Comfort, generous leg room and the latest multimedia equipment are a matter of course in modern coaches. However, engine and driving noise reduction is also important in order to make the journey for passengers as pleasant as possible. Sekisui Alveo, manufacturer of polyolefin foams, together with Foam Techniques Ltd. has developed a new insulation system in this respect. The laminate consisting of two foams and a metallised film ensures perfect acoustic and thermal insulation. Alveo-Soft, a soft foam, also compensates for unevenness of rivets and welded seams on the metal floor. This prevents passengers from stumbling on the gangway. The floor insulation is already being used in vehicles of a major European commercial vehicle manufacturer.
The laminate is made of the heavy layer foam Alveolen NFF E, the soft foam Alveo-Soft and a metallised film. The insulation component, which is only 8 millimeters thick, is inserted between the metal structure and a wooden board lying on top. Due to the welded assemblage and rivets underneath the floor panel, small uneven spots may occur on the gangway in the passenger compartment. The film side of Alveo-Soft, which ensures initial thermal insulation, lies facing downwards on the metal. The semiopen cellular foam is perfectly aligned to the floor panel, compensates for unevenness and smoothes the surface. The foam therefore evens out the level differences much better than conventional heavy layer films made of bitumen or EPDM (ethylene propylene diene monomers). The heavy layer foam Alveolen NFF E lies on top of Alveo-Soft and is used for both acoustic and thermal insulation.
"The foam laminate can easily be glued to the wooden floor", says Hans Gallati, Business Unit Manager Automotive at Sekisui Alveo. That's because the upper surface of the heavy layer foam contains an adhesive layer. The principle is the same as an adhesive tape: simply remove the backing film - that's all. The foam acts in this case as a supporting material. On request, however, Foam Techniques will also directly glue the laminate to the wooden floor on top, so that the manufacturer only needs one production step for installation.
In coaches between metal and wooden floor the new laminate of Sekisui Alveo is used. Composition:
- Wooden floor
- Adhesive layer
- Heavy layer foam Alveolen Alveo-Soft
- Metallised foil
- Metal floor
Commercial vehicles, a growth area
"We believe that the commercial vehicle sector offers high growth potential for our applications", says Gallati. "soft, sound, seal" is the motto here: very soft foams for thermal and acoustic insulation. Sekisui Alveo has already supported customers in different projects. The soft foam Alveo-Soft can be used, for example, as a mirror gasket, thus preventing the ingress of air and water. The noise level is also reduced. The advantage of the soft foam for manufacturers is that, unlike other materials, it does not have to be pressed together with great force prior to use. Due to its semiopen cellular structure, it can be used directly and then aligned perfectly to joints and uneven areas. "Especially in the case of transporters, we could easily imagine this application in the mirror triangle", predicts the Business Unit Manager.
Sekisui Alveo AG with head office in Lucerne, Switzerland, develops and produces cross-linked polyolefin foams, which are used in: Adhesive Coating, Automotive, Consumer Goods, Construction, General Converting and Footwear. The solutions are developed in close cooperation with processing companies and manufacturers, and tested and approved in the company's Application Services Laboratory. Sekisui Alveo is owned by Sekisui Chemical Co. Ltd., which, with its globally active subsidiaries, serves approximately 50% of the global market with cross-linked polyolefin foams. In fiscal 2007 Sekisui Alveo and its approx. 470 employees produced 13,000 tons of polyolefin foams, and generated sales of more than EUR 100 million.