|Publication number||USRE41592 E1|
|Application number||US 11/038,004|
|Publication date||Aug 31, 2010|
|Priority date||Sep 9, 1998|
|Also published as||CA2280393A1, CA2280393C, CN1248520A, DE69917719D1, DE69917719T2, EP0985504A1, EP0985504B1, US6508895, US20020069950|
|Publication number||038004, 11038004, US RE41592 E1, US RE41592E1, US-E1-RE41592, USRE41592 E1, USRE41592E1|
|Inventors||Michael R. Lynn, Frederick T. Jones, Gregory J. Cormier|
|Original Assignee||Gladys Cedella Cormier|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (40), Non-Patent Citations (4), Classifications (23), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application claims the benefit of U.S. Provisional Application No.: 60/099,646 filed Sep. 9, 1998.
The present invention relates generally to a paperless gypsum/fiber board with improved impact resistance and to a process for making such a gypsum/fiber board. More particularly, the present invention relates to a multi-layer gypsum/fiber board having a fiberglass mesh embedded in the backside to provide improved impact resistance.
Conventional gypsum wallboard or panel is typically manufactured from a plaster slurry wherein a wet slurry of calcium sulfate hemihydrate, generally referred to as calcined gypsum, is placed between two layers of paper and the slurry is allowed to set. The set gypsum is a hard and rigid product obtained when the calcined gypsum reacts with water to form calcium sulfate dihydrate. Calcined gypsum is either calcium sulfate hemihydrate (CaSO4•½H2O) or calcium sulfate anhydrite (CaSO4). When calcium sulfate dihydrate is heated sufficiently, in a process called calcining, the water of hydration is driven off and there can be formed either calcium sulfate hemihydrate or calcium sulfate anhydrite, depending on the temperature and duration of exposure. When water is added to the calcined gypsum to cause the gypsum to set, in essence, the calcined gypsum reacts with water, and the calcined gypsum is rehydrated. In typical gypsum wallboard, the two layers of paper contain the slurry and provide the strength required in installation and use. The wallboard is cut into discrete lengths to accommodate subsequent handling and then dried in heated dryers until the board is completely dry. The bending strength of the wallboard depends largely on the tensile strength of the paper. The set gypsum serves as the core and accounts for fire resistance and can be modified for various applications. The paper determines the nature of the application for the board and the surface treatment that may be used on the board.
Although paper-covered wallboard has many uses and has been a popular building material for many years, the prior art has recognized that for certain applications it would be advantageous to provide a gypsum panel that did not rely on paper surface sheets for strength and other properties. Several prior art fiber-reinforced gypsum panels are as follows:
U.S. Pat. No. 5,320,677 to Baig, which is incorporated by reference herein in its entirety, describes a composite product and a process for producing the product in which a dilute slurry of gypsum particles and cellulosic fibers are heated under pressure to convert the gypsum to calcium sulfate alpha hemihydrate. The cellulosic fibers have pores or voids on the surface and the alpha hemihydrate crystals form within, on and around the voids and pores of the cellulosic fibers. The heated slurry is then dewatered to form a mat, preferably using equipment similar to paper making equipment, and before the slurry cools enough to rehydrate the hemihydrate to gypsum, the mat is pressed into a board of the desired configuration. The pressed mat is cooled and the hemihydrate rehydrates to gypsum to form a dimensionally stable, strong and useful building board. The board is thereafter trimmed and dried. The process described in U.S. Pat. No. 5,320,677 is distinguishable from the earlier processes in that the calcination of the gypsum takes place in the presence of the cellulosic fibers, while the gypsum is in the form of a dilute slurry, so that the slurry wets out the cellulosic fibers, carrying dissolved gypsum into the voids of the fibers, and the calcining forms acicular calcium sulfate alpha-hemihydrate crystals in situ in and about the voids.
U.S. Pat. No. 5,135,805 to Sellers et al, describes a water resistant gypsum product that may be a “faceless” product, i.e. it may not include a facing sheet of paper, fiberglass mat or similar material. The gypsum products described by U.S. Pat. No. 5,135,805 typically contain reinforcing fibers, for example, cellulosic fibers, such as wood or paper fibers, glass fibers or other mineral fibers and polypropylene or other synthetic resinous fibers. The reinforcing fibers can be about 10 to about 20 wt. % of the dry composition from which the set gypsum product is made. The density of such a product is typicality within the range of about 50 to about 80 pounds per cubic foot.
