CA1116770A

CA1116770A - Antifouling and antisliming coating material

Info

Publication number: CA1116770A
Application number: CA000323399A
Authority: CA
Inventors: David W. Marshall
Original assignee: Kennecott Copper Corp
Current assignee: Kennecott Corp
Priority date: 1978-03-15
Filing date: 1979-03-14
Publication date: 1982-01-19
Also published as: BR7901574A; ES478659A1; SE7902303L; GB2016474A; NL7902033A; JPS54129033A; DK106479A; FR2419965A1; IT1111999B; SE446008B; IT7920982A0; DE2910020A1; GB2016474B; PT69351A; US4197233A; JPS6224468B2; FR2419965B1

Abstract

ABSTRACT:
A polymeric composition containing copper flake in sufficient quantities to render the entire thickness of the polymeric composition electrically conductive. The copper flake is treated to remove oxides and reacted with conven-tional epoxy resins modified with an expoxidized polyol (polyglycol). The formulation not only exhibits outstanding antifouling properties but also exhibits antisliming prop-erties.
The composition is useful as a coating material and when utilized on ships, boats, and other water craft, a vessel results which requires no additional antifouling or antisliming treatment for several years. The composition can also be used to great advantage as a liner for pipes and conduits used to transport salt or fresh water where fouling of the pipes is a problem.
In one embodiment of the invention, a composition is disclosed which will cure under water. This particular formulation can be used to great advantage in patching holes in copper clad hulls and the like while the vessel is in water.

Description

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~ntifouling and antislimin~ coating material This invention relates to a method and composition for reducing fouling and sliming of submerged objec-ts or marine structures for extended periods of time.
The fouling of boat hulls and other objects immersed in sea water is a well-known problem. Fouling is a term used to described the damage caused by the growth of certain marine macro-organisms such as barnacles, mollusks, incrusting bryozoans, annelids, hydroides, algae, etc. It is well-known that these organisms are highly susceptible to copper.
]0 ~ccordingly, for centuries `sailing vessels have been clad with copper hulls. More recently copper has been applied to hulls in the form of paints, polymers, or copper containing polymers.
Perhaps the most common method of preventing the fouling of a boat hull, particularly on small crafts, is the use of antifouling paints. Such paints are applied to all surfaces of the hull in contact with water for any prolonged period of time. Indeed, even fiberglass hulls, which otherwise do not require painting, are normally painted at the beginning of each boating season with an antifouling paint on areas of the hull which will be in contact with water for long periods of time during the boating season. It would, of course t be highly desirable to provide a coating material for fiberglass hulls which is antifouling for several years. The pclymeric composition of the present invention can be utilized as such a coating material. ~ L

