We specialize in heat-resistant insulators and fire-resistant insulants.

High-voltage resistant sheet

High-voltage resistant sheets D461 and MCT-BS are made by combining mica paper with epoxy resin. They are used for bulkhead plates (barrier plates) and reinforcement plates in high-voltage equipment.

This insulation material has characteristics that cannot be achieved with Bakelite, glass epoxy laminate plate or various types of FRP. It provides excellent electrical insulation even when the board is thin, and is therefore useful for making insulation materials thinner and lighter. Also, MCT-BS has obtained UL94 V-0.


  1. (1) Excellent corona resistance, arc resistance and tracking resistance, as well as good high-frequency property.
  2. (2) It is easy to process and can be cut or grinded without difficulties.
  3. (3) It is unlikely to warp, and possesses high mechanical strength.
  4. (4) It has excellent resistance to water.
  5. (5) In the field of materials for electrical appliances and electronic devices, it can contribute to weight reduction, flame proofing, and cost reduction.


  1. (1) Electrical insulation bulkhead plates in switch boards
  2. (2) Shield (barrier) for aerial switches
  3. (3) Insulation washers and spacers
  4. (4) Heat-resistant insulation reinforcing plates
  5. (5) Reinforcing plate in liquid crystal protection parts for digital camera cases, etc.

Composition and standard dimensions

Symbol D461 MCT-BS
Mica Mica paper based on uncalcinde muscovite
Binder Epoxy Flame-retardant epoxy
Standard thickness(mm) 0.20~20.00
Standard dimensions(mm) 600×1000


Item Unit D461 MCT-BS
Nominal thickness mm 0.55 0.55
Density kg/m3 2.4×103 2.42×103
Dielectric strength kV/mm 46 40
Insulation resistance Normal Ω 1012 1012
After boiling 1012 1012
Surface resistivity Ω 1012 1012
Permittivity 60Hz F/m 5~7 5~7
1MHz 5~7 5~7
Dissipation factor 60Hz % 0.3~0.5 0.3~0.5
1MHz 0.6~0.8 0.6~0.8
Flexural strength MPa 372~402 372~402
Water immersion Room temperature % 0.02~0.05 0.02~0.05
Boiling(1h) 0.15~0.20 0.15~0.20
Tracking resistance(CTI) V 600 500
Arc resistance S 180~210 180~200
Flammability (UL standard) 94V-1(t1.0 mm or more)
94V-0(t5.0 mm or more)
*Measured in compliance with JIS C 2116 and JIS K 6911.
*The above properties are examples from tests, and are not guaranteed values.