Phenolic and polyurethane in-situ composite thermal insulation sandwich panels, their preparation methods and applications

Abstract

This application discloses a phenolic and polyurethane in-situ composite insulation sandwich panel, its preparation method, and its application, relating to the field of insulation materials. The sandwich panel includes a phenolic foam core material, an epoxy fully enclosed coating layer covering all six sides of the phenolic foam core material, a polyurethane foam fusion layer covering the outer surface of the epoxy fully enclosed coating layer, and a panel composited on the outer surface of the polyurethane foam fusion layer. The epoxy fully enclosed coating layer consists of a penetrating sealing primer layer and a dense isolating topcoat layer. This application achieves a pinhole-free and leak-proof sealing effect for the phenolic core material through a double-layer epoxy resin fully enclosed coating layer, effectively isolating air and moisture, and improving the problems of acid reflux, looseness, easy powdering, high water absorption, and poor dimensional stability of traditional phenolic boards. It forms a dual effect of chemical cross-linking and physical anchoring, improving structural stability without affecting the fire resistance of the phenolic core material.

Description

Technical Field

[0001] This application relates to the technical field of building fireproof insulation and cold chain insulation materials, and in particular to a phenolic and polyurethane in-situ composite insulation sandwich panel, its preparation method and application. Background Technology

[0002] Phenolic foam insulation materials possess advantages such as Class A non-combustibility, low smoke, high temperature resistance, and low thermal conductivity, making them widely used in building exterior wall insulation, cold storage enclosures, cleanrooms, and other fields. However, phenolic foam materials themselves have the following inherent defects:

[0003] 1. Loose surface and easy to shed powder: Phenolic foam has a high open cell ratio and low surface strength, which makes it easy to shed dust during handling and processing, affecting the use environment and interfacial adhesion performance;

[0004] 2. High water absorption and poor dimensional stability: The open structure makes the material easy to absorb moisture and become damp. After absorbing water, the thermal conductivity increases, the thermal insulation performance decreases, and the dimensions change significantly with temperature changes.

[0005] 3. Precipitation of acidic residues: Acidic catalysts and free phenols remaining during the synthesis of phenolic resin slowly precipitate out during service, which not only corrode the metal panel, but also have poor compatibility with the subsequent polyurethane foam layer, leading to interface delamination, debonding, and aging failure.

[0006] 4. Difficulty in interface bonding: Phenolic boards have low surface energy, making it difficult for conventional interface treatment agents to form a strong chemical bond. The peel strength between the board and the polyurethane foam layer is usually less than 0.1 MPa, which cannot meet the requirements for long-term use.

[0007] To solve the above problems, existing technologies mainly adopt the following solutions:

[0008] Chinese patent CN201810123456.7 discloses a surface spraying process for phenolic boards, which uses a single layer of epoxy coating for surface sealing. Although this solution has some improvement, the spraying process is difficult to guarantee uniform coverage on all six sides, and corners are prone to missed coating. Furthermore, a single layer of coating cannot simultaneously satisfy the dual functions of penetration sealing and dense isolation.

[0009] Chinese patent CN201710789012.3 discloses a two-component interface agent for phenolic boards, which requires separate application of primer and topcoat. However, this solution involves multiple processes, resulting in low production efficiency, and it does not solve the problem of chemical bonding with the polyurethane foam layer.

[0010] Chinese patent CN202310687910.0 discloses an epoxy dip-coating method for metal parts, involving process steps such as preheating, dip-coating, rolling drying, and curing. However, this technology is designed for metal substrates. When directly applied to porous phenolic boards, problems such as excessive coating penetration, severe sagging, and board deformation caused by high-temperature curing may occur.

[0011] Therefore, developing a composite insulation board that can achieve full six-sided sealing of phenolic board, form a strong chemical bond with polyurethane foam layer, and is suitable for continuous industrial production, as well as its preparation method, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0012] In order to solve at least one of the above-mentioned technical problems and develop a thermal insulation board with good sealing effect and strong structure, this application provides a phenolic and polyurethane in-situ composite thermal insulation sandwich panel, its preparation method and application.

[0013] On the one hand, this application provides a phenolic and polyurethane in-situ composite thermal insulation sandwich panel, comprising:

[0014] Phenolic foam core material;

[0015] An epoxy fully enclosed coating layer covering all six sides of the phenolic foam core material;

[0016] A polyurethane foam fusion layer covering the outer surface of the epoxy fully enclosed film layer;

[0017] And a panel composited on the outer surface of the polyurethane foam fusion layer;

[0018] The epoxy fully enclosed coating layer consists of a penetrating sealing primer layer and a dense insulating topcoat layer.

