MXPA01005163A - Durable acoustical panel and method of making the same - Google Patents

Abstract

An acoustical panel has a fiberboard which includes a fibrous filler and a base binder, and a nodulated overlay disposed on the fiberboard, wherein the overlay includes nodulated wool and an overlay binder and has a substantially smooth surface. In one embodiment of the present invention, the fibrous filler is mineral wool and the base binder is granular starch. In another embodiment of the present invention, the nodulated wool is nodulated mineral wool and the overlay binder is cooked pearl cornstarch. A method of making the durable acoustical panel in accordance with the present invention is disclosed. Initially, an aqueous slurry comprising a fibrous filler, a base binder, and water is formed. The aqueous slurry is deposited onto a moving foraminous support wire to form an aqueous felt, thereby creating a continuous process. Thereafter, the aqueous felt is de-watered to form a wet felt. The wet felt is coated with an aqueous overlay comprising nodulated wool, overlay binder, and water and has a substantially smooth surface. Finally, the wet felt and aqueous overlay are dried to form the ceiling panel.

Description

DURABLE ACOUSTIC PANEL AND METHOD TO MANUFACTURE THE SAME FIELD OF THE INVENTION The present invention relates generally to the field of mineral cartons. More particularly, the present invention relates to a laminated panel having a mineral board and a modulated mineral wool coated thereon and with a method for manufacturing the same.

BACKGROUND OF THE INVENTION Acoustic tiles provide aesthetic appearance, or acoustic modification or damping, accessibility to space above the roof plane, and simple installation and removal. Although such tiles have those characteristics they must be produced at a low cost. To accommodate these characteristics, tiles are constructed using strong but relatively expensive materials such as newspaper, pearlite, clays, mineral wool and binder, such as starch. The acoustic damping, however, requires that the tile be porous, especially on the surface of the tile. Examples of porous tiles are US Pat. Nos. 1,769,519, 4, 911,788 and 5,071,511 are described. Currently, consumer interest is directed to the surface durability of tiles. Unfortunately, porous materials are not as durable as denser materials. The consumer not only desires the acoustic deadening provided by the porous materials, but also expects the tiles to be free of imperfections once installed. Additionally, the roof must remain free of imperfections after the panels have been removed to gain access to the full space above the tiles. Although tiles made of porous mineral board have acceptable noise reduction coefficients (NRC), porous mineral hardboards are soft and can be damaged during installation or removal. For example, surface indentations can easily be created on the porous mineral board with the finger pressure of the installer, and similarly surface scratches can be created by pushing a tile through a support structure in the form of a metal grid. To improve the surface durability, the percentage by weight of a few of the materials used in the construction of the mineral board can be increased, especially the binder and the mineral wool. However, the resulting mineral board, and the tile formed therefrom, is heavy and expensive. Alternatively, laminated structures have been used to provide the desired characteristics of acoustic damping, surface durability and light weight. For example, one such laminated structure is formed by placing a durable thin woven sheet of glass or polymer over the porous mineral board. Although this sheet can provide the desired NRC and surface durability properties, it is expensive to manufacture. Laminated structures that do not employ a thin canvas are discussed in U.S. Patent Nos. 3,283,849 and 3,444,956. Despite the existing shingles formed of mineral board, there is still a need for a durable acoustic panel that provides acoustic damping, has a durable surface, is light in weight, and is produced cheaply. In addition, there remains a need for a method for manufacturing such a panel. Accordingly, it is the provision of a durable acoustic panel that satisfies those needs to which the present invention is primarily directed.

BRIEF DESCRIPTION OF THE INVENTION This invention overcomes the disadvantages of the prior art by providing a durable, lightweight acoustic panel which has a substantially smooth, durable surface, further providing acoustic damping at a relatively low manufacturing cost. The acoustic panel comprises a cardboard comprising a fibrous filler and a base binder, and a nodular coating placed on the cardboard, wherein the coating comprises modulated wool and a coating binder. In one embodiment of the present invention, the fibrous filler is mineral wool and the binder is granular starch. In another embodiment of the present invention, the nodulated wool is nodulated mineral wool and the coating binder is cooked granulated corn starch. In another aspect of the present invention, a method of manufacturing the durable acoustic panel comprises forming an aqueous suspension comprising a fibrous filler, a base binder, and water; deposit the aqueous suspension on a wire of mobile foraminous support to form an aqueous felt; dehydrating the aqueous felt to form a wet felt; coating the wet felt with an aqueous coating comprising nodulated wool, coating binder, and water; and drying the wet felt and aqueous coating to form the panel. Thus, a durable acoustic panel and a unique fabrication method is now provided that provides a successful resolution of the disadvantages or drawbacks of existing shingles and provides distinct advantages over such shingles. The objects, features and further advantages of the invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the figures of the accompanying drawings, which are briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partial elevation view of a modality of a durable acoustic panel made in accordance with the present invention. Figure 2 is a partial perspective view of another embodiment of the durable acoustic panel made in accordance with the present invention.

