JPS638997B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an antifouling paint composition for preventing and protecting ships, underwater structures, etc. from adhesion of fouling organisms. A wide variety of fouling animals live in the sea, from ascidians, which are protochordates ranked next to vertebrates in animal taxonomy, to protozoa, the lowest protozoa. Polluted plants are growing. The antifouling agents used in antifouling paints have a remarkable long-term control effect against a wide variety of fouling organisms in general, and at the same time, they have low toxicity to the human body and have few environmental health problems. is required. In recent years, trialkyltin compounds, triphenyltin compounds, organic chlorine compounds such as DDT and BHC, and organic sulfur compounds such as tetraalkylthiuram disulfides and zinc dialkyldithiocarbamates have been used in antifouling paints as antifouling agents. Generally, these organic antifouling agents are selectively effective only against specific fouling organisms, but are completely ineffective against other organisms, and cannot be expected to be particularly effective in preventing the adhesion of seaweed. Furthermore, there are still many problems in practical use, such as the fact that if it were to have an antifouling effect against all fouling organisms in general, it would become more toxic to the human body. On the other hand, taking cuprous oxide, a typical copper-based antifouling agent, as an example, this compound shows a remarkable antifouling effect against all fouling organisms, while its toxicity to the human body is low, making it a highly practical antifouling agent. It has been used since ancient times as a staining agent. However, cuprous oxide, or cuprous oxide, is unstable and gradually changes to divalent copper salt when oxidized in seawater, and the elution rate of copper ions necessary for antifouling is maintained at 10 μg/cm ² /day. It is observed that the coating film eventually loses its antifouling effect despite the presence of copper compounds in the coating. This is because cuprous oxide dissolves in seawater as monovalent copper ions, but is immediately oxidized to divalent copper ions, which then react with hydroxide ions and carbonate ions, which are present in large quantities in seawater, and finally become basic. This is thought to be due to the change to copper carbonate. If we look at this as a change in solubility, the solubility of cuprous oxide in seawater is 5 to 3 x 10 ^-5 mol/at a pH of 8.2 and a temperature of 20°C.
On the other hand, the solubility of basic copper carbonate is
Under the same conditions, it is 4 to 2 x 10 ^-6 mol/, so there is a difference of 10 times between them. The present inventor researched a method for preventing or suppressing the oxidation of monovalent cuprous oxide into divalent copper compounds in seawater, and found that monovalent copper ions or divalent copper ions have a redox potential. Properties of metals that are subordinate to copper, namely bismuth, tin, lead, nickel, vanadium, cobalt, cadmium, iron, gallium, zinc, selenium, tellurium, manganese, diumconium, germanium, titanium, aluminum, and magnesium, as well as nonmetallic properties. However, we focused on the property that it is reduced by substances such as antimony, arsenic, and phosphorus that form cations, and is reduced to lower ions or metallic copper. We searched for substances that allow the above redox reaction to proceed over a long period of time and pose fewer environmental health problems. The redox reaction of these substances needs to proceed at a stable rate over a long period of time in an alkaline region. Therefore, magnesium and sodium, which have strong redox power and hydrolyze seawater, are quickly depleted in seawater and do not last long. Antimony, zinc, chromium, iron, By adding at least one of nickel, lead, and titanium, not only cuprous oxide but also poorly soluble copper such as cupric hydroxide and basic copper carbonate, which have a solubility in seawater of 3 x 10 ^-6 mol/or less, can be used. It has been found that the dissolution of compounds can be promoted, and by utilizing this, it is possible to provide an antifouling paint composition that can be effectively used for a long period of time. In other words, the elution mechanism of copper from general antifouling paints is not clear because monovalent copper ions are extremely unstable, but it elutes as monovalent copper ions with high solubility.
