Water proofing membrane, and a method for making a water proofing membrane

Abstract

The invention relates to a waterproofing membrane (1) comprising a structure incorporating a fiber layer (10) and carrying a bituminous mass (15) on one side, the other side carrying a layer (20) of a first substance comprising between 10% and 40% by dry weight of an acrylic polymer mixed with between 4% and 40%, preferably between 20% and 40%, by dry weight of titanium dioxide and at least 1% by dry weight of a transparent or translucent hydrophobic material, said layer (20) defining a surface (S) of said membrane (1).

Description

FIELD OF THE INVENTION[0001]The present invention relates to a water proofing membrane, such as for application on a building roof, comprising a structure incorporating a fibre layer, such as a glass fiber web, carrying a bituminous mass on one side and where the other side of the fiber layer has a substance comprising titanium dioxide and an acrylic polymer.BACKGROUND OF THE INVENTION[0002]Such a waterproofing membrane is known from WO 2004 / 070107. For manufacturing the known membrane, the bituminous mass is applied to the one side of the structure where on the other side a cover layer formed by a substance comprising particulate titanium oxide and an acrylic polymer has been applied. The substance is applied as a coating to the fiber layer before the bituminous mass is applied. The acrylic polymer reduces exudation, as discussed also in EP 876 532 and EP 1 252 386, which would otherwise give rise to brown stains forming on the upper side of the membrane. The acrylic polymer also f...

AI Technical Summary

Benefits of technology

[0005]The present inventors have found that this exudation problem arises through a strong local or spot-wise heat absorption, and have identified the cause to be dark spots of dirt that appear on the upper side of the membrane after some time of use due to its exposure to the environment. In fact, over the time dirt in the form of particles settling on the entire surface of the membrane will lead to a darkening of the membrane, reducing the reflective effect of the titanium dioxide. Such a darkening, whether it is spot-wise or a uniform darkening across the entire surface, leads to an increased heat absorption and, hence, to the risk of a consequential oil migration leading to brown spots that in in themselves will make the problem of heat absorption worse over time.

[0006]Hence, an object of the invention is to seek to eliminate or reduce the tendency of oil migration while allowing for a possible reduction in the thickness of the layer of acrylic polymer / titanium dioxide.

[0007]The inventors have found that by adding water-repellent properties to the membrane, dirt which may otherwise give rise to the aforementioned stains, is more easily washed away from the membrane surface, thus reducing the tendency of the formation of local brown spots due to migrating oils that darken the white surface of the membrane. Hence, with the invention local exudation is less likely to occur.

Problems solved by technology

The acrylic polymer also forms to some extend a barrier against ultraviolet rays so that the latter cannot easily reach the bituminous mass.

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