Marine organism fouling inhibiting antifouling paint

Abstract

We provide a marine organism-fouling-inhibiting and antifouling coating that not only inhibits marine organism fouling but also has recoatability. [Solution] The marine biofouling-inhibiting antifouling coating of the present invention is characterized by comprising a room-temperature curable coating component containing a linear organopolysilosan having a viscosity of 0.1 to 50 Pa·s at 23°C and silanol groups at both ends of the molecular chain, a reaction product of a bis(trialkoxysilylalkyl)amine compound and at least one titanium alkoxide compound selected from tetran-butyl titanate, butyl titanate dimer, and tetraoctyl titanate, and a superparamagnetic fluid. The superparamagnetic fluid contains iron(III) oxide (Fe3O4) nanoparticles with a particle size of 5 to 20 nm, and it is preferable that the content ratio is 5 to 30 parts by mass per 110 parts by mass of the room-temperature curable coating component.

Description

Technical Field

[0001] The present invention relates to a marine organism adhesion-inhibiting antifouling paint that requires no external power source, causes no elution of harmful components, can achieve predetermined functions and effects simply by application and drying, and further possesses recoatability.

Background Art

[0002] In marine structures, ships, coastal infrastructure, industrial plants that use seawater, and the like, suppressing the adhesion of marine organisms (biofouling) has become an important issue. For example, groups of organisms such as barnacles and seaweed attached to the hull of a ship significantly increase hydrodynamic frictional resistance, resulting in an increase in fuel consumption and a concomitant sharp rise in greenhouse gas emissions. Historically, as the most effective solution to this issue, self-polishing antifouling paints (SPC: Self-Polishing Copolymer) that gradually elute tributyltin (TBT), cuprous oxide (Cu₂O), or various organic antifouling agents from the coating film into seawater have been adopted.

[0003] However, as the lethal effects of these toxic substances on non-target organisms, the accumulation of heavy metals on the seabed, and environmental risks such as endocrine-disrupting effects have become clear, strict international regulations including a total ban on the use of TBT by the International Maritime Organization (IMO) have been implemented. This regulatory background has become a powerful driving force to strongly promote the development of new environmentally harmonious antifouling technologies (Biocide-free coatings) that do not rely on the elution of toxic substances.

[0004] As such a new environmentally harmonious antifouling technology, for example, Patent Document 1 (U.S. Patent No. 7950452) discloses an invention of an antifouling system in which electrodes are provided around a marine drilling structure or the like, and an external power source is used to control the ion concentration in the seawater between the marine drilling structure or the like and the electrodes to fall within a predetermined range, so as to prevent marine organisms from adhering to the surface of the marine drilling structure or the like.

[0005] Furthermore, Patent Document 2 (International Publication No. 2024-224120) discloses an invention of a marine organism-inhibiting antifouling coating that provides high antifouling properties and long-term functionality to a solid surface, by applying an aqueous dispersion containing a conductive and photocatalytically active sheet component (TiO2 / GO sheet) made of graphene oxide (GO) sheets whose surfaces are modified with titanium dioxide (TiO2) nanoparticles, and a magnetic and conductive nanoparticle component (PANI / Fe3O4 nanorod) made of polyaniline nanorods (PANI) externally decorated with magnetite (Fe3O4) nanoparticles, to a solid surface that comes into contact with seawater, and then using an external magnetic field (0.01~0.32mT) to orient the PANI / Fe3O4 nanorods perpendicular to the coating surface (out-of-plane direction), while the TiO2 / GO sheet remains oriented horizontally (in-plane direction).

