High-pressure-resistant polyurethane insulation board and preparation method thereof

Abstract

The application relates to the technical field of composite insulation boards, and discloses a high-pressure-resistant polyurethane insulation board and a preparation method thereof, which comprises a polyurethane foam base body and a plurality of layers of continuous glass fiber felt reinforcing layers distributed in the polyurethane foam base body; the plurality of layers of continuous glass fiber felt reinforcing layers comprise at least two kinds of glass fiber felt layers with different gram weights, and are arranged in a gram weight gradient distribution along the thickness direction of the composite insulation board; the polyurethane foam base body is prepared by reaction foaming of an A component and a B component, wherein the A component is a polymethylene polyphenyl isocyanate, and the B component comprises a composite coupling agent and a high-molecular-weight polyester polyol; the composite coupling agent is prepared by compounding a silane coupling agent and a titanate coupling agent, the composite coupling agent and the composite coupling agent cooperatively form a flexible buffer transition layer at the bonding interface of the glass fiber and the polyurethane foam base body, are used for absorbing and dissipating interfacial thermal stress under an extremely low-temperature environment, effectively improve the compression strength of the composite board, and meet the bearing requirements of heavy-load floors.

Description

Technical Field

[0001] This invention relates to the field of insulation board technology, specifically to a high-compression-resistant polyurethane insulation board and its preparation method. Background Technology

[0002] With the rapid development of the cold chain logistics industry, cold storage buildings have placed extremely high demands on floor insulation materials. Cold storage floors and heavy-duty floors not only need to have extremely low thermal conductivity to maintain cooling capacity, but must also be able to withstand the long-term rolling load of heavy equipment such as forklifts, while resisting the severe thermal expansion and contraction stress under extremely low temperature environments.

[0003] Currently, rigid polyurethane foam is widely used in building insulation due to its excellent thermal insulation performance and lightweight properties. However, pure rigid polyurethane foam, when used as a flooring substrate, suffers from low compressive strength and poor low-temperature dimensional stability, easily leading to floor cracking or delamination. To compensate for these structural deficiencies, extruded polystyrene (XPS) foam boards are commonly used for cold storage floors. However, XPS boards have a higher thermal conductivity, resulting in lower insulation efficiency than polyurethane; furthermore, their low-temperature dimensional stability is insufficient, and their relatively smooth and dense surface leads to poor interfacial adhesion with cement mortar or polyurethane adhesives, making them highly susceptible to large-area delamination under alternating hot and cold conditions.

[0004] To improve the mechanical properties of polyurethane insulation boards, existing technologies have introduced multi-layer fiberglass mats for composite reinforcement. However, traditional fiberglass reinforced polyurethane composite boards often use simple stacking of single-weight fiberglass mats (e.g., multiple layers of 600g / m² high-weight fiberglass mats). In continuous dual-track foaming processes, the polyurethane foam mixture has high reactivity and extremely rapid viscosity increases. When facing a homogeneous, high-weight, dense layer of fiberglass mat, the foaming material struggles to achieve complete vertical penetration. This results in resin accumulation on the surface of the insulation board, while the central layer inevitably exhibits "dry spots" due to insufficient adhesive. This not only fails to provide synergistic load-bearing support but also creates structural weaknesses.

[0005] Furthermore, the coefficients of thermal expansion of inorganic glass fiber materials and organic polyurethane foam matrices differ significantly. In the extremely cold environment of -30°C in cold storage, the thermal shrinkage stress at the interface is extremely concentrated. Existing reinforcement schemes generally lack targeted interface compatibilization and flexibility designs, resulting in a brittle rigid bond between the glass fiber and the resin matrix. Under the combined effects of long-term loading and extremely low-temperature shrinkage, interfacial shear failure easily occurs within the composite board, leading to severe interlayer debonding and delamination. Summary of the Invention

