What Is A PU Sandwich Panel?
A PU Sandwich Panel is a sandwich-structured composite made of polyurethane foam sandwiched between two side skins:
Polyurethane Core (PU/PUR)
Polyurethane insulation core is typically produced by the reaction of an isocyanate with a polyol, the PU foam board acts as a thermal barrier and ensures low thermal conductivity and excellent resistance to moisture, humidity, and other environmental factors.
Skin Layers
PU sandwich panel consisting of an upper and inner layer made of galvanized steel sheets, PPGI (pre-painted galvanized iron), PPGL (pre-painted galvalume iron, coated by a hot dip zinc substrate), Prepainted steel, Stainless steel plates, Aluminium plate, Fiberglass skin, Fibreglass Reinforced sheet (FRP), CFRT sheet, Plywood, embedded wood, etc. The two skin layers are glued to the PU insulation core using polyurethane resin glue.
Why Choose PU Sandwich Panels?
PU sandwich panels have become essential for multiple commercial and industrial applications where a combination of high structural rigidity, low weight, and insulation performance is required, these characteristics make them preferred for various industries ranging from construction to cold rooms, cold storage, and cold chain. Moreover, these cost-effective PU insulated sandwich panels are popular for a variety of uses including insulated walls, partitions, claddings, roofs, floors, and building envelopes. Besides this, PU sandwich panels are highly resistant to moisture, mold, mildew, bacteria, and other environmental factors such as humidity, temperature variations, abrasion, and corrosion.
What PU Sandwich Panels Are Used For?
PU sandwich panel is an excellent choice for a wide range of applications including interior or exterior walls, partitions, ceilings, roofs, cladding, floors, and doors, these structural panels are most commonly used for the architecture, engineering and construction industry (AEC):
Prefabricated Buildings
- Single and multi-story buildings
- Prefabricated houses and shelters
- Prefabricated buildings
- Prefab buildings
- Portable cabins
- Airplane hangars
Buildings and construction
- Residential complexes
- Commercial facilities
- Office buildings
- Shopping centers
- Clinics and health care centers
- Schools and universities
- Stadiums and sports facilities
- Multi-purpose halls
Agricultural buildings
- Steel agriculture buildings
- Metal farms buildings
- Agricultural storage buildings
- Insulated livestock farms
- Barns and poultry sheds
- Crops and commodity storage structure
- Harvesting equipment stores
Temperature Controlled Environment
- Controlled environmental room
- Clean rooms/Cold rooms
- Cold storage facilities
- Ripening chambers
- CA chambers
Refrigerated Units
- Walk-in refrigeration units
- Refrigeration and freezing room
- Negative temperature cold rooms
- Temperature-sensitive storage
- Temperature controlled warehouse
Applications in Trucks
- Insulated box trucks
- Refrigerated/van trucks
- Refrigerated cargo/van
- Vehicles with refrigerated body
- Freezer trucks/trailer
- Chiller lorry
RVs
- Caravans
- Travel Trailers
- Motor homes
What Are the Components Of PU Sandwich Panels?
PU sandwich panel is a factory pre-engineered system, each unit consists of three layers that are strongly bonded with an adhesive (Polyurethane resin glue).
Polyurethane Insulation (PU/PUR)
Polyurethane insulation offers a thermal conductivity ranging from 0,022 to 0,024 W/(m*K), and an R-value between 6.0 and 7.14 in, thanks to the polyurethane foam structure which contains 90% of rigid closed-cell and has a density core of 32 – 60 Kg per m3. Polyurethane foam is available in different sizes and thicknesses that suit all applications, it is also highly resistant to water, moisture and the elements.
