CORROSION PREVENTION TAPE

Abstract

The present invention relates to a corrosion prevention tape for wrapping an irregular pipe section, the tape comprising: (i) an adhesive component, the adhesive component comprising: from 10 to 50 wt % functionally modified elastomer, and from 0.1 to 20 wt % discrete reinforcing strands dispersed within the adhesive component; and (ii) a backing layer for the adhesive component.

Claims

1. A corrosion prevention tape for wrapping an irregular pipe section, the tape comprising: (i) an adhesive component, the adhesive component comprising: from 10 to 50 wt % functionally modified elastomer, and from 0.1 to 20 wt % discrete reinforcing strands dispersed within the adhesive component; and (ii) a backing layer for the adhesive component.

2. The corrosion prevention tape according to claim 1, wherein the functionally modified elastomer (FME) comprises an elastomeric backbone including a plurality of side chains bearing at least one polar functional group, preferably wherein the at least one polar functional group is selected from the group consisting of a carboxylic acid, chloro, chlorosulfanyl, epoxy, nitrile, sulphide and mixtures of two or more thereof.

3. The corrosion prevention tape according to claim 2, wherein the FME is selected from the group consisting of an acrylic polymer, a carboxylic polymer, polychloroprene, chlorinated polyethylene, a chlorosulphanyl polymer, a epichlorohydrin polymer, an ethylene acrylic copolymer, isobutylene-paramethylstyrene copolymer, a nitrile polymer, a blend of PVC and a nitrile polymer, polysulphide polymer, a styrene butadiene copolymer, and mixtures of two or more thereof.

4. The corrosion prevention tape according to claim 2, wherein the FME is selected from a) carboxylic polymer b) chlorinated polyethylene c) chlorosulphonated polyethylene d) polychloroprene e) nitrile polymer f) a blend of a nitrile polymer and PVC, and mixtures thereof.

5. The corrosion prevention tape according to claim 1, wherein the discrete reinforcing strands have a length of from 2 to 8 mm.

6. The corrosion prevention tape according to claim 5, wherein the discrete reinforcing strands include strands having a length of from 2 to 4 mm and strands having a length of from 5 to 8 mm, wherein the strands having a length of from 2 to 4 mm and the strands having a length of from 5 to 8 mm are present in a weight ratio of from 1:5 to 1:50, more preferably from 1:10 to 1:40.

7. The corrosion prevention tape according to claim 1, wherein the discrete reinforcing strands are chopped synthetic textile fibre strands, preferably wherein the chopped synthetic textile fibre strands are polyester strands.

8. The corrosion prevention tape according to claim 1, wherein the adhesive component further comprises: from 25 to 70 wt % mineral filler; and/or from 0.05 to 2.5 wt % adhesion promoter; and/or from 5 to 40 wt % plasticizer; and/or from 5 to 30 wt % tackifying resin.

9. The corrosion prevention tape according to claim 8, wherein: the mineral filler is selected from the group consisting of a clay-based mineral filler, a magnesium silicate-based mineral filler, and mixtures of two or more thereof; and/or the adhesion promoter is a thiosilane and/or a liquid carboxylated nitrile butadiene rubber; and/or the plasticizer is selected from the group consisting of chlorinated paraffin, organo phosphates or phthalates, aromatic hydrocarbons and mixtures of two or more thereof; and/or the tackifying resin is selected from the group consisting of a hydrocarbon tackifying resin, a phenolic tackifying resin, a rosin ester, a liquid coumarone resin and mixtures of two or more thereof.

10. The corrosion prevention tape according to claim 1, wherein the adhesive component comprises, expressed as parts by mass per hundred parts by mass elastomer, the following: TABLE-US-00011 Range FME 100 filler 75-150 plasticiser 70-150 tackifying resin 50-125 other additives 1-7

11. The corrosion prevention tape according to claim 10, wherein the adhesive component comprises, expressed as parts by mass per hundred parts by mass elastomer, the following: TABLE-US-00012 Range first FME 70-100 second FME 0-30 mineral filler 75-150 first plasticiser 30-70 second plasticiser 40-80 first tackifying resin 25-50 second tackifying resin 25-75 adhesion promoter 2.5-7.0 first antioxidant 0.5-1.5 second antioxidant 0.5-1.5 colour modifier 0.3-1.5

12. The corrosion prevention tape according to claim 1, wherein the composition forming the backing layer comprises polyvinyl chloride.

