JP2015000978A - Coating material and marine organism adhesion-preventing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating material which can suppress adhesion of organisms by active oxygen having a smaller organic component-decomposing power than free radicals, and lasts for a long time without decomposition of a synthetic resin in materials.SOLUTION: A coating material comprises a carbon nanotube, at least one of a metal oxide and a metal peroxide, and a synthetic resin. A mixing ratio of these components is adjusted so that a surface electrical resistivity in a dry coating film state is 10-10Ω/cm, and the carbon nanotube is contained in an amount of 1-10 wt.%.

Description

  The present invention relates to a coating material having a photocatalytic function and a marine organism adhesion suppression method using the coating material.

  As a coating material having a photocatalytic function, for example, there are a member having a photocatalytic function as disclosed in Patent Document 1 and a photocatalytic coating used for the member.

  This member or photocatalyst coating material having a photocatalytic function includes photocatalyst particles made of titanium oxide or zinc oxide, a silicone resin, and CNTs.

  Patent Document 2 discloses a marine organism adhesion prevention and deposit release composition in which a cylindrical nanofiller made of, for example, CNT is added to a polysiloxane-based polymer.

  In general, photocatalysts such as titanium oxide and zinc oxide generate free radicals such as hydroxyl radicals when UV light is incident. These free radicals decompose organic substances such as mold and marine organisms. It is.

  However, in the case of a photocatalyst paint, the synthetic resin, which is a component of the paint, is easily decomposed by free radicals. For this reason, for example, titanium oxide paints are decomposed even when pigments and pigments are mixed. There is a problem that the coating film cannot be made. Moreover, since the synthetic resin component in the paint is decomposed, there is a problem that the coating film does not last long.

  The composition described in Patent Document 2 does not have a photocatalytic function, and by using a cylindrical nanofiller, a highly non-adhesive surface is created against marine organisms so that the organisms cannot grab (attach). It is to make.

  The marine organism adhesion prevention and deposit removal composition described in Patent Document 2 has a problem that non-tackiness tends to be lost due to surface deterioration of the object to be protected protected by this composition.

Japanese Patent No. 4390135 Special table 2010-506705 gazette

  The present invention has been made in view of the above problems, and can suppress the adhesion of living organisms, and the decomposition power of organic matter is not too strong, so that it can last longer and add a dye or a pigment. It is an object of the present invention to provide such a coating material.

The present invention comprises carbon nanotubes, at least one of a metal oxide and a metal peroxide, and a synthetic resin, and the blending ratio thereof is such that the surface electrical resistance value in the state of a dry coating film is 10 ^2. The above problem can be solved by a coating material characterized in that the carbon nanotube is contained in an amount of 10 to ^4.3 Ω / cm and the carbon nanotube is contained in an amount of 1 to 10% by weight.

  According to the present invention, it is possible to generate active oxygen that has a lower decomposing power of organic components such as synthetic resins than free radicals, and thus the living organisms adhere without decomposing the synthetic resin components in the coating material. Can be suppressed. Further, since the synthetic resin is hardly decomposed, a desired color can be coated by mixing dyes and pigments.

