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WO1996017024A1 - Traitement de surfaces peintes - Google Patents

Traitement de surfaces peintes Download PDF

Info

Publication number
WO1996017024A1
WO1996017024A1 PCT/GB1995/002816 GB9502816W WO9617024A1 WO 1996017024 A1 WO1996017024 A1 WO 1996017024A1 GB 9502816 W GB9502816 W GB 9502816W WO 9617024 A1 WO9617024 A1 WO 9617024A1
Authority
WO
WIPO (PCT)
Prior art keywords
composition
water
paint
leached
hull
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB1995/002816
Other languages
English (en)
Inventor
John Fox
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Paint Ltd
Original Assignee
Courtaulds Coatings Holdings Ltd
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 Courtaulds Coatings Holdings Ltd filed Critical Courtaulds Coatings Holdings Ltd
Priority to EP95938527A priority Critical patent/EP0794982A1/fr
Publication of WO1996017024A1 publication Critical patent/WO1996017024A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D9/00—Chemical paint or ink removers

Definitions

  • This invention relates to a process and composition for the rehabilitation and/or rejuvenation of the surface of an antifouling paint which has been in service on a ship's hull.
  • Antifouling paint traditionally comprises a biocide for aquatic organisms, dispersed in a paint binder.
  • the biocide typically is a sparingly soluble biocide having a solubility in seawater of less than 50 parts per million (p.p.m.) by weight, preferably 0.5-10 p.p.m.
  • the most widely used marine biocide is cuprous oxide, although other sparingly soluble copper and zinc compounds are also used, as are organic compounds of similar solubility which are biocides for barnacles, algae and/or diatoms.
  • the sparingly soluble biocide is gradually leached out of the paint, so that the concentration of biocide at the surface of the hull is high enough to prevent settlement of marine organisms such as barnacles, algae or diatoms on the hull.
  • the antifouling paint binder can be of the soluble matrix or eroding type, in which at least part of the binder is sparingly soluble in seawater and is gradually dissolved in seawater after the biocide has been leached out, or of the insoluble matrix type, in which the binder has lower seawater solubility but the pigment volume concentration of biocidal pigment (such as cuprous oxide) and optionally other pigments is higher.
  • biocidal pigment such as cuprous oxide
  • a further type of antifouling paint binder is the "self-polishing" type in which a polymeric binder is gradually hydrolysed to become water-soluble.
  • One example of this type is a triorganotin acrylate or methacrylate polymer as described in GB-A- 1457590; another example is an acrylate or methacrylate polymer having pendent copper carboxylate groups as described in EP-A-204456.
  • This "leached layer” may cause several problems. When the hull is repainted, the presence of the leached layer may cause bubbling of the newly applied paint and detachment of the new antifouling from the old leached antifouling.
  • the leached layer hinders the free release of remaining biocide from underlying intact antifouling paint which still contains the biocide, and it thus retards the rate at which biocide is released from the paint, perhaps eventually to a rate which allows the growth of barnacles, algae and/or diatoms on the surface of the hull.
  • the object of the present invention is to provide a process and a composition for the removal of a leached layer which has built up on a ship's hull coated with antifouling paint.
  • a process according to the invention for removal from a hull of a ship of the outer leached layer of an antifouling paint originally comprising a paint binder and a biocide but from which seawater-soluble material has been leached is characterised in that a water-dispersible composition comprising a solvent for the paint binder remaining in the leached layer is applied to the surface of the antifouling paint, and the surface thus treated is subsequently washed with water to remove the said water- dispersible composition containing dissolved or emulsified material of the leached layer, thereby exposing a surface of underlying intact antifouling paint, i.e. comprising paint binder and biocide.
  • the invention also includes the use of a solvent composition to remove from a hull of a ship an outer leached layer of an antifouling paint, originally comprising a paint binder and a biocide but from which seawater-soluble material has been leached, characterised in that the solvent composition used is a thickened water- dispersible composition comprising a solvent for the paint binder remaining in the leached layer and is capable of being removed from the surface of a painted ship's hull by water washing.
  • a composition according to the invention for facilitating the removal from a hull of a ship of an outer leached layer of an antifouling paint, originally comprising a paint binder and a biocide but from which seawater-soluble material has been leached is a thickened water-dispersible composition comprising a water- dispersible solvent for the paint binder remaining in the leached layer and a thickening agent so that the composition has a viscosity sufficiently high that the composition can be coated on the surface of the said antifouling paint with the ship in a substantially vertical position substantially without running down the hull.
  • the paint binder can for example be rosin or maleinised or fumarised rosin.
