CA2165585A1 - Method for the prevention of cathodic disbondment - Google Patents
Method for the prevention of cathodic disbondmentInfo
- Publication number
- CA2165585A1 CA2165585A1 CA 2165585 CA2165585A CA2165585A1 CA 2165585 A1 CA2165585 A1 CA 2165585A1 CA 2165585 CA2165585 CA 2165585 CA 2165585 A CA2165585 A CA 2165585A CA 2165585 A1 CA2165585 A1 CA 2165585A1
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- Canada
- Prior art keywords
- continuous layer
- polymer
- coating
- composition
- metallic article
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Application Of Or Painting With Fluid Materials (AREA)
Abstract
A method for the protection of a metallic article from cathodic disbondment of the coating is disclosed. The method comprises coating the metallic article with a first continuous layer of a first polymeric composition, and then coating the first continuous layer with a second continuous layer of a second polymeric composition. The first and second polymeric compositions may be the same or different.
The first continuous layer is an electrically conductive layer and the second continuous layer is an electrically non-conductive layer. The second continuous layer forms an adherent and protective coating on the first continuous layer.
The first continuous layer is an electrically conductive layer and the second continuous layer is an electrically non-conductive layer. The second continuous layer forms an adherent and protective coating on the first continuous layer.
Description
~ 65585 _ -- 1 METHOD FOR THE PREVENTION OF CATHODIC DISBONDMENT
The present invention relates to the coating of metal objects, and particularly metal pipes, when cathodic protection is applied to the metal, with two (or more) layer coating compositions that will reduce or eliminate cathodic disbondment of the coating from the metal.
Metal objects frequently come in contact with either the ground or with water in the environment and must be protected against corrosion. For instance, buried metal pipelines employed to convey liquids e.g. petroleum products, are susceptible to substantial corrosion due to the moist, often acidic or alkaline, environments of the soil in which they are buried. Other metal structures in contact with the ground or with aqueous environments e.g.
lakes, rivers or the sea, include those portions of above-ground storage tanks that are in contact with the ground, underground storage tanks, steel reinforcing bars for concrete or the like, steel pilings and other submerged structures.
A number of methods have been devised in attempts to protect metal objects from corrosion. For instance, cathodic protection from corrosion may be provided by a procedure involving the application of an electric potential between the metal of the pipe and the material e.g. earth, that surrounds the pipe. One or more coatings may be applied to the outer surface of the pipe so as to physically protect the pipe surface from the corrosive environments that may be encountered and to insulate the pipe to minimize current loss. With regard to the latter, the coating of metal objects with epoxy/polyolefin coatingcompositions is disclosed in published PCT patent application WO 92/03234 of J.W. Cox and T.A. Pfaff, published March 5, 1992, and in patents referred to therein. Girthweld cutbacks of a concrete-coated pipe have been coated with an electrically conductive film, as disclosed in Canadian Patent 1 239 901 of R.M. Robinson, issued August 02, 1988.
A process for the coating of metal objects to reduce or eliminate cathodic disbondment has now been found.
Accordingly, an aspect of the present invention provides a method for the protection of a metallic article from cathodic disbondment of a coating, comprising:
(a) coating the metallic article with a first continuous layer of a first polymeric composition;
(b) coating the first continuous layer with a second continuous layer of a second polymeric composition;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
In preferred embodiments of the method of the present invention, at least the portion of the metallic article that would be in contact with earth or an aqueous environment is coated with the continuous electrically conductive layer.
In another embodiment, the polymers of the first and second polymer composition are the same.
In yet another embodiment, the polymers of the first and second composition are different but are capable of bonding together, both chemically and physically.
In a further embodiment of the present invention, the polymer of the first polymeric composition is an epoxy polymer and the polymer of the second polymeric composition is an epoxy polymer, a urethane polymer or a modified polyolefin.
The present invention further provides a coated metallic article comprising:
(a) a first continuous layer of a first polymeric composition coated on the metallic article;
21 655~5 _ - 3 -(b) a second continuous layer of a second polymeric composition coated on the first continuous layer;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
The first conductive layer is formed from a polymeric composition that is electrically conductive. The polymer of the composition needs to be a polymer that is capable of being applied to a metallic object to form a coating. If the first polymer is not inherently conductive, then it is necessary to add a material that is electrically conductive to the first polymer to produce a polymeric composition which, in the form applied to the metallic object, is electrically conductive. This may be accomplished in at least two ways e.g. by blending in a polymer that is electrically conductive in an amount to provide a polymer composition that is electrically conductive or by adding particles of a material that is electrically conductive in an amount that produces a polymeric composition that is electrically conductive.
