Fouling release coatings

Abstract

A composition for use in the manufacture of a fouling release coating, e.g. at least one layer of a fouling release coating, comprising at least one curable or crosslinkable polysiloxane and at least one silane terminated polyurethane.

Claims

1. A multilayer fouling release coating comprising: (I) an epoxy primer layer on a substrate; (II) a layer comprising at least one polysiloxane and at least one silane terminated polyurethane directly over the layer (I), wherein said at least one polysiloxane is a silanol terminated polysiloxane; and (III) a polysiloxane layer top layer directly over the layer (II), wherein said polysiloxane top layer is free of silane terminated polyurethane, wherein said multilayer fouling release coating is free of any marine biocide, and wherein the polysiloxane and polyurethane of layer (II) are present in a weight ratio from 10:1 to 2:1.

2. A multilayer fouling release coating as claimed in claim 1 wherein the silane terminated polyurethane has a viscosity of 5,000 to 100,000 cP measured at 23 C. according to ASTM D2196.

3. A multilayer fouling release coating comprising: (I) an epoxy primer layer on a substrate; and (II) a layer comprising polysiloxane and at least one silane terminated polyurethane directly over the layer (I) which have been cured, wherein said polysiloxane is a silanol terminated polysiloxane; and (III) a polysiloxane layer top layer directly over the layer (II), wherein said polysiloxane top layer is free of silane terminated polyurethane, wherein said multilayer fouling release coating is free of any marine biocide, and wherein, prior to curing, the polysiloxane and polyurethane of layer (II) are present in a weight ratio from 10:1 to 2:1.

4. An article, comprising a vessel comprising a cured fouling release coating as claimed in claim 3.

5. A vessel comprising a cured fouling release coating as claimed in claim 3.

6. A multilayer fouling release coating comprising: (I) an antifouling coating or fouling release layer on a substrate; (II) a layer comprising at least one polysiloxane and at least one silane terminated polyurethane directly over the layer (I), wherein the layers (I) and (II) are different; and (III) a polysiloxane top layer directly over the layer (II), wherein said polysiloxane top layer is free of silane terminated polyurethane, wherein said multilayer fouling release coating is free of any marine biocide, and wherein the polysiloxane and polyurethane of layer (II) are present in a weight ratio from 10:1 to 2:1.

7. A multilayer fouling release coating comprising: (I) an antifouling coating layer or fouling release layer on a substrate; (II) a layer comprising at least one polysiloxane and at least one silane terminated polyurethane directly over the layer (I) which have been cured, wherein the layers (I) and (II) are different; and (III) a polysiloxane top layer directly over the layer (II), wherein said polysiloxane top layer is free of silane terminated polyurethane, wherein said multilayer fouling release coating is free of any marine biocide, and wherein, prior to curing, the polysiloxane and polyurethane of layer (II) are present in a weight ratio from 10:1 to 2:1.

8. A vessel comprising a cured fouling release coating as claimed in claim 7.

Description

DETAILED DESCRIPTION

(1) The composition for use in the fouling release coatings of the present invention comprises two key polymer components: at least one curable or crosslinkable polysiloxane and at least one silane terminated polyurethane.

(2) Polysiloxane

(3) The polysiloxane may be any curable or crosslinkable polysiloxane or a mixture of curable or crosslinkable polysiloxanes. By curable or crosslinkable it is meant that the polysiloxane contains reactive groups which enable it to be cured or crosslinked. Such reactive groups are ideally OH, epoxy, amino or alkoxy groups.

(4) The polysiloxane for use in the invention is well known and is already conventionally used without the silane terminated polyurethane in fouling release coatings. It will therefore be familiar to the person skilled in the art.

(5) Polysiloxanes of particular interest are based on polydimethylsiloxane.

(6) Preferably, the curable or crosslinkable polysiloxane is silanol terminated, or is hydrolysable to a silanol terminated polysiloxane. More preferably, the curable or crosslinkable polysiloxane is a silanol terminated diorganosiloxane or is hydrolysable to a silanol terminated diorganosiloxane.

