CX936 Water-Based Insulating Varnish for Motors & Transformers
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Short Product Description:
CX936 is a low-odor, low-VOC water-based insulating varnish formulated with epoxy resin for motor and transformer impregnation. It combines good wetting and rust-prevention properties with strong adhesion and a smooth, flexible film. Suitable for atmospheric and vacuum impregnation, CX936 can be used as supplied or diluted with water, preferably deionized water.
- Description
- Technical Data
- FAQ
Description
Product Overview：
CX936 is a waterborne epoxy insulating varnish designed for the impregnation of motor windings, transformer coils, and associated electrical assemblies. It uses water as the main liquid carrier, providing an option for manufacturers seeking to reduce reliance on organic solvent thinners.
The formulation combines wetting performance with rust-prevention properties to support the treatment of metal-containing electrical assemblies. After proper drying and curing, it forms a smooth, flexible film with strong adhesion, helping bind components while providing electrical insulation.
CX936 has a specified viscosity of 11–15 seconds using a Tu-4 cup at 25 ± 1°C. The manufacturer recommends using the material as supplied in most applications, with water dilution available when required by the component or process.
Its electrical properties include dielectric strength of ≥70 MV/m under normal conditions and volume resistivity of ≥1 × 10¹¹ Ω·m after two hours of water immersion. These values describe the processed insulating material, not the wet varnish.
CX936 supports both atmospheric and vacuum impregnation. The recommended process combines workpiece preheating, controlled impregnation, a standing period, and oven drying, with a staged baking schedule identified as the preferred option in the TDS.
Key Features and Benefits：
· Water-Based Epoxy Formulation: Uses water as the main carrier and allows viscosity adjustment with water, preferably deionized water.
· Low Odor and Low VOC: Described in the TDS as having low odor and low VOC content, supporting applications where solvent use and workplace odor are important considerations.
· Nonflammable Liquid Formulation: The supplied documents describe the liquid product as nonflammable. This does not constitute a flame-retardancy rating for the cured film or finished equipment.
· Good Wetting Performance: Helps the varnish contact component surfaces during atmospheric or vacuum impregnation.
· Rust-Prevention Properties: Provides a formulation designed for use with metal-containing electrical assemblies where rust prevention is relevant.
· Strong Adhesion and Flexible Film: Forms a smooth, flexible coating that supports bonding within the impregnated assembly.
· Electrical Insulation Performance: Specified dielectric strength is ≥70 MV/m under normal conditions.
· Resistivity After Water Exposure: Volume resistivity is ≥1 × 10¹² Ω·m under normal conditions and ≥1 × 10¹¹ Ω·m after two hours of water immersion.
· Ready-to-Use Processing: Generally recommended for use as supplied, reducing the need for routine dilution.
· Two Impregnation Options: Supports atmospheric impregnation for 5–15 minutes or vacuum impregnation for 3–8 minutes under the reference process.
Typical Applications：
CX936 insulating varnish is intended for:
· Electric Motor Windings: Impregnation requiring electrical insulation, adhesion, and film flexibility.
· Transformer Coils: Insulation treatment of transformer winding assemblies.
· Electrical Winding Assemblies: Applications where a waterborne epoxy formulation and oven-drying process are suitable.
· Water-Based Process Conversion Trials: Evaluation by motor and transformer manufacturers seeking an alternative to conventional solvent-based impregnation varnishes.
Confirm compatibility with wire enamel, insulation paper, metal surfaces, plastics, and other assembly materials before production use.
Physical Properties：
| Test Item | Test Condition | Unit | Specification |
| Appearance | Visual | — | Milky white liquid, free of mechanical impurities |
| Viscosity | Tu-4 Cup, 25±1℃ | S | 11-15 |
| Solid Content | 1 g of varnish in an open aluminum box of 45mm×45mm×25mm, 125℃, 1h | % | 20±2 |
| Drying Time (tinplate) | 105℃ | min | Surface dry: 5-10 Full cure: ≤120 |
| Dielectric Strength | Normal state | MV/m | ≥70 |
| Volume Resistivity | Normal state | Ω·m | ≥1×1012 |
| After 2h water immersion | Ω·m | ≥1×1011 |
Technical Notes:
· Viscosity is expressed as cup flow time in seconds.
