Title:
WALLBOARD JOINT SYSTEM
Kind Code:
A1


Abstract:
The present invention relates to a drywall tape or joint tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer on one side and being non-coated on an opposite side for covering seams or for repairs generally in connection with fiber mat-faced gypsum wallboard, and more particularly pertains to a method for finishing joint seams and making other repairs in connection with a coated fiber mat-faced gypsum wallboard.



Inventors:
Francis, Hubert C. (Lithonia, GA, US)
Application Number:
12/013063
Publication Date:
07/16/2009
Filing Date:
01/11/2008
Assignee:
GEORGIA-PACIFIC GYPSUM LLC (Atlanta, GA, US)
Primary Class:
Other Classes:
52/309.1, 52/745.19
International Classes:
E04B2/02
View Patent Images:
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Primary Examiner:
ADAMOS, THEODORE V
Attorney, Agent or Firm:
Georgia-Pacific LLC (Atlanta, GA, US)
Claims:
I claim:

1. A drywall joint comprising a seam region formed by two adjacent coated fiber mat-faced gypsum wallboards; a drywall tape covering said seam region, said drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer thereon, said non-woven web of fibers forming an integral bond with joint compound in the seam region characterized by said fibers being embedded in dried joint compound.

2. The drywall joint of claim 1 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from monomers of alkyl halides of from 2-12 C atoms, alkene halides of from 2-12 C atoms, alkyl acrylamides of from 2-12 C atoms, alkene acrylamides of from 2-12 C atoms, alkyl acrylates of from 2-12 C atoms, and alkene acrylates of from 2-12 C atoms.

3. The drywall joint of claim 2 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from at least one monomer selected from styrene, dimethylstyrene, vinyltoluene, chloroprene, butadiene, ethylene, acrylamide, acrylonitrile, acrolein, methylacrylate, ethylacrylate, acrylic acid, methacrylic acid, methyl methacrylate, n-butyl acrylate, vinylidene chloride, vinyl ester, vinyl chloride, vinyl acetate, acrylated urethane, hydroxyethyl acrylate, dimethylaminoethyleneacrylate, and vinyl acrylate.

4. The drywall joint of claim 1 wherein said film-forming polymer is selected from the group consisting of styrene-butadiene-rubber, styrene-butadiene-styrene, ethylene-vinyl-chloride, poly-vinylidene-chloride, modified poly-vinyl-chloride, poly-vinyl-alcohol, ethylene-vinyl-actate, poly-vinyl-acetate, polymers and copolymers of acrylic acid, polymers and copolymers of methacrylic acid, polymers and copolymers of acrylic acid esters, polymers and copolymers of methacrylic acid esters, polymers and copolymers of acrylonitrile, acetate acrylic acid polymers, styrene/acrylate polymers and combinations thereof.

5. The drywall joint of claim 1, further comprising a feathering portion of said joint compound at edges of drywall tape.

6. A finished drywall seam region or repair region, comprising an unfinished seam region or repair region formed a coated, fiber mat-faced gypsum wallboard; a drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer on one side and being non-coated on an opposite side, wherein fibers on the non-coated opposite side are embedded in dried joint compound forming an integral bond between the drywall tape and joint compound in said seam region or repair region.

7. The finished drywall seam region or repair region of claim 6 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from monomers of alkyl halides of from 2-12 C atoms, alkene halides of from 2-12 C atoms, alkyl acrylamides of from 2-12 C atoms, alkene acrylamides of from 2-12 C atoms, alkyl acrylates of from 2-12 C atoms, and alkene acrylates of from 2-12 C atoms.

8. The finished drywall seam region or repair region of claim 7 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from at least one monomer selected from styrene, dimethylstyrene, vinyltoluene, chloroprene, butadiene, ethylene, acrylamide, acrylonitrile, acrolein, methylacrylate, ethylacrylate, acrylic acid, methacrylic acid, methyl methacrylate, n-butyl acrylate, vinylidene chloride, vinyl ester, vinyl chloride, vinyl acetate, acrylated urethane, hydroxyethyl acrylate, dimethylaminoethyleneacrylate, and vinyl acrylate.