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In addition to beiny antifouling, the coa-ting material of the present invention also exhibits resistance to sliming.
Sliming is a term used to describe the opaque film which forms on the surface of submerged objects. Sliming is generally caused by micro-organisms such as bacteria.
Indeed, when a vessel is placed in salt water, initially bacteria becomes associated with the surface of the object to form a film of slime. The association of the bacteria is followed by an association of a biotic progression of diatoms, hybrides, algae, bryozoans, protozoans, and finally macro-organisms (foulants). It is desirable to reduce sliming for many reasons. Qbviously, the presence of slime contributes to problems associated with foulants such as increasing drag, increasing fuel consumption, etc. However, perhaps morè significant is the fact that macro-organisms tend to be rugophilic and set-tle on roughened surfaces in preference to smooth surfaces. Thus, ther~ ls a view that marine slimes precondition the surface o~ submerged objects in a manner that stimulates the settling of foulants. Thus, slime provides the physical substrate and possibly a nutrient source which encourages the attachment of macroscopic plants and animals. Obviously, it would be clesirable -to provide a material which not only pre~ents foulin~ but which also reduces sliminy. This fact is significant because antifouling paints are not generally characterized as being antisliming.
The conventional method of preventing sliming is to chemically treat the water, i.e., by chlorination or ozonation.
Of course, fouling and sliming is also a problem which occurs when objects are in con-tact with fresh water. Thus, the coating material of the present invention can be used to coat objects which remain in contact with fresh water for prolonged periods of time.
As has been stated above, a common procedure ~or preventing a boat hull from fouling is to apply an anti-fouling paint. Typically, an antifouling paint con-tains an antifouling metal such as copper which leaches into the water to Eorm copper ions. These ions are deadly to the foulants. As one particle of the antifouling metal dissolves, another particle is exposed to solvolysis. This leaching is rapid (when compared to the leaching rate of solid copper~
and varies with such factors as coating age, temperature of the water, salinity of the water, etc.
Quantltive information indicates that in most cases, initially the leaching rate of antifouling paints is exces-sive and results in overkill. Furthermore, the rapid leaching leads to the concentration of the toxic metallic components in quantities well above that normally present in the ocean. Of course, the longer the object to which the an-tifouling paint has been applied is in the water, the less I5 metallic material is available to prevent fouling.
Copper cladding on the other hand leaches copper ions very slowly. However, this slow leaching is still effective in killing foulan-ts. Furthermore, copper cladding is effect-ive as an antifoulant for many years. Indeed, it can be stated that antifoulants that leac:h slowly last longer. It would be highly desirahle to provi~e an antifouling coating material whi.ch has a slow leach rate. The coating material of the present inven-tion is such a material.
The present invention comprises a coating material which exhibits antifouling and antisliming properties com-prising a cured resin formed from an epoxy resin co-reacted with an epoxidized polyol and a curing agent, said cured resin containing copper flake, the copper flake being treated to remove impurities and oxides and being present in sufficient quantities so that the copper flake comprises 50 or more of the weight of the coating material.
The invention further comprises a marine structure having an antifouling and`antisliming coating consisting essentially of a cured resin formed from an epoxy resin co-reacted with an epoxidized polyol and a curing agent, said . .

cured resin containing copper flake, the copper flake being treated to remove-impurities and oxides and being present in sufficient quantities so that the copper flake comprises 50O
or more of the weight of the cured coating.
Still further the invention comprises a conduit for transporting fresh or salt water, the conduit being charac-terized by having a coating on surfaces which contact the water, the coa-ting being a cured epoxy resin containing copper flake, the copper flake being present in sufficient L0 quantities so that the copper flake comprises 50~ or more of the weight of the cured resin.
Most preferably the invention comprises a coating material which exhibits antifouling and antisliming proper-ties comprising a cured resin formed from bisphenol A type epoxy resin having a viscosi-ty less than 12,000 cps in the uncured state, co-reacted with an epoxidized polyol which is polypropylene glycol glycidyl ether having an epoxy equiva-lent weight of 100-500 and which comprises 5-30~ of the to-tal weight of the coating material and copper flake being treated to r~move impurities and c>xides, having a particle si.~e between the rancJe of 100-325 rnesh and which comp.rises S0~ or more of the weight of the coating material.
The coating material includes copper flake that has been treated to remove traces of copper oxide. A sufficient amount of copper flake is utilize~ so the entire thickness of the coating material is electrically conductive. The polymer which forms the coating material is a conventional epoxy resin modified with an epoxidized polyol. This formulation exhibits outstanding antifouling properties as well as antisliming properties when utilized as a coating material on an object in contact with water, especially sea water. The formulation is flexible, has excellent adhesive properties, contains no solvents, and can be either molded or spread as a coating. In one important embodi~ent of the invention, additives are included in the composition which permi-t the coating material to be cured under water. This 7~

