A mucus secreting polysiloxane marine antifouling coating

Abstract

The application discloses a mucus secretion type polysiloxane marine antifouling paint, by introducing thiocyanate groups and mercapto groups in the paint curing agent, using the hydrophobic hydrogen bond network effect generated by the thiocyanate groups to give the curing agent good adhesion, using the folding physical crosslinking effect generated by the mercapto groups to give the curing agent suitable cohesion, so that the adhesion and cohesion of the curing agent are consistent, and the curing agent has excellent bonding effect. In the final cured coating, the bonding effect of the curing agent realizes firm bonding of the coating and the substrate, meanwhile, the free nonpolar mucus in the three-dimensional network molecular structure of the coating migrates to the surface of the coating under the influence of the polar curing agent chain segment and is released, realizing the mucus secretion effect, so that the coating has good antifouling performance. The paint can be applied to the field of marine facility antifouling, and is especially suitable for various marine facilities immersed in seawater environment for a long time.

Description

Technical Field

[0001] This invention belongs to the fields of marine antifouling coating technology and underwater coating protection technology, and specifically relates to a functionalized modified fouling-releasing marine antifouling coating. Background Technology

[0002] Marine biofouling refers to the process by which marine fouling organisms non-selectively adhere to and grow on the surface of objects submerged in seawater. It is a major challenge facing countries around the world in developing their marine and maritime industries, and applying marine antifouling coatings is the most convenient and effective way to solve this problem.

[0003] Traditional marine antifouling coatings, while preventing marine fouling, also cause significant pollution and harm, and are gradually being banned by countries worldwide. New types of marine antifouling coatings, based on environmentally friendly requirements, prevent marine fouling without threatening the marine environment, and are now a focus of development for countries around the world.

[0004] Organosilicon marine antifouling coatings belong to the field of environmentally friendly fouling release antifouling coatings. Based on low surface free energy and low elastic modulus, they utilize the relative motion between the ship and the seawater to achieve the prevention and removal of fouling organisms and the removal of loosely adhered fouling organisms, showing great application potential.

[0005] However, current silicone-based marine antifouling coatings suffer from poor adhesion to substrates and are ineffective in still water environments, requiring significant improvement. Biomimetic research on large marine organisms such as fish and whales has shown that these organisms continuously secrete mucus from the inside out to moisten their skin surface, using this mucus to encapsulate and remove adhering fouling organisms. Biomimetic mucus-secreting marine antifouling coatings developed based on this biomimetic antifouling mechanism have made some progress. However, these mucus-secreting marine antifouling coatings generally suffer from disordered migration and release of the biomimetic mucus, leading to decreased adhesion between the coating and the substrate. Currently, the promotion and use of these coatings are greatly limited. Summary of the Invention

[0006] To address the shortcomings of low surface energy silicone marine antifouling coatings, such as poor adhesion to substrates and the need for seawater rinsing to achieve good antifouling performance, this invention provides a mucus-secreting polysiloxane marine antifouling coating. A modified curing agent is synthesized via Michael addition reaction, introducing thiourea and mercapto groups into the curing agent's molecular structure. The hydrophobic hydrogen bond network generated by the thiourea groups imparts good adhesion to the curing agent, while the folded physical crosslinking effect generated by the mercapto groups provides suitable cohesive strength. This ensures a harmonious balance between adhesion and cohesive strength, guaranteeing excellent adhesion. In the final cured coating, the adhesive effect of the curing agent achieves a strong bond between the coating and the substrate. Simultaneously, the free non-polar mucus within the three-dimensional network molecular structure of the coating migrates and releases to the coating surface under the influence of polar curing agent segments, achieving a mucus-secreting effect and ensuring good antifouling performance.

[0007] This invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a mucus-secreting type polysiloxane marine antifouling coating, comprising, by weight parts: (1) 80-100 parts of component A; (2) 8-20 parts of component B; and (3) 5-10 parts of component C.

[0009] in,

[0010] Component A comprises, by weight, the following:

[0011]

[0012] Component B, by weight, comprises:

[0013] 10-30 parts of modified curing agent

[0014] Solvent B: 20-40 parts;

[0015] Component C, by weight, includes:

[0016] 1-4 parts of catalyst

[0017] Solvent C: 5-20 parts;

[0018] The modified curing agent is prepared through the following steps:

[0019] (1) In a reaction apparatus protected by nitrogen and equipped with a stirring and reflux device, a thiourea compound with unsaturated groups, a mercapto ester monomer, a curing agent, an amine catalyst, and dichloromethane are added in sequence, and then the reaction is stirred at 50-100 rpm for 6-14 h at 20-35 °C.

