Anti-fouling agents, process for their preparation ,their use and anti-fouling coating compositions

The present invention relates to antifouling agents, a process for the production and their use and antifouling coatings produced therefrom.

Antifouling coatings are used to protect objects from fouling, especially hulls, sieves, nets, structures, quay systems and signaling systems that come into contact with sea or brackish water.

The formation of fouling is a major problem, particularly for ships, since this increases the frictional resistance and, due to the increased energy consumption and frequent dry dock stays, the operating costs are significantly increased. For this reason, anti-fouling coatings have been used for a long time to prevent vegetation from algae, barnacles, tube worms, mussels or others.

One can differentiate between principally biocide-containing and biocide-free antifouling coatings.

Antifouling coatings that contain biocides are state of the art. The biocides kill the growth-forming organisms. Common antifouling biocides are organic tin compounds or copper, antimony and bismuth compounds. The night part of these biocides is their low environmental impact. Heavy metal-containing antifouling biocides are particularly problematic since they cause contamination of the lake water and the seabed, particularly in the area of ​​ports.

Biocide-free antifouling coatings have non-stick properties, ie the seizure of marine organisms should be physically prevented. The prior art is, for example, antifouling coatings based on organosilicon liquids, liquid paraffins or fluorinated oils in combination with organopolysilicon polymers, in particular silicone lastomers (see US Pat. No. 5,298,060 and DE-A 26 01 928). Also state of the art are copolymers of organic polymers and silicone polymers. US Pat. No. 4,910,252 and WO 93 13179 describe biocide-free antifouling coatings which contain trialkoxysilane group-containing polymers, preferably acrylates and linear siloxane polymers. EP 329 375 claims a coating composition made of silicone polymers and polyurethane and / or polyurea. WO 98 38251 describes organically inorganic hybrid materials made from at least one organic polymer, inorganic (nano) particles and polyfunctional organosilanes.

The principle of action of the cited antifouling coatings is based on the low surface tension of silicone-containing coatings and / or more or less controlled release of slip additives which are intended to prevent the sticking of marine organisms. However, the effectiveness of such antifouling coatings is limited. A further disadvantage is the low mechanical strength and often insufficient adhesion to corrosion protection coatings, which may make it necessary to apply an additional primer layer.

The present invention is therefore based on the object of providing improved antifouling agents which do not have the disadvantages mentioned of known antifouling agents and whose antifouling properties can already be achieved without biocides.

It has now surprisingly been found that antifouling agents which contain at least one multifunctional carbosilane and / or siloxane (A) and, if appropriate, at least one further alkoxysilane (B), a solvent (C), catalyst (D), inorganic nanoparticles (E) and optionally contain further additives (G) which fulfill the object on which the invention is based.

The antifouling agents according to the invention are room-temperature hardening and are distinguished by good adhesion to corrosion protection coatings and high mechanical strength. An additional primer layer is therefore not necessary. They show an anti-fouling effect and effectively protect objects against fouling, in particular ship hulls, sieves, nets, structures, quay systems and signaling systems which come into contact with sea or brackish water.

The invention therefore relates to antifouling agents, which at least<ul id="ul0001" list-style="dash"><li>a multifunctional carbosilane and / or siloxane (A) of the general formula I         Q [(CH₂)_mSiR¹_nX_(3-n)]_p     (I) and / or its (partial) condensation product With<dl id="dl0001"><dt>R¹ =</dt><dd>C.₁-C₁₈-Alkyl and / or C₆-C₂₀-Aryl, where R¹ can be the same or different within the molecule,</dd><dt>X =</dt><dd>a residue selected from the group OH, C₁-C₄-Alkoxy, C₆-C₂₀Aryloxy or C₁-C₆Acyloxy, preferably OH, methoxy or ethoxy,</dd><dt>n =</dt><dd>0 up to 2</dd><dt>m =</dt><dd>2nd until 6</dd><dt>p =</dt><dd>an integer ≥ 2 and</dd><dt>Q =</dt><dd>either a linear or cyclic silane or siloxane, an unsubstituted hydrocarbon or a hydrocarbon substituted by at least one member of the group O, N, S, P,</dd></dl></li><li>and optionally at least one alkoxysilane (B),</li><li>organic solvents (C) and / or water,</li><li>a catalyst (D),</li><li>inorganic nanoparticles (E), and</li><li>optionally contain further additives (F).</li></ul>

