Triazine macromolecular flame-retardant curing agent, preparation method and application thereof

Abstract

The application discloses a triazine macromolecular flame-retardant curing agent and a preparation method and application thereof, and belongs to the technical field of composite materials. The triazine macromolecular flame-retardant curing agent with a polyamide structure is prepared by adopting 1,2,3,4-butane tetracarboxylic acid and melamine dehydration condensation with magnesium hydroxide as raw material, the polyamide structure unit can realize resin curing with an epoxy group, and the triazine structure can give the thermosetting resin a flame-retardant function; meanwhile, the composite synergistic effect of the triazine structure and the magnesium hydroxide is utilized to effectively improve the flame-retardant efficiency and reduce the actual adding amount of the flame retardant. When the flame-retardant curing agent is applied to a build-up film, good flame-retardant performance can be obtained, the thermal stability of the film is improved, and the thermal expansion phenomenon is reduced.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a triazine macromolecular flame retardant curing agent, its preparation method, and its application. Background Technology

[0002] The reinforcing film used for encapsulating substrates is mainly composed of polymeric resins and inorganic fillers, with epoxy resins being the primary polymeric resin system. Epoxy resin (EP) possesses high adhesive strength, good thermal stability, high mechanical strength, and good processability, and is widely used in coatings, adhesives, composite materials, and electrical equipment. However, due to the low limiting oxygen index of epoxy resin systems, they are flammable materials and release large amounts of dense smoke and toxic gases during combustion, limiting their further application. Adding flame retardants to improve the flame retardant properties of epoxy resin systems can broaden their application areas. Flame retardants are classified into additive (physical mixing) and reactive (chemical bonding) types. Furthermore, curing agents are an essential component of epoxy resin systems. The epoxy groups in epoxy resin react with curing agents such as phenols, thiols, and acid anhydrides to form a three-dimensional network cross-linked polymer structure.

[0003] The development of flame-retardant curing agents that combine flame retardancy and curing properties to impart flame retardancy to epoxy resin composite systems has become a research hotspot in flame-retardant epoxy resins. Flame-retardant curing agents possess excellent smoke suppression, reduce combustion, are low-cost, and environmentally friendly, thus attracting extensive research. The thermal decomposition products of functional groups in flame-retardant curing agents can catalyze the dehydration and carbonization reaction of oxygen-containing groups, forming a dense char layer on the resin surface. This layer acts as a physical barrier, preventing heat transfer and the release of flammable volatiles, and isolating external oxygen penetration, thereby achieving a flame-retardant effect.

[0004] Therefore, there is an urgent need for a flame-retardant curing agent that can improve flame retardancy by obtaining a triazine structure through component design, and at the same time introduce functional groups to achieve efficient curing of epoxy resin, so that it has good comprehensive performance when applied to laminated films. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a triazine macromolecular flame-retardant curing agent, its preparation method, and its application. The invention first uses magnesium hydroxide and a polycarboxylic acid (taking 1,2,3,4-butanetetracarboxylic acid as an example) as raw materials for reaction. Magnesium hydroxide, as an alkaline compound, can neutralize the carboxyl groups of 1,2,3,4-butanetetracarboxylic acid to generate an intermediate. Subsequently, the remaining carboxyl groups of 1,2,3,4-butanetetracarboxylic acid on the surface of the intermediate undergo dehydration condensation with the amino groups on a triazine derivative (taking melamine as an example) to obtain a hyperbranched triazine macromolecular flame-retardant curing agent with a polyamide structure. When the flame-retardant curing agent is applied to an adhesive film, it combines flame-retardant and curing effects, significantly improving the overall performance of the adhesive film while ensuring good flame retardancy.

[0006] To achieve this objective, the present invention adopts the following technical solution: The first aspect of this invention provides a method for preparing a triazine macromolecular flame retardant curing agent, comprising the following steps: Step S1: Using magnesium hydroxide and polycarboxylic acids as raw materials, an intermediate is prepared by stirring reaction; Step S2: After mixing the intermediate and the triazine derivative, dehydration condensation is performed to obtain a triazine macromolecular flame retardant curing agent.

