GB2159066A

GB2159066A - A method of, and apparatus for, continuously forming sheeting and the manufacture of building panels from such sheeting

Info

Publication number: GB2159066A
Application number: GB08413486A
Authority: GB
Inventors: Roger George Hansom; Colin Arthur Primarolo
Original assignee: ARYAN GROUP Ltd
Current assignee: ARYAN GROUP Ltd
Priority date: 1984-05-25
Filing date: 1984-05-25
Publication date: 1985-11-27
Also published as: GB2159066B; GB8413486D0

Abstract

A method of and apparatus for, continuously forming sheeting and the manufacture of building panels from such sheeting. Resin paste 11 comprising resin, hardener and filler is applied from hopper 9 and 10 on to a carrier sheet 1 by which the paste is moved continuously over a vibrating table 4 and through a curing oven 6. Paste 11 is screeded at 12 and a reinforcing glass fibre mat 13 is applied thereto. The mat 13 is embedded by a further load of the paste 11 from hopper 10 and the paste is again screeded at 16. A plastics cover sheet 18 can be applied to the surface of paste 11. Pre-shaped formers can he housed in the oven to mould the paste into a non-flat profile, the paste 11 can be extruded on carrier sheet 1 through an aperture to provide longitudinally extending recesses. These recesses can accommodate insulation material for sandwiching between two sheets in the manufacture of a building panel. <IMAGE>

Description

SPECIFICATION A Method of, and Apparatus for, Continuously Forming Sheeting and the Manufacture of Building Panels from such Sheeting Technical Field and Background Art This invention relates to a method and apparatus for forming resin bonded sheeting and to a method of manufacturing a building panel from such sheeting. More particularly the invention is concerned with the continuous formation of sheeting by curing a paste comprising resin, hardener and filler. Resin bonded sheets and panels for use in the building industry and formed by moulding and curing a paste of resin, hardener and filler are well known, for example as disclosed in U.K. Patents Nos. 1,226,061; 1,259,428 and 1,324,681.

The advantages of moulded and filled resin bonded sheets or panels as compared with the more conventional sheets or panels are also recognised in the building industry. For example, resin bonded sheets and panels may have excellent fire resistant characteristics, can be produced relatively inexpensively-particularly when filled with sand or other readily available material, are chemically and physically stable, have a long life and can be produced in a moulded form ready for assembly or erection on a building site.Hitherto filled resin bonded sheets and panels have been moulded on a piecemeal basis so that their production is labour intensive and relatively slow and it is an object of the present invention to alleviate these disadvantages by forming resin bonded sheeting continuously and, if required, applying such sheeting to the manufacture of building panels (which may be decorative, structural and/or insulating).

Statements of Invention and Advantages According to the present invention there is provided a method of continuously forming resin bonded sheeting which comprises progressively moving a base carrier sheet longitudinally, loading on to the carrier sheet resin paste comprising a mixture of resin, hardener and filler; screeding the said paste on the carrier sheet to a layer of required thickness and moving the resin paste with the base carrier sheet whilst curing of the paste is effected.

Further according to the present invention there is provided apparatus for continuously forming resin bonded sheeting by the method specified in the immediately preceding paragraph which comprises a base carrier sheet; means for progressively moving the sheet longitudinally; means for loading on to the carrier sheet resin paste which is to comprise the sheeting, and means for screeding the resin paste on the carrier sheet to a layer of required thickness for curing.

The invention further comprises a method of manufacturing a building panel which comprises forming resin bonded sheeting the method specified in the aforegoing penultimate paragraph and during said forming moulding in to the sheeting at least one longitudinally extending recess; cutting the sheeting which emerges from the oven to form a resin bonded sheet of predetermined length; and bonding or adhesively securing to said resin bonded sheet a closure sheet to close the longitudinal extent of said recess.

By the present invention the resin bonded sheeting is continuously formed and the cured rigid sheeting on the carrier sheet can be cut into sheets of predetermined length (for example by use of a flying cutter) for use as cladding, decorative panels or for assembly into a building panel which may be intended for structural and/or insulation purposes.

Preferably the resin paste is carried by the carrier sheet through an oven within which the paste is heated to promote curing.

