Conductive paper for forming electroactive surface during construction

Abstract

To provide a method and a material for controlling the electrical conductivity and electromagnetic shielding capabilities of surfaces in building construction.SOLUTION: There is provided a building construction product with a conductive surface 14a. The building construction product includes a core 12 having one or more surfaces covered with conductive paper 14 including carbon fiber. The conductive paper is attached to one or more surfaces of the core.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to construction products that include electrically conductive surfaces, as well as methods and materials for controlling the electrical conductivity and electromagnetic shielding capabilities of surfaces in building construction. [Background technology]

[0002] In building construction, various types of panels are used to form interior and exterior walls, roofs, floors, and ceilings. Often used in interior wall construction is paper-faced gypsum board, commonly called wallboard. Typically, wallboard (also called drywall or gypsum panel) is formed by preparing a slurry containing calcined gypsum, water, and other ingredients. The gypsum slurry is then deposited between two sheets of paper. After the gypsum slurry sets, it forms a gypsum core between two paper cover sheets. U.S. patents such as 8,197,952, 4,853,085, and 1,769,519 relate to gypsum wallboard and methods of forming it. Other building construction products include ceiling tiles, doors, fiberboard, floor tiles, etc.

[0003] In some situations it may be necessary to manufacture construction products with conductive surfaces or to retrofit construction products with conductive surfaces. Such products may be used as shields from electromagnetic waves, for example when radio and / or wifi connections need to be blocked.

[0004] US Patent No. 5,422,174 discloses an electromagnetic wave shielding building material comprising a hydraulic inorganic material and 0.6-3% by weight of carbon fiber mixed with cement. US Patent No. 9,840,851 discloses a building construction material comprising coatings and layers embedded in or encapsulated by a core that provide sound attenuation or blocking. WO99 / 62076 discloses a composite material comprising a thin conductive cellulose layer having the ability to shield electric waves and high frequencies. US Patent No. 8,211,556 discloses a gypsum-based building material comprising graphite and having electromagnetic shielding capabilities. US Patent No. 7,641,764 discloses a nonwoven fabric for gypsum boards comprising 20-60% by weight of glass fiber and carbon fiber as conductive fibers. US Patent No. 5,496,966 discloses a building absorber that provides a surface for absorbing incident electromagnetic signals in a selected frequency range. The panel absorber includes an absorbing layer that is preferably a carbon fiber, carbonyl iron powder, or ferrite material disposed between the upper and lower surfaces of the absorber. Summary of the Invention [Problem to be solved by the invention]

[0005] However, there remains a need in the field of construction products with conductive surfaces whose electroactivity can be controlled and regulated on demand. There is also a need for materials and methods by which construction products can be retrofitted with conductive surfaces.

[0006] In one aspect, the present disclosure provides a building construction product with a conductive surface, the building construction product includes a core having one or more surfaces covered with a conductive paper containing carbon fiber, the conductive paper being attached to one or more surfaces of the core. The building construction product can be a wallboard, fiberboard, ceiling tile, floor tile, door, plank, frame, or roof tile. The building construction product can be a wallboard, and the conductive paper containing carbon fiber is applied to at least one of the long surfaces of the wallboard.

[0007] In any of the building construction products of the present disclosure, the conductive paper cover sheet may be a multi-layer paper including a surface layer in which carbon fibers are incorporated into the surface layer. Suitable carbon fibers include long carbon fibers, short carbon fibers, or any mixture thereof.

[0008] In some building construction products, the paper cover sheet is a multi-layer paper cover sheet including a surface layer, in which carbon fibers are incorporated into the surface layer in an amount between 2% and 40% of the total fibers per layer, with the remaining fibers in the layer being cellulose fibers.

[0009] In some building construction products, carbon fiber is incorporated into a paper cover sheet in a pattern.

[0010] In a further aspect, the present disclosure provides a conductive paper comprising a surface layer and one or more filler layers below the surface layer, the conductive paper comprising carbon fibers in at least the surface layer. In some embodiments, the conductive paper may further comprise carbon fibers in one or more filler layers below the surface layer.

[0011] Suitable carbon fibers have diameters ranging from 1 to 15 micrometers (μM) and lengths ranging from 1 to 20 millimeters (mm). The carbon fibers may be short carbon fibers, long carbon fibers, or any combination thereof. The carbon fibers may be mixed with cellulose fibers. Some of the conductive papers may further include carbon nanotubes.

