AU601330B2 - Improved translucent cladding construction - Google Patents

Description

6 0 3 F®ef: 51404 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int. Class Application Number: PI8214 Lodged: 13 May 1988 0 Accepted: Published: Priority: Related Art: Name and Address of Applicant: Hooper Bailie Associated Limited t/a W.J. Manufacturing Company 88 Christie Street St. Leonards New South Wales 2065

AUSTRALIA

Actual Inventor: NOT KNOWN Address for Service: Spruson Ferguson, Patent Attorneys, Level 33 St Martins Tower, 31 Market Street, Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Improved Translucent Cladding Construction The following statement is a full description of this invention, including the best method of performing it known to me/us REPRINT OF RECEIPT -007323 09/05/.8 5815/2 kii The present invention relates to an improved transparent or translucent cladding construction.

It is often desirable to provide a cladding for a building framework which has good light transmission characteristics so as to, for example, reduce lighting electricity costs in warehouses etc, or to allow entry of natural light for the propagation of plants, vegetables, flowers etc (ie "green houses").

Originally, glazing was employed for this purpose. However, glass presents difficulties in manufacture, handling, installation, is inflexible and brittle, and is thereby generally not cost effective and generally impractical to use for this purpose.

Modern technology has developed synthetic materials which are generally able to simulate the light transmissability and other advantages o of glass, and which substantially overcome the disadvantages of glass.

SThat is, synthetic materials can be easily produced in lengths having ot practically any desired cross-sectional profile, can be handled with oo relative safety, and are "workable" to allow for many alternate Sinstallation methods.

°o°o However, an important disadvantage of synthetic translucent cladding 0 is its relatively short service life. That is, translucent cladding is generally only able to withstand exposure to external climatic conditions o oo °O for a relatively short period of time before deterioration of its surface and consequential reduction of light transmissability becomes evident.

It is known to produce translucent cladding from glass-reinforced oo: polyester resins (GRP) used, for example, in roof-lights and wall panels etc. Initially, This type of sheeting has good light transmission characteristics, however it is susceptible to deterioration due to weathering of the outer surface. That is, the resin can experience water erosion, and glass fibres near the surface of the GRP act as "wicks", promoting penetration of water, resulting in a marked reduction in light transmission and in mechanical strength.

Presently available translucent cladding has been developed to provide a low cost and simple method of providing natural lighting to a variety of building structures whilst continuing to weatherproof the structure.

A variety of translucent reinforced, or non-reinforced plastic sheets in a variety of configurations and types have been used for many and various appli:ations, but have been unable to maintain a high level of light transmission over time when exposed to solar radiation and other KLN/0755b -2ji harsh climatic conditions. The ultimate failure of such sheets is excessive reduction of light transmission through discolouration or through surface erosion.

With reinforced types of sheet, failure occurs when reinforcing fibres become exposed through the surface of the sheet. Various methods of providing a barrier to this form of premature failure to thereby extend the initial light transmission characteristics of th2 product have to date only been partially successful.

For example, GB patent no. 1 517 205 (filed 17 October 1975) discloses a method of adhering a variety of thicknesses of synthetic thermoplastics material (Melinex 301 to the exposed surface of the GRP sheeting during the manufacturing process.

Although this method provides an initial barrier to climatic :oOo elements, a number of disadvantages have become evident.

a 0 n0 o Within approximately two years from initial outdoor exposure, a 0 "haze" appears on the surface of the thermoplastics material which is 0ooo0 caused by micro-crazing. This haze reduces the effective light aoo,0 transmission of the product.

00 0o Further, with continuous exposure, the synthetic thermoplastic coating can become completely eroded and thereby allow water to penetrate into the glass elements in the sheeting, rapidly accelerating the loss of light transmission.

o, Other types of coatings are also known which, also exhibit deterioration of the sheet within five years of exposure to normal weather conditions indicating that the coating has become too thin thereby allowing water to penetrate the GRP sheeting.

Another commonly known and used process to improve the performance of i GRP sheeting requires the insertion of a fine veil of glass on either side of the main glass reinforcement. The fine veil of glass is usually formed during the manufacturing process of the QR~- sheeting.

This process theoretically maintains a separation between the individual glass reinforcing fibres, and the external exposed surface of the sheet, thus creating a resin barrier to prevent water penetrating into into the glass elements in the sheeting, rapidly accelerating the loss of light transmission.

While the method provides some degree of initial protection, during the process of manufacture, the glass veil tends to move very close to the surface of the sheeting where it is under tension. The outer resin layer can therefore be extremely thin, and in a relatively short time can be KLN/0755b -3- ,L eroded allowing water to penetrate into the main glass fibre reinforcement, thus accelerating loss of light transmission and ultimate failure. Light transmission loss is significant within a relatively short period of time (approximately 5 years).

