ZA200504916B

ZA200504916B - Method of produing a hydraulic binder or thermoplastic containing product

Info

Publication number: ZA200504916B
Application number: ZA200504916A
Authority: ZA
Inventors: Michael W Symons
Original assignee: Tower Technology Pty Ltd
Priority date: 2002-08-15
Filing date: 2005-06-15
Publication date: 2006-08-30

Description

Wa 2004/016680 PCT/7Z.A2003/000109

METHOD OF PRODUCING A HYDRAULIC BINDER. OR THERMOPLASTIC CONTAINING ‘ PRODUCT

IBACKGROUND OF THE INVENTION

“This invention relates to a method of producing a product from a flexible open cell polymeric foam element and a hydraulic binder slurry, and to the product so made. The product may be for example a panel or a board or the like for use in the buildi ng industry.

Portland cement based building boards are well known. They are generally made from cement bound particle board or the like, i.e they contain lignoce Hulosic particles or fibres. These boards however suffer from the disadvantage that the lignocellulosic particles or fibres have a propensity go swell when water wetted and can interfere with the cur-e of the Portland cement. In addition, the smanufacture of the boards generally includes autoclaving, which is energy intensive. ther types of hydraulic binder based building boards include those that contain expanded minerals such as vermiculite. The method of manufacture of such boards generally involves the se of pressure and temperature in a sophisticated produsction plant.

Another type of known boards are gypsum building boards which generally include the use of goaper liners. “Thus, while many types of hydraulic binder based buildin g boards are known, they generally suffer . From one or other disadvantage. There is thus a need for a new type of hydraulic binder based

Product.

WVO 2004/016680 PCT/ZA2003/000109

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided a meethod of producing a product from: (a) aflexible open cell polymeric foam element; and (b) abinder selected from: (i) an hydraulic binder slurry; or (i) ~~ amixture of a pozzolan and either lime or Portland cementin the form of a slurry; (ii) a synthetic geopolymer precursor slurry; or (iv) athermoplastic material in liquid form; which includes the steps of: (1) introducing the binder into the open cells of the foa m element by either: (i) compressing the foam element to exclude air from the open cells and then releasing the compression with the foam element in contact with the binder so that the binder penetrates and becomes corwtained in the open cells of the foam element as it regains its shape; or (i) impregnating the binder into the foam element under pressure so that the binder penetrates and becomes containe d in the open cells of the foam - element; and (2) allowing the binder to set or harden and dry to form the product.

In one embodiment, in step (1), the foam element is submergead in the hydraulic binder slurry, and while submerged, the foam element is compressed to exclumde air from the open cells. The compression is then released so that the slurry penetrates amd becomes contained in the open cells. In a second embodiment of the invention, in step (1), the hydraulic binder slurry is applied to a surface of the foam element prior to the foam element being compressed to exclude air from the open cells. In a third embodiment, in step (1), the hydraulic bin der in dry powder form is placed on . the foam element, which hydraulic binder is slurried with water-, whereafter the foam element with the hydraulic binder sluny thereon is compressed to exclude air from the open cells.

In a fourth embodiment of the invention, in step (1), the foam element is compressed to exclude air from the open cells, and while compressed or as the compression is released, a hydraulic binder slurry is applied to a surface of the foam element. As the compression is released and the foam . element regains its shape, the slurry penetrates and becomes contained in the open cells. ) This step may be repeated.

The compression of the foam element in steep (1) is carried out by passing the foam element between a first roller and a surface, for exarrsple a second roller. The hydraulic binder slurry is preferably applied to a surface of the foam element directly by at least one of the first and second rollers.

This may be achieved by providing the or each roller with a perforated surface for contacting a surface of the foam element and a hydraulic binder slurry feed arrangement for feeding the hydraulic binder slurry to the perforated surface of the or each roller for application to a surface of the foam element.

