Aluminum-plastic composite panel with fireproof structure and preparation method of aluminum-plastic composite panel

Abstract

The invention belongs to the technical field of building fireproof materials, and discloses an aluminum-plastic composite panel with a fireproof structure and a preparation method thereof.The composite panel comprises an aluminum plate layer, a microstructure guiding type fireproof layer, a flame-retardant core layer and a back protection layer, the fireproof layer with a multistage micropore or honeycomb structure is arranged between the aluminum plate layer and the flame-retardant core layer, and the fireproof layer with the multistage micropore or honeycomb structure is arranged between the aluminum plate layer and the flame-retardant core layer. Expandable flame-retardant particles packaged in a partition mode are introduced into the structure and used for expanding at high temperature to block a flame channel, and therefore the penetration path of heat and flame is delayed. And by adopting a glue-free physical crosslinking technology, the environment-friendly lamination between the aluminum layer and the core layer is realized through the synergistic effect of aluminum plate electrostatic activation, surface plasma treatment and a silane coupling agent. The prepared composite board is suitable for the field of fire-fighting components of building fire partition walls, cable well plugging and fire protection boards with high requirements for flame retardance, heat insulation and structural durability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building fireproof materials, and particularly relates to an aluminum-plastic composite board with a fireproof structure and a preparation method thereof. BACKGROUND

[0002] The aluminum-plastic composite board is a multi-layer functional board composed of a metal aluminum layer and a polymer core layer through lamination. In recent years, it has been widely concerned and applied in the field of building fireproofing. The aluminum-plastic composite board with flame-retardant performance is suitable for fire-related components such as fire-resistant walls, cable well sealing plates, elevator shaft protective plates, ventilation duct cladding layers and equipment thermal insulation closed systems. Through reasonable structural design and integration of flame-retardant function, such materials not only can delay the spread of fire and heat penetration when a fire occurs, but also can improve the fire resistance limit and thermal stability of the overall component, meeting the use requirements of high-rise buildings, public places and industrial facilities in terms of fireproofing, safety evacuation and functional zoning. Traditional aluminum-plastic boards usually use thermoplastic resins such as polyethylene and polypropylene as core materials, and combine them with aluminum plates through hot melt adhesive or high molecular adhesive layer. Although such structure has good mechanical properties and processability, the core material is easy to melt and burn under high temperature or flame, and even drops, which has a high risk of fire.

[0003] In order to improve its flame-retardant performance, the industry generally adds aluminum hydroxide, magnesium hydroxide, intumescent flame retardant or halogen-free flame retardant system to the core material, and improves it through optimization of material ratio or structural design. However, the existing technology mainly focuses on the modification of the core material, and the overall structure is still mainly in the form of "sandwich type straight line heat conduction path", which still has obvious deficiencies in the control of fire spread path, the stability of fireproof layer interface adhesion and the preparation of non-adhesive environmentally friendly materials. SUMMARY

[0004] In order to solve the deficiencies mentioned in the background art, the purpose of the present application is to provide an aluminum-plastic composite board with a fireproof structure and a preparation method thereof. By constructing a microstructure guided fireproof layer, partitioning and encapsulating flame-retardant particles, a non-adhesive physical cross-linking interface and an environmentally friendly preparation process, the aluminum-plastic composite board thus prepared has excellent flame retardancy, interface stability and durability, and is suitable for fire-related fields such as fire-resistant walls, fireproof plugging and high-safety requirements of building interior and exterior walls.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] An aluminum-plastic composite board with a fireproof structure, the aluminum-plastic composite board comprising, from the outside to the inside, an aluminum plate layer, a microstructure guided fireproof layer, a flame-retardant core layer and a back protective layer, wherein:

[0007] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 30-45 parts of polyolefin matrix resin, 20-35 parts of expanded ammonium polyphosphate, 10-25 parts of aluminum hydroxide, and 1-5 parts of siloxane modifier.

[0008] The surface of the microstructure-guided fireproof layer has a regularly distributed multi-level micropore or honeycomb mesh structure with a pore diameter of 0.5~3.0 mm and a pore depth of 0.3~2.0 mm; its interior is provided with partitioned encapsulated expandable flame-retardant microparticles, and the aluminum plate layer and the fireproof layer are laminated together by physical cross-linking.

[0009] More preferably, the honeycomb structure of the microstructure-guided fireproof layer is a non-through closed-cell structure, and the honeycomb structure is arranged in a staggered or bent manner in the direction of the plate surface.

