High flame-retardant polyurethane cold storage board

Abstract

The utility model discloses a high -performance flame -retardant polyurethane cold storage board relates to cold storage heat preservation field, it includes: frame, pouring opening subassembly, double -deck composite core material, dovetail groove, dovetail convex stripe and apron, the core material contains the intussusception graphite -epoxy resin composite flame -retardant layer of frame inner wall and the flame -retardant modified polyurethane hard bubble layer of inboard, frame both sides are equipped with dovetail shape splicing, and the pouring opening is equipped with the leakage -proof rubber valve, and the apron is equipped with pressure -relief valve. The composite flame -retardant layer meets the fire fast carbonization, and the whole reaches A -class non -combustible, and the dovetail structure + sealing layer reduces the cold loss, and the reinforcing rib promotes the strength, is applicable to various cold storage, long -term durable, and the fire -retardant effect is good.

Description

Technical Field

[0001] This utility model relates to the field of cold storage insulation and flame retardant technology, specifically a high flame retardant polyurethane cold storage panel using composite flame retardant core material. Background Technology

[0002] Cold storage facilities, as core facilities for low-temperature storage, have stringent requirements for the flame retardancy rating, insulation stability, and structural strength of insulation materials. Existing technologies, such as the "Easy-to-process High Flame Retardant Polyurethane Cold Storage Panel" with authorization announcement number CN210887923U, employ a cross-shaped splicing structure. The core material is a single polyurethane material with added flame retardant, lacking an independent flame retardant layer design, and can only achieve a B1 flame retardancy rating.

[0003] The existing technology has significant shortcomings: First, its flame retardant performance is insufficient and its long-term effectiveness is poor. The flame retardancy of a single core material relies on an addition of 8%-10% flame retardant, which is prone to flame spread when exposed to fire. Furthermore, traditional flame-retardant substrates are prone to moisture absorption in the humid and low-temperature environment of cold storage, leading to a decline in flame retardant performance. Second, there is an imbalance between thermal insulation and strength. After increasing the amount of flame retardant added to improve flame retardancy, the thermal conductivity of the core material increases to above 0.028 W / (m·K), while the bending strength drops to below 0.8 MPa. Third, the splicing stability is poor. The cross-shaped protrusions rely solely on mechanical interlocking, which easily creates gaps due to low-temperature shrinkage, resulting in a high cold leakage rate. Fourth, the core material is not firmly bonded to the frame. There is no adaptation treatment on the inside of the panel, and the bonding strength is only 0.12 MPa, making it prone to peeling off after long-term use. Summary of the Invention

[0004] To address the problems of low flame retardancy rating, imbalance between insulation and strength, poor splicing stability, and easy core material detachment in existing polyurethane cold storage panels, this utility model designs a high flame retardant polyurethane cold storage panel consisting of an "expanded graphite-epoxy resin composite flame retardant layer + flame retardant modified polyurethane rigid foam layer + dovetail splicing".

[0005] This utility model includes a frame, a gating assembly, a core material, a dovetail groove, a dovetail protrusion, and a cover plate. The core material is a double-layer composite structure, including an expanded graphite-epoxy resin composite flame-retardant layer adhered to the inner wall of the frame and a flame-retardant modified polyurethane rigid foam layer filled inside the composite flame-retardant layer. The flame-retardant modified polyurethane rigid foam layer is formed by single high-pressure foaming after mixing isocyanate, polyol, and phosphorus-nitrogen composite flame retardant. The frame has a "front-left-rear-right" closed-loop structure. A dovetail protrusion is integrally formed on the left side of the frame, and a dovetail groove adapted to the dovetail protrusion is opened on the right side. The gating assembly includes a pipe body and a plug. The tube body is fixed to the front panel of the frame and forms an injection channel inside. The front end of the tube body has an internal thread, and the plug is adapted to the internal thread of the front end of the tube body and screwed in to fix it. The rear end of the tube body has a rubber valve that closes its opening. A slot is opened in the middle of the rubber valve. Two cover plates are respectively covered on the top and bottom of the frame and fixedly connected to the frame. The core material is filled into the sealed cavity enclosed by the frame and the two cover plates. The expanded graphite-epoxy resin composite flame retardant layer is bonded to the inner wall of the frame by an adhesive. The flame retardant modified polyurethane rigid foam layer is tightly bonded to the expanded graphite-epoxy resin composite flame retardant layer.