In a fifth embodiment of the method of the inwention the binder is fed under pressure directly by one of the perforated rollers the binder penetrating the open cells of the foam element from one side forcing the air out of the foam element from the opposite side without the foam being compressed. Optionally this procedure may be repeated from the other side of the foam element as it is wound around a perforated roller revolving in the opposite direction to the first one and again without need of compression.

It has also been found that thermoplastic materials can be used instead of hydraulic binders in the method of the invention. Thus, the method of the invention as described above, in particular that described in the fourth and fifth embodiments of the invention, included producing a product from: : (b) a thermoplastic material

W 0 2004/016680 PCT/ZA2003/000109

Fhe thermoplastic material is preferably a thermoplastic composition selected from the group consisting of polystyrene, polyethylene, polypropylene, poly vinyl chloride, polyvinyl acetal, A.B.S, bitumen, and refinery bi-product, or any compatible combination, mixture or blend thereof.

Im particular, the thermoplastic composition is a molten thermoplastic composition.

According to a second aspect of the invention there is providead a product comprising an open cell polymeric foam element containing a set binder as described above in the open cells. The product iss preferably made by the method described above.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 is a schematic diagram of an embodiment of the method of the invention.

Figure 2 is a schematic diagram of further embodiments of the method of the invention.

Figure 3 is a schematic diagram of continuous, optic nally simultaneous, pressure injection as used in the fourth embodiment of the method of the invention.

Figure 4 is a schematic diagram of continuous, optio nally sequential, pressure injection as used in the fifth embodiment of the method o-f the invention.

DESCRIPTION OF EMBODIMENTS

T he first aspect of the invention is a method of producing a product from a flexible open cell polymeric foam element and a binder.

T he first component is thus a flexible open cell polymeric foarm element.

T he preferred flexible open cell polymeric foam element is nade from a polyurethane foam having a density in the range of from 6 kg/m? to 40 kg/m3, more preferably from 7 kg/m3 to 20 kg/m3 : iriclusive more preferably from 7 to 12kgs/m®. A particularly suitable flexible open cell polyurethane feoam is one based on the combination of a toluene diisocyanate with a polyol, water, methylene chloride as a blowing agent, stannous octoate as a catalyst, <and a surfactant which determines the cell size. Toluene diisocyanate is produced as two isomers, viz. 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI) and is commercially available as: ) greater than or equal to 99.5% 2,4-T Di; 80% 2,4-TDI and 20% 2,6-TDI which is the most commonly used product and is referred to hereinafter as TDI (80:20); 65% 2,4-TDl and 35% 2,6-TDI; and “crude” TDI with an unidentified isorner ratio.

An example of a composition for use in making a flexible open cell polyurethane foam is as follows: 80 parts TDI Toluene di-isocyanate and 20 parts MDI diphenylmethanediisocyanate

TDI (80:20) 578.7

Durapol 3000 (a polyol) 675

Water 46

Silicone surfactant (Niax L/580) 19.6 33 LV (catalyst) 19

Glycerine (crosslinker) 3.7

Methylene chloride (blowing agent) 166

Stannous octoate (catalyst) 2.1

All parts by weight

The result is a TDI flexible open cell medium hard polyurethane foam with a density of 10 kg/m3.

Other suitable polymeric foams include polyester foams, polyether foams, polyurethane polyester hybrid foams, and the like.

It is important that the polymeric Foam element has a good “memory” so that after it has been ) compressed, when the compression is released, the foam element returns to substantially its original dimensions so that the binder can fill the open cells.

i lt is also important that the polymeric foam elemeznt has a suitable hardness as it is required to act as a carrier for the binder and act to as a re-inforc-er therefor. : Itis preferable that the polymeric foam cell size is not too small so that the surface area of the foam is not too great. A cell size in the range 1 to 5 .mm diameter is preferred giving a composite of ] excellent strength at low densities.

As the polymeric foam element is flexible, the element may be post formed into a desired shape before the binder hardens. The shaping of the p olymeric foam element containing the binder may take place in a mould or maybe formed between &he platens of a press or the like.

