Coating system for coating a surface of a substrate

Abstract

Coating system (1) for coating a surface (3) of a substrate (5), the coating system (1) comprising; a coating (7), and an adhesive layer (9), that is disposed between the substrate (5) and the coating (7), wherein the adhesive layer (9) comprises a first adhesive layer portion (13) adjacent the substrate (5) and a second adhesive layer portion (15) adjacent the coating (7) and a carrier (11) placed between said first and second adhesive layer portions (13, 5), wherein the first adhesive layer portion (13) is composed of a first adhesive layer material, wherein the second adhesive layer portion (15) is composed of a second adhesive layer material, wherein the first adhesive layer material and the second adhesive layer material is having an adhesive or bond strength to the surface (3) of the substrate (5) and to the coating (7) respectively that exceeds their respective cohesive or tensile strength, wherein the first and second adhesive layer materials and carrier (11) combination is configured for having an adhesive strength that is less than their respective cohesive or tensile strength, wherein the carrier (11) is configured with grab tensile properties such that the carrier (11) in combination with the second adhesive layer portion (15) and the coating (7) will separate from the first adhesive layer portion (13) under the action of a peeling force.

Claims

1. A coating system for coating a surface of a substrate, the coating system comprising; a coating, and an adhesive layer that is disposed between the substrate and the coating, wherein the adhesive layer comprises a first adhesive layer portion adjacent to the substrate, a second adhesive layer portion adjacent to the coating, and a carrier placed between said first and second adhesive layer portions, wherein the first adhesive layer portion is composed of a first adhesive layer material, wherein the second adhesive layer portion is composed of a second adhesive layer material, wherein the first adhesive layer material has an adhesive or bond strength to the surface of the substrate that exceeds the cohesive or tensile strength of the first adhesive layer material, wherein and the second adhesive layer material has an adhesive or bond strength to the coating that exceeds the cohesive or tensile strength of the second adhesive layer material, wherein the first adhesive layer material has an adhesive strength to the carrier that is less than the cohesive or tensile strength of the first adhesive layer material, wherein the second adhesive layer material has an adhesive strength to the carrier that is less than the cohesive or tensile strength of the second adhesive layer material, wherein the carrier has tensile properties such that the carrier in combination with the second adhesive layer portion and the coating will separate from the first adhesive layer portion when a peeling force is applied to the carrier, wherein the adhesive or bond strength of the first adhesive layer material to the surface of the substrate is between 6 and 12 MPa and the cohesive or tensile strength of the first adhesive layer material is between 4 and 6 MPa, wherein the adhesive or bond strength of the second adhesive layer material to the coating is between 6 and 12 MPa and the cohesive or tensile strength of the second adhesive layer material is between 4 and 6 MPa, and wherein adhesive strength, bond strength, cohesive strength and tensile strength are each measured according to ASTM D4541.

2. The coating system of claim 1, wherein the first adhesive layer material and/or the second adhesive layer material and/or the coating are composed of identical materials.

3. The coating system of claim 1, wherein said first adhesive layer material and second adhesive layer material are composed of identical materials.

4. The coating system of claim 1, wherein the carrier has a plurality of apertures or perforations, wherein said plurality of apertures or perforations has a number, size, shape and distribution such that the first adhesive layer material flows through the carrier to the opposite side.

5. The coating system of claim 1, wherein the thickness of said carrier is in the range of 60 to 200 μm and the thickness of each of the first and second adhesive layer portions is in the range of 40 to 300 μm.

6. The coating system of claim 1, wherein the adhesive layer comprises a plurality of discrete carriers located in a side by side configuration.

7. The coating system of claim 1, wherein the adhesive layer comprises a plurality of discrete carriers located in a stacked configuration, and the adhesive layer comprises at least a third adhesive layer portion placed between said first and second adhesive layer portions.

8. The coating system of claim 1, wherein the coating is an erosion resistant material.

9. The coating system of claim 1, wherein each of the first and second adhesive layer materials comprises a material selected from among fillers, coatings, primers, adhesives, resins, non-reactive adhesives, hot-melt adhesives, reactive adhesives, multi-part adhesives, polyester resin, polyurethane resin, epoxy resin and single component adhesives.

