Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/04—Interconnection of layers
  • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/04—Polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2323/00—Polyalkenes
  • B32B2323/10—Polypropylene

Definitions

• the present invention relates to a coating of metal surfaces and more particularly of tubes whose external surface is coated with a thermoplastic polymer. This technique is used for example to protect against corrosion buried or submerged pipe lines.
• the tubes are heated to between 130 and 200 ° C., then polyethylene powder is sprayed, by melting, a continuous coating of polyethylene is obtained.
• the surface thus heated can also be coated with a first layer of grafted polyolefin and then an outer layer of polyethylene
• WO 92/03234 describes a process in which the tube is heated to at least 200 ° C., then 200 ⁇ m of epoxy resin is deposited there, before the end of the crosslinking, a 500 ⁇ m layer of a copolymer of the ethylene grafted with maleic anhydride and finally a layer of at least 300 ⁇ m of polyethylene is deposited
• the present invention relates to the coating of metal surfaces which cannot be heated either because they already have a coating on the other face, for example polyethylene, or because the surface metal cannot be heated, such as, for example, cast iron, or because that the metal and the coating on the other side do not withstand heating.
• metal surfaces which cannot be heated either because they already have a coating on the other face, for example polyethylene, or because the surface metal cannot be heated, such as, for example, cast iron, or because that the metal and the coating on the other side do not withstand heating.
• steel pipes whose interior is painted or is coated with polyethylene, or cast iron pipes or even cast iron pipes or steel with internal cement coating These surfaces can hardly be heated above 60 ° C
• the Applicant has discovered that by using an adhesive having a VICAT point lower or at most substantially equal to the possible heating temperature of the metal surface, it was possible to obtain coatings with a peeling force of up to 300 or 400 N / 5 cm at 23 ° C If the VICAT point is higher than this temperature, then the peeling force is very insufficient and the coating is not acceptable
• the present invention relates to a metal surface coated with a thermoplastic polymer comprising at least one adhesive placed between the metal surface and the thermoplastic polymer, the said adhesive having a VICAT point lower than or at most substantially equal to the possible heating temperature of the metal surface.
• the invention also relates to a method for coating these surfaces.
• the invention relates to surfaces which cannot be heated to the temperatures usually used for these steel surfaces of the prior art, that is to say beyond 100 ° C. and up to 200 ° C. It is by example cast iron or cast iron coated on one of its faces with a product which does not withstand high temperatures such as polyethylene or cement.
• the invention can therefore relate to the coating on one or both sides of the metal surface, depending on whether the other face is already coated or whether it is desired to coat only one of the faces.
• the invention is particularly useful for the external surface of pipes, these pipes being able to have an outside diameter for example up to 0.8 or 1.5 m and a thickness of 2 to 25 mm.
• the possible heating temperature means temperatures of the order of 50 to 100 ° C and most often 55 to 70 ° C.
• thermoplastic polymer By way of example of a thermoplastic polymer, mention may be made of polyolefins, polyamides, mixtures of polyamide and polyolefins, these polymers possibly being filled with glass fibers.
• the service temperature of the coated surfaces of the invention is low and is also of the order of 50 to 100 ° C. It is therefore not necessary to use polyamides.
• Polyolefins are advantageously used. By way of example of polyolefins, there may be mentioned
• - Polyethylene polypropylene, copolymers of ethylene or propylene with at least one alpha olefin. These include LDPE, LLDPE, VLDPE and HDPE, among others. - copolymers of ethylene with at least one monomer chosen from esters of i ⁇ saturated carboxylic acids, carboxylic acids wholly or partly neutralized by metals or alkalis such as zinc or lithium, or vinyl esters of saturated carboxylic acids.
• thermoplastic polymer can be loaded with glass fibers, talc, clays, alumina, silica. It can also contain antioxidants, etc.
• the adhesive is any product allowing the thermoplastic to bond to the metal surface and having a VICAT point lower than or at most substantially equal to the possible heating temperature of the metal surface.
• the VICAT point is therefore at most 50 or 100 ° C and most often 55 to 70 ° C at most.
• the adhesive has a VICAT point of at most 60 or 65 ° C, advantageously less than 55 ° C and preferably between 20 and 50 ° C.
• the adhesive can be a polymer functionalized by grafting or copolymerization with a monomer chosen from
• the adhesive can be a polymer in a formulation of the hot melt type.
• Hot melts or hot melt glues are mixtures of a basic polymer (which constitutes the core of the hot melt) with a tackifying resin, waxes, stabilizers and possibly fillers. It is enough to choose among these products those having the suitable VICAT point.
• These adhesives can have a melt flow index (MFI) of 0.5 to 1000 (g / 10 min at 190 ° C under 2.16 kg).
