Method for preventing settlement of aquatic fouling organisms

Abstract: A method for preventing settlement of aquatic fouling organisms on surface of an aquatic structure without environmental hazard is provided. The method is based upon absolutely novel concept to prevent the settlement by means of thick slime layer, i.e. bio-jelly, deposited on said surface. The present invention also provides a bio-jelly producing agent and a bio-jelly producing paint both useful for the present method. Further, the present invention provides a novel low toxic antifouling agent.

Description: Art Field The present invention relates to a method for preventing settlement of aquatic fouling organisms on the surface of aquatic structures, such as ships or bridges. More particularly, the present invention relates to a method to prevent it by means of a bio-jelly produced on the said surface. The present invention also relates to a bio-jelly producing agent useful for the said method and a bio-jelly producing paint containing the same. The present invention also relates to a novel low toxic antifouling agent. Prior Art When aquatic organisms, such as barnacles, tubeworms, tunicates, bryozoa, oyster, tubeworms and algae settle on the outer surface of a ship bottom, total weight of the ship and hydraulic resistance are increased and causes to slow down cruising speed. This leads to industrial problems including shortening of life and increasing of fuel requirement. Many method for preventing settlement of such organisms have been investigated, for example, biological method such as using natural enemy; a method using a material having property of not to be settled such as copper alloy, and silicone or fluoride paint; preventing infiltration of larva with screen; killing the larva by means of, such as, lighting, ultraviolet lighting, coloring, sonication, increasing of temperature and limiting oxygen; removal of settled organisms by means of mechanical force, such as washing, washing by jet flow, brushing and vacuuming; and chemical or biochemical method such as methods using shellfish killing agent, repellent agent and antifouling agent. Recently, an antifouling paint containing an antifouling agent becomes popular because it can be easily applied for wide range, having high efficiency and easy for treating. The antifouling paint is designed so that the antifouling agent is emitted from the paint film into environmental water gradually or the paint film is abraded during the use in order to expose the newly developed surface successively. It is pointed out that such antifouling paint may be an environmental hazard . Particularly, tin compounds, most popular antifouling agents, have been found to be toxic against marine products in 1980's, and European and U.S. government began to regulate the use of tin containing antifouling paint. Development of a novel method for preventing settlement of aquatic organisms instead of using tin compound is highly desirable. However, no method has been developed except for using a relatively low toxic antifouling agent and many people in the art have been studying for low toxic agent instead for the tin compound. Summary of the Invention It is an object of the present invention to provide a method for preventing settlement of aquatic fouling organisms on surface of an aquatic structure without environmental hazard. The present invention provides the method basically without biocidal antifouling agent. Accordingly, the present invention provides a method for producing a bio-jelly layer having a thickness of at least 0.3 mm and being composed of metabolites of aquatic organisms on the surface of an aquatic structure in order to prevent the settlement of visible size aquatic fouling organisms thereon, which method comprises the step of applying to said surface a bio-jelly producing agent comprising a compound of the formula A-N=CH-B wherein A and B are organic moieties having 3 - 26 carbon atoms, respectively. Preferred embodiments of the invention become evident from the dependent claims. On the