Adhesive Expanded Metal Lath

Abstract

Expanded metal lath products, or non-metal facsimile products, are disclosed with moisture resistant pressure sensitive adhesive covered by release sheets, and the use of such products in drywall seaming and their manufacture.

Description

FIELD OF THE INVENTION

The present invention relates generally to the manufacture and use of expanded metal lath products, or non-metal facsimile products, with pressure sensitive adhesive.

BACKGROUND OF THE INVENTION

Expanded metal lath products have been utilized in construction trades for approximately one hundred years. These expanded metal lath products come in a wide variety of configurations. Large and heavy expanded metal lath products may be utilized as decorative or structural elements in buildings, moderate weight expanded metal lath products are used in connection with stucco and concrete, and light weight expanded metal lath products can be utilized in interior construction.

While the expanded metal lath products utilized in connection with stucco or concrete must generally be furred or spaced apart from the adjacent wall, finer gauge expanded metal lath products may be mounted flush with drywall or other surfaces. Generally to attach expanded metal lath product for stucco or concrete, the lath product is nailed at furring points that are bent outward from the plane of the expanded metal lattice. Similarly, at present most interior expanded metal lath product is positioned in place by the use of the staples or tacks and then covered in place by drywall mud or the like. Due to the requirement of tacking expanded metal lath product in place, installation frequently becomes a two person job, and may require an otherwise unnecessary tool such as a stapler.

In interior construction, a variety of materials are utilized in finishing drywall systems. Traditionally, paper tape has been used at seams and applied in a two-step process. The first step is coating the seam with standard pre-mix drywall mud and embedding the tape in the mud. The second step is applying a top coat of drywall mud over the tape. Then after drying, as with most uses of drywall mud, the dried surface will be sanded smooth. Paper tape is relatively inexpensive and is strong so that is used in many situations. However, the paper tape is not self-adhesive and the application of an adhesive layer would prevent the drywall mud from bonding to the interior surface of the paper.

In addition to paper, there is a fiberglass mesh tape that in some instances comes with a self-adhesive coating. Fiberglass mesh tape is generally not as strong as paper tape and is not considered to be useful at corners because the fiberglass product does not fold well. Fiberglass mesh tape is typically used with a setting compound rather than standard pre-mix drywall mud. Setting compound hardens quickly, generally shrinks less, and forms a harder dried material than a standard pre-mix. The use of fiberglass mesh tape is generally not recommended for situations where there may be structural movement, so that in a repair situation it is not well suited for application on anything other than a small hole.

In addition, there are molded pieces that may provide plastic corner beads or transitions, and metal tape that can be folded to provide a straight sharp corner on a variety of angular positions. The typical corner bead and metal tape pieces, as well as other finishing pieces that may be utilized, are attached by staples or nails. Metal tape may be applied, similar to paper tape, by first placing the drywall mud on the corner and pressing the metal strip side into that compound. The corner is then finished with additional coats of drywall compound. In the event that a setting drywall compound does not sand to a nice finish, a softer topping compound can be applied and sanded to a smooth surface.

It would be desirable if a self-adhesive expanded metal lath or similar lattice product was available to avoid the necessity of tacking or stapling the lath in position. Accordingly, it is desirable to provide improved and self-adhering expanded metal lath or other lattice products of metal, or other suitable material for use in interior building applications. Such self-adhesive expanded metal lath products may also be utilized in the temporary positioning of HVAC type work and other fluid piping, or on auto body panels as a support for fillers and molding compounds. The self-adhesive nature of the expanded metal lath makes it suitable for use on such metal substrates in addition to wall board, as it is not necessary to staple or screw the lath to ductwork or body panels. Alternative lattice materials may include plastic or open weave non-wovens that may be treated with pressure sensitive adhesive and used in appropriate circumstances.

Accordingly, aspects of the invention provide for improved techniques for the manufacture of self-adhering expanded metal lath product and lattice products of other material, the use of such self-adhering products, and the products themselves.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described in detail below with reference to the following drawing figures in which the use of like numerals in different figures is intended to illustrate like components.

