Pre-compounded aerogel modified polyurethane foaming insulation board and preparation method thereof

Abstract

The invention discloses a pre-compounded aerogel modified polyurethane foaming insulation board and a preparation method thereof, and belongs to the technical field of polyurethane insulation materials. The pre-compounded aerogel modified polyurethane foaming insulation board is prepared from a component A and a component B through high-pressure foaming and in-mold curing molding, the component A is prepared from the following raw material components in parts by weight: 100 parts of polyol, 8 to 12 parts of modified silicon dioxide aerogel powder, 10 to 15 parts of modified glass fibers, 31 to 37 parts of a composite flame retardant, 4 to 6 parts of an environment-friendly foaming agent, 0.8 to 1.2 parts of deionized water, 1.2 to 1.8 parts of a composite silicone oil stabilizer and 0.48 to 0.95 part of a composite catalyst; the component B is prepared from 130 to 150 parts of polymerized MDI (Diphenyl Diisocyanate). Through cooperation of the modified silicon dioxide aerogel powder and the modified glass fibers, a three-dimensional interpenetrating inorganic framework is formed through pre-compounding and cooperates with a polyol system and polymerized MDI, and through high-pressure foaming and in-mold curing forming, the comprehensive performance of the heat insulation board is remarkably improved, and synergistic balance of heat insulation performance, flame retardant performance and mechanical performance is achieved.

Description

Technical Field

[0001] This application relates to a pre-composite aerogel modified polyurethane foam insulation board and its preparation method, belonging to the technical field of polyurethane insulation materials. Background Technology

[0002] Rigid polyurethane foam is widely used in building exterior wall insulation, cold chain logistics, and industrial pipelines due to its excellent closed-cell structure and extremely low thermal conductivity. However, polyurethane materials are inherently flammable, releasing large amounts of heat and toxic fumes when burning. With increasingly stringent national requirements for building fire safety, traditional B1 or B2 grade polyurethane insulation materials are no longer sufficient to meet the demands of high-end buildings and specialized industrial sectors for Class A non-combustible materials.

[0003] Currently, the conventional methods to improve the flame retardant properties of polyurethane are to add large amounts of inorganic flame retardants (such as aluminum hydroxide and ammonium polyphosphate) or to use halogen-containing flame retardants. However, excessive addition of inorganic flame retardants can severely damage the cell structure of polyurethane, leading to a decrease in closed-cell rate, which in turn causes a sharp increase in thermal conductivity, a significant decrease in compressive strength, and an increase in water absorption. Halogen-containing flame retardants, on the other hand, produce highly toxic and corrosive gases when burned, which does not meet environmental protection requirements. In addition, in order to reduce thermal conductivity, the industry has begun to try to introduce silica aerogel, but aerogel is extremely prone to agglomeration and is difficult to disperse uniformly in polyurethane resin. Moreover, its nanoporous structure easily absorbs oil and water, leading to a surge in the viscosity of the foaming system and loss of control in the foaming process.

[0004] Chinese patent CN 121594245 A discloses a nano-aerogel-modified polyurethane insulation pipe and its preparation method. Specifically, the insulation pipe includes a working pipe, a modified polyurethane insulation layer, and an outer protective pipe from the inside out. The modified polyurethane insulation layer is foamed from a polyol composite material, isocyanate, and nano-aerogel. This patent introduces nano-aerogel, which reduces the thermal conductivity to a certain extent. However, its flame retardant system is conventional and cannot simultaneously achieve flame retardant performance, insulation performance, and mechanical properties. Chinese patent CN 121375267 A discloses a polyurethane composite insulation board with good flame retardant effect. Specifically, it discloses a process including fireproof surface layer pretreatment, flame retardant core layer preparation, reinforced base layer treatment, lamination molding, and post-treatment. By designing a unique three-layer composite structure and adopting a multi-component synergistic flame retardant system, the insulation board can form a multi-level flame retardant barrier when exposed to high temperature and open flame, slowing down the flame spread rate and improving the overall fire safety of the material. The synergistic effect between the functional layers enhances the durability and stability of the flame retardant effect. However, it uses a lamination composite process, which has the disadvantages of easy delamination at the interlayer interface and poor long-term weather resistance. In addition, the flame retardant system of the core layer is still a conventional phosphorus-nitrogen system, which has insufficient flame retardant durability.

[0005] Therefore, how to stably improve the flame retardant performance of polyurethane to A2 level without sacrificing its excellent thermal insulation performance and mechanical strength, while solving the compatibility problems of aerogel dispersion, fiber reinforcement and foaming system, and achieving a synergistic balance of multiple properties such as "low thermal conductivity, high flame retardancy, high strength, low water absorption and long durability", has become a major technical bottleneck that urgently needs to be overcome in the field of polyurethane insulation materials. Summary of the Invention

[0006] To address the aforementioned issues, a pre-composite aerogel-modified polyurethane foam insulation board and its preparation method are provided. By combining modified silica aerogel powder with modified glass fiber, a three-dimensional interpenetrating inorganic framework is pre-compositely formed. This framework, along with a polyol system and polymerized MDI, is then subjected to high-pressure foaming and in-mold curing, significantly improving the overall performance of the insulation board and achieving a synergistic balance between thermal insulation performance, flame retardant performance, and mechanical properties.