[0012] In some embodiments of the conductive paper, carbon fibers are incorporated in an amount of 2% to 40% by weight of the total fibers per surface layer, and the remaining fibers in the surface layer may be cellulose fibers.

[0013] In some embodiments of the conductive paper, the carbon fibers may be in an amount of 2% to 5% by weight of the total fibers per surface layer, and the remaining fibers in the surface layer may be cellulose fibers. The carbon fibers may be incorporated into the surface layer in a pattern. In some of the conductive papers, the carbon fibers in the surface layer are oriented parallel or nearly parallel to each other.

[0014] In a further aspect, the present disclosure provides a conductive paper screen comprising one or more suspension means and a conductive paper comprising a surface layer and one or more filler layers below the surface layer, the conductive paper comprising carbon fibers in at least the surface layer.

[0015] In a further aspect, the present disclosure provides a method for imparting a conductive surface to a building construction product, the method comprising: a) forming a paper sheet from a paper stock containing carbon fibers and / or embedding carbon fibers in a pattern in the formed paper sheet; b) drying the paper sheet; and c) attaching the paper sheet to one or more surfaces of the building construction product.

[0016] A further aspect of the present disclosure includes a method for shielding an area from electromagnetic waves, the method including surrounding the area with a conductive paper including a surface layer and one or more filler layers below the surface layer, the conductive paper including carbon fiber in at least the surface layer.

[0017] Another aspect of the present disclosure includes a method for shielding an area from electromagnetic waves, the method including surrounding the area with a conductive paper including a surface layer and one or more filler layers below the surface layer, the conductive paper including carbon fiber in at least the surface layer.

[0018] Further methods include navigation methods, including indoor navigation, where navigation is guided by detecting signals generated by a conductive surface of the building construction product of the present disclosure. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of a building construction product including a conductive surface. [Diagram 2] FIG. 2 is a cross-sectional view of a conductive multi-layer paper containing carbon fibers. [Diagram 3] FIG. 3 is a block diagram of the manufacturing process for the conductive paper cover sheet containing carbon fibers. [Figure 4] FIG. 4 is a schematic diagram of a continuous manufacturing process for building construction products including conductive surfaces. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] In one aspect, the present disclosure provides a building construction product comprising an electrically conductive surface. As shown in Figure 1, the building construction product, generally (10), comprises a core (12) covered on one side with a paper cover sheet (14). The paper cover sheet (14) is electrically conductive and comprises carbon fiber. The paper cover sheet (14) is attached (glued, bonded) to the core (12). The paper cover sheet (14) creates an electrically conductive surface (14a) of the building construction product (10).

[0021] The paper cover sheet (14) may be attached to the core (12) by any means. The core (12) may include a cementitious material and / or an adhesive, and the paper cover sheet (14) may be bonded to the core (12) during the setting reaction of the cementitious material. Alternatively or additionally, the paper cover sheet (14) may be bonded to the core (12) using an adhesive, for example, starch, glue, polymeric binder. To attach the paper cover sheet (14) to the core (12), the paper cover sheet (14) may include an adhesive layer and / or an adhesive may be applied to the paper cover sheet (14) and / or the core (12). Additionally or alternatively, the paper cover sheet (14) may be attached to the core (12) by nails, adhesive tape, staples, screws, or any other means commonly used in construction to attach a paper cover sheet to a surface. In some embodiments, the paper cover sheet (14) may be wrapped around the core (12).

[0022] The building construction product (10) may be a wallboard, fiberboard, tile, ceiling tile, floor tile, door, plank, frame, roof tile, or any other construction product. In the diagram of FIG. 1, the construction product (10) can be characterized by its length (denoted as "L" in FIG. 1) and the thickness of the core (12) (denoted as "W" in FIG. 1). Because the length "L" is greater than the thickness "W", the construction product (10) has two long surfaces, one of which is the conductive surface (14a) shown in FIG. 1.

[0023] As can be seen from Figure 1, the building construction product has a second long surface (not shown in Figure 1) of the core (12) opposite the conductive surface (14a). This second long surface may be covered with a paper cover sheet (16). The second paper cover sheet (16) may be a paper cover sheet that does not contain carbon fibers, or the second paper cover sheet (16) may also contain carbon fibers to create a second conductive surface.

[0024] In alternative embodiments, the paper cover sheet (16) may be absent or may be replaced with a fiberglass mat (not shown in FIG. 1). In the illustration of FIG. 1, the paper cover sheet (16) and the paper cover sheet (14) are applied directly over the core (12). In further embodiments, there may be one or more intermediate layers (not shown in FIG. 1) disposed between the core (12) and the paper cover sheet (16) and / or the paper cover sheet (14).

