WO2002030663A1

WO2002030663A1 - Plastics films, formulations, laminates and methods and apparatus for their manufacture

Info

Publication number: WO2002030663A1
Application number: PCT/AU2001/001268
Authority: WO
Inventors: John Driscoll
Original assignee: Bodydreha Pty Ltd
Priority date: 2000-10-10
Filing date: 2001-10-09
Publication date: 2002-04-18

Abstract

A laminate for use as sarking in buildings comprising a layer of plastics and a layer of metal foil bonded to the plastics by a layer of water based adhesive having subtantially no free moisture. The adhesive is dried to form a contact adhesive having no free moisture prior to bonding of the layers. The plastic material can be made from a formulation of LLDPE, a metallocene catalysed LLDPE, LDPE, HDPE and a fire retardant. The laminate can be produced by an apparatus which comprises feed means (11), adhesive application means (40), adhesive drying means (80), means for forcing the films together (60), rolling means (70) and tensionning means. In another embodiment there is an apparatus for forming a three layered laminate.

Description

PLASTICS FILMS, FORMULATIONS. LAMINATES AND METHODS AMD APPARATUS FOR THEIR MANUFACTURE

TECHNICAL FIELD OF THE INVENTION This invention relates to plastics films, formulations for their manufacture, laminates and methods and apparatus for their manufacture .

The invention has particular but not exclusive application to laminates of the type used for roof and wall sarking or house wrap, and plastics films for such laminates. However, it will be appreciated that the invention is not limited to such use.

BACKGROUND ART Laminates comprising a metal foil layer and a paper layer or paper product layer are commonly used as sarking in buildings for roof insulation or for house wrap in the wall cavity. Typically, the two layers are bonded together by an intermediate layer of hot melt adhesive. Suitable fire rating of such laminates may be achieved by including fire retardant materials in the adhesive. This practice makes the laminate undesirably heavy and undesirably expensive. In order to ameliorate the sagging problem an open mesh reinforcing fabric is also typically included between the metal foil and the paper layer, the reinforcing fabric normally being embedded in the adhesive. Although hot melt adhesive is commonly used for bonding the metal foil layer to the paper layer, it is known to use a water based adhesive, the adhesive being able to dry successfully by evaporation and/or diffusion of the water content through and/or into the paper layer. However, laminates comprising two layers of water impermeable materials bonded together by an intermediate layer of water based adhesive have not been successful, at least not for use as sarking or house wrap. Such laminates have been known to suffer from separation of the layers from one another which results in loss of strength and performance. Attempts at forming a laminate of two water impermeable layers separated by a paper layer have also not achieved the desired bonding strength. One such laminate is disclosed in Australian Patent No. 642742 which describes a laminate proposed for use as a reflective foil insulation comprising a first layer of metal foil bonded to one face of a layer of paper by a layer of water based adhesive intermediate the first metal foil layer and the paper layer and a second layer of metal foil bonded to the other face of the layer of paper by another layer of water-based adhesive intermediate the second metal foil layer and the other face of the paper layer.

One object of the present invention is to provide a laminate formed of two layers of water impermeable materials bonded together by a layer of water based adhesive which overcomes or at least ameliorates the aforementioned delamination problem. Another object is to provide a relatively light weight laminate which has desirable fire retardant properties. Another object is to provide a plastics film adapted to form a layer in a laminate which has improved fire retardant properties. Another object is to provide a plastic film adapted to form a layer in a laminate which has improved strength to weight ratio. Another object is to provide apparatus for manufacturing laminates. Unless the context requires otherwise, formulations set forth in this specification are by weight. Other objects of the invention may become apparent from the following description. In formulations having a range of proportions of constituent ingredients, unless otherwise specified, the proportion of the predominant ingredient is adjusted so that the summation of proportions achieves 100%.