(7) Ideally, the polysiloxane is of the general formula (I):

(8) ##STR00001##

(9) wherein each R.sup.8 is a hydroxyl, C.sub.1-6-alkoxy, C.sub.1-6-epoxy containing group, C.sub.0-6-alkylamino group or OSi(R.sup.10).sub.y(R.sup.11).sub.(3-y); each R.sup.9 is independently selected from C.sub.1-.sub.10 alkyl, C.sub.6-10-aryl and C.sub.7-12-alkylaryl; R.sup.10 is a hydroxy or a C.sub.1-.sub.6 alkoxy; R.sup.11 is hydrogen or a C.sub.1-.sub.6 alkyl; x is an integer of at least 2 z is 0 or an integer; and y is an integer from 1 to 3.

(10) R.sup.9 is preferably phenyl or methyl, especially methyl. R.sup.8 is preferably OH or C.sub.1-6-alkoxy.

(11) The molecular weight of the polysiloxane is preferably between 400 and 150,000, such as 4000 to 100,000 (determined by GPC).

(12) The viscosity of the polysiloxane may range from 10 to 80,000 cP, such as 40 to 50,000 cP, such as 500 to 25000 cP. Viscosity is measured at 23 C. according to ASTM D2196 using a Brookfield DV-I viscometer with RV-4 spindle at 4 rpm. The polymers are maintained at 23.0 C.0.5 C. before the measurements.

(13) In a particularly preferred embodiment, the curable or crosslinkable polysiloxane is a polydimethylsiloxane, especially a silanol terminated polydimethoxysilane or an alkoxy terminated polydimethoxysilane. The polysiloxane may also be phenyl functionalised, i.e. contain a phenyl side chain.

(14) It is, of course, possible to employ a mixture of two or more polysiloxanes in the compositions of the invention.

(15) Polysiloxanes of use in the invention can be purchased commercially. Commercial suppliers of polysiloxanes include Dow Corning and Momentive. Suitable polysiloxanes are sold under trade names such as Silopren and Dow Corning.

(16) Silane Terminated Polyurethane

(17) Urethane polymers can be modified by end capping some or all of the isocyanate groups with organosilanes. Silane terminated polyurethanes are commercially available polymers any may be called SPU herein.

(18) Urethane polymers bearing terminal active hydrogen atoms which are useful in the present invention can be prepared by the reaction of organic di or polyisocyanate reactants with a polyol such as a polyether. The use of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4-diphenyl-methanediisocyanate, 2,4-diphenyl-methanediisocyanate, isophorone diisocyanate, Desmodor N and the like can be used. A catalyst can of course be employed if necessary.

(19) The polyol may be a diol or triol such as polyether polyols, polyester polyols, polybutadiene diols, polyoxyalkylene diols, polyoxyalkylene triols, polytetramethylene glycols, polycaprolactone diols and triols. The use of propylene glycols is preferred.

(20) Simple diols may also be employed.

(21) To ensure the presence of an active OH group at the end of the polyurethane, a slight excess of polyol is typically used in the polymerisation.

(22) The nature of the urethane backbone can therefore vary but it will obviously contain the urethane OCONH repeating unit. Once formed, the polyurethane is silane terminated. Any silane can be used but it will preferably contain a reactive group such as OH, epoxy, amino or alkoxy groups so that it can cure with the polysiloxane.

(23) The silane terminating group is preferably one of formula (II)
Si(R.sup.1)(R.sup.2)(R.sup.3)(II)

(24) wherein R.sup.1, R.sup.2, R.sup.3 are each independently a C.sub.1-6 alkyl, C.sub.6-10 aryl, OC.sub.1-6alkyl, OH, C.sub.2-6alkenyl, OC.sub.2-6alkenyl, or a C.sub.1-6 epoxy containing group wherein at least one of said R.sup.1, R.sup.2, R.sup.3 groups is a curable group (i.e. is one of the above other than alkyl or aryl).

(25) The urethane may be silane terminated at either or both ends of the molecule. It will be appreciated that the commercial silane terminated polyurethanes are likely to contain a mixture of mono and diterminated molecules.

(26) It is most preferred if at least two of said R.sup.1, R.sup.2, and R.sup.3 groups are reactive, especially all of R.sup.1, R.sup.2, R.sup.3 are reactive (i.e. curable). Ideally, at least one R.sup.1, R.sup.2, R.sup.3 group is OC.sub.1-6 alkyl groups or OH. Ideally, two or all of R.sup.1, R.sup.2, R.sup.3 are OC.sub.1-6 alkyl groups, especially methoxy or ethoxy groups.

