0033] 2) when using volatile fluorine-containing extinguishing agent and cross-linked polymer without vinyl alcohol unit as raw materials, the specific steps are as follows (the following parts are by weight): 200-1000 parts of fluorine-containing extinguishing agent is added to 600-1200 parts of deionized water, an emulsifier is added, and stirring is carried out to obtain an extinguishing agent emulsion; 800-2100 parts of cross-linked polymer solution without vinyl alcohol unit is added dropwise to the extinguishing agent emulsion, the temperature is raised to 30-50℃, and at the same time, acid is slowly added to adjust the pH value to 3.0 1. Slowly raise the temperature to 40-70℃, solidify for 1-10h, filter, wash, and dry at 50-80℃ for 1-5h.

[0034] S2, the microcapsules obtained in S1 are dispersed in a vinyl alcohol-based polymer solution or melt to obtain a microcapsule dispersion, the amount of the vinyl alcohol-based polymer in the dispersion accounts for 5-30% of the total amount of the microcapsules and the vinyl alcohol-based polymer; the vinyl alcohol-based polymer solution or melt contains water or an alcohol polar solvent, and the content of the polar solvent is 5-80wt%; the polar solvent is one or a combination of more than one of water, methanol, ethanol, propanol, isopropanol, n-butanol and tert-butanol.

[0035] S3, the microcapsule dispersion is granulated and formed into extinguishing microcapsule composition particles by a screw extruder; the die temperature of the screw extruder is 60-130℃.

[0036] The above method is further described in combination with specific examples.

[0037] Example 1 An extinguishing microcapsule composition is prepared by the following steps: S1, using volatile fluorine-containing extinguishing agent and cross-linkable monomer without vinyl alcohol unit as raw materials, a microcapsule containing fluorine-containing core material is prepared by suspension polymerization; specifically: 1500g of sodium chloride is added to 12000g of deionized water, and dissolved to obtain an aqueous phase; 300g of methyl methacrylate, 1200g of acrylonitrile and 15g of azobisisobutyronitrile are added and dissolved to obtain an oil phase.

[0038] The aqueous phase and the oil phase are poured into a high-pressure reaction kettle in sequence, 4500g of hexafluoropropane gas is introduced, and then 800g of acidic silica sol (25wt% solid content) is added as a dispersant, and dispersed at a speed of 1500rpm for 25min to obtain an oil-in-water suspension emulsion.

[0039] Nitrogen is introduced into the above reaction kettle to pressurize to 1Mpa, and the polymerization reaction is carried out at a constant temperature of 60℃ and a speed of 300rpm for 20h; the extinguishing microcapsule suspension obtained by reaction is filtered and washed with deionized water three times, and the sample is placed in a 60℃ oven for drying for 2h to obtain the extinguishing microcapsule.

[0040] The detection shows that the particle size of the obtained extinguishing microcapsule is 51μm, and the content of hexafluoropropane is 66wt%.

[0041] S2, 670g of extinguishing microcapsule, 250g of ethylene-vinyl alcohol copolymer and 50g of water are uniformly mixed by using a mixer to obtain a microcapsule dispersion.

[0042] S3, the microcapsule dispersion is added to a single screw extruder for melt mixing, extrusion and granulation, the melting section temperature of the screw extruder is 135℃, and the die temperature is 115℃. The water-containing extinguishing microcapsule composition particles obtained after extrusion are dried at 100℃ for 15h to obtain the extinguishing microcapsule composition, and the content of the vinyl alcohol polymer resin in the extinguishing microcapsule composition is 27.2wt%, and the water content is 0.05wt%.

[0043] The product in Example 1 is detected for core material content and core material release temperature, and the detection method adopts thermal gravimetric analysis TGA to obtain a thermal gravimetric curve. In the curve, the mass loss in the range of 30~250℃ is taken as the mass of the extinguishing agent core material according to the relationship between the sample weight and the temperature. The inflection point of the thermal gravimetric curve is taken as the release temperature of the core material, and the results are shown in Figure 1

[0044] Example 2 An extinguishing microcapsule composition is prepared by the following steps: ​S1, using volatile fluorine-containing extinguishing agent and cross-linkable monomer without vinyl alcohol unit as raw materials, microcapsules containing fluorine-containing core material are prepared by suspension polymerization; specifically: 1500g of sodium chloride is added to 12000g of deionized water, and dissolved sufficiently to obtain an aqueous phase; 500g of methyl methacrylate, 1000g of trifluoroethyl methacrylate, 4500g of perfluorohexanone and 15g of azobisisobutyronitrile are added to a glass bottle, and dissolved sufficiently to obtain an oil phase.