[0025] The one or more intermediate layers may be one or more of an adhesive layer, a fiberglass mat, an insulating material, another paper cover sheet, a reinforcing layer such as a mesh or screed, a coating, a primer, or any combination thereof. In some embodiments (not shown in FIG. 1), the product (10) does not include a core (12) and / or a paper cover sheet (16). In these embodiments, the building construction product includes a paper cover sheet (14) with a conductive surface (14a).

[0026] In some embodiments, the conductive surface (14a) is applied to a front surface of the building construction product (10) that faces the interior of an enclosure, e.g., a room, after the building construction product is installed.

[0027] In other embodiments, the conductive surface (14a) surrounds the outside of the facility. In these embodiments, the other paper cover sheet (16) faces the inside of the enclosure, e.g., a room, while the conductive surface is on the opposite side.

[0028] The core (12) may be a cementitious core including one or more of cement, gypsum, and / or any other hydraulic material. The core (12) may further include organic and / or inorganic fibers, binders, organic and / or inorganic fillers, and other compounds. In some embodiments, the core (12) is a gypsum core traditionally used in wallboard, fiberboard, or ceiling tiles. In further embodiments, the core (12) may be a plank, mat, underlayment, pipe, or any other building construction substrate having one or more surfaces.

[0029] In this disclosure, the paper cover sheet (14) containing carbon fiber is referred to as a conductive paper cover sheet. The conductive paper cover sheet of this disclosure is capable of conducting electric current and has low electrical resistance and low electrical resistivity values ​​compared to conventional paper cover sheets, such as manila grade paper cover sheets or any other conventional paper cover sheets used for wallboard. These conventional paper cover sheets do not contain carbon fiber and have infinite resistance.

[0030] This distinguishes the conductive paper cover sheet of the present disclosure from conventional paper cover sheets that do not contain carbon fibers. Conventional paper cover sheets are not conductive materials and have infinite resistance. The conductive paper cover sheet of the present disclosure has electrical conductivity and good electromagnetic shielding ability.

[0031] In a further aspect, the conductive paper cover sheet is a building construction product that can be used to create a conductive surface on any surface or any portion thereof, including walls, partitions, roofs, ceilings, floors, windows, or doors. In these embodiments, the conductive paper cover sheet can be used to retrofit facilities, such as research facilities or conference rooms, that include wall panels that are already installed. For example, the conductive paper cover sheet of the present disclosure can be used as wallpaper that is installed in a room or any other facility or enclosure.

[0032] The conductive paper cover sheet of the present disclosure may be a single layer paper containing carbon fiber or a multi-layer paper containing carbon fiber. The conductive multi-layer paper may include several central filler layers, typically 2 to 5 layers, pressed together with the surface layers.

[0033] Referring to FIG. 2, a cross-sectional view of one of the conductive multi-layer papers containing carbon fibers according to the present disclosure, generally (70), is shown. The conductive multi-layer paper (70) includes a surface layer (72) pressed together with several filler layers (74), (76), (78), and (78) that are stacked under the surface layer (72) in a pile. In the view of FIG. 2, only four filler layers are shown, but other papers according to the present disclosure may include more than four, e.g., five, six, or seven filler layers, or less than four, e.g., one, two, or three filler layers. In the view of FIG. 2, only one surface layer (72) is shown, but in other embodiments according to the present disclosure, the conductive paper cover sheet may include a second surface layer disposed as an outer layer opposite the surface layer (72). In still other embodiments, the surface of the underlying layer (80) opposite the surface layer (72) may be coated with an adhesive coating (not shown in the view of FIG. 2). This adhesive coating, when present, facilitates adhesion of the conductive paper to the core (12) of the building construction product (10).

[0034] In the conductive paper (70) of the present disclosure, carbon fibers are incorporated into at least the surface layer (72) that will become the surface of the building construction product (10) of the present disclosure (the electroactive surface (14a) in FIG. 1).

[0035] In some multi-layer conductive paper cover sheets, carbon fiber may be incorporated into all layers, even if the amount of carbon fiber varies between different layers, for example, all layers (72, 74, 76, 78, and 80) contain some carbon fiber. In other multi-layer conductive paper cover sheets, carbon fiber may be incorporated only into the surface layer (72). In other multi-layer conductive paper cover sheets, carbon fiber may be incorporated into the surface layer (72) and the filler layer (74) located immediately below the surface layer (72). In still other multi-layer conductive paper cover sheets, carbon fiber may be incorporated into the surface layer (72), the filler layer (74), and the filler layer (76) located immediately below the filler layer (74). Further embodiments include conductive paper in which carbon fiber is incorporated into the surface layer (72) and also into one to four filler layers stacked below the surface layer (72).

