Fire extinguishing microcapsule, patch and preparation method and application thereof

Abstract

The application discloses the technical field of fire extinguishing materials, and discloses fire extinguishing microcapsules, a fire extinguishing patch and a preparation method and application thereof. The fire extinguishing microcapsules are composed of a capsule core and a capsule wall coated on the surface of the capsule core, wherein the preparation raw material of the capsule core comprises, in terms of mass fraction, 40-60 parts of perfluorohexanone, 4-10 parts of perfluoropropyl methyl ether, 50-80 parts of microcarriers and 0.5-2 parts of an adhesive, and the capsule wall is polyurea-formaldehyde resin. The fire extinguishing microcapsules produced by the formula process of the application have excellent embedding efficiency (>85%) and a low response temperature (<80℃), and the capsule wall has high compactness and good storage stability; as fire extinguishing materials, the fire extinguishing microcapsules can quickly break at the initial stage of a fire to form a comprehensive fire extinguishing aerosol, which helps to realize early intervention on the fire. In addition, the fire extinguishing microcapsules can also be used to prepare fire extinguishing patches to realize "non-self-starting" fire extinguishing, and have very excellent application prospects.

Description

Technical Field

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

[0002] Fire extinguishing microcapsules are tiny capsules formed by encapsulating volatile liquid droplets (such as perfluorohexanone) or solid particles with polymer materials using physical or chemical methods. The solid or liquid substance encapsulating the capsule is called the core material, and the membrane formed by the polymer material is called the wall material. Microcapsules can isolate the substance in the core from the external environment, extending the shelf life of unstable and volatile substances. Their small size greatly expands their application scenarios, allowing them to be integrated into enclosed or confined spaces such as battery packs, building materials, and power cabinets through pre-embedding or pre-coating. This enables "self-starting" fire extinguishing, where the capsule wall ruptures when the ambient temperature abnormally rises to a specific threshold, releasing the extinguishing agent instantly and extinguishing the fire in its early stages.

[0003] In related technologies, perfluorohexanone is typically coated onto a polymer capsule to create microcapsule fire extinguishing particles, such as urea-formaldehyde resin, polyurethane, or gelatin. However, several technical bottlenecks remain. For example, the coating effect of the capsule wall is not ideal, resulting in a low coating rate. Perfluorohexanone has a boiling point of only 49.2℃, making it highly susceptible to volatilization loss during microcapsule preparation (especially aqueous polymerization). This leads to a significant amount of extinguishing agent not being effectively coated, severely impacting extinguishing efficiency and increasing costs. To further improve the coating effect, the thickness of the capsule wall is usually increased. However, this easily leads to a high thermal response temperature and insufficient release rate of the microcapsule. In addition, the thermal stability of the capsule wall itself also affects the release of the core material. Polymer capsule walls typically possess good thermal stability and mechanical properties, resulting in a rupture temperature (usually above 90℃) much higher than the boiling point of perfluorohexanone. This causes a delayed extinguishing response, preventing rapid suppression in the early stages of a fire. At the same time, a single core (such as a liquid core) lacks an effective dispersion mechanism when released, making it difficult to form a comprehensive fire extinguishing aerosol.

[0004] Therefore, there is an urgent need to develop a fire extinguishing microcapsule with a simple preparation process, high coating rate, and rapid response even at low temperatures, as well as its preparation method. Summary of the Invention

[0005] The first objective of this invention is to provide a fire extinguishing microcapsule that can rapidly rupture at low temperatures, helping to quickly interrupt the occurrence of a fire in its early stages and thus preventing more serious disasters.

[0006] The second objective of this invention is to provide a method for preparing fire extinguishing microcapsules.

[0007] The third objective of this invention is to provide a fire extinguishing patch.

[0008] The fourth aspect of this invention is to provide a method for preparing a fire extinguishing patch.