10. The coating system of claim 1, wherein each of the first and second adhesive layer materials is polyurethane based and the carrier is a polyester based fabric.

11. The coating system of claim 1, wherein the coating system comprises an embedded tear strip.

12. The coating system of claim 1, wherein the first and/or second adhesive layer material comprises at least one selected from the group of curable adhesives and thermoplastics.

13. The coating system of claim 1, wherein the carrier comprises at least one selected from the group of a textile, a woven fabric, and a non-woven fabric, and the carrier has a plurality of apertures or perforations.

14. The coating system of claim 1, wherein the carrier comprises one or more selected from the group of natural fibers, bamboo, hemp, flax, polymeric fibers, nylon, aramid, polyester, inorganic fibers, glass, carbon, basalt, and metals.

15. The coating system of claim 1, wherein the carrier is a film having a plurality of apertures or perforations.

16. The coating system of claim 1, wherein said carrier comprises at least one selected from the group of a nylon fabric, a polyester fabric, a coated fiber reinforced glass fabric, and a peel ply.

17. The coating system of claim 1, wherein said carrier is a non-permeable film.

18. The coating system of claim 1, wherein the coating comprises a plurality of coating layers located on top of each other with each individual coating layer comprising different properties.

19. The coating system of claim 1, wherein the substrate comprises at least one selected from the group of a wind turbine blade, a leading edge of a wind turbine blade, a rotor blade of a tidal stream generator, a leading edge of a rotor blade of a tidal stream generator, a blade of a gas turbine, steam turbine or water turbine, a leading edge surface of an aircraft or aerospace vehicle, an exposed surface of a building, and a part of an offshore substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail below with reference to the accompanying drawing, where:

(2) FIG. 1a shows a cross section of a first embodiment of a coating system according to the invention,

(3) FIG. 1b shows a cross section of the embodiment of the coating system of FIG. 1a, where the carrier is subjected to the action of a peeling force,

(4) FIG. 1c shows a cross section of a second embodiment of a coating system according to the invention,

(5) FIG. 2 shows a wind turbine blade comprising a coating system according to the invention,

(6) FIG. 3a-d show steps of a method for retrofitting a coating system according to the invention,

(7) FIG. 4a-d show steps of a method for repairing a damaged coating of a coating system according to the invention,

(8) FIG. 5-5b shows thickness, adhesive and tensile strengths in a cross section of embodiments of a coating system according to the invention,

(9) FIG. 6a shows a wind turbine blade as a substrate comprising a plurality of coating systems according to the invention,

(10) FIG. 6b shows a cross section of a further embodiment of a coating system according to the invention,

(11) FIG. 7 shows application of a coating system according to the invention on a wind turbine blade of a wind turbine, and

(12) FIG. 8 shows application of a coating system according to the invention on a rotor blade of a tidal stream generator.

(13) In the following, the invention will be described in greater detail with reference to embodiments shown by the enclosed figures. It should be emphasized that the embodiments shown are used for example purposes only and should not be used to limit the scope of the invention.

DESCRIPTION OF THE EMBODIMENTS

(14) In the explanation of the figures, identical or corresponding elements will be provided with the same designations in different figures. Therefore, no explanation of all details will be given in connection with each single figure/embodiment.

(15) FIGS. 1a and 1b shows a cross section of a first embodiment of a coating system 1 for coating the surface 3 of a substrate 5.

(16) The coating system 1 comprises a coating 7 and an adhesive layer 9.

(17) The coating 7 may be any coating that is suitable for a given application. An example of a coating 7 is an erosion resistant material, such as a material with relatively higher resistance to erosion for example by a flow of fluids, than the substrate itself.

(18) The adhesive layer 9 comprises a carrier 11 and an adhesive. The adhesive layer material is divided by the carrier 11 into a first adhesive layer portion 13 that adheres to the surface 3 of the substrate 5 and a second adhesive layer portion 15 that adheres to the coating 7. Both adhesive layer portions 13, 15 adhere to the carrier 11.

(19) The first adhesive layer portion 13 comprises a first adhesive layer material and the second adhesive layer portion 15 comprises a second adhesive layer material.