DISCLOSURE OF THE INVENTION With the foregoing in view, this invention in one aspect resides broadly in a laminate for use as sarking in buildings, particularly dwelling houses, including: a layer of plastics material; a layer of metal foil bonded to the layer of plastics material by a layer of water based adhesive having substantially no free moisture . In another aspect, this invention resides broadly in a laminate for use as sarking in buildings, particularly dwelling houses, including: a layer of plastics material; a layer of metallized plastics material bonded to the layer of plastics material by a layer of water based adhesive having substantially no free moisture. In another aspect, this invention resides broadly in a laminate for use as sarking in buildings, particularly dwelling houses, including: a layer of plastics material; a layer of metal foil bonded to the layer of plastics material by a layer of water based adhesive, the water based adhesive having been dried to form a contact adhesive having substantially no free moisture prior to bonding of the layers .

In another aspect, this invention resides broadly in a laminate for use as sarking in buildings, particularly dwelling houses, including: a layer of plastics material; a layer of metallized plastics material bonded to the layer of plastics material by a layer of water based adhesive, the water based adhesive having been dried to form a contact adhesive having substantially no free moisture prior to bonding of the layers .

In another aspect, this invention resides broadly in a method of manufacturing a laminate including the steps of: providing a first film which is substantially water impermeable; providing a second film which is substantially water impermeable; applying a water based adhesive to one face of the first film; drying the water based adhesive to form a contact adhesive; forcing one face of the second film against the one face of the first film whereby the contact adhesive bonds the first and second films together to form a laminate. In one form of the invention, the first film is a layer of plastics material and the second film is a metal foil, while in another form the first film is a layer of plastics material and the second film is a metallized plastics material. Preferably, the water based adhesive is a mixture comprising a suspension of polymer in an aqueous diluent and which forms a contact adhesive upon removal of water from the mixture. More preferably, the adhesive is a PVA type adhesive having about 50% by weight water. Advantageously, this composition may be suitably dried to form a contact adhesive prior to bonding the plastic film to the other water impermeable film.

In yet another aspect, the invention resides broadly in a plastics formulation comprising: a linear low density polyolefin; a linear low density metallocene grade polyolefin in approximately equal quantity with the linear low density polyolefin; a low density polyolefin in the range of 4.5% to 5.5% by weight of the total; a linear carrier in the range of 3.5% to 4.5% by weight of the total, and a fire retardant in the range of 4.5% to 5.5%, the fire retardant being selected to retard the supply of oxygen to the surface of the plastics formulation when exposed to and/or in contact with fire.

Preferably, the polyolefins are selected to provide a film suitable to be laminated to a paper, metal foil or metallized plastics film. The linear carrier of the formulation is preferably provided as a coloured masterbatch which is used with the low density polyolefin in cross-linking of the plastics formulation. The colour of the masterbatch may be selected to identify different plastics film products .

Preferably, the fire retardant is a derivative of ammonium phosphate. In a preferred form, the fire retardant is predominantly ammonium polyphosphate .

In yet another aspect, the invention resides broadly in a plastics film comprising: a linear low density polyethylene in the range of 30% to 42% by weight; a linear low density metallocene grade polyethylene in the range of 39% to 51% by weight; a high density, high molecular weight polyethylene in the range of 5% ± 0.5% by weight; a low density polyethylene in the range of 5% ± 0.5% by weight; a linear carrier in the range of 4% ± 0.4% by weight; and a fire retardant in the range of 4% to 10% by weight.

Preferably, the plastics film comprises: a linear low density polyethylene in the range of 31% to 41% by weight; a linear low density metallocene grade polyethylene in the range of 40% to 50% by weight; a high density, high molecular weight polyethylene in the range of 5% + 0.5% by weight; a low density polyethylene in the range of 5% ± 0.5% by weight; a linear carrier in the range of 4% ± 0.4% by weight; and a fire retardant in the range of 4% to 10% by weight.

More preferably, the plastics film comprises: a linear low density polyethylene in the range of 33% to 39% by weight; a linear low density metallocene grade polyethylene in the range of 42% to 48% by weight; a high density, high molecular weight polyethylene in the range of 5% ± 0.3% by weight; a low density polyethylene in the range of 5% ± 0.3% by weight; a linear carrier in the range of 4% ± 0.3% by weight; and a fire retardant in the range of 4% to 8% by weight.

