FP0072AUDescAsFiled.docx AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Container Liner for use in the Building and Other Industries The following statement is a full description of this invention, including the best method of performing it known to us: 1 FP0072AUDescAsFiled.docx Title: Container Liner for use in the Building and Other Industries Field of Invention [0001] The present invention primarily relates to the building and construction industry and other industries which make use of moist or wet mixtures. Background [0002] A number of industries, most notable the building and construction industry make use of moist or wet compositions which are applied to various surfaces. These include wet mixtures such as wet plaster, adhesive compounds, base coat compound, cornice adhesive, render adhesive and topping compound. When these compositions are used an amount of mixture is deposited into a container for a particular job. For example a plasterer may put an amount of cornice adhesive into a bucket to allow him to work putting up cornice in a room. [0003] The compositions may be ready to use as soon as they are deposited in the container or may need to be mixed or otherwise worked in the container before and/or during application depending on various factors such as pot time and the like. [0004] Cleanup of the containers is necessary either at the end of the job or throughout the job. [0005] As will be appreciated by those skilled in the art cleanup involves access to water or other solvents, however the use water and other solvents may not be environmentally desirable. For example cleanup with water often involves use of copious amounts. In addition, cleaning up is time-consuming. As will be appreciated on some sites, such as multi-storey sites access to water may not be easy or convenient. 2 FP0072AUDescAsFiled.docx [0006] A number of proposals have been put forward to prevent a mixture from sticking to a container. These include US patent application No. 2010/0200596 in the name of Wallace and European patent application No. EP 0864415 in the name of Hoechst Diafoil Company which provide thin films that can be peeled away. In addition, patent application No. WO 97/05035 in the name of Henkel Nederland BV discloses a disposable thin protective coating which can cover the inside and/or outside of a container. Further US patent application No. 2004/0134917 in the name of Carnegie discloses a disposable paint tray liner which is essentially a bag that can be secured to the paint tray and thrown away after use. [0007] Yet other examples include US patent No. 4, 122, 973 in the name of Ahern which relates to a disposable bucket liners with thin non-supportive walls made of polypropylene, polystyrene and vinyl, US patent No. 6, 260730 in the name of Fellman which discloses a rigid reusable liner for a paint can, Canadian patent application No. 263 7357 in the name of Molnar which discloses a reusable liner for a pain tray made of Silastic, US patent application No. 2011/005 2858 in the name of GMA industries which relates to a self sustaining tray made of silicon for use in surgical procedures and baking and US patent No. 7, 005, 613 in the name of Saint -Gobain Performance Plastics Corporation which relates to a silicone oven liner. [0008] While the above proposals generally relate to preventing substances from sticking to surfaces of containers they do not provide a robust reusable liner for a moist or wet mixture which allows cleanup with use of a minimal volume of cleaning fluid. [0009] The present inventors set out to provide a reusable container liner which addresses at least to some of the shortcomings discussed above. 3 FP0072AUDescAsFiled.docx [0010] The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. Summary [0011] In one aspect the present invention provides a removable liner for a container, said liner suitable for working viscous material such as wet or moist compositions and the like, said liner comprising: a) a deformable resilient body nestable within a container; b) a stick resistant surface which resists adhesion of the material to be worked; and c) means for positive engagement with the container such that when the material is worked in the liner, the liner is secured in position. [0012]The term "container" refers to any rigid container usually used for working and/or mixing materials such as a bucket, pail, drum, mixing bowl or the like. [0013] The term "viscous material" refers to material which resists flow such as thick wet or moist compositions including wet plaster, adhesive compounds including render adhesive and cornice adhesive, base coat compound and topping compound. [0014]The term "deformable" refers to the ability of the liner to easily bend without breaking. [0015] The term "resilient" refers to the ability of the liner to recoil or retract back into shape after being twisted or otherwise bent out of shape. [0016] The term "nestable" refers to the liner being of a shape so that a portion of it can be housed within the container. 