WO2003011544A1

WO2003011544A1 - A method of forming a tile, a tile, a roofing structure and a mould

Info

Publication number: WO2003011544A1
Application number: PCT/GB2002/003487
Authority: WO
Inventors: Richard Gregg Ogden; David Broadbent
Original assignee: Ogden Industries Limited
Priority date: 2001-07-27
Filing date: 2002-07-29
Publication date: 2003-02-13
Also published as: GB2380446A; GB0118302D0; GB0217477D0

Abstract

A method of forming a reconstituted slate roofing tile having a matt surface utilises a mould (10) comprising a mould body (20) incorporating a moulding surface which includes a region defined by a material having a Rockwell C hardness of at least 40. A closure member (30) is provided and arranged to force a mouldable material comprising slate and a resin into the mould body to produce a tile.

Description

A METHOD OF FORMING A TILE, A TILE, A ROOFING STRUCTURE AND A MOULD

The present invention relates to tiles, and in particular tiles comprising slate, a mould body for tiles, a method for the manufacture of tiles and an assembly of tiles.

Tiles, and in particular roofing tiles are often made using mouldable compositions comprising slate and a press moulding process. Such mouldable compositions generally comprise slate powder and granules and a resin, such as a polyester resin as their principle components. The mouldable composition is generally pressed into a mould body and heated to cure the resin. The moulded tile is then removed from the mould and allowed to cool . It is known to produce such tiles so that they have the appearance of natural slate tiles. However, whilst such tiles are moulded to have the uneven or riven surface appearance of natural slate it has been found that the tiles have a glossy appearance when removed from the mould. In order to produce tiles having the matt finish of natural slate it has been found necessary to treat the tiles post de-moulding, for example by sand blasting, to remove the gloss finish.

Such additional treatment is both time consuming and costly and requires additional production space. In addition the post de-moulding process also has a detrimental effect on the uneven surface appearance given to the tile during the moulding process.

It is an object of the present invention to address the above described problems. According to the present invention there is provided a method of forming a tile from mouldable material comprising slate, the method employing a press moulding process utilising a mould comprising a mould body incorporating a moulding surface and wherein a region of said moulding surface is defined by a material having a Rockwell C hardness of at least 40 and is arranged to impart a matt surface onto a tile moulded therefrom such that a region of the surface of a tile formed in the method has a matt finish upon de-moulding.

Preferably, the region of the moulding surface arranged to impart a matt surface onto a tile moulded therefrom has a matt finish.

Whilst specific reference is made to the hardness in terms of the Rockwell C scale it is to be understood that the scope of the invention extends to materials whose hardness is generally defined in terms of an alternative scale where said material has a hardness equivalent to the Rockwell C value specified herein. Thus a material for which a standard test method using the Rockwell C scale is not available may fall within the scope of the invention if it has a hardness value upon another scale which is equivalent to a Rockwell C value specified herein, as may be established using a conversion table which is readily available to those in the art of hardness testing.

Preferably, the matt imparting region of the moulding surface has a Rockwell C hardness of at least 45, for example between 45 and 80, preferably between 45 and 70, especially between 45 and 60. Preferably the matt imparting region of the moulding surface has a Rockwell C hardness of at least 50, for example between 50 and 75, preferably between 50 and 70, more preferably between 50 and 55. Preferably, the matt imparting region of the moulding surface has a Rockwell C hardness of at least 52.

Preferably, at least 70% of the area, more preferably at least 85% of the area, especially substantially the entirety of the moulding surface has the same hardness as the matt imparting region thereof.

Preferably, the moulding surface is an integral part of the mould body.

Preferably, the material defining the moulding surface comprises cast iron. Preferably the entirety of the mould body comprises cast iron, more preferably cast iron having a Rockwell C hardness of at least 40.

Preferably, the mould further comprises a closure member arranged to compress the mouldable material into the mould body and against the moulding surface . The closure member may comprise a plate which may be substantially flat and arranged such that it can abut the mould body. Alternatively the closure member may comprise a second mould body which may incorporate a second moulding surface. The second mould body may be arranged to cooperate with the first mould body such that they define the shape of the tile to be moulded. Press moulding processes which are suitable to be employed in the method of the present invention are known and it will be understood by those skilled in the art that any closure member known in the art and suitable for use with a mould body may be employed in the method of the present invention. The closure member may comprise steel. Alternatively, the closure member may comprise cast iron.

Preferably, a tile is formed in the method of the invention by moving the closure member towards the mould body such that the mouldable material is pressed therebetween and the closure member is then moved away from the mould body allowing the moulded tile to be released from the mould body.

