GB2197673A - Simulated natural stone panels - Google Patents

Abstract

A building tile or like building product is formed from a mix 9 of an aggregate compound such as silica sand or crushed stone with a synthetic resin such as a polyester, epoxy, or phenolic. The mix 9 is placed in a mould 10 formed by applying a settable material to the surface of a natural stone tile or block, with a release agent applied to the mood surface. The mix is allowed to cure partially to a gel and is then freed from the mould and the cure completed so as to cause monomer or solvent to be driven off to provide a matt finish which combines with the moulded surface to resemble a natural stone appearance. <IMAGE>

Description

Fabricated Building Products This invention relates to the manufacture of artificial products for building, decorative purposes, or the like, having the appearance of natural stone, slate or similar material.

Natural stone and slate when cut and shaped for building purposes are in general extremely expensive} partly due to the normal methods of production. Existing artificial alternatives, which'usually involve the use of cement, do not provide top quality performance and appearance and in particular they tend to lack the texture, colour and natural random appearance of stone or slate.

Accordingly, it is an object of the invention to provide an improved building material or products which will better satisfy the commercial needs. In particular the invention aims to provide a building product with an appearance close to natural stone or slate, having in particular the dull matt appearance and random surface details which normally occur in natural stone. The invention also aims to provide such building products in a range of different shapes and sizes, and if required to the same thickness available with natural materials such as slate.

Surprisingly it has been found that by careful selection of the materials used and the moulding or casting conditions improved building products can be obtained to satisfy these requirements.

Broadly stated the invention consists in a moulded building product comprising an aggregate compound or filler with a synthetic plastic resin having a combination of a moulded irregular surface with a matt finish. According to a preferred feature of the invention the initial mixture includes a solvent or monomer which later evaporates from the surface to leave a matt finish.

The particular choice of synthetic resin is important and the resin is preferably polyester, methacrylate, epoxy, urethane, phenolic or furane. The aggregate may be any natural crushed stone or similar material, but is preferably crushed powdered slate, silica sand, Quartz or calcium carbonate.

According to another preferred feature of the invention the aggregate and/or the synethic resin includes a fire resistant or retardant compound.

The synthetic resin is preferably a thermosetting plastic and is cured chemically and/or thermally, for example, by means of a "redox" couple, a peroxide, an azo initiator, press moulding, hor or cold, or by moisture. Conveniently the materials are cured in a metal or silicone mould or a plastic mould such as polythene, polypropylene or urethane, or a mould coated with a release aqent such as silicone wax. After a first moulding process, the curing is conveniently carried out for example in an oven, to produce a matt finish by evaporation of monom#i #r solvent from the surface surface.

The invention also consists in a method of producing a moulded building product, in which a mixture of a mouldable synthetic plastic resin and an inorganic particulate material is moulded or cast in or on a moulding surface and a monomer or solvent is evaporated from the surface, after "demoulding", to provide a matt finish and the appearance of natural stone or slate.

In a preferred process the mixture is vibrated and/or inserted in a vacuum chamber to allow trapped air bubbles to escape. Conveniently the mixture is first allowed to cure partly in the mould and then deposited onto a second mould surface for a final cure.

The invention may be performed in various ways and details of some preferred processes will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagramatic, sectional elevation through a mould used in performing the invention, and Figure 2 is a similar elevation illustrating a second stage in the process, and Figure 3 is a diagram illustraging the microscopic appearance in section of the resultant surface.