[0006] This invention provides a high-compression-resistant polyurethane insulation board and its preparation method, aiming to solve the problems mentioned in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A high-compression-resistant polyurethane insulation board includes a polyurethane foam matrix and a multi-layer continuous fiberglass felt reinforcement layer distributed inside the polyurethane foam matrix; the multi-layer continuous fiberglass felt reinforcement layer includes at least two fiberglass felt layers with different basis weights, and is arranged in a basis weight gradient distribution along the thickness direction of the insulation board. The polyurethane foam matrix is ​​obtained by reacting and foaming components A and B. Component A is polymethylene polyphenyl isocyanate, and component B includes a composite coupling agent and a high molecular weight polyester polyol. The composite coupling agent is a compound of a silane coupling agent and a titanate coupling agent. The high molecular weight polyester polyol has a hydroxyl value of 50-100 mgKOH / g. It and the composite coupling agent work together to form a flexible buffer transition layer at the interface between the glass fiber and the polyurethane foam matrix, which is used to absorb and dissipate interfacial thermal stress under extremely low temperature conditions.

[0008] Preferably, the multilayer continuous fiberglass mat reinforcement layer has a three-layer structure, consisting of a first fiberglass mat layer, a second fiberglass mat layer, and a third fiberglass mat layer in sequence along the thickness direction; The first and third fiberglass felt layers are low-weight buffer layers with a basis weight of 450 g / m²; the second fiberglass felt layer is located in the center and is the main load-bearing high-weight layer with a basis weight of 600 g / m²; thus forming a low-high-low basis weight gradient structure.

[0009] Preferably, the multilayer continuous fiberglass mat reinforcement layer has a five-layer structure, and the basis weight distribution along the thickness direction is a gradient symmetrical structure of low-medium-high-medium-low.

[0010] Preferably, in the composite coupling agent, the weight ratio of silane coupling agent to titanate coupling agent is 1:0.5 to 2; The titanate coupling agent is used to reduce the local reactive viscosity of the polyurethane foam mixture on the surface of the continuous fiberglass mat. In conjunction with the silane coupling agent, it guides the mixture through the outer low-basis-weight fiberglass mat layer and into the inner high-basis-weight fiberglass mat layer for deep wetting.

[0011] Preferably, component B comprises, by weight: 40-80 parts of polyether polyol; 20-60 parts of polyester polyol; Foam stabilizer 1.0–3.0 parts; Catalyst 0.5–2.0 parts; 10-25 parts of foaming agent; 0.5–2.0 parts of the composite coupling agent; 0.5 to 1.5 parts of high molecular weight polyester polyol.

[0012] Preferably, the high molecular weight polyester polyol has lower reactivity than the polyether polyol and the polyester polyol, so as to delay the local curing rate of the system in the early stage of foaming and provide a time window for the wetting gradient to enhance the structure.

[0013] This application also discloses a continuous preparation method for high-compression-resistant polyurethane insulation boards, comprising the following steps: Step S1: Multi-layer fiberglass mats are simultaneously unrolled and laid to form a gradient alternating layered structure with a preset weight. Step S2: Mix component A and component B and apply them evenly to the surface of the multilayer fiberglass mat. Use gravity and the fluidity of the mixture to allow it to penetrate downwards and wet each fiberglass mat layer. Step S3: The material is fed into a dual-track laminator and foamed, cured, and matured at 25-45°C to form an integrated composite board. Step S4: Cut to length to obtain the finished product.

[0014] Preferably, before coating in step S2, a preheating step is included; the preheating temperature is matched with the activation temperature of the titanate coupling agent in component B, so as to utilize the thermocapillary effect to accelerate the vertical penetration of the foamed mixture in the low-high-low gradient structure.

[0015] Preferably, in step S3, the dual-track laminator has a temperature gradient inside along the direction of travel; The temperature gradient is specifically set as follows: the temperature of the front entry zone is set at 25-30°C to keep the mixture in a low viscosity state so as to fully wet the high basis weight glass fiber mat layer in the center; the temperature of the rear curing zone is set at 35-45°C to promote the rapid cross-linking and curing of the composite coupling agent between the fully impregnated polyurethane system and the glass fiber interface.

[0016] This application also discloses the application of a high-compression-strength polyurethane insulation board in insulation materials for cold storage floors or heavy-duty flooring buildings.