[0006] Furthermore, the expanded graphite-epoxy resin composite flame-retardant layer has a thickness of 5-10mm, a compressive strength ≥1.2MPa after curing, and a bonding strength ≥0.15MPa with the inner wall of the frame; the flame-retardant modified polyurethane rigid foam layer has a density of 40-45kg / m³ and a thermal conductivity ≤0.025W / (m·K); the frame is made of 0.4-0.8mm thick color-coated steel plate, the substrate is cold-rolled steel plate, and the surface coating is polyester or fluorocarbon coating; the cover plate is made of 0.3-0.5mm thick color-coated steel plate of the same material as the frame, with a 5mm high overlap edge, and is fixed to the frame by riveting with rivets at a spacing of 250-300mm to improve connection stability and weather resistance.

[0007] Furthermore, the inner sides of the front and rear panels of the frame are sandblasted to a roughness of Ra1.2-1.6μm and coated with polyurethane primer to enhance the adhesion with the composite flame-retardant layer; the dovetail groove wall and the root of the dovetail protrusion on the inner side of the frame are equipped with high-temperature resistant silicone baffles. The baffles are arranged along the length of the frame and are fixed to the inner wall of the frame. The temperature resistance range is -40℃ to 200℃ and the water absorption rate is ≤1.5%, which precisely defines the foaming range and prevents materials from overflowing into the dovetail groove.

[0008] Furthermore, the groove wall and the surface of the dovetail protrusion are provided with a flame-retardant sealing layer, which is a double-layer structure of pearl cotton base layer with flame-retardant non-woven fabric on the outside. It is fixed by polyurethane adhesive, which not only improves the sealing performance but also enhances the flame retardancy. The core material is provided with diagonal corrugated aluminum alloy reinforcing ribs with a spacing of 500mm. They are fixed to the composite flame-retardant layer by high-temperature resistant structural adhesive, which improves the overall bending strength.

[0009] Furthermore, the cover plate is provided with a pressure relief hole with a one-way pressure relief valve along its length, with an opening pressure of 0.25-0.3MPa and a closing pressure of 0.2MPa to balance the foaming pressure; the end of the plug is provided with a nitrile sealing ring to ensure the sealing of the pouring port; the adhesive is an epoxy resin modified adhesive, which is suitable for the composite flame retardant layer structure and has a bonding strength of not less than 0.15MPa.

[0010] The advantages of this utility model are: 1. Excellent flame retardant performance: the composite flame retardant layer expands within 30 seconds of exposure to fire to form a dense char layer of ≥15mm, which, together with the core material, achieves Class A non-combustible flame retardancy, and the smoke density is reduced by 40% compared with traditional solutions; 2. Balanced insulation and strength: the composite flame retardant layer has a water absorption rate of ≤1.5% to avoid insulation attenuation, the core material has a thermal conductivity of ≤0.025W / (m·K), and the reinforcing rib design makes the bending strength ≥1.0MPa; 3. Stable splicing: the dovetail structure combined with double-layer sealing reduces the cold leakage rate by 50% and improves the installation efficiency by 25%; 4. Long-lasting and durable: the composite flame retardant layer is resistant to aging and the flame retardant is resistant to migration, and its performance does not decrease after 50 cycles of hot and cold, with a service life of ≥30 years. Attached Figure Description

[0011] Figure 1 This is a perspective view of the present utility model; Figure 2 This is a front view of the present utility model; Figure 3 This is a schematic diagram of the gating system assembly. In the figure, 1-frame; 2-gating port assembly; 3-core material; 4-dovetail groove; 5-dovetail protrusion; 6-cover plate; 21-pipe body; 22-plug; 23-rubber flap. Detailed Implementation

[0012] Example 1: This example implements a complete landing solution, as follows: Frame 1 is made of 0.6mm thick fluorocarbon coated color-coated steel plate, and the substrate is cold-rolled steel plate. The inner sides of the front and rear panels are sandblasted to Ra1.4μm and coated with polyurethane primer. A closed-loop structure of "front-left-rear-right" is processed according to the dimensions. The left side has an integrally formed dovetail protrusion 5, and the right side has an adapted dovetail groove 4. Silicone baffle strips with a temperature resistance of -40℃ to 200℃ are attached and fixed to the groove wall of the dovetail groove 4 and the root of the dovetail protrusion 5. The tube body 21 of the pouring port assembly 2 is made of Φ18mm stainless steel tube, which is welded and fixed to the front panel of frame 1. The rear end is press-fitted with a nitrile rubber flap 23 (1mm×8mm in the middle slot), and the front end is screwed with a nylon plug 22 with a nitrile sealing ring.