Figure 3 is a flow chart of a process according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION For a more complete understanding of the present invention, reference should be made to the following detailed description taken in connection with the accompanying drawings, where like reference numbers designate corresponding parts through the different figures. Referring first to Figure 1, a durable acoustic panel 10 made in accordance with the present invention is shown. The panel 10 comprises a board 12 as a base and a nodular coating 16 placed on at least one side 14 of the board 12. The nodular coating 16 has a substantially smooth surface 17. The board 12 comprises from about 30 to about 90% dry weight of fibrous filler from about 3 to about 10% by dry weight of base binder. According to the present invention the board 12 can have a density of about 0.8 to about 1.7 lb / bd ft (12.82 to 27.24 kg / m3) and the liner 16 can have a density of about 1.5 to about 2.5 lb / bd ft (24.03 to 40.06 kg / m3). As used in the present invention, the term "substantially smooth" means that the surface 17 of the coating 16 defines a plane and at least 50% of the coating surfaces are substantially at the same level as the plane and is substantially free of projections that extend from the surface 17 beyond the plane. However, the liner 16 may have fissures extending therefrom from the plane. Examples of tiles that have a rough or textured surface are GLACIER, manufactured by United States Gypsum and STRATUS, manufactured by Armstrong World Industries, Inc. The surface 17 of the coating is at least as smooth as that of the FROST, manufactured by United States Gypsum, or GEOTEX, manufactured by Armstrong World Industries, Inc. The surface texture of the GEOTEX is approximately 39 ml / square foot (0.04 ml / cm2) as measured using a texture volume test. The texture volume test uses glass beads to measure the volume of texture per square foot of a sample. Essentially, glass beads fill the surface texture of the shows up to the highest surface point. The texture volume test is described in more detail later. In another embodiment, the surface texture 17 is approximately as smooth as the average distance between the visible surfaces installed of the STRATUS having a production date of May 19, 2000, and the GEOTEX having a production date of April 24, 2000. The surface texture of STRATUS is approximately 160 ml / square foot (0.17 ml / cm2), according to what was measured using the texture volume test. In this way, the surface texture of this modality is approximately 100 ml / square foot (0.10 ml / cm2). In greater detail, the volume test used to measure the surface texture of the exemplary tiles comprises a square wool structure having an internal dimension of approximately 12 1/16 inches (30.63 centimeters) by 12 1/16 inches (30.63 centimeters) formed by hard wool of 1 foot (0.33 centimeters) by 1 inch (2.54 centimeters). The formed structure has two holes drilled to accommodate nails to hold the sample in place. Additionally, pearls of the 40-60 mesh class (Ussieve) available from Potters Industries are used, Incorporates, Postadam, New York. Referring to the procedures, the tile sample is cut to a dimension of approximately 12 inches (30.48 centimeters) by 12 inches (30.48 centimeters) having four tapered edges so that the top of the tape is at the same level as the high points on each side of the sample. The sample is then placed in the structure and the structure is lifted so that the sample phase is level with the upper part of the structure. Nails are inserted into the holes to hold the sample in place and the structure is lifted up again so that the sample is facing up. The glass beads are then poured onto the sample in a thin layer and using a straight edge the beads are dispersed to completely fill the sample. The sample is often taped to sediment all the pearls within the texture. A small brush is used to gently remove all the pearls from the edges of the structure and the remaining beads are transferred to a clean piece of paper by lifting the board into the structure. It is necessary to gently taper on the back of the board to remove all the pearls of the sample. The beads are then poured into a graduated cylinder and the volume is recorded. The fibrous carton filler 12 can be selected from mineral wool, polyester fibers, polypropylene fibers, NYLON fibers, carbon fibers, hard pulp wood cellulosic fibers, soft pulp wood cellulosic fibers, wollastonite, fiberglass , rock wool, slag wool, and combinations thereof. In one embodiment, the fibrous filler comprises mineral wool. The mineral wool may comprise fibers of rock wool or basalt wool. The fibers, in general, have a diameter of about 3 to about 6 microns. In addition, the fibers can be used in the "primed" or "naked" state. Sizing agents such as mineral oils or acrylic polymer dispersions may be employed. These fibers contribute to the structural integrity and strength or strength of the board 12. The base binder can be selected from granular starches, such as, pearl corn cotton, wheat starch and potato starch, and polymers, such as polystyrene, acetate of polyvinyl, acrylic polystyrene, styrene butadiene, and combinations thereof. In one aspect of this invention the granular, pearled corn starch of the present invention comprises the base binder. To provide additional strength and performance resistance, the board 12 may further comprise up to about 15% by dry weight of cellulose fibers derived from wood fibers, mainly paper fibers, secondary paper fibers, or cotton linters. Such primary and secondary paper fibers, respectively, include pre- and post-consumer paper products, such as newsprint. The length of the fiber can be up to about 1/4 inch in length (0.63 centimeters). In one embodiment, the cellulosic fibers for use in the present invention are newspaper fibers, which generally have a length of about 1/4 of a millimeter to about 5 millimeters with an average length of about 1 millimeter. Specifically, the newspaper comprises cellulosic fibers that contribute to the moisture resistance of the board and are converted from the suspension to a wet damp felt on the way to becoming paperboard 12. Retention agents can be used in the board 12 to help retain the base binder, non-fibrous fillers, and binding fibers during the dehydration operations. There are many such retention agents available in the market that can be employed in the present invention. One such retention agent is a cationic polyacrylamide marketed as PURACHEM 240 EC by Hercules Chemical Co. Fillers or non-fibrous fillers may be employed in the carton in an amount of 0 to about 20% by dry weight. Non-fibrous fillers can be selected from kaolin clay, calcium carbonate, silica, vermiculite, spherical clay or bentonite, talc, mica, gypsum and combinations thereof, namely only a few. The expanded perlite can also be used in the cardboard in an amount from 0 to about 30% dry weight. Perlite is a mineral of volcanic glass, similar to obsidian with the ability to expand to a large extent with heat, typically comprising silica, aluminum, calcium or other alkaline earth silicate. The pearlite contributes to the volume or hardness of the cardboard. Expanded perlite and methods for making expanded perlite are described in the US patent NO. 5,911,818, which is incorporated herein by reference. In general, perlite contains 65-75% Si02, 10-20% A1203, 2-5% H20, and Smaller amounts of soda, potash and lime. Expanded perlite denotes any vitreous rock and more particularly a volcanic glass that has been suddenly expanded or "exploded" while being heated rapidly. This "explosion" generally occurs when crushed pearlite grains are heated to incipient melting temperatures. The water contained in the particle is contained in vapor and the crushed particles expand to form light, fluffy cell particles. Increases in particle volume of at least ten times are common. Expanded perlite is generally characterized by a system of concentric, spheroidal turns, which are known as perlite structure. The different types of perlite are characterized by variations in the composition of the glass that affect properties such as softening point, type, and degree of expansion, size of the bubbles and thickness of the wall between them, and porosity of the product. Conventionally, expanded perlite is prepared by first grinding pearlite ore to a fine size. The finely ground pearlite mineral is then expanded in a perlite expander by means of hot air having a temperature of between approximately 1375 ° F (746.11 ° C) and approximately 1750 ° F (954.44 ° C). The hot air heats the pearlite mineral which causes it to "pop like popcorn" to form expanded perlite that has a density of about 3 to about 20 pounds per cubic foot (48.07 to 320.51 kg / m3). Expanded perlite is a very light weight material, but it contains many cracks and fine fissures. When the expanded perlite is put in contact with water, the water penetrates the cracks and fissures and enters the air-filled cavities of the pearlite, thus causing the pearlite to retain a very large amount of water inside the pearlite particles. expanded. Perlite can also be coated with hydrophobic coatings such as silicones, sizing agents and the like. To provide flame retardant properties, the board 12 includes boric acid. In addition, the boric acid helps the board 12 to resist color degradation during drying operations of the wet felt. Other fireproofing agents can be used. The boric acid is present in the board in an amount from 0 to about 1% by dry weight.