[0007] According to one aspect of this application, a pre-composite aerogel-modified polyurethane foam insulation board is provided, which is obtained by high-pressure foaming and in-mold curing of component A and component B; according to parts by weight, component A includes the following raw material components: 100 parts of polyol, 8-12 parts of modified silica aerogel powder, 10-15 parts of modified glass fiber, 31-37 parts of composite flame retardant, 4-6 parts of environmentally friendly foaming agent, 0.8-1.2 parts of deionized water, 1.2-1.8 parts of composite silicone oil stabilizer, and 0.48-0.95 parts of composite catalyst; component B includes 130-150 parts of polymeric MDI; in the reaction system formed by mixing component A and component B, the isocyanate index is 1.05-1.15; the polyol includes 70-80 parts of flame-retardant aromatic polyether polyol and 20-30 parts of phthalic anhydride polyester polyol.

[0008] Specifically, this application specifies the composition and dosage ratio of component A and component B to achieve a synergistic improvement in thermal insulation performance, mechanical properties, and flame retardant properties.

[0009] Specifically, in component A, modified silica aerogel powder and modified glass fiber are pre-dispersed and compounded by ultrasonication to form a three-dimensional interpenetrating inorganic skeleton unit of aerogel-glass fiber, which is then mixed with other components.

[0010] Optionally, the modified hydrophobic silica aerogel powder is a phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder, and the modified glass fiber is a polydopamine-phosphorus-nitrogen flame-retardant polyol grafted modified alkali-free chopped glass fiber.

[0011] Optionally, the composite flame retardant comprises low-melting-point borosilicate glass powder, organosilicon resin-coated ammonium polyphosphate, zircon powder, and melamine cyanurate, wherein the mass ratio of the low-melting-point borosilicate glass powder, organosilicon resin-coated ammonium polyphosphate, zircon powder, and melamine cyanurate is (15~20):(10~12):(3~5):(2~3).

[0012] Specifically, the composite flame retardant used in this application constitutes a synergistic flame retardant system for A2-grade ceramicization, with low-melting-point borosilicate glass powder as the core, achieving synergistic flame retardancy of phosphorus, nitrogen, boron, and silicon. At high temperatures, the glass powder softens and melts, forming a continuous and hard ceramicized heat insulation layer with zircon powder and the decomposition products of ammonium polyphosphate. Simultaneously, modified glass fiber acts as a reinforcing phase of the ceramic layer, preventing cracking and detachment of the ceramic layer at high temperatures. The nanoporous structure of the modified aerogel forms microporous heat insulation units in the ceramic layer, further blocking heat radiation and heat conduction. The modified silica aerogel powder and the modified glass fiber surface are grafted with phosphorus and nitrogen flame retardant groups, which can simultaneously participate in the char formation and ceramicization reactions, forming a multi-level flame retardant barrier of gas-phase flame retardancy and condensed-phase ceramicized heat insulation. The composite flame retardant provided in this application is deeply compatible with the inorganic skeleton and polyurethane matrix, achieving stable A2-grade non-combustibility without damaging the cell structure, completely avoiding the problems of thermal insulation and mechanical property degradation caused by excessive addition of conventional flame retardants.

[0013] Specifically, the softening temperature of the low-melting-point borosilicate glass powder is 450~550℃, and the particle size D50 is 5~10μm; the organosilicon resin-coated ammonium polyphosphate is type II ammonium polyphosphate, with a coating rate of 8~10%.

[0014] Optionally, the phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder is prepared by the following steps: first, the aerogel powder is in-situ grafted with hydroxyl groups using a fluorosilane coupling agent containing phosphorus-nitrogen flame retardant groups; then, hydroxyapatite whiskers are grown in-situ on the surface of the aerogel. The length of the hydroxyapatite whiskers is 500 nm to 2 μm and the diameter is 20 to 50 nm. The loading of hydroxyapatite whiskers is 3 to 5% of the mass of the aerogel powder.

[0015] Specifically, the preparation method of the phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder includes the following steps: the hydrophobic silica aerogel powder is vacuum dried at 100~105℃ for 1~3h, a fluorosilane coupling agent containing phosphorus-nitrogen flame retardant groups is added, and the powder is dispersed at high speed at 2500~3500rpm for 10~20min to complete the in-situ grafting modification; then calcium source and phosphorus source precursors are added, and hydroxyapatite whiskers are grown in situ by hydrothermal reaction at 110~130℃ for 5~7h. After washing and drying, the phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder is obtained. Specifically, the fluorosilane coupling agent containing phosphorus and nitrogen flame retardant groups is diphenylphosphoxypropyltrimethoxyfluorosilane, and the grafting amount of the in-situ grafting modification is 1.5 to 3% of the mass of the hydrophobic silica aerogel powder.

[0016] Specifically, the hydrophobic silica aerogel powder has a particle size of 20~80μm, a porosity ≥90%, and a thermal conductivity ≤0.020W / (m²). K) Water contact angle ≥120°.