Examples of particles that are electrically conductive include flakes or fibres or other configurations of electrically conductive metals e.g. aluminum, copper and other metals, as well as carbon. A wide variety of materials could be used, provided that the materials are compatible with the polymer of the coating and the environment of use.
The electrically conductive coating should have an electrical resistance of between 1 and 1000 ohms, and preferably between 5 and 100 ohms.
The polymeric composition used to form the first polymeric composition, and optionally also the second polymeric composition, needs to be capable of bonding to the metallic article to form a continuous and adherent protective layer. Such polymeric compositions are known 2~ 65585 _ - 4 and include epoxy resins. It is understood that the metallic article must be suitably cleaned prior to application of the coating. One example of an epoxy resin is a polyglycidyl ether of a polyhydric phenol having a softening point (Durrans') of at least about 90C and preferably from about 90 to about 130C, and a curing agent for the epoxy resin. Examples of polyglycidyl ethers are those obtained from the condensation of bisphenol A
(2,2'bis(hydroxy-phenyl)propane) and epichlorohydrin.
Other polymer compositions that will form the adherent protective layer may be used.
The second polymeric composition may be formed from the same polymer as that used to form the first polymeric composition. Alternatively, the polymer of the second composition may be different from that of the first polymeric composition. If so, then the polymer of the second polymeric composition needs to be capable of bonding to the polymer of the first polymeric composition to form an adherent layer on the first polymeric composition.
An example of a polymer for the second polymeric composition is a modified polyolefin that is a grafted homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms e.g. grafted homopolymers or copolymers of ethylene, propylene, butene-l, 4-methyl pentene-l, hexene-l and octene-l, especially homopolymers and copolymers of ethylene and propylene. As will be appreciated by persons skilled in the art, such polymers may have a broad range of molecular weights if the polymer is to be applied to the pipe as a powder coating but a more limited range if the polymer is to be applied by extrusion techniques. The grafted monomer may be at least one alpha,beta-ethylenically unsaturated carboxylic acid or anhydride, including derivatives of such acids and anhydrides, especially maleic anhydride or acrylic acid.
Methods for the grafting of monomers onto polymers are known in the art, and include solution grafting processes and melt grafting processes.
Alternatively, the modified polyolefin may be a synthesized copolymer of alpha-olefins and alpha, beta-ethylenically unsaturated carboxylic acids or anhydrides.
Examples of such polymers include ethylene acrylic acid copolymers (EEA), for instance Envilon~ polymers from Dow Chemical.
Another example of a polymer for the second polymeric composition is a polyurethane, which may be obtained by reaction of either a hydroxylated resin or an amine/amide resin with an isocyanate resin. An example is Valpipe~ 100 urethane coating from Valspar Inc.
Examples of the second polymeric compositions are commercially available.
The polymer of the first composition must have good adhesion to properly prepared steel, or other metal from which the article is fabricated, and be able to withstand immersion conditions. The conductivity of the polymers is important in enhancement of the cathodic disbondment resistance of the coating and does not necessarily contribute to the other physical properties of the finished product. The conductivity of the first layer allows the electrical current to pass through this layer and be insulated by the second coating layer. Since the bond between the first and second layers should be covalent in nature, in order to form an adherent and protective coating, the tendency to disbond at their interface is almost eliminated. Examples of combinations of polymers that may form covalently bonds include:
(a) amine cured epoxy coating with a urethane coating;
(b) polyamide cured epoxy coating with a urethane coating;
(c) polyamide or amine cured epoxy coating with a modified polyolefin coating; and (d) polyester coating with a urethane or epoxy coating. Combinations of such coatings may also be used _ - 6 -e.g. amine cured epoxy coating topcoated with an amine cured epoxy coating.
Additional polymers and/or stabilizing agents e.g. antioxidants for example phenolic antioxidants, W
stabilizers and heat stabilizers, pigments e.g. titanium dioxide and carbon black, extenders e.g. mica and glass, corrosion inhibiting agents, fillers e.g. talc, calcium carbonate and mica, slip agents and flame retardants or the like may be added, especially to the second polymeric composition.
The invention has been described herein with reference to a first electrically conductive layer and a second electrically non-conductive layer. It is to be understood that the second layer could be in the form of multi-layers of non-conductive compositions i.e. multi-layers including so-called tie layers could be applied on top of the electrically conductive first layer.