[0006] Furthermore, Non-Patent Document 1 shows that a coating film formed using a paint in which graphene oxide (GO)-Fe3O4 hybrid nanofiller is dispersed in a polydimethylsiloxane resin has good superhydrophobic and antifouling properties and can be used as an antifouling paint to suppress the adhesion of marine organisms to ships. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] U.S. Patent Publication No. 7950452 [Patent Document 2] International Publication No. 2024-224120 [Patent Document 3] Patent No. 7450866 [Non-patent literature]

[0008] [Non-Patent Document 1] https: / / pubs.acs.org / doi / 10.1021 / acs.langmuir.2c03061 [Non-Patent Document 2] https: / / pmc.ncbi.nlm.nih.gov / articles / PMC2878482 / [Overview of the project] [Problems that the invention aims to solve]

[0009] According to the invention disclosed in Patent Document 1, the ion concentration in the seawater between the offshore drilling structure and the electrode can be maintained at a level where it is difficult for organisms such as barnacles and seaweed to accumulate or grow, using an external power source. This effectively prevents marine organisms from attaching to the surface of the offshore drilling structure. However, since the invention disclosed in Patent Document 1 controls the ion concentration in the seawater between the offshore drilling structure and the electrode using an external power source and the electrode, it can be effective for fixed structures such as offshore structures including offshore drilling structures, coastal infrastructure, and industrial plants that utilize seawater. However, it is difficult to immediately adopt this invention for moving objects such as ships because it is difficult to maintain a constant ion concentration in the seawater around the ship.

[0010] On the other hand, in the invention of the marine organism fouling-inhibiting antifouling coating disclosed in Patent Document 2, the PANI / Fe3O4 nanorods are oriented perpendicular to the coating surface (out-of-plane direction), and the GO / TiO2 sheet is oriented horizontally along the coating surface (in-plane direction). This results in different electrical conductivity (electrical anisotropy) in the in-plane and out-of-plane directions, thereby suppressing the initial adsorption of bacteria and microorganisms and the formation of biofilms. Furthermore, the reactive oxygen species formed by the photocatalytic action of TiO2 decompose organic matter and microorganisms, leading to long-term antifouling. Moreover, as the water-soluble resin gradually dissolves, the internal PANI / Fe3O4 nanorods are newly exposed. Since the PANI / Fe3O4 nanorods are flexible, they have the excellent effect of making it easier for attached algae and shellfish to detach due to minute vibrations caused by waves and currents. Therefore, in the invention of the antifouling coating disclosed in Patent Document 2, electrical anisotropy is formed between the in-plane and out-plane of the coating film without the need for an external power source. Combined with other effects, this results in an antifouling coating that can provide high antifouling properties and long-term functionality to solid surfaces, thereby inhibiting the adhesion of marine organisms.

[0011] However, the antifouling paint invention disclosed in Patent Document 2 produces a predetermined action and effect as the water-soluble resin component gradually dissolves. As a result, the GO / TiO2 sheet and PANI / Fe3O4 nanorods also detach from the surface of the coating over time, thus deviating from the concept of an environmentally friendly antifouling paint that inhibits marine organism adhesion. In addition, the antifouling paint invention disclosed in Patent Document 2 requires the preparation of PANI / Fe3O4 nanorods by reacting Fe3O4 nanoparticles with PANI. Furthermore, in order to orient the PANI / Fe3O4 nanorods perpendicular to the coating surface (out-of-plane direction), it is necessary to orient them in a predetermined direction using an external magnetic field during coating formation. Therefore, simply applying and drying the antifouling paint that inhibits marine organism adhesion disclosed in Patent Document 2 does not allow for the formation of the predetermined coating, and there is also the problem that coating formation is time-consuming.

[0012] Similarly, the coating disclosed in Non-Patent Document 1 also uses graphene oxide (GO)-Fe3O4 hybrid nanofillers, but it does not suggest whether a coating that exhibits the desired effects can be obtained by using a coating in which Fe3O4 nanoparticles are added alone to a polydimethylsiloxane resin without being bonded to a support such as GO.

[0013] On the other hand, silicone resin antifouling paints are widely known as marine organism-fouling-inhibiting antifouling paints that do not require the use of an external power source and do not cause the leaching or detachment of components from the paint film. However, many of these silicone resin antifouling paints have excellent release properties with water-repellent and oil-repellent properties, and when repainting with these paints, it is necessary to remove the already formed paint film, making it difficult to recoat (hereinafter simply referred to as "recoating"), thus severely limiting their applications.

[0014] On the other hand, the inventors have previously filed a patent application for a room-temperature curable transparent rust-preventive coating containing a reaction product of a specific linear organopolysilosan, a specific bis(trialkoxysilylalkyl)amine compound, and a specific titanium alkoxide compound, and have already obtained a patent (see Patent Document 3 above).