[0017] Specifically, this application employs a dual modification process of in-situ grafting of phosphorus-nitrogen-fluorosilane and in-situ growth of hydroxyapatite whiskers to obtain in-situ grafted modified hydrophobic silica aerogel powder. The fluorosilane coupling agent containing phosphorus-nitrogen flame-retardant groups is covalently grafted, significantly improving the hydrophobicity and dispersibility of the aerogel in the polyol system, fundamentally solving the problem of aerogel agglomeration. The phosphorus-nitrogen groups also synergistically retard flame. The hydroxyapatite whiskers grown in situ on the aerogel surface form a needle-like support structure, resisting high-pressure impacts during foaming, preventing the collapse of the aerogel nanopores, and stabilizing its ultra-low thermal conductivity. Furthermore, the whiskers can form a strong interfacial bond with the polydopamine layer on the modified glass fiber surface, enhancing the structural stability of the three-dimensional framework. Simultaneously, hydroxyapatite can form a denser ceramic phase with the glass powder in the flame-retardant system at high temperatures, further improving the flame-retardant and heat-insulating effects.

[0018] Optionally, the polydopamine-phosphorus-nitrogen flame-retardant polyol grafted modified alkali-free chopped glass fiber is prepared by the following steps: first, a polydopamine nanolayer is deposited on the surface of the alkali-free chopped glass fiber, and then, by bridging with an epoxy silane coupling agent, a polyether polyol containing phosphorus-nitrogen flame-retardant groups is grafted onto the surface of the polydopamine layer. The hydroxyl value of the polyether polyol containing phosphorus-nitrogen flame-retardant groups is 350~400 mgKOH / g, and the functionality is 3~4.

[0019] Specifically, the preparation method of the polydopamine-phosphorus nitrogen flame-retardant polyol graft-modified alkali-free chopped glass fiber includes the following steps: alkali-free chopped glass fiber is placed in a Tris-HCl buffer solution with pH 8.5~10, 2 g / L dopamine hydrochloride is added, and the mixture is stirred and deposited at room temperature for 4~6 h. After filtration and drying, polydopamine-coated fiber is obtained; the coated fiber is immersed in a 5% KH-560 ethanol solution for 25~35 min, dried, and then phosphorus nitrogen flame-retardant polyether polyol is added. The mixture is stirred and reacted at 75~85℃ for 2.5~3 h, and then filtered and dried to obtain the polydopamine-phosphorus nitrogen flame-retardant polyol graft-modified alkali-free chopped glass fiber. Specifically, the alkali-free chopped glass fibers have a length of 3-6 mm and a diameter of 9-13 μm.

[0020] Specifically, this application employs a three-step modification process: polydopamine deposition, epoxy silane bridging, and phosphorus-nitrogen flame-retardant polyol grafting, to obtain polydopamine-phosphorus-nitrogen flame-retardant polyol grafted modified alkali-free chopped glass fibers. The polydopamine nanolayer achieves a strong bond with the inorganic glass fiber matrix and epoxy silane coupling agent through strong hydrogen bonds and covalent bonds, solving the problem of easy detachment during conventional silane treatment. The grafted phosphorus-nitrogen flame-retardant polyol exhibits complete reactivity compatibility with the polyol and isocyanate of the polyurethane matrix, directly participating in the polyurethane cross-linking reaction, completely eliminating interfacial defects between the fiber and the matrix, and avoiding damage to the cell structure. Furthermore, the grafted phosphorus-nitrogen groups can synergistically enhance the flame-retardant effect of the composite flame retardant, and the polydopamine layer can form strong hydrogen bonds with the hydroxyapatite whiskers on the modified aerogel surface, further strengthening the interfacial bonding stability of the three-dimensional skeleton, thus achieving a synergistic improvement in interfacial compatibility, mechanical enhancement, and synergistic flame retardancy.

[0021] Optionally, the environmentally friendly foaming agent includes HFO-1234ze; the composite catalyst includes triethylenediamine and delayed organotin, comprising 0.4 to 0.8 parts of triethylenediamine and 0.08 to 0.15 parts of delayed organotin by weight.

[0022] Specifically, triethylenediamine includes A33, and the delayed organotin includes T-12.

[0023] Specifically, the composite silicone oil stabilizer includes L-580.

[0024] Optionally, the flame-retardant aromatic polyether polyol is a phosphorus-containing flame-retardant modified polyether polyol, wherein the phosphorus-containing flame-retardant modified polyether polyol has a hydroxyl value of 390~450mgKOH / g and a functionality of 4~5; and the phthalic anhydride polyester polyol has a hydroxyl value of 280~320mgKOH / g and a functionality of 2~3.

