44087

Epoxy floor coating [India] 

February 21, 2007

We are manufactruing epoxy floor coating systems using 100% solvent free Bisphenol A and cycloaliphatic amine curing agent. I have some peculiar problems faced at various site and the problems are inconsistent in nature even though the formulation is same.

We used a 22000 CPS epoxy resin with curing agent and made a seal coat to cover porosity in epoxy screed mortar base. The first seal coat filled up in the gaps and was very strong and hard. It achieved full curing ( touch dry) in 3 hours. Later when we put the same material on top we found that it started delaminating after 7 days.

I understand that this could be because of early curing of sealer . Pls advise

Raju
Epoxy floor mfg - Pune, Maharashtra, India

How old was the concrete. Did you acid etch and rinse well and dry well?

James Watts
- FL

Yes, this is normal, although the curing seems too rapid. For molecular bonding between coats, the second coat must be applied before the first coat has fully hardened. The first coat is typically dry to the touch but thumbnail dentable (perhaps even slightly tacky as '100% solids' have no solvent to evaporate). If the first coat has cured hard, it must be sanded or abrasive blasted to allow some mechanical adhesion.

Each epoxy has a recoating 'window' (minimum & maximum time interval) which decreases as temperature increases. A typical formulation might allow recoating between 8 and 48 hours from initial coating. As the manufacturer, you must determine proper recoating times at various temperatures for your customers.

Ken Vlach - Goleta, California