Graffiti resistant film and method for application of an anti-graffiti coating onto a substrate

Abstract

 A sheet substrate (50) comprises a base sheet (52), a first adhesive layer (54) and a print coating (56). The print coating (56) comprises a plurality of respective compositions (56a, 56b, 56c, 56d) each composition comprising a graffiti resistant barrier substance and a different colour pigment. The graffiti resistant barrier substance is preferably a 'two pack' type of graffiti resistant paint product.
The multi-laminate film (50) is manufactured by first placing the base sheet (52) on a screen printing apparatus and applying a first composition (56a) by the screen printing process described above. This operation is repeated for the other compositions (56b to 56d) so forming the print coating (46).

Description

[0001] The present invention relates to a graffiti resistant film and a method for the application of an anti-graffiti coating onto a substrate and is concerned in particular, although not exclusively, with a graffiti resistant self adhesive film and a method for the application of an anti-graffiti coating onto the self adhesive film.

[0002] Known graffiti protective multi-layer films used for display signs, automobile bodywork livery comprise an adhesive backing sheet, a film layer that carries pigment and a transparent protective overlay sheet. The protective overlay sheet may be in the form of a clear polyester and vinyl over-laminates. Such protective overlay sheets can be laborious to apply and may be susceptible to trapped air bubbles if not applied correctly.

[0003] It is known to provide protection systems for protecting livery applied to road and rail bodywork in the form of a multi-layer protective film comprising a plastic base film and a plurality of removeably plastic films. Published patent specifications DE 29814711 and WO 200024576 describe such a multi-layer film.

[0004] According to a first aspect of the present invention there is provided a method for coating a substrate with a graffiti resistant barrier, the method comprising the use of a screen printing process to apply a liquid layer of graffiti resistant barrier substance to a substrate and allowing the layer of graffiti resistant barrier to dry.

[0005] The term screen printing process is used herein for any process of applying a liquid to a surface of a material by squeezing the liquid through the open parts of a mesh on to the surface. A mesh stencil may be used in such a process whereby the liquid is squeezed through the open parts of the mesh stencil on to the surface.

[0006] The surface to which the liquid is applied may be of any suitable material for the required function of the final product. The surface may be smooth or rough, flat or curved. However, preferably the material used is a flexible self-adhesive vinyl or a substantially rigid plastics material as used in the sign industry.

[0007] Preferably, a single screen printing stage is used to apply a single liquid layer of graffiti resistant barrier substance to the substrate forming a single protection layer over the substrate.

[0008] Alternatively, a plurality of screen printing stages are used to apply a plurality of different liquid graffiti resistant barrier substances to the substrate in order to form an image on the substrate.

[0009] According to a second aspect of the present invention there is provided a sheet substrate coated with a graffiti resistant barrier substance.

[0010] Preferably, the sheet substrate is coated with a graffiti resistant barrier substance using a method according to the first aspect of the invention.

[0011] The graffiti resistant barrier substance preferably comprises more than one graffiti resistant paint product.

[0012] Preferably, the graffiti resistant barrier substance comprises a composition of two types of graffiti resistant paint product.

[0013] Previously graffiti resistant paint products have been manufactured to be either painted using a brush or sprayed onto surfaces such as building walls. We have discovered the surprising fact that the characteristics of a 'two pack' type of graffiti resistant paint product allows the composition to be applied using a screen printing process.

[0014] Preferably, the graffiti resistant substance is substantially transparent when dry. The substantially transparent graffiti resistant substance is used to form a barrier over the sheet thus protecting the surface of the sheet and any image or print under the barrier that is applied to the surface of the sheet from potential graffiti.

[0015] Alternatively, the graffiti resistant barrier substance comprises a colour pigment. In an embodiment of the present invention there is provided a plurality of graffiti resistant barrier substances that each comprise a different colour pigment.

[0016] The graffiti resistant barrier substances that comprise colour pigments may be used to form an image or print applied to the sheet. In this particular embodiment a further graffiti resistant barrier covering the image or print may not be necessary.

[0017] In an embodiment of the second aspect of the present invention the sheet substrate is a self-adhesive sheet.

[0018] We have discovered that sheet substrates coated with a graffiti resistant barrier substance according to a second aspect of the present invention have improved fire retardant characteristics that improve the fire performance.

[0019] Other embodiments of the present invention may include any combination of the features or limitations referred to herein.

[0020] The present invention may be carried into practice in various ways, but two embodiments will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a cross section view of a typical screen printing apparatus;

Figure 2 is a cross section view of a known multi-laminate film comprising a protective over-laminate film;

Figure 3 is a cross section view of a single sheet substrate coated with a graffiti resistant barrier substance according to a first embodiment of the present invention; and

Figure 4 is a cross section view of a single sheet substrate coated with plurality of graffiti resistant barrier substances comprising colour pigments according to a second embodiment of the present invention.