[0036] In the building construction product (10), a layer (80) is in contact with the core (12) of the building construction product (10). In some embodiments, this layer comprises carbon fiber in addition to or instead of the surface layer (72).

[0037] A variety of conductive carbon fibers are suitable for producing the conductive paper cover sheet of the present disclosure. Suitable carbon fibers include those made by any conventional method from polyacrylonitrile, lyonol, and / or pitch containing aromatic hydrocarbons. The pitch can be vegetable-based or petroleum-based.

[0038] The length and diameter of the carbon fibers may vary. Suitable carbon fibers include fibers composed primarily of carbon atoms having a diameter in the range of 1 to 15 micrometers (μM) and a length in the range of 1 to 20 millimeters (mm). Carbon fibers of other lengths and / or diameters may also be suitable. The carbon fibers may be coated with a coating comprising one or more compounds. The coating may be an organic coating and may comprise polyvinyl alcohol or any other organic or inorganic compound.

[0039] The length and / or diameter of the carbon fibers in any particular conductive paper cover sheet of the present disclosure may be adjusted as required to achieve a particular electromagnetic shielding capability and electrical conductivity as needed. For purposes of this disclosure, carbon fibers having a length of less than 10 mm, e.g., 2 mm, 3 mm, 4 mm, or 5 mm, are said to be short carbon fibers. Short carbon fibers have a diameter in the range of 1 to 15 μM. The length of the short carbon fibers is 1 mm to 10 mm. Preferably, the short carbon fibers are 1 mm to 5 mm in length.

[0040] For purposes of this disclosure, carbon fibers having a length of 10 mm or more, e.g., 10 mm, 11 mm, 12 mm, 13 mm, or 14 mm, are said to be long carbon fibers. Long carbon fibers have a diameter in the range of 1 to 15 μM. The length of long carbon fibers is 10 mm to 20 mm. Preferably, the length of long carbon fibers is 10 mm to 15 mm.

[0041] In some embodiments, the conductive paper cover sheet of the present disclosure comprises short carbon fibers, hi other embodiments, the conductive paper cover sheet of the present disclosure comprises long carbon fibers.

[0042] At least some of the conductive paper cover sheets of the present disclosure may include a combination of carbon fibers of different lengths. In some embodiments, the conductive paper cover sheets include a mixture of long and short carbon fibers that may be mixed together in at least the surface paper layer. In other embodiments, the conductive paper cover sheets of the present disclosure may include a surface layer and one or more filler layers below the surface layer with short carbon fibers, and / or one or more filler layers below the surface layer with long carbon fibers, and / or one or more filler layers below the surface layer with a combination of short and long carbon fibers.

[0043] At least some of the carbon fibers may be coated or surface treated to improve compatibility in the aqueous paper stock and to improve intermixing of the carbon fibers with the cellulose fibers.

[0044] In at least some embodiments, the conductive paper cover sheet may optionally include carbon nanotubes, which may be used in combination with carbon fibers in the surface layer and / or one or more filler layers.

[0045] In addition to carbon fibers, the conductive paper cover sheet includes cellulose fibers. Any cellulose fibers commonly used in wallboard cover sheets may also be suitable for the conductive paper cover sheet of the present disclosure. The cellulose fibers may be virgin fibers produced from some natural resources, such as wood or cotton, by chemical and / or mechanical methods. The cellulose fibers may be regenerated cellulose fibers obtained by repulping recycled paper. The cellulose fibers may be any combination of virgin and regenerated cellulose fibers. Preferred sources of regenerated cellulose fibers include old corrugated paper, kraft paper, and discarded newspapers.

[0046] In the conductive paper cover sheet, cellulose fiber is the main source of fiber in any layer of the conductive paper. It will be understood that the total amount of carbon fiber per layer may vary and be adjusted as needed to produce a conductive paper cover sheet with the specific conductivity and electromagnetic shielding ability that may be required for any particular application. The total amount of carbon fiber may also be adjusted by mixing short carbon fiber with long carbon fiber and / or using only long carbon fiber or only short carbon fiber as needed. Typically, when long carbon fiber is used, a higher conductivity may be achieved with a smaller amount of carbon fiber compared to the embodiment in which short carbon fiber is used.