(20) The first and second adhesive layer material has an adhesive or bond strength to the surface 3 of the substrate 5 and to the coating 7 respectively that exceeds its cohesive or tensile strength. In contrast the adhesive or bond strength between the first adhesive layer material and the carrier 11 is less than the cohesive strength of both the first and second adhesive layer materials and the carrier, respectively.

(21) When the carrier 11 is subjected to a peeling force, as indicated with arrow 16, it will separate from the first adhesive layer portion 13 at the interface between said first adhesive layer portion 13 and the carrier 11 as illustrated in FIG. 1b.

(22) In FIG. 1b it can be seen how the coating 7 remains attached to the carrier 11, such that waste during removal of a damaged coating is minimized.

(23) The second adhesive layer portion 15 and the coating 7 is locally removed near the edge of the carrier 11 to enable removal of the carrier 11.

(24) In some instances the coating 7 may crack and become detached from the carrier 11. A brittle coating material will have this tendency.

(25) The exposed surface 18 of the first adhesive layer portion 13 will form the base for a replacement coating system 1 to be applied to the substrate 5.

(26) As the coating 7 is replaced a number of times there will be a gradual increase in thickness of the first adhesive layer portion 13. This is because a new first adhesive layer portion (not shown) is applied to the existing first adhesive layer portion 13 during each replacement action.

(27) FIG. 1c shows a cross section of a second embodiment of a coating system 1 according to the invention.

(28) The second embodiment differs from the first embodiment in that the second embodiment comprises a plurality of coating layers 17′, 17″, 17′″.

(29) FIG. 2 shows a wind turbine blade 19 comprising a coating system 1 according to the invention.

(30) In the embodiment shown the coating system 1 is applied to the leading edge 21 of the wind turbine blade 19, more specifically the part of the leading edge 21 that is closer to the tip 23 of the blade.

(31) The carrier is not visible on FIG. 2. However, in one embodiment the coating system 1 comprises a single carrier 11.

(32) Tear strips 25 are embedded at the outline of the carrier 11. When pulling the tear strips 25 the coating 9 is cut and the carrier 11 becomes accessible.

(33) In one embodiment (Not shown in FIG. 2) the coating system 1 comprises a plurality of discrete carriers 11.

(34) In all embodiments shown the adhesive can be selected among curable adhesives.

(35) In all embodiments shown the first and/or second adhesive layer materials and the coating can be composed of identical materials.

(36) In all embodiments shown the carrier can be a fabric or a film having a plurality of perforations.

(37) In all embodiments shown the coating may be an erosion resistant material.

(38) FIGS. 3a to 3d show steps of a method for retrofitting a coating system according to an embodiment of the invention. Before retrofitting the coating system, the surface 3 of the substrate 5 should be clean and prepared, preferably including removing or priming any previously applied coating or adhesives.

(39) FIG. 3a shows the application of a first adhesive layer material e.g. with a paint brush, roller, spatula or spray to form a first adhesive layer portion 13 on the surface 3 on a substrate 5.

(40) FIG. 3b shows the application of a carrier 11 on the first adhesive layer portion 13 wherein the carrier 11 is positioned on the not yet hardened first adhesive layer material.

(41) The right enlargement of the Figure shows a section of the carrier 11 as seen slightly from above and with a plurality of apertures or perforations illustrated in the carrier.

(42) The left enlargement of the Figure shows that some of the adhesive layer material of the first adhesive layer portion 13 flows through the carrier 11 to the other side via a plurality of apertures or perforations in the carrier.

(43) Alternative embodiments without an adhesive soaked carrier 11 are also possible e.g., a carrier without a plurality of apertures or perforations but having a non-permeable surface structure capable of bonding with the adhesive layer material.

(44) FIG. 3c shows the application of a second adhesive layer material e.g. with a paint brush, roller, spatula or spray to form a second adhesive layer portion 15 on the carrier 11. The second adhesive layer material may also bridge with the adhesive layer material of the first adhesive layer portion 13 which has flown through the plurality of apertures or perforations in the carrier 11. The established bridges provide mechanical adherence between the carrier 11 and the first and second adhesive layer materials 13, 15.

