PU Sandwich Panel Fineagles Fineagles -

A sandwich panel is a structure made of three layers:

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• Core
• Two side skin

Sandwich panels are used in applications where a combination of high structural rigidity and low weight is required. The following is the list of the applications whereby sandwich panel is used:

• Cold Storage
• Pack Houses
• CA Chambers
• Ripening Chambers
• Freezer Rooms
• Clean Rooms
• Control Rooms
• Insulated Roofs
• Wall Claddings
• Partition
• Prefabricated Houses and shelters
• Portable Cabins
• Health Centers and Schools, Stadiums, Warehouses
• Communication Shelters
• Insulated Sheds
• Sub Zero Temperature Areas

PU Sandwich Panel:

Polyurethane rigid foam is the core in these kinds of panels. A special feature of polyurethanes is their method of production. Generally, metering and mixing four or more streams of liquid components containing polyurethane precursors at the processing stage produce polyurethanes. Thus, the final, high molecular weight polymer is normally manufactured by the manufacture of Sandwich Panel who has a PU sandwich panel production line. In the production line of sandwich panel, one section is dedicated to performing this process, called &#;PU Foaming Machine&#; or &#;Metering Machine&#;.

Polyurethane has been used as a considerably suitable thermal insulator since . Holding very high insulator properties, Polyurethanes result in energy-saving and consequently related charges up to %60. Since the use of fossil fuels gives birth to about %80 of the world&#;s carbon dioxide (CO2), therefore, use of polyurethane can be a suitable method for reducing energy consumption and, as a result, reduced CO2 gas as one of the most principal causes of global warming. Moreover, polyurethane insulator while holding higher efficiency in thermal insulation, it is considered lightweight and cost-effective compared to other thermal and cold insulators.

There might be questions about resistibility against fire; which is explained by the fire resistance rate. The fire-resistance rating means the duration for which a passive fire protection system can withstand a standard fire resistance test.

Tests according to DIN -1, fire behavior of building materials and building components. Classification of building materials according to EN -1:

• A Class: non-combustible materials &#; Test according to DIN EN ISO (non-inflammable classes)

&#; A1 Class: without organic content,

&#; A2 Class: with organic content

• B Class: combustible materials (such as textiles, furniture, and other interiors)

&#; B1 Class : Flame Retardant

&#; B2 Class: Normal Flammability (self&#;extinguishing)

&#; B3 Class: Easily Flammable (not usable in Industrial Buildings)

In most countries, the PU of the Sandwich panel must pass the classification of B2. The purpose of the test according to DIN -1: -05 section 6.1 is the classification of building materials (except floor coverings) on the basis of their fire behavior. The classification of polyurethane foam in a polyurethane sandwich panel is determined by the raw material used in the foaming machine when manufacturing rigid PU foam.

A sandwich panel with polyurethane typically consists of two sheets. The sheets could be PPGI (pre-painted galvanized iron, also known as pre-coated steel, coil coated steel, color coated steel coated by a hot dip zinc substrate), PPGL (pre-painted Galvalume iron, coated by a hot dip zinc substrate),  Aluminum sheets, and paper foils. The sheets are formed or in other words grooved as required by The Roll Forming Machine.

There are two production lines for manufacturing PU sandwich panels:

Manufacturing sandwich panel methods are mentioned above whereby machinery for manufacturing sandwich panels has significant differences.

In the continuous PU Sandwich Panel Line, the speed of production is almost 10 times more than the discontinuous PU Sandwich Panel Line. Furthermore, manpower required would be significantly reduced when using continuous PU Sandwich Panel machinery. In the Continuous Sandwich Panel, Line Rock wool sandwich panel can also be manufactured by extending the equipment.