Multifunctional carbosilanes (A) in the sense of the invention are silanes of the general formula II         R²_4-pThemselves₂)_mSiR¹_nX '_(3-n)]_p     (II) or their partial condensation products, in which<dl id="dl0002"><dt>p =</dt><dd>4, 3 or 2, preferably 4,</dd><dt>X '=</dt><dd>a remainder corresponds to the group, C₁-C₄-Alkoxy, C₆-C₂₀Aryloxy, preferably methoxy or ethoxy,</dd><dt>R² =</dt><dd>C.₁-C₁₈ Alkyl and / or C₆-C₂₀-Aryl mean and m, n and R¹</dd></dl> have the meaning given above.

In a further embodiment of the invention, the multifunctional carbosiloxanes (A), composed of at least two building blocks, are selected from monofunctional siloxane units M of the general formula R.₃SiO₁₂, difunctional siloxane units D of the general formula R₂SiO_2/2 and / or trifunctional siloxane units T of the general formula RSiO_3/2 and optionally additionally tetra-functional siloxane units Q of the general formula SiO_4/2 and / or their condensation and / or partial condensation products. These can be substituted with at least one member of the group O, N, S, P. R has the meaning of C₁-C₁₈ Alkyl and / or C₆-C₂₀-Aryl, where R can be the same or different within the molecule.

The siloxanes according to the invention preferably have a number average molecular weight between 300 and 5000.

In a preferred embodiment, the multifunctional carbosiloxanes (A) are compounds of the formula III<chemistry id="chem0001" num="0001"><img file="EP0967253A2_D0001.tif" /></chemistry> or their partial condensation products, where<dl id="dl0003" compact="compact"><dt>a =</dt><dd>3rd to 6, preferably 4, and</dd></dl> R¹, X, m and n have the meaning given in formula (I).

The multifunctional carbosiloxanes (A) contained in the antifouling agent according to the invention are very particularly preferably compounds of the formula (IV) and / or (V)<chemistry id="chem0002" num="0002"><img file="EP0967253A2_D0002.tif" /></chemistry> or their partial condensation products.

The multifunctional carbosilanes and / or siloxanes are preferably prepared by the processes described in DE-A 1 960 3241 and DE-A 1 971 1650 by hydrosilylating the corresponding vinyl compound with a chlorosilane and subsequent hydrolysis or alcoholysis.

The multifunctional carbosilanes (A) can also heterocyclic compounds, such as. B the compound of the formula (VI)<chemistry id="chem0003" num="0003"><img file="EP0967253A2_D0003.tif" /></chemistry> be.

This <i>Tris</i>- [3- (Trimethoxysilyl) propyl] isocyanurate (formula VI) is available, for example, from Witco under the trade name Silquest® Y-11597.

Likewise, the multifunctional carbosilanes (A) reaction products of preferably aliphatic polyols, such as 2,2-bis (hydroxymethyl) -1,3-propanediol), with silanes of the formula (VII)         ONC- (CH₂)_mSiR¹_nX_(3-n)     (VII) be, where R¹, X, m and n have the meaning given in formula (I), and / or reaction products of preferably aliphatic polyisocyanates, such as polyisocyanates based on hexamethylene diamine (HDI), with silanes of the formula (VIII)         MR³) N-CH₂)_mSiR¹_nX_(3-n)     (VIII) where R¹, X, m and n have the meaning given in formula (I) and R³ a C₁-C₄-Alkyrest means to be.