embodiment has advantages when used to plug up holes in copper clad hulls and the like while the hulls are in water.
The coating material has a slow leach rate and when applied to a vessel will exhibit antifouling properties for many years.
Fig. 1 is a graph showing an infra-red analysis of two comnercial epoxidized polyols used as a modifier in the antifouling and antisliming formulations; curve labeled A is Dow Chemical's D.E.R. 732, curve B is Ciba-Geigy's Araldite 508;
Fig. 2 is a view of a concrete tunnel which is lined with an antifouling coating material of the present invent-ion;
Fig. 3 is a view of a boat hull which is coated with the antifouling coating material of the present invention;
Fig. ~l is a eross seetional view taken along line 4-~
of Fig. 3;
Fig. 5 is a view o~ a navigational buoy whieh is eoated with the antifouling coating material of the present inventi.on; and, Fiy. 6 is a eross seetiona:L v:iew taken along line 6-6 o ~ ~'iy . 5 .
~t the outset, the invention is described in its broad-est overall aspects with a more detailed description following.
The present invention relates to a composition which ean be applied as a eoating material. The eoating material has antifouling and antisliming properties; and thus, can be used as a coating for any surfaee on an object which is exposed to water, especially salt water, and whieh should have antifouling properties. In its broadest overall aspeet, the eoating material eomprises an epoxy resin con-taining a group such as a polyol which holds eopper flake and reIeases it slowly into the water.
In order for the eoating material of -the present invention -to be usable as an antifouling coating material, it is important that it contain a suffieient amount of .

copper Elake so that -the entire thickness of the coating material is electrically conductive. It is also important tha-t the copper flake be trea-ted or cleaned to remove impurities and/or oxides. Details of this treatment appear below and can also be found in U.S. Patent 3,983,075 to Marshall et al entitled "Copper Filled Conductive Epoxy", the teachings of which are incorporated herein by reference.
Copper flakes having a particle size of 30 to 200 ,~
microns are suitable for use in the coating material of the invention. Copper flakes such as Belmont Smelting and Refining Compan~'s No. 250 flake copper ( a 250 mesh approxima-tely 58 microns particle size copper flake with a purity of at least 99.99% copper) are mixed with enough of a solvent such as chlorinated alkylenes, e.g., trichloroethylene so that ei~ht volumes of a solvent are used per unit volume o~ flakes. Higher ratios can be used, (up to 12 volumes o~
solvent per unit volume of flakes); but, it has been found that generally sufficient cleaning is achieved by utilizing additional aliquot parts rather than employing greater amounts of the solvent. For example, by using a solvent Elake ratio of 5:1 and b~v repeating the process, it has been b Eound that the cLeaning action is enhanced.
The obtained mixture is stirred for about 1/2 hour and then filtered through an appropriate filter device such as a ;~
suchner funnel. After filtering, the flakes are rinsed in the funnel several times with denatured alcohol, methyl alcohol, or ethyl alcohol. After the first step, the copper flakes while still damp with alcohol are removed from the funnel and n~ixed with about 1 quart of 1 molar citric acid and stirred continuousl~ for a prolonged time, e.g., for about 12 hours. This mixture is again filtered in the funnel and rinsed thoroughly with distilled water until the rinse solution is clear. Again, the flakes are rinsed with 1.
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denatured alcohol and filtered to remove the excess fluid.
Drying of the damp copper flakes is carried out in a vacuum oven and generally a temperature of about 100F is employed.
It has been found that the flakes are dry and powdery after drying; but, it is important that these flakes be stored in a clean dry container until ready for use. It is also important that moist air be excluded from the storage vessel because of the tendency of copper to oxidize readily.
In general, epoxy resins (also called epiepoxide, and ethoxyline resins), are the condensation products of epichlorohydrin wi-th diphenols, such as bisphenol A, and have the structure shown below.

CH--CU<II ~ C~ocH2cu. ~-C-- ~IOCH2CH--C~2 The molecular wei~hts of these resins is between th~ range of 360-4000. The resins, in -the illustrated uncured state, are thermoplastic and range from low viscosity liquids (n=0) to high melting point brittle solids (n=10). An epoxy resin may be defined as a polyether containing a highly reactive epoxy or oxirane group at each terminal, separated by an ` alternating aromatic and aliphatic system containin~ i hydroxyl groups.
The epoxide group behaves as a highly unsaturated system and therefore, can react by addition with a wide variety of materials, especially those containing polar (active hydrogen) groups. Hence, except for being much more ~ reactive, the epo~y group acts in a manner very similar to i~
that of an olefin.
Epoxy resins usable in the present invention have a low viscosity, 100-20,000 cps, although resins having a viscosity less than 12,000 are preferred since they allow higher loadings of a filler material such as the copper flakes.

