HK1142355A - Anti-fouling coating compositions containing a carboxyl-functional organosilicone - Google Patents

Description

Anti-fouling coating compositions containing carboxy-functional organopolysiloxanes

The present invention relates to an antifouling coating composition, a substrate coated with said composition and the use of said coating composition for inhibiting fouling of a substrate in an aquatic environment.

Man-made structures such as boat hulls, buoys, drilling platforms, dry dock equipment, oil production rigs, and pipelines that are submerged in water are prone to contamination by aquatic organisms such as green and brown algae, barnacles, mussels, and the like. Such structures are typically made of metal, but may also comprise other structural materials such as concrete. This contamination has a detrimental effect on the hull of the vessel as it increases frictional resistance during movement in the water, with consequent reduction in speed and increase in fuel costs. It has a damaging effect on static structures such as the legs of drilling platforms and oil production rigs, firstly because the resistance of thick fouling layers to waves and currents can cause unpredictable and potentially dangerous stresses in the structure, and secondly because of fouling it is difficult to inspect the structure for defects such as stress fractures and corrosion. It has a detrimental effect on pipes such as cooling water inlets and outlets because contamination reduces the effective cross-sectional area and as a result reduces the flow velocity.

The most successful method of commercially inhibiting fouling involves the use of antifouling coatings containing substances toxic to aquatic organisms, such as tributyltin chloride or cuprous oxide. However, such coatings are increasingly being disfavored because of the destructive effects such toxins may have if released into aquatic environments. Thus, there is a need for non-fouling coatings that do not release significantly toxic materials.

It has been known for many years (for example as disclosed in GB 1,307,001 and US 3,702,778) that silicone rubber coatings resist contamination by aquatic organisms. It is believed that such coatings provide a surface to which organisms do not readily adhere, and therefore they may be referred to as fouling release coatings rather than anti-fouling coatings. Silicone rubbers and silicone compounds generally have very low toxicity. When applied to the hull, the disadvantage of this anti-fouling system is that, although the accumulation of marine organisms is reduced, a higher boat speed is required to remove all the fouling material. Thus, in some cases, it has been shown that effective release from hulls that have been treated with the polymer requires sailing at speeds of at least 14 knots. For this reason, silicone rubbers have met with limited commercial success and there is a need to improve the antifouling and fouling release characteristics of these environmentally benign coatings.

FR 2537985 discloses an anti-fouling coating composition comprising a methyl organosiloxane resin, a silicone elastomer, polytetrafluoroethylene, an acrylic binder and a solvent or diluent.

EP 0903389 discloses an anti-fouling composition comprising a photocatalytic oxide, a silicone resin or silica and a water-repellent fluororesin.

According to WO 02/074870, a further improvement is obtained by providing an anti-fouling composition comprising a fluorinated polymer fluid containing alkyl or alkoxy groups. However, fluorinated polymer or oligomer fluids containing alkyl or alkoxy groups have the disadvantage of not being suitable for clear coatings, since coatings containing such fluids are opaque and have a hazy or milky appearance.

The present invention provides an antifouling coating composition having a low surface energy, having suitable elastic properties, reducing the settlement of fouling organisms and their adhesive strength, and being useful as a clear coat without a hazy or milky appearance.

The present invention relates to an antifouling coating composition comprising (i) a curable polymer and (ii) an organopolysiloxane polymer represented by the following general formula:

wherein:

r1 may be the same or different and are selected from alkyl, aryl and alkenyl, optionally substituted with amine groups; formula OR⁵Wherein R is⁵Is hydrogen or C_1-6An alkyl group; and a functional group of formula (I):

-R⁶-N(R⁷)-C(O)-R⁸-C(O)-XR⁹ (I)

wherein

R⁶Selected from the group consisting of alkyl groups having 1 to 12 carbon atoms, hydroxyalkyl groups, carboxyalkyl groups and polyoxyalkylene groups having up to 10 carbon atoms;

R⁷selected from the group consisting of hydrogen, alkyl groups having 1 to 6 carbon atoms, hydroxyalkyl groups, carboxyalkyl groups and polyoxyalkylene groups having 1 to 10 carbon atoms; r⁷Can be reacted with R⁸The bond forms a ring;

R⁸is an alkyl group having 1 to 20 carbon atoms;

R⁹is hydrogen or alkyl having 1 to 10 carbon atoms, optionally substituted with oxygen-or nitrogen-containing groups;

x is selected from O, S and NH;

provided that at least one R1 group in the organopolysiloxane polymer is a functional group of formula (I) above or a salt derivative thereof;

r2 may be the same or different and are selected from alkyl, aryl and alkenyl;

r3 and R4, which may be the same or different, are selected from the group consisting of alkyl, aryl, capped or uncapped polyoxyalkylene, alkaryl, aralkylene, and alkenyl;

a is an integer of 0 to 50,000;

b is an integer of 0 to 100; and is

a + b is at least 25.

