Patent Application
20140000978
The invention relates to building materials and systems and, in particular, to an acoustical panel for constructing monolithic ceilings and interior walls.
Sound absorption in buildings is commonly achieved with ceiling tiles carried on a suspended grid. Generally, the sound absorbing capacity of the tiles is achieved by material selection and/or characteristics of the room facing surface. Ceiling tile installations have the advantage of affording ready access to the space above the ceiling, but the divisions between the tiles, even when the grid is concealed, remain visible. Architects and interior designers have long sought a monolithic, texture free look in an acoustical ceiling particularly when there is no expected need for access to the space above the ceiling. Ordinary gypsum panel drywall ceiling construction does not achieve a sufficiently high noise reduction coefficient (NRC) that would qualify as acoustical. Perforated gypsum panels may achieve an acceptable NRC level but they are not monolithic in appearance.
The invention resides in the discovery that ordinary gypsum panels, such as drywall sheets, can be modified to construct an acoustical ceiling or wall with a monolithic plain face and surprising acoustical properties. Such panels can achieve an NRC of 0.70 or more.
In accordance with the invention, the gypsum core is made with a multitude of perforations or holes distributed throughout its planar area. The perforations or holes are restricted, preferably with a painted non-woven porous scrim fabric or veil at the front face and, optionally, a non-woven porous acoustical fabric at the back side.
The gypsum panel can be made, for example, by perforating standard sheets of drywall and thereafter covering the perforated sides of the sheet with additional laminated sheets or layers. These perforating and laminating steps can be performed by the original manufacturer of the drywall sheets or by a separate entity independent of the original drywall manufacturer.
Variations in the construction of the gypsum panel are contemplated. Common among these variations is a panel with a perforated gypsum core and with a face covered by a structure that is porous while appearing essentially imperforate to the unaided eye.
The disclosed gypsum-based panels can be installed in the same manner or a like manner as ordinary drywall. For ceiling applications, the acoustical panels of the invention can be screwed to a conventional drywall suspension system of grid tees or “hat channels” carried on black iron channels typically used in commercial applications or they can be attached to wood framing more often used in residential construction. Acoustical walls can be built by attaching the inventive acoustical panels to vertical studs, serving as spaced support elements. It will be seen that the inventive panels can be readily taped and painted like ordinary drywall, using the same or similar materials, equipment, tools and skills, to produce a smooth monolithic ceiling or wall.
Referring now to
Acoustical panels 20 are attached to the lower sides of the grid tees 12, 13 with self-drilling screws 21. The illustrated acoustical panels are 4 ft. by 8 ft. in their planar dimensions, but can be longer, shorter and/or of different width as desired or practical. The size of the panel 20 and spacing of the grid tees 12 and 13, allows the edges of the panel to underlie and be directly attached to a grid tee, assuring that these edges are well supported.
Referring to
Sheets 29, 30 are laminated to both full sides of the perforated drywall sheet thereby at least partially closing both ends of the perforations 28. At a rear side of the drywall, the backer sheet or web 30 is preferably an acoustically absorbent non-woven fabric known in the acoustical ceiling panel art. By way of example, the backer fabric can be that marketed under the trademark SOUNDTEX® by Freudenberg Vliesstoffe KG. It has a nominal thickness of 0.2 to 0.3 mm and a nominal weight of 63 g/m2. Specifically, the main components of this non-woven fabric example are cellulose and E-glass with a synthetic resin binder such as polyacrylate, poly(ethylene-CO-vinylacetate). Alternatively, for example, the backer sheet 30 can be a porous paper layer. The sheet 30 can be provided with a suitable adhesive for binding it to the rear paper side 25 of the modified drywall sheet 22.
At a front side of the drywall sheet 22, a sheet or web in the form of a non-woven fabric scrim layer 29 is attached with a suitable adhesive. The facing layer or sheet 29 is porous; a suitable material for this application is that used commercially as a cover or face for conventional acoustical ceiling panels. An example of this type of veil material is that marketed by Owens Corning Veil Netherlands B.V. under the product code A125 EX-CH02. This scrim fabric comprises hydrated alumina fiberglass filament, polyvinyl alcohol, and acrylate copolymer. The unpainted scrim 29 has a nominal weight of 125 g/m2 and an air porosity, at 100 Pa, of 1900 l/m2 sec. To avoid blocking the face scrim 29, the adhesive can be initially applied to the panel or sheet 22. The facing sheet 29 should be sufficiently robust to withstand field finishing operations described below. It should also be compatible with drywall joint compound or similar material and commercially available paints, typically water-based paints such as that described below.
The panel 20 with other identical panels is hung on the grid 11 in the same manner as ordinary drywall is installed. Similarly, as shown in
After the joint compound 34 has been sanded or sponged smooth, the front sheets 29 and remaining joint compound are painted with a commercially available acoustical paint 31 used for painting acoustical tile. An example of a suitable water-based paint, sometimes referred to as a non-blocking paint, is available from ProCoat Products, Inc. of Holbrook, Me. USA, sold under the trademark ProCoustic. To improve the uniformity of the finished appearance of the ceiling, the taped joints can be covered with strips of the veil fabric 29, wide enough to cover the joint compound, prior to painting. The paint application should leave as much porosity through the layer 29 as is desired but leave the appearance of an essentially imperforate surface to the unaided eye so that the perforations 28 are not seen. Alternatively, where high NRC is not necessary, satisfactory results can be obtained by using a conventional primer and a coat of interior latex paint 31 to complete the installation of the ceiling 10. When the term monolithic is used herein, it is to denote that essentially the entire visible surface of a ceiling or wall appears to be a seamless expanse without joints.
A ½ or ⅝ in. drywall-based panel 20, having the described perforation arrangement and front and rear sheets 29, 30 and customary space behind the panel can exhibit NRC values up to and above 0.70, a rating equal to the performance of better-grade acoustical ceiling tile.
Presently, the preferred characteristics of the gypsum-based core 24 are:
Following are airflow characteristics of the backer layer 30 of the non-woven SOUNDTEX® material described above and the face layer 29 of the non-woven scrim material described above before and after painting with a proprietary acoustical coating and the acoustical ProCoustic coating.
The tables printed below show NRC values for the inventive board and boards of other constructions for comparison purposes. As in the preceding table, unless otherwise noted, the backer is the SOUNDTEX® material and the face is the scrim identified above.
Panel E of Test I had a heavy manila paper face with a basis weight of 263.50 gm/m2, a caliper of 17.22 mils, a density of 0.60 c/m3 and a porosity of 58.97 seconds. This test sample illustrates that a face, although porous, but with too high an air flow resistivity is unsuitable for use with the invention. Panel BB of Test I indicates that a face with a higher air flow resistivity (see above table) than a painted scrim face can achieve a satisfactory NRC.
The acoustical panel of the invention can be manufactured in additional ways and with different constructions, but maintaining the perforations effectively restricted on at least the face (room) side of a completed panel. For example, where high NRC values are not needed, the rear layer 30 may be omitted. Porous paper may be substituted for either of the non-woven layers 29, 30.
It has been further discovered that NRC can be measurably increased by orienting the perforations obliquely to the plane of the panel. Such a construction is illustrated in
The foregoing disclosures involve modification of a conventional drywall sheet to convert it to the acoustical panel of the invention. However, the inventive acoustical panel can be originally manufactured with perforations in the gypsum core while it is being originally formed or immediately after it is formed and prior to attachment of one or both cover sheets or layers to its front face and rear side. The perforations, for example, can be cast into the gypsum body. The cross-section of the perforation in the various disclosed embodiments can be accircular when not drilled.
It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.