[0025] According to another aspect of this application, a method for preparing the above-mentioned pre-composite aerogel-modified polyurethane foam insulation board is also provided, comprising the following steps: (1) Three-dimensional skeleton pre-composite: Modified aerogel powder and modified glass fiber are added to anhydrous ethanol according to the ratio, ultrasonically dispersed at 300~500W power for 20~30min, filtered and vacuum dried to obtain aerogel-glass fiber three-dimensional interpenetrating inorganic skeleton unit. (2) Preparation of Component A: Flame-retardant aromatic polyether polyol and phthalic anhydride polyester polyol were added to a reactor and heated to 55-60°C and stirred until homogeneous. Then, aerogel-glass fiber three-dimensional interpenetrating inorganic framework unit, composite flame retardant, composite silicone oil stabilizer, and composite catalyst were added sequentially. The mixture was stirred at a constant temperature of 55-65°C and 750-850 rpm for 55-65 minutes. The temperature was then lowered to below 30°C, and environmentally friendly foaming agent and deionized water were added. The mixture was stirred in a sealed container and degassed under vacuum to obtain a homogeneous Component A solution. The temperature of the Component A solution was 25±2°C, and the viscosity was 3000-5000 mPa. s; (3) High-pressure foaming and in-mold curing: The A component liquid and the B component polymerized MDI are mixed under high pressure by a high-pressure foaming machine, and injected into a mold preheated to 45~50℃ according to the set injection volume. The mold is closed and in-mold heat preservation and pressure foaming curing are carried out. (4) Post-processing and finished product processing: Demold the board after in-mold curing and send it into a constant temperature drying room for secondary curing. Then, after trimming and polishing, the pre-composite aerogel modified polyurethane foam insulation board is obtained.

[0026] Specifically, this application pre-composite modified aerogel powder with modified glass fiber to form a three-dimensional interpenetrating inorganic skeleton unit of aerogel-glass fiber. The modified glass fiber acts as a rigid support rib of the skeleton, solving the problems of aerogel nanopores being prone to collapse under high pressure during foaming and having weak mechanical properties. The modified aerogel powder is precisely filled into the mesh gaps of the modified glass fiber, blocking the thermal bridging effect of the glass fiber itself, while the nanoporous structure inhibits air convection heat transfer. The two work together to form a continuous reinforcement-thermal insulation dual-functional network in the polyurethane matrix, fundamentally solving the industry contradiction of flame retardant upgrade - thermal conductivity increase - strength decrease caused by the addition of traditional fillers alone, and achieving a synergistic balance between ultra-low thermal conductivity and ultra-high strength.

[0027] Optionally, in step (3), the injection pressure of the high-pressure foaming machine is 15~20MPa, the mixing pressure is 22~25MPa, the foaming and curing time is 15~20min, and the injection volume is calculated according to the formula "mold volume × target apparent density × 1.05 filling coefficient", and the target apparent density is 110~120kg / m³.

[0028] Optionally, in step (4), the temperature of the secondary curing is 60~65℃ and the time is 3~6h.

[0029] The beneficial effects of this application include, but are not limited to: 1. The pre-composite aerogel-modified polyurethane foam insulation board of this application forms a three-dimensional interpenetrating inorganic skeleton by pre-composite modified aerogel and modified glass fiber. Combined with a specific ratio of composite flame retardant, it achieves ultra-low thermal conductivity through the nanoporous structure of the aerogel, ensuring excellent thermal insulation performance. Furthermore, through the synergistic flame retardant effect of phosphorus-nitrogen-boron-silicon, the insulation board consistently meets the A2 non-combustible standard, releasing no highly toxic fumes during combustion, thus meeting environmental protection and fire prevention requirements. Simultaneously, the three-dimensional skeleton forms a rigid support network, and the good compatibility between the modified fiber and the polyurethane matrix avoids the problems of cell destruction and strength reduction caused by excessive addition of conventional flame retardants, significantly improving the compressive strength and structural stability of the board.

[0030] 2. The pre-composite aerogel modified polyurethane foam insulation board of this application adopts a dual modification process of in-situ grafting of phosphorus, nitrogen, fluorosilane and in-situ growth of hydroxyapatite whiskers to treat aerogel. The covalent grafting of fluorosilane coupling agent greatly improves the hydrophobicity and dispersibility of aerogel in polyol system, and avoids aerogel agglomeration. The in-situ grown hydroxyapatite whiskers form a needle-like support structure, which can resist the high pressure impact of foaming, prevent the collapse of aerogel nanopores, and ensure its ultra-low thermal insulation performance.

[0031] 3. According to the pre-composite aerogel modified polyurethane foam insulation board of this application, the glass fiber is modified in three steps: polydopamine deposition, epoxy silane bridging, and phosphorus and nitrogen flame-retardant polyol grafting. The polydopamine layer achieves a firm bond between the fiber, the matrix, and the coupling agent. The grafted flame-retardant polyol can directly participate in the polyurethane crosslinking reaction, eliminate the interface defects between the fiber and the matrix, avoid damage to the cell structure, and solve the problems of easy delamination and poor durability of conventional fiber reinforcement schemes.