FIG. 1A is a top plan view of an exemplary expanded metal lath piece with strips of pressure-sensitive adhesive;

FIG. 1B is a side plan view of the expandable metal lath of FIG. 1A.

FIG. 2 is a schematic manufacturing diagram for expanded metal lath products according to the invention;

FIG. 3 is a perspective view of an exemplary expanded metal lath corner piece.

DETAILED DESCRIPTION

Turning then to FIG. 1A, a self-adhesive expanded metal lath 10 is illustrated. The principal components are the expanded metal lath grid material 11 forming the borders of the nearly diamond shaped grid openings 12, and the strips of pressure sensitive adhesive 14. A side elevation view in FIG. 1B, taken along line B of FIG. 1A, illustrates the bottom release sheet 18, the lattice material 11, the adhesive layer 14 and the top release sheet 16.

A typical adhesive would be 2413 adhesive from DHM Adhesives of Calhoun, Ga., a moisture friendly or water-cured pressure sensitive adhesive, or the like. It is desirable that the pressure sensitive adhesive have a tack strength of at least about 5, and preferably 6 or more, pounds per linear inch. The adhesive is applied in a thin layer. Typically, when applied in stripes as illustrated in FIG. 1A, the adhesive will be applied at a rate of only about 1.06 grams per square foot, and if applied as a complete sheet across all of the lattice work, the weight could be no more than about 2 grams of adhesive per square foot. When applying adhesive over the entire lattice, the adhesive should to be so thin so that it will not obstruct the openings 12 in the lattice, either by remaining on the release sheet or by beading around the lattice elements. Many of these openings should remain unobstructed to provide a connection through the lattice. In addition, for products 10 that are intended for use in the drywall setting, it is important that the adhesive be selected to maintain a bond in the presence of water as a pressure sensitive adhesive subject to hydrolysis could fail too quickly before the drywall mud is set. It is because the drywall mud can penetrate through the openings 12 that it is unnecessary to put down a layer of drywall mud before placing the lath product 10. Adhesives may be selected not only for adhesion to drywall, but also to non-porous materials such as metal ductwork or pipes, plastics, fiberglass, and automobile panels. It is not necessary that the adhesive be impervious to hydrolysis, only resistant to bond failure due to hydrolysis for a relatively short term of between about one and 24 hours to allow drywall mud to adequately set.

While structural expanded metal lath in heavy and moderate gauge applications generally requires the use of metal, interior products may substitute lightweight alternatives to metal. For instance, a molded plastic lattice, or a metal or plastic lattice created from intersecting welded or twisted wires may be utilized in appropriate settings, always taking care to select size for openings 12 relative to the thickness of the lattice materials 11 for the desired application. Generally the pick count of the lattice will be between about two and 15, often the resulting openings will not be square, but will be longer in one direction than another. The wire gauge of the lattice forming material will typically be between about 17 and 32.

A schematic for the automated manufacture of exemplary adhesive expanded metal lath is illustrated in FIG. 2. At the starting point, the top release sheet 16 is dispensed from the spool 26 and proceeds over back roller 28 where it passes by a glue applicator 30. The illustrated applicator has glue-head 30 to apply adhesive and a doctor blade 32 to spread the adhesive. Alternatively, the glue-head can apply only thin lines of adhesive, and no doctor blade may be necessary. Then the adhesive treated release sheet 16 is married to the expanded metal lath scrim 11 that is dispensed from roller 38 and the back release tape 18 that is simultaneously dispensed from roller 40. The marrying of release sheets and lath at point 35 is facilitated by pressure from squeeze rollers 34, 36. The squeeze rollers apply some pressure to the release tapes 16, 18 that are sandwiching the lath scrim 11. In this fashion the adhesive remains between the two release tapes 16, 18 and does not foul the rollers 34, 36. The composite adhesive scrim material and release tapes 42 then proceeds to a finish point, where it is typically rolled although it can be cut or shaped as desired. In addition to rolled lath, typical shapes include flat or folded strips about three to six inches wide and about one to eight feet in length. Rectangular shapes ranging in size from about one foot square to about four feet by six feet are also useful. The scrim can be cut to the size needed for a particular application before use.