[0017] The technical effects and advantages of this invention are as follows: 1. This invention improves the permeability of the foaming system in the reinforcing layer by setting a multi-layered fiberglass felt structure with a gradient basis weight distribution and combining it with the local viscosity-reducing effect of the titanate component in the composite coupling agent. During continuous casting foaming, the low-basis-weight fiberglass felt on the surface provides a relatively smooth physical penetration channel for the foaming material, while the titanate coupling agent helps reduce the reactive viscosity of the polyurethane mixture at the fiberglass interface. The synergistic effect of the two allows the foaming material to smoothly penetrate the surface layer and fully wet the high-basis-weight main load-bearing layer in the center, reducing the central lack of glue and uneven resin enrichment that are prone to occur in conventional homogeneous high-density fiberglass stacking. Under load, the low-basis-weight layers on both sides provide stress buffering, while the high-basis-weight layer in the middle bears the deformation of the main body, thereby effectively improving the compressive strength of the composite board without increasing the overall density of the foam, meeting the load-bearing requirements of heavy-duty flooring.

[0018] 2. To address the problem of interfacial stress concentration leading to debonding between inorganic glass fiber and organic resin matrix at extremely low temperatures due to the difference in their coefficients of thermal expansion, this invention introduces a high molecular weight polyester polyol with a specific hydroxyl value and a composite coupling agent into the foaming system. During the curing stage, the long, flexible segments of the high molecular weight polyester polyol crosslink with the coupling agent, forming a flexible buffer transition zone on the interface between the glass fiber and polyurethane foam. This flexible interface alters the rigid and brittle bonding state between traditional materials, effectively absorbing and dissipating the thermal expansion and contraction stress generated under extremely low temperature conditions. This mechanism reduces the stress concentration at the interface, improves the interlayer shear bond strength, thereby improving the low-temperature dimensional stability of the insulation board and reducing the risk of interlayer delamination and delamination during long-term alternating hot and cold use.

[0019] 3. The continuous preparation process and formulation design of this invention are compatible, ensuring sufficient wetting of the glass fiber reinforcement layer while maintaining the thermal insulation performance of the foam matrix. Utilizing the delayed local gelation rate effect of a low-reactivity high-molecular-weight polyester polyol, combined with the temperature gradient setting of "low temperature at the front and high temperature at the back" within the dual-track laminator, a suitable time window is provided for the foaming mixture to penetrate the multi-layer gradient glass fibers. This synergy between the process thermal field and reaction kinetics allows the mixture to undergo foaming and curing of the main body only after deep wetting, avoiding cell rupture or uneven density distribution caused by premature foaming and extrusion. Therefore, the cured polyurethane matrix maintains a high closed-cell rate and microscopic homogeneity, preserving the inherent low thermal conductivity of polyurethane materials; simultaneously, the gradient weight design optimizes material configuration and enhances the engineering practicality of the product. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the three-layer gradient reinforced polyurethane insulation board structure in Embodiment 1. Figure 2 This is a schematic diagram of the five-layer gradient reinforced polyurethane insulation board structure in Embodiment 2. Figure 3 This is a schematic diagram of the microstructure of the glass fiber and polyurethane matrix interface of the present invention; Figure 4 These are cross-sectional views comparing the resin impregnation of gradient structure and equal weight structure in Embodiment 1 and Comparative Example 1 of the present invention. Figure 5 This is a comparison diagram of the compressive strength of various embodiments and comparative examples of the present invention; Figure 6 This is a schematic diagram illustrating the production principle of the high compressive strength gradient reinforced polyurethane insulation board of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that, unless otherwise specified, all terms "parts" or "ratios" mentioned in this specification are calculated by weight. All raw materials and reagents used in this invention are commercially available products. Specifically: Polymethylene polyphenyl isocyanate (PMDI): Wanhua Chemical, brand name PM-200; Polyether polyol: Sucrose-based polyether polyol, hydroxyl value 400-450 mgKOH / g; Polyester polyols: Phthalic anhydride polyester polyols, hydroxyl value 300-350 mgKOH / g; High molecular weight polyester polyol: Adipic acid-butanediol type linear polyester is used, and the hydroxyl value is set according to the example; Silane coupling agent: Grade KH-550; Titanate coupling agent: Grade NDZ-201; Foam stabilizer: Organosilicon surfactant AK-8805; Catalyst: Foaming catalyst A33 and gel catalyst T-12 are compounded in a weight ratio of 2:1; Foaming agent: HFO-1233zd (trans-1-chloro-3,3,3-trifluoropropylene), with a gas phase thermal conductivity as low as 0.010 W / (m·K), giving the foam superior thermal insulation performance; and with an ODP of zero and a GWP of 1, it belongs to the fourth generation of low-GWP environmentally friendly foaming agents.