surface of an aquatic structure, such as the outer wall of a ship bottom, a thin slime layer having slimy texture is adhered. Conventionally it has been thought in the art that the slime layer should be removed as foulant. However, we have now made an unexpected discovery that slime layer thickly deposited on an aquatic surface, i.e. bio-jelly, is useful for preventing settlement of aquatic fouling organisms on the surface. Until now, there has not been any concept to grow up and utilize the slime layer for preventing settlement of aquatic organisms such as barnacles, algae, oyster, tubeworms, mussels. The inventors found that providing a relatively thick slime layer, e.g. a bio-jelly, on the surface of an aquatic structure is effective to prevent the settlement. In the present method, bio-jelly may be produced on the surface of a structure by applying a bio-jelly producing agent on the surface. The bio-jelly producing agent useful in the method of the present invention comprises a compound of the formula: A-N=CH-B wherein A and B are organic moieties having 3-26 carbon atoms respectively. A preferable compound is a benzylidene aniline derivative of the formula I: wherein n and m are integers of 0-5 respectively; X may be same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxyl having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomehine; Y may be same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxyl having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomethine. Especially useful benzylideneaniline derivatives include the compound of following formula II: wherein, X' is selected from the group consisting of hydrogen, halogen, hydroxyl and nitro; Y' is selected from the group consisting of hydrogen, chloro and methyl; and Z is selected from the group consisting of hydrogen and hydroxyl; in which at least two of X', Y' and Z are simultaneously hydrogen atoms. Definitions In the present specification, the term "aquatic fouling organisms" means attached organisms which settle on surface of structures in aquatic atmosphere and lead to industrial and economical disadvantage. Individuals of which grow up to visible size. They include animals, for example barnacles, mussels, hydroid, bryoza, tuunicates and tubeworms, and plants, for example algae. The term "aquatic structure" includes ship bottom, fish-net, race pipe, bridge, sea structures and the like. The term "slime layer" means a thin layer of slimy texture consisting of metabolites of a variety of aquatic organisms, and deposited on surface of an aquatic structure. The term "bio-jelly" means a slime layer having a thickness of equal to or more than 0.3 mm. The term "bio-jelly producing agent" means an agent comprising of a compound having an ability to promote deposition of the slime and to produce bio-jelly on surface of an aquatic structure. The term "bio-jelly producing paint composition" means a paint composition for aquatic structure having an ability to promote deposition of the slime and to produce bio-jelly on surface of an aquatic structure. The term "antifouling agent" means a biocidal agent for preventing settlement of the aquatic fouling organisms. The term "antifouling paint" means a paint for aquatic structure having an biocidal activity to prevent settlement of the aquatic fouling organisms. Detailed Description The present invention provides a method for preventing settlement of aquatic fouling organisms on surface of an aquatic structure comprising of a step to produce a thick slime layer, i.e. bio-jelly, on said surface. According to the present method, thickness of the slime layer is preferably equal to or more than 0.3 mm, more preferably 0.5-6 mm, and still more preferably, 1-5 mm. In the present specification, a slime layer having thickness of greater than 0.3 mm is called bio-jelly. In the present specification, the thickness of slime layer or bio-jelly is measured with a scale after the plate to be measured is out from water and leave it for one hour at room temperature. The slime layer or bio-jelly is composed