[0019] Phenolic foam, as a core thermal insulation and fireproofing substrate, possesses two major advantages. First, it boasts excellent fire resistance, achieving an A2 fire rating (GB 8624-2012), exhibiting no open flame, low smoke, and high temperature resistance, fully meeting the fire protection requirements of building insulation, cold storage, and fireproof air ducts—a core advantage unmatched by polyurethane. Second, it exhibits outstanding thermal insulation performance, with a thermal conductivity as low as 0.024 W / m·K, similar to polyurethane, enabling highly efficient thermal insulation. However, phenolic foam has significant shortcomings in its physical properties, specifically its loose surface, tendency to shed powder, poor dimensional stability, and extremely weak interfacial adhesion to metal panels and other composite layers. It also has a high water absorption rate. These physical defects severely limit its practical applications, which is the key reason why single-material phenolic foam cannot meet the demands of high-end applications.

[0020] In contrast, polyurethane possesses superior physical properties, precisely compensating for the aforementioned shortcomings of phenolic foam: polyurethane foam materials exhibit excellent adhesion, flexibility, and density, demonstrating excellent compatibility with metal panels and epoxy coatings, forming a strong interfacial bond. Simultaneously, its dense structure helps improve the overall strength and dimensional stability of composite panels, effectively solving the problems of phenolic foam such as powdering, interfacial debonding, and dimensional deformation. However, polyurethane's core disadvantage is its insufficient fire resistance, failing to meet Class A fire protection standards. When used alone, it struggles to comply with building fire protection design codes, limiting its application in high-end fireproof insulation.

[0021] This application utilizes a process of "double-layer epoxy fully enclosed film + polyurethane in-situ foaming composite" to achieve complementary advantages and offset disadvantages of the two materials, resulting in a composite insulation sandwich panel with excellent fire resistance, high thermal insulation efficiency, and stable physical properties.

[0022] Optionally, the panel is selected from metal panels, stainless steel plates, aluminum-magnesium-manganese plates, fiberglass plates, or wood composite panels.

[0023] Optionally, the penetrating and sealing primer layer is made from the following raw materials in parts by weight: 100 parts epoxy resin, 10-15 parts reactive diluent, 45-55 parts amine curing agent, 1-3 parts silane coupling agent, and 0.3-0.8 parts defoamer.

[0024] Optionally, the dense isolation topcoat layer is made from the following raw materials in parts by weight: 100 parts epoxy resin, 5-10 parts reactive diluent, 25-35 parts cashew nut shell oil modified phenolic amine curing agent, 1-3 parts silane coupling agent, 0.2-0.5 parts defoamer, and 0.3-0.8 parts leveling agent.

[0025] Optionally, the total dry film thickness of the epoxy fully enclosed coating layer is 120-160 μm.

[0026] Optionally, the density of the phenolic foam core material is 35~45 kg / m³, and the thickness is 20~200 mm.

[0027] Secondly, this application provides a method for preparing the aforementioned sandwich panel, comprising the following steps:

[0028] S1, Surface activation treatment

[0029] Surface activation treatment is applied to phenolic foam core material;

[0030] S2, Apply primer

[0031] Apply a penetrating and sealing primer to the surface of the activated core material, control the wet film thickness to 30~40μm, and dry at 50~70℃ for 8~12min to form a penetrating and sealing primer layer.

[0032] S3, Apply topcoat

[0033] A dense isolation topcoat is applied to the surface of the penetrating and sealing primer, the wet film thickness is controlled at 120~160μm, and dried at 70~80℃ for 10~15min to form a dense isolation topcoat layer, thus obtaining an epoxy fully sealed coating layer.

[0034] S4, Closed Inspection

[0035] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0036] S5, PU / PIR foam composite

[0037] Polyurethane foam raw material is poured between the metal panel and the epoxy fully enclosed film layer, and foaming and composite are carried out at 20~28℃ and linear speed of 3~6m / min, with a foaming peak temperature ≤160℃.

[0038] S6, Curing Cut

[0039] Allow to mature at room temperature for ≥24 hours before cutting, inspecting, and packaging.

[0040] The preparation method of the present invention can be directly utilized in existing polyurethane sandwich panel continuous production lines. Only surface activation treatment and multiple roller coating and drying units need to be added at the front end. It requires little investment, is quick to modify, and has good industrialization and promotion value.

[0041] Optionally, the surface activation treatment described in S1 is selected from one of corona treatment, plasma treatment or flame treatment, and the contact angle between the core material surface and water after treatment is ≤30°.

[0042] Optionally, the pot life of the penetrating sealing primer in S2 after mixing is ≥40 min, and the pot life of the dense isolation topcoat in S3 after mixing is ≥60 min.