[0020] (2) The product after reaction is filtered and precipitated, and washed with dichloromethane at least 3 times. The precipitated product is then obtained by filtration and dried in a vacuum device for 24 hours to finally obtain the modified curing agent.

[0021] Preferably, the weight ratio of the thiourea compound with unsaturated groups, the mercapto ester monomer, the curing agent, the amine catalyst, and the dichloromethane is (1-5):(5-12):(10-20):(1-3):(50-100).

[0022] Preferably, the thiourea compound with unsaturated groups is selected from N-allylthiourea, N-propenylN'-2-hydroxyethylthiourea, 4-(3-allylthiourea)benzoic acid, 4-propenylthioaminourea, and 1-allyl-3-(pyridin-2-yl)thiourea.

[0023] Preferably, the mercapto ester monomer is selected from one of 3-mercaptopropionate, trimethylolpropane tris(3-mercaptopropionic acid) ester, 2-ethylhexyl 3-mercaptopropionate, and isooctyl 3-mercaptopropionate.

[0024] Preferably, the curing agent is selected from one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-(isobutenyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane.

[0025] Preferably, the amine catalyst is selected from N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, and N,N,N',N'-tetramethylalkylene diamine.

[0026] Preferably, the nonpolar viscous liquid is selected from non-reactive inert silicone oil.

[0027] Specifically, the non-reactive inert silicone oil is selected from one of the following: methyl silicone oil with a kinematic viscosity of 10-50 cSt at room temperature, phenylmethyl silicone oil with a kinematic viscosity of 50-200 cSt at room temperature, and alkyl silicone oil with a kinematic viscosity of 70-100 cSt at room temperature.

[0028] Preferably, the hydrophobic organosilicon resin is selected from α,ω-dihydroxypolydimethylsiloxane with a viscosity of 2800-10000 mPa·s at 25°C.

[0029] Preferably, the additive is selected from at least one of wetting and dispersing agents, defoamers, and leveling agents.

[0030] Specifically, the wetting and dispersing agent is selected from BYK116 and BYK169 from BYK Corporation, and 901 and 903 from Deqian Company.

[0031] Specifically, the defoamer is selected from BYK065 and BYK066N from BYK Corporation, and EFKA2020 from Efka, Netherlands.

[0032] Specifically, the leveling agent is selected from one of BYK308, BYK310, and BYK373 from Germany.

[0033] Preferably, the pigments and fillers are common in this field and have no special requirements. As a preferred option, they are selected from, but not limited to, calcium carbonate, ferric oxide, titanium dioxide, barium sulfate, kaolin, and zinc oxide.

[0034] Preferably, solvent A is selected from methanol, xylene, and acetone.

[0035] Preferably, solvent B is selected from acetone, butanone, and acetylacetone.

[0036] Preferably, the catalyst is selected from one of dibutyltin disilicate, stannous octoate, and organobismuth.

[0037] Preferably, the solvent C is selected from acetylacetone, cyclohexanone, and toluene.

[0038] Secondly, the present invention also provides a method for preparing the coating described in the first aspect, which involves preparing component A, component B, and component C separately according to conventional preparation methods and storing them in a sealed container, specifically including the following steps:

[0039] (1) Add hydrophobic organosilicon resin, additives and non-polar viscous liquid sequentially to a dispersion and stirring device, and then disperse at 100 rpm for 20 min. Then add pigments, fillers and solvent A to the dispersion and stirring device, and continue to disperse at the same speed for 20 min to prepare component A. Then seal and store.

[0040] (2) Use a dispersion and stirring device to disperse the modified curing agent and solvent B at 50 rpm for 10 min to prepare component B, and then seal and store it.

[0041] (3) Use a dispersion and stirring device to disperse the catalyst and solvent C at 50 rpm for 10 min to prepare component C, and then seal and store it.

[0042] Thirdly, the present invention also provides an antifouling coating prepared by the coating described in the first aspect, wherein components A, B, and C are mixed evenly using conventional dispersion processes and equipment, and applied by spraying, rolling, brushing, or other methods, and cured for at least 48 hours to prepare a coating with a film thickness of 150 to 250 μm.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. A modified curing agent is synthesized through Michael addition reaction, incorporating thiourea and mercapto groups into the molecular structure of the curing agent. The hydrophobic hydrogen bond network generated by the thiourea groups imparts good adhesion to the curing agent, while the folding physical crosslinking effect generated by the mercapto groups imparts suitable cohesive force. This ensures that the adhesion and cohesive force of the curing agent are coordinated and consistent, guaranteeing that the curing agent has excellent bonding performance.