essentially of metabolites of aquatic organisms, especially that of aquatic microorganisms. Some organisms, such as bacteria and diatoms, can inhabit the layer and are actually observed there. As a chemical material, the layer contains a variety of saccharide, polysaccharide, lipids, glycoproteins and phospholipid. According to the present method, preferred bio-jelly contains a number of polysaccharides. The preferred polysaccharides are composed from one or more neutral monosaccharides including rhamnose, mannose, arabinose, glucose and the like. More preferably, at least 60 % by weight of the polysaccharides are composed from such neutral monosaccharides. According to the present method, bio-jelly can be produced on the surface of an aquatic structure by means of a paint containing a kind of compound. Such a compound useful for the present method includes 1,8-cineole, benzylidene aniline derivatives and compounds having styrene or cinnamoyl group. When one or more such compounds are applied on surface of an structure and put it into aquatic atmosphere, deposition of slime layer on the surface is promoted and it becomes a thick bio-jelly soon. In the present specification, such a compound is called as bio-jelly producing agent. A bio-jelly producing agent of the present invention including a compound of the formula: A-N=CH-B wherein A and B are organic moieties having 3-26 carbon atoms respectively. Preferable compound is a benzylidene aniline derivative of the formula I: wherein n and m are integers of 0-5 respectively, X may be the same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxy having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomethine; Y may be the same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxy having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomethine. Preferably, n and m are 0 or 1 respectively. X is preferably a halogen, such as chloro or bromo; a hydrocarbon, especially a saturated or unsaturated aliphatic hydrocarbon having 1-18 carbon atoms which may or may not have a side chain, for example ethyl, isopropyl, n-propyl, t-butyl, hexyl, octyl, 2-ethylhexyl, nonyl, decyl, lauryl, stearyl and oleyl; an alkoxy, especially saturated or unsaturated an alkoxy group having 1-18 carbon atoms, for example ethoxy, butoxy, hexyloxy, octoxy, nonyloxy, stearyloxy, benzyloxy and naphthyloxy; hydroxy; and nitro. Examples of preferable bio-jelly producing agent of the present invention include 4'-ethylbenzylidene-4-ethyl aniline, 2'-isopropylbenzylidene-4-butoxyaniline, 4-nonyl benzylideneaniline, 4'-stearylbenzylidene-4-butoxyaniline, benzylidene-4-nonyloxyaniline, 4'-ethylbenzylidene-4-hexylaniline, 4'-ethoxybenzylidene-4-n-octylaniline, 2'-butoxybenzylidene-2-ethylaniline, 4'-naphthyloxy benzylidene aniline, 4'-ethylbenzylidene-4-nitroaniline, 3',4'-diethylbenzylidene-4-butylaniline, terephthalidene-di-4-butoxyaniline, di-4-butoxybenzylidene-p-phenylenediamine, benzylidene-4-n-octylaniline, 4'-nonylbenzylidene-4-methoxyaniline, 4'-ethylhexylbenzylideneaniline, 4',4-oleyloxybenzylideneaniline, 2'-ethoxy-4'-bromobenzylideneaniline, 4'-hexylbenzylidene-4-octoxyaniline, 4'-nonyloxybenzylidene-4-nonylaniline, 4'-nonylbenzylidene-2-butoxyaniline, benzylideneoctylamine, butylideneaniline, octylidene-4-hexylaniline, octylidene-4-octylaniline, cinnamilideneaniline and cinnamilideneoctylamine. Especially useful benzylideneaniline derivative includes a compound of the following formula II: wherein, X' is selected from the group consisting of hydrogen, halogen, hydroxyl and nitro; Y' is selected from the group consisting of hydrogen, chloro and methyl; and Z is selected from the group consisting of hydrogen and hydroxyl; in which at least two of X', Y' and Z are simultaneously hydrogen atoms. In the above compounds of the formula II, especially preferable bio-jelly producing agents include benzylidene aniline, benzylidene-4-chloroaniline, benzylidene-4-bromoaniline, benzylidene-4-nitroaniline, benzylidene-4-hydroxyaniline, 4'-methylbenzylideneaniline, 4'-chloro benzylideneaniline and 