[0015] The inventors then considered applying the technical concept of the marine biofouling-inhibiting antifouling paint disclosed in Patent Documents 2 to Non-Patent Document 1 to the transparent rust-preventive paint disclosed in Patent Document 3. However, the coating film formed by the transparent rust-preventive paint disclosed in Patent Document 3 does not contain the "gradually dissolving water-soluble resin component," which is an essential constituent element of the marine biofouling-inhibiting antifouling paint disclosed in Patent Document 2, and therefore cannot be applied as is. In addition, the marine biofouling-inhibiting antifouling paints disclosed in Patent Documents 2 to Non-Patent Document 1 use Fe3O4 bonded with other components, such as PANI / Fe3O4 nanorods (Patent Document 2) or graphene oxide (GO)-Fe3O4 hybrid nanofiller (Non-Patent Document 1), resulting in a complex structure and time-consuming manufacturing.

[0016] Therefore, the inventors have accumulated various knowledge about the physical properties of magnetite (Fe3O4) nanoparticles used in the marine organism fouling-inhibiting antifouling paint disclosed in Patent Document 2. As a result, they found that magnetite exhibits superparamagnetism when its particle size is small, and has been used extensively in medical applications in particular (see Non-Patent Document 2). However, they discovered that a coating film formed using a paint containing superparamagnetic magnetite nanoparticles as they are in a transparent anti-corrosion paint disclosed in Patent Document 3 exhibits excellent marine organism fouling-inhibiting antifouling properties, even without using ferromagnetic / magnetic field generating means such as an external magnet to orient the magnetite nanoparticles in a predetermined direction, and even without bonding the magnetite nanoparticles with other components. This led to the completion of the present invention.

[0017] Superparamagnetism is a phenomenon that appears in nanoparticles of ferromagnetic and ferrimagnetic materials. In ordinary ferromagnetic and ferrimagnetic materials, the direction of magnetization is aligned to maintain the magnetized state, but when these particles reach nanoscale size, the direction of magnetization fluctuates randomly due to heat, resulting in a phenomenon where the macroscopic remanent magnetization becomes zero. Furthermore, because the ratio of surface area to volume is extremely large, superparamagnetic nanoparticles become highly susceptible to the influence of atoms and electrons on their surface, and are particularly sensitive to external magnetic fields, exhibiting high magnetic responsiveness.

[0018] In other words, the present invention aims to provide a marine organism-fouling-inhibiting antifouling paint that does not require an external power source, does not cause elution or detachment of components from the coating film, and can form a coating film that exhibits predetermined marine organism-fouling-inhibiting antifouling properties simply by applying and drying a paint to which the superparamagnetic fluid itself has been added, and furthermore, also possesses recoatability. [Means for solving the problem]

[0019] According to the present invention, a linear organopolysilosan having a viscosity of 0.1 to 50 Pa·s at 23°C and silanol groups at both ends of the molecular chain, A room-temperature curable coating component comprising a reaction product of at least one bis(trialkoxysilylalkyl)amine compound selected from bis[2-(trimethoxysilyl)ethyl]amine, bis[3-(trimethoxysilyl)propyl]amine, bis[4-(trimethoxysilyl)butyl]amine, bis[2-(triethoxysilyl)ethyl]amine, bis[3-(triethoxysilyl)propyl]amine, and bis[4-(triethoxysilyl)butyl]amine, and at least one titanium alkoxide compound selected from tetra-n-butyl titanate, butyl titanate dimer, and tetraoctyl titanate, and A superparamagnetic fluid is further added to the room-temperature curable coating component Including, The superparamagnetic fluid is iron(III) oxide (Fe) with a particle size of 5 nm to 20 nm. 3 O 4 A marine organism-fouling-inhibiting antifouling paint is provided, which contains ) in a proportion of 5 to 30 parts by mass relative to 110 parts by mass of the room-temperature curable paint component. While the particle size of iron(II,III) oxide exhibits good superparamagnetism as it decreases from 20 nm to 20 nm, it is difficult to reduce the particle size to less than 5 nm, so it is preferable to have a particle size of 5 nm to 20 nm. Furthermore, if the content ratio of the superparamagnetic fluid to 110 parts by mass of the room-temperature curable paint component is less than 5 parts by mass, the antifouling properties that inhibit marine organism adhesion will be poor, and if it exceeds 30 parts by mass, the properties exhibited by the room-temperature curable paint component itself will deteriorate, which is undesirable.

