Method of manufacturing paper based honeycomb core wallboard panel

Abstract

The instant invention is directed to a boric and boron based fire resistant wall board panel and method of manufacture. The wall board panels are formed from a pair of sheet members which are parallel in alignment and a honeycomb core sandwiched between the sheet members. The inner surfaces of the sheet members are coated with an adhesive material and the honeycomb core is impressed into the adhesive layers.

Description

FIELD OF THE INVENTION

This invention relates generally to the field of construction and in particular to a method of manufacturing a fire resistant wallboard panel for use in interior building wall construction.

BACKGROUND OF THE INVENTION

The most common type of wallboard used for interior wall construction in buildings is gypsum board, also known as drywall. It is commonly available under brand names such as Sheetrock or Gyproc. Typically, Gypsum is constructed by a continuous process, first by a Gypsum Slurry transferred on a paper fed composite that are rolled into a continuous flat sheets. The process results in a Gypsum drywall comprising a sheet of gypsum with a paper facing and paper backing.

The gypsum based drywall is used for the interior walls, ceilings, and partitions. It has a surface which is suitable for the reception of finish materials such as paint and wallpaper. While it is a useful and ubiquitous material in building construction, gypsum drywall is difficult to work with. The weight of the gypsum makes the sheets of drywall unwieldy and difficult to manipulate. In addition to its heavy weight, the drywall is extremely fragile and panels of gypsum drywall can easily crack if they are mishandled. Further, thicker drywall is necessary if sound deadening or greater insulation is desired.

The process of installation of the drywall panels requires that the panels be cut to fit around doors, windows and other openings, usually resulting in approximately one pound of waste for every square foot of finished house. The waste produced averages nearly one ton of gypsum drywall for each single family home built. A reason for the large amount of waste is that walls and ceilings are easier to tape and spackle and are less likely to develop cracks if they are covered with large pieces of drywall from which the openings are cut. Small pieces of drywall require significantly more time and labor for finishing. Also, the joints between them are susceptible to cracking over time.

Debris from construction, remolding, and demolition activities is estimated to account for approximately 24% of the solid waste that is discarded in the landfills across the United States, a large percentage of which is drywall. This large volume of waste creates serious environmental concerns. The disposal of waste gypsum drywall is problematic. Landfills receiving the waste drywall are becoming less available and more expensive.

A greater concern is the face that in a landfill the moist anaerobic conditions allow bacteria to reduce the sulfate component of the gypsum to hydrogen sulfide gas, carbon dioxide, and water. Hydrogen sulfide gas at low concentrations is noxious and at higher concentrations pose serious health and safety risks. Some landfills have already refused to accept drywall waste because of concerns about the hydrogen sulfide gas.

An alternative to the landfills is incineration. Incineration of drywall causes the sulfate present in the gypsum to be converted to sulfur dioxide gas. Air pollution concerns associated with this makes this alternative undesirable unless expensive scrubbers are employed. Another alternative is dumping the waste into the ocean. A study of this ocean dumping was performed by the Canadian government. While the conclusion of this study was that since the materials present in drywall are naturally present in the environment, this method would be environmentally benign. However, the highly negative public perception of ocean dumping of solid waste materials makes this option undesirable.

While it is technically feasible to recycle drywall, the high costs of recycling the drywall verses the relatively low costs of the raw gypsum make this practice economically undesirable. As a result of the grave environmental concerns associated with drywall, there is an urgent need for an alternative building material which can be used in place of gypsum drywall. The material should be able to be used in the same manner as gypsum drywall yet overcome the drawbacks and disposal problems associated with gypsum drywall. There is also a need for a wallboard material which is easier to handle than gypsum drywall, which can be inexpensively produced and which is environmentally friendly.

There are several examples in the prior art of wall panels incorporating a honeycomb core. These include U.S. Pat. Nos. 3,106,503; 3,785,788; 3,930,085; 5,498,462; 5,899,037; 6,253,530; 6,635,202; 6,743,497; and 6,852,192 and U.S. Publication No. 2005/0025929. From a manufacturing standpoint, honeycomb materials can be characterized as one of two types, expanded or non-expanded. The expanded types are formed from strips of a flexible material, such as paper or plastic, which are stacked and bonded along staggered joint lines. The structure is secured at the top and bottom surfaces and then the stack is pulled apart to produce the honeycomb structure. The stack can be fixed in its expanded form by immersion into a resin bath, or in the case of thermoplastic materials, the stack can be is heated to fix the cells in their expanded condition.

Another type of honeycomb material is non-expanded honeycomb material. This material consists of discretely formed hexagonal tubes which have been bonded together in a honeycomb formation. Each of the prior art references cited above have honeycomb cores which are fabricated using the expansion process.