[0047] Preferably, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% by weight (abbreviated as "wt" in the remainder of this disclosure) to 30% by weight of the total fibers in the layer, the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% by weight to 30% by weight of the total fibers in the layer, the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% by weight to 20% by weight of the total fibers in the layer, the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% by weight to 10% by weight of the total fibers in the layer, the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% to 10% by weight of the total fibers in the layer, with the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 2% to 5% by weight of the total fibers in the layer, with the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers. In some embodiments, the conductive paper cover sheet may comprise carbon fibers in an amount of 5% to 10% by weight of the total fibers in the layer, with the remaining fibers being cellulose fibers, e.g., virgin and / or regenerated cellulose fibers.

[0048] When the conductive multilayer paper includes carbon fiber in one or more filler layers in addition to the surface layer, the amount of carbon fiber in each filler layer may be the same or different. Furthermore, the amount of carbon fiber may be the same or different from that in the surface layer. In some embodiments, the surface layer may include 5% to 10% by weight of carbon fiber of the total fiber in the surface layer, while the filler layer may include 2% to 5% by weight of carbon fiber of the total fiber in the filler layer.

[0049] In the conductive paper of the present disclosure, the carbon fibers may be incorporated in a number of different ways. In some embodiments, the carbon fibers are uniformly mixed with the cellulose fibers throughout the layer. In these embodiments, the carbon fibers are randomly oriented within the layer.

[0050] In other embodiments, the carbon fibers may be incorporated in a pattern across the layer to create a conductive matrix within the layer. Some distribution patterns are such that the carbon fibers are oriented in a particular direction, for example, the carbon fibers are oriented parallel or nearly parallel to each other. When one or more filler layers, in addition to the surface layer, contain carbon fibers, the orientation pattern of the carbon fibers between two adjacent layers of the multilayer paper may be the same or different.

[0051] The conductive paper of the present disclosure can be formed by incorporating carbon fibers into various paper grades, including those disclosed in U.S. Patent Publication No. 2012 / 0088114. Suitable paper grades include manila, which has a smooth calendared finish, and news-lined, which has a rougher finish. Typically, both paper grades are multi-layered with at least one liner (surface) layer and multiple filler layers. The manila liner layer typically uses recycled paper from hardwood pulp with shorter fibers compared to the filler layer, where longer fibers are used. News-lined paper typically has the same fiber type in the liner layer as that used in the filler layer.

[0052] The carbon fiber containing surface layer may further comprise old corrugated container (OCC) or double lined kraft (DLK) waste paper.

[0053] With reference to FIG. 3, the present disclosure further provides methods for producing the conductive paper cover sheet of the present disclosure. In these methods, a modified conventional papermaking press can be used. For example, a Fourdrinier paper machine or any modification thereof can be used. The press can be further modified as necessary to allow the incorporation of carbon fibers in a pattern in which the orientation of the carbon fibers is pre-determined. The setup can include one or more computer processors with software, which calculates the amount and / or pattern of carbon fibers that may be required to achieve a particular level of electromagnetic shielding in the conductive surface produced. Thus, the present method produces a conductive paper cover sheet with a predetermined electromagnetic shielding capability and that may be required for any particular application.

[0054] FIG. 3 is a block diagram generally at 100 illustrating a method for making the conductive paper cover sheet (14). The method for forming the conductive paper cover sheet includes mixing a paper stock. The paper stock is a very dilute suspension of fibers in water. The paper stock includes water, cellulose fibers, carbon fibers, and other additives. The cellulose fibers can be, for example, virgin fibers produced from some natural sources such as wood or cotton by chemical and / or mechanical methods, regenerated cellulose fibers obtained by repulping recycled paper, or any combination of virgin and regenerated cellulose fibers.

[0055] Preferred sources of regenerated cellulose fibers include old corrugated cardboard, kraft paper, and discarded newspapers. The paper stock may further include one or more of the following additives: sizing agents, flocculants, defoamers, water retention agents, binders, fillers, deinking agents, and pigments. The carbon fibers may be surface treated or surfactants may be added to the paper stock to reduce the surface tension of the carbon fibers and improve the compatibility of the carbon fibers with the cellulose fibers in the paper stock.