The front view which shows typically the state which carried out the immersion test in the seawater with the steel plate (AJ, N, O) which applied the coating material which concerns on the Example of this invention with the steel plate (chemicoat and blank: Z) of a comparative example. Photomicrograph showing enlarged part of carbon nanotubes (CNTs) dispersed in the coating material according to the above example Explanatory drawing which shows the photograph which shows the state after immersion of the steel plates A-G with the evaluation etc. Explanatory drawing which shows the photograph which shows the state after immersion of the steel plate HJ, N, O, Z and the steel plate of Chemicoat, along with the evaluation etc. Diagram showing the relationship between the coating surface electrical resistance value and the biological adhesion rate on the steel sheet surface after immersion in seawater A diagram showing the relationship between the surface electrical resistance value of the coating film and the CNT content in the coating film 1000 × electron micrograph showing the surface of steel sheet A after the immersion test 3000 × electron micrograph of part of FIG. 7 (A-2-SE) 10000 × electron micrograph of part of (A-2-SE) (A-3-SE) 3000 × electron micrograph of part of FIG. 7 (A-4-SE) 10000 × electron micrograph of part of (A-4-SE) (A-5-SE) 1000 times electron micrograph showing the surface of steel plate B after the immersion test 3000 × electron micrograph of part of FIG. 12 (B-3-SE) 10000 × electron micrograph of part of (B-3-SE) (B-4-SE) 3000 × electron micrograph of part of FIG. 12 (B-7-SE) 10000 × electron micrograph of part of (B-3-SE) (B-5-SE) 1000 × electron micrograph showing the surface of steel sheet G after immersion test 3000 × electron micrograph of part of FIG. 17 (G-2-SE) 10000 × electron micrograph of part of (G-2-SE) (G-3-SE) 3000 × electron micrograph of part of FIG. 17 (G-4-SE) 10000 × electron micrograph of part of (G-4-SE) (G-5-SE) 1000 × electron micrograph showing the surface of steel sheet H after the immersion test 3000 × electron micrograph of part of FIG. 22 (H-2-SE) 10000 × electron micrograph of part of (H-2-SE) (H-3-SE) 3000 × electron micrograph of part of FIG. 22 (H-4-SE) 10000 × electron micrograph of part of (H-4-SE) (H-5-SE) Explanatory drawing which shows the outline of the irradiation test which measures the relationship between an active oxygen generation amount, a material, and a light ray in the coating material which concerns on the Example of this invention. Diagram showing hydroxyl radical generation state in coating film samples 19 to 30 to be subjected to irradiation test Diagram showing generation state of singlet oxygen in coating film samples 31 to 36 Diagram showing hydroxyl radical generation state in coating film samples 37 to 44 Diagram showing the generation state of singlet oxygen in the coating film samples 45 to 48 Diagram showing active oxygen generation state in coating film of steel plates G, H, A and B after immersion in seawater in UV light irradiation test without seawater Diagram showing the active oxygen generation state in the UV light irradiation test of the coating films of steel plates G, H, A and B after immersion in seawater with seawater Diagram showing the relationship between the active oxygen signal intensity and the coating surface electrical resistance value in the coatings of steel plates A and B after immersion in seawater Diagram showing the relationship between the active oxygen signal intensity and the coating surface electrical resistance value in the coatings of steel sheets G and H after immersion in seawater The diagram which shows the generation | occurrence | production state of the singlet oxygen in the UV light irradiation test in the state without seawater of the coating film of the steel plates A and G after seawater immersion Diagram showing the generation of singlet oxygen in the presence of seawater

  Hereinafter, embodiments of the present invention will be described in detail.

In the embodiment of the present invention, the coating material includes carbon nanotubes (hereinafter referred to as CNT), at least one of a metal oxide and a metal peroxide, and a synthetic resin. In this state, the surface electrical resistance value is 10 ² to 10 ^4.3 Ω / cm, and the CNT is contained in an amount of 1 to 10% by weight.

  Here, the carbon nanotube (hereinafter referred to as CNT) is usually divided into a single layer and a multilayer, but in the present invention, either a single layer or a multilayer may be used. However, since the price of single-walled CNT is about 20 times that of multilayered CNT, it is preferable to use multilayered CNT.

  Examples of metals that form metal oxides or metal peroxides include zinc, narrowly defined alkaline earth metals (Ca, Sr, Ba, Ra) or broadly defined alkaline earth metals (Group 2) containing Be and Mg. Element) and 0.5 to 50% by weight is blended in the coating film.

  The synthetic resin is an organic / inorganic hybrid resin or silicone resin that is resistant to active oxygen and excellent in water resistance.

  The organic / inorganic hybrid resin used is one prepared by a sol-gel method based on an alkoxysilane, or a mixture of a colloidal resin and one of a urethane resin, an acrylic resin, an epoxy resin emulsion, and a dispersion. .

  As the silicone resin, an elastomeric wet-drying resin is used. The elastomeric wet-drying resin may be either solvent-based or water-based.

  When such a coating material was irradiated with UV light, the generation mechanism could not be confirmed, but singlet oxygen was generated, and attachment of organisms could be suppressed.

  Next, the Example in the case of using the coating material of this invention as a biological repellent antifouling coating apply | coated to a ship or a marine structure for marine organism adhesion suppression is demonstrated.

  In this embodiment, the adhesion of marine organisms is suppressed by a photocatalytic coating having marine organism repellent properties of ships and marine structures.

  This marine organism repellent paint (coating material) includes multilayer CNT, at least one of zinc peroxide and zinc oxide, and a synthetic resin as a base material.

  The composition of the coating material is such that at least one of zinc peroxide and zinc oxide is 0.5 to 50% by weight, and CNT is 1 to 10% by weight.