[0043] Thirdly, this application provides a method for repairing the aforementioned sandwich panel, wherein a dense insulating topcoat layer is applied to the cut surface of the sandwich panel.

[0044] Fourthly, this application provides the application of the aforementioned sandwich panels in the fields of building exterior wall insulation, cold chain cold storage, pharmaceutical cleanrooms, and fireproof air ducts.

[0045] The phenolic and polyurethane in-situ composite insulation sandwich panel provided by this invention combines the Class A fire resistance of phenolic foam with the excellent bonding properties of polyurethane, and can be widely used in...

[0046] Cold chain cold storage: -30℃~+30℃ cold storage enclosure structure, meeting the requirements of low water absorption rate and high airtightness;

[0047] Pharmaceutical cleanroom: Meets GMP cleanroom requirements, with no dust shedding and easy cleaning;

[0048] Building exterior wall insulation: Class A fireproof, in compliance with building fire protection design specifications;

[0049] Fireproof air ducts: High temperature resistant, non-combustible, low smoke, meeting the requirements of smoke control and exhaust systems.

[0050] In summary, the present invention has at least one of the following beneficial technical effects:

[0051] 1. This invention achieves a pinhole-free and leak-proof sealing effect for the phenolic core material through a double-layer epoxy fully enclosed coating, effectively isolating it from air and moisture, and improving the problems of loose surface, easy powdering, high water absorption, and poor dimensional stability of traditional phenolic boards; at the same time, it seals the acidic residues and free phenol in the phenolic core material, making the product surface neutral, avoiding corrosion of metal panels, and extending the product's service life;

[0052] 2. The epoxy fully enclosed coating layer and the polyurethane foam fusion layer of the present invention form a dual effect of chemical cross-linking and physical anchoring, which improves the problems of poor compatibility between phenolic board and polyurethane foam layer, interface delamination, debonding, and aging failure, and ensures the structural stability of the product for long-term use.

[0053] 3. The epoxy coating layer used in this invention has a moderate thickness and inherent fireproof, insulating and heat-insulating properties. While not affecting the Class A fireproof performance of the phenolic core material, it can also significantly improve the overall mechanical strength, environmental aging resistance and service life of the board. Detailed Implementation

[0054] The present application will be further described in detail below with reference to the embodiments.

[0055] Unless otherwise specified, all raw materials involved in the following embodiments of this application are purchased from commercially available products.

[0056] Phenolic foam core material: density 40kg / m³, thickness 100mm, size 1200mm×600mm.

[0057] E-51 epoxy resin: epoxy value 0.51, purchased from Nan Ya Plastics.

[0058] 692 reactive diluent: industrial grade, purchased from Anhui Xinyuan.

[0059] Modified alicyclic amine curing agent: amine value 300-350 mgKOH / g, purchased from Cardlä.

[0060] Cashew nut shell oil modified phenolic amine curing agent: CARDOLITE® NC-541, purchased from Cardlite.

[0061] KH-550 silane coupling agent: industrial grade, purchased from Nanjing Shuguang.

[0062] KH-560 silane coupling agent: industrial grade, purchased from Nanjing Shuguang.

[0063] Silicone defoamer: BYK-052N, purchased from BYK Chemical.

[0064] Polyether-modified silicone leveling agent: BYK-333, purchased from BYK Chemical.

[0065] Example 1

[0066] The following formula is used in this embodiment:

[0067] Penetrating sealing primer

[0068] E-51 epoxy resin: 100 parts by weight;

[0069] 692 reactive diluent: 12 parts by weight;

[0070] Modified alicyclic amine curing agent: 50 parts by weight;

[0071] KH-550 coupling agent: 2 parts by weight;

[0072] Organosilicon defoamer: 0.5 parts by weight.

[0073] Dense isolation topcoat

[0074] E-51 epoxy resin: 100 parts by weight;

[0075] 692 reactive diluent: 8 parts by weight;

[0076] Cashew nut shell oil modified phenolic amine curing agent: 30 parts by weight;

[0077] KH-560 coupling agent: 2 parts by weight;

[0078] Organosilicon defoamer: 0.3 parts by weight;

[0079] Polyether-modified silicone leveling agent: 0.5 parts by weight.

[0080] This embodiment uses the following preparation method:

[0081] S1, Surface activation treatment

[0082] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. The contact angle between the treated surface and water was 25°.

[0083] S2, Apply primer

[0084] The penetrating and sealing primer prepared in this embodiment has a working period of 45 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 35 μm and dried with hot air at 65°C for 10 minutes to form a penetrating and sealing primer layer.

[0085] S3, Apply topcoat

[0086] The dense protective topcoat prepared in this embodiment has a working period of 65 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 140 μm and dried with hot air at 75°C for 12 minutes to form a dense protective topcoat layer.

