Three-in-one jointing tape

Abstract

The invention relates to a jointing tape (10) for jointing a gap (20g) between two abutting plasterboards (20) comprising a support film (1) and a jointing assembly (11) comprising in sequential order, - a first layer (2) of ready-mix jointing composition applied on the support film (1), wherein the first layer (z) of ready-mix jointing composition is in a flowable state, - a structural fibrous tape (3) made of fibres, and - a second layer (4) of ready-mix jointing composition, wherein the second layer (4) of ready-mix jointing composition is in a flowable state. The jointing tape (10) is rolled up to form a roll (10r) with the support film (1) forming an external surface of the roll (10r), and wherein the support film (1) is releasable from the first and second layers (2, 4) of ready-mix jointing compositions.

Description

THREE-IN-ONE JOINTING TAPEFIELD OF THE INVENTION

[0001] The invention relates to the field of jointing gaps between two abutting plasterboards. The present invention proposes a ready-to-use jointing tape allowing jointing a gap between two abutting plasterboards in a single operation.BACKGROUND OF THE INVENTION

[0002] Many inner walls and outer walls, even load bearing walls and ceilings in modern constructions are made of plasterboards fixed side by side to a frame made of metal or wooden beams. A gap is inevitably formed between two adjacent plasterboards, which need be jointed to form a continuously smooth wall surface, where the gaps between adjacent plasterboards are not visible to the naked eye.

[0003] Currently, applying a jointing compound to a gap is a complex and time consuming task. This operation requires a first layer of jointing composition to be applied to the gap and edges of the abutting plasterboards, e.g., with a knife or roller. The first layer must be left to dry during a time of the order of 6 to 24 h depending on the jointing composition. To stabilize the first layer during setting or drying, a structural fibrous tape made of fibres such as a paper joint tape or a scrim tape is generally applied on top of the still wet first layer. Because of shrinkage of the jointing composition upon setting or drying, a dip is formed along the gap. To eliminate the dip along the gap, a second layer of jointing composition is applied on top of the structural fibrous tape, e.g., with a knife and is left to set or dry. Once the second layer has set or dried (after another 6 to 24 h), it can be sanded and polished with appropriate tools, including e.g., sandpaper, to smoothen the joint and to form a perfectly smooth finish. These operations require skills and are generally out of reach for the average occasional DIY-handyman.

[0004] Application of the first and I or second layers of jointing compound can be made easier by using a finishing box. A finishing box is a container in the form of a box filled with liquid jointing compound and fixed at the end of a pole. As the finishing box is pushed by the user along the surface over the gap, jointing compound is dispensed through an adjustable nozzle onto the wall or ceiling. A uniform layer can thus be formed across the area covered by the box, resulting in a smooth finish, free from bumps and ridges. The use of a finishing box facilitates the application of the jointing compound, but the jointing operation remains a multi-step process extending over a long period of time.

[0005] So called grouting machines or more popularly referred to as bazookas are available. They permit to simultaneously apply paper tape and apply the exact amount of jointing composition for forming the first layer. Bazookas improve reproducibility and allow the first layerof jointing compound and tape to be applied quicker than when applied separately by hand. Bazookas, however, still require waiting that the first layer dries or sets before applying the second layer of jointing compound. The second layer can be applied with a finishing box. They are expensive and not that easy to use. Again, the occasional DYI-handyman is not likely to buy and learn how to handle a bazooka for jointing plasterboards of a single wall.

[0006] WO15061842 and WO10099563 describe a similar process as described supra, wherein the structural fibrous tape is applied first on top of the gap between abutting plasterboards, and first and second layers of jointing compound are successively applied,

[0007] WO17044329 describes a flexible adhesive composition reinforced with fibres to be applied over the gap between two abutting plasterboards. A single layer of joint compound is applied on top of the flexible adhesive composition after it has set. The flexible adhesive composition replaces the structural fibrous tape.

[0008] WO21095038 proposes a jointing compound reinforced with synthetic fibres. A single layer of jointing compound is sufficient, without the need for a structural fibrous tape or a second layer of jointing compound.

[0009] US5333433 discloses a self-adhesive wallboard finishing tape designed to conceal or finish joints between adjacent wallboard panels, creating a simulated monolithic wall surface. The tape features a substrate with first and second adhesive layers pre-applied to eliminate the need for a separate drywall cementitious compound layer. The first adhesive layers are cementitious and placed along the edges of the tape, while the central portion contains a pressure-sensitive adhesive.

[0010] US2020190365 discloses adhesive articles designed for damage-free removal from surfaces. These articles consist of a core with peelable adhesive layers on either side. The adhesives layers are based on acrylics, rubbers, silicones, or polyurethanes. No layer of ready mix is disclosed.

[0011] US20130075027 discloses a multi-layer assembly that includes a silicone-based pressure-sensitive adhesive composition. This invention addresses the issue of adhesion buildup between silicone-based adhesives and release liners over time and under varying environmental conditions. No layer of ready mix is disclosed.

[0012] Jointing the gaps between two adjacent plasterboards remains a lengthy and skilful operation requiring experience. There is to date no solution to substantially simplify the process of jointing two adjacent plasterboards, rendering it available to the occasional DYI-handyman. There is also no solution available to reduce the lengthy three-step operation of (1) applying the first jointing compound, (2) applying the structural fibrous tape, and (3) applying the second layer of jointing compound, once the first layer has dried or set, into a substantially shorter single-stepoperation.

