Page 309 - Handbook of Adhesives and Sealants

Primers and Adhesion Promoters 273

Isocyanate Terminated Urethane, Adhesion to Aluminum

1. urethane is Adiprene L-100 (DuPont)
2. substrates degreased and etched
3. most commonly recommended for pot life
Figure 7.5 Effect of silane addition to an isocyanate terminated urethane adhesive. 27

enhance the wet strength of water borne adhesives and sealants. 33
Conventional silanes are limited to high solids and solvent adhesive
and sealant applications in which moisture is not encountered until
use.

7.3.2 Titanates, zirconates, and others
While silanes predominate as coupling agents, the use of titanate, zir-
conate, and other agents are growing. These coupling agents also al-
low increased impact strength and other physical properties in com-
posites and highly filled plastic compounds. Like the silanes, they
react with surface hydroxyl groups, but there is no condensation po-
lymerization to produce a polymer network at the interface. Adhesion
promoters based on titanium and zirconium have been used to im-
prove filler-polymer adhesion and to pretreat aluminum alloy for ad-
hesive bonding. 37
Titanate adhesion promoters can provide a dual function of improv-
ing processability and bonding. Titanates have been used predomi-