  • the paint binder can alternatively be a hydrophilic acrylic polymer, for example a polymer containing units of an alkoxyalkyl acrylate or methacrylate such as methoxyethyl acrylate or a polyoxyalkylene acrylate or methacrylate as described in GB-A-2152947 or units of a hydroxyalkyl acrylate or methacrylate such as hydroxyethyl methacrylate as described in WO-93/02146.
  • the binder may be a mixture of rosin with such a hydrophilic acrylic polymer or with any other acrylic polymer such as polybutylacrylate or with a vinyl ether polymer such as a copolymer of vinyl methyl ether with vinyl chloride or vinyl acetate.
  • these binders are intended to be, and usually are, gradually dissolved in seawater, it has been found that a thick leached layer up to 50 or 100 microns thick sometimes forms, particularly in the case of soluble matrix paints which contain a hydrophilic acrylic polymer or a vinyl ether polymer as part or all of the paint binder.
  • the binder is often a mixture of resins with different seawater solubility, and the less soluble resins frequently become enriched in the leached layer.
  • the paint binder can for example be a vinyl chloride polymer such as a vinyl chloride/vinyl acetate copolymer.
  • a paint can form a thick leached layer, particularly if the pigment volume concentration of the paint is below the critical pigment volume concentration.
  • Antifouling paints of the "self-polishing" type generally have a thin outer leached layer, typically 10 to 30 microns thick, of paint binder which is at least partly hydrolysed but which has not yet dissolved. Such a thin leached layer does not spoil the antifouling efficiency of the paint, but in some cases it may be desired to remove the leached layer before overcoating with further antifouling.
  • the solvent composition which is applied to the leached layer of antifouling paint should dissolve the paint binder remaining in the leached layer or emulsify it sufficiently that it can be washed off with water.
  • the solvent composition must be at least water-dispersible, that is to say it must at least disperse in water and may be water-miscible or dissolve in water. It may itself be an aqueous composition containing for example at least 20 or 40% up to 80 or 90% water, by weight.
  • the solvent composition contains a hydrocarbon solvent which dissolves or disperses the paint binder remaining in the leached layer.
  • a solvent which is particularly useful for dissolving leached rosin layers is a terpenic hydrocarbon such as limonene, for example D-limonene, or pinene.
  • the hydrocarbon solvent can alternatively be a "white spirit", which is a predominantly aliphatic, especially paraffinic, hydrocarbon mixture.
  • the white spirit is preferably one having some aromatic content, for example 10 to 30% by weight aromatics, although entirely aromatic hydrocarbon solvents are less effective than white spirit.
  • White spirit is itself less effective than D-limonene as a solvent for leached rosin layers, that is to say it may need to be used at a higher concentration in the solvent composition or with a longer contact time between application of the composition and water washing, but white spirit may be preferred because of lower cost.
  • a mixture of white spirit and a terpenic hydrocarbon may be used.
  • the proportion of hydrocarbon solvent in the solvent composition is preferably at least 5 and may be up to 50 or even 80% by weight, with the most preferred proportion being in the range 8 or 10 to 30% by weight for many leached layers.
  • the solvent composition preferably contains sufficient of a surfactant to ensure that the hydrocarbon solvent is stably dispersed in the solvent composition and/or that the solvent composition is itself water-dispersible on washing with water.
  • the surfactant can be an anionic, nonionic or cationic surfactant; an example of a suitable anionic surfactant is an ammonium, amine or alkali metal salt of a long-chain sulphonic acid such as dodecylbenzenesulphonic acid.
  • the surfactant can be present at up to 30% by weight of the solvent composition, most preferably at 5 to 25%, particularly 15 to 25%, by weight.
  • An example of a solvent which is miscible with water and which can be used in the solvent composition is an ether alcohol for example methoxypropanol, ethoxyethanol, butoxyethanol or ethoxyethoxyethanol.
  • the ether alcohol acts as a solvent for hydrophilic acrylic polymers and for vinyl ether polymers. Esters of such ether alcohols, for example methoxypropyl acetate, can also be used. Other alcohols or carboxylate esters may also be useful.
  • the proportion of water-miscible solvent, for example ether alcohol, in the solvent composition can be up to 50% by weight, preferably up to 25%, for example 1 to 20%, by weight. The presence of such a water-miscible organic solvent in the solvent composition may aid in the solution or dispersion of a hydrocarbon solvent.
  • the solvent composition is preferably thickened before application to the leached layer on the ship's hull, for example by incorporation of a thickening agent which makes the composition thixotropic or pseudoplastic.
  • the solvent composition may even be gelled, provided it is capable of being applied to the hull.
  • the thickening agent used is preferably a fine-particle silica gel such as that sold under the Trade Mark "Aerosil 200", which can for example be used at 2 to 6% by weight of the composition, and/or a bentonite clay.
