CYMEL® U-21-510

• The stability of baking enamels containing CYMEL® U-21-510 Resin resin can be enhanced by the addition of alcohols, amines, or a combination of these. Low molecular weight primary alcohols, such as n-butanol, are most effective.
• Recommended amines are TEA, DMEA, or 2-AMP at a concentration of 0.5-1.0% on total binder solids.

CYMEL® U-21-510 Resin may not require the addition of an acid catalyst to the formulation to obtain effective cure. In many instances, the acidity of the backbone polymer in the formulation is sufficient to catalyze the reaction under normal baking conditions (15-20 minutes at 120-150°C). If catalyst addition is required, then 0.5-1.0% of CYCAT® 4040 catalyst or CYCAT 296-9 catalyst based on total resin solids is recommended.

• CYMEL® U-21-510 Resin not only reacts with the hydroxyl and carboxyl functionalities of the other binders in the formulation, but it also has a tendency for self-condensation. Therefore, its practical equivalent weight, on a solids basis, is typically 200-280.
• The resulting films are harder and more resistant to chemical attack with increasing levels of CYMEL® U-21-510 Resin, but they may also be more brittle. The optimum level of the resin in a given formulation should be determined experimentally.

• CYMEL® U-21-510 Resin has a shelf life of 12 months from the date of manufacture when stored at temperatures between 5°C and 30°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.
• CYMEL® U-21-510 Resin viscosity can be returned to normal by gentle re-warming; however, care should be taken to avoid excessive localized heating as this can cause an irreversible increase in viscosity.