The resin, hardener and filler which are mixed to form the resin paste may comprise the constituents and proportions as discussed in prior U.K. Patents 1,226,061; 1,259,428 and 1,324,681. More preferably however the resin paste is a homogeneous mixture where the resin (unsaturated polyester) is 1 part by weight, the filler is 1 to 15 parts by weight sand, and the hardener (or catalyst) is 0.01 to 0.05 parts by weight; in addition the mixture can include minor proportions of accelerator and fine filler or slipping agent (such as French chalk).

If the resin is subjected to accelerated curing within an oven as mentioned above, the oven will likely have a temperature in the range of 10 C to 1 500C while the paste (which is likely to have a thickness in the order of 3 to 10 mms) is carried through the oven on the carrier sheet at a speed in the order of 3 to 6 metres per minute.

It is a preferred feature of the present invention that the resin paste when applied to the carrier sheet and during, and subsequent to, the screeding operation, is subjected to vibration. This vibration is conveniently achieved by sliding the carrier sheet over a vibrating table. This vibration of the resin paste is advisable to remove air from the paste. The presence of air pockets or bubbles within the paste can adversely affect the strength of the resultant cured sheeting, can adversely affect the curing of the sheeting and can cause voids in the cured sheeting which may cause the sheeting (or a panel or other product formed therefrom) to retain water in use and possibly be subjected to frost damage.

The vibration of the paste also has the advantage that it can be used to provide a fine, smooth surface finish to the paste before it is cured within the oven.

If required a textured finish such as sand, fine aggregate or a print or embossing can be applied to the surface of the sheeting prior to curing.

When the resin paste has been screeded it is preferred that a reinforcing sheet (such as glass fibre mat or other reinforcement as discussed in our previously mentioned U.K. Patents) is applied to the paste. During the application of the reinforcing sheet to the resin paste it is preferred that the paste is vibrated as mentioned above, this has the advantage of wetting-out the reinforcing sheet to ensure that a thorough bond is achieved between the paste and the sheet in the subsequently cured resin bonded sheeting. Preferably the reinforcing sheet is embedded in resin paste; this may be achieved by applying to the reinforcing sheet on the screeded resin paste a second load of resin paste and screeding that second load to a required thickness.The presence of a reinforcing sheet such as glass fibre mat to the resin paste considerably improves the tensile strength of the resultant sheeting and also renders the sheeting less likely to fracture. Preferably the reinforcing sheet is embedded in the resin paste so that it is disposed substantially symmetrically in the paste. Also it is preferred that the reinforcing sheet, particularly if of a fibrous nature, is wholly embedded in the resin paste to alleviate filaments from being exposed in the outer surface of the resin sheet which could then provide conduits through which water gains access into the interior of the resin sheeting. If required, two or more layers of reinforcing sheet can be applied with alternating layers of resin paste and again it is preferred that the reinforcing sheets are disposed substantially symmetrically in the resin paste.The preferred symmetrical disposition of the reinforcing sheet or sheets in the resin paste alleviates the likelihood of the resin bonded sheeting becoming deformed or "curling" during its curing (so that, if required, substantially flat resin bonded sheeting can be formed) and renders the resultant cured sheet less likely to snap or fracture under bending loads.

A cover sheet may be applied to the surface of the resin paste remote from the base carrier sheet, conveniently prior to the paste entering the oven.

This cover sheet may assist in forming and maintaining the top surface of the resin bonded sheeting. The carrier sheet and/or the cover sheet is conveniently of plastics and if required one or both of these sheets may be recirculated whereby that sheet or sheets on emerging from the oven is peeled from the cured resin bonded sheeting and circulated for re-use with a further load or loads of resin paste.