9. The finished drywall seam region or repair region of claim 6 wherein said film-forming polymer is selected from the group consisting of styrene-butadiene-rubber, styrene-butadiene-styrene, ethylene-vinyl-chloride, poly-vinylidene-chloride, modified poly-vinyl-chloride, poly-vinyl-alcohol, ethylene-vinyl-actate, poly-vinyl-acetate, polymers and copolymers of acrylic acid, polymers and copolymers of methacrylic acid, polymers and copolymers of acrylic acid esters, polymers and copolymers of methacrylic acid esters, polymers and copolymers of acrylonitrile, acetate acrylic acid polymers, styrene/acrylate polymers and combinations thereof.

10. The finished drywall seam region or repair region of claim 6 further comprising a feathering portion of said joint compound at edges of the drywall tape.

11. A method of making a drywall joint in a seam region formed by two adjacent coated fiber mat-faced gypsum wallboards comprising applying a water-containing drying type joint compound or a setting-type joint compound to the seam region, applying a drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer on one side and being non-coated on an opposite side onto the joint compound to embed fibers on the non-coated opposite side in joint compound to form an integral bond between the drywall tape and dried joint compound in said seam region.

12. The method of claim 11, further comprising: applying a feathering portion of said joint compound at edges of the drywall tape.

13. The method of claim 11 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from monomers of alkyl halides of from 2-12 C atoms, alkene halides of from 2-12 C atoms, alkyl acrylamides of from 2-12 C atoms, alkene acrylamides of from 2-12 C atoms, alkyl acrylates of from 2-12 C atoms, and alkene acrylates of from 2-12 C atoms.

14. The method of claim 13 wherein said film-forming polymer is selected from the group consisting of at least one polymer derived from at least one monomer selected from styrene, dimethylstyrene, vinyltoluene, chloroprene, butadiene, ethylene, acrylamide, acrylonitrile, acrolein, methylacrylate, ethylacrylate, acrylic acid, methacrylic acid, methyl methacrylate, n-butyl acrylate, vinylidene chloride, vinyl ester, vinyl chloride, vinyl acetate, acrylated urethane, hydroxyethyl acrylate, dimethylaminoethyleneacrylate, and vinyl acrylate.

15. The method of claim 11 wherein said film-forming polymer is selected from the group consisting of styrene-butadiene-rubber, styrene-butadiene-styrene, ethylene-vinyl-chloride, poly-vinylidene-chloride, modified poly-vinyl-chloride, poly-vinyl-alcohol, ethylene-vinyl-actate, poly-vinyl-acetate, polymers and copolymers of acrylic acid, polymers and copolymers of methacrylic acid, polymers and copolymers of acrylic acid esters, polymers and copolymers of methacrylic acid esters, polymers and copolymers of acrylonitrile, acetate acrylic acid polymers, styrene/acrylate polymers and combinations thereof.

Description:

FIELD OF THE INVENTION

The present invention relates to a drywall tape or joint tape for covering seams or for repairs generally in connection with fiberglass faced gypsum wallboard constructions, and more particularly pertains to a method for finishing joint seams and making other repairs in connection with a coated fiberglass faced gypsum wallboard.

BACKGROUND OF THE INVENTION

Recently, a gypsum wallboard product has become commercially available that has the conventional multi-ply paper facer replaced with a coated, non-woven mat of glass fibers. Aspects of this wallboard construction are described in U.S. Patent Publications 2005/0266225 and 2006/0240236, the disclosures of which are incorporated herein by reference.

This new wallboard product is installed and finished in a very similar fashion to conventional paper-faced wallboard or drywall by affixing the boards to studs or joints and filling and coating the joints with a specially prepared adhesive called “joint compound” or “mud.”

The same procedure is used to repair surface defects, such as holes and dents, and to finish openings around electrical boxes, piping and duct work. Inside corners created by the intersection of wallboards are also finished in a similar fashion.

In conventional drywall finishing, that is in constructions using the conventional multi-ply paper-faced gypsum wallboard, a drywall tape or joint tape also is used to cover seams, defects and other openings. The tape generally adds strength and crack resistance and also assists in preparing a smooth surface for concealing butt joints and inside corners.

Conventionally, two types of drywall tape have been available.

A simple Kraft paper strip is one commonly used drywall tape. The Kraft paper tape is used by first applying an initial layer or “bedding coat” of the of joint compound or mud to the wallboard seam or defect, then adhering the Kraft paper strip to the wet joint compound and finally the assembly is finished by feathering additional joint compound on both edges of the paper strip with subsequent sanding to form a smooth surface.

