WO1992003234A1 - Procede de revetement epoxy/polyolefine - Google Patents

Procede de revetement epoxy/polyolefine Download PDF

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Publication number
WO1992003234A1
WO1992003234A1 PCT/CA1991/000293 CA9100293W WO9203234A1 WO 1992003234 A1 WO1992003234 A1 WO 1992003234A1 CA 9100293 W CA9100293 W CA 9100293W WO 9203234 A1 WO9203234 A1 WO 9203234A1
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WO
WIPO (PCT)
Prior art keywords
coating
pipe
polyolefin
epoxy resin
microns
Prior art date
Application number
PCT/CA1991/000293
Other languages
English (en)
Inventor
James John William Cox
Toni Alois Pfaff
Original Assignee
Du Pont Canada Inc.
Valspar, Inc.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Du Pont Canada Inc., Valspar, Inc. filed Critical Du Pont Canada Inc.
Priority to BR919106771A priority Critical patent/BR9106771A/pt
Priority to AU83330/91A priority patent/AU8333091A/en
Publication of WO1992003234A1 publication Critical patent/WO1992003234A1/fr
Priority to GB9302474A priority patent/GB2262709B/en
Priority to NO930485A priority patent/NO930485D0/no

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/14—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies
    • B05D7/148—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to metal, e.g. car bodies using epoxy-polyolefin systems in mono- or multilayers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
    • F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
    • F16L58/04—Coatings characterised by the materials used
    • F16L58/10—Coatings characterised by the materials used by rubber or plastics
    • F16L58/1054—Coatings characterised by the materials used by rubber or plastics the coating being placed outside the pipe
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2363/00—Characterised by the use of epoxy resins; Derivatives of epoxy resins