[0010] More preferably, the partitioned encapsulated expandable flame-retardant microparticles are selected from one or two of the following: encapsulated expandable graphite microparticles and ammonium phosphate flame-retardant microcapsules.

[0011] The coated expanded graphite microparticles are structural flame-retardant particles obtained by modifying expanded graphite with a silane coupling agent and coating its surface with polyphosphate ester or polysiloxane to form a shell. The particle size is 80~200 μm and the expansion ratio is not less than 150.

[0012] The ammonium phosphate flame-retardant microcapsules are heat-stable microcapsule particles formed by encapsulating polyurea or polymethyl methacrylate with ammonium polyphosphate as the core material through in-situ polymerization, with a particle size of 50~150 μm.

[0013] More preferably, the flame-retardant core layer comprises the following raw materials in parts by weight: 40-60 parts of polyethylene resin, 30-50 parts of magnesium hydroxide, 10-20 parts of talc, and 1-3 parts of anti-dripping agent;

[0014] The anti-dripping agent is micronized polytetrafluoroethylene or PTFE masterbatch with polyethylene as a carrier.

[0015] More preferably, the siloxane modifier is a copolymeric organosilicon solution prepared by mixing γ-glycidoxypropyltrimethoxysilane and aminopropyltriethoxysilane in a 1:1 molar ratio and then carrying out a hydrolysis-condensation reaction in deionized water at 60°C.

[0016] More preferably, the interface between the aluminum plate layer and the microstructure-guided fireproof layer is formed by corona treatment of the aluminum plate layer surface and coating the treated aluminum plate layer surface with a silane coupling agent, wherein the surface tension of the aluminum plate layer is not less than 45 mN / m.

[0017] A method for preparing an aluminum-plastic composite panel with a fire-resistant structure includes the following steps:

[0018] S1. Mix polyolefin resin, intumescent flame retardant, inorganic filler and siloxane modifier, melt extrude into sheet in extrusion equipment, and press to form a microstructure-guided fireproof layer;

[0019] S2. Perform corona treatment on the surface of the aluminum plate layer and surface activation treatment on the surface of the microstructure-guided fireproof layer;

[0020] S3. Stack the aluminum plate layer, fireproof layer, flame-retardant core layer and back protective layer in sequence, perform physical cross-linking lamination under hot pressing conditions, cool and form to obtain the finished aluminum-plastic composite panel.

[0021] More preferably, in step S2, the surface treatment of the aluminum plate layer is corona treatment, with a treatment power of 400~600W and a treatment time of 30~60 s.

[0022] More preferably, the surface activation treatment of the microstructure-guided fireproof layer surface in step S2 is low-temperature plasma treatment, with a treatment power of 200~600 W and a treatment time of 30~120 s.

[0023] More preferably, the encapsulation method of the expandable flame-retardant microparticles in the microstructure-guided fireproof layer is as follows: multiple independent pressure holes are formed on the surface of the fireproof layer sheet by molding, the encapsulated expandable graphite microcapsules are filled into each pressure hole by a quantitative pressing device, and the pressure holes are sealed by heating and pressing to form a partitioned encapsulation structure.

[0024] The beneficial effects of this invention are:

[0025] This invention employs a microstructure-guided fireproof layer with a multi-level microporous or non-penetrating honeycomb structure between an aluminum plate layer and a flame-retardant core layer. Within this fireproof layer, expandable flame-retardant microparticles are encapsulated in partitions, forcing flames and heat to spread along tortuous and staggered paths, effectively extending heat penetration time and reducing the linear spread rate of the flame. This fireproofing method, achieved through "structural path control," significantly improves overall fire resistance safety while ensuring mechanical and processing performance. Furthermore, the encapsulated expandable graphite microparticles or ammonium phosphate flame-retardant microcapsules undergo volume expansion or charring upon heating, synergizing with the microporous structure in the fireproof layer to further block thermal channels, forming a stable heat insulation and flame-retardant barrier, effectively suppressing the risk of molten dripping and secondary combustion. Furthermore, this invention achieves a stable physical cross-linking bond between the aluminum plate layer and the fireproof layer without using traditional hot melt adhesives or solvent-based adhesives through corona treatment, surface activation, and the action of silane coupling agents. This avoids the release of volatile organic compounds, improves the environmental friendliness and aging resistance of the product, and enhances the interfacial bonding strength and long-term reliability. Attached Figure Description

[0026] The invention will now be further described with reference to the accompanying drawings.