[0045] The aqueous phase and the oil phase are poured into a high-pressure reaction kettle in sequence, and then 500g of silica sol (25wt% solid content) is added as a dispersant, and dispersed at a speed of 2000rpm for 25min to obtain an oil-in-water suspension emulsion. Nitrogen is introduced into the above reaction kettle to pressurize to 0.5Mpa, and the polymerization reaction is carried out at a constant temperature of 60℃ and a speed of 300rpm for 20h, and then depressurized and cooled to room temperature to obtain an extinguishing microcapsule suspension. The extinguishing microcapsule suspension obtained by reaction is filtered and washed with deionized water three times, and the sample is placed in a 60℃ oven for drying for 2h to obtain extinguishing microcapsules.

[0046] It is detected that the particle size of the obtained extinguishing microcapsules is 22μm, and the perfluorohexanone content is 72wt%.

[0047] S2, 670g of extinguishing microcapsules, 250g of ethylene-vinyl alcohol copolymer and 80g of water are uniformly mixed using a mixer to obtain a microcapsule dispersion.

[0048] S3, the microcapsule dispersion is added to a single screw extruder for melt mixing, extrusion and granulation, the melting section temperature of the screw extruder is 120℃, and the die temperature of the screw extruder is 102℃. The water-containing extinguishing microcapsule composition particles obtained after extrusion are dried at 100℃ for 15h to obtain an extinguishing microcapsule composition, and the content of the vinyl alcohol polymer resin in the extinguishing microcapsule composition is 27.0wt%, and the water content is 0.06wt%.

[0049] Example 3 An extinguishing microcapsule composition is prepared in this example, and the specific steps are as follows: S1, using volatile fluorine-containing extinguishing agent and cross-linkable monomer without vinyl alcohol unit as raw materials, microcapsules containing fluorine-containing core material are prepared by suspension polymerization; specifically: The 100 g melamine, 400 g urea, 1500 g formaldehyde solution (mass concentration of 37 wt%), 1500 g deionized water were stirred and dissolved uniformly in a reaction kettle, the pH value of the solution was adjusted to 9.5 using ammonia water, slowly heated to 75℃, cooled after reaction for 1 h under the condition of 200 rpm stirring, and diluted with 6000 g deionized water to prepare a melamine urea-formaldehyde resin prepolymer solution. 2400 g perfluorohexanone was added to 3000 g deionized water, 3 g sodium dodecyl sulfate was added, and 500 rpm stirring was carried out for 10 min to obtain a perfluorohexanone emulsion.

[0050] The above-mentioned melamine urea-formaldehyde resin prepolymer solution was added dropwise to the above-mentioned perfluorohexanone emulsion, slowly heated to 35℃, and at the same time, hydrochloric acid was slowly added to adjust the pH value to 3.0 0.5. Slowly heated to 50℃, and cured for 4 h. Filtration, washing, and drying in a 60℃ air-drying oven for 3 h to obtain fire extinguishing microcapsules.

[0051] The detection showed that the particle size of the obtained fire extinguishing microcapsules was 105 μm, and the perfluorohexanone content was 85 wt%.

[0052] S2, 670 g fire extinguishing microcapsules, 200 g ethylene-vinyl alcohol copolymer, 150 g water, and 25 g methanol were uniformly mixed using a mixer to obtain a microcapsule dispersion.

[0053] S3, the microcapsule dispersion was added to a single screw extruder for melt mixing, extrusion, and granulation. The melting section temperature of the screw extruder was 105℃, and the die temperature was 85℃. The obtained water-containing fire extinguishing microcapsule composition particles after extrusion were dried at 100℃ for 15 h to obtain a fire extinguishing microcapsule composition. The content of the ethylene-vinyl alcohol polymer resin in the fire extinguishing microcapsule composition was 22.5 wt%, and the water content was 0.03 wt%.

