ADHESIVE FOIL FOR WINDSCREEN PROTECTION

Abstract: A protective film (13) for windscreens of vehicles comprises a polypropylene base sheet (16) and an acrylate adhesive layer (18). Film (13) serves to protect the windshield against damage during transport from factory to showroom and can be removed on arrival.

Description: ADHESIVE FOIL FOR WINDSCREEN PROTECTION This invention relates to a means for protection of vehicle windscreens, particularly during transit. It is known, for example from EP-A-51 9278 (Nitto Denko) to cover the bodywork and attachments such as fenders of vehicles with adhesive film or cloth sheets to protect against damage during transport or shipping of the vehicle. It has been found that in practice, when transporting vehicles in long ocean voyages, it is inevitable that water will find its way into the hold, and drip onto the windscreen of a vehicle. Such water will contain iron oxide due to contact with rusted surfaces within the ship and this oxide can permanently stain and damage a windscreen, particularly when a horizontal trap associated with the windscreen, such as a lower edge seal, catches the dripping water and holds it for a long time to leave behind an iron oxide residue. Currently available protective films or cloths are not suitable for use, since it is impracticable to apply them onto the windscreens after the vehicles have been loaded onto the ship. It is the usual procedure to apply all protective films or sheets just before leaving the factory. Since the vehicles have to be driven onto and from the ship, a typical protective f ; !m or cloth is unsuitable for use to cover the windscreen since it obscures the driver's vision. It is a further requirement that any cover applied to the windscreen should be sufficiently abrasion resistant to withstand wiper action, in case the car is unloaded or loaded in bad weather. Ruching or peeling of the cover by the windscreen wipers will damage or remove the cover and compromise its effectiveness. U.S. Patent 5,002,326 proposes a windscreen cover of a multiplicity of polycarbonate film sheets non-permanently bonded by pressure sensitive adhesive. 1 2 to 16 sheets are suggested. As each exposed film is worn and degraded by exposure it is removed to expose the next film below. The initially rather thick layer is not suitable for use as a temporary cover tor vehicles in transit and also the material chosen is likely to degrade due to UV exposure. Any adhesive used must be strong enough to stick the cover to the windscre n during use of the wipers, yet be sufficiently easily releasable to remove the cover without leaving an adhesive residue on the glass. No windscreen cover has so far been produced which is able to satisfy all these requirements, and it is an object of the invention to provide such a windscreen cover. The invention therefore provides a vehicle windscreen cover, for vehicles in transit, which comprises a transparent thermoplastic film, for application over the area of a vehicle windscreen, said film having a coating of a pressure-sensitive adhesive on one face of the film, to contact the windscreen. The transparent thermoplastic film may be a propylene polymer. The pressure-sensitive adhesive is preferably an acrylic based material. The film is preferably sufficiently large to cover not only the windscreen glass area, but also at least part of the surrounding frame area, to prevent access of dirty water to any corners, cracks or channels which might cause such water to accumulate. An embodiment of the invention is described by way of example, with reference to the accompanying drawings, wherein:- Fig. 1 is a view of a vehicle windscreen protected by a windscreen cover according to this invention; Fig. 2 is a fragmentary cross section of the windscreen and windscreen cover; and Fig. 3 is an enlarged sectional view of the cover itself. As shown in Fig. 1 , a vehicle 10 (only partially shown) has a windscreen 1 1 , surrounded by a frame 1 2, by means of which the windscreen is held in the bodywork of the vehicle. The windscreen 1 1 is protected by a removable cover 13, the edges 1 3a of which extend beyond the frame ' 2 to partially overlie the bodywork. The cover 13 is also provided below windscreen wipers 1 4, which can be used over the screen cover 1 3. This latter feature is more clearly shown in Fig. 2, where the edges of the screen 1 1 are shown to be received in seals 15, received in the frame 12. The edges 1 3a extend sufficiently beyond the frame 1 2 to cover any cracks, channels or water-retaining angles arising between the screen 1 1 and the seal 1 5 or frame 1 2, so that accumulation of water in any such water traps is avoided. The screen cover 13, as shown in Fig. 3, comprises a film 16 of a propylene polymer or co-polymer, which is transparent and thermoplastic and provides a smooth outer surface 17 which provides no resistance to the operation of a wiper blade 14 and thus has no tendency to peel, ruche or tear under the action of the wiper blade. This enables the vehicle to be driven, e.g. to and from a storage location or onto and from a ship during transit of the vehicle for delivery, with the windscreen cover 13 in place. The windscreen cover can thus be placed on the windscreen at the factory before despatch, without impairing the usual delivery routines which require the vehicle to be driven occasionally. The film 16 has an adhesive backing 1 8, comprising a pressure- sensitive acrylic-based adhesive, which is sufficiently strong enough to resist any loading imposed by operation of wiper blades 14, but can nevertheless be easily removed by peeling from the windscreen 1 1 when it is necessary to remove the cover 13. A suitable film for the film 16 by way of example comprises a polypropylene film with the following properties:- Density - 0.91 g/cm 3 Thickness - 47 microns Load at break - 70N/25mm (machine direction) Elongation at break - 600% (machine direction) Coefficient of friction - 0.2 Gloss - 85% Peel adhesion strength - 100g/25mm The adhesive backing 1 8 is in a preferred embodiment a coating on one side of the film 16 comprising 1 5.7g/m 2 of a solvent-based acrylic pressure sensitive adhesive using dimethylene diisocyanate (MDI) in a toluene solvent as a curing reagent. The f;*m preferably has a density in the range 0.75-1 .Og/cm 3 ; a thickness in the range 20-150 microns; load at break in the range 30- 100N/25mm; elongation at break in the range 300-800%; coefficient of friction 0.05-0.8; and peel adhesion strength 30-1 50g/25mm. A windscreen cover as described will prevent dirty, e.g. rust containing water from accumulating on or about the edges of the windscreen and thus prevent the occurrence of unsightly and potentially damaging rust stains on the windscreen or its immediate frame.