[0045] 2. In the final cured coating, the uniformly distributed curing agent structure imparts a beneficial adhesion effect to the cured coating, which can firmly bond to the substrate and intermediate paint surface. At the same time, as the curing agent molecular structure, it will not affect the main film-forming polysiloxane molecular structure of the coating, ensuring that the cured coating still has excellent flexibility and low surface energy characteristics.

[0046] 3. By utilizing the polar groups (mainly thiol groups) brought by the modified curing agent, the non-polar mucus existing in the free state in the cured coating can be driven to migrate and release to the coating surface, thereby simulating the antifouling properties of mucus secretion. This ensures that the coating still has active physical antifouling properties even without high-speed seawater scouring, thus ensuring the coating's beneficial antifouling performance.

[0047] 4. The cured coating and the substrate or intermediate paint achieve a strong adhesion through hydrogen bonding network, while simultaneously inhibiting the migration of non-polar adhesives to the coating-substrate region, thus ensuring that non-polar adhesives can only migrate and be released to the coating surface. Detailed Implementation

[0048] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0049] The coating of the present invention, on the one hand, utilizes the modified curing with thiourea groups and mercapto groups to ensure that the cured coating can firmly adhere to liquids, and on the other hand, non-polar liquids cannot be stably stored inside the coating and migrate to the coating surface under the drive of the polar curing agent molecular structure, thereby achieving good physical antifouling properties even in the absence of high-speed seawater scouring.

[0050] The raw materials used in the examples are shown in Table 1. In actual implementation, the raw materials are not limited to those listed in Table 1; appropriate products can be selected based on the foregoing. Other raw materials used in the examples are commercially available chemical reagents.

[0051] Table 1

[0052]

[0053] Modified curing agent 1

[0054] The weight ratio of the thiourea compound with unsaturated groups, mercapto ester monomers, curing agent, amine catalyst, and dichloromethane is 5:10:20:2:60. The specific preparation steps are as follows:

[0055] (1) In a reaction apparatus protected by nitrogen and equipped with a stirring and reflux device, thiourea compound 6-1 with unsaturated groups, mercapto ester monomer 7-1, curing agent 8-2, amine catalyst 9-1 and dichloromethane were added in sequence, and then stirred at 80 rpm for 10 h at 25 °C.

[0056] (2) The product after the reaction was filtered and precipitated, and washed with dichloromethane at least 3 times. The precipitated product was then obtained by filtration and dried in a vacuum device for 24 hours to finally obtain modified curing agent 1.

[0057] Modified curing agent 2

[0058] The weight ratio of the thiourea compound with unsaturated groups, mercapto ester monomers, curing agent, amine catalyst, and dichloromethane is 1:5:15:1:50. The specific preparation steps are as follows:

[0059] (1) In a reaction apparatus protected by nitrogen and equipped with a stirring and reflux device, thiourea compound 6-2 with unsaturated groups, mercapto ester monomer 7-2, curing agent 8-1, amine catalyst 9-2 and dichloromethane were added in sequence, and then stirred at 100 rpm for 6 h at 20 °C.

[0060] (2) The product after reaction was filtered and precipitated, and washed with dichloromethane at least 3 times. The precipitated product was then obtained by filtration and dried in a vacuum device for 24 hours to finally obtain modified curing agent 2.

[0061] Modified curing agent 3

[0062] The weight ratio of the thiourea compound with unsaturated groups, mercapto ester monomers, curing agent, amine catalyst, and dichloromethane is 3:12:10:3:100. The specific preparation steps are as follows:

[0063] (1) In a reaction apparatus protected by nitrogen and equipped with a stirring and reflux device, thiourea compound 6-3 with unsaturated groups, mercapto ester monomer 7-2, curing agent 8-3, amine catalyst 9-2, and dichloromethane were added in sequence, and then stirred at 50 rpm for 14 h at 35 °C.

[0064] (2) The product after reaction was filtered and precipitated, and washed with dichloromethane at least 3 times. The precipitated product was then obtained by filtration and dried in a vacuum device for 24 hours to finally obtain modified curing agent 3.

[0065] Examples 1-5

[0066] The proportions of components A, B, and C in Examples 1-5 are shown in Table 2, and the specific proportions of each component in Examples 1-5 are shown in Table 3.