Alternatively, the polymeric foam element may be shaped before it comes into contact with the binder. For example the polymeric foam element may be produced in a block and then cut to a desired shape, e.g for the production of a fielded and planed door core, a shaped roof tile, or a board with textured surfaces, before the binder is introduced, and which shape is maintained by the “memory” of the foam, after the binder has been introduced.

The second component is a choice of inorganic haydraulic binders as slurries in water binder.

The hydraulic binder is preferably selected from %he group consisting of Portland cement, the alpha and beta hemi-hydrates of calcium sulphate, a calcium aluminate cement, magnesium oxychloride, and magnesium oxysulphate.

The hydraulic binder may be a Portland cement, preferably a rapid hardening Portland cement with a particle size of from 475 m?/kg or finer. The Porfland cement may be mixed with up to 15% by weight of an undensified silica fume with a particle size of about 20000 m?kg.

When the hydraulic binder is the alpha or beta hemi-hydrate of calcium sulphate, it is preferably the : beta-hemi hydrate of calcium sulphate, which iss preferably finely ground, having a particle size of 300 which may be either synthetic or natural. Thuis product is also referred to as gypsum.

When the hydraulic binder is Porlamd cement, the hydraulic binder slurry preferably contains 35 to 55 parts by weight of water to 100 parts by weight of the Portland cement. When the hydraulic binder is the beta hemi-hydrate of Calcium sulphate, the hydraulic binder slurry preferably contains ) from 55 to 130 parts by weight of water to 100 parts by weight of the binder.

The hydraulic binder slurry may incl ude various optional additives as follows: 1 a polyvinyl alcohol as an aumxiliary binder, introduced in the water. A suitable example is

Mowiol 8/88 by Clariant. 2 An acrylic emulsion a methacrylate or a polyvinyl acetate, added in the water, which increases water resistance, tsoughness and flexural strength. An example is Acrylic Polymer

E330 by Rohm & Haas. 3 A super plasticiser in order to reduce the water to binder ratio at a given viscosity. A suitable example is Melment F10 by Hoechst, which is a melamine formaldehyde condensate. 4 A hydrophobic agent such ass a silicone masonry water repellant. A suitable example is BS 94 by Wacker which is an a_nhydrous silicone based on hydrogen polysiloxane. When the hydraulic binder is gypsum, iit is preferably added to the gypsum in an amount of about 0.3% by weight. Another suitable hydrophobic agent, particularly for use with Portland cement is

BS 1307 by Wacker which iss a silicone resin siloxane mixture which is used in an amount of about 0.4% by weight.

A hydrate precursor or hydreogel such as Borax or an alkali silicate respectively to improve performance in fire. 6 Reinforcing fibres of a maxinum length of 1mm such as cellulose or polyamide.

The inorganic binder may also be a combination of a pozzolan and lime or Portiand cement in a water slurry.

Suitable pozzolans include silica furme with a particle size in the range of from 5 000 to 220 000 m2kg, ground granulated blast furnace slag with a particle size in the range of from 300 to 2 000 ) mz/kg, and fly ash with a particle size in the range of from 300 to 2 000 m2/kg, or a mixture «of any two or more thereof.

As stated above, the pozzolan must be combined with either lime or Portland cement as the source of calcium hydroxide. Generally there is used 95 to 75 parts by weight of the pozzolan to & to 25 parts by weight of the lime or Portland cement.

The inorganic binder may also be a synthetic goepolymer precursor in water slurry. An example of a suitable geopolymer precursor is a blend of a metal oxide such as aluminium oxmde or magnesium oxide with a calcium silicate, in the form of Wollastonite, the blend having a pearticle size of 300 mesh or finer. In this case, the geopolymer precursor is impregnated into the foam element in the form of a water slumy. Thereafter the foam element containing the slurry is dried and then post-impregnated with a compound selected from the group consisting of ammonium phosphate, phosphoric acid, or a solution of aluminium phosphate and phosphoric acid, fo fo rm the geopolymer, viz. a magnesium ammonium phosphate hexahydrate.