13. The corrosion prevention tape according to claim 1, which includes a release film covering the side of the adhesive component remote from the backing layer, preferably wherein the composition forming the release film comprises a non-polar material.

14. The corrosion prevention tape according to claim 1, wherein the adhesive component is vulcanizable, preferably wherein the adhesive component further comprises a curing system which permits vulcanization of the adhesive component, more preferably wherein the curing system comprises one or more of the following: a curing activator, a vulcanization accelerator, and a curing agent.

15. The corrosion prevention tape according to claim 1, wherein the tape is functional at a continuous operating temperature of up to 130 C.

16. A kit for providing a pipe joint with corrosion protection, the kit comprising the corrosion prevention tape according to claim 1 and a flexible wrapping tape.

17. The kit according to claim 16, wherein the composition forming the flexible wrapping tape comprises a vulcanizable rubber.

18. The kit according to claim 17, wherein the composition forming the flexible wrapping tape further comprises a curing system which permits vulcanization of the vulcanizable rubber, preferably wherein the curing system comprises one or more of the following: a curing activator, a vulcanization accelerator, and a curing agent.

19. A corrosion protected article, which includes a substrate, preferably a steel pipe section, covered by a corrosion prevention tape, with at least a portion of the adhesive component of the corrosion prevention tape adhering to the substrate, preferably wherein the article is further provided with a flexible wrapping tape as defined in claim 16 provided on the corrosion prevention tape.

20. A method of protecting a substrate, preferably a steel pipe section, against corrosion, the method comprising wrapping the substrate with a corrosion prevention tape such that at least a portion of the adhesive component of the corrosion prevention tape adheres to the substrate and, optionally, binding the corrosion prevention tape with a flexible wrapping tape as defined in claim 16.

Description

FIGURES

[0113] The present invention will now be described in relation to the following non-limiting FIGURE:

[0114] FIG. 1 shows a diagrammatic three-dimensional view of a portion of a corrosion prevention tape (CPT) in accordance with the invention.

[0115] In the FIGURE, reference numeral 10 generally indicates a corrosion prevention tape according to the invention.

[0116] The tape 10 includes an adhesive component, generally indicated by reference numeral 12, sandwiched between a PVC backing layer 14 and a removable disposable release film 16.

[0117] The adhesive component comprises a functionally modified elastomer (FME). The adhesive component 12 is pliable at the temperature at which the tape is applied to a substrate.

[0118] Discrete reinforcing chopped polyester fibres 18 are dispersed within the adhesive component 12, and are aligned with the parallel longitudinal edges of the tape 10. A vulcanizable PVC flexible sleeve (not shown) can be provided against, and adhering to, the PVC backing layer 14, with the adhesive component 12 and PVC backing layer 14 thus constituting an inner wrap.

[0119] In use, the CPT 10 is applied to a substrate (not shown) such as a steel pipe, to prevent corrosion of the pipe. It is applied by removing the disposable release film and then winding the thus exposed undersurface 20 of the adhesive component 12 against the pipe and wrapping the tape 10 continuously around the pipe so that a portion of the undersurface 20 of a particular loop of the tape 10 around the pipe abuts both the pipe as well as a portion of the backing film of the preceding tape loop.

[0120] The adhesive component 12 ensures good adhesion to both the pipe and to the backing film 14. Thus, the adhesive component 12 forms the steel adhesive component of the CPT 10 and represents the bulk of its mass. The effectiveness of the adhesive component is of crucial importance to the effectiveness of overall protective inner/outer wrap system, since the adhesive component's adhesion to steel is the foundation of the CPT.

