AU4746699A - A laminate material - Google Patents

Description

1, i

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: 47466/99 Lodged: 8 Complete Specification Lodged: Accepted: Class Int. Class September 1999 Published: Priority: PP 5746 filed on 8 September 1998 Related Art: Applicant(s): AMATEK LIMITED 004 093 092) 6 THOMAS STREET CHATSWOOD NSW 2067

AUSTRALIA

Address for service in Australia: PHILLIPS ORMONDE FITZPATRICK 367 Collins Street MELBOURNE VICTORIA 3000 Tel: (03) 9614 1944 Fax: (03) 9614 1867 Attorney Code: PO Complete Specification for the invention entitled: "A LAMINATE MATERIAL" Our Ref: IRN 542156 The following statement is a full description of this invention, including the best method of performing it known to applicant: N:DJH\PA47466-99B.doc9/28/99 A LAMINATE MATERIAL The present invention relates to a laminate material. The invention has been developed especially for building insulation and is herein described in that context. However, the invention has broader application and may also be used for sarking or decorative purposes and is therefore not limited to that particular use.

It is well known to provide a laminate material which includes a metal foil layer as insulation in a roof cavity. Typically the metal foil is located on an outer surface of the laminate and the laminate is installed with the foil facing either outwardly or inwardly to provide a thermal barrier. The laminate may also provide a fire retardant layer which is typically a hotmelt adhesive and structural components such as a kraft paper backing for the foil and a reinforcing fibrous layer. The insulating laminate may be used by itself or may be used as a support for bulk insulation blankets or the like.

In the past, it has been found that such laminates are prone to degradation. For example, the laminates have been found to degrade particularly upon exposure to corrosive environments such as those that exist in ,poultry farms. The degradation of the laminate can be unsightly even if it does not affect the insulating properties of the laminate and this can be a particular problem as the inner surface of the laminate is often exposed, particularly in industrial environments.

An aim of the present invention is to provide a laminate material of the 0 above type which is more durable and has improved aesthetic qualities.

In its broadest terms, the present invention relates to a laminate sheet .e S 25 including a substrate incorporating a layer of metal foil, and a UV resistant film bonded to said substrate.

Previous insulating laminated sheets incorporated unstabilised film, such as biaxially oriented polypropylene films These films were considered suitable for use in the insulating material as the laminates are normally installed in roofing and accordingly not exposed to direct sunlight.

However, the applicant surprisingly has found that a UV resistant (or stabilised) film can substantially inhibit degradation of the film and accordingly increase the CAP-542156.doc 24109)99 1 surface life of the insulation. The applicant has found that, even under relatively low UV penetration, such as that which results from reflective light, it can seriously impact on the service life of the laminate material, particularly when it is exposed in corrosive environments.

Preferably, the UV resistant film is formed from a polymeric material which is preferably selected from polypropylene, polyethylene, polyester, PVC or similar material having a thickness of between 10pm and 200pm.

Preferably, the UV resistant film is made resistant to UV rays by the incorporation of UV stabilisers. These UV stabilisers are preferably organic compounds and protect polymeric and other light sensitive materials from degradation by sunlight and artificial sources of UV. The UV stabilisers may take various forms including UV absorbers, hindered amines, nickel chelates, hindered phenols, and aryl esters.

Many polymers, such as polyethylene, polypropylene and polyester S. 15 degrade quite rapidly when exposed to sunlight under the process of photooxidation as a result of UV absorbing chromphores which are contained in the polymers. These chromphores are found in the catalyst residues, polymer oxidation products, processing aids, colourants and the like which are used in the commercial production of the polymer. In the presence of excess of oxygen, photooxidation causes increased concentration of hydroperoxides to occur which cleave homolytically by absorption of thermal or actinic energy to O yield additional radicals. UV stabilisers can retard the initiation of photooxidation by additives that function by photophysical mechanisms such as SUV absorption and quenching of photoexcited chromophores.

In a preferred form, the UV stabiliser is in the form of a hindered amine stabiliser, (HALS) which are derivatives of 2, 2, 6, tetramethyl piperidine.

Preferably the HALS contain the group represented by the following formula: CAP.542156 doc 24109/99 HALS are a highly active stabiliser and may be used in a wide variety of substrates subject to photooxidation, such as polypropylene, styremic polymers and polyurethane. Whilst not known for certain it is considered that the HALS function primarily as light-stable antioxidants in which the hindered amine and its oxidation product function as radical scavengers. The HALS are effective in low concentration and preferably are used in concentration of 0.05 5% by weight.