The retention of the hydraulic binder slurry in foam elements where the cell sizes are rel atively large is a function of apparent visco sity or rheology. In order to ensure a suitable rheology, silica - fume may be added to Portland cement, or suitable organic thickeners may be added to any~ of the hydraulic binders. Acrylic based thickener compounds are preferred.

The first step of the method of the in vention is to introduce the hydraulic binder slurry into the open cells of the foam element by compressing the foam element to exclude air from the open ce lis and then releasing the compression with the foam element in contact with the hydraulic binder slay so that the slurry penetrates and becomes contained in the open cells.

In one embodiment of the inveantion, the foam element is submerged in the hydraulic binder slurry” and while submerged, the foann element is compressed, whereafter the compression is released som that the slurry penetrates and becomes contained in the open cells.

In the compression stage, the air in the open cells of the foam element is forced out of the opera cells. Thereafter, when the compression is released, the foam element, having a memory, returnss substantially to its original size= and shape, i.e the open cells open up again, allowing the hydraulic binder to penetrate and be con.tained in the open cells.

It is not necessary to exclude all of the air from the open cells of the foam element. Depending ora the nature of the product to be- manufactured, the amount of air to be excluded from the open cells can be determined.

The compression of the foarnn element is preferably carried out by passing the foam elemen® between a first roller and a surface, for example a second roller.

This first embodiment of the inwention is illustrated in Figure 1.

Referring to Figure 1, a flexible open cell polymeric foam element 10, which may be either a continuous sheet, or a discrete element, which may be flat or shaped, is transported on a conveyowr 12 into a slurry tank 14 containing an agitator 16. The slurry tank 14 is filled with a hydraulic bindewr slurry. The foam element 10 is passed between two rollers 18, 20 between which the foam element 10 is compressed. On exiting the rollers 18, 20 the foam element 10 regains its original size and shape and the hydraulic binder slurry penetrates and becomes contained in the open cells of the foam element 10. The foam element 10 now containing the hydraulic binder slurry passes out of the slurry tank 14 and is passed between two rollers 22, 24. The foam element 10 containing the hydraulic binder slurry is compressed between the rollers 22, 24 to extract some of the hydraulic binder slurry therefrom. This hydraulic binder slurry is then fed back to the slurry tank< } 14.

The foam element 1 Q now containing the desired content of hydraulic binder slurry is passed onto a conveyor 26 and then through a drier 28 in which the hydraulic binder hyadrates and sets and is dried. The final product 30 then exits the drier 28.

In an alternative, before the hydraulic binder in the hydraulic binder slurry Bhydrates and sets, the foam element contamining the hydraulic binder slury may be formed into & desired shape. For example, the foam e=lement containing the hydraulic binder slurry may be pl=xced onto a mould and then conformed to a shape such as a corrugated sheet or U-section or the likze.

In a second embodimment of the invention, a hydraulic binder slurry may be applied to a surface of the foam element. Then the foam element with the hydraulic binder thereon is compressed to exclude air from the open cells and then the compression is released so th at the hydraulic binder slurry penetrates an d becomes contained in the open cells. The compression between the rollers : or perforated comprsession plate or plates forces penetration of the hydraulic binder slurry into the open cells of the Foam element. This step may be repeated in order fo ensure sufficient penetration of the hysdraulic binder slurry into the open cells of the foam element. This embodiment has the advantage that weights and final product densities may be very accurately controlled in a batch production cortext.

A further embodiment of the invention is illustrated in Figure 2 which is; () toimpose a shape upon the foam element containing the inorganic birder slurry, and/or (i) to achieve a taigher concentration of the inorganic binder slurry at the surfaces of the foam element when compared with the concentration of the organic binder slurry in the interior of the foam elenent.

In terms of the second alternative, the foam element containing the ino rganic binder slurry is compressed to impose a shape upon the foam element, either on one or Tooth sides of the foam element, which shape is retained when the inorganic binder sets.

