A low surface energy marine antifouling coating

Abstract

The present invention provides a low-surface-energy marine antifouling coating comprising the following components, calculated by weight: 50-80 parts of a silicone-modified polyurethane prepolymer, 5-15 parts of silica nanoparticles, 5-15 parts of a fluorinated cage-type polysilsesquioxane, 1-5 parts of a curing agent, and 5-25 parts of a first solvent. The coating formed by the coating has both low surface energy and excellent antifouling properties. Furthermore, the coating also exhibits good mechanical properties, enabling long-term use in complex marine environments.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a low-surface-energy marine antifouling coating. Background Art

[0002] Ships are the primary means of transport in the ocean. However, biofouling in the marine environment severely limits the service life of ships and even threatens their navigational safety. With increasing environmental awareness, the most cost-effective solution to marine biofouling is the development of new, highly efficient, and environmentally friendly antifouling coatings. Fouling-removing antifouling coatings have become a research focus because they meet environmental requirements by not releasing toxic biocides. Low-surface-energy antifouling coatings, in particular, hold great promise for development due to the unique properties of their resins.

[0003] However, due to the complex marine environment, low surface energy antifouling coatings are often required to possess not only low surface properties but also excellent mechanical properties, such as hardness and impact resistance. Currently available low surface energy antifouling coatings can indeed reduce the surface properties of the coating to a certain extent, providing some antifouling performance. However, due to improper raw materials or formulation design, these coatings suffer from poor mechanical properties and other drawbacks, making them unsuitable for use in complex marine environments.

[0004] Therefore, providing a coating with low surface energy, good antifouling performance and excellent mechanical properties is of great significance for marine operations. Summary of the Invention

[0005] In order to solve the problems and shortcomings of the prior art, the present invention provides a low surface energy marine antifouling coating. The coating formed by the coating has both low surface energy and excellent antifouling performance. At the same time, the coating formed by the coating also has good mechanical properties and can meet the needs of long-term use in complex marine environments.

[0006] The invention provides a low surface energy marine antifouling coating, which comprises the following components, calculated by weight: 50 to 80 parts of organosilicon-modified polyurethane prepolymer, 5 to 15 parts of silicon dioxide nanoparticles, 5 to 15 parts of fluorinated cage-type polysilsesquioxane, 1 to 5 parts of a curing agent, and 5 to 25 parts of a first solvent.

[0007] Using silicone polyurethane prepolymer as the main resin of the coating, silicone can effectively reduce the surface energy of the coating and improve the coating's anti-fouling ability. However, the mechanical properties of silicone resins are often poor. By combining silicone with polyurethane, the resulting resin can take into account both the anti-fouling and mechanical properties of the coating. The introduction of silica nanoparticles and fluorinated cage-type polysilsesquioxanes can further improve the mechanical properties of the coating. Fluorinated cage-type polysilsesquioxanes contain fluorine and silicon atoms, which can further reduce the surface properties of the coating and improve the coating's anti-fouling ability. At the same time, silica nanoparticles and fluorinated cage-type polysilsesquioxanes contain silicon atoms and are also silicon-containing substances. They can form a good dispersion system with the silicone polyurethane prepolymer, promote the synergistic effect of the three substances: silicone polyurethane prepolymer, silica nanoparticles, and fluorinated cage-type polysilsesquioxane, and further optimize the coating's anti-fouling and mechanical properties. Moreover, these three substances in the above-mentioned proportion can better balance the anti-fouling performance and mechanical properties of the coating, so that the coating can be used for a long time in a complex marine environment, and improve the long-term protection performance of the coating for ships.