Preferably, the tile is formed by pressing the mouldable material under a pressure of at least 100 ton. Preferably, the tile is formed by pressing the mouldable material under a pressure of between 200 and 500 ton, more preferably of between 350 -and 450 ton.

Preferably, the tile is formed by subjecting the mouldable material to heat whilst it is pressed between the mould body and closure member. Preferably, the mould body and closure member are at a temperature of at least 80°C. Preferably, the mould body and closure member are at a temperature of between 100°C and 160°C, more preferably between 118°C and 150°C, for example between 125°C and 135°C. Preferably, the mouldable material reaches the temperature of the mould body and closure member, during formation of the tile.

Preferably, the mouldable material is pressed between the mould body and closure member for at least 30 seconds. Preferably, the mouldable material is pressed between the mould body and closure member for between 40 and 120 seconds, more preferably between 40 and 80 seconds, for example between 50 and 70 seconds. Preferably the mouldable material is heated for the entirety of the time it is pressed.

Preferably, the moulding surface of the mould body is arranged such that a matt surface is imparted onto a region of the tile which is visible when said tile is in use. Preferably, a matt surface is imparted onto the whole region of the tile which is visible in use.

Preferably, the matt imparting region of the moulding surface appears matt due to its surface structure. Preferably, the matt imparting region of the moulding surface has a microscopic surface roughness and it is this which causes the surface to appear matt. When a tile is formed using the method of the present invention the moulding surface may impart a negative of its surface structure onto the tile. Consequently a part of the tile may be given a microscopic surface roughness such that it has a matt finish.

Preferably, the moulding surface is arranged such that a region of the matt imparting region of the moulding surface also has an uneven texture (hereinafter the "textured region") . By uneven texture it is meant there are surface undulations which are visibly apparent and which are additional to the microscopic surface undulations which may provide the matt finish to the moulding surface. For example a part of the moulding surface may have a riven finish. Preferably, the entirety of the matt imparting region of the moulding surface may have an uneven texture. The textured region of the moulding surface may resemble the surface of natural slate. The textured region of the moulding surface may be produced by taking a cast of a natural slate. The moulding surface may thus impart an uneven textured matt surface onto a tile formed using the method of the present invention such that a part of a surface of said tile closely resembles that of natural slate.

Alternatively, the textured element of the moulding surface may closely resemble other natural materials, for example natural shingle or shake manufactured from timber.

Preferably, a tile produced in the method of the present invention may be such that some or all of the parts of its surfaces which are not arranged, in use, to be visible have a gloss finish. This may be achieved by providing the moulding surface of the mould body (and appropriate regions of a said closure member when provided) with corresponding regions having a gloss surface. The regions of the moulding surface (and/or closure member) having a gloss finish may be polished to provide them with said gloss finish. The gloss regions of the moulding surface

(and/or closure member) may be substantially smooth. Preferably, the gloss regions of the moulding surface

(and/or closure member) have a microscopic surface roughness which is substantially less than that of the matt imparting region of the moulding surface.

Preferably, at least 60% of the area of the moulding surface is arranged to impart a matt surface onto a tile moulded therefrom, more preferably at least 65%, for example at least 70%. At least 90% of the moulding surface may be arranged to impart a matt finish onto a tile moulded therefrom.

Preferably, at least 60% of the surface of the tile comprising the region which is arranged, in use, to be visible, comprises a matt finish, more preferably at least 65% comprises a matt finish.

Between 65% and 75% of the surface comprising the region which is arranged, in use, to be visible, may comprise a matt finish. Alternatively, between 90% and 100% of the surface comprising the region which is arranged, in use, to be visible, may comprise a matt finish.

Preferably, the tile produced according to the method of the present invention may be suitable for cladding a part of a building. Preferably the tile produced according to the method of the invention comprises a roof tile, in particular a reconstituted slate roof tile. Alternatively, the tile may comprise a wall or floor tile.

Preferably, the mouldable material comprises crushed natural slate. Preferably the mouldable material comprises fine slate powder and/or coarse slate granules. Suitably, said mouldable material includes at least 50 wt%, preferably at least 60 wt%, more preferably at least 70 wt%, especially at least 75 wt % of slate. The amount of slate is preferably less than 95 wt%, more preferably less than 90 wt%. Preferably, the mouldable material further comprises a resin. Preferably, the resin is a synthetic resin. Said resin is preferably curable. Said resin may be a polyester resin. Preferably, said mouldable material includes at least 5 wt%, preferably at least 10 wt%, especially at least 12 wt% resin. Said material may include less than 40 wt%, suitably less than 30 wt%, preferably less than 20 wt%, especially less than 18 wt% resin. Preferably, the mouldable material comprises unsaturated polyester resin in styrene binder. Preferably, the mouldable material comprises iron oxide, titanium dioxide or chrome dioxide and may also comprise zinc stearate. The mouldable material may also comprise calcium carbonate and may in addition comprise an organic peroxide catalyst to act as an aid in the curing of the resin. The mouldable material may also comprise one or more of glass fibres, aluminium trihydroxide and polythene beads. The mouldable material may also comprise further components known to those skilled in the art.

