Flame-retardant heat-insulating agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of flame-retardant materials, in particular to a flame-retardant heat-insulating agent as well as a preparation method and application thereof. The flame-retardant heat-insulating agent is prepared from the following components in parts by weight: 30 to 50 parts of polymer matrix resin, 20 to 40 parts of guanidine salt modified expandable graphite, 5 to 15 parts of graphene nanosheet hybrid flame retardant, 10 to 20 parts of inorganic synergistic flame retardant, 5 to 10 parts of phosphorus-nitrogen synergist and 1 to 5 parts of auxiliary agent. According to the flame-retardant and heat-insulating agent disclosed by the invention, through the synergistic effect of various components such as the composite guanidine salt modified expandable graphite, the graphene nanosheet hybrid flame retardant and the inorganic synergistic flame retardant, the comprehensive excellent properties of efficient flame retardance, heat insulation, mechanical enhancement and weather resistance improvement are realized, and the flame-retardant and heat-insulating agent is suitable for complex environments such as forest fire isolation belts; fire spreading can be effectively prevented, and the ecological system and human life and property safety are protected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant materials, in particular to a flame-retardant heat insulating agent, a preparation method and application thereof. BACKGROUND

[0002] Forest fire is a serious natural disaster, which poses a great threat to the ecological system, human life and property safety, and social economy. In order to effectively prevent the spread of forest fires, the construction of forest fire prevention isolation belt is crucial. The fire prevention isolation belt usually prevents the spread of fire through physical isolation, chemical flame retardant and other means, among which the use of flame retardant is one of the key measures. However, traditional forest fire prevention flame retardants have many problems in practical application, which limits their effectiveness and safety.

[0003] Traditional forest fire prevention flame retardants mostly use halogen-containing compounds (such as bromide, chloride) or metal hydroxides (such as aluminum hydroxide, magnesium hydroxide), which have problems such as environmental risk, insufficient efficiency and poor weather resistance. Halogen-containing flame retardants release toxic gases such as hydrobromic acid (HBr) and hydrochloric acid (HCl) during combustion, which not only cause serious environmental pollution, but also harm human health. In addition, the use of halogen-containing flame retardants may also cause soil acidification, water pollution and other problems, which have long-term impact on the ecological system. Inorganic hydroxides have certain flame-retardant effect, but a high addition amount (usually more than 50%) is needed to achieve ideal flame-retardant performance. However, high addition amount will significantly reduce the mechanical properties of the base material, such as the strength and toughness of the material. This makes it difficult to balance the flame-retardant performance and the mechanical properties of the material in practical application, limiting its use in forest fire prevention isolation belt and other scenarios. Traditional intumescent flame retardants have poor performance stability under extreme environmental conditions (such as high temperature, high humidity, low temperature, etc.). For example, traditional intumescent flame retardants are prone to moisture absorption, which reduces their performance in humid environments. In addition, under high temperature conditions, traditional flame retardants are prone to form fly ash, and the flame-retardant layer is easy to break, which cannot effectively isolate heat and oxygen, thereby reducing the flame-retardant effect. This poor weather resistance problem limits the service life and reliability of the flame retardant in complex environments such as forest fire prevention isolation belt. SUMMARY

[0004] The present application provides a flame-retardant heat insulating agent, a preparation method and application thereof, to solve the problems of high environmental toxicity, low flame-retardant efficiency, and loose and easy-to-fall carbon layer structure of traditional forest fire prevention flame retardants.

[0005] According to a first aspect of the present application, the present application provides a fire-retardant thermal insulation agent comprising, by weight parts, the following components: 30-50 parts of a polymer matrix resin, 20-40 parts of guanidine salt modified expandable graphite, 5-15 parts of graphene nanoplatelet hybrid flame retardant, 10-20 parts of inorganic synergistic flame retardant, 5-10 parts of phosphorus-nitrogen synergistic agent, and 1-5 parts of auxiliary agent.

