Patent Publication Number: US-2011076470-A1

Title: Method of making aesthetic panels with enhanced acoustic performance

Description:
FIELD OF THE INVENTION 
     The present invention relates to aesthetic paneling and more particularly to acoustic paneling. 
     BACKGROUND OF THE INVENTION 
     Decorative panels formed of wood and/or veneer are sometimes used as ceiling panels. The products presently on the market are heavy and difficult to install. Perhaps more importantly, these decorative panels do not provide any significant acoustical (sound absorption) value. These products have Noise Reduction Coefficient (NRC) values of under 0.50. One product currently on the market places a fiberglass board behind a perforated wood panel. The perforations allow sound to travel back to the acoustic fiberglass panel. Even this combined product has relatively poor acoustic performance, achieving a reported NRC of only 0.40-0.50. An improved acoustic panel is desired. 
     SUMMARY OF THE INVENTION 
     A method of manufacturing an acoustic ceiling panel having an aesthetic covering includes the steps of: providing a non-woven fabric having an outer major printable surface and an inner major surface; printing an image onto the printable surface of the non-woven fabric using a high-speed printing process, the image being provided from at least one image carrier; providing a base ceiling substrate having selected acoustical properties, the base ceiling substrate having an outer major surface; and adhering the inner major surface of the non-woven fabric to the outer major surface of the base ceiling substrate to form a laminated panel, wherein the non-woven fabric is acoustically transparent relative to the base ceiling substrate. 
     The above and other features of the present invention will be better understood from the following detailed description of the preferred embodiments of the invention that is provided in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate preferred embodiments of the invention, as well as other information pertinent to the disclosure, in which: 
         FIG. 1  is an exploded view of a panel of the present invention; 
         FIGS. 2-2F  are side views of embodiments of a ceiling panel of the present invention; 
         FIG. 3  is a perspective view of a ceiling made up of panels of the present invention; 
         FIG. 4  is a stylized image of a rotogravure printing press for use in printing an image on the nonwoven fabric of the panel of the present invention; 
         FIG. 5  is a flow diagram illustrating a method of making a panel of the present invention; and 
         FIG. 6  is a stylized image of a screen printing press for use in printing an image on the nonwoven fabric of the panel of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. 
     The present invention relates to a panel, such as a ceiling panel, that can be customized with a design or image to yield an aesthetically pleasing appearance without sacrificing acoustical. More specifically, a high-speed printing process, such as a rotogravure or screen printing method, is used to print an image on a semi-porous non-woven fabric that is then laminated to an underlying acoustical board. By semi-porous, it is meant that the fabric has sufficient fiber content to ensure good printability, but that that it is not so porous that it appears to have perforations (i.e., the pores in the fabric are not visible through the naked eye. In exemplary embodiments, the image that is printed on the non-woven fabric corresponds to a wood finish, including realistic coloring and grain. 
     With reference to  FIG. 1 , the two primary components of the panel  10  are a base ceiling substrate  12  having selected acoustical properties and a flexible non-woven fabric  20 . The base ceiling substrate  12  has a top major surface  14 , a bottom major surface  18  and side surfaces  16 . The base ceiling substrate  12  can be formed from a mineral board, fiberglass board, gypsum board, rigid foam board, hard board, or medium density fiberboard depending on the desired acoustical properties. All of these boards are known in the art for use as ceiling or wall panels. It is within the scope of the present invention to use other types of boards for the base ceiling substrate  12 . The only essential requirements for base ceiling substrate are that it be a rigid panel with desirable physical characteristics, such as sound insulating properties, and that it be capable of being suspended in a ceiling grid (or within a wall in embodiments). As those skilled in the art will appreciate, the base ceiling substrate  12  described herein can be constructed in any number of shapes or sizes as required by the intended use. The most common sizes are 2′×2′, 2′×4′ and 4′×4′ panels. 