The aforementioned cover sheet can initially act as a second carrier sheet onto an upwardly directed surface of which resin paste is loaded and screeded to a layer of required thickness. During this loading and screeding operation the cover sheet and resin paste thereon are preferably subjected to vibration-conveniently in a similar manner to the vibration of the first carrier sheet as previously discussed and for similar reasons (particularly to remove air pockets). The cover sheet and its vibrated paste load can now be inverted (usually by passing over a roller) so that the resin paste is directed downwardly while adhering to the cover sheet and in this condition the layer of resin paste on the cover sheet can be moved onto the layer of resin paste on the first carrier sheet to sandwich a reinforcing sheet between the two paste layers.This proposal has the advantage that each of the two layers of resin paste (on the carrier sheet and cover sheet) can be vibrated to remove air pockets (especially from the interface of the resin paste layer with the sheet which carries it) so that both the top and bottom surfaces of the resultant cured sheeting can have a fine, smooth surface finish.There is also the advantage that during vibration of the resin paste layers, the filler will tend to settle in those layers and a film of resin will develop on the upper surface of each of the layers; these films of resin will serve to wet-out the reinforcing sheet to ensure a thorough bond therewith as the reinforcing sheet is deposited on the upper surface of the resin paste layer on the carrier sheet and when the layer of resin paste on the cover sheet is inverted (so that the resin film is directed downwardly) and moved to sandwich the reinforcing sheet as aforementioned.

The present invention can advantageously be applied to the continuous formation of resin bonded sheeting which is other than flat. For example, the carrier sheet and resin paste (and any reinforcing sheet) can be passed over pre-shaped former means which is preferably located in the oven and which determines the shape (for example corrugated) of the resin bonded sheeting. If required the former means can progressively mould the paste into the shape required for the sheeting during the movement of the paste and prior to the paste being fully cured. Alternatively, or in addition, the resin paste may be screeded by drawing it through a pre-shaped aperture so that a predetermined nonflat profile is provided for the surface of the resin paste remote from the carrier sheet and prior to the resin paste being cured.

The ability to mould or shape the surface of the resin paste to a non-flat profile as aforementioned can be used to advantage in the manufacture of building panels in accordance with the present invention. To achieve this the resin paste can be drawn as aforementioned to have in its upper surface one or more longitudinally extending recesses. Resin bonded sheets of predetermined length are then cut from the sheeting and the recesses are then closed by a closure sheet adhesively secured or bonded to the resin bonded sheet. The cavity or cavities which are formed between the longitudinally extending recesses and the closure sheet can serve to house insulation material and/orto accommodate reinforcing elements such as joists, struts or conduiting.

Preferably the closure sheet is derived from resin bonded sheeting formed by the method of the present invention. The closure sheet may be substantially flat or otherwise. Preferably however the two resin bonded sheets are of substantially the same configuration and size and are secured together substantially in the mirror image of each other to form the cavity or cavities between opposing longitudinal recesses in the respective sheets.

The insulation material, which may be for thermal, sound or otherwise, is preferably provided by foaming material which is injected into the cavities. Other insulation can be provided, for example, sand or ballast with which the cavities can be filled, possibly on site, following delivery of a hollow panel. To ensure structural rigidity and strength for the building panel, particularly where the panel is formed by two substantially identical resin bonded sheets which are secured or bonded together in the mirror image of each other, it is preferred that each resin bonded sheet is provided with at least one reinforcing sheet and that the reinforcing sheets are symmetrically disposed within the assembled panel. If required, the exposed ends of the recesses in the panel can be closed by caps or plates which are bonded, adhesively secured or otherwise fitted to the ends of the panel.

Drawings Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying illustrative drawings in which: Figure 1 diagrammatically shows a side elevation of apparatus for continuously forming resin bonded sheeting in accordance with the method of the present invention; Figure 2 is a perspective view of a simple form of mould or former by which the resin paste can be pre-moulded into a corrugated profile for the sheeting; Figure 3 is a perspective view of a carrier sheet with reinforced resin paste thereon and illustrates the manner in which the paste can be drawn to provide resin bonded sheeting with longitudinally extending recesses therein;; Figure 4 is an end view of a structural building panel which may be constructed from the sheeting formed as shown in Figure 3, and Figure 5 shows a modification of the apparatus in Figure 1.

Detailed Description of Drawings In the apparatus of Figure 1 a plastics carrier sheet 1 is drawn off from a roll 2 and beneath a guide roller 3 to slide over a flat topped vibrating table 4.