[0006] The fire-retardant thermal insulation agent of the present application comprises a polymer matrix resin, guanidine salt modified expandable graphite, graphene nanoplatelet hybrid flame retardant, inorganic synergistic flame retardant, phosphorus-nitrogen synergistic agent, and auxiliary agent. The polymer matrix resin serves as a film-forming matrix, imparting good mechanical properties and film-forming properties to the material. The guanidine salt modified expandable graphite expands rapidly at high temperatures, forming a dense porous carbon layer that effectively insulates heat and oxygen. At the same time, the inert gases (such as NH3, H2O) released by the decomposition of guanidine salt dilute the concentration of combustible gases, playing a gas-phase flame-retardant role. By combining multiple flame-retardant components, the present application achieves comprehensive performance of efficient flame retardation, thermal insulation, and mechanical enhancement. The graphene nanoplatelet hybrid flame retardant enhances the continuity and stability of the carbon layer, while reducing local hotspot temperatures and extending the carbon layer's lifespan, through its high specific surface area (200-400 m 2 / g) and good thermal conductivity. The inorganic synergistic flame retardant (such as aluminum hydroxide, magnesium hydroxide) absorbs heat and decomposes, inhibiting the pyrolysis of the matrix and further improving flame retardation performance. The phosphorus-nitrogen synergistic agent (such as ammonium polyphosphate, pentaerythritol) promotes the dehydration and carbonization of the matrix through catalytic carbonization, forming a stable carbon layer. The rapid expansion of guanidine salt modified expandable graphite forms a physical barrier, while the graphene nanoplatelet hybrid flame retardant extends the carbon layer's lifespan through catalytic carbonization and thermal regulation. The two components form a dynamic synergy of "expansion-enhancement". The decomposition products of guanidine salt (such as NH3) combine with the PO· free radicals released by the phosphorus-nitrogen synergistic agent in the gas phase, quenching active free radicals (chemical flame retardation). The auxiliary agent (such as silane coupling agent, dispersant) improves the dispersibility and interfacial strength of the fillers, enhancing the overall performance of the material. By combining these components together and limiting the amount of each component within a reasonable range, the present application enables better synergy between components, resulting in efficient flame retardation, mechanical enhancement, environmental friendliness, and weather resistance.

[0007] Preferably, the fire-retardant thermal insulation agent comprises, by weight parts, the following components: 40-50 parts of a polymer matrix resin, 25-35 parts of guanidine salt modified expandable graphite, 8-12 parts of graphene nanoplatelet hybrid flame retardant, 12-18 parts of inorganic synergistic flame retardant, 6-10 parts of phosphorus-nitrogen synergistic agent, and 1.5-2 parts of auxiliary agent.

[0008] Further, the guanidine salt modified expandable graphite has an expansion volume ≥ 250 ml / g and a particle size range of 50-200 mesh. The expansion volume of the guanidine salt modified expandable graphite is significantly higher than that of traditional expandable graphite (usually 100-200 ml / g), which means that a thicker and denser carbon layer can be formed at high temperature, thereby providing stronger thermal insulation and flame retardation effects. Limiting the particle size range to a reasonable range value makes the modified expandable graphite more uniformly dispersed in the matrix, further improving the stability and consistency of the flame retardation performance.

[0009] Further, the graphene nanosheet hybrid flame retardant has a layer number ≤ 8 and a Raman spectrum I(D) / I(G) intensity ratio ≤ 0.15. Limiting the layer number of the graphene nanosheet hybrid flame retardant to ≤ 8 ensures that it has a higher specific surface area (200-400 m 2 / g), thereby more closely combining with the matrix and enhancing the continuity and stability of the carbon layer. Limiting the Raman spectrum I(D) / I(G) intensity ratio to ≤ 0.15 indicates that the graphene has a lower defect density and a complete structure, which can better play its role in heat conduction and mechanical reinforcement, while reducing the performance decay caused by structural defects.