[0032] 4. The preparation method of the pre-composite aerogel modified polyurethane foam insulation board according to this application has a clear preparation process, controllable parameters, mature high-pressure foaming and in-mold curing processes, scientific component ratios, no need for complex special equipment, can be directly adapted to existing polyurethane insulation board production lines, realize industrialized mass production, and facilitate large-scale promotion and utilization. Detailed Implementation

[0033] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described in this patent are for illustrative purposes only. In the following examples and comparative examples, the hydrophobic silica aerogel powder has a particle size of 20-80 μm, a porosity of 92%, and a thermal conductivity of 0.018 W / (m²). K), water contact angle 135°, alkali-free chopped glass fiber length 3~6mm, diameter 11μm.

[0035] The preparation method of in-situ grafted modified hydrophobic silica aerogel powder with phosphorus nitrogen fluorosilane-hydroxyapatite whiskers includes the following steps: the hydrophobic silica aerogel powder is vacuum dried at 105℃ for 2h, 2% of diphenylphosphoxypropyltrimethoxyfluorosilane by mass of aerogel is added, and the powder is dispersed at 3000rpm for 15min to complete the in-situ grafting modification; calcium nitrate and sodium dihydrogen phosphate precursors are then added, the calcium-phosphorus molar ratio is controlled at 1.67, and the hydroxyapatite whiskers are grown in situ at 120℃ for 6h under hydrothermal reaction. The loading of hydroxyapatite whiskers is 4% of the mass of aerogel. After washing and vacuum drying at 105℃, the in-situ grafted modified hydrophobic silica aerogel powder with phosphorus nitrogen fluorosilane-hydroxyapatite whiskers is obtained. The preparation method of polydopamine-phosphorus nitrogen flame retardant polyol graft-modified alkali-free chopped glass fiber includes the following steps: alkali-free chopped glass fiber is placed in a Tris-HCl buffer solution at pH 8.5, 2 g / L dopamine hydrochloride is added, and the mixture is stirred and deposited at room temperature for 5 h. After filtration and drying at 120 °C, polydopamine-coated fiber is obtained. The coated fiber is immersed in a 5% KH-560 ethanol solution for 30 min, dried at 120 °C, and then a phosphorus nitrogen flame retardant polyether polyol with a hydroxyl value of 380 mg KOH / g and a functionality of 3 is added. The mixture is stirred and reacted at 80 °C for 3 h, filtered, and dried at 120 °C to obtain the polydopamine-phosphorus nitrogen flame retardant polyol graft-modified alkali-free chopped glass fiber. Example 1 The following is a formulation for a pre-composite aerogel-modified polyurethane foam insulation board: Component A: 75 parts flame-retardant aromatic polyether polyol, 25 parts phthalic anhydride polyester polyol, 10 parts phosphorus-nitrogen-fluorine-silane-hydroxyapatite whisker modified aerogel powder, 12.5 parts polydopamine-phosphorus-nitrogen flame-retardant polyol modified glass fiber, 33 parts composite flame retardant (17 parts low melting point borosilicate glass powder, 11 parts organosilicon-coated ammonium polyphosphate, 3 parts zircon powder, 2 parts melamine cyanurate), 5 parts HFO-1234ze foaming agent, 1.0 part deionized water, 1.5 parts composite silicone oil stabilizer L-580, 0.6 parts triethylenediamine, and 0.1 parts delayed organotin T-12.

[0036] Component B: 140 parts of polymeric MDI, isocyanate index 1.10.

[0037] A method for preparing a pre-composite aerogel-modified polyurethane foam insulation board: (1) Three-dimensional skeleton pre-composite: Modified aerogel powder and modified glass fiber were added to anhydrous ethanol according to the ratio, ultrasonically dispersed at 400W power for 25min, filtered, and vacuum dried at 60℃ to obtain aerogel-glass fiber three-dimensional interpenetrating inorganic skeleton unit. (2) Preparation of Component A: Flame-retardant aromatic polyether polyol and phthalic anhydride polyester polyol were added to a reactor and heated to 58°C and stirred until homogeneous. Then, aerogel-glass fiber three-dimensional interpenetrating inorganic framework unit, composite flame retardant, composite silicone oil stabilizer, and composite catalyst were added sequentially. The mixture was stirred at 60°C and 800 rpm for 60 min. The temperature was lowered to 25°C, and HFO-1234ze foaming agent and deionized water were added. The mixture was stirred in a sealed container for 15 min and then vacuum degassed for 20 min to obtain a homogeneous Component A solution. The temperature of the Component A solution was 25°C and the viscosity was 4200 mPa. s; (3) High-pressure foaming and in-mold curing: The A component liquid and the B component polymerized MDI are mixed under high pressure by a high-pressure foaming machine. The injection pressure is 18MPa and the mixing pressure is 23MPa. The mixture is injected into a mold preheated to 48℃ at an injection volume of 115kg / m³×1.05. The mold is closed and in-mold heat preservation and pressure foaming curing is carried out for 18min. (4) Post-processing and finished product processing: Demold the board after in-mold curing and send it to a 65℃ constant temperature drying room for secondary curing for 4 hours. Then, after trimming and polishing, the pre-composite aerogel modified polyurethane foam insulation board is obtained.

