Patent Application
20080302032
1. Field of the Invention
The present invention relates to fenestration products, particularly, a skylight having a laminated glazing unit.
2. Background Art
Fenestration building products have been used to allow light into residential, commercial, and industrial buildings and typically fit in an opening in the building. Examples of fenestration products include skylights and tubular skylights. Skylights typically do not require the same degree of optical quality of windows. Therefore, low cost and lightweight plastic panels can be used in place of glass. Skylights are typically formed of a light transparent panel of glass or plastic mounted in a peripheral frame formed of wood, metal or extruded plastic. In order to achieve structural rigidity the plastic panels are frequently outwardly domed in a convex manner, the peripheral edges of the plastic panels being mounted in a rectangular or circular mounted frame.
Skylights are typically mounted on non-vertical surfaces of the building, particularly a roof. As a consequence, they are subjected to damage when items fall on them. Examples of these items may include hail, swaying tree limbs, or wind driven missiles such as during a hurricane. Sudden breaching of the skylight window subjects the underlying room to potentially substantial water damage and possibly could pressurize or depressurize the building causing the failure of other windows or doors. In extreme situations, breaching a skylight can allow strong winds to pressurize a building leading to the loss of a roof or other major structural failures.
In order to address missile impact failures, skylights in hurricane regions frequently use laminated tempered glass panels or very thick wall domed acrylic panels. However, laminated glass canopies are relatively heavy and relatively expensive. Their weight often demands stronger, more expensive support structures, like the door, larger roof joists, and larger size equipment for installation. Both of these increase the overall cost of the skylights.
What is needed is an inexpensive fenestration product which is inexpensive and lighter in weight that prevents catastrophic breaching such as with skylights by falling or windblown debris.
In its simplest form, the present invention comprises a fenestration product, such as a window or a skylight, to be mounted in a building opening. The fenestration product is provided with a peripheral frame to be mounted on the building defining a frame opening. Within the frame opening is a laminated panel capable of transmitting visible light into the building. The laminated panel is an outer periphery which is held by the peripheral frame spanning the panel opening. The laminated panel is made up of a first sheet of plastic, a second sheet of plastic and an interposed layer of resin which bonds the first and second sheets of plastic internal resin layer into a structural member. The laminated panel is selectively formable into a three-dimensional shape.
A preferred embodiment of the invention is a skylight assembly having a peripheral frame defining a frame opening. Within the frame opening is a laminated panel which sealingly cooperates with the peripheral frame to close the peripheral frame opening. The laminated panel is transparent to visible light and is made up of three layers, a first sheet of plastic, an intermediate sheet of resin and a second sheet of plastic which are collectively bonded together to form a laminate. Preferably, the laminate is selectively thermal formed so that the central region of the laminate forms a dome.
Another preferred embodiment of the invention, the dome laminated panel has a the peripheral frame molded in situ about to form a leak resistant bond between the single piece molded frame and the laminated panel.
In yet another embodiment of the invention, the skylight assembly described above having a peripheral frame and a laminated panel is further provided with the secondary transparent panel located in spaced relation to the laminated panel and cooperating with the frame to define an enclosed space which is filled with gas to improve the insulating qualities of the skylight assembly.
Reference will now be made in detail to compositions, embodiments, and methods of the present invention known to the inventors, however it should be understood that the disclosed embodiments are merely exemplary of the present invention which may be embodied in various alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting rather merely as a representative basis for teaching one skilled in the are to variously employ the present invention. Except where expressly indicated all numerical quantities in this description indicating the amounts of material or conditions it is understood as modified by the word “about” in describing the broadest scope of the present invention. Practice within the numerical limits is generally preferred.
In referring to
It should be understood that the reflective interior surface of collector 16, the light pipe 20, the interior flange 26, and the diffuser 28 are optional items in the skylight assembly 8.
The optional curb 14 and flashing 15 may be secured to the roof by methods known in the art. It should be understood that the frame 12 may include other securing elements without exceeding the spirit of the invention.
It should be further understood that while illustrations of certain embodiments are directed to skylight assemblies, other fenestration products may not exceed the spirit of the invention. Non-limiting examples of other fenestration products may include windows, patio doors, sidelights, doorlites, and transoms.
Referring now to
Referring to
The sheets of plastic 40 and 44 may be formable when laminated with the resin layer 48 in certain embodiments. These sheets range in thickness from 0.75 mm to 100 mm, with typical thicknesses independently selected from 2 mm, 3 mm, 4 mm, 5 mm, 10 mm or 20 mm. Non-limiting examples of forming processes for these sheets may include thermoforming, vacuum forming or pressure forming. The forming process in certain processes may occur at a temperature below a melting point of the selected plastics used in sheets 40 and 44. The processing temperature for forming should exceed a service temperature for the skylight, which in certain embodiments may range from 60-95° C. Examples of formable materials include acrylic and polycarbonate.