[0067] Table 2

[0068] A 70 100 80 70 90 B 10 15 20 15 12 C 5 8 10 10 8

[0069] Table 3

[0070]

[0071] According to Tables 2 and 3, the preparation method of the mucus-secreting polysiloxane marine antifouling coatings of Examples 1-5 is as follows:

[0072] (1) Add hydrophobic organosilicon resin, additives and non-polar viscous liquid sequentially to a dispersion and stirring device, and then disperse at 100 rpm for 20 min. Then add pigments, fillers and solvent A to the dispersion and stirring device, and continue to disperse at the same speed for 20 min to prepare component A. Then seal and store.

[0073] (2) Use a dispersion and stirring device to disperse the modified curing agent and solvent B at 50 rpm for 10 min to prepare component B, and then seal and store it.

[0074] (3) Use a dispersion and stirring device to disperse the catalyst and solvent C at 50 rpm for 10 min to prepare component C, and then seal and store it.

[0075] (4) Mix components A, B and C evenly using conventional dispersion processes and equipment, apply the coating by spraying, rolling, brushing or other methods, and cure for at least 48 hours to prepare a coating with a thickness of 150 to 250 μm.

[0076] In practical applications, it can be prepared by following the conventional methods for marine antifouling coatings, and is not limited to the preparation methods mentioned above.

[0077] Comparative Example 1 (Ordinary silicone low surface energy marine antifouling coating)

[0078] Ordinary organosilicon low surface energy marine antifouling coating comprises the following raw materials in parts by weight: 90.0 parts polysiloxane resin, 30.0 parts pigments and fillers, 4.0 parts crosslinking curing agent, 1.5 parts catalyst, 0.5 parts additives, and 10.0 parts third solvent.

[0079] The polysiloxane resin selected was α,ω-dihydroxypolydimethylsiloxane with a viscosity of 10000 mPa·s; the pigment selected was zinc oxide; the crosslinking curing agent selected was tetraethyl orthosilicate; the catalyst selected was dibutyltin disilicate; the additive selected was 0.5 parts of BYK161 dispersant from BYK Corporation; and the third solvent selected was xylene.

[0080] (1) Add 90.0 parts of α,ω-dihydroxypolydimethylsiloxane with a viscosity of 10000 mPa·s and 30.0 parts of micron-sized zinc oxide to a disperser and disperse at high speed at 300 rpm for 30 min. Then, add 0.5 parts of BYK161 dispersant from BYK Corporation to the disperser at 200 rpm and disperse for 30 min. Then grind the mixture in a sand mill until the fineness is less than 40 μm to make a pre-dispersed slurry, which is then bottled for later use.

[0081] (2) Mix 4.0 parts of tetraethyl orthosilicate and 10.0 parts of xylene evenly to prepare a crosslinking curing agent component and then bottle it for later use; mix 1.5 parts of dibutyltin disilicate and 20.0 parts of xylene evenly to prepare a catalyst component and then bottle it for later use;

[0082] (3) Before use, mix the pre-dispersed slurry, crosslinking curing agent and catalyst components evenly according to the ratio. After coating and curing, the resulting coating is a common organosilicon low surface energy marine antifouling coating with a thickness of 150-250μm.

[0083] Comparative Example 2

[0084] Compared with Example 1, the modified curing agent prepared did not introduce mercapto ester monomers, and the remaining components and their weight parts were the same, and its preparation process was also the same as that of Example 1.

[0085] <Specific Test Experiments and Conditions>

[0086] Test 1: Adhesion test of steel plate after 100 days of seawater immersion (with epoxy intermediate paint) using the pull-out method.

[0087] The adhesion of coatings applied to corresponding substrates or epoxy intermediate paints was measured using a BGD500 digital display semi-automatic adhesion tester manufactured by Guangzhou Biaogeda Precision Instruments Co., Ltd. The steel plate needed to be sanded with 800-grit sandpaper before use. The epoxy intermediate paint used was epoxy micaceous iron oxide intermediate paint manufactured by Shanghai Jinshidi. Before testing, the coating was immersed in sterilized seawater for 100 days, then removed, dried, and tested.

[0088] Test 2: Stain Resistance

[0089] A strain containing at least 10⁸ units of *Streptococcus salivarius* was dispersed in 20 mL of trypsin-soy broth and incubated at 38 °C with 5% CO₂ for 2 hours. The suspension was then further diluted and inoculated onto agar supplemented with 5% sheep blood, and incubated at 38 °C with 5% CO₂ for 48 hours. Units containing six colonies were then dispersed in 10 mL of trypsin-soy broth. A 20 mL layer of the above bacterial suspension was then applied to a 10 × 5 cm area and incubated at 38 °C with 5% CO₂ for 24 hours. After incubation, each sample was swirled in 45 mL of distilled water for 30 seconds, followed by rinsing with 50 mL of distilled water to remove non-adhesive material. The bacteria adhering to the surface were observed using a Carl Zeiss Simga 300 scanning electron microscope.