[0013] The present invention proposes a jointing tape allowing gaps between abutting plasterboard to be jointed in a single and simple operation, which can be carried out quicker and / or also by occasional DYI-handypersons. These and other advantages of the present invention are described in more details in the following sections.SUMMARY OF THE INVENTION

[0014] The present invention concerns a jointing tape for jointing a gap between two abutting plasterboards comprising a support film and a jointing assembly comprising in sequential order,• a first layer of ready-mix jointing composition applied on the support film, wherein the first layer of ready-mix jointing composition which includes at least 30 wt.% of the total weight of the composition (i.e., including water), of mineral charge selected in calcium sulphate and or calcium carbonate is in a flowable state,• a structural fibrous tape made of fibres, and• a second layer of ready-mix jointing composition, wherein the second layer (4) of ready-mix jointing composition is in a flowable state, wherein the jointing tape is rolled up to form a roll with the support film forming an external surface of the roll, and wherein the support film is releasable,• from the second layer of ready-mix jointing composition, so that the jointing tape can be unrolled and• from the first layer of ready-mix jointing composition, so that, as the jointing tape is unrolled, the support film can be removed from the first layer of ready-mix jointing composition, while preserving an integrity of the first and second layers of ready-mix jointing composition.

[0015] The mineral charge selected among calcium carbonate and / or calcium sulphate, which can be present in an amount comprised between 30 and 80 wt.%, preferably between 50 and 70 wt.% of the total weight of the composition (i.e., including water), and a polymeric component selected among ethylene vinyl acetate (EVA), Vinyl ester of Vinyl acetate, polyvinyl acetate (PVAc), acrylic, styrene acrylic, styrene butadiene, polyvinylalcohol and blends or copolymers thereof, which can be present in an amount comprised between 0.5 and 10 wt.%, preferably between 1 and 8 wt.%, more preferably between 2 and 7 wt.% of the total weight of the composition, and water, which can be present in an amount comprised between 15 and 50 wt.%, preferably between 20 and 45 wt.%, more preferably between 22 and 35 wt.% of the total weight of the composition.

[0016] In another embodiment, the polymeric component is present between 1 and 10 wt.%, which can be present in an amount comprised between 1 and 10 wt.%, preferably between 2 and 7 wt.%, more preferably between 3 and 6 wt.% of the total weight of the composition and water which is present in an amount comprised between 15 and 50 wt.%, preferably between 20 and 40 wt.%, more preferably between 25 and 35 wt.% of the total weight of the composition.

[0017] The support film can be made of a polymer selected among polyethylene (PE), polypropylene (PP), polyester, preferably polyethylene terephthalate (PET), polyamide (PA), polystyrene, and the like, as well as blends and copolymers thereof.

[0018] The structural fibrous tape can be made of fibres selected among• synthetic or mineral fibres, preferably polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyester, acrylic, polyvinyl chloride (PVC), polyamide (PA), glass, and• natural fibres, preferably, cellulose, hemp, cotton, flax, maize,• or mixtures thereof.The structural fibrous tape maybe a nonwoven, preferably a woven fabric.

[0019] The support film can comprise perforations distributed over a surface thereof to promote drying of the first and second layers of ready-mix joint after application. In a preferred embodiment, the support film can comprise flaps distributed along lateral edges of the support film, which are configured for being folded over to cover lateral edges of the jointing tape.

[0020] The first and I or second layers of ready-mix jointing composition can comprise,• calcium carbonate, and• a polymeric component selected among ethylene vinyl acetate (EVA), polyvinyl acetate (PVAc), acrylic, styrene acrylic, and blends or copolymers thereof, and• water.The first layer of ready-mix jointing composition is preferably identical to the second layer of ready-mix jointing composition.

[0021] In a preferred embodiment, each of the first and second layers of ready-mix jointing composition has in the flowable state a Brookfield viscosity comprised between 200 and 1000 Pa s, preferably between 400 and 900 Pa s, more preferably between 400 and 800° Pa s, measured at 20°C with a spindle D rotating at 2.5 revolutions per minute (RPM).

[0022] The jointing tape can have a width (W) of the jointing tape comprised between 20 and150 mm, preferably between 30 and 100 mm, more preferably between 40 and 70 mm. To prolong storage time of the jointing tape, the roll is preferably packed such that the first and second layers of ready-mix jointing composition maintain their flowable state during storage of the jointing tape.

[0023] The present invention also concerns a method for jointing a gap between first and second abutting plasterboards. The method comprises the following steps.• providing two abutting plasterboards separated by a gap,• providing a roll of the jointing tape as defined supra,• unroll the roll and apply the jointing tape over and along the gap with the second layer of ready-mix jointing composition contacting a surface of each of the first and second abutting plasterboards flanking the gap,• apply a pressure on the support film of the jointing tape to spread the first layer of ready-mix jointing composition and to drive the second layer of ready-mix jointing composition to penetrate into the gap; the pressure is preferably applied by means of a tool, preferably a roller or a knife,• remove the support film to leave only the jointing assembly in place.

[0024] In an embodiment of the invention, the first layer of ready-mix jointing composition is allowed to solidify, and wherein the support film is removed after the first layer of ready-mix jointing composition is solidified, preferably when the C-shore hardness of the first layer of ready-mix jointing composition is at least 60, preferably at least 70, more preferably at least 75.

[0025] In an alternative embodiment, the support film is removed before the first layer of ready-mix jointing composition is solidified. Pressure can thereafter be applied onto the first layer of ready-mix jointing composition to smoothen the surface thereof, preferably by means of a tool, more preferably a roller or a knife.

[0026] The present invention also concerns a process for producing a jointing tape as defined supra. The process comprises the following steps.• feeding a continuous support film,• applying the first layer of ready-mix jointing composition onto a surface of the continuous support film, applying a continuous structural fibrous tape (3) on top of the first layer of ready-mix jointing composition,applying the second layer of ready-mix jointing composition onto a surface of the continuous structural fibrous tape,• rolling the thus formed jointing tape to form a roll,• the roll can be conditioned in a package ensuring that the first and second layers of ready-mix jointing composition maintain their flowable state during storage of the jointing tape.