According to the present invention there is further provided a tile produced by the method of the invention as described in any statement herein.

According to the present invention there is provided a moulded tile comprising slate, wherein all or part of said tile has a matt finish surface as a result of the moulding process.

Preferably, the tile may be suitable for cladding a part of a building. Preferably, said tile comprises a roofing tile. Alternatively, said tile may comprise a floor or wall tile, a ceiling tile, shingle or shake.

Preferably, the tile has a width of between 200 and 400 mm, more preferably between 250 and 350mm, for example between 280 and 330mm. Preferably, the tile has a length of between 200 and 700mm, more preferably between 250 and 650mm. The tile may have a length of between 250 and 350mm, more preferably between 280 and 310mm. Alternatively the tile may have a length of between 500 and 650mm, more preferably of between 580 and 620mm.

Preferably, the tile has a thickness of between 2 and 15 mm, more preferably between 3 and 10mm. Preferably, the tile has a thickness of between 4 and 7mm.

The tile may be substantially rectangular. Alternatively, the tile may have another form and the lengths and widths given above may correspond to its largest dimensions.

According to the present invention there is further provided an assembly of two or more tiles produced in accordance with the present invention.

Preferably, the assembly is arranged such that only matt surfaces of the tiles are visible. Preferably, the assembly is arranged such that only textured regions of the tile are visible. Preferably, the assembly is arranged such that it has the appearance of an assembly of natural slate tiles.

Preferably, the assembly is arranged to form the outer surface of a roofing structure.

According to the present invention there is further provided a roofing structure comprising one or more tiles made in accordance with the invention. Preferably, the roofing structure comprises a plurality of substantially parallel roofing bars to which a plurality of tiles are secured.

Preferably, the roofing structure comprises an assembly of tiles as hereinbefore described.

According to the present invention there is provided a building structure comprising one or more tiles made in accordance with the present invention.

According to the present invention there is further provided a mould body suitable for use in the method of the invention as described in any statement herein.

The mould body may be suitable for performing many moulding operations. Preferably, the mould body is suitable for performing at least 1000 moulding operations, more preferably at least 10,000 moulding operations.

According to the present invention there is further provided a mould body arranged to be employed in the production of tiles comprising slate, the mould body incorporating a moulding surface a region of which has a Rockwell C hardness of at least 40, wherein said surface is arranged to impart a matt finish to a part of a tile moulded therefrom.

Preferably, the matt imparting region of the moulding surface has a Rockwell C hardness of at least 50. Preferably, the entirety of the moulding surface has the same hardness as the matt imparting region. The mould body may comprise hardened cast iron. Preferably, the mould body comprises SG cast iron having a moulding surface with a Rockwell C hardness of between 50 and 55.

Preferably, the mould body is formed by taking a cast of a pattern which has the desired form of the outwardly facing or front face of the tile which will be made using the mould body. Preferably, the mould body is formed by taking a cast from a sample of natural slate.

Preferably, the cast is created by pouring molten iron into a mould comprising the pattern. Preferably, once the mould body is cast it is then heat treated to harden the moulding surface. Preferably, any parts of the moulding surface which are desired to have a non-matt finish may be polished.

If the rear face of the moulded tile is desired to have features then a second mould body may be formed by taking a cast of a second pattern representing the rear face of the tile and optionally part of the side faces of the tile.

Any feature of any aspect of any invention or embodiment described herein may be combined with any feature of any aspect of any other invention or embodiment described herein.

A specific embodiment of the present invention will now be described, by way of example,^" with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a mould. Figure 2 is a perspective view of a moulded tile.

Figure 1 shows a mould 10 comprising a mould body 20 and a closure member 30 which can be arranged to force a mouldable material comprising slate (not shown) into the mould body 20 to produce a tile 100 as shown in Figure 2.

