Patent application title: PLUG FOR PLASTERBOARD REPAIR
Gudrun S. Laukka (Lent, FR)
IPC8 Class: AE04G2302FI
Class name: Static structures (e.g., buildings) with means for split-prevention or damaged part repair
Publication date: 2015-10-29
Patent application number: 20150308133
A repair plug for sealing holes in plasterboards is provided. The repair
plug has gypsum plaster or the like material, substantially a conical
shape with a longitudinal axis extending between a front end and a back
end, a conical side wall, and recesses on the side wall. The recesses are
either longitudinal or spiral around the cylindrical side walls.
1. A repair plug (1) for sealing holes in plasterboards, said repair plug
comprising gypsum plaster or other chalk-like material and having a
conical shape with a longitudinal axis extending between a front end (3)
and a back end (4), wherein said back end has a wider circumference than
said front end, and having a conical side wall (2), the plug being shaped
with recesses (5) on the side wall (2) which recesses are either
longitudinal or spiral shaped around the conical side walls.
2. The repair plug of claim 1, having at least three longitudinal recesses (5) along the conical side wall (2).
3. The repair plug of claim 2, having in the range from four to ten longitudinal recesses (5) along the conical side wall.
4. The repair plug of claim 3, having four longitudinal recesses (5) along the conical side wall
5. The repair plug of claim 1, having spiraling recesses (5) with a pitch (11) in the range of about 5 to 15 mm.
6. The repair plug of claim 1, where the depth (9) of each recess is in the range of about 5-25% of the outer diameter of the plug.
7. The repair plug of claim 1, having a diameter in the range of about 5 to 12 mm.
8. The repair plug of claim 1, having a diameter in the range of about 12 to 90 mm.
9. The repair plug of claim 1, having a length in the range of about 10 to 120 mm.
10. The repair plug of claim 1, having an outer diameter in the range from 40 to 84 mm.
11. The repair plug of claim 1, having one or more vertical recesses (10) circumscribing the plug dividing the plug into two or more segments (12).
12. The repair plug of claim 11, having a segment length in the range of about 8 to 30 mm.
13. The repair plug of claim 1, having a conical angle in the range from about 0,25.degree. to 10.degree..
14. The repair plug of claim 1, having a conical angle in the range from about 0,5.degree. to 2.5.degree..
15. The repair plug of claim 1, wherein the side walls on said front end have a chamfered edge.
16. The repair plug of claim 1, having one or more markings on the side wall indicating the direction in which the plug is suited to be inserted.
17. The The repair plug of claim 16, having one or more markings pointing to the direction of the front end.
CROSS-REFERENCE TO RELATED APPLICATIONS
 This application claims priority of U.S. Provisional Application No. 61/984,570 filed on Apr. 25, 2014 under 35 U.S.C. §119(e), the entire contents of which are hereby incorporated by reference.
 Plasterboard, also referred to as drywall, gypsum board or sheetrock (proprietary name of United States Gypsum Company) is a common standard material for interior walls and ceilings in modern buildings. Plasterboard is made primarily from gypsum plaster, the semi-hydrous form of calcium sulphate (CaSO4•1/2H2O), typically mixed with additives such as fiber and mildew and fire resistance agents, which is sandwiched between two sheets of heavy paper or fiberglass mats. When the core sets and is dried, the sandwich becomes rigid and strong.
 It is easy to cut the plasterboards and make holes through them, e.g. for cords and pipes that have to cross the walls or ceilings being formed by the boards.
 Methods for repairing plasterboard constructions, e.g. closing off holes made for pipes or cords that are no longer used or holes from accidental impact, typically involve use of a joint compound (sometimes referred to as "mud") which is supplied as a powder for mixing with water or ready-to-use we paste. Such compound is also used for sealing and finishing joints between adjacent plasterboards in a wall structure. Larger holes require cutting even edges around the hole and fastening therein a suitably cut-out plasterboard piece.
 However, using joint material for filling cracks or holes can often be tedious as the material shrinks upon drying and several layers are often required which must be allowed to dry in between applications.
 Alternative simple and time-saving methods for repairing plasterboards would therefore be appreciated.
SUMMARY OF INVENTION
 The invention provides an improved plug for repairing plasterboards, and particularly for sealing holes. The plug has a conical shape with a longitudinal axis extending between a front end and a back end, and having a conical side wall and a substantially circular cross-section across the longitudinal axis. The cross-section can also have substantially a cross-shape or star-shape, e.g. as a three-pronged or five pronged start, as shown in the drawings. The plug further comprises recesses on the side wall which recesses are either longitudinal or spiral around the conical side walls. The conical angle is in certain embodiments in the range from about 0,25° to 8°.
