Wallboard joint tape with fluorescent compound

Abstract

An identifiable wallboard joint tape is provided and includes a web of tape incorporated with an identifier such that the tape is visible under UV light and visually distinguishable from the surrounding wallboard joint and joint compound.

Claims

1. An identifiable wallboard joint, comprising: two wallboard panels having a wallboard joint therebetween; an identifiable wallboard joint tape applied to the wallboard joint, wherein the identifiable wallboard joint tape comprises a web of liquid permeable paper wallboard joint tape integrally incorporated with an optical brightener, which is formed by applying an aqueous solution having the optical brightener in the range of 0.001 to 0.01 weight percent to the web of wallboard joint tape; and a layer of joint compound covering the identifiable wallboard joint tape, wherein under standard lighting conditions, said optical brightener is invisible and wherein said identifiable wallboard joint tape is visible and visually distinguishable under UV light from the wallboard joint.

2. The identifiable wallboard joint of claim 1, wherein said optical brightener is provided in an aqueous solution on an average of 0.005 weight percent, said solution being applied to said web of joint tape.

3. The identifiable wallboard joint of claim 1, wherein said optical brightener has the formula C.sub.28H.sub.20S.sub.2O.sub.6Na.sub.2.

4. The identifiable wallboard joint of claim 1, wherein said optical brightener is provided to said web of joint tape in an aqueous solution in a concentration equal to 0.0069 wt. %.

5. The identifiable wallboard joint of claim 1, wherein said optical brightener is applied on said web of joint tape in a pattern.

6. An identifiable wallboard joint, comprising: two wallboard panels having a wallboard joint therebetween; an identifiable wallboard joint tape applied to the wallboard joint, wherein the identifiable wallboard joint tape comprises a web of liquid permeable paper wallboard joint tape incorporated with an optical brightener, which is formed by applying an aqueous solution having the optical brightener in a concentration of 0.005 weight percent to the web of wallboard joint tape, and wherein said brightener has the formula C.sub.28H.sub.20S.sub.2O.sub.6Na.sub.2; and a layer of joint compound covering the identifiable wallboard joint tape, wherein under standard lighting conditions, said optical brightener is invisible and wherein said identifiable wallboard joint tape is visible and visually distinguishable under UV light from the wallboard joint.

7. The identifiable wallboard joint of claim 6, wherein said optical brightener is applied on said web of wallboard joint tape in a pattern.

8. An identifiable wallboard joint, comprising: two wallboard panels having a wallboard joint therebetween: an identifiable wallboard joint tape applied to the wallboard joint, wherein the identifiable wallboard joint tape comprises a web of liquid permeable paper wallboard joint tape integrally incorporated with an optical brightener, which is formed by applying an aqueous solution having the optical brightener in a concentration of 0.0069 weight percent to the web of wallboard joint tape, and wherein the applying is by embedding, coating, spraying, dipping, rolling, mist rolling, stamping, printing or otherwise surface treating said web of wallboard joint tape; and a layer of joint compound covering the identifiable wallboard joint tape, wherein under standard lighting conditions, said optical brightener is invisible and wherein said identifiable wallboard joint tape is visible and visually distinguishable under UV light from the wallboard joint.

9. The identifiable wallboard joint of claim 8, wherein said optical brightener is applied on said web of wallboard joint tape in a pattern.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. FIGS. 1a-b are a plan view of two wallboard tapes, control and treated, under normal illumination on the left (1a), and under UV illumination on the right (1b);

(2) FIGS. 2a-b depict a partially finished wallboard joint having a coat of joint compound covering the present tape under normal illumination on the left (2a), and under UV illumination on the right (3b); FIG. 3a-b depict a partially finished wallboard joint having a second coat of joint compound freshly applied over the joint of FIG. 2, under normal illumination on the left, and under UV illumination on the right;

(3) FIG. 4a-b are views of the same wallboard joint in FIGS. 4a-b after drying, the left side under normal illumination, the right side under UV illumination; FIGS. 5a-d are a collection of four views of a finished wallboard joint, with zones showing control tape and treated tape under UV illumination;

(4) FIGS. 6a-d show the finished wallboard joint of FIGS. 4a-d with surface partial removal and illuminated by UV light;

(5) FIGS. 7a-b depict four strips of wallboard tape with varying concentrations of the present brightener, shown in normal illumination at the top half (7a), and under UV illumination at the bottom half (7b);

(6) FIGS. 8a-b depict the four strips of wallboard tape shown in FIGS. 7a-b and covered with a skim coat of wallboard joint compound, shown under normal daylight illumination at the top half (8a), and under UV illumination at the bottom half (8b);

(7) FIG. 9 shows the four strips of wallboard joint tape shown in FIGS. 8a-b covered in a completed wallboard joint with multiple layers of joint compound, with the tape shown in dashed lines, and exposed to UV illumination;

(8) FIG. 10 is a plot of Weighted Average Grayscale Intensity vs. Optical brightener solution concentration, weight %; and

(9) FIG. 11 is an embodiment of the present joint tape with the identifier applied in a design.