[0007] As a preferred technical solution, the particle size D50 of magnesium hydroxide in step S1 is 1.0~2.0μm.

[0008] As a preferred technical solution, step S1 specifically involves: adding 10-20 parts by weight of polycarboxylic acid to 300-400 parts by weight of deionized water and stirring to dissolve, then adding 2-4 parts by weight of magnesium hydroxide, heating to 80-90°C and stirring for 6-8 hours, filtering after the reaction, washing the filter residue with deionized water, and vacuum drying to obtain the intermediate.

[0009] As a preferred technical solution, the polycarboxylic acid is selected from one of 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, and 1,2,3,4,5,6-cyclohexanehexacarboxylic acid.

[0010] As a more preferred technical solution, the polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid.

[0011] As a preferred technical solution, the dehydration condensation step in step S2 is as follows: by weight, 300-400 parts of deionized water are heated to 90-95°C, then 4-8 parts of triazine derivative are added and stirred for 20-30 minutes. The pH is adjusted to 5-6 with hydrochloric acid solution, then 2-4 parts of the intermediate are added. The mixture is dehydrated and condensed at 90-95°C for 6-8 hours, filtered, washed with hot deionized water, and vacuum dried to obtain the triazine macromolecular flame retardant curing agent.

[0012] As a preferred technical solution, the triazine derivative is selected from melamine, cyclopropionate, 2,4-diamino-1,3,5-triazine and 2-chloro-4,6-diamino-1,3,5-triazine.

[0013] As a more preferred technical solution, the triazine derivative is melamine.

[0014] The second aspect of the present invention provides a triazine macromolecular flame retardant curing agent prepared by the preparation method described in the first aspect.

[0015] The third aspect of this invention provides the application of a triazine macromolecular flame retardant curing agent prepared by the preparation method described in the first aspect in an adhesive film.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, magnesium hydroxide and polycarboxylic acid (taking 1,2,3,4-butanetetracarboxylic acid as an example) are first reacted. Magnesium hydroxide, as an alkaline compound, can neutralize the carboxyl groups of 1,2,3,4-butanetetracarboxylic acid to generate an intermediate. Subsequently, the remaining carboxyl groups of 1,2,3,4-butanetetracarboxylic acid on the surface of the intermediate undergo dehydration condensation with the amino groups on the triazine derivative (taking melamine as an example) to obtain a hyperbranched triazine macromolecular flame retardant curing agent with a polyamide structure. The 1,2,3,4-butanetetracarboxylic acid of this invention contains four carboxyl groups, and melamine contains multiple amino groups. The multifunctional properties of both can form a hyperbranched polyamide structure during the dehydration condensation process.

[0017] (2) The flame retardant curing agent of the present invention contains a triazine structure and magnesium hydroxide, wherein the triazine structure promotes char formation and improves the density of the char layer, and magnesium hydroxide improves the thermal stability of the char layer, forming a char-magnesium composite barrier layer; at the same time, the triazine ring decomposes to release non-combustible gas to dilute the oxygen and combustible gas concentration in the combustion zone to achieve gas phase flame retardancy, and the decomposition reaction of magnesium hydroxide absorbs a large amount of heat to reduce the temperature of the substrate to achieve condensed phase flame retardancy, thereby synergistically improving the flame retardancy efficiency of the material.

[0018] (3) In the flame retardant curing agent of the present invention, the amide group can form dense hydrogen bonds with the epoxy resin to inhibit chain segment movement. The dense network structure makes the material more rigid and heat resistant. Micron-sized magnesium hydroxide (1.0~2.0μm) is uniformly dispersed to form a supporting skeleton. By anchoring the polymer molecular chain, it restricts the movement and rotation of the resin chain segment and suppresses the volume expansion caused by thermal vibration and chain segment extension. Through the action of different functional groups of the flame retardant curing agent, the glass transition temperature of the coated film is significantly increased and the coefficient of thermal expansion is reduced. Detailed Implementation

[0019] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0020] This invention provides a method for preparing a triazine macromolecular flame retardant curing agent, comprising the following steps: Step S1: Using magnesium hydroxide and polycarboxylic acids as raw materials, an intermediate is prepared by stirring reaction; Step S2: After mixing the intermediate and the triazine derivative, dehydration condensation is performed to obtain a triazine macromolecular flame retardant curing agent.

