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Title:
POLYMERIC LAMINATE FILM FOR APPLICATION ONTO GLASS OR POLYCARBONATE SURFACE
Document Type and Number:
WIPO Patent Application WO/2002/068182
Kind Code:
A1
Abstract:
The invention relates to a laminate film suitable for applying to a substrate comprising a first and a second layer of material (1, 2), and a layer of adhesive (3) disposed therebetween, wherein said second layer comprises self-clinging vinyl. The invention further relates to a method of preparing a laminate film suitable for applying to a substrate, comprising the steps of: taking a first layer of material having a layer of pressure sensitive adhesive predisposed on a surface thereof, and applying a second layer comprising self-clinging vinyl onto said pressure sensitive adhesive to produce a laminate film wherein the pressure sensitive adhesive is disposed between the first and second layers.

Inventors:
PAYTON DAVID MICHAEL (GB)
Application Number:
PCT/GB2002/000692
Publication Date:
September 06, 2002
Filing Date:
February 18, 2002
Export Citation:
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Assignee:
PAYTON DAVID MICHAEL (GB)
International Classes:
B32B7/12; (IPC1-7): B32B7/12
Foreign References:
GB2231551A1990-11-21
CH669157A51989-02-28
CH671373A51989-08-31
US4581281A1986-04-08
Attorney, Agent or Firm:
GEOFFREY OWEN & COMPANY (Church Street, Liverpool L1 3AB, GB)
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Claims:
CLAIMS
1. A laminate film suitable for applying to a substrate, comprising a first and a second layer of material, and a layer of adhesive disposed therebetween, wherein said second layer comprises selfclinging vinyl.
2. A laminate film according to claim 1 wherein the film is pliable.
3. A laminate film according to claim 1 or 2 wherein the first layer has stretch properties to accommodate expansion and contraction of a substrate.
4. A laminate film according to any one of the preceding claims wherein the first layer comprises a plastics film.
5. A laminate film according to claim 4 wherein the plastics film is single ply.
6. A laminate film according to claim 4 wherein the plastics film is multiply.
7. A laminate film according to any one of the preceding claims wherein the first layer comprises paper.
8. A laminate film according to any one of the preceding claims wherein one or more of the layers is tinted.
9. A laminate film according to any one of the preceding claims wherein one or more of the layers is coloured.
10. A laminate film according to any one of the preceding claims wherein one or more of the layers is reflective.
11. A laminate film according to any one of the preceding claims wherein the first layer has a thickness of 25375 ym.
12. A laminate film according to any one of the preceding claims wherein the first layer has a thickness of 37. 5 ym.
13. A laminate film according to any one of the preceding claims wherein the second layer comprises plasticised PVC.
14. A laminate film according to any one of the preceding claims wherein the second layer has a thickness of 0.100.30 mm.
15. A laminate film according to any one of the preceding claims wherein the second layer has a thickness of 0.25 mm.
16. A laminate film according to any one of the preceding claims wherein the second layer includes a pressure sensitive adhesive.
17. A laminate film according to any one of the preceding claims wherein the adhesive is polymeric.
18. A laminate film according to any one of the preceding claims wherein the adhesive is pressure sensitive.
19. A laminate film according to any one of the preceding claims wherein the second layer is protected by a removable release liner.
20. A method of preparing a laminate film suitable for applying to a substrate, comprising the steps of: taking a first layer of material having a layer of pressure sensitive adhesive predisposed on a surface thereof, and applying a second layer comprising selfclinging vinyl onto said pressure sensitive adhesive, to produce a laminate film wherein the pressure sensitive adhesive is disposed between the first and second layers.
21. A method according to claim 20 wherein the method is performed under water.
22. A method according to claim 21 wherein the laminate film is subjected to pressure to squeeze out excess water trapped between the layers.
23. A method according to claim 2022 wherein the laminate film is cured by drying and heating.
24. A solar shade for a window comprising the film of any one of claims 119.
25. A freehanging blind for a window or a door comprising the film of any one of claims 119.
26. A laminate film substantially as hereinbefore described with reference to the accompanying drawing.
27. A method of preparing a laminate film substantially as hereinbefore described with reference to the accompanying drawing.
Description:
DESCRIPTION POLYMERIC LAMINATE FILM FOR APPLICATION ONTO GLASS OR POLYCARBONATE SURFACE The present invention relates to films, in particular to laminate films suitable for application onto a surface such as glass or polycarbonate.