In addition, pigments, water repellents, etc. can be used. Additional water and "defective paper" can be added to the aqueous suspension that forms the board 12. "Defective paper" is predominantly recycled board material that may have been rejected or cut from commercially acceptable boards, as well as other waste products. The defective paper can be used in an amount of about 0 to about 40% dry weight. Additional additives, such as dispersants, defoamers, fungicides and combinations thereof, can be added to the aqueous suspension forming the board in an amount of from 0 to about 1% by dry weight. Such additives are known in the art and can be readily employed by those skilled in the art. In the process of preparing the carton, the ingredients mentioned above are mixed together with the amount of water necessary to provide consistency to the suspension in conventional mixing and containment equipment (not shown). In the present invention, sufficient water is added to form an aqueous suspension comprising approximately up to about 13% by weight solids. In one embodiment, the aqueous suspension comprises from about 2 to about 5% solid weight. The acoustic properties (i.e., sound absorption) of sheets made in accordance with the present invention are based on the sound that enters the cardboard 12 through its pores. Although in the cardboard 12, the sound energy is converted into thermal and mechanical energy due to the natural resonant properties of the materials that comprise the cardboard. The side walls of the pores in the cardboard 12 convert the sound to thermal energy via friction. The techniques of formation of standard boards (Fourdrinier or cylinder) using superior cellulose fibers (periodic) and pearlite levels will produce a cardboard that, although it has a sufficient total porosity so as not to impede the flow of sound completely, will have large pores in the face and smaller pores in the back. The disposition of the pores in the cardboard does not absorb or convert the sound energy efficiently. The large pores on the face do not have enough surface area on the wall to convert the sound to thermal energy and the small pores on the back do not have enough cross-sectional area to allow the sound enters the pores. Therefore, although the total porosity of the board can be relatively high (85% -90%), substantially less than all the pores have the appropriate ratio of cross-sectional area to pore surface area to allow sound to flow towards the pores. pores in conjunction with the absorption of sound within the pores. However, the process of forming the mobile foraminous support wire of this invention produces a homogeneous cardboard structure, so that substantially all pores of the board 12 are available for both sound flow and absorption. Thus, the highly acoustic properties of the board 12 of this invention are attributable to its high porosity and its substantially uniform density from front to back, a well-controlled density gradient. Formulations containing high amounts of man-made fibers usually exhibit high porosity with accompanying acoustic properties. Using current cardboard forming techniques, fibers containing high amounts of mineral wool will have a high NRC, that is, at least 0.60. The formulations containing significant amounts of cellulose and pearlite normally they do not exhibit such high NRCs. In the present invention, by uniformly distributing the aqueous suspension again from the wire of the foraminous support before draining the water, the fibers are uniformly formed from front to back resulting in substantially uniform distribution of the pore sizes. The mesh structure remains fixed before free drainage and water removal. As further shown in Figure 2, perforations 18 can be partially placed through the cardboard to improve the NRC. Referring again to Figure 1, the modulated coating 16 is placed on at least one side 14 of the board 12. The modulated coating 16 comprises from about 50 to about 85% dry weight of nodulated wool and a coating binder. In the present invention, the coating binder is selected from starch by a foaming agent. Starches found useful in the present invention include, but are not limited to, pearly corn starch, wheat starch, potato starch and combinations thereof. In one embodiment, starch, such as pearled corn starch, is mixed with water and heated from about 190 ° F to about 210 ° F (87.77 ° C to 98.88 ° C) for one hour. a sufficient period of time until the mixture of starch and water gels to form a cooked starch. The amount of cooked starch present in coating 16, when used, is from about 5 to about 12% by dry weight. Alternatively, a foaming agent may be used in the coating. Such foaming agents include bis (2-hydroxyethyl) ceboalkylamine (sold under the trade name ETHOMEEN T-12 by Akzo Nobel Chemicals Inc.), laurate (1) sodium sulfate, deceto (3) ammonium sulfate, C6_10 alcohol ammonium ethoxysulfate, sodium dodecylbenzene sulfonate and combinations thereof. In one embodiment, the foaming agent is bis (2-hydroxyethyl) bac-alkylamine. When employed, the foaming agent is present in coating 16 from about 0.1 to about 1% dry weight. When a foaming agent is employed, the coating 16 further includes about 2 to about 8% dry weight of a granular binder. The foaming agent is not a binding agent in the same manner as the cooked or granular starch, but also helps to provide a stable body to the coating, which allows the coating to be separated without substantial dehydration. Granular binders include, but are not limited to, pearl corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, acrylic polystyrene, styrene butadiene and combinations thereof. In addition to the granular binder, from 0 to about 1% by dry weight of aluminum sulfate may be included to assist the foaming agent. The nodulated wool was prepared from fibrous materials, such as mineral wool, metal slag wool, glass fiber, rock wool and combinations thereof, and other hot liquifiable raw materials capable of being converted into fibers and being nodulated. Conventional methods for nodulating fibers are known in the art, and can be employed in the present invention to nodulate the various fibrous materials described above. Mineral fibers usually have a diameter length that is equal to 10 or greater, with lengths ranging from 0.1 to 100 mm, most typically between 1 and 10 mm, and diameters within the range of 0.1 to 25 microns. Wool nodules are characterized by size using a sieve analysis method. The suspension containing all the ingredients is washed to Separate the nodules from all the other ingredients. The wool pellets are dried and then approximately 15 grams-25 grams of the dried pellets are added to the upper sieve, and separated by means of the ROTAP model RX-29 from W.S. Tyler Table 1 shows the size distribution useful in the present invention. A preferred size distribution has been listed based on exhaustive factory tests, all using nodes of the same size. There has been an unlimited number of tests with another size distribution.