2'-hydroxybenzylideneaniline. The bio-jelly producing agents useful in the method of the present invention are commercially available or may be synthesized according to conventional process. The bio-jelly producing agent may be incorporated into an appropriate paint composition and applied on the surface of an aquatic structure. Unlike tin compounds, the bio-jelly producing agent does not become an environmental hazard, therefore it may be used as a paint composition for fish net by dissolving or suspending it into an appropriate solvent and if necessary, adding an appropriate polymer. The present invention also provides a method wherein the step of applying the bio-jelly producing agent comprises the step of applying a paint composition comprising the above defined bio-jelly producing agent and a binder resin. A binder resin suitable for the paint composition has a glass transition temperature (Tg) of 15-120 °C, more preferably of 25-100 °C, a number-average molecular weight of 1000-50000, more preferably of 5000-30000, and a hydroxyl number of 0-100 mg KOH/g, more preferably of 0-80 mg KOH/g. The above range of Tg contributes to strength and abrading characteristics of the paint film which is also preferable as conventional antifouling paint. When the Tg is lower than 15 °C, the paint film becomes too soft to keep itself from peeling into water during cruising of the ship. When the Tg is greater than 120 °C, some cracks may spread on the paint film. When the number-average molecular weight is lower than 1000, desired strength of the film cannot be obtained. When it is greater than 50,000, viscosity of the paint will be higher and excess solvent will be required in order to keep a definite viscosity. When the hydroxyl number is greater than 100, sea water may invade inside of the paint film and too much of the bio-jelly producing agent may be released into the water, and therefore, antifouling activity cannot be kept long enough. Examples of the binder resin which can be used in the present invention include acrylic, polyester, alkyd, vinyl, epoxy, urethan and urea resins. The bio-jelly producing paint composition contains the bio-jelly producing agent in an amount of 15-75 %, preferably 20-60 % by weight of solid component of the composition. The composition also contains the binder resin in an amount of 20 - 70 %, preferably 30-60 % by total weight of the composition. In addition to the bio-jelly producing agent and binder resin, the paint composition may comprise another ingredients including appropriate diluent, for example water, alcohol, alkyl glycol, cellosolve, acetate ester, xylene, toluene or ketone, extender pigment for example talc, coloring pigment and hardening agent. Further, to the composition of the present invention may be added an amount of known antifoulant, pesticide or herbicide within the range which does not inhibit the production of bio-jelly. The paint composition may be applied on a structure by any one of the methods known in the art, for example painting, soaking or spraying. The bio-jelly produced on the structure is peeled gradually by mechanical force due to waves or cruising of the ship, and new bio-jelly is then produced. To facilitate the reproduction of the bio-jelly, it is preferred that the paint film itself is abraded gradually due to cruising or waves and new paint surface is revealed successively. On this newly revealed paint surface, deposition of bio-jelly is better than on the old one and a thick layer of bio-jelly may be obtained again within a short time. Such an abrading character of the paint composition is estimated by degree of film consumption. In the present specification, the degree of film consumption is determined as follows. A test composition is applied on an acrylic resin disk and dried overnight at room temperature so that the thickness of the dried film is around 200 µm. The initial paint film thickness (d 0 ) of the dried disk was determined exactly with a roughness meter. The painted disk is rotated in sea water at a peripheral speed of 30 knot