(45) FIG. 3d shows the application of a coating layer 17 e.g. with a paint brush, roller, spray, spatula or e.g. as a, preferably adhesive, film, tape or sheet, on the second adhesive layer portion 15. The coating layer 17 is preferably applied after the curing of the first and second adhesive layer materials.

(46) FIG. 4a-d show steps of a method for repairing a damaged coating of a coating system according to an embodiment of the invention.

(47) FIG. 4a shows a substrate 5 after a damaged coating system has been removed by applying a peeling force to a carrier, such that the carrier separated from the first adhesive layer portion while carrying the damaged coating. This original first adhesive layer portion 13′ is hereby exposed but remains on the surface 3 of the substrate 5. A first adhesive layer portion 13 is applied as a method step on the original first adhesive layer portion 13′ e.g. with a paint brush, roller, spatula or spray.

(48) FIG. 4b-d show repair method steps corresponding to the retrofit method steps shown in FIGS. 3b-3d and as described above.

(49) FIG. 5 and FIG. 5a-5b show thickness, adhesive and tensile strengths of the carrier 11 and first and second adhesive layer portions 13, 15 in a cross section and enlarged cross sections of embodiments of a coating system 1 according to the invention.

(50) The first adhesive layer material and second adhesive layer material may be composed of identical or different materials.

(51) FIG. 5a shows an enlargement of the coating system 1 in FIG. 5. The adhesive or bond strength AS.sub.1, AS.sub.2 of the first and second adhesive layer materials to the surface of the substrate 5 and to the coating layer 17 respectively is preferably between 6 and 12 MPa (ASTM D4541). The respective cohesive or tensile strength TS.sub.1, TS.sub.2 of said first adhesive layer material and second adhesive layer material is preferably between 4 and 6 MPa (ASTM D4541).

(52) The first and second adhesive layer materials and carrier combination is configured for having an adhesive strength (AS3, AS4) that is less than their respective cohesive or tensile strength (TS1, TS2).

(53) FIG. 5b shows an enlargement of another embodiment of a coating system 1 as illustrated in FIG. 5. The thickness T.sub.c of the carrier 11 or, in a stacked configuration as shown in FIG. 6b, a plurality of carriers 11′, 11″, 11′″, 11″″, may for example be in the range of 60 to 200 μm, e.g. 80 to 120 μm, each, preferably approx. 100 μm. The thickness T.sub.1, T.sub.2 of the first and second adhesive layer portion 13, 15 is preferably in the range of 40 to 300 μm, for example in the range of 60 to 100 μm, and in the range of 80 to 300 μm, for example in the range of 80 to 100 μm, respectively. For example, an embodiment with a carrier thickness being about the same or larger than the thickness of the first adhesive layer portion 13 and the thickness of the second adhesive layer portion 15, or an embodiment with adhesive layer portions thicker than the carrier, or an embodiment with a very thing first adhesive layer portion and a thicker second adhesive layer portion. Depending on the application technique, e.g. painting, spraying, etc., the thickness T.sub.1, T.sub.2 of the first and second adhesive layer portion 13, 15 may be fluctuating over the area covered by the coating system.

(54) FIG. 6a shows a wind turbine blade 19 exemplifying an application of a substrate comprising a plurality of coating systems 1a, 1b, 1c, 1d according to the invention. The plurality of coating systems 1a, 1b, 1c, 1d is located in a side-by-side configuration along the leading edge 21 of the wind turbine blade with the one coating system 1d coating the surface at the blade tip 23.

(55) The plurality of coating systems may be placed on the substrate as separate and independent systems i.e. with uncoated surface of the substrate in between adjacent systems.

(56) The coating systems may also be placed on the substrate as partly overlapping systems i.e. with no uncoated surface of the substrate in between adjacent overlapping systems. The size of overlap between two systems may be just sufficient to also ensure a protection of the substrate in the area of the overlap e.g. to avoid any separate coating work in the area between adjacent coating systems.

(57) The coating systems 1a, 1b, 1c, 1d may comprise one common or a plurality of separate embedded tear strips 25.

(58) FIG. 6b shows a cross section of a further embodiment of a coating system 1 according to the invention. The coating system has a plurality of adhesive layer portions and carriers located in a stacked configuration between the coating layer 17 and the substrate 5 e.g. a wind turbine blade as disclosed in FIG. 6a.

