CA1192329A - Organotin polysiloxane and acrylic antifouling coating - Google Patents
Organotin polysiloxane and acrylic antifouling coatingInfo
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- CA1192329A CA1192329A CA000413264A CA413264A CA1192329A CA 1192329 A CA1192329 A CA 1192329A CA 000413264 A CA000413264 A CA 000413264A CA 413264 A CA413264 A CA 413264A CA 1192329 A CA1192329 A CA 1192329A
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Abstract
Abstract of the Disclosure A marine antifouling coating composition comprises an acrylic resin such as methyl methacrylate in the range of from 6 to 20% by weight, a polysiloxane having substituted thereon tributyltin moieties that are toxic to marine organisms. The polysiloxane is in the range of from 7 to 25% by weight. The acrylic resin and polysiloxane are dissolved in a solvent in the range of from 18 to 52% by weight with the balance of the composition in the range of from 10 to 65% by weight being primarily conventional marine paint and toxicant agents for augmenting action of the tributyltin polysiloxane. Copper or copper salts that are effective for inhibiting growth of marine organisms and facilitating release of toxins can also be included.
Description
23~
13790:RDS -1-ORGANOTIN POLYSILOXANE AND ACRYLIC
ANTIFOULING COATING
Field of the Invention This invention relates to marine antifouling coating cQmpositions including an acrylic resin and a trisubstituted or~anotin substituted polysiloxane in a paint ~ixture. Preferably, the compositions also include copper or a copper salt :l~or inhibiting marine ~ouling.
Back~round When a ship moves through the water the drag : resistance or watex frictional forces which must be : overcome are responsible for as much as hal of the power consumed in operation of the vessel. The surface condition of ~he hull is a major factor inducing drag~ It is therefore desirable to have an extremely smooth surface on the hull and paint formulations have been developed that are vçry smoo~h when cured and/or are polished by moving water to ~: 30 pxo~ide an extremely smooth surface. It is desirable to have a coating material that exhi~its this polishing action to produce a microsmooth surlace to minimize the drag penalty due to microroughness.
~ I
3~2~
1 Fouling of the hull by pestiferous marine organisms is a major source o~ drag. The use of antifouling protective coatings on a ship's hull is a primary approach to controlling fouling and the resulting drag. The antifouling coating inhibits growth o~ marine organisms on the hull ~o keep it smooth. Coatings can also be used on static structures exposed to seawater to minimize growth of organisms that could cause deterioration of such structures.
A trul~ ef~ective an~ifouliny coating meets at least three criteria: ~1) It will possess broad spectrum antifouling effi~acy (i.e., inhibit yrowth of a bxoad varie~y of organisms) for extended periods of time, usually thxee years; ~2) it will possess a smooth surface so as not to cause a microroughness drag penalty; and (3) it will actively reduce drag by reduciny the roughness profile of the sur~ace.
To meet the first criterion it is necessary to deliver ~o the surface of the coating in a controlled fashion~ minimum ef~ective amounts of ~oxin or fouling control agents. The amount of toxin delivered at the surface should no~ be substantially above the minimum effective amoun~ for inhibiting fouling to avoid premature depletion of the antifouling agent.
One technique for controlling release of toxin involves khe use o~ latent toxicants which are activated by an environmental or chemical trigger such as hydrolysis.
This is the principle behind the operation of organotin polysiloxane materials as described in U. S. Pa ent No. 4,080,190. In these materials a trisubstituted organotin moiety is chemically bonded ~o a macromolecular 3~
1 polysiloxane backbone. Through hydrolysis the organokin moiety is gradually liberated and diffuses to the surface of the coating as the active fouling control agent.
The organotin polysiloxane materials can act as binders, co-resins, or toxic pigments or additives depending on the tin to silicon ratio and related physical form. A low tin to silicon ratio permits the organotin polysiloxane to perform as a binder.
Such material is primarily inorgarlic in nature though ~he presence o~ the organotin groups do impart a certain degree o~ organic character. This enhances ccmpatability with organic materials and better adhesion to me~al substrates, for example, than a polysiloxane wi~hout organotin substitution.
As a binder the organotin polysiloxane can serve as a matrix for essentially inorganic fillers and pigments. The coating is microporous allowing con~inual release o~ the toxic agent; that is, an organotin radical is formed in situ through hydrolysis ~f the tin-oxygen-sili¢on bond. Such continual release of t~xicant avoids surface passivation as frequently occ~rs in conventional copper ~ased antifouling coatings.
Since this kype of formulation is microporous, performance is essentially independent of turbulence;
that is, sufficient toxicant is l~ached to the surface for preventing fouling under either static or dynamic conditions.
With a higher tin to silicon ratio the organotin polysiloxane can be an additive in a coating composition using a vari~ty of binders. In such a composition the release of toxicant is a function of the properties of the binder plus hydrolysis characteristics of the organo~in polysilo-xane.
srief Sun~ary of the Invention In accordance with the present invention there is provided a marine antifouling coating composition comprisi~g:
an acrylic resin selected ~rom the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate in the range of fxom 6 to 20 percent by weight;
an organotin polysiloxane having the formula rO X I
I
X-O- - si - o- -x O - X m where m is an average of up to about ten, each X is independently selected from the gxoup consisting of R and Y; where each R is selected fro~ the group consi sting of hydrogen and alkyl and alkoxyalkyl radicals containing less than six carbon atoms;
where each Y is a trisubstituted tin radical having the formula Rl _ f n R3 where Rl, R2, and R3 are independently selected from the group co~lsisting of alkyl, cycloalkyl and aryl radicals and Rl, R2, and R3 contain collectively up to 18 carbon atoms; and the X's aLe selected so that the ra~io of tin atoms to silicon atoms is in the range of from 0.7:5 to 5:5~ the organotin polysiloxane being in the range of from 7 to 25 percent by weight;
solvent for the acrylic resin and polysiloxane in the range o~ from 18 to 52 percent by weight; and 3~
- 4a a balance in the range of from 10 to 65 percent by weight of primarily marine paint and toxicant agents selected from the group consisting of pigment powders, fillers, thicken.ing agents, antisettling agents, copper powder, cuprous salts, zinc oxide, algicides, silica, clay, talc, metal oxides, plasticizers and slightly water soluble resins.
3~
1 Description The marine antifouling coating composition provided in practice of this invention comprises a mixture of resins or binders, solvent and pigments or fillers, along with associated marine paint and antiouling ingredients in a consistency suitable as a paint for brushing, spraying, or the like on ship hulls or o~her s~ructures exposed to seawater.
~he binders in the composition comprise an acrylic resin in the range of from about 6 to 20% by weight and an.organotin substituted polysiloxane in the range of from ahout 7 to 25% by weight. A volatile organic solvent for the acrylic resin and polysiloxane is preferably present in the range of from about 18 to 52% by wPight. The balance of the composition in ~he range of from about 10 to 65% ~y weight comprises conventional plasticizers, a small amount o~ water soluble resin, pigment powders, fillers, thickening agents, antisettling agents, copper powder, copper salts, zinc oxide, algicides, clay, talc, metal ~xides and the like.
It is particularly desixable that the composition include coppex powder or cuprous salts that are effective for inhibiting growth of marine organisms. ~he combination of organo~in polysiloxane, acrylic xesin and copper supplying antifouling agent appears to avoid passivation of the copper bearing antifouling agent which of~en occurs in seawatex. Preferably the copper or c-lprous salt is present in a proportion of up to about 30% by w~ight.
1 The acrylic resin is selected from the group consisting oE methyl methacrylate, ethyl methacrylate, propyl methacryla~e, isobutyl methacrylate, and n-butyl methacrylate. Such materials can be used separa~ely or as polymer blends. Preferably the acrylic resin is pol~methyl methacrylate since economical, readily commercially available, and an excellent resin for marine coatings. The methyl methacrylate forms a microsmooth coating and has appropriate charac~eristics in moving seawater to maintain a low drag profile on a vessel.
The acrylic resin is present in the composition in the range of from about 6 to 20% by weight. If the acrylic resin is present in a proportion less than about 6% by weight, adhesion o~ the coating to metal substrates can ~e excessively degraded. Further, the microsmoothness and ablation characteristics of the resultant coating may not be adequate for minimizing drag when used on a ship or ~he like. If the proportion of acrylic resin is more than about 20~ by weight, the amount of polysiloxane in the composition may need to ~e re~uced to a level that the antifouling proper~ies of the coating are degraded.
Prefera~ly the acrylic resin is present in the range of ~rom about 8 to 12% by wei~ht. Such proportions are found to give an excellent balance of adhesion of the coating composition ~o a variety of substrates, microsmoothness and ablation characteristics suitable for reducing drag and lon~ life as an antifouling coating. A particularly preferred composition has fxom about 10 to 11% by weight of aarylic resin.
3~
1 The organotin polysiloxane comprises a polymeric pxecursor having the formula O - X ~
X ~ ~ Si ~ 0- - X
O ~X
m where m is in the xange up to an average of about 10 and preferably is an average of at least about 5. In this formula each X is independently selected from the group consis~ing of R and Y. Each R is selected fr~m the group consisting of hydrogen, and alkyl and alkoxyalkyl radicals containing less ~han six carbon atoms~ Each ~ in the formula is a trisubstituted organotin radical having the formula:
~2 Rl - Sn -In this organotin moiety Rl, R2 and R3 are independently selected from the gro~p consisting of alkyl 9 ~ycloaklyl, and aryl radicals and collectively contain up to about 18 carborl atoms. Preferably Rl, R~ and R3 are each butyl for optimum toxicity of the composition to marine organisms. Triphenyl tin polysiloxane can be substituted or some of the tributyl tin siloxane in some embodi~ents.
