Patent Application
20090272055
One or more embodiments of this invention relate to an architectural wall panel system designed to cover an interior or exterior building surface. More specifically, one or more embodiments relate to an architectural wall panel system employing high strength bonding adhesives to attach mounting clips to the wall panel.
Architectural wall panel systems, including both metal and composite wall panel systems, have been used extensively for some time, primarily in the commercial and industrial building markets. In recent years the popularity of composite wall panel systems, in particular, has been increasing steadily. There are a number of factors that may be credited for the wide-spread and increased use of such wall panel systems. One such factor is the high cost to construct commercial and industrial buildings, which tend to be relatively large, from stone or brick. Wood is not a suitable substitute due to the large loads the buildings supporting structure must withstand. Another factor affecting the increased use of metal and composite wall panel systems is the high durability of the systems. Both the metals and composites used to make the panels for wall panel systems are highly resistant to damage from sun, dirt, moisture, fire, and many other environmental elements. Consequently, the metal and composite wall panel systems have a long life, and may require less maintenance than other alternative building materials and systems.
Architectural wall panel systems can generally be placed into one of two categories: Face-sealed architectural panel systems or vented rain-screen architectural panel systems. Face-sealed architectural panel systems include those systems that have a sealant in both the horizontal and vertical joints between adjacent wall panels. The sealants make the wall panel system impermeable to air and water, and may include caulking, gaskets, or other sealants with a similar function. Vented rain-screen architectural panel systems are those systems designed to allow permeability through the joints between adjacent wall panels. The permeable joints allow for breathability and rapid pressure equalization within the wall panel system to prevent pressure buildups behind the wall panels.
Architectural wall panel systems have many advantages, as discussed above, however, these systems may also present a number of challenges and disadvantages. One such challenge is the thermal expansion and contraction of the wall panels. The metal and composite materials used most commonly in architectural wall panel systems are subject to natural expansion and contraction due to changes in atmospheric conditions, including heat and humidity. If a means of accommodating this inherent thermal cycling is not provided in the attachment system of the architectural wall panel system then the panels can become warped and cracked, requiring repairing or replacement.
Another challenge that may be associated with architectural wall panel systems is directly related to the first issue of thermal cycling, and relates to the effectiveness of sealants used in joints between adjacent wall panels in face-sealed architectural panel systems. Because the joints increase and decrease in size during thermal cycling, sealants often become dislodged and/or cracked and are thereafter ineffective at preventing the infiltration of air and water. As a result, sealants used in face-sealed architectural panel systems have proven disappointingly ineffective.
An additional disadvantage associated with many architectural wall panel systems is the complexity of the system, including the number of pieces and parts needed and the extensive time and labor required to install the complex system. In particular, where a form of an attachment clip is used to secure the wall panels to the substructure, each clip must typically be fastened to the wall panel and to the substructure, either directly or indirectly. This means that if an extremely high number of fasteners are used, it results in a great deal of time and effort spent in installation of the systems just to secure the clips to the panels prior to attaching the panels to the structure.
A further disadvantage is that the weight of the wall panels can cause a shearing moment on the clips of the system. Until now, mechanical fasteners have been required to counteract this shearing moment. Common adhesives, such as, for example, silicone adhesives, have not had the necessary shear strength to secure the clips to the wall panels, necessitating the continued use of fasteners. Furthermore, silicone adhesives take a long time to cure, and are not conducive to additional finishing steps such as sanding and painting.
A number of different attachment systems have been introduced and employed in an attempt to overcome the challenges and alleviate the disadvantages discussed above. One known attachment system includes a plurality of locking members secured directly to, or formed integrally with, the outer surface of the return flanges of wall panels. The locking members secure the panel to a retaining member, which is itself secured to a surface of a building structure. The locking members are shaped such that they may be forced into a channel, but cannot be removed from that channel, such as angled surfaces with an apex adjacent the retaining member that resemble half of an arrowhead. The system may also optionally provide a drainage channel to carry water and other debris away from the surface of the building structure. While this attachment system allows for more efficient installation of an architectural wall panel system, it suffers from the disadvantage mentioned above relating to thermal cycling of the wall panel system because it does not allow for movement of the wall panels. In addition, the attachment system suffers from a number of new disadvantages, such as not providing adequate attachment strength to withstand some natural weather conditions, and making it extremely difficult to repair or replace installed wall panels as the locking members prevent the panel from being removed from the retaining members.
