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Polyurethane sandwich panels (PU) are among the best choices for constructing prefabricated structures, cold storage facilities, and industrial buildings.
These panels consist of a polyurethane foam core sandwiched between two metal sheets (galvanized, aluzinc, or aluminum).
Thanks to their unique features — exceptional thermal and sound insulation, high resistance to moisture and fire, as well as outstanding durability — polyurethane sandwich panels are widely used across various industries.
Advantages of Polyurethane Sandwich Panels
• Excellent Thermal Insulation: The closed-cell structure of polyurethane minimizes heat transfer and reduces energy consumption.
• Superior Sound Insulation: Effectively blocks incoming and outgoing noise, making it ideal for industrial and office environments.
• High Fire Resistance: Fire-retardant polyurethane (B1 or B2 grade) resists flames and prevents the spread of fire.
• Moisture and Corrosion Resistant: Performs excellently in humid environments and inhibits mold and mildew growth.
• High Mechanical Strength: Resistant to pressure and impact, suitable for long-lasting structures.
• Lightweight and Easy to Install: Despite its strength, the panel is lightweight and can be installed quickly.
Disadvantages of Polyurethane Sandwich Panels
• Higher Cost: The production cost of polyurethane is higher than polystyrene, though it pays off in the long run due to its superior quality.
• Limited Recyclability: Polyurethane is not easily recyclable, which may pose limitations for environmentally-conscious projects.
Applications of Polyurethane Sandwich Panels
• Cold Storage and Industrial Refrigerators: Prevents energy loss due to excellent insulation.
• Prefabricated and Residential Buildings: Used for walls and roofs of modern structures.
• Factories and Industrial Warehouses: Withstands heat and chemical exposure.
• Food and Pharmaceutical Transport Trucks: Maintains optimal temperatures inside compartments.
• Hospitals and Laboratories: Ensures controlled and isolated environments.
Mehdi Panel Polyurethane Sandwich Panels
At Mehdi Panel, polyurethane sandwich panels are produced using fully automated (continuous) production lines.
We offer two types of polyurethane foam differing in fire resistance:
• Standard fire-retardant polyurethane with B2 fire rating
• German-made PIR (Polyisocyanurate) with B1 rating, fully fire-resistant
As seen in the panel image, foam is uniformly injected throughout the entire panel, including the tongue-and-groove joints, maximizing thermal resistance and minimizing energy transfer.
The polyurethane foam used in Mehdi Panel products has a density of 40 kg/m³, ensuring maximum performance.
The metal sheets used are pre-painted galvanized steel, primarily sourced from reputable domestic suppliers such as Mobarakeh Steel Company.
Pricing of Polyurethane Sandwich Panels
The price of polyurethane sandwich panels depends on several factors, each contributing to the final cost:
Factors Affecting Price:
• Surface Sheet Type: The material and thickness of the surface sheet (usually galvanized or aluminum) directly impact the price. Higher quality and thicker sheets cost more.
• Polyurethane Foam Thickness: Thicker foam provides better insulation and increases the cost.
• Panel Dimensions: Custom sizes can raise production costs.
• Foam Density: Higher-density foam offers better insulation and costs more.
• Surface Finish: Coatings, colors, and textures influence the price.
• Order Quantity: Bulk purchases often come with discounts.
• Manufacturer Brand: Quality, after-sales service, and warranty also affect pricing.
• Market Fluctuations: Raw material costs, exchange rates, and economic factors play a role.
Tips for Buying Polyurethane Sandwich Panels
• Quality: Check the quality of raw materials and manufacturing. High-quality panels last longer and reduce maintenance costs.
• Price vs. Quality: The cheapest option is not always the best.
• Warranty: Purchase from manufacturers offering product warranties.
• Consultation: Speak to sales experts to choose a panel that meets your needs and budget.
Available Types of Polyurethane Sandwich Panels
• Roof Panels: Produced in widths of 107 cm (effective width 100 cm) with a five-rib design, available in thicknesses from 2 to 6 cm.
• Wall Panels: Produced in widths of 102 cm (effective width 100 cm) with a rail design, available in thicknesses from 3 to 15 cm.
Production Methods of Polyurethane Sandwich Panels
Continuous Method
In the continuous (mechanized) method, machines and mechanical robots transform raw materials into finished panels. Galvanized sheet rolls, polyurethane foam components (polyol and isocyanate), and adhesives enter the machine from one end and emerge as finished, cut, and packaged panels from the other.
Polyurethane Continuous Machine
This was the first type of machine imported to Iran for producing sandwich panels.
The production line includes two or more uncoilers (for top and bottom sheets), roll-forming stations, specialized rollers for shaping the sheets, and a mixing unit where polyol and isocyanate are combined and injected. The foam expands, releases heat, and must quickly be pressed and cured at high temperature. Finally, panels are cut to size, cooled, and packaged.
Discontinuous Method
In the discontinuous (non-continuous) method, each step occurs at separate stations. Sheets are roll-formed and placed in molds, injected with foam, pressed, heated, cooled, and then removed from the mold before repeating the cycle.
Advantages of Polyurethane Foam
• Highest density among insulation cores: approximately 40 ± 2 kg/m³
• First foam used in sandwich panel production in Iran
• Produced both continuously and discontinuously
• High molecular bonding due to exothermic reaction of polyol and isocyanate
• Excellent adhesion to galvanized sheets
• Completely fills gaps and cavities upon expansion
• Lower thermal conductivity than polystyrene, providing higher thermal resistance (higher R-value)
Disadvantages of Polyurethane Foam
• More expensive than other insulation materials, significantly increasing product cost
• Produces toxic cyanide gas when burned, posing a serious fire hazard; its use is restricted in some building codes
• High water absorption can reduce cold storage efficiency and insulation performance
• Not recommended for areas where thermal insulation is less critical due to its high cost
• Limited production options in very thick dimensions
• Potential manufacturing defects can result in weak or hollow panels, which are difficult to detect
• Completely reliant on imported raw materials, making production vulnerable to sanctions and supply chain issues
• Releases greenhouse gases during production, harmful to the environment and ozone layer — increasingly restricted in eco-conscious countries