Pre~era~ly the R radical on the polysiloxane is ethyl. When the silox~ne is polymerized by hydrolysis and condensation, the rea~tion by-product is ethyl alcohol ~.~Lg23~
1 which has a volatility similar to the organic solvents in the composition, thereby making the composition readily applicable as a paint. If desired, the polysiloxane can be prehydrolyzed when making up tne composition to speed polycondensation in which cas~ at least a portion of R is hydrogen. Such prehydrolysis can reduce the shelf li.fe of the composition~
Such organotin polysiloxane and methods for making them are described in U. S. Paten~ No. 4,080,190, In the polysiloxane m represents the average number of silicon atoms per molecule. Generally there is a random distribution of molecules having more or less than m silicon atoms. For example, when m = 5, molecules containing 4, 5 and 6 silicon atoms can be present. Preferably, m is less than about 10 so that the siloxane can ~e properly poly~erized by hydrolysis and polycondensation during curing of the coating composition. Preferably m is an average of about 5. Such a polysiloxane can pol~merize, following transesterification to in~roduce the organotin moiety, to produce linear and/or crosslinked polymers. Such material has a high silica content, hence a relatively high proportion of solid binder following polycondensation and removal of the preferred ethyl radical.
The X ' 5 in the formula are selected so that the ratio of tin atoms to silicon atoms in the organotin polysiloxane is in the range of from about 0.7:5 to 5:5.
'~
~3~3~1 1 If the ratio of tin atoms to silicon atoms in the composition is less than about 0.7 tin atoms for every 5 silicon atoms, the quantity of the trisubstituted tin moiety can be so low that toxicity of the coating to marin~ organisms is marginal. When the tin ~o silicon ratio is low, extensive cross-linking of the polysiloxane can be obtained so that the polysiloxane forms a durable binder in the coating composition. This permits a higher proportion of polysiloxane and a lower proportion of acrylic resin in the composition without degrading the desired mechanical properties of the xesultant coating.
The proportion of tin atoms to silicon atoms should be less than about 5:5 for polymerization of the polysiloxane. The tris~bstituted tin moiety on the polysiloxane introduces sufficient steric hindrance that at high ~in to silicon ratios cross-linking is inhibited. Thus, with high tin to silicon ratios, the mechanical ~rope~ties of the polymerized siloxane are redu~ed. In such an embodimen the proportion of acrylic xesin to polysiloxane is increased for maintaining the mechanical properties of the coating. At high tin to silicon ratios in the polysiloxane, conventional plas~icizers may be omitted as the polysiloxane ~lend with the acrylic resin can provide sufficient plasticizing.
Preferably, the tin to silicon ratio in the polysiloxane is in the range of from about l.3:5 to 2.5:5. A particularly preferred composition has a ratio of tin atoms to silicon atoms of about
13790:RDS -1-ORGANOTIN POLYSILOXANE AND ACRYLIC
ANTIFOULING COATING
Field of the Invention This invention relates to marine antifouling coating cQmpositions including an acrylic resin and a trisubstituted or~anotin substituted polysiloxane in a paint ~ixture. Preferably, the compositions also include copper or a copper salt :l~or inhibiting marine ~ouling.
Back~round When a ship moves through the water the drag : resistance or watex frictional forces which must be : overcome are responsible for as much as hal of the power consumed in operation of the vessel. The surface condition of ~he hull is a major factor inducing drag~ It is therefore desirable to have an extremely smooth surface on the hull and paint formulations have been developed that are vçry smoo~h when cured and/or are polished by moving water to ~: 30 pxo~ide an extremely smooth surface. It is desirable to have a coating material that exhi~its this polishing action to produce a microsmooth surlace to minimize the drag penalty due to microroughness.
~ I
3~2~
1 Fouling of the hull by pestiferous marine organisms is a major source o~ drag. The use of antifouling protective coatings on a ship's hull is a primary approach to controlling fouling and the resulting drag. The antifouling coating inhibits growth o~ marine organisms on the hull ~o keep it smooth. Coatings can also be used on static structures exposed to seawater to minimize growth of organisms that could cause deterioration of such structures.
A trul~ ef~ective an~ifouliny coating meets at least three criteria: ~1) It will possess broad spectrum antifouling effi~acy (i.e., inhibit yrowth of a bxoad varie~y of organisms) for extended periods of time, usually thxee years; ~2) it will possess a smooth surface so as not to cause a microroughness drag penalty; and (3) it will actively reduce drag by reduciny the roughness profile of the sur~ace.
To meet the first criterion it is necessary to deliver ~o the surface of the coating in a controlled fashion~ minimum ef~ective amounts of ~oxin or fouling control agents. The amount of toxin delivered at the surface should no~ be substantially above the minimum effective amoun~ for inhibiting fouling to avoid premature depletion of the antifouling agent.
One technique for controlling release of toxin involves khe use o~ latent toxicants which are activated by an environmental or chemical trigger such as hydrolysis.
This is the principle behind the operation of organotin polysiloxane materials as described in U. S. Pa ent No. 4,080,190. In these materials a trisubstituted organotin moiety is chemically bonded ~o a macromolecular 3~
1 polysiloxane backbone. Through hydrolysis the organokin moiety is gradually liberated and diffuses to the surface of the coating as the active fouling control agent.
The organotin polysiloxane materials can act as binders, co-resins, or toxic pigments or additives depending on the tin to silicon ratio and related physical form. A low tin to silicon ratio permits the organotin polysiloxane to perform as a binder.
Such material is primarily inorgarlic in nature though ~he presence o~ the organotin groups do impart a certain degree o~ organic character. This enhances ccmpatability with organic materials and better adhesion to me~al substrates, for example, than a polysiloxane wi~hout organotin substitution.
As a binder the organotin polysiloxane can serve as a matrix for essentially inorganic fillers and pigments. The coating is microporous allowing con~inual release o~ the toxic agent; that is, an organotin radical is formed in situ through hydrolysis ~f the tin-oxygen-sili¢on bond. Such continual release of t~xicant avoids surface passivation as frequently occ~rs in conventional copper ~ased antifouling coatings.
Since this kype of formulation is microporous, performance is essentially independent of turbulence;
that is, sufficient toxicant is l~ached to the surface for preventing fouling under either static or dynamic conditions.
With a higher tin to silicon ratio the organotin polysiloxane can be an additive in a coating composition using a vari~ty of binders. In such a composition the release of toxicant is a function of the properties of the binder plus hydrolysis characteristics of the organo~in polysilo-xane.
srief Sun~ary of the Invention In accordance with the present invention there is provided a marine antifouling coating composition comprisi~g:
an acrylic resin selected ~rom the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate in the range of fxom 6 to 20 percent by weight;
an organotin polysiloxane having the formula rO X I
I
X-O- - si - o- -x O - X m where m is an average of up to about ten, each X is independently selected from the gxoup consisting of R and Y; where each R is selected fro~ the group consi sting of hydrogen and alkyl and alkoxyalkyl radicals containing less than six carbon atoms;
where each Y is a trisubstituted tin radical having the formula Rl _ f n R3 where Rl, R2, and R3 are independently selected from the group co~lsisting of alkyl, cycloalkyl and aryl radicals and Rl, R2, and R3 contain collectively up to 18 carbon atoms; and the X's aLe selected so that the ra~io of tin atoms to silicon atoms is in the range of from 0.7:5 to 5:5~ the organotin polysiloxane being in the range of from 7 to 25 percent by weight;
solvent for the acrylic resin and polysiloxane in the range o~ from 18 to 52 percent by weight; and 3~
- 4a a balance in the range of from 10 to 65 percent by weight of primarily marine paint and toxicant agents selected from the group consisting of pigment powders, fillers, thicken.ing agents, antisettling agents, copper powder, cuprous salts, zinc oxide, algicides, silica, clay, talc, metal oxides, plasticizers and slightly water soluble resins.
3~
1 Description The marine antifouling coating composition provided in practice of this invention comprises a mixture of resins or binders, solvent and pigments or fillers, along with associated marine paint and antiouling ingredients in a consistency suitable as a paint for brushing, spraying, or the like on ship hulls or o~her s~ructures exposed to seawater.
~he binders in the composition comprise an acrylic resin in the range of from about 6 to 20% by weight and an.organotin substituted polysiloxane in the range of from ahout 7 to 25% by weight. A volatile organic solvent for the acrylic resin and polysiloxane is preferably present in the range of from about 18 to 52% by wPight. The balance of the composition in ~he range of from about 10 to 65% ~y weight comprises conventional plasticizers, a small amount o~ water soluble resin, pigment powders, fillers, thickening agents, antisettling agents, copper powder, copper salts, zinc oxide, algicides, clay, talc, metal ~xides and the like.
It is particularly desixable that the composition include coppex powder or cuprous salts that are effective for inhibiting growth of marine organisms. ~he combination of organo~in polysiloxane, acrylic xesin and copper supplying antifouling agent appears to avoid passivation of the copper bearing antifouling agent which of~en occurs in seawatex. Preferably the copper or c-lprous salt is present in a proportion of up to about 30% by w~ight.
1 The acrylic resin is selected from the group consisting oE methyl methacrylate, ethyl methacrylate, propyl methacryla~e, isobutyl methacrylate, and n-butyl methacrylate. Such materials can be used separa~ely or as polymer blends. Preferably the acrylic resin is pol~methyl methacrylate since economical, readily commercially available, and an excellent resin for marine coatings. The methyl methacrylate forms a microsmooth coating and has appropriate charac~eristics in moving seawater to maintain a low drag profile on a vessel.
The acrylic resin is present in the composition in the range of from about 6 to 20% by weight. If the acrylic resin is present in a proportion less than about 6% by weight, adhesion o~ the coating to metal substrates can ~e excessively degraded. Further, the microsmoothness and ablation characteristics of the resultant coating may not be adequate for minimizing drag when used on a ship or ~he like. If the proportion of acrylic resin is more than about 20~ by weight, the amount of polysiloxane in the composition may need to ~e re~uced to a level that the antifouling proper~ies of the coating are degraded.