Definitions

  • This invention relates to the coating of metal objects, and particularly metal pipes, with three-layer specialized epoxy/polyolefin coating compositions.
  • Epoxy resin coatings have been used extensively for protection of pipe surfaces, and one such composition is shown in Warnken, U.S. Patent 4 009 224. Polyolefin coatings also have been used. Sakayori et al., U.S. Patent Re. 30 006, reissued 1979 May 22, describe the application of a coating of a polyolefin modified by reaction with an unsaturated dicarboxylic organic acid or anhydride to a metal surface bearing a thin, preferably 5-10 micron, primer coating of an uncured epoxy resin to improve adhesion of the polyolefin to the pipe. Japanese Kokai patent SHO 56[1981]-168862 of K.
  • thermosetting fusion bonded epoxy powder or thermosetting two-pack liquid epoxy has been applied in a thickness of 70 ⁇ 20 microns, followed by a terpolymer of ethylene, acrylic ester and maleic anhydride in a thickness of 300-400 microns and then a low or medium density extrusion grade of polyethylene.
  • metal pipe of the type used, for example, in the manufacture of petrochemical pipelines is heated to a temperature of at least about 200 ⁇ C.
  • a powdered epoxy resin composition comprising an epoxy resin having a softening point of at least about 90°C, and a curing agent therefor, is applied to the hot outer surface of the pipe, the resin composition melting and coalescing upon the hot pipe surface to form a coating having a thickness of at least about 200 microns and desirably in the range of from about 300 to about 800 microns; in a preferred embodiment, the epoxy resin composition has a softening point of at least about 95°C.
  • an epoxy resin-reactive polyolefin is applied to the hot outer surface of the epoxy resin;
  • the epoxy-resin reactive polyolefin which is referred to herein as modified polyolefin, is comprised of a polyolefin that has been grafted with an ethylenically unsaturated organic carboxylic acid or anhydride.
  • an unmodified polyolefin is applied over the layer of modified polyolefin.
  • the heat capacity of the metal pipe and the temperature to which it is heated prior to application of the epoxy resin composition desirably are such as to provide enough energy to sequentially (a) melt the powdered epoxy resin and cause it to form a continuous coating upon the pipe surface, (b) melt and coalesce the subsequently applied modified polyolefin upon surface of the incompletely cured epoxy resin, and (c) then substantially cure the layer of epoxy resin; an outer layer of polyolefin is also applied.
  • the three-layer composite coating adheres tenaciously to the metal pipe surface and provides the pipe with not only substantial resistance to cathodic disbondment but also with the ability to withstand substantial physical abuse and relatively high operating temperatures, especially when the polyolefin is polypropylene. Accordingly, the present invention provides a method of coating metallic pipe for use in buried pipelines to provide the pipe with resistance to impact damage and to cathodic disbondment, comprising:
  • modified polyolefin preferably after the epoxy resin composition has gelled upon the pipe surface but in any event before complete curing thereof, applying thereto a modified polyolefin, said modified polyolefin being a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms and which has been grafted with an ethylenically unsaturated organic carboxylic acid or anhydride, the modified polyolefin forming an adherent and protective coating on the epoxy coating and having a thickness in the range of up to 500 microns; and
  • a polyolefin selected from the group consisting of homopolymers or copolymers of hydrocarbon alpha-olefins having 2-10 carbon atoms, especially a polyolefin selected from the group consisting of homopolymers of ethylene, homopolymers of propylene and copolymers of ethylene and C 3 -C 10 hydrocarbon alpha-olefins, said layer of polyolefin having a thickness of at least about 300 microns.
  • the present invention further provides metal pipe suitable for buried pipeline use and bearing an outer composite coating resistant to impact damage and to cathodic disbondment, said coating comprising an inner layer of a cured epoxy resin composition having a thickness of at least about 200 microns, an intermediate coating of a modified polyolefin bonded to the inner layer and having a thickness of up to about 500 microns, and an outer layer in a thickness of at least about 300 microns of a polyolefin that is a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms, especially a polyolefin selected from the group consisting of homopolymers of ethylene, homopolymers of propylene and copolymers of ethylene and C--C 10 hydrocarbon alpha-olefins.
  • the present invention also provides a method of coating metal pipe to be used in the construction of a buried pipeline, comprising
  • a modified polyolefin preferably a powdered modified polyolefin
  • the modified polyolefin forming a polyolefin layer having a thickness of up to about 500 microns, said modified polyolefin being a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms and which has been grafted with an ethylenically unsaturated organic carboxylic acid or anhydride; the axial speed of the pipe through said stations and the distance between the first and second coating stations being adjusted to cause the polyolefin to be applied in the second coating station preferably shortly after gelation of the coating of the epoxy resin composition applied in the first coating station but in any event before complete curing thereof; and
  • a molten layer in a thickness of at least about 300 microns of a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms, especially a polyolefin selected from the group consisting of homopolymers of ethylene, homopolymers of propylene and copolymers of ethylene and C 3 -C 10 hydrocarbon alpha-olefins, to the pipe.
  • Figure 1 is a perspective, schematic view of a portion of a pipeline coating apparatus