[0009] The fifth aspect of this invention aims to provide an application of fire extinguishing microcapsules or fire extinguishing patches in the preparation of fire extinguishing materials.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a fire extinguishing microcapsule, the fire extinguishing microcapsule comprising a core and a capsule wall covering the surface of the core, wherein the raw materials for preparing the core, by mass parts, comprise: 40-60 parts of perfluorohexanone, 4-10 parts of perfluoropropyl methyl ether, 50-80 parts of microcarrier and 0.5-2 parts of adhesive. The capsule wall is made of polyurea-formaldehyde resin.

[0011] The fire extinguishing microcapsules of this invention have at least the following beneficial effects: (1) The fire extinguishing microcapsule of the present invention is composed of a core and a capsule wall covering the surface of the core. The core uses a microcarrier (such as micro-powdered silica gel) as a solid dispersion component, and is combined with high-boiling-point perfluorohexanone (49°C) and low-boiling-point perfluoropropyl methyl ether (34°C). When heated, the solid microcarrier provides a large surface area and an efficient heat conduction pathway, which can assist the liquid fire extinguishing component to vaporize rapidly. The low-boiling-point perfluoropropyl methyl ether can generate a high vapor pressure environment first in the capsule wall. Perfluorohexanone vaporizes at a slightly higher temperature, generating a larger volume expansion and forming a second wave of pressure peak. Through continuous pressure accumulation, the response temperature can be significantly reduced, the response time can be shortened, and a more intense and dispersed release effect can be achieved.

[0012] (2) This invention uses polyurea-formaldehyde resin as the capsule wall. The cross-linked network structure of polyurea-formaldehyde resin is very tight, with high density and solvent resistance, which can prevent the volatilization and leakage of volatile components (such as perfluorohexanone and perfluoropropyl methyl ether) in the capsule core, thus helping to improve storage stability. In addition, using polyurea-formaldehyde resin to coat the capsule core has a good coating effect, with a core embedding rate of >85%, which helps to improve the fire extinguishing effect.

[0013] In some embodiments of the present invention, the particle size of the microcarrier is 10~100μm. Preferably, it is 10~50μm.

[0014] In some embodiments of the present invention, the microcarrier is selected from at least one of micronized silica gel, diatomaceous earth, and nano-silica aerogel.

[0015] In some embodiments of the present invention, the adhesive is selected from at least one of β-cyclodextrin, dextrin, α-cyclodextrin, and γ-cyclodextrin.

[0016] In some embodiments of the present invention, the raw materials for preparing the core include, by mass parts: 45-55 parts of perfluorohexanone, 4-10 parts of perfluoropropyl methyl ether, 55-70 parts of microcarrier, and 0.5-2 parts of adhesive.

[0017] In some embodiments of the present invention, the mass ratio of perfluorohexanone to perfluoropropyl methyl ether is 45~55:4~10.

[0018] In the fire extinguishing microcapsule core of the present invention, perfluorohexanone serves as the main fire extinguishing agent, which can achieve efficient fire extinguishing through a dual mechanism of endothermic reaction and chemical interruption of chain reaction. Perfluoropropyl methyl ether mainly serves as a propellant. Its boiling point is extremely low (34°C), and it can vaporize violently when the temperature just exceeds its boiling point, providing early and strong pressure to the inside of the microcapsule for bursting the capsule wall. However, when its content is too high, it can generate a high vapor pressure at room temperature, which is not conducive to room temperature storage and may cause the inside of the microcapsule to burst due to excessive expansion during storage.

[0019] In some embodiments of the present invention, the raw materials for preparing the polyurea-formaldehyde resin include formaldehyde, urea, melamine, curing agent and polymeric dispersant.

[0020] In some embodiments of the present invention, the curing agent is selected from at least one of resorcinol and ammonium chloride.

[0021] In some embodiments of the present invention, the polymeric dispersant is selected from at least one of styrene-maleic anhydride copolymer, polyvinyl alcohol, and polyvinylpyrrolidone.