A still further known process of improving the service life of GRP sheeting requires providing the base GRP sheet with a predetermined thickness of resin. The resin layer is formed simultaneously with the production of the base sheeting material. The coating is formulated from high performance resins which are able to provide long service life in exposed conditions by providing a controlled thickness barrier between the exposed surface and the glass roving reinforcement.

However, this type of GRP sheeting protection presents manufacturing difficulties. That is, the process involves simultaneously attempting to chemically react two significantly different chemical components and to provide assurance of complete chemical cure and bond. The process is expensive, and the ultimate performance thereof does not appear to show any consistent improvement over other known types of protection.

A still further known process requires the adhesion of a polyvinyl fluoride film of varying thicknesses to the outer surface of a typical GRP sheeting.

Polyvinyl fluoride film is an inert material which provides a controlled thickness barrier to the outer surface of the GRP sheet, is known to be resistant to ultra-violet degradation and is extremely resistant to environmental attack from the elements, and a variety of chemicals.

However, polyvinyl fluoride tends to be incompatible with the the typical polyester resins, and unsuitable for the manufacturing processes, used in making GRP sheeting. Although an adequate bond therebetween can be achieved, this type of construction usually results in premature delamination from the surface of the GRP sheeting within approximately three years.

Although present technologies have improved the service life of various translucent panels through the use of coatings and/or protection layers, it would be advantageous to further improve the service lives of translucent cladding.

It is the object of the present invention to overcome or substantially ameliorate the problems and/or disadvantages of the prior art.

In one broad form the present invention provides a translucent or opaque building or cladding sheet comprising: KLN/0755b -4a plastic material base sheet; and a laminate heat sealed to at least one surface of said base sheet; said laminate comprising at least one polyvinyl fluoride film, and at least one polyester film; and wherein one of said polyester films is adjacent to said base sheet and one of said polyvinyl fluoride films exposed.

In a further broad form, the present invention provides a method of manufacturing a translucent or opaque cladding sheet, said method comprising: forming a plastic material base sheet; forming at least one laminate comprising at least one polyvinyl fluoride film and at least one polyester wherein with one surface of said laminate is polyvinyl fluoride and the other surface is polyester; positioning said laiminate so that said other surface abuts said base sheet; and heat sealing said laminate to said base sheet.

A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 is a schematic exploded perspective view of the component layers of the present invention.

Figure 2 is a schematic perspective view of a process of manufacturing the present invention.

There is depicted in the figures an improved construction for a translucent cladding sheet The sheet 10 comprises a base sheet 11 and a laminate 12 heat sealed to one or both surfaces of the base sheet 11. i The laminate 12 comprises a polyvinyl fluoride film 13 (most suitably "Tedlar" (TM)designated "TUT 10 BGI") and a co-extruded polyester film 14 (most suitably "Melinex 301" (TM) which best exhibits the unique properties of providing a heat sensitive adhesive layer). The polyester film 14 is adapted to provide an adhesive base between the laminate 12 and the base sheet 11. The two layers (13 and 14) of the laminate 12 is formed having an adhesive inter-layer which is necessarily resistant to breakdown through exposure to heat, solar radiation and other environmental conditions.

The laminate 12 is manufactured separately from the base sheet 11, and is then itself laminated to the base sheet 11 during or after the manufacturing process thereof.

The polyester film 14 "Melinex 301") is laminated to the polyvinyl fluoride film 13 at a temperature of approximately 60° to KLN/0755b 1

;I

i ii a o c

I

and at a pressure of approximately 6-10 bars. The thickness of each of the PVF films 13 is approximately 20 to 30 microns and of each of the polyester films 14 is approximately 12 to 25 microns.

The laminate 12 is laminated to the base sheet 11 at a temperature of approximately 700 to O110 0 C. In the lamination process the base sheet 11 and laminate 12 are held in constant contact by a series of male and female dies until gelation of the base sheet 11 occurrs.

It is envisaged that the laminate 12 will be used in conjunction with a base sheet 11 being a glass reinforced polyester material, or any other translucent plastics material known in the art.

A method of manufacturing the improved sheet construction 10 of the present invention is depicted in Figure 2.

A bottom carrier film 20 in a continuous roll is fed in the apparatus 21. A liquid resin 22 is applied to the bottom carrier film 20 whereupon a cut fibreglass reinforcement 23 is applied onto the liquid resin 22 to form a reinforcement/resin matrix.

A top carrier film 24 and the preformed protective laminate 12, S together in a continuous roll, then covers the reinforcement/resin matrix.

This sandwich construction is fed into the forming apparatus comprising formers 26 and ovens 27 wherein adhesion lamination) of the protective laminate 12 to the base sheet 11 occurs.

The composite laminate sheet 10 exits the forming apparatus 25 and is then cut to size and stacked for delivery.