In one preferred form, the plastics film comprises: a linear low density polyethylene in the proportion of 36% by weight; a linear low density metallocene grade polyethylene in the proportion of 35% by weight; a high density, high molecular weight polyethylene in the proportion of 5% by weight; a low density polyethylene in the proportion of 5% by weight ; a linear carrier in the proportion of 4% by weight; and a fire retardant in the proportion of 5% by weight.

Preferably, the film is co-extruded in two layers, one layer having more fire retardant than the other. The low density polyethylene, the linear carrier and the fire retardant components are preferably maintained at least at the levels described in order that the film retains its desirable properties of strength and fire resistance.

In one example of the invention, a plastics film was formed by coextruding a plastics formulation having a first layer comprising:

36% linear low density polyethylene;

45% linear low density metallocene grade polyethylene;

5% high density, high molecular weight polyethylene; 5% low density polyethylene;

4% linear carrier (blue coloured masterbatch) ; and

5% ammonium polyphosphate fire retardant masterbatch, and a second layer comprising:

34% linear low density polyethylene; 43% linear low density metallocene grade polyethylene;

5% high density, high molecular weight polyethylene;

5% low density polyethylene;

4% linear carrier (blue coloured masterbatch) ; and

9% ammonium polyphosphate fire retardant masterbatch. The film was found to have desirable strength and fire retardant properties. In particular, the plastics film was found to develop sufficient cross-linking to resist cold creep and thus is believed to be suitable for use in laminates as sarking and house wrap. In another aspect the invention resides broadly in a laminate including a layer of plastics film as previously described and a layer of metal foil or a layer of metallised plastics material bonded to said layer of plastics film by a layer of water based adhesive having substantially no free moisture.

In another aspect, this invention resides broadly in apparatus for the manufacture of a laminate comprising a first layer of substantially water impermeable material and a second layer of substantially water impermeable material bonded together, including: first feed means for feeding a first film of substantially water impermeable material from a first roll for forming the first layer; second feed means for feeding a second film of substantially water impermeable material from a second roll for forming the second layer; application means downstream of the first feed means for applying a coating of water based adhesive to one face of the first film; drying means downstream of the application means for removing substantially all free moisture from the coating of water based adhesive; forcing means downstream of the drying means for forcing one face of the second film against the one face of the first film, to form a laminate with the first and second films being bonded by the adhesive; rolling means downstream of the forcing means for forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate. Removal of the free water from the water based adhesive is believed to cause the water based adhesive to become a contact adhesive prior to the second film being forced against the first film.

In another aspect, this invention resides broadly in apparatus for the manufacture of a laminate comprising two layers of material bonded together, including: first feed means for feeding a first film of material from a first roll for forming one layer of the laminate ; second feed means for feeding a second film of material from a second roll for forming another layer of the laminate; third feed means for feeding a third film of material from a third roll for forming an alternative layer to the one or other layer of the laminate; application means downstream of the first feed means for applying a coating of adhesive selectively to one of one face of the first film and one face of the second film; forcing means downstream of the application means for selectively forcing one of one face of the second film against the one face of the first film to form a laminate with the first and second films being bonded by the adhesive and one face of the third film against one face of the first film to form a laminate with the first and third films being bonded by the adhesive; rolling means downstream of the forcing means for forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate.

In another aspect, this invention resides broadly in apparatus for the manufacture of a laminate comprising two layers ■ of material bonded together, including: first feed means for feeding a first film of material from a first roll for forming one layer of the laminate ; second feed means for feeding a second film of material from a second roll for forming another layer of the laminate; third feed means for feeding a third film of material from a third roll for forming an alternative layer to the other layer of the laminate; application means downstream of the first feed means for applying a coating of adhesive selectively to one of one face of the first film and one face of the second film; first forcing means downstream of the application means for forcing one face of the second film against the one face of the first film to form a laminate with the first and second films being bonded by the adhesive; second forcing means downstream of the application means for forcing one face of the third film against one face of the first film as an alternative to the second film to form a laminate with the first and third films being bonded by the adhesive; rolling means downstream of the first and second forcing means for selectively forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate.

Preferably, the first and second feed means (and third feed means where provided) are in the form of rollers which have tensioning means operatively connected thereto and adapted to apply a desired amount of resistance to unrolling thereby applying tension to each of the first and second films respectively (and third film where provided) .