DETAILED DESCRIPTION

(10) The present wallboard joint tape is provided to address the situation where there is a need for identifying a joint tape as originating with a particular manufacturer. In such occasions, it is advantageous to provide an identifier material to the joint tape, such as a fluorescing agent, also referred to as a tagging agent. Adding the identifier to the joint tape preferably occurs at the conclusion of product manufacture. In the preferred embodiment, after the tape has been sliced and sanded to improve bonding with the joint compound, the identifier material is applied by embedding, coating, spraying, dipping, rolled, mist rolled or otherwise surface treating the paper tape post production. However, it is also contemplated that the identifier is integrally incorporated with the wallboard tape during the formulation of the paper tape, with the identifier being part of the pulp slurry.

(11) In the preferred embodiment, the identifier material is Benetex OB-M1 fluorescent Whitening Agent, also referred to as an optical brightener, produced by Mayzo, Inc., Suwanee, Ga. 30024. The preferred optical brightener is a derivative of distyryl biphenyl (DSBP) compound, with a formula of C.sub.28H.sub.20S.sub.2O.sub.6Na.sub.2. Other optical brighteners are well known in the art of laundry detergent formulation, and are also considered suitable for the present composition. As discussed below, it has been found that the weight percentage of the identifier/optical brightener can be very low and still achieve the desired visual distinguishability when samples are viewed in the field using handheld UV lights. Accordingly, the present optical brightener is preferably provided in a weight percentage in the range of 0.001 to 0.01 weight (wt.) percent of an aqueous solution that is applied to the joint tape, such as by embedding, coating, spraying, dipping, rolled, mist rolled or otherwise surface treating the paper tape post production. A more preferred range of the optical brightener is approximately 0.003 to 0.007 wt. percent. Most preferably, the optical brightener is effective or visually distinguishable when applied in an aqueous solution where the optical brightener concentration is equal to or greater than 0.0069 wt. percent, and even more preferably 0.005 wt. percent. Thus, the brightener is effective and visually distinguishable under UV light at very low doses.

(12) After the present tape has been incorporated with the identifier and applied to a wallboard joint, the identifier is invisible to the eye under normal or standard lighting conditions, defined as conventional room illumination using fluorescent, incandescent and/or LED bulbs and fixtures or the like with optional ambient natural light when windows are present. Upon exposure of the present tape, or the associated wallboard joint to UV light, as through a hand-held UV blacklight used under standard lighting conditions described above, the indicator will fluoresce sufficiently to be detectable and visually distinguishable by the naked eye. As such, when exposed to UV light, the present tape is visible and visually distinguishable from the surrounding wallboard joint and joint compound, typically by fluorescing.

(13) Referring now to FIGS. la and 1b, webs or strips of the present wallboard tape 10 having the present identifier applied in an aqueous solution of 0.005 wt. percent are shown placed next to a control or untreated tape 16 illuminated under normal or standard light in FIG. 1a, and using a flashlight-style handheld UV light with normal-or standard light in FIG. 1b. It is seen in FIG. 1b that the treated tape 10 is significantly more visible and visually distinguishable under UV light.

(14) Referring now to FIGS. 2a and 2b, a wallboard joint is designated 18 (shown hidden) and represents the intersection of panels 20 and 22. In FIG. 2a, the untreated tape 16 has been applied to the joint, covered with a layer of joint compound 24 and illuminated with UV light. It will be seen that the tape is relatively invisible. In FIG. 2b, the tape 10 with the indicator has been applied to the joint 18 and was covered by a thin layer of joint compound 24 as is common in the initial stages of forming the taped wallboard joint, as is well known in the art. Again, in FIG. 2b, upon exposure to UV light, the tape 10 with the indicator is highly visible and visually distinguishable through the joint compound 24.

(15) Referring now to FIGS. 3a and 3b, the joint 18 of FIGS. 2a and 2b is shown with another layer of joint compound 24 applied after the first layer has dried, again as is common in the art. Upon exposure to UV light in FIG. 3a, with the second layer or joint compound 24 still wet, the untreated tape 16 is barely visible, while in FIG. 3b, the treated tape 10 is highly visible and is visually distinguishable from the surrounding wallboard joint 18 and the joint compound 24.

(16) Referring now to FIGS. 4a and 4b, the joint 18 is shown after the second layer of joint compound 24 has dried. In FIG. 4a, the untreated tape 16 is invisible under UV light, while in FIG. 4b the treated tape 10 with the identifier is highly visible to UV light and is visually distinguishable through multiple layers of joint compound 24.

(17) Referring now to FIGS. 5a-d, several views of the joint 18 with the untreated tape 16 are shown exposed to UV light. At this stage, the joint 18 is completed, with several layers of joint compound 24 applied, dried and sanded, as is the well-known custom in the art. In FIGS. 5a and 5b, the position of the tape 16 is marked by lines 26.