Other known attachment systems for securing wall panels of an architectural wall panel system to a building surface utilize some form of an insert wedged between the two adjacent flanges of adjacent wall panels, while the flanges are received in a channel. The insert is secured between the two flanges by a fastener, and fits snuggly therebetween to provide a seal against water and air infiltration. The insert may be made of an elastomeric material to allow for thermal expansion and contraction of the wall panels. This system, however, uses a high number of parts, and the thermal cycling of the system is limited by the small amount of movement allowed by the elastomeric insert. Furthermore, the elastomeric insert is subject to wear from the natural elements it will be exposed to, and subject to failure due to these elements and repeated expansion and contraction as a result of the thermal cycling of the wall panel system.
Additional attempts at improved attachment systems have included attachment systems utilizing variously shaped flanges extending along at least one edge of the wall panel to facilitate attachment of the panel to a building surface; attachment systems using rotatable retaining members secured to the mounting surface that rotate between a first (narrow) position designed to allow placement of the wall panels and a second (broad) position extending into slots in the wall panel flange to secure the panel in place, such as, for example, a T-shaped retaining member that rotates about an axis parallel to the wall panel flanges; and attachment systems having vents and filler strips which slide into grooves and are positioned within the gaps between adjacent wall panels to provide a watertight seal while allowing air flow therethrough. None of these attachment systems has proven noticeably advantageous over conventional attachment methods in providing a more efficient, reliable, and practical means of attaching architectural wall panels to the surface of a structure.
There is therefore a need for an improved architectural wall panel system, and specifically an improved attachment system for attaching architectural wall panels, that alleviates one or more of the disadvantages discussed herein.
In one or more embodiments of the present invention an architectural wall panel system (hereinafter referred to as wall panel system) is provided, and is generally indicated by the numeral 20 in
Wall panels 22 may be made of any suitable material. These include those materials that have the strength and wear characteristics to withstand the natural forces and elements that act upon the wall panel system. These materials will be readily apparent to a person of ordinary skill in the art. In one or more embodiments wall panels 22 may be made of metal, and in certain embodiments wall panels 22 are made of aluminum. In other embodiments, wall panels 22 may be made of a composite material. In still other embodiments, wall panels 22 may be made of ACM, or architectural composite material, as is well known in the industry. Wall panels 22, as shown in the figures, have a rectangular shape, however other shapes may be employed without deviating from the scope of the invention.
Wall panels 22 are positioned adjacent to one another with a gap, generally indicated by the numeral 25, therebetween to facilitate installation and thermal cycling, as will be discussed in greater detail below. Each wall panel 22 has a top edge 26, a bottom edge 28, and left side edge 30, and a right side edge 32. Gaps 25 are formed between the adjacent edges of two panels, such as, for instance, a horizontal gap 25 between top edge 26 of a lower panel and bottom edge 28 of an upper panel positioned immediately above the lower panel. Similarly, vertical gaps 25 are formed between a left side edge 30 and a right side edge 32 of adjacent panels.
As is apparent from
In one or more embodiments wall panel 22 is generally pan shaped having a body portion 27 and side portions, also referred to as side flanges or flanges, extending from the edges of body portion 27. Body portion 27 may have any desired size, depending upon the desired appearance of wall panel system 20 and the engineering design constraints relating to wind forces and other factors that may limit the dimensions of wall panel 22 in one or more ways. In one or more embodiments, such as the embodiment shown in the figures, a rectangular shaped wall panel 22 is provided with body portion 27 having a height, or distance between top edge 26 and bottom edge 28, of between approximately 3 inches and 72 inches, in other embodiments between approximately 6 inches and 60 inches, and in still other embodiments between 6 inches and 48 inches. Similarly, body portion 27 may have a width, or distance between left side edge 30 and right side edge 32, of between approximately 3 inches and 180 inches, in other embodiments between approximately 6 inches and 144 inches, and in still other embodiments between 6 inches and 120 inches.
The height and width of body portion 27 may differ, creating a rectangular shaped body portion 27, or they may be equal, thereby making body portion 27 square in shape. In one or more embodiments wall panel 22 may have a depth of between approximately 0.5 inches and 6 inches, in other embodiments a depth of between 0.5 and 3 inches, and in a preferred embodiment a depth of approximately 0.875 inches. Wall panel 22 may also include one or several of a variety of finishes or textures to provide a desired appearance, as is well known in the art.