· Volume resistivity is reported in Ω·m.
· Electrical performance should be evaluated after the assembly has been fully dried and cured.
Application Guidance：
· Preparation and Dilution
Use CX936 as supplied under normal conditions. If dilution is necessary, add water according to the application requirements; deionized water is preferred.
Mix thoroughly and allow the varnish to stand for approximately 20 minutes before use, as recommended in the TDS.
Determine the dilution ratio through trials. Additional water lowers the working solids content and may change resin pickup, coating build, and drying requirements.
· Workpiece Preheating
Preheat the workpiece at approximately 100°C until it is heated throughout. Allow it to cool to an internal temperature suitable for the process; the TDS recommends placing the workpiece into the varnish bath after cooling to 50–60°C.
These temperatures refer to the workpiece, not a recommendation to heat the entire varnish bath to 50–60°C.
· Impregnation
| Application Method | Reference Impregnation Time |
|---|---|
| Atmospheric impregnation | 5–15 min |
| Vacuum impregnation | 3–8 min |
Select the method and duration according to winding construction and the required penetration. The TDS does not provide a numerical vacuum setpoint; confirm this with the supplier and validate it on the actual assembly.
After impregnation, allow a standing period of 15–30 minutes before baking.
· Reference Baking Options
| Baking Option | Temperature | Reference Time |
|---|---|---|
| Single-stage option 1 | 90–95°C | 3–4 h |
| Single-stage option 2 | 110°C | 2–3 h |
| Preferred staged cycle: stage 1 | 80–90°C | 1 h |
| Preferred staged cycle: stage 2 | 100–120°C | 2–3 h |
For the staged cycle, complete stage 1 followed by stage 2.
Determine the final schedule through trials based on workpiece shape, size, equipment conditions, and the required degree of cure. Provide adequate airflow and exhaust for water removal.
Do not release components based only on surface dryness. Verify drying and curing within the winding assembly before electrical testing or service.
· Bath and Process Management
Prevent contamination by unknown substances, other varnishes, or foreign matter. Maintain consistent dilution and mixing practices, and follow first-in, first-out stock rotation.
When replacing a solvent-based varnish, assess tank cleanliness, equipment compatibility, impregnation quality, and oven performance before changing over production.
Water-Based vs. Solvent-Based Insulating Varnish Advantages and Limitations：
Water-based and solvent-based insulating varnishes can both provide electrical insulation and mechanical bonding. Their practical differences involve the liquid carrier, emissions, handling, drying process, and compatibility with production equipment.
Waterborne electrical insulation products can reduce VOC emissions and fire risk compared with conventional solvent-based formulations. However, these benefits depend on the specific product and do not establish that every water-based varnish performs better in every application.