[0010] Further, the high polymer matrix resin is one of water-based polyurethane, water-based epoxy resin or acrylate emulsion, and has a solid content ≥ 50% and a viscosity of 2000-5000 mPa·s at 25℃. The optimization of the type of high polymer matrix resin ensures that the material has good film-forming property, mechanical property and weather resistance, and the solid content ≥ 50% and the viscosity range of 2000-5000 mPa·s (25℃) make the material have good construction performance during coating.

[0011] Further, the inorganic synergistic flame retardant is one or both of aluminum hydroxide and magnesium hydroxide. By selecting the appropriate type of inorganic synergistic flame retardant, a better synergistic effect can be formed with other components, further enhancing the flame retardation performance and improving the heat resistance and weather resistance of the material.

[0012] Further, the phosphorus-nitrogen synergistic agent is one or both of ammonium polyphosphate and pentaerythritol. By selecting the appropriate type of phosphorus-nitrogen synergistic agent, a better synergistic effect can be formed with other components, and through catalytic carbon formation, the stability and flame retardation performance of the carbon layer are further improved.

[0013] Further, the adjuvant is one or both of silane coupling agent and dispersant. The use of adjuvants (silane coupling agent and dispersant) improves the dispersibility and interfacial strength of the filler and improves the overall performance of the material.

[0014] According to the second aspect of the present application, the present application also provides a preparation method of the above-mentioned flame retardant thermal insulation agent, comprising the following steps: The polymer matrix resin is premixed with additives, and then mixed with guanidinium modified expandable graphite, graphene nanosheet hybrid flame retardant, inorganic synergistic flame retardant and phosphorus-nitrogen synergistic agent.

[0015] The application provides a high-efficiency flame-retardant thermal insulation agent preparation method, which ensures uniform dispersion of components in a polymer matrix through premixing and mixing processes, thereby improving performance stability and consistency of the material.

[0016] Further, the rotation speed of the premixing is 1000-1500 rpm, and the time is 10-20 min; the mixing time is 1-2 h. The optimized rotation speed and time of the premixing and the mixing time ensure uniform dispersion of components in the polymer matrix, and meanwhile, avoid performance decline caused by excessive mixing.

[0017] The mixing is performed under vacuum conditions of -0.08 MPa to -0.1 MPa. The mixing process under vacuum conditions further improves the density and performance stability of the material.

[0018] Further, the preparation method of the guanidinium modified expandable graphite comprises the following steps: The flake graphite is reacted with a mixed acid solution and an oxidant at 20-50 DEG C for 0.5-2 h, washed with water until pH=5-6, to obtain primary expandable graphite; the primary expandable graphite is mixed with a guanidine phosphate solution at a mass ratio of 1:1.2-1:1.8, and intercalation reaction is performed at 50-80 DEG C for 1-3 h, and then dried to obtain guanidinium modified expandable graphite; The above scheme optimizes the preparation method of the guanidinium modified expandable graphite, and through specific mixed acid oxidation and specific guanidinium intercalation process, the expansion volume and carbon layer stability of the expandable graphite are significantly improved.

[0019] Preferably, in the mixed acid solution, the volume ratio of concentrated sulfuric acid to nitric acid is 3:1-5:1; the weight ratio of the flake graphite to the mixed acid solution is 1:(1-2); the oxidant is potassium dichromate or potassium permanganate, and the amount of the oxidant is 5-15% of the mass of the flake graphite; the volume ratio of concentrated sulfuric acid to nitric acid in the mixed acid solution and the amount of the oxidant are optimized, which ensures efficient generation of graphite intercalation compounds (GIC), thereby improving the interlayer bonding force of the graphite.

[0020] Preferably, the mass concentration of the guanidine phosphate solution is 10-20%. The mass concentration of the guanidine phosphate solution is combined with the optimization of the intercalation temperature, which avoids decomposition of the guanidinium at high temperature, and ensures efficient intercalation reaction.