U.S. Pat. No. 5,342,566 to Schafer et al, which is incorporated by reference herein in its entirety, refers to a method of producing fiber gypsum board comprising the steps of mixing in a preliminary mixing step predetermined amounts of fibers and water respectively, to form a mixture of wetted, loose fibers; mixing in a mixing step the wetted fibers with a predetermined amount of dry calcined gypsum; premixing an accelerator with one of the components of dry calcined gypsum, fiber and water; promptly laying the mixed composition into a mat; immediately degassing the mat in a first compression step, adding a predetermined amount of water onto the resultant mat; and immediately compressing the mat to form a board composed of bonded fibers and gypsum. This process may be used to produce a homogeneous board which is preferably a gypsum board reinforced by fiber, such as paper fiber, wherein several layers of board forming materials are placed on each other before the board is fully formed, pressed, and dried and wherein each of the layers is identical in composition. Schafer et al specifically describes the formation of a three layer board wherein the central, core layer has a composition which differs from the composition of the outer layers.
Carbo et al Provisional Application Serial No. 60/073,503, describes a multi-layer, paperless gypsum/fiber board and a process for making such a three layer gypsum/fiber board wherein the central, core layer has a composition which differs from the composition of the outer layers, all of which is incorporated by reference herein in its entirety.
Prior art gypsum/fiber boards have been modified by adhering a layer of mesh to the back of the board, in order to provide improved impact resistance. While such modified boards had improved impact resistance, the production rates of such board were low, the energy costs were higher, the materials cost increased, the labor cost increased, because of the need to laminate the gypsum boards to the mesh in separate processes that have control problems with respect to the lamination process and the problem of blocking between panels. The process of lamination can be difficult with any variation of thickness of the panel being covered with a mesh or solid reinforcement. With variation in thickness or profile the lamination process is a problem with respect to maintaining constant pressure across the panel. The problem of blocking panels which stick to one another is a significant problem when laminating mesh's on surfaces as the glue can actually glue the stacked panels to one another in addition the mesh on the surface.
It is the object of the present invention to provide a fiber-reinforced gypsum board that has improved impact resistance that avoids many of the problems of the prior art gypsum/fiber boards. More particularly, it is the object of present invention to provide a multi-layer gypsum/fiber board having a fiberglass mesh embedded in the backside to provide improved impact resistance as determined by Soft Body Impact Resistance according to ASTM E695 and by Hard Body Impact Resistance according to USG method as documented in independent reports HPWLI #7122 and HPWLI #7811-02. Embedding a reinforcing mesh to the gypsum/fiber board, in accordance with the present invention, provides many advantages including high production rates; better product aesthetics, integral consolidation of reinforcing mesh in board and reduced product cost. Embedding a reinforcing mesh also improves the handling properties of the board and reduces the tendency of the board to block (adhere to adjacent boards when horizontally stacked). The product of the present invention can include a flush mesh which does not mark up the face of the panel on which it is stacked, and improved retention of the reinforcement in the panels as it is protected from wearing and rubbing on the surface. Another product benefit is the tensioning of the mesh in the product to provide enhanced stiffness to the panel. In terms of the process the present invention eliminates the need to transport the panels to secondary operations, and allows the reinforced panel to be produced on a standard gypsum fiberboard line.
The present invention relates generally to a paperless gypsum/fiber board with improved impact resistance, and to a process for making such a gypsum/fiber board. The term “paperless” gypsum/fiber board, as used herein, is intended to distinguish the fiber-reinforced gypsum panels to which the present invention relates from conventional prior art gypsum panels, which are referred to as “wall board” or “dry wall” which have at least one surface comprised of paper, including “wall board” or “dry wall” having some form of fiber-reinforcement in the core.
The paperless gypsum/fiber board having improved impact resistance is produced by embedding a reinforcing mesh, preferably a flexible fiberglass mesh, in the back side of a multi-layer gypsum fiber board. In the process, the mesh is fed into the forming area of the panel before the panel is pressed prior to drying.