Prefera~ly the acrylic resin is present in the range of ~rom about 8 to 12% by wei~ht. Such proportions are found to give an excellent balance of adhesion of the coating composition ~o a variety of substrates, microsmoothness and ablation characteristics suitable for reducing drag and lon~ life as an antifouling coating. A particularly preferred composition has fxom about 10 to 11% by weight of aarylic resin.
3~
1 The organotin polysiloxane comprises a polymeric pxecursor having the formula O - X ~
X ~ ~ Si ~ 0- - X
O ~X
m where m is in the xange up to an average of about 10 and preferably is an average of at least about 5. In this formula each X is independently selected from the group consis~ing of R and Y. Each R is selected fr~m the group consisting of hydrogen, and alkyl and alkoxyalkyl radicals containing less ~han six carbon atoms~ Each ~ in the formula is a trisubstituted organotin radical having the formula:
~2 Rl - Sn -In this organotin moiety Rl, R2 and R3 are independently selected from the gro~p consisting of alkyl 9 ~ycloaklyl, and aryl radicals and collectively contain up to about 18 carborl atoms. Preferably Rl, R~ and R3 are each butyl for optimum toxicity of the composition to marine organisms. Triphenyl tin polysiloxane can be substituted or some of the tributyl tin siloxane in some embodi~ents.
Pre~era~ly the R radical on the polysiloxane is ethyl. When the silox~ne is polymerized by hydrolysis and condensation, the rea~tion by-product is ethyl alcohol ~.~Lg23~
1 which has a volatility similar to the organic solvents in the composition, thereby making the composition readily applicable as a paint. If desired, the polysiloxane can be prehydrolyzed when making up tne composition to speed polycondensation in which cas~ at least a portion of R is hydrogen. Such prehydrolysis can reduce the shelf li.fe of the composition~
Such organotin polysiloxane and methods for making them are described in U. S. Paten~ No. 4,080,190, In the polysiloxane m represents the average number of silicon atoms per molecule. Generally there is a random distribution of molecules having more or less than m silicon atoms. For example, when m = 5, molecules containing 4, 5 and 6 silicon atoms can be present. Preferably, m is less than about 10 so that the siloxane can ~e properly poly~erized by hydrolysis and polycondensation during curing of the coating composition. Preferably m is an average of about 5. Such a polysiloxane can pol~merize, following transesterification to in~roduce the organotin moiety, to produce linear and/or crosslinked polymers. Such material has a high silica content, hence a relatively high proportion of solid binder following polycondensation and removal of the preferred ethyl radical.
The X ' 5 in the formula are selected so that the ratio of tin atoms to silicon atoms in the organotin polysiloxane is in the range of from about 0.7:5 to 5:5.
'~
~3~3~1 1 If the ratio of tin atoms to silicon atoms in the composition is less than about 0.7 tin atoms for every 5 silicon atoms, the quantity of the trisubstituted tin moiety can be so low that toxicity of the coating to marin~ organisms is marginal. When the tin ~o silicon ratio is low, extensive cross-linking of the polysiloxane can be obtained so that the polysiloxane forms a durable binder in the coating composition. This permits a higher proportion of polysiloxane and a lower proportion of acrylic resin in the composition without degrading the desired mechanical properties of the xesultant coating.
The proportion of tin atoms to silicon atoms should be less than about 5:5 for polymerization of the polysiloxane. The tris~bstituted tin moiety on the polysiloxane introduces sufficient steric hindrance that at high ~in to silicon ratios cross-linking is inhibited. Thus, with high tin to silicon ratios, the mechanical ~rope~ties of the polymerized siloxane are redu~ed. In such an embodimen the proportion of acrylic xesin to polysiloxane is increased for maintaining the mechanical properties of the coating. At high tin to silicon ratios in the polysiloxane, conventional plas~icizers may be omitted as the polysiloxane ~lend with the acrylic resin can provide sufficient plasticizing.
Preferably, the tin to silicon ratio in the polysiloxane is in the range of from about l.3:5 to 2.5:5. A particularly preferred composition has a ratio of tin atoms to silicon atoms of about
2.5:5. A composition having a ratio of about 1.3 tin atoms or every 5 silicon atoms in the polysiloxane 1 fonms an excellent binder for the coating composition with sufficient trisubs~ituted organotin moiety for high toxicity of marine organisms. Such a composition can ~e useful where a durable antifouling coating is desired with low polishing action. In such an embodiment a relatively higher proportion of polysiloxane and relatively lower proportion of acrylic resin ~ay be used in the composition~ A
particularly preferred composition has a ratio of 10 a~out 2.5 tin atoms per 5 silicon atoms. Such matexial is not c~mpletely cross-linXed and serves to modulate ~he properties of the acrylic resin in the coating composition. ~ high proportion of tin moiety is present in the composition providing 15 long life antifouling characteristics. Such a material has about the optimum balance of mechanical propexties and toxicity.
It will ~e recognized that the quantity of organotin polysiloxane binder in the composition 20 following hydrolysis and condensation will be 12ss than the proportion of oxganotin siloxane in the uncured coating composition. For example, when the organo~in siloxane comprises a tributyl tin moiety on an ethoxy siloxane whereill each molecule Z5 has an average of five silicon at~ms and the ratio of tin atoms to silicon atoms is about 2.5:5, the cured siloxane has about 73~ of the weigh~ of the uncured pr~cursor. ~he weight loss comes about from loss of the ethyl radical upon hydrolysis and 30 con~ensation, ~2~
l The acrylic resin and organotin polysiloxane in the sompositlon act as co-resins forming a binder for a paint coating. Evaporation of the solvent from the composition and exposure of the composition to en~ironmental water or water vapor results in solidification of the binder blend through deposition of the acrylic resin and concurrent hydrolytic polycondensation of the siloxane. Depending on the proportions of the materials, this binder system can be in the orm of a resin blend or an intexpenetrating pol~mer network.
Preferably the organotin polysiloxane is present in thP composition in the range of from about 7 to 25~
by weigh~. If the proportion is less ~han about 7~ by weight, the quantity ~f the organotin moiety can become so low that the antifouling characteristics of the co~position can be ~oo low fox practical use.
The rate of release of toxicant at the coating suxface can be less than the minimum required for inhibiting growth of organisms.
If the proportio~ of organotin polysiloxane in the composition is more than about 25% by weight, the mechanical properties of the organotin polysiloxane can predominate over those o the acrylic resin, ~5 thereby reducing the desirable properties of the acrylic. Further, high proportions of organotin polysiloxane can reduce the content of other toxicants such as copper bearing antiouling agents, thereby narrowing the spectrum of organisms agains~ which the antifouling coating is e~ective.
~3~3~
1 Preferably the oryanotin polysiloxane is present in the cQmposition in the range of from about 12 to 16~ by weight. This gives a good halance of the antifouling proper~ies of the siloxane and the mechanical properties of the acrylic.
Such a coating has a long useful lifetime in bo~h static and dyn~nic fouling control situations.
Preferably the quantity o~ organotin polysiloxane is somewhat larger than the proportion of acrylic resin in the composition. Preferably the weight ratio of acrylic resin to organotin polysiloxane is in the range of from about 0.5 to 1.0 and most particularly in ~he range of ~rom about 0.6 to 0.8. These provide optimum balance of an~ifouling characteristics in the combination of controlled release of toxicant and mechanical properties in ~he resultant coating.
As co-resins in the binder system the organotin polysiloxane moderates the physical properties of the acrylic resin. Ordinarily, a polysiloxane is incompatible with an acrylic resin, however, it is found that th p~esence of the trisubstituted organotin moiety on the polysiloxane makes the two types of ~inder compatible so ~hat a coating composition with Z5 reasonable shelf life can he formulated.
In the cured composition, the acrylic in the binder provides a microsmooth surface that minimizes microroughness drag penalty, and a slow controlled poiishing action can be obtained for providing m~ximum reduction of drag. In the preferred embodiment of this invention, the surface profile roughness envelope is in the 15 to 25 micron range throughout the ser~ice life of the coating and its ablation rate is less ~ha~ 3 microns o coa ing loss per month at a speed of 15 kno~s. T~e organotin moiety in the 1 binder is released at a controlled rate since it is chemically bonded to a polymeric content of the coa~ing and is not free to migrate or diffuse before hydrolysis frees the tin moiety from the.polysi.loxane.
S In other compositions in which an acrylic resin is used as binder and antifouling agen~s are included as addLtives, such as cuprous salts or tributyltin oxide, the toxicant is released at a rate controlled only by matrix properties. Since diffusion rate depends on concentration, release of toxicant at the surface is relatively high when ~he coating is fresn and diminishes steadily thereafter. To maintain an effective release rate at the surface after a long time, an excessive release rate is needed in the beginning.
.... _ . . , . _ . .. . _ _ .. . . .. . .. .... . .. . . . .. _ .. _ .. _ . . . .. . _ _ . .. . . _ .
In a composition with organotin polysiloxane and acryllc resin, release of toxicant occurs upon hydrolysis of the tin-oxygen-silicon bond. The rate ~o~ release is thus~control~ed by the rate of hydrolysis which r~mains steady throughout the life of the çoating. Since the xate of release is nearly constant~
the amount of toxicant ~an be selected to provide slightly more than an efestive amount at the projected end of the useful li~e of the coating. Little excess toxi~ant is released during the early lifP of the coating and longer life can ~e ob~ained fQr a selec~ed total amount of toxicant.
An or~anic solvent for the acxylic resin and organotin polysiloxane is preerably present in the range of from about 18 to 52% by wei~ht. Xylene is an excellent solvent for both the acrylic resin and ~23%~
l polysiloxane. In an exemplary embodiment acrylic resin is included in the composition by way of a commercially available solution of acrylic resin and -toluene. In such an embodiment the solvent in the composition compri.ses a blend of toluene and xylene. Other nonpolar solvents for acxylic resin and polysiloxane can also be used, along with limited amounts of alcohols. Exemplary solvents are xylene, toluene, various Cellosolves,* naphtha and mineral spirits. The organic solvents should be selected to provide 2 volatility that permits drying of the coating composition in a reasonable time when applied to the hull of a vessel or other substrate.