  • Figure 2 is a broken-away schematic view in partial cross section of a powder coating station employed in the apparatus of Figure 1.
  • the powdered epoxy resin composition that is employed in the process and pipe of the present invention desirably employs an epoxy resin which is a polyglycidyl ether of a polyhydric phenol having a softening point (Durrans*) of at least about 90°C and preferably from about 90 to about 130 ⁇ C, and a curing agent for the epoxy resin.
  • the preferred polyglycidyl ethers are those obtained from the condensation of bisphenol A (2,2'bis(hydroxyphenyl)propane) and epichlorohydrin.
  • Other polyhydric phenols which provide high melting polyglycidyl ethers include the phenol and o-cresol novolaks.
  • Polyglycidyl ethers of the type described are available commercially e.g. from Dow Chemical Canada Inc. under the trade designation DER 663U, from Ciba-Geigy Canada Ltd. under the trade designation GT 7074 and from Shell Canada Products Ltd. under the trade designation Epon ® 2002, or may be made by extending a lower molecular weight epoxy resin with, for example, bisphenol A.
  • the epoxy resins employed in the present invention are high melting solids and are curable at temperatures in the range of from about 180 to about 250 ⁇ C. Any of the various known latent curing agents may be employed, and among these may be listed amines e.g. dimethylethanolamine and methylene dianiline, amides e.g. dicyandiamide, especially accelerated dicyandiamide, and phenolic resins.
  • the epoxy resin compositions used in the invention may include flow control agents e.g. silicones an example of which is Modaflow ® flow agent powder (Monsanto) , pigments e.g. titanium dioxide, iron oxide and carbon black, fillers e.g. talc, calcium carbonate and mica, and other materials for the same purposes and effect as they are used in epoxy coating powders of the prior art.
  • flow control agents e.g. silicones an example of which is Modaflow ® flow agent powder (Monsanto)
  • pigments e.g. titanium dioxide, iron oxide and carbon black
  • fillers e.g. talc, calcium carbonate and mica
  • Another example is a pipe coating resin from Shell Chemical Company that contains Epon 2004 epoxy resin (78.2 parts), Epon Curing Agent P-104 (3.1 parts), Epon Resin 2002-FC-1O (5 parts, contains 10% by weight of Modaflow flow control agent), red iron oxide (1.5 parts), barium sulphate (11.7 parts) and Cab-O-Sil ® M-5 silica (0.5 parts) .
  • the powdered epoxy resin coating compositions may be manufactured by various methods known to the prior art; in a preferred embodiment, the coating compositions may be manufactured using a process in which the ingredients are melt blended, cooled and ground into a powder.
  • Epoxy resin coating compositions of the type described are available commercially, examples of such resins being sold by Valspar, Inc. under the designations D-1003LD and D-1003EG.
  • the epoxy resin compositions of the invention exhibit gel times of from about 2 to about 20 seconds (and preferably from about 5 to about 10 seconds) at pipe coating temperatures of about 250"C.
  • gel time is defined as the time required for an epoxy resin composition to gel i.e.
  • Gel time is measured by placing the epoxy resin composition on a hot metal surface, especially a hot plate, that is at the predetermined temperature. Using a spatula or other suitable device, a portion of the epoxy resin composition is drawn over the heated surface, to provide a sample having a thickness of approximately 200 microns. A sharp edged object e.g. paper clip, is then moved through the now molten layer of epoxy resin composition until a rapid increase in the melt viscosity of the composition is observed. The time, expressed in seconds, between when the epoxy resin composition is placed in the hot surface and the rapid rise in melt viscosity is the gel time.
  • Degree of cure may be measured by differential scanning calorimetry (DSC) using the procedure of the Canadian Standards Association (CSA) for fusion bonded epoxy resins para. 12.2 (page 28).
  • DSC differential scanning calorimetry
  • CSA Canadian Standards Association
  • the aforementioned epoxy resin composition 1003LD exhibits curing times of 50 seconds at 243"C, 60 seconds at 235 ⁇ C and 70 seconds at 232°C.
  • the modified polyolefins employed in the invention are grafted homopolymers and copolymers of hydrocarbon alpha-olefins having 2-10 carbon atoms.
  • the polymers may be homopolymers or copolymers of ethylene, propylene, butene-1, 4-methyl pentene-1, hexene-1 and octene-1.
  • the preferred polymers are homopolymers and copolymers of ethylene and propylene.
  • the polymers of ethylene may include hompolymers of ethylene and copolymers of ethylene with, for example, butene-1, hexene-1 and/or octene-1.
  • the polymers of propylene may include homopolymers of propylene and copolymers of propylene and ethylene, including so-called random and impact grades of polypropylene.
  • 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; both procedures of applying the polyolefin are discussed herein.
  • the polymer is modified by grafting with at least one alpha,beta-ethylenically unsaturated carboxylic acid or anhydride, including derivatives of such acids and anhydrides.
  • acids and anhydrides which may be mono-, di- or polycarboxylic acids, are acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, itaconic anhydride, nadic anhydride, maleic anhydride and substituted maleic anhydride e.g. dimethyl maleic anhydride.
  • derivatives of the unsaturated acids are salts, amides, imides and esters e.g. mono- and disodium maleate, acrylamide, maleimide and dimethyl fumarate.
  • the amount of grafted monomer is usually in the range of 0.01 to 5% by weight of the polymer; in preferred embodiments, the amount of grafted monomer is in the range of 0.1 to 2% by weight of polymer.
  • the characteristics of the polymer subjected to the grafting reaction will depend on the characteristics required in the grafted polymer that is to be coated over the epoxy resin composition, it being understood that some polymers, especially polypropylene, tend to undergo scission reactions in the presence of organic peroxides i.e. in the grafting process.