<Test example>
Mainly to confirm the marine organism repellent effect, the type of paint (water-based paint, solvent-based paint), test steel plate and solvent system coated with 12 kinds of paints with different combinations of CNT and zinc peroxide to the base paint A total of 16 comparative test steel sheets, 4 types of paint blanks, water-based paint blanks, chemical-coated blanks and chemical-coated blanks, were prepared. As shown in FIG. 1, Tokyo Bay in Ota-ku, Tokyo Was immersed in seawater for about 2 months, and a seawater immersion test was performed to measure the surface properties after immersion.

  The steel plates used were galvanized steel plates, each of which was undercoated (one-time coating) with an aquatic undercoat paint for galvanized steel plates (Suise Metal Plastic; manufactured by Taiyo Paint Co., Ltd.) Each test paint was applied twice as a top coat.

In addition, as a comparative test steel plate, an antifouling paint (Chemicoat (trade name) Blue; manufactured by Taiyo Paint Co., Ltd.) was applied, and three types of blank paint were added without water-based or solvent-based CNT / ZnO _2. What applied the paint was prepared.

As shown in Table 1, there are six types of test steel plates coated with water-based paints: steel plates A, B, C, D, E, and F. Steel plates coated with solvent-based paint are steel plates G and H. , I, J, N, and O. In Table 1, the composition is shown by weight ratio. In the case of water-based paint, the weight ratio between the base paint and liquid C, and in the case of solvent-based paint, the weight ratio between the base paint, liquid A and liquid B. ing.

As shown in Tables 2 and 3, there are two types of base paints, a glossy water-based paint and a matte water-based paint, and the solvent-based paint is a silicone rubber paint.

Here, the liquid C added to the base paint in the water-based paint and the liquid A and liquid B added to the solvent-based paint are shown in Table 4.

In Tables 5 and 6, the blending ratio is shown in order to clarify the blending amount of CNT and ZnO ₂ with respect to 40 parts of the resin content in the paint. The resin content in the numerical value of the base paint is 40 parts.

  The CNTs blended in the paint are roughly classified into single-walled CNTs and multilayered CNTs, but any of single-layered and multilayered materials may be used in the present invention. However, since single-walled CNTs are very expensive (about 20 times) compared with multilayered CNTs, multilayered CNTs were used.

Specifically, NC7000 (diameter: 9.5 nm, length (average): 1.5 μm, water / solvent dispersion (ultrasonication)) having a carbon purity of 90% manufactured by Nanosil (Belgium) was used. FIG. 2 shows an electron micrograph of this carbon nanotube. Table 7 shows data for the NC7000.

  FIG. 3 shows the immersion test results of the test steel plates A to G, and FIG. 4 shows the test results of the test steel plates H, I, J, N, O, the blank steel plate, and the chemi-coated steel plate. 3 and 4 show photographs showing the surface of the steel sheet after immersion, evaluations, and coating surface resistance values.

  The coating surface electrical resistance value was measured by leaving the test steel plate to stand for one week at room temperature, drying it thoroughly, and removing the dirt on the back surface as much as possible. The measuring device used was a Simco surface resistor (ST-4).

The state of the immersion test result is as shown in FIG. 3 and FIG. 4, and FIG. 5 shows the relationship between the coating surface electric resistance value and the biological adhesion rate. FIG. 5 shows that the bioadhesion rate becomes 0% when the coating surface electric resistance value is 10 ^4.3 Ω / cm or less (n = 4.3).

The minimum value of the coating surface electrical resistance as a result of the immersion test is ^103.3 Ω / cm (n = 3.3) in the test steel plate D. From FIG. Since it is estimated that the biofouling rate can be reliably 0%, the biofouling rate can be 0% even if the coating surface electrical resistance value is less than n = 3.3. Here, the minimum value of the coating surface electric resistance value can be set to 10 ² Ω / cm from an empirical rule for this type of coating film.

  FIG. 6 shows the relationship between the coating surface electric resistance value of the test steel sheet and the CNT content in the coating film. FIG. 6 shows that when the CNT content in the coating exceeds 6% by weight, the coating surface electrical resistance does not decrease even when the CNT content is increased. Accordingly, the CNT content may be functionally up to 6% by weight, but the content may be increased to increase the strength of the coating film. The maximum content is 10% by weight.