(59) The first adhesive layer portion 13 and the second adhesive layer portion 15 is located adjacent to the substrate 5 and the coating layer 17, respectively. A carrier 11′ is located between the first adhesive layer portion 13 and a third adhesive layer portion 27 and a further carrier 11″ is located between the third adhesive layer portion 27 and a fourth adhesive layer portion 28. An even further carrier 11′″ is located between the fourth adhesive layer portion 28 and a fifth adhesive layer portion 29. The last carrier 11″″ in the embodiment is located between the second adhesive layer portion 15 and the fifth adhesive layer portion 29.

(60) Embodiments with stacked configurations comprising further or fewer carriers and adhesive layer portions than shown in FIG. 6b located between the first and second adhesive layer portion 13, 15 are also possible.

(61) By including a plurality of carriers in a stacked configuration makes it possible to remove one carrier and the coating layer from a substrate as part of a repair method, while the stack of remaining carriers is recoated to establish the coating system on the substrate again, without the need to provide a new carrier. Hence, the coating system may easily be repaired as many times as the number of carriers included in the original stack, simply by applying new coating, preferably on a fresh second adhesive layer portion, without new carriers having to be refitted on the substrate.

(62) FIG. 7 shows application of a coating system 1 according to the invention on a wind turbine blade 21 of an operational wind turbine 31 such as an offshore wind turbine. The coating system 1 is being applied as part of a retrofit or repair method to the leading edge of the wind turbine blade in a locked standby position by a maintenance worker standing in a work basket of a maintenance crane 33. The repairing or retrofitting methods of embodiments of the present invention may also be performed by any other blade access techniques, for example rope access, for example with a service platform or personal harness suspended by wiring from the wind turbine nacelle. The coating 7 of the coating system may in this example preferably be a conventionally available leading edge protection material selected in consideration of the specific application, environment and cost-effectiveness.

(63) FIG. 8 shows application of a coating system 1 according to the invention on a rotor blade 37 of a tidal stream generator 35. The tidal stream generator is shown as located in an inactive position above the sea surface (full lines) and in an operational position below the sea surface (dotted lines). The coating system 1 is being applied as part of a retrofit or repair method to the leading edge of the rotor blade above the sea surface by a maintenance worker standing in a work basket of a maintenance crane 33.

(64) The coating system 1 according to the invention may in a similar manner as shown in FIGS. 7 and 8 be applied to a blade of other offshore substrates as well as be applied to a blade of a gas turbine, steam turbine or water turbine, a leading edge surface of an aircraft or aerospace vehicle or an exposed surface of a building, for example in desert area.

(65) It is to be noted that the figures and the above description have shown the example embodiments in a simple and schematic manner.

LIST

(66) 1. Coating system 1a, 1b, 1c, 1d. A plurality of coating systems 3. Surface of a substrate 5. Substrate 7. Coating 9. Adhesive layer 11. Carrier 11′, 11″, 11′″, 11″″. Plurality of carriers 13. First adhesive layer portion 13′. Original first adhesive layer portion of a removed coating system 15. Second adhesive layer portion 16. Peeling force applied to a carrier 17. Coating layer 17′, 17″, 17′″. Plurality of coating layers 18. Exposed surface of the first adhesive layer portion 19. Wind turbine blade 21. Leading edge of the wind turbine blade 23. Tip of the wind turbine blade 25. Tear strips 27, 28, 29. Third, fourth and fifth adhesive layer portions 31. Wind turbine 33. Maintenance crane 35. Tidal stream generator 37. Rotor blade in a tidal stream generator AS.sub.1, AS.sub.2. Adhesive or bond strength for a first and second adhesive layer material to the surface of the substrate and the coating, respectively AS.sub.3, AS.sub.4. Adhesive or bond strength for a first and second adhesive layer material to the carrier TS.sub.1, TS.sub.2. Cohesive or tensile strength of a first and second adhesive layer material PF. Peeling force (16) T.sub.1, T.sub.2. Thickness of a first and second adhesive layer portion T.sub.c. Thickness of a carrier