  • Additional polymers and/or stabilizing agents e.g. antioxidants for example phenolic antioxidants, UV stabilizers and heat stabilizers, pigments e.g. titanium dioxide and carbon black, extenders e.g.
  • mica and glass may be added to the polymer either subsequent to the grafting process but prior to extrusion or other recovery of the grafted polymer from the apparatus used in the grafting process or in subsequent steps.
  • ungrafted polymer that is identical to or different from the polymer that has been grafted may be added to the grafted polymer.
  • Toughening agents e.g. elastomers and very low density polyethylenes e.g. with densities below about 0.910 g/cm 3 , may be added but such agents must be thoroughly dispersed in the polymer matrix.
  • Other materials e.g.
  • the polyolefin applied as the outer coating is a homopolymer or copolymer of hydrocarbon alpha-olefins having 2-10 carbon atoms, especially a polyolefin selected from the group consisting of homopolymers of ethylene, homopolymers of propylene and copolymers of ethylene and C 3 -C 10 hydrocarbon alpha-olefins ; the hydrocarbon alpha-olefins may be branched or unbranched alpha-olefins.
  • the polyolefin may be a homopolymer of ethylene of, in particular, low or medium density.
  • the polyolefin may be copolymer of ethylene and a hydrocarbon alpha-olefin, especially butene-1, hexene-1 and/or octene-1 having a low or medium density.
  • the polymer may be a polymer of propylene e.g. a homopolymer of propylene or especially a copolymer of propylene and a minor amount of ethylene.
  • a preferred coating procedure of the invention involves the use of two powder spray stations spaced along the path of travel of a preheated section of metal pipe, the first station being employed to spray the powdered epoxy resin composition upon the pipe surface and the second station being employed to spray the powdered, modified polyolefin upon the incompletely cured epoxy resin surface.
  • Techniques and apparatus for spraying powdered coating materials upon hot pipe surfaces are known in the art, and are described, for example, in J. Protective Coatings and Linings, May 1988, Vol. 5, No. 5 p 26, by S.E. McConkey.
  • the powdered epoxy resin composition is entrained in an air stream and is directed by means of nozzles or jets against the hot pipe surface.
  • a series of nozzles may be provided within a coating station through which lengths of preheated pipe are caused to pass.
  • the nozzles may be positioned circumferentially of the pipe and spaced so as to provide a uniform coating of epoxy resin upon the pipe, or preferably are positioned on one side of the pipe with the coating composition being sprayed onto the pipe surface as the pipe, which is being rotated, passes axially through the coating station.
  • a second, similar coating station is provided adjacent the first coating station, the second station being adapted to spray onto the epoxy-coated pipe the powdered, modified polyolefin employed in the instant invention.
  • the coating of the powdered epoxy resin or the powdered, modified polyolefin or both may be aided through the use of electrostatic coating procedures in which the powdered material is provided with an electric charge.
  • the coating stations as thus described may be partially enclosed within appropriate housings to avoid the escape of resin particles and/or contamination of the epoxy resin powder or modified polyolefin powder by the other.
  • the modified polyolefin may also be applied in the form of molten polymer e.g. using extrusion coating techniques.
  • the modified polyolefin may be applied by use of an annular die through which the pipe is passed or by side extrusion in which molten polymer in the form of a tape or film is extruded onto rotating pipe.
  • a third coating station is used for the coating of the outer layer of polyolefin onto the pipe using extrusion techniques.
  • the polyolefin may be applied by use of an annular die through which the pipe is passed or by side extrusion in which molten polymer in the form of a tape or film is extruded onto rotating pipe.
  • a length of pipe to be coated passes axially and with optional rotation along a predetermined path sequentially through the coating stations.
  • the pipe Before entering the first (epoxy resin composition) coating station, the pipe passes through a heating station where it is heated to an appropriate coating temperature in the range of from about 200 to about 250°C; this may be appropriately accomplished by means of induction heating, infrared heating or gas fired ovens.
  • the hot pipe passes through the coating stations, which are aligned with the heating station and with each other, it receives sequential coatings of the epoxy resin composition, the modified polyolefin and the outer coating of polyolefin.
  • the epoxy resin powder has a particle size of up to about 250 microns, especially in the range of about 10 to about 150 microns.
  • the modified polyolefin powder has a particle size of up to about 350 microns, especially in the range of about 75 to about 175 microns.
  • the epoxy resin powder has a melting point in the range of about 90 to 130"C, especially in the range of about 95 to 125"C.
  • the modified polyolefin powder has a melting point in the range of about 105 to 175"C, especially in the range of about 120 to 165°C.
  • the coating of epoxy resin has a thickness of at least about 200 microns, preferably a thickness in the range of about 300 to 800 microns, especially in the range of about 350 to 600 microns.
  • the modified polyolefin has a coating thickness of up to about 500 microns, for example 50 to 500 microns, especially 100 to 400 microns, preferably a thickness in the range of about 100 to 250 microns.
  • the polyolefin has a thickness of at least about 300 microns e.g. 300 to 7000 microns, preferably in the range of about 400 to 1500 microns.