Polymeric films have been applied to windows and to other surfaces for a variety of reasons. Their aesthetic and functional use as a sunshield or privacy shield is well established, for example on car windscreens and in conservatories, where tinted or reflective sheets of adhesive film may be applied to the glass or other surface to reduce the intensity and glare of solar rays.

Such adhesive films have also found use as safety films, being applied to one or both surfaces of a sheet of glass so that upon shattering of the glass, loose fragments remain adhered to the film.

Films already used in the field typically comprise a plastics film coated on one side with a pressure sensitive adherent such as an ethylene vinyl acetate copolymer. Upon contact of the adherent with a surface such as glass, pressure is applied to induce adherence of the film onto the glass.

The application of such films can however be problematic. The film is difficult to apply smoothly onto the surface, and requires skill and care.

Particular care must be taken to avoid entrapment of particles of dust, paint flakes, insects and even fingerprints. In practice, complete exclusion of unwanted particles is virtually impossible, since minor particles on the glass or film are not always visible until pressure is applied to the film with a squeegee.

The particles then become embedded in the adhesive and form indents in the plastics film. Even if the film is pulled away from the window to remove the particles, the flaws remain due to disturbed adhesive or indented film.

In view of the above difficulties, it is necessary to employ an experienced fitter to apply the film satisfactorily with the minimum of flaws. At present, therefore, the use of films is costly.

The use of such films has further drawbacks. Owing to the surface tack properties and to the composition of the film, such film must be rapidly adhered to a substrate and cannot be stored or used in situations where the adherent surface of the film is left exposed to the atmosphere for any appreciable length of time.

Particles of dust would readily adhere to the exposed adherent and would be difficult to remove, affecting the appearance and further use of the film.

Once fitted and bonded onto a substrate surface, the film currently used adheres strongly to the surface and can only be removed with difficulty, by tearing off and damaging the film. It cannot thus be removed and repositioned or reused. A satisfactory finish must therefore be achieved at the first attempt.

Owing to the difficulty and cost of removal and/or refitting, the film tends to be left in place for long periods of time, typically of up to ten years, and is thus regarded as a permanent fixture. During this time, the film may be prone to damage or vandalism, giving an unsightly appearance which can only be rectified by complete removal and replacement of the film. Again, this requires an expert fitter, even for a single window pane. Clearly this is neither cost nor time-effective and discourages from the outset many potential buyers of the product especially in the domestic market.

An object of the present invention is to address at least some of the above-mentioned problems and to provide an improved film which can be applied to glass, windows and other suitable substrates. More particularly, an object of the invention is to provide a film which can be quickly and easily adhered to a substrate without the need for special equipment or skill. A further object of the invention is to provide a film which, once applied to a substrate, can be removed easily and reused without damage to the film or the substrate.

A further object of the invention is to provide a film having an adherent surface contactable with a substrate, at least part of which surface may be left exposed to the atmosphere for extended periods of time without detriment to said surface. Such film could be employed for example in situations wherein at least part of said surface is temporarily or permanently exposed to the atmosphere.

Yet a further object of the invention is to provide a method of producing such a film.

According to a first aspect of the invention, there is provided a laminate film comprising a first and a second layer of material, and a layer of adhesive disposed therebetween, wherein said second layer comprises self-clinging vinyl.

According to a second aspect of the invention, there is provided a method of preparing a laminate film suitable for applying to a substrate, comprising the steps of: taking a first layer of material having a layer of pressure sensitive adhesive predisposed on a surface thereof, and applying a second layer comprising self-clinging vinyl onto said pressure sensitive adhesive, to produce a laminate film wherein the pressure sensitive adhesive is disposed between the first and second layers.

While the above-described process is the preferred method of production of the film according to the invention, alternative methods are envisaged, for example a method whereby the adhesive is applied to a layer of self-clinging vinyl, said first layer of material then being applied to the adhesive.