(27) Ideally all of R.sup.1, R.sup.2, R.sup.3 are the same.

(28) The addition of this Si(R.sup.1)(R.sup.2)(R.sup.3) groups is preferably achieved via reaction of the base polyurethane with a compound of formula (III):
OCNRSi(R.sup.1)(R.sup.2)(R.sup.3)(III)

(29) wherein R is a divalent organic group such as C.sub.1-6 alkylene, a C.sub.5-10-cycloalkylene or a C.sub.6-10arylene group and R.sup.1-R.sup.3 are as hereinbefore defined. Preferred compounds of formula (III) are therefore gamma-isocyanatopropyl-trimethoxy/triethoxy silane.

(30) Alternatively, the reactive compound may be N-phenyl-gamma-aminopropyltrimethoxysilane or N-phenyl-gamma-aminopropyltriethoxysilane.

(31) The Mw of the formed silane terminated polyurethanes may be 5000 to 100,000 g/mol, preferably 10,000 to 25,000 g/mol.

(32) They may have a viscosity of 5,000 to 100,000 cP, such as 15,000 to 90,000 cP, preferably 50,000 to 75,000 cP. Viscosity is measured at 23 C. according to ASTM D2196 using a Brookfield DV-I viscometer with RV-4 spindle at 2.5 rpm. The polymers are maintained at 23.0 C.0.5 C. before the measurements).

(33) SPUs are available commercially. Suppliers include, inter alia, Momentive, Wacker and Bayer. Products are sold under tradenames such as PFEIF, SPUR and Desmoseal

(34) The composition for use in forming fouling release compositions of the invention comprises at least one curable or crosslinkable polysiloxane and at least one silane terminated polyurethane. The weight ratio of these two components in the composition can vary. Preferably, the polysiloxane and polyurethane are present in a weight ratio 25:1 to 1:1, preferably 15:1 to 2:1, especially 10:1 to 2:1. There is therefore generally a significant excess of the polysiloxane. These figures are based on the total polysiloxane content.

(35) Additional Components

(36) In a further preferred embodiment, the composition for use in forming a fouling release composition, e.g. one layer of such a coating comprises: 1) at least one curable or crosslinkable polysiloxane and at least one silane terminated polyurethane composition; 2) a catalyst; and 3) optionally, a crosslinking agent.

(37) Ideally, composition of the invention comprises a room temperature vulcanizable (hereafter denoted RTV) composition comprising the components: 1) at least one curable or crosslinkable polysiloxane and at least one silane terminated polyurethane composition; 2) a catalyst; and 3) optionally, a crosslinking agent.

(38) By RTV means that when the components are mixed the polysiloxane and the silane terminated polyurethane will cure at the temperature in the environment in question without the application of heat. That might typically be in the range of 0 to 50 C.

(39) The RTV composition can be a one-part system but is preferably made up of several parts to prevent curing before desirable and hence is shipped as a kit of parts. Preferably, the composition contains no more than three parts.

(40) The crosslinking agent can be any suitable agent well known in the art. The crosslinking agent contains at least one, preferably at least two reactive groups such as hydroxyl or amino groups. Ideally, the crosslinking agent will be a silane, especially a hydrolysable silane compound, especially a low molecular weight silane of Mw less than 1000. It should have at two reactive groups such as OH or OC.sub.1-6alkoxy.

(41) It may have the general formula (IV):
R.sub.aSiR.sub.bR.sub.cR.sub.d(IV)
wherein two or three or four, preferably three, of R.sub.a, R.sub.b, R.sub.c and R.sub.d are independently a group selected from OH, oximino (e.g. a methylethylketoximo group), acetoxy, alkylamino (i.e. C.sub.1-6alkyl-NH.sub.2), C.sub.1-6 containing epoxy group and C.sub.1-6alkoxy, and any remaining of R.sub.a, R.sub.b, R.sub.c and R.sub.d is a group selected from C.sub.1-6 alkyl (e.g. methyl and ethyl), (meth)acryloxymethyl, C.sub.1-6-alkylamino, C.sub.2-6 alkenyl (e.g. vinyl) and aryl (e.g. phenyl).