This is illustrated schematically in Figure 2, Referring to Figure 2, a foam eleement 10 impregnated with an inorganic binder slurry is conveyed from a slurry tank (not shown) «on a conveyer 12 and then betweean top and bottom conveyors 14, 16 respectively, the conveyo r 14 being shaped as illustrated, te impose a shape upon the foam element 10. The inorganic binader impregnated in the foam eleme-nt 10 must set sufficiently prior to release from the conveyors 1-4, 16 so that the foam element 10 wetains its shape once it is moved out from between the conveyors 14, 16.

The shaped foam element 10 is then conveyed on a conveyor 18 into a drier 20, where the product is dried.

As an altermative, when the inorganic binder is for example a Portland cement, the foam element may be shaped between platens 22 which are then stacked and/or clamped to allow the

Portland cemment to set sufficiently prior to removal of the foam elements 1@0 from the platens 22, e.g for a per-iod of 12 to 24 hours.

For example, the foam elements 10 may be allowed to hydrate fully over =n extended period by stacking in &n open area with or without steam curing.

In the third alternative, the foam element containing the inorganic binder slurry is compressed to increase the concentration of the inorganic binder at the surfaces of the foam element relative to the concentration of the inorganic binder in the interior of the foam element.

This is illustrated in Figure 3 where there is shown a foam element: 30 having a higher concentration of inorganic binder 32 close to the surfaces thereof relative £o the concentration of inorganic biander 34 in the interior of the foam element 30.

For example the foam element may initially have a thickness of 20 mm which is then compressed to a final thickness of 12 mm.

This is achieved as is illustrated schematically in Figure 4. In Figure 4A, there is shown an open cell 40 of a foam element containing an amount of an inorganic binder 42. In Figure 4B the same cell 40 is illustrated when it has been partly compressed, indicating the concentration of the inorganic binder 42 in the cell. In Figure 4C there is agai nillustrated the same cell 40, now with an even greater concentration of the inorganic binder 42 in the cell 40.

In this way, it is possible to produce what is effectively a stress skin component with the highest concentration of the inorganic binder being in the outer horizons of the component. This is also used for lamination.

The hydraulic binder slurry may be reinforced with themoplastic polymers chosen from acrylates, methacrylates, vinyls or polyvinyl alcohol, or with water miscible thermosets such as oligo isocyanates such as Suprasec 1042 by Huntsman, or phenol formaldehyde resoles.

A fourth embodiment of the invention is illustrated in figures 5 which is;

Referring to Figure 5, a flexible open cell polymeric foam element 10, which may be either a continuous sheet or a discrete element, which may be flat or shaped, is transported on a conveyor 12 between two rollers 14, 16 between which the foam element 10 is compressed.

The rollers 14, 16, in this embodiment, are revolving perforated hollow feed tube rollers that include solid stationary cores 18, 20, respectively. The cares 1 8, 20 include respective feed conduits or channels 22, 24 for conveying a hydraulic binder slunry to the rollers 14, 16 and respective feed passages 26, 28 for feeding the hydraulic binder slurry to the perforated surfaces 30, 32.

The hydraulic binder slurry then contacts the surfaces 34, 36 of the foam element 10, whilst compressed and/or as compression is released, and then penetrates and becomes contained in the open cells of the foam element 10 as compression is eeleased on exiting the rollers 18, 20.

On exiting the rollers 18, 20 the impregnated foam element 10 regains its original size and shape. : The foam element 10 now containing the hydraulic binde=r slurry may be passed through a second set of perforated hollow tube rollers 38, 40, where the albovementioned method may be repeated. ) In addition, the impregnated foam element 10 may be passed between an optional third set of hollow feed tube rollers 42, 44 which only partially compress the foam e-lement 10 thereby resulting in partial impregnation of the outer regions of the foam element 10 to foam integrated solid or semi- sold Outer skins 46, 48. The foam element 10 now containing the d esired content of hydraulic binder slurry can then be further treated.