The proportion of solvent in the composition is subject to rather wide variation and is determined largely by the desired viscosity in the composition to permit application to substrates by spraying, brushing, or the like. If the ~roportion of solvent is less than about 18% by weight, the viscosity of the composition may be so high that application to substrates in coatings of reasonable thickness is rather di.fficult. Levelling to obtain a smooth coating may also be inhibite~. If the composition has more than about 52% by weight of solvent, application of coatings of reasonable thickness can be limited by sagging or running. Preferably, the solvent is present in the range of from abou-t 24 to 36% by weight. It is found that such a proportion of solvent with the preferred resin compositions and other marine paint additives hereinafter described provides a viscosity range quite suitable for application to substrates by brushing and/or spraying.
* Cellosolve is a trademark of Union Carbide Corporation.
1 A variety of other ingredients can form the balance of the composition in the range of ~rom ahout 10 to 65~ by weight. Such additional ingredients are conven~ional additions ~o marine paints and are employed ~or modifyiny the properties of the coating composition or providing antifouling toxicity~
In addition to the organo~in su~stituted polysiloxane, oth~r marine antifouling ingredients can ~e included in the composition, in particular it is found desirable to include up to about 30% by weight of copper powder and/or cuprous salts, such as Cu20, CuSCN, Cu2S, CuO~, or the like in the composition.
Cuprous oxide is a preferred copper base antifouling a~ent. Such copper based materials are widely recognized ~s agents for inhibiting growth of marine organisms and are desirable additives in the marine coating cQmposition. Pre~erahly such copper base antifouling agents are present in the composition in the range of frorn about 10 to 20% by weight.
~en the copper bearing antifouling agent is present at less than about 10 weight percent, the minimum e~ective release rate may not be achieved o~er a lons lifetime of the coating. If the proportion is much above about 20%, passiva~ion of the copper agent may occur under some conditions.
It is desirable to include copper bearing antifouling agents in the composition for enlarging the spectrum of marine organisms combated by the antifouling coating. Copper and cuprous salts tend to be somewhat more e~fective for inhibiting growth 3Z~
of algae and more primitive soft organisms, where~s the organotin moiety is somewhat more effective against higher organisms, barnacles or the like, which are often referred to as "hard" fouling.
When the proportion of copper base antifouliny agent i5 ~n the order o~ about 15% by weight, good long-life antifouling characteristics are obtained without decreasing the other desirable properties of the coating.
When a copper ba ed antifouling agent is 1ncluded in the composition, it is also desirable to include zinc oxide in a proportion of about one-hal~ the proportion of copper base antifouling agent. The zinc oxide is desirable since it pot~ntiates ~he antifouling activi~y of the copper by enhancing the transport of copper ion across the biological membranes of marine organisms. Zi~c oxide can also promote gal~anic release o copper from the antifouling coating. An exc~ss amount of zinc oxide can suppress the antifouling activity of the copper, hence, it is desirable that the maxim~m ~inc oxide be i~ a proportion o a~out 50% of the copper base antifoulant. If zinc is included in the composition, the propor~ion of zinc oxide should be reduced.
It is believed that no single toxicant is available for compositions that can be applied to surfaces in practical situations and khat will universally protect marine surfaces against fouling.
While organotin compounds are very e~fec~ive as
particularly preferred composition has a ratio of 10 a~out 2.5 tin atoms per 5 silicon atoms. Such matexial is not c~mpletely cross-linXed and serves to modulate ~he properties of the acrylic resin in the coating composition. ~ high proportion of tin moiety is present in the composition providing 15 long life antifouling characteristics. Such a material has about the optimum balance of mechanical propexties and toxicity.
It will ~e recognized that the quantity of organotin polysiloxane binder in the composition 20 following hydrolysis and condensation will be 12ss than the proportion of oxganotin siloxane in the uncured coating composition. For example, when the organo~in siloxane comprises a tributyl tin moiety on an ethoxy siloxane whereill each molecule Z5 has an average of five silicon at~ms and the ratio of tin atoms to silicon atoms is about 2.5:5, the cured siloxane has about 73~ of the weigh~ of the uncured pr~cursor. ~he weight loss comes about from loss of the ethyl radical upon hydrolysis and 30 con~ensation, ~2~
l The acrylic resin and organotin polysiloxane in the sompositlon act as co-resins forming a binder for a paint coating. Evaporation of the solvent from the composition and exposure of the composition to en~ironmental water or water vapor results in solidification of the binder blend through deposition of the acrylic resin and concurrent hydrolytic polycondensation of the siloxane. Depending on the proportions of the materials, this binder system can be in the orm of a resin blend or an intexpenetrating pol~mer network.
Preferably the organotin polysiloxane is present in thP composition in the range of from about 7 to 25~
by weigh~. If the proportion is less ~han about 7~ by weight, the quantity ~f the organotin moiety can become so low that the antifouling characteristics of the co~position can be ~oo low fox practical use.
The rate of release of toxicant at the coating suxface can be less than the minimum required for inhibiting growth of organisms.
If the proportio~ of organotin polysiloxane in the composition is more than about 25% by weight, the mechanical properties of the organotin polysiloxane can predominate over those o the acrylic resin, ~5 thereby reducing the desirable properties of the acrylic. Further, high proportions of organotin polysiloxane can reduce the content of other toxicants such as copper bearing antiouling agents, thereby narrowing the spectrum of organisms agains~ which the antifouling coating is e~ective.
~3~3~
1 Preferably the oryanotin polysiloxane is present in the cQmposition in the range of from about 12 to 16~ by weight. This gives a good halance of the antifouling proper~ies of the siloxane and the mechanical properties of the acrylic.
Such a coating has a long useful lifetime in bo~h static and dyn~nic fouling control situations.
Preferably the quantity o~ organotin polysiloxane is somewhat larger than the proportion of acrylic resin in the composition. Preferably the weight ratio of acrylic resin to organotin polysiloxane is in the range of from about 0.5 to 1.0 and most particularly in ~he range of ~rom about 0.6 to 0.8. These provide optimum balance of an~ifouling characteristics in the combination of controlled release of toxicant and mechanical properties in ~he resultant coating.
As co-resins in the binder system the organotin polysiloxane moderates the physical properties of the acrylic resin. Ordinarily, a polysiloxane is incompatible with an acrylic resin, however, it is found that th p~esence of the trisubstituted organotin moiety on the polysiloxane makes the two types of ~inder compatible so ~hat a coating composition with Z5 reasonable shelf life can he formulated.
In the cured composition, the acrylic in the binder provides a microsmooth surface that minimizes microroughness drag penalty, and a slow controlled poiishing action can be obtained for providing m~ximum reduction of drag. In the preferred embodiment of this invention, the surface profile roughness envelope is in the 15 to 25 micron range throughout the ser~ice life of the coating and its ablation rate is less ~ha~ 3 microns o coa ing loss per month at a speed of 15 kno~s. T~e organotin moiety in the 1 binder is released at a controlled rate since it is chemically bonded to a polymeric content of the coa~ing and is not free to migrate or diffuse before hydrolysis frees the tin moiety from the.polysi.loxane.
S In other compositions in which an acrylic resin is used as binder and antifouling agen~s are included as addLtives, such as cuprous salts or tributyltin oxide, the toxicant is released at a rate controlled only by matrix properties. Since diffusion rate depends on concentration, release of toxicant at the surface is relatively high when ~he coating is fresn and diminishes steadily thereafter. To maintain an effective release rate at the surface after a long time, an excessive release rate is needed in the beginning.
.... _ . . , . _ . .. . _ _ .. . . .. . .. .... . .. . . . .. _ .. _ .. _ . . . .. . _ _ . .. . . _ .
In a composition with organotin polysiloxane and acryllc resin, release of toxicant occurs upon hydrolysis of the tin-oxygen-silicon bond. The rate ~o~ release is thus~control~ed by the rate of hydrolysis which r~mains steady throughout the life of the çoating. Since the xate of release is nearly constant~
the amount of toxicant ~an be selected to provide slightly more than an efestive amount at the projected end of the useful li~e of the coating. Little excess toxi~ant is released during the early lifP of the coating and longer life can ~e ob~ained fQr a selec~ed total amount of toxicant.
An or~anic solvent for the acxylic resin and organotin polysiloxane is preerably present in the range of from about 18 to 52% by wei~ht. Xylene is an excellent solvent for both the acrylic resin and ~23%~
l polysiloxane. In an exemplary embodiment acrylic resin is included in the composition by way of a commercially available solution of acrylic resin and -toluene. In such an embodiment the solvent in the composition compri.ses a blend of toluene and xylene. Other nonpolar solvents for acxylic resin and polysiloxane can also be used, along with limited amounts of alcohols. Exemplary solvents are xylene, toluene, various Cellosolves,* naphtha and mineral spirits. The organic solvents should be selected to provide 2 volatility that permits drying of the coating composition in a reasonable time when applied to the hull of a vessel or other substrate.
The proportion of solvent in the composition is subject to rather wide variation and is determined largely by the desired viscosity in the composition to permit application to substrates by spraying, brushing, or the like. If the ~roportion of solvent is less than about 18% by weight, the viscosity of the composition may be so high that application to substrates in coatings of reasonable thickness is rather di.fficult. Levelling to obtain a smooth coating may also be inhibite~. If the composition has more than about 52% by weight of solvent, application of coatings of reasonable thickness can be limited by sagging or running. Preferably, the solvent is present in the range of from abou-t 24 to 36% by weight. It is found that such a proportion of solvent with the preferred resin compositions and other marine paint additives hereinafter described provides a viscosity range quite suitable for application to substrates by brushing and/or spraying.