The other type of drywall tape is a woven glass fiber tape, which usually has an adhesive backing so that it self-adheres to the conventional paper faced wallboard. In this way, the initial bedding step needed to finish joints, openings and other defects when using the paper tape can be eliminated. Conventional woven glass fiber tape is either configured with a fiberglass leno-weave mesh or is manufactured with a cross-fiber construction that purportedly resists stretching and wrinkles, such as supplied by United States Gypsum Company, Chicago, Ill. Both of these prior art weaves have a very open mesh-like construction as illustrated in FIG. 1.

To date the newly commercialized fiberglass faced gypsum wallboard product has been finished using the generally less expensive paper joint tape since the adhesive back of the woven glass fiber tape does not adhere well to the fiberglass facer material. Thus, it has not been considered advisable to dispense with the initial bedding layer for the joint or other defect during the finishing operation, which eliminates one of the main advantages recommending the use of the generally higher priced fiberglass drywall tape.

A joint treatment system which includes reinforcing tape and joint compound, must provide joints as strong as the gypsum board itself. Otherwise, normal structural movement in the wall or ceiling assembly can result in the development of cracks over the finished joint.

One of the main advantages of the previously identified non-woven fiberglass faced wallboard product is its resistance to supporting mold and mildew growth. When paper tape is used for finishing the joints and other openings with this fiberglass-faced product, however, that advantage is potentially compromised, as the paper at the seams, inside corners and other locations can potentially provide a suitable surface for supporting mold and mildew growth.

Applicant has thus developed an improved method for finishing the joint seams, inside corners and other openings in wall constructions using the new coated non-woven fiberglass mat faced gypsum wallboard products, which method also resists mold and mildew growth.

In particular, the present invention provides a drywall tape or joint tape for covering seams, or for repairs generally in connection with coated non-woven fiberglass faced gypsum wallboard constructions, and a related method for finishing such joint seams and making other repairs, that comprises a coated, non-woven fiberglass mat similar in composition and construction to the coated glass mat facer used in the previously identified fiberglass faced gypsum wallboard products.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are used to illustrate the invention and highlight its novel features.

FIG. 1 is a photograph of a cross-fiber construction of the fiberglass joint tape of the prior art and especially IMPERIAL® Type P Tape manufactured for the United States Gypsum Company.

FIG. 2: is a photograph of the un-coated, non-woven fiberglass base sheet used to manufacture the joint tape of the present invention.

FIG. 3 is a photograph of the coated, non-woven fiberglass mat or web used as the drywall tape or joint tape of the present invention

FIG. 4: is a is a schematic representation of a finished seam prepared using the coated, non-woven fiberglass joint tape of the present invention in connection with a coated, nonwoven fiberglass mat-faced gypsum wallboard construction.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, an improved system and method for finishing seams and other openings in a wall construction which uses a coated non-woven fiberglass mat-faced gypsum wallboard is provided.

The system and method comprises applying a layer of joint compound to the seam, inside corner or other defect in a coated, non-woven fiberglass mat-faced gypsum wallboard assembly and then affixing thereto a coated, non-woven glass fiber mat-based joint tape or drywall tape. The coated, non-woven glass fiber mat drywall tape or joint tape is applied to wet joint compound in the seam, inside corner or other defect in a coated, fiberglass-faced gypsum wallboard assembly using the non-coated side of the drywall tape.

The coating on what ultimately becomes the free surface of the coated non-woven glass fiber mat joint tape or drywall tape in the finished seam or repair region comprises a cured (e.g., dried), highly filled film-forming, e.g., latex, binder similar in composition to the coating that is resident on the surface of the coated non-woven fiberglass mat-faced gypsum wallboard itself. The other surface of the glass fiber tape, i.e., the back surface which is affixed to the initial layer or “bedding coat” of the joint compound or mud consists essentially of the raw fibers of the non-woven mat.

The present invention thus provides a drywall tape, a drywall joint finished with the drywall tape, and a method of preparing finished drywall joints and other opening for a gypsum wallboard construction employing coated, non-woven fiberglass mat-faced gypsum wallboard.

Thus, in one embodiment, the present invention relates to a drywall joint comprising a seam region formed by two adjacent coated glass fiber mat-faced gypsum wallboards; a drywall tape covering said seam region, said drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer thereon, said non-woven web of fibers forming an integral bond with joint compound in the seam region characterized by said fibers being embedded in dried joint compound.