Preferably, the application means includes a set of rollers adapted to apply adhesive to the one face of the first film in a manner similar to that by which the rollers of a flexographic printing machine apply ink to the article to be printed, the water based adhesive being suitably formulated for application in this manner. In a preferred form, the application means includes a reservoir suitably in the form of a trough for holding the water-based adhesive; an adhesive take-up roller arranged such that at least a portion of its roller surface is immersed in use in the adhesive; a trimming roller in operative rolling contact with the adhesive take-up roller whereby adhesive may be transferred from the take-up roller to the trimming roller; an application roller in operative rolling contact with the trimming roller whereby a film of adhesive of predetermined thickness may be transferred from the trimming roller to the application roller; and a driving roller arranged in operative rolling contact with the application roller whereby in use they may pull a film of plastics material or foil therebetween and whereby the application roller may apply adhesive to the one face of the first film. Advantageously, this form of application means applies a suitably thin layer of adhesive to the one face of the first film. In a preferred form the take up roller is much larger than the application roller thus allowing the apparatus to operate at a greater web speed. In this respect the greater diameter allows the take up roller to operate at lower angular velocity for the same peripheral velocity and it is believed that the adhesive holds to the surface of the take up roller better at the lower angular velocity. Preferably, the drying means includes a blower and a heater connected to a duct for directing heated air onto the surface of the water-based adhesive on the one face of the first film, downstream of the application means . Suitably, the drying means is arranged to remove substantially all of the free water therein prior to the film reaching the forcing means so as to produce a contact adhesive extending evenly across the surface of the first film. Suitably, the adhesive is formulated to dry sufficiently in the period of run between the application means and the forcing means upon application of a predetermined amount of heat over a predetermined period. Preferably, the duct is arranged to direct heated air progressively along a length of the first film and evenly across its width. It is also preferred that the duct be arranged to direct heated air in countercurrent fashion to the direction of movement of the first film.

Preferably, the forcing means includes a set of nip rollers arranged to force the first and second films or first and third films together as the case may be. In such form the forcing means also includes guide rollers suitably arranged to guide the relevant films onto and off the nip rollers as required. In such form it is preferred that the nip rollers be driven at a desired speed to pull the first and second or third films therebetween at a suitable linear speed. It is also preferred that the first feed means, the second feed means, the third feed means (where provided) , and the rolling means also be driven via slipping clutches, such that a desired tension is applied to the laminate and/or the first, second and third films as required. In a preferred form the rolling means is driven at a no-load speed which is up to about 5% greater than the speed of the laminate leaving the nip rollers, and preferably between about 1% and 5% greater.

BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood and put into practical effect, reference will now be made to the following drawings which illustrate a preferred embodiment of the invention, and wherein: Fig. 1 is a diagrammatic side elevation of apparatus according to the present invention showing a first roll and alternative second and third feed rolls;

Fig. 2 is a diagrammatic side elevation of apparatus according to the present invention with the third feed roll removed, and

Fig. 3 is a diagrammatic side elevation of apparatus according to the present invention with the second feed roll removed.

DETAILED DESCRIPTION OF THE DRAWINGS The laminating apparatus 10 illustrated in Fig. 1 includes a first feed roller 11 having a frame 12 and a roll of first film 13 mounted thereon for rotation about a first roll axis 14, a second feed roller 15 having a frame 16 and a roll of second film 17 mounted thereon for rotation about a second roll axis 18, and a third feed roller 19 having a frame 20 and a roll of third film 21 mounted thereon for rotation about a third roll axis 22. The feed rollers are all aligned with their axes parallel and are mounted on a concrete floor below an elevated platform 23 which is supported above the floor by a plurality of posts 24a to 24f. As can be appreciated from Figs. 2 and 3, the apparatus is intended for use in the production of a laminate comprising a film from the roll of first film and a film from the roll of second film or alternatively comprising a film from the roll of first film and a film from the roll of third film.