  • the modified polyolefin be applied to the epoxy resin-coated surface of the pipe before the epoxy resin composition has substantially cured; preferably, the polyolefin powder is applied immediately, i.e. within about 5 to about 60 seconds, after application of the epoxy resin composition, and desirably within about 15 seconds following application to the pipe of the epoxy resin composition.
  • This careful timing feature may be controlled, among other things, by controlling the temperature and thermal mass of the pipe, the speed at which the pipe moves through the coating stations and the spacing between the coating stations.
  • Figure 1 schematically shows a portion of a pipe coating apparatus of the type employed in the present invention. It will be understood that the entire pipe coating process employs various treatment stations both upstream and downstream from the apparatus shown in Figure 1.
  • stock lengths of pipe may be subjected to preheating, abrasive cleaning as by sandblasting and the like, sanding and grinding, and other surface conditioning operations before passing to the apparatus shown in Figure 1.
  • a section of pipe is shown at 12 in Figure 1 and is conveyed along an axial path of travel shown by the arrow 14 by means of conveyor rollers 16.
  • the latter may be positioned at an angle to the axis of the pipe so as to impart an axial rotation to the pipe, as shown by the arrow 10.
  • the section of pipe enters a heating station 18 in which the pipe is heated by various means such as passage through a gas fired oven and is thus heated to a temperature in the range of about 200-250 ⁇ C.
  • the pipe then passes directly to an epoxy powder coating station 20.
  • This station comprising a chamber having pipe entrance and exit ports and within which an epoxy powder of the type described above is sprayed upon the hot pipe surface.
  • FIG. 2 A schematic view of the chamber is shown in Figure 2, the chamber including a supply ring 22 about the pipe 12, the supply ring having a series of radially inwardly oriented spray nozzles 24 adjacent one side of the pipe to direct epoxy powder against the surface of the rotating pipe.
  • Supply and exhaust tubes 26, 28 are provided to supply air-entrained epoxy resin composition powder to and to exhaust air from the chamber.
  • the interior of the chamber becomes filled with a cloud of epoxy resin particles.
  • the pipe passes to a polyolefin coating station 30 which is exemplified as a powder coating station and may be substantially identical to the epoxy powder coating station 20.
  • a polyolefin coating station 30 which is exemplified as a powder coating station and may be substantially identical to the epoxy powder coating station 20.
  • air-entrained modified polyolefin powder is brought into contact with the hot surface of the epoxy-coated pipe and coalesces upon that surface to the desired thickness.
  • the pipe exits the polyolefin powder coating station 30, and curing of the epoxy resin coating layer continues as the pipe passes downstream in the direction of the arrow 14.
  • an additional heating station 32 may be provided downstream from the modified polyolefin powder coating station, the station 32 typically employing infrared heating means to further heat and thus flow out the modified polyolefin layer.
  • the pipe section then enters the third coating station 40 in which the outer coating of polyolefin is applied, normally using extrusion techniques.
  • the pipe section 12 is then quenched
  • a typical speed of travel of the pipe section 12 along the path 14 may average about 24 feet (about 7.3 metres) per minute. If the polyolefin powder is to be applied to the epoxy-coated pipe within about 15 seconds following application of the epoxy resin composition, then the distance "d" between the epoxy powder and polyolefin powder stations must be approximately 6 feet (about 1.8 metres) . As noted above, it is preferable that the polyolefin powder be applied before substantial curing of the epoxy resin coating, but desirably after gelation. In practice, this can be accomplished by varying the temperature to which the pipe is heated, the linear speed with which the pipe passes through the coating stations, and the distance "d" between the epoxy and the polyolefin coating stations. Commonly, adjustments are made to the axial speed of the pipe or to the distance "d" between the coating stations 20, 30, which may be made movable along the axial path of travel 14 of the pipe so that the distance between them may be varied.
  • the thicknesses of the epoxy resin and the polyolefin coating will depend upon the flow rates of the respective powders to the pipe surface and the speed of the pipe through the coating stations.
  • the flow rates of powdered epoxy and powdered modified polyolefin and the extrusion rate of the polyolefin for the outer coating may be adjusted as desired, as may the linear speed of pipe passing through the coating stations, the pipe speed, however, remaining strictly subject to the requirement that the polyolefin powder be applied to the epoxy resin composition layer before it has substantially cured but desirably after it has gelled.
  • An example of a typical pipe coating operation under the present invention may employ steel pipe having an outer diameter of about 12 inches (about 30.5 cm) and a wall thickness of 0.312 inches (0.78 cm).
  • the pipe may be rotated and provided with an axial speed of about 24 feet (about 7.3 metres) per minute.
  • the heating station 18 which may be a gas fired oven, the pipe may be heated to a temperature of 240°C.
  • the pipe then immediately enters the epoxy powder coating station 20, epoxy powder being uniformly applied by means of a spray to the pipe surface and coalescing to form a wet film.
  • the epoxy resin composition applied may be that sold commercially by Valspar, Inc. under the designation D-1003LD, this powdered resin composition having gel time at 240°C of about 4-8 seconds.
  • the distance “d” separating the epoxy and polyolefin coating stations may be approximately 4 feet (1.2 metres), this distance providing approximately 10 seconds between the epoxy and the polyolefin coating steps.