(18) Referring now to FIGS. 6a-6d, several views are provided of the joint 18 with the treated tape 10 having the present identifier. In these views, the layers of joint compound 24 have been partially removed using various techniques in the manner used in the field by inspectors in the process of studying the effectiveness of a conventional wallboard joint finishing procedure. In FIG. 6a, the joint compound 24 has been removed by digging it out in a region 28 to expose the tape 10. As seen, under UV illumination, the tape 10 is highly visible and visually distinguishable from the surrounding joint compound 24 and the joint 18. In FIG. 6b, the joint compound 24 has been scored heavily with a knife at 30 in two regions. In FIG. 6c, the joint compound 24 has been sanded in the region 32 to expose the tape 10, which is highly visible and distinguishable under UV light. Lastly, in FIG. 6d, the joint compound has been selectively picked away in region 34 to reveal the tape 10, again highly visible and distinguishable under UV light. As indicated above, the UV light is applied with normal illumination in the room.

(19) Referring now to FIGS. 7a and 7b, four strips of joint tape are shown placed on a substrate, such as the wallboard panel 20, with a strip 40 being untreated with any optical brightener, a strip 42 having the optical brightener incorporated into the tape at 0.0625 wt. %; a strip 44 having the optical brightener incorporated at 0.0208 wt. %, a strip 46 having the optical brightener incorporated at 0.0069 wt.%. In FIG. 7a at the top half of the image, the strips 40-46 are shown under standard or normal interior illumination. In FIG. 7b, at the bottom half of the image, the strips 40-46 are shown under UV light as described above, sourced from a UV fluorescent tube, with normal interior illumination turned off. Note that while under normal illumination, all of the strips 40-46 appear the same and are visually indistinguishable from each other, under UV illumination, all of the treated strips 42-46 are visible and visually distinguishable from the untreated strip, even at the relatively low concentration of 0.0069 wt.%. Thus, the present wallboard joint tape is visually distinguishable with brightener concentrations in an aqueous solution of equal to or greater than 0.0069 wt. %.

(20) Referring now to FIGS. 8a and 8b, the four strips 40-46 described above are shown coated with a thin layer of tape coat of joint compound 48, then covered with another relatively thin skim coat of joint compound 50, as is common in the art during the wallboard joint taping process. In FIG. 8a, the strips are shown under standard or normal daylight artificial illumination, as described above. In this view, all of the strips 40-46 are covered with joint compound and are visually indistinguishable from each other. However, in FIG. 8b, under UV illumination, all of the treated strips 42-46 are visually distinguishable from the untreated strip 40, even the strip 46 with the lowest concentration of optical brightener at 0.0069 wt. %.

(21) Referring now to FIG. 9, which shows the same tape samples, strips 40,42,44, and 46, as FIG. 7 but are shown converted to grayscale for image processing. By converting the images to grayscale and then measuring the grayscale intensity, the brightness of each tape, under exposure to UV light only, can be measured and compared. The dashed white box at 52 drawn on each of the tape samples designates the area that was used for image processing. The results of the image processing are shown in FIG. 10. Even without an image processing technique it is clear that all of the treated strips 42-46 are visually distinguishable from the untreated strip 40, even the strip 46 with the lowest concentration of optical brightener. Referring now to FIG. 10, a graphical comparison of the weight percent of optical brightener with a weighted average of Grayscale Intensity is plotted for each of the test wallboard tape strips 40-46 described above. As is known in the art, Grayscale Intensity measures the whiteness of a colored surface, with 0.0 Intensity designating the blackest black, with absolutely no whiteness, and 255.0 is the extreme whitest white. The vertical error bars 56 reflect the range of test values from the lightest to the darkest pixel measured from each sample of the tape 40-46 using computer software known in the art. The tape samples 46 received a 77.7 Intensity, which, as discussed above, is visually distinguishable from the control strip 40 under UV light, whether or not the tape is exposed on a substrate, or is covered with several layers of wallboard joint compound as is customary in the wallboard joint finishing process. The tape samples 44 received an Intensity of 105.6, and the samples 42 received an Intensity of 128.5, both of which are also discussed above as being visually distinguishable over the control strip 40.

(22) Referring now to FIG. 11, an alternate embodiment of the present joint tape is generally designated 60. The tape 60 shares all of the above-described characteristics of the tape 10 described above, with the main distinction being that the identifier, shown here as 62, is applied in a distinct pattern, logo, certification symbol or the like on the tape, rather than being sprayed or otherwise applied or impregnated across the entire strip of tape. Since the tape 10 is often produced and sold in rolls, the identifier pattern 62 is contemplated as being applied in regular intervals along the strip of tape.

(23) While a particular embodiment of the present fluorescent joint tape has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.