* Cellosolve is a trademark of Union Carbide Corporation.
1 A variety of other ingredients can form the balance of the composition in the range of ~rom ahout 10 to 65~ by weight. Such additional ingredients are conven~ional additions ~o marine paints and are employed ~or modifyiny the properties of the coating composition or providing antifouling toxicity~
In addition to the organo~in su~stituted polysiloxane, oth~r marine antifouling ingredients can ~e included in the composition, in particular it is found desirable to include up to about 30% by weight of copper powder and/or cuprous salts, such as Cu20, CuSCN, Cu2S, CuO~, or the like in the composition.
Cuprous oxide is a preferred copper base antifouling a~ent. Such copper based materials are widely recognized ~s agents for inhibiting growth of marine organisms and are desirable additives in the marine coating cQmposition. Pre~erahly such copper base antifouling agents are present in the composition in the range of frorn about 10 to 20% by weight.
~en the copper bearing antifouling agent is present at less than about 10 weight percent, the minimum e~ective release rate may not be achieved o~er a lons lifetime of the coating. If the proportion is much above about 20%, passiva~ion of the copper agent may occur under some conditions.
It is desirable to include copper bearing antifouling agents in the composition for enlarging the spectrum of marine organisms combated by the antifouling coating. Copper and cuprous salts tend to be somewhat more e~fective for inhibiting growth 3Z~
of algae and more primitive soft organisms, where~s the organotin moiety is somewhat more effective against higher organisms, barnacles or the like, which are often referred to as "hard" fouling.
When the proportion of copper base antifouliny agent i5 ~n the order o~ about 15% by weight, good long-life antifouling characteristics are obtained without decreasing the other desirable properties of the coating.
When a copper ba ed antifouling agent is 1ncluded in the composition, it is also desirable to include zinc oxide in a proportion of about one-hal~ the proportion of copper base antifouling agent. The zinc oxide is desirable since it pot~ntiates ~he antifouling activi~y of the copper by enhancing the transport of copper ion across the biological membranes of marine organisms. Zi~c oxide can also promote gal~anic release o copper from the antifouling coating. An exc~ss amount of zinc oxide can suppress the antifouling activity of the copper, hence, it is desirable that the maxim~m ~inc oxide be i~ a proportion o a~out 50% of the copper base antifoulant. If zinc is included in the composition, the propor~ion of zinc oxide should be reduced.
It is believed that no single toxicant is available for compositions that can be applied to surfaces in practical situations and khat will universally protect marine surfaces against fouling.
While organotin compounds are very e~fec~ive as
3~ antifouling toxicants, practical compositions that 232~
1 provide controlled relea~e of toxicant over long periods of time do not have sufficiently broad antifouling properties ~or the full spectrum of organisms. I~ is ~ound, however, that hy combining the organotin polysiloxane with other toxicants, such as copper or cuprous salts or organic algicides, the an~ifouling perormance of the coating can be effecti~e in a wide variety of fouling en~ironments for periods of ~ime far in excess of cvnventional lo coatings. This effectiveness is present under both static and turbulen~ conditionsO This diff~rs from prior compositions for con~rolled xelease of toxicants which are optimized for either static or dynamic c~nditions, rather than both.
It is particularly advantageous to employ copper bearing an~ifouling agents such as copper powder or cuprous salts as an additional toxicant in a coating composition having trisubstituted organotin polysiloxane and acrylic resin as binders. Ordi~arily in a seawater environment at least a portion of the ¢opper is converted to inactive salts, such a~ copper oxychloxides, which are rela~ively ineffective in inhibiting growth of marine fouling organisms. The reason that the acrylic and organotin polysiloxane 2S binders tend to s~abilize the copper or copper salts in seawater is not yet un~lers~ood. It is believed that with organo~in polysiloxane in the composition ~he amount o~ copper bearing antifouling agent can be reduced, as compared with pxior compositions, withou~
reducing antifouling activity. Lower copper concentration may avoid passivation.
3~
l Preferably the weight ratio of trisubstituted organotin polysiloxane to copper powder or cuprous saLt in the composition is in the range of from about 0.5 to 1.5. When the ratio is either above or below this range there is a decrease in the spectrum of organisms combated by the anti~ouling composi~ion.
A proportion near the middle of this range appears to give the best broad spectrum antifouling activity.
It is also desirable that the weight ratio of binders to copper powder or cuprous salt be in the range of fr~m about 0.~ to 2 to provide an appropriate range of strength and controlled release of toxicant for good long life antiouling activity. When ~he ratio of ~inder to copper bearing antifouling agent is less tha`n about 0.8 the erosion resistance of the coa~ing and the life of the copper constituent can ~e significantly reduced. If the proportion of ~inder relative to the copper bearing constituent is more ~han-about 2, there is a reduction in the a~ailability of copper at the surface an~ a decrease in the antifouling activity, particularly for algae and soft organîsms against which copper is particularly effective.
Pre~erably, the composition includes a conven~ional plasticizer for the binders in the range of ~rom about 0.5 to 5% by weight, and most preferably about 0~5 to 2~ by weight. The plasticizer imparts flexibili~y and resilience to the ~ured composition. External plasticizers that maintain theix molecular identity are preferred, 3~
1 rather than plasticizers that chemically bond in the polymer system. A variety of conventional plasticizers that are compatible with the acrylic resin and organotin polysiloxane are suitable, such as alkyl benzyl, phthalates, dialkyl phthalates, phosphate esters, sulfonamides, butyl phthalyl butyl glycolate, diphenyl phthalate, dicyclohexyl phthala~e, tricresyl phosphate, and the like~ The amount of plasticizer employed in the compositio~
is somewhat proportioned to the tin to silicon ratio in the polysiloxane. A smaller amount of plasticizer can be used when the tin to silicon ratio is high since the polysiloxane can also act as a plasticizer. Conversely, when the tin to silicon ratio is low so that the polysiloxane is extensively cross-linked and xigid, a somewhat higher proportion of other plasticizer can be i~cluded in the co~position.
It is desirable to include a slightly water soluble resin in the composition for enhancing ~radual dissolution and ablation of the coating.
Addition of such resins ~hat are slightly soluble in seawater enhances the microporosity of the coating and can help control the hydrolysis of the organotin moiety for maintaining antifouling characteris~ics over a long li~etime. Pre~erably, the water soluble resin is water white rosin, since it is economical, easily blended into the composi~ion, and quite suitable in stability and water solubility. Other sli~htly soluble resins can be substituted such as hydroxy et~yl methacrylate, polyvinyl acPtate, polyvinyl alcohol, or the like.
3~
( 1 The proportion of water soluble resin in the composition depends on the degree of solubility of the resin and desired xate of ablation and penetration of water into the coating. For example, when rosin is the seawater soluble portion of the composition, it is preferably present in the range of from about 1 to 10 by weight, and most preferably in the rangé of from about 3 to 6~ by weight. If the rosin is present at less than about 1~ by weight, the coating may become passivated, and a~tifouling characteristics degraded, particularly when copper or copper salts are included in the composition. Rosin content o more than about 10~ by weight leads to excessive ablation and short lifetime of such a coating. Preferably, rosin is present in the range of from about 3 to 6~ by weight, to provide a good balance of coating lifetime and water penetration to provide long antifouling activity.
It is highly desirable to include a thixotropic agent such as alcohol swellable clay, talc, or colloidal silica. Such conventional thickeners are widely used in paint compositions for modifying viscosity and obtaining paints that can be sprayed or brushed to provide a coating of reasonable thickness without sagging or running. An exemplary thickening agent particularly useful is dimethyl dioctodecyl ammonium bentonite avallable from the Baroid Division of National Lead Company, Houston, Texas, as Bentone*34.
Preferably the thickener is present in the composition in the range of from about 0.5 to 4% by weight and most preferably in the range of from about 0.5 to 2.0 by weight, as is conventional in paint compositions.
*Bentone is a trade mark of National Lead ~ompany.
2~
1 It is desirable to include antisettling agents for the copper base materials and other fillers and pigments employed in the composition. A variety of antisettling agents used in paint compositions are suitable for preventing settling and minimizing mixing that might be nee~ed before a composition is used after a prolonged shelf life. Antisettling agents are employed in marine paint compositions up to a~out 3% by weight.
If desired, organic algicides can ~e included in the composition, such as dichlorisothiazalone or diiodomethyl p-tolyl sulfone. Preferably, such algicides are present in a proportion up to about 16% ~y weightr and most preferably up to about 5%
by weight. 5uch algicides can promote gelling of the composition and the proportions are preferably kept low e~ough to inhibit such gelling and maintain a long shel li~e.
A variety of conventional fillers and pigments can also be included in the coating composition.
Such materials can modify the properties of the paint as it is applied, such as body to promote good spreading and leveling without runs or sags.
Such materials can also modify properties o the ~ured coating such as strength, toughness, opa~ity and color. Pigments and fillers can also help protect the substrate on which the coating composition is placed. Exemplary pigments and illers include red iron oxide, talc, silica, titanium ~ioxide, chromium oxi~e, and the like.
3~
3~
1 Such pigments and fillers can be included in the composition up to about 20% by weight. If present in a proportion more than about 20~ by weight,it hecomes necessary to reduce the propo~tions o~ algicides and other ingredients in the composition that are active in inhibiting growth of marine organisms. Preferably the pigments and fillers are present in the order o~ about 7% by weight which provides good protection for substrates, opacity and strength.
The proportions of liquid and solid ingredients are selected so that the composition can be sprayed or brushed onto a variety of substrates as a marine paint.
Miscellaneous other ingredients can also be included in the composition. Zinc powder can be included for inhibiting corrosion. A small amount of phosphoric acid ~e.g., 0.5%) can be included for inhibiting premature gelling. The composition is preera~1y packaged in a single container for ready use as a paint. I~ desired it can be prepared in two packages ~or longer shelf life and mixed shortly ~efore use. Many other modifications and variations will be apparent.
