Insulating diamond dotted adhesive paper, commonly abbreviated as DDP (Diamond Dotted Paper) within the industry, is a widely used bonding insulation paper in the transformer sector. Its functional principle is ingenious: epoxy resin microdots are arranged in diamond lattice patterns on insulation paper substrates, remaining solid and non-tacky at room temperature for easy cutting and stacking. Upon heating and pressurization, resin microdots melt and flow to bond adjacent layers together, solidifying into robust adhesion after cooling. Compared with fully coated adhesive paper, only approximately 15% of the surface area features resin dots while 85% retains the original insulation paper, resulting in nearly unaffected insulation performance – this core advantage drives its widespread adoption across large transformers.
A large dry-type transformer manufacturer previously used fully coated adhesive paper for copper foil bonding, suffering compromised insulation performance and uneven adhesive layers leading to persistent quality issues. We recommended rhombus dotted adhesive paper, where resin occupies only a small fraction of surface area to preserve original insulation strength while delivering sufficient bonding force. The customer passed all testing and standardized dotted paper into their production processes. Our monthly shipment volume of dotted adhesive paper ranges from 70 to 100 tons, ranking it among our flagship products. Multiple substrate options are available for insulating diamond dotted adhesive paper including DMD substrates, PET film substrates and aramid paper substrates, covering temperature resistance grades from Class F to Class C to meet diverse transformer design requirements.
Specification Parameters
|
Parameter Item |
Technical Index |
|
Finished Thickness |
0.05～0.5mm |
|
Maximum Width |
1600mm |
|
Minimum Slitting Width |
6mm |
|
Temperature Resistance Class |
Class F (155℃) |
|
Resin Dot Arrangement |
Rhombus Lattice |
|
Resin Dot Height |
30～80μm |
Application Fields
- Interlayer bonding and fixation of oil-immersed transformers
- Copper foil insulation layer bonding of dry-type transformers
- Slot insulation fixation of motors
- Interlayer fixation of reactor coils
- All insulation structures requiring dot bonding
Factory Strength
We rank among domestic manufacturers with large production capacity for dotted adhesive paper, equipped with 2 professional dot coating machines delivering a monthly capacity of 200 tons and maximum coating width of 1600mm. The core technical challenge of dot coating lies in consistent resin dot geometry: full, uniform, regularly arranged dots free of connected dots, missing dots or flow smearing. Our dot coating equipment adopts precision numerical control dot dispensing valves with dot diameter error controlled within ±10% and resin dot height tolerance of ±10 microns. The factory covers 2,000 square meters with complete equipment including three-in-one composite machines, polymer laminators, 4 high-precision slitting machines and stamping forming machines, delivering an annual output of 2,000 tons. We independently complete all processes from substrate composite manufacturing to dot coating processing and slitting forming, retaining full control over quality and delivery schedules.
Quality Control
Three core links govern quality control of dotted adhesive paper: substrate inspection, real-time monitoring during dot coating production and finished product performance testing. All incoming substrates undergo breakdown voltage and thickness testing, with unqualified batches rejected immediately. During dot coating production, samples are collected every 30 minutes for microscopic inspection of resin dot diameter, height and spacing, with machine adjustments implemented promptly upon detecting deviations. Before delivery, finished products undergo peel strength and breakdown voltage tests after curing to guarantee both adhesion and insulation performance. Our dedicated testing laboratory is equipped with tensile strength testers, breakdown voltage testers, electrothermal blast drying ovens and glow wire test instruments, with all test data filed for traceability. The company holds ISO9001 certification, and quality control processes strictly comply with national standards.
Customization Capabilities
Insulating diamond dotted adhesive paper offers extensive customization options. Multiple substrate choices include DMD paper, PET film, aramid paper and high-temperature resistant paper suitable for dot coating. Resin formulas are adjustable: fast-curing variants complete curing in only 5 minutes at 150℃ for high-speed production lines, while slow-curing variants offer extended 30-minute operation windows for complex manual processes. Resin dot height is customizable from 30 microns to 80 microns based on your bonding strength requirements. Width ranges from a minimum of 6mm to maximum 1600mm. Flexible supply formats include rolls, sheets and custom-stamped special-shaped parts. OEM labeling is fully supported with packaging and label content customized to your demands. The minimum order quantity is 500 kg, and free small samples are available for testing.
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