[0087] S4, Closed Inspection

[0088] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0089] S5, PU / PIR foam composite

[0090] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0091] Polyurethane foam raw material ratio: 150 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.10.

[0092] Foaming process parameters: pouring temperature 25℃, linear velocity 4m / min, peak foaming temperature 158℃;

[0093] S6, Curing Cut

[0094] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0095] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 1.

[0096] Table 1 Performance parameters of the sandwich panel prepared in Example 1

[0097] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.32 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 6.0 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0098] Example 2

[0099] The following formula is used in this embodiment:

[0100] Penetrating sealing primer

[0101] E-51 epoxy resin: 100 parts by weight;

[0102] 692 reactive diluent: 10 parts by weight;

[0103] Modified alicyclic amine curing agent: 45 parts by weight;

[0104] KH-550 coupling agent: 3 parts by weight;

[0105] Organosilicon defoamer: 0.8 parts by weight.

[0106] Dense isolation topcoat

[0107] E-51 epoxy resin: 100 parts by weight;

[0108] 692 reactive diluent: 5 parts by weight;

[0109] Cashew nut shell oil modified phenolic amine curing agent: 25 parts by weight;

[0110] KH-560 coupling agent: 3 parts by weight;

[0111] Organosilicon defoamer: 0.5 parts by weight;

[0112] Polyether-modified silicone leveling agent: 0.8 parts by weight.

[0113] This embodiment uses the following preparation method:

[0114] S1, Surface activation treatment

[0115] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. The contact angle between the treated surface and water was 25°.

[0116] S2, Apply primer

[0117] The penetrating and sealing primer prepared in this embodiment has a working period of 45 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 35 μm and dried with hot air at 60°C for 12 minutes to form a penetrating and sealing primer layer.

[0118] S3, Apply topcoat

[0119] The dense protective topcoat prepared in this embodiment has a working period of 65 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 140 μm and dried with hot air at 70°C for 15 minutes to form a dense protective topcoat layer.

[0120] S4, Closed Inspection

[0121] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0122] S5, PU / PIR foam composite

[0123] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0124] Polyurethane foam raw material ratio: 150 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.10.

[0125] Foaming process parameters: pouring temperature 25℃, linear velocity 3m / min, peak foaming temperature 158℃;

[0126] S6, Curing Cut

[0127] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0128] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 2.

[0129] Table 2 Performance parameters of the sandwich panel prepared in Example 2

[0130] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.25 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 5.8 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0131] Example 3

[0132] The following formula is used in this embodiment:

[0133] Penetrating sealing primer

[0134] E-51 epoxy resin: 100 parts by weight;

[0135] 692 reactive diluent: 15 parts by weight;

[0136] Modified alicyclic amine curing agent: 55 parts by weight;

[0137] KH-550 coupling agent: 1 part by weight;

[0138] Organosilicon defoamer: 0.3 parts by weight.

[0139] Dense isolation topcoat

[0140] E-51 epoxy resin: 100 parts by weight;

[0141] 692 reactive diluent: 10 parts by weight;

[0142] Cashew nut shell oil modified phenolic amine curing agent: 35 parts by weight;

[0143] KH-560 coupling agent: 1 part by weight;

[0144] Organosilicon defoamer: 0.2 parts by weight;

[0145] Polyether-modified silicone leveling agent: 0.3 parts by weight.

[0146] This embodiment uses the following preparation method:

[0147] S1, Surface activation treatment

[0148] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. The contact angle between the treated surface and water was 25°.

[0149] S2, Apply primer

[0150] The penetrating and sealing primer prepared in this embodiment has a working period of 45 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 35 μm and dried with hot air at 50°C for 8 minutes to form a penetrating and sealing primer layer.

[0151] S3, Apply topcoat

[0152] The dense protective topcoat prepared in this embodiment has a working period of 65 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 140 μm and dried with hot air at 80°C for 10 minutes to form a dense protective topcoat layer.

[0153] S4, Closed Inspection

[0154] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0155] S5, PU / PIR foam composite

[0156] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0157] Polyurethane foam raw material ratio: 150 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.10.

[0158] Foaming process parameters: pouring temperature 25℃, linear velocity 6m / min, peak foaming temperature 158℃;

[0159] S6, Curing Cut

[0160] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0161] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 3.

[0162] Table 3 Performance parameters of the sandwich panel prepared in Example 3

[0163] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.31 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 5.5 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0164] Example 4

[0165] The following formula is used in this embodiment:

[0166] Penetrating sealing primer

[0167] E-51 epoxy resin: 100 parts by weight;

[0168] 692 reactive diluent: 11 parts by weight;

[0169] Modified alicyclic amine curing agent: 48 parts by weight;

[0170] KH-550 coupling agent: 1.5 parts by weight;

[0171] Organosilicon defoamer: 0.6 parts by weight.