(42) Ideally, R.sub.a-R.sub.d are C.sub.1-6alkoxy or C.sub.1-6alkylamine. Ideally there should be at least three C.sub.1-6alkoxy groups, preferably four C.sub.1-6alkoxy groups. Those are ideally methoxy or ethoxy. Preferred alkylamino groups are ethylamino (CH.sub.2CH.sub.2NH.sub.2) or propylamino.

(43) When present, the total amount of cross-linker added to the composition for use in the fouling release coating of the invention (i.e. the SPU/polysiloxane composition) is such that the crosslinker forms up to 30 wt %, such as in the range of 1-20 wt %, e.g. 2-10 wt % of the composition. In one particularly interesting embodiment, the total amount is in the range of 3-9% by weight. Mixtures of two or more crosslinkers may be used if desired.

(44) Examples of commercially available crosslinkers are alkoxy silanes such as: vinyltriethoxysilane, vinyltrimethoxysilane, oligomeric vinyltriethoxysilane, tris(3-(trimethoxysilyl)propyl)isocyanurate, vinyl-alkyl siloxane oligomer, octyltriethoxysilane, propyltriethoxysilane, methyltrimethoxysilane, tetra-n-propylsilicate, phenyltrimethoxysilane, tetraethoxysilane, ethyl silicate, alkoxy functional polysiloxane, (methacryloxymethyl)-methyldimethoxysilane, methacryloxymethyltrimethoxysilane, (methacryloxymethyl)-methyldiethoxysilane, methacryloxymethyltriethoxysilane, gamma glycidoxypropyl trimethoxysilane, gamma glycidoxypropyl triethoxysilane, beta-3,4-epoxycyclohexyl ethyl trimethoxysilane, and beta-3,4-epoxycyclohexyl ethyl triethoxysilane; and

(45) silanes with oxime or acetoxy functionalities such as: vinyltris(methylethylketoximo)silane, methyltris(methylethylketoximo)silane, methyltriacetoxysilane and vinyltriacetoxysilane.

(46) The use of tetraethoxysilane or aminopropyltriethoxysilane is preferred.

(47) We discuss below the option of including a further top coat above the layer of the invention. In that embodiment, we can consider that the SPUR layer is acting as a tie coat. Where an additional top coat is employed it is preferably free of silane terminated polyurethane but it may contain a polysiloxane, catalyst and crosslinker as herein defined. Such a crosslinker should be amine free however. The use of tetraalkoxysilane is preferred as the cross-linker in such a top coat.

(48) The crosslinking agent may be in a monomeric form or in the form of a self-condensation product, such as a dimer, oligomer or polymer.

(49) If the curable or crosslinkable polysiloxane is di- or tri-alkoxy terminated, a separate crosslinking agent is not necessarily required. In some embodiments, the silane terminated polyurethane may perform the role of the crosslinker. In a preferred embodiment, no crosslinking agent is present in the composition of the invention.

(50) Curing of the polysiloxane with the silane terminated polyurethane preferably proceeds in the presence of a catalyst. Useful catalysts are those well known in the art to facilitate condensation reactions in RTV silicone systems, such as carboxylic salts of tin, zinc, titanium, lead, iron, barium and zirconium. Non-metallic catalysts such as hexylammonium acetate and benzyl trimethylammonium acetate, may also be employed. A particularly preferred catalyst is dibutyltindiacetate or dialkyltindilaurate, e.g. dibutyltindilaurate. The amount of catalyst employed may be in the range of 0.01 to 3 wt % of the composition containing polysiloxane and the silane terminated polyurethane, e.g. 0.01 to 1 wt %.

(51) Curing is preferably carried out at a temperature of 0 to 50 C. such as 15 to 30 C. A relatively high humidity is also preferred such as 30%, preferably 50% relative humidity or more. Curing can be allowed to occur for up to 14 days before the formed layer is used either for further coating or in a submarine application. Preferably of course, curing should occur as rapidly as possible, e.g. within 24 hrs.

(52) It will be appreciated that to prevent curing the catalyst, cross-linking agent and the polysiloxane/polyurethane compositions are ideally kept apart until curing is desired.