[0021] Further, the preparation method of the graphene nanosheet hybrid flame retardant comprises the following steps: The expandable graphite is mixed with the ionic liquid at a mass ratio of 1:0.8-1:1.2, ball-milled to obtain a graphene nanosheet dispersion with a layer number of less than 8; The graphene nanosheet dispersion is mixed with a hybrid agent at a mass ratio of 1:4-1:10 at 100-140 DEG C for 2-4 h to form the graphene nanosheet hybrid flame retardant; the hybrid agent is selected from one of ammonium polyphosphate, pentaerythritol and melamine.

[0022] The above scheme optimizes the preparation method of the graphene nanosheet hybrid flame retardant, adopts a specific ionic liquid assisted ball-milling exfoliation process, reduces the van der Waals force between the graphite layers through the intercalation and shearing synergistic effect of the ionic liquid, realizes low-defect and high-efficiency exfoliation of the graphene, and the exfoliation efficiency is increased by 3-5 times compared with the traditional ball-milling. The specific thermal compounding process of the graphene nanosheet and the hybrid agent is beneficial to the formation of the "core-shell" structure, and further improves the thermal stability and flame retardant performance of the flame retardant.

[0023] Preferably, the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate or 1-ethyl-3-methylimidazolium tetrafluoroborate; the use of the specific type of ionic liquid reduces the van der Waals force between the graphite layers and improves the exfoliation efficiency.

[0024] Preferably, the ball-milling is carried out in a ball mill at a speed of 1800-2200 rpm for 36-60 h. The optimization of the ball-milling speed and time ensures that the number of layers of the graphene is less than 8, and the intensity ratio of Raman spectrum I(D) / I(G) is less than or equal to 0.15, thereby reducing the performance attenuation caused by structural defects.

[0025] According to a third aspect of the present application, the present application also provides the use of the above-mentioned flame-retardant thermal insulation agent in forest fire prevention materials.

[0026] The flame-retardant thermal insulation agent of the present application has the advantages of being halogen-free, environmentally friendly, excellent in mechanical properties and strong in weather resistance, and is suitable for complex environments such as forest fire prevention isolation belts, and can effectively prevent the spread of fire and protect the ecological system and the safety of human life and property.

[0027] According to a fourth aspect of the present application, the present application also provides a forest fire prevention isolation belt material prepared from the above-mentioned flame-retardant thermal insulation agent.

[0028] Preferably, the preparation method of the forest fire prevention isolation belt material comprises the following steps: coating the flame-retardant thermal insulation agent on the surface of a non-woven fabric or glass fiber substrate at a coating amount of 100-300 g / m 2 , and heat curing at 80-120 DEG C for 30-60 min. The optimization of the coating amount and curing conditions ensures the performance stability and consistency of the material.

[0029] The performance indicators of the traditional expanded graphite flame retardant are generally as follows: oxygen index is 25-29%, vertical burning level (UL-94) is V1-V2 level, thermal conductivity is 0.08-0.12 W / (m·K), carbon layer compressive strength is 0.5-1.0 MPa, water resistance (water absorption rate) is 10-15%, and environmental adaptability is generally-10℃-60℃ performance fluctuation >20%. Compared with the traditional expanded graphite flame retardant, the forest fire prevention isolation belt material has excellent oxygen index (≥32%), vertical burning level (UL-94 V0 level (1.6 mm thickness)), thermal conductivity (≤0.05 W / (m·K)), carbon layer compressive strength (≥2.0 MPa), water resistance (water absorption rate ≤5% after 7 days of immersion), and environmental adaptability (performance fluctuation <5% at-30℃-120℃), which can effectively prevent the spread of fire and is suitable for forest fire prevention isolation belt and other complex environments.