[0022] In some embodiments of the present invention, the raw materials for preparing the polyurea-formaldehyde resin include, by mass parts, 25-30 parts formaldehyde, 10-15 parts urea, 7-8 parts melamine, 0.5-1.5 parts curing agent and 1-3 parts polymeric dispersant.

[0023] In some embodiments of the present invention, the mass ratio of formaldehyde to urea is 27.5:12~14.

[0024] The molar ratio of urea to formaldehyde directly affects the structure and molecular weight of the prepolymer. A higher urea ratio means more amino groups to capture formaldehyde, generating more linear or branched low molecular weight prepolymers. These low molecular weight prepolymers have better fluidity and can migrate to the interface and complete the coating more quickly, which is beneficial to improving the coating efficiency.

[0025] In some embodiments of the present invention, the raw materials for preparing the polyurea-formaldehyde resin also include polyethylene glycol.

[0026] This invention discovers that adding a small amount of flexible polymer (such as polyethylene glycol PEG-400) to the polyurethane prepolymerization reaction helps to improve the coating effect. It is speculated that this is because these flexible polymer segments can act as "toughening agents" and be inserted into the rigid network of urea-formaldehyde resin, thereby improving the toughness and film-forming properties of the shell, so that it can better adapt to the shape of the core during curing and form a more airtight encapsulation.

[0027] In some embodiments of the present invention, the amount of polyethylene glycol added is 0.5 to 1.5 parts by weight.

[0028] In some embodiments of the present invention, the encapsulation rate of the core is greater than 85%. Preferably, the encapsulation rate of the core is 85% to 95%.

[0029] In some embodiments of the present invention, the average particle size of the fire extinguishing microcapsules is 400~850μm.

[0030] A second aspect of the present invention provides a method for preparing the fire extinguishing microcapsules described in the first aspect, comprising the following steps: S1. Mix the raw materials for preparing the core to obtain a solid composite core; S2. Mix the formaldehyde, urea and melamine, adjust the pH value to 8-9, and react to obtain a prepolymer solution; S3. Mix the prepolymer solution, the dispersion containing the polymeric dispersant, and the curing agent, then add the solid composite core, adjust the pH value to 3-4, and after curing and washing, collect the solid phase and dry it to obtain the final product.

[0031] In some embodiments of the present invention, in step S3, the concentration of the polymeric dispersant in the dispersion containing the polymeric dispersant is 0.5~1.5wt%.

[0032] In some embodiments of the present invention, the raw materials for preparing the polyurea-formaldehyde resin include, by mass parts, 25-30 parts formaldehyde, 10-15 parts urea, 7-8 parts melamine, 0.5-1.5 parts curing agent and 1-3 parts polymeric dispersant.

[0033] In some embodiments of the present invention, step S2 further includes the addition of polyethylene glycol.

[0034] Preferably, the polyethylene glycol is in the form of 0.5 to 1.5 parts by mass.

[0035] In some embodiments of the present invention, in step S3, the mass fraction of the solid composite core is 75 to 90 parts.

[0036] In some embodiments of the present invention, the pH value of the dispersion is 9 to 11.

[0037] In some embodiments of the present invention, the curing temperature is below 30°C.

[0038] In some embodiments of the present invention, the curing time is 2 to 6 hours.

[0039] In a third aspect, the present invention provides a fire extinguishing patch, the raw materials for which are prepared, including the fire extinguishing microcapsules described in the first aspect.

[0040] In some embodiments of the present invention, the raw materials for preparing the fire extinguishing patch also include an adhesive.

[0041] In some embodiments of the present invention, the raw materials for preparing the adhesive include polyurethane prepolymer, isocyanate curing agent and photoinitiator.

[0042] In some embodiments of the present invention, the raw materials for preparing the adhesive include, by weight parts: 80-120 parts of polyurethane prepolymer, 10-20 parts of isocyanate curing agent and 2-5 parts of photoinitiator.