[0027] Figure 1 This is a comparison chart of the combustion oxygen index of samples from Examples 1-3 and Comparative Examples 1-2;

[0028] Figure 2 This is a comparison chart of the 180° peel strength of samples from Examples 1-3 and Comparative Examples 1-2;

[0029] Figure 3 The graph shows a comparison of the peel strength and peel strength retention rate of the samples from Examples 1-3 and Comparative Examples 1-2 after 10 thermal aging cycles. Detailed Implementation

[0030] 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] An aluminum-plastic composite panel with a fire-resistant structure, the aluminum-plastic composite panel comprising, from the outside to the inside, an aluminum plate layer, a microstructure-guided fire-resistant layer, a flame-retardant core layer, and a back protective layer, wherein:

[0033] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 30 parts of polyolefin matrix resin, 20 parts of expanded ammonium polyphosphate, 10 parts of aluminum hydroxide, and 1 part of siloxane modifier.

[0034] The flame-retardant core layer comprises the following raw materials in parts by weight: 40 parts polyethylene resin, 30 parts magnesium hydroxide, 10 parts talc, and 1 part anti-dripping agent.

[0035] The specific steps for preparing the aluminum-plastic composite panel are as follows:

[0036] S1. Take 30 g of polyolefin matrix resin, 20 g of expanded ammonium polyphosphate, 10 g of aluminum hydroxide and 2 g of siloxane modifier, add them to a high-speed mixer at room temperature, and mix at 600 rpm for 3 min to obtain a fireproof layer premix. Feed the mixture into a twin-screw extruder (L / D ratio of 40), set the temperature range to 160℃ / 170℃ / 175℃ / 170℃, and the screw speed to 60 rpm. After melt blending and extrusion, and molding, a fireproof layer sheet with a thickness of about 0.8 mm is obtained. Then, it is molded at 100℃ to form a non-penetrating honeycomb structure (pore diameter 0.5 mm, pore depth 0.3 mm, staggered arrangement). Subsequently, pre-made coated expanded graphite microcapsules (particle size 80 μm, expansion ratio not less than 150) are filled into the honeycomb pores using a quantitative pressing method, and then heat-sealed at 90℃ and 0.2 MPa for 1 min.

[0037] S2. The plate layer uses an anodized aluminum plate with a thickness of 0.3 mm. The surface is treated with a corona treatment device at 400 W for 60 s to increase the surface tension to 46 mN / m. Then, a 3 wt% γ-glycidyl ether propoxytrimethoxysilane ethanol solution is sprayed on and allowed to dry at room temperature for 10 min. The surface of the microstructure-guided fireproof layer is activated by a low-temperature plasma treatment device with a treatment power of 200 W and a treatment time of 30 s.

[0038] S3. The treated aluminum plate layer, the fireproof layer sheet obtained in step S1, the flame-retardant core layer sheet (made by double-roll pressing of 40 g polyethylene resin, 30 g magnesium hydroxide, 10 g talc powder and 1 g micronized polytetrafluoroethylene at 135℃, with a thickness of 1.0 mm) and the polyester film back protective layer with a thickness of 0.05 mm are sequentially stacked and sent into a hot pressing equipment. They are hot-pressed at 160℃ and 0.5 MPa for 10 minutes. After cooling and demolding, they are cut into aluminum-plastic composite panel samples of 300 mm × 300 mm × 2 mm.

[0039] Example 2

[0040] An aluminum-plastic composite panel with a fire-resistant structure, the aluminum-plastic composite panel comprising, from the outside to the inside, an aluminum plate layer, a microstructure-guided fire-resistant layer, a flame-retardant core layer, and a back protective layer, wherein:

[0041] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 45 parts of polyolefin matrix resin, 35 parts of expanded ammonium polyphosphate, 25 parts of aluminum hydroxide, and 5 parts of siloxane modifier.

[0042] The flame-retardant core layer comprises the following raw materials in parts by weight: 60 parts polyethylene resin, 50 parts magnesium hydroxide, 20 parts talc, and 3 parts anti-dripping agent.