Condensation or partial condensation products within the meaning of the invention are taken to mean those compounds which are formed, for example, by reaction of 2 radicals X of the general formula (I) with elimination of water or alcohol.

Alkoxysilanes (B) for the purposes of the invention are compounds of the general formula (IX)         R⁴_bSiY_(4-b)     (IX) With<dl id="dl0004"><dt>R⁴ =</dt><dd>same or different monovalent C within the molecule₁-C₁₄-Alkyl- or C₆-C₂₀Aryl radicals which may optionally be substituted by a member of the group O, N, S, P,</dd><dt>Y =</dt><dd>a hydrolyzable group, preferably C₁-C₈-Alkoxy or C₂-C₈ Acyloxy, very particularly preferably C₁-C₂-Alkoxy and</dd><dt>b =</dt><dd>0, 1, 2 or 3, preferably 0 or 1</dd></dl> and / or a (partial) condensation product of at least one organosilane of the formula IX.

As a preferred alkoxysilane (B), the antifouling agent according to the invention contains tetraethoxysilane, methyltrimethoxysilane and / or methyltriethoxysilane, very particularly preferably tetraethoxysilane or a (partial) condensation product of the silanes mentioned, preferably of tetraethoxysilane. However, other silanes of the formula IX, mixtures of such silanes, (partial) condensation products of these silanes or (partial) condensation products of mixtures of the silanes mentioned can also be used. Examples of suitable silanes of the formula IX are Si (OR<i>'</i> )₄, R<i>''</i> Si (OR<i>'</i> )₃, R<i>''</i> Si (OOCR<i>'</i> )₃ with R<i>'</i> and R<i>''</i> independently of one another methyl, ethyl, (iso) propyl, (iso) butyl, (iso) pentyl, (iso) hexyl or (iso) octyl. The alkoxysilanes (b) are particularly preferably used as (partial) condensates.

Solvent (C) is preferably a water-miscible organic solvent such as isopropanol, optionally in a mixture with water, the latter being preferred.

All condensation catalysts known in silicone chemistry, such as, for example, in W. Noll, Chemistry and Technology of Silicones, chap. 5.4, ​​p. 179, Verlag Chemie, Weinheim, 1968, can be used. An acid is preferably used as the catalyst, particularly preferably<i>para-</i>Toluenesulfonic acid.

The agent according to the invention can additionally contain inorganic nanoparticles (E) and / or further additives (F).

Inorganic nanoparticles (E) in the sense of the invention are, for example, metal or semimetal oxides or oxide hydrates with an average particle diameter (number average) from 5 to 100 nm, preferably from 5 to 50 nm, determined by means of ultracentrifugation. Examples of the nanoparticles according to the invention are silica sols (SiO₂), Boehmite brine (Al (O) OH) and / or TiO₂-Sole. The inorganic nanoparticles according to the invention can also be prepared in situ by hydrolysis of suitable molecular precursors, such as, for example, the corresponding metal or transition metal alcoholates or acetylacetonates and / or their (partial) hydrolysates. The inorganic nanoparticles can also be surface-modified by the known processes, for example by reaction with hexamethyldisilazane. Silica sols dispersed in an organic solvent with an average particle size (number average) of 5 to 100 nm are particularly preferred, very particularly preferably with an average particle size of 5 to 50 nm. The particle size was determined by ultracentrifugation.

The agents according to the invention can contain, as further additives (F), inorganic pigments, organic pigments, dyes, which are preferably not soluble in (sea) water, and / or customary auxiliaries such as fillers, solvents, plasticizers, catalysts, inhibitors, adhesives, paint additives and / or contain common dispersing agents.

It is of course also possible to add known release or slip additives, such as organosilicone liquids, liquid paraffins and / or fluorinated oils, to the agent according to the invention for use in antifouling.