• the Applicant has also discovered that if the MFi is greater than 10 and preferably between 15 and 100, then the application of the adhesive is easier, the layer is homogeneous, a good peel strength is more certainly obtained.
• the MFi is too low, for example between 0.5 and 10, care must be taken to distribute the adhesive over the entire surface.
• the adhesive is a copolymer:
• esters of unsaturated carboxylic acids such as, for example, alkyl (meth) acrylates
• vinyl esters of saturated carboxylic acids such as, for example, vinyl acetate or propionate
• alpha olefins such as for example butene-1.
• the functional monomer can be an unsaturated carboxylic acid, an anhydride and also the derivatives of these acids and anhydrides.
• carboxylic acids mention may be made of methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, itaconic anhydride, nadic anhydride, maleic anhydride and substituted maleic anhydrides such as for example dimethyl maleic anhydride.
• derivatives examples include salts, amides, imides and esters such as sodium mono and dimaleate, acrylamide, maleimide and dimethyl fumarate.
• the functional monomer can also be an unsaturated epoxide such as, for example, glycidyl (meth) acrylate, allylglycidyl ether, vmylglycidylether, glycidyl itaconate or glycidyl maleate.
• adhesives there may be mentioned: - polyethylene, polypropylene, ethylene propylene copolymers, ethylene-butene copolymers, all these etanl products grafted with maleic anhydride or glycidyl methacrylate.
• the alkyl (meth) acrylates can be, for example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethyl hexyl acrylate , cyclohexyl acrylate, ⁇ e methyl methacrylate or ethyl methacrylate.
• the adhesive is an ethylene / (meth) acrylate / maleic anhydride copolymer.
• the amount of alkyl (meth) acrylate can be up to 45% by weight of the copolymer and usually from 5 to 40%.
• Maleic anhydride is present in amounts up to 10% by weight and most often 0.2 to 5%.
• the alkyl (meth) acrylate is preferably methyl, ethyl or n-butyl acrylate.
• the adhesive can include mineral fillers such as talc, CaCo 3, etc.
• the amount of mineral fillers can be up to 10% of the amount of adhesive.
• the metal surface coated according to the invention also comprises between the metal surface and the adhesive at least one epoxy resin.
• the coated surface successively comprises the metal surface, at least one layer of epoxy resin, at least one layer of adhesive and at least one layer of thermoplastic polymer.
• epoxy resins The principle of epoxy resins is described for example in KIRK-OTHMER Encyclopedia of Chemical Technology Vol. 9 - pages 257-289 3rd edition. These resins are most often polyglycidyl ether of a polyphenol. For example: - the condensation products of bisphenol A and epichlorohydrin;
• triazine derivatives such as triglycidyl isocyanurate - resins derived from hydantoin.
• the resins used in the present invention are preferably two-component systems which can be crosslinked at room temperature.
• These resins can comprise additives such as silicone, pigments such as titanium dioxide, iron oxides, carbon black, fillers such as calcium carbonate, talc or mica.
• the gel time is advantageously between 20 and 30 minutes.
• the freezing time is defined by standard AFNOR NFA 49-706. It is the time necessary to cause a rapid increase in viscosity at a determined temperature.
• the catalyst is added thereto (to crosslink).
• the thickness of the optional layer of epoxy resin can be between 20 and 400 ⁇ m and preferably between 50 and 150 ⁇ m.
• the thickness of the adhesive layer can be between 100 and 500 ⁇ m and preferably between 200 and 350 ⁇ m.
• the thickness of the layer of thermoplastic polymer can be between 0.5 and 5 mm and preferably 1, 5 and 3 mm.
• the present invention also relates to a method of manufacturing these coated surfaces.
• the metal surface can first be degreased and / or shot blasted or sanded. Any epoxy resin is deposited in liquid form on the metal surface After about 20 to 30 minutes, that is to say, at the end of the freezing time, the tube is heated and then the adhesive is deposited by coating or laminating. Then, the thermoplastic polymer is deposited in the same way.
• the same procedure is followed for the epoxy resin, then the adhesive is extruded in an annular die arranged concentrically around the tube. It can also be extruded in a flat die producing a continuous ribbon which is wrapped around the tube for example by the rotation of the tube on itself.
• the thermoplastic is deposited in the same way.
• LDPE 1 denotes a low density polyethylene of MFI 0.2 loaded with carbon black (1 002 CJ black from ELF ATOCHEM).
• Adhesives have the following properties
• OREVAC 1 denotes an E / VA / GMA copolymer containing 6% GMA (VA denotes vinyl acetate and GMA glycidyl methacrylate)
• LOTADER 1 denotes an ethylene / ethyl acrylate / maleic anhydride copolymer containing 17% by weight of acrylate and 3% by weight of MAH.
• LOTADER 2 denotes an ethylene / ethyl acrylate / maleic anhydride copolymer containing 9% by weight of acrylate and 3% by weight of MAH,
• the non-shot tube is heated to 60 ° C.
• the adhesive is deposited on the tube by extrusion at 230 ° C (temperature of the melt) and then covered by LDPE 1 by extrusion at 220 ° C. (temperature of the melt).
• the tube is then cooled with water for 3 min.
• A is a mixture of 4, glycidyloxy-N N-digiycidylaniline and bisphenol A B is a cycloaliphatic amine
• the adhesion is measured - 400 N / 5 cm at 23 ° C 75 N / 5 cm at 50 ° C