[0043] The specific steps for preparing the aluminum-plastic composite panel are as follows:

[0044] S1. Take 45 g of polyolefin matrix resin, 35 g of expanded ammonium polyphosphate, 25 g of aluminum hydroxide, and 5 g of siloxane modifier. Add them to a high-speed mixer at room temperature and mix for 3 minutes to obtain a uniform premix. Feed the mixture into a twin-screw extruder and melt-extrude it according to the method in Example 1 to produce a fireproof sheet of approximately 0.8 mm. Then press it at 100°C to form a non-through closed-cell honeycomb structure with a single pore diameter of 3.0 mm and a pore depth of 2.0 mm. The structure is arranged in a bent pattern in the plate direction. Using a quantitative pressing method, pre-made coated expanded graphite microcapsules (particle size of 200 μm, shell of polyphosphate, expansion ratio of not less than 150) are filled into the formed honeycomb pores. Then heat-seal it at 90°C and 0.2 MPa for 1 min to complete the partitioned encapsulation and obtain a microstructure-guided fireproof layer.

[0045] S2. Anodized aluminum plates with a thickness of 0.3 mm were selected as the aluminum plate layer. A corona treatment device was used to continuously treat the aluminum plate at 400 W for 60 s, increasing its surface tension to approximately 46 mN / m. Subsequently, a 3 wt% γ-glycidyl ether propoxytrimethoxysilane ethanol solution was sprayed onto the aluminum plate surface, and the plate was allowed to dry at room temperature for 10 minutes. The microstructure-guided fireproof layer was treated using a low-temperature plasma device with a treatment power of 200 W and a treatment time of 30 s.

[0046] S3. Mix 60 g of polyethylene resin, 50 g of magnesium hydroxide, 20 g of talc powder, and 3 g of micronized polytetrafluoroethylene evenly, and press them into a core layer sheet with a thickness of 1.0 mm in a two-roll press at 135℃ for later use. Stack and assemble the treated aluminum plate layer, fireproof layer sheet, core layer sheet, and 0.05 mm polyester film backing sheet in sequence, and send them into a hot press. Hot press at 160℃ and 0.5 MPa for 10 minutes. After cooling, demold and cut to obtain an aluminum-plastic composite panel sample of 300 mm × 300 mm × 2 mm.

[0047] Example 3

[0048] An aluminum-plastic composite panel with a fire-resistant structure, the aluminum-plastic composite panel comprising, from the outside to the inside, an aluminum plate layer, a microstructure-guided fire-resistant layer, a flame-retardant core layer, and a back protective layer, wherein:

[0049] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 37.5 parts of polyolefin matrix resin, 27.5 parts of expanded ammonium polyphosphate, 17.5 parts of aluminum hydroxide, and 3 parts of siloxane modifier.

[0050] The flame-retardant core layer comprises the following raw materials in parts by weight: 50 parts polyethylene resin, 40 parts magnesium hydroxide, 15 parts talc, and 2 parts anti-dripping agent.

[0051] The specific steps for preparing the aluminum-plastic composite panel are as follows:

[0052] S1. Take 37.5 g of polyolefin matrix resin, 27.5 g of expanded ammonium polyphosphate, 17.5 g of aluminum hydroxide, and 3 g of siloxane modifier, add them to a high-speed mixer at room temperature, and mix at 600 rpm for 3 minutes to obtain a homogeneous fireproof layer mixture. Prepare a fireproof layer sheet using the mixture according to the method in Example 1. After cooling, the fireproof layer sheet is molded in a 100°C hot mold to form a non-penetrating honeycomb structure with a pore size of 1.75 mm, a pore depth of 1.15 mm, and a staggered arrangement of pores. Encapsulated expanded graphite microcapsules with a particle size of 140 μm, a polyphosphate shell, and an expansion ratio of not less than 150 are filled into the pores using a quantitative pressing method. After pressing, heat-seal at 90°C and 0.2 MPa for 1 minute to construct a structurally stable, partitioned encapsulated fireproof layer.

[0053] S2. Anodized aluminum sheet with a thickness of 0.3 mm was selected as the aluminum plate layer. Its surface was treated with a 400 W corona treatment device for 60 s to achieve a surface tension of 45~46 mN / m. Subsequently, a 3 wt% γ-glycidyl ether propoxytrimethoxysilane ethanol solution was uniformly sprayed onto its surface, and it was allowed to dry at room temperature for 10 min. The surface of the microstructure-guided fireproof layer sheet was activated by low-temperature plasma treatment with a power of 200 W for 30 s.

