Highly reflective and emissive asphalt-based roofing membrane

Abstract

A prefabricated asphalt-based waterproof roofing membrane for use in a multi-ply asphalt-based commercial roofing system, e.g. a cap sheet that forms the exposed layer of a multi-ply built-up roofing system, is manufactured at a factory to have a highly reflective and emissive non-asphalt based elastomeric top coating layer. Preferably, a polymer primer layer is interposed between the highly reflective and emissive coating layer and an asphalt saturated and coated reinforcing substrate to keep oils and other colored components in the asphalt from exuding into the highly reflective and emissive coating layer.

Description

[0001] This patent application is a continuation-in-part of patent application Ser. No. 10 / 659,001 filed Sep. 10, 2003.BACKGROUND OF THE INVENTION [0002] The subject invention relates to asphalt-based waterproof roofing membranes used in multi-ply asphalt-based commercial roofing systems and, in particular, to a prefabricated asphalt-based waterproof roofing membrane for use in a multi-ply asphalt-based commercial roofing system, e.g. a cap sheet that forms the exposed layer of a multi-ply built-up roofing system, that is manufactured at a factory to have a highly reflective and emissive upper surface that meets EPA Energy Star and similar energy saving requirements. [0003] Asphalt-based waterproof roofing membranes, such as cap sheets, are currently manufactured in a process that includes several major process steps. The process steps for producing these black asphalt-based waterproof roofing membranes include: saturating a reinforcing substrate with asphalt (bitumen), typically an...

AI Technical Summary

Benefits of technology

[0011] The standardized, prefabricated asphalt-based waterproof roofing membrane of the subject invention can be easily applied at a job site with no need to coat the asphalt-based roofing membrane at the job site to improve the reflectivity and emissivity of the top surface of the membrane to meet EPA Energy Star requirements as measured by ASTM standard E 903 and California Code Title 24. In the method of manufacturing the prefabricated asphalt-based waterproof roofing membrane of the subject invention, a highly reflective and emissive non-asphalt based elastomeric coating, in liquid or powder form, is applied to the top surface of a black asphalt saturated and coated reinforcing substrate of the membrane during the manufacture of the asphalt-based waterproof roofing membrane at the factory to provide the asphalt-based waterproof roofing membrane with a highly reflective and emissive top surface that meets current EPA Energy Star requirements as measured by ASTM standard E 903 and California Code Title 24. Preferably, the highly reflective and emissive top surface of the asphalt-based waterproof roofing membrane is white. The highly reflective and emissive top surface of the asphalt-based waterproof roofing membrane may be smooth or the highly reflective and emissive top surface of the asphalt-based roofing membrane may be embossed or otherwise textured, may contain granules between the asphalt and the white polymeric surface coating, or may contain granules that are directly applied to the top surface of the white polymeric coating to enhance the appearance of the top surface and to provide a slip-resistant roofing surface on which the workers can walk.

[0012] The highly reflective and emissive elastomeric coating used in the prefabricated asphalt-based waterproof roofing membrane of the subject invention is opaque to protect the underlying asphalt layer of the asphalt saturated and coated reinforcing substrate of the membrane from the deleterious effects of ultraviolet radiation and may have various additives to improve the performance of the composite, e.g. fungi growth-inhibiting agents, fire retardants, etc.

[0013] The highly reflective and emissive coating of the subject invention is a polymer material binder that is preferably colored with a white pigment, such as titanium dioxide, zinc oxide, aluminum oxide. The polymer material binder used in the highly reflective and emissive coating to carry and bind the highly reflective and emissive pigments of the coating to the top surface of the asphalt layer of the asphalt saturated and coated reinforcing substrate of the membrane includes several families of binders. Preferably, the polymer binders are made up of amine-terminated polymer resins and / or amine-terminated chain extenders. Acrylic and isocyanate-based elastomers are particularly well suited for use as the coatings with the isocyanate elastomers being preferred. Preferably, a polymer primer, which is impermeable to the oils and other components of the asphalt, is applied between the highly reflective and emissive coating layer and the top surface of the top asphalt layer of the asphalt saturated and coated reinforcing substrate to prevent the exuding of oils and other components from the asphalt into the highly reflective and emissive coating and to thereby prevent the oils and other components of the asphalt from staining and otherwise discoloring or adversely affecting the highly reflective and emissive coating layer.

Problems solved by technology

Due to their irregular granular top surfaces and the intergranule spaces that reveal the black light-absorbing asphalt surfaces to which the granules are adhered, asphalt-based waterproof roofing membranes, such as cap sheets, currently on the market do not meet current EPA Energy Star reflective requirements as measured by ASTM standard E 903-Standard Test Method for Solar Absorptance, Reflectance, and Transmission of Materials Using Integrating Spheres.

This procedure leads to several problems: a waiting period of up to 30 days before the coating can be applied to the top surface of the membrane; the cost of and time required to clean the top surface of the membrane before applying the coating to the top surface of the membrane; the cost of and time involved in the labor intensive application of the coating to the top surface of the membrane; the quality and / or consistency of the application of the coating to the top surface of the membrane which is dependent on the skill and conscientiousness of the laborer; the limited service life of such coatings on the top surface of the membrane; and the requirement for the periodic maintenance and reapplication of the coating to the top surface of the membrane.

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