The sheets of plastic 40 and 44 are adjacent to the resin layer 48. It should be understood that the plastic 40 and 44 may be bonded, adhered or otherwise secured to the resin layer to form a multi-layer structural laminate. The fitness-for-use requirements of the inner plastic sheet 44 may be less stringent than the outer plastic sheet 40. The sheet 40 being on the outer layer may be exposed to a harsher environment than the sheet 44 on the inner layer in regards to temperature extremes, ultraviolet radiation, physical abrasion, and other conditions. It should be understood that the outer and inner sheets may be different or identical materials without violating the intent of the invention. Examples inner plastic sheets 44 may further include polyolefin, vinyl, and terephthalate. Since the inner plastic sheets 44 may not provide as much structural strength as the outer plastic sheets 40 the thickness of the inner sheet 44 may also be relatively thinner than the outer plastic sheet 40.
The resin layer 48 may be comprised of a resin. Non-limiting examples of the resin include polyvinyl butyral, ethylene vinyl acetate polymer or copolymer, or polyethylene. The resin layer may be applied as a liquid, a film or a sheet according to certain embodiments of this invention. Other physical forms of the resins may be used in this invention without violating the intent of the invention.
The periphery 51 of the canopy 10 which includes the periphery 42 of the first sheet 40, the second sheet 44 and the resin layer 48 is overmolded into the peripheral frame 12. It should be understood that other means of securing the canopy 10 to the frame 12 may be used without violating the spirit of this invention. Examples of securing means may include a gasket or a sealer. In certain embodiments, an optional spaced apart inner layer of plastic 52 may be included in the skylight assembly 8 in order to improve the thermal transmission resistance of the assembly 8. The multi-layer canopy 10 and the inner plastic layer 52 are preferably bonded together about their peripheral edges by a two-sided tape seal 53 to form an insulated unit. The two-sided tape seal 53 is described in detail in co-pending commonly owned U.S. patent application Ser. No. 11/671,657, entitled “Polymeric Insulated Glazing Unit with Molded Frame”, which is incorporated herein in its entirety.
The frame 12 may be formed of multiple pieces in a conventional manner. The multiple pieces may be fitted around the periphery of the canopy 10 to form the skylight assembly 8. An example is a rectangular frame having four individual frame sections that may corner-keyed and sealed. The frame is then sealed to the laminated panel using methods and materials known in the art.
Preferably the frame 12 is formed as a single piece. The single piece may be made as a separate molded part having no joints. The separate molded part then being sealed to the laminated panel. As an alternative, the frame 12 may be the single piece molded in-situ encapsulating the periphery of the laminated panel and simultaneously forming a watertight seal.
Materials that may be suitable for forming a single piece frame may include polymers, such as thermoset plastics like reaction injection molded plastics, thermoplastics, and fiber reinforced plastics. These materials may be shaped by processes known in the art, such as reaction injection molding, high pressure injection molding, extrusion, thermoforming, or compression molding.
Further, the skylight assembly 8 either alone or as part of a tubular skylight may have a reflective interior surface 54. This provides a good seal against dust and other small debris dropping from the inside of the roof, as well as allowing the skylight to be trim finished from an interior perspective. The reflective interior surface 54 aids in transmitting light to the room below. In addition, the reflective interior surface 54 may also connect with the light pipe 20 to further enhance the amount of light going to the room.
An example of the skylight assembly having the light pipe is disclosed in detail in co-pending, commonly owned U.S. patent application Ser. No. 11/671,726, entitled “Overmolded Fenestration Building Product and Method of Manufacture”, which is incorporated herein in its entirety.
As an option, a mar-resistant coating 56 may be applied to an exterior exposed surface of the plastic sheet 40 of the canopy 10. Siloxane or polymethyl methacrylate coatings or the like can be used to provide a hard, mar resistant exterior surface to the canopy 10.
To make the skylight assembly 8, take two sheets of plastic 40 and 44 which will be large enough to span the opening 6. In certain embodiments, the first 40 and second 44 sheets are bonded together by interposing the resin layer 48 between them. The sheets are laminated using methods known in the art. Non-limiting examples of methods may include pressure and/or heat, or heat under vacuum. Such a step removes any gas that may be trapped between the layers, as well as provides any curing or bonding necessary for the resin layer 48.