[0054] S3. Take 50 g of polyethylene resin, 40 g of magnesium hydroxide, 15 g of talc powder, and 2 g of micronized polytetrafluoroethylene. Mix the four components and press them into a core layer sheet with a thickness of about 1.0 mm using a two-roll press at 135°C. Then, sequentially stack and assemble the treated aluminum plate layer, fireproof layer sheet, core layer sheet, and a 0.05 mm thick PET film back protective layer. Place the stack in a hot press and hot press at 160°C and 0.5 MPa for 10 minutes. After cooling and demolding, cut the sample into 300 mm × 300 mm × 2 mm aluminum-plastic composite panels.

[0055] Comparative Example 1

[0056] An aluminum-plastic composite panel with a fire-resistant structure, the aluminum-plastic composite panel comprising, from the outside to the inside, an aluminum plate layer, a microstructure-guided fire-resistant layer, a flame-retardant core layer, and a back protective layer, wherein:

[0057] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 37.5 parts of polyolefin matrix resin, 27.5 parts of expanded ammonium polyphosphate, 17.5 parts of aluminum hydroxide, and 3 parts of siloxane modifier.

[0058] The flame-retardant core layer comprises the following raw materials in parts by weight: 50 parts polyethylene resin, 40 parts magnesium hydroxide, 15 parts talc, and 2 parts anti-dripping agent.

[0059] The preparation of the aluminum-plastic composite panel is the same as in Example 3, except that the honeycomb structure pressing and flame-retardant microparticle encapsulation treatment is not performed in step S1.

[0060] Comparative Example 2

[0061] An aluminum-plastic composite panel with a fire-resistant structure, the aluminum-plastic composite panel comprising, from the outside to the inside, an aluminum plate layer, a microstructure-guided fire-resistant layer, a flame-retardant core layer, and a back protective layer, wherein:

[0062] The microstructure-guided fireproof layer is composed of the following raw materials in parts by weight: 37.5 parts of polyolefin matrix resin, 27.5 parts of expanded ammonium polyphosphate, 17.5 parts of aluminum hydroxide, and 3 parts of siloxane modifier.

[0063] The flame-retardant core layer comprises the following raw materials in parts by weight: 50 parts polyethylene resin, 40 parts magnesium hydroxide, 15 parts talc, and 2 parts anti-dripping agent.

[0064] The aluminum-plastic composite panel is prepared in the same manner as in Example 3, except that no surface physical treatment or coupling agent spraying is performed on the aluminum plate before laminating the fireproof layer in step S3. The selected aluminum plate is an untreated anodized aluminum plate, and the fireproof layer sheet is not subjected to plasma treatment and is directly used in the lamination process.

[0065] Performance testing

[0066] 1. Flame retardant performance test

[0067] Oxygen Index Test: The sample is cut into strips of 130 mm × 6.5 mm and placed in an oxygen-nitrogen mixed gas stream. By adjusting the oxygen volume fraction, the lowest oxygen concentration (unit: %) required for the material to maintain combustion for 30 seconds or a combustion distance of more than 50 mm under the action of a flame is recorded, which is the oxygen index.

[0068] Vertical burning test: Conducted according to GB / T 2408-2008, with a sample size of 125 mm × 13 mm, suspended vertically on a special bracket. Ignite for 10 seconds, observe the self-extinguishing time (t1) after extinguishing, and the time to extinguish again after re-ignition (t2) to determine the flammability rating of the material.

[0069] The results are shown in Table 1 below.

[0070] Table 1 Flame retardant performance results

[0071] Sample Oxygen index (%) Self-extinguishing time t1 (s) Self-extinguishing time t2 (s) Combustion grade Example 1 32.5 5.8 6.4 1 Example 2 36.0 2.7 3.2 0 Example 3 34.2 3.6 4.1 0 Comparative Example 1 27.8 8.9 9.6 2 Comparative Example 2 29.5 6.7 7.1 1

