Automotive & Transportation
Professional articles

The perfect solution for every requirement - Resistant, durable, and high-quality car interiors due to high-performance adhesives

Close-up of door trim

Close-up of door trim Picture: Jowat SE

Bonding of a loadspace floor

Bonding of a loadspace floor: Carpet laminated on GMPU using a polyurethane hot melt adhesive Picture: Jowat SE

Modern manufacturing processes in the automotive industry would be inconceivable without bonding technology. About 15 kg of adhesive per car are used on average in the production and assembly of the different parts. In automotive interiors alone, adhesives are used in a wide range of applications, each with different requirements. High-performance adhesives from Jowat play a major role in facilitating durable parts with a premium look and feel of the materials.

From instrument panels and centre consoles to side panels and loadspace floors – bonding technology has long become indispensable in the production of interior parts for the automotive industry. The wide range of laminated parts in car interiors is matched by an even wider spectrum of requirements for the used adhesives. High resistance in changing climate tests as well as low fogging and VOC values are key requirements for all interior parts. Adhesion to diverse materials and processing characteristics adapted to different lamination and application procedures are also required. While plastic TPO or PVC foils are laminated in vacuum deep-drawing processes, porous and air-permeable materials like leather and Alcantara are laminated by pressing. Special surface structures such as graining are embossed into the material directly during the lamination process by In-Mould-Graining (IMG). The comprehensive range of adhesive systems supplied by Jowat, the adhesives specialist from Detmold, provides the perfect solution for all requirements in current applications.

Instrument panels and centre consoles
Dashboards and centre consoles are always in the driver’s field of view. A sophisticated look and feel is therefore a major requirement for the parts laminated with different decor materials.
PU dispersions have been tried and proven for laminating bigger parts with three-dimensional geometries and high restoring forces in vacuum deep-drawing. The water-borne adhesives based on polyurethane are used to precoat the substrates and are reactivated by heat after they have dried. These adhesives are characterised by a very fast and high initial strength, a low reactivation temperature in deep-drawing processes, as well as good resistance to solvents, and are therefore frequently used for bonding thermoplastic decor foils.
Polyurethane hot melt adhesives are the product of choice for press laminating porous decor materials like Alcantara and pressure-sensitive composites consisting of genuine leather with a backing of spacing fabric.
Solvent-based PU adhesives that provide the necessary initial strength may be used in manual manufacturing processes without high pressures.

Door trim
Door panels are assembled from several individually laminated parts consisting of diverse material combinations bonded together with different adhesive systems. For instance, armrests with integrated door openers which are laminated by pressing or in deep-drawing processes using PUR hot melt adhesives, plus the interior trim.
Premium parts with a particularly refined and sophisticated surface finish can be laminated with a TPO foil by In-Mould-Graining (IMG). The IMG method facilitates the transfer of a grain structure onto the foil surface during thermoforming. The exposure to high temperatures is a major challenge in this process and requires laminating adhesives with high initial strengths. PU dispersions and PUR hot melt adhesives from Jowat meet those requirements and have been tried and proven in this application.
Reactive polyolefin hot melt adhesives facilitate the lamination of moulded polypropylene parts with TPO composites without a pretreatment of the substrates. Due to the same chemical basis of the materials and the adhesive, the compound does not need to be separated for recycling.

Jowat has developed a new high-performance dispersion which meets the high requirements in manual pre- and repositioning operations of cut-and-sewn leather. The adhesive sticks to the carrier part as well as to the laminating material, and has also become established in manual edgefolding processes due to its high initial strength.

Textile lamination
Textile laminates used for headliners, seats and pillar trim are generally bonded with PUR hot melt adhesives. The high-performance adhesives are characterised by a broad spectrum of adhesion to the different material combinations including leather, plastic foils, foams, or nonwovens. Another challenge: The use of constantly thinner, translucent textile layers means that the adhesive becomes more visible. Adhesives with an increased UV resistance prevent the glue dots from yellowing and facilitate a durable superior appearance of the car interior. The finished textile composites are then bonded to the carrier part with either dispersions or hot melt adhesives, depending on the substrate and the application system.

In the cargo area, weight reduction plays a major role. Trunk components are therefore manufactured from a combination of different materials which are bonded together using powerful PUR and PO hot melt adhesives. In the production of loadspace floors, polyolefin hot melts have been tried and proven for laminating carpets with insulation fleece as well as PP boards with carpets. Polyurethane hot melts impress in edgefolding applications with high restoring forces and are therefore usually the product of choice for laminating 3D-shaped floors made from honeycomb polyurethane boards reinforced with fibre glass. Due to good adhesion characteristics and high heat resistance, reactive PUR hot melts are also used for laminating the retractable cargo shade as well as for wrapping the profiles of the shade box.

Reliable partners for all relevant applications in the manufacture of car interiors, the high-performance adhesives from Jowat for the automotive industry are constantly optimised further. One objective is to develop polyurethane hot melt adhesives for an even wider range of applications. New polyolefin hot melt adhesives for IMG methods are currently also in development at Jowat.
The broad portfolio of adhesives based on different technologies supplies a solution for all established lamination processes in the manufacture of car interiors. In addition, processors are supported by Jowat with technical advisory and an expertise based on many years of experience to meet all current requirements and process parameters.