[0030] The beneficial effects of the present application are: The flame-retardant heat-insulating agent provided by the present application realizes the comprehensive excellent performance of efficient flame retardation, heat insulation, mechanical enhancement and weather resistance through the synergistic effect of various components such as guanidine salt modified expandable graphite, graphene nanosheet hybrid flame retardant and inorganic synergistic flame retardant. The oxygen index is ≥32%, the thermal conductivity is ≤0.05 W / (m·K), the vertical burning level reaches UL-94 V0 level, the carbon layer compressive strength is ≥2.0 MPa, the water resistance is excellent (water absorption rate ≤5%), and the performance fluctuation is less than 5% under extreme temperature and humidity conditions (-30℃ to 120℃). The flame-retardant heat-insulating agent is halogen-free and environmentally friendly, has excellent mechanical properties, is suitable for complex environments such as forest fire prevention isolation belt, can effectively prevent the spread of fire, and protects the ecological system and human life and property safety.

[0031] The preparation method of the flame-retardant heat-insulating agent realizes efficient and stable production effect through optimization of each key process step. First, expandable graphite is modified by guanidine phosphate intercalation, which significantly improves the expansion volume and carbon layer stability; second, few-layer graphene is efficiently prepared by using ionic liquid assisted ball milling exfoliation technology, the exfoliation efficiency is 3-5 times higher than that of traditional methods, and the ball milling parameters are strictly controlled to reduce the structural defects of graphene; in addition, a hybrid flame retardant with "core-shell" structure is formed by high-temperature compounding of ammonium polyphosphate and graphene, which further enhances the flame retardant performance. The whole preparation process is carried out in vacuum condition, which ensures the uniformity of mixing and the density of the material. Finally, the flame-retardant heat-insulating agent is coated on the surface of non-woven fabric or glass fiber substrate and heat cured, and the prepared forest fire prevention isolation belt material has excellent flame retardation, heat insulation, mechanics and weather resistance, and is suitable for forest fire prevention isolation belt in complex environment. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0033] Figure 1 The on-site experiment diagram of the fireproof isolation belt material of Example 1 of the present application and without coating the flame-retardant heat insulation agent. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the following will combine the drawings in the present application to clearly and completely describe the technical solutions in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application.

[0035] The raw materials used in the following examples and comparative examples are as follows: Water-based polyurethane: sourced from An Da Huatai, model 1707.

[0036] Water-based epoxy resin: sourced from Nantong Xingchen, model e51.

[0037] Acrylate emulsion: sourced from Guangdong Bangtai, model f3057.

[0038] Dispersant: sourced from Aladdin, model k88-96.

[0039] Example 1 (the matrix is water-based polyurethane) The present embodiment provides a flame-retardant heat insulation agent, which comprises the following raw materials in parts by weight: water-based polyurethane 40 parts, guanidine salt modified expandable graphite 35 parts, graphene nanosheet hybrid flame retardant 10 parts, aluminum hydroxide 15 parts, ammonium polyphosphate 8 parts, and KH-550 2 parts.

[0040] The present embodiment also provides a preparation method of the flame-retardant heat insulation agent, which comprises the following steps: 1. Preparation of modified expandable graphite: Take 10 kg of natural flake graphite (100 mesh) and 15 kg of mixed acid (H2SO4: HNO3 volume ratio = 3:1) and 1.2 kg of potassium dichromate, react at 40℃ for 1 hour, wash with water until pH = 5.5, and obtain primary expandable graphite.

[0041] The primary expandable graphite is immersed in a 15% guanidine phosphate solution (mass ratio 1:1.5) and reacted at 70°C for 2.5 hours. After drying, the expanded volume reaches 290 ml / g, and the number of layers of the graphene nanoplatelet hybrid flame retardant is ≤8, and the Raman spectrum ID / IG intensity ratio is ≤0.15.

[0042] 2. Preparation of the graphene nanoplatelet hybrid flame retardant: The expandable graphite is ball milled with 1-butyl-3-methylimidazolium hexafluorophosphate (mass ratio 1:1) for 48 hours (2000 rpm) to obtain a graphene nanoplatelet dispersion with a layer number ≤8. The graphene nanoplatelet dispersion is hot compounded with ammonium polyphosphate (mass ratio 1:8) at 130°C for 3 hours to obtain a graphene nanoplatelet hybrid flame retardant with a layer number ≤8, a Raman spectrum ID / IG intensity ratio ≤0.15, and a particle size range of 50-200 mesh.