In producing a laminate comprising a first film and a second film ("a first type"), the first film feeds from its roll over a series of guide rollers 26, 27, 28 and 29 which are mounted on the frame assembly in the direction shown as "A", to a bonding station 30 which will be described in more detail later. At the same time film from the roll of second film feeds around a series of guide rollers 36, 37 and 38 to a coating station 40 in which adhesive is applied to one face of the second film as will be described in more detail later. The adhesive for a first type of laminate can be a water based adhesive or any other suitable adhesive. From the coating station the second film enters the bonding station 30. Laminate leaving the bonding station passes over guide rollers 41, 42, 43 and 44 on the way to a collecting station 70 which will be described in more detail later.

In producing a laminate comprising a layer of first film and a layer of third film ("a second type"), the first film passes around guide rollers 51, 52 and 53 before entering the previously mentioned coating station 40 and after leaving the coating station passes around a series of guide rollers 55, 56, 57, 58 and 59 before reaching the series of rollers 26, 27, 28, 41, 42, 43 and 44 mentioned earlier. From roller 44 the first film is directed to a second bonding station 60 from where it travels around a series of guide rollers 66, 67 and 68 before entering the collecting station 46. The arrangement shown in Fig. 3 is intended for producing a laminate comprising a first layer of substantially water impermeable material and a second layer of substantially water impermeable material bonded together by a layer of water based adhesive. For this purpose, the apparatus includes a drying system shown diagrammatically at 80 which is arranged to dry the water based adhesive after application to the first film to form a contact adhesive prior to the film reaching the bonding station 60. The drying system 80 includes a fan and heater assembly shown diagrammatically at 81 having an air inlet 82 and an air outlet 83. A duct also shown diagrammatically at 84 is connected to the air outlet and extends across the full width of the first film over a substantial part of the web run. The duct has a plurality of outlets shown as arrows 85 directed onto the adhesive on the film and the outlets are arranged such that the air is directed counter to the direction of movement of the first film. The apparatus as shown in Fig. 3 is arranged for the production of a laminate comprising a first film of a plastics material from the roll 13 and an aluminium foil from the roll 21 which are bonded together by a water based adhesive of the polyvinyl acetate or polyvinyl alcohol type suitably about 8 gms per square metre of adhesive is applied to the film which dries to about 4 gms per square metre. In order to sufficiently dry the adhesive prior to the film entering the bonding station 60, the temperature of the drying air should be approximately 85 degrees Celsius at a web speed of 75 metres per minute and an air flow rate of about 1000 litres per second.

The coating station 40 is mounted on a stand 110 and includes a trough 111 for holding adhesive 112, a take up roller 113 which is partly immersed along its length in the trough and adapted to pick up adhesive onto its surface as it rotates, a trimming roller 114 which is in rolling contact with the take up roller and adapted to receive therefrom a film of adhesive, an application roller 116 in rolling contact with the trimming roller and adapted to receive therefrom a form of adhesive at a predetermined desirable thickness, and a driving roller in rolling contact with the application roller. The rollers are all aligned with the feed rollers and have their axes parallel thereto. As can be seen in Fig. 2, when producing a first type of laminate, the second film passes between the application roller and the drive roller and in so doing, the application roller applies adhesive to one face thereof prior to the film entering the bonding station 30. Similarly, when producing a second type of laminate, the first film passes between the application roller and the drive roller and in so doing the application roller applies adhesive to one face thereof prior to the film entering the bonding station 60. It will be seen that the pick up roller 113 is almost twice the diameter of the trimming roller, the application roller and the drive roller which are all of similar diameter. Advantageously this allows the film to travel at a greater linear speed and in this respect it is believed that the adhesive holds better to the pick up roller of greater diameter and results in a thinner film being applied to the film than otherwise possible. When producing a laminate of the second type, this is particularly advantageous because a thinner layer of water based adhesive can be more readily dried.

The bonding stations 30 and 60 are similar in many respects although the positioning of the various guide rollers differs in order to guide the relevant film from the relevant source to the relevant destination. Bonding station 30 has a set of nip rollers 131 and 132 which force the two films together and bonding station 60 has similar rollers 161 and 162. However, in the case of bonding station 60, when the previously mentioned water based adhesive is used, nip roller 161 is heated to approximately 80 degrees Celsius in order to sufficiently melt the resulting contact adhesive as the first film wraps that roller to form the desired bond. Nip roller 162 may also be heated if desired. Similarly, nip roller 132 maybe heated for some applications if desired.

