E962F Low-Odor Air-Drying Insulating Varnish for Coils
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Short Product Description:
E962F is a low-odor, air-drying insulating varnish based on modified polyester resin. Designed for transformer, generator, and motor coils, it combines low viscosity, good wetting, strong adhesion, and film flexibility. This solvent-based varnish supports ambient drying or oven drying for coating and impregnation of electrical winding assemblies.
- Description
- Technical Data
- FAQ
Description
Product Overview:
E962F is an electrical insulating varnish developed for coil treatment in medium to large electrical equipment. Its low-odor polyester formulation has a reported viscosity of 16 ± 5 seconds using a Tu-4 cup at 25°C, supporting wetting during coating and impregnation.
After drying, E962F forms a smooth, transparent yellow film that provides electrical insulation and bonds winding components. Strong adhesion helps reduce electromagnetic vibration and associated noise, while film flexibility helps accommodate differential thermal expansion between metal and insulating materials.
This air-drying insulating varnish offers two drying options: ambient drying at 25°C or accelerated oven drying at 110°C. Manufacturers can select and validate the process according to component size, winding structure, and production requirements.
The TDS lists thermal classes B, F, and H and describes temperature resistance from −40°C to 180°C. Suitability for a specific thermal class or operating temperature should be confirmed for the complete insulation system.
Key Features and Benefits：
· Low-Odor Formulation: Designed for applications where odor is a product selection consideration. E962F remains solvent-based and requires suitable ventilation during application and drying.
· Air-Drying Capability: Reaches surface dryness in ≤20 minutes at 25°C, with a reported through-dry time of seven days under the stated conditions.
· Optional Oven Drying: At 110°C, the TDS reports surface drying in ≤5 minutes and internal drying in ≤4 hours, providing an accelerated processing option.
· Low Viscosity and Good Wetting: A reported cup viscosity of 16 ± 5 seconds at 25°C supports wetting of component surfaces during coating and impregnation.
· Strong Adhesion: Helps bond winding and transformer components, reducing electromagnetic vibration and associated noise.
· Flexible Insulating Film: Helps accommodate movement caused by temperature changes and differences in expansion between metal and insulating materials.
· Electrical Performance After Water Exposure: Reported dielectric strength is 132 kV/mm under normal conditions and 116 kV/mm after 24 hours of water immersion.
· Smooth, Transparent Finish: Dries to a smooth, transparent yellow film that allows the underlying surface to remain visible.
Typical Applications：
E962F insulating varnish is intended for coating and impregnation of coils in medium to large electrical equipment, including:
· Large Transformers: Coil insulation and bonding of winding assemblies.
· Large Generators: Treatment of generator coils requiring electrical insulation and mechanical support.
· Electric Vehicle Motors: Insulation treatment of motor coils used in new energy vehicle applications.
· Motor Stator Coils: Coating or impregnation of stator winding assemblies.
· Other Electrical Coil Assemblies: Applications requiring a low-odor polyester insulating varnish with ambient or oven-drying options.
Verify compatibility with wire enamel, insulating materials, and other assembly components before production use.
Physical Properties：
| Item | E962F | |
| Thermal Class | B, F, H | |
| Properties | Specification | |
| Varnish Properties | Viscosity (25℃, Tu-4 Cup) | 16±5″ |
| Specific Gravity (25℃) | 0.950±0.03 | |
| Non-Volatile Content (105℃/3h, %) | 40±3.0 | |
| Appearance | Varnish Appearance (25℃, Visual) | Brown translucent liquid |
| Film Appearance (25℃, Visual) – Film Color Film Appearance (25℃, Visual) – Film State | Yellow, transparent Smooth | |
| Drying Properties | Surface Drying (110℃, min) | ≤5 |
| Internal Drying (110℃, h) | ≤4 | |
| Surface Dry (25℃) | ≤20 min | |
| Full Cure (25℃) | 7 days | |
| Volume Resistivity | Normal State (Ω·m) | 8.5×1013 |
| After 24h Water Immersion (Ω·m) | 2.2×1013 | |
| Dielectric Strength | Normal State (kV/mm) | 132 |
| After 24h Water Immersion (kV/mm) | 116 | |
| Breakdown Voltage | Twisted Pair (TP) Ф=1.0mm AIW (kV) | 16 |
| Film Thickness (mm) | ≥0.05 | |
| Thinner | X-86 series, X-12 series | |
| Shelf Life (at 40℃) | 6 months | |
Technical Notes:
· Viscosity is expressed as cup flow time in seconds, not dynamic viscosity in mPa·s.
· Specific gravity is dimensionless, and volume resistivity is reported in Ω·m.
· Dielectric strength in kV/mm and twisted-pair breakdown voltage in kV represent different measurements.
· Surface dryness does not indicate complete drying within an impregnated winding.
Application Guidance：
· Preparation and Thinning
Use the specified X-86 series or X-12 series thinner when viscosity adjustment is required. Determine the dilution ratio through trials based on component geometry, winding structure, and the selected application method.
Confirm compatibility with the actual wire enamel, insulation materials, and other components before introducing E962F into production.
· Coating and Impregnation
Apply E962F electrical insulating varnish using a coating or impregnation process suited to the assembly. Establish impregnation time and other production parameters through trials on the actual component.
For large transformers and densely wound coils, verify both penetration and drying throughout the winding structure before approving the process.