Preferably, the process of the second aspect is performed under water to ensure smooth adhesion of the layers by minimising attraction of dust by static electricity between the layers. Pressure may then be applied to force out excess water from between the layers, thus producing a smooth and uniform laminate film which is free of dust particles. The process may be performed using a squeegee or a roller, for example.

In a preferred embodiment of either the first or second aspect of the invention, the film is pliable. It may have stretch properties, enabling it to accommodate expansion and contraction of the substrate to which it is bound. Preferably the first layer alone has stretch properties. Stretch properties are particularly desirable for films intended for application to polycarbonate surfaces such as those commonly used in conservatory roofing. It is well known that such materials expand with temperature. A film applied to the surface must therefore be able to accommodate expansion without splitting, cracking, stressing, bubbling or becoming detached from the substrate.

Preferably, according to the first or second aspect of the invention, the first layer comprises a plastics film, which may be single or multi-ply. Alternatively or additionally, it comprises paper. The first and second layers may independently of one another be tinted and/or coloured and/or patterned and/or reflective. Either or both of the first and second layers may be printable, for example for display purposes, advertising or decoration.

The first and/or second layer may have solar rejection properties.

Preferably, according to the first or second aspect of the invention, the first layer has a thickness of 25 ymto 375 ym, more preferably 37.5 Am. The self-clinging vinyl of the second layer preferably comprises plasticised PVC. Preferably, the second layer has a thickness of 0.10 to 0.30 mm, more preferably 0.25 mm.

It may include a pressure sensitive adhesive.

Preferably, according to the first or second aspect of the invention, the adhesive is polymeric.

Alternatively or additionally, the adhesive is pressure sensitive. Other types of adhesive such as spray-on adhesives might also be employed.

The second layer is preferably protected by a release liner which is removable prior to application of the film to the desired substrate. Alternatively, a release liner need not be used. Typically the film may be stored and sold in sheets or as a roll, without the need for a protective release liner.

The present invention may be used in a variety of applications, for example it may be applied to windows as a solar or privacy shade, as an advertising, promotional or decorative display, in crime surveillance to provide a one-way viewing screen, or to provide a decorative patterned, coloured or stained glass effect on a window.

The film may also serve as a safety shield for strengthening glass. The film may be applied to one or both sides of a glass, polycarbonate or other panel to protect the panel from shattering upon impact. Even if the panel breaks, any shards or broken fragments will remain adhered to the film, thus reducing risk of injury or damage.

In contrast to films already used in the field, the film of the present invention can be applied to a surface quickly and simply, without the need for a trained expert.

Typically, the film of the invention is supplied with a peelable release liner protecting the outer surface of the second layer. In order to apply the film to a surface, the release liner is peeled away to expose the self-clinging vinyl of the second layer. The film can then be placed onto the surface, the self-clinging vinyl thus contacting the surface. Pressure is then applied over the film to obtain a smooth, even contact with the surface, and to maintain the required adherence between the film and glass.

Small areas of film are easy to apply simply by applying manual pressure across the film. For larger areas, to ensure a smooth and dust-free finish and to minimise static build-up, the substrate and/or film is preferably wet with water or a dilute soap or detergent solution and pressure applied across the film applied using a squeegee. Any water is forced out from between the surface and the film. This method reduces likelihood of entrapment of dust particles or unsightly air bubbles under the film.

Another advantage of the present invention is that the film is sufficiently flexible and robust to allow repeated handling and reuse. The multi-laminate film has reduced stretchability compared with single layer flexible vinyl, plasticised PVC and polymeric films, and this confers improved strength, enabling the film to be handled repeatedly without damage. Once applied to a substrate, the film can be removed and repositioned as often as necessary. The film has sufficient cling adhesion for it tc remain in place indefinitely, whilst still allowing film to be removed and reused at any time as desired. Therefore, if dust particles are trapped, or the film has been incorrectly positioned, it can simply be taken off and reapplied until a satisfactory result is achieved. This is also useful, for example, for providing a solar screen only at certain times of the day or year. Since the film is easy to apply and can be reused, it is less wasteful and more economic, offering a significant saving in cost over films currently available. Owing to the advantages of the present invention over the prior art, the use of window films will become more attractive to the customer.