[0021] With reference to Figure 1, screen printing apparatus 1 comprising a printing base 2, a frame 4 and a mesh 6. The mesh 6 is stretched between and attached to the frame 4. A stencil 8 may be placed between the mesh 6 and a stock sheet 9 to define a desired pattern. The stock sheet 9 is supported by the printing base 2. The stock sheet 9 may be a self-adhesive vinyl sheet as used for a vehicle livery or a rigid plastic sheet as used in the sign industry. In use an ink 10 is forced through the mesh 6 and onto the uppermost surface of the stock sheet 9 using a squeegee 12. Such a process is well known to the skilled person in the art.

[0022] With reference to Figure 2, a known multi-laminate film 20 comprises a polyester base sheet 22, a first adhesive layer 24, a print layer 26 and a vinyl protective over-laminate film 30 comprising a second adhesive layer 28.

[0023] The multi-laminate film 20 is manufactured by first placing the base sheet 22 on a screen printing apparatus and applying the print layer 26. Once dry the protective over-laminate film 30 is placed onto the print layer 26 and bonded thereto by the second adhesive layer 28. The first adhesive layer 24 is used to fix the multi-laminate film 20 to a desired surface such as a vehicle side. Air bubbles may become trapped between the print layer 26 and the second adhesive layer 28.

[0024] With reference to Figure 3, a sheet substrate 40 comprises a base sheet 42, a first adhesive layer 44, a print layer 66 and a coating 48 of a graffiti resistant barrier substance. The graffiti resistant barrier substance is preferably a 'two pack' type of graffiti resistant paint product. One such two pack anti-graffiti paint is Grafiklens F™, which is manufactured by Tremco Limited. We have found that a mix ratio of 59.4% part A to 40.6% part B works particularly well. Although these types of products have been manufactured to be applied to a surface using a brush or spraying device we have discovered the surprising fact that they may be used as a screen printable ink.

[0025] The sheet 40 is manufactured by first placing the base sheet 42 on a screen printing apparatus and applying the print layer 46. Once the print layer 46 is dry the coating 48 of a graffiti resistant barrier substance is applied to the print layer 46 using the screen printing apparatus.

[0026] As there is no protective over-laminate film 30 there is no chance of trapping air bubbles. We have discovered that sheet substrates coated with a graffiti resistant barrier substance have improved fire retardant characteristics that improve the fire performance.

[0027] With reference to Figure 4, a sheet substrate 50 comprises a base sheet 52, a first adhesive layer 54 and a print coating 56. The print coating 56 comprises a plurality of respective compositions 56a, 56b, 56c, 56d each composition comprising a graffiti resistant barrier substance and a different colour pigment. The graffiti resistant barrier substance is preferably a 'two pack' type of graffiti resistant paint product.

[0028] The multi-laminate film 50 is manufactured by first placing the base sheet 52 on a screen printing apparatus and applying a first composition 56a by the screen printing process described above. This operation is repeated for the other compositions 56b to 56d so forming the print coating 46.

Claims

1. A method for coating a substrate (52) with a graffiti resistant barrier, the method comprising the use of a screen printing process to apply a liquid layer of graffiti resistant barrier substance (56) to the substrate (52) and allowing the layer of graffiti resistant barrier substance (56) to dry.

2. The method of claim 1 wherein a mesh stencil is used whereby the liquid is squeezed through the open parts of the mesh stencil on to the substrate.

3. The method of claim 1 or claim 2 wherein the substrate (52) comprises a flexible self-adhesive vinyl.

4. The method of claim 1 or claim 2 wherein the substrate (52) comprises substantially rigid plastics material.

5. The method of any one of the preceding claims wherein a single screen printing stage is used to apply a single liquid layer of graffiti resistant barrier substance (56) to the substrate (52) forming a single protection layer over the substrate (52).

6. The method of any one of claims 1 to 5 wherein a plurality of screen printing stages are used to apply a plurality of different liquid graffiti resistant barrier substances (56a, 56b) to the substrate (52) in order to form an image on the substrate (52).

7. A sheet substrate (52) coated with a graffiti resistant barrier substance (56).

8. The sheet substrate (52) of claim 7 wherein the sheet substrate (52) is coated with a graffiti resistant barrier substance (56) using a method according to any one of claims 1 to 6.

9. The sheet substrate (52) of claim 7 or claim 8 wherein the graffiti resistant barrier substance (56) comprises more than one graffiti resistant paint product.

10. The sheet substrate (52) of claim 9 wherein the graffiti resistant barrier substance (56) comprises a composition of two types of graffiti resistant paint product.

11. The sheet substrate (52) of any one of claims 7 to 10 wherein the graffiti resistant substance (56) is substantially transparent when dry.

12. The sheet substrate(52) of any one of claims 7 to 10 wherein , the graffiti resistant barrier substance (56) comprises a colour pigment.

13. The sheet substrate (52) of claim 12 wherein there is provided a plurality of graffiti resistant barrier substances (56a, 56b) that each comprise a different colour pigment.

14. The sheet substrate (52) of claim 13 wherein the graffiti resistant barrier substances (56a, 56b) that comprise colour pigments are used to form an image or print applied to the sheet.

15. The sheet substrate (52) of claim 14 wherein the sheet substrate (52) is a self-adhesive sheet.

Drawing