SUMMARY OF THE INVENTION

The present invention is directed to a fire resistant wallboard made from paper constructed and arranged to form a honeycomb core sandwiched between outer layers. The resulting wallboard is lightweight yet has a superior tensile strength because of the honeycomb core. In particular, water based slurry processed into sheet paper may be composed of recycled and virgin cellulose, incorporating creation of partially soluble boric acid and borax pentahydrate solids. The panel comprises a pair of sheet members which are parallel in alignment and a honeycomb core sandwiched between the sheet members. The inner surfaces of the sheet members are coated with an adhesive material and the honeycomb core is impressed into the adhesive layers. The panels impregnated with fire retardant resultantly improve panel strength, reduce weight, improve workmanship characteristics, increase panel fire ratings, and reduce waste by being formed from recycled material, as well as being capable of one hundred percent (100%) recyclability. A honeycomb core is manufactured using sheet members that can also include insulation and/or fire-retardant material disposed within the core.

Accordingly, it is an objective of the instant invention to provide a wallboard panel which is lightweight, fire resistant, has a high tensile strength, and can be recycled.

It is a further objective of the instant invention to provide a wallboard panel constructed from virgin or recycled paper.

It is yet another objective of the instant invention to provide a new process for the manufacture of a honeycomb core allowing for a thicker piece of wallboard with enhance sound deadening characteristics.

It is a still further objective of the invention to provide a wallboard panel which is constructed from biodegradable materials.

It is a still further objective of the invention to provide a wallboard panel that is 100% recyclable, requires less labor to install, carries a higher insulation value, produces less waste, reduces shipping costs by virtue of its light weight, reduces the carbon footprint, and will have a greater green value than gypsum board.

Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with any accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. Any drawings contained herein constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a wallboard panel according to a preferred embodiment of the invention in which a surface is shown partially cut away.

FIG. 2 is a cross-sectional view taken along line2-2 in FIG. 1 which illustrates the wallboard panel of FIG. 1 fastened to a wall stud.

FIG. 3 illustrates indicia on the outer surface of the wallboard of FIG. 1.

FIG. 4 is a block diagram of the process of recycling paper products to produce recycled sheet paper.

FIG. 5 is a block diagram of the assembly for processing paper rolls into the fire rated wallboard panels.

FIG. 6 illustrates the honeycomb core in its expanded state.

FIG. 7 is a side view of the paper layers illustrating the spacing of the glue strips.

FIG. 8 illustrates how four rolls of paper are brought together to form the pre-expanded honeycomb core.

FIG. 9 is view of the rotary knives cutting the sheet of paper into strips.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-3, set forth is a wallboard panel 10 and method of construction that provides superior fire resistance by use of a boric and boron mixture, together with a construction that provides superior strength without the weight of conventional gypsum wallboards. The wallboard panel 10 can be utilized in the same manner as standard gypsum drywall and advantageously requires no special tools for installation. The wallboard panel 10 is constructed from facing sheet members 12 and 14 which sandwich a honeycomb core 16 therebetween. As seen in the cross-section view shown in FIG. 2, the facing sheet members 12 and 14 have inner and outer surfaces 12a, 12b, 14a and 14b respectively. The inner surfaces 12b and 14b are adhered to the honeycomb core 16. Use of the honeycomb core 16 produces a wallboard panel 10 which is lightweight and has a tensile strength superior to standard gypsum drywall. The honeycomb core 16 also provides superior noise suppression thereby providing superior soundproofing qualities compared to gypsum drywall. In the preferred embodiment of the invention the facing sheet members 12 and 14 and the honeycomb core are constructed from recycled paper. The resultant product is “environment-friendly” from the manufacturing standpoint as well as with regard to the ultimate disposal of the material.

Referring now to FIG. 4, the initial step in producing environment-friendly wallboard includes receipt of raw material 108 in the form of recycled paper in bales. These bales may weigh one thousand pounds and is primarily composed of newspaper and cardboard. Municipal recycling programs and general recycling efforts are the main source of raw materials. Though the paper to be recycled can come from a variety of sources, waste newspaper or other cellulose material is preferred. However, fibrous material such as cotton, wool, linen or the like can be used.

Raw material 108 is placed within a hydrapulper 110 for contaminant removal such as staples, baling wire, tape, and so forth. The raw material is initially soaked in water to soften, the material may also be ground up by grinder 109 to speed up the soaking process resulting in a slurry 111. Sufficient water is added to the raw material during the grinding process to create an aqueous slurry which is fairly viscous, yet pourable. The grinder 109 if of the type that does not destroy the long paper fibers used for strength in the final product. The length of the grinding is determined by the type of paper being treated. While acceptable materials continue through the process, rejected materials are discharged 113 for proper disposal.