R2, R3 and R4 are preferably independently selected from methyl and phenyl, more preferably methyl.

R⁶Preferably an alkyl group having 1 to 12, more preferably 2 to 5 carbon atoms.

R⁷Preferably hydrogen or alkyl having 1 to 4 carbon atoms.

R⁸Preferably an alkyl group having 2 to 10 carbon atoms.

R⁹Preferably hydrogen or alkyl having 1 to 5 carbon atoms.

X is preferably an oxygen atom.

a + b is preferably 100-300.

In one embodiment, R⁷Is hydrogen and R⁸Is an alkyl group having 1 to 20, preferably 2 to 10, more preferably 2 to 5 carbon atoms. Examples of such functional groups are: 1-butyric acid-4-amidopropyl group:

and 1-decanoic acid-10-amidopropyl:

in another embodiment, R⁷And R⁸The bond forms a pyrroline ring. Examples of functional groups of this embodiment are 1-amido-3-carboxypyrrolidone-1-propyl:

and 1-amido-3-methoxypyrrolidone-1-propyl:

in a preferred embodiment, the organopolysiloxane polymer is present as a fluid in the coating composition and in the coating obtained by curing the coating composition.

Within the scope of the present invention, the fluid material is prepared according to ASTM (1996) D4359-90: standard Test methods for determining whether a Material Is a Liquid or a Solid are defined. According to this test, the material is kept in a tightly closed container at 38 ℃. The lid is removed and the container is inverted. The flow of material from the container is observed to determine whether it is a solid or a liquid. A total of 50mm or less of material flowed in 3min was considered solid. Otherwise it is considered as liquid.

Preferably, the viscosity of the (fluid) organopolysiloxane polymer is from 5 to 1,500cSt at 25 ℃.

Suitable organopolysiloxane polymers can be prepared according to US 6,565,837.

Preferably the organopolysiloxane polymer does not react with the curable polymer also present in the coating composition and does not participate in any crosslinking reaction.

Within the present description, the term "organopolysiloxane polymer" is understood to include organopolysiloxane polymers and organopolysiloxane oligomers.

In a preferred embodiment, the organopolysiloxane polymer has a weight average molecular weight of about 500-15,000. When the molecular weight exceeds 15,000, the antifouling property of the coating is impaired.

The organopolysiloxane polymer is preferably present in the coating composition of the present invention in an amount of at least 1% by weight, more preferably at least 3% by weight, most preferably at least 5% by weight. The coating composition preferably does not contain more than 40 wt.% of organopolysiloxane polymer, more preferably not more than 20 wt.%, most preferably not more than 10 wt.%. All weight percents are based on the total weight of the coating composition.

The coating composition of the present invention also comprises a curable polymer. Preferably the polymer is an organosiloxane-containing polymer. More preferably, the organosiloxane-containing polymer comprises repeating units of the general structure- [ SiR 'R' -O ] -, wherein R 'and R' are independently selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, and alkenyl. It is particularly preferred that R 'and R' are independently selected from methyl and phenyl. Even more preferably, both R 'and R' are methyl. Cyclic polydiorganosiloxanes similar to those of the above formula may also be used.

More specific examples of suitable organosiloxane-containing polymers are dihydroxyl-functionalized polydimethylsiloxanes and silicone-acrylic hybrid polymers. The most preferred organosiloxane-containing polymers are polymers containing siloxane groups that are substantially free of carbon in the backbone (meaning: containing less than 1% by weight carbon), such as Polydimethylsiloxane (PDMS). Other suitable polymers are those disclosed in WO 99/33927, in particular the polymers disclosed on page 12, lines 23 to 31, i.e.organohydrogenpolysiloxanes or polydiorganosiloxanes. The polysiloxane may, for example, comprise copolymers of diorganosiloxane units with organohydrogensiloxane units and/or with other diorganosiloxane units or homopolymers of organohydrogensiloxane units or homopolymers of diorganosiloxane units.