· Reference Drying Conditions
| Drying Method | Temperature | Surface-Dry Time | Through-Dry or Internal Drying Time |
|---|---|---|---|
| Ambient drying | 25°C | ≤20 min | 7 days |
| Oven drying | 110°C | ≤5 min | ≤4 h |
These values are reference conditions. Actual drying depends on coating thickness, solvent retention, component size, airflow, and oven loading.
When oven drying, account for the time required for the winding assembly to reach the target temperature. Confirm complete drying before electrical testing or service.
Precautions：
· Determine the dilution ratio, baking temperature, and baking time experimentally based on product shape, size, and specific requirements.
· The product may absorb moisture and turn whitish under high humidity; performance remains unaffected after baking.
· This product is flammable; keep away from fire and heat sources.
Packaging, Storage/Transport & Shelf Life：
· Packaging: metal pails, 18 KG/pail
· Storage & transport: flammable chemical — keep away from fire and heat; handle per regulations; store cool (RT), dark and dry.
· Shelf life: stored sealed, 6 months at 5-25℃.
Frequently Asked Questions About E962F Insulating Varnish
1. What is E962F insulating varnish used for?
E962F is a low-odor polyester electrical insulating varnish used for coating and impregnation of coils in medium to large electrical equipment. Typical applications include large transformers, generators, electric vehicle motors, and motor stator windings.
After drying, it forms a smooth, transparent yellow film that provides electrical insulation and helps bond winding components.
2. Is E962F solvent-free or low-VOC?
E962F is a solvent-based, low-odor insulating varnish. Low odor does not mean solvent-free or establish a low-VOC classification.
A VOC content test report is listed in our Insulating Varnish downloads section. Request the report applicable to E962F when reviewing emissions requirements. Suitable ventilation is required during application and drying.
3. How long does E962F take to dry at room temperature?
At 25°C, E962F has a reported surface-dry time of no more than 20 minutes and a through-dry time of seven days under the stated reference conditions.
Surface dryness does not mean an impregnated winding is fully dry. Actual drying depends on coating thickness, winding geometry, retained solvent, and airflow. Confirm complete drying before electrical testing or service.
4. Can E962F be oven-dried to shorten processing time?
Yes. At 110°C, the E962F TDS reports surface drying in no more than five minutes and internal drying in no more than four hours.
These are reference values, not a guaranteed production cycle for every assembly. Account for component heating, oven loading, and solvent removal when establishing the drying schedule, particularly for large or densely wound coils.
5. What thermal class does E962F support?
The E962F TDS lists thermal classes B, F, and H and describes temperature resistance from −40°C to 180°C. Confirm the applicable thermal class for your intended insulation system before selecting the product.
These listings do not establish a continuous operating temperature of 180°C for every finished assembly. Suitability depends on the winding materials, insulation system, and operating conditions.
6. How does E962F help reduce winding vibration and noise?
E962F helps bond winding components, reducing movement associated with electromagnetic vibration and noise. Its flexible film also helps accommodate differences in thermal expansion between metal and insulating materials.
The resulting performance depends on equipment design, varnish penetration, drying quality, and operating conditions.
7. What electrical insulation performance does E962F provide?
The E962F TDS reports dielectric strength of 132 kV/mm under normal conditions and 116 kV/mm after 24 hours of water immersion. Reported volume resistivity is 8.5 × 10¹³ Ω·m under normal conditions and 2.2 × 10¹³ Ω·m after 24 hours of water immersion.
These values describe performance under the stated tests. They should not be used directly as the allowable operating voltage of finished equipment or as proof of suitability for continuous underwater service.
8. Which thinner should be used with E962F?
Use the specified X-86 series or X-12 series thinner when adjusting E962F’s application viscosity. The supplied varnish has a reported cup flow time of 16 ± 5 seconds at 25°C, measured with a Tu-4 cup.
Determine the exact thinner grade and dilution ratio through trials based on winding structure, component geometry, and the selected coating or impregnation process. The cup flow time is not a viscosity value in mPa·s.
9. What should be checked before using E962F on large or densely wound coils?
Verify compatibility with wire enamel, insulation materials, and other assembly components. Establish working viscosity, impregnation time, and drying conditions using representative winding assemblies.
Check both varnish penetration and complete drying throughout the coil. A dry outer surface alone does not confirm that the internal winding structure is adequately impregnated and dry.
10. Why can E962F develop a whitish appearance?
E962F may absorb moisture and turn whitish when applied under high-humidity conditions. The product guidance states that performance is not affected after baking.
Control application humidity and check the finished film’s appearance and drying condition. If whitening occurs during ambient drying, confirm a suitable corrective drying procedure before accepting the component.
11. Is RoHS documentation available for E962F insulating varnish?
RoHS documentation is available through our Insulating Varnish downloads section, alongside an MSDS and a VOC content test report. Specify E962F when requesting documents so the applicable report or declaration and its product coverage can be confirmed.
For X-86 or X-12 series thinners, request documents for the exact grade used. The Thinners section separately lists RoHS documentation and a halogen content test report; these should be reviewed separately from the varnish documents.
12. How is E962F packaged, and what are its storage requirements?
E962F is supplied in 18 kg metal pails. The stated storage guidance gives a shelf life of six months when stored sealed at 5–25°C.
Keep the varnish in a cool, dark, dry location away from fire and heat sources. E962F is flammable; follow the applicable safety data sheet for handling, storage, and transport.
13. What information should I provide when requesting an E962F quotation?
Include your equipment type, winding materials, required thermal class, application method, and available drying conditions. These details help assess compatibility with your production process.
For pricing and delivery, provide the required quantity, destination, and target delivery date. Include any trial-material or compliance-document requirements so availability and the applicable documentation can be confirmed.