[0020] The general formula of the bis(trialkoxysilylalkyl)amine compound is shown below. Provided that, in the following general formula, R represents an alkyl group. JPEG0007936642000002.jpg26136

[0021] The reaction between the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound is presumed to follow the reaction formula shown below, when the general formula of tetra-n-butyl titanate and tetraoctyl titanate is expressed as Ti(OR')₄. Since the butyl titanate dimer is a compound produced by the hydrolysis reaction of tetra-n-butyl titanate, it is presumed that the reaction is substantially the same as in the case of tetra-n-butyl titanate. Provided that, in the following general formula, R represents an alkyl group, and R' represents an n-butyl group or an n-octyl group. JPEG0007936642000003.jpg102136

[0022] While titanium alkoxide compounds themselves are known to react with water to form white titanium oxide, the reaction product of the bis(trialkoxysilylalkyl)amine compound and titanium alkoxide compound used in this invention is substantially transparent, far more stable to water than titanium alkoxide, and, when used in combination with a linear organopolysiloxane having silanol groups at both ends of the molecular chain, a coating film with long-lasting corrosion resistance can be obtained.

[0023] Furthermore, in the antifouling coating that inhibits marine organism adhesion according to the above embodiment, it is preferable to use a linear organopolysilosan having silanol groups at both ends of the molecular chain in the room-temperature curable coating component, which has a viscosity of 0.1 to 50 Pa·s at 23°C. If the viscosity of the organopolysilosan at 23°C is less than 0.1 Pa·s, the elongation of the resulting coating film cannot be sufficiently ensured, and similarly, if it exceeds 50 Pa·s, the workability during coating film formation will be poor, which is undesirable.

[0024] Furthermore, the marine organism fouling-inhibiting antifouling coating of the present invention further contains a superparamagnetic fluid in the room-temperature curing coating component described above. Since the room-temperature curing coating itself is a type of silicone resin coating, its coating film exhibits a certain degree of marine organism fouling-inhibiting antifouling properties. However, a coating film formed using a coating containing a superparamagnetic fluid exhibits even better marine organism fouling-inhibiting antifouling properties.

[0025] While the detailed reasons need to be clarified through future research, it is presumed that when seawater flow (movement of electrolyte solution) occurs due to the movement of ships or the influence of waves, extremely small currents and magnetic gradients are generated electromagnetically in the superparamagnetic fluid contained in the coating film of the present invention. This disrupts the cell membrane potential of barnacles, seaweed, bacteria, etc., inhibiting initial attachment (biofilm formation), and consequently resulting in good antifouling properties that suppress marine organism adhesion.

[0027] In the aforementioned antifouling paint for inhibiting marine organism adhesion, at least one bis(trialkoxysilylalkyl)amine compound selected from bis[2-(trimethoxysilyl)ethyl]amine, bis[3-(trimethoxysilyl)propyl]amine, bis[4-(trimethoxysilyl)butyl]amine, bis[2-(triethoxysilyl)ethyl]amine, bis[3-(triethoxysilyl)propyl]amine, and bis[4-(triethoxysilyl)butyl]amine can be used as the bis(trialkoxysilylalkyl)amine compound in the room-temperature curable paint component. More preferred aminobissilane compounds are bis[3-(trimethoxysilyl)propyl]amine and bis[3-(triethoxysilyl)propyl]amine.

[0028] Furthermore, in the aforementioned embodiment of the marine organism-fouling-inhibiting antifouling paint, it is preferable that the reaction product of the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound in the room-temperature curable paint component is obtained by reacting the titanium alkoxide compound in a ratio of 0.1 to 0.3 moles per mole of bis(trialkoxysilylalkyl)amine compound. This makes it possible to obtain a marine organism-fouling-inhibiting antifouling paint that has a small amount of unreacted bis(trialkoxysilylalkyl)amine compound or titanium alkoxide compound present in a free state, and can also provide a good rust prevention effect.