[0056] Suitable surfactants may include, but are not limited to, ionic and nonionic surfactants having a medium or high hydrophobic / lipophilic balance ("HLB") of about 10 to about 18. Suitable dispersants may include naphthalene sulfonates and other alkylbenzene sulfonates, lignosulfonates, fatty alcohol ethoxylates, and alkylphenol ethoxylates. Other surfactants include alkyl sulfates such as ammonium lauryl sulfate and sodium lauryl sulfate, and related alkyl ether sulfates such as sodium laureth sulfate and sodium myreth sulfate, alkyl aryl ether phosphates, alkyl ether phosphates, sodium stearates, and quaternary ammonium salts.

[0057] Suitable sizing agents may include, but are not limited to, alum, rosin, rosin soup, alkyl ketene dimers, and alkenyl succinic anhydrides.

[0058] Suitable humectants may include, but are not limited to, polyacrylamide and polyethyleneimine.

[0059] Suitable fillers may include, but are not limited to, calcium carbonate, talc, and titanium dioxide.

[0060] Suitable binders may include, but are not limited to, styrene maleic anhydride copolymers, styrene-acrylate copolymers, and modified starches.

[0061] When layers of different chemical composition are pressed together to form a multi-layer paper sheet, such as in the case of a filler layer and a liner layer, separate paper stocks are prepared for such layers: for example, one stock is prepared for the liner layer and another stock is prepared for the filler layer.

[0062] The amount of carbon fiber in the paper stock varies and depends on the requirements of the particular conductive surface being produced. Increasing the amount of carbon fiber and / or using longer fibers helps produce a conductive paper cover sheet with stronger electrical conductivity.

[0063] Typically, paper stock for conductive paper may contain from about 2% to about 40% carbon fiber by weight, based on the total weight of all fibers by dry weight. For example, if a paper stock is prepared with 95 g of dry cellulose fiber and 5 g of dry carbon fiber, the paper stock is said to have 5% carbon fiber by weight, based on the total weight of all fibers by dry weight.

[0064] The composition of cellulose fibers in any particular paper stock will depend on the type of layer and / or paper being produced. Filler layers can be prepared from stiff paper stocks that may include kraft paper and cardboard scraps. Liner layers can be prepared from paper stocks that include flyleaf shavings and / or newsprint.

[0065] In the block diagram of Figure 3, the paper stock from the headbox (block 112) is dispensed at block (114) onto a forming mesh table, also called a wire Fourdrinier table, which moves continuously, where water is drained and a web for the paper layers is formed. The formed paper layers may already contain carbon fibers if carbon fibers were mixed with cellulose fibers in the paper stock from which the paper layers are formed. However, some paper layers may be formed from paper stock that does not contain carbon fibers.

[0066] After block (114), the shaped paper layer formed from paper stock that does not contain carbon fibers may be passed to block (116), a pattern forming station, where a set of rolls or some other means may be used to imprint the carbon fibers in a pattern into the shaped paper layer. By pattern, it is meant that the carbon fibers are oriented in a particular direction, for example, the carbon fibers may be imprinted parallel or nearly parallel to each other. The pattern forming station may be operated by a computer with software that calculates the pattern to be imprinted. In some embodiments, the pattern forming step may be omitted.

[0067] The formed paper layer, either directly from block (114) or from block (116), is then pressed in a press station (block 118) by a felt roller. If a multi-layer paper is to be formed, several layers are superimposed at this stage of the process. The layers are pressed in block (118). If the layers have different fiber compositions, the layers can be fed to the press station from several different layer forming mesh tables (not shown in the diagram of FIG. 3).

[0068] Thus, a multi-layered paper sheet can be formed that includes several inner filler layers and a surface layer (72) that includes carbon fiber.

[0069] After block (118), the pressed paper is dried in a multi-cylinder drying section (block 120) by passing through an additional set of felt rollers and dryers.

[0070] From block (120), the dried paper passes to a calender at block (122) where the dried paper is calendered for uniformity. The conductive paper is then wound into rolls at block (124) and is ready for various uses.

[0071] It should be noted that various modifications can be made to the method depending on the application for which the conductive paper is being made. For example, the conductive paper can be coated with a water-resistant coating and / or carbon fibers may be incorporated into one or more filler layers in addition to the surface layer.

[0072] In some embodiments, the conductive paper can be coated on one of its surfaces with an adhesive composition that creates an adhesive layer that adheres the conductive paper to a variety of substrates, such as, for example, concrete walls, gypsum panels, ceiling tiles, metal pipes, wooden planks, or other building construction surfaces that require a conductive surface to be retrofitted.

[0073] In yet another aspect, the present disclosure provides a method for manufacturing a construction product including a conductive surface.