The carrier sheet 1 is drawn to progress longitudinally from the table 4 between a pair of opposed idler rollers 5 and into an oven 6. The sheet 1 emerges from the oven to pass over a roller 7 which latter conveniently serves as a haul-off roller which determines the longitudinal speed of the carrier sheet. During its passage through the oven 6 and after emerging from the oven, the carrier sheet 1 is supported on an array of rollers 8 which may be idler rollers or driven rollers to assist in displacing the sheet 1 longitudinally.

Mounted over the carrier sheet 1 on the vibrating table 4 are two longitudinally spaced hoppers 9 and 10 each of which is charged with resin paste 11 comprising a homogeneous mixture of resin, hardener and filler. The resin paste is a homogeneous mixture comprising (in parts by weight): a):21 parts "Polyester 247" sold by Warwick Resins Limited; 71 parts graded sand filler; 0.5 part Cobalt Octoate NL51 accelerator sold by Akzo Chemie U.K. Limited; 2 parts Butanox M50 hardener sold by Akzo Chemie; 8 parts French chalk (slipping agent); orb):- 19 parts "401 B" Resin sold by Freeman Chemicals Limited; 72 parts graded sand filter; 0.4 part Cobalt Octoate NL51 and 0.5 part Dimethylanaline as accelerator; 0.5 part "Triganox 215"; 1 part Perkadox 16; and 2 parts Butanox SA4 all sold by Akzo Chemie U.K.

Limited as hardener; 8 parts French chalk.

Resin paste from the hopper 9 is deposited on to the carrier sheet 1 and the sheet thus loaded carries the paste beneath a blade 12 which screeds the paste to a required depth on the carrier sheet.

A sheet of reinforcing material in the form of glass fibre mat 13 is now applied to the surface of the resin paste 11 which emerges from beneath the screeding blade 12. The mat 13 is drawn from a roll 14 thereof and beneath an idler roller 15 to be deposited on the resin paste for carriage therewith by the sheet 1 over the vibrating table 4. The roller 15 is positioned longitudinally between the hoppers 9 and 10 and resin paste 11 from the hopper 10 is deposited on to the glass fibre mat and resin paste which emerges from beneath the roller 15. The additional resin paste from the hopper 10 together with the originally applied resin paste and reinforcement are carried by the carrier sheet to pass beneath a second blade 16 by which the resin paste is again screeded to a required depth on the carrier sheet.

Downstream of the blade 16, the carrier sheet 1 and its load passes beneath an idler roller 17 by which a plastics cover sheet 18 drawn from a roll 19 is applied to the upper surface of the resin paste to assist informing and maintaining that upper surface.

The composite of sheeting, paste and reinforcements is now drawn between the rollers 5 (which determine the final thickness of the composite as required for the resin bonded sheeting which is formed) and enters the oven 6 where it is supported by the rollers 8. The oven will usually have a temperature in the range of 10'Cto 150 C while the resin paste having a thickness in the order of 3 to 6 mms. is drawn therethrough at a speed in the order of 3 to 6 metres per minute to ensure that the composite sheeting 19 which emerges therefrom is full cured.

During movement of the carrier sheet 1 over the table 4, the loading of the resin paste 11 from the hoppers 9 and 10 onto the sheet 1, and the application of the reinforcing sheet 13 and cover sheet 18, the table 4 is continuously vibrated. The purpose of this vibration is to remove excess air from the resin paste 11 and alleviate voids in the paste which could vary its curing characteristics and detract from the strength of the resin bonded sheeting which emerges from the oven. Such voids could also act to retain water in a product formed from the sheeting so that the product may be susceptible to frost damage. The vibration also serves to wet out the glass fibre mat 13 as it is applied to the surface of the resin paste 11 to ensure that a thorough bonding is achieved between the resin paste and the mat.This vibration is also a convenient means of providing a smooth/fine finish to the upper surface of the paste 11 to the extent that the cover sheet 18 may not be required. The vibration also acts to facilitate the drawing of the resin paste beneath the screeding blades 12 and 16.

The resin bonded sheeting which emerges from the oven 6 can be cut to required lengths by any convenient means such as a flying saw (not shown).