  In addition, the test steel sheets Z and O having a CNT content of 0.5% or less have a coating surface resistance value of n> 10, whereas the CNT content is 2.2%, 2.4%, In the case of 2.7% test steel sheets N, I and J, the coating surface electric resistance was less than n = 6.0, and although not 100%, the adhesion of organisms was suppressed, so the CNT content The minimum value is 1% by weight.

  Next, scanning electron microscope (SEM) photographs taken for confirming the antifouling function of the coating film by surface observation will be described.

  FIGS. 7 to 26 are 1000 times and 3000 times the test steel plates A and G having the most biological repellent effect and the test steel plates B and H having the least effect in the coating films after immersion in each of the aqueous and solvent systems. It is a 10,000 times magnified photograph.

  7 to 26, the alignment state of CNT and zinc peroxide was unknown, but the test steel plate B having a small biological repellent effect has a 1000-fold increase in FIG. 12 (B-7- SE) was found to be a species of marine life. The 3000 times image is shown in FIG.

Next, the stability of the coating agent, in particular, the presence or absence of coating caked during storage due to the blending of CNTs was confirmed for each of the water-based paint and the solvent-based paint. Table 8 shows the components of the water-based paint and the solvent-based paint for the test.

  Prepare 450g of each of the above two types of paint, put the water-based paint in a 500ml plastic container and the solvent-based paint in a 500ml can and let it stand in the test room at room temperature for 50 days. There was no.

Furthermore, a storage stability test was carried out at room temperature for two and a half months for the coating agents for test steel sheets A and H with a large amount of CNT and ZnO ₂ prepared for the above immersion test. No caking occurred even with the addition of zinc oxide. In addition, no precipitate was formed.

  Next, the presence or absence of the generation of hydroxyl radicals and singlet oxygen generated in the coating film by light irradiation and the strength measurement test in the case of the generation will be described.

  FIG. 27 shows an outline of an active oxygen measurement test. The test method is the electron spin resonance method, the measurement method is the strapping method, the electron spin resonance apparatus used is JES-RE1X, and the measurement engine is the Kanagawa Dental University electron spin resonance laboratory. The measurement test was performed four times.

The first time is based on halogen light irradiation assuming visible light. As shown in Table 9, the presence or absence of CNT, zinc peroxide, CNT + zinc peroxide, and the combination of these with pure water or seawater Samples 1 to 18 which were combined with halogen light irradiation or no irradiation conditions were subjected to hydroxyl radical and singlet oxygen measurement tests.

  As a result, hydroxyl radicals and active oxygen were not detected in any combination.

  Irradiation was performed for 1 minute using a 150 w halogen light source. In the measurement of samples 1 to 12, 1 mM CYPMPO was used as a trap material. In the measurement of samples 13 to 18, 40 mM 4-OH-TENP was used as a trap material in order to detect singlet oxygen.

Here, the used CNT (stock) was 5% by weight, and ZnO ₂ (stock) was 25% by weight.

As shown in Tables 10 and 11, the second active oxygen measurement test was performed using a combination of pure water, seawater, or a combination thereof, the presence or absence of CNT, the presence or absence of zinc peroxide, and the presence or absence of UV light irradiation. A measurement test was conducted for 19-48. In samples 37 to 48, zinc oxide was used instead of zinc peroxide.

  As a result, for samples 19 to 30, weak signals of hydroxyl radicals were detected both in the absence of seawater and in seawater immersion, as shown in FIG. For samples 31 to 36, a strong signal of singlet oxygen was detected as shown in FIG.

  As shown in Table 11, with respect to Samples 37 to 44, as shown in FIG. 30, a weak signal of hydroxyl radicals was partially detected as in Samples 19 to 30. On the other hand, in samples 45 to 48, a strong signal of singlet oxygen was detected in all samples (see FIG. 31).

Here, CNT (stock) was 5% by weight, and 128 ml was used for the measurement. ZnO ₂ (stock) was 5% by weight, and 32 ml was used for the measurement. ZnO (stock) was 5% by weight, and 32 ml was used for the measurement.

Irradiation with UV light (wavelength, UV-A + UV-B, 150 mW / cm ² ) for 1 minute was performed.

  CNT and zinc peroxide were in a weight ratio of 4 to 1, and when each was measured alone, ultrapure water was used instead of the material not added, and the total amount of samples was made equal. Moreover, it replaced with zinc peroxide and measured similarly also with zinc oxide (made by Wako Purechemical).