A potential difficulty in using the method referred to as the first embodiment of the invention illustrated in Figure 1 is that when water is added to a hydraulic birmder, hydration immediately commences and even in a continuous process the binder slumy in a bath or container will, in a relatiwely short period of time, produce lumps, accumulations or granules of set or partly set hydra_ulic binder at different stages of the hydration process. In some Cases, such as gypsum, the : hydration process can be almost indefinitely retarded, but this require=s added cost and at some point in the process, either the retardation must be neutralised or thee hydration accelerated fo overc-ome the retarder.

A further potential difficulty in impregnating the open cellular foam in a bath in which it is submerged is that when it is removed from the bath, the relatively high wiscosity of the slurry on top of the= emerging impregnated foam means that it must be removed unless the sheet exits the bath vertically. This difficulty is particularly true of sheet material.

In ad dition to obviating the above potential difficulties of submersiorm of the foam element, this fourtra embodiment of the invention allows for the degree of impregnation to be accurately controlled by pressure of the binder and the speed of the feed rollers. Further, the system is seff- purging, preventing the accumulation of set or semi-set hydraulic binder. Further, it makes provission for varying the reology or apparent viscosity of the slum without process difficulty, because it is under positive pressure and is forced into the foam. It alsso allows for the inclusion of a heavily or totally impregnated outer layer for added strength and vavater resistance of the final product. The system is easy to clean and easy to maintain and the binder can be easily maintained at a specific temperature by heating the stationary solid cores of the perforated rollers.

As indicated above, there may be used instead of the hydraulic binder slurry a thermoplastic material, typically a thermoplastic composition. The thermoplastic comeposition, which is preferably molten for erase of processing, may be selected from the group consisting of polystyrene, polyethylene, polypropylene, polyvinyl chloride, polyvinyl acetal, A.B.S, bitumen or refinery waste.

A fifth embod iment of the method of the invention is illustrated in Figure 6»

An example ©f the introduction of a binder into the open cells of a foan element by impregnation under pressure will now be given.

Figure 6 is a schematic diagram of this method of the invention. A length of an open cell polymeric foam element 10 is passed between free rolling feed rollers 12 whicih have a clutch controlled resistance so as to apply a tension to the open cell polymeric foam element 10. The open cell polymeric foam element 10 is pulled by a perforated feed roller 14, rotating in the direction shown.

At the feed roller 14, a binder in slumy or liquid form is impregnated into the open cell polymeric foam element 10 through a feed galley 16 in an assembly 18. As the bimnder in slurry or liquid form is injected into one side of the open cell polymeric foam element 10, air in the open cells is exhausted from the other side of the open cell polymeric foam element 1-0.

Optionally, compression rollers 20 may compress the open cell polyrmeric foam element 10 to ensure unifo rm wetting and penetration of the binder.

The open cell polymeric foam element 10 now impregnated from one si de is then wound around a second perforated feed roller 22, rotating in the opposite direction to thwe feed roller 14. The feed roller 22 incl udes a feed galley 24 in an assembly 26 which injects the b inder in slurry or liquid form into the opposite side of the open cell polymeric foam element 10, with ir again escaping from the side of the open cell polymeric foam element 10 not being impregnated.

The assembly again may include compression rollers 28 to ensure uniform wetting and penetration of the binder.

The impregnated open cell foam element 10 is then deposited onto a casnveyor 30.

Adjustable tension rollers 32 control the tension in the open cell polymeric foam element 10 as well as the area of surface contact with the perforated feed rollers 14 and 22.

The binder impregnated into thee open cell polymeric foam element 10 is then allowed to set to form the finished product.

As an alternative, the binder rmay be impregnated under pressure into the open cells of the foam element from one side thereof only, the binder penetrating through the entire thickness of the foam element

In another embodiment a binder precursor may be impregnated into the open cells of the foam element from one side of the element by a first feed roller followed by the impregnation into the foam element of a reactant to the binder precursor from the other side of the foam element by a second or sequential roller.

As indicated in the previous eembodiments, before the binder sets, the foam element contacining the binder may be formed into a desired shape.

In another embodiment of the invention, when the binder is a hydraulic binder slurry, the thydraulic binder slurry may be foamed by any method known in the art, i.e. the use of a pre-formed foam on the use of a foaming agent that foams in situ to give a low density hydraulic binder slurry.

