AU2015201932A1 - Jointing compound - Google Patents

Abstract

Ajointing compound for use as an all-purpose compound is disclosed. The compound can replace the need for separate and different base coat and topping compounds, or can be used as a base coat and/or as a final (finish) coat (e.g. where a plaster-based base compound has been 5 used). The jointing compound comprises filler material, a gelling/thickening agent, a water soluble or dispersible polymeric binder and a water-retaining agent. The compound is formulated such that the amount of water-retaining agent comprises less than 1% by weight of the compound. It has been observed that, by appropriately controlling (limiting) the amount of water-retaining agent, air entrainment during formulation of the compound can be reduced to a 0 level that does not impede workability and use of the compound as both a base coat and topping compound. The water-retaining agent may also function as a gelling and/or thickening agent in the compound in use. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA

Description

- 1 JOINTING COMPOUND TECHNICAL FIELD Ajointing compound for use with plasterboard and wallboard is disclosed. The compound finds particular, though not exclusive, application as an all-purpose compound for 5 use with plasterboard and wallboard to replace the separate, different base coat and topping compounds, and will be described in this context. The compound may also be used either as a base coat for a first and second coat, or as a third, final (finish) coat where a plaster-based or limestone-based base coat has been used for first and second coats. BACKGROUND 0 Plasterboard panels are used in construction to provide an internal lining for walls and ceilings. To provide for a smooth, paintable joint between adjacent panels, the panels are joined using, in order, a base compound, jointing tape to hide the joint and a topping compound to hide the base compound and tape. The base compound is applied in two stages, a first to secure the tape therein, and a second to cover the tape and provide a level surface. 5 The topping compound may be formulated to have a similar colour to the externally facing paper of the plasterboard, and is applied to provide a smooth, sandable finish and to better hide the joint once painted. Because the base compound is used together with the jointing tape, and because it also provides the underlying joint strength between the adjacent panels, it is formulated to -0 have moderate or high compressive strength, low shrinkage and good adhesion to the tape. In this regard, it can be formulated from calcium sulphate hemihydrate plaster to hydrate and set relatively quickly via a reaction with water. On the other hand, the topping compound requires good spread-ability (i.e. easily trowelled), high sand-ability (i.e. easily sanded), and a good (e.g. smooth) surface finish once applied and sanded. In this regard, it can be 25 formulated from a water-based polymeric binder. Thus, the base and topping compounds are formulated differently. Efforts have been made to develop all-purpose compounds that can perform the function of both base and topping compounds, with varying degrees of success. For example, AU 2005251974 discloses a jointing and surfacing compound that can perform both 30 functions. However, AU 2005251974 requires an anti-foaming agent to compensate for air entrainment in the compound during formulation. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -2 The above references to the background art do not constitute an admission that the art forms part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the application of the jointing compound as disclosed herein. 5 SUMMARY OF DISCLOSURE Disclosed herein is ajointing compound. The compound can be employed as an all purpose compound to replace the need for separate and different base coat and topping compounds. The compound can also be used as a base coat and/or as a final (finish) coat (e.g. where a plaster-based base compound has been used). 0 In accordance with the disclosure, thejointing compound is formulated such that the amount of water-retaining agent comprises less than 1% by weight of the compound. It has been observed that, by appropriately controlling (limiting) the amount of water-retaining agent, air entrainment during formulation of the compound can be reduced to a level that does not impede workability and use of the compound as both a base coat and topping compound. 5 In one embodiment, the water-retaining agent may also function as a gelling and/or thickening agent in the compound in use. In one embodiment, the water-retaining agent may comprise a cellulosic carbohydrate polymer. For example, the cellulosic carbohydrate polymer may comprise one or more of: hydroxy ethyl cellulose; hydroxy propyl methyl cellulose; or methyl cellulose. 20 In one embodiment, the weight % proportion of the cellulosic carbohydrate polymer in the compound can be in the range of 0.2 to 0.6 %. For example, hydroxy ethyl cellulose and hydroxy propyl methyl cellulose may together be present at about 0.4% by weight of the compound, etc. In addition to the cellulosic carbohydrate polymer functioning as both a water 25 retaining agent and gelling/thickening agent, the compound may comprise a clay-based gelling/thickening agent such as a clay mineral having high water absorption. For example, the clay mineral may comprise a hydrous aluminium and/or magnesium silicate. In one embodiment, the clay may comprise one or more of: attapulgite {(Mg,Al) 2 Si 4 01o(OH) 4(H 2 0)}; sepiolite {Mg 4 Si 6 Oi 5

