Process for coating modified bitumen membranes using reflective laminate coatings

Abstract

A method of applying a laminate composition containing a whitening pigment during manufacture of modified bitumen roll roofing membranes, is provided. The laminate composition is heat activated providing greater adherence to surfaces that it applied to, and greater reflective properties. The laminate has an initial energy efficiency rating greater than or equal to 0.65 for a low-sloped roof, or an initial energy efficiency greater than or equal to 0.25 for a steep-sloped roof.

Description

[0001] The present invention relates to a new and useful laminate composition and a method for applying the laminate, and more specifically, to a reflective laminate film composition for roll roofing products that is applied during the manufacturing process. BACKGROUND OF THE INVENTION [0002] Modified bitumens were developed in Europe during the late 1960's for roofing applications and found a market in the United States during the 1980's. These products are an important part of the roofing industry and are produced as a continuous sheet on a roofing line and are later cut down to individual pieces and wound in rolls of various lengths. Subsequent to laying on a roof, they are top coated with coatings that provide energy efficacy and reflectivity. [0003] With prior art white reflective coatings problems have occurred in maintaining roof surface reflectivity. Reflectivity decreases the most during the first year of a roof's life. After three years, the rate that reflectivity declines...

AI Technical Summary

Benefits of technology

The present invention provides an improved laminate composition for use in roofing products that provides energy efficacy, greater reflectivity, greater adherence, and a method of manufacture whereby the coating is applied during manufacture of the roll roofing membranes. The reflectivity provided by the inventive laminate composition, meets today's Energy Star® standards. The roofing product produced is flexible enough to allow the product to be rolled without cracking, yet is sufficient puncture and scuff resistant to adequately protect the laminate. The laminate is a white reflective laminate that adheres well to various roof substrates, particularly modified bitumen membranes. The method of the present invention involves applying the laminate that is adhered to roofing membranes during the manufacture of the roof membrane obtained via the extrusion processes to the roll roofing membrane while it is still hot exiting the formation line where it is produced, resulting in heat activated curing and adhesion to the membrane. The resulting coated roof has greater reflectivity than that achievable with coatings applied subsequent to placement of the membranes on site. The energy efficacy of the laminate is determined by its solar reflectance. The laminate composition of the present invention comprises a dispersion of plastic resins and a pigment. The invention is also related to the film, i.e. top coat, that is formed from the top coating composition of the present invention as well as roofing products that are coated with the same. The laminate is applied in-plant during manufacture of the roll roofing membranes in order to achieve a higher reflectivity.

Problems solved by technology

With prior art white reflective coatings problems have occurred in maintaining roof surface reflectivity.

Depending on the geographic exposure and how well roof surfaces drain, keeping roof surfaces white and preventing premature failure from cracking and peeling can be a significant challenge and result in major maintenance expenditures for owners.

However, granules are difficult to coat because of their rough, uneven surface areas.

Moisture and air pockets can be trapped under the coating and lead to blisters or pinholes in the cured coating.

Inconsistent coverage and potential cracking of areas where the coating is applied too heavily are additional problems related to application of previous coatings.

Virtually all parts of North America have some application limitations as a result of cold weather, daily rainstorms, high humidity and / or fog, or reduced daylight hours during winter.

Rain on an uncured coating will cause a partial or total coating run-off.

Problems occur when an acrylic coating is specified on a construction project without regard to the time of year the coating is to be installed.

Cold temperatures and lack of sunlight decrease the freshly applied coating's evaporation.

This often requires cleaning of the surface and reapplication of the coating.

Wet weather and cooler temperatures inhibit final cure and may inhibit proper fusing.

Consequently, acrylic coating applications cannot be attempted on roofing projects from late fall to early spring in most North American areas.

Film laminate coatings cannot be directly applied to asphaltic compounds because of inter alia difficulties due to heat sensitivities of the film, potential for delamination of the film caused by exudation of oil from modified bitumen membranes, and discoloration of the film due to exudation of oil.

However, foil materials typically have very smooth surfaces, which may provide insufficient surface area for binding, and therefore could delaminate from the surface of the asphaltic compound after cooling of the roofing membrane.

Moreover, use of a thin layer of aluminum can cause the surface film laminate to fail by erosion or damage due to traffic.

Conversely, use of a thicker foil increases cost in addition to posing other problems such as the product becomes very rigid and difficult to handle.

Importantly, foil will not meet Energy Star® requirements.

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