TABLE 1 Additionally, a slip agent was employed in the coating 16 to assist in depositing the nodular coating 16 on the cardboard 12, particularly in screening operations. In addition to the commercially available glidants, isostearamidopropyl ethyl etosulfate (sold under the tradename SHERCOQUAT IAS by Scher Chemicals) and polyethylene oxide can be used. The following materials can also be used in the amounts indicated in the nodular coating 16 and are described above: Cellulose fibers from 0 to about 10% by dry weight Non-fibrous filler from 0 to about 15% dry weight Expanded perlite 0 to approximately 20% by dry weight Boric acid from 0 to approximately 1% by dry weight Defective paper from 0 to approximately 35% by dry weight Sliding agent from 0 to approximately 1% by dry weight Additives from 0 to approximately 1% dry weight However, when the agent is present in coating 16, defoaming agents are absent from it. Referring now to Figure 3, a method for manufacturing the durable acoustic panel 10 according to the present invention is shown. Initially, an aqueous suspension is formed comprising a fibrous filler, a binder and water. The aqueous suspension is deposited on a movable foraminous support wire to form an aqueous felt, thereby creating a continuous process. Subsequently, the aqueous felt is dehydrated to form a wet felt. The wet felt is coated with an aqueous coating comprising nodulated wool, coating binder and water. Finally, the wet felt and the aqueous coating are dried to form the panel. The aqueous coating, regardless of the coating binder, comprises from about 15 to about 35% by weight solids. In another embodiment, the aqueous coating comprises from about 21 to about 28% by weight solids. As indicated above, the nodular coating 16 can be formed using a coating binder comprising cooked starch. The starch cooked is formed by mixing water and starch, such as pearled corn starch, in a mixing tank 20. Initially, the starch comprises from about 2 to about 14% by weight of water and starch mixture. The mixture of water and starch is heated to cook the starch. In the present invention, steam is injected into the mixture to raise the temperature of the mixture to about 190 ° F (87.77 ° C). The steam is interrupted and the mixture is kept under agitation for a sufficient period of time, for example 7 minutes, to reach a final temperature of about 200 ° F to about 210 ° F (93.33 ° C to 98.88 ° C) to form the cooked starch. After this mixture is cooled to approximately 200 ° F (93.33 ° C), additional water is added to the binder mixture 20 to further dilute the cooked starch. Subsequently, other materials may be added, such as cellulose fibers, non-fibrous fillers, expanded perlite, boric acid, defective paper and cooked starch additives and mixed perfectly, for example 5 minutes. This mixture can be pumped to a use tank 25 to be stored until ready to be added to a top cut mixer or slat 40. Any mixer can be used that can be used. it can uniformly mix a high fibrous suspension in solids and thus produce wool pellets. The batten mixer 40 is maintained at low speed (approximately 20 rpm) while the mixture described above is added with the slip agent and open wool. Before being added to the batten mixer 40, the wool is separated from a bale by a conventional bale separator and transferred to a granulator 35 which further breaks the large woolen tufts. After all the ingredients mentioned above are placed in the batten mixer 40, the speed is increased to 40 rpm for a sufficient period of time, for example 7 minutes, to nodulate the wool fibers and form the aqueous nodular coating 16. The speed of the batten mixer 40 is reduced to 20 rpm for about 1 minute and then transferred to a batten mixer 45 to maintain a substantially uniform mixture of the aqueous nodular coating 16 and subsequently supply the forming line. Alternatively, the nodular coating 16 can be formed using a coating binder and a foaming agent. As indicated above, the foaming agent and the binder granular are an alternative to cooked starch. However, the cooked starch may be employed with the foaming agent. In this aspect of the present invention, water is added to the mixing tank 20. Subsequently, other materials may be added, such as aluminum sulfate, cellulose fiber (4.0% by weight of solid), non-fibrous fillers, expanded perlite, boric acid, defective paper, and water additives and mix perfectly, for example, 5 minutes. This mixture can be pumped to the use tank 25 to be stored until ready to be added to the batten mixer 40. The batten mixer 40 is maintained at high speed, approximately 40 rpm while the mixture described above, the foaming agent and the Open wool as described above, is added to it. All of the aforementioned ingredients are mixed in the batten mixer 40 for a sufficient period of time, for example, about 14 minutes, to nodulate the wool and form the aqueous nodular coating. The amount of the foaming agent and the mixing time are varied to obtain a wet foam density of 900 grams in a 950 ml cup. This mixture is then transferred to the slat mixer 45 for maintaining a substantially uniform mixture of the aqueous nodular coating 16 and subsequently supplying the formation line. The aqueous suspension of the paperboard 12 is deposited on the movable foraminous wire of a conventional upper box 50 to form the aqueous felt 52. Immediately afterwards, the aqueous felt 52 is allowed to drain freely flowing the water by gravity and is then passed through the rollers of Pressed 54 to drain water from aqueous felt 52, smooth at least one side 14 of aqueous felt 52 to create a substantially consistent gauge or thickness through aqueous felt 52. Aqueous felt 52 is then operably coupled with a vacuum a vacuum box 56 for further dewatering the aqueous felt 52 and forming the wet felt 58. Optionally, the wet felt 58 may be partially perforated by a conventional perforator (not shown). The wet felt 58 then enters the nip under an oscillating master blade 60. The master blade is positioned at an angle of between about 20 to about 40 degrees with respect to the wet felt 58, such as 30 degrees, and oscillates transversely with respect to the direction of the machine with speed enough to prevent coating from accumulating on it. In the present invention, the master blade 60 is formed of, for example, a UHMW plastic, for example UHMW polypropylene, to minimize wear and help prevent the buildup of the coating. The master blade 60 can be formed from other materials and / or coatings, particularly materials and coatings comprising a high wear resistance and a relatively low coefficient of friction. The aqueous coating 62 is pumped from the batten mixer 45 to a position behind the master blade 60. In one embodiment, an oscillating tube distributes the aqueous coating 62 on the wet filter 58. The coating flow is maintained so that it exists a continuous strip of aqueous coating accumulated behind the master blade 60. The line of contact between the master blade 60 and at least one side 14 can be fixed to a desired coating thickness, for example about 0.200"(0.508 cm). The coating should be maintained at a minimum temperature of 100 ° F (37.8 ° C) to maintain its sliding characteristics through the master blade 60.