| Comparison Factor | Water-Based Insulating Varnish | Solvent-Based Insulating Varnish |
|---|---|---|
| VOC and odor | Often offers lower organic-solvent emissions and less odor. Numerical VOC content still requires product-specific data. | Often introduces more organic-solvent vapor and odor. The level depends on solvent type and formulation. |
| Flammability | Water-rich formulations can reduce liquid-handling fire risk. CX936 is described as nonflammable in its supplied documents. | Many products are flammable and require controls for ignition sources, vapor accumulation, and static electricity. |
| Dilution | Can use water when specified. CX936 recommends deionized water if dilution is needed; water quality and dilution consistency matter. | Requires the specified compatible thinner. Solvent selection affects viscosity, evaporation, and material compatibility. |
| Drying and production conditions | Water removal makes temperature, airflow, and humidity important. Dense windings require a validated drying cycle. | Evaporation depends on the solvent blend and process. Products may be air-drying or bake-curing; fast surface drying does not ensure complete internal drying. |
| Wetting and compatibility | Must be evaluated on the actual substrates. CX936 is specifically formulated for good wetting and rust prevention. | Can provide effective wetting, but solvents may affect plastics, wire enamel, or other materials. Compatibility testing remains necessary. |
| Electrical performance | Can provide strong insulation after complete drying and curing. Retained moisture and contamination must be controlled. | Can also provide strong insulation. Retained solvent and incomplete curing can compromise results. |
| Heat and moisture resistance | Depends on resin chemistry and the cured insulation system. Water as a carrier does not automatically mean poor water resistance after curing. | Also depends on formulation and cure. A solvent-based carrier does not automatically provide a higher thermal class or better moisture resistance. |
| Storage | Some formulations are sensitive to freezing and contamination. CX936 must be protected from freezing and stored at 5–25°C according to its TDS. | Storage must account for flammability, solvent loss, temperature, and formulation stability. Shelf life is product-specific. |
| Cleanup and waste | Water-based cleaning may reduce solvent use, but contaminated wash water still requires treatment. | Cleaning often uses compatible solvents, adding solvent handling and waste-management requirements. |
| Overall production cost | May reduce organic thinner consumption, but water quality, drying, equipment changes, and wastewater treatment must be included. | May fit an existing solvent-based line with fewer changes, but thinner use, ventilation, fire controls, and solvent waste contribute to cost. |
Temperature and humidity sensitivity are recognized processing considerations for waterborne coatings; the required controls should be established for the actual varnish and production line. U.S. EPA: Pollution Prevention in the Paints and Coatings Industry
Main Advantages of Water-Based Insulating Varnish
· Potentially lower VOC emissions and workplace odor.
· Reduced reliance on organic solvent thinners.
· Potentially lower liquid-handling fire risk.
· Suitable formulations can provide strong bonding, corrosion protection, and electrical insulation.
Main Limitations of Water-Based Insulating Varnish
· Requires effective water removal and control of drying conditions.
· May require changes to an existing solvent-based production process.
· Water quality, contamination, and freezing protection need attention.
· Lower solvent use does not automatically mean lower total processing cost.
Main Advantages of Solvent-Based Insulating Varnish
· Can fit established solvent-based impregnation and coating processes.
· Offers a range of air-drying and baking formulations.
· Can provide effective wetting, bonding, and insulation when correctly selected and processed.
Main Limitations of Solvent-Based Insulating Varnish
· Many formulations introduce flammable vapors and stronger odor.
· Requires compatible solvent thinners and appropriate exposure controls.
· Solvent compatibility with assembly materials must be verified.
· Solvent removal, emissions, and waste handling add process requirements.
How CX936 Fits the Selection
CX936 is a candidate for motor and transformer manufacturers seeking a water-based epoxy insulating varnish with low odor, water dilution, and documented electrical properties. Its specified dielectric strength of ≥70 MV/m and volume resistivity of ≥1 × 10¹¹ Ω·m after two hours of water immersion provide useful evaluation data.
These figures should not be used to claim superiority over another varnish tested under different conditions. A meaningful comparison uses the same component, insulation materials, test methods, conditioning, and acceptance criteria.
Before switching, compare cured resin pickup, penetration, adhesion, electrical performance, drying time, reject rate, and total cost per accepted component.
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 nonflammable; keep away from fire and heat sources.
Packaging, Storage/Transport & Shelf Life：
· Packaging: metal pails, 18 KG/pail
· Storage & transport: handle per regulations; store cool (RT), dark and dry.
· Shelf life: stored sealed, 6 months at 5-25℃.
Frequently Asked Questions About CX936 Water-Based Insulating Varnish
1. What is CX936 water-based insulating varnish used for?
CX936 is a waterborne epoxy insulating varnish designed for impregnation of motor windings, transformer coils, and associated electrical assemblies. After proper drying and curing, it forms a smooth, flexible film that provides electrical insulation and helps bond winding components.
The formulation also offers wetting and rust-prevention properties for suitable metal-containing assemblies. Verify compatibility with wire enamel, insulation paper, metals, and plastics before production use.
2. Can CX936 replace a solvent-based insulating varnish?
CX936 can be evaluated as a water-based alternative for motor and transformer impregnation. It uses water as the main liquid carrier and generally does not require an organic solvent thinner.
