Automotive adhesives

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Automotive adhesives are adhesives optimized for automotive applications . Body adhesives, window adhesives and surface adhesives are applied differently and must meet different end requirements. That is why different types of adhesive are used.

The Porsche 911 from 1964 weighed 1095 kg and delivered 130 hp. The 2011 Porsche Carrera 911 weighed 1380 kg and delivered 350 hp. In other words, more power and more torsional strength and safety have been achieved despite minimal weight gain. Among other things, the structural bonding enabled the consistent lightweight construction in aluminum-steel mixed construction. This article looks at the different adhesives used in automotive engineering.

Body adhesives

Body adhesives are mostly applied before the cathodic dip painting , must cross this undamaged and only cure in the downstream dryer of the cathodic dip painting at 160–200 ° C. The flow of the applied adhesive is just as undesirable as the flow out of areas that have already been joined. A high washout resistance is essential, especially since very high forces can occur when passing nozzles in the immersion process. High thixotropic properties are required, with structurally viscous and non- Newtonian behavior being typical.

The area of ​​application of the body adhesives defines their ideal elasticity:

Very soft body adhesives ( modulus of elasticity <10 MPa) are mostly used as seals.

Medium - soft body adhesives ( modulus of elasticity : 50–1,500 MPa) are used as elastic linings. These are, for example, permanent connections between outer and inner sheets.

High-modulus, so-called structural body adhesives are used for crash-resistant bonds. “Structural bonding” describes a joining behavior in which substrates are permanently connected with an adhesive in a dimensionally stable manner. In the case of structural bonds, the mechanical load-bearing capacity of the connection exceeds that of the substrates. In the event of a crash, adhesive bonds hold in such a way that the crash-relevant, joined components can perform their function as crash elements. The great hardness (or the high modulus) is achieved, for example, by epoxy adhesives . The typical “brittleness” of epoxides or their low tear strength is prevented in industrial, structural adhesives by adding elasticizing additives. Automotive approved structural adhesives are tested according to DIN ISO 11343.

Window adhesives

Nowadays, windshields take on various functions: After being glued to the body, they make a significant contribution to its torsional rigidity . This would speak in favor of the highest possible modulus of elasticity. However, remaining body torsions must not lead to local glass stresses that would cause glass to break. Last but not least, the windshield acts as a support for the airbag . Without a glass pane, the airbag and the passenger would be catapulted outwards in a head-on collision. After gluing the glass, the car should leave the assembly line as quickly as possible. When repairing broken glass, the end customer wants to be able to drive away his car even faster. A safe drive away time is achieved when the crosslinking of the adhesive is almost complete. Elastic bonds that are crosslinked sufficiently quickly are achieved, for example, with polyurethanes . Window adhesives are tested according to local standards for Safe Drive Away Time.

Surface adhesives

Surface adhesives are used to enable polymer composites and also composites with textiles. Front consoles, roof inserts, seating elements and much more, which are largely made of polyurethane, are glued. That is why the natural affinity of polyurethane adhesives for long-lasting bonds makes a big contribution.

further reading

Industrial adhesives:

  • Everett M Ellestad, Sven-Erik Larsson, Gunnar Nydrén, Casco Nobel: Industrial Adhesives Handbook. Self-published, Fredensborg 1992, ISBN 91-630-1007-0 .

Elastic bonding:

  • K. Diggelmann et al. a .: Elastic Bonding. Verlag Moderne Industrie, Landsberg ad Lech 1998, ISBN 3-937889-35-3 .

Gluing and sealing:

Individual evidence

  1. ↑ Porsche 911: Fight the kilos. In: automobile production. Nov. 2011, special edition, pp. 48–50.
  2. ↑ D. Lootens, U. Rheinegger, JO Schulenburg: rheology viscoelastic body filled adhesives. In: Adhesion. 5/2011, pp. 32-36.
  3. ↑ Martin Linnenbrink u. a .: Semi-structural linings with 2K adhesives. In: Adhesion. 9/2006, pp. 2-6.
  4. ↑ B. Burchard et al. a .: State of the art of hybrid joining. In: Adhesion. 4/2009, pp. 28-33.
  5. ↑ Structural body adhesive in accordance with DIN ISO 11343 ( Memento of the original from June 26, 2012 in the Internet Archive ) Info: The archive link has been inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  @1@ 2Template: Webachiv / IABot / www.sika.com
  6. ↑ Different glass adhesives in comparison ( Memento of the original from June 20, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / usa.sika.com
  7. ↑ Safe Drive Away Time Standard for the USA: FMVSS 212/208
  8. ↑ Liz White: Polyurethanes help Car Makers with Light Weight Parts for E-Mobility. In: Urethane Technology International. December 2011 / January 2012, Vol. 28, No. 6, pp. 21-23.