The principal application of the present invention is to provide a protective layer to translucent sheeting products which will provide an extension to the light transmission properties of the sheeting products, and perhaps as much as double the service life of present commonly used S" translucent cladding (that is, up to approximately 20 years). Further, the present translucent cladding construction could extend the useful period, before, ultimate failure of the sheeting due to water penetration, to years or more.

The invention provides a combination of proven adhesion properties between the base GRP sheet panel (or any other translucent sheet) and the inner layer of the laminate coating the polyester film 14), and a barrier to environmental elements such as ultra-violet attack by provision of the outer layer of the laminate the polyvinyl fluoride film 13).

The known individual performance characteristics of the polyester film 14, and the polyvinyl fluoride film 13, and combined in a heretobefore unknown construction which may provide a considerable extension to the KLN/0755b effective life of typical translucent panel through the maintenance of initial light transmission and weathering properties.

i Translucent cladding provided with the present novel construction may be used, for example, in conjunction with a framework for enclosing an area used for the propagation of plants, vegetables, flowers, that is, in a form of greenhouse.

The base sheet 11 provides a solid barrier to the elements, while the coating laminate 12) provides a barrier to the base sheet 11 to reduce typical rate of deterioration of light transmission.

The present construction of translucent cladding could also be used in a manufacturing process incorporating use of corrosive chemicals.

The process could be encapsulated with panels coated on both sides in accordance with the present invention, said coating to provide protection to the panels from the environment and resistance to the process (e.g.

planting works, etc).

1 i K' -0755b

Claims (16)

1. A translucent or opaque building or cladding sheet comprising: a plastic material base sheet; and a laminate heat sealed to at least one surface of said base sheet; said laminate comprising at least one polyvinyl fluoride film, and at least one polyester film; and wherein one of said polyester films is adjacent to said base sheet and one of said polyvinyl fluoride films is exposed.

2. The sheet of claim 1 wherein said laminate comprises one only polyvinyl fluoride film, and one only polyester film.

3. The sheet of claims 1 or 2 wherein said polyvinyl fluoride film is Tedlar (TM).

4. The sheet of claims 1, 2 or 3 wherein said polyester film is Melinex 301 (TM). So o The sheet of any one of claims 1 to 4 wherein said laminate has °O o adhesive interlayers between said films. oaoo° 6. The sheet of any one of claims 1 to 5 wherein said polyvinyl fluoride film is between 20 and 30 microns thick. 00o 0, 7. The sheet of any one of claims 1 to 6 wherein said polyester a film is between 12 and 25 microns thick.

8. The sheet of any one of claims 1 to 7 wherein said base sheet comprises upper and lower carrier films with a reinforcement/resin matrix therebetween.

9. The sheet of any one of claims 1 to 8 wherein said laminate is provided on one surface only of said base sheet. The sheet of any one of claims 1 to 8 wherein laminate is provided on both surfaces of said base sheet.

11. A method of manufacturing a translucent or opaque cladding sheet, said method comprising: forming a plastic material base sheet; forming at least one laminate comprising at least one polyvinyl fluoride film and at least one polyester wherein one surface of said laminate is polyvinyl fluoride, and the other surface is polyester; and heat sealing said laminate to said base sheet.

12. The method of claim 1 wherein said laminate is preformed with adhesive interlayers.

13. The method of claims 11 or 12 wherein said laminate is formed at a temperature of 60 to 80 C and at a pressure of 6 to 10 bars.

14. The method of claims 11, 12 or 13 wherein said polyvinyl KLN/O755b ~-AM fluoride film is 22 to 30 microns thick. The method of any one of claims 11 to 14 wherein said polyester film is 12 to 25 microns thick.

16. The method of any one of claims 11 to 15 wherein said laminate is laminated to said base sheet at a temperature of 70 to 110 C and wherein said laminate and said base sheet are held in constant contact by male and female die means during said lamination.

17. The method of any one of claims 11 to 16 wherein said base sheet is formed by applying a fluid resin to a lower carrier film, applying reinforcement rovings to said resin to form a reinforcement/resin matrix, and covering said matrix with an upper carrier film.

18. The method of claim 17 wherein said upper carrier film is dispensed onto said matrix from a roll together with said laminate, and said laminate is laminated to said base sheet as said base sheet gelatinises.

19. The method of any one of claims 11 to 17 wherein laminate is laminated to both sides of said base sheet.

20. A method of manufacturing a translucent or opaque cladding sheet construction as hereinbefore described with reference to, and as shown in the accompanying drawings.

21. A translucent or opaque building or cladding sheet as hereinbefore described with reference to, and as shown in the accompanying SO", drawings. DATED this EIGHTH day of MAY 1989 e Hooper Bailie Associated Limited t/a W.J. Manufacturing Company Patent Attorneys for the Applicant SPRUSON FERGUSON KLN/0755b -9-