Before changing production, validate tank cleanliness, material compatibility, varnish penetration, cured resin pickup, electrical performance, and oven drying. A successful changeover depends on the complete process, particularly effective water removal from the winding.
3. Is CX936 a low-VOC insulating varnish?
The CX936 TDS describes the formulation as low odor and low VOC. However, the supplied technical data does not state a numerical VOC content, so it should not be described as zero-VOC.
Request the applicable VOC content test report when evaluating project requirements. Provide adequate airflow and exhaust during baking to remove water and process emissions.
4. Does CX936 need to be diluted before use?
CX936 is generally recommended for use as supplied. If viscosity adjustment is required, use water, preferably deionized water, according to the application requirements.
Its specified viscosity is 11–15 seconds at 25 ± 1°C, measured with a Tu-4 cup. Determine the dilution ratio through trials, as added water changes working solids content, resin pickup, coating build, and drying requirements. After mixing, allow approximately 20 minutes of standing time before use.
5. Can CX936 be used for atmospheric and vacuum impregnation?
Yes. CX936 supports both atmospheric and vacuum impregnation. The reference impregnation times are 5–15 minutes for atmospheric processing and 3–8 minutes for vacuum processing.
Select the method and duration according to winding construction and required penetration. The TDS does not provide a numerical vacuum setpoint; confirm this parameter with the supplier. After impregnation, allow a standing period of 15–30 minutes before baking.
6. Should motor windings be preheated before impregnation with CX936?
The CX936 guidance recommends preheating the workpiece at approximately 100°C until heated throughout, then allowing it to cool to an internal temperature of 50–60°C before immersion.
These temperatures refer to the workpiece. They are not instructions to heat the varnish bath to 50–60°C. Validate the preheating and cooling procedure for the actual assembly.
7. What baking schedule is recommended for CX936?
The preferred CX936 baking schedule is a staged cycle: 80–90°C for one hour, followed by 100–120°C for two to three hours.
The TDS also provides single-stage alternatives of 90–95°C for three to four hours or 110°C for two to three hours. Validate the selected schedule according to component size, winding geometry, oven loading, and water removal. Confirm complete drying and curing before electrical testing or service.
8. Do CX936’s tinplate drying times apply to complete motor windings?
No. The reported surface-dry time of 5–10 minutes and full-cure time of no more than 120 minutes at 105°C were measured on tinplate.
These results do not directly establish the drying time of an impregnated motor or transformer. Complete assemblies require a validated baking cycle that accounts for internal moisture removal and component heating.
9. What electrical insulation performance does CX936 provide?
CX936 has a specified dielectric strength of at least 70 MV/m, equivalent to 70 kV/mm, and volume resistivity of at least 1 × 10¹² Ω·m under normal conditions.
These values describe the dried and cured insulating material, not the wet varnish. Finished assemblies should be evaluated after complete drying and curing.
10. Is cured CX936 resistant to water exposure?
CX936 has a specified volume resistivity of at least 1 × 10¹¹ Ω·m after the stated two-hour water immersion test.
This result provides reference data for the cured material’s insulation performance after water exposure. The supplied documents do not specify dielectric strength after immersion or establish suitability for continuous underwater service.
11. Are RoHS and REACH documents available for CX936?
The product’s Technical Data section lists RoHS and REACH documentation, together with an MSDS, a VOC content test report, and a halogen content test report.
12. How is CX936 packaged and stored?
CX936 is supplied in 18 kg metal pails. Its stated shelf life is six months when stored sealed at 5–25°C.
Protect the varnish from freezing and contamination, and store it in a cool, dark, dry location. Follow first-in, first-out stock rotation and check the material’s condition before use.
13. What information should I provide when requesting a CX936 quotation?
Include your motor or transformer type, winding materials, impregnation method, available baking equipment, and required electrical and thermal performance. If replacing a solvent-based varnish, describe your existing production process.
For pricing and delivery, provide the required quantity, delivery destination, target delivery date, and any trial-material or compliance-document requirements.