BRIEF DESCRIPTION OF FIGURES
 FIGS. 1A, 1B, and 1C show a conical plug with longitudinal recesses, divided into segments that can be broken apart prior to use. The cross-section of the plug is shown in 1A. FIGS. 1B and 1C show variants of markings intended to show the direction of insertion of the plugs.
 FIGS. 2A, 2B, and 2C show an example of a wider plug
 FIGS. 3A, 3B and 3C show an example of an even wider plug of the invention.
 FIGS. 4A, 4B and 4C show an example of a wide single-segment plug.
 FIGS. 5A, 5B and 5C show an example of a wide single-segment plug.
 FIGS. 6A-6D illustrate an embodiment with a different cross-section, having five longitudinal recesses forming a five-armed star-shaped cross-section.
 FIGS. 7A-7D illustrate an embodiment with a different cross-section, having three longitudinal recesses forming a three-armed star-shaped cross-section.
 FIG. 8 shows an example of a plug with maximum width of 12 mm.
 FIG. 9 shows an example of a plug with maximum width of 18 mm.
 FIG. 10 shows an example of a plug with maximum width of 28 mm.
 FIG. 11 shows an example of a plug with maximum width of 34 mm.
 FIG. 12 shows an example of a single-segment plug with maximum width of 52 mm.
 FIG. 13 shows an example of a single-segment plug with maximum width of 74 mm.
 FIG. 14 shows an example of a single-segment plug with maximum width of 84 mm.
 The conical repair plug of the invention comprises gypsum plaster or materially similar material (chalk or chalk-like material including in particular conventional gypsum plaster (hydrated calcium sulfate) but can also be from calcium carbonate, magnesium carbonate, magnesium silicate, etc.). The term `chalk-like material` is used herein to describe solid, typically porous or semi-porous material, which can be readily filed or sanded down. Accordingly, the term also encompasses other material that fulfils this functional criterion, including but not limited to polymeric material, e.g. PVC-based polymer clay, cement material, and any mixtures of the above-mentioned materials. In certain embodiments polystyrene or similar plastic polymer material is used in the plug.
 The plug of the present invention has a substantially conical shape with a longitudinal axis extending between a front end 3 and a back end 4, the front end having a more narrow circumference than the back end. The plug further has a conical side wall 2 and a cross-section across the longitudinal axis which can be substantially circular or have other suitable shape such as but not limited to those illustrated in the accompanying drawings. The plug further has recesses 5 on the side wall 2 which recesses are preferably longitudinal but can also be spiral-shaped like a thread around the cylindrical side wall. These recesses 5 provide a filling space for joint material which is used for fastening the plug in the hole to be closed. Since the plug is made from a relatively soft chalk material, the recesses also aid in the insertion of a plug into a hole which is slightly smaller than the plug, as the plug can be lightly twisted or screwed in the hole, thereby peeling off some of the outermost material in between the recesses is peeled/polished off and the plug sits snugly in the hole. The conical shape of the plug further aids in the fastening as it means that the plug does not need to match the hole exactly.
 When the recesses on the side wall are longitudinal these are typically at least three and can also be in the range of about 4 to 10, such as 4, 5 or 6. This can however depend on the diameter of the plug; wider plugs (e.g. in the range of 12 to 50 mm such as in the range 20 to 40 mm) can in certain embodiments have a higher number of recesses, e.g. 1-4 recesses per cm of the outer circumference of the plug, forming a longitudinally striped pattern on the sidewall. Wider plugs can however as well have relatively few recesses, such as four, five or six. Examples of such plugs of varying diameter are shown in the accompanying figures. The invention is not limited to certain particular dimensions of the recesses, the width of the recesses may typically depend to some extent on the diameter of the plug and typically the recesses have an outermost width 7 in the range of about 2 to 10 mm. In certain plugs, particularly the larger plugs, the recesses can lie relatively close to each other such that the section 8 of the circumference of the plug (in between adjacent recesses) can be about as wide as the recess width 7, or the section 8 can be slightly shorter than the recess width 7, or substantially wider than the recess width, as in the embodiments shown in FIG. 5.
 In other useful embodiments, the plug has spiraling recesses, which spiral around the sidewall of the plug much like the thread of a screw. Similar to the longitudinal recesses described above, spiraling recesses can have varying depth and width, and can be arranged with varying pitch, i.e. how closely spaced the recesses are to each other. FIG. 3 illustrates two examples of different pitch 11 on two different plugs of this type.