[0074] In one embodiment, the wallboard including the conductive surface is manufactured by using conventional gypsum board forming methods and equipment. In these embodiments, a gypsum slurry is prepared with calcined gypsum and water. Typically, the gypsum slurry may include various other additives, which may include, but are not limited to, one or more of the following: binders, fillers, defoamers, organic and / or inorganic fibers, foams, dispersants, set retarders, set accelerators, biocides, and / or colorants.

[0075] 4 is a schematic diagram of a manufacturing process for gypsum wallboard with a conductive surface, generally (30). A first paper cover sheet (32) is fed onto a moving conveyor (36) from a roll (34). Gypsum slurry (38) is dispensed from a mixer (40) onto the first paper cover sheet (32), which in some embodiments is a conductive paper cover sheet containing carbon fibers as described in this disclosure.

[0076] A second paper cover sheet (42) is deposited on top of the dispensed gypsum slurry (38) from a roll (44). If the first paper cover sheet (32) does not contain carbon fiber, this second paper cover sheet (44) is a conductive paper cover sheet containing carbon fiber, as described in this disclosure. Note that in some other embodiments, both paper cover sheets (32) and (44) are conductive paper cover sheets containing carbon fiber.

[0077] Typically, the paper cover sheets (32) and (44) are multi-layer paper cover sheets. When the cover sheets (32) and / or cover sheets (44) contain carbon fiber, the carbon fiber is typically incorporated into at least a surface layer of the cover sheets (32 and / or 44), which remains a free surface opposite the surface of the cover sheets (32 and / or 44) that is in contact with the gypsum slurry (38). However, in at least some embodiments, the gypsum slurry can be placed in contact with the surface layer that contains the carbon fiber.

[0078] The shaped wallboard (46) then passes through a forming station equipped with forming means, e.g., rolls (48), where the distribution of the gypsum slurry (38) between the first paper cover sheet (32) and the second paper cover sheet (42) is homogenized by the forming means to form a shaped wallboard (46) of a predetermined thickness. As the shaped wallboard (46) leaves the forming station (48), it moves continuously on the conveyor (36) in a direction indicated by the arrow shown below the conveyor (36) until the gypsum slurry (38) congeals to produce a wallboard having a conductive surface (50). The wallboard (50) is then cut to size and dried in a dryer, e.g., a kiln.

[0079] In yet another embodiment, the present disclosure provides a method for imparting a conductive surface to a building construction product. The building construction product can be any of conventional wallboard, fiberboard, tiles, ceiling tiles, windows, floor panels, doors, pipes, planks, frames, or other construction products having at least one surface. A conductive paper cover sheet comprising the carbon fibers of the present disclosure can be attached to the surface of the building construction product.

[0080] In some of these embodiments, a self-adhesive pre-made conductive paper cover sheet of the present disclosure can be used and / or the conductive paper cover sheet of the present disclosure can be coated with an adhesive and then applied to the surface of the construction product. This method can be carried out on the surface of a construction product that is already in place.

[0081] Further methods of the present disclosure include shielding an area, such as a room, a set of rooms, a portion of a building, or a building, from electromagnetic waves, in which the area is surrounded by a cover sheet of conductive paper.

[0082] In a further embodiment, the construction product with a conductive surface includes a conductive paper screen, which may be foldable. The conductive paper screen includes the conductive paper cover sheet of the present disclosure and one or more hanging means. The hanging means may include one or more planks, e.g., plastic, metal, or wood planks, which may be assembled together to create a frame to which the conductive paper screen is then adhered. Additionally or alternatively, the hanging means may include wires, self-adhesive strips, ropes, and / or some adhesive. The conductive paper screen may be hung from a ceiling, wall, window frame, door frame, wall frame, and / or the conductive paper screen may be supported by a frame and be freestanding. The conductive paper screen may be used to create an enclosure for a portion of a room. This enclosure may shield a portion of a room from electromagnetic waves, for example, when some equipment sensitive to electromagnetic waves needs to be protected.

[0083] The conductive paper of the present disclosure can be used in a variety of applications. One application is to create various enclosures that shield from electromagnetic waves. This can be used to block the transmission of radio waves, including wifi signals, or to ensure communication only via specific waves permitted within the enclosure.

[0084] The building construction products of the present disclosure include a conductive surface created by a conductive paper cover sheet. The conductive surface can be used to block electromagnetic waves and / or as an electromagnetic signature (a signal detected by one or more detectors) for navigation, including indoor navigation, when an electric field is applied to the conductive surface. The conductive surface can also provide touch sensitivity when an electric field is applied to the surface.