(53) Other Additives

(54) The composition suitable for use as a layer in a fouling release composition comprising a curable or crosslinkable polysiloxane together with a silane terminated polyurethane in accordance with the present invention may also include one or more non-reactive oils and other substances commonly used in coating formulations such as fillers, pigments, solvents and other additives such as waxes, dyes, dispersants, wetting agents, surfactants, water scavengers and thickeners.

(55) Examples of non-reactive oils include silicone oils such as non curable polysiloxanes, methylphenyl silicone oils; organic oils such as polyolefin oils and paraffin and biological oils such as coconut oil. These compounds are non curable as they are free of reactive groups. They are therefore commonly terminated in hydrocarbyl groups such as alkyl groups or aryl groups.

(56) Examples of fillers include barium sulphate, calcium sulphate, calcium carbonate, silicas, silicates, bentonites and other clays. The preferred fillers are silica, including hydrophobic and hydrophilic fumed silica and precipitated silica.

(57) Examples of pigments include titanium dioxide, iron oxides, carbon black, lamp black, iron blue, phthalocyanine blue, cobalt blue, ultramarine blue, and phthalocyanine green. It will be appreciated that some pigments such as titanium dioxide can also act as fillers.

(58) Examples of suitable solvents and diluents include aromatic hydrocarbons such as toluene, xylene, trimethylbenzene; aliphatic hydrocarbons such as white spirit; alcohols such as 1-methoxy-2-propanol, 4-hydroxy-methylpropylether (Dowanol), and butanol; ketones such as 2,4-pentanedione, 4-methyl-2-pentanone, 5-methyl-2-hexanone, cyclohexanone; esters such as butyl acetate and mixtures thereof.

(59) It is preferred if the fouling release coating of the invention is free of any marine biocide such as cuprous oxide.

(60) Considering the composition used to form the cured layer of the invention as shipped or as applied, the at least one polysiloxane preferably forms 10 to 30 wt % of the composition. The silane terminated polyurethane preferably forms 4 to 50 wt % of the composition. Solvent preferably makes up 20 to 40 wt % of the composition. Other additives total less than 20 wt % of the composition. When the film is cured there is substantially no longer any solvent in the cured film.

(61) The crosslinker is preferably kept separate from the first component until curing is desired. The crosslinker is preferably supplied as is, i.e. 100% crosslinker.

(62) The catalyst is preferably kept separate from both the cross-linker and the coating composition until curing is desired. It is preferably supplied as a 0.5 to 10 wt % solution in a hydrocarbon solvent such as an aromatic solvent or alcohol solvent.

(63) Application

(64) The compositions of the invention may be utilised in the manufacture of fouling release coatings for preventing fouling in an aquatic environment, in particular a marine environment.

(65) The compositions of the invention are particularly useful in fouling release coatings for articles submerged in sea water. Preferably, the articles are marine constructions such as vessels, oil platforms and buoys. Ideally, the surface is on a vessel which is adapted to travel faster than 8-10 knots.

(66) The coating can be applied by any conventional method such as brushing, rolling or spraying (airless or conventional). The composition of the present invention can be applied onto any pre-treatment layers designed for polysiloxane based fouling release finish layers.

(67) As noted above, it is not possible to coat a metallic substrate directly with the fouling release compositions of the invention as they do not possess the necessary anti-corrosion properties. It will still be necessary to provide a substrate therefore with an anticorrosive primer layer. Such primer layers are very well known in the art. They are typically based on epoxies. Commercial primers include Jotamastic 87 and Jotacoat Universal.

(68) In a preferred embodiment therefore the composition of the invention is applied directly to this primer coating to form the fouling release coating of the invention. Thus, the invention relates to an article comprising a multilayer fouling release composition, said article comprising a metal layer, a primer layer and a cured composition of the invention as tie layer/top coat.

(69) It may be necessary however to employ a further layer, above the polysiloxane/polyurethane layer of the invention. The invention definitively allows the elimination of the link layer normally used between a primer layer and a tie coat.

(70) Such a further top coat can be a conventional polysiloxane top coat free of the SPU of the invention. The top coat can therefore comprise a polysiloxane e.g. as hereinbefore defined, crosslinker and catalyst as hereinbefore described but no SPU. Such a top coat is a commercially available material e.g. SeaLion Repulse from Jotun AS.