[0027] If the support film is provided with flaps, the flaps can be folded over the lateral edges of the jointing tape upon rolling it to form the roll.SHORT DESCRIPTION OF THE DRAWINGS

[0028] These and further aspects of the invention will be explained in greater detail by way of example and with reference to the accompanying drawings in which,Figure 1a shows a perspective view of the layers forming the 3-in-1 jointing tape of the present in invention.Figure 1 b shows a detail of the surface of a preferred support film comprising perforations.Figures 2a & 2b show two embodiments of jointing tapes rolled up in a roll.Figure 3a shows a step of applying the jointing tape to a gap between two plasterboards, by unrolling the jointing tape and applying pressure on the thus applied tape with an appropriate tool (e.g., knife or roller).Figure 3b shows the removal of the support film and sanding of the thus formed joint with an appropriate tool (e.g., sandpaper).Figures 4a & 4b show the application of the jointing tape onto the gap by unrolling the jointing tapes of Figures 2a & 2b wherein the edges of the abutting plasterboards are (4a) straight and (4b) chamfered.Figures 5a & 5b show the cross-sections of the plasterboard gaps of Figures 4a & 4b jointed after smoothing of the first and second layers of jointing compound and removal of the support film.Figure 6 shows an apparatus for producing the jointing tape of the present invention.Figure 7a shows a preferred embodiment of support film comprising flaps.Figure 7b shows a roll with a support film according to Figure 7a, with the flaps folded to protect the sides of the roll from evaporation.DETAILED DESCRIPTION OF THE INVENTION

[0029] As illustrated in Figures 1.a and 1.b, the present invention concerns a jointing tape (10) for jointing a gap (20g) between two abutting plasterboards (20). The joining tape (10) comprises a support film (1) and a jointing assembly (11). The jointing assembly (11) comprises in sequential order,• a first layer (2) of ready-mix jointing composition applied on the support film (1), wherein the first layer (z) of ready-mix jointing composition is in a flowable form,• a structural fibrous tape (3) made of fibres, and• a second layer (4) of ready-mix jointing composition, wherein the second layer (4) of ready-mix jointing composition is in a flowable form.

[0030] As shown in Figures 2a and 2b, the jointing tape (10) is rolled up to form a roll (1 Or) with the support film (1) forming the outer surface of the roll (1 Or). The support film (1) is releasable from both first and second layers of ready-mix jointing composition while preserving an integrity of the first and second layers (2, 4). The support film (1) must be releasable from the second layer (4) of ready-mix jointing composition to allow the jointing tape to be unrolled. The support film (1) must be releasable from the first layer (2) of ready-mix jointing composition to allow, the support film (1) to be removed from the first layer (2) of ready-mix jointing composition after the jointing tape (10) is unrolled and applied to the gap (20g) between the two abutting plasterboards (20).

[0031] The roll (1 Or) of jointing tape (10) is preferably packed such that the first and second layers (2, 4) of ready-mix jointing compositions maintain their flowable state during storage of the jointing tape (10). The packaging must offer a barrier to moisture to maintain stable the level of moisture in the first and second layers (2, 4) of ready-mix jointing composition. The roll (1 Or) is preferably packed in a vacuum. The packaging can be made of water resistant paper, such as coated paper, e.g., wax paper, or parchment paper, or it can be made of a polymer film, such as polyethylene, polypropylene, polystyrene, and the like.The present invention also concerns a method for jointing a gap (20g) between first and second abutting plasterboards (20) comprising providing two abutting plasterboards (20) separated by a gap (20g) and providing a jointing tape (10) as defined supra. As illustrated in Figures 3a, 4a, and 4b, the roll (1 Or) is unrolled and the jointing tape (10) is applied over and along the gap (20g) with the second layer (4) of ready-mix jointing composition contacting a surface of each of the first and second abutting plasterboards (20) flanking the gap (20g). A pressure is applied onto the support film (1) of the jointing tape to spread the first layer (2) of ready-mix jointing composition and to drive the second layer (4) of ready-mix jointing composition to penetrate into the gap (20g). The support film (1) can be removed either before or after the first layer (2) of ready-mix jointing composition it is in contact with has set or solidified. After removal of the support film (1) only the jointing assembly (11) is left in place jointing the gap (20g) between the two plasterboards (20).THE SUPPORT FILM (1)

[0032] As the name indicates, a function of the support film (1) is to support the jointing assembly (11) comprising the first layer (2) of ready-mix jointing composition, the structural fibrous tape (3), and the second layer (4) of ready-mix jointing composition. The support film (1) must also be flexible enough to allow rolling the jointing tape (10) into a roll (1 Or). When the jointing tape is rolled up, each surface of the support film (1) is in contact with one of the first and second layers (2, 4) of ready-mix jointing composition. For this reason, and because the support film (1) is to be removed from the jointing assembly (11) after application of the jointing tape (10) over the gap (20g) separating the two plasterboards, both surfaces of the support film (1) must have surface energy properties such that adhesion thereof with the first and second layers (2, 4) of ready-mix jointing composition remains weak. This is required to fulfil the condition defined supra, that the support film (1) must be releasable from both first and second layers of ready-mix jointing composition while preserving an integrity of the first and second layers (2, 4).

[0033] The integrity of the first and second layers (2, 4) is preserved if after removal of the support film (1), not more than 10 wt.%, preferably not more than 5 wt.%, more preferably not more than 1 wt.% of the total weight of ready-mix joint composition of, respectively, the first and second layers (2, 4) is removed together with the support film (1). For the second layer (4), this condition must necessarily be fulfilled when the ready-mix joint composition is in the flowable form, to allow the jointing tape (10) to be unrolled without losing any (substantial amount) of the ready-mix composition of the second layer (4).

[0034] For the first layer (2), it depends on the use of the jointing tape (10). If the support film (1) is to be removed directly after application of the jointing tape over the gap region between the two plasterboards, then this condition must necessarily be fulfilled when the ready-mix joint composition of the first layer (2) is in the flowable form. If, on the other hand, the support film (1) is to be removed only after the first layer (2) has set or solidified, then this condition must be fulfilled at least after setting or solidification of the first layer (2) of ready-mix joint composition.