  • the thickened solvent composition most preferably has a viscosity at low or zero shear higher than is usual for paint; this allows application of a thick layer of the solvent composition, preferably at least 100 microns, for example 150 or 200 microns up to 250 or even 500 microns thick (wet film thickness), and it inhibits the penetration of the solvent composition into the intact antifouling paint below the leached layer.
  • the thickened solvent composition is preferably applied by spray, for example airless spray, especially when treating big ships, but it can alternatively be applied by brush or roller.
  • the thickened composition is preferably able to be applied to a ship's hull when the ship is in a substantially vertical position, for example in a dry dock, substantially without the composition running down the hull.
  • the solvent composition can contain one or more additional ingredients, for example it may contain a colouring pigment to aid visibility so that there is an easy check that the solvent composition has been removed before re-painting.
  • a light wash (hosing down with water at a normal pressure of up to 10.5 MPa (1500 psi) is usually adequate in the case of treated layers of "self-polishing" antifouling paints and may be sufficient for layers of other antifouling paints.
  • a high-pressure water wash at at least 10.5 MPa (1500 psi) and preferably at 14 MPa (2000 psi) or more, particularly 14 to 35 MPa (2000- 5000 psi), is usually preferred to ensure removal of all the treated leached layer.
  • water washing can take place any time from 5 minutes to 5 days or more after the solvent composition has been applied; but it is preferred to carry out washing 1 to 24 hours after application of the solvent composition, most preferably at least 2 or 3 hours, for example 4 to 16 hours, after application. Water washing should be continued until all the solvent composition has been washed from the hull before applying further antifouling paint.
  • the removal of the leached layer provides a surface of intact paint to which newly applied antifouling paint, for example a self-polishing organotin antifouling paint or an eroding soluble matrix antifouling paint, will adhere securely without bubbling. If there is a substantial layer of old intact paint beneath the leached layer, this will be revealed and biocide will subsequently be leached from the paint at the intended rate,. Moreover, removal of the leached layer restores the colour of the painted surface from a faded appearance to an appearance more like a freshly painted surface.
  • antifouling paint for example a self-polishing organotin antifouling paint or an eroding soluble matrix antifouling paint
  • Example 1 The process of Example 1 was repeated except for the use of the following solvent compositions (% by weight based on liquid ingredients) in place of the composition used in Example 1:
  • Example 2 64% by weight "Citrisolve Concentrate” as described in Example 1 was mixed with 3% by weight "Aerosil 200" and 1% by weight of the tinter used in Example 1 in a high speed disperser for 15 minutes. A further 32% by weight 'Citrisolve Concentrate” was mixed into the mixture for 5 nutes before any gel formation occurred. A thixotropic 1 then formed about 12 hours after manufacture. The resulting gel was applied by airless spray to the underwater hull area of a ferry at a thickness of 200 microns.
  • the hull had previously been coated with a rosin- based soluble matrix antifouling paint and had a pale "patina" or leached layer of antifouling on about 50% of its underwater area, which layer could not be removed by water washing at 4,000 psi (28 MPa) .
  • the gel composition was left in contact with the leached layer for 2 hours.
  • the treated hull was then water washed at 4000 psi (28 MPa) followed by a wash at 2000 psi (14 MPa) to remove any traces of foam caused by the surfactant in the gel composition.
  • the leached layer was completely removed and the colour of the hull reverted back to the original red colour of the soluble matrix antifouling paint.
  • the treated hull was overcoated the next day with a rosin-based soluble matrix antifouling paint. No problems of bubbling or adhesion were encountered during coating or subsequently in service.
  • the gel was sprayed by airless spray onto the underwater hull of a container ship which had a pale leached layer of soluble matrix antifouling paint resulting from excessive time spent stationary in harbour between newbuilding and pre-delivery drydocking.
  • the ambient temperature was 2°C, but no problems were encountered during spraying.
  • the gel was applied to the whole starboard side and the bow and stern of the port side, and was left in contact with the leached layer for about 12 hours.
  • the starboard broadside was water-washed at 24.5 MPa (3500 psi) using a hydroblasting machine and the bow and stern (both sides) were water washed at 17.5 MPa (2500 psi) with high-pressure water lances.
  • the port broadside (which had not been treated according to the invention) was water washed at 35 MPa (5000 psi) using the hydroblasting machine. In the areas treated according to the invention, the leached layer was removed and the underlying antifouling remained in its active state and original red colour. The leached layer was not removed from the port broadside.
  • the treated hull was overcoated with an organotin self-polishing antifouling paint.
  • the areas which had been treated according to the invention showed no bubbling or detachment of the overcoating.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)