[0121] It has been found that the CPT of the invention is, as regards its application to substrates, reasonably tolerant to variations in surface preparation. The adhesive component surface wetting characteristics hereinbefore described are exhibited with a broad range of substrates after minimum of surface preparation. Hydrogen bonds form with any polar substrate, to enhance the Van der Waal's bonds formed from surface wetting.

[0122] However, substrate contaminants, such as oil, grease and moisture, should be removed, prior to wire brushing to remove loose surface solid contaminants. The quality of surface preparation, prior to the application of the CPT, preferably complies with ISO standards. For consistent, durable protection, preparation to St. 2 (wire brushing) is recommended.

[0123] For CPT applications, a crucial property of the adhesive component is robust adhesion to steel substrate over as wide a range of service conditions as possible. Since PVC film has the most desirable all-round physical characteristics for both adhesive component backing film and outer wrap applications, good adhesion to PVC is necessary, not only to prevent water ingress at the PVC/adhesive component interface but also when the inner wrap is wound onto a steel structure. An overlapping technique is employed, as the pipe is wrapped, to provide multi-layer corrosion protection and the adhesive must therefore also bond to the reverse side of the backing film.

[0124] In order for strong, durable adhesive bonds to be formed between steel and elastomeric coverings, an adhesive solution is conventionally applied to the cleaned, abraded steel surface. Such solutions are commercially available under the Lord Corporation brand name Chemlock.

EXAMPLES

[0125] The present invention will now be described in relation to the following non-limiting examples.

Example 1

[0126] A CPT in accordance with the invention was made up to have a reinforced adhesive component composition as set out in Table 1.

[0127] The CPT can be supplied to suit low to moderate temperature, i.e.20 to 60 C, and elevated temperatures i.e. 60-100 C., applications, but equally can be used in high temperature applications (e.g. up to 130 C.) provided it is used in combination with both a vulcanizable FME adhesive, vulcanizable outer wrap and rubber-to-metal bonding agent, such as that provided in Example 3.