In one procedure according to the invention building material for use as an artificial roof slate is manufactured by initially mixing a blend of aggregate together with an adding resin. A suitable formulation is below using silica sands although crushed slate, quartz, calcium carbonate and other aggregate formulation can be used, Silica Sand 0.8 mm to 1.5 mm Dia 40% Silican Sand 0.4 mm to 0.8 mm Dia 20% Silica Sand 0.3 mm to 0.6 mm Dia 10% Silica Sand 0.0 mm to 0.3 mm Dia 8% Silica Flour 7% Pigments 0.5% Peroxide 0.3% Pre-Accelerated Polyester Resin 14. 2% To produce a 610 mm x 305 mm roof slate 2-2 kg of the above mixture is placed in a silicone mould 10 which has been manufactured by casting silicone over a natural slate.The silicone mould is treated with a silicone release agentll.The material 9 is left in the mould to cure after vibrating, to level and ensure all entrapped air is removed, as shown in Figure 1. As soon as the resin and aggregate has gelled, i.e.

partially polymerised, to a state where it is partly cured and has sufficient strength it is demoulded "faceup" onto a board as shown at 12 in Figure 2. The polyester resin chosen must be sufficient free monomer at this stage so that monomer evaporation from the surface during the final cure and exotherm creates a matt finish. The time for complete cure is dependent on the reactivity of the chosen polyester resins.

An alternative formulation for manufacturing a roof slate is given below: Silica Sand 0.8 mm to 1.5 mm Dia 40% Silica Sand 0.4 mm to 0.8 mm Dia 20% Silica Sand 0.3 mm to 0.6 mm Dia 10% Silica Sand 0.0 mm to 0.3 mm Dia 8% Silica Flour 7% Pigments 0.5% Epoxy Resin Component A (resin) 7.5% Epoxy Resin Component B (hardener) 5% Xylene 2% The pigments and aggregates are mixed together and the two components of epoxy are mixed together and the solvent Xylene added to the epoxy.

The resin and aggregates are then mixed together and placed in a cold metal closed mould, which is manufactured by electrodeposition of nickel on to (chemically) plated natural slate. The complete mould assembly is placed under a press and left to start the cure.

Release agent (wax) is applied to the mould beforehand and after part-curing the roof slate is "demoulded",inverted, and placed in an air circulation oven at 120or to drive off the solvent to produce a matt surface finish.

The polymerisation procedure is illustrated by the following example of esterification of 1:1 mol of pentaerythritol with 2 mol of adipic acid: Pentaerythritol Adipic acid CH2 - OH O 0 HO-CH2-C-CH20H HO-C-CH2 CH2CH2CH2C-OH CH2-OH The ratio of reactive groups r is 4.4/4.0 = 1.1. If more than 55% of the hydroxyl groups are reacted (Pc o.55), the system will form a gel. The disruption of the surface creates a matt surface.

The temperature needed to carry out the process of matting-off is dependent upon the monomer/solvent used, and can be achieved or improved by air circulation or oven stoving.

Examples of some applicable solvents are as follows: Acetone, Acetonitrile,Acrylonitrile, n-Amylalcohol,Aniline, Benzene, n-Butanol, tert-Butylalcohol, Carbon disulfide, Carbon tetrachloride, Chlorobenzene, Chloroform, Cyclohexane, Cyclohexanone, n-Decane, Dietbylcarbonate, Diethylene glycol (DEG), DEG, monobutyl ether, DEG, monoethyl ether, Diethyl ether, N,N - Diformylpiperazine, Diisopropyl ether, N,N-Dimethylacetamide, N,N-Dimethylformamide, Dimethyl sulfoxide, 1,4-Dioxane, Ethyl acetate, Ethanol, Ethylbenzene, Ethylene carbonate, Ethylene dichloride (or l,2-dichloroethane), Ethylene glycol (EG) EG, monobutyl ether or (2-butoxyethanol), EG, monoethyl ether or (2-ethoxyethanol), Ethylene oxide, 2-Ethylhexanol, Formamide, Furfural, Glycerol, n-Heptane, n-Hexane, Isophorone, Isopropyl acetate, Isopropyl alcohol, Kerosene (typical) Methylene chloride, Methylethylketone, Nitrobenzene, Nitroethane,Nitromethane, l-Nitropropane, 2-Nitropropane, n-Pentane, Perchlorethylene or tetrachloroethylene, Piperidine,Propionitrile,n-Propyl alchohol, Propylene glycol or (1,2-propanediol), Propylene oxide, Pyridine, Styrene, Tetrahydrofuran, Toluene, 1.1,2-Trichloroethane, 1,1,2-Trichorethylene, l,l,l-Trichloro-2,2,2trifluoroethane, VM and P Naptha, Water, Xylene (mixed) The time scale for arriving at the gel state is dependent upon the polymer system used. For a Monomer such as Degamet 1400 (methylmethacrylate resin) supplied by Degussa, Germany, the gel time is approximately 30 PTn mins. For a polyester such as Polymaster 2685 TAL LSE (a polyester resin)supplied by K & K Mouldings (England) Limited.The gel time for the resin with a catalyst (Methyl Ethyl Ketone peroxide 50%) at 0.75% is approximately 45 mins.