Furthermore, the film has important advantages over the prior art in that the adherent surface may be left exposed indefinitely to the atmosphere without detriment to the quality or the properties of the film. Any particles of dust or other matter which might become adhered to the exposed adherent surface may be removed by wiping or by immersion in water. The tack properties of adherent surface enable the film to be used in situations where part or all of the surface is not in contact with a substrate.

The film thus may be used for free-hanging blinds for windows and doors in buildings and in vehicles, and for umbrellas and sunshades, for example. The film may be stitched or heat-welded and may be used for the manufacture of traditional blinds, such as vertical blinds and roller blinds, as well as for vehicle window blinds which are attachable over a window pane by a variety of fastening means. The desired appearance and purpose of such articles can be achieved by selection of a film having the required properties, for example solar rejection, colour, reflectivity.

An advantage of free-hanging blinds according to the present invention over existing free-hanging solar blinds is that of improved visibility. Solar blinds currently available generally have a rigid, multilayer construction with a rough surface which tends to reduce or distort visibility.

The invention will now be described in detail by way of the following preferred embodiments, with reference to the accompanying drawing.

Figure 1 is a sectional view of the film.

Example 1 According to a preferred embodiment of the first aspect of the invention, a flexible film comprises three adjacent, contacting coplanar layers. The components of the layers will vary, depending on its intended use. The present example pertains to a film for application to a glass surface or other substrate, in particular for adding a tint and/or solar rejection properties to a window.

In the present example, referring to Figure 1, the first layer 1 is a transparent plastics film having a thickness of approximately 37.5 Um, a tensile strength of 28000-30000 psi and a melting point of 260-265W. Typical characteristics of the material of the first layer 1 are as follows: solar transmittance 50% solar absorptance 44% solar reflectance 6% visible light transmittance 520 visible light reflectance 8% emissivity 0.94 W transmittance (300-380 nm) <2% total solar energy rejected 380 A second layer 2 is a sheet of flexible, plate surfaced plasticised PVC having a thickness of 0.25 mm.

Preferably, it is clear and transparent but could alternatively be coloured, tinted and/or opaque.

Between the first layer 1 and second layer 2 is disposed a layer of polymeric pressure sensitive adhesive 3. The adhesive comprises an ethylene vinyl acetate (EVA) copolymer having between 15-50% vinyl acetate (VA) and a melt index between 20-60, the balance of the copolymer being ethylene, a stabilisation package and an aged adhesion inhibitor package. The stabilisation package may comprise a non-yellowing antioxidant to protect the film from oxidative degradation, a stabiliser to protect film from UV radiation, and a thermal stabiliser to protect the film from heat degradation.

At point of sale, the film of the invention is provided with a peelable release liner 4 to protect the otherwise exposed, self-clinging vinyl surface of the plasticised PVC of the second layer 2. This allows easy and convenient storage and handling of the film until it is ready to be applied.

Example 2 A typical, preferred method of production of the film of the invention is as follows: A layer of flexible, self-clinging vinyl must be bonded with a sheet of plastics film which is pre-coated on one surface with a pressure-sensitive adhesive. The plastics film is supplied in a form wherein the adhesive coating is protected by a peelable release liner.

Firstly, the self-clinging vinyl is laid onto a smooth, dust-free surface. The release liner protecting the adhesive coating of the plastics film is then removed, and the plastics film laid over the vinyl to form a bond between the vinyl and the pressure sensitive adhesive.

In the present, preferred embodiment, this procedure is mechanised and is performed under water in a tank receptacle to minimise the presence and attraction of dust or other particles. A further advantage of the underwater method is that the pressure sensitive adhesive is wetted, this being required for optimum adhesion.

Once bonded, the composite laminate product is subjected to pressure to squeeze out any excess water trapped between the layers. The bonding of the two products is then cured by drying and heating. The resultant material is then ready for manufacturing into the desired finished product, for example by applying a removable release liner to protect the exposed surface of the self-clinging vinyl.

From the above-described examples, which serve merely to illustrate preferred embodiments of the invention, modifications and variations will be appreciated without departing from the scope of the claimed invention.