[0008] In addition, it should be noted here that, in current low surface energy marine antifouling coatings, many adopt organic fluorine resins, because organic fluorine resins can well reduce the surface properties of coating, but organic fluorine resins are expensive, have a high forming temperature, and the carbon chain rigidity in the fluorine-containing resin is larger, and higher energy is needed when cleaning the organisms attached to the surface, so in actual applications, there are also many restrictions, if more organic fluorine resins are contained in the coating, problems such as practical application difficulties may be caused. And the matrix resin adopted in the present invention is an organosilicon polyurethane resin, which introduces fluorine atoms by introducing fluorinated cage-type polysilsesquioxanes, and content is less, can not affect practical application, and cost is lower, and further optimizes coating performance by introducing silicon dioxide nanoparticles. These three substances, under a specific ratio, can, without using organic fluorine resins, make coating have excellent antifouling properties, and possess good mechanical properties simultaneously.

[0009] Preferably, the first solvent includes at least one of acetone and n-butyl acetate.

[0010] Preferably, the preparation of the fluorinated cage-type polysilsesquioxane comprises the following steps: mixing a perfluoroalkyloxysilane with a second solvent, adjusting the pH of the resulting mixed system to 11-12, and reacting with a reflux reaction at 95-105° C. for 1-1.5 hours to obtain the fluorinated cage-type polysilsesquioxane; the perfluoroalkyloxysilane comprises at least one of perfluoroalkyltrimethoxysilane and perfluoroalkyltriethoxysilane.

[0011] Preferably, the second solvent comprises tetrahydrofuran.

[0012] Preferably, the perfluoroalkyloxysilane is perfluoroalkyltriethoxysilane, and the number of carbon atoms in the perfluoroalkyltriethoxysilane is not less than 12. The use of perfluoroalkyltriethoxysilane with the above carbon number can enable the prepared fluorinated cage-type polysilsesquioxane to contain more fluorine atoms, which can effectively reduce the surface energy of the coating.

[0013] Preferably, the silica nanoparticles are modified with alkyltriethoxysilane. This modification changes the hydrophilic surface of the silica nanoparticles, which is rich in hydroxyl groups, to a hydrophobic surface containing organic functional groups. This not only improves the hydrophobicity of the coating, thereby enhancing the antifouling properties of the coating, but also facilitates the uniform dispersion of the silica nanoparticles in the organic coating system, fully leveraging the synergistic effect of the silica nanoparticles with other substances.

[0014] Preferably, the alkyltriethoxysilane is n-octyltriethoxysilane.

[0015] Preferably, the particle size of the silicon dioxide nanoparticles is 100 to 200 nm.

[0016] Preferably, the specific operation of modifying the silica nanoparticles with alkyltriethoxysilane is as follows: mixing alkyltriethoxysilane with ethanol to obtain a first mixed solution; diluting ammonia water by 5 times, adding the silica nanoparticles thereto and mixing to obtain a dispersion; mixing the first mixed solution with the dispersion, reacting at 35-45° C. for 10-14 hours, washing, and drying to obtain the product.

[0017] Preferably, the preparation of the above-mentioned silicone-modified polyurethane prepolymer includes the following steps: S1. mixing aminopolydimethylsiloxane with the first part of the third solvent, and the epoxy compound with the second part of the third solvent to obtain an aminopolydimethylsiloxane solution and an epoxy compound solution; adding the aminopolydimethylsiloxane solution to the epoxy compound solution, reacting at 50-60°C for 8-10 hours to obtain a polyol; S2. mixing diisocyanate and the third part of the third solvent, adding the polyol thereto, and reacting at 70-90°C for 4-6 hours to obtain a silicone-modified polyurethane prepolymer.

[0018] The above preparation method can obtain a silicone-modified polyurethane prepolymer with a suitable molecular weight, which can remain in the solvent for a long time without settling, and can form a good mixed system with silica nanoparticles and fluorinated cage-type polysilsesquioxane, which is conducive to forming a uniform and compact coating, exerting excellent anti-fouling and mechanical properties, while not affecting other properties of the coating.

[0019] Preferably, the third solvent comprises butyl acetate.

[0020] Preferably, the aminopolysiloxane includes at least one of aminoethylaminopropyl polydimethylsiloxane and α,ω-diaminopropyl-terminated polydimethylsiloxane; the epoxy compound is an alkylene oxide having 4 to 8 carbon atoms; and the diisocyanate includes at least one of toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The choice of materials often influences the properties of the final synthesized product. Using these materials facilitates the synthesis of a stable silicone-modified polyurethane prepolymer with excellent antifouling and mechanical properties.