It is to be understood that the foregoing general description, and the following detailed description, are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several embodiments of the invention and together with the description, serve to explain the operation of the present invention.
The present invention relates generally to a paperless gypsum/fiber board with improved impact resistance, and to a process for making such a gypsum/fiber board. The paperless gypsum/fiber board having improved impact resistance is produced by embedding a reinforcing mesh, preferably a flexible fiberglass mesh, in the backside of a multi-layer gypsum fiber board. In the process, the mesh is fed into the forming area of the panel before the panel is pressed prior to drying.
Enhanced and improved impact resistance of the gypsum/fiber board is provided by embedding a reinforcing mesh in the backside of the gypsum/fiber board. The mesh may be either woven or nonwoven and may be made of a variety of materials. Preferably the mesh is made from a flat yarn of an inelastic material such as fiberglass mesh. Most preferably the mesh is a fiber glass mesh having openings in the mesh of sufficient size to allow a quantity of the dry gypsum/fiber mixture to pass through the mesh and embed the mesh in set gypsum in the final product.
One useful woven fiberglass mesh is available from Bayex under the number 0040/286. Bayex 0040/286 is a Leno weave mesh having a warp and weft of 6 per inch (ASTM D-3775), a weight of 4.5 ounces per square yard (ASTM D-3776), a thickness of 0.016 inches (ASTM D-1777) and a minimum tensile of 150 and 200 pounds per inch in the warp and weft, respectively (ASTM D-5035). It is alkali resistant and has a firm hand. Other fiberglass meshes having approximately the same dimensions have opening of sufficient size to allow a portion of the gypsum/fiber mix to pass through the mesh during formation of the board and may be used.
Another useful woven fiberglass mesh is available from Bayex under the number 0038/503. Bayex 0038/503 is a Leno weave mesh having a warp of 6 per inch and weft of 5 per inch (ASTM D-3775), a weight of 4.2 ounces per square yard (ASTM D-3776), a thickness of 0.016 inches (ASTM D-1777) and a minimum tensile of 150 and 165 pounds per inch in the warp and weft, respectively (ASTM D-5035). It is alkali resistant and has a firm hand.
Yet another useful woven fiberglass mesh is available from Bayex under the number 0038/504. Bayex 0038/504 is a Leno weave mesh having a warp of 6 per inch and weft of 5 per inch (ASTM D-3775), a weight of 4.2 ounces per square yard (ASTM D-3776), a thickness of 0.016 inches (ASTM D-1777) and a minimum tensile of 150 and 165 pounds per inch in the warp and weft, respectively (ASTM D-5035). It is alkali resistant and has a firm hand. Other fiberglass meshes having approximately the same dimensions have opening of sufficient size to allow a portion of the gypsum/fiber mix to pass through the mesh during formation of the board and may be used.
Yet another useful woven fiberglass mesh is available from Bayex under the number 4447/252. Bayex 4447/252 is a Leno weave mesh having a warp of 2.6 per inch and weft of 2.6 per inch (ASTM D-3775), a weight of 4.6 ounces per square yard (ASTM D-3776), a thickness of 0.026 inches (ASTM D-1777) and a minimum tensile of 150 and 174 pounds per inch in the warp and weft, respectively (ASTM D-5035). It is alkali resistant and has a firm hand. Other fiberglass meshes having approximately the same dimensions have opening of sufficient size to allow a portion of the gypsum/fiber mix to pass through the mesh during formation of the board and may be used.
The mesh is preferably embedded in the backside of the three-layer board with the warp oriented in the longitudinal direction of the board. Because the board of the present invention is expanded multi-directionally during the pressing step, the use of a mesh which is extensible provides better bonding to the gypsum/fiber board.
It is preferred to have the mesh substantially embedded in the board and covered by the gypsum/fiber mix, because this secures the mesh to the board. Additionally, completely embedding the mesh in the gypsum/fiber mix provides the best impact resistance to the board. Completely embedding the mesh in the gypsum/fiber mix also makes the reinforcement less perceptible to the consumer.
In one embodiment, the mesh is treated with an adhesive in order to improve the bond between the mesh and the gypsum/fiber board. Suitable adhesives include polyvinyl acetates, polyvinyl alcohols and proprietary types. Preferably the adhesive is water activated, i.e. activated due to moistening by water of the board during the forming step of the board making process.