Various additives and binders can be added to the aqueous mixture during the beating process. In order to add desirable properties to the finished product, fire-proofing chemicals, insect repellents, etc. are added at this stage. The mixture can also be impregnated with phenolic resin 112, as an optional step to further which provide waterproofing and insect resistance, as well as inhibiting the growth of fungus and molds. Optionally the paper can be impregnated with a quantity of resin, normally a water or other solvent-based resin, such as a low-emission, waterborne phenolic resin of the type sold by Georgia-Pacific Resins, Inc. of Decatur, Ga.

The treated slurry 114 is advanced from the screening process to a forward cyclone separator 116 where centrifugal force engages the treated slurry to separate paper fibers from contaminates 118. Heavy materials, such as gravel, fall to the bottom while lighter paper fibers flow to the top. Subsequent to the forward cyclone 116, the pulp enters a reverse cyclone 120 to separate fibers from contaminates by working in the opposite direction. The reverse cyclone causes heavy paper fibers to move towards and to the bottom of the tube. Oppositely, lightweight materials, such as plastics, move upward and are subsequently rejected 118.

A disk thickener 124 constructed of plates with bars and grooves of various sizes is used to thicken the treated slurry into a refined mixture 126 and contact the paper fibers to cause additional contact points to provide a stronger sheet paper. A concentration of boric acid and boron 128 is added to the mixture at the refining stage. The boric acid and boron are fire retarding additives. A preferable, non-limiting, mixture is between two to seven percent (7-25%) determinative upon the amount of the required fire rating. Boron is safe to use and its application is widely accepted. Boron naturally occurs as an element is has been tested to produce less smoke than other fire retardants. Borax, also known as sodium borate, sodium tetraborate or disodium tetraborate works interchangeable with boric acid and boron at the mixture rate between two to seven percent (7-25%). The composite fire treated paper wallboards distinct advantage over fire rated gypsum board is that it is 10% of the weight of gypsum. Higher fire ratings can be obtained without increasing the thickness or weight of the composite paper wallboard.

A portion of the pulp that will form the bottom ply of the paper shall be sent to through a cyclonic separator 130 with the cleaned material directed to a headbox 132 of a papermaking machine. The headbox 132 includes spray nozzles for delivering the mixture of pulp and water onto a moving screen 134, additionally known as a wire or “wet end” of the paper machine. As the pulp moves down the screen toward a press section 136, water drains out and the pulp begins to form a sheet of paper. The press section 136 includes continuous loops, known as “felts”, for carrying the paper through the press. The press squeezes water from the sheet, in preferred embodiment of the instant invention, the paper sheet is forty percent (40%) fiber and sixty percent (60%) water. The thickness of said wallboard panel adjacent the longitudinal each of the edges is reduced.

A second set of felts carry the paper through a dryer section 138 which employs steam-heated rolls or “cans” to dry the paper. The paper is dried by thirty-three steam-heated cans to reduce the moisture content to approximately seven percent (7%).

After the dryer section, the paper passes through a plurality of dryer calendar rolls 140 constructed and arranged to smooth the surface of the paper. The finished roll 140 is wound on a jumbo roll or reel which may be weigh twenty-five tons. The finished roll 140 is rewound onto smaller rolls 142. The smaller rolls weigh typically weight less than three tons.

Referring now to FIG. 5, illustrates a block diagram detailing the assemblage of paper rolls into fire retardant board having a particular fire rating. The rolls are mounted onto a board machine 144 and fed at the leading edges of the paper through and across a plurality of rollers. From the board machine 144, a set of rollers shall apply glue strips 146 to the sheet of paper. Preferably, the glue strips 146 shall be applied alternately to the surface of the sheet of paper drawn across the rollers. In an exemplary embodiment, the glued paper is joined against other sheets, pressed together and pulled forward as a sheet of ply paper having multiple layers 148.

The sheets 148 are then cut and stacked, and subsequently the stacked sheets are cut into paper strips 150. The paper strips are separated and assembled on a layout table 152. Once assembled, the strips are fed through a set of rollers where glue 156 is applied to the top and bottom edges 154. The glued strips are fed through rollers where they are pulled to expand the formed honeycomb cells 158. The honeycomb cells are placed upon a solid sheet of paper on the set up table and the top is covered with a solid sheet of paper, the composite is drawn through rollers forming a honeycomb sheet press 160 to press the composite onto glued 157 areas. A plurality of honeycomb core cells with plaster 159. The core cells filled with plaster are preferably arranged in vertical and horizontal lines to facilitate attachment to wall studs. The core cells filled with plaster can be marked with indicia to illustrate location of the filled cell. The filled cell prevents the sidewall collapse with a nail or screw fastener is used to attached the wall board to a framing stud. Further, the filled cell allows additional support for attaching of a picture or other wall hanging item. The finished product 162 may be stacked for shipping.