The cutting to length of the sheeting can be effected prior to, or subsequent to, the carrier and cover sheets 1, 18 being peeled from the sheeting or if required the carrier and cover sheets can be retained on the resin bonded sheeting for protection or aesthetic purposes. Where iris intended that, say, the carrier sheet 1 and/or the cover sheet 18 is to be peeled from the resin bonded sheeting before the sheeting is cut to length, the apparatus can be modified so that the carrier sheet 1 and/or the cover sheet 18 is re-circulated and in the form of an endless belt which feeds over the table 4 and through the oven; in this latter modification the roll 2 and/or the roll 19 will of course be omitted.

To ensure that the glass fibre reinforcing mat 13 is thoroughly bonded and wetted into the surface of the resin paste 11 to which it is applied, a laterally displaceable roller (not shown) having its axis disposed substantially longitudinally can be provided between the roller 15 and hopper 11 to reciprocate and roll over the width of the sheet 1 to lightly press the glass fibre mat into the surface of the underlying resin paste.

Preferably the glass fibre mat 13 is embedded within the resin paste 11 substantially symmetrically within the thickness of that paste as it enters the oven 6.

The apparatus as shown in Figure 1 is intended for continuously forming substantially flat resin bonded sheeting. If required however, the substantially flat pre-cured composite which emerges from between the rollers 5 can be moulded into a non-flat profile within the oven 6. This can be achieved by replacing rollers 8 within the oven by formers or moulding plates. One such moulding plate is shown at 20 in Figure 2 and has a preformed profile 21 over which the carrier sheet 1 and its load is drawn to be moulded into the required form. It will be apparent that when the composite load on the carrier sheet 1 is drawn over the profile 21 the resultant resin bonded sheeting will have a corrugated profile. It will also be apparent that by this moulding technique many different profiles can be formed for the sheeting other than corrugated, for example of arcuate lateral section.Usually several moulding plates 20 will be longitudinally spaced within the oven 6 to provide adequate support for the sheeting and if required the moulding of the sheeting into the required form can be progressive until such time as the paste has cured sufficiently to prevent further moulding. As an alternative to the separate moulding plates 20 it is also possible for the sheeting to be moulded by running along appropriately shaped tracks or channels within the oven which provide continuous supportforthe sheeting.

The apparatus shown in Figure 1 can also be modified to continuously form resin bonded sheeting having one or more longitudinally extending rebates or recesses in a surface thereof.

This can be achieved by subjecting the resin paste to a moulding process as will now be described with reference to Figures 1 and 3. The cover sheet 18, roller 17 and upper roller of the pair 5 are removed (and if required the screeding blade 16 can also be removed). The resin paste 11 and reinforcing mat 13 which emerged from beneath the hopper 10 are carried on the sheet 1 beneath a die plate 22 having an aperture 23 through which the resin paste is drawn. The aperture 23 has a profile corresponding to that required of the resin bonded sheeting 18' which is to be formed. It will be seen from Figure 3 that the sheeting 18' is moulded by the die plate 22 to have a pair of longitudinally extending recesses 24 and side rebates 25 in the upper surface thereof while the base of the sheeting has embedded therein the reinforcing mat 13.The die plate 22 is located adjacent to the oven 6 (and indeed may be located within the oven 6) to ensure that the resin paste is sufficiently cured shortly after its extrusion to prevent the paste from slumping and losing its required profile. In the example shown in Figure 3 the carrier sheet 1 is flat so that one face of the resin bonded sheeting which is formed will be correspondingly flat; if required however, the carrier sheet can be provided with longitudinally extending ribs which may serve to provide corresponding recesses or rebates in the opposing surface of the resin bonding sheeting when the carrier sheet is peeled therefrom. This latter proposal may usefully be achieved where the carrier sheet 1 is in the form of an endless belt as previously described.

The resin bonded sheeting 18' as formed with the longitudinally extending recesses 24 can be cut to required sheet lengths and these sheets may readily be assembled to form a structural building panel as shown in Figure 4. To achieve this two identical sheets 18' are fitted together in mirror image of each other so that the respective sets of recesses 24 oppose each other and form cavities therebetween.