[0038] Example 2 The following is a formulation for a pre-composite aerogel-modified polyurethane foam insulation board: Component A: 70 parts flame-retardant aromatic polyether polyol, 30 parts phthalic anhydride polyester polyol, 8 parts phosphorus-nitrogen-fluorine-silane-hydroxyapatite whisker modified aerogel powder, 10 parts polydopamine-phosphorus-nitrogen flame-retardant polyol modified glass fiber, 31 parts composite flame retardant (15 parts low melting point borosilicate glass powder, 10 parts organosilicon-coated ammonium polyphosphate, 3 parts zircon powder, 3 parts melamine cyanurate), 6 parts HFO-1234ze foaming agent, 0.8 parts deionized water, 1.2 parts composite silicone oil stabilizer L-580, 0.4 parts triethylenediamine, and 0.08 parts delayed organotin T-12.

[0039] Component B: 130 parts of polymeric MDI, isocyanate index 1.05.

[0040] A method for preparing a pre-composite aerogel-modified polyurethane foam insulation board: (1) Three-dimensional skeleton pre-composite: Modified aerogel powder and modified glass fiber were added to anhydrous ethanol according to the ratio, ultrasonically dispersed at 500W power for 20min, filtered, and vacuum dried at 60℃ to obtain aerogel-glass fiber three-dimensional interpenetrating inorganic skeleton unit. (2) Preparation of Component A: Flame-retardant aromatic polyether polyol and phthalic anhydride polyester polyol were added to a reactor and heated to 60°C and stirred until homogeneous. Then, aerogel-glass fiber three-dimensional interpenetrating inorganic framework unit, composite flame retardant, composite silicone oil stabilizer, and composite catalyst were added sequentially. The mixture was stirred at 65°C and 850 rpm for 55 min. The temperature was lowered to 25°C, and HFO-1234ze foaming agent and deionized water were added. The mixture was stirred in a sealed container for 15 min and then vacuum degassed for 20 min to obtain a homogeneous Component A solution. The temperature of the Component A solution was 25°C and the viscosity was 4200 mPa. s; (3) High-pressure foaming and in-mold curing: The A component liquid and the B component polymerized MDI are mixed under high pressure using a high-pressure foaming machine. The injection pressure is 20MPa and the mixing pressure is 25MPa. The mixture is injected into a mold preheated to 50℃ at an injection volume of 110kg / m³×1.05. The mold is closed and in-mold heat preservation and pressure foaming curing is carried out for 18min. (4) Post-processing and finished product processing: Demold the board after in-mold curing and send it to a 60℃ constant temperature drying room for secondary curing for 6 hours. Then, after trimming and polishing, the pre-composite aerogel modified polyurethane foam insulation board is obtained.

[0041] Example 3 The following is a formulation for a pre-composite aerogel-modified polyurethane foam insulation board: Component A: 80 parts of flame-retardant aromatic polyether polyol, 20 parts of phthalic anhydride polyester polyol, 12 parts of phosphorus-nitrogen-fluorine-silane-hydroxyapatite whisker modified aerogel powder, 15 parts of polydopamine-phosphorus-nitrogen flame-retardant polyol modified glass fiber, 37 parts of composite flame retardant (20 parts of low-melting-point borosilicate glass powder, 12 parts of organosilicon-coated ammonium polyphosphate, 3 parts of zircon powder, 2 parts of melamine cyanurate), 4 parts of HFO-1234ze foaming agent, 1.2 parts of deionized water, 1.8 parts of composite silicone oil stabilizer L-580, 0.8 parts of triethylenediamine, and 0.15 parts of delayed organotin T-12.

[0042] Component B: 150 parts of polymeric MDI, isocyanate index 1.15.

[0043] A method for preparing a pre-composite aerogel-modified polyurethane foam insulation board: (1) Three-dimensional skeleton pre-composite: Modified aerogel powder and modified glass fiber were added to anhydrous ethanol according to the ratio, ultrasonically dispersed at 300W power for 30min, filtered, and vacuum dried at 60℃ to obtain aerogel-glass fiber three-dimensional interpenetrating inorganic skeleton unit. (2) Preparation of Component A: Flame-retardant aromatic polyether polyol and phthalic anhydride polyester polyol were added to a reactor and heated to 55°C and stirred until homogeneous. Then, aerogel-glass fiber three-dimensional interpenetrating inorganic framework unit, composite flame retardant, composite silicone oil stabilizer, and composite catalyst were added sequentially. The mixture was stirred at 55°C and 750 rpm for 55 min. The temperature was lowered to 25°C, and HFO-1234ze foaming agent and deionized water were added. The mixture was stirred in a sealed container for 15 min and then vacuum degassed for 20 min to obtain a homogeneous Component A solution. The temperature of the Component A solution was 25°C and the viscosity was 4200 mPa. s; (3) High-pressure foaming and in-mold curing: The A component liquid and the B component polymerized MDI are mixed under high pressure by a high-pressure foaming machine. The injection pressure is 15MPa and the mixing pressure is 22MPa. The mixture is injected into a mold preheated to 48℃ at an injection volume of 120kg / m³×1.05. The mold is closed and in-mold heat preservation and pressure foaming curing is carried out for 18min. (4) Post-processing and finished product processing: Demold the board after in-mold curing and send it to a 65℃ constant temperature drying room for secondary curing for 3 hours. Then, after trimming and polishing, the pre-composite aerogel modified polyurethane foam insulation board is obtained.