(OH)

2 6H 2 0}; or montmorillonite. 30 Typically the clay comprises attapulgite at a weight % proportion of about 1.

5 %. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -3 The compound also comprises a water soluble or dispersible polymeric binder. For example, the compound may comprise one or more of polyvinyl alcohol; a polymer emulsion of: ethylene vinyl acetate; polyvinyl acetate; acrylic; polyacrylamide; styrene acrylic; styrene butadiene rubber. 5 In one embodiment, the weight % proportion of the polyvinyl alcohol in the compound can be in the range 0.2 - 0.7%. The polyvinyl alcohol may be provided as a dry powder together with filler material for the compound as well as the gelling/thickening agent and water-retaining agent. In one embodiment, the polymer emulsion is ethylene vinyl acetate. The ethylene 0 vinyl acetate emulsion may be provided at a weight % range of about 3 - 5%. The emulsion may be supplied as part of an aqueous solution to be mixed with the dry powder to form the jointing compound. The compound comprises one or more filler materials (e.g. at least two mineral fillers). For example, a bulk of the filler material can comprise a metal carbonate-based 5 material such as calcium carbonate or dolomite. The weight % proportion of the calcium carbonate in the compound can be in the range of about 40-55%. The calcium carbonate can be provided with a desirable particle size (or distribution) so as to provide a smooth, grit-free consistency to the compound once formulated. For example, a particle size of around 20 microns. 0 Other mineral fillers may be used in combination with calcium carbonate such as: phyllosilicate-based fillers (i.e. one or more hydrated magnesium silicates, such as talc, mica, vermiculite, etc); dolomite, silica, quartz, gypsum, barium sulphate, magnesium carbonate and the like. The compound can also comprise talc or mica. Talc and mica can provide additional 25 body to the calcium carbonate, as well as providing a smooth surface, improving joint life, and sand-ability and paint-ability (i.e. increased slip) of the cured compound. The weight % proportion of talc in the compound can be in the range of about 3 -10%. The compound can also comprise lightweight filler such as perlite microspheres. These can improve spread-ability, sand-ability and paint-ability of the cured compound. The 30 weight % range of the perlite microspheres in the compound can be in the range of about 3 10%. 6396528_1 (GHMatters) P96731 .AU.1 SAMVANTHA -4 A biocide can be added to the compound for the control of bacteria and fungi, to improve shelf life as well as the in situ life of the compound. The biocide may comprise, for example, 2[(hydroxymethyl) amino] ethanol, 5-chloro-2-methyl-2H-isothiazol-3 -one, di methyl-2H-isothiazol-3 -one (CAS-No. 2682-20-4) (CMIT/MIT) and/or 2-methyl 1,2 5 benzisothiazolin-3-one e.g. in the range of about 0.1 - 0.2% by weight of the compound. Other suitable aqueous-based biocides can be employed. Sorbitol and/or mannitol can also be added to the compound when, for example, the compound is employed with plasterboard. Plasterboard may typically contain boric acid or other borate, and the sorbitol and/or mannitol can be added to the compound in an amount 0 such as to counteract the reaction of polyvinyl alcohol with borate. The weight % range of the sorbitol in the compound can be in the range of about 0.1-0.