[0172] Dense isolation topcoat

[0173] E-51 epoxy resin: 100 parts by weight;

[0174] 692 reactive diluent: 6 parts by weight;

[0175] Cashew nut shell oil modified phenolic amine curing agent: 28 parts by weight;

[0176] KH-560 coupling agent: 1.5 parts by weight;

[0177] Organosilicon defoamer: 0.4 parts by weight;

[0178] Polyether-modified silicone leveling agent: 0.6 parts by weight.

[0179] This embodiment uses the following preparation method:

[0180] S1, Surface activation treatment

[0181] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. After treatment, the surface contact angle with water was 28°.

[0182] S2, Apply primer

[0183] The penetrating and sealing primer prepared in this embodiment has a working period of 42 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 32 μm and dried with hot air at 62°C for 11 minutes to form a penetrating and sealing primer layer.

[0184] S3, Apply topcoat

[0185] The dense protective topcoat prepared in this embodiment has a working period of 62 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 130 μm and dried with hot air at 72°C for 13 minutes to form a dense protective topcoat layer.

[0186] S4, Closed Inspection

[0187] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0188] S5, PU / PIR foam composite

[0189] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0190] Polyurethane foam raw material ratio: 145 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.08.

[0191] Foaming process parameters: pouring temperature 23℃, linear velocity 3.5m / min, peak foaming temperature 155℃;

[0192] S6, Curing Cut

[0193] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0194] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 4.

[0195] Table 4 Performance parameters of the sandwich panel prepared in Example 4

[0196] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.25 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 5.8 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0197] Example 5

[0198] The following formula is used in this embodiment:

[0199] Penetrating sealing primer

[0200] E-51 epoxy resin: 100 parts by weight;

[0201] 692 reactive diluent: 14 parts by weight;

[0202] Modified alicyclic amine curing agent: 52 parts by weight;

[0203] KH-550 coupling agent: 2.5 parts by weight;

[0204] Organosilicon defoamer: 0.4 parts by weight.

[0205] Dense isolation topcoat

[0206] E-51 epoxy resin: 100 parts by weight;

[0207] 692 reactive diluent: 9 parts by weight;

[0208] Cashew nut shell oil modified phenolic amine curing agent: 32 parts by weight;

[0209] KH-560 coupling agent: 2.5 parts by weight;

[0210] Organosilicon defoamer: 0.35 parts by weight;

[0211] Polyether-modified silicone leveling agent: 0.4 parts by weight.

[0212] This embodiment uses the following preparation method:

[0213] S1, Surface activation treatment

[0214] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. After treatment, the surface contact angle with water was 26°.

[0215] S2, Apply primer

[0216] The penetrating and sealing primer prepared in this embodiment has a working period of 43 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 38 μm and dried with hot air at 68°C for 9 minutes to form a penetrating and sealing primer layer.

[0217] S3, Apply topcoat

[0218] The dense protective topcoat prepared in this embodiment has a working period of 63 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 150 μm and dried with hot air at 78°C for 11 minutes to form a dense protective topcoat layer.

[0219] S4, Closed Inspection

[0220] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0221] S5, PU / PIR foam composite

[0222] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0223] Polyurethane foam raw material ratio: 155 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.12.

[0224] Foaming process parameters: pouring temperature 26℃, linear velocity 5m / min, peak foaming temperature 157℃;

[0225] S6, Curing Cut

[0226] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0227] The performance of the sandwich panels prepared above was tested, and the test results are shown in Table 5.

[0228] Table 5 Performance parameters of the sandwich panel prepared in Example 5

[0229] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.28 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 5.6 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0230] Example 6

[0231] The following formula is used in this embodiment:

[0232] Penetrating sealing primer

[0233] E-51 epoxy resin: 100 parts by weight;

[0234] 692 reactive diluent: 13 parts by weight;

[0235] Modified alicyclic amine curing agent: 51 parts by weight;

[0236] KH-550 coupling agent: 2.2 parts by weight;

[0237] Organosilicon defoamer: 0.7 parts by weight.

[0238] Dense isolation topcoat

[0239] E-51 epoxy resin: 100 parts by weight;

[0240] 692 reactive diluent: 7 parts by weight;

[0241] Cashew nut shell oil modified phenolic amine curing agent: 33 parts by weight;

[0242] KH-560 coupling agent: 2.2 parts by weight;

[0243] Organosilicon defoamer: 0.25 parts by weight;

[0244] Polyether-modified silicone leveling agent: 0.7 parts by weight.