4 FP0072AUDescAsFiIed.docx [0017] The term "stick resistant surface" refers to a surface which has a reduced tendency for other substances to stick to it. [0018] The term "material to be worked" refers to the viscous material it is intended to be dispensed and/or mixed in the liner. [0019] The term "means for positive engagement" refers to a means which engages by gripping, clamping or otherwise securing the liner to the container. Depending on the nature of the container which the liner is designed to be used with, the means for positive engagement may be a recess, channel, a female part or a protuberance, or male part. [0020] The present inventors had the surprising realization that a snug fitting liner or glove made of nonstick flexible material could reduce the amount of time and labour involved in cleaning buckets used for application of wet mixtures in the building industry and other industries. This includes saving time spent accessing water for cleaning. [0021] Preferably the liner conforms to the shape of the container and does not need any additional structural reinforcing. [0022] Preferably the means for positive engagement is of a flexible or resilient nature and is integral with the body. [0023] Preferably the body and means for positive engagement are made of the same material. 5 FP0072AUDescAsFiIed.docx [0024] Preferably the liner is made of an elastomer such as an organic elastomer including rubber or an inorganic elastomer. More preferably the liner is made of an inorganic synthetic elastomer. Even more preferably the liner is made from a silicone based elastomer such as silicone rubber. [0025] The invention also provides a method of reduced solvent usage in cleanup of a wet mixture, said method comprising providing: i) a liner and a suitable container said liner comprising: a deformable resilient body nestable within the container; a stick resistant surface which resists adhesion of the mixture and means for positive engagement with the container such that when the mixture is worked in the liner, the liner is secured in position; ii) inserting the liner into the container; iii) adding the mixture to the liner and using the desired amount of mixture for a job; iv) allowing the remaining mixture in the liner to dry and; v) removing the liner from the container and deforming the liner such that the dry mixture flakes or peels off the surface wherein cleaning of the liner involves use of less solvent than conventional cleaning. [0026] The term "solvent" refers to any cleaning liquid required and includes water. [0027] The term "using the desired amount of mixture for a job" refers to where once the mixture has been dispensed in the liner the required amount is used for a job such as plastering or the like. [0028] The invention also relates to a complementary bucket and liner combination. Specifically invention provides a container and liner combination for working viscous materials said combination comprising: i) a suitable container for housing a removable liner; and ii) a removable liner; wherein said liner comprises a deformable resilient body nestable within the container; a stick resistant surface which resists adhesion of 6 FP0072AUDescAsFiIed.docx the material being mixed and wherein the bucket or the liner comprises a means for positive engagement such that when the material is mixed in the liner, the liner is secured in position. [0029] The invention also relates to a method of manufacture of the liner comprising providing a suitable elastomeric material and moulding said elastomeric material into a suitable size and shape to form the liner. Detailed Description of Illustrative Embodiments of the Invention [0030] The invention will now be described with reference to the following non limiting illustrative drawings. [0031] Figure 1 is a front view of the bucket with a liner inserted and a partial cutaway showing the bucket and liner in longitudinal section. [0032] Liner 20 is suitable for use with a container in the form of bucket 40 as shown in Figure 1. Liner 20 is nested or housed within bucket 40. [0033] Bucket 40 is made of standard plastic material and has base 42 at one end and open top 43 at the other end joined by tapered wall 45. Base 42 is of smaller diameter than an open top 43. Base 42 joins wall 45 in a smooth curve 42a inside bucket 40. [0034] Open top 43 as an annular lip or rim 47 on outside 40a of bucket 40. Annular lip 47 comprises a thickened portion of wall 45. Reinforcing band 48 is an annular member on outside 40a of wall 42 just below rim 47 of bucket 40. Handle 49 is mounted on reinforcing band 48. 