The side flanges of wall panel 22 extend a relatively short distance from body portion 27, as compared with the overall dimensions of wall panel 22. The flanges extend from each edge so that top edge 26, bottom edge 28, left side edge 30, and right side edge 32 each has a flange extending therefrom, referred to hereinafter as top flange 36, bottom flange 38, left side flange 40, and right side flange 42 (
An attachment system 50 useful to secure wall panels 22 to building surface 24 is shown in
Mounting bracket 54 includes a top channel 60 that receives a portion of a clip 52 attached to the bottom flange 38 of a wall panel 22, as will be discussed in greater detail below. Top channel 60 is generally U-shaped, and is displaced outwardly from building surface 24. Mounting bracket 54 also includes a bottom channel 62 that is positioned below top channel 60, and which is also displaced outwardly from building surface 24. Bottom channel 62, like top channel 60, is generally U-shaped and is adapted to receive a portion of a clip 52 attached to the top flange 36 of a wall panel 22. In one or more embodiments, bottom channel 62 may include a protrusion 64 within the U-shaped channel extending toward building surface 24 on the upper end of the channel. Protrusion 64 helps to maintain clip 52 within bottom channel 62, as will be discussed hereinafter.
In one or more embodiments, clip 52 may be between approximately 0.5 and 5.0 inches wide, in other embodiments clip 52 may be between approximately 2.0 and 4.0 inches wide, and in a preferred embodiment clip 52 may be approximately 3.0 inches wide. In one or more embodiments, a right-angled portion, generally indicated by the numeral 66, of clip 52, having a first section 67 and a second section 69, rests in the corner created by top flange 36 and body portion 27 of wall panel 22, as best seen in
In at least one embodiment, clip 52 further includes a slot 68 (
In one or more embodiments, clip 52 may be attached to wall panel 22 by an adhesive system, which, when cured, provides an adhesive layer 65 between clip 52 and wall panel 22. In other words, adhesive layer 65 bonds clip 52, or at least a portion thereof, to wall panel 22, or at least a portion thereof. In one or more embodiments, adhesive layer 65 may be interposed between the first and second sections 67 and 69 of right-angled portion 66 of clip 52 and the corner of wall panel 22, thereby securing both surfaces of right angled portion 66 to wall panel 22. Specifically, adhesive layer 65 may secure first section 67 to flange 36 and second section 69 to body portion 27. By utilizing adhesive on both surfaces of right-angled portion 66 of clip 52, it is possible for an adhesive to overcome the shear moment acting upon the clip 52 so long as an appropriate adhesive is used that provides the desired mechanical properties. In one or more embodiments, adhesive layer 65 may also fill gap 73 between displaced portion 71 of second section 69 and body portion 27, providing increased resistance to the shear forces acting upon clip 52.
In one or more embodiments, the adhesive system includes an acrylic adhesive, which may be referred to simply as an adhesive. Uncured acrylic adhesives include a monomer that contains one or more reactive acrylate groups. For example, the acrylic adhesive may include acrylate or methacrylate monomer. Examples of methacrylate monomers include ethyl acrylate, butyl acrylate, and methyl methacrylate. In one or more embodiments, the uncured acrylic adhesive may include one or more co-monomers that are capable of reacting with the acrylate monomer to form a copolymer. Examples of co-monomers include styrene and unsaturated rubber. Examples of commercially available acrylic adhesives include Lord® 403, 406, and 410, available from Lord Corporation.
In one or more embodiments, other components of the adhesive system include an accelerator. Accelerators include mix-in curatives that promote faster cure times or curing of the adhesive at room temperature. In one or more embodiments, the accelerator includes an epoxy resin, diisobutyl phthalate, and benzoyl peroxide. Examples of commercially available accelerators for acrylic adhesives includes Lord® 19 and 19GB.
In one or more embodiments, the adhesive system may be applied to the substrate (wall panel 22 or clip 52) as a two part system (e.g., The acrylic adhesive as one component and the accelerator as another component). This application method is well known in the art, and involves the application of the two components from separate containers, allowing the two components of the adhesive system to react or interact with each other, and then introducing the mixture to the surface to be bonded.
The ratio of adhesive to accelerator may vary. In one or more embodiments, the mix ratio of adhesive to accelerator by weight may be from about 2:1 to about 4:1, in other embodiments from about 2.5:1 to about 3.5:1, and in other embodiments from about 2.7:1 to about 3.3:1. An exothermic reaction may produce heat buildup upon mixing and curing that may begin immediately. In one or more embodiments, handling strength is achieved at room temperature within about 4 to about 60 minutes from mixing. As will be understood by those skilled in the art, handling strength refers to the strength required for transportion or for following operations of the bonded article without disturbing the bond created by the adhesive. In one or more embodiments, substantially complete cure is achieved within about 24 hours at room temperature.