  • the polyolefin is applied to the epoxy resin coating approximately 2-6 seconds after the latter has gelled but well before curing has been completed.
  • the modified polyolefin powder is applied to the epoxy resin-coated pipe at a rate sufficient to coat the epoxy to the required thickness.
  • the modified polyolefin so applied may be Fusabond PMD 139 GBK or EMB 158, both manufactured by Du Pont Canada Inc.
  • the length of pipe 12 is supported a sufficient distance downstream from the modified polyolefin coating station so that the modified polyolefin powder coating has coalesced into a wet film and has cooled to a solid before contacting downstream supporting rollers.
  • the polyolefin applied as the outer coating may be an ethylene/butene-1 copolymer e.g. Sclair ® 35B polyolefin, manufactured by Du Pont Canada Inc. It is preferred that the polyolefin from which the modified polyolefin has been manufactured and the polyolefin of the outer coating be similar types of polymers e.g. both polypropylene or both polyethylene, which tends to result in improved compatibility and hence improved bond strength between the layer of modified polyolefin and the outer layer of polyolefin.
  • the resulting composite coating on the pipe is tightly adherent to the metal pipe surface and, because of the modified polyolefin intermediate coating and the polyolefin outer coating, is highly resistant to impact damage or damage from rough handling. It has been found to be substantially impossible to physically separate the modified polyolefin coating layer from the epoxy layer at ambient temperature, the two layers being intimately bonded together. Similarly, the layers of modified polyolefin and polyolefin cannot be readily separated.
  • the thick epoxy resin coating layer provides the pipe with substantial resistance to cathodic disbondment and, together with the overlying polyolefin layers, serves to physically protect the pipe from damage of the type encountered in a pipeline laying operation.
  • the coating is considerd to be an integral structure rather than a mere assemblage of layers.
  • the modified polyolefin By being placed in contact with the coalesced epoxy resin layer before the latter has completely cured, .the modified polyolefin (through its carboxyl or anhydride groups) reacts with and chemically bonds to the epoxy resin to provide an extremely adherent bond between these layers.
  • the interface between the epoxy resin and the modified polyolefin is slightly diffuse, and attempts to separate these layers one from another along their interface has resulted in disruption of one layer or the other without evidence of interface separation.
  • the confronting surfaces of the modified polyolefin layer and the polyolefin outer layer are at least to some extent melt blended together during the application of the outer layer, and the bond between these layers is thus somewhat diffuse and may be extremely strong. Attempts to separate these layers along their interface have similarly resulted in disruption of the layers themselves, without interface separation.
  • the composite coating of the invention may be thought of as a sandwich structure in which the parts of the sandwich are intimately and inseparably joined in a cooperative manner.
  • the epoxy resin layer bonds tenaciously to the metal surface to which it is applied.
  • the intermediate modified polyolefin layer chemically bonds to the epoxy layer, and the polyolefin outer layer is melt blended at its interface into the outer surface of the modified polyolefin layer.
  • the epoxy resin layer serves functionally to physically cover and protect the underlying metal surface, to adherently bond the composite coating to the metal layer, and to effectively and efficiently resist cathodic disbondment.
  • the intermediate modified polyolefin layer serves to tenaciously adhere the epoxy resin layer to the outer polyolefin layer, and the intermediate layer should be of sufficient thickness e.g. at least 50 microns, to achieve this purpose.
  • the intermediate layer may also in itself provide sufficient physical protection to the underlying epoxy resin layer.
  • the outer polyolefin layer commonly will be the thickest layer, and serves to encapsulate and protect the layers beneath it and, accordingly, to protect the underlying metal surface. The composite coating therefore does not have three separate and distinct layers, even though the layers are applied separately.
  • the composite coating that is formed functions as an integral coating having an inner portion (the epoxy resin) that is tenaciously bonded to the underlying metal surface and provides protection against cathodic disbondment, and an outer portion (formed from the intermediate modified polyolefin and the outer polyolefin layers) which is generally hydrophobic and waterproof and which exhibits sufficient flexibility as to enable it to absorb the physical abuse commonly encountered in pipe laying procedures while continuing to protect the underlying epoxy portion and the metal surface itself.
  • Metal pipe commonly used in petroleum pipeline applications may have a wall thickness in the range of about 2-25 mm and an outer diameter in the range of about 2.5-150 cm; for example, when heated to coating temperatures in the range of about 240°C, such pipe has sufficient thermal mass i.e. it has absorbed sufficient heat energy, so that its surface temperature falls quite slowly. Unless quenched, the temperature of such a typical section of pipe heated to 240°C and then coated in accordance with the invention falls to 220°C only after about 1-3 minutes. Thus, the more critical parameters involve the speed of the pipe through the coating stations and the space between the stations.
  • the present invention is particularly intended for the coating of pipe intended for use in petroleum applications. However, the coated pipe may have uses in other applications in which protection against cathodic disbondment is important.