In one particularly preferred form, the UV stabiliser uses the formula:

N--(CH

2 )n-N N N SN CH 3

CH

3

CH

3 H CH 3

CH

3 H- CH 3

H

2

N-CCH

2

CCH

3

CH

3

CH

3

CH

3

CH

3

CH

3

CH

3 n UV stabilisers of this class are sold under the trade name CHIMASORB 944. Other similar UV stabilisers are sold under the trade names TINUVIN 144, TINUVIN 770, TINUVIN 292 and TINUVIN 622CD.

*Preferably, the metal foil is located on one outer surface of the laminate and the UV resistant film is located on the other. In use, the UV resistant film 15 may form the lower or upper surface of the laminate and is often exposed, particularly in industrial environments. A further advantage of the film of the present invention is that it may be coloured, so as to improve the aesthetic appeal of the laminate. For example, the UV resistant film may be white so as to give the appearance of a traditional ceiling. Of course it is to be appreciated 20 that other colours may be used. A further advantage of the UV resistant film is that when it is formed from a plastic, it may be easily cleaned.

Preferably the UV resistant film is cast or blown as this allows the use of custom additives for colour and UV protection.

Preferably at least two adjacent layers of the laminate are bonded together by a flame retardant adhesive. Typically this adhesive is hotmelt and applied by reverse roll coating. Preferably the adhesive is based on chlorinated paraffin and filler with additives promoting adhesion and cohesion. The flame retardant adhesive most preferably is a chlorinated paraffin containing antimony CAP-542158.doc 24/09/99 oxide as a synergistic flame retardant compound dispersed or incorporated therein.

In one form, the film may be applied directly to the adhesive to form the laminate. However to further improve the durability of the laminate, it is preferable that a barrier is provided between the hotmelt adhesive and the UV resistant film to inhibit the components of the flame retarding hotmelt reacting with the UV stabilisers. The flame retardant may be prone to release components such as hydrogen chloride which may react with the UV stabilisers in the film. The use of the barrier retards the penetration of the flame retardant components into the UV resistant film.

In one form, the barrier may be in the form of a polypropylene extrudate.

Preferably the extrudate is applied at a thickness of approximately 30g/m 2 although higher grammages of extrudate may be used. Alternatively, the polypropylene may be replaced by other polymers which may adhere to the film and reinforcing weave. However depending on the polymers in these components, other extrusion polymers and copolymers may be used.

Furthermore instead of an extrudate, a dry laminating adhesive process may also be used.

In another form, the UV resistant film is bonded to a backing sheet. In a preferred form, the backing sheet is kraft paper having a weight in the range of 20-150g/m 2 The film may be bonded to the backing sheet using any suitable 44 adhesive. For example, a latex based adhesive may be used in a wet laminating process. Alternatively an extrudate, such as polyethylene acid copolymer, may be used.

4 25 The metal foil is designed to act as a thermal barrier. In one form, an aluminium foil is used having a gauge of between 6pm and 15pm. Such foils are commercially available and offer the barrier and emittance properties required at an economical price. However, the gauge of the foil is not critical and apart from the cost, higher gauges of 7pm or more may be used if required.

As an alternative to an aluminium foil, other materials may be used such as a metallised polyester film which would typically be between 5pm or 100pm gauge.

CAP-54215a.doc 24/09/99 The metal foil typically forms an outer layer of the laminate material and may be coated with a film of ink or dye so as to reduce the reflecting properties of that surface so as to reduce the reflected glare during installation of the product.

Additional layers may be included to improve the structural characteristics of the laminate.

In one form, the metal foil is bonded to a backing sheet, such as kraft paper. The backing provides added strength to the metal foil and facilitates its handling. In one form, a paper having weight of approximately 30-100g/m 2 is used though higher grammages may be used if the increased structural properties are required or economically justified. Other non-woven backings (formed from synthetics such as PE, polyester or cellulosics) may be used instead of a paper backing.

A wide range of adhesives may be used to bond the metal foil to its 15 backing sheet. The adhesive may be a water based emulsion. Alternatively, o extrusion lamination, using extruded PE, copolymer, and other materials may be used as an alternative to a water or solvent based adhesive.

~In one form, the laminate may be designed to be sufficiently strong to support the weight of a man. This has a practical advantage in the construction industry where the laminate material may have the dual function of providing both an insulating barrier as well as a safety mesh.

S.In one form, to provide the required structural characteristics to support °the weight of a man, a fibrous layer is provided in the laminate. The fibrous layer may be woven or non woven. In one form, the fibrous layer incorporates a polypropylene weave having an end count of about 3.2 x 2.2 ends/cm, although higher end counts of weave may be used depending on the strength requirements. The polypropylene polymer may also be replaced by weave using HDPE or similar polymers depending on the required characteristics of the laminate. Similarly, non-woven webs, using synthetics such as PE, polyester or cellulosic materials may also be used.