In one or more embodiments, the surfaces to be bonded may be pre-treated to remove grease, oxides, or other contaminants. Pretreatment of the surfaces may include any known method of preparing a surface for adhesive bonding, including cleaning the surface with high pressure air, wiping the surface down with water, or the use of quick vaporizing solvents.
In one or more embodiments, effective adhesives are characterized by a cured tensile strength at break (ASTM D638) of at least 25 MPa, in other embodiments at least 28 MPa, in other embodiments at least 30 MPa, and in other embodiments at least 32 MPa.
In one or more embodiments, effective adhesives are characterized by a cured elongation at break (ASTM D638) of at least 25%, in other embodiments at least 27%, in other embodiments at least 29%, and in other embodiments at least 30%.
In one or more embodiments, effective adhesives are characterized by a cured Young's Modulus (ASTM D638) of at least 800 MPa, in other embodiments at least 840 MPa, in other embodiments at least 880 MPa, and in other embodiments at least 895 MPa.
In one or more embodiments, effective adhesives are characterized by a cured Glass Transition Temperature (ASTM E1640-99) of at least 68° C., in other embodiments at least 70° C., in other embodiments at least 72° C., and in other embodiments from about 68 to about 80° C.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a lap shear at room temperature (ASTM D1002; Failure Mode C; 1.0″×0.5″ bond area; 0.010″ film thickness; 24 hr at room temperature cure; aluminum to aluminum) of at least 15 MPa, in other embodiments at least 17 MPa, in other embodiments 17.5 MPa, and in other embodiments 18.0 MPa.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a lap shear at hot strength [82° C.] (ASTM D1002; Failure Mode TLC; 1.0″×0.5″ bond area; 0.010″ film thickness; 24 hr at room temperature cure; aluminum to aluminum) of at least 10 MPa, in other embodiments at least 12 MPa, in other embodiments 13 MPa, and in other embodiments 13.5 MPa.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a lap shear after 500 hours salt spray exposure (ASTM D1002; Failure Mode TLC; 1.0″×0.5″ bond area; 0.010″ film thickness; 24 hr at room temperature cure aluminum to aluminum) of at least 15 MPa, in other embodiments at least 17 MPa, in other embodiments 17.5 MPa, and in other embodiments 18 MPa.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a lap shear after 14 days at 38° C. and 100% RH (ASTM D1002; Failure Mode C; 1.0″×0.5″ bond area; 0.010″ film thickness; 24 hr at room temperature cure; aluminum to aluminum) of at least 16 MPa, in other embodiments at least 18 MPa, in other embodiments 19 MPa, and in other embodiments 20 MPa.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a lap shear at −34° C. (ASTM D1002; Failure Mode C; 1.0″×0.5″ bond area; 0.010″ film thickness; 24 hr at room temperature cure; aluminum to aluminum) of at least 14 MPa, in other embodiments at least 15.5 MPa, in other embodiments 16.5 MPa, and in other embodiments 17 MPa.
In one or more embodiments, the bond performance of adhesive layer 65 may be characterized by a T-peel (ASTM D1876; Failure Mode C; 1.0″×3.0″ bond area; 0.010 film thickness; 72 hr at room temperature cure; aluminum to aluminum) of at least 3.0 N/mm, in other embodiments at least 3.5 N/mm, in other embodiments at least 4.0 N/mm, and in other embodiments at least 4.3 N/mm.
With reference back to
As is apparent from the drawings, a single mounting bracket 54 can provide mounting channels for the bottom of one wall panel 22 and the top of another wall panel 22. It should be appreciated that in one or more embodiments clips 52 and mounting brackets 54 may also be provided on the vertical flanges of wall panels 22. Additional clips may be particularly useful, and may be necessary, in cases where wall panel 22 has a significant height and therefore requires additional support along its vertical flanges. Clips 52 are interchangeable within attachment system 50, meaning that a clip 52 may be used on top flange 36, bottom flange 38, or vertical flanges.
A fastener 84, as shown in
An exemplary clip arrangement is shown in
As can be seen in
Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein.
This application gains the benefit of U.S. Provisional Application No. 61/049,190 filed Apr. 30, 2008, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61049190 | Apr 2008 | US |
