What are the production process and index requirements for Class F DMD prepreg materials?

The production process for Class F DMD prepregs involves the use of polyester films and polyester fibre nonwovens as flexible composites, which are impregnated with heat-modified epoxy resins, followed by a baking process to form the final product. This material is particularly suitable for interlayer insulation of low-voltage coils in dry-type transformers, slot insulation of class F motors, and phase-to-phase insulation, exhibiting good electrical properties, heat resistance, flame retardancy and a long storage period at room temperature. In addition, there is a medium-temperature curing epoxy prepreg consisting of heat-resistant epoxy resin, latent curing agent, dmd polyester composite film and other components, which is particularly suitable for F class transformer low voltage coil foil winding interlayer insulation, with a long storage period, high reactivity, good adhesion of the cured material, shear strength and other characteristics.

The specifications for Class F DMD prepreg materials include, but are not limited to, thickness (0.18±0.02 mm, 0.20±0.03 mm, 0.25±0.03 mm), dosage (220±30 g/m2, 240±30 g/m2, 310±30 g/m2), tensile strength (≥70 N/10mm, ≥80 N/10mm, ≥80 N/10mm in longitudinal direction without bending), and resin content (50 to 80 g/m2), volatile matter content (≤1.5%), soluble resin content (≥85%) and electrical strength, etc.