[0245] This embodiment uses the following preparation method:

[0246] S1, Surface activation treatment

[0247] The phenolic foam core material was treated on all six sides using a corona treatment machine with a treatment power of 1.5kW and a linear speed of 3m / min. After treatment, the surface contact angle with water was 27°.

[0248] S2, Apply primer

[0249] The penetrating and sealing primer prepared in this embodiment has a working period of 44 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 36 μm and dried with hot air at 66°C for 10.5 minutes to form a penetrating and sealing primer layer.

[0250] S3, Apply topcoat

[0251] The dense protective topcoat prepared in this embodiment has a working period of 64 minutes after mixing. It is applied using a six-sided roller coater with a wet film thickness of 145 μm and dried with hot air at 76°C for 12.5 minutes to form a dense protective topcoat layer.

[0252] S4, Closed Inspection

[0253] Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides.

[0254] S5, PU / PIR foam composite

[0255] It is fed into a double-belt continuous foaming production line, with the upper and lower panels made of 0.5mm thick galvanized steel sheets.

[0256] Polyurethane foam raw material ratio: 152 parts by weight of isocyanate (PM-200), 100 parts by weight of polyether (PS-3152), and isocyanate index 1.11.

[0257] Foaming process parameters: pouring temperature 24℃, linear velocity 4.5m / min, peak foaming temperature 156℃;

[0258] S6, Curing Cut

[0259] After being left at room temperature for 24 hours, the core is cut to the required size to obtain a phenolic-polyurethane in-situ composite insulation sandwich panel.

[0260] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 6.

[0261] Table 6 Performance parameters of the sandwich panel prepared in Example 6

[0262] Water absorption rate (vol%) GB / T 5486-2008 0.21 Peel strength (MPa) GB / T 2790-1995 0.28 Moist heat aging (80℃ / 95%RH×168h) Visual inspection No bubbling, no layering Surface pH value Moistened pH test strips 5.5 Combustion performance GB 8624-2012 A2 level Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0263] Comparative Example 1 (Uncoated with epoxy)

[0264] This comparative example uses the same phenolic core material as Example 1, without any coating treatment, and directly performs PU / PIR foaming composite.

[0265] The performance of the sandwich panels prepared above was tested, and the test results are shown in Table 7.

[0266] Table 7 Performance parameters of the sandwich panel prepared in Comparative Example 1

[0267] Water absorption rate (vol%) GB / T 5486-2008 8.5 Peel strength (MPa) GB / T 2790-1995 0.08 Moist heat aging (80℃ / 95%RH×168h) Visual inspection Severe stratification Surface pH value Moistened pH test strips 4.5 Combustion performance GB 8624-2012 conform to Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0268] Comparative Example 2 (Single-layer epoxy coating)

[0269] This comparative example uses the same phenolic core material as Example 1, with only one layer of dense isolation topcoat (wet film thickness 140μm, no primer), and is then PU / PIR foamed and laminated after drying.

[0270] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 8.

[0271] Table 8 Performance parameters of the sandwich panels prepared in Comparative Example 2

[0272] Water absorption rate (vol%) GB / T 5486-2008 2.1 Peel strength (MPa) GB / T 2790-1995 0.18 Moist heat aging (80℃ / 95%RH×168h) Visual inspection Slight bubbling Surface pH value Moistened pH test strips 6.6 Combustion performance GB 8624-2012 conform to Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0273] Comparative Example 3 (Commercially Available Interface Agent)

[0274] This comparative example uses a commercially available brand of phenolic board interface agent, applied twice according to the product instructions, and then PU / PIR foamed and laminated after drying.

[0275] The sandwich panels prepared above were subjected to performance tests, and the test results are shown in Table 9.

[0276] Table 9 Performance parameters of the sandwich panels prepared in Comparative Example 3

[0277] Water absorption rate (vol%) GB / T 5486-2008 3.8 Peel strength (MPa) GB / T 2790-1995 0.15 Moist heat aging (80℃ / 95%RH×168h) Visual inspection Local debonding Surface pH value Moistened pH test strips 6.2 Combustion performance GB 8624-2012 conform to Thermal conductivity (W / m·K) GB / T 10294-2008 0.024

[0278] Comparative Example 4 (using process parameters CN202310687910.0)

[0279] This comparative example uses the same formulation as Example 1, but is prepared according to the process parameters disclosed in CN202310687910.0: preheating: 80℃×25min; curing: 80℃×40min.

[0280] The prepared sandwich panel has the following characteristics: board deformation: warpage 3.2 mm / m; peel strength: 0.16 MPa; coating appearance: microcracks present.