[0029] Furthermore, if the titanium alkoxide compound is less than 0.1 moles per mole of bis(trialkoxysilylalkyl)amine compound, the amount of unreacted bis(trialkoxysilylalkyl)amine compound relative to the titanium alkoxide compound will be large, resulting in weak adhesion of the marine organism-inhibiting antifouling coating to the substrate. Similarly, if it exceeds 0.3 moles, the amount of unreacted titanium alkoxide compound relative to the bis(trialkoxysilylalkyl)amine compound will be large, resulting in poor stability of the marine organism-inhibiting antifouling coating.

[0030] Furthermore, in the aforementioned embodiment of the marine organism-fouling-inhibiting antifouling coating, the content ratio of the reaction product of the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound in the room-temperature curable coating component is preferably 0.5 to 10% by mass in solid ratio with respect to the organopolysiloxane. If the content ratio of the reaction product of the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound with respect to the organopolysiloxane is less than 0.5% by mass, the adhesion of the marine organism-fouling-inhibiting antifouling coating film to the substrate will be weak, and a sufficient antifouling effect will not be obtained. Similarly, if it exceeds 10% by mass, the resulting marine organism-fouling-inhibiting antifouling coating will thicken and become gel-like, which is undesirable. [Effects of the Invention]

[0031] As described above, according to the present invention, it is possible to form a coating that exhibits predetermined marine organism adhesion-suppressing antifouling properties simply by applying and drying a coating containing the superparamagnetic fluid itself, without requiring an external power source, without the elution or detachment of components from the coating film, and furthermore, it is possible to provide a marine organism adhesion-suppressing antifouling coating that also has recoatability. [Brief explanation of the drawing]

[0032] [Figure 1] (a) is a diagram showing the state in which each test specimen is fixed to the iron plate, and (b) is a diagram showing an overview of the location where the iron plate with the various test specimens fixed to it is installed in the sea. [Modes for carrying out the invention]

[0033] The marine biofouling-inhibiting antifouling coating according to the present invention will be described in detail below using various experimental examples. However, the various experimental examples shown below are intended to illustrate the technical concept of the present invention and are not intended to limit the present invention to those shown in these experimental examples. The present invention is equally applicable to other embodiments included in the claims.

[0034] [Paint preparation for each experimental example] (Experimental Example 1) To a mixed solvent of 20 parts by mass of butyl acetate and 60 parts by mass of isopropyl alcohol, 16 parts by mass of bis[3-(trimethoxysilyl)propyl]amine (manufactured by Momentive Performance Materials Japan LLC) was added while stirring. Then, 4 parts by mass of tetran-butyl titanate (manufactured by Matsumoto Fine Chemical Co., Ltd.) was added, and stirring was continued at 30°C for 60 minutes. After that, the mixture was sealed and allowed to stand at 25°C for 24 hours. The reaction solution gradually changed from a colorless, transparent liquid to a dark, transparent yellow liquid. Next, 10 parts by mass of this reaction solution, after standing for 24 hours, was added to 100 parts by mass of a linear organopolysilosan having silanol groups at both ends of the molecular chain and a viscosity of 6 Pa·s, to prepare the room-temperature curable paint component of Experimental Example 1. This room-temperature curable paint component of Experimental Example 1 is substantially transparent, and no superparamagnetic fluid was added.

[0035] (Experimental Examples 2-4) Furthermore, before the room-temperature curing paint component hardened, magnetite (Fe3O4) (Ferrobeads®, FB-01SH (product name) manufactured by Ferrotec Corporation), whose main component is a superparamagnetic fluid with an average particle size of 10 nm, was added in amounts of 2 parts by mass (Experimental Example 2), 5 parts by mass (Experimental Example 3), and 30 parts by mass (Experimental Example 4), respectively, based on solid content. These were then thoroughly stirred and mixed to prepare the marine biofouling-inhibiting antifouling paints of Experimental Examples 2-4. These marine biofouling-inhibiting antifouling paints of Experimental Examples 2-4 exhibited a dark brown color, and the black color became darker as the proportion of superparamagnetic fluid increased.

