Typical Formulation Ingredients
Ingredient
Parts by weight
Modified epoxy resin (EPON 8132, Momentive)
DGEBA resin (EPON 828, Momentive)
Fumed silica (Cab-O-Sil M5)
Amidoamine (EPI-CURE 3055, Momentive)
Typical Properties
Gel time, min, at 25°C, 100 gm
Thin film setting time, hr
Tensile shear strength, psi, after 7 days at 25°C on:
• Polyethylene terephthalate
Tensile shear strength, psi, after 30 min cure at 140°C on:
• Polyethylene terephthalate
Glass transition temperature, °C
Resulting Properties
The formulation above shows moderately flexible epoxy resin formulations that can be used for bonding difficult plastic substrates including PVC. The main problem of bonding to flexible PVC is due to the plasticizer in the compound. Plasticizer migration from the vinyl into the adhesive bondline can degrade the strength of the joint. Adhesives must be tested for their ability to resist the plasticizer. Certain epoxy adhesive formulations such as those above have been found to provide excellent adhesion to flexible PVC substrates.