[0043] In some embodiments of the present invention, the raw materials for preparing the polyurethane prepolymer include isophorone diisocyanate (IPDI), polytetrahydrofuran ether diol (PTMG-1000) and hydroxyethyl acrylate (HEA), with a molar ratio of 2.5~3.5:1:1.5~2.5.

[0044] In some embodiments of the present invention, the photoinitiator is selected from at least one of TPO (diphenylphosphine oxide), Irgacure 819, and Darocur 1173.

[0045] In some embodiments of the present invention, the ratio of the adhesive to the fire extinguishing microcapsule is 80~120:30~50.

[0046] A fourth aspect of the present invention provides a method for preparing a fire extinguishing patch as described in the third aspect, comprising: mixing the raw materials for preparing the adhesive, then adding the fire extinguishing microcapsules, pouring the mixture into a patch mold, and curing the mixture to obtain the patch.

[0047] In some embodiments of the present invention, the curing temperature is 25~40°C. Preferably, it is 25~30°C.

[0048] A fifth aspect of the invention provides the use of fire extinguishing microcapsules as described in the first aspect or fire extinguishing patches as described in the third aspect in the preparation of fire extinguishing materials.

[0049] Other features and advantages of the present invention will be set forth in the following description. Detailed Implementation

[0050] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0051] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0052] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0053] In the description of this invention, the reference term "and / or" includes all and any combination of one or more of the associated listed items.

[0054] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0055] In an embodiment of the invention, the micronized silica gel was purchased from Guangzhou Xinxi Metallurgical Chemical Co., Ltd., and the particle size was 800 mesh (approximately 18.75 μm).

[0056] The CAS number of perfluoropropyl methyl ether is 375-03-1, the brand name is NOVEC 7000, and the boiling point is 34℃.

[0057] The CAS number of ethyl perfluoroisobutyl ether is 163702-06-5, the grade is NOVEC 7200, and the boiling point is 76℃.

[0058] The CAS number for the styrene-maleic anhydride copolymer is 9011-13-6.

[0059] The brand of polymeric MDI is Wanhua, and its brand name is PM200.

[0060] The CAS number for the isocyanate curing agent is 75-13-8.

[0061] The CAS number for the photoinitiator TPO is 75980-60-8.

[0062] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0063] Example 1 This embodiment provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0064] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0065] Example 2 This embodiment provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 51:5:65:1.

[0066] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0067] Example 3 This embodiment provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0068] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 14g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0069] Example 4 This embodiment provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0070] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 11g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0071] Example 5 This embodiment provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0072] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea, 7.5g melamine and 1g polyethylene glycol (PEG-400), adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0073] Comparative Example 1 This comparative example provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein the capsule wall is polyurea-formaldehyde resin and the core is perfluorohexanone.

[0074] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S2. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S3. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of perfluorohexanone, stir at 2000 rpm for 15 min, adjust the pH to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and cure for 4 h. After curing, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 680 ± 50 μm.

[0075] Comparative Example 2 This comparative example provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, micronized silica gel and β-cyclodextrin in a mass ratio of 56:65:1.

[0076] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, micronized silica gel and β-cyclodextrin are mixed according to the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0077] Comparative Example 3 This comparative example provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, ethyl perfluoroisobutyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0078] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, ethyl perfluoroisobutyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20 °C, add 80 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH value to 3.5 with hydrochloric acid, heat to 30 °C at a rate of 1 °C / min, and solidify for 4 h. After solidification, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 700 ± 50 μm.

[0079] Comparative Example 4 This comparative example provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0080] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20°C, add 55 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH to 3.5 with hydrochloric acid, heat to 30°C at a rate of 1°C / min, and cure for 4 h. After curing, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 690 ± 50 μm.