(71) In a preferred embodiment, the coating of the invention is applied directly to the epoxy primer layer used in conventional fouling release coating systems.

(72) Moreover, the layer of the invention can also be applied directly on top of conventional anti-fouling coatings or fouling release coatings already present on the surface of an article. The composition of the invention can therefore be retrofitted to any ship which already has an anti-fouling coating or fouling release coating based on existing technology. There is no requirement therefore to add a link coat.

(73) In all embodiments of the invention, the layer may be utilised in a fouling release coating which, once applied to a surface, is further coated with a topcoat. The coating layer in this instance acts as a both a link coat and a tie coat, thereby eliminating the need for the former as an additional layer leading to cost savings.

(74) The layer of the invention may also be utilised in a fouling release coating which is used in the absence of a further topcoat. The coating layer thereby acts as a link coat, tie coat and top coat.

(75) Whilst it is possible to have all components of the coating layer present in a single pack, provided that the material is kept dry, it is preferred if the compositions of the invention are transported in kits, preferably with the polymer components kept separate from the catalyst component to prevent curing taking place prior to application to the desired surface. In theory, the silane terminated polyurethane component can be added to any of the components of the kit such as the polysiloxane, catalyst or crosslinker component (if present). The components should be combined and thoroughly mixed before use. Conventional mixing techniques can be used.

(76) Such kits provide a further aspect of the invention. A crosslinker may additionally be present in the kits of the invention in either the catalyst component, SPU/polysiloxane component or as a separate component.

(77) The layer formed using the silane terminated polyurethane/polysiloxane composition of the invention is preferably 50 to 400 um in thickness. The primer coat is typically 100 to 600 um in thickness. Should an additional top coat be used this preferably has a thickness of 50 to 500 um. It will be appreciated that any layer can be laid down using single or multiple applications of the coating.

(78) The invention will now be described with reference to the following non-limiting examples.

(79) Methods and Materials

(80) Polysiloxane was provided as part of the commercially available SeaLion Tiecoat which is a three-pack foul release coating which contains polysiloxane (Component A), a catalyst (Component C) and a cross-linking agent (Component B).

(81) Silane Terminated Polyurethane

(82) Desmoseal S XP 2774 viscosity approx. 50000 mPas at 23 C.

(83) Desmoseal S XP 2636 viscosity 32000-42000 mPas at 23 C.

(84) PFEIF 1199 viscosity approx. 25,000 mPas at 23 C.

(85) SPUR 1015 LM viscosity approx 50,000 cP at 25 C.;

(86) (1 cP=1 mPas)

(87) CatalystThe composition used in example 1 below contains a catalyst, dibutyl tin acetate provided as SeaLion Tiecoat component C.

(88) CrosslinkerThe composition used in example 1 below also contains aminopropyl triethoxyl silane) provided as SeaLion Tiecoat component B.

(89) Epoxy Based Primers

(90) Two standard, commercially available epoxy based primers (Jotamastic 87 and Jotacoat Universal) produced by Jotun A/S were utilised in the examples.

(91) Anti-Fouling Coatings

(92) Two standard, commercially available anti-fouling coatings (SeaQuantum and SeaForce) produced by Jotun A/S were utilised in the examples.

(93) Adhesion Strength

(94) Adhesion strength was determined by way of scratching the surface with a spatula 12 and 24 hours after curing at ambient temperature and humidity (20 C. and 60% relative humidity) and was measured on a scale of 1 to 5, 1 conveying poor adhesion and easy removal of the coating and 5 indicating strong adhesion.

(95) The following examples illustrate the present invention:

(96) Preparation of Panels to be Coated

(97) Panels Coated with Jotamastic and Jotacoat Universal

(98) Polyvinyl chloride or steel panels (4020 cm and 2010 cm) were coated with Jotamastic 87 or Jotacoat Universal using airless spray. Jotamastic 87 was applied with a wet film thickness of 245 micrometers and cured for 12 hours at 23 C. and 70% air humidity. Jotacoat Universal was applied with a wet film thickness of 220 micrometers and cured for 12 hours at 23 C. and 70% air humidity. The silane terminated polyurethane containing polysiloxane coating was applied using either airless spray or with an applicator with a film thickness of 150 micrometers and was left to cure at 23 C. and 70% humidity for 24 hours.