[0021] Preferably, the mass ratio of aminopolysiloxane, epoxy compound, and diisocyanate is 50:40 to 50:0.5 to 1.5. During the preparation of silicone polyurethane resin, the ratio of ingredients directly affects its performance. Different ratios can lead to variations in many performance indicators of the silicone polyurethane resin, such as surface properties, cure speed, hardness, and tensile strength. Maintaining the ratio of each raw material within the above range facilitates the production of a silicone polyurethane resin that balances both antifouling and mechanical properties without compromising other properties of the silicone polyurethane resin, such as weathering resistance and corrosion resistance.

[0022] Preferably, the curing agent is an amine curing agent, which can promote the curing of the coating at room temperature, improve the convenience of operation, and facilitate practical operation.

[0023] Preferably, the amine curing agent includes at least one of ethylenediamine and xylenediamine.

[0024] Preferably, the above-mentioned low surface energy marine antifouling coating further comprises, calculated by weight, 0.1 to 0.3 parts of a defoaming agent, 0.5 to 2 parts of a leveling agent, 0.03 to 1.5 parts of a dispersant, and 0.5 to 2 parts of an anti-settling agent.

[0025] Preferably, the defoaming agent includes at least one of Efka 2722, Efka 272S, and Digo AIREX 900.

[0026] Preferably, the leveling agent includes at least one of Efka 3236, Efka 3239, and Lenz LC-178.

[0027] Preferably, the dispersant includes at least one of Eukanuba 560S, Eukanuba 765S and Eukanuba 8941, Efka 4061, Efka 4665 and BASF Dispex Ultra FA4425.

[0028] Preferably, the anti-settling agent includes at least one of BYK 410, BYK 411, and Deqian SD-2.

[0029] Preferably, the above-mentioned low surface energy marine antifouling coating is prepared according to the following steps: a silicone-modified polyurethane prepolymer, a fluorinated cage polysilsesquioxane, and a first solvent are mixed evenly, and then a dispersant, an anti-settling agent, silica nanoparticles, and a leveling agent are added in sequence and mixed evenly, and finally a curing agent and a defoaming agent are added and mixed evenly to obtain a low surface energy marine antifouling coating. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0031] Example 1

[0032] (1) Preparation of silicone-modified polyurethane prepolymer

[0033] S1. An aminodimethylsiloxane solution and an epoxy compound solution were mixed with butyl acetate to obtain an aminodimethylsiloxane solution and an epoxy compound solution. The two solutions were then allowed to stand for dehydration at room temperature for 12 h using an appropriate amount of 4A molecular sieves. After dehydration, the aminodimethylsiloxane solution was added to the epoxy compound solution and reacted at 55 ° C for 8 hours to obtain a polyol.

[0034] S2. Diisocyanate and butyl acetate are mixed, and polyol is added thereto, and the mixture is reacted at 80° C. for 5 hours to obtain a silicone-modified polyurethane prepolymer.

[0035] In the above reaction, the mass ratio of aminopolysiloxane, epoxy compound and diisocyanate is 50:45:1, the aminopolysiloxane is aminoethylaminopropyl polydimethylsiloxane, and the epoxy compound is 1,2-epoxycyclopentane.

[0036] (2) Preparation of fluorinated cage-type polysilsesquioxane

[0037] Perfluorooctyltriethoxysilane and tetrahydrofuran were mixed, and the pH of the obtained mixed system was adjusted to 12 with a sodium hydroxide solution. The mixture was refluxed at 100° C. for 1 hour to obtain a fluorinated cage-type polysilsesquioxane.