Skin Layers
The two side facings consist of upper and lower layers, both of the skin layers are made from high-strength metal or non-metal material such as:
- PPGI (Pre-painted Galvanized iron)
- PPGL (Pre-painted Galvalume iron)
- Galvanized steel sheets
- Pre-painted steel sheets
- Stainless steel sheets
- Aluminum plate
- Glass Reinforced Plastic (GRP)
- Fiberglass Reinforced Polymer (FRP)
- Plywood or Oriented Strand Board (OSB)
Protective coating
Metal skin layers can be protected using different types of coatings such as:
- Polyester (PE)
- SP Polyester 25 μm
- SP Polyester Mat Pearl 35 μm
- Food Safe PVC
- Aluzinc + Easyfilm,
- Polyvinyl chloride (PVC) coating
- Polyvinylidene fluoride (PVDF)
- Silicone modified polyester (SMP)
- High durability polyester (HDP)
What Are the Characteristics of Polyurethane Sandwich Panels?
PU sandwich panels are widely used to build the most sophisticated commercial and industrial facilities, thanks to the extremely durable material which offers unmatched benefits, we summarized some of them:
Thermal Insulation
PU sandwich panels offer an excellent thermal conductivity (lambda λ) of 0.022 (W/mK), this coefficient is unparalleled by any other insulation material like EPS (Expanded Polystyrene) and Mineral Wool (MW), thanks to the PU system core which provides superior thermal insulation while it minimizes heat transfer across the whole building envelopes including walls, partitions, facades, ceilings, roofs and floors. Furthermore, Polyurethane (PU) sandwich panels have an average R-value of 6.5 per inch of thickness, the R-value (W/m²K) is normally determined by the thickness of the polyurethane foam (PU), the higher the R-value the better is the thermal resistance of the PU sandwich panel and the more it resists the conductive flow of heat.
Air-Tightness
One of the most important features of polyurethane sandwich panels is their excellent insulation properties and airtight structure, which resists air, water, vapor ingress, and moisture, each structural insulated panel (SIP) comes with a tongue and groove joints sealed with white or transparent sealants, the sealing is applied to avoid air infiltrations and leakage of heat or cooling energy through the building envelope, this enhances energy-efficiency and substantially lower the energy spend for heating in the winter and cooling in the summer, which minimize energy costs over the long run while it maintains a consistent temperature inside the building and provide comfort.
What Are The Types Of PU Sandwich Panels?
PU sandwich panels are highly versatile, architects and builders can choose from a variety of attractive features that include a wide range of shapes, profiling patterns, colors, finishes, protection coatings, and endless customization options, this allows them to achieve the greatest benefits at the lowest cost. The most commonly used PU sandwich panels are as follows:
- PU Wall Sandwich Panels
- PU Roof Sandwich Panels
- PU Floor Sandwich Panels
- PU Sandwich Panels for Duct Board
- HVAC Air Duct PU Sandwich Panels
- Insulated Air Ducts (Polyurethane Insulation Panel)
- PU Sandwich Panels for Cold Rooms
- PU Sandwich Panels for Cold Storage
- Fireproof PU Sandwich Panels
Also, PU sandwich panels come with different types of fixing and joints:
- Secret Fix Panels
- Hidden screw sandwich panel
- Boltless sandwich panel
- Hidden joint sandwich panel
What Sizes Are PU Sandwich Panels?
Polyurethane sandwich panels can be manufactured in a variety of sizes; the following are the standard sizes available on the sandwich panels market, while custom sizes can be also provided:
- Interior and Exterior skin: 0.5 – 0.8 mm steel sheet
- Width: 500 -1000 (mm)
- Length: 2.0 – 24 (m)
- Thickness: 40, 60, 75, 100, 125, 150, 170, 200 (mm)
- PU Wall Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120, 150, 170, 200 mm
- PU Roof Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120 mm
- PU Cold Room Sandwich Panel: 120, 150, 170, 200 mm
- PU Duct Panel Sandwich Panel: 20, 30 mm
What Is The Length Of PU Sandwich Panels?
The length of the PU sandwich panel depends mainly on the application requirements; the standard length of PU sandwich panels varies between 2 – 16 mts, and up to 22 meters long. Also, PU sandwich panels can be custom-sized to a specific length.