[0044] Example 4 The difference between Example 4 and Example 1 is that the composite flame retardant includes 15 parts of low-melting-point borosilicate glass powder, 12 parts of organosilicon-coated ammonium polyphosphate, 5 parts of zircon powder, and 2 parts of melamine cyanurate, while the rest are the same.

[0045] Example 5 The difference between Example 5 and Example 1 is that 12 parts of phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker modified aerogel powder and 10 parts of polydopamine-phosphorus-nitrogen flame retardant polyol modified glass fiber are used, while the rest are the same.

[0046] Example 6 The difference between Example 6 and Example 1 is that 8 parts of phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker modified aerogel powder and 15 parts of polydopamine-phosphorus-nitrogen flame-retardant polyol modified glass fiber are used, while the rest are the same.

[0047] Example 7 The difference between Example 7 and Example 1 is that the modified silica aerogel powder is modified with conventional KH-550 aminosilane, and the modified glass fiber is impregnated with conventional KH-550 silane. Furthermore, the two are not pre-composite and are directly added to the reaction vessel separately. All other aspects are the same.

[0048] Example 8 The difference between Example 8 and Example 1 is that the composite flame retardant consists of 11 parts of organosilicon-coated ammonium polyphosphate, 17.5 parts of silane-modified aluminum hydroxide, and 4.5 parts of melamine cyanurate; the rest are the same.

[0049] Example 9 The difference between Example 9 and Example 1 is that in the composite flame retardant, there are 8.25 parts of low melting point borosilicate glass powder, 8.25 parts of organosilicon-coated ammonium polyphosphate, 8.25 parts of zircon powder, and 8.25 parts of melamine cyanurate; the rest are the same.

[0050] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the modified silica aerogel powder was replaced with an equal amount of kaolin, while all other aspects were the same.

[0051] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not include modified glass fiber, but all other aspects are the same.

[0052] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the step (1) of three-dimensional skeleton pre-composite is not included. The modified aerogel powder and modified glass fiber are directly added to the reactor. All other aspects are the same.

[0053] Experimental Example 1 After the insulation boards prepared in Examples 1-9 and Comparative Examples 1-3 were placed for 7 days, performance tests were conducted according to the core technical indicators. The applicable standards were: thermal conductivity - GB / T10294; combustion performance - GB8624-2012; compressive strength - GB / T8813; volumetric water absorption - GB / T8810; apparent density - GB / T6343. The test results are shown in Table 1. Table 1 Performance Test Results

[0054] As shown in Table 1, the insulation board provided by this application exhibits excellent performance in all aspects, achieving A2-level flame retardancy. Compared with the comparative examples, the performance of Examples 1-6 is improved in a balanced manner. However, compared with Example 1, the performance of Example 7 is lower, and a continuous and complete ceramicized insulation layer is not formed. The reason for this is that the modification method of the modified silica aerogel powder and modified glass fiber has been changed. Example 8 uses a conventional flame retardant system, which achieves A2-level flame retardancy, but there is no hard ceramic layer after combustion, and the char layer is easy to powder and fall off. The heat insulation and anti-collapse performance at high temperatures is far worse than the ceramicized system formed by the composite flame retardant of this invention. The flame retardant performance of Example 9 is lower, which is attributed to the change in the component ratio and their synergistic effect. In Comparative Example 1, the modified silica aerogel powder and modified glass fiber are removed. After silica aerogel powder was applied, the thermal conductivity increased sharply, and the flame retardancy rating dropped to B1, demonstrating the core role of the modified aerogel in the synergistic effect of low thermal conductivity and flame retardancy. In Comparative Example 2, after removing glass fiber, the compressive strength decreased significantly, and the ceramic layer cracked due to lack of support during combustion, with the flame retardancy rating dropping to B1, proving that the modified glass fiber is the core support for mechanical strength and ceramic flame retardancy, and the three-dimensional skeleton formed by the pre-composite of the two has an irreplaceable synergistic effect. In Comparative Example 3, without pre-composite, the modified aerogel and glass fiber were directly added, and the performance decreased significantly compared to Example 1, proving that the three-dimensional interpenetrating skeleton constructed by the pre-composite process is the key to achieving the synergistic effect of the two, which is fundamentally different from the simple mixing method of the prior art.

[0055] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A pre-composite aerogel-modified polyurethane foam insulation board, characterized in that, The product is prepared by high-pressure foaming and in-mold curing of components A and B. By weight, component A comprises the following raw materials: 100 parts polyol, 8-12 parts modified silica aerogel powder, 10-15 parts modified glass fiber, 31-37 parts composite flame retardant, 4-6 parts environmentally friendly foaming agent, 0.8-1.2 parts deionized water, 1.2-1.8 parts composite silicone oil stabilizer, and 0.48-0.95 parts composite catalyst. Component B comprises 130-150 parts polymeric MDI. In the reaction system formed by mixing components A and B, the isocyanate index is 1.05-1.