TABLE-US-00007 TABLE 1 PARTS PER HUNDRED GENERIC OF ELASTOMER INGREDIENT PRE- INGREDIENT NAME DESCRIPTION RANGE FERRED FUNCTION CSM CHLOROSULPHONATED 70-100 85 ELASTOMER POLYETHYLENE CPE CHLORINATED 0-30 15 ELASTOMER POLYETHYLENE TALC MINERAL FILLER 75-150 120 HYDROPHOBIC DILUENT FILLER ADHESION PROMOTER/ FILLER S THIO SILANE 2.5-7.0 4.5 COUPLING SILANE AGENT LIQUID CNBR CARBOXXYLATED 2.0-6.0 4.0 ADHESION NITRILE RUBBER PROMOTER/ TACKIFIER CHLORINATED CHLORINATED 30-70 40 PLASTICISER POLYETHYLENE PARAFFIN PALE LIQUID LIQUID COUMARONE 40-80 75 PLASTICIZER/ CIR INDENE RESIN TACKIFIER BKF SUBSTITUTED PHENOL 0.5-1.5 1.2 NON-STAINING ANTI-OXIDANT ANTIOXIDANT TMQ SUBSTITUTED PHENOL 0.5-1.5 1.0 NON-STAINING ANTI-OXIDANT ANTIOXIDANT C5 RESIN HYDROCARBON 25-50 25 TACKIFYING TACKIFYING RESIN RESIN GUM ROSIN ROSIN ESTER 10-40 20 TACKIFYING RESIN MICROLITH PHTHALOCYANINE 0.3-1.5 0.3 COLOUR BLUE PIGMENT MODIFIER POLYESTER CHOPPED POLYESTER 2-4 3.0 TENSILE STAPLE YARN, 6 mm, 1.2 dtex REINFORCEMENT POLYESTER CHOPPED POLYESTER 0.05-0.15 0.1 THERMAL STAPLE YARN, 3 mm, 1.2 dtex STABILIZER SUPPLIER & GENERIC TRADE NAME INGREDIENT OF TYPICAL NAME GRADE COMMENT CSM DU PONT: HYPALON Excellent moisture resistance 40 (elastomer commonly used in dam CPE DU PONT: TYRIN linings). High green strength/high TALC SCOTIA TALC filler acceptance. S DE GUSSA: SILANE Si Inherent steel bonding SILANE 69 characteristics. Good PVC LIQUID CNBR HYPRO: EMERALD adhesion when compounded. MATERIALS Excellent oxidation resistance. CHLORINATED DOVER CHEM: Similar properties to CSM but at POLYETHYLENE CHLOROFLO lower cost. PALE LIQUID NEVILLE CHEM: Reduces cost. Low water CIR CUMAR P-10 adsorption. Promotes reduction of BKF BAYER: compound surface tension. VULKANOX BKF Promotes filler/elastomer coupling TMQ BAYER: & labile cross-link formation. VULKANOX DS Improved high temperature flow resistance. C5 RESIN EXXON: Promotes substrate adhesion ESCOREX Promotes substrate adhesion and 1102 surface tack. GUM ROSIN ARIZONA CHEM: Good compatibility with CSM. SYLVALITE Effective reduction in compound MICROLITH BASF: plasticity/surface tension. Good BLUE MICROLITH hydrophobicity. BLUE 7080T Improves effectiveness of POLYESTER BARNET:CHDA912(12) secondary tackifiers & STAPLE hydrophobicity, enables increased POLYESTER BARNET:CHDA912(3) filler loadings, reduces surface tension, STAPLE promotes surface wetting, improves steel/PVC surface compatibility and adhesion. Reduces compound plasticity. Induces no staining or discoloration. Low extractability. Induces no staining or discoloration. Low extractability. General purpose synthetic resin. Improves surface tack. Esterified wood rosin. Improves surface wetting and promotes steel/PVC adhesion. Compounds are colour coded for both identification during manufacture and to differentiate from competitor offerings. Improves tensile reinforcement and thermal stability Improves thermal stability without affecting steel adhesion. FEATURES: Polar functional groups lead to hydrogen bond formation with substrate. Chopped fibre tensile (longitudinal) reinforcement with ease of lateral extensibility, allowing ease of application. Self-healing. Thermally stable.