In another embodiment, the present invention comprises a finished drywall seam region or repair region, comprising an unfinished seam region or repair region formed by a coated, non-woven fiberglass mat-faced gypsum wallboard; a drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer on one side and being non-coated on an opposite side, wherein fibers on the non-coated opposite side are embedded in dried joint compound thus forming an integral bond between the drywall tape and joint compound in said seam region or repair region.

In still another embodiment, the present invention comprises a method of making a drywall joint in a seam region formed by two adjacent coated fiberglass mat-faced gypsum wallboards comprising applying a water-containing drying type joint compound or a setting type to the seam region, applying a drywall tape comprising a non-woven web of fibers having a coating of a filled, film-forming polymer on one side and being non-coated on an opposite side onto the joint compound to embed fibers on the non-coated opposite side in the joint compound to form an integral bond between the drywall tape and dried (cured) joint compound in said seam region.

With regard to the FIG. 1, a conventional fiberglass joint tape or drywall tape construction is shown. This material is representative of IMPERIAL® Brand Tape—Type P, commercially available from the United States Gypsum Company. As shown, such prior art drywall tapes have a very open mesh structure (about 100 openings per square inch), with openings clearly visible to the natural eye. Visually, both sides of the joint tape appear essentially identical. The side designed to be applied to the wallboard seams and to other wallboard defects generally has a layer of a pressure sensitive adhesive applied to it. It also is possible that the opposite side of the glass fibers, i.e., the side that faces away from the wallboard surface, may also be provided with a coating of a resin or polymer. Notably, any such coating does not alter the open nature of the mesh weave.

FIG. 1 should be contrasted with FIGS. 2 and 3 which illustrates the construction of the joint tape for use in connection with the present invention.

As shown in FIG. 2, the substrate or base material for the joint tape or drywall tape for use in connection with the present invention comprises a web or base of non-woven fibers held together by an adhesive binder. The fibrous nature of the base non-woven fiberglass web or mat is clearly viewed in FIG. 2. Preferably high strength fibers are used to form the non-woven web. The fibers can be a mineral-type material such as glass fibers, carbon fibers, graphite fibers and/or synthetic resin fibers, such as polyester fibers. Also, combinations of these fibers can be used. Glass fibers are preferred. Fibers having a diameter of about 8 to 16 microns are typical, with diameters between 10 and 12 microns more usual. Nonwoven mats are generally made from chopped strands of fibers of a length predominately between about ¼ and 1 inch, though continuous fiber strands can be used satisfactorily. For the most part, non-woven webs are less costly than woven materials.

Typically, but not exclusively, the non-woven fiber webs used as the base substrate of the coated joint tape or drywall tape of the present invention are made by a wet-forming process using chopped strands of fibers and formed as a continuous non-woven web of any workable width on a Fourdrinier-type machine. Webs having widths of up to 240 inches or more are possible and the webs are collected in roll form for storage and handling, e.g., transportation. Drywall tape having a width of about 2¼ inches then can be cut from such larger width webs.

Non-woven fiberglass webs or mats suitable for use in the present invention can be prepared by a wet-laid process, which is carried out on what can be viewed as modified papermaking machinery. Indeed, the resulting web or mat has a visual appearance similar in many respects to paper. Descriptions of the wet-laid process for making fiber webs or mats, generally using glass fibers, may be found in a number of U.S. patents, including U.S. Pat. Nos. 2,906,660, 3,012,929, 3,050,427, 3,103,461, 3,228,825, 3,760,458, 3,766,003, 3,838,995, 3,905,067, 4,112,174, 4,681,802 and 4,810,576, all of which are incorporated herein by reference. Machines such as wire cylinders, Fourdrinier machines, Stevens Former, Roto Former, Inver Former and Venti Former machines and the like can be used to form the non-woven fiber web or mat.

In one of the common wet-forming processes, a very dilute aqueous stock of the fiber material is applied over several linear feet of an upwardly inclined wire screen, followed by several linear feet of high vacuum water removal through the screen, whereby the fibers in the slurry enmesh themselves into a freshly prepared wet fiber web or mat. This is often followed by a “curtain coater,” where a fiber binder such as a urea-formaldehyde resin binder, or in preferred practice for the present invention, an acrylic-type binder, is applied to the wet-formed web or mat of entangled fibers. Thereafter, the binder impregnated non-woven web or mat is passed through an oven that removes excess water and cures (or dries) the binder adhesive to form a coherent web or mat structure. Generally, the binder comprises about 20 to 30% by weight of the web or mat. With this process, fibrous webs or mats comprising chopped, non-woven, filaments, particularly glass fibers, oriented in a random pattern and bound together with the resin binder are formed. This structure is evident in FIG. 2.