Likewise when using a solvent such as xylene in an Epoxy resin: Component A Epoxy resin EEW180 (1) 84% Reactive Solvent (2) 16% 100% Component B -,r1 Epilink/R 4018 (3) 100% Component C Quartz sand 0.7-1.2 62.5% Quartz sand 0.1-0.3 37.5% 100% (1) obtainable from Shell (2) obtainable from EMS Chemie Ch (e) obtainable from AKZO Chemie The diagram of Figure 3 illustrates that the final surface of the moulded products has a general contour X derived from the mould surface and on to this is superimposed the small irregularities Y derived from the evaporation of the monomer or solvent after preliminary moulding. It is the irregularities Y which give the necessary matt finish and without which the surface of the moulded product does not have a realistic resemblance to that of natural stone. In general the range of dimensional variation of the moulded contour X is of the order of 0.1 to 5.0 mm. while the range of dimensional variation on the microscopic scale, giving the matt surface rougness Y is of the order of O.lto 50 microns.

Claims (15)

1. A moulded building product comprising an aggregate compound with a synthetic plastic resin having a combination of a moulded irregular surface with a matt finish.

2. A building product according to Claim 1, in which the matt finish is produced by evaporation of a solvent or monomer from the initial material.

3. A product according to Claim 1 or Claim 2, in which the synthetic resin is a polyester resin, a methacrylate resin, an epoxy resin, a urethane resin, a phenolic resin or a furane resin.

4. A product according to any of claims 1,2 or 3, in which the aggregate comprises crushed slate (i.e. slate dust), silica sand, Quartz sand, calcium carbonate, or any natural crushed stone.

5. A product according to any of the preceding claims, in which the aggregate and/or the synthetic resin includes a fire resistant or retardant compound.

6. A product according to any of the preceding claims, in which the synethic resin is cured chemically and/or thermally, for example by means of a "redox" couple, a peroxide, an azo initiator, press moulding, hor or cold, or by moisture.

7. A product according to any of the preceding claims, in which the resin and aggregate are cured in a metal or silicone mould or a plastic mould such as polythene, polypropylene or urethane, or a mould.

8. A building product according to any of the preceding claims which is post-cured after moulding, in an oven, with its moulded surface exposed, to produce a matt finish by evaporation of monomer or solvent from the surface.

9. A building product according to any of the preceding claims, in which the moulded surface has major irregularities with dimensional variations between approximately 0.1 - 5.0 mm. and minor irregularities or pores having dimensions between approximately 0.1 - 50 microns.

10. A method of producing a moulded building product, in which a mixture of a mouldable synthetic plastic resin and an inorganic particulate material is moudled or cast in or on a moulding surface and allowed to cure partially, and is then freed from the mould to allow evaporation of solvent or monomer, thus producing a matt surface so as to provide the appearance of natural stone or slate.

11. A method according to Claim 10, in which the mixture is vibrated in or on the mould to allow trapped air bubbles to escape.

12. A method according to Claim 10 or Claim 11, in which the mixture is first allowed to cure partly in the mould and then inverted so that the moulded surface is freed for a final cure.

13. A method according to any of Claims 10 to 12, in which the mixture includes a monomer, or solvent, or other evaporating components, which is/are allowed to evaporate from the surface to create a matt finish.

14. A building product substantially as described herein.

15. A method of manufacturing a building product substantially as described herein.