The laminated panel formed above optionally may be formed into a three-dimensional shape, such as a pyramid, a dome or similar convex configuration. The three-dimensional shape may provide additional structural strength relative to a flat sheet. Further, the three-dimensional configuration may less the impact force by deflecting the impact of some of the energy of relatively concentrated short-term loads such as 2″×4″ lumber missiles driven by a hurricane-force wind. These concentrated short-term loads are simulated by a missile impact test like TAS 201 used by the Miami-Date County Building Department. As described above, the laminated sheet may be formed using processes known for shaping. In an example of an embodiment of the method, a laminated panel may be positioned in a first mold half which is warmed sufficiently to soften the laminated panel. By applying a relatively mild pressure, the laminated panel, when softened, may then be shaped to conform to the first mold half. The laminated panel, once shaped, can be removed from the first mold half and positioned in a second mold that is a closed mold. The closed mold then is injected with a plastic in an area adjacent to the periphery of the laminated panel.
In this embodiment of the method of making the skylight assembly 8, a continuous frame 12 of plastic is molded in situ and the plastic forms a seal between the frame and the laminated panel. Once the frame 12 is cured, a substantially complete skylight assembly 8 can then be removed from the open mold. Forming the single piece frame encapsulating the laminated panel eliminates extra seals and joints, and is an example of the method to limit the opportunities for water to leak into a residence or commercial building. Seals and joints of other designs may deteriorate with environmental exposure, as well as fail due to fatigue originating with cyclic wind pressures and thermal expansions. The formation of a molded polymer frame is disclosed in published U.S. patent applications US2005/0178078A1 dated Aug. 18, 2005 and US2005/0055901A1 dated Mar. 17, 2005, both of which are co-pending, commonly owned, and incorporated by reference herein in their entirety.
The leak-tightness of the skylight assembly 8 may be tested according to ASTM E547-00 and ASTM E331-00. For areas of the United States that often suffer hurricane force winds and driven rain, an acceptance criterion for these standards is allowing no leakage during the period of the test. Structurally, the skylight assembly 8 may be tested according to ASTM E330-02 where there is a positive and negative wind load placed on the skylight assembly 8. The acceptance standard for a hurricane velocity wind zone is where the skylight assembly 8 exceeds the load of 250 pounds per square foot.
Even more significant performance criteria for the skylight assembly 8 are the missile impact test and a cycling test of TAS201 and TAS203 used by the Miami-Dade County Building Department. When measured using these two methods, an acceptance criterion is that no cracks or tears occur in the skylight assembly 8 at less than 90 pounds per square foot of force when measured using TAS203.
The skylight 60 of
Commercial buildings are using large skylights to allow natural light into the building and reduce their reliance on florescent overhead lighting. Such a commercial skylight is a curb-mounted cap. In this example, a curb with the outside maximum diameter of 46″×94″ can be prepared in the commercial roof to receive the nominal 4′×8′ curb-mounted cap having a laminated panel. The laminated panel is comprised of two 3 mm thick sheets of polymethyl methacrylate with 1.5 mm thick layer of polyvinyl butyral resin between the two sheets of acrylic. The laminated panel then is thermoformed into the shape of a dome. The domed laminated panel is then encapsulated with a frame of aliphatic polyurethane material which is colored bronze for aesthetic purposes. This curb-mounted cap then is mounted on the roof on the prefabricated curb.
In this example, the skylight for a residence is mounted on the roof having less than a 20° slope. A 3′×3′ residential skylight assembly is fitted into a 30.5″×30.5″ rough opening with a self-flashing curb attached to the roof. A curb-mounted cap having maximum outside dimensions of 34.5″×24.5″ is attached to the seamless self-flashing curb. The curb is trimmed out on the interior using approximately ¼″ thick sheets of trim stock wood. Trim stock is attached to the roof joists and finished to meet with the interior ceiling.
The curb-mounted cap includes a laminated panel having a 3 mm acrylic sheet on the exterior layer and a 2.5 mm polyethylene terephthalate interior layer. Between the layers a sheet of 0.5 mm ethylene vinyl acetate copolymer is bonded. The laminated panel is shaped to a dome configuration using vacuum-assisted thermoforming at a temperature of approximately 120° C. to 150° C.
For a residence in a high velocity wind zone such as within one mile of the Florida coast, a higher impact material may be necessary for the canopy 10. A skylight having this higher impact resistance is formed with a laminated panel having 4 mm polycarbonate on the outer layer and 2 mm polycarbonate sheet on the interior layer. The polyvinyl butyral layer in between the two sheets of polycarbonate is 2.5 mm. The outer layer of polycarbonate is protected with a coating of polymethyl methacrylate for increased resistance to degradation by ultraviolet light. On top of the polymethyl methacrylate layer, a layer of tetraorgano polysiloxane is applied as a scratch resistant coating. The laminate is encapsulated in a frame of aliphatic polyurethane material. This forms the curb-mounted cap which is then applied to the residential seamless self-flashing curb as in Example 2. The cap is secured to the curb with deck screws or the like.
It should be appreciated that various fenestration products may be manufactured utilizing the novel laminated panel and frame assembly and the invention is not limited to skylights per se. While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