 In certain embodiments, the repair plug described herein is shaped such that the depth of each recess is in the range of about 5-25% of the diameter of the plug, such as, e.g., in the range of about 5-20% or 5-15% or in the range of 5-10%, including about 5% or about 7% or about 10% but also any value in the range of about 10-20% of the diameter of the plug, such as in the range of about 12-20%, for example, 12%, 15% or 17%. The depth is measured from the outer most circumference radially to the inner most point of the recess.
 The plug of the present invention is not limited to certain dimensions. It follows however, that it is most useful for holes that are larger than can be readily closed and finished with a single layer of joint material. Consequently, the plugs can be relatively small, having a diameter in the range of about 5-12 mm, such as about 5 mm, 6 mm, 7 mm, 8 mm, 10 mm or 12 mm. Plugs with a larger diameter can be even more useful, such as with a diameter in the range of about 12-50 mm, such as in the range of about 12-25 mm, including the range of about 10-20 mm. In a particular embodiments the plugs are made even bigger, such as having a maximum cross section in the range of about 50-85 mm, e.g. having a width of about 54, 74 or 84 mm. Such plugs are however typically shorter and typically not segmented with vertical recesses, as their large width would make them difficult to break. In certain embodiments however such plugs are provided segmented, having relatively deeper vertical recesses than the more narrow types of plugs. Accordingly the vertical recesses on such segmented broad plugs can have a depth of 10-33%, meaning that the inner circumference of the plug in the vertical recess is in the range from 80% to 33% of the full external circumference. These large plugs are useful for closing of unused holes in walls intended for electrical circuitry, switches and the like. These extra wide plugs can have a length of about e.g. 1 cm, 2 cm, 3 cm or 4 cm or another suitable length. Such segmented plugs can accordingly have a total length which is e.g. 2×, 3× or 4× such length.
 The plugs can be suitably offered in lengths roughly corresponding to the thickness of the boards to be repaired. Plasterboards manufactured in accordance with the metric system can have a thickness such as 10, 12 or mm, and frequently walls are made from two layers of board. Consequently, in certain embodiments the plugs have a length such as 10, 12, 14, 18, 20, 24 or 30 mm. It should be noted that generally, interior walls have a hollow space and thus when a hole is being repaired, the plug does not have to be flush with the inner surface of the plasterboard, as it is in those cases only the outer, visible surface of the board that should be flat, such that after the repaired area has been finished and painted, the repaired area is preferably nearly invisible.
 The more narrow front end 3 is intended to be inserted first and is typically the end facing the inside of the wall after location of the plug, while the back end 4 is the end facing the outer, visible surface of the board. The front end 3 preferably has a chamfer 6 to ease insertion of the plug.
 In a useful embodiment the plug has one or more vertical recesses 10 that circumscribe the plug, dividing the plug into two or more segments 12, such as, e.g., 3, 4, 5 or 6 segments. By means of the recesses, the segments can be broken off the remaining plug, one by one, or more than one segment at a time. The length of each segment is consequently preferably such as any of the length values mentioned above, whereas the overall length of the plug in this embodiment is more, depending on the number of segments. If, for example, the segment length is 12 mm, one segment can be broken off for a suitable length to repair a single 12 mm plasterboard whereas two segments provide a plug of 24 mm, suitable for repair of a double-layered wall of two 12 mm plasterboards.
 The conical shape of the plugs of the invention has the added benefit that segmented plugs can be broken down into incrementally larger plugs, such that one plug, that typically may have four segments provides four slightly varying plug segments, or individual plugs after separating. Thus, a single size of a segmented plug readily fits different holes of slightly different size. This greatly improves flexibility of the plugs, which thus can be pre-made in relatively few sizes, yet fitting holes with a variety of diameters. The angle of the conical plug of the present invention can in some preferred embodiments be in the range from about 0.25° to about 10°, such as in the range from 0.25° to about 5°. Typically narrow plugs (e.g. with a width in the range 8-25 mm) will have a relatively small angle, such as in the range from about 0.25° to about 2.25°, such as in the range from about 0.3° to about 1.0°, such as but not limited to about about 0.36°, 0.5° , 0.67° or 0.75°.
 Wider plugs may in certain embodiments have relatively larger angle, such as in the range 1° to 10°, such as in the range from 1° to 8°, or in the range from 1 to 5°, such as but not limited to about 1°, 1.4°, 2°, 2.5°, 4°, 5°, 6°, or about 7.1°.
 The above angle values refer to the angle of the side wall relative to the longitudinal axis, also referred to as side angle, thus the true geometrical conical angle is twice the side angle.
Patent applications in class WITH MEANS FOR SPLIT-PREVENTION OR DAMAGED PART REPAIR
Patent applications in all subclasses WITH MEANS FOR SPLIT-PREVENTION OR DAMAGED PART REPAIR