Description
Epoxy Prepreg DMD consists of a three‑layer DMD base (polyester non‑woven / polyester film / polyester non‑woven) impregnated with high‑temperature epoxy resin and pre‑cured to B‑stage so it remains tack‑free at room temperature and cures rapidly under heat and pressure. After final curing in the customer’s process, it forms a rigid, well‑bonded insulation structure with high dielectric strength, good mechanical properties, and low thermal shrinkage.
The material is generally supplied as rolls (typical width about 1000 mm, 50 kg/roll) in standard thicknesses from about 0.16 mm to 0.40 mm, which can be slit or die‑cut for different transformer and motor designs. It is widely used to replace conventional paper/film combinations and vacuum‑pressure impregnation in low‑voltage dry‑type transformer coils, improving production efficiency and short‑circuit strength of foil‑wound windings.
Typical technical data
| Test Report | ||||||
| Product name: Epoxy Prepreg DMD Thickness:0.2mm Test time: 2024.5 | ||||||
| No. | Test performance/project | Unit | Requirement | Test Result | Test Method | |
| 1 | Appearance | / | The surface of the sample should be smooth and free of obvious resin unevenness and impurities that would affect its use. When rolling the sample, the surface should not be damaged due to bonding. The sample has no defects such as folds, bubbles, wrinkles, etc. | Meet requirement | JB/T 10942-2010 GB/T 5591.2-2017 GB/T 1408.1-2016 |
|
| 2 | Thickness | mm | 0.2±0.03 | 0.21 | ||
| 3 | Tensile strength | MD (not bending) | N/10mm | ≥80 | 261 | |
| 4 | Soluble resin | g/m2 | ≥45 | 48 | ||
| 5 | Volatile content | % | ≤1.5 | 0.8 | ||
| 6 | Breakdown voltage (in air) | kV | ≥8 | 12.1 | ||
| 7 | Tensile shear strength | MPa | ≥3 | 3.02 | ||
| 8 | Temperature index | / | ≥155 | Meet requirement | ||
| Test result: Pass | ||||||
| Address:Room 618, YiTian Building, 850 ChengXin Road,Yinzhou,Ningbo,China,315100 | ||||||
Note:The product specifications provided are for reference purposes only. Please refer to the actual product for final specifications. We also offer various sizes and thicknesses to meet your specific needs. For further customization, please contact us.
Application scenarios
Epoxy Prepreg DMD is mainly used as layer and liner insulation for copper or aluminum foil low‑voltage windings of dry‑type transformers, where it is wound together with the conductor and cured to form a tight, bonded insulation system. This improves coil mechanical strength, short‑circuit resistance, and reduces partial discharge risk compared with traditional paper plus VPI processes.
It is also used for slot, wedge liner, phase, and turn‑to‑turn insulation in B–F class motors and other electrical equipment, benefiting from its good conformability before curing and high mechanical and dielectric strength after curing. Additional uses include end insulation, interlayer barriers, and structural insulation components in reactors, chokes, and other dry‑type magnetic devices operating up to Class F temperature limits.
FAQs
1. What is Epoxy Prepreg DMD made of?
Epoxy Prepreg DMD is made from a DMD flexible laminate (polyester non‑woven / polyester film / polyester non‑woven) impregnated with high‑temperature‑resistant epoxy resin and pre‑cured to B‑stage. This structure provides a balance of dielectric strength, mechanical toughness, and resin bonding to conductors after final cure.
2. What is the thermal class of this material?
The material is designed as a Class F insulation, suitable for continuous operating temperatures up to 155 °C according to IEC 60085. It can also be used in systems where B‑class or F‑class insulation is required for motors and transformers.
3. How should Epoxy Prepreg DMD be stored and what is the shelf life?
Rolls should be stored upright in a cool, dry, ventilated area, below about 25 °C and away from fire, heat sources, and direct sunlight to prevent premature curing. Under these conditions, typical shelf life is around 6 months from the date of production, after which re‑testing is recommended before use.
4. What are the typical curing conditions?
For most dry‑type transformer and motor applications, recommended curing conditions are about 130–150 °C for 30–90 minutes depending on thickness and equipment, ensuring complete epoxy crosslinking. Curing is usually carried out in an oven or press after winding or forming to achieve full bond strength and dimensional stability.
5. Which standards and tests are relevant for this product?
Relevant tests typically follow IEC 60243 for dielectric strength, IEC 60093 for volume/insulation resistance, IEC 60250 for dielectric loss, and IEC 60085 for thermal class evaluation. Flexible laminate mechanical performance often references IEC 60641 or IEC 60684 methods for tensile, elongation, and heat‑resistance tests.
6. In which thicknesses and widths is it available?
Common industry thicknesses are about 0.16, 0.18, 0.20, 0.23, 0.25, 0.30, 0.35, and 0.40 mm, with standard roll width around 1000 mm; custom slitting is generally available upon request. Exact sizes can be tailored to transformer foil width, motor slot geometry, and customer processing equipment.
7. Is Epoxy Prepreg DMD environmentally compliant?
Similar Class F epoxy DMD prepregs on the market are produced to comply with RoHS and REACH requirements, and some grades carry UL recognition for insulation systems. SIDA can specify the exact compliance and certification status of its own grade in the corresponding datasheet or declaration of conformity.