Xuchang Chengrui
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Epoxy Resin Diamond Dotted Paper (DDP)
Diamond dotted insulation paper or epoxy diamond dotted paper is made of electrical insulating paper coated with heat-curable epoxy resin, the epoxy adhesive is applied to both sides of the paper in a diamond pattern consisting of 9.5mm x 9.5mm diamonds with 15.9mm center spacing.
Additional Information
Type: Insulation Paper
Thickness: 0.08mm, 0.13mm, 0.15mm, 0.17mm, 0.20mm, 0.25mm
Width: 960mm, 1000mm or customized
Color: Natural
Insulation class: A (105 °C)
Application: Insulators, Electrical Winding Insulation, Winding Wire Coating Insulation, Electrical Base, Shell, Motor, Switch Baseplate
Epoxy Resin Diamond Dotted Paper (DDP)
Diamond Dotted Paper (DDP)
Diamond dotted paper(commonly abbreviated as DDP) is a specialized composite insulating material engineered for oil-immersed transformer coils and windings. It is manufactured by printing a heat-curable, B-stage epoxy resin onto high-purity electrical kraft paper. The resin is precisely applied in a distinct diamond-shaped dot pattern on either one or both sides of the base insulation paper.
During the transformer drying process, the printed epoxy resin melts at a specific temperature, polymerizes, and cures, forming a rigid bond that locks adjacent winding layers together into a solid mechanical structure. This unique patterned coating ensures optimal bonding strength while leaving the remaining uncoated cellulose paper exposed for maximum dielectric oil impregnation and heat dissipation.
Technical Specifications & Parameters
Base Material Basis: 100% Unbleached Electrical Kraft Paper
Adhesive Type: B-Stage Heat-Curable Epoxy Resin
Nominal Thickness: 0.08mm, 0.13mm,0.18mm, 0.20mm, 0.25mm
Number | Index | Unit | Standard | |
| 1 | Thickness tolerance | mm | 0.08±0.005 | |
| 2 | Density | g/cm3 | 0.85~1.10 | |
| 3 | Adhensive thickness of single side | μm | 10~15 | |
| 4 | Water content | % | 4.0~8.0 | |
| 5 | Oil absorbency | % | ≥20 | |
| 6 | Adhensive strength | Ordinary state | kPa | ≥650 |
100oC±2oC | ≥400 | |||
| 7 | Pollution for transformer oil | - | Pollution-free(tan∮<0.001) | |
Diamond Dotted Paper Features
1. Kraft paper, 100% sulfate pulp
2. High purity and mechanical strength
3. Baked enamel coating: Epoxy resin, rhombic, one or both sides
4. Good compatibility with liquid dielectric after the baked enamel coating has hardened.
5. Care should be taken that the layers to be baked remain closely pressed against each other during baking time
Applications in Electrical Manufacturing
Where is diamond dotted paper utilized?
Oil-Immersed Distribution Transformers: Serving as the premier layer insulation for high-tension and low-tension winding coils.
Power Transformers & Reactors: Providing structural and dielectric reinforcement for heavy-duty power grid components.
Automated Foil Winding Machinery: Ideal for high-speed automated winding production lines due to its high tensile strength and predictable curing behavior.
Frequently Asked Questions
Q1: What is the purpose of the diamond pattern on DDP insulation paper?
The diamond pattern allows the epoxy resin to provide high mechanical bonding while leaving sufficient bare paper surface. This bare surface allows air and moisture to escape during vacuum processing and ensures transformer mineral oil can completely impregnate the paper, preventing destructive partial discharges.
Q2: What is the required curing profile for diamond dotted paper?
A: B-stage epoxy resin typically begins to soften and flow at around 90°C and achieves full polymerization and curing when held at 120°C to 140°C for 2 to 4 hours. Exact curing schedules can be optimized depending on the overall thermal mass of your transformer winding assembly.
Q3: Does Chengrui offer customized roll dimensions and single-sided DDP?
A: Yes. We supply DDP with either single-sided (SDDP) or double-sided (DDDP) resin patterns, and we also offer thermally upgraded diamond dotted paper
Contact Directly With Our Agents
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- Phone +86-15939981307
- Email inquiry@chrcn.com
- Location Xingye Road, Dongcheng District, Xuchang City, Henan Province, China
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