The materials used to produce the gypsum fiber board are conventional materials. The term “gypsum”, as used herein, means calcium sulfate in the stable dihydrate state; i.e. CaSO4•2H2O, and includes the naturally occurring mineral, the synthetically derived equivalents, such as FGD gypsum (a synthetic gypsum which is the by-product of flue gas desulphurization), and the dihydrate material formed by the hydration of calcium sulfate hemihydrate (stucco) or anhydrite. The term “calcium sulfate material”, as used herein, means calcium sulfate in any of its forms, namely calcium sulfate anhydrite, calcium sulfate hemihydrate, calcium sulfate dihydrate and mixtures thereof.
The fibers that serve to reinforce the gypsum are organic fibers, and are preferably cellulosic fibers that are readily available. For example the cellulosic fiber may be waste products such as waste paper, used newspaper, inexpensive household waste paper, and reject fibers of pulp production.
Expanded perlite is used in the core of the product in order to reduce the density of the core layer. Conventional expanded perlite may be used. Preferably the perlite is expanded to a density range of about 5 to 10 pounds per cubic foot range.
Additional components of the type conventionally used in gypsum fiberboard may be used in the board of the present invention. Such conventional components include accelerators, wetting agents, fungicides and the like.
The present invention contemplates the formation of fiber-reinforced gypsum panel having a homogeneous structure throughout, as illustrated by board 102 in
The formation of the board can be described with reference to
Immediately downstream of the discharge rolls are scalper rolls 3117 and 3137, respectively, which scrape off excess fiber and thereby equalize the thickness of the mat. The scalper rolls can be adjusted in height to ensure that the deposited mat of fibers has a uniform weight, and a vacuum is applied at the rollers to pneumatically draw off excess fibers. Fibers scraped off by the scalper rolls are recycled pneumatically by pneumatic conveyors 2513 and 2507 into the same shuttle conveyors on the top of fiber formers 3114 and 3134. The preforming belts operate at a constant speed.
The dry calcined gypsum additive mixture 2480 from distribution bin (not shown) is fed to plaster forming bins 3124, 3164, and 3144. The plaster, as explained below, is predominately calcined gypsum, although the plaster may include other conventional additives to control the chemical process. The gypsum is metered from the forming bins by conventional means, such as conveyors, chutes, or rollers. The bins have a variable speed bottom belt conveyor with an integrated mat scale 3125, 3145, and 3165 to control the amount of plaster deposited on the preforming belt depending on the recipe. The correct amount of plaster is added as a top layer onto the fiber mat. Elements 4911, 4913 and 4912 are permanent magnets.
A continuous belt of mesh 120, which may be wound on supply roll 126, is fed onto forming belt 4010, as shown in FIG. 3. Preferably, the warp of mesh 120 is oriented parallel to the direction of the movement of forming belt 4010.
At the head section 3146 of the preforming belts 3136, the fiber plaster layer is guided downward onto mixing heads 3129, and 3148 and 3168. The mixing heads comprise sets of spike rollers (not shown) which thoroughly mix the fiber and plaster into a homogeneous composition and carry the mixture from the head of the preforming belt (infeed) to the outfeed of the mixing head onto mesh 120 positioned on the forming belt 4010. Depending upon the distance from the preforming belt head to the mixing head, a series of spike rolls controls the downward motion of the material. A portion of the fiber/plaster mix falls through the openings of the reinforcing mesh 120 as the mesh moves on forming belt 4010. Spraying nozzles apply additional water to the bottom layer of the mat.
For a multilayered board, the core layer is formed in a similar manner to that of the surface layer. In the example being described, a lower percentage of fiber is included in the core layer because a volume of expanded perlite is used in the core layer. Expanded perlite is included in the core layer to reduce the overall specific weight of the board. The expanded perlite in combination with the gypsum provide a non combustible core material which enables the core to pass the ASTM E136 test procedure. Preferably, the mixture of wetted paper fibers and perlite particles are moisturized so that they will carry the water necessary to hydrate the plaster to optimum strength added to form the core layer. As explained below, in the preferred embodiment as adhesive, preferably liquid starch, is first mixed with the water for moistening the perlite, and the fibers are separately mixed with water. The wetted fibers and wetted perlite are then mixed together to form a uniform mixture.