Polysiloxanes which can be crosslinked by hydrosilylation reactions can also be used as curable polymers in the coating compositions of the present invention. Such polysiloxanes are known as "hydride polysiloxanes" and are disclosed, for example, on page 3, lines 37 to 53 of EP874032-A2, i.e.of the formula R ' - (SiOR ') '₂)m-SiR″′₃Wherein each R 'is independently a hydrocarbon or fluorinated hydrocarbon group, at least two R' groups per molecule are hydrogen, and m has an average value of about 10 to 1,500. The hydride polysiloxane is preferably a hydrogenpolydimethylsiloxane. The hydride polysiloxane preferably has a number average molecular weight of about 1,000-28,000, corresponding to a value of m of about 13-380.

The curable polymer is preferably present in the coating composition of the present invention in an amount of at least 30 wt.%, more preferably at least 50 wt.%, most preferably at least 70 wt.%. The coating composition preferably does not contain more than 99 wt.% of curable polymer, more preferably not more than 90 wt.%, most preferably not more than 80 wt.%.

Preferably, the coating composition of the present invention further comprises one or more fillers, pigments, catalysts and/or solvents.

Examples of suitable fillers are barium sulfate, calcium carbonate, silica or silicates (e.g. talc, feldspar and china clay), aluminium pastes/flakes, bentonite or other clays. Some fillers may have a thixotropic effect on the coating composition. The proportion of fillers may be from 0 to 25% by weight, based on the total weight of the coating composition.

Examples of suitable pigments are black iron oxide and titanium dioxide. The proportion of pigments may be from 0 to 10% by weight, based on the total weight of the coating composition.

Suitable solvents include aromatic hydrocarbons, alcohols, ketones, esters and mixtures of the above solvents with each other or with aliphatic hydrocarbons. In order to minimize the use of solvents on the environmental floor, it is advantageous to use solutions which are as concentrated as possible and compatible with the coating technology used. The solids content of the coating composition is preferably at least 50% by weight, more preferably at least 70% by weight. The solids content is preferably not more than 95 wt.%, more preferably not more than 90 wt.%, most preferably not more than 80 wt.%.

Examples of suitable catalysts are carboxylates of various metals such as tin, zinc, iron, lead, barium and zirconium. The salts are preferably long-chain carboxylates, such as dibutyltin dilaurate, dibutyltin dioctoate, iron stearate, tin (II) octoate and lead octoate. Other examples of suitable catalysts include organobismuth and organotitanium compounds and organophosphates such as bis (2-ethylhexyl) hydrogen phosphate. Other possible catalysts include chelates, such as tin dibutylacetylacetonate. In addition, the catalyst may comprise a halogenated organic acid having at least one halogen substituent on a carbon atom in the alpha-position relative to the acid group and/or at least one halogen substituent on a carbon atom in the beta-position relative to the acid group, or a derivative which is hydrolysable under the condensation reaction conditions to form the acid.

Depending on the type of curable polymer, the coating composition may require a crosslinker. The presence of a cross-linking agent is only required if the curable polymer cannot be cured by condensation. Depending on the functional groups present in the polymer. In general, when the polymer contains alkoxy groups, the presence of a crosslinking agent is not required. If the polymer contains alkoxy-silyl groups, the presence of a small amount of condensation catalyst and water is generally sufficient to achieve adequate curing of the coating after application. For these compositions, atmospheric humidity is generally sufficient to induce cure, and it is generally not necessary to heat the coating composition after application.

The optional crosslinker may be a crosslinker comprising a functionalized silane and/or one or more oxime groups. Examples of such cross-linking agents are provided in WO 99/33927 page 19, line 9 to page 21, line 17. Mixtures of different crosslinking agents may also be used.

The antifouling coating compositions of the invention can be applied to a substrate by common techniques such as brushing, rolling or spraying (airless and conventional). To achieve proper adhesion to the substrate, the coating composition is preferably applied to the substrate coated with the primer layer. The primer layer can be any conventional primer/sealer coating system. Good results, particularly in terms of adhesion, were found when using a primer comprising an acrylic siloxy-functional polymer, a solvent, a thixotropic agent, a filler and optionally a moisture scavenger. Such a bottom layer is disclosed in WO 99/33927. The coating composition of the present invention may also be applied to a substrate containing an aged anti-fouling coating. Prior to applying the coating composition of the present invention to the aged layer, the aged layer is cleaned by high pressure water washing to remove any contamination. The primer layer disclosed in WO 99/33927 can be used as a tie layer between an aged coating layer and the coating composition of the present invention.