[0021] As a preferred technical solution, the particle size D50 of magnesium hydroxide in step S1 is 1.0~2.0μm, such as 1.5μm.

[0022] This embodiment controls the particle size of magnesium hydroxide to avoid structural defects caused by excessively large magnesium hydroxide particles. Uniformly dispersed and small-sized magnesium hydroxide is conducive to the formation of a dense and stable three-dimensional network structure, thereby ensuring that the material can be uniformly catalyzed into char during combustion, forming a complete protective char layer and improving the flame retardant performance of the material. At the same time, small-sized magnesium hydroxide can be better distributed in the material's functional groups, restricting molecular chain movement, increasing the glass transition temperature, and reducing the coefficient of thermal expansion.

[0023] As a preferred technical solution, step S1 specifically involves: adding 10-20 parts (e.g., 10, 15, 20, etc.) of polycarboxylic acid to 300-400 parts (e.g., 300, 350, 400, etc.) of deionized water and stirring to dissolve it, then adding 2-4 parts (e.g., 2, 3, 4, etc.) of magnesium hydroxide, heating to 80-90℃ (e.g., 80℃, 85℃, 90℃, etc.) and stirring to react for 6-8 hours (e.g., 6 hours, 7 hours, 8 hours, etc.), filtering after the reaction is completed, washing the filter residue with deionized water, and vacuum drying to obtain the intermediate.

[0024] On the one hand, the polycarboxylic acid of the present invention undergoes an acid-base neutralization reaction with magnesium hydroxide, and magnesium ions combine with polycarboxylic acid ions in the solution to form organic magnesium salts; on the other hand, magnesium ions have a small ionic radius and a high charge density, and their good coordination ability allows them to exist in a coordinated combination with polycarboxylic acids, thereby preparing an intermediate.

[0025] As a preferred technical solution, the polycarboxylic acid is selected from one of 1,2,3,4-butanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, and 1,2,3,4,5,6-cyclohexanehexacarboxylic acid.

[0026] As a more preferred technical solution, the polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid.

[0027] 1,2,3,4-Butanetetracarboxylic acid has a high coordination density, with each molecule possessing four carboxyl groups. During the preparation of intermediates, some carboxyl groups can combine with magnesium hydroxide, while the remaining carboxyl groups can react with triazine derivatives. At the same time, compared with aromatic polycarboxylic acids, 1,2,3,4-Butanetetracarboxylic acid has less steric hindrance in its aliphatic chain structure, which is conducive to the reaction of carboxyl groups.

[0028] As a preferred technical solution, the dehydration condensation step in step S2 is as follows: 300-400 parts (e.g., 300 parts, 350 parts, 400 parts, etc.) of deionized water are heated to 90-95℃ (e.g., 90℃, 92℃, 95℃, etc.) by weight, and then 4-8 parts (e.g., 4 parts, 6 parts, 8 parts, etc.) of triazine derivative are added and stirred for 20-30 minutes (e.g., 20 minutes, 25 minutes, 30 minutes, etc.). The pH is adjusted to 5-6 (e.g., 5, 6, etc.) with hydrochloric acid solution, and then 2-4 parts (e.g., 2 parts, 3 parts, 4 parts, etc.) of the intermediate are added. The mixture is dehydrated and condensed at 90-95℃ (e.g., 90℃, 92℃, 95℃, etc.) for 6-8 hours (e.g., 6 hours, 7 hours, 8 hours, etc.). The mixture is then filtered, washed with hot deionized water, and vacuum dried to obtain the triazine macromolecular flame retardant curing agent.