The resulting product has a low density and yet a high thermal insulation and this is suitable for all thermal insulation applications, particularly the insulation of buildings.

Examples of products which nnay be produced by the method of the invention include the feollowing:

Gypsum Containing Products

A product moulded on both sides, such as the core of a fielded and planed or multi pane: lied door, ’ with a dry density in the range of from 250 to 400 kg/m? inclusive.

A product moulded to hasve a texture or pattern on one surface, such as an acoustic ceiling tie, with a dry density in the range of from 200 to 300 kg/m? inclusive.

Ceiling boards, wall boar-ds and wall cores, particularly wall boards reinforced with an acrylic to conform to the ASTM peerformance standards for wall boards without paper liners, with a dry density in the range of fro-m 400 to 600 kg/m? inclusive, or more preferably laminated wwith paper on both sides by a thermoplastic polymer reinforced gypsum slurry.

Thermal insulation panelss with a dry density in the range of from 100 to 175 kg/m3 inc lusive and an

R value of 3.2.

Portland Cement Produ«cts

Siding where the foam element has been shaped to the requisite profile to produce & product with a dry density of about 800 kg/m3, which may then receive a pure acrylic pigmented oveercoat.

Splash backs with a denssity of about 900 kg/m? and a typical thickness of about 12 mr.

Corrugated roof sheeting where the foam element containing the hydraulic binder slurry has been shaped over a former to provide a corrugated profile, the product having a dry dersity of about 1200 kg/m.

A roof tile with a dry dens ity in the range of from 1200 to 1500 kg/m3.

A U-section gutter, having a thickness of 10 mm and a dry density of about 1400 kg/me?.

Another product which m3ay be produced by the method of the invention is lightweight aggregate, ’ formed from chipped foamm particles or granules which may then be bound together by a hydraulic binder before or after s-efting, or by another binder after setting, and used as & castable or sprayable composition.

The foam element may be formed into particles or granules before coming into contact with the hydraulic binder slurry. Alternatively the product may be broken up after the hydraulic binder has set to give particles or granules.

The density of the product is controlled by the following variables: the cell size of the polymeric foam element; the water to hydraulic binder proportion by weight in excess of that required for full hydration of the hydraulic binder; and the amount of the hydraulic binder slurry removed from the saturated polymeric foam element during the method.

Densities of from 100 to 1500 kg/m3 are achievable with great accuracy by the method of the invention.

It is also to be noted that because the polymeric foam element has a uniformity of cell distribution, the resulting product is also uniform.

In addition, dense surface skins of hydraulic binder may easily be incorporated into a product before setting of the hydraulic binder.

The method of the invention has various advaretages. Firstly, it utilises simple equipment which thus has cost implications. The method is also e nergy efficient. The method allows density control of the finished product over a wide range. Using the method of the invention it is possible to produce a wide variety of finished products, with a variety of shapes.

A particular advantage unique over other forms of foamed inorganic binders is the peel strength, or resistance to delamination, of laminated foam dwe to the penetration of the adhesive system to a - requisite depth.

The method permits the production of products containing no lignocellulosic or other carrier fibres with their associated disadvantages. ‘ Examples of the invention will now be given. ’ Example 1

An acoustic ceiling file is made by the following method :

There is provided a 20 mm thick 10 kg/m? density open cell flexible TD! polyurethane foam element.

There is produced a hydraulic binder slurry containing:

Beta hemihydrate natural gypsum fine grind 1200 2% solution of Mowiol 8/88 by Clariant — polyvinyl alcokol in water solution 800

Melment F10 super plasticiser by Hoechst 10

Wacker BS15 potassium methyl siliconate 20

All parts by weight

The foam element is passed into a slurry tank containing the hydraulic binder slurry composition set above and is compressed between two rollers. On release of the compression, the hydraulic binder slurry penefrates and becomes contained in the open cells of the foam element.

