Secondary Operations: Adhesive Bonding

Unlike solvents, which evaporate, an adhesive layer remains a functional part of the finished assembly. Therefore, the characteristics of the adhesive layer play a key role in the performance and appearance of the finished part.
 
Consider these characteristics when selecting an adhesive:

• Chemical compatibility with parts being joined
• Aesthetics of the finished joint
• Expansion/contraction with temperature changes (NOTE: if expansion/contraction are a major concern, consider mechanical fasteners.)
• Brittleness, rigidity, flexibility
• Durability/service life
• Adhesive strength (adhesion to the plastic)
• Cohesive strength (resistance to internal tearing)
• End-use requirements

 
Eastman Tritan^™ copolyester offers outstanding chemical resistance and has been studied with many adhesives and different bonding procedures. 
Adhesive bonding procedures for Eastman Tritan^™ copolyester     
When adhesive bonding parts made with Tritan, joining surfaces should:

• Fit well without forcing
• Have no visible gaps
• Be smooth but not polished:
  • Sand the surfaces you wish to bond with a 120-grit or finer paper.
  • Diamond-wheel polishers, jointers/planers, or other mechanical devices can produce excellent results.
  • Do not use soft-polishing wheels or flame polishing, as they can round the edges, creating gaps and improper fit.

 
Before selecting an adhesive system, conduct a careful evaluation of the part application to ensure the adhesive provides both acceptable performance (bond appearance and strength) and that it meets all applicable regulatory requirements. See inset box for several recommendations.
 NOTE: This list of recommended adhesive systems does not include all products have been used successfully with Tritan. For best performance, always follow the guidelines provided by the adhesive manufacturer.
    

Recommended adhesive systems for use with Tritan
Dymax adhesives for medical devices  Henkel adhesives for medical devices  Weld-On® 55* Lord® adhesives 7542 A/B* Flex Welder™ 14345* Lord adhesives 403/19* Lord adhesives 406/19* Lord adhesives 406/17* Plastic Welder® II 14340* *Tested according to ASTM D1002

For details about bonding Tritan to itself and to other materials, contact your Eastman technical representative. For more information about adhesive bonding as well as tips for decorating, painting, overmolding, and other tips, download a free copy of the Secondary operations guide. 
 

TMI TIP: Adhesives that contain a volatile component may shrink while curing. To compensate for shrinkage, cut the joint on an angle, thereby providing space for the joint to be slightly overfilled. Consult your adhesive supplier literature for specific information on shrinkage.