The metal of the metallic object will usually be steel. Steel is used in the construction of pipelines, tanks, reinforcing for concrete, and in a variety of other end uses involving contact of the metallic object with the ground or with aqueous environments. The metallic object may have a variety of shapes, including pipelines, storage tanks which may be fully or partially above ground, steel reinforcing bars for concrete, steel pilings, offshore structures which are submerged in part in the sea, and a variety of other shapes.
The present invention is illustrated by the following examples.
Example I
A steel coupon was cleaned by abrasive blasting using G-25 steel grit at a pressure of 100 psi. The cleanliness of the coupon was verified to be that of SSPC-SP10, a procedure specified by the Steel Structures Painting Council.
The cleaned coupon was then coated with the following composition.
~1 ~5S~5 _ - 7 -A. A conductive layer of an epoxy coating was applied at a thickness of 15 mils using a brush. The coating composition was as follows:
57% by weight of Epon 828 epoxide resin (Shell Chemical Co.);
7% by weight of Ketjen Black 600 (Akzo Chemical);
7% by weight of Conductive polymer identified as Elastchem Antistat (Plastomer Inc.); and 28% by weight of Amino Ethyl Piperizine (Dow Chemical Limited) B. A top coat was applied while the first layer was still reactive, to ensure good adhesion. This layer was:
60% by weight of Epon 828 epoxide resin;
20% by weight of Amino Ethyl Piperazine;
20% by weight of Barium Sulphate;
The coated coupon was allowed to cure for 28 hours at ambient temperature prior to testing.
The test used was according to the procedures of Canadian Standards Association (CSA) standards for fusion bonding epoxy coatings, specifically the cathodic disbondment resistance test, using the following conditions. The solution used was a 5% by weight sodium chloride solution at 65C. A voltage of -1.5 V was applied. It was found that after both 14 days and 28 days duration of testing on different samples, the amount of disbondment was 0 mm.
Example II
A steel pipe length with a 6 inch internal diameter and a wall thickness of 0.5 inches was abrasive blasted using 1624 grit to a standard of SSPC-SP5. A
profile of 3.5 mils (approx. 90 micron) was achieved at a nozzle pressure of 110 psi.
The pipe length was then coated with an epoxy of composition 57% by weight Epon~ 828 epoxide resin 7% by weight Ketgen black 21 655~5 7% by weight conductive polymer (as in Example I) and 21% by weight amino ethyl piperazine 7% by weight Versamine~ 125 amine resin (Henkel Corp.) The topcoat was applied after a 30 minute set up time at 25C.
The topcoat was a commercially available elastomer urethane called Polibrid 705 manufactured by Polibrid Coatings of Brownsville, Texas, U.S.A.
The coated pipe was allowed to cure for 12 hours at 40C before testing. The elastomer topcoat was chosen to give a higher degree of impact and abrasion resistance than the epoxy topcoat.
The cathodic disbondment testing was done to the standards of the procedure of ASTM G8.
After 28 days, there was no cathodic disbondment of the coating from the steel.
The present invention relates to the coating of metal objects, and particularly metal pipes, when cathodic protection is applied to the metal, with two (or more) layer coating compositions that will reduce or eliminate cathodic disbondment of the coating from the metal.
Metal objects frequently come in contact with either the ground or with water in the environment and must be protected against corrosion. For instance, buried metal pipelines employed to convey liquids e.g. petroleum products, are susceptible to substantial corrosion due to the moist, often acidic or alkaline, environments of the soil in which they are buried. Other metal structures in contact with the ground or with aqueous environments e.g.
lakes, rivers or the sea, include those portions of above-ground storage tanks that are in contact with the ground, underground storage tanks, steel reinforcing bars for concrete or the like, steel pilings and other submerged structures.
A number of methods have been devised in attempts to protect metal objects from corrosion. For instance, cathodic protection from corrosion may be provided by a procedure involving the application of an electric potential between the metal of the pipe and the material e.g. earth, that surrounds the pipe. One or more coatings may be applied to the outer surface of the pipe so as to physically protect the pipe surface from the corrosive environments that may be encountered and to insulate the pipe to minimize current loss. With regard to the latter, the coating of metal objects with epoxy/polyolefin coatingcompositions is disclosed in published PCT patent application WO 92/03234 of J.W. Cox and T.A. Pfaff, published March 5, 1992, and in patents referred to therein. Girthweld cutbacks of a concrete-coated pipe have been coated with an electrically conductive film, as disclosed in Canadian Patent 1 239 901 of R.M. Robinson, issued August 02, 1988.