[0035] To fulfil the foregoing functions and conditions, the support film is preferably made of a material having a low surface energy. For example, the surface energy of the support film (1) is preferably not more than 40 mJ I m2, preferably not more than 35 mJ I m2or not more than 31 mJ I m2. For example, the support film can be a polymer, such as polyethylene terephthalate (PET), polyamide (PA), polystyrene preferably polyethylene (PE), polypropylene (PP) or polyester, and the like, as well as blends and copolymers thereof. Alternatively, the support film (1) can be made of hydrophobic paper such as parchment paper or coated paper, e.g., wax paper polymer or silicone coated paper. As well known in the art, the surface energy of a solid surface can be determined by measuring the contact angle of a sessile drop of liquid of known surface tension sitting on the solid surface (e.g., water has a surface tension of 72 mJ I m2).

[0036] The thickness of the support film (1) is only dictated by the requirement of being strongenough to support the jointing assembly (11) and flexible enough to allow easy rolling and unrolling the jointing tape (10). The thinner the better for obvious ecological and financial reasons, as well as for reducing the diameter of the roll (1 Or).

[0037] In a preferred embodiment, particularly advantageous when the support film is to be removed after the first layer (2) of ready-mix jointing composition has set or solidified, the support film (1) comprises perforation (1 P) as illustrated in Figure 1 b. The perforations allow an exchange between the first layer (2) of ready-mix jointing composition and the ambient atmosphere favouring elimination of moisture from the first layer (2) of ready-mix jointing composition and contact of the latter with ambient air to enhance setting or solidification of the first layer (2) of ready-mix jointing composition. The perforations need not be large and can have a hydraulic diameter Dh = 4 A / P, wherein A is the area and P the perimeter of a perforation, comprised between 0.5 and 3 mm, preferably between 0.8 and 2 mm. The perforations (1 P) can cover up to 50% of the area of the support film (1), preferably up to 30%, more preferably up to 20%. The perforations can cover at least 5%, preferably at least 10% of the support film area. For example, the support film (1) can comprise 0.3 to 1 perforation per cm2, depending on the dimensions of the perforations.

[0038] In an embodiment of the invention illustrated in Figures 7a and 7b, the support film (1) comprises flaps (1 f) distributed along the longitudinal edges thereof. The flaps (1 f) are configured for being folded substantially normal to the support film (1) to contact and cover the lateral edges of the jointing tape (10). They preferably have a substantially trapezoidal geometry to allow the lateral edges of the thus folded flaps (1 f) to contact or overlap each other when rolled into a roll as shown in Figure 7b. The lateral flaps are preferably folded to contact the lateral edges of the jointing tape (1) upon rolling the jointing tape into a roll (1 Or). This embodiment has the advantage of preventing drying by evaporation of the first and second layers (2, 4) of ready-mix jointing compositions from the lateral edges of the jointing tape (10) during storage of the roll (1 Or) both packed and also unpacked after use of only a portion of the jointing tape (10). It also has the advantage of allowing unpacking of the roll (1 Or) from the package without any of the ready-mix joint compositions of the first and second layers (2, 4) inadvertently flowing out and dirtying hands and surfaces which the roll could be laid on.FIRST LAYER (2) OF READY-MIX JOINTING COMPOSITION

[0039] The first layer (2) of ready mix-jointing composition is the layer which will be visible after application of the jointing tape (10) and removal of the support film (1). After optional sanding and polishing, it should therefore have a surface finish similar to the surfaces of the first and second plasterboards (20). A ready-mix composition is a composition that does not require mixing with water prior to use, It must be in a flowable state, with a consistency similar to a soft playing dough, in that it must not be free flowing, but can be pressed and deformed plastically by hand pressure. Typically, the first layer (2) of ready mix jointing composition can have in the flowable state thereofa Brookfield viscosity, comprised between 200 and 1000 Pa s, preferably between 400 and 900 Pa s, more preferably between 400 and 800° Pa s, measured at 20°C with a spindle D rotating at 2.5 revolutions per minute (RPM).. The ready-mix jointing composition sets or solidifies alone, upon exposure to ambient air. It preferably sets or solidifies in not more than 24 h, preferably in not more than 12 h, more preferably in not more than 6 h, and can set or solidify between 1 and 2 h. The first layer (2) of ready mix-jointing composition is considered to have set or solidified when the C-shore hardness thereof is at least 60, preferably at least 70, more preferably at least 75.

[0040] Any ready-mix jointing composition showing the required viscosities and setting or solidifying times can be used to form the first layer (2). In a preferred embodiment, the first layer (2) of ready-mix jointing composition comprises,• a mineral charge, such as calcium carbonate and I or calcium sulphate, which can be present in an amount comprised between 30 and 80 wt.%, preferably between 50 and 70 wt.% of the total weight of the composition (i.e., including water), and• a polymeric component selected among ethylene vinyl acetate (EVA), polyvinyl acetate (PVAc), acrylic, styrene acrylic, and blends or copolymers thereof, which can be present in an amount comprised between 1 and 10 wt.%, preferably between 2 and 7 wt.%, more preferably between 3 and 6 wt.% of the total weight of the composition, and• water, which can be present in an amount comprised between 15 and 50 wt.%, preferably between 20 and 40 wt.%, more preferably between 25 and 35 wt.% of the total weight of the composition.

[0041] The first layer (2) of ready-mix jointing composition can comprise additional components. For example, it can comprise a secondary mineral charge, such as talc, mica, perlite, and I or glass beads (preferably hollow), and mixtures thereof. The secondary mineral charge can be present in amounts comprised between 0 and 40 wt.%, preferably between 5 and 30 wt.%, more preferably between 10 and 20 wt.%. It can also comprise a thickening agent, such as starch, a gum, e.g., gum Arabic, clay, polyacrylamide, or mixtures thereof. The thickening agent can be present in amounts comprised between 0 and 5 wt.%, preferably between 0.2 and 3 wt.%. A water retention agent such as a cellulose ether can be added in amounts comprised between 0.1 and 0.3 wt.%, and polyvinyl alcohol (PVOH) can be used as binder or adhesive aid, in amounts comprised between 0 and 2 wt.%, preferably between 0.2 and 1 .5 wt.%. A defoaming agent, such as an oil, preferably a silicone based oil can be added in amounts comprised between 0.05 and 0.1 wt.%, and between 0 and 1 wt.% of a water repellent such as a siloxane or silicone can be used. The first layer (2) of ready-mix jointing composition can also comprise fibres, such as glass, polymeric fibres, or natural fibres. Finally, because the jointing tape is stored with substantial amounts of water, between 0.4 and 1 wt.%, preferably between 0.5 and 0.6 wt.% of a biocide is preferably added to the composition.