[0013] Core Material 3 Preparation: Both layers of the core material utilize materials known in the flame-retardant field. The main components of the expanded graphite-epoxy resin composite flame-retardant layer, expanded graphite and epoxy resin, are commonly used flame-retardant substrates and bonding agents. The isocyanate, polyol, and phosphorus-nitrogen composite flame retardant of the flame-retardant modified polyurethane rigid foam layer are also conventional raw materials for polyurethane flame-retardant modification. In this embodiment, a slurry of 65% expanded graphite (80 mesh, expansion ratio 250 times) and 35% epoxy resin was prepared and applied to the inner wall of frame 1 with a thickness of 8 mm. Accelerated curing at 80℃ for 2 hours formed the expanded graphite-epoxy resin composite flame-retardant layer, with a compressive strength of 1.3 MPa. This composite flame-retardant layer expands within 30 seconds of exposure to fire, forming a dense char layer ≥15 mm thick, exhibiting significantly superior heat and oxygen insulation capabilities compared to traditional single flame-retardant layers. Corrugated aluminum alloy reinforcing ribs are obliquely fixed to the inner side of the composite flame-retardant layer at 500 mm intervals, bonded using high-temperature resistant structural adhesive. The cover plate 6 is made of 0.4mm thick color-coated steel plate of the same material, with a 5mm overlap edge and a pressure relief hole with a one-way pressure relief valve (opens at 0.3MPa and closes at 0.2MPa). It is riveted to the bottom of the frame 1 with a rivet spacing of 300mm.

[0014] Preparation of Flame-Retardant Modified Polyurethane Rigid Foam Layer: In this embodiment, isocyanate, polyol, and phosphorus-nitrogen composite flame retardant are mixed at a mass ratio of 45:45:10 and injected through pipe 21 using a high-pressure foaming machine at a foaming pressure of 0.28 MPa. The pressure relief valve automatically balances the pressure. After curing, the core material 3 has a density of 42 kg / m³ and a thermal conductivity of 0.024 W / (m·K). This flame-retardant rigid foam layer uses a phosphorus-nitrogen composite flame retardant to achieve synergistic flame suppression in both the gas and solid phases, significantly improving the flame-retardant efficiency compared to traditional single flame retardants. Furthermore, the optimized formula also addresses the insulation requirements for low thermal conductivity, solving the problem of "imbalance between flame retardancy and insulation" in traditional flame-retardant rigid foam. Finally, the top cover plate 6 is riveted, and a pearl cotton + flame-retardant non-woven fabric sealing layer is bonded to the surfaces of the dovetail groove 4 and dovetail protrusion 5 to complete the fabrication. The overall product meets Class A non-combustible standards, with a bonding strength of 0.16 MPa.

[0015] Example 2: This example refines the preparation of the composite flame-retardant layer as follows: Expanded graphite with a particle size of 120 mesh is dried at 100℃ for 2 hours to remove moisture, and mixed with bisphenol A type epoxy resin at a ratio of 70:30. 2% curing agent (amine) is added, and the mixture is stirred at 1500r / min for 10 minutes using a high-speed mixer to prepare a uniform slurry. After sandblasting the inner side of the frame 1 panel, two coats of epoxy resin primer are applied. The second coat is applied after the first coat is surface dry, with a total thickness of 0.1mm. A scraper with thickness control is used when applying the slurry to ensure a uniform thickness of 5mm. The slurry is cured at room temperature for 24 hours. After curing, the surface flatness is 0.4mm / m, the bonding strength with the panel is 0.17MPa, and it expands to form a 16mm char layer after 25s of exposure to fire. The smoke density is 45, which is significantly lower than the smoke density of conventional boards in the prior art.

[0016] Example 3: This example refines the combination of core material and reinforcing ribs, specifically as follows: The flame-retardant modified polyurethane rigid foam layer formula is adjusted to isocyanate 40: polyol 50: phosphorus-nitrogen composite flame retardant 10, with the addition of 1% silicone oil defoamer, reducing the thermal conductivity to 0.023 W / (m·K); under this formula, the oxygen index of the rigid foam layer reaches 32%, and the flexural strength is 1.1 MPa, which improves both the mechanical and flame-retardant properties compared to traditional flame-retardant rigid foam. The corrugated aluminum alloy reinforcing ribs are made of 1.2 mm thick profiles with a corrugation height of 8 mm. After cutting, structural adhesive is applied to both ends, and after being bonded to the composite flame-retardant layer, they are fixed with clamps for 2 hours to ensure a strong bond; during foaming, the material wraps around the reinforcing ribs, forming an integrated "reinforcing rib-core material" structure, suitable for large-span cold storage scenarios.

[0017] Example 4: This example refines the splicing and sealing structure as follows: The dovetail groove 4 is designed with a groove width of 20mm and a groove depth of 15mm. The dovetail protrusion 5 is adapted to the groove with a fitting gap of 0.1mm. The sealing layer uses 2mm thick pearl cotton as the base layer, composited with 0.6mm thick flame-retardant non-woven fabric, and bonded with two-component polyurethane adhesive. The adhesive application amount is 0.3g / cm², and after bonding, a pressure of 0.5MPa is applied and maintained for 30min. During splicing, the dovetail protrusion 5 is inserted into the dovetail groove 4, the sealing layer compression rate is 30%, and the cold leakage rate is ≤0.01W / (m²·K), which is 55% lower than the traditional tongue and groove structure.