When th~ coating composition is applied to a surface, concurrent effects are occurring in the acrylic and polysiloxane binders. The acrylic resin foxms a solid binder network as the volatile solvents evaporate. The organotin polysiloxane hydrolyzes and condenses. If desired, the polysiloxane can be l at least partially hydrolyzed before application of the coating. Such prehydrolysis can be desirable for rapid cure of the coatiny but the shelf life of the mi~ure may be decreased. Hydrolysis of the polysiioxane can occur from ambient water vapor of exposure to water. ~ variety of bases or acids can be present in small quantities ~o promote hydrolysis as descrIbed in U. S. Paten~ No. 4,080,190. Algicides, zinc oxide and other ingredients in the composition can ~e sufficient to promote hydrolysis. I~ might be note~ that use of some basic promoters of hydrolysis may not be totally compatible with copper bearing antifouling agents. Such promoters may be omitted or the composition used within a reasonable time after mixing, or ~he copper ~earing materials can be added shortly before applying the coating.
EXAPPLES
Table I sets forth the compositions o six antifoulihg coating compositions prepared in practice of this invention. The compositions were mixed much as one would mix other paint compositions. The composi~ions were applied to standaxd test panels by spraying and the tes~ panels were immersed in seawater at Daytona Beach, Florida, for detenmining antifouling activity.
~92~
EXAMPLES
INGREDIENT A B C D E F
Acryloid B-48N ~26.8 26.8 17.818.0 26.8 22.5 OTPS 15~3 15.2 12.212.4 15.2 14~7 Cuprous oxide - 22.2 19.018.7 17.0 15.5 Zinc oxide 8.0 8.8 8.8 8.9 9.0 7.5 Ethyl aminoethanol 0.8 0.8 - - 1.1 0.8 Di-isodecylphthalate 1.0 2.0 1.3 1.2 2.0 1.2 W. W. Rosin 4.2 4.8 5.8 5.9 4.8 4.0 Red iron oxide11.4 - 2~8 7.3 ~ 2.4 Nytal 300 C~ ~ )7.0 2.5 ~.5 ~ 3.0 2.1 MP~-1078X ~f.~ l.g 1.9 - 1.6 Bentone 34 (~ ~ ~ 1.5 1.3 0.9 0.9 0.7 1.1 ~eosol ~-r ~.~ 0.4 0.4 0.3 0.2 0.2 0.3 Amical 48 (~. n ) _ - 6.0 C-9211 C~ ~ ) 6.0 6.0 - 6.1 6.0 6.6 Xylene _ 17.6 9.2 20.718.5 1~.2 19.7 TOTAL100~0 100.0 100.0 100.0 100.0 100.0 ~
The proportions of ingredients listed in Table I are set forth in percentayes by weight for each of the six coating compositions. The materials set forth in Table I are identified as follows:
Acryloid*B~48N comprises a solution of methyl methacrylate in toluene available from Rohm and Haas, Philadelphia, Pennsylvania. The solution has 45~ by weight polymethyl methacrylate and 55% by weight toluene.
OTPS refers to organotin polysiloxane. In each of the coating compositions set forth in Table I, the organotin * Acryloid is a trade mark of Rohm and Haas~
- ~s -1 polysiloxane had the formula:
x - o - - Si - t X
o - X ~
m where m was an average of about 5 and X was either an ethyl radical o~ a tributyl tin radica~ and the X ' s were selected so that the ratio of tin atoms to silicon 10 a~oms was about 2. 5: S.
Cuprous oxide is present as a ~inely divided powder which, as pointed out above, inhibits gxowth of marine org2nisms. 2inc oxide is also present as a finely divided powder and serves as a pigment plus potentiat~:~g the activity of the copper salt.
Ethyl aminoethanol is present in the composition to promote hydrolysis and condensation of ~he siloxane.
Di~isodecylphthalate is present as an external plasti~izer for the acrylic and siloxane binders. W. W. rosin (water 20 white rosin) is present as a slightly wa~er soluble resin to modiy the binder matrix and help control gradual release of toxicants when he GOating is immersed in seawatex.
Red iron oxide is present in the ~orm of a powder serving as a pigment. The pigment improves the strength and opa~ity of the composition. Nytal 300 is a finely divided talc available from Ro T. Vanderbilt Company, Wo~walk, Connecticut. The talc is present as a filler that improves ~iscosity of the coa~ing composi~ion and ~0 inhi~its sagging.
, .
1 MPA-1078X available from Baker Castor Oil Company, Bayonne, New Jersey, is a colloidal thixotropic agent used to prevent settling of solid powders. It is added as a paste of solids dispersed in a solvent o~ xylene or toluene.
Bentone 34, a-railable from National Lead Company, Baroid Division, ~ouston, Texas, is finely divided dLmethyl dioctodecyl ammonium bentonite for thickening the composition and aiding in suspension of solids~
Neosol, available from Shell Chemical Company, ~ouston, Texas, is ethyl alcohol denatured with small amounts of me~hyl isobutyl ke~one, ethyl acetate and a~ia~ion gasol.ineO As a preliminary step in formulating the coating eomposi~ion the Neosol i~ mixed with the Bentone 34 to form a pas~a and cause swelling of the Bentone 34.
kmical-48 available from Abbott Laboratories, North Chicago~ Illinois, comprises di~-iodometh~ tolyl sulfone and serves as an additional algicide.
C-9211 is a 4,5~dichloro-2-n-octyl-4-isothiazalin-~-one algicide available ~rom Rohm and Haas Company, Philadelphia, Pennsylvania. The algicide can also provide a source o protons to promote hydrolysis of the sil~xane. It ~s aesirable in preparin~ a composition to add ~he algicide after all o~ the other ingredients have been mixed to minimi~e the possibility o premature gelation.
The composition is made by first diluting the acrylic resi~ solution with additional sol~en~. Some of the xylene can ~e reserved .for making a paste of the solid ingredients to speed mixing~ The organotin 3~
~z~æ~
l polysiloxane is added and mixed, followed by the plasticizer. After all of the liquid and soluble ~aterials have been mixed, the solid material~ are added with as much mixing shear as required to obtain a smooth paint composition. The order of adding in~.redients to the composition is not c.ritical, although it is desirable to add the algicide or any catalyzing amine last in order to minimize premature gelation.
The coating compositions set forth in Table I
were applied to standard blan~ panels of primer coated steel or plastic for measuring resistance to marine fouling. These panels wexe then exposed to sewater at Daytona Beach, ~lori~a. The foulinq resistance of the composition as a function o months of exposure is set forth in Table II.
TABLE II
H~D FOULING _ ALGAL FOULING _ _ EXAMPLE 612 18 24 Mos. 6 12 18 24 Mos.
~
A 10 1~10 10 9 5 5 10~0 - 1010 10 -Control 0 0 00 0 0 Control panel refers to a blank panel with no antifouling ~oating. Hard fouling refers to the growth o barnacles and similar organisms with hard body parts. Algal fouling ~5 3%~
1 refers to algae and other soft organisms. The ratings of the test panels or fouling resistance is on a scale of 0 to 10, where 10 represents no fouling whatsoever, 9 represents a very minor or trace amount of fouling, 5 represents approximately 50% of the test panel fouled and 0 represents complete ailure or fouling over the entire surface.
1 provide controlled relea~e of toxicant over long periods of time do not have sufficiently broad antifouling properties ~or the full spectrum of organisms. I~ is ~ound, however, that hy combining the organotin polysiloxane with other toxicants, such as copper or cuprous salts or organic algicides, the an~ifouling perormance of the coating can be effecti~e in a wide variety of fouling en~ironments for periods of ~ime far in excess of cvnventional lo coatings. This effectiveness is present under both static and turbulen~ conditionsO This diff~rs from prior compositions for con~rolled xelease of toxicants which are optimized for either static or dynamic c~nditions, rather than both.
It is particularly advantageous to employ copper bearing an~ifouling agents such as copper powder or cuprous salts as an additional toxicant in a coating composition having trisubstituted organotin polysiloxane and acrylic resin as binders. Ordi~arily in a seawater environment at least a portion of the ¢opper is converted to inactive salts, such a~ copper oxychloxides, which are rela~ively ineffective in inhibiting growth of marine fouling organisms. The reason that the acrylic and organotin polysiloxane 2S binders tend to s~abilize the copper or copper salts in seawater is not yet un~lers~ood. It is believed that with organo~in polysiloxane in the composition ~he amount o~ copper bearing antifouling agent can be reduced, as compared with pxior compositions, withou~
reducing antifouling activity. Lower copper concentration may avoid passivation.
3~
l Preferably the weight ratio of trisubstituted organotin polysiloxane to copper powder or cuprous saLt in the composition is in the range of from about 0.5 to 1.5. When the ratio is either above or below this range there is a decrease in the spectrum of organisms combated by the anti~ouling composi~ion.
A proportion near the middle of this range appears to give the best broad spectrum antifouling activity.
It is also desirable that the weight ratio of binders to copper powder or cuprous salt be in the range of fr~m about 0.~ to 2 to provide an appropriate range of strength and controlled release of toxicant for good long life antiouling activity. When ~he ratio of ~inder to copper bearing antifouling agent is less tha`n about 0.8 the erosion resistance of the coa~ing and the life of the copper constituent can ~e significantly reduced. If the proportion of ~inder relative to the copper bearing constituent is more ~han-about 2, there is a reduction in the a~ailability of copper at the surface an~ a decrease in the antifouling activity, particularly for algae and soft organîsms against which copper is particularly effective.