[0038] (3) Modification of silica nanoparticles

[0039] n-Octyltriethoxysilane was mixed with ethanol to obtain a first mixed solution; ammonia water was diluted 5 times, silica nanoparticles (particle size of 150 nm) were added thereto and mixed, and ultrasonicated for 10 minutes to obtain a dispersion; the first mixed solution was mixed with the dispersion, reacted at 40°C for 12 hours, centrifuged, washed, dried, and ground to obtain n-Octyltriethoxysilane-modified silica nanoparticles.

[0040] During the above reaction process, the mass ratio of n-octyltriethoxysilane to silica nanoparticles is 0.55:3.

[0041] (4) Preparation of coating

[0042] 70 parts of the above-mentioned silicone-modified polyurethane prepolymer, 10 parts of fluorinated cage-type polysilsesquioxane, 5 parts of acetone, and 5 parts of n-butyl acetate solution were mixed evenly, and then 0.8 parts of dispersant (BASF Dispex Ultra FA4425), 0.8 parts of anti-settling agent (Bick 411), 12 parts of silica nanoparticles (modified with n-octyltriethoxysilane), and 1.2 parts of leveling agent (EFKA 3239) were added in sequence and continued to mix evenly. Finally, 3 parts of curing agent (phenylenediamine) and 0.2 parts of defoaming agent (EFKA 2722) were added and continued to mix evenly to obtain a low surface energy marine antifouling coating.

[0043] During the actual application of the coating, the curing agent can be added in the final use stage according to the actual situation to avoid adding the curing agent too early, which may cause the resin in the coating to cure prematurely and become ineffective.

[0044] Example 2

[0045] The difference between this embodiment and embodiment 1 is that in (2) the preparation of fluorinated cage-type polysilsesquioxane, the perfluorooctyltriethoxysilane used is perfluorobutyltriethoxysilane; the rest is the same as embodiment 1.

[0046] Example 3

[0047] The difference between this embodiment and embodiment 1 is that in (2) the preparation of fluorinated cage-type polysilsesquioxane, the perfluorooctyltriethoxysilane used is perfluorooctyltrimethoxysilane; the rest is the same as embodiment 1.

[0048] Example 4

[0049] The difference between this embodiment and embodiment 1 is that in (3) modification of silica nanoparticles, n-octyltriethoxysilane is replaced with n-pentyltriethoxysilane; the rest is consistent with embodiment 1.

[0050] Example 5

[0051] The difference between this embodiment and embodiment 1 is that in (3) modification of silica nanoparticles, n-octyltriethoxysilane is replaced with n-decyltriethoxysilane; the rest is consistent with embodiment 1.

[0052] Example 6

[0053] The difference between this embodiment and embodiment 1 is that in (1) the organosilicon-modified polyurethane prepolymer, the feed ratio of aminopolysiloxane, epoxy compound, and diisocyanate is 50:35:1; the rest is the same as embodiment 1.

[0054] Example 7

[0055] The difference between this embodiment and embodiment 1 is that in (1) the organosilicon-modified polyurethane prepolymer, the feed ratio of aminopolysiloxane, epoxy compound, and diisocyanate is 50:55:1; the rest is the same as embodiment 1.

[0056] Example 8

[0057] The difference between this embodiment and embodiment 1 is that the silica nanoparticles are not modified, that is, the silica does not undergo the process of "(3) modification of silica nanoparticles"; the rest is consistent with embodiment 1.

[0058] Comparative Example 1

[0059] This comparative example differs from Example 1 in that the organosilicon-modified polyurethane prepolymer is replaced with an organosilicon resin (commercially available); the rest is the same as Example 1.

[0060] Comparative Example 2

[0061] This comparative example differs from Example 1 in that the fluorinated cage-type polysilsesquioxane is replaced with cage-type polysilsesquioxane (commercially available); the rest is the same as Example 1.

[0062] Comparative Example 3

[0063] This comparative example differs from Example 1 in that no fluorinated cage-type polysilsesquioxane is added; the rest is the same as Example 1.

[0064] Comparative Example 4

[0065] This comparative example differs from Example 1 in that silicon dioxide nanoparticles are not added; the rest is the same as Example 1.