After leaving the bonding station 30 or 60 as the case may be, the laminate is formed into a roll about a roll former at collecting station 70. The collecting station includes two adjacent support rollers 71 and 72 on which the roll former is driven. The roll is formed by placing the former in the recess between the two rolls and applying downward pressure by a pneumatic ram 73 in order that rotary drive is transferred from the drive roller 72 to the former. It will be appreciated that as the roll grows in diameter, the peripheral speed remains constant.

The application station and the two bonding stations are driven by an electric motor 130 via chains and sprockets (not shown) . Pneumatically operated brakes are provided on the shafts of the three feed rollers for maintaining sufficient tension on the respective films. Similarly a pneumatic brake (not shown) mounted adjacent the end of the roller is provided on the collecting roller 71 and can be adjusted to ensure that sufficient tension is maintained on the laminate as desired. In this respect, the collecting roller 71 is driven at a peripheral speed which is approximately 5% faster than the speed of the laminate leaving bonding station 30 or 60 to ensure that the laminate is tensioned to an extent whereby a tight roll is created.

If desired, a reinforcing mesh such as that known as CRENET or another layer may be included in the laminate by adding a further film layer in an appropriate place. Although the invention has been described with reference to one or more specific examples, it will be appreciated by persons skilled in that the invention may be embodied in many other forms within the broad scope and ambit of the invention as defined in the appended claims .

Claims

1. A laminate for use as sarking in buildings, including: a layer of plastics material; a layer of metal foil bonded to said layer of plastics material by a layer of water based adhesive having substantially no free moisture .

2. A laminate for use as sarking in buildings, including: a layer of plastics material; a layer of metallized plastics material bonded to said layer of plastics material by a layer of water based adhesive having substantially no free moisture.

3. A laminate for use as sarking in buildings, including: a layer of plastics material; a layer of metal foil bonded to said layer of plastics material by a layer of water based adhesive, said water based adhesive having been dried to form a contact adhesive having substantially no free moisture prior to bonding of the layers.

4. A laminate for use as sarking in buildings, including: a layer of plastics material; a layer of metallized plastics material bonded to said layer of plastics material by a layer of water based adhesive, said water based adhesive having been dried to form a contact adhesive having substantially no free moisture prior to bonding of the layers .

5. A method of manufacturing a laminate including the steps of: providing a first film which is substantially water impermeable; providing a second film which is substantially water impermeable; applying a water based adhesive to one face of the first film; drying said water based adhesive to form a contact adhesive; forcing one face of said second film against said one face of said first film whereby said contact adhesive bonds said first and second films together to form a laminate.

6. A method according to Claim 5, wherein said first film is a layer of plastics material and said second film is a metal foil.

7. A method according to Claim 5, wherein said first film is a layer of plastics material and said second film is a metallized plastics material.

8. A method according to any one of Claims 5, 6 and 7, wherein said water based adhesive is a mixture comprising a suspension of polymer in an aqueous diluent which forms a contact adhesive upon removal of water from the mixture .

9. A method according to any one of Claims 5 to 8 , wherein said water based adhesive is a PVA type adhesive having 50% by weight water.

10. A plastics formulation comprising: a linear low density polyolefin; a linear low density metallocene grade polyolefin in approximately equal quantity with the linear low density polyolefin; a low density polyolefin in the range of 4.5% to 5.5% by weight of the total ; a linear carrier in the range of 3.5% to 4.5% by weight of the total, and a fire retardant in the range of 4.5% to 5.5%, the fire retardant being selected to retard the supply of oxygen to the surface of the plastics formulation when exposed to and/or in contact with fire.

11. A plastics formulation according to Claim 9, wherein said fire retardant is a derivative of ammonium phosphate.

12. A plastics formulation according to Claim 10, wherein said fire retardant is predominantly ammonium polyphosphate.

13. A plastics formulation according to any one of Claims 9 to 12, wherein said polyolefins are selected to provide a film suitable for bonding to a layer of paper, metal foil or metallized plastics film.

