Technical Field

[0001] The present disclosure relates generally to a joint compound for use on joints between adjacent wall panels and, in particular, a joint compound that can be used without the need for tape.

Background

[0002] In construction of buildings, interior walls and/or ceilings are formed from prefabricated boards such as fibre cement sheeting, gypsum wallboards, plaster boards and the like. The prefabricated boards are typically fastened to wall frames and the joints between panels filled with a joint compound embedded with a tape layer.

Typically, when the base coat containing the tape layer is dry or set, a second layer of a joint compound is applied, followed by a third "finishing coat" which, once dry or set, can be finished in a conventional manner.

[0003] There are two general types of joint compound, setting type and drying type. Setting type joint compounds set through a chemical reaction. Setting type joint compounds are typically premixed and set within 1 to 4 hours of applying to the joint, however can be difficult to work and finish.

[0004] Drying type joint compounds set through drying, the evaporation of water from the mixture. Drying type compounds are typically supplied in powder form, requiring them to be mixed with water on site. Once mixed, drying type compounds must be used immediately on the joints as the mixture can set in a relatively short time. Having to mix the compound on site can be labour intensive, and the resulting mixture must be used quickly once mixed to avoid waste.

[0005] Current setting and drying compounds require the use of a tape layer in the joints to provide adequate strength and flexibility at the joint, as well as to minimise cracking of the joint compound during setting. The process of applying a tape layer to the wall can be time consuming and requires skill to ensure the tape is correctly positioned prior to the setting of the joint compound.

[0006] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

Summary

[0007] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0008] In a first aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising a filler, a binder and carbon fibres.

[0009] The filler may be a filler selected from the group comprising calcium carbonate (limestone), calcium sulphate dihydrate (gypsum), calcium sulphate hemihydrate (plaster of paris), calcium magnesium carbonate (dolomite), magnesium silicate (talc), and combinations thereof.

[0010] The binder may be a binder selected from the group comprising acrylic copolymer emulsions, polyvinyl acetate, polyvinyl alcohol, ethylene vinyl acetate copolymers, vinyl acrylic copolymers, styrene -butadiene polymers, polyacrylamides, other acrylic polymers, latex emulsions, caseins, and combinations thereof. [0011] The ratio of binder to filler is not particularly limited. For example the ratio may range from about 5: 1 to about 1: 1.

[0012] The ratio of carbon fibres to filler is not particularly limited. For example the ratio may range from about 1: 1000 to about 1:50. In some embodiments, the ratio of fibres to filler is from about 1:500 to about 1:300. The fibres may be from about 10 μιη in length to about 10 mm in length, for example from about 1 mm to about 5 mm.

[0013] The carbon fibres may, for example, be pitch based, polyacrylonitrile (PAN based), rayon (viscose) based or any combination thereof.

[0014] The joint compound may further comprise a fibre additive selected from the group comprising cellulose fibres, mineral fibres, synthetic organic fibres and synthetic inorganic fibres, or combinations thereof. The ratio of fibre additive to filler may range from about 1: 1 to about 1: 10.

[0015] The fibre additive may comprise cellulose fibres. The ratio of cellulose fibres to filler may range from about 1: 1 to about 1: 10.

[0016] The fibre additive may comprise polymer fibres. The ratio of polymer fibres to filler may range from about 1: 1000 to 1:50.

[0017] The joint compound may further comprise one or more additives such as water, defoamers, thickeners, gelling agents, pigments, surfactants, neutralising agents, coalescing agents, surfactants, wetting agents, non-levelling agents, biocides, fungicides and other known additives.

[0018] In a second aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising 5 to 50% by weight filler, 5 to 80% by weight binder, 0 to 30 % by weight additives, 0.001 to 10% by weight carbon fibres, and 0 to 20% by weight fibre additive. [0019] In a third aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising a filler, a binder and carbon nanotubes.

[0020] In a fourth aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising 5 to 40% by weight filler, 5 to 50% by weight binder, 0 to 30% by weight additives, 0.0001 to 1% by weight carbon nanotubes, and 0 to 20% by weight fibre additive.

[0021] In a fifth aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising 5 to 40% by weight filler, 30 to 50% by weight binder, 0.001 to 1% by weight carbon fibres, 0.001 to 1% by weight polymer fibres, and 0.01 to 10% by weight cellulose fibres.

[0022] In a sixth aspect, there is provided a joint compound for use on joints between adjacent wall panels, the joint compound comprising 5 to 40% by weight filler, 5 to 50% by weight binder, 0 to 30 % by weight additives, 0.001 to 1% by weight carbon fibres, and 0 to 20% by weight fibre additive.

Description of Embodiments

[0023] An embodiment of the invention will now be described, by way of example only, with reference to the following examples.

[0024] Examples 1 to 3 below show examples of formulations prepared utilising 3mm long carbon fibres and a cellulose fibre additive. Properties of the carbon fibres and paper fibres used in Examples 1 and 2 are shown in Tables 1 and 2, respectively. Single fibre diameter 7.0 to 10 μηι

Tensile strength 3.0 to 3.6 GPa

Tensile modulus 220 to 240 GPa

Carbon content >93%

Elongation percent 1.5%

Density 1.6 to 1.76 g/cm

Colour Black

Volume resistivity 1.5 x 10 ^"3 ohms/cm

Table 1: Carbon Fibre Properties

Diameter (ave) 20μιη

Specific gravity 1.1

Moisture content (ave) 3%

Oil absorption 3.71

Retention 325 mesh 28%

Table 2: Cellulose Fibre Properties

EXAMPLE 1

[0025] A tapeless joint compound was made in accordance with the formulation shown in Table 3.

Table 3: Formula F4-A1 EXAMPLE 2

A joint compound was prepared in accordance with the formulation shown

Table 4: Formula F4-A2 EXAMPLE 3

A joint compound was prepared in accordance with the formulation shown

Table 4: Formula F9-A STRENGTH TESTING

[0028] For a tapeless joint compound to be a viable alternative to current joint compounds utilising tape, it is important that joints formed with the tapeless compound are at least as strong as those using traditional joint compounds with tape. The above formulations were tested for strength and compared with industry standard for joints made with joint compounds and tape in the following manner.

[0029] A substrate is prepared joining two sheets of fibre cement sheet or plasterboard. The joint is treated with two coats of the joint compound and one coat of a topping compound. The prepared substrate is affixed to a frame with screws at the top left and right corners and chains attached to the bottom left and right corners suspending a wooden platform. 25 kg weights are added at 30 second intervals to the wooden platform until breaking point.

Table 6: Strength testing results [0030] As can be seen from Table 6 above, the tapeless joints formed with Formula F4-A1 and Formula F4-A2 matched and exceeded the industry standard joints using paper tape for strength.

[0031] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.