Colemanite

Introduction:

Colemanite is a borate mineral with the chemical formula Ca₂B₆O₁₁·5H₂O and is the main ore for Boron production. 

Thermal decomposition at 330 °C, loosing its water of hydration according to the following reaction: 

Ca₂B₆O₁₁·5H₂O -> Ca₂B₆O₁₁ + 5H₂O

The  Ca₂B₆O₁₁ char residue has better mechanical properties than MgO, the char residue coming from the thermal decompostion of hydromagnesite.

Further characterized by: 

• Relatively low density of 2.42 g/cm³ compared to other mineral fillers, which are typically at 2.7 g/cm³
• Medium Mohs Hardness of 4.0
• Decomposition around 330°C, releasing water. 

Basic properties

PORTAFLAME® CA, C grades are micronized halogen-free flame retardant (HFFR) fillers (based on Colemanite), used as an effective synergist for other flame retardant fillers, such as ATH and magnesium hydroxide. 

Setting PORTAFLAME® CA, C grades apart from other flame retardant minerals is that the flame-retarding mechanism of PORTAFLAME® CA, C is based mainly upon its high char forming and glazing/fluxing ability in combination with endothermic decomposition (heat-sink effect). In applications such as polyolefin-based Wire & Cable compounds, a significant reduction of the peak Rate of Heat Release, as measured by the oxygen depletion method, is achieved.

PORTAFLAME® CA, C grades are easy to process and are an economical alternative to other flame-retardant fillers.