[0043] 3. Preparation of the flame-retardant thermal insulation agent: The following raw materials are prepared: water-based polyurethane 40 parts, guanidine salt modified expandable graphite 35 parts, graphene nanoplatelet hybrid flame retardant 10 parts, aluminum hydroxide 15 parts, ammonium polyphosphate 8 parts, and KH-550 2 parts.

[0044] The water-based polyurethane and the silane coupling agent KH-550 are premixed in a high-speed disperser at a speed of 1500 rpm for 20 minutes. Then, the guanidine salt modified expandable graphite, the graphene nanoplatelet hybrid flame retardant, the aluminum hydroxide, and the ammonium polyphosphate are sequentially added, and the mixture is stirred and mixed under vacuum conditions (-0.1 MPa) for 2 hours to obtain a mixed slurry.

[0045] The example also provides a forest fire prevention isolation belt material, and the preparation method thereof is to coat the obtained mixed slurry on the surface of a glass fiber substrate at a coating amount of 200 g / m², and heat cure at 120°C for 40 minutes to form a fire prevention isolation belt material. Figure 1 The field experiment graph of the fire prevention isolation belt material of Example 1 and the fire prevention isolation belt material without the coating of the flame-retardant thermal insulation agent shows that the glass fiber without the coating of the flame-retardant thermal insulation agent is burned through in 10 seconds after being sprayed by a flame, while the fire prevention isolation belt material of the present application is burned through in 1 minute.

[0046] The forest fire prevention isolation belt material is subjected to performance testing, and the test results are as follows: oxygen index 36%, UL-94 V0, thermal conductivity coefficient 0.048 W / (m·K), and tensile strength 18 MPa.

[0047] Example 2 (matrix is water-based epoxy resin) The example provides a flame-retardant thermal insulation agent, which comprises the following raw materials in parts by weight: water-based epoxy resin 45 parts, modified expandable graphite 30 parts, graphene nanoplatelet hybrid flame retardant 8 parts, magnesium hydroxide 12 parts, pentaerythritol 6 parts, and KH-560 1.5 parts.

[0048] The embodiment also provides a preparation method of the flame-retardant thermal insulation agent, which is different from that of the embodiment 1 in that: 1. Preparation of modified expandable graphite: Potassium permanganate is used to replace potassium dichromate (8% in use), and the reaction temperature is 30°C, so that the modified expandable graphite with an expansion volume of 270 ml / g and a particle size range of 50-200 meshes is prepared.

[0049] 2. Preparation of graphene nanosheet hybrid flame retardant: 1-ethyl-3-methylimidazolium tetrafluoroborate is ball milled to obtain a graphene nanosheet dispersion liquid with a layer number of ≤8; The graphene nanosheet dispersion liquid is hot compounded with pentaerythritol (mass ratio 1:4) to obtain a graphene nanosheet hybrid flame retardant with a layer number of ≤8 and a Raman spectrum ID / IG intensity ratio of ≤0.15.

[0050] 3. Preparation of flame-retardant thermal insulation agent: 45 parts of water-based epoxy resin, 30 parts of modified expandable graphite, 8 parts of graphene nanosheet hybrid flame retardant, 12 parts of magnesium hydroxide, 6 parts of pentaerythritol, and 1.5 parts of KH-560.

[0051] The embodiment also provides a forest fire prevention isolation belt material, which is different from the embodiment 1 in that a glass fiber cloth (250 g / m²) is coated and cured at 100°C for 50 minutes.

[0052] The forest fire prevention isolation belt material is subjected to performance testing, and the test results are as follows: an oxygen index of 34%, UL-94 V1, a thermal conductivity of 0.052 W / (m·K), and water resistance (water absorption rate of 4.2% after immersion for 7 days).