15. The polyol comprises 70-80 parts flame-retardant aromatic polyether polyol and 20-30 parts phthalic anhydride polyester polyol.

2. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 1, characterized in that, The modified hydrophobic silica aerogel powder is a phosphorus-nitrogen-fluorine-silane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder, and the modified glass fiber is a polydopamine-phosphorus-nitrogen flame-retardant polyol grafted modified alkali-free chopped glass fiber.

3. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 1, characterized in that, The composite flame retardant comprises low-melting-point borosilicate glass powder, organosilicon resin-coated ammonium polyphosphate, zircon powder, and melamine cyanurate, wherein the mass ratio of the low-melting-point borosilicate glass powder, organosilicon resin-coated ammonium polyphosphate, zircon powder, and melamine cyanurate is (15~20):(10~12):(3~5):(2~3).

4. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 2, characterized in that, The phosphorus-nitrogen-fluorosilane-hydroxyapatite whisker in-situ grafted modified hydrophobic silica aerogel powder is prepared by the following steps: first, the aerogel powder is in-situ grafted with hydroxyl groups using a fluorosilane coupling agent containing phosphorus-nitrogen flame-retardant groups; then, hydroxyapatite whiskers are grown in-situ on the surface of the aerogel. The length of the hydroxyapatite whiskers is 500 nm to 2 μm and the diameter is 20 to 50 nm. The loading of hydroxyapatite whiskers is 3 to 5% of the mass of the aerogel powder.

5. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 2, characterized in that, The polydopamine-phosphorus-nitrogen flame-retardant polyol graft-modified alkali-free chopped glass fiber is prepared by the following steps: first, a polydopamine nanolayer is deposited on the surface of the alkali-free chopped glass fiber, and then, by bridging with an epoxy silane coupling agent, a polyether polyol containing phosphorus-nitrogen flame-retardant groups is grafted onto the surface of the polydopamine layer. The hydroxyl value of the polyether polyol containing phosphorus-nitrogen flame-retardant groups is 350~400 mgKOH / g, and the functionality is 3~4.

6. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 1, characterized in that, The environmentally friendly foaming agent includes HFO-1234ze; the composite catalyst includes triethylenediamine and delayed organotin, comprising 0.4-0.8 parts of triethylenediamine and 0.08-0.15 parts of delayed organotin by weight.

7. The pre-composite aerogel-modified polyurethane foam insulation board according to claim 1, characterized in that, The flame-retardant aromatic polyether polyol is a phosphorus-containing flame-retardant modified polyether polyol, wherein the hydroxyl value of the phosphorus-containing flame-retardant modified polyether polyol is 390~450mgKOH / g and the functionality is 4~5; the hydroxyl value of the phthalic anhydride polyester polyol is 280~320mgKOH / g and the functionality is 2~3.

8. A method for preparing a pre-composite aerogel-modified polyurethane foam insulation board according to any one of claims 1 to 7, characterized in that, Includes the following steps: (1) Three-dimensional skeleton pre-composite: Modified aerogel powder and modified glass fiber are added to anhydrous ethanol according to the ratio, ultrasonically dispersed at 300~500W power for 20~30min, filtered and vacuum dried to obtain aerogel-glass fiber three-dimensional interpenetrating inorganic skeleton unit. (2) Preparation of Component A: Flame-retardant aromatic polyether polyol and phthalic anhydride polyester polyol were added to a reactor and heated to 55-60°C and stirred until homogeneous. Then, aerogel-glass fiber three-dimensional interpenetrating inorganic framework unit, composite flame retardant, composite silicone oil stabilizer, and composite catalyst were added sequentially. The mixture was stirred at a constant temperature of 55-65°C and 750-850 rpm for 55-65 minutes. The temperature was then lowered to below 30°C, and environmentally friendly foaming agent and deionized water were added. The mixture was stirred in a sealed container and degassed under vacuum to obtain a homogeneous Component A solution. The temperature of the Component A solution was 25±2°C, and the viscosity was 3000-5000 mPa. s; (3) High-pressure foaming and in-mold curing: The A component liquid and the B component polymerized MDI are mixed under high pressure by a high-pressure foaming machine, and injected into a mold preheated to 45~50℃ according to the set injection volume. The mold is closed and in-mold heat preservation and pressure foaming curing are carried out. (4) Post-processing and finished product processing: Demold the board after in-mold curing and send it into a constant temperature drying room for secondary curing. Then, after trimming and polishing, the pre-composite aerogel modified polyurethane foam insulation board is obtained.

9. The method for preparing a pre-composite aerogel-modified polyurethane foam insulation board according to claim 8, characterized in that, In step (3), the injection pressure of the high-pressure foaming machine is 15~20MPa, the mixing pressure is 22~25MPa, the foaming and curing time is 15~20min, the injection volume is calculated according to the formula "mold volume × target apparent density × 1.05 filling coefficient", and the target apparent density is 110~120kg / m³.

10. The method for preparing a pre-composite aerogel-modified polyurethane foam insulation board according to claim 8, characterized in that, In step (4), the temperature of the secondary curing is 60~65℃ and the time is 3~6h.

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