[0072] As shown in Table 1, the fireproof structure constructed in this invention has a significant effect on improving the overall flame retardant performance of the material. The oxygen indices of Examples 2 and 3 reached 36.0% and 34.2%, respectively, and the vertical combustion rating reached level 0, indicating that the material can quickly self-extinguish under flame and effectively suppress continuous combustion. This is mainly attributed to the blocking and deflection effect of the multi-level microporous or honeycomb structure in the microstructure-guided fireproof layer on the heat and flame spread path. Simultaneously, the partitioned, expandable flame-retardant microparticles expand upon heating, forming a dense char layer, creating a secondary barrier against flame and heat. In contrast, Comparative Example 1, lacking a partitioned flame-retardant structure, allowed the flame to spread rapidly along a relatively straight path, resulting in a significantly lower oxygen index, prolonged self-extinguishing time, and a combustion rating of only level 2. Although Comparative Example 2 retained the fireproof layer structure, insufficient interface treatment reduced the interlayer bonding stability, affecting the synergistic effect of the flame-retardant system; its flame-retardant performance was between that of Examples 2 and Comparative Example 1.

[0073] 2. 180° peel strength test

[0074] The interfacial bond strength between the aluminum plate layer and the fireproof layer was tested according to GB / T 2790-1995 standard. Aluminum-plastic composite panel samples were cut into strips 25 mm wide and 200 mm long. A 50 mm free end was peeled off from one end of the sample along the interlayer structure. The strips were clamped in the upper and lower fixtures of a tensile testing machine. The peeling angle was set to 180°, and the peeling speed was 300 mm / min. The average peeling force during the stable peeling stage was recorded. Each sample was tested three times, and the average value was taken. The unit is N / 25 mm. A higher value indicates a stronger interlayer bond. The results are shown in Table 2 below.

[0075] Table 2. Results of 180° peel strength test for different samples

[0076] Sample Average peel strength (N / 25 mm) Interface state Example 1 62.5 No delamination, interface compact Example 2 75.8 Interface bonding tight, complete Example 3 70.2 Interface continuous, good adhesion Comparative Example 1 48.6 Interface complete but bonding weak Comparative Example 2 31.4 Delamination obvious, interface damaged

[0077] As shown in Table 2, the average peel strength of Examples 1-3 was significantly higher than that of the comparative examples, indicating excellent interfacial bonding. This demonstrates that the adhesive-free physical cross-linking interface construction method adopted in this invention effectively improves the bonding force between the aluminum plate layer and the fireproof layer. Among them, Example 2, due to the use of the maximum amount of siloxane modifier, combined with corona treatment and coupling agent coating, achieved the tightest interfacial bonding, with a peel strength as high as 75.8 N / 25 mm. No warping or delamination occurred during the peeling process, indicating that the composite board structure is stable and reliable. Although Comparative Example 1 retained the structural design, the lack of encapsulation microstructures slightly reduced the interfacial stability. Comparative Example 2, by eliminating corona treatment and coupling treatment, resulted in interfacial failure and severe delamination, with the peel strength dropping to 31.4 N / 25 mm, significantly lower than the other samples.

[0078] 3. Temperature test of the unexposed side

[0079] The temperature response of the unexposed side of an aluminum-plastic composite panel under open flame was simultaneously tested using thermocouples and a thermal imager. Samples were cut into 100 mm × 100 mm specimens and placed on a vertical frame. A propane torch (flame temperature approximately 1000℃) was used to continuously apply heat to the central area of ​​the unexposed side of the sample for 30 seconds. Simultaneously, a thermocouple sensor was attached to the center of the unexposed side of the sample, and the temperature change was recorded. An infrared thermal imager was used to record the heat distribution on the unexposed side every 5 seconds. The highest temperature on the unexposed side after 30 seconds of flame application was taken as the test index. Each sample was tested three times, and the average value was taken. The results are shown in Table 3 below.

[0080] Table 3 Temperature results of the unexposed side

[0081] Sample Maximum temperature on backfire side (°C) Heat distribution characteristics Example 1 172 Local temperature rise in central area, slow diffusion Example 2 158 Clear heat spot control, conduction path offset Example 3 165 Heat diffusion blocked, slow temperature rise at boundary Comparative Example 1 212 Rapid temperature rise in center, severe diffusion Comparative Example 2 195 Fast temperature rise, local heat spot drift

[0082] As shown in Table 3, the highest temperature on the unexposed surface of Examples 1-3 was significantly lower than that of the comparative example, indicating that the microstructure-guided fireproof layer and partitioned encapsulated flame-retardant microparticle system constructed in this invention have a significant inhibitory effect on heat conduction. In particular, Example 2 had the lowest temperature on the unexposed surface, only 158°C, and exhibited clear hot spot control and a shift in the heat conduction path. This indicates that the non-penetrating honeycomb structure and the expanded microparticle encapsulation work synergistically to form a directional char layer barrier under flame impact, effectively delaying heat penetration to the unexposed surface. In contrast, Comparative Example 1 did not have an encapsulation structure, resulting in a significant straight flame penetration path, severe heat diffusion, and an unexposed temperature as high as 212°C. Comparative Example 2, due to the lack of surface treatment, suffered from poor interface adhesion, discontinuous char layer formation, and reduced heat shielding effect, yet the temperature still reached 195°C.

