Adhesives at their best!
In today’s modern production factories, as we know them all over the world, it is desirable, even necessary, to make the individual processes as plannable as possible. Modern 2-K Polyurethane ad- hesives can be adapted very well to the individual requirements of the customers or to their wishes. However, there are influences that have a big effect on adhesives, but which cannot be met by one adhesive alone. One major influence that plays a big role in the predictability of processes is temperature.
One very important adhesive application in modern RV design is the production of sidewall and roof sandwich panels. In principle there are three different adhesive technologies in use. H.B. Fuller is able to serve
all of them. Reactive Hotmelt widely used in the US, Liquid Moisture cure, the main technology in Europe and as a specialty, mainly for big- ger Luxury vehicles, is standard 2-K Polyurethane. Reactive Hotmelt is applied at higher temperatures above 100° C, so the ambient room temperature in production isn’t a big issue. Using Liquid Moisture cure products at different temperatures during the production, cannot be balanced and so customers often use different products to overcome the temperature effect. For the usage of 2-K Polyurethane H.B. Fuller has developed innovative products that can easily compensate existing temperature fluctuations on site.
The curing behavior of adhesives is linked to the ambient temperature. The pot life is determined at a standardized temperature in order to obtain a certain comparability with other adhesives. Or also to have an indication of the curing time in relation to the prevailing ambient temperatures in production. The reaction of polyurethane adhesives is faster at higher temperatures, which leads to a shorter pot life, and correspondingly slower at lower temperatures, which means a longer pot life (see Graphic 1).
Depending on the ambient temperature, the adhesive must be selected accordingly to ensure a certain process time. Since the ambient temperatures are not constant, several pot life variations may be necessary to achieve a safe process in production. To ensure a constant process time, it is necessary to use adhesives with different pot life/curing times. This means storing different pot life variants and deciding which is the most suitable variant for the process depending on the ambient temperature. This is a big challenge in terms of logistics and production technology and can only be achieved with a great deal of effort.
In order to keep the desired process times as short as possible, “HBF” offers the possibility of using the 2-K PU as a 3-K PU. This can be realised in two different ways:
-
by using two A-components with different pot lives. This enables a longer or shorter pot life by premixing a long and a short pot life in different mixing ratios (see Graphic 2);
-
as an alternative to the method described above, an A-component with a long pot life can be used with the standard B-comp and the pot life can be adjusted by adding a third (booster) component (see Graphic 3).
Both of these variants can be adjusted very individually to the desired process times. Thanks to the predefined parameters in the application system, the pot life can also be changed quickly and allows the customer to adapt the production to various processing steps, where different curing times are needed.
Customer’s Results and Benefits:
• High Flexibility
• Elimination of temperature impact
• Compensation of temperature fluctuation
• Constant quality of the PUR-system
• Individual adjustment of the process speed
• Possibility of flexible cycle times
• Low inventory management
This solution has been proven in practice for a manufacturer of sandwich panels. With the use of a 3-K-System that gives him the flexibility to adapt to various situations in the production. For example, the pot life was individually adapted to each sandwich element, which was stacked in the vacuum table for curing. For this purpose, a rather long pot life was first used for the first sandwich panel. For the other panels, the
pot life was adjusted according to the process sequence.
This enables a shorter curing process and thus an optimised process time. It is also possible to produce different sizes of sandwich panels in one process, in which the pot life is adapt- ed to the panel size or to the application time of the adhesive. A longer pot life is used for the large panels and a correspondingly shorter pot life for the smaller panels.
The 3-K poly- urethane systems are also ideal for compensating the fluctuating ambient temperature, which affects the process time. Since very few production halls are heated, they are subject to temperature fluctuations (summer/winter, day/night), which affects the curing of the adhesives and thus the cycle time in production. These conditions can be counteracted by selecting pre-installed parameters on the gluing system. By adjusting the pot life to ambient temperature, a desired process time is achieved, which in turn enables a reliable production process or manufacturing. Whether the client wants to contain temperature fluctuations for his process times or optimise safe, reliable processes in terms of cycle time. The 3-K polyurethane system offers any possibility to do so.
It is H.B. Fullers aim to always focus on the customer’s individual needs and to develop tailor made solutions. Thanks to the many years of experience and the high reputation on the market as a reliable and flexible supplier of adhesives the enterprise is able to offer high-performance system solutions that are individually tailored to the respective situation of the customer on site. H.B. Fuller strongly believes in the importance of long-term business relationships based on partnership and the company supports the customers from the project planning to implementation and beyond.
Company profile
H.B. Fuller
From a one-man wallpaper paste shop in Minnesota in 1887, H.B. Fuller has grown into a $3 billion adhesives global leader today. Its recent acquisition of Royal Adhesives and Sealants, including the KÖMMERLING Chemische Fabrik GmbH business, created a unique powerhouse of RV adhesive and sealant expertise, supplying products for every conceivable RV application.
Kömmerling
Headquartered in Pirmasens, some 170 km south west of Frankfurt, and founded in 1897, Kömmerling is a leading international manufacturer of high-quality adhesives and sealants. In this capacity, it has been supplying the RV industry in Europe and beyond for more than 20 years. It became a member of H.B. Fuller’s global network through the company’s acquisition of Royal Adhesives & Sealants in October 2017.