[0029] Triazine derivatives, acting as a multifunctional core, undergo amidation and dehydration condensation reactions with carboxyl-containing intermediates to form stable amide bonds. Simultaneously, triazine derivatives contain multiple amine groups, enabling them to undergo multifunctional cross-linking with intermediates, forming complex three-dimensional macromolecular networks. As a preferred technical solution, the triazine derivative is selected from melamine, cyclopropionate, 2,4-diamino-1,3,5-triazine and 2-chloro-4,6-diamino-1,3,5-triazine.

[0030] As a more preferred technical solution, the triazine derivative is melamine.

[0031] Melamine's molecular structure consists of three amine groups symmetrically linked to a triazine ring, forming a three-armed star-shaped rigid planar molecule. At the same time, the three primary amine groups have moderate reactivity and can be used to construct a stable macromolecular network, which is beneficial for forming triazine macromolecular flame retardant curing agents and improving overall performance.

[0032] This invention provides a triazine macromolecular flame retardant curing agent prepared by the preparation method described in this invention.

[0033] This invention provides an application of a triazine macromolecular flame retardant curing agent prepared by the preparation method described in this invention in an adhesive film.

[0034] The present invention will be further described in detail below through specific embodiments.

[0035] The sources of some components in the following examples and comparative examples are as follows: Magnesium hydroxide I, model MX-1, with a particle size D50 of 1.5μm, was purchased from Weifang Wanfeng New Material Technology Co., Ltd. Magnesium hydroxide II, model MX-180, with a particle size D50 of 5.0μm, was purchased from Weifang Wanfeng New Material Technology Co., Ltd. 1,2,3,4-Butanetetracarboxylic acid, CAS No. 1703-58-8, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Cyclobutane carboxylic acid, CAS No. 3721-95-7, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Melamine, CAS No. 108-78-1, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. 2-Amino-1,3,5-triazine, CAS No. 4122-04-7, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Bisphenol A type epoxy resin, model 828EL, purchased from Mitsubishi Chemical Company; Naphthalene-type epoxy resin, model HP-6000, purchased from DIC Company; Silica, model SO-C2, purchased from Yaduma Company; Phenoxy resin, model YX7553BH30, was purchased from Mitsubishi Chemical Company. 4-Dimethylaminopyridine (DMAP), CAS No. 1122-58-3, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0036] Example 1 This embodiment provides a method for preparing a triazine macromolecular flame retardant curing agent, including the following steps: Step S1: By weight, 20 parts of 1,2,3,4-butanetetracarboxylic acid were added to 400 parts of deionized water and stirred to dissolve. Then, 4 parts of magnesium hydroxide I were added, and the mixture was heated to 90°C and stirred for 6 hours. After the reaction was completed, the mixture was filtered, the filter residue was washed with deionized water, and the mixture was dried under vacuum to obtain the intermediate. Step S2: Heat 400 parts of deionized water to 95°C, then add 8 parts of melamine and stir for 30 minutes. Adjust the pH to 6 with hydrochloric acid solution, then add 4 parts of the intermediate. Dehydrate and condense at 95°C for 6 hours, filter, wash with hot deionized water, and vacuum dry to obtain triazine macromolecular flame retardant curing agent.

[0037] Example 2 This embodiment provides a method for preparing a triazine macromolecular flame retardant curing agent, including the following steps: Step S1: By weight, 10 parts of 1,2,3,4-butanetetracarboxylic acid were added to 300 parts of deionized water and stirred to dissolve. Then, 2 parts of magnesium hydroxide I were added, and the mixture was heated to 80°C and stirred for 8 hours. After the reaction was completed, the mixture was filtered, the filter residue was washed with deionized water, and then dried under vacuum to obtain the intermediate. Step S2: Heat 300 parts of deionized water to 90°C, then add 4 parts of melamine and stir for 20 minutes. Adjust the pH to 5 with hydrochloric acid solution, then add 2 parts of the intermediate. Dehydrate and condense at 90°C for 8 hours, filter, wash with hot deionized water, and vacuum dry to obtain triazine macromolecular flame retardant curing agent.

