Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B59/00—Hull protection specially adapted for vessels; Cleaning devices specially adapted for vessels
  • B63B59/04—Preventing hull fouling
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
  • C23F13/02—Inhibiting corrosion of metals by anodic or cathodic protection cathodic; Selection of conditions, parameters or procedures for cathodic protection, e.g. of electrical conditions
  • C23F13/04—Controlling or regulating desired parameters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B2221/00—Methods and means for joining members or elements
  • B63B2221/10—Methods and means for joining members or elements using adhesives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B2231/00—Material used for some parts or elements, or for particular purposes
  • B63B2231/02—Metallic materials
  • B63B2231/12—Copper or copper alloys
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F2213/00—Aspects of inhibiting corrosion of metals by anodic or cathodic protection
  • C23F2213/30—Anodic or cathodic protection specially adapted for a specific object
  • C23F2213/31—Immersed structures, e.g. submarine structures

Definitions

• the rate of leaching is not constant.
• the layer exposed to the water is first exhausted, later followed by deeper laying layers.
• the antifouling paints becomes less and less effective with exposure time. This is particularly true for pleasure boats, many of which spend most of their time at rest at their moorings. Hence the antifouling is subdued to little attrition and the active antifouling components have to diffuse through the paint layer to reach the water.
• the paint matrix is frequently made of components permitting the release of the toxic substance when in contact with water.
• the matrix thus assumes an open structure actually absorbing the water.
• This inevitable and necessary property of constituting an open structure strongly reduces the paints protective qualities in all other respects than its antifouling properties.
• paints offer no protection against so called "osmosis", the uptake of water by the polyester laminate, frequently being the preferred material for boat construction.
• the antifouling paints equally, offers no or very poor additional protection of the hull against mechanical chocks.
• antifouling paints because of its open structure, are mat, giving the underwater surface a rough finish. This roughness, which is in the order of 250 microns, adds significantly to the water resistance and the cost of propelling the vessels.
• a further inconvenience with antifouling paints is its property to smear on contact. Whilst the boat in water, any contact with the antifouling paint will cause smearing of the object with the paint leaving patches that are difficult to remove. Many have had their ropes, fenders and bathing suits destroyed by contact with antifouling paint.
• hulls were made of wood.
• the underwater parts were protected by covering the hull beneath the water line by nailing sheets of copper by the use of copper nails to the wooden hull.
• Experience using steel nails rapidly proved fatale as the steel nails corroded away within short and the sheets ran the risk of falling off.
• the copper-containing plates were thick, to be handled and hence heavy.
• the antifouling effect was very satisfactory indeed not to say outstanding. Its antifouling properties lasted unchanged, year after year.
• the US patent US4987036 describes a method trying to overcome the problem of using copper-containing sheets to surfaces for their protection against fouling. Also this method necessitates the prior bonding of the copper-containing sheets to a supporting structure, made of a mesh, grid or an elastic material, for subsequent bonding of this laminate, using exclusively a curable neoprene rubber, to the surface to be protected. This method overcomes the problem of covering curved shapes by first bonding, to the above mentioned supporting structure, narrow copper or copper nickel sheets comprising a plurality of individual strips of copper or a copper-nickel alloy in the form of substantially parallelogram in shape.
• the present invention describes a method, a product and its application, permitting an effective and practical use of copper-containing sheets to counteract biological fouling on any surface including complicatedly shaped surfaces such as boat-or ship hulls in particular.
• the method overcomes the difficulties of bonding copper-containing sheets to surfaces, curved in three dimensions.
• the method also and additionally provides further protection of the underwater surfaces against damages caused by the surfaces contact with water such as so called osmosis and the method adds to the strength of the structure and its resistance to mechanical shock.
• the use of the method further reduces the roughness of the hulls thus permitting improved fuel economy or higher speeds.
• the protected surface moreover, becomes essentially smear-free thus offering enormous advantages both when it comes to handling of the protected surface and the almost total absence of environmental impact when cleaning.
• the method provides protection from fouling over a period of several years.
• Copper-containing materials are heavy and thick plates may not become sufficiently bonded to withstand its tendency to fall down by its own weight. Also this is avoided using very thin sheets or foils. Such thin sheets may basically be held in place by the hydrostatic pressure exerted on them by the water pressure, provided that essentially no water is permitted to enter between the surface to be protected and the copper-containing sheet itself. Such close contact can be achieved by the use of one or several commercially available adhesives.
• the sheets must not be too thin. They should of course be sufficiently thick so as not to corrode away too quickly, making the use impractical. As it has been reported that, under realistic conditions on commercial vessels, the rate of corrosion is in the order of 10 pm per year, the practical absolute minimum thickness would be some 10 ⁇ m.
• the copper-containing sheets must additionally have properties such as to permit its firm bonding to the surface to be sheeted. Also this is facilitated by the use of very thin and soft sheets. Copper-containing materials have a high thermal expansion coefficient, which differs much from that of the materials normally used for ship- and boat hulls. A thin and soft copper-containing sheet exerts less global strain on the bonding than a thick one as the temperature changes.
• the surface to be coated must also be prepared so as to enable its sheathing. Also this aspect is covered by the new invention. Then, the adhesive means used to bond the sheets to the surface must have a high bonding power between the copper-containing sheets and the surface to be treated.
• the sheathing must be reversible, i.e. some day, eventually, all hulls must be refurbished and the removal of the sheathing must not be virtually impossible, risk to destroy the hull itself or otherwise cause damage to it.
• One aspect of the new invention takes full account of this must important aspect.
