Knowing how mica is used through illustrations
Okabe Mica in numbers
Mica, also called isinglass, 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
power and power generation, fire and insulation fields,
home appliances, next-generation energy fields,
production of new materials, and research and development.
Taking advantage of this thin peeling feature,
the "mica splittings" product, bonded with mica flakes, was the mainstream product of Okabe Mica.
Power in plants
Home electric appliances
Hydrogen fuel cells
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.
Mica has a structure that connects a sheet-like frame layer formed by a chemically-strong covalent bond with a K-ion layer using a relatively-weak ion bond. Therefore, it can be peeled apart thinly as a sheet form.
What is an advantage of mica’s thin peeling characteristics?
For example, a cake-like structure.
Top view of pulverized mica
Side view of pulverized mica
Mica after paper making
Microscopic sectional image of mica paper
Mineralogically, mica is classified into about six different types depending on
Okabe Mica uses two types of mica, muscovite and phlogopite.
Muscovite in particular has excellent electrical insulation characteristics,
and is therefore used mainly for electrical insulation products.
Phlogopite has particularly excellent heat resistance characteristics,
and is therefore used mainly for heat resistance/fireproof materials.
Muscovite (origin of India)
It has particularly excellent electrical insulation characteristics.
Phlogopite (origin of Sri Lanka)
It has particularly excellent heat resistance characteristics.
|Color||–||Colorless or light yellow||Amber or dark green|
|Density||kg/m3||(2.6 to 3.2) x 103||(2.6 to 3.2) x 103|
|Thermal decomposition temperature||℃||600 to 800||900 to 1000|
|Weight loss by heating
|wt%||4 to 5||0.3 to 1.0|
|Dielectric breakdown voltage||kV/ 0.1 mm||18 to 25||15 to 19|
|Linear thermal expansion coefficient||m/m·k||3.6 x 10-5||5.2 x 10-5|
Why do mica products have such electrical insulation characteristics?
The answer lies in its layered squamous particle structure, which is formed by utilizing its thin-peeling characteristics.
Look at a cross section of mica products. Thinly-peeled squamous mica are repeatedly layered.
This has the effect of lengthening the path of electricity flow.
This allows a longer insulation distance and leads to further improvement in its electrical insulation characteristics.
In case long-term electrical insulation is needed, it provides a significant effect.
Muscovite has higher dielectric breakdown voltage than phlogopite, thus, muscovite is mainly used for electrical insulation.
Mica is a natural inorganic mineral. That is to say a stone. 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.
Electric motors and generators for supporting our lives
Mica products have been used for electric insulation of industrial electric motors or
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.
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.
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.
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.
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.
Features of mica materials for fire spread prevention