The individual strands of such webs or mats thus are bonded together to form a unitary structure by the adhesive binder. The web or mat can range in thickness, for example, from about 10 mils (10 thousandths of an inch) to about 45 mils, with a web or mat thickness of about 15 mils to about 40 mils generally being suitable for the present invention.

The aforementioned fibrous webs or mats are known and are commercially available in many forms, for example, such as those which have been sold under the trademark DURA-GLASS by Manville Building Materials Corporation and those which have been sold by Elk Corporation as BUR or shingle mat. Webs or mats of this type also are available from Owens-Corning.

Uncoated, non-woven fiber mats suitable for making the coated joint tape or drywall tape of the present invention usually have a basis weight between about 8 and 30 lbs. per thousand square feet of mat surface area, more usually between about 12 and 27 lbs. per thousand square feet and preferably between about 16 and 22 lbs. per thousand square feet.

As clearly evident in a visual comparison of FIG. 2 with FIG. 1, non-woven, fiber webs or mats made in this way do not have the open mesh structure of the nature shown in FIG. 1. In fact, when viewed by the un-aided eye, such webs or mats have the visual appearance of paper and do not appear to have an open structure at all. However, on a microscopic level, such webs or mats do have an open pore structure with a high percentage of fiber-fiber interstitial space and it is possible to force air through the pores of the web or mat.

To prepare the joint tape or drywall tape used in connection with the present invention it is necessary to apply a coating onto one surface of the fiber web or base. The coated mat useful as the drywall tape of the present invention is shown in FIG. 3. A coating is applied to the fiber web or mat using an aqueous coating formulation. The aqueous formulation is applied in a way so that the coating formulation coats the surface fibers of the web and also substantially uniformly penetrates into the open-pore structure of the fiber web without passing completely though the thickness of the web or mat. In this way, the fibers are substantially completely occluded by the coating on one side of the mat or web (the coated side); while the random, overlapping and somewhat open fiber structure is preserved on the side of the mat opposite to the side on which the coating is applied (the non-coated side). In other words, the coated side of the web or mat has the appearance of FIG. 3, while the non-coated side of the coated mat or web retains a visual appearance much like that shown in FIG. 2.

In accordance with the present invention, the aqueous coating is applied such that it penetrates into and envelopes the fibers of the glass fiber web or mat preferably to a depth of from about 30 percent to about 50 percent of the thickness of the fiber web or mat. An amount of coating is applied so that substantially all of the fibers on the coated side of the web or mat are embedded or occluded in the coating. With this preferred degree of coating penetration, the un-coated web or mat portion comprises about 50 percent to about 70 percent of the total web or mat thickness. This uncoated portion is available for penetration by the joint compound when a seam, corner, or other defect is finished in accordance with the present invention.

The applied coating has a morphology characterized by a highly-filled film which covers one surface of the web and which to a certain extent bridges individual fibers in the web or mat. Importantly, the coating is accompanied by a distribution of micropores (not shown) that extend through the film coating. The distribution of micropores in the coating is sufficient to allow air-flow there through when the drywall tape is pressed into the bedded layer of joint compound, thus allowing the joint compound to fill (or facilitating the joint compound's flow into) the fiber-fiber interstices of the non-coated side of the joint or drywall tape. The micropores also allow the joint compound to dry (or facilitate the drying of the joint compound) by allowing moisture in the joint compound to evaporate in its vaporous state through the drywall tape.

The aqueous coating composition, which is applied to one, free surface of the above-described wet laid, non-woven fiber web or mat (see FIG. 2) for making the coated joint tape or coated drywall tape used in the present invention, comprises an aqueous combination of predominately three components (1) a mineral pigment or filler material; (2) an organic adhesive binder, preferably a film-forming polymer and usually a film-forming latex adhesive; and, optionally (3) an inorganic second binder or an inorganic second adhesive.