[0090] The specific test results of Examples 1-5 and Comparative Examples 1-2 are shown in Table 4.

[0091] Table 4

[0092]

[0093] The above tests confirm that both the example and comparative coatings exhibit low surface free energy, thus demonstrating excellent antifouling performance. The advantage of this invention lies in the fact that the examples show superior adhesion to various polar substrates, far exceeding that of the comparative examples, exhibiting excellent bonding effects.

[0094] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A mucus-secreting type polysiloxane marine antifouling coating, characterized in that, The product comprises, by weight, 80-100 parts of component A; 8-20 parts of component B; and 5-10 parts of component C. in, Component A comprises, by weight, the following: 60-100 parts of hydrophobic silicone resin 1-3 parts of auxiliary agent 10-30 parts of non-polar mucus 50-80 parts of pigments and fillers Solvent A: 50-100 parts; Component B, by weight, comprises: 10-30 parts of modified curing agent Solvent B: 20-40 parts; Component C, by weight, includes: 1-4 parts of catalyst Solvent C: 5-20 parts; The modified curing agent is prepared through the following steps: (1) In a reaction apparatus protected by nitrogen and equipped with a stirring and reflux device, thiourea compound with unsaturated groups, mercaptoester monomer, curing agent, amine catalyst and dichloromethane are added in sequence, and then the reaction is stirred at 50-100 rpm for 6-14 h at 20-35℃. (2) The product after the reaction is filtered to precipitate and washed with dichloromethane at least 3 times. The precipitate is then obtained by filtration and dried in a vacuum device for 24 hours to obtain the modified curing agent.

2. The antifouling coating as described in claim 1, characterized in that, The weight ratio of thiourea compound with unsaturated groups, mercapto ester monomer, curing agent, amine catalyst, and dichloromethane is (1~5):(5~12):(10~20):(1~3):(50~100).

3. The antifouling coating as described in claim 1, characterized in that, The thiourea compound with an unsaturated group is selected from one of N-allylthiourea, N-propenylN'-2-hydroxyethylthiourea, 4-(3-allylthiourea)benzoic acid, 4-propenylthioaminourea, and 1-allyl-3-(pyridin-2-yl)thiourea.

4. The antifouling coating as described in claim 1, characterized in that, The mercaptoester monomers are selected from one of 3-mercaptopropionate, trimethylolpropane tris(3-mercaptopropionic acid) ester, 2-ethylhexyl 3-mercaptopropionate, and isooctyl 3-mercaptopropionate.

5. The antifouling coating as described in claim 1, characterized in that, The curing agent is selected from one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-(isobutenyloxy)propyltrimethoxysilane, γ-methacryloyloxypropyltriisopropoxysilane, and γ-methacryloyloxypropylmethyldimethoxysilane.

6. The antifouling coating as described in claim 1, characterized in that, The amine catalyst is selected from one of N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, and N,N,N',N'-tetramethylalkylene diamine.

7. The antifouling coating as described in claim 1, characterized in that, The nonpolar viscous liquid is selected from non-reactive inert silicone oil.

8. The antifouling coating as described in claim 7, characterized in that, The non-reactive inert silicone oil is selected from one of the following: methyl silicone oil with a kinematic viscosity of 10-50 cSt at room temperature, phenylmethyl silicone oil with a kinematic viscosity of 50-200 cSt at room temperature, and alkyl silicone oil with a kinematic viscosity of 70-100 cSt at room temperature.

9. The method for preparing the antifouling coating as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Add hydrophobic silicone resin, additives and non-polar viscous liquid to the dispersion and stirring equipment in sequence, and then disperse at 100 rpm for 20 min. Then add pigments, fillers and solvent A to the dispersion and stirring equipment and continue to disperse at the same speed for 20 min to prepare component A. Then seal and store. (2) Use a dispersion and stirring device to disperse the modified curing agent and solvent B at 50 rpm for 10 min to prepare component B, and then seal and store it. (3) Use a dispersion and stirring device to disperse the catalyst and solvent C at 50 rpm for 10 min to prepare component C, and then seal and store it.

10. The antifouling coating prepared by the antifouling coating according to any one of claims 1-8, characterized in that, Mix components A, B, and C evenly, apply the mixture to a substrate, and cure for at least 48 hours to prepare a coating with a thickness of 150~250 μm.

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