[0018] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high flame-retardant polyurethane cold storage panel, characterized in that, The system includes a frame (1), a gating assembly (2), a core material (3), a dovetail groove (4), a dovetail protrusion (5), and a cover plate (6). The core material (3) is a double-layer composite structure, including an expanded graphite-epoxy resin composite flame retardant layer attached to the inner wall of the frame (1) and a flame retardant modified polyurethane rigid foam layer filled inside the composite flame retardant layer. The flame retardant modified polyurethane rigid foam layer is formed by single high-pressure foaming after mixing isocyanate, polyol and phosphorus-nitrogen composite flame retardant. The frame (1) is a "front-left-back-right" closed-loop structure. A dovetail protrusion (5) is integrally formed on the left side of the frame (1), and a dovetail groove (4) adapted to the dovetail protrusion (5) is opened on the right side. The gating assembly (2) includes a pipe body (21), a plug (22), and a cover plate (6). A rubber valve (23) and a tube (21) are fixed to the front panel of the frame (1) and form an injection channel inside. The front end of the tube (21) is provided with an internal thread. The plug (22) is adapted to the internal thread at the front end of the tube (21) and screwed in to fix it. The rear end of the tube (21) is provided with a rubber valve (23) that closes its opening. A slot is opened in the middle of the rubber valve (23). The two cover plates (6) are respectively covered on the top and bottom of the frame (1) and fixedly connected to the frame (1). The core material (3) is filled in the sealed cavity enclosed by the frame (1) and the two cover plates (6). The expanded graphite-epoxy resin composite flame retardant layer is bonded to the inner wall of the frame (1) by an adhesive. The flame retardant modified polyurethane rigid foam layer is tightly bonded to the expanded graphite-epoxy resin composite flame retardant layer.

2. The high flame-retardant polyurethane cold storage panel according to claim 1, characterized in that, The thickness of the expanded graphite-epoxy resin composite flame retardant layer is 5-10mm, the compressive strength after curing is ≥1.2MPa, and the bonding strength with the inner wall of the frame (1) is ≥0.15MPa; the density of the flame retardant modified polyurethane rigid foam layer is 40-45kg / m³, and the thermal conductivity is ≤0.025W / (m·K); the frame (1) is made of 0.4-0.8mm thick color-coated steel plate, the substrate is cold-rolled steel plate, and the surface coating is polyester or fluorocarbon coating; the cover plate (6) is made of 0.3-0.5mm thick color-coated steel plate of the same material as the frame (1), with a 5mm high overlap edge, and is riveted to the frame (1) by rivets with a rivet spacing of 250-300mm.

3. The high flame-retardant polyurethane cold storage panel according to claim 2, characterized in that, The inner sides of the front and rear panels of the frame (1) are sandblasted with a roughness of Ra1.2-1.6μm and coated with polyurethane primer. The dovetail groove (4) and the root of the dovetail protrusion (5) on the inner side of the frame (1) are provided with high temperature resistant silicone baffle strips. The baffle strips are arranged along the length of the frame (1) and are attached and fixed to the inner wall of the frame (1). The temperature resistance range is -40℃ to 200℃ and the water absorption rate is ≤1.5%.

4. The high flame-retardant polyurethane cold storage panel according to claim 3, characterized in that, The dovetail groove (4) and the surface of the dovetail protrusion (5) are provided with a flame-retardant sealing layer. The sealing layer is a double-layer structure of flame-retardant non-woven fabric on the outside of the pearl cotton base layer. It is bonded and fixed to the surface of the dovetail groove (4) and the dovetail protrusion (5) by polyurethane adhesive. The core material (3) is provided with corrugated aluminum alloy reinforcing ribs arranged obliquely. The spacing between the reinforcing ribs is 500mm. They are fixed to the flame-retardant layer of expanded graphite-epoxy resin composite by high-temperature resistant structural adhesive.

5. The high flame-retardant polyurethane cold storage panel according to claim 4, characterized in that, The cover plate (6) is provided with a pressure relief hole with a one-way pressure relief valve along its length. The one-way pressure relief valve has an opening pressure of 0.25-0.3MPa and a closing pressure of 0.2MPa. The end of the plug (22) is provided with a nitrile sealing ring, which fits and seals against the front end face of the pipe body (21). The adhesive is an epoxy resin modified adhesive, and the bonding strength between the expanded graphite-epoxy resin composite flame retardant layer and the inner wall of the frame (1) is not less than 0.15MPa.

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