Referring again to
Following the formation of the mesh backed mat on the forming belt 4010, the three layered mat is pressed by a press line, shown in FIG. 4. In one embodiment, the forming belt 4010 is also part of the press line and extends through the press and calibrating sections. In another embodiment (not shown), there is an open gap between the degassing station and the compression station. Behind the last compressing roller of the degassing station, spraying nozzles are installed for adding additional water for moistening the top surface of the mat.
The press line includes three main sections, the degassing station 4012, the compression station 4013, and the calibration station 4014. These stations can be adjusted to vary the spacing between the conveyor belts as well as the pressure being applied to the mat or gypsum, fibers, additives, and other materials. The adjustment of the station, therefore, allows the user to vary the thickness of the board.
Initially, the mat is pre-compressed by the degassing station 4012 to remove air from the mat. For a standard board, this station reduces the mat from a thickness of several inches close to the final thickness that can vary, e.g. from ⅜ to ¾ inch. Taper belts are guided into this press along the outboard edges and center of the mat. The taper belts impart a taper into the pressed board along the edges of the panels. These tapers are beneficial for the taping and finishing of panels prior to decoration. Next, the degassed mat is pressed in compression station 4013 where the mat is subject to a high load and pressed to the final board thickness. The mat then goes through calibration station section 4014 which holds the thickness of the board to allow the setting process to continue.
After pressing and prior to drying, the boards are cut and prepared to enter the dryers. The boards, which are formed and pressed endlessly, are pre-trimmed and cut into e.g. 24 foot long pieces. High-pressure water jets may be used to cut and trim the board. For example, 2 stationary jets may be used to trim the sides, while a moving water jet cross cuts the board to length. While in the cutting area and immediately prior to, the board is supported by a conveyor belt that provides forward motion. Alternatively, airjets or similar means (not shown) may provide an air cushion as is well known in the art. Belt conveyors (not shown in
In a preferred embodiment, a three layer fiber-reinforced board is produced with a core having a low content of organic materials that allows the core to pass the ASTM E 136 test procedure. The improved fiber-reinforced board of the present invention may be classified as non combustible because the various code bodies, e.g. BOCA, provide for the removal of ⅛″ from both the top and the bottom layers of the board prior to the application of the ASTM test procedure to core of the board. With the removal of the surface layers containing relatively high levels of paper fibers, the remaining portion, i.e. the core, becomes non-combustible. Prior art fiberboards were relatively non-combustible because they employ non-combustible fiber such as asbestos and minerals such as aluminum trihydrate that reduce the heat released during the test. The board of the present invention passes the ASTM E136 test because the composition of the core contains a total of no more than 2% organic material, including a nominal 0.6% starch sprayed onto the perlite, with a paper content not exceeding 1.4% including paper from clips (fiber) and paper from recycled panel materials. However the board of the present invention has high strength that is provided by the high paper fiber content in the surface layers.
In this embodiment, the composition of the three layers is shown below in Table 1, including bottom surface layer (“SLB”), the top surface layer (“SLT”), and the center, core layer (“CL”).
The reinforcement process consists of laying out a fiberglass mesh over the forming belt, spreading the bottom surface layer, consisting of mixed paper fibers and plaster over the fiberglass mesh, followed by the application of additional water required for hydration. Once the surface layer/fiberglass mesh configuration has been established the core and top layers are mixed, spread and deposited over the bottom surface layer. At this point, a 3-layer mat is formed and brought forward to the precompressor where excess air is removed. Additional water required for hydration is added to the top surface layer and the mat is conveyed forward through the press. In the press the materials are compressed and the plaster sets to bind all the materials together in the green /. At the same time the fiberglass mesh is embedded solidly into the bottom surface of the green board.
The continuous green board exits the press, is cut to size with a high-pressure water-jet and individual panels are conveyed to the dryer. The free moisture after hydration is removed, the panels are conveyed to the coating line where a sealant Is applied to the top surface of the panels. The panels are then conveyed to a secondary dryer where excess moisture is removed from the top surface of the panels. The panels are conveyed to the finishing line, cut-to-size, graded and packaged for shipping.