Pre~erably, the composition includes a conven~ional plasticizer for the binders in the range of ~rom about 0.5 to 5% by weight, and most preferably about 0~5 to 2~ by weight. The plasticizer imparts flexibili~y and resilience to the ~ured composition. External plasticizers that maintain theix molecular identity are preferred, 3~
1 rather than plasticizers that chemically bond in the polymer system. A variety of conventional plasticizers that are compatible with the acrylic resin and organotin polysiloxane are suitable, such as alkyl benzyl, phthalates, dialkyl phthalates, phosphate esters, sulfonamides, butyl phthalyl butyl glycolate, diphenyl phthalate, dicyclohexyl phthala~e, tricresyl phosphate, and the like~ The amount of plasticizer employed in the compositio~
is somewhat proportioned to the tin to silicon ratio in the polysiloxane. A smaller amount of plasticizer can be used when the tin to silicon ratio is high since the polysiloxane can also act as a plasticizer. Conversely, when the tin to silicon ratio is low so that the polysiloxane is extensively cross-linked and xigid, a somewhat higher proportion of other plasticizer can be i~cluded in the co~position.
It is desirable to include a slightly water soluble resin in the composition for enhancing ~radual dissolution and ablation of the coating.
Addition of such resins ~hat are slightly soluble in seawater enhances the microporosity of the coating and can help control the hydrolysis of the organotin moiety for maintaining antifouling characteris~ics over a long li~etime. Pre~erably, the water soluble resin is water white rosin, since it is economical, easily blended into the composi~ion, and quite suitable in stability and water solubility. Other sli~htly soluble resins can be substituted such as hydroxy et~yl methacrylate, polyvinyl acPtate, polyvinyl alcohol, or the like.
3~
( 1 The proportion of water soluble resin in the composition depends on the degree of solubility of the resin and desired xate of ablation and penetration of water into the coating. For example, when rosin is the seawater soluble portion of the composition, it is preferably present in the range of from about 1 to 10 by weight, and most preferably in the rangé of from about 3 to 6~ by weight. If the rosin is present at less than about 1~ by weight, the coating may become passivated, and a~tifouling characteristics degraded, particularly when copper or copper salts are included in the composition. Rosin content o more than about 10~ by weight leads to excessive ablation and short lifetime of such a coating. Preferably, rosin is present in the range of from about 3 to 6~ by weight, to provide a good balance of coating lifetime and water penetration to provide long antifouling activity.
It is highly desirable to include a thixotropic agent such as alcohol swellable clay, talc, or colloidal silica. Such conventional thickeners are widely used in paint compositions for modifying viscosity and obtaining paints that can be sprayed or brushed to provide a coating of reasonable thickness without sagging or running. An exemplary thickening agent particularly useful is dimethyl dioctodecyl ammonium bentonite avallable from the Baroid Division of National Lead Company, Houston, Texas, as Bentone*34.
Preferably the thickener is present in the composition in the range of from about 0.5 to 4% by weight and most preferably in the range of from about 0.5 to 2.0 by weight, as is conventional in paint compositions.
*Bentone is a trade mark of National Lead ~ompany.
2~
1 It is desirable to include antisettling agents for the copper base materials and other fillers and pigments employed in the composition. A variety of antisettling agents used in paint compositions are suitable for preventing settling and minimizing mixing that might be nee~ed before a composition is used after a prolonged shelf life. Antisettling agents are employed in marine paint compositions up to a~out 3% by weight.
If desired, organic algicides can ~e included in the composition, such as dichlorisothiazalone or diiodomethyl p-tolyl sulfone. Preferably, such algicides are present in a proportion up to about 16% ~y weightr and most preferably up to about 5%
by weight. 5uch algicides can promote gelling of the composition and the proportions are preferably kept low e~ough to inhibit such gelling and maintain a long shel li~e.
A variety of conventional fillers and pigments can also be included in the coating composition.
Such materials can modify the properties of the paint as it is applied, such as body to promote good spreading and leveling without runs or sags.
Such materials can also modify properties o the ~ured coating such as strength, toughness, opa~ity and color. Pigments and fillers can also help protect the substrate on which the coating composition is placed. Exemplary pigments and illers include red iron oxide, talc, silica, titanium ~ioxide, chromium oxi~e, and the like.
3~
3~
1 Such pigments and fillers can be included in the composition up to about 20% by weight. If present in a proportion more than about 20~ by weight,it hecomes necessary to reduce the propo~tions o~ algicides and other ingredients in the composition that are active in inhibiting growth of marine organisms. Preferably the pigments and fillers are present in the order o~ about 7% by weight which provides good protection for substrates, opacity and strength.
The proportions of liquid and solid ingredients are selected so that the composition can be sprayed or brushed onto a variety of substrates as a marine paint.
Miscellaneous other ingredients can also be included in the composition. Zinc powder can be included for inhibiting corrosion. A small amount of phosphoric acid ~e.g., 0.5%) can be included for inhibiting premature gelling. The composition is preera~1y packaged in a single container for ready use as a paint. I~ desired it can be prepared in two packages ~or longer shelf life and mixed shortly ~efore use. Many other modifications and variations will be apparent.
When th~ coating composition is applied to a surface, concurrent effects are occurring in the acrylic and polysiloxane binders. The acrylic resin foxms a solid binder network as the volatile solvents evaporate. The organotin polysiloxane hydrolyzes and condenses. If desired, the polysiloxane can be l at least partially hydrolyzed before application of the coating. Such prehydrolysis can be desirable for rapid cure of the coatiny but the shelf life of the mi~ure may be decreased. Hydrolysis of the polysiioxane can occur from ambient water vapor of exposure to water. ~ variety of bases or acids can be present in small quantities ~o promote hydrolysis as descrIbed in U. S. Paten~ No. 4,080,190. Algicides, zinc oxide and other ingredients in the composition can ~e sufficient to promote hydrolysis. I~ might be note~ that use of some basic promoters of hydrolysis may not be totally compatible with copper bearing antifouling agents. Such promoters may be omitted or the composition used within a reasonable time after mixing, or ~he copper ~earing materials can be added shortly before applying the coating.
EXAPPLES
Table I sets forth the compositions o six antifoulihg coating compositions prepared in practice of this invention. The compositions were mixed much as one would mix other paint compositions. The composi~ions were applied to standaxd test panels by spraying and the tes~ panels were immersed in seawater at Daytona Beach, Florida, for detenmining antifouling activity.
~92~
EXAMPLES
INGREDIENT A B C D E F
Acryloid B-48N ~26.8 26.8 17.818.0 26.8 22.5 OTPS 15~3 15.2 12.212.4 15.2 14~7 Cuprous oxide - 22.2 19.018.7 17.0 15.5 Zinc oxide 8.0 8.8 8.8 8.9 9.0 7.5 Ethyl aminoethanol 0.8 0.8 - - 1.1 0.8 Di-isodecylphthalate 1.0 2.0 1.3 1.2 2.0 1.2 W. W. Rosin 4.2 4.8 5.8 5.9 4.8 4.0 Red iron oxide11.4 - 2~8 7.3 ~ 2.4 Nytal 300 C~ ~ )7.0 2.5 ~.5 ~ 3.0 2.1 MP~-1078X ~f.~ l.g 1.9 - 1.6 Bentone 34 (~ ~ ~ 1.5 1.3 0.9 0.9 0.7 1.1 ~eosol ~-r ~.~ 0.4 0.4 0.3 0.2 0.2 0.3 Amical 48 (~. n ) _ - 6.0 C-9211 C~ ~ ) 6.0 6.0 - 6.1 6.0 6.6 Xylene _ 17.6 9.2 20.718.5 1~.2 19.7 TOTAL100~0 100.0 100.0 100.0 100.0 100.0 ~
The proportions of ingredients listed in Table I are set forth in percentayes by weight for each of the six coating compositions. The materials set forth in Table I are identified as follows:
Acryloid*B~48N comprises a solution of methyl methacrylate in toluene available from Rohm and Haas, Philadelphia, Pennsylvania. The solution has 45~ by weight polymethyl methacrylate and 55% by weight toluene.
OTPS refers to organotin polysiloxane. In each of the coating compositions set forth in Table I, the organotin * Acryloid is a trade mark of Rohm and Haas~
- ~s -1 polysiloxane had the formula:
x - o - - Si - t X
o - X ~
m where m was an average of about 5 and X was either an ethyl radical o~ a tributyl tin radica~ and the X ' s were selected so that the ratio of tin atoms to silicon 10 a~oms was about 2. 5: S.
Cuprous oxide is present as a ~inely divided powder which, as pointed out above, inhibits gxowth of marine org2nisms. 2inc oxide is also present as a finely divided powder and serves as a pigment plus potentiat~:~g the activity of the copper salt.
Ethyl aminoethanol is present in the composition to promote hydrolysis and condensation of ~he siloxane.
Di~isodecylphthalate is present as an external plasti~izer for the acrylic and siloxane binders. W. W. rosin (water 20 white rosin) is present as a slightly wa~er soluble resin to modiy the binder matrix and help control gradual release of toxicants when he GOating is immersed in seawatex.
Red iron oxide is present in the ~orm of a powder serving as a pigment. The pigment improves the strength and opa~ity of the composition. Nytal 300 is a finely divided talc available from Ro T. Vanderbilt Company, Wo~walk, Connecticut. The talc is present as a filler that improves ~iscosity of the coa~ing composi~ion and ~0 inhi~its sagging.
, .
1 MPA-1078X available from Baker Castor Oil Company, Bayonne, New Jersey, is a colloidal thixotropic agent used to prevent settling of solid powders. It is added as a paste of solids dispersed in a solvent o~ xylene or toluene.
Bentone 34, a-railable from National Lead Company, Baroid Division, ~ouston, Texas, is finely divided dLmethyl dioctodecyl ammonium bentonite for thickening the composition and aiding in suspension of solids~
Neosol, available from Shell Chemical Company, ~ouston, Texas, is ethyl alcohol denatured with small amounts of me~hyl isobutyl ke~one, ethyl acetate and a~ia~ion gasol.ineO As a preliminary step in formulating the coating eomposi~ion the Neosol i~ mixed with the Bentone 34 to form a pas~a and cause swelling of the Bentone 34.
kmical-48 available from Abbott Laboratories, North Chicago~ Illinois, comprises di~-iodometh~ tolyl sulfone and serves as an additional algicide.