The foam element containing the hydraulic binder skurry is passed out of the slurry tank and is rolled between two rollers to extract certain of the hydraulic binder slurry. The foam element containing the desired quantity of hydraulic binder slurry is then passed through a drier where the hydraulic binder sets and the product dries. Thereafter the product is cut to size to produce a : ceiling tile measuring 600 x 600 x 20 mm with a dry density of 250 kg/m?.

Example 2

A building board is made by the following method:

There is provided an 8 mm thick 14 kg/m3 density flexible open cell TDI polyureithane foam element.

There is produced a hydraulic binder slurry containing:

Rapid hardening Portland cement 900

Silica fume undensified 100

Water 420 . Acrylic emulsion 60

Melment F10 super plasticiser 10

Wacker BS1307 silicone base 6

All parts by weight

The foam element is passed into a slurry tank containing the hydraulic binder slurry composition described above. The foam element is compressed between two rollers in the slurTy tank. On release of the compression, the hydraulic binder slurry penetrates and becomes contained in the open cells of the foam element.

The foam element containing the hydraulic binder slurry is passed out of the slurry tank. The

Portland cement is allowed to hydrate and set, whereafter the product is dried to prodwuce an 8 mm thick building board with a density of 900 kg/m3. The board is easy to cut and nail, can be machined, is resistant to freeze/thaw and is cost effective.

Claims

wr CLEAN COPY ’ CLAIMS

1. A method for manufacturing a product which includes the steps of: a) engaging an open cell polymeric foam element with at least a fi rst perforated roller; b) fee ding a binder through the first roller; Cc) impregnating the binder into the foam element so that the bincder peretrates and becomes contained in the open cells of the foam ele ment; and d) allowing the binder to set to form the product.

2. A method according to claim 1 wherein the foam element includes a flexible open cell polyurethane foam in the density range of 7 to 20kg/m>.

3. A method according to claim 1 or 2 wherein the first roller includes. a perforated surface through which the binder is delivered.

4. A method according to claim 3 wherein the first roller includes a feed passage where through the binder moves to the perforated surface.

5. A method according to any one of claims 1 to 4 wherein the binder is selected from: i) an hydraulic binder slurry; ii) a mixture of a pozzolan and either lime or Portland cement in the foram of a slurry; iii) a s-ynthetic geopolymer precursor slurry; and P20697/nv/bijt

- CLEAN COPY - iv) a thermoplastic material in liquid form.

6. A method according to clairm 5 wherein the hydraulic binder slurry is selected from: i) alpha or beta hemihydrates of calcium sulphates; i) Portland cement; iii) calcium aluminate; iv) a pozzolan with lime or with Portland cement; Vv) magnesium oxichloride=; and vi) magnesium oxisulphate.

7. A method according to any ore of claims 1 to 6 which includes the step of compressing the foam element.

8. A method according to any ome of claims 1 to 7 which includes the step of shaping the foam element by molding, pressing or cutting.

9. A method according to any ome of claims 1 to 8 which includes the step of engaging the foam element with a second perforated roller.

10. A method according to any ome of claims 1 to 9 which includes the step of engaging the foam element with a first set of rollers consisting of the first and second rollers and at least a second set of rollers.

11. A method according to any ome of claims 1 to 10 which includes the step of drying the binder impregnated foam element in a drier. P20697/nv/bjt

CLEAN COPY } 12. A method for manufacturing a product whicha includes the steps of: : a) engaging a flexible open cell polymeric foam element in the density range of 7 to 20kg/m? with at least a first perforated roller; b) feeding a binder through the first roller; c) impregnating the binder into the foam element so that the binder penetrates and becomes contained in the open cells of the foam element; d) compressing the foam element; and e) allowing the binder to set to form the product.

13. A method for manufacturing a product as described herein with reference to any one of the accompanying drawings, Figures 1 to 6 and any one of the examples. CLEAN COPY dated this 17" day of MAY 2006 McCALLUM RADEMEYER & FREIMOND Patent Agents for the Applicant P20697/nv/bjt