There are significant variations in the water repellency properties within the mineral wool insulation category. There are products on the market with no water repellency properties, products with superficial hydrophobic treatment with water repellent additive of the finished product and also products where the actual fibers are treated. Also there is a difference between the hydrophobic additives employed, some being organic and thus more susceptible to thermal degradation and others being inorganic and therefore more stable when exposed to high temperature.
For industrial insulation products, the purpose of the water repellency is to:
Provide short term protection against water exposure during installation
Delay water ingress during service
Reduce water absorption during service
Wet insulation material offers reduced insulation performance and water trapped under the insulation material or in the insulation material may cause corrosion of unprotected metal. This paper will discuss the function of the hydrophobic treatment of mineral wool and different types of hydrophobic treatments that are used. It will also introduce a novel and significantly improved hydrophobic treatment that offer superior water repellency properties at ambient temperatures, but also retained after heating to 250 _C (482 _F).
The paper will present measurements of water repellency properties of different mineral wool products, with different types of treatment, as well as the effect on corrosion, when the different insulation materials are employed in a simple corrosion test.
Key words: Water Repellency, CUI, Mineral Wool, EN13472, ASTM C1763, Heat aging