Biocides such as triazoles, imidazoles, naphthalene derivatives etc. can also be added to the antifouling agent. However, the advantages of the mixture according to the invention are already achieved without it.

The agent according to the invention is preferably provided in organic solvents. However, it is also possible to prepare the agent according to the invention as an aqueous formulation. In this case it is advantageous if the components (E) and (F) contained in the agent according to the invention are also added as an aqueous formulation or if they are compatible with the aqueous agent.

In a preferred embodiment of the invention, the antifouling agent according to the invention has the following composition:<ul id="ul0002" list-style="dash"><li>2nd up to 100% by weight, preferably 10 to 70% by weight, of at least one multifunctional carbosilane and / or siloxane (A), preferably one multifunctional carbosilane and / or siloxane of the formulas (II) to (V), very particularly preferably a multifunctional carbosiloxane of the formula (IV) and / or (V) or their (partial) condensation products,</li><li>0 up to 60% by weight, preferably 10 to 40% by weight of at least one alkoxysilane (B), preferably an alkoxysilane of the formula IX, very particularly preferably tetraethoxysilane or a condensation product of at least one silane of the formula IX,</li><li>0 up to 70% by weight, preferably 20 to 60% by weight of at least one solvent (C), preferably a water-dilutable solvent, particularly preferably an organic solvent in a mixture with water,</li><li>0.01 to 2% by weight, preferably 0.02 to 1.0% by weight, of at least one catalyst (D), preferably an acid, particularly preferably para-toluenesulfonic acid,</li><li>0 up to 20% by weight, preferably 3 to 15% by weight, of inorganic nanoparticles (E), with an average particle diameter (number average) of 5 to 100 nm, preferably 5 to 50 nm,</li><li>0 up to 50% by weight, preferably 0 to 30% by weight, further additives (F),</li></ul> with the proviso that the sum of components (A) to (F) is 100% by weight.

Another object of the present invention is the preparation of the agent according to the invention, the individual components (A) to (F) being stirred together. The individual components can be mixed together in any order using the stirring or dispersing methods known in the paint industry until a homogeneous solution or dispersion has formed. It proves to be advantageous if component (D) is added as the last component and the agent is stirred at 15 to 20 ° C. for 30 to 90 minutes before application. In a preferred embodiment of the invention, a storage-stable hydrolyzate / condensate is produced from components (B) to (D) with the addition of water. For the preparation of the hydrolyzate / condensate, it is preferred if 0.2 to 0.7 mol, preferably 0.4 to 0.6 mol, of water are added per mol of hydrolyzable group Y of the silanes (B) with the general formula (IX) . Details of the sol-gel process are described, for example, by CJ Brinker and W. Scherer in "Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing", Academic Press, New York (1990). The solvent (C) used to prepare the hydrolyzate and the reaction alcohol of the alkoxysilane (B) can be partially distilled off and / or replaced by another solvent after the reaction has ended. In this case, the hydrolyzate from (B) to (D) is mixed homogeneously with component (A) and, if appropriate, with components (E) and (F). The agent can be applied immediately.

In addition, the use of the antifouling agent according to the invention as an antifouling coating and this antifouling coating and its production is the subject of the invention.

The antifouling coatings produced with the agent according to the invention can be applied as the only anti-fouling coating or paint to the marine surface to be protected. The marine surfaces to be protected can also be provided with a primer with corrosion-preventing paints before the antifouling coating produced with the agent according to the invention is applied.

The antifouling agent according to the invention is preferably applied to a solid base by spraying, dipping, rolling or brushing.

<b>Examples</b>

<b>example 1</b>

37.4 g of tetraethoxysilane (TEOS ), 30 g of isopropanol and 8.2 g of 0.1 n p-toluenesulfonic acid. the reaction mixture is stirred for 60 min. A slightly exothermic reaction takes place during the reaction time. The viscosity of the agent according to the invention is 15 mPas at 23 ° C., the pot life is approximately 16 hours.