On a dry weight basis of the two required components (100%), the organic adhesive binder or film-forming polymer comprises at least about 1% and usually no more than about 30% by weight of the total coating, with the balance being the inorganic, mineral pigment or filler. Usually, the organic adhesive binder or film-forming polymer comprises between about 5 and 20% by weight of the coating, on a dry weight basis. The optional inorganic second binder comprises no more than about 20% by weight of the dried (cured) coating. Usually, the weight ratio of the mineral pigment or filler to the dry solids of the film-forming polymer (organic adhesive) binder can be in excess of 15:1 and in some cases can be in excess of 20:1, but usually is at least about 5:1.

Suitable coating compositions for making the coated joint or drywall tape useful in the present invention thus may contain, on a dry weight basis of the three noted components (100%), about 70 to 99 percent mineral pigment or filler, more usually about 80 to 95 percent mineral pigment or filler, about 0 to 20 percent inorganic second adhesive, more usually about 0 to 10 percent and about 1 to 30 percent organic adhesive binder (film-forming polymer), more usually about 5 to 20 percent.

As noted, a mineral pigment or filler comprises the major component of the coating composition. Examples of mineral pigments suitable for making the coated joint tape useful in the present invention include, but are not limited to, ground limestone (calcium carbonate), clay, sand, mica, talc, gypsum (calcium sulfate dihydrate), aluminum trihydrate (ATH), antimony oxide, or a combination of any two or more of these substances.

For making the aqueous coating formulation, the mineral pigment is provided in a particulate form, preferably as a fine powder. To be an effective mineral pigment or filler for making coated joint or drywall tape for use in this invention, the pigment preferably has a particle size such that at least about 95% by weight of the pigment particles pass through a 100 mesh wire screen, with about 75% of the particles (by number) being greater than about 5 μm. Preferably, the pigment or filler has most of, if not all of, the very fine particles removed, especially particles less than 1 μm (i.e., particles that pass through a screen having an opening of 1 μm). The presence of an excessive amount of very fine particles in the coating composition negatively impacts the porosity (microporosity or micropore structure) of the coated drywall tape. One preferred mineral pigment is a limestone having a number average particle size of about 40 μm.

The other required constituent of the coating composition is the organic adhesive binder or film-forming polymer. The organic adhesive binder can be anyone of a variety of film-forming materials, generally supplied as a latex emulsion, which can be formulated in an aqueous coating composition. For example, the film-forming polymer can be selected, for example, from at least one polymer derived from monomers of alkyl halides of from 2-12 C atoms, alkene halides of from 2-12 C atoms, alkyl acrylamides of from 2-12 C atoms, alkene acrylamides of from 2-12 C atoms, alkyl acrylates of from 2-12 C atoms, and alkene acrylates of from 2-12 C atoms. Some preferred polymers include those derived from at least one monomer selected from styrene, dimethylstyrene, vinyltoluene, chloroprene, butadiene, ethylene, acrylamide, acrylonitrile, acrolein, methylacrylate, ethylacrylate, acrylic acid, methacrylic acid, methyl methacrylate, n-butyl acrylate, vinylidene chloride, vinyl ester, vinyl chloride, vinyl acetate, acrylated urethane, hydroxyethyl acrylate, dimethylaminoethyleneacrylate, and vinyl acrylate. For example, the film-forming polymer can be a latex selected from at least one polymer derived from at least one monomer comprising repeating units derived from an alkyl halide having at least one double bond, such as a vinyl halide, e.g., vinyl chloride, and an alkene, such as ethylene, wherein the alkyl halide has from 2 to 12 C atoms, and wherein the alkene has from 2 to 12 C atoms. The alkyl halide can be a vinyl halide, for example.

A large number of suitable film-forming materials useful as the organic adhesive binder, in addition to those identified above, will be apparent to skilled workers and can include, as a representative and non-limiting list, such materials as styrene-butadiene-rubber (SBR), styrene-butadiene-styrene (SBS), ethylene-vinyl-chloride (EVCl), poly-vinylidene-chloride (PVdC), modified poly-vinyl-chloride (PVC), poly-vinyl-alcohol (PVOH), ethylene-vinyl-actate (EVA), and poly-vinyl-acetate (PVA).

The binder may also be a hydrophobic, film-forming, UV resistant, polymer or copolymer containing units of acrylic acid and/or methacrylic acid (together usually referred to as (meth)acrylic acids)), of their esters (usually referred to together as ((meth)acrylates) or of acrylonitrile, including acetate acrylic and styrene/acrylate polymer materials. The formulation for making the coated joint tape of the present invention should not be limited to any particular film-forming polymer.