[0042] The first layer (2) of ready-mix jointing composition can comprise a same or different selection of components as the second layer (4) of ready mix-jointing composition; in same or different amounts. Preferably, the composition of the first layer (2) of ready mix-jointing composition is identical to the second layer (4) of ready-mix jointing composition.STRUCTURAL FIBROUS TAPE (3)

[0043] The structural fibrous tape (3) is formed of one or more types of fibres. The present invention is not restricted to any particular type of fibres which can be either,• synthetic or mineral fibres, such as polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyester, acrylic, polyvinyl chloride (PVC), polyamide (PA), glass, or• natural fibres, preferably, cellulose, hemp, cotton, flax, maize, and the like,

[0044] The fibres can be continuous or short (e.g., chopped), woven, nonwoven, braided, and the like. The structural fibrous tape (3) can be homogenous (i.e., comprising a single type of fibres) or hybrid, (i.e., comprising two or more types of fibres). The structural fibrous tape (3) is sandwiched between the first and second layers (2, 4) of ready-mix jointing compositions. It has several functions, including one or more of, giving structural stability to the jointing tape (10), bridging the gap between two plasterboards (20), forming a relatively smooth surface, and enhancing adhesion between first and second layers (2, 4) of ready-mix jointing composition. A binder can be used to stabilize the structural fibrous tape (3) and / or to enhance adhesion with the first and second layers (2, 4) of ready-mix jointing composition.

[0045] In one embodiment, the fibres can be cellulose and the structural fibrous tape can be made of paper, optionally sized and / or coated. In an alternative embodiment, the structural fibrous tape (3) can be made of a gauze mat, forming an open mesh allowing penetration therethrough of the ready-mix compositions of the first and second layers (2, 4) and thus enhancing mechanical adhesion.SECOND LAYER (4) OF READY-MIX JOINTING COMPOSITION

[0046] The second layer (4) of ready mix-jointing composition is the layer which, upon application of the jointing tape (10) over the gap (20g), will penetrate and partially fill the gap (20g) formed between two adjacent plasterboards (20). For this reason, as shown in Figure 2b, the second layer (4) of ready mix-jointing composition can have a thickness larger than the first layer (2) of ready mix-jointing composition. The second layer (4) of ready mix-jointing composition will not be visible after application of the jointing tape (10), so that the surface finish thereof is not a priority, and it needs not be easily sanded or polished after setting or solidifying. A ready-mix composition is a composition that does not require mixing with water prior to use, It must be in a flowable form, with a consistency similar to a soft playing dough, in that it must not be free flowing, but can bedeformed and pressed by hand pressure. Typically, the second layer (4) of ready mix jointing composition can have in the flowable state thereof a Brookfield viscosity, comprised between 200 and 1000 Pa s, preferably between 400 and 900 Pa s, more preferably between 400 and 800° Pa s, measured at 20°C with a spindle D rotating at 2.5 revolutions per minute (RPM).. The readymixjointing composition sets or solidifies alone, upon exposure to ambient air. It preferably sets or solidifies in not more than 24 h, preferably in not more than 12 h, more preferably in not more than 6 h, and can set or solidify between 1 and 2 h. The second layer (4) of ready mix-jointing composition has set or is solidified when the C-shore hardness thereof is at least 60, preferably at least 70, more preferably at least 75.

[0047] The second layer (4) of ready mix-jointing composition must be releasable from the support film (1) in the flowable state thereof, since it contacts the support film (1) in the rolled up configuration only and must be released therefrom when the jointing tape (10) is unrolled for application to a drywall.

[0048] Any ready-mix jointing composition showing the required viscosities and setting or solidifying times can be used to form the second layer (4). In a preferred embodiment, the second layer (4) of ready mix-jointing composition can be formed of the same components as listed for the first layer (2) of ready-mix jointing composition, namely comprising,• a mineral charge, such as calcium carbonate and I or calcium sulphate, which can be present in an amount comprised between 30 and 80 wt.%, preferably between 50 and 70 wt.% of the total weight of the composition (i.e., including water), and• a polymeric component selected among ethylene vinyl acetate (EVA), polyvinyl acetate (PVAc), acrylic, styrene acrylic, and blends or copolymers thereof, which can be present in an amount comprised between 1 and 10 wt.%, preferably between 2 and 7 wt.%, more preferably between 3 and 6 wt.% of the total weight of the composition, and• water, which can be present in an amount comprised between 20 and 50 wt.%, preferably between 25 and 35 wt.% of the total weight of the composition.

[0049] The second layer (4) of ready-mix jointing composition can comprise additional components. For example, it can comprise a secondary mineral charge, such as talc, mica, perlite, and I or glass beads (preferably hollow), and mixtures thereof. The secondary mineral charge can be present in amounts comprised between 0 and 40 wt.%, preferably between 5 and 30 wt.%, more preferably between 10 and 20 wt.%. It can also comprise a thickening agent, such as starch, a gum, e.g., gum Arabic, clay, polyacrylamide, or mixtures thereof. The thickening agent can be present in amounts comprised between 0 and 5 wt.%, preferably between 0.2 and 3 wt.%. A water retention agent such as a cellulose ether can be added in amounts comprised between 0.1 and 0.3 wt.%, and polyvinyl alcohol (PVOH) can be used as binder or adhesive aid, in amounts comprised between 0 and 2 wt.%, preferably between 0.2 and 1 .5 wt.%. A defoamingagent, such as an oil, preferably a silicone based oil can be added in amounts comprised between 0.05 and 0.1 wt.%, and between 0 and 1 wt.% of a water repellent such as a siloxane or silicone can be used. The second layer (4) of ready-mix jointing composition can also comprise fibres, such as glass, polymeric fibres, or natural fibres. Finally, because the jointing tape is stored with substantial amounts of water, between 0.4 and 1 wt.%, preferably between 0.5 and 0.6 wt.% of a biocide is preferably added to the composition.