A process for the coating of metal objects to reduce or eliminate cathodic disbondment has now been found.
Accordingly, an aspect of the present invention provides a method for the protection of a metallic article from cathodic disbondment of a coating, comprising:
(a) coating the metallic article with a first continuous layer of a first polymeric composition;
(b) coating the first continuous layer with a second continuous layer of a second polymeric composition;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
In preferred embodiments of the method of the present invention, at least the portion of the metallic article that would be in contact with earth or an aqueous environment is coated with the continuous electrically conductive layer.
In another embodiment, the polymers of the first and second polymer composition are the same.
In yet another embodiment, the polymers of the first and second composition are different but are capable of bonding together, both chemically and physically.
In a further embodiment of the present invention, the polymer of the first polymeric composition is an epoxy polymer and the polymer of the second polymeric composition is an epoxy polymer, a urethane polymer or a modified polyolefin.
The present invention further provides a coated metallic article comprising:
(a) a first continuous layer of a first polymeric composition coated on the metallic article;
21 655~5 _ - 3 -(b) a second continuous layer of a second polymeric composition coated on the first continuous layer;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
The first conductive layer is formed from a polymeric composition that is electrically conductive. The polymer of the composition needs to be a polymer that is capable of being applied to a metallic object to form a coating. If the first polymer is not inherently conductive, then it is necessary to add a material that is electrically conductive to the first polymer to produce a polymeric composition which, in the form applied to the metallic object, is electrically conductive. This may be accomplished in at least two ways e.g. by blending in a polymer that is electrically conductive in an amount to provide a polymer composition that is electrically conductive or by adding particles of a material that is electrically conductive in an amount that produces a polymeric composition that is electrically conductive.
Examples of particles that are electrically conductive include flakes or fibres or other configurations of electrically conductive metals e.g. aluminum, copper and other metals, as well as carbon. A wide variety of materials could be used, provided that the materials are compatible with the polymer of the coating and the environment of use.
The electrically conductive coating should have an electrical resistance of between 1 and 1000 ohms, and preferably between 5 and 100 ohms.
The polymeric composition used to form the first polymeric composition, and optionally also the second polymeric composition, needs to be capable of bonding to the metallic article to form a continuous and adherent protective layer. Such polymeric compositions are known 2~ 65585 _ - 4 and include epoxy resins. It is understood that the metallic article must be suitably cleaned prior to application of the coating. One example of an epoxy resin is a polyglycidyl ether of a polyhydric phenol having a softening point (Durrans') of at least about 90C and preferably from about 90 to about 130C, and a curing agent for the epoxy resin. Examples of polyglycidyl ethers are those obtained from the condensation of bisphenol A
(2,2'bis(hydroxy-phenyl)propane) and epichlorohydrin.
Other polymer compositions that will form the adherent protective layer may be used.
The second polymeric composition may be formed from the same polymer as that used to form the first polymeric composition. Alternatively, the polymer of the second composition may be different from that of the first polymeric composition. If so, then the polymer of the second polymeric composition needs to be capable of bonding to the polymer of the first polymeric composition to form an adherent layer on the first polymeric composition.
An example of a polymer for the second polymeric composition is a modified polyolefin that is a grafted homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms e.g. grafted homopolymers or copolymers of ethylene, propylene, butene-l, 4-methyl pentene-l, hexene-l and octene-l, especially homopolymers and copolymers of ethylene and propylene. As will be appreciated by persons skilled in the art, such polymers may have a broad range of molecular weights if the polymer is to be applied to the pipe as a powder coating but a more limited range if the polymer is to be applied by extrusion techniques. The grafted monomer may be at least one alpha,beta-ethylenically unsaturated carboxylic acid or anhydride, including derivatives of such acids and anhydrides, especially maleic anhydride or acrylic acid.
Methods for the grafting of monomers onto polymers are known in the art, and include solution grafting processes and melt grafting processes.
Alternatively, the modified polyolefin may be a synthesized copolymer of alpha-olefins and alpha, beta-ethylenically unsaturated carboxylic acids or anhydrides.
Examples of such polymers include ethylene acrylic acid copolymers (EEA), for instance Envilon~ polymers from Dow Chemical.
Another example of a polymer for the second polymeric composition is a polyurethane, which may be obtained by reaction of either a hydroxylated resin or an amine/amide resin with an isocyanate resin. An example is Valpipe~ 100 urethane coating from Valspar Inc.
Examples of the second polymeric compositions are commercially available.