3 %. The compound may further comprise a dispersant, such as a hydrophobic copolymer carboxylate polyelectrolyte (e.g. provided at weight % in the compound of about 0.05%. 5 Also disclosed herein is a jointing compound for use with plasterboard or wallboard. The compound comprises (at a weight % proportion in the compound): 45-75% filler material; 1- 2 % of a clay-based gelling/thickening agent; 3-5% of a water soluble or dispersible polymeric binder; less than 1% by weight of the compound of a cellulosic carbohydrate polymer; and the balance water. 0 The compound may otherwise be defined as set forth above. Also disclosed herein is a method of formulating ajointing compound as set forth above. Such a method can, for example, be deployed on site. The method comprises dry mixing the filler material, gelling/thickening agent and 25 water-retaining agent. This may be performed offsite (e.g. at a manufacturing facility). The dry mix may further comprise a powdered form of a polymeric binder (e.g. PVA powder), sorbitol and a dispersant. This dry mixture can then be transferred into an aqueous solution that comprises therein the polymeric binder (e.g. an EVA emulsion), and the resultant dispersion can then be 30 mixed. The polymeric binder may be premixed in the aqueous solution as an emulsion. The aqueous solution may further comprise a biocide. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -5 The mixing of the dry mix with the aqueous solution may be performed offsite (e.g. at the manufacturing facility), or it may be performed onsite by an end user. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS In the following detailed description, the illustrative embodiments described are not 5 intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter disclosed herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure. 0 A compound according to the present disclosure finds particular application as a so called all-purpose compound, replacing the base coat and topping compound in a typical plasterboard/wallboard joint. In other words, the one-and-same jointing compound is able to provide underlying joint strength between the adjacent panels, and has low shrinkage and good tape adhesion to the tape. At the same time, it has good spread-ability, high sand-ability 5 and a smooth surface finish once applied and sanded. Example 1 - Formulation for Jointing Compound Ajointing compound formulation comprising three types of fillers (two mineral fillers and one inert, lightweight filler), a gelling clay, cellulosic (carbohydrate polymer) water retainers/thickeners ("cellulosics"), and two water soluble/dispersible polymeric -0 binders/thickeners was prepared. The amount of cellulosic (carbohydrate polymer) water-retainers/thickeners was restricted to less than 1% by weight of the compound. They may be limited even further to be less than 0.6 wt. % - such as in the range 0.2-0.6%. It has been observed that, by limiting the amount of such water-retaining agents, air entrainment during formulation/mixing of the 25 compound was able to be reduced to a level that does not impede workability and use of the compound as both a base coat and a topping compound. In other words, the jointing compound did not require the addition of anti-foaming agents or the like. In addition to the air retention properties, which are not desirable for jointing, the higher the level of cellulosics (e.g. >0.6 wt. %), the stickier the compound becomes (i.e. 30 becoming harder to trowel, sticking to the jointing tools, etc). 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -6 The preferred formulation comprises an appropriate proportion/combination of the fillers CaCO 3 , talc and perlite microspheres; clay - attapulgite (palygel); cellulosics hydroxy ethyl cellulose (HEC) and hydroxy propyl methyl cellulose (HPMC); and polymeric binders - polyvinyl alcohol (PVA) and ethylene vinyl acetate (EVA) emulsion. 5 The cellulosics - HEC (at about 0.3 wt. %) and HPMC (at about 0.1 wt. %), or approximately 0.4 wt. % in total, were able to retain sufficient water in the compound, as well as to provide a sufficient amount of thickening, to facilitate a smooth and easy trowelling of the compound with the jointing tools. The CaCO 3 (40-55 wt. %) provided body/bulk to the cured compound. The calcium 0 carbonate grade was 60/16 at a particle size of around 20 microns and so provided a smooth, grit-free consistency to the compound once formulated and cured. The talc in the range of 3-10% (e.g. hydrated magnesium silicate at -7 wt. %) provided additional body to the calcium carbonate, as well as providing a smooth surface, improved joint life, sand-ability and paint-ability (i.e. increased slip) of the cured compound. 