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About MICA01

Basic Information on Mica

Mica is a natural mineral that is characterized by its thin peeling nature.
In addition, mica has excellent electrical insulation and heat resistance, and is widely used for motor and generation, fire-proof and electrical insulation fields, home appliances, next-generation energy fields, production of new materials, and research and development.

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Mica structure

Mica is a mineral that is mainly composed of silicon (Si), aluminum (Al), magnesium (Mg), and potassium (K).
The structure is formed by many layers of sheet-like frame layers composed of Si, Al (or Mg) oxides and K-ion layers.

Interlayer distance is approximately 1 nm.
This means that mica is a flat and smooth crystalline substance at atomic level.
The structure of this crystalline substance is the key to mica’s thin peeling characteristic.

About MICA03

Types of Mica

From a mineralogical standpoint, mica is classified into roughly six types depending on its composition. However, we will introduce two types used by Okabe Mica Co., Ltd.

  • Muscovite

    Muscovite in particular has excellent electrical insulation characteristics,
    and is therefore used mainly for electrical insulation products.

    Chemical formula KAl2(Si3Al)O10(OH)2
    Color Colorless or light yellow
    Density（kg/m3） (2.6~3.2)×103
    Thermal decomposition temperature
    （℃）    		 600~800
    Weight loss by heating
    （wt%）
    ※900°C-3hr     		4〜5
    Dielectric breakdown voltage
    （kV/0.1mm）    		 18〜25
    Linear thermal expansion coefficient
    （m/m・K）    		 3.6×10-5

  • Phlogopite

    Phlogopite has particularly excellent heat resistance characteristics,
    and is therefore used mainly for heat resistance/fireproof materials.

    Chemical formula KMg3(Si3Al)O10(OH)2
    Color Amber or dark green
    Density（kg/m3） (2.6~3.2)×103
    Thermal decomposition temperature
    （℃）    		 900~1000
    Weight loss by heating
    （wt%）
    ※900°C-3hr     		0.3〜1.0
    Dielectric breakdown voltage
    （kV/0.1mm）    		 15～19
    Linear thermal expansion coefficient
    （m/m・K）    		 5.2×10-5

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Key Properties of Mica

  • 01.electrical insulation

    The layered structure of scale-like particles, which is formed by taking advantage of the "thin peeling" property, provides excellent electrical insulation. When looking at a cross-section of mica, one can see thin flakes layered repeatedly on top another. This structure effectively lengthens the electrical current's path, increasing the insulation distance. As a result, mica has impressive electrical insulation. This characteristic is particularly vital in applications that require long-term electrical insulation. In addition, muscovite has a higher dielectric breakdown voltage than phlogopite; thus, muscovite is mainly used for electrical insulation.

  • 02.heat resistance

    Mica is a natural inorganic mineral. Therefore, it has very excellent heat resistance characteristics.
    Compared to muscovite, phlogopite experiences less weight loss by heating, and is thus widely used for heat resistance.

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Applications of Mica

Mica products can tackle a variety of challenges. Below are a few examples.
Even issues that are difficult to resolve with conventional materials can often be resolved by mica products.

  • 01.Preventing the spread of fire

    Mica has excellent heat resistance and thermal insulation properties, so it can be used as a material to help prevent the spread of fires.

  • 02.High voltage insulation

    With its outstanding electrical insulating properties, mica enables reliable insulation even under high-voltage conditions.

  • 03.Thin and lightweight designs

    Even when processed into very thin layers, mica still fully retains its high insulation performance and heat resistance. This makes it possible to develop products that are both thinner and lighter.

  • 04.Compliance with international quality standards

    By using our mica products, you can achieve overseas quality standards, such as UL standards, that are often difficult to meet with conventional materials.

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Fields where mica is used

Mica, with its electrical insulation, heat resistance, and unique design, is used in a variety of fields.

Heavy electric field（motor / generator）

  • Elevators

  • Trains

  • Power in plants

  • Thermal generator

  • Hydraulic generator

  • Nuclear generator

  • Wind generator

Electric motors and generators for supporting our lives

  • Mica products have been used for electric insulation of industrial electric motors or generators.
    Basic structures of electric motors and generators are similar. Their difference is only whether rotation power is obtained by charging electricity to coils or electric power is obtained by adding rotation power from outside.

  • Because a form of coils is like a turtle shell, it can be insulated only by a tape form of insulation materials.

    →A mica tape may wrap around any shapes, therefore, it may provide an appropriate function.

  • Mica may provide insulation performance that may be resistant to high voltage in electric motors or generators.

    →Mica is used at the pale orange part. Insulation performance may be provided because mica is wrapped around here.
Achievements

Fireproofing / insulation field

  • High-rise building cables

Fireproof and insulation characters of mica may protect people from fire

  • Cables for emergency power circuits of fire fighting/disaster prevention facilities are legally determined to have fireproof performance at 840℃ for 30 minutes. To withstand these severe conditions, fireproof/insulation characters of mica are utilized.
    Okabe Mica’s mica tape for fireproof cables has excellent flexibility and a structure to wrap around cable conductors easily.
    Also, according to use situations for customers, we have achieved to produce a longer tape.
Achievements

Home appliance field

  • Hair dryer

  • Toaster

  • Electric kettle

  • Toilet

Mica used in our daily home electric appliances

  • Mica has excellent heat resistance and electrical insulation characters, which is used for our daily necessities such as a hair dryer, toaster, electric pot, toilet, etc.
    Specifically, mica is used for supports and protective cases of the heater wire that is a heating source.
Achievements

Next generation energy field

  • Hydrogen fuel cells

  • Electric vehicles

  • Lithium-ion batteries

  • Data center

Mica prevents the spread of the fire for lithium-ion batteries

  • Heat resistance property of mica products are also effective to prevent lithium-ion batteries from fire spread.

Features of mica materials for fire spread prevention

  • Okabe Mica’s fire spread prevention materials have excellent heat resistance, heat insulation, and rigidity.
    Also, they have good processability and may be used for highly-flexible designs that are not restricted by their shapes.
    They have enough abilities to prevent a series of fire spread of lithium-ion batteries.
Achievements