The two sheets are adhesively secured or bonded together at their interface to form a hollow structural panel having side channels defined by the opposing sets of rebates 25. These side channels 25 can accommodate joining members for connecting adjacent panels in a wall structure. It will be appreciated that the cavities formed by the recesses 24 can accommodate, for example, load bearing reinforcement such as joists or struts or conduiting.

The cavities can also accommodate insulation material indicated at 26 which, conveniently, is formed by injecting foaming plastics material into those cavities. The ends of the panel can be closed by cover plates or caps which may conveniently be bonded or adhesively secured to the sheets 18'.

The modification shown in Figure 5 primarily concerns the manner in which the glass fibre mat 13 is embedded in the resin paste prior to curing whereby the mat 13 is sandwiched between independantly developed upper and lower layers 1 1a and 1 1b respectively of resin paste which are respectively carried by the cover sheet 18 and the carrier sheet 1. The lower layer 11 b of resin paste is formed as previously discussed by the screeding blade 12 and during movement of the carrier sheet 1 over the vibrating table 4. The upper layer 1 la of resin paste is formed by depositing paste onto the upper surface of a horizontal run of the cover sheet 18 as that sheet is displaced over a second vibrating table 27 to move the paste beneath a screeding blade 28 and form the layer 1 1a to the required thickness.The formation of the paste layer 1 la with the vibration from the table 27 is consequently substantially the same as the formation of the paste layer 1 lib so that the cover sheet 18 acts as a second carrier sheet and accordingly the same advantage (as previously discussed) apply to both layer 1 1a and lit.

From the table 27, the cover sheet 18 passes over support rollers 29 and around an idler (or driven) roller 30 to a run where it overlies the carrier sheet 1 and moves therewith between the rollers 5 and through the oven 6 as previously described. In passing around the roller 30 the cover sheet 18 is inverted so that the paste layer 1 1a (which will adhere sufficiently to the sheet 18) is carried by the sheet 18 to be directed downwardly to oppose and move into contact with the paste layer 1 it. As shown in Figure 5, the glass fibre mat 13 is fed from the roller 15 to be sandwiched between the paste layers 1 lea and 1 1t as they move into contact thereby ensuring that the mat is fully embedded in the resin paste prior to entering the oven for curing.

During vibration of the two resin paste layers 11a and lIt, the filler tends to settle and form a film of resin 31 in the upper surface of the respective vibrating layer. As the upper layer 1 lea of resin paste is inverted its resin film 31 becomes the lower surface which moves into contact with the glass fibre mat 13; this, together with the resin film on the upper surface of the lower layer 1 1t serves to wet-out the mat 13 and ensure that a thorough bond can be achieved between the resin paste and glass fibre reinforcement in the cured sheeting. It will be appreciated that although the technique as above described is advantageous for embedding the reinforcing mat 13 between the two resin paste layers 1 la and 1 1t, it can be applied in the absence of the mat 13 (or other reinforcement) to take advantage of the facility which it provides of ensuring that the resultant sheeting can have both of its surfaces good and substantially free of voids from entrapped air.

Claims

1. A method of continuously forming resin bonded sheeting which comprises progressively moving a base carrier sheet longitudinally, loading on to the carrier sheet resin paste comprising a mixture of resin, hardener and filler; screeding the said paste on the carrier sheet to a layer of required thickness and moving the resin paste with the base carrier sheet whilst curing of the paste is effected.

2. A method as claimed in claim 1 which comprises moving the carrier sheet and resin paste through an oven within which the paste is heated to promote curing.

3. A method as claimed in either claim 1 or claim 2 which comprises subjecting the resin paste carried on the carrier sheet to vibration.

4. A method as claimed in any one of the preceding claims which comprises applying to the screeded paste a reinforcing material.

5. A method as claimed in claim 4 in which the reinforcing material is a fibrous sheet.

6. A method as claimed in either claim 4 or claim 5 which comprises embedding the reinforcing material in resin paste so that it is disposed substantially symmetrically in said paste.

7. A method as claimed in any one of the preceding claims which comprises applying to the resin paste on the carrier sheet a second load of resin paste.

8. A method as claimed in claim 7 which comprises screeding the second load of resin paste to a required thickness.

9. A method as claimed in claim 8 which comprises screeding the second load of resin paste Following its application to the carrier sheet.

