HK1128010A - Ceiling tile construction - Google Patents

Description

Ceiling decoration board structure

Technical Field

The present invention relates to improvements in suspended ceiling tile and in particular to a novel combination of synthetic material and mechanical improvements to the structural body of such a tile.

Background

Conventional suspended ceiling tile is typically relatively light in weight, or more precisely, low density. This low weight is advantageous for manufacturing, transportation, handling and installation reasons. However, low density conventional ceiling tile often has the disadvantage of being relatively soft and brittle, making it vulnerable to damage during handling, handling and installation. Finally, in use, prior art trim panels are often damaged when they are temporarily moved in order to reach the space or plenum above them, or are accidentally knocked or hit by objects moving below them. Another problem encountered with some prior art tile is the tendency to sink from the ceiling plane, especially under wet conditions. Often times, more durable, sink resistant product structures are more expensive to manufacture and therefore must be sold at an ultra-high price. There is a need for a cost effective ceiling tile that is more damage and sag resistant than the ceiling tile structures commonly found in the prior art.

Disclosure of Invention

The present invention provides a ceiling tile structure that is relatively inexpensive to manufacture and is of a robust nature such that it is relatively damage resistant. It has been found that physically modifying a synthetic panel composed of natural materials can meet both the economic and durability requirements.

The synthetic material comprises a homogeneous mixture of gypsum and cellulose fibers. Structural panels formed from these materials are typically manufactured in a felting-like process known in the industry and can be modified according to the present invention by making a plurality of holes in the side of the panel that ultimately becomes the interior or front face of the tile.

These holes advantageously help reduce the effective density of the sheet material and increase the Noise Reduction Coefficient (NRC) exhibited by the tile. These cellulosic fibers are uniformly distributed and randomly positioned throughout the board and help produce a board with a high modulus of rupture (MOR) value that easily and cleanly exceeds the requirements of ceiling tile applications and is exceptionally highly resistant to sagging. Furthermore, the composite nature of the panel produces a sound insulating effect, reducing reflected and transmitted noise. The constituent fibers help physically lock the gypsum particles in place, effectively eliminating the potential for the particles to dust or spill from the interior of the holes that could otherwise be produced by mechanical cutting in the board during the disclosed shipping, handling and service. Similarly, the embedding of such cellulose fibers in a gypsum matrix produces a product that can be easily and cleanly cut without excessive breakage and without the presence of large amounts of loose fiber ends.

Several variations of the ceiling tile of the present invention are disclosed. In a basic configuration, the reduced density and sound absorbing holes are blind holes cut by a suitable drilling operation (cut), for example from the side of the tile facing the inside of the room or space when finally installed. As an improvement, a decorative porous fabric may be laminated on the room side of the tile over the holes to effectively hide them from view and increase the sound absorbing properties of the holes.

In another variant of the invention, the board is cut by means of a suitable punch or other tool having a punching function, that is to say extending through its thickness.

Free sound transmission through perforated facia is objectionable in applications where the back of the panel is laminated with a suitable non-porous fabric such as heavy paper stock. The room side is laminated with a porous fabric and these punched holes can be hidden on the visible side or room side of the tile. In both drilled and punched configurations, the holes may be of uniform size and spacing, or may be of different sizes and/or may be randomly spaced.

A particularly suitable panel construction for forming the structural core or body of the tile of the present invention has been found to be disclosed in us patent No. 5320667, the disclosure of which is incorporated herein by reference. Such panels comprise relatively inexpensive natural materials that are combined in a unique panel forming process. Ceiling tile body compositions made primarily of gypsum and cellulose fibers such as disclosed in this patent exhibit a high degree of sag resistance and, in addition to the aforementioned low sag performance, wherein the holes are drilled, machined or otherwise cut, are easily and neatly finished without chipping, fraying or the like with edge relief or portions. Furthermore, the ceiling tile is particularly strong, so that it has a high degree of damage resistance under ordinary circumstances.