[0081] Comparative Example 5 This comparative example provides a fire extinguishing microcapsule and its preparation method. The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core, wherein: the capsule wall is polyurea-formaldehyde resin, and the core is prepared by mixing perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin in a mass ratio of 48:8:65:1.

[0082] The preparation method of the above-mentioned fire extinguishing microcapsules includes the following steps: S1. At 4°C, perfluorohexanone, perfluoropropyl methyl ether, micronized silica gel and β-cyclodextrin are mixed in the above mass ratio and stirred evenly to obtain a solid composite capsule core. S2. Mix 27.5g formaldehyde, 12g urea and 7.5g melamine, adjust the pH to 8.5 with triethanolamine, and react at 70℃ for 1h to carry out the prepolymerization reaction to obtain the prepolymer solution. S3. Weigh 100 mL of 2 wt% styrene-maleic anhydride copolymer aqueous solution, adjust the pH value to 10, and then keep it at 70℃ for 1 h to obtain a dispersion. S4. Mix the above prepolymer solution and dispersion with 100 mL of 0.8 wt% resorcinol solution, cool to 20°C, add 95 g of the above solid composite capsule core, stir at 2000 rpm for 15 min, adjust the pH to 3.5 with hydrochloric acid, heat to 30°C at a rate of 1°C / min, and cure for 4 h. After curing, filter, collect the solid phase, wash with water, and dry to obtain fire extinguishing microcapsules with an average particle size of 710 ± 50 μm.

[0083] Example of detection: This test example examines the encapsulation efficiency, storage stability, and thermal response temperature of the fire extinguishing microcapsules prepared in Examples 1-5 and Comparative Examples 1-5. The specific test methods are as follows.

[0084] (1) Embedding rate detection: Encapsulation efficiency refers to the ratio of the mass of the core inside the microcapsule shell to the total mass of the microcapsules. The higher the ratio, the higher the practical application value of the fire extinguishing microcapsule product. The calculation formula is as follows: Encapsulation efficiency = (core mass of microcapsule / total mass of microcapsule) × 100%.

[0085] (2) Storage stability test: The fire extinguishing microcapsule product was placed in a 40℃ constant temperature oven for accelerated aging for three months, and the storage stability of the microcapsules was characterized by the mass loss rate.

[0086] (3) Thermal response temperature: The fire extinguishing microcapsule product was placed in a constant temperature oven, and the temperature was increased at a rate of 1℃ / min to test the rupture temperature of the fire extinguishing microcapsules. Each group was repeated 5 times, and the average value was taken.

[0087] The test results are shown in Table 1.

[0088] Table 1

[0089] Based on the above test results, it can be seen that the fire extinguishing microcapsules produced using the formulation and process of this invention have excellent encapsulation efficiency (>85%) and good storage stability, indicating that the capsule wall has high density. Furthermore, the fire extinguishing microcapsules have a low response temperature (<80℃). During the low-temperature response fire extinguishing process, micro-powdered silica gel is added to the fire extinguishing microcapsules. At the moment the capsule wall ruptures, perfluoropropyl methyl ether (boiling point 34℃) and perfluorohexanone (boiling point 49℃) rapidly vaporize successively under continuously increasing temperature, providing a large internal pressure. This allows the microcapsules to rupture rapidly in the early stages of a fire, helping to form a comprehensive fire extinguishing aerosol, thereby achieving excellent early fire extinguishing effects.

[0090] Compared to Example 1, Comparative Example 1 only added perfluorohexanone to its core. The test results showed that its encapsulation efficiency (68.5%) was significantly lower than that of Example 1, and its core loss rate was higher. The thermal response temperature (87°C) was also significantly increased, indicating that micronized silica gel and β-cyclodextrin played a certain role in adsorption and stabilization, and the formation of a solid composite core helped improve encapsulation efficiency and stability. Furthermore, due to the lack of the synergistic effect of micronized silica gel and perfluoropropyl methyl ether in Comparative Example 1, the core vaporization pressure was insufficient in the initial stage of the thermal response, thus requiring a higher temperature to rupture.

