What materials are the inner core material and outer structure of the polyurethane cold storage board of the cold storage composed of?

The inner core of the polyurethane cold storage board uses rigid polyurethane foam as the core insulation material. This material forms a honeycomb structure with a closed-cell rate of more than 90% through a foaming process. The thermal conductivity of polyurethane foam is extremely low. When the density is 35~45 kg/m³, the thermal conductivity is only 0.018~0.023 W/(m·K), which is one of the lowest thermal conductivity categories among all insulation materials currently available. Its closed-cell structure effectively blocks heat transfer and reduces cold loss.
The closed-cell rate and high molecular hydrophobicity of polyurethane make it almost non-absorbent (water absorption rate ≤3%), and it can maintain stable insulation performance even in a high humidity environment, avoiding the increase of thermal conductivity due to moisture absorption. Polyurethane materials can be used stably in extreme temperature ranges from -100℃ to 150℃, and are suitable for a variety of scenarios such as freezers and quick-freeze warehouses. By adding flame retardants, polyurethane can reach the B1 level flame retardant standard. When burning, a carbonized layer is formed on the surface to isolate oxygen, inhibit the spread of fire, and no toxic gas is released at high temperatures.
The external structure of the cold storage board is composed of metal panels and composite lamination processes. The surface is galvanized and coated, which has corrosion resistance and impact resistance, and is suitable for conventional cold storage environments. Mainly 304 stainless steel, it is rust-proof and corrosion-resistant, and is suitable for high-sanitation standard scenes such as medicine and food. Embossed aluminum plates/galvanized steel plates are both lightweight and beautiful, and are often used in prefabricated cold storage or occasions that require surface decoration.
The metal panel is bonded to the polyurethane core material through a continuous roll forming process to form a sandwich structure. Some products adopt a concave and convex groove splicing design, and the air tightness of the joints is enhanced by eccentric hooks or labyrinth notches to reduce the cold bridge effect. The panel thickness is usually 0.4~0.8 mm, and different specifications are selected according to the load-bearing requirements. For example, color steel plates are often matched with 0.5 mm thickness, while stainless steel plates require higher strength to support the load.
The low thermal conductivity of polyurethane combined with the sealing of metal panels can reduce heat transfer caused by the temperature difference between the inside and outside of the cold storage and reduce the energy consumption of the refrigeration system. For example, in a -18℃ cold storage, using a 150 mm thick cold storage panel can reduce energy consumption by about 30%. The metal panel provides compressive and bending strength (compressive strength ≥ 200 kPa), while the closed-cell structure of the polyurethane core material gives the panel anti-freeze and anti-deformation capabilities, with an average service life of more than 30 years.
The corrosion resistance of stainless steel or color steel panels combined with the moisture resistance of polyurethane make it suitable for harsh environments such as high temperature, high humidity, and salt spray, such as coastal areas or chemical cold storage. Standardized panel size and plug-in design support rapid assembly and modular expansion of cold storage, especially suitable for prefabricated cold storage construction.