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: -S ~ J7,'3 Col~lercially availahle e~oxy resins suitable for use in the presen-t invention include:
Manufacturer Resin Name . . _ Ciba-Geigy Araldite*507 Araldite*502 Araldite*6004 Araldite 6005 Shell Chemical Epon*815 Epon*826 Epon 820 ~ .
Dow Chemical D.E.R.*334 D.E.R.*335 D.E.R.*321 !
D.~.R.*332 Celanese Epi-Res 504 Epi-Res 5077 -Epi-Res 5091 1~
General Mills Gen Epo~y*M170 Gen Epoxy*M189 Gen Epoxy*M245 Gen Epoxy 175 An important feature of the present invention is to include a reactive group such as a polyylycol ~polyol) in the cured epoxy resin which when in the presence o ~ater will react with copper to complex it. It is believed that this reactive ~roup is not compl~tely react~d with the epoxy resin and hence, some of the -OH groups are able to react with the copper flake in water to form either a basic cupric ~ I
carbonate CuCO3Cu(~H)2 or cupric butyrate Cu(C~H702)2 2H
or some other metal-organic compound which depends on the structure o~ the polyol. It is believed that the copper complex prevents sliming. At this point, it should be noted that the purpose of the polyol is to create a reaction product which inhibits slime formation. Polyols are desir- -able because they react easily with epoxy resins. Indeed, * Trade Mark ' ~i, , ,.-.

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7~ , epoxy resins containing polyols ]cnown as epoxidized polyols, are available commercially. A representative list of such epoxidized polyol resins appear below: a - Equivalent Manufacturer Trade Name Epoxy Weight I, Ciba-Geigy Araldite 508 ~00-~55 '`
Dow Chemical D.E.R. 732 305-335 .1 Dow Chemical D.E.R. 736 175-205 General Mills Gen Epoxy*G-192 175-205 General Mills Gen Epoxy*G-320 305-335 As used throughout this speciEication and claims, all percentages and parts are by weight unless otherwise speci-fied.
The equivalent epoxy weight is the weight of a molecule per reactive epoxy group. For example, if a resin contains a~

2 epoxy groups per molecule, the equivalent epoxy weight is the weight of the molecule divided by 2. As is known in ~, this art, the equivalent epo~y weight is utili.~ecl in order ti to ascertain the correct amo~lnt of curing agent.
The preEerred epo.xidized polyol resin is ~ralditc 508 which is an epoxy resin modif:ied with polypropylene cJlycol glycidyl ether. This resin has t.he following generalized ~orMula~
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CH2 - CH - CH2 -CH2-CH - 0- CH2- Cll- 0- CH2 _ CH - CH2 epoxidized n polyol where n is a nu~er between 2-7, the epoxidized polyol resin has a molecular weight between the range o~ 260-1000, and R
~ is hydrogen or an aliphatic hydrocarbon containing 1-6 - carbons.
As is well known, epoxy resins can be cured with amines, b amides, anhydrides, or catalytic agents such as boron tri-fluroide complexes and other Lewis acids.
The amine may be an aliphatic amine such as diethylene-triamine, diethylaminopropylamine, or triethylenetetramine. ~`