Alternatively, the laminate may be reinforced by other arrangements such as strands of fibreglass located in mass directly in the flame retardant CAP-542158.doc 2410999 adhesive. Such arrangements may be particularly preferred where the laminate is not required to act as a structural safety mesh.

A particularly preferred laminate according to the invention includes the following layers and adhesives: 40pm opaque, white cast polypropylene film, containing hindered amine light stabilisers.

Polypropylene extrudate coating weight of 30 g/m 2 Polypropylene weave, 3.8 x 2.2 ends/cm Flame retardant adhesive (hotmelt) coating weight of 245 g/m 2 Kraft paper 39 g/m 2 Adhesive coating weight of 2 g/m 2 6.5 pm Aluminium foil.

The laminate is formed, preferably using conventional apparatus. In one arrangement the laminate is formed from three separate passes. Firstly, the 15 cast polypropylene film is extrusion laminated to the polypropylene weave using polypropylene. In a second pass, the aluminium foil is adhesive laminated to the kraft paper. Finally the two webs are laminated to each other on a hotmelt laminater using the flame retardant hotmelt adhesive.

In an alternative construction, the UV resistant film is wet or extrusion laminated to kraft paper in a first pass. In a second pass, aluminium foil is adhesive laminated to the film/paper web on a hot melt laminater using a flame retardant hotmelt adhesive.

The laminate material including the UV resistant film is more durable as it is corrosive resistant whilst providing a more aesthetic structure which can be C C S 25 easily cleaned. The applicant has found that a preferred form of the laminate including the cast polypropylene film with UV stabiliser components and polypropylene extrudate, is far less prone to degrade or breakdown as compared to similar laminates which include a polypropylene film which is not UV resistant.

A preferred form of the laminate is now described with reference to the accompanying drawing which illustrates schematically a laminate in cross section to a greatly enlarged scale.

CAP-542156.dOC 24/09/99 As illustrated, the laminate 10 includes seven distinct layers. Proceeding from a lower surface, the laminate 10 includes an outer layer of aluminium foil 11. The foil has a gauge of approximately 6.5pm and whilst not shown may be coated with an ink or dye so as to reduce its reflectivity. This will reduce the insulation property of the laminate but may be used particularly where the laminate is used for other purposes such as a vapour barrier. This coating is designed to reduce the reflective glare which can cause particular problems when installing the laminate.

The foil 11 is bonded to a layer of kraft paper 13 by adhesive 12. The kraft paper has a grammage of approximately 39g/m 2 whereas the adhesive which is typically a water based emulsion has a grammage of about 2g/m 2 The next layer of the laminate is a hotmelt adhesive 14. This adhesive is a flame retardant grade and has a coating weight of approximately 245g/m 2 The adhesive is based on chlorinated paraffin and filler and both combines bulk 15 and stiffness to the laminate.

0 A reinforcing layer 17 overlies the flame retardant adhesive. In the illustrated form, the fibrous layer is formed from a polypropylene weave having a density of approximately 3.8 x 2.2 end/cm. This reinforcing layer provides sufficient strength to enable the laminate 10 to support a man thereby enabling the laminate to have the dual function of providing insulation as well as serving as a safety layer for workers during building construction.

Overlaying the polypropylene weave is a polypropylene extrudate having a coating weight of approximately 30g/m 2 The extrudate is designed to form a barrier between the flame retardant adhesive and a cast polypropylene film 17 9.

which completes the laminate and forms its outer surface. The cast polypropylene film includes HALS as UV stabilisers having the following formula:

N-(CH

2 )n-Ni IN N

CH

3

CH

3

CH

3 H CH 3

CH

3 H CH 3

H

2

N-CCH

2

CCH

3

CH

3

CH

3

CH

3 CH3

CH

3

CH

3 n CAP-542156.doc 24/09/99 8 These UV stabilisers are added as a master batch in effective proportions to the polypropylene prior to casting. Colour additives are also added to the film as required to provide a desired colour finish to the plastic film 17. Typically the film has a gauge of approximately The laminate 10 is formed using conventional apparatus in three separate passes. Firstly, the cast polypropylene film 17 is extrusion laminated to the polypropylene weave 15 using polypropylene 17 as the extrudate. In a second pass, the aluminium foil 11 is adhesive laminated to the kraft paper 13.

Finally, the two webs are laminated to each other on a hotmelt laminater using the flame retardant hotmelt adhesive 14.