[0050] The second layer (4) of ready-mix jointing composition can comprise a same or different selection of components as the first layer (2) of ready mix-jointing composition; in same or different amounts. Preferably, the second layer (4) of ready mix-jointing composition is identical to the first layer (2) of ready-mix jointing composition.JOINTING TAPE (10)

[0051] The jointing tape (10) is formed by a jointing assembly (11) laid upon the support film (1) and rolled up to form a roll (1 Or) with the support film (1) forming the outer surface of the roll (1 Or), as illustrated in Figures 2a and 2b. The support film is removed after application of the jointing tape (10) onto a drywall, preferably albeit not necessarily after setting or solidification of the first layer (2) of ready-mix composition. As shown in Figures 3a, 5a and 5b, only the jointing assembly (11) remains in place on the drywall after removal of the support film (1).

[0052] As shown in Figures 1 a, 2a, and 2b, the jointing assembly (11) is formed by the structural fibrous tape (3) sandwiched between the first and second layers (2, 4) of ready-mix compounds. Both first and second layers (2, 4) of ready-mix compounds must be in a flowable state until use. A flowable state is a dough-like state, allowing plastic deformation by application of a gentle pressure. A flowable state can be defined by a Brookfield viscosity comprised between 200 and 1000 Pa s, preferably between 400 and 900 Pa s, more preferably between 400 and 800°Pa s, measured at 20°C with a spindle D rotating at 2.5 revolutions per minute (RPM). In order to maintain the flowable state of the first and second layers (2, 4) of ready-mix compounds during storage of the jointing tape (10), the roll (1 Or) can be packed in a water and I or air impervious package to substantially slow down or even block setting or solidification of anyone of the first and second layers (2, 4) of ready-mix compounds. For example, the roll (1 Or) is preferably packed under a vacuum.

[0053] The support film (1) must be releasable from the second layer (4) of ready-mix compound when the latter is in the flowable state, during unrolling of the jointing tape (10) as the second layer (4) of ready-mix compound is brought into contact with the two plasterboards (20). The support film (1) must also be releasable from the first layer (2) of ready-mix compound. Depending on whether the support film (1) is to be removed from the jointing assembly (11) before or after setting or solidification of the first layer (2) of ready-mix compound, the support film must be releasable from the first layer (2) of ready-mix compound in the flowable state or it suffices that it be releasable when the first layer (2) of ready-mix compound is solidified (i.e., the C-shorehardness thereof is at least 60, preferably at least 70, more preferable at least 75).

[0054] The dimensions of the jointing tape (10) must be optimised such as to reduce the number of cuts required to apply it. For example, the width (W) of the jointing tape (10) can be optimised depending on the geometry of the edges of the plasterboards (20). If the plasterboards have straight edges as shown in Figure 4a, the width (W) of the jointing tape illustrated in Figure 2b is lower than if the plasterboards (20) have chamfered edges as shown in Figures 2b and 4b. For example, the width (W) of the jointing tape can be comprised between 20 and 150 mm, preferably between 30 and 100 mm, more preferably between 40 and 70 mm. For use with plasterboards with straight edges (cf. Figure 4a), the width (W) is preferably comprised between 20 and 60 mm, preferably between 25 and 45 mm. For use with plasterboards with chamfered edges (cf. Figure 4b), the width (W) must span at least over the full width of the chamfered regions of both plasterboards (20) separated by the gap (20g). The width (W) can thus be preferably comprised between 35 and 120 mm, preferably between 50 and 110 mm. The expression “chamfered edge" is used herein to encompass any type of cut (i.e., removal of material) extending along an edge of a plasterboard (20), be it straight as shown in Figures 4b and 5b, or curved, and for all angles.

[0055] The thickness of the first layer (2) of ready-mix compound can be comprised between 100 and 1000 pm, preferably between 250 and 750 pm. When the thickness of the first layer (2) of ready-mix compound can be maintained constant for all types of plasterboards (20), the thickness of the second layer (4) of ready-mix compound preferably depends on the geometry of the plasterboard edges the jointing tape (10) is to be used with. In case of plasterboards with straight edges as shown in Figure 4a, the thickness of the second layer (4) of ready-mix compound must be sufficient to partially fill in the gap (20g), preferably totally fill between the two plasterboards, and to spread thinly on the plasterboards on either side of the gap (20g) as shown in Figure 5a. In case of plasterboards with chamfered edges as shown in Figure 4b, the thickness of the second layer (4) of ready-mix compound must be sufficient to partially fill in the gap (20g) between the two plasterboards as well as fully fill the chamfered portions flanking the gap (20g) and to spread thinly on the plasterboards adjacent to the chamfered portions, as shown in Figure 5b. Consequently, as shown by comparing Figures 2a and 2b, the thickness of the second layer (4) of ready-mix compound of a jointing tape (10) to be used with plasterboards (20) having chamfered edges (cf. Figures 2b and 4b) is preferably higher than the thickness of the second layer (4) of a jointing tape to be used with plasterboards (20) having straight edges (cf. Figures 2a and 4a). For example, the thickness of the second layer (4) of ready-mix compound can be comprised between 100 and 12000 pm. In jointing tapes (10) for use with plasterboards with straight edges, the thickness of the second layer (4) of ready-mix compound can be comprised between 100 and 12000 pm. In jointing tapes (10) for use with plasterboards with chamfered edges, the thickness of the second layer (4) of ready-mix compound can be comprised between 100 and the plasterboard thickness, preferably between 250 and 5000 pm.