The following example will serve to illustrate the manufacture of a gypsum/fiber board product within the present invention, that is a three layer fiber-reinforced board produced with a core having a relatively low content of organic material in order to be classified as a noncombustible building material as specified by various building codes (e.g. BOCA) and as tested according to ASTM E136. The board of the present invention achieves a noncombustible rating because the composition of the core contains a total of not more than about 2% organic materials, including a nominal 0.6% starch sprayed onto the perlite, and a paper content not exceeding 1.4% including paper from clips (fiber) and paper from recycled panel materials. However, the board of the present invention has high strength that is provided by the paper fiber content in the surface layers. However, it should be understood that this example is set forth for illustrative purposes and that many other gypsum fiber products are within the scope of the present invention.
Composite paperless fiber reinforced gypsum panels are produced in the following manner. Calcined gypsum (calcium sulfate hemihydrate) is blended with recycled paper fibers, expanded perlite, starch, water and potassium sulfate to form a three-layer board. Three formulations of fiber and gypsum, shown below in Table 2, are prepared for use as the bottom surface layer (“SLB”), as the top surface layer (“SLT”), and as the center layer (“CL”). These formulations are used to prepare a 3-layer gypsum/fiber board ⅝ inches thick, using the continuous process and apparatus described above under the heading “MULTI-LAYER GYPSUM FIBER BOARD.”
Part of Total Board %
Component in Layer
Dry Basis Total Layer
Wet Basis Total Layer
The fiber used is a scrap paper fiber from magazines, newspapers and similar materials. The “plaster” is about 97% calcium sulfate hemihydrate, the balance being inert impurities. The plaster requires about 18% by weight of water to form the complete hydrate. The reinforcing mesh was the Bayex 0038/503, described above.
The resulting three-layer board is ⅝ inches thick and has a density of 55 pounds per cubic foot of which the center layer is 44% and the surface layers 28% each. Owing to the relatively low paper content of the center layer, the resulting board may be classified as a noncombustible building material as specified by various building codes (e.g. BOCA). The improved fiber-reinforced board of the present invention achieves a noncombustible rating because the building codes (e.g. BOCA) allows the removal of ⅛″ from both the top and the bottom layers of the board prior to combustion testing. With the removal of the surface layers containing relatively high levels of paper fibers, the remaining portion, the core, is noncombustible when tested in accordance with ASTM E136. Prior art fiberboards are relatively noncombustible because they employ noncombustible fiber such as asbestos and minerals such as aluminum trihydrate, which reduces the heat released during the combustion test. The board of the present invention achieves a noncombustible rating because the composition of the core contains a total of not more than about 2% organic materials, including a nominal 0.6% starch sprayed onto the perlite, and a paper content not exceeding 1.4% including paper from clips (fiber) and paper from recycled panel materials. However, the board of the present invention has high strength that is provided by the paper fiber content in the surface layers. The board had superior impact resistance, as shown by ASTM Test E-695, compared to similar board with no mesh reinforcement.
The board produced in the foregoing example was tested for impact resistance in accordance with the test method as prescribed under ASTM E695. Several commercially available ⅝-inch thick boards were also tested in accordance with ASTM E695. The results of the tests are shown below in Table 3.
IMPACT STRENGTH (ft-lb)
Type X gypsum board
BOARD OF EXAMPLE
Type X gypsum board is a conventional gypsum wallboard. The FIBEROCK AR is a commercial product designated as Abuse Resistant that is produced without fiberglass mesh. The impact strength of the BOARD OF EXAMPLE exceeded the maximum limit of the apparatus on which it was tested.