PU Sandwich Panel Sizes and Types:

There are different types of PU sandwich which can be manufactured with both continuous and discontinues sandwich panel line:

• PU Wall Panel for Cold Rooms
  Typical Size of Cold Room Sandwich Panel: 120, 150, 170, 200 mm
• PU Roof Panels
  The number of Grooves can be selected / Typical Size of Roof Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120 mm
• PU Wall Panels
  Typical Size of Wall Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120, 150, 170, 200 mm
• Secret Fix Panels (hidden screw sandwich panel, boltless sandwich panel, and hidden joint sandwich panel)
  Typical Size of Secret Fix Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120, 150, 170, 200 mm
• Solar Roof Panels
  Typical Size of Roof Sandwich Panel: 40, 50, 60, 70, 80, 90, 100, 120 mm
• Duct Panel
  Typical Size of Duct Panel Sandwich Panel: 20, 30 mm
• Board Panel
  Typical Size of Board Panel Sandwich Panel: 20, 30, 40, 50, 70, 100, 120, 150, 200 mm

Weight And Length Of PU Sandwich Panel

The two factors which determine the sandwich panel weight are:

1. The thickness of skin, previously mentioned that the sheets could be PPGI (pre-painted Galvanized iron, also known as pre-coated steel, coil coated steel, color coated steel coated by a hot dip zinc substrate), PPGL (pre-painted Galvalume iron, coated by a hot dip zinc substrate),  Aluminum sheets and paper foils.
2. The density of PU foam produced by metering or foam machine in the sandwich panel production line.

The length of the sandwich panel produced by continuous sandwich panel production depends on the usage requirements which could be a minimum of 0.5 meters to 22-meter long. Yet, sandwich panels are normally produced less than 12 meters for easier transportation and avoiding over-length cargo.

How Much Does It Cost?

The two main factors which determine the sandwich panel prices:

• The thickness of the sandwich panel
• The type and thickness of the skin

Therefore, the price of the sandwich panel will be different with every single specification and request. There is of course one more factor in sandwich panel prices; the country in which sandwich panel is produced. The raw material of sandwich panel could be available in some countries, so sandwich panel manufacturer can easily access the raw material, and sandwich panel might be lower in those countries whereas in some countries raw material for sandwich panel production might be imported (associated import cost to be added) and locally not available. As a result, the sandwich panel price will be higher.

Thermal Insulation of PU Sandwich Panel: 

Thermal Transmittance or K-value is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure. The units of measurement are W/m²K. The K-value is determined by the thickness of the sandwich panel.

The below chart shows an example of approx. weight and K-value of the sandwich panel where 40 ± 2 (kg/m³) density of sandwich panel is considered consistent and PPGI for both sides of PU foam is 0.5 mm.

The thickness of the Sandwich panel line (mm) 40 50 60 80 100 120 150 200 Weight of Sandwich Panel  (kg/m2) 10.1 10.6 11 11.9 12.8 13,4 14.7 16,8 Thermal Transmission K-Value of Sandwich Panel (w/m2 K) 0.52 0.43 0.35 0.27 0.21 0.18 0.14 0.11

Comparing 30 mm PU Sandwich Panel with Other Materials in Equivalent:

 

Following is the List of Advantages of Sandwich Panels:

• Lightweight (resulting to save and use less material in buildings and reduced total costs)
• Low heat transfer coefficient
• Fire resistance class of B1 and B2 Low
• Installation cost
• Moisture insulator
• Sound insulator
• Appropriate mechanical features (against shear, tensile, and pressure forces)
• Low energy consumption (cooling and heating cost-effectiveness)
• High resistance against microbial and biologic contamination
• Product appearance and various color options

WHAT

What is EPS? Expanded Polystyrene (EPS) is a rigid cellular plastic found in a multitude of shapes and applications. Most commonly, EPS is used to make things like fish boxes, packaging for electrical consumer goods, and insulation panels in buildings.  

What is PUR? PUR (Polyurethane) is a closed-cell foam core. When cured, the foam becomes chemically inert and will not outgas any harmful chemicals.

Link to Wiskind New Materials

BOARDS

PUR

·        The boards are nominally 12mm thick and these are bonded to the PUR.