[0281] In Comparative Example 1 (without epoxy coating and no effective polyurethane composite), the single phenolic core material was directly composited with the metal panel. Due to its poor physical properties, the peel strength was only 0.08 MPa, the water absorption rate was as high as 8.5 vol%, the surface was prone to powdering, and it severely delaminated after humid heat aging, making it unusable for long-term use. In Examples 1-6, the polyurethane foam layer was in situ composited with the epoxy-coated phenolic core material. The excellent adhesion of polyurethane and the epoxy coating layer formed a dual effect of chemical cross-linking and physical anchoring, which greatly improved the interfacial bonding of the composite board, which was better than that of Comparative Example 1 (0.08 MPa). At the same time, the dense structure of polyurethane assisted the epoxy coating layer, which further reduced the water absorption rate of the phenolic core material. The water absorption rate of all examples was stable at 0.21 vol%, which improved the problem of phenolic foam's easy water absorption and dimensional instability. This gave the composite board excellent physical stability, which can withstand the external forces during handling, processing and long-term service, and avoid defects such as powdering, deformation and delamination.

[0282] On the other hand, the fire-retardant advantages of phenolic foam are utilized to compensate for the shortcomings of polyurethane's fire resistance, ensuring the fire safety of the composite panels. Polyurethane alone cannot achieve Class A fire resistance, while in this application, phenolic foam serves as the core material, and its Class A2 fire resistance is maintained throughout the entire composite panel. The double-layer epoxy coating not only does not affect the fire-retardant effect of phenolic foam but also further enhances its high-temperature resistance. The combustion performance of Examples 1-6 all reaches Class A2, fully meeting fire resistance requirements. Conversely, if only polyurethane composite (without phenolic core material) is used, this fire resistance level cannot be achieved, making it unsuitable for scenarios with strict fire resistance requirements, such as building exterior walls and fireproof air ducts. Simultaneously, the excellent thermal insulation performance of phenolic foam is synergistic with the thermal insulation efficiency of polyurethane. The thermal conductivity of all embodiments remains stable at 0.024 W / m·K, ensuring the composite panels have highly efficient thermal insulation performance. Compared with single phenolic or single polyurethane, the thermal insulation performance is not diminished and is even more stable.

[0283] Furthermore, the test results of Comparative Examples 2-4 further verified the necessity of this complementary effect: Comparative Example 2 (single-layer epoxy, without effective polyurethane composite), due to the lack of polyurethane bonding reinforcement, had a peel strength of only 0.18 MPa and a water absorption rate of 2.1 vol%, which could not make up for the shortcomings of phenolic physical properties; Comparative Example 3 (commercially available interface agent, without in-situ polyurethane composite), had weak interfacial bonding (peel strength 0.15 MPa) and insufficient sealing (water absorption rate 3.8 vol%), which also failed to achieve effective complementarity between phenolic and polyurethane; Comparative Example 4 (improper process leading to poor bonding between polyurethane and phenolic), the board deformed and the coating cracked, the physical property advantages of polyurethane could not be brought into play, and the fireproof and heat insulation advantages of phenolic were also affected, further illustrating that only by achieving effective composite of the two can the goal of performance complementarity be achieved.

[0284] Examples 1-6 have a surface pH of 5.5-6.0, which is within the neutral range. After 168 hours of humid heat aging at 80℃ / 95%RH, none of them exhibited bubbling, delamination, or debonding, demonstrating excellent performance stability. Comparative Example 1 has a pH of 4.5 and showed severe delamination after humid heat aging. Comparative Examples 2-3 have a pH of 6.2-6.6 and exhibited slight bubbling and localized debonding, respectively. Comparative Example 4 has microcracks in its coating and is prone to aging and failure with long-term use. The double-layer epoxy coating layer of this application can completely seal off the acidic catalyst and free phenol remaining during the synthesis of the phenolic core material, preventing their slow precipitation. This serves three purposes: first, it protects the metal panel from corrosion, extending the product's service life; second, it prevents acidic substances from damaging the interface bonding with polyurethane, ensuring performance stability under humid heat conditions; and third, it keeps the product surface neutral, making it suitable for high-end applications. In contrast, Comparative Example 1 lacked epoxy sealing, allowing acidic substances to precipitate directly, corroding the metal and damaging the interface; Comparative Examples 2 and 3 had insufficient sealing, leaving a small amount of acid residue, which was prone to aging with long-term use; and Comparative Example 4 had process defects that caused the coating to crack, making it unable to prevent acid precipitation. None of these examples could achieve the stable performance of the embodiments in this application.

[0285] Examples 1-6 all employ a double-layer epoxy fully enclosed structure composed of a penetrating sealing primer and a dense isolating topcoat. A six-sided roller coating process is used to achieve pinhole-free and leak-proof coverage of the phenolic foam core material. The only differences are in the formulation ratio, coating parameters, and foaming process. Their core performance meets the design requirements of this application. Comparative Examples 1-4 represent four scenarios: no epoxy coating, single-layer epoxy coating, treatment with commercially available interface agent, and improper process parameters, respectively. All of their performance is significantly inferior to that of the examples.

