For manufacturers who seek to produce the best-looking panels, reduce waste and imperfections, and save precious time during the production process, there are clearly several benefits of using H.B. Fuller’s low-foaming technology adhesives. With its depth of experience in the caravan and motorhome sector, manufacturers can switch to using H.B. Fuller’s low-foaming technology adhesive with the greatest confidence of its total support. Words John Rawlings
As manufacturers use more composite alternatives to wood in floor, wall and roof panels to reduce the effects of any water ingress, some have encountered a new issue of CO2 getting trapped and causing bubbles to be Company news H.B. FULLER visible, particularly on side walls. The main issue of the switch from EPS to XPS is that XPS is a less porous material than EPS so it doesn’t release the CO2 as readily as EPS. In response to this issue, H.B. Fuller has developed a solution using a new range of adhesives using LMC (Liquid Moisture Curing) and low-foaming technology.
Production and quality issues
As a leading manufacturer and supplier of adhesives used in the manufacture of caravans and motorhomes, H.B. Fuller works closely with several manufacturers in Europe. From listening to customer feedback, and closely monitoring industry trends, H.B. Fuller knows that the switch from using wood for battens, particularly in side walls, to composites (with high density of foaming PV of PU or PP), is that the release of the CO2 has become less easy than before.
Also, as XPS has a thinner skin on top, it is not always very easy to get good adhesion. Before, EPX was much easier to bond.
The CO2 needs to escape or the excess CO2 can result in problems during the pressing process that negatively affect the external appearance of caravans or motorhomes. This adversely affects the external appearance of the vehicle (and potentially its resale values) and not only causes negative customer satisfaction issues, but could also damage the reputation of the manufacturer.
The solution: LMC low-foaming technology
CO2 is created as a by-product of the chemical reaction between the polyurethane adhesive and water. To solve the issue of CO2 forming as a micro foam and not being released the experts at H.B. Fuller developed low-foaming technology for a new adhesive product.
Using the same amount of this glue generates considerably less micro foam, so the risk of trapping excess CO2 during the process of making a sandwich panel for a caravan or motorhome is drastically reduced.
H.B. Fuller is already supplying some leading European brands with its low-foaming adhesive but has found that some manufacturers are not aware of it yet, while some are nervous about changing from an existing adhesive product from H.B. Fuller.
Benefits of low-foaming technology
In addition to the improved quality and aesthetics from reducing the risk of unwanted defects in body panels, using low-foaming technology adhesive also has other benefits for the manufacturing process.
Usually, with the standard process, the excess foam has to be cleaned from the press after each panel is pressed to reduce the risk of imperfections in the next pressing; but with the low-foaming alternative the press needs much less cleaning, and the nozzles are also cleaner, so valuable time is saved during the production process.
During the production process, once the press is closed the CO2 cannot escape, so some wait as long as possible before shutting it, but the longer the press is open, the lower the quality can be; however, with the low-foaming adhesive it can be closed immediately – another opportunity to save time and reduce the risk of imperfections.
In addition, when using LMC low-foaming technology, the pressing process also requires considerably less pressure. Usually, a good quality sandwich panel requires around 0,3 to 0,5 bars (3 to 5 tonnes/m²). Less pressure improves the look of the panel as there is less chance of the frames in the panel showing through. Another advantage of low-foam technology is that it is possible to glue the PVC floor at the same time while making the sandwich panel. With standard adhesives, this is usually a two-step process with the sandwich panel of the floor made first, then the bonding of the PVC floor carried out later in the second stage. Today, the use of a low-foaming LMC glue allows the panel to be made and the PVC floor to be glued directly to the PU line at the same time, thus eliminating the second step using an acrylic adhesive generally applied manually with a roller.
Testing, testing…
To demonstrate the strong adhesion of the low-foaming technology adhesive, in tests H.B. Fuller removed the GRP outer layer to show the more extensive area the adhesive has covered compared to the standard LMC.