[0083] 4. Peel performance test after thermal aging cycle

[0084] According to GB / T 7141-1999 standard, thermal aging cycle tests were conducted on aluminum-plastic composite panel samples. The samples were placed in a temperature-cooling alternating chamber, with the temperature range set from -20℃ to 70℃. Each cycle consisted of: holding at 70℃ for 2 hours, restoring to room temperature for 30 minutes, holding at -20℃ for 2 hours, and then restoring. A total of 10 complete cycles were performed. After the cycles, the samples were subjected to a 180° peel strength test according to GB / T2790-1995 standard, and the change in peel force was recorded. The results are shown in Table 4 below.

[0085] Table 4 Peel strength after thermal aging cycles

[0086] Sample Peel strength (N / 25 mm) Peel strength retention rate (%) Example 1 58.2 93.1 Example 2 72.6 95.8 Example 3 66.9 95.3 Comparative Example 1 41.0 84.4 Comparative Example 2 22.7 72.3

[0087] The results are shown in Table 4. Examples 1-3 maintained high peel strength and good retention rate after 10 thermal cycling cycles, indicating that the physical cross-linking interface between the aluminum plate and the fireproof layer constructed by this invention has excellent thermal aging durability. In particular, Example 2, after high and low temperature cycling, still achieved a peel strength retention rate of 95.8%, indicating that its interface bonding structure was stable and no thermal fatigue damage or bonding failure occurred. This is due to the synergistic effect of the corona treatment combined with the silane coupling agent to form a stable cross-linking interface and the embedded structure in the fireproof layer. In contrast, Comparative Examples 1 and 2, lacking encapsulation structures or interface treatment, were prone to delamination or cracking of the bonding interface after thermal cycling due to repeated thermal expansion and contraction, resulting in a significant decrease in peel strength, with retention rates of only 84.4% and 72.3%, respectively.

[0088] 5. Fire resistance limit test

[0089] According to the requirements of GB / T 9978.1-2008 "Test Method for Fire Resistance of Building Components", the fire resistance limit of aluminum-plastic composite panel samples was tested using a standard fire-resistant furnace. The prepared composite panel samples were installed in the test frame of the fire-resistant furnace and heated under specified loading conditions. The time for the samples to reach the loss of integrity (E) and the loss of insulation (I) under flame exposure were recorded. Each group of samples was tested three times, and the average value was taken as the final fire resistance limit time (unit: min). The results are shown in Table 5 below.

[0090] Table 5 Fire resistance limit test results

[0091] Sample Integrity retention time (min) Thermal insulation retention time (min) Comprehensive fire resistance limit (min) Example 1 87 75 75 Example 2 112 98 98 Example 3 102 90 90 Comparative Example 1 55 38 38 Comparative Example 2 61 45 45

[0092] As shown in Table 5, Examples 1-3 all exhibited significantly better fire resistance performance than the comparative examples in the fire resistance limit test. Example 2 achieved an integrity retention time of 112 min, a thermal insulation retention time of 98 min, and a comprehensive fire resistance limit close to 100 min, indicating that it could maintain structural integrity and effectively block heat transfer for a long time under the standard fire curve. This is mainly due to the delaying effect of the multi-level porous structure in the microstructure-guided fireproof layer on the flame and heat flow path, and the formation of a dense char layer by the partitioned encapsulated expandable flame-retardant microparticles at high temperatures, which provides a continuous flame barrier effect. In contrast, Comparative Examples 1 and 2, lacking the above-mentioned structural synergy or with insufficient interface stability, experienced earlier thermal insulation failure and structural damage under the action of flame, resulting in significantly lower fire resistance limits.