7 FP0072AUDescAsFiled.docx [0035] Liner 20 comprises a deformable resilient body 22 made of silicone rubber having non stick surface 25. Any suitable silicone rubber base may be used such as Xiameter* RBB-2400-70 base manufactured by Dow Corning or the appropriate NE series made by Dong Jue Fine Chemicals (Nanjing) Co. Ltd. [0036] Liner 20 is of uniform thickness and conforms glove like to the internal shape of bucket 40. Positive engagement means is provided in the form of locking rim 30 with flange 30a. Locking rim 30 forms an annular casing or channel which fits over annular lip 47 when liner 20 is inserted and rim 30 pressed onto lip 47. Other configurations of the engagement means are also contemplated. [0037] The thickening of wall 45 to form an annular rim 47 of bucket 40 facilitates positive engagement or mating between lip 47 and rim 30. This provides frictional grip and eliminates rotation of liner 20 when viscous substances are mixed with a mechanical device. In addition it prevents collapse of liner 20 within bucket 40. Liner 20 has an appropriate Shore value and flexibility which ensures conformity to the inner surface of bucket 40. Further, the radius of smooth curve 42a and corresponding curve on liner 20 facilitates easier extraction of hardened waste from the liner. [0038] Although in the embodiment illustrated the positive engagement means comprises a channel in the form of locking rim 30 and this engages with annular lip 47 of bucket 40, it will be appreciated that the female/male relationship may be reversed. It is contemplated that in some embodiments the liner may comprise a male member of or series of male members or protrusions which engage with complementary female member or series of members on the container. Example 1: initial production of the liner [0039] The liner is best suited to be manufactured using a mechanical technique such as pressurized vulcanizing for commercial viability. 8 FP0072AUDescAsFiIed.docx [0040] However, for the prototype, a compression mould was utilized to perform the invention. [0041] Firstly an outer enclosure was created by using structural form ply 18mm in thickness with dimensions are 530 mm x530 mm x380 mm high. [0042] To create an outer mould, an 18 litre bucket was positioned inside the outer enclosure. Concrete was placed between outer enclosure and outer mould to form a solid encasing to withstand the pressure expected during compression. [0043] The inner mould was formed using fiberglass. The inner mould was 6mm smaller in circumference and 3mm higher than the outer rim of the outer mould to allow formation of a liner with 3mm thickness on all surfaces as well as creating a 3mm thick top edge of liner which forms part of the locking rim of liner. [0044] This inner mould was filled with concrete to give weight to the mould plus strength to cope with compression. An 18 mm form ply circle was placed atop the inner mould to act as the outer form for top of liner as well as the meeting point for inner and outer moulds. A steel cross dimension 500 x 500 was bolted to the top side of the ply circle. This has 3 x 400mm long steel tubular sections welded vertically at precise locations at the outside of cross. These form inner sections to slide into outer tubular sections which are welded to a steel plate and attached to precise locations on the outer enclosure in line with inner tubular sections to create a slide which ensures the correct liner thickness is obtained around circumference of mould. These are greased for ease of sliding inner mould into outer mould. [0045] There was an 18mm form ply ring which encompasses the outer mould. This created an airtight join between outer mould and ply and acted as a base for a further 9 FP0072AUDescAsFiIed.docx 18mm form ply ring with 2mm x 2mm grooves formed at the top edge of ring to allow overflow silicone rubber to secrete the mould upon compression. This is fixed to above said ring to achieve the outer edge and underside of locking rim. [0046] The inner mould and outer mould were highly polished using Meguiar's mirror glaze number 8 maximum mold release wax, then, Mann ease release 200 spray solution was added to both moulds and brushed evenly over moulds and left to sit for 5 minutes. [0047] During this resting period the silicone rubber formula was mixed. This is achieved by adding 1.2 litres of part A base SRT-30 RTV2 shore A30 flexible pouring grade silicone rubber to 75ml of SRT-30 catalyst. SRT-30 RTV2 is manufactured by Dalchem Pty Ltd, Australia. This was mixed through well. [0048] A further addition of ease release 200 was sprayed onto both inner and outer moulds from a 12 inch distance. [0049] The aforementioned mixture is poured from a height of 2 metres creating a maximum stream width of 2-3 mm in diameter. Once poured, the inner mould device was inserted by way of inner tubular sections being placed inside outer tubular sections and this then slides to allow base of inner mould to reach silicone rubber mixture at base of outer mould. A hydraulic jack was then placed atop inner mould steel cross and below a purpose built press. The jack was then tensioned to force the inner mould into the silicone rubber mixture. This creates compression sufficient to send the mixture flowing to the outer extremities of the void between both moulds. The two moulds then reach the meeting point, and the mould is held in place via 8 x 50 mm screws which connect the ply of the outer mould to ply on inner mould at this meeting point. 