It should be noted that plaster and/or cement 162 can be added to strengthen the final product. A mixture including about 20-50% plaster will produce a textured stone hard material. Use of a plaster-impregnated material to fabricate wallboard in accordance with the invention will produce a product suitable for outdoor use.

In addition to the above, the slurry may be poured into a mold and compressed to form a mat. The strength of the final product is a function of the degree of pressure applied. Greater pressure generally results in a stronger product. In order to obtain satisfactory strength characteristics, it is preferable to use pressures from about 700 to 2000 pounds per square inch (psi). If binders such as plaster and concrete are used, the compressed slurry must be allowed to harden while under the pressure.

Referring to FIGS. 6-8, the honeycomb core is formed by combining four layers of paper 34, 36, 38 and 40 having strips of glue 42 at specific locations, in a stacked relation with each layer on top of the previous layer. The glued portions of each layer are spaced from each other in such a manner that the glued portions of each layer are adhered to the adjacent layer of paper below. The non-adhered portions of the layers permit the combined layers to be pulled apart to form a honeycomb structure. Each of the four layers of paper contains a narrow band of glue 42 which extends the entire width of each layer. The glue bands of adjacent layers of paper are offset from each other as illustrated in FIG. 7. In a preferred embodiment layers of paper are removed from four rolls of paper 44, each roll being four feet wide. Glue is applied in a narrow band to the width of each roll by applicators 46. The bands of glue are spaced apart approximately one inch in a preferred embodiment. The bands of glue in adjacent rolls are offset by one half of the distance between the bands or approximately ½ inch so that adjacent layers of paper can be attached to each other thereby forming a honeycomb core. Each layer of paper is passed over a roller 48 after the glue is applied. This roller helps to align the layers of paper into a stacked relationship. After the four layers of paper are attached to each other they are passed over roller 52 and then through a cutter 54 which cut the four foot wide sheets of paper into a plurality of ⅜ inch wide strips. The cutter 54 comprises an axle 56 onto which a plurality of rotary cutting wheels 58 are rotatably mounted. As the layers of paper pass the cutter the cutting wheels cut the paper into strips approximately ⅜ inch wide.

A ⅜ inch wide strip of four sheets of paper are placed on top of another ⅜ inch wide strip of four sheets of paper such that the bottom sheet of the first or upper group is adhered to the top sheet of the second or lower group. This process forms a honeycomb core material which can be expanded to twice the width of a single group of sheets. The strips or groups of paper are attached on top of each other until an expanded section of honeycomb material up to 12 feet long is formed.

The inner surfaces 12b and 14b of the sheet members are respectively coated with adhesive layers 21 and 23. The adhesive is preferably a one component, solvent free, moisture curing, non-volatile urethane adhesive such as Mor-AdM-612, produced by Morton International. Mor-Ad division, of Chicago, Ill. Another suitable adhesive is a two component epoxy resin such as one sold under the brand name Stic-Bond, available from Stic-Adhesive Products Co. Inc., of Los Angeles, Calif. The adhesive layers 21 and 23 are preferably about 5 mm thick. To assemble the wallboard panel 10, the honeycomb panel 16 is impressed into the adhesive layers 21 and 23. Prior to assembly, the open cells of the honeycomb core 16 can be filled with a desired material, such as a fiberglass insulation or a fire-retardant material. The open cells of the honeycomb adjacent all of the outer peripheral edges of the wallboard panel 10 are preferably filled with a viscous material which will harden as it dries. This prevents fraying of the edges of the wallboard. The finished wallboard is preferably ½ inch thick. However, additional wallboard panels could be formed with different thicknesses conforming to conventional wallboard thicknesses.

Along each longitudinal edge of the wallboard the thickness of the wallboard is reduced to allow for the use of tape and spackle to finish the installed wallboard. Normally the abutting edges of wallboard result in a visible joint which must be hidden to produce a finished wall. The joint in normally covered with a tape and spackling compound. To allow for the tape and spackle to be placed on the wall without increasing the overall thickness of wall, the thickness of conventional wallboard adjacent these edges is reduced. Accordingly, the thickness along the longitudinal edges of the wallboard of the instant invention will also be reduced.