[0053] Embodiment 3 (high-weather-resistant formula) The embodiment provides a flame-retardant thermal insulation agent, which comprises the following raw materials in parts by weight: 50 parts of acrylate emulsion, 25 parts of guanidine salt modified expandable graphite, 12 parts of graphene nanosheet hybrid flame retardant, 18 parts of aluminum hydroxide / magnesium hydroxide (1:1), 10 parts of ammonium polyphosphate, and 2 parts of dispersant (polyvinyl alcohol).

[0054] The embodiment also provides a preparation method of the flame-retardant thermal insulation agent, which is different from that of the embodiment 1 in that: 1. Preparation of modified expandable graphite: Guanidine carbonate solution (concentration 18%) is used for intercalation, so that the modified expandable graphite with an expansion volume of 260 ml / g and a particle size range of 50-200 meshes is prepared.

[0055] 2. Preparation of graphene nanosheet hybrid flame retardant: The ball milling time is shortened to 36 hours, and the number of layers of the graphene nanosheet dispersion liquid is less than or equal to 8; the graphene nanosheet dispersion liquid and ammonium polyphosphate / melamine (mass ratio 1:1) are hot compounded according to a mass ratio of 1:5. The number of layers of the obtained graphene nanosheet hybrid flame retardant is less than or equal to 8, and the Raman spectrum ID / IG intensity ratio is less than or equal to 0.15.

[0056] 3. Preparation of the flame-retardant heat insulator: 50 parts of an acrylate emulsion, 25 parts of guanidinium-modified expandable graphite, 12 parts of graphene nanosheet hybrid flame retardant, 18 parts of aluminum hydroxide / magnesium hydroxide (mass ratio 1:1), 10 parts of ammonium polyphosphate, and 2 parts of a dispersant (polyvinyl alcohol).

[0057] The example also provides a forest fire prevention isolation belt material, and a preparation method thereof is to spray the obtained mixed slurry on the surface of a rock wool board (300 g / m 2 ) and cure at 80°C for 60 minutes.

[0058] The forest fire prevention isolation belt material is subjected to performance testing, and the test results are as follows: oxygen index 33%, UL-94 V0, no cracking after being frozen at -30°C for 24 hours, and oxygen index retention rate > 95% after heat aging at 80°C for 72 hours.

[0059] Comparative Example 1 (without graphene nanosheet hybrid flame retardant) The comparative example provides a flame-retardant heat insulator, which is different from the example 1 in that the graphene nanosheet hybrid flame retardant is cancelled, and an equal amount of ammonium polyphosphate is increased to 18 parts.

[0060] The flame-retardant heat insulator is used to obtain a forest fire prevention isolation belt material by a preparation method similar to that of the example 1, and the forest fire prevention isolation belt material is subjected to performance testing, and the test results are as follows: oxygen index 29%, UL-94 V2, and carbon layer cracking rate > 50%, verifying the key role of graphene in the integrity of the carbon layer.

[0061] Comparative Example 2 (unmodified expandable graphite) The comparative example provides a flame-retardant heat insulator, which is different from the example 1 in that ordinary expandable graphite (expansion volume 180 ml / g) is used to replace the guanidinium-modified expandable graphite.

[0062] The flame-retardant heat insulator is used to obtain a forest fire prevention isolation belt material by a preparation method similar to that of the example 1, and the forest fire prevention isolation belt material is subjected to performance testing, and the test results are as follows: oxygen index 27%, and carbon layer shedding is serious during combustion, and the vertical combustion grade does not reach V level.

[0063] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A flame retardant heat insulating agent, characterized in that: The invention comprises the following components in parts by weight: 30-50 parts of polymer matrix resin, 20-40 parts of guanidine salt modified expandable graphite, 5-15 parts of graphene nanosheet hybrid flame retardant, 10-20 parts of inorganic synergistic flame retardant, 5-10 parts of phosphorus nitrogen synergist and 1-5 parts of auxiliary agent.