     By varying the material of base ceiling substrate  12  behind the fabric layer  20 , the acoustical properties of the panel can be changed considerably from a high sound absorptive panel (e.g., fiberglass) to a sound reflective panel (e.g., gypsum board) as desired. The base ceiling substrate  12  may have a variety of densities, ranging from 2.5 to 20.0 lbs/ft 3 , and thicknesses, ranging from 0.40-3.0″. 
     The fabric layer  20  includes top, image-receiving, printable surface  22  and a bottom surface  24 . An adhesive layer  26  is shown on the bottom surface  24  of fabric  20  for adhering the fabric  20  to the top major surface  14  of the substrate  12 . The preferred non-woven fabric  20 , which may alternatively be referred to as a mat layer, is preferably formed from a non-woven blend of cellulosic and synthetic fibers. In one exemplary embodiment, the non-woven fabric  20  is a combination of fiberglass, cellulosic and synthetic fibers. In one exemplary embodiment, the blend is a combination of polyester, polypropylene, wood fiber, fiberglass and/or viscose rayon fibers. Depending on the application, the various constituent fibers can be varied. This construction yields a relatively lightweight sheet that is semi-porous and allows for limited absorption of printing ink. This limited ink absorption, in turn, yields a printable surface with desirable physical properties. In embodiments, the non-woven fabric layer  20  has a basis weight in the range of about 50-250 g/m 2  and a thickness of between about 0.010-0.200″. The porosity of the fabric  20  should be balanced between printability and sound transparency. That is, the fabric should not be so porous that print quality suffers or be so closed, such that sound transfer to the underlying substrate is adversely affected. One possible means by which porosity could be quantified is by performing air permeability tests. This combination of features yields a fabric layer  20  that is acoustically transparent, semi-porous, visually opaque (enough to acceptably mask the underlying substrate  12 ), printable and durable enough to be processed in high-speed printing processes and post-printing sizing operations. The fabric holds multiple layers of ink on its surface  22  without allowing the ink to penetrate to the base ceiling substrate layer and without “sealing off” the underlying substrate layer  12 . 
     As shown in  FIG. 1 , one exemplary image printed on the image receiving surface  22  is an image that achieves a wood appearance. Several coats of ink can be applied and the chosen grain added to achieve this appearance. In exemplary embodiments, the non-woven fabric  20  before the fabric  20  is laminated to the base ceiling substrate  12 . 
     The inner surface  24  of the non-woven fabric  20  is adapted to be laminated to the outer surface  14  of the base ceiling substrate  12  via adhesive layer  26 . In embodiments, the adhesive layer  26  includes an ethyl vinyl acetate (EVA) adhesive. The adhesive layer can be applied directly to either the surface  24  of the fabric  20  (as shown) or to the surface  14  of the base ceiling substrate  12 , or both. Pressure can be applied, such as using rollers (not shown), to facilitate a good bond between the surfaces. However, those skilled in the art will undoubtedly be familiar with the other suitable laminating techniques. The only requirement is that non-woven fabric  22  and base substrate  12  be adhesively joined in a manner that resists delamination and results in a smooth panel surface  22 . The laminated layers together constitute laminated panel  10 . 
     The present invention finds particular application in the creation of individual ceiling tiles or panels that are designed to fit within a standard ceiling tile grid, such as ceiling grid  50  shown in  FIG. 3 . These tiles come in a standard size of 23¾′ by 23¾″ (nominally 2′ by 2′). Other standard sizes are 2′ by 4′ and 4′ by 4′. 
       FIG. 2  is a side view of the ceiling panel  10 . As can be seen in  FIG. 2 , the ceiling panel  10  includes base ceiling substrate  12  laminated to non-woven fabric  20 . The adhesive layer  26  is not shown. 
       FIG. 2A  is a side view of an alternative embodiment of a ceiling panel  10 A. In this embodiment, the bottom surface  18  of the base ceiling substrate  12  is covered with a layer  28 , which may be a woven or non-woven layer selected to improve the look and/or feel of the surface  18  of the base ceiling substrate. In embodiments, the layer  28  is a nonwoven made of fiberglass and a combination of other cellulosic and synthetic fibers such as polyester, rayon, polypropylene, etc. 