[0023] Please see Figures 1-6This invention provides a high-compression-resistant polyurethane insulation board suitable for cold storage floors and heavy-duty flooring structures. The insulation board comprises a polyurethane foam matrix and multiple layers of continuous fiberglass mat reinforcement distributed within the matrix.

[0024] In this embodiment, the multi-layer continuous fiberglass felt exhibits a weight gradient distribution along the thickness direction of the insulation board. In a preferred embodiment, the multi-layer continuous fiberglass felt has a three-layer structure, consisting of a first fiberglass felt layer (450g / m², low weight), a second fiberglass felt layer (600g / m², high weight main load-bearing layer), and a third fiberglass felt layer (450g / m², low weight), forming a low-high-low symmetrical gradient structure. In another embodiment, the multi-layer continuous fiberglass felt can also employ a five-layer structure, such as a low-medium-high-medium-low gradient structure with layer weights of 300g / m², 450g / m², 600g / m², 450g / m², and 300g / m².

[0025] The polyurethane foam matrix is ​​prepared by mixing and foaming component A and component B according to a conventional isocyanate index (usually 1.05–1.20). Component A is polymethylene polyphenyl isocyanate (PMDI). By weight, the basic formulation of component B includes: 40–80 parts of polyether polyol; 20–60 parts of polyester polyol; 1.0–3.0 parts of foam stabilizer (such as silicone oil); 0.5–2.0 parts of catalyst (such as amine or tin catalyst); and 10–25 parts of blowing agent (HFO-1233zd or hydrofluoroolefin blowing agent).

[0026] To complement the aforementioned gradient glass fiber structure, 0.5–2.0 parts of a composite coupling agent and 0.5–1.5 parts of a high molecular weight polyester polyol (hydroxyl value of 50–100 mg KOH / g) are specifically added to component B.

[0027] The composite coupling agent is a mixture of a silane coupling agent (such as KH-550) and a titanate coupling agent at a weight ratio of 1:0.5 to 2. The titanate coupling agent can significantly reduce the local reactive viscosity of the foamed mixture on the surface of the continuous fiberglass mat, thereby guiding the polyurethane mixture to quickly penetrate the outer low-basis-weight layer and deeply wet the high-basis-weight fiberglass layer in the center. Meanwhile, the high-molecular-weight polyester polyol, due to its lower reactivity, can provide a wetting delay time in the early stages of foaming. Simultaneously, after foaming and curing, the high-molecular-weight polyester polyol and the composite coupling agent form a flexible buffer transition layer in situ at the interface between the fiberglass and the polyurethane foam matrix. This transition layer can effectively absorb and dissipate the interfacial thermal expansion and contraction stress under extremely low temperature (-20℃ to -30℃) conditions, solving the problem of interfacial debonding and delamination.

[0028] Continuous preparation method The above-mentioned insulation board is produced using a dual-track continuous foaming production line, and the specific steps include: Step S1: Multiple rolls of continuous fiberglass mat with different weights are simultaneously unwound and laid before entering the track section to form a preset alternating layered structure (e.g., 450-600-450g / m²). Step S2: Preheat the multilayer fiberglass mat online at a temperature of 35-45°C (matching the activation temperature of the titanate coupling agent). Then, apply the uniformly mixed components A and B through a high-pressure mixing head to the surface of the top layer of fiberglass mat, and use gravity, the fluidity of the mixture and the thermocapillary effect to make it penetrate downwards. Step S3: The composite material is fed into a dual-track laminator for foaming and curing. The dual-track laminator is set with a temperature gradient: the temperature of the front entry zone is controlled at 25-30℃ (to maintain low viscosity and fully penetrate the high-density central layer), and the temperature of the rear curing zone is controlled at 35-45℃ (to promote rapid cross-linking and curing of the interfacial coupling agent and polyurethane system), forming an integrated composite board; Step S4: After the board is produced, cut it to the specified length to obtain the finished product.