The forms of invention shown and described herein are to be considered only as illustrative. It will be apparent to those skilled in the art that numerous modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2200155||Nov 21, 1936||May 7, 1940||United States Gypsum Co||Manufacture of wallboard having a cementitious core|
|US4257710||Jan 15, 1979||Mar 24, 1981||Saint Gobain Industries||Continuous process mixing of pulverized solids and liquids and mixing apparatus|
|US4288263||Jan 15, 1979||Sep 8, 1981||Saint Gobain Industries||Process for making plaster board|
|US4334786||Jan 15, 1979||Jun 15, 1982||Saint Gobain Industries||Process and mechanism for evolutive pulp flow regulation|
|US4364790||Nov 26, 1980||Dec 21, 1982||Saint Gobain Industries||Apparatus for making plaster board|
|US4378405||Sep 17, 1981||Mar 29, 1983||Bpb Industries Public Limited Company Of Ferguson House||Production of building board|
|US4383960 *||Jun 4, 1981||May 17, 1983||Adrien Delcoigne||Process and mechanism for the elimination of excess water from a mixture of plaster and water, and the product obtained|
|US4450022||Jun 1, 1982||May 22, 1984||United States Gypsum Company||Method and apparatus for making reinforced cement board|
|US4572861||Jun 12, 1984||Feb 25, 1986||Consultora Sides C.A.||Prefabricated element for use in particular in the building industry and a method of manufacture of said prefabricated element|
|US4647496||Feb 27, 1984||Mar 3, 1987||Georgia-Pacific Corporation||Use of fibrous mat-faced gypsum board in exterior finishing systems for buildings|
|US4916004||Dec 27, 1988||Apr 10, 1990||United States Gypsum Company||Cement board having reinforced edges|
|US5135805||Jul 27, 1990||Aug 4, 1992||Georgia-Pacific Corporation||Method of manufacturing a water-resistant gypsum composition|
|US5221386||Apr 7, 1989||Jun 22, 1993||United States Gypsum Company||Cement board having reinforced edges|
|US5320677||Oct 15, 1991||Jun 14, 1994||United States Gypsum Company||Composite material and method of producing|
|US5342566||Aug 23, 1990||Aug 30, 1994||Carl Schenck Ag||Method of manufacturing fiber gypsum board|
|US5350554||Jul 16, 1993||Sep 27, 1994||Glascrete, Inc.||Method for production of reinforced cementitious panels|
|US5477652||Dec 7, 1993||Dec 26, 1995||General Electric Company||Composite security wall systems|
|US20020095893||Feb 26, 1999||Jul 25, 2002||James M. Slattery||Building board|
|EP0003705A2||Feb 6, 1979||Aug 22, 1979||Saint-Gobain Industries||Method and device for manufacturing a plaster web or plaster panels and panels so produced|
|EP0154094A2||Dec 28, 1984||Sep 11, 1985||Georgia-Pacific Corporation||Fibrons mat-faced gypsum board and its use in exterior insulation, in finishing systems for buildings and in shaft wall assemblies|
|FR2457754A1||Title not available|
|FR2547533A1||Title not available|
|GB771581A||Title not available|
|GB772581A||Title not available|
|GB1536663A||Title not available|
|GB2225599A *||Title not available|
|GB2316693A||Title not available|
|JPH0312205U||Title not available|
|JPH0797249A||Title not available|
|JPH0842111A||Title not available|
|JPH03120013A||Title not available|
|JPH04501703A||Title not available|
|JPH06198618A||Title not available|
|JPH06505448A||Title not available|
|JPS54117521A||Title not available|
|JPS55162487A||Title not available|
|JPS58219009A||Title not available|
|JPS60226933A||Title not available|
|JPS63502975A||Title not available|
|WO1998009033A1||Aug 19, 1997||Mar 5, 1998||Bpb Plc||Building board|
|1||Al Moslemi "Inorganic Bonded Wood and Fiber Composite Materials" 1990, pp. 85-87.|
|2||*||Fiberbond VHI Very High Impact Fiber-Reinforced Gypsum Wallboard Panels, May 1994.|
|3||James Y. Oldshue, "Fluid Mixing Technology", pp. 94-95 and 525-533, McGraw-Hill, Dec. 1983.|
|4||Louisiana Pacific "Fiberbond VHI Specifications", 1994, Two Pages.|
|U.S. Classification||156/39, 156/44, 156/42, 156/346|
|International Classification||B28B23/02, C04B2/02, B28B1/52, B28B23/00, E04C2/04, B32B37/15, B32B13/02, B32B37/24, B32B13/14|
|Cooperative Classification||B28B1/522, E04C2/043, B28B1/526, B28B19/0092, B28B23/0006|
|European Classification||B28B19/00K, E04C2/04C, B28B1/52C, B28B1/52F, B28B23/00A|
|Jan 18, 2011||CC||Certificate of correction|
|Jul 21, 2014||FPAY||Fee payment|
Year of fee payment: 12