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Laminated Bodies (AREA)
• Adhesives Or Adhesive Processes (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Rigid Pipes And Flexible Pipes (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9488021

Family Applications (1)

Country Status (11)

Families Citing this family (4)

Citations (6)

• 1996
  • 1996-01-10 FR FR9600231A patent/FR2743330A1/fr active Pending
  • 1996-12-30 CN CN96193742A patent/CN1183744A/zh active Pending
  • 1996-12-30 KR KR1019970706297A patent/KR19980702889A/ko not_active Application Discontinuation
  • 1996-12-30 BR BR9607824A patent/BR9607824A/pt not_active Application Discontinuation
  • 1996-12-30 CA CA002214002A patent/CA2214002A1/fr not_active Abandoned
  • 1996-12-30 WO PCT/FR1996/002102 patent/WO1997025202A1/fr not_active Application Discontinuation
  • 1996-12-30 EP EP96944101A patent/EP0813473A1/fr not_active Withdrawn
  • 1996-12-30 JP JP9524900A patent/JPH11502163A/ja active Pending
  • 1996-12-30 IL IL12167996A patent/IL121679A0/xx unknown
• 1997
  • 1997-01-10 AR ARP970100096A patent/AR006966A1/es unknown
  • 1997-01-10 AR ARP970100095A patent/AR005428A1/es unknown
  • 1997-09-09 NO NO974144A patent/NO974144D0/no not_active Application Discontinuation

Patent Citations (6)

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