CN111997285A - Weather barrier - Google Patents

Disclosed herein is a weather barrier having: (a) a hydrophobic, air impermeable, UV and acid resistant, externally facing transparent or translucent barrier layer; (b) an intermediate reflective layer of a metallic material having a solar reflectance in a range of 0.7 to 0.95; and (c) a support layer structurally carrying the reflective layer and the barrier layer. Also disclosed herein is a method of forming a weather barrier by: the method includes bonding a reflective layer to a base layer with an adhesive, and applying a barrier layer to the reflective layer.

Weather barrier

Technical Field

The present invention relates to a weather protection barrier. Although not exclusively, the barrier has particular application on roofs with the aim of limiting the transfer of heat from solar radiation to the building. Weather barriers that limit heat transfer from solar radiation are also suitable for trucks, tents and pipes.

Background

Building design considerations in warm climates such as the tropics take into account the solar reflectance of the exterior surfaces. In particular, these surfaces preferably have a high solar reflectance, thereby reducing the amount of heat transferred into the building (and thus reducing the level of air conditioning required to maintain a comfortable environment within the building). Solar reflectance is important because more than 90% of the energy in the solar spectrum is in both the visible and infrared portions of the spectrum. About 5% of the solar energy is contributed by the Ultraviolet (UV) part of the solar spectrum, so the emphasis of exterior building products such as roofs has been to ensure relatively high solar reflectance through exposed metal surfaces (e.g. aluminum) or through light-colored paints.

An example of such a weather barrier as a laminated roof sheet is disclosed in us patent 5096759 (Simpson et al). The sheet material includes an outer aluminum foil layer bonded to an underlying polyethylene substrate by a resin. The asphalt layer is present on the underside of the polyethylene layer and serves two purposes. One purpose is as an adhesive to secure the roofing sheet to the roof support structure, while another purpose is to seal the punctures or breaks in the polyethylene layer, thereby maintaining the waterproof integrity of the roofing sheet. Roof sheets such as those disclosed by Simpson et al may have a solar reflectance in the range of 0.05 to 0.9, depending on the form of the aluminum layer.

The same structure exists in today's roofing laminate sheet products. However, the applicant has observed that the aluminium foil layer oxidizes over time and therefore its ability to reflect solar radiation is reduced. This means that solar radiation is absorbed to a greater extent by the roofing sheet, heating the roof and transferring the heat to the underlying building.

In addition to oxidation, the aluminum layer is exposed to dust and dirt carried by wind and rain, and this dust and dirt will wear away the aluminum layer over time, resulting in the reflected light finish on the surface being gradually removed over time. As a result, the solar reflectance of the aluminum layer decreases over time. The same effect occurs when the aluminum layer is exposed to acid rain due to acid etching of the aluminum surface. These effects are exacerbated by the accumulation of dirt and organic materials (e.g. moss, lichens and fungi) on the surface of the aluminium layer. Accumulation means that less of the surface is exposed to solar radiation and therefore the solar reflectance is reduced. As a result, solar energy is more easily transmitted into buildings or other underlying structures.

UV radiation has an embrittling effect on polymeric materials, including hydrocarbons contained in bitumen, which, once embrittled, may crack due to thermal expansion under daily or seasonal temperature changes. Thus, the reflectivity of the aluminum foil layer is important to protect the underlying polyethylene and asphalt layers from degradation that may result in cracking of the water barrier, thereby compromising the weather resistance of the roof sheet. It follows that the integrity of the aluminium layer is important for the durability of the roof sheet as a weather barrier. It is expected that the solar reflectance of a roof barrier with an exposed aluminium layer will decrease relatively quickly over time.

U.S. patent 7803867 (Hanrahan et al) discloses another form of weather barrier that includes a white fluoropolymer layer coated on a flexible roof substrate or directly on a primer layer or tie layer. The light color incorporated into the fluoropolymer layer is intended to block and reflect solar radiation, thereby keeping the underlying structure cool. However, the color of the white fluoropolymer layer may fade over time and the solar reflectance may decrease as well.

Accordingly, there is a need to provide a weather barrier that maintains a suitably high solar reflectance for a longer period of time than existing products.