In a variant of the described laminate, the polypropylene weave 15 and the polypropylene extrudate 10 may be omitted. In this arrangement, the polypropylene film 17 is bonded directly to the flame retardant adhesive. To maintain the structural integrity of the laminate, glass reinforcing may be located in mass directly in the flame retardant adhesive 5. The advantage of S .this arrangement is that it reduces the processing steps with the film being able to be directly laminated to the foil/paper web using the flame retardant hotmelt adhesive.

Finally, it will be appreciated that variations and or modification may be made to the components herein described without departing from the spirit of •ambit of the invention.

S S

S

O*°

CAP-542156.doc 24/09/99

Claims (27)

1. A laminated sheet including a substrate incorporating a layer of metal foil, and a UV resistant film bonded to said substrate.

2. A laminated sheet according to claim 1, wherein the UV resistant film is formed from a polymeric material having a thickness of between 10 pm and 200 pm.

3. A laminated sheet according to claim 2, wherein the UV resistant film includes UV stabilisers selected from at least one of the following classes: UV absorbers, hindered amines, nickel chelates, hindered phenols and aryl esters.

4. A laminated sheet according to claim 3, wherein the UV resistant film includes a hindered amine light stabiliser.

A laminated sheet according to either claim 3 or 4, wherein the UV stabiliser contains the group represented by the following formula: CH 3 CH 3 VO H "CH 3 CH3

6. A laminated sheet according to any one of claims 3 to 5, wherein UV stabiliser is represented by the following formula: -N-(CH 2 N CH 3 CH 3 CH 3 H CH 3 CH 3 H CH 3 H 2 N-CCH 2 COH 3 S_ CH 3 CH 3 CH 3 CH 3 H 3 CH 3 n

7. A laminated sheet according to any preceding claim, wherein the UV resistant film is cast or blown.

8. A laminated sheet according to any preceding claim, wherein the UV resistant film forms one outer layer of the sheet and the layer of metal foil forms the other opposite outer layer of the sheet. CAP-542156.doc 24/09/99

9. A laminated sheet according to any preceding claim, wherein at least two adjacent layers of the sheet are bonded together by a flame retardant adhesive.

A laminated sheet according to claim 9, wherein a barrier layer is provided between the hot melt adhesive and the UV resistant film.

11. A laminated sheet according to claim 10, wherein said barrier layer is formed from a polymer extrusion.

12. A laminated sheet according to claim 11, wherein said polymer extrusion is in the form of a polypropylene extrudate, having a coating weight between g and 50 g/m 2

13. A laminated sheet according to any preceding claim, wherein the metal layer is in the form of an aluminium foil having a thickness of between 6 pIm and pm.

14. A laminated sheet according to any one of claims 1 to 12, wherein the metal layer is in the form of a metallised polyester film having a thickness of between 12 pm and 100 pm. o

15. A laminated sheet according to any preceding claim, further including an intermediate layer between said UV resistant film and said metal foil.

16. A laminated sheet according to claim 15, wherein said intermediate layer is kraft paper.

17. A laminated sheet according to claim 15, wherein said intermediate layer is a non-woven polymer sheet.

18. A laminated sheet according to any preceding claim, further including a reinforcing layer disposed between said UV resistant film and said metal foil.

19. A laminated sheet according to claim18, wherein said reinforcing layer is formed from a fibrous material and is operative so that the sheet is able to bear Sthe weight of a man.

A laminated sheet according to claim 19, wherein the fibrous layer is woven and comprises fibrous material incorporating a polymer weave having an end count of greater than 2.5 X 1.5 ends/cm.

21. A laminated sheet according to claim 18, when dependent on claim 11, wherein the reinforcing layer includes strands of fibreglass located directly in the flame retardant adhesive. CAP-542158.doc 24/09/99

22. A method of making a laminated sheet including the steps of: forming a first web by adhesively bonding a UV resistant film to a polymer weave; forming a second web by adhesively bonding an aluminium foil to a backing sheet; and forming said laminated sheet by laminating the first and second webs to each other using a flame retardant hot melt adhesive.

23. A method according to claim 22, wherein the UV resistant film is extrusion laminated to the polymer weave using a polypropylene extrudate.

24. A method of making a laminated sheet including the steps of: forming a first web by adhesively bonding a UV resistant film to a backing sheet; and laminating said first web to an aluminium foil using a flame retardant hot melt adhesive to form said laminated sheet.

25. A method according to claim 23, wherein said aluminium foil is adhesive laminated to a backing sheet prior to being laminated to said first web.

26. A method according to any one of claims 22 to 25, wherein said backing sheet is kraft paper.

27. A laminate material substantially as herein described with reference to the accompanying drawing. 4 DATED: 29 September 1999 25 PHILLIPS ORMONDE FITZPATRICK S* Attorneys for AMATEK LIMITED CAP-54215a.doc 20/99 12