[0029] The following are specific verification examples and comparative examples: Example 1

[0030] This embodiment provides a three-layer gradient reinforced polyurethane insulation board, the preparation process of which is as follows: Preparation of Component B: 60 parts polyether polyol, 40 parts polyester polyol, 2.0 parts foam stabilizer, 1.5 parts composite catalyst, and 18 parts blowing agent were added to a mixing tank and stirred until homogeneous. Then, 1.5 parts composite coupling agent (a 1:1 weight mixture of KH-550 and NDZ-201) and 1.0 part high molecular weight polyester polyol (hydroxyl value 75 mg KOH / g) were added, and stirring continued at room temperature for 30 minutes to obtain the white component of Component B. The black component of Component A was PM-200. The isocyanate index of both Component A and Component B was controlled to be 1.10.

[0031] Step S1: On the dual-track continuous production line, three unwinding stations are set up to simultaneously unwind three layers of continuous fiberglass mat. The layup structure is pre-set as follows (from bottom to top): first fiberglass mat layer (450g / m²), second fiberglass mat layer (600g / m²), and third fiberglass mat layer (450g / m²), forming a low-high-low gradient alternating structure. Step S2: The three layers of fiberglass mat proceed synchronously into the infrared heating oven for online preheating at 40°C to activate the titanate coupling agent to be coated subsequently. Then, components A and B are rapidly mixed using a high-pressure mixing head (injection pressure 12MPa), and uniformly poured and coated onto the surface of the third fiberglass mat layer (the top layer) in a multi-stream pattern. The foamed mixture penetrates vertically downwards under the combined effects of gravity, fiberglass capillary action, and the viscosity-reducing effect of the titanate. Step S3: The composite material is fed into a 24-meter-long dual-track laminator along the production line. The dual-track laminator is divided into two temperature zones: the front entry zone (0-8 meters) is set at 28°C, which delays the rapid gelation of the foaming system by using a lower temperature, giving the mixture a time window to fully impregnate the central 600g / m² high-density layer; the rear curing zone (8-24 meters) is set at 42°C, which promotes the rapid cross-linking of high molecular weight polyester polyol and interfacial coupling agent, forming a flexible buffer transition layer and completing the overall curing and foaming; the production line speed is controlled at 5m / min. Step S4: After the plate exits from the dual tracks, it is cut by a fixed-length follow-up cutting machine to obtain a finished plate with a thickness of 100mm. Example 2

[0032] This embodiment provides a five-layer gradient reinforced polyurethane insulation board.

[0033] Except for the composite coupling agent being 1.8 parts (silane to titanate weight ratio 1:0.8) and the high molecular weight polyester polyol being 1.5 parts (hydroxyl value 100mgKOH / g), the other raw materials and proportions of component B are the same as in Example 1.

[0034] In step S1, five unwinding stations are set up, and the layup structure of the multi-layer continuous fiberglass mat along the thickness direction is preset to a low-medium-high-medium-low gradient: 300g / m², 450g / m², 600g / m², 450g / m², and 300g / m², respectively.

[0035] In step S2, the glass fiber preheating temperature is set to 35°C. In step S3, the front entry zone temperature is 25°C, and the rear curing zone temperature is 45°C. The remaining processes are the same as in Example 1. Example 3

[0036] This embodiment provides a three-layer gradient reinforced polyurethane insulation board.

[0037] Component B is adjusted to: 70 parts polyether polyol, 30 parts polyester polyol, 0.8 parts composite coupling agent (silane to titanate weight ratio 1:1.5), 0.5 parts high molecular weight polyester polyol (hydroxyl value 50mgKOH / g), and the remaining additives are the same as in Example 1.

[0038] The glass fiber gradient structure and preparation process parameters are the same as in Example 1.

[0039] Comparative Example 1 This comparative example uses a traditional single-weight stacking method to prepare the insulation board.

[0040] The difference lies in step S1: the three-layer fiberglass mat is pre-laid with equal weights: the first layer (600g / m²), the second layer (600g / m²), and the third layer (600g / m²).