[0036] (Experimental Example 5) A silicone resin antifouling coating of Comparative Example 2 was prepared by adding 5 parts by mass of titanium polymerization catalyst D-20 (product name, Shin-Etsu Chemical Co., Ltd.) to 95 parts by mass of silicone oligomer KR-500 (product name, Shin-Etsu Chemical Co., Ltd.) having a methoxy group. No superparamagnetic fluid was added to the silicone resin antifouling coating of this Experimental Example 5.

[0037] (Experimental Example 6) New Peraclin PRUS (product name, Chugoku Marine Paints Co., Ltd.), a commercially available silicone-based antifouling paint for small vessel propellers, was used as the silicone-based antifouling paint in Experimental Example 6. Although New Peraclin PRUS is normally used with an epoxy-based primer, for the purpose of comparison with other experimental examples, various tests were conducted using it alone without a primer.

[0038] The compositions of each paint used in Experimental Examples 1-6 are summarized in Table 1 below. [Table 1]

[0039] [Sea immersion test] As described above, immersion tests were conducted using each of the paints prepared in Experimental Examples 1 to 6. First, commercially available FRP plates (148 x 210 x 5 mm) were used as test specimens common to all tests, and each was coated using a roller application method, with a coating amount of 150 g / m² in Experimental Examples 1 to 4. 2 As such, in Experimental Example 5, the application amount was 100g / m². 2 In addition, in Experiment Example 6, 240 g / m 2 The paints were applied in this manner, dried at room temperature for 24 hours, and then cured at room temperature for 2 weeks. Multiple test pieces were then prepared, each coated with one of the paints described in Experimental Examples 1-6. The appearance of each test piece at this time is summarized in the "Before Sea Immersion Test" column of Table 2 below.

[0040] Next, the test pieces coated with each of the paints from Experimental Examples 1 to 6 were arranged and fixed to the surface of an iron plate, as shown in Figure 1(a), and suspended in seawater by ropes for a predetermined period to measure the attachment of shellfish. The test location was near Otoshima Fishing Port in Tamashima, Kurashiki City, Okayama Prefecture (see Figure 1(b)), and the test period was approximately six and a half months, from March 27, 2025 to October 8, 2025. The appearance of each test piece immediately after removal is summarized in the "After Sea Immersion Test" column of Table 2 below.

[0041] [Table 2]

[0042] The results shown in Table 2 indicate the following: First, the specimen in Experimental Example 5 was coated with a silicone resin antifouling paint and did not contain superparamagnetic fluid, yet barnacles were attached to its entire surface. Second, the specimen in Experimental Example 6 was coated with a paint commercially available as an antifouling system for small vessel propellers and did not contain superparamagnetic fluid, yet it showed excellent results with almost no barnacle attachment.

[0043] In contrast, the test specimen in Experimental Example 1 was coated with paint consisting only of the room-temperature curable paint component that constitutes the marine organism fouling-inhibiting antifouling paint of the present invention, and did not contain superparamagnetic fluid, but a small amount of shellfish attachment was observed. The test specimen in Experimental Example 2 was coated with paint in which 2 parts by mass of superparamagnetic fluid was added to 110 parts by mass of the room-temperature curable paint component that constitutes the marine organism fouling-inhibiting antifouling paint of the present invention, but a small amount of shellfish attachment was observed, although less than in the test specimen in Experimental Example 1. Furthermore, in the test specimens in Experimental Examples 3 and 4, the addition ratio of superparamagnetic fluid to 110 parts by mass of the room-temperature curable paint component was higher than in the test specimen in Experimental Example 2, at 5 parts by mass (Experimental Example 3) and 30 parts by mass (Experimental Example 4), respectively, but virtually no shellfish attachment was observed.

