06. Sep 2013

Thermal bonding of insulation boards

Category: Building


"Thermobonding“ in high demand – already seven Bürkle systems in operation at customer site

Robert Bürkle GmbH, Freudenstadt, Germany, is further  expanding their area of competence "Systems for insulating material“. Another two systems for the thermal bonding of insulation boards were just sold  recently, thus bringing  the number of Bürkle systems installed at producers and processers of  insulating material to seven worldwide. Bürkle is very optimistic about  the future of this business field, as direct energy expenses will continue to rise at a fast pace, and thus   engineering innovations  for the reduction of energy costs are be in high demand.

The basic characteristic of the thermobonding technology is the bonding or gluing of two board surfaces without adding any additional adhesive or bonding agent. The form- and force-fit  is achieved simply by a thermal process. Thus not only costs for adhesives or bonding agents are saved, also the recycling of the board will be considerably simplified, as the  composite final product doesn’t contain any bonding additives.

Five of the already installed systems are part  of automatic production lines including board feed, processing and bundle stacking. Also the 6th  system - which has now been installed - is integrated in a complete machine line on which EPS insulation boards are finished by thermobonding.

Panels of expanded polystyrene (EPS) are mainly used at facades underneath plaster for the thermal insulation of buildings. The grey panels (color caused by adding graphite) can considerably heat up when exposed to direct sun light during the fitting process, because of their high degree of absorption. Considerable stress in the material is the negative consequence. However, with the thermobonding procedure, a  bright and reflecting EPS layer is applied to the base board, substantially reducing the absorption rate.  Therefore, stress in the material causing  potential negative consequences like material fatigue, distortion or even detachment from the facade are thus a problem of the past.

The 7th thermobonding station is a "stand alone“ machine, with the help of which the Bürkle customer plans to  determine process parameters for different extruded polystyrene (XPS) materials. Also, the client plans to use the XPS panels manufactured on this machine   for the product certification approval process by the building&construction authorities.  The development  machine can be integrated later directly in a fully automatic line for the production of thick XPS boards.

Because of technological limitations, XPS panels can be foamed or produced only up to a maximum thickness of 200 mm. The thicker the final product, the lower the inner homogeneity,  and the more heterogeneous the insulation effect becomes and the more the insulation effect is reduced. In order to meet higher insulation needs, i. e. for thicker insulation panels, the  boards must be doubled up as a consequence. With thermobonding, two or three boards are physically bonded for a final product with a maximum thickness of up to 400 mm – without any bonding agent or adhesive and without any additional glue application machinery.

As a composite XPS panel of three or four XPS boards bonded by thermal bonding provides a considerably higher insulation value than one single foamed board of the same total thickness. In addition to the enhanced product features, there are also economic advantages – such as for instanced savings through reduced consumption of adhesives, which can easily add up to more than 1 million Euros per year for  XPS production at one manufacturer.  Thus the Bürkle thermobonding systems are unrivalled for the production of EPS and XPS insulating boards for many reasons.

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