As noted, an optional component of the coating composition is an inorganic adhesive binder. Examples of inorganic adhesive binders which can be used in combination with the film-forming polymer (organic adhesive binder(s)) in the coating composition include, but are not limited to the following: calcium oxide, calcium silicate, calcium sulfate (anhydrous or hemi-hydrate), magnesium oxychloride, magnesium oxysulfate, and other complex inorganic binders of some Group IIA elements (alkaline earth metals), as well as aluminum hydroxide.

Inorganic pigments or filler materials will often inherently contain some naturally occurring inorganic adhesive binder. Examples of such fillers, some listed with the naturally occurring binder, include (but are not limited to) the following: limestone containing quicklime (CaO), clay containing calcium silicate, sand containing calcium silicate, aluminum trihydrate containing aluminum hydroxide, cementitious fly ash and magnesium oxide containing either the sulfate or chloride of magnesium, or both.

Obviously, to form the aqueous coating formulation, the required binder and filler are mixed with water. Water is provided in an amount sufficient to provide suitable rheological properties (e.g., viscosity) to the aqueous coating composition. Other adjuvants, such as thickeners or rheological control agents for adjusting the viscosity of the coating composition can also be added. A suitable rheological property is one which, given the chosen form of application of the aqueous coating composition to the fiber mat or web, provides for the retention of a suitable portion of the coating formulation on the surface of the fibers of the fiber mat and within the interstices of the fiber mat or web preferably to a depth between 30 and 50 percent of the thickness of the fiber mat or web from a free surface of the mat (to which the coating formulation is applied) and also results in the formation of the desired coating morphology (microporosity) through the thickness of the coating. The aqueous coating composition may also include other optional ingredients such as colorants (e.g., pigments and dyes), defoamers, dispersants and preservatives. When used, the aggregate amount such other ingredients in the coating composition is typically in the range of about 0.1 to 5% and generally is not more than about 2% of the dry weight of the coating formulation. Generally, a suitable aqueous coating formulation will have a viscosity between about 8,000 and 18,000 cps. The preparation of a suitable formulation with such ingredients to achieve such results is well within the skill of the art.

Any suitable method for applying an aqueous coating composition to a fiber mat or web substrate can be used for making the coated joint or dry wall tape of the present invention and can include such techniques as roller coating, curtain coating, knife coating, brush coating, spray coating and the like, including combinations thereof.

Following application of the aqueous coating composition to the web or mat, the applied coating composition is dried (cured), typically in a drying oven, to form the coated joint or drywall tape. The coated web or mat is dried at a temperature and for a time sufficient to remove water from the coating composition, to coalesce the organic film-forming polymer adhesive on the web and to form an adherent coating, without degrading the coating or the web. Suitable temperatures and times will be influenced greatly by the equipment being used and the specific nature of the coating formulation itself and can be selected by those skilled in the art using routine experimentation.

The coated joint or drywall tape for use in the present invention will typically have a mass of applied coating amounting, on a dry weight basis, to at least about 20 pounds per 1000 square feet, more usually between about 30 and 50 lbs., per 1000 sq. ft. of mat depending upon the thickness of the glass fiber mat. Thus, the basis weight of the coated joint or drywall tape itself will generally be at least about 30 pounds per 1000 sq. ft. and usually will be between about 40 and 60 pounds per 1000 sq. ft.

With reference to FIG. 4, the use of the coated joint or drywall tape in accordance with the present invention will now be described. As illustrated in connection with FIG. 4, a method is provided for preparing a drywall joint in wall constructions featuring coated fiberglass-faced gypsum wallboards.

A particular advantage of this construction is that both the wallboard and the joint tape are resistant to mold and mildew growth, a property not shared by paper-based joint tape. A further feature of this invention is that by using similar materials of construction for both the wallboard facing and for the joint or drywall tape, the wallboard joints (including corners and other repaired defects) are less affected (and may be substantially unaffected) by changing environmental factors, including changing temperatures and humidity levels. In contrast, when the joints, corners and other defects in coated non-woven fiberglass mat-faced gypsum wallboards are treated in the conventional manner using paper joint tape, changing environmental factors place stresses on the interface between the paper and the coated fiberglass possibly leading to the development of unsightly cracks or other defects.