After the coating is cured, it can be immediately immersed and immediately protected against fouling and fouling release. As mentioned above, the resulting coatings have very good anti-fouling and fouling release properties. This makes the coating composition of the invention very suitable for use as an anti-fouling or non-fouling coating for marine applications. The coating composition can be used for dynamic and static structures such as hulls of ships, buoys, drilling platforms, oil production rigs, and pipelines that are submerged in water. The coating composition can be applied to any substrate used in these structures, such as metal, concrete, wood, or fiber reinforced resins.

Examples

Synthesis example a: synthesis of 1-methoxy pyrrolidone-3-amido-1-propyl dimethyl silicone polymer

The 1-amido-3-carboxypyrrolidone-1-propylpolydimethylsiloxane fluid was added to 500ml of methanol and 0.28g of p-toluenesulfonic acid. The resulting mixture was heated at 60 ℃ under reflux for 5 hours. This results in the formation of two layers. The supernatant was removed and concentrated under vacuum to leave an orange oil.

Synthesis example B: synthesis of 1-butyric acid-4-amido propyl dimethyl silicone polymer

Succinic anhydride (1g, 0.01mol) was dissolved in tetrahydrofuran and the mixture was added dropwise over a period of 20 minutes to 43.7g (0.01mol) of amino-functionalized PDMS. The resulting solution was heated to 80 ℃ and refluxed for 2 hours. This results in the formation of two layers. The supernatant was removed and concentrated under vacuum to leave an oil.

Synthesis example C: synthesis of 1-decanoic acid-10-amido propyl polydimethylsiloxane

Sebacic acid (2g, 0.01mol) was dissolved in 60ml tetrahydrofuran and the mixture was added dropwise to 43.7g (0.01mol) amino-functionalized PDMS with stirring. The resulting solution was heated to 80 ℃ and refluxed for 5 hours. This results in the formation of two layers. The supernatant was removed and concentrated under vacuum to leave an oil.

Example 1

A three-component coating composition having the following formulation was prepared:

component 1 (matrix):

33g3g5g

alpha, omega-hydroxy-functionalized polydimethylsiloxane (dynamic viscosity 35 poise) 1-amido-3-dimethylaminopropylamidopyrrolidone-1-propylpolydimethylsiloxane xylene

Component 2 (curing agent):

1.7g5g

tetraethyl orthosilicate xylene

Component 3 (catalyst solution):

0.28g2.54g

dibutyl tin dilaurate 2, 4-pentanedione

Example 2

A three-component coating composition having the following formulation was prepared:

component 1 (matrix):

65g9g

alpha, omega-hydroxy-functionalized polydimethylsiloxane xylenes

Component 2 (curing agent):

3g5g9.5g

tetraethyl orthosilicate 1-amido-3-carboxypyrrolidone-1-propylpolydimethylsiloxane xylene

Component 3 (catalyst solution):

0.5g4.8g

dibutyl tin dilaurate 2, 4-pentanedione

Example 3

A three-component coating composition having the following formulation was prepared:

component 1 (matrix):

33g4.5g

alpha, omega-hydroxy-functionalized polydimethylsiloxane xylenes

Component 2 (curing agent):

1.5g2.5g4.5g

tetraethyl orthosilicate 1-methoxypyrrolidone-3-amido-1-propylpolydimethylsiloxane xylene

Component 3 (catalyst solution):

0.25g2.4g

dibutyl tin dilaurate 2, 4-pentanedione

Example 4

A three-component coating composition having the following formulation was prepared:

component 1 (matrix):

3.3g4.5g

alpha, omega-hydroxy-functionalized polydimethylsiloxane xylenes

Component 2 (curing agent):

1.5g2.5g4.5g

tetraethyl orthosilicate 1-butyric acid-4-amidopropyl polydimethylsiloxane xylene

Component 3 (catalyst solution):

0.25g2.4g

dibutyl tin dilaurate 2, 4-pentanedione

Example 5

A two-component coating composition having the following formulation was prepared:

component 1:

component 2 (curing agent):

example 6

A two-component coating composition having the following formulation was prepared:

component 1:

component 2 (catalyst solution):

0.04g7.5g

dibutyl tin dilaurate trimethylbenzene

Example 7: anti-fouling test

The compositions of examples 2, 3 and 4 were applied by brush (to a dry film thickness of about 300 μm) to 60cm x 60cm marine plywood panels primed with both an epoxy primer and an acrylic tie coat. Six samples of each composition were applied by brush. Standard coatings and non-toxic controls were applied as references to evaluate the relative performance of the coatings of the invention and the amount and diversity of the distribution of contaminant deposition.