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  • Laminated Bodies (AREA)

Abstract

L'invention décrit un procédé de revêtement de conduite métallique. Le procédé comprend le réchauffement de la conduite à une température d'au moins 200 °C et l'application d'une composition de résine époxy, dont l'épaisseur est d'au moins 300 microns, à la surface extérieure de la conduite réchauffée. Avant le durcissement complet de la composition de résine époxy mais, de préférence, après sa gélification, on applique un revêtement d'une polyoléfine modifiée, d'une épaisseur de 500 microns maximum. La polyoléfine modifiée est un homopolymère ou copolymère d'alpha-oléfines d'hydrocarbure comportant de 2 à 10 atomes de carbone, qui a été modifiée par greffe avec un acide ou un anhydride carboxylique organique éthyléniquement insaturé. On applique ensuite un revêtement extérieur d'une polyoléfine d'une épaisseur de 300 microns au moins, la polyoléfine étant un homopolymère ou un copolymère d'alpha-oléfines d'hydrocarbure comportant de 2 à 10 atomes de carbone et, de préférence, un homopolymère d'éthylène ou de propylène ou un copolymère d'éthylène et d'une alpha-oléfine d'hydrocarbure C3-C10. Le revêtement obtenu est résistant aux chocs et à la désagrégation cathodique. On peut utiliser le tuyau recouvert par le revêtement pour les pipelines souterrains de l'industrie pétrolière.
PCT/CA1991/000293 1990-08-20 1991-08-16 Procede de revetement epoxy/polyolefine WO1992003234A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BR919106771A BR9106771A (pt) 1990-08-20 1991-08-16 Processo de revestimento com epoxi/poliolefinas
AU83330/91A AU8333091A (en) 1990-08-20 1991-08-16 Epoxy/polyolefin coating process
GB9302474A GB2262709B (en) 1990-08-20 1993-02-09 Epoxy/polyolefin coating process
NO930485A NO930485D0 (no) 1990-08-20 1993-02-11 Fremgangsmaate ved belegging av metallroer med epoksy/polyolefin

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB909018236A GB9018236D0 (en) 1990-08-20 1990-08-20 Epoxy/polyolefin coating process
GB90.18236 1990-08-20

Publications (1)

Publication Number Publication Date
WO1992003234A1 true WO1992003234A1 (fr) 1992-03-05

Family

ID=10680937

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA1991/000293 WO1992003234A1 (fr) 1990-08-20 1991-08-16 Procede de revetement epoxy/polyolefine

Country Status (4)

Country Link
BR (1) BR9106771A (fr)
CA (1) CA2089766C (fr)
GB (2) GB9018236D0 (fr)
WO (1) WO1992003234A1 (fr)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994022598A1 (fr) * 1993-03-31 1994-10-13 Basf Lacke + Farben Ag Agent de revetement a trois couches pour tubes metalliques et procede permettant de recouvrir en trois couches l'exterieur de tubes metalliques
FR2723006A1 (fr) * 1994-07-28 1996-02-02 Gts Isopipe Sa Procede pour realiser un revetement de protection sur un tube et, notamment, sur un tube de pipeline dispositif et installation pour sa mise en oeuvre
FR2743330A1 (fr) * 1996-01-10 1997-07-11 Atochem Elf Sa Revetement de surfaces metalliques
JP2004130669A (ja) * 2002-10-10 2004-04-30 Dai Ichi High Frequency Co Ltd 複層被覆金属曲管の製造方法
JP2004155003A (ja) * 2002-11-05 2004-06-03 Dai Ichi High Frequency Co Ltd 防食被覆形成用複層被覆資材および防食被覆形成方法
WO2007062871A1 (fr) 2005-12-03 2007-06-07 Skumtech As Protection anticorrosion pour des éléments d’ancrage dans la roche
US8038829B2 (en) 2006-02-22 2011-10-18 Shawcor Ltd. Coating method for pipe having weld bead
US20140034216A1 (en) * 2011-01-20 2014-02-06 Saipem S.P.A. Pipe-Joining Method for Building Hydrocarbon Pipelines, in Particular, Underwater Pipelines
DE102014102621A1 (de) * 2014-02-27 2015-08-27 Doege Beteiligungs Gmbh Grossrohranordnung und Verfahren zur Herstellung einer solchen
WO2015191280A2 (fr) 2014-06-12 2015-12-17 Dow Global Technologies Llc Revêtements pulvérulents
US10082236B2 (en) 2015-05-22 2018-09-25 Solvay Specialty Polymers Italy S.P.A. Multilayer assembly
CN115715236A (zh) * 2020-07-07 2023-02-24 第一高周波工业株式会社 三层被覆金属管的制造方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2632802A1 (fr) * 2008-05-30 2009-11-30 Shawcor Ltd. Preparations protectrices et/ou decoratives, et procedes de realisation