When this is oxidized to become divalent copper ions with low solubility, a unidirectional reaction progresses in which excess divalent copper ions become cupric hydroxide and basic copper carbonate and precipitate on the surface of cuprous oxide. However, it is thought that the elution rate of copper ions gradually decreases. In contrast, in the antifouling paint composition of the present invention, cupric hydroxide and basic copper carbonate deposited on the surface of cuprous oxide have high solubility due to added reducing substances such as tin, antimony, and iron. It is believed that a reaction in the opposite direction of reduction to a monovalent copper compound occurs, and that by maintaining an equilibrium between these two forward and reverse reactions at a certain point, a more stable and high elution rate of copper ions can be obtained. The antifouling paint composition of the present invention includes a sparingly soluble copper compound and a reducing substance that has a lower redox potential than the copper compound and is sparingly soluble in water. The poorly soluble copper compound referred to here refers to a copper compound that is generally said to be insoluble, with a solubility in seawater of PH8.2 of 1 x 10 ^-4 mol/or less at 20°C, and specifically copper oxides and sulfides. , hydroxide, rhodanide, ferrocyanide, basic copper carbonate, copper silicate, copper phosphate,
and sparingly soluble organic copper compounds that dissociate into copper ions. Tin, antimony, zinc, chromium, iron, nickel, lead, and titanium used in the present invention can be used alone, of course;
It can also be used as an alloy of two or more of these metals. In addition, the particle size affects the reduction rate and sustainability of the reducing agent, so it varies depending on the paint composition, purpose of use, etc., but in consideration of coating film performance and painting workability, particles finer than 250 mesh are used. In the antifouling paint composition of the present invention, the combination of a poorly soluble substance and a reducing substance and their blending ratio vary depending on the method and purpose of using the antifouling paint. For example, if long-term antifouling properties are not required, the amount of cuprous oxide mixed is as low as 20 to 35% by weight, but antimony, iron, titanium, etc., which have strong reducing power, are added at 0.1 to 30% by weight of cuprous oxide. %, and if you expect stain resistance for more than 2 years, add 40 to 50% by weight of cuprous oxide to nickel, zinc, lead, etc. whose reducing action is relatively slow and long-lasting. Copper 5~
Add 60% by weight. For copper rhodanide, cupric hydroxide, basic copper carbonate, etc., which have lower solubility than cuprous oxide, there are substances that have a strong reducing effect that increases the initial dissolution rate, and substances that are persistent. By using these in combination, a stable elution rate can be obtained. However, it is not enough to accelerate the elution rate of copper without limit;
It is sufficient to maintain the amount without significantly exceeding 10 μg/cm ² /day. As the antifouling agent in the antifouling paint composition of the present invention, in addition to the sparingly soluble copper compound, known organic antifouling agents such as organic tin compounds and organic sulfur compounds may be used in combination. It is also interesting to note that this discovery promotes the dissolution of poorly soluble copper compounds, making it possible to omit rosin, which was considered an essential condition in conventional copper-based antifouling paint compositions, thereby increasing the strength of the antifouling paint film. could be significantly improved. The invention is illustrated by the following examples. Examples and percentages are by weight unless otherwise specified. Example 1 5 g of cuprous oxide and 2 g of antimony powder as a reducing substance are placed in a 500 ml Erlenmeyer flask, 300 ml of seawater is added, and the flask is stored while stirring. During storage, seawater is refreshed once a week, and a portion of the sample is taken out at regular intervals.
The solubility of copper in seawater adjusted to pH 8.2 and temperature 20℃ was measured. Examples 2 to 4 The solubility of copper was measured in the same manner as in Example 1 except that the type of reducing substance was changed. Example 5 Cuprous oxide was replaced with cupric hydroxide, combined with antimony powder, treated in the same manner as in Example 1, and the solubility of copper was measured. Example 6 The antimony powder was replaced with 8-chromium stainless steel powder, treated in the same manner as in Example 5, and the solubility of copper was measured. Comparative Example 1 The antimony powder in Example 5 was replaced with red phosphorus powder, the same treatment as in Example 5 was carried out, and the solubility of copper was measured. These results are shown in Table-1.