[0091] Compared with Example 1, Comparative Example 2 did not add perfluoropropyl methyl ether, and Comparative Example 3 replaced perfluoropropyl methyl ether with ethyl perfluoroisobutyl ether. The results showed that the encapsulation rate was comparable to that of Example 1, but the thermal response temperature was significantly higher. This is because perfluoropropyl methyl ether has a low boiling point (about 34°C) and can vaporize rapidly when heated. It works synergistically with perfluorohexanone to generate internal pressure and reduce the rupture temperature. However, when this component is missing or replaced with ethyl perfluoroisobutyl ether (boiling point 76°C), which has a higher boiling point, its vaporization pressure is reduced after the thermal response, so a higher temperature is required to trigger rupture.

[0092] Compared to Example 1, the amount of solid composite core used in Comparative Example 4 was reduced, while the amount of solid composite core used in Comparative Example 5 was increased. The results showed that the encapsulation rate in Comparative Example 4 was significantly reduced, and the thermal response temperature was significantly increased, presumably due to the excessive thickness of the core wall. Although Comparative Example 5 showed a higher encapsulation rate and a lower response temperature, its storage stability was relatively poor, presumably because the core wall was too thin or incomplete, failing to effectively seal the core and causing a large amount of core volatilization or leakage during storage.

[0093] Application Example 1 Based on the fire extinguishing microcapsule of Example 1 above, this application example provides a method for preparing a fire extinguishing patch, specifically including the following steps: S1. By weight, 100 parts of polyurethane prepolymer, 15 parts of isocyanate curing agent and 3 parts of photoinitiator TPO are mixed evenly to obtain an adhesive solution; wherein the raw materials for preparing the polyurethane prepolymer include isophorone diisocyanate (IPDI), polytetrahydrofuran ether diol (PTMG-1000) and hydroxyethyl acrylate (HEA) in a molar ratio of 3:1:2.

[0094] S2. Take 40 portions of the fire extinguishing microcapsules from Example 1 above and add them to the adhesive solution in portions. Stir thoroughly after each addition to ensure that the fire extinguishing microcapsules are evenly distributed in the adhesive solution. S3. Drop the adhesive solution containing the fire extinguishing microcapsules into the patch mold, and place the patch mold on a low-frequency ultrasonic vibration table to vibrate, so as to remove air bubbles and make the fire extinguishing microcapsules evenly distributed in the mold. S4. After vibration, let the patch mold stand for 1 hour, and then cure it with ultraviolet light at 30°C. After curing, remove the patch from the patch mold to obtain the fire extinguishing patch.

[0095] The fire extinguishing patch prepared by the above method has excellent fire extinguishing performance. When the temperature reaches the thermal response temperature, it can achieve excellent fire extinguishing effect within two seconds. It also has good storage stability and has great application value.

[0096] In summary, this invention provides a fire extinguishing microcapsule, patch, its preparation method, and its application. The fire extinguishing microcapsule of this invention consists of a core and a capsule wall covering the surface of the core. The core uses a microcarrier (such as micro-powdered silica gel) as a solid dispersion component, combined with high-boiling-point perfluorohexanone (49°C) and low-boiling-point perfluoropropyl methyl ether (34°C). When heated, the solid microcarrier provides a large surface area and an efficient heat conduction pathway, which can assist the rapid vaporization of the liquid fire extinguishing components. The low-boiling-point perfluoropropyl methyl ether can first generate a high vapor pressure environment within the capsule wall, and the perfluorohexanone will then vaporize at a slightly higher temperature, generating greater volume expansion and forming a second wave of pressure peaks. Through continuous pressure accumulation, the response temperature can be significantly reduced, the response time shortened, and a more intense and dispersed release effect can be achieved. For the capsule wall, this invention uses polyurea-formaldehyde resin as the material. The cross-linked network structure of polyurea-formaldehyde resin is very dense, exhibiting high compactness and solvent resistance, which can prevent the volatilization and leakage of volatile components (such as perfluorohexanone and perfluoropropyl methyl ether) in the capsule core, thus contributing to improved storage stability. Furthermore, using polyurea-formaldehyde resin to coat the capsule core provides a good coating effect, with an encapsulation rate of >85%, which helps improve the fire extinguishing effect.