[0044] Based on a comprehensive assessment of the results of these experimental examples 2 to 4, it can be seen that the preferred addition ratio of superparamagnetic fluid to 110 parts by mass of the room-temperature curable paint component constituting the marine organism fouling-inhibiting antifouling paint of the present invention is 5 to 30 parts by mass. If the addition ratio of superparamagnetic fluid is less than 5 parts by mass relative to 110 parts by mass of the room-temperature curable paint component, as is clear from the results of experimental example 2, the amount of superparamagnetic fluid added is too small, resulting in poor marine organism fouling-inhibiting antifouling properties. Conversely, if it exceeds 30 parts by mass, the viscosity becomes too high, and the properties exhibited by the room-temperature curable paint component itself deteriorate, which is undesirable.

[0045] [Recoating Test] Using the same test pieces prepared in the same manner as those used in the "sea immersion test" described above, the same paint was recoated under the same application conditions as in each of the experimental examples. After drying at room temperature for 24 hours, the pieces were cured at room temperature for 2 weeks to prepare test pieces for the recoatability test of each of the experimental examples 1 to 6. The surface of these recoatability test pieces was visually observed, and those with no peeling observed across the entire surface were evaluated as "○", while those with some peeling observed were evaluated as "×". The results are summarized in Table 4 below.

[0046] Furthermore, adhesion tests were performed on the recoatability test specimens of Experimental Examples 1-6, prepared in this manner, based on the adhesion (cross-cut method) specified in JIS K 5600-5-6:1999. The adhesion test results were evaluated according to the classification table shown in Table 3 below, as specified in this JIS standard, and the results are summarized in Table 4. [Table 3]

[0047] [Table 4]

[0048] The results shown in Table 4 indicate the following: The test pieces in Experimental Examples 5 and 6 both exhibited poor recoating properties. This indicates that the paints used in Experimental Examples 5 and 6 were both silicone-based paints, which are inherently water-repellent and oil-repellent paints with excellent mold release properties, and therefore have virtually no recoating properties. In contrast, the test pieces in Experimental Examples 1 to 4 all contained a room-temperature curing paint component, and since this room-temperature curing paint component possesses recoating properties, it is considered that recoating properties were exhibited in both cases, whether the superparamagnetic fluid was included (Experimental Examples 2 to 4) or not (Experimental Example 1). Therefore, it was confirmed that the marine organism fouling inhibiting antifouling paint of the present invention possesses not only a marine organism fouling inhibiting antifouling effect but also recoating properties. [Industrial applicability]

[0049] As described above, the marine organism fouling-inhibiting antifouling coating of the present invention makes it possible to effectively suppress the fouling of marine organisms on marine structures, ships, coastal infrastructure, industrial plants that utilize seawater, and the like.

Claims

1. A linear organopolysilosan having a viscosity of 0.1 to 50 Pa·s at 23°C and silanol groups at both ends of the molecular chain, A room-temperature curable paint component comprising a reaction product of at least one bis(trialkoxysilylalkyl)amine compound selected from bis[2-(trimethoxysilyl)ethyl]amine, bis[3-(trimethoxysilyl)propyl]amine, bis[4-(trimethoxysilyl)butyl]amine, bis[2-(triethoxysilyl)ethyl]amine, bis[3-(triethoxysilyl)propyl]amine, and bis[4-(triethoxysilyl)butyl]amine and at least one titanium alkoxide compound selected from tetran-butyl titanate, butyl titanate dimer, and tetraoctyl titanate, The aforementioned room-temperature curable paint component further contains a superparamagnetic fluid, The superparamagnetic fluid contains iron(III) oxide (Fe₃O₄) nanoparticles with a particle size of 5 to 20 nm, and the content ratio of these nanoparticles is 5 to 30 parts by mass per 110 parts by mass of the room-temperature curable paint component, thereby providing an antifouling paint that inhibits marine organism adhesion.

2. The reaction product of the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound is obtained by reacting the titanium alkoxide compound in a ratio of 0.1 to 0.3 moles per mole of the bis(trialkoxysilylalkyl)amine, as described in claim 1.

3. The marine biofouling inhibitory antifouling paint according to claim 1 or 2, characterized in that the content of the reaction product of the bis(trialkoxysilylalkyl)amine compound and the titanium alkoxide compound is 0.5 to 10% by mass in solid ratio with respect to the organopolysiloxane.

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