Example 2

[0128] A CPT in accordance with the invention was made up to have a reinforced adhesive component composition as given in Table 2.

[0129] This CPT is suitable for high temperature applications, i.e. substrate temperatures in excess of 100 C.

TABLE-US-00008 TABLE 2 PARTS PER HUNDRED GENERIC OF RUBBER/ELASTOMER INGREDIENT PRE- INGREDIENT NAME DESCRIPTION RANGE FERRED FUNCTION NBR ACRYLONITRILE 100 100 ELASTOMER BUTADIENE RUBBER TALC MINERAL FILLER 75-150 120 HYDROPHOBIC DILUENT FILLER SILANE THIO SILANE 2.5-7.0 4.5 ADHESION PROMOTER/ COUPLING FILLER COUPLING AGENT AGENT CHDCE CYCLO 30-70 40 POLYMERIC CARBOXYLIC PLASTICISER ESTER PALE LIQUID LIQUID 40-80 75 PLASTICIZER/ CIR COUMARONE TACKIFIER INDENE RESIN BKF SUBSTITUTED 0.5-1.5 1.2 NON-STAINING PHENOL ANTIOXIDANT ANTIOXIDANT TMQ SUBSTITUTED 0.5-1.5 1.0 NON-STAINING PHENOL ANTIOXIDANT ANTIOXIDANT GUM ROSIN ROSIN ESTER 25-75 60 TACKIFYING RESIN MICROLITH PHTHALOCYANINE 0.3-1.5 0.3 COLOUR BLUE PIGMENT MODIFIER POLYESTER CHOPPED POLYESTER 0.7-1.5 0.9 TENSILE STAPLE YARN, 6 mm, 1.2 dtex REINFORCEMENT CBS ZINC OXIDE 3.0-6.0 4 CURING ACTIVATOR STEARIC ACID 0.4-1.8 1 CURING ACTIVATOR CYCLOHEXYL BENZATHIAZOLE 1.0-2.5 1.5 VULCANIZATION SULPHENAMIDE ACCELERATOR TMT TETRAMETHYL 0.3-1.0 0.3 VULCANIZATION THIURAM ACCELERATOR DISULPHIDE DIMORPHOLENE SULPHUR 2.5-4.0 3.0 CURING AGENT DONOR SUPPLIER & GENERIC TRADE NAME INGREDIENT OF TYPICAL NAME GRADE COMMENT NBR BAYER: KRYNAC General purpose, high 2745C molecular weight, nitrile rubber. High green strength. TALC SCOTIA TALC High filler/additive loading capacity. SILANE DE GUSSA: Moderate cure rate at low SILANE Si 69 cure-in-situ temperatures. Reduces cost. Low water adsorption. Low moisture CHDCE BASF: HEXAMOL content. Promotes reduction of DINCH compound surface tension. Promotes filler/elastomer PALE LIQUID NEVILLE CHEM: coupling & labile cross-link CIR CUMAR P-10 formation. Improved high temperature flow resistance. BKF BAYER: Promotes substrate adhesion VULKANOX BKF High permanence/low extractability. Effective TMQ BAYER: reduction in compound VULKANOX DS plasticity/surface tension. Good hydrophobicity. GUM ROSIN ARIZONA CHEM: Improves effectiveness of SYLVALITE secondary tackifiers & MICROLITH BASF: hydrophobicity, enables BLUE MICROLITH increased filler loadings, BLUE 7080T reduces surface tension, POLYESTER BARNET:CHDA912(12) promotes surface wetting, STAPLE improves adhesion to PVC. CBS BAYER: High permanence/low VULKACIT extractability. Low toxicity. CZ Induces no staining or TMT BAYER: discoloration. Low VULCACIT extractability. THIURAM Induces no staining or discoloration. Low DIMORPHOLENE MONSANTO: extractability. SULPHASAN R Esterified wood rosin. Good NBR compatibility. Improves surface wetting and promotes PVC adhesion. Compounds are colour coded for both identification during manufacture and to differentiate from competitor offerings. Improves tensile reinforcement and thermal stability Zinc oxide/stearic acid used commonly to boost cure state in rubber compounds. Long cure indiction/long shelf life, increased vulcanization rate. Improved vulcanized compound physical properties. No free sulphur. Improved vulcanized compound physical properties. Extended pre-cured shelf life FEATURES: Elevated temperature applications. Vulcanizable, chemically bonded to steel via pre-applied, commercially available primer (rubber-to-metal bonding agent). Soft, tacky, conformable, easy to apply. Cures in situ.

Example 3

[0130] A flexible wrapping tape for use in a kit in accordance with the invention was made up to have composition as given in Table 3.

[0131] This flexible wrapping tape is suitable for high temperature applications, i.e. substrate temperatures in excess of 100 C.