5 The perlite microspheres (3-10 wt. %) reduced the density (weight) of the compound and thus increased its ease of handling. The perlite also improved the rheology, surface, sand-ability and paint-ability of the cured compound. The attapulgite provided an additional thickening function (i.e. reducing the need for an additional amount of cellulosic agents) and thus also helped to reduce compound -0 stickiness and air entrainment. The polyvinyl alcohol (PVA) provided both a binding and thickening function (i.e. again reducing the need for an additional amount of cellulosic agents) and thus again helped to reduce compound stickiness and air entrainment. In addition to PVA, the formulation also comprised the binder ethylene vinyl acetate 25 emulsion (EVA) in the range of 3-5 wt. %. The EVA helped to bind together (i.e. during curing) all of the components, as well as to promote good adhesion properties of the compound to plasterboard/wallboard substrates. A biocide was also added to the compound to control bacterial and fungal growth therein, to improve shelf life as well as in situ life of the compound. The biocide added was 30 2[(hydroxymethyl) amino] ethanol (around 0. 1-0.2wt. %) to the aqueous solution for 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -7 formulation. Other suitable aqueous-based biocides to be used included e.g. Kathon LX 1.5, Acticide HIHB, Acticide CBM and/or Bioban 551 S. Sorbitol or mannitol (around 0.1-0.2 wt. %) was also added to the compound, being an amount to counteract the presence of boric acid (in the form of metal borate) in 5 plasterboard. Otherwise, the metal borate reacts with and coagulates the polyvinyl alcohol. A dispersant such as a hydrophobic copolymer carboxylate polyelectrolyte (about 0.05 wt. %.) was added to help disperse all of the components evenly throughout the compound during formulation. A preferred jointing compound had the following formulation: All-Purpose Compound Formulation: Talc - Off White Perlite Microspheres ~ Hydroxy Ethyl Cellulose ~-0. 3 Hydroxy Propyl Methyl Cellulose ~-0. 1 Polyvinyl Alcohol ~-0. 5 Sorbitol ~.0 .2 Di spersant ~-0.05 Water ~34 EVA Emulsion ~4 Biocide ~-0. 1 Total 100 6396528_1 (GHMatters) P96731.AU.1 SAMVANTHA Example 2 - Formulation Methodology Calcium carbonate and talc were first weighed to an accuracy of ± 2%. The other raw materials were weighed to an accuracy of ± 1%. The materials were sieved (as required) to remove grit and lumps. 5 The dry powders (calcium carbonate, talc, perlite, attapulgite, PVA, HEC, HPMC, sorbitol and dispersant in the table above) were then added to a ribbon blender. A ribbon blender was employed as it provided the requisite uniformity to the mix, with minimal dusting as well as minimal damage to the dry components. The dry powders were mixed for 10 minutes. 0 Instead of a ribbon blender, a paddle mixer or air-jet blender was able to be employed, with an air jet blender mixing more rapidly. The wet mixture (water, EVA emulsion and biocide in the table above) was prepared as follows. 700 litres of water, 85 litres of EVA emulsion and 2.4 litres of biocide were added to a wet blender and stirred. 5 The mixed dry blend was then transferred to the wet mix in the wet blender, and the wet and dry materials were mixed for 15 minutes to form a smooth consistency paste. The viscosity of the resultant formulation was tested. If required, additional water was added to reduce the viscosity and the paste was remixed for a further 5 minutes. When the viscosity was satisfactory (i.e. approximately 400 B.U.), the product was transferred to a 20 storage tank, ready for packaging. Whilst the mixing of the dry mix with the aqueous solution is usually performed at the manufacturing facility (i.e. to supply a packaged, sealed and ready-to-use compound), the powder and solution may be supplied separately, and mixed/formulated onsite by an end user (e.g. plasterer). In other forms, the powder alone may be supplied, and mixed/formulated 25 with water, for example, onsite by an end user (e.g. plasterer). Example 3 - Comparative Analysis A comparative analysis of the "Present (All-Purpose) Formulation" from Example 1 was made against two known types of all-purpose jointing compound, as follows: 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA -9 Joint Compound Regular All- Lightweight All- Present (All (JC) Purpose JC Purpose JC Purpose) Formulation JC Tests Units Viscosity @ 25'C BU 460 430 430 Density, wet g/cc 1.8 1.3 1.2 Rheology G,F,P Good Good Good Water Content % 29.0 36.5 38.0 Trowel-ability VG, G,F,P Good Good Very Good PH PH 9.3 9.5 9.0 Water retention VG,G,F,P Good Very Good Very Good Shrinkage, ring @ 23 C 50% RH % 17.5 16.3 12.6 Tape Adhesion 230 C, Paper tape % 85 80 100 Tape Adhesion 40 0 C, Paper tape % 98 93 100 Sand-ability 230 C cc 0.9 1.26 1.34 Sand-ability 40 0 C cc 0.55 1.01 0.96 Tape Edge Cracking @ 40 0 C % 0 5 0 Check Cracking @ 40 0 C 0-10 0 0 0 Coverage VG,G,F,P Fair Good Very Good From these test results, it can be seen that the Present (All-Purpose) Formulation compares favourably with existing jointing compound formulations in all respects. Whilst a number of specific compound embodiments have been described, it should 5 be appreciated that the compound may be embodied in other forms. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA - 10 In the claims which follow and in the preceding summary except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", that is, various features may be associated with further features in various embodiments. 5 Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA

