Mineral fibre products
AssigneeRockwool International A/S
InventorSoren Jensen
Life of this patent
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Abstract
The properties of mineral fibres comprising silicon, magnesium, calcium, iron, aluminium and oxygen atoms are improved by exposure to a heat treatment under oxidising conditions which causes migration of MgO, thereby creating an outer layer with increased concentrations of MgO. Batts and other fibrous products containing the fibres have increased resistance to shrinkage and sintering.
Claims20
A mineral fibre product comprising fibres formed of a silicate network and comprising silicon, calcium, magnesium, iron, aluminium, oxygen and optionally alkali metal characterised in that the fibres have an analysis (expressed as % by weight oxides) including at least 3% FeO, 0 to 8% alkali metal oxide and at least 5% MgO, in that at least 70% of the iron is ferric in that the fibres have a core surrounded by an outer surface layer less than 1 μm thick in which the peak concentration of magnesium atoms is at least 1.5 times the concentration of magnesium atoms in the total fibre.
A method of treating mineral fibres formed of a silicate network to improve their high temperature properties wherein the fibres comprise silicon, calcium, magnesium, iron, aluminium, oxygen and optionally alkali metal, characterised in that the fibres have an analysis (expressed by weight oxides) including iron in an amount of at least 3% measured as FeO and in which there is at least 2% iron (measured as FeO) present as ferrous iron, 0 to 8% alkali metal oxide and at least 5% MgO, and the method comprises exposing the fibres containing at least 2% by weight ferrous iron under oxidising conditions to a controlled increased temperature which is above the temperature at which oxidation of the iron in the fibres occurs but which is below the temperature at which substantial network crystallisation occurs and thereby oxidising the ferrous iron to provide fibres in which at least 70% of the total iron is ferric.
Dependencies are inferred from the claim text.