What is the effect of a primer with regard to the interaction between adhesive and substrate?
Primers are bonding agents which improve the adhesion of the adhesive to porous or problematic substrates. The primer leaves a film or residual bonding agent on the substrate on which the adhesive can build up better adhesion.
How good is the frost resistance of adhesives and sealants during transport and storage?
Transportation and storage of anhydrous adhesives and sealants based on silicon, hybrid and polyurethane are possible for a limited period. Permanent storage at temperatures below 0°C is not recommended, particularly because processing of "cold" sealants leads to longer curing times and most products are of a harder consistency at low temperatures, as is the case when they are taken from cold storage and processed immediately. “Cold” products should be warmed to room temperature prior to processing.
After complete curing these products are permanently resistant to temperatures below 0°C.
During processing care should be taken that there is no ice, dew, condensation water or any other source of dampness on the seal surfaces, as this functions as a release agent and impairs or prevents bonding of the sealant.
Aqueous adhesives and sealants based on acrylic dispersions, as well as OTTOCOLL® P 270 and the aqueous OTTOFLEX products, are not resistant to frost when unprocessed and during the curing phase and should not be stored or processed at a temperature below + 5°C Some acrylic dispersions are resistant for a limited period and can be transported at -10°C for a maximum of 48 hours. In this context the information provided in the latest technical sheets should be referred to. Longer storage or storage/transportation at lower temperatures causes irreversible frost damage to the acrylic sealant (coagulation).
After complete curing most acrylic dispersions are permanently resistant even at temperatures below + 5°C.