[0054] The fire extinguishing microcapsules prepared in step S1 of Examples 1-3 were respectively detected for performance (using conventional detection methods in the art), and the results are shown in Table 1 below.

[0055] Table 1: Performance detection results

[0056] It can be seen that the fire extinguishing microcapsules prepared in step S1, before adding the ethylene-vinyl alcohol polymer, had a high shear core material loss of 13-22 wt%, a high thermal storage core material loss of 21-33 wt%, and a release temperature of 110-132℃, all of which were lower than 150℃.

[0057] Comparative Example 1 A fire extinguishing microcapsule composition was prepared in the same manner as in Example 1, except that the amount of ethylene-vinyl alcohol copolymer used in step S2 was modified to 500 g and the amount of water was modified to 150 g. The other substances, conditions and parameters were the same as in Example 1.

[0058] Comparative Example 2 A fire extinguishing microcapsule composition was prepared in the same manner as in Example 1, except that the drying temperature in step S3 was modified to 90°C. The other substances, conditions and parameters were the same as in Example 1.

[0059] Comparative Example 3 A fire extinguishing microcapsule composition was prepared in the same manner as in Example 1, except that the amount of ethylene-vinyl alcohol copolymer used in step S2 was modified to 30 g and the amount of water was modified to 15 g. The other substances, conditions and parameters were the same as in Example 1.

[0060] Comparative Example 4 A fire extinguishing microcapsule composition was prepared in the same manner as in Example 1, except that the amount of ethylene-vinyl alcohol copolymer used in step S2 was modified to 500 g, the amount of 50% solid content polyacrylate emulsion was modified to 500 g, and the amount of water was modified to 0 g. The other substances, conditions and parameters were the same as in Example 1.

[0061] Comparative Example 5 A fire extinguishing microcapsule composition was prepared in the same manner as in Example 1, except that the amount of ethylene-vinyl alcohol copolymer used in step S2 was modified to 500 g, the amount of 50% solid content polyurethane emulsion was modified to 500 g, and the amount of water was modified to 0 g. The other substances, conditions and parameters were the same as in Example 1.

[0062] The compositions and properties of the microcapsule compositions obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were tested, and the results are shown in Table 2 below.

[0063] Table 2: Results of property testing

[0064] After the ethylene-vinyl alcohol polymer was coated on the surface of the fire extinguishing microcapsules, the shear and high-temperature heat storage loss of the core material of the fire extinguishing microcapsule compositions of Examples 1 to 3 was significantly better than that of the fire extinguishing microcapsules not containing the ethylene-vinyl alcohol polymer, with a shear core material loss of 1 to 3 wt%, a heat storage core material loss of 0.9 to 1.5 wt%, and a core material release temperature of 175 to 185°C.

[0065] By comparing Example 1 and Comparative Example 1, it can be seen that too much vinyl alcohol polymer is added in the fire extinguishing microcapsule composition, although the loss of core material after shearing and heat storage is lower and the release temperature is higher at 183℃, but the content of vinyl alcohol polymer in the composition reaches 41wt%, and the content of fire extinguishing microcapsule component in the composition is 59wt%, the content of vinyl alcohol polymer is too high, and the content of corresponding fire extinguishing core material is insufficient, which is not conducive to the fire extinguishing effect.

[0066] By comparing Example 1 and Comparative Example 2, it can be seen that water has a huge impact on the performance of the fire extinguishing microcapsule composition. The water content of the fire extinguishing microcapsule composition in Comparative Example 2 is 1.2wt%, and the loss of core material after heat storage is 10wt%, which is significantly higher than the leakage of core material of 0.9wt% in Example 1.

[0067] Comparing Example 1 with Comparative Example 3, it can be seen that when the content of vinyl alcohol polymer in the fire extinguishing microcapsule composition is too low (4%), the loss of core material after shearing is higher than 10wt%, the loss of core material after heat storage is greater than 5wt%, and the release temperature of the fire extinguishing agent is lower than 150℃.