The mould body 20 comprises a moulding surface 21 made of a material having a Rockwell C hardness of 52 to 54 and incorporating a region 22 arranged to impart a matt finish onto a region 122 of the surface of a tile 100 moulded therefrom. The tile 100 thus comprises a region 122 which has a matt finish upon de-moulding and which does not require further treatment to achieve a matt finish. The region 22 of the moulding surface 21 is also arranged to impart a riven or uneven textured appearance onto the region 122 of the surface of the tile 100 moulded therefrom. The moulding surface 21 imparts the matt surface onto the tile 100 because the region 22 of the moulding surface itself has a matt finish. The tile may thus have a region 122 having the appearance of natural slate upon de-moulding.

Regions 23,24 of the moulding surface are polished such that they impart a gloss finish onto corresponding regions 123,124 of the surface of a tile 100 moulded therefrom. Such regions 123,124 form sections of the tile 100 which will not be visible in use and may make the matt region 122 look more natural to a prospective purchaser.

A method of producing a tile as hereinbefore described can employ the following process. A measured amount of crushed natural slate (fine powdered and coarse granules) is screw fed into a mixer. Zinc stearate, which is a release agent to stop the mixed compound sticking to the mould, is added along with iron oxide pigments . The dry powders are then mixed for around three minutes .

A measured amount of polyester resin is pumped into a tank where an organic peroxide is added and thoroughly mixed. The organic peroxide acts as a catalyst; when the mixed compound is subjected to heat the catalyst speeds up the cure time .

A measured amount of catalysed polyester resin is fed from the tank and through a flow meter into the mixer where it is mixed with the dry powders to form a dough moulding compound (DMC) . The DMC is then dropped into an extruder which forms charges . Each charge is check weighed and then taken to the press. The press comprises twelve moulds, and each requires one 2.05 kg charge to mould a 600mm x 300mm slate. The press comprises three sets of four mould bodies with the sets arranged to sit above one another. The press further comprises three plates, one of which is arranged to sit under each mould set and which are arranged to act as closure members to the mould bodies . Thus, two of the plates lie between the mould sets. Each plate acts as the closure member for four mould bodies . The mould bodies are orientated such that their moulding surfaces point downwards towards the closure member. Four charges are placed on each closure member and the mould bodies and closure members are then moved towards one another. Each charge is pushed into the mould body and subjected to 1500 pounds per square inch of pressure at a temperature of 130 °C. After one minute the press opens and the charges are taken out of the press, inspected and placed on a table to cool . The cooling table has a centre bar which gives the slates a slight positive camber to ensure they lie flat when installed on a roof.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference .

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) , may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment (s) . The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings) , or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of forming a tile from mouldable material comprising slate, the method employing a press moulding process utilising a mould comprising a mould body incorporating a moulding surface and wherein a region of said moulding surface is defined by a material having a Rockwell C hardness of at least 40 and is arranged to impart a matt surface onto a tile moulded therefrom such that a region of the surface of a tile formed in the method has a matt finish upon de-moulding.

2. A method according to Claim 1, wherein the region of the moulding surface arranged to impart a matt surface onto a tile moulded therefrom has a matt finish.

3. A method according to Claim 1 or Claim 2 , wherein the matt imparting region of the moulding surface has a Rockwell C hardness of at least 50.

4. A method according to any preceding claim, wherein the material defining the moulding surface comprises cast iron.

5. A method according to any preceding claim, wherein the mould further comprises a closure member arranged to compress the mouldable material into the mould body and against the moulding surface.

6. A method according to any preceding claim, wherein the tile is formed by pressing the mouldable material under a pressure of at least 100 ton.

7. A method according to any preceding claim, wherein the matt imparting region of the moulding surface has a microscopic surface roughness which causes the surface to appear matt .

8. A method according to Claim 7, wherein the moulding surface is arranged such that a region of the matt imparting region of the moulding surface has an uneven texture .

9. A method according to Claim 8 , wherein the uneven texture is produced by taking a cast of a natural slate.

10. A method according to any preceding claim, wherein a tile produced is such that some or all of the parts of its surfaces which are not arranged in use to be visible have a gloss finish.

11. A method according to any preceding claim, wherein the tile produced is a roof tile.

12. A method according to any preceding claim, wherein the mouldable material comprises crushed natural slate.

13. A method according to any preceding claim, wherein the mouldable material further comprises a resin.

14. A method according to Claim 12 and Claim 13 , wherein said mouldable material includes at least 5 wt% resin and at least 50 wt% slate.

15. A tile produced in a method according to any of Claims 1 to 14.

16. A roofing structure comprising one or more tiles made in a method according to any of Claims 1 to 14.

17. A mould body arranged to be employed in the production of tiles comprising slate, the mould body incorporating a moulding surface, a region of which has a Rockwell C hardness of at least 40, wherein said surface is arranged to impart a matt finish to a part of a tile moulded therefrom.