[0038] Example 3 This embodiment provides a method for preparing a triazine macromolecular flame retardant curing agent, including the following steps: Step S1: By weight, 15 parts of 1,2,3,4-butanetetracarboxylic acid were added to 350 parts of deionized water and stirred to dissolve. Then, 3 parts of magnesium hydroxide I were added, and the mixture was heated to 85°C and stirred for 7 hours. After the reaction was completed, the mixture was filtered, the filter residue was washed with deionized water, and then dried under vacuum to obtain the intermediate. Step S2: Heat 350 parts of deionized water to 92°C, then add 6 parts of melamine and stir for 25 minutes. Adjust the pH to 5.5 with hydrochloric acid solution, then add 3 parts of the intermediate. Dehydrate and condense at 92°C for 7 hours, filter, wash with hot deionized water, and vacuum dry to obtain triazine macromolecular flame retardant curing agent.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that magnesium hydroxide II (model MX-180) was used instead of magnesium hydroxide I (model MX-1) in the preparation of the flame retardant curing agent.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that cyclobutanecarboxylic acid was used instead of 1,2,3,4-butanetetracarboxylic acid in the preparation of the flame retardant curing agent.

[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that 2-amino-1,3,5-triazine was used instead of melamine in the preparation of the flame retardant curing agent.

[0042] Application Example 1 This application embodiment provides a method for preparing an extended adhesive film, comprising the following steps: by weight, 20 parts of bisphenol A type epoxy resin (828EL), 20 parts of naphthalene type epoxy resin (HP-6000), 60 parts of silica (SO-C2), 20 parts of the flame retardant curing agent described in Example 1, 3 parts of phenoxy resin (YX7553BH30), 0.2 parts of 4-dimethylaminopyridine (DMAP), and 300 parts of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0043] Application Example 2 This application embodiment provides a method for preparing an extended adhesive film, comprising the following steps: by weight, 20 parts of bisphenol A type epoxy resin (828EL), 20 parts of naphthalene type epoxy resin (HP-6000), 60 parts of silica (SO-C2), 20 parts of the flame retardant curing agent described in Example 2, 3 parts of phenoxy resin (YX7553BH30), 0.2 parts of 4-dimethylaminopyridine (DMAP), and 300 parts of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0044] Application Example 3 This application embodiment provides a method for preparing an extended adhesive film, comprising the following steps: by weight, 20 parts of bisphenol A type epoxy resin (828EL), 20 parts of naphthalene type epoxy resin (HP-6000), 60 parts of silica (SO-C2), 20 parts of the flame retardant curing agent described in Example 3, 3 parts of phenoxy resin (YX7553BH30), 0.2 parts of 4-dimethylaminopyridine (DMAP), and 300 parts of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0045] Application Comparison Example 1 This comparative example provides a method for preparing an extended adhesive film, comprising the following steps: by weight, 20 parts of bisphenol A type epoxy resin (828EL), 20 parts of naphthalene type epoxy resin (HP-6000), 60 parts of silica (SO-C2), 20 parts of the flame retardant curing agent described in Comparative Example 1, 3 parts of phenoxy resin (YX7553BH30), 0.2 parts of 4-dimethylaminopyridine (DMAP), and 300 parts of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0046] Application Comparison Example 2 This comparative example provides a method for preparing an extended adhesive film, comprising the following steps: by weight, 20 parts of bisphenol A type epoxy resin (828EL), 20 parts of naphthalene type epoxy resin (HP-6000), 60 parts of silica (SO-C2), 20 parts of the flame retardant curing agent described in Comparative Example 2, 3 parts of phenoxy resin (YX7553BH30), 0.2 parts of 4-dimethylaminopyridine (DMAP), and 300 parts of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0047] Application Comparison Example 3 This comparative example provides a method for preparing an extended adhesive film, comprising the following steps: 20 parts by weight of bisphenol A type epoxy resin (828EL), 20 parts by weight of naphthalene type epoxy resin (HP-6000), 60 parts by weight of silica (SO-C2), 20 parts by weight of the flame retardant curing agent described in Comparative Example 3, 3 parts by weight of phenoxy resin (YX7553BH30), 0.2 parts by weight of 4-dimethylaminopyridine (DMAP), and 300 parts by weight of cyclohexanone are coated onto a substrate to obtain an adhesive film layer, dried, and covered with a protective film to obtain an extended adhesive film.