The test panels were submerged from rafts designed to submerge the experimental test surface and the conditions were representative of those experienced by the hulls of cruise or tanker ships.

The panel was attached to the test frame and suspended vertically 0.5-1.5m below the water surface at each test site. The panels were periodically checked for the presence of biofouling and coating integrity.

The test sites include: newton Ferrers, UK showing typical contamination of all major contaminating species and Brattons with significant shell contamination (hard animals), sweden.

The pollution coverage was evaluated with four main ecologically derived pollution species: microbial contamination, weeds, mollusks and hard animals, and visual analysis of the four contaminating species provides sufficient information to distinguish coating performance while allowing some general comparison between test sites.

The results are shown in the table below. The data in the table refer to the total contamination coverage (expressed as a percentage) of the test panel surface.

Watch (A)

	Brattons, Sweden for 11 weeks	Brattons, Sweden for 22 weeks	Newton Ferrs, UK16 weeks
				Example 2	75.83	14.20	33.33
Example 3	46.67	23.20	32.50
				Example 4	83.83	33.40	75.67
Standard antifouling coatings	100.00	31.20	95.50
				Only corrosion resistant primer layer	100.00	100.00	99.67

The table shows that after 4 months of immersion in UK water and 5 months of immersion in swedish water, the accumulated contamination is significantly less than that of the control substrate coated only with the corrosion resistant underlayer and less than that of the standard substrate. Any contamination on the coatings of examples 2-4 could be very easily removed by light rubbing, whereas accumulated contamination on the control substrate could not be removed in a similar manner.

In addition, it should be noted that all of the coatings of the present invention are transparent and do not have a hazy or milky appearance.

Claims (10)

1. An antifouling coating composition comprising a curable polymer and an organopolysiloxane polymer represented by the general formula:

wherein:

r1 may be the same or different and are selected from alkyl, aryl and alkenyl, optionally substituted with amine groups; formula OR⁵Wherein R is⁵Is hydrogen or C_1-6An alkyl group; and a functional group of formula (I):

-R⁶-N(R⁷)-C(O)-R⁸-C(O)-XR⁹ (I)

wherein

R⁶Selected from the group consisting of alkyl groups having 1 to 12 carbon atoms, hydroxyalkyl groups, carboxyalkyl groups and polyoxyalkylene groups having up to 10 carbon atoms;

R⁷selected from the group consisting of hydrogen, alkyl groups having 1 to 6 carbon atoms, hydroxyalkyl groups, carboxyalkyl groups and polyoxyalkylene groups having 1 to 10 carbon atoms; r⁷Can be reacted with R⁸The bond forms a ring;

R⁸is an alkyl group having 1 to 20 carbon atoms;

R⁹is hydrogen or alkyl having 1 to 10 carbon atoms, optionally substituted with oxygen-or nitrogen-containing groups;

x is selected from O, S and NH;

with the proviso that at least one R1 group in the organopolysiloxane polymer is a functional group of formula (I) above or a salt derivative thereof;

r2 may be the same or different and are selected from alkyl, aryl and alkenyl;

r3 and R4, which may be the same or different, are selected from the group consisting of alkyl, aryl, capped or uncapped polyoxyalkylene, alkaryl, aralkylene, and alkenyl;

a is an integer of 0 to 50,000; and is

b is an integer of 0 to 100; and is

a + b is at least 25.

2. The coating composition according to claim 1, wherein in one embodiment, R⁷Is hydrogen and R⁸Is an alkyl group having 1 to 20 carbon atoms.

3. The coating composition according to claim 1, wherein R⁷And R⁸The bond forms a pyrrolidone-type ring.

4. A coating composition according to any one of the preceding claims wherein the organopolysiloxane polymer is a fluid.

5. The coating composition according to any one of the preceding claims, wherein the organopolysiloxane polymer has a weight average molecular weight of 500-15,000.

6. A coating composition according to any one of the preceding claims, wherein the curable polymer is an organosiloxane-containing polymer.

7. A coating composition according to any one of the preceding claims wherein the curable polymer comprises repeating units of the general structure- [ SiR 'R "-O ] -wherein R' and R" are independently selected from the group consisting of hydrogen, alkyl, aryl, aralkyl and vinyl.

8. The coating composition of claim 7, wherein R' and R "are independently selected from methyl and phenyl.

9. Use of a coating composition according to any one of the preceding claims to inhibit contamination of a substrate in an aquatic environment.

10. A coated substrate obtained by applying the coating composition of any one of claims 1 to 8 to a substrate and subsequently curing the coating composition.