Claims (32)

1. Ajointing compound for use with plasterboard or wallboard, the compound comprising: - filler material; 5 - gelling/thickening agent; - water soluble or dispersible polymeric binder; - water-retaining agent that comprises less than 1% by weight of the compound.

2. A compound as claimed in claim 1, wherein the water-retaining agent is also the gelling/thickening agent. 0

3. A compound as claimed in claim 2, wherein the water-retaining agent and gelling/thickening agent comprises a cellulosic carbohydrate polymer.

4. A compound as claimed in claim 3, wherein the cellulosic carbohydrate polymer comprises one or more of: hydroxy ethyl cellulose; hydroxy propyl methyl cellulose; or methyl cellulose.

5 5. A compound as claimed in claim 3 or 4, wherein the weight % proportion of the cellulosic carbohydrate polymer in the compound is present in the range of about 0.2-0.6%.

6. A compound as claimed in claim 5, wherein the cellulosic carbohydrate polymer comprises hydroxy ethyl cellulose and hydroxy propyl methyl cellulose.

7. A compound as claimed in any one of claims 3 to 6, wherein, in addition to the 0 cellulosic carbohydrate polymer, the gelling/thickening agent comprises a clay mineral having high water absorption.

8. A compound as claimed in claim 7, wherein the clay comprises a hydrous aluminium and/or magnesium silicate.

9. A compound as claimed in claim 8, wherein the clay comprises one or more of: .5 attapulgite { (Mg,Al) 2 Si 4 Oo(OH) 4(H 2 0)}; sepiolite {Mg 4 Si 6 Oi 5 (OH) 2 6H 2 0}; or montmorillonite. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA - 12

10. A compound as claimed in claim 9, wherein the clay comprises attapulgite at a weight % proportion of about 1.5%.

11. A compound as claimed in any one of the preceding claims, wherein the water soluble or dispersible polymeric binder comprises one or more of: 5 polyvinyl alcohol; a polymer emulsion of: ethylene vinyl acetate; polyvinyl acetate; acrylic; polyacrylamide; styrene acrylic; styrene butadiene rubber.

12. A compound as claimed in claim 11, wherein the weight % proportion of the water soluble or dispersible polymeric binder is in the range of about 3 - 5%. 0

13. A compound as claimed in claim 11 or 12, wherein the polyvinyl alcohol is provided as a powder together with the filler material, gelling/thickening agent and water-retaining agent; and wherein the polymer emulsion is supplied as part of an aqueous solution to be mixed with the powder to form the jointing compound.