[0048] The performance of the laminated films provided in the above application examples and comparative examples was tested using the following methods: Flame retardancy: After removing the protective film, the extension film with release liner is laminated to the substrate using a laminating machine. The extension film (without release liner) is laminated to both sides of the substrate to obtain a laminate. After lamination, the release liner on the laminate is removed, and heat curing (heat curing at 190°C for 90 minutes) is performed to form a cured product on both sides of the substrate, thus obtaining the test sample. The test sample (approximately 380 μm thick) is cut into test pieces of 12.7 mm × 127 mm with an edge of 1.27 mm, and tested according to the UL-94V standard. The test results are recorded.

[0049] Coefficient of thermal expansion: After removing the protective film, the extension film with the release film was cured at 100℃ for 30 min and at 190℃ for 90 min. Then the release film was peeled off to obtain the test sample. The test sample was cut into test pieces with a width of about 3 mm and a length of about 20 mm. Thermomechanical analysis was performed using a thermomechanical analysis device (TA Instruments' "TMA450") under the conditions of a preload force of 0.02 N, a heating range of 25℃-260℃, and a heating rate of 10℃ / min to obtain the coefficient of thermal expansion in the range of 25℃ to 150℃.

[0050] Glass transition temperature: After removing the protective film, the extension film with the release film was cured at 100℃ for 30 min and then at 190℃ for 90 min. The release film was then peeled off to obtain the test sample. The test sample was cut into test pieces with a width of about 3 mm and a length of about 20 mm. The test was performed using a dynamic thermomechanical analysis device (TA Instruments' "DMA850") in tensile mode. The test conditions were set as follows: vibration frequency 1 Hz, amplitude 15 μm, heating rate 5℃ / min, and heating range 25℃-260℃. The glass transition temperature Tg was obtained.

[0051] The performance test data above are shown in Table 1.

[0052] Table 1 Performance Test Results

[0053] As can be seen from Table 1: 1. Flame retardancy The flame retardant ratings of the laminated films in Application Examples 1-3 all reached UL-94 V-0, while those in Comparative Examples 1-3 were only V-1. The difference stems from the selection of raw materials and structural design of the flame retardant curing agent. Comparative Application Example 1: Using large-particle magnesium hydroxide (D50=5.0μm) instead of small-particle magnesium hydroxide (D50=1.5μm) in Example 1. Large particles are prone to forming structural defects, making it impossible to catalyze into carbon uniformly, and reducing the integrity of the carbon layer. Comparative Application Example 2: Cyclobutane carboxylic acid (monocarboxylic acid) was used instead of 1,2,3,4-butanetetracarboxylic acid (tetracarboxylic acid) in Example 1. The monofunctional group could not form a hyperbranched polyamide structure, and the synergistic flame retardant effect of triazine and magnesium hydroxide was weakened. Comparative Application Example 3: 2-amino-1,3,5-triazine was used instead of melamine in Example 1. The former has fewer amino groups, making it difficult to form a dense hyperbranched structure, and the synergistic effect of the gas-phase flame retardancy of the triazine ring and the condensed-phase flame retardancy of magnesium hydroxide is reduced.

[0054] 2. Coefficient of thermal expansion The coefficients of thermal expansion of Application Examples 1-3 (21-24 μm / m·℃) were significantly lower than those of Comparative Examples 1-3 (35-54 μm / m·℃). The core reason for this is the difference in the ability of the flame retardant curing agent to restrict the movement of resin chains. The flame retardant curing agents in Examples 1-3 contain hyperbranched polyamide structures, where amide groups form dense hydrogen bonds with epoxy resin, and small-particle magnesium hydroxide is uniformly dispersed to form a supporting skeleton, anchoring the molecular chains and inhibiting thermal expansion. Comparative Example 1's large-particle magnesium hydroxide has poor dispersibility and cannot effectively form a supporting framework; Comparative Example 2's monocarboxylic acid structure is difficult to construct a dense network; Comparative Example 3's triazine derivative has insufficient amino groups and low structural branching, all of which lead to weakened restriction of chain segment movement and increased coefficient of thermal expansion.