The polymer of the first composition must have good adhesion to properly prepared steel, or other metal from which the article is fabricated, and be able to withstand immersion conditions. The conductivity of the polymers is important in enhancement of the cathodic disbondment resistance of the coating and does not necessarily contribute to the other physical properties of the finished product. The conductivity of the first layer allows the electrical current to pass through this layer and be insulated by the second coating layer. Since the bond between the first and second layers should be covalent in nature, in order to form an adherent and protective coating, the tendency to disbond at their interface is almost eliminated. Examples of combinations of polymers that may form covalently bonds include:
(a) amine cured epoxy coating with a urethane coating;
(b) polyamide cured epoxy coating with a urethane coating;
(c) polyamide or amine cured epoxy coating with a modified polyolefin coating; and (d) polyester coating with a urethane or epoxy coating. Combinations of such coatings may also be used _ - 6 -e.g. amine cured epoxy coating topcoated with an amine cured epoxy coating.
Additional polymers and/or stabilizing agents e.g. antioxidants for example phenolic antioxidants, W
stabilizers and heat stabilizers, pigments e.g. titanium dioxide and carbon black, extenders e.g. mica and glass, corrosion inhibiting agents, fillers e.g. talc, calcium carbonate and mica, slip agents and flame retardants or the like may be added, especially to the second polymeric composition.
The invention has been described herein with reference to a first electrically conductive layer and a second electrically non-conductive layer. It is to be understood that the second layer could be in the form of multi-layers of non-conductive compositions i.e. multi-layers including so-called tie layers could be applied on top of the electrically conductive first layer.
The metal of the metallic object will usually be steel. Steel is used in the construction of pipelines, tanks, reinforcing for concrete, and in a variety of other end uses involving contact of the metallic object with the ground or with aqueous environments. The metallic object may have a variety of shapes, including pipelines, storage tanks which may be fully or partially above ground, steel reinforcing bars for concrete, steel pilings, offshore structures which are submerged in part in the sea, and a variety of other shapes.
The present invention is illustrated by the following examples.
Example I
A steel coupon was cleaned by abrasive blasting using G-25 steel grit at a pressure of 100 psi. The cleanliness of the coupon was verified to be that of SSPC-SP10, a procedure specified by the Steel Structures Painting Council.
The cleaned coupon was then coated with the following composition.
~1 ~5S~5 _ - 7 -A. A conductive layer of an epoxy coating was applied at a thickness of 15 mils using a brush. The coating composition was as follows:
57% by weight of Epon 828 epoxide resin (Shell Chemical Co.);
7% by weight of Ketjen Black 600 (Akzo Chemical);
7% by weight of Conductive polymer identified as Elastchem Antistat (Plastomer Inc.); and 28% by weight of Amino Ethyl Piperizine (Dow Chemical Limited) B. A top coat was applied while the first layer was still reactive, to ensure good adhesion. This layer was:
60% by weight of Epon 828 epoxide resin;
20% by weight of Amino Ethyl Piperazine;
20% by weight of Barium Sulphate;
The coated coupon was allowed to cure for 28 hours at ambient temperature prior to testing.
The test used was according to the procedures of Canadian Standards Association (CSA) standards for fusion bonding epoxy coatings, specifically the cathodic disbondment resistance test, using the following conditions. The solution used was a 5% by weight sodium chloride solution at 65C. A voltage of -1.5 V was applied. It was found that after both 14 days and 28 days duration of testing on different samples, the amount of disbondment was 0 mm.
Example II
A steel pipe length with a 6 inch internal diameter and a wall thickness of 0.5 inches was abrasive blasted using 1624 grit to a standard of SSPC-SP5. A
profile of 3.5 mils (approx. 90 micron) was achieved at a nozzle pressure of 110 psi.
The pipe length was then coated with an epoxy of composition 57% by weight Epon~ 828 epoxide resin 7% by weight Ketgen black 21 655~5 7% by weight conductive polymer (as in Example I) and 21% by weight amino ethyl piperazine 7% by weight Versamine~ 125 amine resin (Henkel Corp.) The topcoat was applied after a 30 minute set up time at 25C.
The topcoat was a commercially available elastomer urethane called Polibrid 705 manufactured by Polibrid Coatings of Brownsville, Texas, U.S.A.
The coated pipe was allowed to cure for 12 hours at 40C before testing. The elastomer topcoat was chosen to give a higher degree of impact and abrasion resistance than the epoxy topcoat.
The cathodic disbondment testing was done to the standards of the procedure of ASTM G8.