14. A plastics formulation according to any one of Claims 9 to 12 , wherein said linear carrier is provided as a coloured masterbatch.

15. A plastics formulation according to Claim 14, wherein the colour of said coloured masterbatch is selected to identify different products .

16. A plastics film comprising: a linear low density polyethylene in the range of 30% to 42% by weight; a linear low density metallocene grade polyethylene in the range of 39% to 51% by weight; a high density, high molecular weight polyethylene in the range of 5% ± 0.5% by weight; a low density polyethylene in the range of 5% ± 0.5% by weight; a linear carrier in the range of 4% ± 0.4% by weight; and a fire retardant in the range of 4% to 10% by weight.

17. A plastics film according to Claim 16, wherein said linear low density polyethylene is in the range of 31% to 41% by weight, said linear low density metallocene grade polyethylene is in the range of 40% to 50% by weight, said high density, high molecular weight polyethylene is in the range of 5% ± 0.5% by weight, said low density polyethylene is in the range of 5% 1 0.5% by weight, said linear carrier is in the range of 4% ± 0.4% by weight, and said fire retardant is the range of 4% to 10% by weight.

18. A plastics film according to Claim 16, wherein said linear low density polyethylene is in the range of 33% to 39% by weight, said linear low density metallocene grade polyethylene is in the range of 42% to 48% by weight, said high density, high molecular weight polyethylene in the range of 5% ± 0.3% by weight, said low density polyethylene is in the range of 5% ± 0.3% by weight, said linear carrier is in the range of 4% + 0.3% by weight, and said fire retardant is in the range of 4% to 8% by weight.

19. A plastics film according to claim 16, wherein said linear low density polyethylene is in the proportion of 36% by weight, said linear low density metallocene grade polyethylene is in the proportion of 45% by weight, said high density, high molecular weight polyethylene is in the proportion of 5% by weight, said low density polyethylene is in the proportion of 5% by weight, said linear carrier is in the proportion of 4% by weight, and said fire retardant is in the proportion of 5% by weight.

20. A plastics film according to any one of Claims 16 to 19, co- extruded in two layers, one layer having more fire retardant than the other .

21. A plastics film according to Claim 20, wherein one layer comprises : 36% linear low density polyethylene;

45% linear low density metallocene grade polyethylene;

5% high density, high molecular weight polyethylene;

5% low density polyethylene;

4% linear carrier (blue coloured masterbatch) ; and 5% ammonium polyphosphate fire retardant masterbatch, and the other layer comprises :

34% linear low density polyethylene;

43% linear low density metallocene grade polyethylene;

4% linear carrier (blue coloured masterbatch) ; and

9% ammonium polyphosphate fire retardant masterbatch.

22. A laminate including a layer of plastics film according to any one of Claims 16 to 21 and a layer of metal foil or a layer of metallised plastics material bonded to said layer of plastics film by a layer of water based adhesive having substantially no free moisture.

23. Apparatus for the manufacture of a laminate comprising a first layer of substantially water impermeable material and a second layer of substantially water impermeable material bonded together, including: first feed means for feeding a first film of substantially water impermeable material from a first roll for forming the first layer; second feed means for feeding a second film of substantially water impermeable material from a second roll for forming the second layer; application means downstream of the first feed means for applying a coating of water based adhesive to one face of the first film; drying means downstream of the application means for removing substantially all free moisture from the coating of water based adhesive; forcing means downstream of the drying means for forcing one face of the second film against the one face of the first film, to form a laminate with the first and second films being bonded by the adhesive; rolling means downstream of the forcing means for forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate.

24. Apparatus for the manufacture of a laminate comprising two layers of material bonded together, including: first feed means for feeding a first film of material from a first roll for forming one layer of the laminate ; second feed means for feeding a second film of material from a second roll for forming another layer of the laminate; third feed means for feeding a third film of material from a third roll for forming an alternative layer to the one or other layer of the laminate; application means downstream of the first feed means for applying a coating of adhesive selectively to one of one face of the first film and one face of the second film; forcing means downstream of the application means for selectively forcing one of one face of the second film against the one face of the first film to form a laminate with the first and second films being bonded by the adhesive and one face of the third film against one face of the first film to form a laminate with the first and third films being bonded by the adhesive; rolling means downstream of the forcing means for forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate.