Drawings

FIG. 1 is a reverse mirror plan view of a ceiling tile according to the present invention;

FIG. 2 is a cross-sectional view of a portion of the ceiling tile of FIG. 1;

FIG. 3 is a cross-sectional view of a second embodiment of a ceiling tile constructed in accordance with the present invention; and

FIG. 4 is a still sectional view of another embodiment of the present invention;

Detailed Description

Fig. 1 and 2 diagrammatically illustrate a ceiling tile 10 according to one form of the present invention. The tile 10 is conventionally rectangular in plan view, the illustrated unit is square, and it should be understood that the tile may be elongated from the tile shown. More specifically, the tile 10 is typically manufactured in plan view dimensions at approximate nominal dimensions of 2 feet by 2 feet, 2 feet by 4 feet, 4 feet by 4 feet, 2-1/2 feet by 5 feet, 5 feet by 5 feet, and 1 foot by 6 feet. The unusual strength of the disclosed tile or core enables the use of relatively large panels without excessive risk of breakage. The tile 10 is relatively thin compared to the planar dimensions, having a thickness of, for example, 1/2 inches or less, nominal dimension. The tile 10 is preferably cut from a larger preformed sheet, ideally having a thickness corresponding to the thickness of the tile.

The tile 10 features a plurality of holes 11, the holes 11 being distributed substantially entirely along the room-side surface 12. These holes 11 are blind holes in the sense that they do not extend completely through the thickness of the tile 10. These holes 11 are formed so short that a wall 13 is left which is relatively thin compared to the thickness of the tile 10 at the back side of the tile, i.e. the side 14 opposite the room side 12. In the example shown in fig. 1 and 2, these holes 11 are in a regular form and of uniform size with a diameter of, for example, 3/8 inches. These holes 11 help to increase the Noise Reduction Coefficient (NRC) of the panel, and at the same time reduce the weight and effective net density of the tile 10.

The tile 10 according to the present invention is a composite of natural materials comprising primarily gypsum and cellulose fibers. In the prior art, these materials have previously been combined in various forms, proportions and processes to produce panels for construction purposes, however, these prior art products have not apparently been considered commercially for ceiling tile applications. A preferred composite material for making the suspended ceiling tile panels of the present invention is disclosed in the aforementioned us patent 5320677. Gypsum-based materials typically exhibit low tensile strength and, as a corollary, have very limited cohesiveness, making them relatively brittle or fragile. Gypsum is also relatively heavy or dense. In part, these characteristics explain why gypsum-based materials are not generally considered for suspended ceiling tile applications. On the other hand, cellulosic fiber gypsum composite materials can exhibit relatively high tensile strength to weight ratios. In addition, the cellulose fiber gypsum composition exhibits relatively high fire resistance, which is of great benefit in ceiling tile applications. Still further, it has been found that a properly manufactured cellulose fiber/gypsum composite can provide exceptional sag resistance, which is a very important characteristic in ceiling tile products. The ratio of cellulose fiber to gypsum is between about 8% to about 30%, and preferably between 8% to 15% by weight of cellulose fiber to corresponding gypsum. The cellulose fibers and gypsum preferably comprise at least about 90% and more preferably at least about 95% of the dry solids of the finished board from which the tile 10 or structural board described below is made. Additives for facilitating the size mixing/felting process of the tile or board, or for enhancing its properties, such as set accelerators, retarders, weight reducing filler materials and the like, may constitute a balance of the weight of the tile or board. The composite board is characterized by cellulose fibers uniformly and randomly positioned throughout the gypsum matrix.

A very desirable property of cellulosic fiber/gypsum composites, which does not appear to be recognized in processed goods, when contrasted with the Arough @ structure, is that they can be cut with a knife or another machining means without creating excessive residual loose dust or loosely adhered particles or fibers in the remaining cut surface. Furthermore, the cellulose fiber/gypsum composite allows the holes 11 to be formed very close to the edges of the tile without the risk of high material breakage between the holes and the edges. The synthetic material disclosed in the aforementioned us patent 5320677 is produced from gypsum which has been subjected to calcination under pressure in a dilute cellulose fiber slurry, dewatering and subsequent rehydration to recrystallize and thereby interlock in or around the cellulose fibers, and is particularly suitable for use in the practice of the present invention. This material, in addition to its higher strength/weight characteristics, has been found to have significant sag resistance characteristics. Furthermore, this material is particularly suitable for producing prefabricated panels or trims, which, after mounting, are subsequently machined or otherwise cut to form holes 11 for weight reduction and noise absorption, as well as any edge treatment such as the production of notches 16, as shown, for example, in fig. 2. The intimate bonding of the dihydrate crystals and the cellulose fibers results in a clean, relatively smooth cut surface, substantially all free of loose gypsum particles and/or cellulose fibers, and partially attached or hanging fibers. The clean cuttability of the preferred materials produces a quality appearance that does not require an auxiliary finishing operation. Another important benefit of the combined uniform structure of the gypsum/cellulose fiber composite is that it resists falling in the area of the machining, drilling or otherwise making the hole 11 during subsequent handling, transportation, installation and maintenance. Such a fall can otherwise create problems, particularly for the installer and the end user. The material removed from forming the holes 11 can be 100% recycled to the raw material used to make the preformed sheet from which the tile 10 is made. The tile 10 may be painted or coated with a suitable appearance coating before or after the holes 11 are drilled or otherwise cut.