[0041] The other parameters of the formulation and preparation process (such as preheating at 40°C and temperature gradient of 28°C / 42°C) are exactly the same as those in Example 1.

[0042] Comparative Example 2 This comparative example uses a conventional foaming formula to prepare gradient insulation boards.

[0043] The difference lies in the formulation preparation: no composite coupling agent or high molecular weight polyester polyol is added to component B, but an equal amount of conventional polyester polyol is added.

[0044] The layup structure (low-high-low gradient) and other parameters of the preparation process are exactly the same as in Example 1.

[0045] Comparative Example 3 The difference lies in the formulation preparation: Component B contains only 1.5 parts of a single type of silane coupling agent KH-550, without adding titanate coupling agent NDZ-201, and without adding high molecular weight polyester polyol.

[0046] The layup structure and process parameters are the same as in Example 1.

[0047] Comparative Example 4 Commercially available rigid polyurethane foam boards for cold storage (without any fiberglass reinforcement).

[0048] Performance Testing and Results Analysis Samples were taken from Examples 1-3 and Comparative Examples 1-4, and performance tests were conducted after standing for 48 hours.

[0049] Compressive strength: The compressive strength perpendicular to the plate surface (with 10% deformation) is tested according to GB / T8813.

[0050] Low-temperature dimensional stability: According to GB / T8811, the sample was placed in a -30℃ low-temperature chamber for 24 hours, and the volume change rate in the length, width and thickness directions was measured.

[0051] Interlaminar shear strength: The shear fracture strength at the interface between the core layer and the glass fiber reinforcement layer was determined using a universal testing machine to characterize the interfacial bonding state.

[0052] Cross-sectional micromorphology: The central section of the board was cut open, and the fiberglass layer was observed with the naked eye and a magnifying glass to see whether it was completely wrapped by resin.

[0053] The test results are shown in Table 1.

[0054] Table 1. Performance test results of each embodiment and comparative example.

[0055] Results analysis: Comparing Example 1 and Comparative Example 1, with similar total basis weights, Comparative Example 1, using a full 600g / m² structure, experienced excessive resistance when the foaming material penetrated the top layer, leading to localized resin accumulation on the surface and "dry spots" (insufficient adhesive) appearing in the central layer. These became weak points under pressure, resulting in a compressive strength of only 0.52MPa. Example 1, employing a low-high-low gradient, allowed for rapid resin penetration in the low basis weight of the surface layer, while the central layer, as the main load-bearing layer, was fully impregnated and cured, increasing the compressive strength to 0.68MPa.

[0056] As can be seen from the comparison of Example 1 and Comparative Example 3, Comparative Example 3, using only conventional silane coupling agents, resulted in localized dry spots in the central high-density layer due to the excessively rapid increase in the viscosity of the foam material, even with a gradient structure. Example 1, by introducing a titanate coupling agent in conjunction with a preheating process, effectively utilized the significant local viscosity-reducing effect of titanate on the polyurethane foam system, perfectly guiding deep penetration.

[0057] The core problem of low-temperature delamination addressed by this invention was demonstrated by Comparative Example 2. Comparative Example 2 lacked a high-molecular-weight polyester polyol and a composite coupling agent. Although the impregnation was good, the interface exhibited a rigid bond, with an interlayer shear strength of only 0.35 MPa. After a -30°C freezing test, the different shrinkage rates of the resin and glass fiber led to microcracks. Example 1, utilizing a high-molecular-weight polyester polyol with a specific hydroxyl value and a coupling agent, generated a flexible buffer transition layer in situ at the interface, achieving an interlayer shear strength as high as 0.85 MPa, thus completely solving the delamination problem of cold storage flooring under extremely low-temperature environments.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-compression-resistant polyurethane insulation board, comprising a polyurethane foam matrix and a multi-layer continuous fiberglass mat reinforcement layer distributed within the polyurethane foam matrix; characterized in that: The multi-layer continuous fiberglass felt reinforcement layer includes at least two fiberglass felt layers with different basis weights, and is arranged in a basis weight gradient distribution along the thickness direction of the insulation board. The polyurethane foam matrix is ​​obtained by reacting and foaming components A and B. Component A is polymethylene polyphenyl isocyanate, and component B includes a composite coupling agent and a high molecular weight polyester polyol. The composite coupling agent is a compound of a silane coupling agent and a titanate coupling agent. The high molecular weight polyester polyol has a hydroxyl value of 50-100 mgKOH / g. It and the composite coupling agent work together to form a flexible buffer transition layer at the interface between the glass fiber and the polyurethane foam matrix, which is used to absorb and dissipate interfacial thermal stress under extremely low temperature conditions.