Thus, one aspect of the present invention comprises a method for preparing a drywall joint in wall constructions featuring coated fiberglass mat-faced gypsum wallboards in which a pair of coated, fiberglass mat-faced gypsum wallboards are disposed in an adjoining relationship to one another to form a seam region. A layer of joint compound or mud, either a drying-type or a setting type joint compound, is applied to the seam region and then the coated, non-woven fiber joint tape of the present invention is disposed over the seam by pressing the non-coated side of the joint tape into the wet “mud.” As noted earlier, the tape has sufficient microscopic porosity to facilitate entry of the joint compound or mud into the interstitial spaces of the non-woven fiber mat tape. This incorporation of the joint compound into the tape ensures a strong bond between the joint compound and the joint tape.

Once the first layer of joint compound dries, one or more additional layers of joint compound (mud) can be applied usually over the outer edges of the tape and, once dried (cured), can be sanded (referred to as feathering) to provide a smooth finish.

As shown in FIG. 4, a flat drywall joint can be constructed by butt joining a pair of coated, fiberglass mat-faced wallboards 18 and 17 each having a coated, fiberglass facing 12, to form a seam region 45. The wallboards preferably are constructed in accordance with U.S. Patent Publications 2005/0266225 and 2006/0240236, the disclosures of which are incorporated herein by reference. Each wallboard 17 and 18 has a gypsum core 20 with a non-woven fiberglass mat facing 13 integrally bonded to the core. The non-woven mat has an adhered coating 14 on its outer surface. A first layer of drying-type or setting-type joint compound or mud 19 is applied over and into the seam region 45. While the joint compound is still wet, the joint tape 100 of the present invention is applied, with pressure, over the joint compound so that the joint compound or mud flows into the interstitial spaces of the non-woven glass fiber tape 101. The joint tape 100 comprises a web of non-woven fiber 102 with a coating 103 of a filed, film-forming polymer. Care must be taken to provide the proper amount of joint compound under the tape to prevent blistering of the tape. If necessary, any excess joint compound can be removed from the edges 104 and 105.

After the first layer of joint compound 19 has dried, a second layer of joint compound 22 is applied along the edges of the tape. If necessary, additional water can be included in the joint compound so as to thin it for easier application.

Similar approaches can be provided for finishing inside corners, outside corners, horizontal flat joints, for repairing holes and crack, and for finishing seams along electrical boxes and switches and seams around piping and duct work.

After the second coat 22 is allowed to dry, preferably overnight, a third layer (not shown) of drying-type joint compound can be applied over the second coat 22, ideally with an 8 inch knife, feathering slightly beyond the second coat. If further coats are desired, though generally unnecessary, the third coat is allowed to dry, and a fourth or finishing coat (also not shown) can be applied with a 10 inch knife to the flat joints. The third coat or fourth coat can be lightly sanded if necessary.

Joint compounds conventionally used in finishing drywall joints and other defects can be classified as either a “drying” type (e.g., see U.S. Pat. No. 3,998,769) or a “setting” type (e.g., see U.S. Pat. No. 5,653,797). In a drying-type joint compound, the filler comprises substantially calcium carbonate. Prior to use, the filler and the binder, along with several other known ingredients, are mixed with water. After application, when the water dries by evaporation, a dry, relatively hard cementitious material is left behind. Pre-mixed drying type products also are commercially available (known as ready mixed materials). Joint compounds or compositions known as the “setting” type include at least a substantial portion of calcium sulfate hemihydrate (Plaster of Paris) in the mixture. During use of a setting-type joint compound, the calcium sulfate hemihydrate is rehydrated to the dihydrate state. This rehydration process normally takes place over a fairly short period of time. Setting-type joint compounds are believed to form a crystalline network upon setting. The present invention can employ both the drying type and setting type joint compounds, though for ease of application and use the drying type is usually used in preference to the setting type.

From the foregoing it can be realized that this invention provides drywall joints and methods of joint fabrication in a wall construction employing coated fiberglass-faced wallboards, which drywall joints are expected to exhibit superior properties of mold and mildew resistance and better integrity over Kraft paper tape joints and over other glass tape joints employing rubber based or binder coatings.

The present invention has been described with reference to specific embodiments for the purpose of describing, but not limiting the invention. Various modifications, which will become apparent to one skilled in the art, and the invention is intended to cover those changes and substitutions that may be made by those skilled in the art without departing from the spirit and the scope of the invention. Unless otherwise specifically indicated, all percentages are by weight. Throughout the specification and in the claims the term “about” is intended to encompass + or −5% and preferably is only about + or −2%.