The wet felt sheet / aqueous coating 64 is subsequently pressed using a smooth roller 66 (cold rolled steel or stainless steel, surface machined) which rotates cocurrently with the forming wire, but at a speed of about 50% to about 300%, preferably from about 50% to about 150%, faster than the forming wire. The contact line of the smooth roller 66 is fixed to press the sheet 64, for example, to approximately 0.150"(0.381 cm), preferably approximately 0.100" (0.254 cm), thereby smoothing even more at least one box 17 The wet felt 58 of the sheet 64 is then operably coupled with a vacuum by means of a vacuum box 68 in the presence of steam directed towards the aqueous coating of a steam hood to remove water. Various apparatuses and techniques for applying steam or dehydration methods that can be employed in the present invention are discussed in US Patent Nos. 2,642,314, 2,714,839, 2,809,867, 2,838,982, 2,949,239, 3,850,792 and 3,945,881, which are incorporated herein in their entirety. After dehydrating at least partially the wet felt and the aqueous coating sheet 64, the sheet 64 is pressed by the leveling roller 72 (cold-rolled steel or stainless steel, machined surface) which rotates countercurrently with the forming wire, for example up to about 0.100"(0.254 cm). The leveling roller 72 rotates at speeds substantially equal to the wire of formation to further level at least one side 14. Finally, the wet felt and aqueous coating sheet 64 is dried in an oven (not shown) to form the durable acoustic panel 10 of the present invention. discoloration of the panel 10, the furnace temperature decreases in the direction of the machine, for example, at the inlet of the furnace, the temperature is about 700 ° F (371.1 ° C) and gradually decreases to about 400 ° F (204.4 ° C) ) at the exit of the furnace Finally, the panel 10 can take a number of finishes, which include paints, fissures, grooves, engraving, stamping, abrasion, sanding and any combination of the Such methods are known in the art. Such finishing processes are described in U.S. Patents 4,911,788 and 5,277,762, which are hereby incorporated in their entirety.