for one month, then, the thickness of the paint film (d 1 ) was determined with the roughness meter. The difference between d 0 and d 1 (i.e. d 1 -d 0 ) was determined as degree of film consumption. The bio-jelly producing paint showing a degree of film consumption of 2-40 µm/month, preferably 20-40 µm/month is useful for the present invention. The antifouling paint may be applied on surface of an aquatic structure by any known method including painting, soaking and spraying. To further illustrate this invention, and not by way of limitation, the following examples are given. EXAMPLES Example 1 A bio-jelly producing paint composition was prepared by mixing 20 g of butyral resin, 25 g of xylene, 5 g of n-butanol and 15 g of bio-jelly producing agent, 1,8-cineole homogeneously. The paint was applied on surface of an acrylic plate (300 mm x 100 mm x 2 mm) and dried so that the thickness of the paint film is about 200 µm. The plate was soaked into sea at the temperature of 12-18 °C. After 2 weeks, 1, 2, 4, and 8 months, thickness of slime layer (bio-jelly) deposited and amount of aquatic fouling organisms settled on the surface of the plate was determined. The results are shown in table 1. Comparative Example 1 A paint composition similar to example 1 with the exception of using 7 g of tributyltinoxide (TBTO), a conventional tin antifoulant, instead of 1,8-cineole was prepared and determined its properties according to the procedure of example 1. The results are shown in table 1. Comparative Example 2 A paint composition was prepared by dissolving 20 g of butyral resin into 40 g of xylene. The properties of the paint were determined according to the procedure of example 1. The results are shown in table 1. Comparative Example 3 The same acrylic plate used in example 1 was soaked into sea at the temperature of 12-18 °C. After 2 weeks, 1, 2, 4, and 8 months, thickness of slime layer (bio-jelly) deposited and amount of aquatic fouling organisms settled on the surface of the plate was determined. The results are shown in table 1. SETTLEMENT PREVENTION 2 weeks 1 month 2 months 4 months 8 months Example 1 1/0 2/0 2/0 3/0 2/0 Comparative Example 1 <0.1/0 <0.1/0 <0.1/0 <0.1/0 <0.1/0 Comparative Example 2 <0.1/5 <0.1/15 <0.1/100 <0.1/100 <0.1/100 Comparative Example 3 <0.1/5 <0.1/10 <0.1/70 <0.1/100 <0.1/100 thickness of slime layer(bio-jelly) (mm)/settlement of fouling organisms (area %) Determination of sugar component of bio-jelly. Bio-jelly or slime layer obtained in example 1 or comparative example 2 was removed and filtrated, and then purified by recrystallization with methanol. One hundred twenty mg of the each purified samples was putted into a tube and one ml aliquot of 4M trifluoroacetic acid was added. The tube was sealed under reduced pressure, and the sample was hydrolysed for 6 hours at 100 °C. Resulted product was dried under vacuo and dissolved into 1 ml of water. The solution was injected into HPLC and the peak area and retention time were compared with that of standard sample to determine and quantify the sugar. The result is shown in table 2. saccharide components of bio-jelly (wt %) monosaccharide Example 1 Comparative Example 2 2 weeks 2 months 2 weeks 2 months rhamnose 20.5 17.9 10.2 8.1 ribose 1.6 2.7 3.8 3.2 mannose 8.1 11.8 4.2 3.6 fructose 4.0 3.1 4.5 7.2 arabinose 5.7 5.7 36.9 42.8 galactose 4.8 10.8 3.2 2.2 xylose 0.6 0.9 10.2 16.3 glucose 57.9 47.1 27.0 16.6 Example 2 (antibiotic activity) (1) Preparation of medium: Two per cent solution of the determination disk medium (kyokuto kabushiki kaisha) in water was sterile at 120 °C for 30 minute. Into five parts by weight of the solution, one part by weight of culture of mixed bacteria comprising of Bacillus sp. , Vibrio sp. , and Salmonella sp. in bouillon medium was added, and the mixture was poured into a sterile petri dish to prepare an agar plate. (2) Preparation of paper disk: 1,8-cineole, a bio-jelly producing agent was used as a test compound. The test compound was dissolved in acetone. A paper disk of 7 mm diameter (TOYO ROSHI, #53) was