TABLE-US-00009 TABLE 3 VULCANISABLE, NITRILE RUBBER/PVC BASED SELF-FUSING COVER PLY AND OUTER WRAP FOR USE AT ELEVATED TEMPERATURE (140 C). PARTS PER HUNDRED OF SUPPLIER & GENERIC RUBBER/ELASTOMER TRADE NAME INGREDIENT PRE- INGREDIENT OF TYPICAL NAME DESCRIPTION RANGE FERRED FUNCTION GRADE COMMENT NBR NBR/PVC 120-140 120 ELASTOMER POLYEUROPA: NBR and PVC are compatible at PRE-BLEND N OZO 70.28 a molecular level and can be PVC PVC RESIN 0-20 5 IMPACT SASOL: PVC blended in any ratio - effectively MODIFIER S7106 forming a cross-linkable PVC. TALC MINERAL 50-150 120 HYDROPHOBIC SCOTIA TALC Improves impact resistance in FILLER DILUENT FILLER physically demanding SILANE THIO SILANE 0.5-2.5 0.7 ADHESION DE GUSSA: environments. PROMOTER/FILLER SILANE Si 69 Reduces cost. Low water COUPLING AGENT adsorption. Low moisture CHDCE CYCLO 30-70 20 POLYMERIC BASF: content. Promotes reduction of CARBOXYLIC PLASTICISER HEXAMOL compound surface tension. ESTER DINCH Promotes filler/elastomer PALE LIQUID 40-80 30 PLASTICIZER/ coupling & labile cross-link LIQUID COUMARONE TACKIFIER formation. Improved high CIR INDENE RESIN temperature flow resistance. BKF SUBSTITUTED 0.5-1.5 1.5 NON-STAINING BAYER: Promotes substrate adhesion PHENOL ANTIOXIDANT VULKANOX High permanence/low ANTIOXIDANT BKF extractability. Effective reduction TMQ SUBSTITUTED 0.5-1.5 1.5 NON-STAINING BAYER: in compound plasticity/surface PHENOL ANTIOXIDANT VULKANOX tension. Good hydrophobicity. ANTIOXIDANT DS Improves effectiveness of GUM ROSIN ROSIN ESTER 25-75 30 TACKIFYING ARIZONA secondary tackifiers, enables RESIN CHEM: increased filler loadings, reduces SYLVALITE surface tension, N550 CARBON BLACK 3.0-5.0 3 UV CORAX: N550 promotes surface wetting, STABILISER improves both self-fusion and ZINC OXIDE 3.0-6.0 4 CURING adhesion to PVC. High ACTIVATOR permanence/low extractability. STEARIC ACID 0.4-1.8 1 CURING Low toxicity. CYCLOHEXYL ACTIVATOR Induces no staining or BENZATHIAZOLE discoloration. Low extractability. CBS SULPHENAMIDE 1.0-2.5 1.5 VULCANIZATION BAYER: Induces no staining or TETRAMETHYL ACCELERATOR VULKACIT discoloration. Low extractability. CZ Esterified wood rosin. Good NBR TMT THIURAM 0.3-1.0 0.7 VULCANIZATION BAYER: compatibility. Improves surface DISULPHIDE ACCELERATOR VULCACIT wetting and promotes self-fusing THIURAM and PVC adhesion. DI- SULPHUR 2.5-4.0 3.0 CURING AGENT MONSANTO: UV stability at elevated MORPHOLENE DONOR SULPHASAN R temperature. Zinc oxide/stearic acid used commonly to boost cure state in rubber compounds. Long cure indiction/long shelf life, increased vulcanization rate. Improved vulcanized compound physical properties. No free sulphur. Improved vulcanized compound physical properties. Extended pre-cured shelf life FEATURES: Elevated temperature applications. Vulcanizable, conformable, easy to apply. Self-fusing (ie not self-adhesive via PSA). Cures in situ.

Example 4

[0132] A CPT comprising an adhesive layer having a composition as defined in Table 1 and a PVC backing layer was wound continuously around an exposed steel pipe section, forming an inner wrap. The CPT was provided with a removable release film, which was removed and discarded prior to wrapping.

[0133] A flexible outer armouring was also provided comprising a self-adhesive PVC film applied helically and under tension, with a 55% overlap, to yield at least a double layer of protection.

[0134] The adhesive properties and impact resistance of the CPT were measured with reference to ISO 21809-3:2016 (Petroleum and natural gas industriesExternal coatings for buried or submerged pipelines used in pipeline transportation systemsPart 3: Field joint coatings). The results are provided in Table 4.

TABLE-US-00010 TABLE 4 Adhesive and impact resistance properties of CPT in accordance with the invention Analytical Analysis CPT in accordance Wrapping with the System Conditions Unit ISO21809-3 invention Thickness: m Innerwrap (1x single straight wrap) Outerwrap (2 55% overlap PVC HD) Innerwrap 900 compound thickness Total 3200 system thickness Peel @23 C. N/mm 0.2 0.45-Pass Strength @70 C. N/mm 0.02 0.07-Pass Layer to Layer Outer to Outer Peel @23 C. N/mm 0.04 0.32-Pass >95% Strength to Substrate Coverage pipe Coverage surface >95% @70 C. N/mm 0.02 0.06-Pass >95% Substrate Coverage Coverage >95% Impact @23 C. J 15 Pass Resistance (MAX 16J)

