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

Insulation sheet

Insulation sheet is made by combining mica paper with silicone adhesive. It has excellent heat resistance and electrical insulation properties. Furthermore, it is unique in a way that it causes very little smoke, odor or gas and the expansion of mica.
Although it is primarily used for insulation boards in electric heating appliances, heating elements and resistors, this product provides excellent workability that enables processing into custom shapes requested by the users, and has been applied to a wide variety of heat-resistant insulators.

Also, this product has obtained UL94 V-0, as well as UL thermal index 746B (D581: Electrical properties 750℃, mechanical properties 450℃, D581A: Electrical properties 760℃, mechanical properties 600℃). (UL File No.E58537)


  1. (1) Causes hardly any smoke or odor when heated to high temperature.
  2. (2) Causes hardly any deterioration of strength or insulation resistance after heating.
  3. (3) Excellent water-resistant properties, showing extremely high electrical insulation in high humidity atmosphere.
  4. (4) High Edge strength which provides excellent workability for winding heater wires, etc.
  5. (5) Easy to perform die-cutting.
    * Die-cutting is possible up to a board thickness of 1.5 mm though it also depends on the product shape. Please contact us for more details as some shapes may be difficult to process.


  1. (1) Supports for heater wires placed in toasters, electric rice cookers, pots, irons, electric iron, hair dryers, etc.
  2. (2) High heat-resistant washers, gaskets
  3. (3) Insulation parts such as circuit breaker and fuse
  4. (4) Insulation protective sheet on circuit boards
  5. (5) Fire spread prevention sheets

Composition and standard dimensions

Symbol D581 D581A
Mica Mica paper based on uncalcinde muscovite Mica paper based on phlogopite
Binder Silicone
Standard thickness(mm) 0.15~1.5
Width × Length(mm) 600×1000


Item Unit D581 D581A
Nominal thickness mm 0.5 1.0 0.5 1.0
Thickness Average mm 0.506 1.007 0.500 1.009
Max. 0.523 1.034 0.516 1.042
Min. 0.486 0.977 0.482 0.981
Density kg/m3 2.07×103 2.08×103 2.03×103 2.04×103
Loss of mass
% 0.65 0.65 0.62 0.63
Flexural MPa 222 199 166 137
Normal 2,000 or more 2,000 or more 2,000 or more 2,000 or more
550℃×1hr 100 or more 100 or more 100 or more 100 or more
Dielectric strength kV/mm 26 26 21 21
Water immersion
% 0.30 0.29 0.28 0.28
*Measured in compliance with JIS C 2116.
*The above properties are examples from tests, and are not guaranteed values.