10 FP0072AUDescAsFiled.docx [0050] Once this step has been taken, the jack tension is released. At this point there is a flow of silicone rubber through the 2 mm x 2 mm escape ways. [0051] The curing time in this method is between 3-4 hours. [0052] Once cured, the inner mould was released through a series of steps which culminate in using external tension the silicone rubber liner was then gently peeled away from the outer mould and the product now named BUCKET GLOVETM was revealed. Example 2: manufacture of the liner [0053] A suitable mould was produced to make the liner by vulcanization extrusion. Those skilled in the art of making silicone rubber objects will be familiar with the methods used to produce a mould and with the vulcanization extrusion process. [0054] The liner was made from a mixture comprising silicone rubber: 99.8 % in the form of NE- 5160 and vulcanizing agent: 0.15-0.2%. [0055]NE- 5160 is available from Dong Jue Fine Chemicals (Nanjing) Co. Ltd and has the following properties in sheet form under vulcanizing conditions of 1750 C for 5 minutes with vulcanizing agent Double 2,5 at 0.65% Density g/cm 3 1.18±0.05 Durometer Shore A 60±3 Tensile Strength MPa 7.0 Elongation at break %> 280 Permanent deformation at 10 break % 10 Tear strength kN/m2 18 11 FP0072AUDescAsFiled.docx [0056] The liner produced by this method is substantially of uniform thickness which is approximately 2 mm. Example 3: Use of the liner [0057] Liner 20 is seated into bucket 40 and locking rim 30 is engaged with annular lip 47 by pressing down around locking rim 30. [0058] The user who will commonly be a person skilled in the building industry places water and the mixable product into liner 20 and uses a manual or mechanical device to mix product. The viscous material is then used for its intended purpose. [0059] These products have a working life, so they inevitably go hard. Once the product either hardens or is no longer required for the task, the liner is removed from bucket and sat aside until the mixed product completely dries. [0060] A second liner is then placed within the bucket and working can continue as required. This can be repeated. [0061] Alternatively, a number of liners can be nested together within the bucket ready for sequential use. [0062] Once dry, the liner is shaken by hand and waste is placed in a receptacle. The liner is then wiped clean using a damp cloth or sponge if necessary. [0063] It will be seen from the above that the advantages of the invention include its re usable nature due to the extreme durability of the compound used to form the liner. The liner saves time for the user because of the efficiency created in terms of ease of use which includes minimal mess in relation to clean up, minimal water to clean the 12 FP0072AUDescAsFiled.docx product as opposed to current methods which require a conservative estimate of 40 litres per mix. Further the invention is cost effective, because of the simplicity and durability of the product. It is easily manufactured en masse. [0064] The fact that the invention conserves water means saving massive amounts of water on a global scale. The very nature of the methods currently used in these industries means copious amounts of water are required. The invention is ecologically responsible for all the reasons outlined above plus the fact that buckets are destroyed and are unable to be recycled and simply go to landfill, where this product will be reusable for long periods of time without replacement. Further the waste product would usually be washed into an entrapment system and need to be removed once full. The present invention allows the user to simply empty the dried residue into a receptacle. [0065] From the foregoing, it will be observed that numerous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiment illustrated herein is intended or should be inferred. The disclosure is intended to cover, by the appended claims, all such modifications as fall within the scope of the claims. [0066] Throughout this specification and the claims that follow, unless the context requires otherwise the words "comprise", "comprises", "comprising" will be understood to mean the inclusion of the stated integer, step or group of integers or steps but not the exclusion of any of other integer, step or group of integers or steps. 13