[0093] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0094] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. An aluminum-plastic composite sheet having a fireproof structure, characterized by, The aluminum-plastic composite board comprises, from outside to inside, an aluminum plate layer, a microstructure-guided fireproof layer, a fire-retardant core layer and a back protective layer. The microstructure-guided fireproof layer is composed of the following raw materials by weight: polyolefin matrix resin 30-45 parts, expanded ammonium polyphosphate 20-35 parts, aluminum hydroxide 10-25 parts, and siloxane modifier 1-5 parts. The microstructure-guided fireproof layer has regularly distributed multi-stage micropores or honeycomb network structures on the surface, with a pore diameter of 0.5-3.0 mm and a pore depth of 0.3-2.0 mm; and an expandable fire-retardant particle partitioned and encapsulated inside, and the aluminum plate layer and the fireproof layer are combined by physical cross-linking lamination.

2. The aluminum-plastic composite sheet according to claim 1, characterized by, The honeycomb structure of the microstructure-guided fireproof layer is a non-penetrating closed-cell structure, and the honeycomb structure is arranged in a staggered or bent manner in the direction of the board surface.

3. The aluminum-plastic composite sheet according to claim 1, wherein The partitioned and encapsulated expandable fire-retardant particles are selected from one or both of coated expandable graphite particles and phosphoric amine salt fire-retardant microcapsules. The coated expandable graphite particles are structural fire-retardant particles obtained by modifying expandable graphite with a silane coupling agent, and then coating the surface of the modified expandable graphite with polyphosphate or polysiloxane to form a shell layer, with a particle size of 80-200 μm and an expansion ratio of not less than 150. The phosphoric amine salt fire-retardant microcapsules are heat-stable microcapsule particles obtained by coating polyurea or polymethyl methacrylate on polyphosphate as a core material by in-situ polymerization, with a particle size of 50-150 μm.

4. The aluminum-plastic composite sheet according to claim 1, wherein The fire-retardant core layer comprises the following raw materials by weight: polyethylene resin 40-60 parts, magnesium hydroxide 30-50 parts, talc 10-20 parts, and anti-dripping agent 1-3 parts. The anti-dripping agent is micronized polytetrafluoroethylene or PTFE masterbatch with polyethylene as a carrier.

5. The aluminum-plastic composite sheet according to claim 1, wherein The siloxane modifier is a copolymerized organosilicon solution obtained by mixing γ-glycidyl ether propyltrimethoxysilane and aminopropyltriethoxysilane at a molar ratio of 1:1, and then performing hydrolysis and condensation polymerization in deionized water at 60°C.

6. The aluminum-plastic composite sheet according to claim 1, wherein The bonding interface between the aluminum plate layer and the microstructure-guided fireproof layer is formed by the following method: performing corona treatment on the surface of the aluminum plate layer, and coating a silane coupling agent on the surface of the treated aluminum plate layer, with a surface tension of the aluminum plate layer of not less than 45 mN / m.

7. A method for producing an aluminum-plastic composite sheet having a fireproof structure, the aluminum-plastic composite sheet being as claimed in any one of claims 1 to 6, characterized by, The method comprises the following steps: S1. Mixing polyolefin resin, expanded fire-retardant agent, inorganic filler and siloxane modifier, and melt extruding into a sheet in an extrusion device to form a microstructure-guided fireproof layer; S2. Performing corona treatment on the surface of the aluminum plate layer, and surface activation treatment on the surface of the microstructure-guided fireproof layer; S3. Stacking the aluminum plate layer, the fireproof layer, the fire-retardant core layer and the back protective layer in sequence, and performing physical cross-linking lamination under heat pressing conditions to obtain an aluminum-plastic composite board product.

8. The method for preparing the aluminum-plastic composite panel according to claim 7, characterized in that, In step S2, the surface treatment method of the aluminum plate layer is corona treatment, with a treatment power of 400-600 W and a treatment time of 30-60 s.

9. The method for preparing the aluminum-plastic composite panel according to claim 7, characterized in that, The surface activation treatment mode of the microstructure-guided fireproof layer in the step S2 is low-temperature plasma treatment, the treatment power is 200-600 W, and the treatment time is 30-120 s.

10. The method for preparing the aluminum-plastic composite panel according to claim 7, characterized in that, The packaging mode of the expandable fire-retardant microparticles in the microstructure-guided fireproof layer is as follows: a plurality of independent pressing holes are formed on the surface of the fireproof layer sheet through molding, the coated graphite microcapsules are filled into each pressing hole through a quantitative pressing device, and the pressing holes are sealed through a heating and sealing mode to form a partitioned packaging structure.

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