[0068] Comparing Example 1 with Comparative Example 4 and Comparative Example 5, it can be seen that when the vinyl alcohol polymer in the fire extinguishing microcapsule composition is replaced by acrylate or polyurethane resin, the loss of core material after shearing is higher than 10wt%, the loss of core material after heat storage is greater than 1wt%, the protection effect on the fire extinguishing core material is weaker, the release temperature of the fire extinguishing agent is 130℃, and the heat resistance of the microcapsule composition is limited due to the limited softening temperature of the resin itself.

[0069] Therefore, the fire extinguishing microcapsule composition and the preparation method thereof, the composition comprises fire extinguishing microcapsules and vinyl alcohol polymer resin, the fire extinguishing microcapsules comprise low-boiling-point gas or liquid fluorine-containing fire extinguishing agent core material, which can release the core material fire extinguishing agent after the microcapsule shell layer softens or is damaged, thereby achieving fire extinguishing; the vinyl alcohol polymer component is coated on the surface of the fire extinguishing microcapsules and has high barrier property, 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. At the same time, after the high alcoholysis degree vinyl alcohol polymer resin is selected to coat the outer layer of the fire extinguishing microcapsules, the heat resistance of the fire extinguishing microcapsules can be significantly improved, so that the core material can be released at a higher temperature.

[0070] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A fire extinguishing microcapsule composition, characterized in that: it comprises microcapsules with a core-shell structure comprising an inner layer and a vinyl alcohol-based polymer resin layer coated on the outside of the microcapsules; the microcapsules are composed of a volatile fluorine-containing fire extinguishing agent as the core layer and a cross-linked polymer material without vinyl alcohol units as the shell layer; and the content of the vinyl alcohol-based polymer resin layer is 5-30% of the total weight of the fire extinguishing microcapsule composition. The vinyl alcohol-based polymer is one or a combination of polyvinyl alcohol, vinyl alcohol-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, and ethylene-vinyl alcohol-vinyl acetate copolymer.

2. A fire extinguishing microcapsule composition according to claim 1, characterised in that: The shell layer of the microcapsule is one or a combination of acrylate copolymer, methacrylate copolymer, acrylonitrile copolymer, styrene copolymer, melamine formaldehyde resin, and melamine urea formaldehyde resin.

3. A fire extinguishing microcapsule composition according to claim 1, wherein: The volatile fluorine-containing fire extinguishing agent is one or a combination of C3-C8 perfluoroketone, C3-C8 perfluoroalkane, or methyl nonafluorobutyl ether.

4. A fire extinguishing microcapsule composition according to claim 1, wherein: The method comprises the following steps:

5. A process for the preparation of a fire extinguishing microcapsule composition according to any one of claims 1 to 4, characterized in that, S1. Using a volatile fluorine-containing fire extinguishing agent and a cross-linked polymer without vinyl alcohol units as raw materials or using a volatile fluorine-containing fire extinguishing agent and a polymerizable monomer as raw materials, microcapsules containing fluorine-containing core materials are prepared using suspension polymerization or interfacial polymerization technology; S2. The microcapsules obtained in S1 are dispersed in a vinyl alcohol-based polymer solution or melt to obtain a microcapsule dispersion; S3. The microcapsule dispersion is granulated into fire extinguishing microcapsule composition particles by a screw extruder. In S1, the mass of the core material in the microcapsules accounts for 50-95wt% of the total mass of the microcapsules, and the shell layer thickness is 1-20μm.

6. The method of claim 5, wherein: In S2, the vinyl alcohol-based polymer solution or melt contains water or an alcohol polar solvent, and the content of the polar solvent is 5-80wt%.

7. The method of claim 6, wherein: After the fire extinguishing microcapsule composition is stored at 85℃ and 65% relative humidity for 7 days, the loss of the core material is not more than 5wt%.

8. The method of claim 7, wherein: After the fire extinguishing microcapsule composition is subjected to high-speed shearing treatment in an aqueous dispersion, the loss of the core material is not more than 10wt%.

9. The method of claim 8, wherein: The release temperature of the fire extinguishing core material of the fire extinguishing microcapsule composition is not less than 150℃, and the water content of the fire extinguishing microcapsule composition is less than 1wt%.

10. The method of claim 9, wherein: ​

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