2. The flame retardant and heat insulating agent according to claim 1, characterized in that: The expansion volume of the guanidine salt modified expandable graphite is ≥250 ml / g, and the particle size range is 50-200 mesh.

3. The flame retardant and heat insulating agent according to claim 1 or 2, characterized in that: The number of layers of the graphene nanosheet hybrid flame retardant is ≤8, and the Raman spectrum ID / IG intensity ratio is ≤0.

15.

4. The flame retardant and heat insulating agent according to any one of claims 1 to 3, characterized in that: The polymer matrix resin is one of waterborne polyurethane, waterborne epoxy resin or acrylic emulsion, with a solid content of ≥50% and a viscosity of 2000-5000 mPa·s at 25°C; And / or, the inorganic synergistic flame retardant is selected from one or both of aluminum hydroxide and magnesium hydroxide; And / or, the phosphorus-nitrogen synergist is selected from one or both of ammonium polyphosphate and pentaerythritol; and / or, one or both of the auxiliary agents silane coupling agent and dispersant.

5. The method for preparing the flame retardant and heat insulating agent according to any one of claims 1 to 4, characterized in that: The steps include: The polymer matrix resin and the additive are premixed, and then the guanidine salt modified expandable graphite, the graphene nanosheet hybrid flame retardant, the inorganic synergistic flame retardant and the phosphorus nitrogen synergist are added and mixed.

6. The preparation method according to claim 5, characterized in that The premixing speed is 1000-1500 rpm, and the time is 10-20 min; the mixing time is 1-2 h; and the mixing is carried out under a vacuum condition of -0.08 MPa to -0.1 MPa.

7. The preparation method according to claim 5, characterized in that The preparation method of the guanidine salt modified expandable graphite comprises the following steps: The flake graphite is reacted with a mixed acid solution and an oxidant at 20-50° C. for 0.5-2 h, and washed with water until the pH is 5-6 to obtain primary expandable graphite; the primary expandable graphite is mixed with a guanidine phosphate solution at a mass ratio of 1:1.2-1:1.8, and intercalated at 50-80° C. for 1-3 h, and dried to obtain guanidine salt-modified expandable graphite; Preferably, in the mixed acid solution, the volume ratio of concentrated sulfuric acid to nitric acid is 3:1-5:1; the weight ratio of the flake graphite to the mixed acid solution is 1:(1-2); Preferably, the oxidant is potassium dichromate or potassium permanganate, and its amount is 5-15% of the mass of the flake graphite; Preferably, the mass concentration of the guanidine phosphate solution is 10-20%.

8. The preparation method according to claim 5, characterized in that The preparation method of the graphene nanosheet hybrid flame retardant comprises the following steps: The expandable graphite and the ionic liquid are mixed in a mass ratio of 1:0.8-1:1.2, and ball milled to obtain a dispersion of graphene nanosheets with a layer number of ≤8; Thermally compounding the graphene nanosheet dispersion and the hybridizing agent at a mass ratio of 1:4-1:10 at 100-140° C. for 2-4 hours to form the graphene nanosheet hybrid flame retardant; the hybridizing agent is selected from one of ammonium polyphosphate, pentaerythritol and melamine; Preferably, the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate or 1-ethyl-3-methylimidazolium tetrafluoroborate; Preferably, the ball milling is carried out in a ball mill at a rotation speed of 1800-2200 rpm for 36-60 h.

9. Use of the flame retardant and heat insulating agent according to any one of claims 1 to 4 in forest fire prevention materials.

10. A forest fire isolation belt material, characterized in that: It is prepared from the flame retardant and heat insulating agent according to any one of claims 1 to 4; Preferably, the method for preparing the forest fire isolation belt material comprises the following steps: applying a flame retardant and heat insulating agent to the surface of a non-woven fabric or a glass fiber substrate, with a coating amount of 100-300 g / m 2 , heat-cured at 80-120℃ for 30-60 min.

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