Abstract

Procédé de décapage d'une couche extérieure de peinture antifouling déposée sur la coque d'un bateau et ayant été lessivée, comprenant à l'origine une peinture servant de liant et un produit biocide, mais dont la partie soluble à l'eau de mer a été lessivée. Ledit procédé consiste à appliquer à la surface de la peinture antifouling une composition hydrodispersible comportant un solvant du liant restant dans la couche lessivée. La surface ainsi traitée est ensuite rincée à l'eau pour éliminer ladite composition contenant des produits dissous ou émulsifiés provenant de la couche lessivée de manière à mettre à nu la surface de la couche sous-jacente d'antifouling.
PCT/GB1995/002816 1994-12-02 1995-12-01 Traitement de surfaces peintes Ceased WO1996017024A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95938527A EP0794982A1 (fr) 1994-12-02 1995-12-01 Traitement de surfaces peintes

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9424415A GB9424415D0 (en) 1994-12-02 1994-12-02 Treatment of painted surfaces
GB9424415.9 1994-12-02

Publications (1)

Publication Number Publication Date
WO1996017024A1 true WO1996017024A1 (fr) 1996-06-06

Family

ID=10765365

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1995/002816 Ceased WO1996017024A1 (fr) 1994-12-02 1995-12-01 Traitement de surfaces peintes

Country Status (4)

Country Link
EP (1) EP0794982A1 (fr)
GB (1) GB9424415D0 (fr)
TW (1) TW372245B (fr)
WO (1) WO1996017024A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2872824A1 (fr) * 2004-07-06 2006-01-13 Rhodia Chimie Sa Procede pour epaissir un milieu liquide concentre en agents tensioactifs
WO2014032166A1 (fr) * 2012-08-29 2014-03-06 Protocol Environmental Solutions, Inc. Décapant de peinture antisalissure

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0330379A2 (fr) * 1988-02-26 1989-08-30 The British Petroleum Company p.l.c. Compositions de nettoyage
WO1994024216A1 (fr) * 1993-04-14 1994-10-27 Edwin Stevens Procedes et compositions de decapage de peinture

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0330379A2 (fr) * 1988-02-26 1989-08-30 The British Petroleum Company p.l.c. Compositions de nettoyage
WO1994024216A1 (fr) * 1993-04-14 1994-10-27 Edwin Stevens Procedes et compositions de decapage de peinture

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2872824A1 (fr) * 2004-07-06 2006-01-13 Rhodia Chimie Sa Procede pour epaissir un milieu liquide concentre en agents tensioactifs
WO2006013282A1 (fr) * 2004-07-06 2006-02-09 Rhodia Chimie Procede pour epaissir un milieu liquide concentre en agents tensioactifs
WO2014032166A1 (fr) * 2012-08-29 2014-03-06 Protocol Environmental Solutions, Inc. Décapant de peinture antisalissure

Also Published As

Publication number Publication date
EP0794982A1 (fr) 1997-09-17
TW372245B (en) 1999-10-21
GB9424415D0 (en) 1995-01-18

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