C-9211 is a 4,5~dichloro-2-n-octyl-4-isothiazalin-~-one algicide available ~rom Rohm and Haas Company, Philadelphia, Pennsylvania. The algicide can also provide a source o protons to promote hydrolysis of the sil~xane. It ~s aesirable in preparin~ a composition to add ~he algicide after all o~ the other ingredients have been mixed to minimi~e the possibility o premature gelation.
The composition is made by first diluting the acrylic resi~ solution with additional sol~en~. Some of the xylene can ~e reserved .for making a paste of the solid ingredients to speed mixing~ The organotin 3~
~z~æ~
l polysiloxane is added and mixed, followed by the plasticizer. After all of the liquid and soluble ~aterials have been mixed, the solid material~ are added with as much mixing shear as required to obtain a smooth paint composition. The order of adding in~.redients to the composition is not c.ritical, although it is desirable to add the algicide or any catalyzing amine last in order to minimize premature gelation.
The coating compositions set forth in Table I
were applied to standard blan~ panels of primer coated steel or plastic for measuring resistance to marine fouling. These panels wexe then exposed to sewater at Daytona Beach, ~lori~a. The foulinq resistance of the composition as a function o months of exposure is set forth in Table II.
TABLE II
H~D FOULING _ ALGAL FOULING _ _ EXAMPLE 612 18 24 Mos. 6 12 18 24 Mos.
~
A 10 1~10 10 9 5 5 10~0 - 1010 10 -Control 0 0 00 0 0 Control panel refers to a blank panel with no antifouling ~oating. Hard fouling refers to the growth o barnacles and similar organisms with hard body parts. Algal fouling ~5 3%~
1 refers to algae and other soft organisms. The ratings of the test panels or fouling resistance is on a scale of 0 to 10, where 10 represents no fouling whatsoever, 9 represents a very minor or trace amount of fouling, 5 represents approximately 50% of the test panel fouled and 0 represents complete ailure or fouling over the entire surface.
Claims
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A marine antifouling coating composition comprising:
an acrylic resin selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate in the range of from 6 to 20 percent by weight;
an organotin polysiloxane having the formula where m is an average of up to about ten, each X is independently selected from the group consisting of R and Y; where each R is selected from the group consisting of hydrogen and alkyl and alkoxyalkyl radicals containing less than six carbon atoms;
where each Y is a trisubstituted tin radical having the formula where R1, R2, and R3 are independently selected from the group consisting of alkyl, cycloalkyl and aryl radicals and R1, R2, and R3 contain collectively up to 18 carbon atoms; and the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 0.7:5 to 5:5, the organotin polysiloxane being in the range of from 7 to 25 percent by weight;
solvent for the acrylic resin and polysiloxane in the range of from 18 to 52 percent by weight; and a balance in the range of from 10 to 65 percent by weight of primarily marine paint and toxicant agents selected from the group consisting of pigment powders, fillers, thickening agents, antisettling agents, copper powder, cuprous salts, zinc oxide, algicides, silica, clay, talc, metal oxides, plasticizers and slightly water soluble resins.
2. A composition as recited in Claim 1 wherein the acrylic resin is present in the range of from 8 to 12 percent by weight.
3. A composition as recited in Claim 2 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
4. A composition as recited in Claim 1 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
5. A composition as recited in Claim 1 wherein the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 1.3:5 to 2.5:5.
6. A composition as recited in Claim 5 wherein the acrylic resin comprises polymethyl methacrylate in the range of from 8 to 12 percent by weight.
7. A composition as recited in Claim 6 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
8. A composition as recited in Claim 5 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
9. A composition as recited in Claim 1 comprising a copper base antifouling agent selected from the group consisting of copper powder and cuprous salts in the range of from 10 to 30 percent by weight.
10. A composition as recited in Claim 9 wherein the acrylic resin is present in the range of from 8 to 12 percent by weight.
11. A composition as recited in Claim 10 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
12. A composition as recited in Claim 9 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
13. A composition as recited in any of claims 2, 5 and 10, comprising a plasticizer for acrylic resin in the range of from 0.5 to 5 percent by weight.
15. A composition as recited in any of claims 3, 5 and 9, wherein the solvent is present in the range of from 24 to 36 percent by weight.
16. A composition as recited in any of claims 3, 5 and 9, wherein the balance of marine paint and toxicant agents is in the range of from 30 to 45 percent by weight.
17. A composition as recited in claim 1 wherein m in the formula is an average of at least about 5.
18. A composition as recited in claim 17 wherein R1, R2 and R3 are each butyl.
19. A compositon as recited in claim 1 wherein R1, R2 and R3 are each butyl.
20. A composition as recited in Claim 19 wherein R is selected from the group consisting of hydrogen and ethyl radical.
21. A composition as recited in Claim 20 wherein the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 1.3:5 to 2.5:5.
22. A composition as recited in Claim 21 wherein m in the formula is an average of at least about 5.
23. A composition as recited in Claim 1 wherein the weight ratio of acrylic resin to organotin polysiloxane is in the range of from 0.5 to 1Ø
24. A composition as recited in Claim 23 wherein the weight ratio of acrylic resin to organotin polysiloxane is in the range of from 0.6 to 0.8.
25. A composition as recited in Claim 1 comprising a copper bearing antifouling agent selected from the group consisting of copper powder and cuprous salts wherein the weight ratio of organotin polysiloxane to the copper bearing antifouling agent is in the range of from 0.5 to 1.5.
26. A composition as claimed in claim 1, 4 and 22, comprising a copper bearing antifouling agent selected from the group consisting of copper powder and cuprous salts.
1. A marine antifouling coating composition comprising:
an acrylic resin selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, and n-butyl methacrylate in the range of from 6 to 20 percent by weight;
an organotin polysiloxane having the formula where m is an average of up to about ten, each X is independently selected from the group consisting of R and Y; where each R is selected from the group consisting of hydrogen and alkyl and alkoxyalkyl radicals containing less than six carbon atoms;
where each Y is a trisubstituted tin radical having the formula where R1, R2, and R3 are independently selected from the group consisting of alkyl, cycloalkyl and aryl radicals and R1, R2, and R3 contain collectively up to 18 carbon atoms; and the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 0.7:5 to 5:5, the organotin polysiloxane being in the range of from 7 to 25 percent by weight;
solvent for the acrylic resin and polysiloxane in the range of from 18 to 52 percent by weight; and a balance in the range of from 10 to 65 percent by weight of primarily marine paint and toxicant agents selected from the group consisting of pigment powders, fillers, thickening agents, antisettling agents, copper powder, cuprous salts, zinc oxide, algicides, silica, clay, talc, metal oxides, plasticizers and slightly water soluble resins.
2. A composition as recited in Claim 1 wherein the acrylic resin is present in the range of from 8 to 12 percent by weight.
3. A composition as recited in Claim 2 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
4. A composition as recited in Claim 1 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
5. A composition as recited in Claim 1 wherein the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 1.3:5 to 2.5:5.
6. A composition as recited in Claim 5 wherein the acrylic resin comprises polymethyl methacrylate in the range of from 8 to 12 percent by weight.
7. A composition as recited in Claim 6 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
8. A composition as recited in Claim 5 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
9. A composition as recited in Claim 1 comprising a copper base antifouling agent selected from the group consisting of copper powder and cuprous salts in the range of from 10 to 30 percent by weight.
10. A composition as recited in Claim 9 wherein the acrylic resin is present in the range of from 8 to 12 percent by weight.
11. A composition as recited in Claim 10 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
12. A composition as recited in Claim 9 wherein the organotin polysiloxane is present in the range of from 12 to 16 percent by weight.
13. A composition as recited in any of claims 2, 5 and 10, comprising a plasticizer for acrylic resin in the range of from 0.5 to 5 percent by weight.
15. A composition as recited in any of claims 3, 5 and 9, wherein the solvent is present in the range of from 24 to 36 percent by weight.
16. A composition as recited in any of claims 3, 5 and 9, wherein the balance of marine paint and toxicant agents is in the range of from 30 to 45 percent by weight.
17. A composition as recited in claim 1 wherein m in the formula is an average of at least about 5.
18. A composition as recited in claim 17 wherein R1, R2 and R3 are each butyl.
19. A compositon as recited in claim 1 wherein R1, R2 and R3 are each butyl.
20. A composition as recited in Claim 19 wherein R is selected from the group consisting of hydrogen and ethyl radical.
21. A composition as recited in Claim 20 wherein the X's are selected so that the ratio of tin atoms to silicon atoms is in the range of from 1.3:5 to 2.5:5.
22. A composition as recited in Claim 21 wherein m in the formula is an average of at least about 5.
23. A composition as recited in Claim 1 wherein the weight ratio of acrylic resin to organotin polysiloxane is in the range of from 0.5 to 1Ø
24. A composition as recited in Claim 23 wherein the weight ratio of acrylic resin to organotin polysiloxane is in the range of from 0.6 to 0.8.
25. A composition as recited in Claim 1 comprising a copper bearing antifouling agent selected from the group consisting of copper powder and cuprous salts wherein the weight ratio of organotin polysiloxane to the copper bearing antifouling agent is in the range of from 0.5 to 1.5.
26. A composition as claimed in claim 1, 4 and 22, comprising a copper bearing antifouling agent selected from the group consisting of copper powder and cuprous salts.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31286881A | 1981-10-19 | 1981-10-19 | |
| US312,868 | 1981-10-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1192329A true CA1192329A (en) | 1985-08-20 |
Family
ID=23213364
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000413264A Expired CA1192329A (en) | 1981-10-19 | 1982-10-12 | Organotin polysiloxane and acrylic antifouling coating |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1192329A (en) |
-
1982
- 1982-10-12 CA CA000413264A patent/CA1192329A/en not_active Expired
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