       FIG. 2B  is a side view of an alternative embodiment of a ceiling panel  10 B. In this embodiment, one or more of the side surfaces  16  of the base ceiling substrate  12  are painted with a layer of paint  30 . In embodiments, the paint is a standard latex based paint and is used to conceal the edges of the substrate  12 . 
       FIG. 2C  is a side view of another alternative embodiment of a ceiling panel  10 C. In this embodiment, the non-woven fabric  20 ′ extends over and is adhered to one or more of the side surfaces  16  of the base ceiling substrate  12 . Although not shown in  FIG. 2C , the fabric  20  can also be sized to extend around the sides  16  of the base ceiling substrate to cover part or all of the bottom surface  18 . 
     Partial or complete covering or encapsulation of the side and bottom surfaces  16 ,  18  of the underlying base ceiling substrate  12  using the techniques described above in connection with  FIGS. 2A-2C  or below in connection with  FIGS. 2E and 2F  can be used to reduce shedding or dusting from the underlying base ceiling substrate. This type of shedding or dusting is a particular concern in hygienic environments, such as hospitals. For example, covering the side and/or bottom surfaces  16 ,  18  of a fiberglass panel can help reduce or eliminate the release of fiberglass fibers into the environment during installation or replacement or due to gusts from HVAC systems. 
       FIG. 2D  is a side view of another alternative embodiment of a ceiling panel  10 D. In this embodiment, the non-woven fabric layer  20 , which has the selected wood image printed thereon, is also coated with an additional coat of paint  30 . The paint can be selected to ensure that the non-woven fabric meets a desired targeted flame retardancy, such as a Class A rating on the ASTM E 84 Steiner Tunnel Test. The paint can be selected to also provide a desired visual attribute (e.g., sheen or gloss). This paint layer should be clear and not impact the visibility of the underlying wood-grain image/design that is printed on the non-woven fabric layer  20 . 
       FIG. 2E  is a side view of another alternative embodiment of a ceiling panel  10 E. This embodiment is similar to the embodiment of  FIG. 2A  only the top lateral edges of the base ceiling substrate  12 ′ are routed to form routed side surface  16 ′. These types of panels are called “reveal edged” panels. 
       FIG. 2F  is a side view of another alternative embodiment of a ceiling panel  10 F. In this embodiment, the side surface  16 ′ of the substrate  12 ′ is painted with a layer of paint  30 ′. The layer of paint can cover all of the side surface  30 ′ or any combination of the three surfaces that form the side surface  16 ′ (e.g., only the routed step portion). 
     As will be understood by those familiar with this art, routed edges are provided primarily for visual appearance. It should be understood that a single panel could have two different kinds of paint, e.g., paint layer  32  for providing some physical or visual attribute to the non-woven sheet  20 , such as sheen, gloss, better flame retardancy, modified acoustical properties (e.g., sound blocking), metallic finish, etc.) and paint layer  30  or  30 ′ for encapsulating the side faces  16  or  16 ′. 
       FIG. 5  is a flow diagram illustrating one exemplary process of making the ceiling panel described above. At step  502 , the non-woven fabric is provided in bulk form, such as from a roll or other bulk source of the non-woven fabric. 
     At step  504 , the non-woven fabric is fed to a high-speed printing press, such as a high speed automated rotogravure or screen printing press. 
     At step  506 , an image is printed onto a surface of the non-woven fabric from an image carrier (e.g., gravure cylinder in a rotogravure printer or screen/stencil of the screen printing pressed) used in the high-speed printing system. 
     At step  508 , it is determined whether additional layers of ink are required to refine, further define and/or complete the printed image. Forming a wood grain pattern as shown in  FIG. 1 , for example, will typically require 2 to 5 different printing steps. 
     If at step  508  additional printing is required, the method returns to step  504  to provide the non-woven fabric to one or more high-speed printing presses for printing additional layers. If at step  508  additional printing is not required, the method proceeds to step  510 . 