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0366168A1 (fr) * 1988-10-03 1990-05-02 Dow Benelux N.V. Procédé pour revêtir des tubes aux champs

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0366168A1 (fr) * 1988-10-03 1990-05-02 Dow Benelux N.V. Procédé pour revêtir des tubes aux champs

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1994022598A1 (fr) * 1993-03-31 1994-10-13 Basf Lacke + Farben Ag Agent de revetement a trois couches pour tubes metalliques et procede permettant de recouvrir en trois couches l'exterieur de tubes metalliques
US6174569B1 (en) 1993-03-31 2001-01-16 Basf Coatings Ag Three-layer metal pipe coating compositions and process for the exterior coating or metal pipes by a three-layer method
FR2723006A1 (fr) * 1994-07-28 1996-02-02 Gts Isopipe Sa Procede pour realiser un revetement de protection sur un tube et, notamment, sur un tube de pipeline dispositif et installation pour sa mise en oeuvre
WO1996003222A1 (fr) * 1994-07-28 1996-02-08 Isotub Coating Procede, dispositif et installation pour revetir un tube notamment un tube de pipeline
FR2743330A1 (fr) * 1996-01-10 1997-07-11 Atochem Elf Sa Revetement de surfaces metalliques
WO1997025202A1 (fr) * 1996-01-10 1997-07-17 Elf Atochem S.A. Revetement de surfaces metalliques
JP2004130669A (ja) * 2002-10-10 2004-04-30 Dai Ichi High Frequency Co Ltd 複層被覆金属曲管の製造方法
JP2004155003A (ja) * 2002-11-05 2004-06-03 Dai Ichi High Frequency Co Ltd 防食被覆形成用複層被覆資材および防食被覆形成方法
WO2007062871A1 (fr) 2005-12-03 2007-06-07 Skumtech As Protection anticorrosion pour des éléments d’ancrage dans la roche
US8038829B2 (en) 2006-02-22 2011-10-18 Shawcor Ltd. Coating method for pipe having weld bead
US20140034216A1 (en) * 2011-01-20 2014-02-06 Saipem S.P.A. Pipe-Joining Method for Building Hydrocarbon Pipelines, in Particular, Underwater Pipelines
US10527206B2 (en) * 2011-01-20 2020-01-07 Saipem S.P.A. Pipe-joining method for building hydrocarbon pipelines, in particular, underwater pipelines
DE102014102621A1 (de) * 2014-02-27 2015-08-27 Doege Beteiligungs Gmbh Grossrohranordnung und Verfahren zur Herstellung einer solchen
WO2015191280A2 (fr) 2014-06-12 2015-12-17 Dow Global Technologies Llc Revêtements pulvérulents
US10082236B2 (en) 2015-05-22 2018-09-25 Solvay Specialty Polymers Italy S.P.A. Multilayer assembly
CN115715236A (zh) * 2020-07-07 2023-02-24 第一高周波工业株式会社 三层被覆金属管的制造方法
CN115715236B (zh) * 2020-07-07 2024-04-30 第一高周波工业株式会社 三层被覆金属管的制造方法

Also Published As

Publication number Publication date
GB9302474D0 (en) 1993-04-21
BR9106771A (pt) 1993-06-29
GB9018236D0 (en) 1990-10-03
CA2089766C (fr) 1999-03-30
GB2262709B (en) 1994-03-02
CA2089766A1 (fr) 1992-02-21
GB2262709A (en) 1993-06-30

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