[0066] Test Case

[0067] 1. Experimental Construction Method

[0068] The coatings obtained in the above examples and comparative examples were poured into molds respectively and cured at room temperature for 12 hours to obtain coatings. The coatings were tested for water contact angle, impact resistance, tensile strength, elongation at break, and acid and alkali resistance. The specific test methods are as follows:

[0069] (1) Water contact angle test

[0070] An optical contact angle meter was used to quantitatively test the hydrophobicity of the coating. The contact angle (CA) was measured using 5 μL of test liquid. At least three different locations of the same sample were tested, and the corresponding average value was taken.

[0071] (2) Impact resistance test

[0072] The test was carried out in accordance with the standard GB / T 1732-93.

[0073] (3) Tensile strength and elongation at break test

[0074] Tested in accordance with JGT 172-2005.

[0075] (4) Acid and alkali resistance test

[0076] The test was carried out in accordance with GB / T 9274-1988.

[0077] 2. Experimental Results

[0078] The relevant performance test results of the coatings formed by the coatings obtained in the above examples and comparative examples are shown in Table 1.

[0079] Table 1 Test results of relevant properties of the coatings formed by the coatings obtained in the examples and comparative examples

[0080]

[0081]

[0082] As can be seen from Table 1, the combination of silicone polyurethane prepolymer, silica nanoparticles, and fluorinated polysilsesquioxane can achieve both antifouling and mechanical properties. For reference, the performance data in Examples 1-8 can be used. Specifically, the coatings in Examples 1-7 achieved water contact angles exceeding 110°, impact strength exceeding 50 kg / cm, tensile strength exceeding 6.0 MPa, and elongation at break exceeding 580%, demonstrating low surface energy and excellent mechanical properties. Furthermore, the coatings in Examples 1-7 exhibited good acid and alkali resistance, with the paint films exhibiting no flaking or blistering, or only slight blistering, after 960 hours.

[0083] And the matrix resin adopted in comparative example 1 is only organosilicon resin, organosilicon resin can reduce the surface energy of coating to a certain extent, but the mechanical property of organosilicon resin is poor, causes the impact resistance, tensile strength and elongation at break of coating to be significantly reduced compared with embodiment 1.In comparative example 2, fluorinated cage type polysilsesquioxane is replaced with cage type polysilsesquioxane, causes the water contact angle of coating to be less, and antifouling property is poor, and this is because the fluorine atom in fluorinated cage type polysilsesquioxane can effectively reduce the surface energy of coating, improves the antifouling property of coating.In like manner, fluorinated cage type polysilsesquioxane is not added in comparative example 3, also causes the water contact angle of coating to be less, and antifouling property is poor.Meanwhile, the acid and alkali resistance of the coating in comparative examples 2, 3 also declines, and this is because the acid and alkali resistance of fluorine atom is better, if cage type polysilsesquioxane is not fluorinated or does not add fluorinated cage type polysilsesquioxane, all can cause the decline of coating acid and alkali resistance. In Comparative Example 4, no silica nanoparticles were added, resulting in a decrease in the contact angle of the coating, as well as a decrease in the mechanical properties and acid and alkali resistance. This is because silica nanoparticles have good structural strength, a large specific surface area, and a relatively rough surface, and can therefore enhance the anti-fouling properties, mechanical properties, and acid and alkali resistance of the coating.

[0084] Further, comparing Examples 1 and 2, the fluorinated octyloxysilane used in Example 2 is perfluorobutyltriethoxysilane, which has 10 carbon atoms, less than 12, and a low fluorine atom content. Therefore, it cannot effectively reduce the surface performance of the coating, and the anti-fouling performance improvement effect is not obvious.

[0085] Comparing Examples 1, 4, and 5, in Examples 4 and 5, the silane coupling agents used in the modification of silica nanoparticles are n-pentyltriethoxysilane and n-decyltriethoxysilane, respectively. Different silane coupling agents have inconsistent surface modification effects on silica nanoparticles, resulting in inconsistent surface properties of the modified silica nanoparticles, which ultimately affects the surface energy of the coating.