[0135] The CPT of the present invention provides many advantages over conventional inner wrap constructions of CPTs as hereinbefore described. The advantages include [0136] the use of PVC for both inner wrap backing and outer wrap improves mechanical protection and bagging resistance [0137] self healing after puncturing induced from the PVC inner wrap backing alone, enhanced by the PVC outer wrap [0138] very high adhesive values attainable with polar FME based mastic adhesives to both PVC and steel prevents moisture ingress at any interface [0139] easy release of the aggressive adhesive component from release films [0140] use of high MW FME improves adhesive component green strength and adhesion peel resistance. High MW also provides resilient recoverability after thermal stressing and resistance to flow and creep [0141] availability of Van der Waals and hydrogen bonds provides additional adhesion promotion and allows for minimum surface preparation [0142] use of CSF reinforcement provides flow and creep resistance at elevated temperature. CSF inclusion also eliminates the possibility of delamination, or flow/creep at the adhesive component/reinforcing carrier interface [0143] asymmetric reinforcement due to alignment of CSF allows ease of lateral (and slight longitudinal) stretching to facilitate ease of application.

[0144] The CPT of the invention, as hereinbefore set out, provides good adhesion and surface wetting.

[0145] When a liquid spreads onto a solid surface, an adhesive bond is formed between the substances. The strength of the bond, which is only established when liquid and solid are in very close proximity, is dependent on the mutual compatibility of the components and their relative surface tension. Water droplets form distinct beads on the surface of wax-polished paintwork as a result of the high surface tension in the water and the hydrophobicity of the wax polish. Adding soap to the water droplet lowers the surface tension and allows the droplet to spread over, or wet, the polished surface. The adhesive bond formed between a liquid and wetted surfaces are termed Van der Waal forces and such bonds, which may be relatively strong, form the basis of many adhesive systems.

[0146] The adhesive component of the CPT of the invention is in the form of a very soft, conformable mass, which readily flows into, and wets, the micro fissures of the steel surface. Aggressive adhesion between the adhesive and substrate is vital in order to resist the ingress of moisture at the adhesive component/steel interface. The tenacity with which the adhesive bonds to the substrate is also important, since even after mechanical impact, sufficient adhesive residue must remain adhered to the steel surface to prevent moisture incursion and the possible onset of corrosion. Traditional adhesive components rely solely on the good surface wetting of the substrate and the subsequent Van der Waal bond formation between the adherents. Viewed chemically, the adhesive component must bond to iron oxide, since iron, in steel, is spontaneously oxidised when exposed to the oxygen in the atmosphere. The FME is able to form hydrogen bonds with the polar, oxygenate surface.

[0147] Adhesive bond formation is also crucial to both the backing layer and the tensile reinforcing strands of the CPT. The adhesive body of the CPT of the invention is formulated to provide good adhesion to the other tape components (reinforcing fibres and PVC backing film) and the resultant structure forms a composite with optimized performance.

[0148] The invention thus uses the novel combination of FMEs, CSFs and PVC film as the components of a CPT which, together with its over wrapping, provides a mechanically protective system. Polar FMEs promote surface chemistry induced benefits when used to replace the bitumen, petrolatum or polyisobutylene (PIB) adhesive component of CPTs currently available. Reinforcing of the adhesive component with CSFs and backing with a PVC film, provides a composite structure whose improved physical characteristics overcome many of the limitations of CPTs currently commercially available. The CPT constructions described in this patent are applicable to the requirements of standard EN12068 Class C.

[0149] The construction of the CPT in accordance with the invention uses components which have been specifically designed to have high adhesive strength to both themselves and with the substrate (typically steel) to which the CPT is applied. Such a construction leads to the formation of a composite CPT structure, resulting in improved performance over traditionally applied tapes.

[0150] The foregoing detailed description has been provided by way of explanation and illustration, and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art, and remain within the scope of the appended claims and their equivalents.