[0085] Example 1. Three different types of conductive paper were produced. 1)OCC70%: Carbon fiber 3mm 30% (basis weight ~28lb / msf; msf means 1000 square feet) 2) OCC 80%: Carbon fiber 3mm 20% (basic weight ~28lb / msf) 3) OCC 90%: Carbon fiber 12mm 10% (basic weight ~26lb / msf)

[0086] All papers were single ply. Samples were cast on a Williams Standard Pulp Testing Apparatus using a 100 mesh screen.

[0087] Example 2. The resistance of the conductive paper samples of Example 1 was measured using a Fluke 115 True RMS multimeter. Conductive Papers 1, 2, and 3 had the following dimensions: approximately 8 inches by 4 inches.

[0088] Output is reported in kilohms. 1 kilohm = 1000 ohms. Conventional wallboard was used for comparison. Imgne X3 graphene enhanced conductive geotextile was used as a positive control. 1) OCC70%: Carbon fiber 3mm 30% (basis weight ~28lb / msf; msf means 1000 sq. ft.) = 0.006 kilohms 2) OCC 80%: Carbon fiber 3mm 20% (basis weight ~28lb / msf) = 0.010k ohms 3) OCC 90%: Carbon fiber 12mm 10% (basis weight ~26lb / msf) = 0.030k ohms 4) Imgne X3 graphene-enhanced conductive geotextile; vendor sample (www.imgne.com) = 1.095 kOhm 5) TRADITIONAL SHEETROCK WALL BOARD = INFINITE RESISTANCE

[0089] The resistance of the conductive paper samples ranged from 0.006 kilohms (sample 1) to 0.030 kilohms (sample 3), while the conventional wallboard without carbon fiber had infinite resistance. This result suggests that the conductivity of the conductive paper cover sheet can be adjusted as required by varying the length and / or amount of carbon fiber in the paper cover sheet.

[0090] [Note] [Appendix 1] 1. A building construction product with a conductive surface, the building construction product comprising a core having one or more surfaces covered with a conductive paper comprising carbon fiber, the conductive paper being attached to one or more surfaces of the core.

[0091] [Appendix 2] 2. The building construction product of claim 1, wherein the conductive paper comprises a surface layer and one or more filler layers stacked in a pile beneath the surface layer, the conductive paper comprising carbon fiber in at least one of the following layers: the surface layer, the one or more filler layers, or any combination thereof.

[0092] [Appendix 3] 3. The building construction product of claim 1 or 2, wherein the building construction product is a wallboard, a fiberboard, a ceiling tile, a floor tile, a door, a plank, a frame, a conductive paper screen or a roof tile.

[0093] [Appendix 4] 3. The building construction product of claim 1 or 2, wherein the building construction product is a wallboard having two long surfaces, and the conductive paper is attached to at least one of the long surfaces of the wallboard.

[0094] [Appendix 5] 3. The building construction product of claim 1 or 2, wherein the carbon fibers in the conductive paper have a diameter in the range of 1 to 15 micrometers (μM) and a length in the range of 1 to 20 millimeters (mm).

[0095] [Appendix 6] The conductive paper has the following characteristics: a) the carbon fibers are short carbon fibers, long carbon fibers, or any combination thereof; b) the carbon fibers are mixed with cellulose fibers in a random orientation; and / or c) the conductive paper further comprises carbon nanotubes.

[0096] [Appendix 7] 3. The building construction product of claim 2, wherein the carbon fibers are in an amount of 2% to 40% by weight of the total fibers per surface layer of the conductive paper, and the remainder of the fibers in the surface layer of the conductive paper are cellulose fibers.

[0097] [Appendix 8] 3. The building construction product of claim 1 or 2, wherein the carbon fibers are embedded in a pattern.

[0098] [Appendix 9] 3. The building construction product of claim 1 or 2, wherein the carbon fibers are oriented parallel or near parallel to one another.

[0099] [Appendix 10] 1. A method for imparting a conductive surface to a building construction product, comprising: a) forming a paper sheet from a paper stock containing carbon fibers and / or embedding carbon fibers in a pattern in the formed paper sheet; b) drying the paper sheet; and c) attaching said paper sheet to said building construction product.

Claims

[Claim 1] 1. A building construction product with a conductive surface, the building construction product comprising a core having one or more surfaces covered with a conductive paper comprising carbon fiber, the conductive paper being attached to one or more surfaces of the core.

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