1035395

Protect and insulate

- Chemically crosslinked, transparent protective varnish based on polyurethane for high performance
- After curing has a high chemical resistance to solvents and aggressive vapors
- Protects circuit boards and surfaces, even in extreme conditions
- Drying time at 20°C: dry to touch in 20 mins., curing: 2...7 days
- Temperature range: -40...+120°C
- Dielectric strength: approx. 130kV/mm
- Directly solderable for repair purposes
 

For small runs and service applications, the easiest way to use URETHAN 71 is from an aerosol can. Spray the product from a distance of 20-30 cm on a dry, and degreased surface. We do recommend Kontakt PCC to remove greasy layers, dirt and flux remains from PCB’s. After usage, purge the valve by spraying the can in an up-side-down position until only propellant escapes. For serial production runs, bulk URETHAN 71 can be applied by brush, by dipping or by spraying. If the mixture, as supplied, is too viscous for existing spraying equipment, a little “Thinner for Urethan 71” (acetone) can be added. The exact mixing ratio must be determined by trial. The product must be properly sealed when being stored. Because URETHAN 71 is susceptible to cross-linking during drying, a coating once thickened can not be made useable again by dilution. At ambient temperature, almost all solvents will be evaporated after 120 minutes. At this stage the coating is sufficiently dry to allow further assemblies to be handled for mounting. The chemical cross linking reactions take several days under ambient conditions. However 90% cross-linking can be achieved after 24 hrs storage at 60°C. URETHAN 71 contains flammable solvents and hence all ignition sources should be removed. Make sure there is good ventilation in the work place. Further information on safety can be obtained from the Safety Data Sheet