IS 8570 / IEC 60554
High Density Kraft Paper
High density electrical grade insulation kraft paper in a thickness range of 3 mil to 10 mil, made to your specified thickness for applications that call for higher density.
High Density Kraft Paper is our electrical grade insulation kraft paper produced to a higher density, for designs that call for it. It is available in a thickness range of 3 mil to 10 mil, made to the thickness your specification calls for.
It shares the process of our standard Electrical Grade Insulation Kraft Paper: 100% imported virgin fibre, de-mineralised process water throughout, dual-ply construction, and offline calendering and supercalendering.
High Density paper is also the base for DDP-HD, our Diamond Dotted Paper with the heat-curable epoxy coating applied to the high density base.
Key characteristics
- 100% imported virgin fibre from Europe and North America
- De-mineralised process water throughout
- Dual-ply (twin layer) construction as standard
- Offline calendering and supercalendering for uniform thickness and density
Applications
- Transformer interleaving
- Bushings
- Distribution transformers
- Power transformers
Technical data
Specification
Specification limits for High Density Kraft Paper, 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% |
| 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 |
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% |
| 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 |
- 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