     At step  510 , optionally, a backer layer is adhered to the back surface of the base ceiling substrate. 
     At step  512 , the non-woven fabric layer is adhered to the base ceiling substrate. 
     At step  514 , the structure (base ceiling substrate with adhered backer and non-woven fabric layer) is cut to size (e.g., 2′×2′, etc.). For example, an image can be printed upon  4 ′ wide roll of non-woven fabric using a high-speed printing process. Thereafter, the fabric can be laminated in an assembly line process onto a series of 4′ by 8′ sections of base ceiling substrate. A total of eight of the aforementioned nominal  2 ′ by 2′ tiles, four  2 ′ by 4′ tiles and two 2′ by 4′ tiles can then be cut from each of the resulting  4 ′ by 8′ laminated panels. 
     At step  516 , the edges of the base ceiling substrate are optionally routed and/or painted, and the process ends at step  518 . 
     It should be understood that while a wood finish image is one preferred image for printing on the non-woven fabric, the invention can be used to form any of a number of pictures with a pleasing aesthetic appearance. Moreover, the process can be employed to form a number of different laminated panels  10 , each with a different individual image that can then be arranged to form a larger, composite picture. A number of laminated panels  10  can be assembled within a ceiling  50  to form a composite picture. Of course, the method can readily be used to form a single decorative panel  10  or to form a number of panels  10  with images that do not necessarily form a composite picture. 
     With reference to  FIG. 4 , a rotogravure printing press  100  is shown. Rotogravure is a type of intaglio printing process, in that it involves engraving the image onto an image carrier. In gravure printing, the image is engraved onto a copper cylinder. Rotary gravure presses are the fastest and widest presses in operation, printing everything from narrow labels to 12 feet (4 m)-wide rolls of vinyl flooring. In embodiments, the press  100  is used as the high-speed printing press for printing the image onto the non-woven fabric. It should be understood that the press  100  can be one of a series of presses  100 . The number of units varies depending on what colors are required to produce the final image. 
     Each rotogravure printing press  100  includes an ink fountain  102 , an engraved gravure cylinder  104 , which includes the image carrier corresponding to the image to be printed, an impression roll  108 , a optional doctor blade  106  and a dryer (not shown). The nonwoven sheet  110  is continuously fed to the rotogravure printing press  100  for transfer of the image from the image carrier of the gravure cylinder  104  to the image receiving side of the nonwoven fabric  110 . Additional operations may be in-line with a gravure press or presses  100 , such as painting and sizing operations. 
     While the press  100  is in operation, the engraved cylinder  104  is partially immersed in the ink fountain  102 , filling the recessed cells of the engraved cylinder  104 . As the cylinder  104  rotates, it draws ink out of the fountain  102  with it. The doctor blade  106  is angled toward the cylinder  104  and acts as a squeegee to scrape the cylinder  104  before it makes contact with the nonwoven fabric  110 , removing ink from the non-printing (non-recessed) areas. The doctor blade  106  is normally positioned as close as possible to the nip point where the fabric  110  meets the cylinder  108 . This is done so ink in the cells has less time to dry out before it meets the fabric  110  via the impression roller(s)  108 . Next, the nonwoven fabric  110  gets sandwiched between the impression roller  108  and the gravure cylinder  104 . This is where the ink gets transferred from the recessed cells to the printed side of the nonwoven fabric  110 . The capillary action of the fabric  110  and the pressure from impression roller(s)  108  draw/force the ink out of the cell cavity and transfer it to the fabric  110 . The purpose of the impression roller  108  is to apply force, pressing the fabric  110  onto the gravure cylinder  104 , ensuring even and maximum coverage of the ink. Then, the fabric  110  goes through a dryer to completely dry before further processing, such as going through the next color unit and absorbing another coat of ink. 