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~' Polyamides are also usable as curing agents. In general the ratio of the epoxy to the polyamide curative is 70 parts of epoxy to 30 parts of polyamide. However, ratios s as low as 50 epoxy to 50 polyamide and as high as 80 epoxy to 20 polyamide can be used.
More specific details on the curing agent appear below.-Aliphatic amines Triethylene Tetramine (TETA) is an aliphatic amine usually used in the ratio of 13 parts by weight to 100 parts resin. Other aliphatic amines such asdiethylenetriamine (D~TA) aminoethylethanolamine, tetrae-thylenepentamine, diethylaminopropylamine and the like would also be satisfactory. Proportions of amine to resin can st vary from about 4 phr to 30 phr dependiny on the particular 3 aliphatic amine chosen. Those that cure completely at room temperature such as TETA and DETA are used in proportions lcss thall 15 phr and are preferrecl since elevated temper- ~le atures are not need~cl to cure the r~sin and the volume o~
the curincJ agellt is not enou~h to cause excessive dilution of the copper filled resin. rrhe term "phr" lndi.cates parts 3`
per 100 parts resin. L
Ancamille 1510 is a modiEied cycloaliphatic amine made by Paci~i.c ~nchor Chem.ical Corporation. It has a very low viscosity (.5 centapoise) and results in a more fluid antiEouling compound. Similar cornpounds are Ancamine MCA and Ancamine 1561. Ancamine 1510 is recommended to be used at sS`
30 phr but may be used ~rom 20-40 phr with slightly reduced physical properties.
DMP-30 is the aroma-tic-ring-containing aliphatic tertiary amine, tris (dimethylaminomethyl) phenol. It is used in the range of 6 to 10 phr for room temperature cures with 10 phr being the preferred composition. Benzyldi- :
methylamine, ~ -methylbenzyldimethylamine and dimethy- k~
laminomethylphenol are acceptable substitutes.
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Because available epoxy rcsins modified wi-th glycols . f~
such as Araldite 508 tend to be soft when cured with an amine, it is advantageous to include an unmodified epoxy resin in the formulation. For e~ample, the resin D.E.R. 332 has been included in a formulation as follows:

Araldi~e 508 . 70g D.E.R. 332 30g TETA 13y .
Other additives include:
Epodil L which is a non-reactive liquid hydrocarbon . .. . . _ resin that is used primarily as a viscosity reducing diluent. It can be used up to 50% by weight with any resin, but the recommended range is 10-15% by weight. .
The polymeric composition is prepared in accordance with proceduxes tha-t are well known in this art. Prior to bein~ cured however, the copper Elake is added to the reactive mixture. Tests have indicated that -to be ef~ective as an antiouling coating, a coating material must con-tain at least 45~j and preferably 50g or more by wei~ht copper.
With this amount oE copper in the polymer, it would be electrically concluctive.
Curing agents would be used in their normal proportions which are readily available in the literature. Thus, for example, for an amine curing agent, the literature suggests using 2-50 parts of amine per 100 parts of an epoxy resin.
In ~eneral, the curing can be eEfected at room temperature or up to a temperature of 250F. A cure at room temperature is achieved at 70F or a cure period of 16 hours. Although .
the resins will harden within this time period, further f ; 30 curing will continue for several weeks or longer. Curing can be accelera-ted by adding small amounts of tertiary ff-amines or by heating to about 150F.
Anhydride cured resins are usually cured at a higher tèmperature such as for 2 hours at 200F plus an additional ; 35 ovcrnigh-t CUI e at 250F and a post cure of 4 hours a-t * Trade Mark .

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350F. It has been found, however, that short and lower temperature cure conditions reduce the possible oxidation of the flakes. At cure temperatures above 250F, the electrical conductance o~ the resin is impaired.
The invention is fur-ther illustrated by the following nonlimiting examples.
The use of copper filled electrically conductive epoxy resins as antifouling coatings in accordance with the present invention was tested. Initially, twelve formu-lations were coated on ~ inch by 6 inch fiberglass plates and placed in sea water tes-t racks at Woods Hole, Buzzards Bay, and Winthrop Harbor, Massachusetts. Seven of these L
initial twelve formulations showed significant fouling resistance and the best six were placed in new racks along with several other formulations.
The ~ormulations tested are listed in Table I.
Variations of resin type and copper content were evaluated.
~fter the first year o testing, i-t became apparent that copper contents of less than 35% were not antifouling and that ~5% copper was marginal in mos-t cases.
Flake size was also varied. A coarse Elake, U.S.
Bronæe's C-100 t~100 mesh), a Ei~e ~lake, USB 6500 (~,325 mesh), and a 50-50 mixture of the two were used in several different formulations. The USs 6500 and the blend were 2S tested for only one season, and no differences were appar-ent.
Table II summarizes the results of the three test sites. In general, the specimens at Mass. Maritime (Buzzards Bay) were not as heavily fouled as those a-t Woods Hole and Winthrop Harbor. The relative difference between specimens was the same`however (i.e., the least fouled at Mass. Maritime was the least fouled at the other sites).
There were differences in the fouling organisms at all three sites. Winthrop ~Iarbor fouled the racks heavily with mussels, a greenish sludge and numerous round jelly-like organisms. Woods l~ole fouled more heavily with algae, barnacles, and a flat jelly-like oryanism.