<b>Example 2</b>

In a beaker, 24.5 g of a (partial) condensation product of 1,3,5,7-tetramethyl-1,3,5,7-tetra (2-hydroxydimethylsilylethylene) -cyclotetrasiloxane are at a temperature of 19 ° C. 31.5 g of tetraethoxysilane (TEOS), 38.5 g of isopropanol and 5.3 g of 0.1 N p-toluenesulfonic acid were added in succession with stirring. The reaction mixture is stirred for 60 minutes. The viscosity of the agent according to the invention is 14 mPas at 23 ° C., the pot life is about 5 hours.

<b>Example 3</b>

In a beaker, 18.7 g of 1,3,5,7-tetramethyl-1,3,5,7-tetra (2-hydroxydimethylsilylethylene) cyclotetrasiloxane are added 12.1 in succession at a temperature of 19 ° C. with stirring g of tetraethoxysilane (TEOS), 29.6 g of isopropanol, 37.5 g of organosol (Bayer AG, 30% colloidal solution of silicon dioxide in isopropanol) and 2.1 g of 0.1 n p-toluenesulfonic acid. The reaction mixture was stirred at 19 ° C for 60 minutes. The viscosity of the agent according to the invention is 13 mPas at 23 ° C., the pot life was about 12 hours.

<b>Example 4</b>

4.1 Prehydroysate

1667 g of tetraethoxysilane (TEOS) and 2041 g of ethanol are placed in a three-necked flask equipped with a stirrer, internal thermometer, reflux condenser and dropping funnel, and 291.5 g of 0.1 N aqueous 4-toluenesulfonic acid are added with stirring. The reaction temperature rises to approx. 50 ° C. The reaction mixture is stirred for 24 hours. The hydrolyzate is stable in storage in a closed container for at least 6 months at room temperature.

4.2 Prehydroysate

114 g of tetraethoxysilane (TEOS), 330 g of organosol (Bayer AG, 30% colloidal solution of silicon dioxide in isopropanol) and 337 g of ethanol are placed in a three-necked flask equipped with a stirrer, internal thermometer, reflux condenser and dropping funnel, and 337 g of ethanol are added, and stirring is carried out with 20 g of 0.1 n aqueous 4-toluenesulfonic acid. The reaction mixture is stirred for 24 hours. The hydrolyzate is stable in storage in a closed container for at least 6 months at room temperature.

4.3 Prehydoysate

In a three-necked flask equipped with a stirrer, internal thermometer, reflux condenser and dropping funnel, 87.4 g of 0.05 N aqueous 4-toluenesulfonic acid are added to 500 g of tetraethoxysilane (TEOS) with stirring. The reaction temperature rises to approx. 67 ° C. After about 25 minutes, the initially cloudy reaction mixture clears up. After the temperature has dropped again to 30 ° C., 100 g of 1-pentanol are added and ethanol is distilled off at 60 ° C. under a slight vacuum. A further 200 g of 1-pentanol are added dropwise during the distillation. The hydrolyzate is adjusted to 30% by weight solids with 1-pentanol. It is stable for at least 6 months in a closed container at room temperature.

<b>Example 5</b>

In a beaker 100 g of pre-hydrolyzate from Example 4.1 with 66 g of a 75% solution (w / w) of a (partial) condensation product of 1,3,5,7-tetramethyl-1,3,5,7-tetra were stirred (2-hydroxydimethylsilylethylene) cyclotetrasiloxane combined in n-butanol. The agent according to the invention can be applied immediately. The pot life is approximately 45 minutes.

<b>Example 6</b>

In a beaker 100 g of pre-hydrolyzate from Example 4.1 are combined with 66 g of a (partial) condensation product of 1,3,5,7-tetramethyl-1,3,5,7-tetra (2-diethoxymethylsilylethylene) cyclotetrasiloxane. The agent according to the invention can be applied immediately. The pot life is approximately 12 hours.

