IS 8570 / IEC 60554
Diamond Dotted Paper HD (DDP-HD)
Diamond Dotted Paper on a high density base, 3 mil to 10 mil, coated with heat-curable epoxy resin for oil-immersed transformer coil insulation.
DDP-HD is our Diamond Dotted Paper produced on High Density Kraft Paper as the base. The heat-curable epoxy resin coating cures under high temperature, binding the electrical conductor into a single rigid unit.
It is available from 3 mil to 10 mil, made to the thickness your specification calls for, for designs that need the bonding behaviour of DDP together with a higher density base.
Key characteristics
- High density (HD) electrical grade base paper
- Heat-curable epoxy resin coating
- Bonds the conductor into a rigid unit at temperature
Applications
- Insulation between coils in oil-immersed transformers
Technical data
Specification
Specification limits for Diamond Dotted Paper HD (DDP-HD), by grade. The same data is in the PDF datasheet.
3HD to 7HD
IEC 60554-3 compliant| Property | Unit | 3HD | 4HD | 5HD | 6HD | 7HD |
|---|---|---|---|---|---|---|
| pH of aqueous extract | – | 6.0–8.0 | 6.0–8.0 | 6.0–8.0 | 6.0–8.0 | 6.0–8.0 |
| Ash content | % | max 1.0 | max 1.0 | max 1.0 | max 1.0 | max 1.0 |
| Electrical strength | kV/mm | min 8.0 | min 8.0 | min 8.0 | min 8.0 | min 8.0 |
| Conductivity of aqueous extract | mS/m | max 10.0 | max 10.0 | max 10.0 | max 10.0 | max 10.0 |
| Grammage | g/m² | 76 ± 5% | 102 ± 5% | 127 ± 5% | 152 ± 5% | 178 ± 5% |
| Thickness (5 sheets) | µm | 76 ± 7% | 102 ± 7% | 127 ± 4% | 152 ± 4% | 178 ± 4% |
| Coating film thickness | µm | 10–15 | 10–15 | 10–15 | 10–15 | 10–15 |
| Density | g/cm³ | > 0.95 | > 0.95 | > 0.95 | > 0.95 | > 0.95 |
| Tensile index MD | N·m/g | min 93 | min 93 | min 93 | min 93 | min 78 |
| Tensile index CD | N·m/g | min 35 | min 35 | min 35 | min 35 | min 28 |
| Elongation MD | % | min 2.0 | min 2.0 | min 2.0 | min 2.0 | min 2.0 |
| Elongation CD | % | min 4.0 | min 4.0 | min 4.0 | min 4.0 | min 4.0 |
| Tear index MD | mN·m²/g | min 5.0 | min 6.0 | min 8.0 | min 8.0 | min 8.0 |
| Tear index CD | mN·m²/g | min 6.0 | min 7.0 | min 9.0 | min 9.0 | min 9.0 |
| Water absorption | mm | min 10.0 | min 10.0 | min 10.0 | min 10.0 | min 10.0 |
| Moisture content | % | max 8.0 | max 8.0 | max 8.0 | max 8.0 | max 8.0 |
| Bond test | psi | min 40 | min 40 | min 40 | min 40 | min 40 |
8HD to 10HD
IS 8570 compliant| Property | Unit | 8HD | 9HD | 10HD |
|---|---|---|---|---|
| pH of aqueous extract | – | 5.0–8.5 | 5.0–8.5 | 5.0–8.5 |
| Ash content | % | max 2.0 | max 2.0 | max 2.0 |
| Electrical strength | kV/mm | min 8.0 | min 8.0 | min 8.0 |
| Conductivity of aqueous extract | mS/m | max 3.0 | max 3.0 | max 3.0 |
| Grammage | g/m² | 200 ± 10% | 225 ± 10% | 250 ± 10% |
| Thickness (5 sheets) | µm | 200 ± 10% | 225 ± 10% | 250 ± 10% |
| Coating film thickness | µm | 10–15 | 10–15 | 10–15 |
| Density | g/cm³ | min 1.0 | min 1.0 | min 1.0 |
| Tensile strength MD | N/15 mm | min 180 | min 180 | min 180 |
| Tensile strength CD | N/15 mm | min 70 | min 70 | min 70 |
| Moisture content | % | max 8.0 | max 8.0 | max 8.0 |
| Bond test | psi | min 40 | min 40 | min 40 |
- Values are specification limits for standard supply. Where a specification has been agreed with you in writing, that specification applies.
- Thickness and grammage are nominal values with the tolerance shown. 1 mil = 25.4 µm.
- This datasheet is provided for information. It is not a warranty that the product is suitable for a particular application: confirm suitability for your design and process with us before ordering.
- Specifications may be revised without notice. Copies are uncontrolled once downloaded or printed; the current revision is published at www.tomoegawaindia.com.
- Batch test certificates can be supplied with every despatch on request.
Revision 01, issued 17 October 2026