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Mass. Maritime had tube worms which were not present at either of the other two sites.
Two formulations looked particularly good after a two year exposure. They are formulations 3 and 4. Both contain 55% copper. Formula 3 showed moderate fouling at Winthrop Harbor after the second year but did not foul at either of the other two si-tes. At the Winthrop site, only the bottom 1/2 of the sample fouled significantly. The bottom 1/2 had previously been sanded to present a smoother surface. It is possible that the sanding smeared some of the resin over the exposed copper although no difference between top and bottom were noticed at the other test sites.
Formulation 4 showed no evidence of fouling at any of the test sites and also seemed to collect significantly less slime than the other formulations. This formulation is the only Eormulation that contains a polyglycol. Several other polyqlycol containing resins w~re made and after one fouling season they all remain unEouled and had very li-ttle slime.
Formulation 8 which was thinned to make a flowable system that could be painted or sprayed showed no Eouling after one year.
Substituting a conductive carbon black for copper in one oE the better anti~ouling formulations showed that the copper was essential. Formulation 18 containing only carbon black fouled heavily.
Long antlfouling life was expected for the formulations which show good electrical conductivity since this is taken to be an indication of particle to particle contact through- j out the thickness of the piece. The resistance of several formulations was measured prior to placing the samples at `the various test sites. The values are presented in Table III. There does not appear to be a direct correlation between conductivity and fouling resistance. However, there is a correlation between copper content and performance if the data in Table II is examined. It is likely that within a given copper fillcd formulation conduc-tivi-ty and foulirlg are related since in this case conductivi-ty is related to - copper content.

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There are 10 formulations which have shown no fouling t~
after one season of exposure at all three -test sites.

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7~ , TABLE I
Test Formulations Formulations Parts Varia-tions A _ _ ~

1) Araldite 507 100 - 100 100 100 ~`

USB C-100 138 92 61138 untreated ', 2) Araldite 6005 100 100 100 Ancamine 1510 30 30 30

3) Araldite 6005 100 100 100 Epodil L 15 15 15 TETA 13 13 13 ..
USB C-100 156 104 69 .
i 15 4) Araldite 508 100 Araldit~ 6005~2.8 ...
TETA 18.4 USB C-100 202.8 5) Araldite 6005 100 Thiokol LP-3 50 b~

* ` 1 6) Araldite 507 100 TETA . 13 . `
' 25 7) Araldite 507 100 100 U5B 6500 138138 un-treated * Trade Mark ~

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T~BLE I ~Con't) .Test Formulat.ions Formula-tions Parts Variations i, A B C

58) Araldite 507 100 ) TETA13~ Flowable USB C-100138~Formulation Methyl Alcohol80J

109) Araldite 507100) ~o alcohol wash TETA13~ used in treatin~
USB C-100138) the flake ~
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10) DER 332 100 ~ ~`
Epicure 807128 ~Cured *
Epic,ure 8744\ uncler~ater USB C-100 160) 11) DER 332 100 ) Araldite 85070~ Cured underwater .
USB C-100 flake 200 ) 2012) Araldite 508100 TETA 18 :

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`, TABLE I (Con '-t) , . Test Formulations Formulations Parts Variations A B C
i 15) DER 332 50 USB 6500 69 :~

10 16) Uncoated fiberglass r`

17) Devcon underwater curing Epoxy 18) Araldit~?*507 100 ~C 72R*Carbon 1.5 Black 51 1.9)~x~lcli~*507 100 ) ~ 2133(llcat: c:urecl , USB C-10063 ~syst:em USB 6500 63J . r;:
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20 20) Teflon sheet l:

; 21) Araldite 507100) Flattened under T~TA13~ a polyethylene sheet USB C-100144J to give a smooth surface ` 22) DER 332 50 DER 73250 Glycol containing Araldite 85070 underwater curing ~`
USB C-100200 resin * Trade Mark !:~

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USB C-100 and USB 6500 are -tradenames for copper flake.
sold by U.S. Bronze Corp. USB C-100 is a 100 mesh copper flake and US~ 6500 is a 325 mesh copper flake.