Disclosure of Invention

According to one aspect, there is provided a weather barrier having:

(a) a hydrophobic, air impermeable, UV and acid resistant weather-facing transparent or translucent barrier layer;

(b) an intermediate reflective layer of a metallic material having a solar reflectance in a range of 0.7 to 0.95; and

(c) a support layer structurally carrying the reflective layer and the barrier layer.

The barrier layer protects the reflective layer from dirt and organic materials and is impermeable to air, meaning that the outward facing surface of the reflective layer is not oxidized. Thus, the reflective layer does not degrade significantly over time. Thus, it is contemplated that the reflective layer may prevent UV light from reaching the base layer and any other water resistant material layered beneath the weather barrier.

The term "UV resistant" as used in the present specification and claims means that the barrier layer is capable of withstanding at least 1000MJ of solar radiation.

The term "acid-fast" as used in the present specification and claims means that the barrier layer does not degrade when immersed in an acid having a pH of at least 3.15 for at least two days.

The support layer may be bonded to the reflective layer by an adhesive.

The weather barrier may comprise a waterproof layer on the inner side of the support layer.

The support layer may be a polymer and have a tensile strength in the range of 150 to 350MPa according to ASTM-D882. In one embodiment, the support layer may be polyethylene terephthalate (PET). Alternatively, the PET may be biaxially oriented PET (bopet). In other embodiments, the support layer is polyester.

In an alternative form, the support layer may be a non-polymeric material. For example, it may be woven glass fibre or may be non-woven glass fibre.

Optionally, the support layer is thermally stable at a temperature to which the weather barrier is heated when exposed to solar radiation. This means that its melting temperature is higher than the temperature to which the weather barrier is heated when exposed to solar radiation. This also means that the weather barrier has a low oxidation sensitivity (oxidizability) at the temperatures to which it is heated when exposed to solar radiation. The high thermal stability ensures that the weather barrier is subjected to a wide range of temperatures and therefore thermal expansion or contraction due to the temperature range will not cause tearing or cracking of the substrate layer due to daily and seasonal temperature changes.

Furthermore, the support layer must be thermally stable enough to be unaffected by the temperature at which the asphalt is applied, as the weather barrier may be applied to the hot asphalt to secure the weather barrier to the substrate. The temperature of the hot asphalt is typically about 150 ℃.

Typically, the substrate may be secured to the structure by asphalt or another suitable weather (weather/climate resistant) adhesive. More specifically, the weather barrier layer may be secured to the structure at certain locations (points) of the weather barrier or areas across the weather barrier, and it is important that the weather barrier not thermally expand or contract to the point where the weather barrier fractures or breaks (e.g., beyond the tensile strength of the base layer). Exceeding the tensile strength may result in cracking or breaking of the barrier layer or the reflective layer or both, thereby exposing the underlying asphalt waterproofing layer to solar radiation. If cracking or breaking occurs, solar radiation exposure, more specifically UV radiation exposure, of the underlying asphalt waterproofing layer may be compromised. In that case, water may penetrate the structure in which the weather barrier is provided, possibly causing water damage to the structure. If the weather barrier is used to seal a roof, water damage may affect roof structural components (e.g., beams, purlins, or joists) and may affect the ceiling material (e.g., gypsum board) secured to the roof structural components.

The barrier layer is inert to UV, visible and infrared radiation in solar radiation.

Optionally, the barrier layer is applied to the reflective layer by gravure printing, flexographic printing (flexographic printing) or spray coating. Optionally, the barrier layer has a thickness in the range of 0.5 to 10 μm.

The barrier layer may have a surface tension of less than 28 mN/m. This relatively low surface tension means that the barrier layer is hydrophobic. In practice this means that water will bead up on the barrier layer and run off. This effect means that most of the dirt and organic material carried in the water and already present on the surface will be carried away from the barrier layer by the water. In other words, the barrier layer actually has self-cleaning properties.

