Applications
EV & HV Batteries
Cell-to-cell and module-to-module insulation, plus insulation and thermal protection around the ECU. Helps improve safety inside battery packs.
Inverters & Power Semiconductors
For EV/HV inverter sections and around SiC/GaN power modules, applications that require insulation and heat dissipation at the same time.
Motors, Transformers & Capacitors
Motor coil insulation, transformer interlayer insulation, capacitor components, and other applications requiring insulation performance under high temperatures.
Challenges We Help Solve
Balancing Heat and Insulation in EVs & Batteries
Need cell-to-cell insulation and heat dissipation together in a confined space? We help solve battery pack and inverter design challenges.
Maintaining Insulation in High-Temperature Environments
Need insulation performance that holds up under continuous use at 155°C? Suited for motor coils, transformers, and around power semiconductors.
Replacing Existing Materials
Considering an alternative to resin sheet, mica, or ceramic? Achieve lighter weight, better processability, and reduced environmental impact.
Insulation Paper Lineup
Heat-Resistant Insulation Paper (In Development)
A sheet material composed of special heat-resistant fibers and a heat-resistant binder, maintaining insulation performance even at high temperatures. Offers heat resistance equivalent to JIS C 4003 Class F (≤155°C) and flame retardancy equivalent to UL94 V-0.
Key Properties
・Heat class: Class F, ≤155°C equivalent
・Dielectric breakdown strength: 14 kV/mm
・Flame retardancy: V-0 equivalent (UL-94)
Thermally Conductive Insulation Paper (In Development)
A sheet material made from high-thermal-conductivity raw materials and a small amount of binder, dissipating heat through its thickness while maintaining insulation. Suitable for thermal management needs such as around EV/HV inverters.
Key Properties
・Thermal conductivity: 0.8-1.6 W/m·K (pressure-dependent)
・Dielectric breakdown strength: 29 kV/mm
・Flame retardancy: V-0 equivalent (UL-94)
Property Comparison
| Property | Heat-Resistant Insulation Paper | Thermally Conductive Insulation Paper | Notes |
|---|---|---|---|
| Thickness | 0.4 mm | 0.5 mm | — |
| Tensile strength | 15 MPa | 5 MPa | Reference value |
| Compression rate (P=34.5 MPa) | 7 % | 12 % | — |
| Recovery rate (P=34.5 MPa) | 60 % | 53 % | — |
| Surface resistivity | 1.4×1016 Ω | — | JIS K6911 |
| Volume resistivity | 2.2×1014 Ω・cm | 8.4×1014 Ω・cm | JIS K6911 |
| Dielectric breakdown strength | 14 kV/mm | 29 kV/mm | JIS K6911 |
| Heat resistance class | Class F (≤155°C) equivalent | — | JIS C 4003 |
| Through-thickness thermal conductivity | — | 0.8-1.6 W/m·K | ASTM D5470 |
| Flame retardancy | V-0 equivalent | V-0 equivalent | UL-94 |
*The figures above are representative values, not guaranteed specification values.
Why Choose Sekine Seal Industrial
Formulation Expertise
Optimal formulation of special fibers, flame retardants, and binders. We design the functional balance of heat resistance, thermal conductivity, insulation, and flame retardancy to match your application.
Processability & Small-Lot Support
Supports a wide range of secondary processing including pressing, die-cutting, and impregnation. A supply structure that adapts to every development phase, from sample prototyping to mass production.
1,300 Years of Papermaking Technology
Rooted in the traditional techniques of UNESCO-listed Ogawa Washi. An integrated in-house development system covering everything from raw material formulation to papermaking, surface treatment, and 3D forming.
Our Process
Contact Us
Start by reaching out through our contact form with any question, from new product development and joint development inquiries to questions about existing products.
Selecting an Existing Product or Developing a New Formulation
Based on your requirements (application, function, budget, lead time, and more), we propose the specification we believe best fits your needs.
Lab Evaluation
We run a lab evaluation to confirm whether a material meeting your requirements can be manufactured.
Production-Line Trial
We produce trial samples using actual production equipment.
Mass Production & Delivery
We begin mass production and deliver to you.
We Welcome Joint Development & Sample Requests
Feel free to contact us for sample requests, technical consultations, or joint development proposals related to our Heat-Resistant and Thermally Conductive Insulation Papers. RoHS, REACH, and other substance-content documentation is available on request.
Frequently Asked Questions
Q. What is the difference between the Heat-Resistant and Thermally Conductive Insulation Papers?
Both are paper sheets with electrical insulation and flame retardancy, but their design goals differ. The Heat-Resistant Insulation Paper is designed primarily to maintain insulation performance in high-temperature environments, supporting continuous use at Class F, 155°C. The Thermally Conductive Insulation Paper, on the other hand, is designed to dissipate heat while maintaining insulation, achieving a through-thickness thermal conductivity of up to 1.6 W/m·K. It suits applications, such as around EV/HV inverters, that need both insulation and thermal management.
Q. What does “Class F, 155°C” mean?
It is one of the heat-resistance classes for electrical insulation materials defined by JIS C 4003. Class F means a maximum operating temperature of 155°C, a heat-resistance class widely used in motors, transformers, and similar equipment. In testing, this product has confirmed heat resistance equivalent to Class F (a representative value, not a guaranteed specification).
Q. What does “UL94 V-0 equivalent” mean?
UL94 is a flammability test standard for plastic materials defined by UL (Underwriters Laboratories) in the United States. V-0 is one of its strictest flame-retardancy ratings, requiring a vertically mounted specimen to self-extinguish within 10 seconds of the ignition source being removed, with no flaming drips. In testing, this product has confirmed flame-retardant performance equivalent to V-0. Please contact us to discuss formal UL certification for your specific application.
Q. Can you provide samples or small-lot trial production?
Yes. We can provide samples or small-lot trial production tailored to your application and required performance. Customization of thickness, size, and physical properties can also be discussed. Please contact us through our inquiry form.
Q. Can these materials replace our existing insulation material?
We regularly receive inquiries about replacing resin sheet, mica, ceramic, and similar materials. Drawing on the processability (die-cutting, pressing, impregnation), light weight, and design freedom unique to paper sheet, we propose a specification tailored to your application that meets the required insulation and heat-resistance performance.
Q. Do these products comply with environmental regulations such as RoHS and REACH?
Yes, they comply with the RoHS Directive and REACH Regulation. Documentation on substance content and regulatory compliance is available on request.