·        The adhesive used to bond the OSB with the PUR is Phenol Formaldehyde (PF). PF is a thermosetting adhesive that produces a Type-A bond that is durable and permanent under conditions of full weather exposure, long-term stress, and a combination of both. Formaldehyde-based resins have been well-proven and documented as an adhesive in the wood industry for over 70 years. An important thing to note is that there is more formaldehyde naturally occurring in many foods, such as apples and onions, or the human blood (3 ppm), than in a home built with SIPs.

·        Unless otherwise specified, all framing timber used is a minimum structural grade SG 8 Radiata pine following the NZ Building Code.

·        The timber framing is treated to meet the requirements of H1.2.

·        The OSB boards are manufactured in Kaitaia.

·        PUR panels can also be made of ply (although this will cost more than OSB).

EPS

·        The timber used on the outside of our panels is Oriented Strand Board (OSB) which is manufactured from natural wood fibres. All the OSB used in our panels comes from Sustainable Forestry Initiative managed forests.

• OSB used in our panels utilises 90% of the useable timber from the source tree. Compare this to under 25% utilisation in timber framing.

 

R-VALUES

R values are the measure most used to determine a material's ability to resist the transfer of heat. The higher the "r value", the better thermal resistance the product will provide. This is what to use when looking for the best insulation products or, in our case, the best structural insulated panels for your home.

The following are the r values for our EPS and PUR panels (any of these thicknesses can be used for walls, roofs or flooring. Please see the map below table for an explanation of climate zones):

 The R-value of our PUR panels shows the value of an average panel at manufacture, and the thermal performance over the intended lifetime of the product (typically at least 50 years) reduces to no less than 115mm R3.7, 165mm R6 and 215mm R8.

PROS AND CONS

Thermal Performance

PUR has a higher initial R-value for SIPs, but for NZ conditions, the R values of EPS are still very high, particularly when combined with the inherent airtightness achieved by SIP construction (airtightness trumps R-value). After around 2-5 years, PUR can experience a decrease in r-value due to &#;thermal drift&#; resulting in the r-value being the same as EPS.

Workability

PUR panels from NZSIP are delivered to the site pre-cut. EPS panels, however, may require some cutting with a hot knife (which gives off a toxic &#;smoke&#;) when arriving on site.

Spans

PUR has higher creep deflection than EPS, so it cannot span as far. Creep deflection is where a loaded member moves gradually over time; something all plastics are prone to. While initially providing higher strength values, the gradual movement in PUR means engineers cannot specify as long a span with PUR SIPs.

Cost

PUR SIPs are more expensive than EPS SIPs because the PUR panels come with the timber pre-inserted inside the panel. EPS SIPs provide an allowance for the timber that is inserted on-site.

Fire

PUR is a thermosetting plastic, so it doesn't melt. EPS does melt when it gets hot enough but pulls back from the source of heat/flame and forms a hard skin.

Eco

·        PUR is a thermosetting plastic, which means once it has been used in a panel, that's it. An EPS core, on the other hand, can be recycled for other uses later, should the need ever arise (however, we think that the chances of anyone needing to recycle their house are almost zero!). 

·        Due to the non-sagging, water-phobic and adhesive qualities of PUR SIPs, they perform at optimal levels for the life of the building.

·        The R-Values of PUR panels are significantly higher than EPS panels.

·        EPS panels come in 5 sizes as opposed to PUR panels which come in 3.

·        The OSB for the PUR panels are manufactured right here in New Zealand, so not only is this beneficial to the economy but it also means no shipping delays. PUR panels can also be made with NZ-made ply instead of OSB if the client prefers (however, ply does cost more). The OSB for the EPS panels come from overseas but the SIPS are assembled in NZ.

We hope this article has helped demystify any questions you may have had about the difference between EPS and PUR SIPs. If you have questions or would like to discuss your project with us, please feel free to get in touch with us:

If you want to learn more, please visit our website PUR Sandwich Panel.