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TABLE III

Electrical Conductivities of Antifouling Formulations FormuIation No. *Resistance (ave. 3 values) I 0.3 ohms lC > 500 K

7 0.3 7A ~ lOOO K

9 - ' '0.5-. 1.2 O ll 50.0 12 1.2 *Between test probes a 3" span on actual test specimens.
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The foregoincJ tests indicate that in order for the coating material to be antifoulin~ it should con-tain 50% or more by weight of copper. A test sample with this amount of copper will have an electrical resistance of less than 50 ohms. The tests also indicate that only a coating material which contains a polyol has significant antisliming prop- ;~
erties. I
As has been stated above, one embodiment of the coating ~.
material of the present invention can be cured under water.
10 Details on this embodiment appear below.
An ordinary bisphenol A based epoxy resin is mixed with treated copper flake. The mix is then blended with a hard-ener which will cure underwater such as Ciba-Geigy's Hardner 850 or Celanese's Epicure 8071 and 874 (see test formulations 10 and 11)- The mixed resin is then placed on a plastic film such as polyethylene from which it can be transferred by a diver or sonte mechanical mechanism to the surface oE
the underwater object to be coatecl. ~E-ter a 24 hour cure, the polyethylene can be stripped away leavin~ the copper- ~ .
20 resin surface exposed.
~ glycol containing antisliming formulation is illus-trated in formulation ~22.
From the foregoiny it should be clear that ~n essenti.al requirement o the coating ma-terial oE the present invention 25 is that it comprise a cured epoxy resin containing 50% or more o~ copper ~lake which has been treated to remove copper oxides. It is preferable ~hat the copper flake be of the size between the range of 100-325 mesh tu.s. Sieve Series).
It is also preferable that the epoxy be a bisphenol A type 30 epoxy. For embodiments of the invention where antisliming properties are also desirable, a polyol is included in the epoxy formulation. In such cases, the polyol should comprise between 5-30 wei~ht percent of the total coating material, that is 5-30~ of the total weight of the resin, additives, 35 and the copper. It is also desirable that the polyol (poly-glycol) that is selected ~or inclusion in the epoxy resin be h such that the epoxy equivalent weight range o~ the polyol is between the range of lQ0-50Q.

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As has been stated above, the coating material of the present invention is utilized to provide antifouling prop-erties to water craft and conduits. The term "water craft"
is used in its broadest sense and is intended to cover any object which floats or is immersed in water. Thus, "water craft" is intended to cover stationary pilings for piers, buoys of all sizes as well as ship hulls. Likewise, the term "conduit" is intended to describe any tube or tubular structure. Thus, the coating material of the present inven-tion can be utilized to coat large tunnels used, for example,in nuclear power plants to conduct cooling sea water as well as the smallest tubing which might also be utilized to deliver sea water from one place to another.
An example of a utility intake tunnel is shown in Fig.
2. Such structures can be coated with a coating material in accordance with the present invention to make them anti-fouling. For example, a 6 foot diameter utility cooling water tunnel 10 ormed from concre-te 12 can be coated with coating material in accordance with the present invention.
To accomplish the Eoregoing, formulation 4 is applied to the tunnel lO by spra~ing it on the inside wall of ~he tunnel.
This technique is commonl~ used by boat manufacturers. Tl~e spraying woul~ be continued until a coating 14 approximately l/16th of an inch thick resulted.
Of course, smallèr conduits can be coated with the coating material of the present invention by techniques well `` known in t~his art. For fiberglass reinforced plastic piping, the coating màterial can be troweled onto the mandrel used to manufactuxe the pipe.
Fig. 3 shows a boat having a coating material in accord-ance with the present invention and Fig. 4 is a cross-sectional view taken along line 4-4 of Fig. 3. Referring more specifically to the drawing, the boat 2 in water 4 has a coating 6 of the coaking material of the present invention below the water line 8. The procedure for coating such a boat hull is similar to the procedure utilized for coating the intake -tunnel. In this case a formulation such as 77~