What Is The Weight Of PU Sandwich Panels?
The weight of the PU sandwich panel is determined by the thickness of the skin and the density of PU foam and size. On average, PU sandwich panels’ weight ranges between 10 and 20 (kg/m2), however, most PU sandwich panels come on the following weight (kg/m2):
- Thickness: 40 mm, weight (kg/m2): 10
- Thickness: 80 mm, weight (kg/m2): 12
- Thickness: 140 mm, weight (kg/m2): 14
- Thickness: 200 mm, weight (kg/m2): 17
What Is the Production Process Of PU Sandwich Panels?
A PU sandwich panel typically consists of two elements: a polyurethane insulation core and two metal sheets (skin layers), these components are produced as follows:
Polyurethane Core
Polyurethane panels (PU-PUR) foam production starts by mixing the required chemicals which are metered and dosed together in a polyurethane foaming system like “PU Foaming Machine” or “Metering Machine”, the mixture results in creating a liquid which is distributed over the metal skin layer (rigid metal facing material).
Skin Layers
The skin layers or metal sheets could be PPGI (pre-painted galvanized iron), PPGL (pre-painted Galvalume iron), and Aluminum sheets, these skin layers are formed or grooved with a roll forming machine (metal roll forming machine) which is used to produce flat metallic sheets when mass-production is required. Also, rigid metal facings can be coated by metallic substrate, hot dip zinc substrate or color coated.
How PU Sandwich Panels Are Manufactured?
Polyurethane (PU) sandwich panels are manufactured using continuous or discontinuous production lines:
Continuous Polyurethane Sandwich Panel Line
All the materials are processed together and operated continuously, the process includes an automatic feeding of raw materials, and passes by the roll forming system, after that, the formed panels are finished and cut to the desired lengths without stopping the production line. The continuous PU sandwich panel line comes with an advanced automation system that ensures high-volume manufacturing, and high speed which is 10 times more than the discontinuous PU sandwich panel line, it can also produce 12 meters per minute double press and achieve a production capacity of about 1,180,000 meters per year.
Discontinuous Polyurethane Sandwich Panel Line
In a discontinuous process, the materials are processed separately, while the facings sheets are formed and cut to the desired length, after that, all the components are joined together in a press where the foam is injected. Cutting-edge manufacturing equipment is used to customize PU sandwich panels and create special shapes. The discontinuous polyurethane sandwich panel line is used to produce a small volume of PU sandwich panels as it has limited production capacity and cannot be compared with that of the continuous sandwich panel production line.
Frequently Asked Questions
1. What is a PU sandwich panel?
A PU sandwich panel is an insulated composite panel made with a rigid polyurethane foam core between two outer facing layers. The polyurethane core provides thermal insulation, while the outer layers add strength and protect the insulation.
2. What are PU sandwich panel used for?
PU sandwich panels are used for walls, partitions, ceilings, roofs, floors, doors, and other insulated structures. They are commonly used in cold rooms, cold storage facilities, refrigerated warehouses, industrial buildings, prefabricated building, agricultural facilities and refrigerated transport.
3. Are PU panels moisture resistant?
Yes. The closed cell polyurethane foam core has a good resistance to moisture and water absorption. Properly installed and sealed panel joints also help reduce the entry of air, water vapor, and moisture into the insulated structure.
4. What types of PU sandwich panels are available?
PU sandwich panels are available for different applications, including wall panels, roof panels, floor panels, cold room panels, cold storage panels, and HVAC duct panels. Different joint and fixing systems are also available depending in the project requirements.
5. What sizes are PU sandwich panels available in?
PU sandwich panels are available in different widths and thicknesses depending on their applications. Common panel widths range from 500mm t0 1,000mm, while thickness can be selected according to the required insulation performance. Custom dimension can also be produced for specific projects.
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