<b>Example 7</b>

100 g of pre-hydrolyzate from Example 4.2 with 40 g of a 75% solution (w / w) of a (partial) condensation product of 1,3,5,7-tetramethyl-1,3,5,7-tetra are placed in a beaker with stirring (2-hydroxydimethylsilylethylene) cyclotetrasiloxane combined in n-butanol. The agent according to the invention can be applied immediately. The pot life is approximately 12 hours.

<b>Example 8</b>

60 g of pre-hydrolyzate from Example 4.3 with 80 g of a (partial) condensation product of 1,3,5,7-tetramethyl-1,3,5,7-tetra (2-diethoxymethylsilylethylene) cyclotetrasiloxane and 18 g of a are baked in a beaker with stirring 0.1 molar solution of 4-toluenesulfonic acid combined in ethanol. The agent according to the invention can be applied immediately. The pot life is approximately 48 hours.

<b>Example 9</b>

In a three-necked flask with magnetic stirrer, internal thermometer, reflux condenser and patio heater, under N₂Combined atmosphere 12.2 g (0.075 mol) of pentaerythritol, 74.1 g (0.3 mol) of Dynasilan® A-1310 (from Witco) and 100 g of methoxypropyl acetate. The reaction mixture is stirred at 100 ° C. for 24 h. A clear solution is created. The solvent is distilled off at a pressure of 10 mbar and a temperature of 140 ° C. The product was obtained as a clear, highly viscous liquid.<dl id="dl0005" compact="compact"><dt>Yield:</dt><dd>59 g (70% of theory)</dd><dt>Molar mass:</dt><dd>1124.15 g</dd></dl><ul id="ul0003" list-style="none" compact="compact"><li>¹H-NMR ([d6] -DMSO): δ = 0.46 ppm (tr, 8H, SiC<u><b>H</b></u>₂CH₂CH₂NH), δ = 1.15 ppm (tr, 24H, OC<u><b>H</b></u>₂CH₃), δ = 1.45 ppm (m, 8H, SiCH₂C.<u><b>H</b></u>₂CH₂NH), δ = 2.95 ppm (m, 8H, SiCH₂CH₂C.<u><b>H</b></u>₂NH), δ = 3.74 ppm (q, 36H, OCH₂C.<u><b>H</b></u>₃), d = 3.93 ppm (m, 8H, C<u><b>H</b></u>₂OC (O) NH), δ = 7.1 ppm (m, 4H, OC (O) N<u><b>H</b></u>CH₂).</li></ul>

<b>Example 10</b>

10.0 g of tetraethoxysilane (TEOS), 24 g of isopropanol, 17.5 g of organosol (Bayer AG, 30% colloidal solution of silicon dioxide and isopropanol) and were added to 38.5 g of the multifunctional carbosilane prepared in Example 9 with stirring Added 5.0 g of 0.1 n p-toluenesulfonic acid. The reaction mixture is stirred at 19 ° C for 60 minutes. The viscosity of the agent according to the invention is 13 mPas at 23 ° C., the pot life is about 7 hours.

<b>Examples of use</b>

The antifouling agents according to the invention were applied by brushing or pneumatic spraying at a spray pressure of 4 bar and 2 crossways on test plates measuring 650 x 250 mm, which were coated with a zinc-containing epoxy corrosion protection primer (available, for example, under the trade name Oldopox®377-0066, from Relius) Coatings) were coated in a dry layer thickness of 50 microns, applied and dried for 7 days at room temperature. The test plates were swapped out on a raft in Wilhelmshaven. After 3 months there was almost no fouling on the panels. Fouling, such as algae or barnacles, could be removed by rubbing lightly with a cloth.

The antifouling coatings according to the invention have good mechanical resistance, high hardness (pencil hardness 3 H to 7 H) and adhere very well to the corrosion protection base used.