The barrier layer may include a fluoropolymer. The fluoropolymer is inert to UV radiation and has non-tackiness which renders it self-cleaning. Furthermore, the barrier layer preferably bonds well to metal surfaces. Preferably, the barrier layer is formed of a material that bonds to the metal surface without an intermediate adhesive. Thus, the combination of a transparent or translucent fluoropolymer with a metal surface forms a highly reflective laminate that is relatively stable when exposed to solar radiation because it is more resistant to degradation than other materials.

The barrier layer may also have anti-glare properties. The barrier layer may have an anti-glare property that causes the solar reflectance of the weather barrier to be substantially the same as the solar reflectance of a weather barrier without the anti-glare property. Preferably, the antiglare property reduces the overall solar reflectance by less than (less than) 10%. More preferably, the antiglare property reduces the overall solar reflectance by less than 5%. Even more preferably, the antiglare property reduces the overall solar reflectance by less than 2%.

The weather barrier may have a high solar reflectance of 0.7 or higher. The weather barrier may also have a high energy dissipation capability for the absorbed energy. In other words, the energy absorbed by the weather barrier from exposure to solar radiation will be in the form of heat. The degree to which the weather barrier becomes hot depends on its ability to dissipate heat into the atmosphere (i.e., dissipate heat).

In an alternative form, the barrier layer may be coloured a light colour. For example, the barrier layer may be colored white, light gray, cream, or beige. In this alternative, a substantial portion of the solar energy is reflected by the barrier layer. Some solar radiation may penetrate the fluoropolymer and be reflected by the reflective layer.

The reflective layer may be metallic. Optionally, the reflective layer is a metal foil of aluminum. Optionally, the aluminum foil has a thickness in the range of 3 to 30 μm.

According to another aspect, there is provided a method of forming a weather barrier by:

(a) bonding the reflective layer to the base layer using an adhesive; and

(b) a barrier layer is applied to the reflective layer.

According to this aspect, the barrier layer may be applied by gravure printing, flexography, and spray coating. The barrier layer may be a fluoropolymer.

The reflective layer may be an aluminum foil. The substrate layer may be PET.

Optionally, a water barrier layer may be applied on the opposite side of the substrate layer from the reflective layer. The water barrier layer may be an asphalt layer.

Drawings

Embodiments of the above aspects will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 is a schematic exploded cross-sectional view of a weather barrier in accordance with an embodiment of the weather barrier disclosed above.

Detailed Description

Preferred embodiments of the invention will now be described hereinafter, including reference numerals corresponding to features shown in the drawings.

Optionally, the fluoropolymer barrier layer has anti-glare properties. Preferably, the barrier layer has an anti-glare property that causes the solar reflectance of the weather barrier to be substantially the same as the solar reflectance of a weather barrier that does not have the anti-glare property. More specifically, it is preferable that the antiglare property reduces the total solar reflectance by less than (less than) 10%. More preferably, the antiglare property reduces the overall solar reflectance by less than 5%. Even more preferably, the antiglare property reduces the overall solar reflectance by less than 2%.

It will be appreciated that a suitable alternative to BOPET may be used in place of BOPET, provided that the alternative has the required tensile strength and low coefficient of thermal expansion. Suitable alternatives are known to the person skilled in the art.

Those skilled in the art to which the invention relates will appreciate that many variations and modifications may be made to the preferred embodiments without departing from the spirit and scope of the invention.

In the appended claims and the foregoing description, unless the context requires otherwise due to express language or necessary implication, the word "comprise" and variations such as "comprises" or "comprising" are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus and methods disclosed herein.

In the foregoing description of the preferred embodiments, specific terminology has been resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents that operate in a similar manner to accomplish a similar technical purpose. If terms such as "front" and "rear", "inner" and "outer", "above", "below", "upper" and "lower" are present in the specification, they are used as convenient words for providing reference positions, and should not be construed as limiting terms. Similarly, the terms "vertical" and "horizontal" (if used in this specification including the claims) refer to an orientation relative to a conventional operating orientation.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the invention. Moreover, the various embodiments described above can be implemented in conjunction with other embodiments, e.g., aspects of one embodiment can be combined with aspects of another embodiment to implement other embodiments. Furthermore, each individual feature or component in any given assembly may constitute additional embodiments.