14. A compound as claimed in any one of the preceding claims, wherein the filler 5 material comprises at least two mineral fillers.

15. A compound as claimed in claim 14, wherein the filler material comprises: - a metal carbonate-based material such as calcium carbonate; - a filler to improve slip/sand-ability such as talc or mica; - a lightweight filler such as perlite microspheres. 0

16. A compound as claimed in claim 15, wherein the weight % proportion of the calcium carbonate in the compound is in the range of about 4 0- 5 5 %; the weight % proportion of the talc in the compound is about 3-10%; and the weight % range of the perlite microspheres in the compound is about 3 -10%.

17. A compound as claimed in any one of the preceding claims, further comprising a 5 biocide for control of bacteria and fungi.

18. A compound as claimed in claim 17, wherein the biocide comprises 2[(hydroxymethyl) amino] ethanol, 5 -chloro-2-methyl-2H-i sothiazol -3-one, di-methyl-2H 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA - 13 isothiazol-3-one (CAS-No. 2682-20-4) (CMIT/MIT) and/or 2-methyl 1,2 benzisothiazolin-3 -one present in water in a range of about 0.1 - 0.2% by weight of the compound.

19. A compound as claimed in any one of the preceding claims, further comprising sorbitol and/or mannitol in an amount to counteract the presence of boric acid in use of the 5 compound with plasterboard material.

20. A compound as claimed in claim 19, wherein the weight % range of the sorbitol in the compound is about 0.1-0. 30 %.

21. A compound as claimed in any one of the preceding claims, further comprising a dispersant. 0

22. A compound as claimed in claim 21, wherein the dispersant comprises a hydrophobic copolymer carboxylate polyelectrolyte provided at a weight % proportion in the compound of about 0.0 5 %.

23. Ajointing compound for use with plasterboard or wallboard, the compound comprising, at a weight % proportion in the compound: 5 - 45-75% filler material; - 1-2% of a clay-based gelling/thickening agent; - 3-5% of a water soluble or dispersible polymeric binder; - less than 1% of a cellulosic carbohydrate polymer; - balance water. .0

24. A compound as claimed in claim 23, wherein the cellulosic carbohydrate polymer comprises hydroxy ethyl cellulose present and hydroxy propyl methyl cellulose present in the range of about 0.2-0.6 weight %.

25. A compound as claimed in claim 23 or 24, wherein the filler material comprises calcium carbonate in the range of about 4-55 wt.% having a diameter of about 20 microns; talc .5 in the range of about 3-10 weight %; and perlite microspheres in the range of about 3-10 weight % having a diameter of about 40 microns. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA - 14

26. A compound as claimed in any one of claims 23 to 25, wherein the polymeric binder comprises polyvinyl alcohol powder and ethylene vinyl acetate-in-water emulsion in the range of about 3-5 weight %.

27. A compound as claimed in any one of claims 23 to 26, wherein the clay-based 5 gelling/thickening agent comprises attapulgite at about 1.5 weight %.

28. A compound as claimed in any one of claims 23 to 27, which is otherwise as defined in any one of claims I to 22.

29. A method of formulating for use a jointing compound as claimed in any one of the preceding claims, the method comprising: 0 dry mixing the filler material, gelling/thickening agent and water-retaining agent; and transferring this dry mixture into an aqueous solution that comprises therein the polymeric binder, and then mixing the resultant dispersion.

30. A method as claimed in claim 29 wherein the polymeric binder is present in the aqueous solution as an emulsion. 5

31. A method as claimed in claim 29 or 30 wherein the dry mix further comprises a powdered form of a polymeric binder, sorbitol and a dispersant, and the aqueous solution further comprises a biocide.

32. A method as claimed in any one of claims 29 to 31 wherein the dry mix and the aqueous solution are provided separately for a user to formulate in situ. 6396528_1 (GHMatters) P96731.AU.1 SAMANTHA