CYMEL® U-663

• Low formaldehyde release 
• Very good early stacking properties 
• High gloss films

To extend catalyzed pot life of the formulation, addition of primary alcohols, such as n-butanol, ethanol, and methanol, is required at concentrations of 10- 25% on total resin solids.

Faster evaporating alcohols will improve speed of dry.

• The CYMEL U-663 resin responds best to strong acid catalysts, like CYCAT® 4040 catalyst.
• Generally, 6-10% CYCAT 4040 catalyst on total binder solids of the formulation is sufficient to obtain fast drying behavior at room temperature

• CYMEL U-663 resin is a very effective crosslinking agent for backbone polymer resins containing hydroxyl functional groups, such as alkyd, polyester or acrylic resins.
• CYMEL U-663 resin has high reactivity and a high tendency for selfcondensation providing fast drying films with good gloss, hardness and block resistance.
• The optimum level of CYMEL U-663 resin in an acid curing wood coating formulation should be in the range of 25-35% on total resin solids.
• To obtain formulations with optimum resistance properties, addition of a melamine resin, such as CYMEL MB-98, at levels of 5-10% on total resin solids is recommended

• CYMEL U-663 resin has a shelf life of 720 days from date of manufacture when stored at temperatures below 32°C.
• Although low temperatures are not detrimental to stability, the viscosity of the product will increase making the resin more difficult to pump or pour.
• Product viscosity can be returned to normal by gentle warming, however, care should be taken to avoid excessive localized heating as this can cause an irreversible increase in viscosity.