[0056] The jointing tape (10) can have any length. It preferably has a length of at least 2500 mm,more preferably at least 3000 mm, most preferably at least 3500 mm to joint plasterboards of corresponding heights with a single jointing tape (10), with no interruption between, or overlap of two jointing tapes (10). Since the height of the plasterboards can greatly vary from case to case, it is preferred to not set a standard length to fit a given plasterboard height. The length of the jointing tape can therefore be as long as possible and is therefore limited by the desired diameter of the roll (1 Or), which also depends on the thicknesses of the various layers (1-4), in particular the thickness of the second layer (4) of ready-mix jointing composition. The diameter of the roll (1 Or) must allow an easy handling of the jointing tape (10) and an easy application of the jointing tape over a gap (20g) between two plasterboards (20). The diameter of the roll (1 Or) can be comprised between 50 and 300 mm, preferably between 100 and 200 mm.METHOD FOR JOINTING A GAP (20g) BETWEEN ABUTTING PLASTERBOARDS (20)

[0057] The jointing tape (10) of the present invention is advantageous for use in a method for jointing a gap (20g) between first and second abutting plasterboards (20). The method comprises the following steps. First, two abutting plasterboards (20) separated by a gap (20g) and a roll (1 Or) of jointing tape (10) as defined supra are provided.

[0058] As shown in Figure 3a, the roll (1 Or) is unrolled and the jointing tape (10) is applied over and along the gap (20g) with the second layer (4) of ready-mix jointing composition contacting a surface of each of the first and second abutting plasterboards (20) flanking the gap (20g). As the jointing tape (10) is being applied or after it was applied over the gap (20g), pressure is applied onto the support film (1) of the jointing tape to spread the first layer (2) of ready-mix jointing composition and to drive the second layer (4) of ready-mix jointing composition to penetrate the gap (20g). Preferably, the pressure can be applied onto the support film (1) with a roller (15r) or a knife (15b), as shown in Figure 3a. Applying the pressure onto the support film (1) has the advantages of keeping the tools clean with no direct contact thereof with the first layer (2) of ready-mix jointing composition, and of distributing the pressure over a larger area, yielding a smoother joint with few unevenness, requiring less sanding and polishing.

[0059] The support film (1) is removed to leave only the jointing assembly (11) in place. In one embodiment, the support film (1) is removed after the first layer (2) of ready-mix jointing composition is solidified. The jointing composition can be considered as being solidified preferably when the C-shore hardness of the first layer (2) of ready-mix jointing composition is at least 60, preferably at least 70, more preferably at least 75. In this embodiment, it is preferred that the support film (1) comprises perforations (1 P) as illustrated in Figure 1 b, to allow exchange of moisture and air between the jointing assembly (11) and ambient environment to accelerate setting or solidification of the first layer (2) and, to a lesser measure the second layer (4) of ready-mix joint compositions. After removal of the support film (1) from the jointing assembly, the solidified first layer (2) of ready-mix jointing composition is quite smooth. As shown in Figure 3b, if the finish is not satisfactory, it can be improved by sanding or polishing with sanding paper (15s)or any appropriate tool or accessory.

[0060] In an alternative embodiment, the support film (1) is removed before the first layer (2) of ready-mix jointing composition is solidified, i.e., before the C-shore hardness of the first layer (2) or ready-mix jointing composition has reached 60. In this embodiment, the support film (1) must be releasable from the first layer (2) of ready-mix jointing composition when it is in the flowable state (i.e., a 20°C Brookfield viscosity of not more than 1000 Pa s). The support film (1) is removable from the first layer (2) of ready-mix jointing composition in the flowable state if after removal of the support film (1), not more than 10 wt.%, preferably not more than 5 wt.%, more preferably not more than 1 wt.% of the total weight of the first layer (2) of ready-mix joint composition is removed with the support film (1).

[0061] After removal of the support film (1), pressure is preferably thereafter applied onto the first layer (2) of ready-mix jointing composition which is still in the flowable state, to smoothen the surface thereof, preferably by means of a tool, more preferably a roller (15r) or a knife (15b). The first and second layers (2, 4) of ready-mix jointing compositions are left to set or solidify. If, after solidification, the surface finish of the first layer (2) of ready-mix jointing composition is not satisfactory, it can be improved by sanding or polishing with sanding paper (15s) or any appropriate tool or accessory.

[0062] This method is substantially easier and quicker than traditional jointing operations, even using expensive and difficult to use equipment such as a bazooka. This method can be implemented by any average occasional DIY-handyman without any major difficulty. This method is quick and clean as no jointing composition needs be prepared and stirred until reaching the desired viscosity before applying a first layer by hand or with a finishing box or other grouting machine, waiting for the first layer to solidify before repeating the foregoing operations to apply a second layer.PROCESS FOR PRODUCING A JOINTING TAPE (10)

[0063] Figure 6 illustrates an embodiment of an apparatus for producing a jointing tape (10) of the present invention in a method comprising the following steps.

[0064] A continuous support film (1) is fed, preferably laid onto a conveying belt (30), and the first layer (2) of ready-mix jointing composition is applied onto a surface of the continuous support film (1). If the support film (1) is sufficiently strong to support the weight of the jointing assembly (11), a conveying belt (1) is not essential. To reduce the thickness of the support film (1), however, it is preferred to lay the support film on a conveying belt (30).

[0065] This is followed by applying a continuous structural fibrous tape (3) on top of the first layer (2) of ready-mix jointing composition. Then the second layer (4) of ready-mix jointing composition is applied onto a surface of the continuous structural fibrous tape (3). The thus formed jointing tape can be rolled to form a roll (1 Or). To increase the storage time of the jointing tape (10) theroll (1 Or) can be packaged such as to protect it from contact with the ambient atmosphere. This ensures that the first and second layers (2, 4) of ready-mix jointing composition maintain their flowable state during storage of the jointing tape (10). Preferably, the roll (1 Or) is packed under vacuum.