[Table] As is clear from Table 1, the addition of the reducing substance according to the present invention was able to significantly increase the solubility of the poorly soluble copper compound. Examples 7 to 9 Examples 7 to 9 and Comparative Examples 2 and 3 in Table 2
Prepare the paint by uniformly mixing the ingredients of
A test plate coated with a thickness of 100 microns was suspended on a raft in the Tamano Sea area in Okayama Prefecture, and lifted out at regular intervals to measure the elution rate of copper ions eluted from the paint film. The results are shown in Table-3.

【table】

[Table] Note * Vinyl chloride = Vinyl butyl ether Copolymer resin Manufactured by Hoechst, West Germany

[Table] The coatings coated with the composition of the present invention showed a remarkable effect on the elution rate of copper ions compared to the coatings coated with the comparative paint. The minimum elution rate required for antifouling is 10 μg/cm ² /day. Example 10 Titanium powder 2.0 Cuprous oxide 20.0 Triphenyltin hydroxide 10.0 Red iron 13.0 Talc 10.0 Rosin 10.0 Chlorinated rubber 10.0 TCP 5.0 Xylene 20.0 Total 100.0 Example 11 Antimony powder 5.0 Cuprous oxide 20.0 Red iron 15 .0 Talc 15.0 Rosin 10.0 Chlorinated Rubber 10.0 TCP 5.0 Xylene 20.0 Total 100.0 Example 12 Nickel powder 10.0 Cuprous oxide 50.0 Rosin 8.0 Polyvinyl chloride (UCC VYHH) 6.0 TCP 2.0 Methyl isobutyl ketone 12.0 Toluene 12.0 Total 100.0 Example 13 Zinc powder 10.0 Cuprous oxide 50 .0 Polyvinyl chloride ( VYHH manufactured by UCC) 10.0 TCP 2.0 Methyl isobutyl ketone 14.0 Toluene 14.0 Total 100.0 Example 14 Stainless steel powder (8 chromium steel) 20.0 Cupric hydroxide 40.0 Rosin 8.0 Polyvinyl chloride (VYHH manufactured by UCC) 6.0 TCP 2.0 Methyl isobutyl ketone 12.0 Toluene 12.0 Total 100.0 Example 15 Lead powder 15.0 Cuprous oxide 40.0 Rosin 15.0 Linseed boil oil 10.0 Naphtha 20.0 Total 100.0 Comparative example 4 Cuprous oxide 20.0 Triphenyltin hydroxide 10.0 Zinc white 10.0 Red iron 10.0 Talc 5.0 Rosin 10.0 Chlorinated rubber 10.0 TCP 5.0 Xylene 20.0 Total 100.0 Comparative Example 5 Cuprous oxide 50.0 Zinc white 5.0 Red iron 5.0 Rosin 8.0 Polyvinyl chloride (VYHH manufactured by UCC) 6.0 TCP 2.0 Methyl isobutyl ketone 12.0 Toluene 12.0 Total 100.0 Comparative example 6 Cuprous oxide 40.0 Red iron 10.0 Talc 5.0 Gin 15.0 Linseed boil oil 10.0 Naphtha 20.0 Total 100.0 Comparative Example 7 Red iron 25.0 Zinc white 20.0 Talc 5.0 Rosin 20.0 Chlorinated rubber 7.0 TCP 3.0 Xylene 20.0 Total 100.0 Examples 16 to 19

【table】

Table: Synthesis Example of Polymeric Organotin Compounds 26 parts of tributyltin methacrylate and 14 parts of methyl methacrylate were dissolved in 60 parts of xylene, and 0.4 parts of benzoyl peroxide were added.
The temperature was gradually increased over 8 hours, cooling as necessary to control exotherm, and the final temperature was
The temperature reached 110℃. The resulting polymeric organotin compound 40
% solution was obtained. Comparative Example 8 40% solution of polymeric organotin compound 55 Cuprous oxide 30 Titanium white 10 Bentonite 1 Hydroquinone 0.1 Xylene 4 Total 100.1 The compositions described in the above Examples and Comparative Examples were made into a paint according to a conventional method. After applying the antifouling paint to a steel plate that had been previously coated with antirust paint, a one-year underwater immersion test was conducted in Uno Port, Tamano City, Okayama Prefecture. The results are shown in Table 4. The test results were divided into the following six levels and displayed according to the percentage of attachment of organisms. 5: 80% or more adhesion 4: 40-80% adhesion 3: 20-40% adhesion 2: 10-20% adhesion 1: 10% or less adhesion 0: No biofouling

[Table] As shown in Table 4, the antifouling paint composition according to the present invention was evaluated in an underwater immersion test, and as a result, 12
It was also possible to completely prevent the adhesion of seaweed by soaking the shells.

Claims (1)

[Scope of Claims] 1. An antifouling paint composition comprising a sparingly soluble copper compound and a reducing substance that has a lower redox potential than the copper compound and is sparingly soluble in water. 2. The antifouling paint composition according to claim 1, wherein the reducing substance is at least one of tin, antimony, zinc, chromium, iron, nickel, lead, or titanium. 3. The antifouling paint composition according to claim 1, wherein the reducing substance is at least one kind of alloy containing tin, antimony, zinc, chromium, iron, nickel, lead, or titanium.