EXAMPLES The following examples demonstrate a range of formulations for both coating and carton and the ability to form the panel continuously. It is known in the art that both cellulose and starch contribute to the distortion by moisture and dimensional stability by moisture. In the following examples, the content of fiber (cellulose) and binder (starch) can be quantified (excluding water bound to the filler or filler) by measuring the LOI (Loss by Ignition, weight loss on board at 843 ° C) of the panel layers. The acoustic properties of the boards are measured directly as NRC, Coefficient of Noise Reduction. This is a standard test method according to the ASTM C 423-84a test designation, by which sound absorption at various frequencies is measured. Hardness is tested in accordance with ASTM C367-95, Sections 2-7. The following tiles were made according to the method of the present invention as described above.

EXAMPLE 1 EXAMPLE 1 (cnt) The NRC of the 0.770"(1.95 cm) unpainted tile was 0.70 (average frequency of 4 = 0.708).

EXAMPLE 2 EXAMPLE 2 (continued) The carton formula was loaded from Example 1. The NRC of the face and back of the 0.670"(1.70 cm) board painted was 0.65 (average frequency of 4 = 0.670).

EXAMPLE 3 EXAMPLE 3 (continued) The formula of the carton was loaded from Example 1. The NRC of the board 0.675"(1.71 cm) painted was 0.65 (average frequency of 4 = 0.657).EXAMPLE 4 EXAMPLE 4 (continued) This board was made using a foaming agent. The NRC for the board face of 0.710"(1.80 cm) painted was 0.70 (average frequency of 4 = 0.695). The weight of the cup of the foamed coating suspension was 979 gms. EXAMPLE 5 EXAMPLE 5 (continued) This board is the cardboard used in Examples 1 and 3. The NRC of the 0.710"(1.80 cm) unpainted board was 0.70 (average frequency of 4 = 0.686) This example was provided to demonstrate the capability of the present invention to maintain or improve an NRC, while improving the surface hardness With respect to the above description then, it should be understood that the optimal dimensional relationships for the parts of the invention, including variations in size, shape, profile, function and The manner of operation, assembly and use, are considered to be readily apparent and obvious to one skilled in the art, and all ratios equivalent to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. of the embodiments of the invention can be exchanged to produce additional modalities and it is intended that such additional embodiments be encompassed by the present invention. Therefore, the foregoing is considered as illustrative only of the principles of the invention. In addition, various modifications of the invention can be made without departing from the scope thereof and it is desired, therefore, that only such limitations be placed on it and placed according to what is imposed by the prior art and what is set forth in the appended claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (67)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. A durable acoustic panel, characterized in that it comprises: a board comprising a fibrous filler and a base binder, and a nodular coating placed on the board, where the coating comprises nodulated wool and a coating binder and has a substantially smooth surface.

The panel according to claim 1, characterized in that the paperboard comprises from about 30 to about 90% dry weight of fibrous filler and about 3 to about 10% dry weight of base binder.

3. The panel according to claim 1, characterized in that it is selected from mineral wool, polyester fibers, polypropylene fibers, NYLON fibers, carbon fibers, hard pulp wood cellulosic fibers, cellulosic fibers of soft pulp wood, wollastite, fiberglass, rock wool, slag wool, and combinations thereof.

4. The panel according to claim 1, characterized in that the fibrous filler is mineral wool.

5. The panel according to claim 1, characterized in that the base binder is granular starch.

The panel according to claim 1, characterized in that the base binder is selected from pearl corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, acrylic polystyrene, styrene butadiene, and combinations thereof.

The panel according to claim 1, characterized in that the board further comprises up to about 15% by dry weight of cellulose fibers derived from primary paper fibers, secondary paper fibers, or cotton linters.

8. The panel according to claim 1, characterized in that the board further comprises about 0.02 up to about 0.2% dry weight of a retention agent.

9. The panel according to claim 1, characterized in that the cardboard further comprises: non-fibrous filler from 0 to approximately 20% by dry weight Expanded perlite from 0 to approximately 30% dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 40% dry weight Additives from 0 to approximately 0.5% dry weight wherein the additives are selected from dispersants, defoaming agents, fungicides and combinations thereof and where at least one of the non-fibrous filler, expanded perlite, boric acid, defective paper and additive is present.

10. The panel according to claim 9, characterized in that the board further comprises cellulose fibers derived from primary paper fibers, secondary paper fibers or cotton linters.

The panel according to claim 9, characterized in that the filler is selected from kaolin clay, calcium carbonate, silica, vermiculite, spherical clay, talc, mica, gypsum and combinations thereof.

12. The panel according to claim 1, characterized in that the coating binder is starch or a foaming agent.

The panel according to claim 12, characterized in that the starch is selected from corn starch, pearl, wheat starch, potato starch and combinations thereof.

14. The panel according to claim 1, characterized in that the coating binder is a cooked starch.

15. The panel according to claim 14, characterized in that the cooked starch is cooked pearled corn starch.

16. The panel according to claim 12, characterized in that the foaming agent is selected from bis (2-hydroxyethyl) ceboalkylamine, lauret (1) sodium sulfate, decet (3) ammonium sulfate, C6.10 alcohol ammonium ethoxysulfate, sodium dodecylbenzene sulfonate and combinations thereof.

17. The panel according to claim 12, characterized in that the foaming agent is bis (2-hydroxyethyl) ceboalkylamine.

18. The panel according to claim 12, characterized in that the coating further comprises from about 2 to about 8% dry weight of a granular binder when the coating binder includes a foaming agent.