Referring to fig. 3, in which the above-required high NRC performance is obtained only by arranging the holes 11, a ceiling tile 20 may be formed by providing a porous fabric 21 on a structural body 22. The porous fabric 21 may be a non-woven fiberglass scrim (scrim) as is known in the industry. The fabric 21 may be laminated to the body 22 using a suitable adhesive known in the art and initially preferably applied to the structural body 22. The structural body 22 is substantially identical in composition and form to the ceiling tile described in relation to fig. 1 and 2. In the illustration of fig. 3, the structural body 22 is illustrated without the edge portion 16 of the tile 10 of fig. 1 and 2. Since these holes 11 of the structural body 22 are blind holes, air does not pass or suck through them, and airborne dust is not sucked onto the fabric 21, so that ghosting of the holes 11 does not occur on the outer surface of the fabric 21. If desired, more than one porous or fabric layer may be laminated to the room side of the body 22 to increase the NRC of the tile 20 and/or to achieve a desired appearance.

Fig. 4 illustrates a cross-sectional view of a suspended ceiling tile 30 having a structural core or body 31 and a noise barrier 32 laminated to the back or rear of the body. The body 31 may be formed from materials and processes like those described above for the body of the tile 10 of fig. 1 and 2. Holes 33 for weight reduction and sound absorption are cut into the structural body 31 after the body is built up and before the insulation sheet 32 is laminated. The holes may preferably be cut using a punch known in the art or by a drill or other tool. The sound barrier 32 is an imperforate web, such as paper formed from heavy paper stock used in wallboard manufacture. The noise insulation panel 32 is preferably laminated to the core using a suitable adhesive. If desired, a porous fabric or sheet may be provided between the body 31 and the barrier sheet 32 to increase the NRC of the tile.

Although not shown in the drawings, modified versions of the ceiling tile of fig. 3 and 4 may be provided with edge portions such as the rebates 16 seen in fig. 2, if desired. Any of the ceiling tiles 10, 20 or 30 may be painted for appearance purposes and for potential noise absorption benefits.

The tile structures 10, 22 and 31 all have the feature of being preferably manufactured from a cellulosic gypsum composition of the type disclosed in us patent 5320677, and subsequently being manufactured from a felting process into rigid boards or preforms provided with a plurality of spaced apart holes which are effectively open at the front or room face side of the tile. The holes are drilled by using a suitable drill or punched out using a tool punch or otherwise machined into the composite sheet. As described above, a homogeneous mixture of randomly positioned cellulose fibers and gypsum particles forming a tile or tile structural core creates a structure that is fire resistant, dimensionally stable, and particularly resistant to sagging. Still further, an important feature provided by the present invention is that the material has anti-drop properties when the sheet material of the structure is cut to form the apertures and any edge portions. The intimate association of the cellulose fibers and gypsum particles reduces the likelihood of such particles falling down, as well as the likelihood of the fibers or portions thereof becoming loose and unsightly at any cut hole or cut edge portion. Preferably, the holes 11, 33 are of sufficient size and number to reduce the weight of the tile 10 or body 22, 31 by at least about 10%, more preferably at least about 20% relative to the weight of such a tile or panel without the holes.

While the invention has been shown and described with reference to particular embodiments, this is for the purpose of illustration and not of limitation, and other variations and modifications of the specific embodiments herein shown and described will be apparent to those skilled in the art, all within the intended spirit and scope of the invention. Accordingly, this patent is not intended to be limited in scope or effect to the specific embodiments herein shown and described nor in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.

