Polystyrene sandwich panels, also referred to as EPS color-steel composite panels, consist of a flame-retardant polystyrene foam core bonded between two color-coated steel facings. The steel facings are typically 0.4 mm to 0.8 mm in thickness. The core is a molded expanded polystyrene board. A two-component polyurethane adhesive is commonly used to bond the facings and core into a single component. Tianjin SENBO manufactures these panels on dedicated continuous lamination lines, with in-house control over facing material selection, adhesive application, and core density to maintain consistent product quality.
The panel works on the stressed-skin principle. Under bending, the metal facings resist tensile and compressive forces, while the core transfers shear stress and holds the facings apart. This design provides higher flexural rigidity than would be expected from the panel's weight alone. Senbo's production monitoring covers core density and bond strength at regular intervals, which helps ensure that the stressed-skin behavior remains reliable over the panel's service life.
Standard thickness options include 50 mm, 75 mm, 100 mm, 150 mm, 200 mm, and 250 mm. Effective widths are 1150 mm or 1200 mm. Panels can be produced in lengths up to 12,000 mm, and custom sizes are available depending on transport and project requirements.
| Performance Indicator | Parameter / Specification | Basis or Remarks |
|---|---|---|
| Executive Standard | JC/T 689-1998 | Industry standard for metal-faced polystyrene sandwich panels |
| Facing Material | Color-coated steel sheet | Thickness 0.4–0.8 mm |
| Core Material | Flame-retardant polystyrene (EPS) | Molded board |
| Core Density | ≥18 kg/m³ | Required for panel rigidity |
| Thermal Conductivity | ≤0.041 W/(m·K) | Measured for EPS core |
| Bond Strength | >0.1 MPa | Higher than typical rock wool or polyurethane panels |
| Flexural Load Capacity | ≥0.5 kN/m at deflection L₀/250 | Meets general envelope requirements |
| Core Oxygen Index | >30% | Per GB/T 10801.1 |
| Combustion Performance | Class B2 (Combustible) | Not suitable for areas with specific fire-resistance requirements |
| Common Thicknesses | 50–250 mm | Custom sizes available |
| Effective Width | 1150 mm / 1200 mm | Standard widths |
The minimum bond strength for polystyrene sandwich panels is specified as 0.1 MPa. By comparison, polyurethane panels require at least 0.09 MPa, and rock wool panels require at least 0.06 MPa. In peel tests, the core material remaining on each facing must be evenly spread and cover no less than 85% of the bonded area. This requirement helps ensure that the facings and core continue to act together during service.
The EPS core has a thermal conductivity no higher than 0.041 W/(m·K). Its closed-cell content is close to 100%, meaning the material contains a large number of independent air pockets that reduce convective heat transfer. A 50 mm panel shows a total heat transfer coefficient of approximately 0.68 W/(m²·K) and weighs roughly 10 kg per square meter.
The flexural load capacity is at least 0.5 kN/m when the deflection reaches L₀/250, where L₀ is the distance between supports. This level is sufficient for standard building enclosure applications. The core density of 18 kg/m³ or higher contributes to the panel's overall stiffness.
GB/T 10801.1 requires the polystyrene core to have an oxygen index above 30% and to meet the B2 combustible classification. Polystyrene sandwich panels are not intended for building parts that require a formal fire-resistance rating. They should be limited to areas with low fire safety demands. When a rated assembly is required, panels with rock wool or polyurethane cores should be specified.
A 50 mm EPS sandwich panel typically provides an average sound insulation of about 40 dB. This level is generally adequate for industrial buildings and storage facilities where moderate acoustic separation is sufficient.
They are generally used in buildings where fire safety requirements for the envelope are low, such as some warehouses, temporary offices, and agricultural structures. For occupied buildings or areas governed by strict fire codes, panels with non-combustible cores are usually required.
EPS panels are lighter and often less expensive, but their B2 fire rating limits their use. Polyurethane panels offer better thermal performance per unit thickness and usually achieve B1 flame retardancy. The right choice depends on fire codes, insulation targets, and budget.
They should be kept dry, covered, and away from heat sources. Prolonged UV exposure can affect the steel coating, and moisture can enter the core if edges are not sealed. Inspect the protective film and packaging regularly.
The steel facings are recyclable. EPS foam can also be recycled or used as a raw material in some processes, but local recycling facilities and regulations should be checked in advance.
Each batch of incoming steel and EPS is checked for thickness, density, and surface condition. Production monitoring covers panel dimensions, adhesive application, and bonding consistency. Before shipment, panels are reviewed for edge quality, facing damage, and package integrity. Reports aligned with JC/T 689-1998 can be supplied, and additional third-party testing is available when required by the project.
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