immersed into the solution to absorb 25 mg of the test compound. (3) The paper disk obtained in (2) was dried and putted on the agar plate of (1), and incubated the plate for 5 days at 30 °C. Then, diameter of inhibition zone formed around the paper disk was determined and antibiotic activity of the bio-jelly producing agent was evaluated. The result is shown in table 3. Comparative example 4 With the exception of immersing the disk into acetone without test compound, example 2 was repeated and evaluated the background activity. The result is shown in table 3. Comparative example 5 An antibiotic activity of TBTO was evaluated according to the procedure of example 2. The result is shown in table 3. ANTIBIOTIC TEST sample Control (disk) 1,8-cineol TBTO diameter of inhibition zone (mm) 7 7 15 Examples 3-26 A bio-jelly producing paint composition was prepared by mixing 20 g of butyral resin, 25 g of xylene, 5 g of n-butanol and 15 g of respective bio-jelly producing agents listed in table 4. The properties of the composition were determined according to the procedure of example 1. The results are shown in table 4. Comparative example 6 A paint composition similar to example 3 with the exception of using 7 g of tin antifouling agent, i.e. TBTO instead of the bio-jelly producing agent was prepared, and determined its properties according to the procedure of example 1. The results are shown in table 4. Comparative example 7 A paint composition similar to example 3 with the exception of using 15 g of cuprous antifouling agent, i.e. cuprousoxide and 5 g of rosin instead of bio-jelly producing agent was prepared, and determined its properties according to the procedure of example 1. The results are shown in table 4. Comparative example 8 A paint composition similar to example 3 except for not containing any bio-jelly producing agent were prepared, and determined its properties according to the procedure of example 1. The results are shown in table 4. Examples 27-44 (antibiotic activity) An antibiotic activity of the compound listed in table 5 was evaluated according to the procedure of example 2. The results are shown in table 5. Comparative example 9 An antibiotic activity of cuprous oxide was evaluated according to the procedure of example 2. The result is shown in table 5. bio-jelly producing agent inhibition zone (mm) Ex. 27 4'-ethylhexylbenzylideneaniline 7 Ex. 28 4',4-oleyloxybenzylideneaniline 7 Ex. 29 2'-ethoxy-4'-bromobenzylideneaniline 7 Ex. 30 4'-ethoxybenzylidene-4-n-octylaniline 7 Ex. 31 2'-butoxybenzylidene-2-ethylaniline 7 Ex. 32 4'-naphthyloxybenzylideneaniline 7 Ex. 33 4'-ethylbenzylidene-4-nitroaniline 7 Ex. 34 3',4'-diethylbenzylidene-4-butylaniline 7 Ex. 35 telephtalidene-di-4-butoxyaniline 7 Ex. 36 di-4-butoxybenzylidene-p-phenylenediamine 7 Ex. 37 benzylidene-4-n-octylaniline 7 Ex. 38 4'-nonylbenzylidene-4-methoxyaniline 7 Ex. 39 4'-ethylbenzylidene-4-ethylaniline 7 Ex. 40 2'-isopropylbenzylidene-4-butoxyaniline 7 Ex. 41 4-nonylbenzylideneaniline 7 Ex. 42 4'-stearylbenzylidene-4-butoxyaniline 7 Ex. 43 benzylidene-4-nonyloxyaniline 7 Ex. 44 4'-ethylbenzylidene-4-hexylaniline 7 Comp. Ex. 9 (Cu 2 O) 12 Examples 45-52 A bio-jelly producing paint composition was prepared by mixing 20 g of butyral resin, 25 g of xylene, 5 g of n-butanol and 15 g of respective bio-jelly producing agent listed in table 6 homogeneously. The properties of the compound were determined according to the procedure of example 1. The results are shown in table 6. Comparative example 10 A paint composition similar to example 45 with the exception of using TBTO instead of the bio-jelly producing agent. The properties of the compound were determined according to the procedure of example 1. The results are shown in table 6. Comparative example 11 A paint composition similar to example 45 with the exception of using 15 g of cuprous oxide and 5 g of rosin instead of the bio-jelly producing agent. The properties of the compound were determined according to the procedure of example 1. The results are shown in table 6. Comparative example 