• thin soft copper-containing sheet or foil is bonded directly, without the need of supporting films or structures, to the curved surfaces to be protected by the use of any commercially available adhesive suitable for the water resistance bonding of copper-containing sheets onto the surface to be protected. Because of the softness and the low weight of such thin copper-containing foils, the strain on the bonding is low and the bonding itself, with the proper selection of adhesive, becomes stronger than the foil itself.
• the practical thickness of the foils was found to be in the range of 20 to 250 ⁇ m, preferably between 10 and 100 ⁇ m.
• thin copper-containing sheets or foils can be prepared in advance with a water resistance adhesive, which can be activated at a later time when the actual sheathing has to take place.
• a water resistance adhesive which can be activated at a later time when the actual sheathing has to take place.
• Such adhesives can be of any of the types found among the group of "tapes", known under the commercial names "SCOTCH", "TESA”, etc.
• Such adhesives are frequently derivatives of acrylics but the invention is in no way limited to the use of such acrylics as any water resistant adhesive can be used.
• the foils may thus be prepared in advance to form a composite tape where the adhesive side would covered by a so-called release cover to be removed just prior to the sheathing.
• other suitable adhesives can be used as those activated by heat, solvents or other methods.
• thin copper-containing sheets can be used to constitute an integral part of a ship's or boat's hull.
• Boats made of glass fibre reinforced resins, like polyester, epoxy etc. are produced by laminating the fibreglass with the resin in moulds. When the laminate has hardened and cured, the mould is removed and the hull is then fitted with such further details as to make it complete. The bottom must then be painted with antifouling.
• the present invention facilitates the completion of the hulls.
• the copper-containing sheet is first placed on the part later of the mould later to hold the underwater part of the hull, then the laminating proceeds as usual, taking into full account to use a laminating resin having a sufficient adhesion to the copper-containing foil.
• the hull When the laminate has hardened and cured and the mould has been removed, the hull already has its underwater part sheathed with the copper-containing sheet. In this way the finished hull will have an incorporated antifouling treatment.
• the same technique can be used for any item, produced in moulds and which should possess antifouling properties
• the copper-containing sheets are mounted to the surface in such a way as not to expose any edge of copper-containing sheet to the main direction of the water flow. This may be achieved by ensuring to overlap the sheets "downstream" thus effectively reducing the risk of the sheets being peeled off by the action of the flow of water over the surface when the vessel is making headway.
• copper-containing foil as thick as typically 100 micron of the soft quality, supplied by the company Outokompu, Viferas, Sweden could be shaped to follow any curvature present on boat hulls. This thickness would correspond to about ten years of heavy use, a considerable advantage compared to antifouling paint practice of repainting mostly every year.
• the roughness of the copper-containing foil was in the order of 5 microns.
• This surface was subdued to severe testing including twenty cycles of consecutive freezing and prolonged, 48 hours, exposure to 40 °C warm salt-water. The surface was equally subjected to 80 bar water jet cleaning. Neither of these conditions led to any visual separation of the copper-containing foil from the surface.
• the surface to be protected was first prepared in the same way as in example 1 but using a glossy paint.
• the surface of the hull to be studied was first clad with the double-sided tape (so called adhesive transfer tape available from the company 3M) making sure to cover the entire underwater surface and a band some decimetres above the waterline.
• adhesive transfer tape available from the company 3M
• the copper-containing-containing foil was pressed firmly, against the adhesive tape by the aid of a rubber roller. Care was taken not to enclose any air under the copper-containing-containing foil. Thus the work proceeded until the entire surface, to be studied, was covered.
• glossy paint was used in this example, the invention is in no way limited to the use such paint as also mat paint gives satisfactory results.
• the boat was then launched.
• a hydrostatic pressure actually counteracted the weight of the copper-containing sheathing so that in theory no further bonding would be required under static conditions, which explains why such a relatively unqualified adhesive turned out to have sufficient bonding strength.
• a boat or ship does not stay at rest and the water swirling by, when the hull makes headway, exerts a force on the sheathing. To avoid “peeling" off of the sheathing, it was applied in such a way as to ensure that all overlapping of the sheets was done "downstream" i.e. the surface was clad from stem to bow.
• the copper-containing-containing sheet could be easily removed by heating the sheet by means of a hot air gun and a scraper.
• the surface to be sheeted was first prepared by proper cleaning, sanding and painting with a polyurethane paint.
• a copper-containing sheet 100 microns thick and from the same supplier, had been washed and treated to ensure the removal of grease and loose oxides. After drying, the double-sided transfer tape was applied to the copper-containing sheet, leaving the protective outer film intact.
• the protective film was then removed and the copper-containing sheet, with its transfer tape, was pressed against the surface of the boat hull by means of a rubber roller.
• the surface to be protected was prepared in the same way as in example 1, 2 and 3.
• the surface was then coated with a heat sensitive adhesive tape, available from 3M Company.
• a heat sensitive adhesive tape available from 3M Company.
• Such tapes perform like ordinary tapes but their bonding properties can be much improved on heating the substrate after the initial bonding.
• the copper-containing sheet was applied in the same way as in example 1 and 2 but the surface was later heated using an electrically heated "iron” device so as to cure the bonding according to 3M's specifications.
• a mould normally used for the production of boat structures, was first clad with the thin copper foil on the part to be under water in the finished hull. Then, on top of the copper foil, this area was laminated using epoxy resin and a thick glass fibre weave, commercially readily available. The lamination then proceeded using resin and fibre glass in the usual manner until the part was finished. After release from the mould, the part of the structure, to be submerged, was thus shethed with the copper foil.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Combustion & Propulsion (AREA)
• Ocean & Marine Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Laminated Bodies (AREA)

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Publications (1)

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Cited By (2)

Citations (9)

• 1999
  • 1999-09-17 EP EP99440252A patent/EP1084948A1/fr not_active Withdrawn

Patent Citations (9)

Non-Patent Citations (1)

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