After 28 days, there was no cathodic disbondment of the coating from the steel.
Claims (15)
1. A method for the protection of a metallic article from cathodic disbondment of the coating comprising:
(a) coating the metallic article with a first continuous layer of a first polymeric composition;
(b) coating the first continuous layer with a second continuous layer of a second polymeric composition;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
(a) coating the metallic article with a first continuous layer of a first polymeric composition;
(b) coating the first continuous layer with a second continuous layer of a second polymeric composition;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
2. The method of Claim 1 in which at least the portion of the metallic article that would be in contact with earth or an aqueous environment is coated with the continuous electrically conductive layer.
3. The method of Claim 2 in which the composition is applied in (a) to provide a coating with an electrical resistance in the range of 1 to 1000 ohms.
4. The method of Claim 2 in which the composition is applied in (a) to provide a coating with an electrical resistance in the range of 5 to 100 ohms.
5. The method of any one of Claims 1-4 in which the polymers of the first and second polymer composition are the same.
6. The method of any one of Claims 1-4 in which the polymers of the first and second composition are different but are capable of bonding together, both chemically and physically.
7. The method of any one of Claims 1-4 in which the polymer of the first polymeric composition is an epoxy polymer and the polymer of the second polymeric composition is an epoxy polymer, a urethane polymer or a modified polyolefin.
8. The method of any one of Claims 1-7 in which the metallic article is formed from steel.
9. A coated metallic article comprising:
(a) a first continuous layer of a first polymeric composition coated on the metallic article;
(b) a second continuous layer of a second polymeric composition coated on the first continuous layer;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
(a) a first continuous layer of a first polymeric composition coated on the metallic article;
(b) a second continuous layer of a second polymeric composition coated on the first continuous layer;
said first continuous layer being an electrically conductive layer and said second continuous layer being an electrically non-conductive layer;
the second continuous layer forming an adherent and protective coating on the first continuous layer.
10. The coated metallic article of Claim 9 in which the composition of (a) has an electrical resistance in the range of 1 to 1000 ohms.
11. The coated metallic article of Claim 9 in which the composition of (a) has an electrical resistance in the range of 5 to 100 ohms.
12. The coated metallic article of any one of Claims 9-11 in which the polymers of the first and second polymer composition are the same.
13. The coated metallic article of any one of Claims 9-11 in which the polymers of the first and second polymer composition are different, and are bonded together both chemically and physically.
14. The coated metallic article of any one of Claims 9-11 in which the polymer of the first polymeric composition is an epoxy polymer and the polymer of the second polymeric composition is an epoxy polymer, a urethane polymer or a modified polyolefin.
15. The coated metallic article of any one of Claim 9-14 in which the metal is steel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9425557.7 | 1994-12-19 | ||
| GBGB9425557.7A GB9425557D0 (en) | 1994-12-19 | 1994-12-19 | Method for the prevention of cathodic disbondment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2165585A1 true CA2165585A1 (en) | 1996-06-20 |
Family
ID=10766141
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2165585 Abandoned CA2165585A1 (en) | 1994-12-19 | 1995-12-19 | Method for the prevention of cathodic disbondment |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2165585A1 (en) |
| GB (1) | GB9425557D0 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3569632A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569631A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569630A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569629A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3660069A1 (en) | 2018-11-29 | 2020-06-03 | Evonik Operations GmbH | Fast curing epoxy systems |
-
1994
- 1994-12-19 GB GBGB9425557.7A patent/GB9425557D0/en active Pending
-
1995
- 1995-12-19 CA CA 2165585 patent/CA2165585A1/en not_active Abandoned
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3569632A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569631A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569630A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| EP3569629A1 (en) | 2018-05-17 | 2019-11-20 | Evonik Degussa GmbH | Fast curing epoxy systems |
| US11286335B2 (en) | 2018-05-17 | 2022-03-29 | Evonik Operations Gmbh | Fast-curing epoxy systems |
| US11359048B2 (en) | 2018-05-17 | 2022-06-14 | Evonik Operations Gmbh | Fast-curing epoxy systems |
| US11370877B2 (en) | 2018-05-17 | 2022-06-28 | Evonik Operations Gmbh | Fast-curing epoxy systems |
| US11370876B2 (en) | 2018-05-17 | 2022-06-28 | Evonik Operations Gmbh | Fast-curing epoxy systems |
| EP3660069A1 (en) | 2018-11-29 | 2020-06-03 | Evonik Operations GmbH | Fast curing epoxy systems |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9425557D0 (en) | 1995-02-15 |
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