12 A paint composition was prepared by mixing 20 g of butyral resin, 15 g of xylene and 5 g of butanol. The properties of the paint were determined according to the procedure of example 1. The results are shown in table 6. Comparative example 13 A paint composition was prepared by dissolving 20 g of butyral resin into 40 g of xylene. The properties of the paint were determined according to the procedure of example 1. The results are shown in table 6. Examples 53-60 (antibiotic activity) Antibiotic activity of the compound listed in table 7 was determined according to the procedure of example 2 The results are shown in table 7. Comparative example 15 With the exception of immersing the disk into acetone without test compound, example 2 was repeated and evaluated background activity. The result is shown in table 7. Comparative example 16 Antibiotic activity of TBTO was determined according to the procedure of example 2. The result is shown in table 7. Comparative example 17 Antibiotic activity of cuprous oxide was determined according to the procedure of example 2. The result is shown in table 7. bio-jelly producing agent inhibition zone (mm) Ex. 53 benzylideneaniline 7 Ex. 54 benzylidene-4-chloroaniline 7 Ex. 55 benzylidene-4-bromoaniline 7 Ex. 56 benzylidene-4-nitroaniline 7 Ex. 57 benzylidene-4-hydroxyaniline 7 Ex. 58 4'-methylbenzylideneaniline 7 Ex. 59 4'-chlorobenzylideneaniline 7 Ex. 60 2'-hydroxybenzylideneaniline 7 Comp. Ex. 15 (control (disk)) 7 Comp. Ex. 16 (TBTO) 15 Comp. Ex. 17 (Cu 2 O) 12 Preparation of binder resin: Preparation of binder resin A: Into a four-necked flask equipped with a stirrer, reflux condenser and dropping funnel, 69 parts by weight of xylene and 9 parts by weight of n-butanol were charged, and the mixture was kept at 110-120 °C. Into the vessel, a mixture of 67 parts by weight of styrene, 21 parts by weight of 2-ethylhexylacrylate, 12 parts by weight of 2-hydroxyethyl methacrylate and 2 parts by weight of azo-bis-isobutyronitryl were added dropwise over 3 hours at uniform rate and then the temperature was kept 2 more hours. Then, varnish A, in which solid content of the resin is 53.0%, and number-average molecular weight of the resin is 9900, was obtained. (Tg= 40 °C, OH value=50 mg KOH /g; wherein the Tg was determined according to JIS K7121-1987) Preparation of binder resin B: Into a four necked flask equipped with a stirrer, reflux condenser and dropping funnel, 69 parts by weight of xylene and 8 parts by weight of n-butanol were charged, and the mixture was kept at 110-120 °C. Into the vessel, a mixture of 45 parts by weight of 2-ethylhexyl methacrylate, 30 parts by weight of styrene, 6 parts by weight of 2-ethylhexyl acrylate, 16 parts by weight of 2-hydroxyethyl methacrylate, 3 parts by weight of methacrylic acid and 2 parts by weight of azo-bis-isobutyronitryl was added dropwise over 3 hours at uniform rate and then the temperature was kept 2 more hours. Then, varnish B, in which solid content of the resin is 56.0%, and number-average molecular weight of the resin is 8600, was obtained. (Tg= 25 °C, OH value=70 mg KOH/g; wherein the Tg was determined according to JIS K7121-1987) Preparation of binder resin C-N Similar to the procedure for preparing the binder resin B, binder resin C-N listed in table 10 were synthesized. Examples 107-148 An antifouling paint composition of the present invention were prepared according to the formulations listed in tables 11-14, using above obtained varnishes. Comparative examples 34-41 A paint composition containing no bio-jelly producing agent was prepared with components listed in table 15. Comparative Example 34 35 36 37 38 39 40 41 varnish A 50 45 40 50 varnish B 40 50 varnish M 50 varnish N 45 ethylbenzene 7.5 34 vinylcyclohexane 22.5 ethylcyclohexane 30 benzylideneaniline 20 25 titanium oxide 20 20 15 20 15 20 10 10 indian red 5 5 5 5 10 5 colloidal silica 1.5 1.5 1.5 1.5 1.5 1.5 3 3 xylene 16 16 13.5 23.5 9.5 23.5 5 n-butanol 7 7 The antifouling paint composition prepared as above was applied on surface of an acrylic plate (300 