10. A method as claimed in claim 8 which comprises screeding the second load of resin paste to a second layer of required thickness and applying that second layer to resin paste on the carrier sheet.

11. A method as claimed in any one of claims 7 to 10 which comprises vibrating the second load of resin paste.

12. A method as claimed in claim 11 which comprises vibrating the second load of resin paste prior to the application thereof to the resin paste on the carrier sheet.

13. A method as claimed in any one of claims 7 to 12 when appendant to claim 4 in which the second load of resin paste is applied to embed the reinforcing material on the carrier sheet.

14. A method as claimed in any one ofthe preceding claims which comprises progressively moving a cover sheet longitudinally and applying that cover sheet on the surface of resin paste remote from the base carrier sheet.

15. A method as claimed in claim 14 when appendantto any one of claims 7 to 13 which comprises applying the second load of resin paste to the cover sheet and moving the second load with the cover sheet to apply that load to the resin paste on the carrier sheet.

16. A method as claimed in claim 15 which comprises applying the second load of resin paste to an upwardly directed surface of the cover sheet; inverting the cover sheet with the second load thereon and applying the second load of resin paste to the resin paste on the carrier sheet.

17. A method as claimed in claim 16 when appendant to claim 10 which comprises screeding the second load while on the upwardly directed surface of the cover sheet.

18. A method as claimed in either claim 16 or claim 17 when appendant to claim 11 which comprises vibrating the second load while on the upwardly directed surface of the cover sheet.

19. A method as claimed in any one of the preceding claims in which at least one of the carrier sheet and cover sheet is plastics.

20. A method as claimed in any one of the preceding claims in which at least one of the carrier sheet and cover sheet is re-circulated whereby that sheet or sheets is peeled from the cured resin bonded sheeting and circulated for re-use with a further load or loads of resin paste.

21. A method as claimed in any one of the preceding claims which comprises passing the paste and carrier sheet beneath a roller to determine the thickness of the subsequently cured resin bonded sheeting formed therefrom.

22. method as claimed in any one of the preceding claims in which the resin bonded sheeting is substantially flat.

23. A method as claimed in any one of claims 1 to 21 which comprises passing the carrier sheet and resin paste thereon over pre-shaped former means which determines the shape (for example corrugated) of the resin bonded sheeting which emerges from the oven.

24. A method as claimed in claim 23 in which the former means progressively moulds the paste into the shape required for the sheeting.

25. A method as claimed in any one of claims 1 to 13 which comprises drawing the resin paste through a pre-shaped aperture to provide a predetermined non-flat profile to the surface thereof remote from the carrier sheet.

26. A method as claimed in any one of the preceding claims which comprises cutting the cured sheeting to form resin bonded sheets of predetermined length.

27. A method of manufacturing a building panel which comprises forming a resin bonded sheet by the method as claimed in claim 26 and during said forming moulding into the sheet at least one longitudinally extending recess; and bonding or adhesively securing to said resin bonded sheet a closure sheet to close the longitudinal extent of said recess.

28. A method as claimed in claim 27 which comprises forming the closure sheet by the method as claimed in claim 26.

29. A method as claimed in claim 28 in which each of the two resin bonded sheets is provided with at least one longitudinally extending recess and which comprises securing the sheets together with the recesses opposing each other to form enlarged cavities.

30. A method as claimed in claim 29 in which the two resin bonded sheets are substantially identical and are secured together substantially in the mirror image of each other.

31. A method as claimed in claim 30 when appendant to claim 4 in which each of the two resin bonded sheets includes reinforcing material and said reinforcing material is substantially symmetrically disposed in the thickness of the panel.

32. A method as claimed in any one of claims 27 to 31 which comprises locating insulation material in at least one cavity formed between a longitudinally extending recess and the closure sheet.

33. A method as claimed in claim 32 which comprises injecting into a said cavity foaming insulation material.

34. A method as claimed in either claim 32 or claim 33 which comprises locating in a said cavity, elements for load bearing or conduiting.

35. A method as claimed in any one of claims 27 to 34 which comprises securing end caps to the sheets to close the ends of said recess.