     The gravure cylinder  104  can be digitally engraved with the image by a diamond tipped or laser etching machine. On the gravure cylinder  104 , the engraved image is composed of small recessed cells (or “dots”) that act as tiny wells. Their depth and size control the amount of ink that gets transferred to the fabric via a process of pressure, osmosis, and electrostatic pull. 
     In a trial, average speeds of 150-200 ft/min were observed for printing a wood grain image onto a non-woven fabric as described above. With a lane width of 4 feet, that amounts to a production capacity of 600-800 ft 2 /min. Lane widths of 8 feet could also be used, doubling the production capacity to 1200-1600 ft 2 /min. Even higher yields can be achieved with wider lanes. To put into perspective, an ink jet printer printing the same image onto a similar fabric would operate at only about 2-4 ft/min. 
     As mentioned above, another alternative high-speed printing technique which can be employed to transfer an image from an image carrier to the fabric is screen printing.  FIG. 6  illustrates a screen printing press  600 . The screen printing press includes a screen  612  that is made from a piece of porous, finely woven mesh fabric over a frame  604 . Most mesh is made of man-made materials such as steel, nylon, and polyester. Areas of the screen are blocked off with a non-permeable material to form a stencil  610 , which is a negative of the image to be printed; that is, the open spaces are where the ink will appear. The screen is placed over the nonwoven fabric  602  disclosed above. Ink  606  is spread across the mesh opening with a fill bar (also known as a floodbar) (not shown). The screen is lifted to prevent contact with the underlying non-woven fabric  602  while a slight amount of downward force is applied and the fill bar is pulled across the front of the screen. This effectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. A squeegee (rubber blade)  608  then moves the mesh down to the fabric layer  602  as it is pushed to the rear of the screen. The ink that is in the mesh opening is pumped or squeezed by capillary action to the fabric  602  in a controlled and prescribed amount, i.e. the wet ink deposit is equal to the thickness of the mesh and or stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the fabric  602  (called snap-off) leaving the ink upon the fabric  602 . In this manner, the IMAGE is transferred to the fabric  602 . High speed printing can be achieved by employing automatic presses. 
     While  FIG. 6  illustrates a “flat-bed” type of screen printing, other types of screen-printing, such as “cylinder” or “rotary” may be used. 
     In exemplary embodiment of the ceiling panel described herein, the ceiling panel has excellent acoustic properties, such as a NRC rating of 0.5 or greater, and more preferably 0.75 or greater, and most preferably 0.8 or greater. NRC is a scalar representation of the amount of sound energy absorbed upon striking a particular surface. An NRC of 0 indicates perfect reflection and an NRC of 1 indicates perfect absorption. NRC is an arithmetic value average of sound absorption coefficients at frequencies of 250, 500, 1000 and 2000 Hz indicating a specimen&#39;s ability to absorb sound. NRC values higher than 1.0 are sometimes reported due to the way the number is calculated in a laboratory. A test material&#39;s area does not include the sides of the panel (which are exposed to the test chamber) which vary due to its thickness. A certain percentage of the sound is absorbed by the side of the panel due to diffraction effects. While being acoustically transparent and semi-porous, the nonwoven fabric is preferably substantially imperforate. That is, the nonwoven fabric, while semi-porous, need not be perforated, such as by punch holes, wheel abrasions, embossing or the like, in order to obtain the desired acoustical transparency. This feature helps provide an improved image-receiving surface and a smooth look, touch, and feel. 
     Excellent results were observed in a ceiling panel having an underlying base ceiling substrate that was a fiberglass board having a thickness of 1″ and a density of 4 lb/ft 3 . A non-woven fabric as described above having a basis weight of 80-100 g/m 2  and a thickness of 0.010-0.012″ was adhered to the top surface of the base ceiling substrate. The fiber orientation of the non-woven fabric was random. The adhesive was LAW 1913 VETAK adhesive provided in about 2-6 g/m 2 /ft 2 . 
     The present disclosure includes that contained in the appended claims, as well as that of the foregoing description. Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly to include other variants and embodiments of the invention that may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.