The panel according to claim 17, characterized in that the coating further comprises about 2 to about 8% dry weight of a granular binder.

The panel according to claim 18, characterized in that the granular binder is selected from pearly corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, acrylic polystyrene, styrene butadiene and combinations thereof.

The panel according to claim 19, characterized in that the granular binder is selected from pearl corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, polystyrene acrylics, styrene butadiene and combinations thereof.

22. The panel according to claim 1, characterized in that the coating further comprises up to about 10% dry weight of cellulose fibers.

23. The panel according to claim 22, characterized in that the cellulose fibers are derived from pulps of primary paper, secondary paper fibers or cotton linters.

24. The panel according to claim 1, characterized in that the coating further comprises: non-fibrous filler from 0 to approximately 15% by dry weight expanded perlite from 0 to approximately 20% dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 35% dry weight Sliding agent from 0 to about 1% by dry weight additives from 0 to about 1% by dry weight where the additives are selected from dispersants, defoamers, fungicides and combinations thereof, and where at least one of the non-fibrous filler, expanded perlite, boric acid, defective paper and additives is I presented.

25. The panel according to claim 24, characterized in that the filler is selected from kaolin clay, calcium carbonate, silica, vermiculite, spherical clay, talc, mica, gypsum and combinations thereof.

26. The panel according to claim 24, characterized in that the slip agent is selected from isostearamidopropyl ethyl ethoxide and polyethylene oxide.

27. The panel according to claim 1, characterized in that the nodulated wool is selected from nodulated mineral wool, slag wool from nodulated metal, nodulated fiberglass, nodulated rock wool and combinations thereof.

28. The panel according to claim 1, characterized in that the nodulated wool is nodulated mineral wool.

29. A method for manufacturing a durable acoustic panel, characterized in that it comprises: (a) forming an aqueous suspension comprising a fibrous filler, a base binder, and water; (b) depositing the aqueous suspension on a movable foraminous support wire to form an aqueous filter; (c) dehydrating the aqueous felt to form a wet felt; (d) coating the wet felt with an aqueous coating comprising nodulated wool, coating binder, and water, wherein the aqueous coating has a substantially smooth surface; and (e) drying the wet felt and aqueous coating to form the panel.

30. The method according to claim 29, characterized in that the substantially smooth surface has a surface texture of approximately less than 100 ml / square foot (1076.4 ml / square meter).

31. The method according to claim 29, characterized in that in step (c) the aqueous felt is dehydrated by pressing.

32. The method according to claim 29, characterized in that in step (c) the aqueous felt is dehydrated by operably coupling a vacuum with the aqueous felt.

33. The method according to claim 29, characterized in that in step (c) the aqueous felt is dehydrated by pressing and then an operable vacuum is used to extract water from the aqueous felt.

34. The method according to claim 29, characterized in that it further comprises between the steps (d) and (e): partially dehydrating the aqueous felt and the accu accord.

35. The method according to claim 34, characterized in that the wet felt and the aqueous coating are dehydrated by partially operatively coupling a vacuum with the wet felt.

36. The method according to claim 35, characterized in that it further comprises pressing the partially dehydrated wet felt and the aqueous coating.

37. The method according to claim 29, characterized in that it further comprises between steps (c) and (d) partially perforating the wet felt.

38. The method according to claim 29, characterized in that it further comprises between steps (d) and (e) making the aqueous coating to a substantially uniform thickness through the wet felt.

39. The method according to claim 34, characterized in that the aqueous coating is flush to a substantially uniform thickness through the wet felt before partially dehydrating the wet felt and aqueous coating.

40. The method according to claim 29, characterized in that in step (e) the wet felt and the accu- sive coating are dried to a temperature of approximately 400 ° F (204.4 ° C) to approximately 750 ° F (398.9 ° C).

41. The method according to claim 29, characterized in that in step (a) the aqueous suspension is formed by substantially uniformly mixing the fibrous filler, the base binder and the water.

42. The method according to claim 29, characterized in that the aqueous suspension of step (a) is a substantially uniform aqueous mixture having between about 2 and up to about 13% by weight solids and comprises: fibrous filler from about 30 to about 90% dry weight binder base from about 3 to about 10% by dry weight cellulose fibers from 0 to approximately 15% by dry weight retention aid of approximately 0.02 to approximately 0.2% dry weight non-fibrous filler from 0 up to about 20% in dry weight expanded perlite from 0 to about 30% dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 40% dry weight additives from 0 to approximately 0.5% dry weight where the additives are selected from dispersants, defoaming agents, fungicides and combinations thereof.

43. The method according to claim 42, characterized in that the fibrous filler is selected from mineral wool, polyester fibers, polypropylene fibers, NYLON fibers, carbon fibers, hard pulp wood cellulosic fibers, wood cellulosic fibers of soft pulp, wollastonite, fiberglass, rock wool, slag wool, and combinations thereof.

44. The method according to claim 42, characterized in that the fibrous filler is mineral wool.

45. The method according to claim 42, characterized in that the base binder is granular starch.

46. The method according to claim 45, characterized in that the base binder is selected from pearl corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, acrylic polystyrene, styrene butadiene, and combinations thereof.

47. The method according to claim 42, characterized in that the cellulose fibers are derived from primary paper fibers, secondary paper fibers or cotton fluff.

48. The method according to claim 42, characterized in that the non-fibrous filler is selected from clay of kaolin, calcium carbonate, silica, vermiculite, spherical clay, talc, mica, gypsum and combinations thereof.