It will be understood that the scrim 11 can be expanded metal lath material or can be plastic or wire material as desired for particular applications. In addition, the adhesive may be dyed so that it is more easily identified and the adhesive side of the expanded metal lath piece 10 made more readily ascertainable. Alternatively, a colored release sheet or release tape can be utilized on one side of the piece 10 to facilitate the identification of the adhesive side.

As shown in FIG. 3, the lattice material 11, when made of metal, is easily formed as a folded shape suitable for use as a corner piece 20 with the corner 21 that is sufficiently flexible to be adjusted to cover a range of interior angles, and not merely the standard 90 degree angle that is most common. The bottom release sheet 18 is visible on the exterior of the corner piece 20 and the openings 12 in the lattice material 11 are also visible. Usually a corner piece 20 made of expanded metal lath will be utilized on exterior angles so that the adhesive will be on the interior surface of the folded lattice 11. If the corner piece 20 were intended for use at an interior corner, such as where a ceiling meets a vertical wall, the adhesive would need to be applied on the exterior of the angle and the top release sheet 16 would be visible in the view of FIG. 3.

When a self-adhesive lattice lath is applied to drywall, it is easily supported in a vertical orientation by the adhesive as a square yard of lath for interior use will rarely weight more than 2.5 pounds per square yard and more often only a fraction of that amount. When positioned horizontally along a ceiling seam, the usual adhesives still supply an abundance of grip strength to support the lath. When drywall mud is applied to the lath, it penetrates through the openings 12 to the drywall and encapsulates the lattice material. Thus the laths 10, 20 end up being held in place by the pressure sensitive adhesive and the drywall mud's adhesion to the drywall and no delamination is likely even if the adhesive should fail after a few years. Ideally the adhesive may even be a pressure sensitive adhesive that cures in the presence of moisture from the drywall mud so that no adhesive failure will be likely over time.

Numerous alterations of the structure and techniques herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to the preferred embodiment of the invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Claims

1. A lattice lath having first and opposite sides with a pressure sensitive adhesive applied in a plurality of stripes on the first side and a release sheet over the pressure sensitive adhesive.

2. The lattice lath of claim 1 further comprising a release sheet over the opposite side.

3. The lattice lath of claim 1 wherein the lattice lath is expanded metal lath.

4. The lattice lath of claim 1 wherein the lattice lath is substantially planar.

5. The lattice lath of claim 1 wherein the lattice lath has two planar portions joined at a flexible corner.

6. The lattice lath of claim 1 wherein the pressure sensitive adhesive has a tack strength of at least 5.

7. The lattice lath of claim 6 wherein the weight of pressure sensitive adhesive applied to the lath is between one and two grams per square foot.

8. The lattice lath of claim 1 wherein the pick count of the lattice grid is between 2 and 15 picks per inch.

9. The lattice lath of claim 3 wherein wire gauge of the metal lattice forming material is between 17 and 32.

10. The lattice lath of claim 6 wherein the pressure sensitive adhesive is resistant to short-term hydrolysis failure.

11. A method of seaming a drywall surface having a seam therein comprising removing the release sheet from the pressure sensitive adhesive of the lattice lath of claim 1, applying said lattice lath over at least a portion of the drywall seam so that the pressure sensitive adhesive holds the lattice lath in position, and applying drywall mud over the lattice lath.

12. The method of claim 12 wherein the lattice lath has a pick count between 2 and 15 picks per inch and the drywall mud penetrates through the openings between picks to the drywall surface.

13. A method of manufacturing the lattice lath of claim 1 by passing a lath scrim beneath a glue head, dispensing pressure sensitive adhesive from the glue head onto the lath scrim, marrying a release sheet to the adhesive on the lath scrim, and cutting the lath scrim to lengths between one and eight feet.

14. The method of claim 13 wherein the pressure sensitive adhesive is applied to the lath scrim at a rate between one and two grams per square foot.