(99) Panels Coated with SeaQuantum Classic

(100) Polyvinyl chloride panels were coated with Safeguard Universal ES with a wet film thickness of 240 micrometers using airless spray and left to cure for 12 hours at 23 C. and 70% humidity. The Safeguard Universal ES substrate was coated with SeaQuantum Classic using airless spray with a film thickness of 250 micrometers and dried for 24 hours at 23 C. and 70% humidity.

(101) Some of the panels were immersed in seawater in Sandefjord, Norway for 15 months whereupon they were washed with fresh water, left to dry at ambient temperature for 12 hours whereupon the silane terminated polyurethane containing polysiloxane coating was applied using an applicator giving a wet film thickness of 150 micrometers and left to cure for 24 hours at 23 C. and 70% humidity. These panels are called Old Sea Quantum Classic in the examples/Table 2.

(102) Panels Coated with SeaForce 60

(103) Steel panels were coated with Jotacoat Universal (with a wet film thickness of 220 micrometers and cured for 12 hours at 23 C. and 70% air humidity), followed by Safeguard Plus (with a wet film thickness of 180 micrometers and cured for 12 hours at 23 C. and 70% air humidity and SeaForce 60 (with a wet film thickness of 250 micrometers and cured at 23 C. and 70% air humidity). All coatings were applied using airless spray.

(104) After SeaForce 60 had dried for 2 days the silane terminated polyurethane containing polysiloxane coating was applied with an applicator with a wet film thickness of 150 micrometers and was left to cure at 23 C. and 70% humidity for 24 hours.

Example 1

Coating on an Epoxy Based Primer Layer

(105) The relative adhesion of a standard polysiloxane based coating compared to a coating comprising various amounts of a silane terminated polyurethane to two standard, commercially available epoxy based primers (Jotamastic 87 and Jotacoat Universal) was investigated. In general terms, X wt % SPU was mixed with 100-X wt % SeaLion Tie Coat. Different kinds of SPUs were used as indicated in Table 1.

(106) Adhesion results are shown in Table 1.

(107) TABLE-US-00001 TABLE 1 Relative adhesion of Tiecoat containing various amounts of silane terminated polyurethane (0-20 weight % relative to SeaLion Tiecoat component A). Adhesion Primer Primer silane terminated SPU Jotamastic Jotacoat Example polyurethane [wt. %] 87 Universal C1 SPUR 1015 LM 0 1 1 2 5 5 5 3 10 5 5 4 20 5 5 C2 Desmoseal S XP 2636 0 1 1 5 5 5 5 6 10 5 5 7 20 5 5 C3 Desmoseal S XP 2774 0 1 1 8 5 5 5 9 10 5 5 10 20 5 5 C4 PEIF 1199 0 1 1 11 5 5 5 12 10 5 5 13 20 5 5

Example 2

(108) Example 1 was repeated but applying the mixture to antifouling coatings. Results are presented in Table 2.

(109) TABLE-US-00002 TABLE 2 Relative adhesion of Tiecoat containing various amounts of silane terminated polyurethane (0-20 weight % relative to SeaLion Tiecoat Component A) Adhesion Amount Old SPUR SeaQuantum SeaQuantum SPU [wt. %] Classic SeaForce Classic SPUR 1015 LM 0 1 1 1 5 3 3 3 10 5 5 5 20 5 5 5

(110) Old SeaQuantum Classic means an object coated with SeaQuantum Classic which has been exposed to seawater for months, washed and thereafter applied a tiecoat as indicated.

(111) The addition of a silane terminated polyurethane (SPU) to a polysiloxane based coating increased the adhesion dramatically to standard epoxy primers. The commercially available standard fouling release coating based on polysiloxane (containing various amounts of SPU (5-20%)) shows good to strong adhesion to a standard hydrating and or hydrolyzing antifouling coatings as well. The hydrolyzing and hydrating antifoulings were freshly applied and the adhesion of the polysiloxane coating (with addition of SPU) should be even stronger if the substrate would have been exposed to normal marine conditions. Since adhesion of most polysiloxane coatings to most surfaces increase over time, overcoating a freshly applied antifouling coating should theoretically be more difficult that overcoating an old and worn coating.