Claims (19)

1. A ceiling tile having a rectangular shape and having nominal dimensions generally between 2 feet by 2 feet and 5 feet by 5 feet, the tile being formed from gypsum and cellulose fibers formed into a felted board by uniformly mixing the fibers and gypsum in a water-based slurry, the gypsum and cellulose fibers then subjecting the board to a pressing and drying process at a desired board thickness, the dried board being processed to form a plurality of holes in its surface through at least most of the thickness of the board, the total volume of the holes being sufficient to reduce the weight of the board by at least 10% and increase the NRC exhibited by the board such that the increased NRC is higher than the NRC of an otherwise identically composed and non-porous board.

2. A ceiling tile as set forth in claim 1, wherein said holes are cut from one side of the sheet and are blind.

3. A ceiling tile as set forth in claim 1, wherein said board is covered with a porous fabric.

4. A ceiling tile as set forth in claim 1, wherein said holes are formed through said sheet material having an imperforate sheet laminated to one side thereof.

5. A ceiling tile as set forth in claim 4, wherein said board is covered with a porous fabric laminated on the side opposite to the side on which said non-porous board is laminated.

6. A ceiling tile as set forth in claim 1, wherein said board is made of cellulose fibers and gypsum, the gypsum having been calcined under pressure in a water slurry and thereafter recrystallized in the spaces and interstices of the fibers to intimately bond the gypsum particles and the cellulose fibers.

7. A generally planar ceiling tile for suspended ceilings, the tile having a rectangular shape in plan view and being relatively thin in the vertical direction compared to its planar dimension, the tile having a structural body formed from a uniform composition of gypsum and cellulose fibers together constituting substantially at least 90% of the weight of the body, the body being formed by a felting-type process whereby the cellulose fibers are uniformly and substantially randomly distributed and oriented in the body so that the body exhibits substantially identical mechanical properties in both directions of the rectangular tile profile, the body having a uniform thickness over a major portion of the area spanned by its rectangular shape, a plurality of spaced apart holes being cut into the body on the side of the body adapted to face the interior of a house, wherein the tile is mounted and distributed over substantially all of said one side, the holes are of sufficient size and number to reduce the weight of the body by at least 15% and to increase the NRC of the body.

8. A ceiling tile as set forth in claim 7, wherein the composite-made body is a product formed by calcining gypsum under pressure in a slurry and then recrystallizing the gypsum on and in cellulose fibers.

9. A ceiling tile as set forth in claim 7, wherein said holes are blind holes produced as holes drilled to a depth less than the thickness of the structural body.

10. A ceiling tile as set forth in claim 7, wherein the perimeter of the structural body is cut to form a notched edge such that the surface on which said holes are formed is slightly less in profile than the entire planar profile of the structural body, and the perimeter region of the body lies in a plane between said surface and the opposite back face of the body.

11. A ceiling tile as set forth in claim 7, wherein a porous fabric is laminated to said surface, said porous fabric serving to increase the NRC of the tile.

12. A ceiling tile as set forth in claim 7, wherein said holes are cut through the entire thickness of the structural body.

13. A ceiling tile as set forth in claim 12, including an imperforate web laminated on a surface of said structural body opposite the front surface.

14. A ceiling tile as set forth in claim 13, wherein said imperforate web is a relatively thick paper stock.

15. A process for making a ceiling tile comprising calcining gypsum under pressure in a dilute aqueous slurry having at least 90% solids, wherein said at least 90% solids contain from about 8% to about 30% cellulose fibers and the corresponding gypsum complement, dewatering the slurry prior to rehydrating the gypsum, and rehydrating and recrystallizing the gypsum in and around the spaces in the cellulose fibers to form a rigid preformed synthetic panel, and after solidifying the panel by rehydration and recrystallization of the gypsum, cutting a plurality of holes in the surface of the preformed panel to reduce the effective weight of the panel and increase its NRC.

16. A method as set forth in claim 15, including covering said pores with a porous fabric adhered to said surface.

17. A method as set forth in claim 15, wherein said holes are blind holes formed by cutting to a depth less than the thickness of the sheet.

18. A method as set forth in claim 15, wherein said holes are cut through said plate.

19. A method as set forth in claim 18, wherein one side of said sheet material is covered by an imperforate web adhered to said side.