formulation 4 :is sprayed into a female mold. The bac~in~
resin is then put into the mold and the glass mat is applied to form the hull.
The present invention can be utilized to coat naviga-tional buoys as well as other floats. A significant problemwhich develops when navigational buoys are in the water for any prolonged period o~ time is that they become so fouled that they are weighted down to a point ~Ihere they must be removed from the wa-ter, scraped, and repositioned. This, of course, is an expensive operation. By coating navigational buoys and other floats with the coating material of the present invention, the buoys do not require tending as frequently as they would otherwise require. Fig. 5 shows a buoy having a coating material in accordance with the present I5 invention and Fig. 6 is a sectional view along line 6-6 of Fig. 5. ~eferring more specifically to Figs. 5 and 6, the buoy 2' in water 4' has a coatincJ 6' of a coating material in accordance with the present invention below the water line 8'. Such buoys can be made antifouling by either spraying or troweling the resin 6' and allowing it to cure over the substrate 11. Of course, because oE the high copper content of the coatiny mat:erial, it would not be applied direc~ly over steel, since this arrangement would produce galvanic action which would corrode the buoy.
5maller buoys and floats can be simply dipped into the ~ coating material ~efore it is cured and then allowed to - cure.
The invention ma~ be embodied in other specific forms without departing from the spirit or essential characteris-tics thereof. The present embodiments are therefore to beconsidered in all respects as illustrative and not restric-tive, the scope of the invention being indicated by the appended claims rather than by the foregoing descrip-tion, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced thcrein.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

Claims:

1. A coating material which exhibits antifouling and antisliming properties comprising a cured resin formed from an epoxy resin co-reacted with an epoxidized polyol and a curing agent, said cured resin containing copper flake, the copper flake being treated to remove impurities and oxides and being present in sufficient quantities so that the copper flake comprises 50% or more of the weight of the coating material.

2. The coating material as set forth in claim 1 where-in the cured resin is formed from an uncured epoxy resin having a viscosity less than 12,000 cps.

3. The coating material as set forth in claim 1 where-in the epoxidized polyol is present in sufficient quantities to comprise 5-30% of the total weight of the coating material

4. The coating material as set forth in claim 1 where-in the epoxidized polyol has an epoxy equivalent weight within the range of 100-500.

5. The coating material as set forth in claim 1 where-in the epoxy resin is a bisphenol A type epoxy resin.

6. The coating material as set forth in claim 1 where-in the particle size of the copper flake is between the range of 100-325 mesh.

7. The coating material as set forth in claim 1 where-in the epoxidized polyol which is co-reacted with said epoxy resin has the following generalized formula:
wherein n is a number between 2 and 7, and R is hydrogen or an aliphatic hydrocarbon containing 1-6 carbon atoms.

8. The coating material as set forth in claim 7 where-in the epoxidized polyol is a polypropylene glycol glycidyl ether.

9. The coating material as set forth in claim 1 where-in the cured resin is formed with a curing agent which cures underwater.

10. The coating material as set forth in claim 1 where-in said resin is applied to a marine structure.

11. The coating material as set forth in claim 10 where-in the marine structure is a boat hull.

12. The coating material as set forth in claim 10 wherein the marine structure is a navigational buoy.

13. The coating material as set forth in claim 10 where-in the marine structure is a float.

14. The coating material as set forth in claim 1 where-in said resin is applied to a conduit for transporting fresh or salt water, the coating being applied on surfaces which contact the water.

15. A coating material which exhibits antifouling and antisliming properties comprising a cured resin formed from a bisphenol A type epoxy resin having a viscosity less than 12,000 cps in the uncured state, co-reacted with an epoxi-dized polyol which is polypropylene glycol glycidyl ether having an epoxy equivalent weight of 100-500 and which comprises 5-30% of the total weight of the coating material, and copper flake being treated to remove impurities and oxides, having a particle size between the range of 100-325 mesh and which comprises 50% or more of the weight of the coating material.