mm x 100 mm x 2 mm) and dried so that the thickness of the paint film was about 200 µm. The plate was putted into lm depth of sea at the temperature of 12-18 °C, and observed of amount of settled animals such as barnacles and tubeworms, and plants such as algae and green algae by naked eyes and evaluated by % of settled area. The results are shown in table 16. settlement prevention 2 weeks 1 month 2 months 4 months 6 months Ex. 107 0/1 0/2 0/3 0/3 0/3 Ex. 108 0/2 0/2 0/2 0/2 0/2 Ex. 109 0/2 0/3 0/2 0/2 0/3 Ex. 111 0/2 0/2 0/2 0/2 0/3 Ex. 112 0/1 0/1 0/2 0/2 0/3 Ex. 113 0/2 0/2 0/2 0/2 0/2 Ex. 115 0/1 0/1 0/1 0/2 0/2 Ex. 118 0/1 0/2 0/1 0/2 0/3 Ex. 124 0/2 0/2 0/2 0/2 0/3 Ex. 125 0/2 0/2 0/2 0/2 0/3 Ex. 126 0/1 0/3 0/2 0/2 0/2 Ex. 127 0/2 0/3 0/3 0/2 0/3 Ex. 128 0/2 0/3 0/3 0/3 0/2 Ex. 129 0/2 0/2 0/2 0/2 0/2 Ex. 130 0/1 0/1 0/1 0/3 0/3 Ex. 131 0/2 0/3 0/2 0/2 0/3 Ex. 132 0/1 0/1 0/1 0/2 0/3 Ex. 133 0/2 0/1 0/2 0/2 0/3 Ex. 135 0/2 0/1 0/2 0/2 0/3 Ex. 136 0/1 0/3 0/1 0/2 0/2 Ex. 138 0/1 0/1 0/1 0/2 0/2 Ex. 139 0/2 0/2 0/2 0/2 0/2 Ex. 140 0/2 0/2 0/3 0/2 0/2 Ex. 141 0/2 0/1 0/2 0/2 0/2 Ex. 143 0/1 0/1 0/1 0/2 0/2 Comp. Ex. 34 5/0.1> 15/0.1> 40/0.1> 100/0.1> 100/0.1> Comp. Ex. 35 5/0.1> 15/0.1> 40/0.1> 100/0.1> 100/0.1> Comp. Ex. 36 5/0.1> 15/0.1> 60/0.1> 100/0.1> 100/0.1> Comp. Ex. 37 10/0.1> 20/0.1> 75/0.1> 100/0.1> 100/0.1> Comp. Ex. 38 5/0.1> 15/0.1> 65/0.1> 100/0.1> 100/0.1> Comp. Ex. 39 10/0.1> 20/0.1> 70/0.1> 100/0.1> 100/0.1> Comp. Ex. 40 0/1 0/2 paint was peeling off. Comp. Ex. 41 0/0.2 5/0.17 30/0.17 100/0.17 100/0.17 settlement of fouling organisms (area %)/ thickness of slime layer(bio-jelly) (mm)

Claims: A method for producing a bio-jelly layer having a thickness of at least 0.3 mm and being composed of metabolites of aquatic organisms on the surface of an aquatic structure in order to prevent the settlement of visible size aquatic fouling organisms thereon, which method comprises the step of applying to said surface a bio-jelly producing agent comprising a compound of the formula: A-N=CH-B wherein A and B are organic moieties having 3-26 carbon atoms, respectively. The method of claim 1, wherein the bio-jelly deposited on the surface of the aquatic structure contains polysaccharides. The method of claim 2, wherein at least 60% of the polysaccharides are composed of neutral monosaccharide units selected from the group consisting of rhamnose, mannose, arabinose and glucose. The method of claim 1 wherein the compound is a benzylidene aniline derivative of the formula I: wherein n and m are integers of 0-5, respectively X may be same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxyl having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomethine group, Y may be the same or different and is selected from the group consisting of halogen, hydrocarbon or alkoxy having 1-20 carbon atoms, nitro, amino, hydroxyl, carboxyl, ester, cyano, azo and azomethine. The method of claim 4, wherein the benzylidene aniline derivative has the formula II: wherein X' is selected from the group consisting of hydrogen, halogen, hydroxyl and nitro; Y' is selected from the group consisting of chloro and methyl; and Z is selected from the group consisting of hydrogen and hydroxyl; and at least two of X', Y' and Z are hydrogen atoms. The method of any one of claims 1 to 5 wherein the step of applying the bio-jelly producing agent comprises the step of applying a paint composition comprising 20 to 70 wt.-% of a binder resin and 15 - 75 wt.-% of the bio-jelly producing agent, based on the total weight of the composition. The method of claim 6 wherein the Tg of the binder resin is 15-120°C. The method of claim 6 or 7 wherein the paint film of the composition shows a degree of film consumption of 2-40 µ m/month.

Inventors: HAMADE RYOJI, HARADA AKIO, NAKAMURA ISAO, OHSUGI HIROHARU, YAMAMORI NAOKI, YOKOI JUNJI, HAMADE, RYOJI, HARADA, AKIO, NAKAMURA, ISAO, OHSUGI, HIROHARU, YAMAMORI, NAOKI, YOKOI, JUNJI
Applicants: NIPPON PAINT CO LTD, NIPPON PAINT CO., LTD.
Application year: 1995
Main classification: C09D5
IPC codes: C09D5