[0055] 3. Glass transition temperature (Tg) The Tg (180-183℃) of Application Examples 1-3 is higher than that of Application Comparative Examples 1-3 (162-175℃), demonstrating the effect of flame retardant curing agent on improving the heat resistance of materials. The hyperbranched polyamide structure in Examples 1-3, combined with the rigid network formed by small-particle magnesium hydroxide, improves the heat resistance of the material. The substitution of raw materials in Comparative Examples 1-3 disrupted the rigid network structure (such as large-particle magnesium hydroxide, monocarboxylic acid, and few aminotriazine derivatives), making chain segment movement easier and reducing Tg.

[0056] In summary, this invention provides a triazine macromolecular flame-retardant curing agent, its preparation method, and its application. The invention first uses magnesium hydroxide and 1,2,3,4-butanetetracarboxylic acid as raw materials for a reaction. Magnesium hydroxide, as an alkaline compound, can neutralize the carboxyl groups of 1,2,3,4-butanetetracarboxylic acid to generate an intermediate. Subsequently, the remaining carboxyl groups of 1,2,3,4-butanetetracarboxylic acid on the surface of the intermediate undergo dehydration condensation with the amino groups on melamine to obtain a hyperbranched triazine macromolecular flame-retardant curing agent with a polyamide structure. The hyperbranched triazine macromolecular flame-retardant curing agent with a polyamide structure prepared by this invention allows the polyamide structural units to achieve resin curing with epoxy groups, while the triazine structure imparts flame-retardant functionality to the thermosetting resin. Simultaneously, the synergistic effect of the triazine structure and magnesium hydroxide effectively improves flame-retardant efficiency and reduces the actual amount of flame retardant added. When the flame-retardant curing agent is applied to an adhesive film, it achieves good flame-retardant performance, improves the thermal stability of the adhesive film, and reduces thermal expansion.

Claims

1. A method for preparing a triazine macromolecular flame retardant curing agent, characterized in that, Includes the following steps: Step S1: Using magnesium hydroxide and polycarboxylic acids as raw materials, an intermediate is prepared by stirring reaction; In step S1, the magnesium hydroxide is 2-4 parts by weight and the polycarboxylic acid is 10-20 parts by weight. Step S2: After mixing the intermediate and the triazine derivative, dehydration condensation is performed to obtain a triazine macromolecular flame retardant curing agent; In step S2, the intermediate is 2 to 4 parts by weight, and the triazine derivative is 4 to 8 parts by weight. In step S1, the particle size D50 of magnesium hydroxide is 1.0~2.0 μm; The polycarboxylic acid is 1,2,3,4-butanetetracarboxylic acid; The triazine derivative is melamine.

2. The preparation method of the triazine macromolecular flame retardant curing agent according to claim 1, characterized in that, Step S1 specifically involves: adding 10-20 parts by weight of polycarboxylic acid to 300-400 parts by weight of deionized water and stirring to dissolve, then adding 2-4 parts by weight of magnesium hydroxide, heating to 80-90°C and stirring for 6-8 hours, filtering after the reaction, washing the filter residue with deionized water, and vacuum drying to obtain the intermediate.

3. The preparation method of a triazine macromolecular flame retardant curing agent according to claim 1, characterized in that, The dehydration condensation step in step S2 is as follows: by weight, 300-400 parts of deionized water are heated to 90-95°C, then 4-8 parts of triazine derivative are added and stirred for 20-30 minutes. The pH is adjusted to 5-6 with hydrochloric acid solution, then 2-4 parts of the intermediate are added. The mixture is dehydrated and condensed at 90-95°C for 6-8 hours, filtered, washed with hot deionized water, and vacuum dried to obtain the triazine macromolecular flame retardant curing agent.

4. A triazine macromolecular flame retardant curing agent, characterized in that, It is prepared by the preparation method according to any one of claims 1-3.

5. The application of a triazine macromolecular flame retardant curing agent prepared by any one of claims 1-3 in an adhesive film.

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