Claims

CLAIMS1 . Jointing tape (10) for jointing a gap (20g) between two abutting plasterboards (20) comprising a support film (1) and a jointing assembly (11) comprising in sequential order,• a first layer (2) of ready-mix jointing composition including at least 30 wt.% of mineral charge selected among calcium sulphate and or calcium carbonate applied on the support film (1), wherein the first layer (z) of ready-mix jointing composition is in a flowable state,• a structural fibrous tape (3) made of fibres, and• a second layer (4) of ready-mix jointing composition, wherein the second layer (4) of ready-mix jointing composition is in a flowable state, wherein the jointing tape (10) is rolled up to form a roll (1 Or) with the support film (1) forming an external surface of the roll (1 Or), and wherein the support film (1) is releasable,• from the second layer (4) of ready-mix jointing composition, so that the jointing tape can be unrolled and• from the first layer (2) of ready-mix jointing composition, so that, as the jointing tape (10) is unrolled, the support film (1) can be removed from the first layer (2) of ready-mix jointing composition, while preserving an integrity of the first and second layers (2, 4) of ready-mix jointing composition.

2. Jointing tape (10) according to claim 1 wherein the first layer (2) of ready-mix jointing composition comprises,• a mineral charge selected among calcium carbonate and I or calcium sulphate, which can be present in an amount comprised between 30 and 80 wt.%, preferably between 50 and 70 wt.% of the total weight of the composition (i.e., including water), and• a polymeric component selected among ethylene vinyl acetate (EVA), Vinyl ester of Vinyl acetate, polyvinyl acetate (PVAc), acrylic, styrene acrylic, styrene butadiene, polyvinylalcohol and blends or copolymers thereof, which can be present in an amount comprised between 0.5 and 10 wt.%, preferably between 1 and 8 wt.%, more preferably between 2 and 7 wt.% of the total weight of the composition, and• water, which can be present in an amount comprised between 15 and 50 wt.%, preferably between 20 and 45 wt.%, more preferably between 22 and 35 wt.% of the total weight of the composition.

3. Jointing tape (10) according to claim 1 or 2 wherein the support film (1) is made of a polymer selected among polyethylene terephthalate (PET), polyamide (PA), polystyrene, preferablypolyethylene (PE), polypropylene (PP), polyester, and the like, as well as blends and copolymers thereof.

4. Jointing tape (10) according to anyone of the preceding claims, wherein the structural fibrous tape (3) is made of fibres selected among• Synthetic or mineral fibres, preferably polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), polyester, acrylic, polyvinyl chloride (PVC), polyamide (PA), glass, and• natural fibres, preferably, cellulose, hemp, cotton, flax, maize, or mixtures thereof, and wherein the structural fibrous tape (3) is a nonwoven preferably a woven fabric.

5. Jointing tape (10) according to anyone of the preceding claims, wherein the first and / or second layers (2, 4) of ready-mix jointing composition comprise,• calcium carbonate and I or calcium sulphate, and• a polymeric component selected among ethylene vinyl acetate (EVA), polyvinyl acetate (PVAc), acrylic, styrene acrylic, and blends or copolymers thereof, and• water, and wherein the first layer (2) of ready-mix jointing composition is preferably identical to the second layer (4) of ready-mix jointing composition.

6. Jointing tape (10) according to anyone of the preceding claims, wherein a width (W) of the jointing tape is comprised between 20 and 150 mm, preferably between 30 and 100 mm, more preferably between 40 and 70 mm.

7. Jointing tape (10) according to anyone of the preceding claims, wherein the roll (1 Or) is packed such that the first and second layers (2, 4) of ready-mix jointing composition maintain their flowable state during storage of the jointing tape (10).

8. Jointing tape (10) according to anyone of the preceding claims, wherein the support film (1) comprises perforations (1 P) distributed over a surface thereof.

9. Jointing tape according to anyone of the preceding claims, wherein the support film (1) comprises flaps (1 f) distributed along lateral edges of the support film (1), which are configured for being folded over to cover lateral edges of the jointing tape (10).

10. Method for jointing a gap (20g) between first and second abutting plasterboards (20) comprising,• providing two abutting plasterboards (20) separated by a gap (20g),• providing a roll (1 Or) of the jointing tape (10) according to anyone of the preceding claims,• unroll the roll (1 Or) and apply the jointing tape (10) over and along the gap (20g) with the second layer (4) of ready-mix jointing composition contacting a surface of each of the first and second abutting plasterboards (20) flanking the gap (20g),• apply a pressure on the support film (1) of the jointing tape to spread the first layer (2) of ready-mix jointing composition and to drive the second layer (4) of ready-mix jointing composition to penetrate into the gap (20g), and• remove the support film (1) to leave only the jointing assembly (11) in place.11 . Method according to the preceding claim, wherein the first layer (2) of ready-mix jointing composition is allowed to solidify, and wherein the support film (1) is removed after the first layer (2) of ready-mix jointing composition is solidified, preferably when the C-shore hardness of the first layer (2) of ready-mix jointing composition is at least 60, preferably at least 70, more preferably at least 75.

12. Method according to claim 10, wherein the support film (1) is removed before the first layer (2) of ready-mix jointing composition is solidified, and wherein pressure is preferably thereafter applied onto the first layer (2) of ready-mix jointing composition to smoothen the surface thereof, preferably by means of a tool, more preferably a roller (15 r) or a knife (15b).

13. Method according to anyone of claim 10 to 12, wherein the pressure is applied onto the support film by means of a tool, preferably a roller (15 r) or a knife (15b).

14. Process for producing a jointing tape (10) according to anyone of claims 1 to 9, comprising• feeding a continuous support film (1),• applying the first layer (2) of ready-mix jointing composition onto a surface of the continuous support film (1),• applying a continuous structural fibrous tape (3) on top of the first layer (2) of ready-mix jointing composition,• applying the second layer (4) of ready-mix jointing composition onto a surface of the continuous structural fibrous tape (3),• rolling the thus formed jointing tape to form a roll (1 Or).

15. Process according to the preceding claim, wherein the roll (1 Or) is conditioned in a package ensuring that the first and second layers (2, 4) of ready-mix jointing composition maintain their flowable state during storage of the jointing tape (10).

Images