2. The high-compression-resistant polyurethane insulation board according to claim 1, characterized in that, The multi-layer continuous fiberglass mat reinforcement layer has a three-layer structure, consisting of a first fiberglass mat layer, a second fiberglass mat layer, and a third fiberglass mat layer along the thickness direction. The first and third fiberglass felt layers are low-weight buffer layers with a basis weight of 450 g / m²; the second fiberglass felt layer is located in the center and is the main load-bearing high-weight layer with a basis weight of 600 g / m²; thus forming a low-high-low basis weight gradient structure.

3. The high-compression-resistant polyurethane insulation board according to claim 1, characterized in that, The multilayer continuous fiberglass mat reinforcement layer has a five-layer structure, and the basis weight distribution along the thickness direction is a gradient symmetrical structure of low-medium-high-medium-low.

4. The high-compression-resistant polyurethane insulation board according to claim 2, characterized in that, In the composite coupling agent, the weight ratio of silane coupling agent to titanate coupling agent is 1:0.5-2; The titanate coupling agent is used to reduce the local reactive viscosity of the polyurethane foam mixture on the surface of the continuous fiberglass mat. In conjunction with the silane coupling agent, it guides the mixture through the outer low-basis-weight fiberglass mat layer and into the inner high-basis-weight fiberglass mat layer for deep wetting.

5. The high-compression-resistant polyurethane insulation board according to claim 1, characterized in that, By weight, component B comprises: 40-80 parts of polyether polyol; 20-60 parts of polyester polyol; Foam stabilizer 1.0–3.0 parts; Catalyst 0.5–2.0 parts; 10-25 parts of foaming agent; 0.5–2.0 parts of the composite coupling agent; 0.5 to 1.5 parts of high molecular weight polyester polyol.

6. The high-compression-resistant polyurethane insulation board according to claim 5, characterized in that, The high molecular weight polyester polyol has lower reactivity than the polyether polyol and the polyester polyol, so as to delay the local curing rate of the system in the early stage of foaming and provide a time window for the wetting gradient to enhance the structure.

7. A continuous preparation method for a high-compression-strength polyurethane insulation board as described in any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Multi-layer fiberglass mats are simultaneously unrolled and laid to form a gradient alternating layered structure with a preset weight. Step S2: Mix component A and component B and apply them evenly to the surface of the multilayer fiberglass mat. Use gravity and the fluidity of the mixture to allow it to penetrate downwards and wet each fiberglass mat layer. Step S3: The material is fed into a dual-track laminator and foamed, cured, and matured at 25-45°C to form an integrated composite board. Step S4: Cut to length to obtain the finished product.

8. The continuous preparation method of high-compression-resistant polyurethane insulation board according to claim 7, characterized in that, Prior to the coating in step S2, a preheating step is included; the preheating temperature is matched with the activation temperature of the titanate coupling agent in component B to utilize the thermocapillary effect to accelerate the vertical penetration of the foamed mixture in the low-high-low gradient structure.

9. The continuous preparation method of high-compression-resistant polyurethane insulation board according to claim 7, characterized in that, In step S3, the double-track laminator is equipped with a temperature gradient along the direction of travel. The temperature gradient is specifically set as follows: the temperature of the front entry zone is set at 25-30°C to keep the mixture in a low viscosity state so as to fully wet the high basis weight glass fiber mat layer in the center; the temperature of the rear curing zone is set at 35-45°C to promote the rapid cross-linking and curing of the composite coupling agent between the fully impregnated polyurethane system and the glass fiber interface.

10. The application of the high-compression-strength polyurethane insulation board according to any one of claims 1-6 in the insulation material of cold storage floors or heavy-duty flooring buildings.

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