[0286] Example 7

[0287] This embodiment repairs the cut surface of the sandwich panel prepared in Example 1. The sandwich panel prepared in Example 1 is taken and cut along its length to expose the new cut surface. The dense insulating topcoat used in Example 1 is applied to the cut surface with a brush, and after curing at room temperature for 2 hours, the water absorption rate is tested after 24 hours.

[0288] The 24-hour water absorption rate of the unrepaired cut surface was 6.8 vol%, while the 24-hour water absorption rate of the cut surface repaired with the dense isolation topcoat used in Example 1 was only 1.9 vol%, a significant decrease in water absorption rate.

[0289] The sandwich panel prepared in this application has the advantages of convenient and efficient repair of the cut surface, solving the performance degradation problem caused by the exposed cut surface after the composite board is cut. After cutting, the unrepaired cut surface of the composite board prepared in Example 1 has a water absorption rate as high as 6.8 vol% after 24 hours. However, after on-site repair with the dense isolation topcoat provided by this application and curing at room temperature for 2 hours, the water absorption rate drops to 1.9 vol% after 24 hours. This improves the performance degradation problems caused by water vapor penetration, acid precipitation, and interface debonding due to the exposed cut surface, ensuring the consistency and stability of the overall performance of the composite board.

[0290] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A phenolic and polyurethane in-situ composite thermal insulation sandwich panel, characterized in that, include: Phenolic foam core material; An epoxy fully enclosed coating layer covering all six sides of the phenolic foam core material; A polyurethane foam fusion layer covering the outer surface of the epoxy fully enclosed film layer; And a panel composited on the outer surface of the polyurethane foam fusion layer; The epoxy fully enclosed coating layer consists of a penetrating and sealing primer layer and a dense and insulating topcoat layer; The penetrating and sealing primer layer is made of the following raw materials in parts by weight: 100 parts epoxy resin, 10-15 parts reactive diluent, 45-55 parts amine curing agent, 1-3 parts silane coupling agent, and 0.3-0.8 parts defoamer. The dense isolation topcoat layer is made from the following raw materials in parts by weight: 100 parts epoxy resin, 5-10 parts reactive diluent, 25-35 parts cashew nut shell oil modified phenolic amine curing agent, 1-3 parts silane coupling agent, 0.2-0.5 parts defoamer, and 0.3-0.8 parts leveling agent.

2. The sandwich panel according to claim 1, characterized in that, The total dry film thickness of the epoxy fully enclosed coating layer is 120-160 μm.

3. The sandwich panel according to claim 1, characterized in that, The density of the phenolic foam core material is 35~45 kg / m³. 3 The thickness is 20~200mm.

4. A method for preparing a sandwich panel according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1, Surface activation treatment Surface activation treatment is applied to phenolic foam core material; S2, Apply primer Apply a penetrating and sealing primer to the surface of the activated core material, control the wet film thickness to 30~40μm, and dry at 50~70℃ for 8~12min to form a penetrating and sealing primer layer. S3, Apply topcoat A dense isolation topcoat is coated on the surface of the penetrating and sealing primer, the wet film thickness is controlled at 120~160μm, and dried at 70~80℃ for 10~15min to form a dense isolation topcoat layer, thus obtaining an epoxy fully sealed coating layer. S4, Closed Inspection Visual inspection with a magnifying glass revealed no exposed surfaces or pinholes on all six sides. S5, PU / PIR foam composite Polyurethane foam raw material is poured between the metal panel and the epoxy fully enclosed film layer, and foaming and composite are carried out at 20~28℃ and linear speed of 3~6m / min, with a foaming peak temperature ≤160℃. S6, Curing Cut Allow to mature at room temperature for ≥24 hours before cutting, inspecting, and packaging.

5. The preparation method according to claim 4, characterized in that, The surface activation treatment described in S1 is selected from one of corona treatment, plasma treatment or flame treatment, and the contact angle between the core material surface and water after treatment is ≤30°.

6. The preparation method according to claim 4, characterized in that, The pot life of the penetrating and sealing primer described in S2 is ≥40 min after mixing, and the pot life of the dense and isolating topcoat described in S3 is ≥60 min after mixing.

7. A method for repairing a sandwich panel as described in claim 1, characterized in that, A dense insulating topcoat layer is applied to the cut surfaces of the sandwich panel.

8. The application of the sandwich panel according to claim 1 in the fields of building exterior wall insulation, cold chain cold storage, pharmaceutical cleanroom, and fireproof air duct.