  In the measurement of samples 19 to 30 and 37 to 44, 1 mM CYPMPO was used as a trap material for the purpose of detecting hydroxyl radicals and superoxide. Alternatively, in the measurement of samples 31 to 36 and 45 to 48, 40 mM 4-OH-TEMP was used as a trap material for the purpose of detecting singlet oxygen.

Next, the active oxygen measurement test by the third UV light irradiation will be described. In this third test, as shown in Table 12, UV light was applied to the coating film after immersion of the test steel plates G, H, A, and B, and hydroxyl radicals and singlet oxygen were measured. .

  In either case, the hydroxyl radical signal could not be detected, and for singlet oxygen, a strong signal of active oxygen could be detected both in the presence and absence of seawater (Fig. 32, 33).

  Although singlet oxygen could be measured under each condition, the generation amount was reduced by adding seawater. Since no hydroxyl radical was detected, seawater addition was not measured.

Said test steel plate G, H, A, the relationship between the active oxygen signal intensity and the coating film surface resistivity 10 ⁿ Ω / cm in the coating film after immersion B shown in FIGS. 34 and 35. From FIG. 34, it can be seen that the smaller the coating surface electrical resistance value, the greater the active oxygen signal intensity.

Next, the fourth active oxygen measurement test by UV light irradiation will be described. As shown in Table 13, this test is based on UV light irradiation of the test steel sheets A and G before being immersed in seawater. In this case as well, as shown in FIGS. In addition, singlet oxygen was detected with a strong signal intensity, but in the case of the hydroxyl radical, this could not be detected.

  Compared with the steel plate A after the third immersion for the test steel plate A of the water-based paint, the signal strength increased without seawater before immersion, but the signal strength decreased with the seawater when compared with the third time.

  This can be estimated from the fact that singlet oxygen is generated by placing a spin trap material on the paint surface, and that there is unevenness in each component on the paint surface.

  For this reason, if the components are evenly distributed on the surface, it is considered that there is almost no change in the singlet oxygen generation capacity from the material even when immersed in seawater.

  From the above, it can be determined that the biological adhesion of the test steel plate is mostly due to the action of active oxygen (singlet oxygen).

  Although it is not clear from the above experimental examples, it is presumed that the photocatalytic function is obtained by the combination of zinc peroxide and / or zinc oxide and CNT, thereby generating active oxygen.

  As described above, since active oxygen has a weaker organic matter resolution than hydroxyl radicals, the synthetic resin contained in the coating material is less decomposed.

  The above experimental example is a test of marine organism repellent effect that suppresses the adhesion of organisms to the ship bottom and marine structures, but the present invention is not limited to this and In a structure or the like, it can be applied to a place where organisms such as molds are likely to be generated to suppress the adhesion of the organisms.

  Furthermore, this coating material suppresses biofouling by active oxygen and does not utilize hydroxyl radicals, such as titanium oxide as a photocatalyst. There is nothing to do. Therefore, various color pigments can be added to the coating material.

  In addition, the coating material of the present invention can be applied to a land structure to suppress the attachment of organisms.For example, when used on the bottom of a ship in contact with seawater or an offshore structure, as in the experimental example, The coating material of the present invention may be applied as an overcoat after applying the anticorrosive paint to the object.

Claims (6)

It comprises carbon nanotubes, at least one of a metal oxide and a metal peroxide, and a synthetic resin, and these compounding ratios have a surface electrical resistance value of 10 ² to 10 ^{4 in} a dry coating state ^. A coating material characterized by being ³ Ω / cm and containing 1 to 10% by weight of the carbon nanotubes. In claim 1,
The metal which forms the said metal oxide and metal peroxide is either zinc or alkaline-earth metal, and is 0.5-50 weight% of coating materials characterized by the above-mentioned. In claim 1 or 2,
The synthetic resin is one of an organic / inorganic hybrid resin and a silicone resin. In claim 3,
The organic / inorganic hybrid resin is one produced by a sol-gel method based on alkoxysilane, or a mixture of a colloidal resin and one of urethane resin, acrylic resin, epoxy resin emulsion and dispersion. A coating material characterized by being. In claim 3,
The silicone resin is an elastomeric wet-drying resin. A method for suppressing the attachment of marine organisms to a protected object,
After applying a rust preventive paint to the object to be protected, the coating material according to any one of claims 1 to 5 is applied as a photocatalyst paint on the film of the rust preventive paint. Method.