Claims: CLAIMS 1 . A vehicle windscreen cover, for vehicles in transmit, said cover comprising a transparent thermoplastic film, for application over at least a substantial part of a vehicle windscreen, said film having a coating of a pressure-sensitive adhesive on the face of said film which is to contact the windscreen. 2. A cover according to claim 1 wherein said transparent thermoplastic film comprises a polymer or co-polymer of propylene. 3. A cover according to claim, 1 or 2 wherein said pressure sensitive adhesive is an acrylic based material. 4. A cover according to any proceeding claim wherein said cover has dimensions sufficiently large to cover not only the entire glass area of the windscreen, but at least part of the surrounding frame area. 5. A cover according to any proceeding claim which is applied to a windscreen below any wiper blades present, and presents a smooth outer surface after application to the windscreen to enable the wipers to be operated with the cover in place. 6. A cover according to any preceding claim wherein said pressure- sensitive adhesive has a composition to enable the cover to be removed from the windscreen by peeling from the windscreen without leaving any visible adhesive residue on the windscreen after the film has been removed. 7. A vehicle windscreen cover according to any preceding claim wherein the film has a density in the range of 0.75-1 .Og/cm 3 ; a thickness in the range 20-1 50 microns; load at break in the range 30-100N/25mm; elongation at break in the range 300-800%; coefficient of friction 0.05-0.8; and peel adhesion strength 30-1 50g/25mm. 8. A vehicle windscreen cover according to any preceding claim wherein the adhesive comprises a solvent-based acrylic pressure sensitive adhesive using dimethylene diisocyanate (MDI) in a toluene solvent as a curing reagent. 9. A vehicle windscreen cover according to claim 8 wherein the adhesive is applied at a weight of 15.7g/m 2 .

Inventors: BATEY SANDRA, BATEY, SANDRA
Applicants: BATEY SANDRA, SCAPA GROUP PLC, BATEY, SANDRA
Application year: 1998
Main classification: C09J7
IPC codes: B60J11, C09J7, C09J133