[0086] Comparing Examples 1, 6, and 7, the mass ratio of the aminopolysiloxane, epoxy compound, and diisocyanate in Examples 6 and 7 is not within the range of 50:40 to 50:0.5 to 1.5, resulting in differences in the properties of the ultimately formed silicone polyurethane. This also affects the properties of the final coating, specifically, the contact angle, impact strength, tensile strength, and elongation at break are all lower than those in Example 1.

[0087] Comparing Examples 1 and 8, the silica nanoparticles used in Example 7 were not modified with a silane coupling agent, which reduced the surface roughness of the silica nanoparticles. As a result, the water contact angle of the coating was also reduced, and the antifouling performance was slightly worse.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents, but these modifications or replacements are all within the scope of protection of the present invention.

Claims

1. A low surface energy marine antifouling coating, characterized in that: Calculated by weight, it includes the following components: 50-80 parts of organosilicon-modified polyurethane prepolymer, 5-15 parts of silicon dioxide nanoparticles, 5-15 parts of fluorinated cage-type polysilsesquioxane, 1-5 parts of curing agent, and 5-25 parts of first solvent; The preparation of the organosilicon-modified polyurethane prepolymer comprises the following steps: S1. The amino dimethylsiloxane and the first part of the third solvent, the epoxy compound and the second part of the third solvent are mixed to obtain an amino dimethylsiloxane solution and an epoxy compound solution; the amino dimethylsiloxane solution is added to the epoxy compound solution, and the reaction is carried out at 50 to 60 ° C for 8 to 10 hours to obtain a polyol; S2. mixing the diisocyanate and the third part of the third solvent, and adding the polyol thereto, reacting at 70 to 90 ° C for 4 to 6 hours to obtain the silicone-modified polyurethane prepolymer; The preparation of the fluorinated cage-type polysilsesquioxane comprises the following steps: The perfluoroalkyloxysilane is mixed with a second solvent, and the pH of the obtained mixed system is adjusted to 11-12, and the mixture is refluxed at 95-105° C. for 1-1.5 hours to obtain the fluorinated cage-type polysilsesquioxane; the perfluoroalkyloxysilane includes at least one of perfluoroalkyltrimethoxysilane and perfluoroalkyltriethoxysilane.

2. The low surface energy marine antifouling coating according to claim 1, characterized in that: The perfluoroalkyloxysilane is perfluoroalkyltriethoxysilane; The perfluoroalkyltriethoxysilane has no less than 12 carbon atoms.

3. The low surface energy marine antifouling coating according to claim 1, wherein: The silica nanoparticles are modified with alkyltriethoxysilane.

4. The low surface energy marine antifouling coating according to claim 3, characterized in that: The alkyltriethoxysilane is n-octyltriethoxysilane.

5. The low surface energy marine antifouling paint according to claim 3, characterized in that: The specific operation of modifying the silica nanoparticles with the alkyltriethoxysilane is as follows: The alkyltriethoxysilane is mixed with ethanol to obtain a first mixed solution; ammonia water is diluted 5 times, and silicon dioxide nanoparticles are added thereto and mixed to obtain a dispersion; the first mixed solution is mixed with the dispersion, reacted at 35-45° C. for 10-14 hours, washed, and dried to obtain the product.

6. The low surface energy marine antifouling coating according to claim 1, characterized in that: The aminopolysiloxane includes at least one of aminoethylaminopropyl polydimethylsiloxane and α, ω-diaminopropyl terminated polydimethylsiloxane; The epoxy compound is an alkylene oxide, and the number of carbon atoms of the alkylene oxide is 4 to 8; The diisocyanate includes at least one of toluene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate.

7. The low surface energy marine antifouling coating according to claim 1, characterized in that: The mass ratio of the aminopolysiloxane, the epoxy compound and the diisocyanate is 50:40 to 50:0.5 to 1.

5.

8. The low surface energy marine antifouling coating according to claim 1, characterized in that: The curing agent is an amine curing agent.

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