25. Apparatus for the manufacture of a laminate comprising two layers of material bonded together, including: first feed means for feeding a first film of material from a first roll for forming one layer of the laminate ; second feed means for feeding a second film of material from a second roll for forming another layer of the laminate; third feed means for feeding a third film of material from a third roll for forming an alternative layer to the other layer of the laminate; application means downstream of the first feed means for applying a coating of adhesive selectively to one of one face of the first film and one face of the second film; first forcing means downstream of the application means for forcing one face of the second film against the one face of the first film to form a laminate with the first and second films being bonded by the adhesive; second forcing means downstream of the application means for forcing one face of the third film against one face of the first film as an alternative to the second film to form a laminate with the first and third films being bonded by the adhesive; rolling means downstream of the first and second forcing means for selectively forming the laminate into a roll; and tensioning means operatively connected to the rolling means for maintaining a desired amount of tension on the laminate.

26. Apparatus according to Claim 23, wherein said first and second feed means include rollers and tensioning means are operatively connected to said rollers, said tensioning means being adapted to apply a predetermined resistance to unrolling.

27. Apparatus according to Claim 24 or Claim 25, wherein said first, second and third feed means include rollers and tensioning means are operatively connected to said rollers, said tensioning means being adapted to apply a predetermined resistance to unrolling.

28. Apparatus according to any one of Claims 23 to 27, wherein said application means includes a set of rollers adapted to apply adhesive to the one face of the first film in a manner similar to that by which the rollers of a flexographic printing machine apply ink to the article to be printed.

29. Apparatus according to Claim 28, wherein said application means includes a trough for holding the water-based adhesive, an adhesive take-up roller arranged such that at least a portion of its roller surface is immersed in use in the adhesive, a trimming roller in operative rolling contact with the adhesive take-up roller whereby adhesive may be transferred from said take-up roller to said trimming roller, an application roller in operative rolling contact with said trimming roller whereby a film of adhesive of predetermined thickness may be transferred from said trimming roller to said application roller, and a driving roller arranged in operative rolling contact with said application roller whereby in use they may pull a film of plastics material or foil therebetween and whereby said application roller may apply adhesive to the one face of the first film.

30. Apparatus according to Claim 28, wherein said take up roller is substantially larger than said application roller.

31. Apparatus according to any one of Claims 23, 26, 28, 29 or 30. wherein said drying means includes a blower and a heater connected to a duct for directing heated air onto the surface of the water-based adhesive on the one face of the first film, downstream of said application means, said drying means being selected and arranged to remove substantially all of the free water from the water based adhesive prior to the film reaching said forcing means so as to form a contact adhesive extending evenly across the surface of the first film.

32. Apparatus according to Claim 31, wherein said duct is arranged to direct heated air progressively along a length of the first film and evenly across its width.

33. Apparatus according to Claim 32, wherein said duct is arranged to direct heated air in countercurrent fashion to the direction of movement of the first film.

34. Apparatus according to Claim 23, wherein said forcing means includes a set of nip rollers arranged to force the first and second films together.

35. Apparatus according to Claim 25, wherein said first forcing means includes a set of nip rollers arranged to force the first and second films together and said second forcing means includes a set of nip rollers arranged to force the first and third films together.

36. Apparatus according to Claim 23 wherein said first feed means , said second feed means and said rolling means are driven via slipping clutches whereby a predetermined tension is applied to the laminate and/or the first and second films .

37. Apparatus according to Claim 24 or Claim 25, wherein said first feed means, said second feed means, said third feed means and said rolling means are driven via slipping clutches whereby a predetermined tension is applied to the laminate and/or the first, second and third films.

38. Apparatus according to Claim 36 or Claim 37, wherein said rolling means is driven at a no-load speed which is between about 1% and about 5% greater than the speed of the laminate leaving the nip rollers.

39. Apparatus as hereinbefore described with reference to any of the accompanying drawings .

Dated this 9^th day of October, 2001

BODYDREHA PTY LTD

By its Patent Attorneys AHEARN FOX