In use, the wallboard panel 10 is attached to adjoining studs in a wall or joists in a ceiling using an attachment means such as nails or screws. In order to provide a stable anchor for the attachment means a portion of the honeycomb cells 19 can be formed with reinforcing material. The honeycomb core includes a solid cell 25. The solid cell 25 can be formed by filling hollow cells 19 with a suitable viscous material which will harden as it dries. The solid cell 25 is preferably comprised of a material having a sufficient hardness to hold a nail, or other attachment element, in place, but not so hard as to require pre-drilling of the cell prior to penetration by the nail or drywall screw. FIG. 2 illustrates the wallboard panel 10 attached to a wall stud 50 by a fastener 60, nail or screw, which penetrates the solid cell 25.

The solid cells 25 are arranged in a regular pattern within the honeycomb core 16. The solid cells 25 are preferably arranged in vertical and horizontal lines to facilitate attachment of the wallboard 10 to the wall studs 50. The frequency of placement of the solid cells 25 within the honeycomb core can be varied depending on the particular application. As shown in FIG. 3, the outer surfaces 12a and 14a are marked with indicia 30 illustrating the location of the solid cells 25 within the wallboard panel 10 to enable someone installing the wallboard to readily locate the solid cells 25 during the installation process.

The wallboard panel 10 can be manufactured in various sizes depending on application requirements. The wallboard preferably has a standard depth and the width and length can have any desired dimensions. For example, the width of the wallboard panel 10 can be a standard 4 feet and the lengths can be in multiples of one foot. Also, papermaking techniques may be used to make the panels in a continuous running length by pouring the slurry onto a moving weir screen wire to a particular depth and delivering the wet material to pressure rolls for compaction and drying, the continuous batt goes through punching rolls which may have a pattern of punches. The areas not punched contain the solid material. Various materials may be added to the punched batt to fill other apertures. Continuous sheets of paper are delivered to both sides of the batt with adhesives applied to the batt or the sheets. The complete panel is compressed again to set the adhesives, then the continuous panel is delivered to a cutter for sizing.

All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. All patents and publications are herein incorporated by reference to the same extent as if each individual publication was specifically and individually indicated to be incorporated by reference.

It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.

Claims

1. A process for forming a fire-resistant honeycomb wallboard structure comprising: creating a slurry of paper pulp by use of a hydrapulper;inducing a forward cyclonic flow to remove heavier materials;reverse the cyclonic flow to remove lighter materials;thickening of said treated slurry;admixing a concentration of boric acid and boron between about 7-25% with said thickened treated slurry;inducing a forward cyclonic flow to remove heavier materials participated out by said admixing step;spraying said treated slurry on a moving screen having a width to obtain a uniform thickness;removing excess water from said treated slurry forming sheet of conditioned paper having a longitudinal length;applying a plurality of glue bands to one side of said base sheet of conditioned paper, each glue band being relatively short compared to the length of said base sheet of conditioned paper and extending substantially the width of said base sheet of conditioned paper;arranging an adjacent sheets of conditioned paper in a stacked relationship on top of said base sheet of conditioned paper having glue bands;applying glue bands on each said adjacent sheet of conditioned paper being spaced apart in a staggered relationship such that the glue bands on each said adjacent sheet of conditioned paper are spaced midway between the glue bands on the previous sheet of conditioned paper;expanding said stacked sheets of conditioned paper forming a honeycomb structure having individual core cells; andsecuring said honeycomb structure between a first and second side sheet of conditioned paper to form a wallboard panel.

2. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 wherein the thickness of said wallboard panel is reduced along the longitudinal length.

3. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 wherein said step of removing excess water from said treated slurry to form a said conditioned sheet of paper creates a structure having about forty percent (40%) fiber and sixty percent (60%) water.

4. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 wherein boric acid and boron are fire retarding additives admixed between two to seven percent (7-25%).

5. The process of forming a fire-resistant honeycomb wallboard structure according to claim 4 wherein boric acid and boron is borax.

6. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 wherein said glue is a one component, solvent free, moisture curing, non-volatile urethane.

7. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 wherein said glue is a two component epoxy resin.

8. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 including the step of filling a plurality of honeycomb core cells.

9. The process of forming a fire-resistant honeycomb wallboard structure according to claim 8 wherein a plurality of core cells are filled with plaster.

10. The process of forming a fire-resistant honeycomb wallboard structure according to claim 9 wherein said filled core cells are marked with indicia to illustrate location.

11. The process of forming a fire-resistant honeycomb wallboard structure according to claim 1 including the addition of a phenolic resin to said slurry, whereby said phenolic resin provides waterproofing, insect resistance, and inhibits the growth of fungus and molds.