[0097] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A fire extinguishing microcapsule, characterized in that, The fire extinguishing microcapsule consists of a core and a capsule wall covering the surface of the core. The raw materials for preparing the core include, by mass parts: 40-60 parts of perfluorohexanone, 4-10 parts of perfluoropropyl methyl ether, 50-80 parts of microcarrier, and 0.5-2 parts of adhesive. The capsule wall is made of polyurea-formaldehyde resin.

2. The fire extinguishing microcapsule according to claim 1, characterized in that, The microcarrier is selected from at least one of micronized silica gel, diatomaceous earth, and nano-silica aerogel; And / or, the adhesive is selected from at least one of β-cyclodextrin, dextrin, α-cyclodextrin, and γ-cyclodextrin.

3. The fire extinguishing microcapsule according to claim 1, characterized in that, The raw materials for preparing the polyurea-formaldehyde resin include formaldehyde, urea, melamine, curing agent, and polymeric dispersant.

4. The fire extinguishing microcapsule according to claim 3, characterized in that, The curing agent is selected from at least one of resorcinol and ammonium chloride; And / or, the polymeric dispersant is selected from at least one of styrene-maleic anhydride copolymer, polyvinyl alcohol, and polyvinylpyrrolidone; And / or, the raw materials for preparing the polyurea-formaldehyde resin, by weight, include 25-30 parts formaldehyde, 10-15 parts urea, 7-8 parts melamine, 0.5-1.5 parts curing agent, and 1-3 parts polymeric dispersant.

5. The fire extinguishing microcapsule according to any one of claims 1 to 4, characterized in that, The encapsulation rate of the core is greater than 85%; And / or, the average particle size of the fire extinguishing microcapsules is 400~850μm.

6. A method for preparing fire extinguishing microcapsules as described in any one of claims 3 to 4, characterized in that, Includes the following steps: S1. Mix the raw materials for preparing the core to obtain a solid composite core; S2. Mix the formaldehyde, urea and melamine, adjust the pH value to 8-9, and react to obtain a prepolymer solution; S3. Mix the prepolymer solution, the dispersion containing the polymeric dispersant, and the curing agent, then add the solid composite core, adjust the pH value to 3-4, and after curing and washing, collect the solid phase and dry it to obtain the final product.

7. The preparation method according to claim 6, characterized in that, In step S3, the concentration of the polymeric dispersant in the dispersion is 0.5~1.5 wt%. And / or, the pH of the dispersion is 9 to 11; And / or, the curing temperature is below 30°C.

8. A fire extinguishing patch, characterized in that, The raw materials for preparation include the fire extinguishing microcapsules as described in any one of claims 1 to 5.

9. The fire extinguishing patch as described in claim 8, characterized in that, The raw materials for preparing the fire extinguishing patch also include adhesives.

10. The fire extinguishing patch as described in claim 9, characterized in that, The raw materials for preparing the adhesive include polyurethane prepolymer, isocyanate curing agent, and photoinitiator.

11. The method for preparing the fire extinguishing patch according to any one of claims 9 to 10, characterized in that, include: The raw materials for preparing the adhesive are mixed, then the fire extinguishing microcapsules are added, poured into a patch mold, and cured to obtain the final product.

12. The use of the fire extinguishing microcapsule as described in any one of claims 1 to 5 or the fire extinguishing patch as described in any one of claims 8 to 10 in the preparation of fire extinguishing materials.

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