49. The method according to claim 29, characterized in that the aqueous coating of step (d) is formed by the steps comprising: forming a mixture comprising a coating binder, wool fibers and water; Y stir the mixture for a period of time sufficient to distribute substantially uniform and nodular wool fibers.

50. The method according to claim 29, characterized in that the aqueous coating is a substantially uniform aqueous mixture having between about 15 to about 35% by weight solids and the coating binder is selected from a cooked starch and a foaming agent.

51. The method according to claim 50, characterized in that the aqueous coating comprises: nodulated wool from about 50 to about 85% dry weight cellulose fibers from 0 to about 10% by dry weight non-fibrous filler from 0 to approximately 15% dry weight Expanded perlite from 0 to about 20% dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 35% dry weight Sliding agent from 0 to about 1% by dry weight additives from 0 to about 1% by dry weight where the additives are selected from dispersants, defoaming agents, fungicides and combinations thereof.

52. The method according to claim 51, characterized in that the coating binder is cooked starch comprising from about 5 to about 12% by dry weight of the aqueous coating and is selected from pearled corn starch, wheat starch, starch from potato and combinations thereof.

53. The method according to claim 51, characterized in that the coating binder is a foaming agent comprising from about 0.1 to about 1% by dry weight of the aqueous coating and is selected from bis (2-hydroxyethyl) ceboalkylamine, laureth ( 1) sodium sulfate, decet (3) ammonium sulfate, alcohol of C6.10 ethoxysulfate of ammonium, sodium dodecylbenzene sulfonate and combinations thereof.

54. The method according to claim 53, characterized in that the coating further comprises from about 2 to about 8% by weight of a granular binder and from 0 to about 1% by dry weight of aluminum sulfate.

55. The method according to claim 54, characterized in that the base binder is selected from pearl corn starch, wheat starch, potato starch, polystyrene, polyvinyl acetate, acrylic polystyrene, styrene butadiene, and combinations thereof.

56. The method according to claim 51, characterized in that the cellulose fibers derived from primary paper fibers, secondary paper fibers or cotton linters.

57. The method according to claim 52, characterized in that the filler is selected from kaolin clay, calcium carbonate, silica, vermiculite, spherical clay, talc, mica, gypsum and combinations thereof.

58. The method according to claim 52, characterized in that the slip agent is selected from isostearamidopropyl ethyl diammonium ethosulfate and polyethylene oxide.

59. The method according to claim 52, characterized in that the additives are selected from dispersants, defoaming agents, fungicides and combinations thereof, with the proviso that defoaming agents are absent in the coating when a foaming agent is present in the coating. he .

60. The method according to claim 52, characterized in that the nodulated wool is selected from nodulated mineral wool, slag wool of nodulated metal, nodulated cut glass, nodulated rock wool and combinations thereof.

61. A durable acoustic panel, characterized in that it comprises: a board comprising a fibrous filler and a base binder, and a nodular coating placed on the board, where the coating comprises nodulated wool and a coating binder and has a texture surface area of approximately less than 100 ml / square foot (1076.4 ml / square meter).

62. The panel according to claim 61, characterized in that the paperboard comprises from about 30 to about 90% dry weight of fibrous filler and about 3 to about 10% dry weight of base binder.

63. The panel according to claim 61, characterized in that the fibrous filler is mineral wool.

64. The panel according to claim 61, characterized in that the base binder is granular starch.

65. The panel according to claim 61, characterized in that the board further comprises from about 0.02 to about 0.2 dry weight of a retention agent.

66. The panel according to claim 61, characterized in that the cardboard further comprises: non-fibrous filler from 0 to approximately 20% in dry weight expanded perlite from 0 to about 30% dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 40% dry weight Additives from 0 to approximately 0.5% dry weight wherein the additives are selected from dispersants, defoaming agents, fungicides and combinations thereof and where at least one of the non-fibrous filler, expanded perlite, boric acid, defective paper and additive is present.

67. The panel according to claim 61, characterized in that the coating further comprises: Non-fibrous filler from 0 to approximately 15% dry weight expanded pearlite from 0 to approximately 20% in dry weight boric acid from 0 to about 1% by dry weight defective paper from 0 to approximately 35% dry weight Sliding agent from 0 to about 1% by dry weight additives from 0 to about 1% by dry weight where the additives are selected from dispersants, defoamers, fungicides and combinations thereof, and where at least one of the non-fibrous filler, expanded perlite, boric acid, defective paper and additives is I presented. SUMMARY OF THE INVENTION An acoustic panel has a hard board which includes a filler or fibrous filler and a base binder, and a modulator coating placed on the hard board, where the coating includes nodulated wool and a coating binder and has a substantially smooth In one embodiment of the present invention, the fibrous fabric filler is mineral wool and the base binder is granular starch. In another embodiment of the present invention, the nodulated wool is nodulated mineral wool and the coating binder is cooked pearled corn starch. A method for manufacturing the durable acoustic panel according to the present invention is described. Initially, an aqueous suspension is formed comprising a filler or fibrous filler, a base binder and water. The aqueous suspension is deposited on a movable foraminous support wire to form an aqueous felt, thereby creating a continuous process. Subsequently, the aqueous felt is dehydrated to form a wet felt. The wet felt is coated with an aqueous coating comprising nodulated wool, coating binder, and water and has a substantially smooth Finally, the wet felt and water coating are dried to form a roof panel.