36. A method of continuously forming resin bonded sheeting as claimed in claim 1 and substantially as herein described.

37. A method of manufacturing a building panel as claimed in claim 27 and substantially as herein described.

38. Resin bonded sheeting or a building panel when formed or manufactured by the method as claimed in any one of the preceding claims.

39. Apparatus for continuously forming resin bonded sheeting by the method as claimed in claim 1 which comprises a base carrier sheet; means for progressively moving the sheet longitudinally; means for loading on to the carrier sheet resin paste which is to comprise the sheeting, and means for screeding the resin paste on the carrier sheet to a layer of required thickness for curing.

40. Apparatus as claimed in claim 39 and comprising an oven through which the carrier sheet is displaced to promote curing of the resin paste thereon.

41. Apparatus as claimed in either claim 39 or 40 and comprising meansforvibrating the resin paste on the carrier sheet.

42. Apparatus as claimed in claim 41 in which the vibrating means comprises a vibrating table over which the carrier sheet is displaced.

43. Apparatus as claimed in any one of claims 39 to 42 and comprising means for feeding reinforcing material on to the screeded resin paste.

44. Apparatus as claimed in claim 43 in which the reinforcing material is in sheet form fed from a roll thereof.

45. Apparatus as claimed in any one of claims 39 to 44 and comprising means for depositing a second load of resin paste on to the resin paste on the carrier sheet.

46. Apparatus as claimed in claim 45 and comprising longitudinally displaceable sheet means onto which the second load of resin paste is applied and transferred thereby to be further deposited on the carrier sheet.

47. Apparatus as claimed in claim 46 in which the sheet means has a longitudinal run with an upwardly directed surface onto which the second load of resin paste is applied and from which run said sheet means is inverted to move with and overlie the carrier sheet for depositing the second load of resin paste onto the resin paste on the carrier sheet.

48. Apparatus as claimed in any one of claims 45 to 47 and comprising means for screeding the second load of resin paste to a required thickness.

49. Apparatus as claimed in claim 48 in which the screeding means is located to screed said second load on the carrier sheet.

50. Apparatus as claimed in claim 48 when appendant to either claim 46 or claim 47 in which the screeding means is located to screed said second load on the sheet means.

51. Apparatus as claimed in any one of claims 45 to 50 and comprising means for vibrating the second load of resin paste.

52. Apparatus as claimed in claim 51 when appendant to either claim 46 or claim 47 in which the vibrating means is located to vibrate the resin paste which is applied to the sheet means prior to the deposition thereof onto the carrier sheet.

53. Apparatus as claimed in claim 52 in which the vibrating means comprises a, or a second, vibrating table over which said sheet means is displaced.

54. Apparatus as claimed in any one of claims 45 to 53 when appendant to claim 43 in which the reinforcing material is fed to become embedded by sandwiching between resin paste on the carrier sheet and the second load of resin paste applied thereto.

55. Apparatus as claimed in any one of claims 39 to 54 and comprising means for feeding a cover sheet on to the surface of the resin paste remote from the carrier sheet.

56. Apparatus as claimed in claim 55 when appendant to claim 46 in which said sheet means is the cover sheet.

57. Apparatus as claimed in any one of claims 39 to 56 and comprising a roller beneath which the resin paste is passed to determine the thickness of the resin bonded sheeting.

58. Apparatus as claimed in any one of claims 39 to 57 in which at least one of the carrier sheet and cover sheet is endless and is re-circulated during the formation of the sheeting.

59. Apparatus as claimed in claim 40 or in any one of claims 41 to 58 when appendant to claim 40 in which the oven houses pre-shaped former means which determines the shape of the sheeting which emerges from the oven.

60. Apparatus as claimed in claim 59 in which the pre-shaped former means progressively moulds the resin paste into the shape required of the sheeting during movement of said paste through the oven.

61. Apparatus as claimed in any one of claims 39 to 55 and comprising a die through which the paste is drawn to provide a predetermined non-flat profile to the surface of the paste remote from the carrier sheet.

62. Apparatus as claimed in claim 61 in which the die through which the paste is drawn provides the paste with at least one longitudinally extending recess.

63. Apparatus as claimed in claim 39 and substantially as herein described with reference to the accompanying illustrative drawings.