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 method comprises the step of applying to said surface a bio-jelly producing agent comprising a compound of the formula III: wherein X" is selected from the group consisting of hydrogen, carboxyl, hydroxymethyl, aldehyde, carbonyl and amide, when X" is carboxyl, it may be an ester or a salt thereof; Y" is selected from the group consisting of halogen, alkyl, halogenated alkyl, nitro, alkoxy, carboxyl, ester, cyano, azo, azomethine, amino, alkoxysilyl and alkoxysilylalkyl; R is selected from the group consisting of hydrogen, alkyl and halogen; q is an integer of 0-2 and p is an integer of 0 or 1.

Description: Art Field The present invention relates to a method for preventing 'settlement of aquatic fouling organisms on surface of aquatic structures, such as ships or bridges. More particularly, the present invention relates to a method to prevent it by means of bio-jelly produced on the said surface. Prior Art When aquatic organisms, such as barnacles, tubeworms, tunicates, bryozoa, oyster, tubeworms and algae settle on outer surface of a ship bottom, total weight of the ship and down hydraulic resistance are increased and causes to slow down cruising speed. It lead industrial problems including shortening of life and increasing of fuel requirement. Many method for preventing settlement of such organisms has been investigated, for example, biological method such as using natural enemy; a method with 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; remove 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 hazards. Particularly, tin compound, most popular antifouling agent, had been founded 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 preventing settlement of visible size aquatic fouling organisms on the surface of an aquatic structure, comprising the step of producing a bio-jelly on said surface. In particular the present invention relates to 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 III: wherein X" is selected from the group consisting of hydrogen, carboxyl, hydroxymethyl, aldehyde, carbonyl and amide, when X" is carboxyl, it may be an ester or a salt thereof; Y" is selected from the group consisting of halogen, alkyl, halogenated alkyl, nitro, alkoxy, carboxyl, ester, cyano, azo, azomethine, amino, alkoxysilyl and alkoxysilylalkyl; R is selected from the group consisting of hydrogen, alkyl and halogen; q is an integer of 0-2 and p is an integer of 0 or 1. Preferred embodiments of the invention become apparent from the dependent claims. On surface of an aquatic structure, such as outer wall of a ship bottom,' a thin slime layer having slimy texture is adhered. Conventionally the slime layer has been thought in the art that should be removed as foulant. However, we have now made an unexpected discovery that slime layer thickly deposited on 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 of a relatively thick slime layer, e.g. a bio-jelly, on surface of an aquatic structure is effective to prevent the settlement. In the present method, bio-jelly is produced on surface of a structure by applying a bio-jelly producing agent on the surface. Definitions In the present specification, the term "aquatic fouling organisms" means attached organisms which settle on surface of structures in aquatic atmosphere and lead 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 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 an 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 the 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, slime layer having thickness of greater than 0.3 mm is called as 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 in 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 polysaccharide. The preferred polysaccharide are composed from one or more neutral monosaccharide including rhamnose, mannose, arabinose, glucose and.the like. More preferably, at least 60 % by weight of the polysaccharide are composed from such neutral monosaccharide. According to the present method, bio-jelly can be produced on surface of an aquatic structure by means of a paint containing a kind of compound. Such a compound useful for the present method includes 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 thick bio-jelly soon. In the present specification, such a compound is called as bio-jelly producing agent. The bio-jelly producing agents used in the method of the present invention include a compound having a styryl or cinnamoyl group of the formula III: wherein, X" is selected from the group consisting of hydrogen, carboxyl, hydroxymethyl, aldehyde, carbonyl and amide; when X" is carboxyl, it may be an ester or salt thereof; Y" is selected from the group consisting of halogen, alkyl, halogenated alkyl, nitro, alkoxy, carboxyl, ester, cyano, azo, azomethine, amino, alkoxysilyl and alkoxysilylalkyl; R is selected from the group consisting of hydrogen, alkyl and halogen; q is an integer of 0-2, p is an integer of 0 or 1. The compounds defined as above formula III can be divided into two categories, one of which is a styrene derivative wherein X" is hydrogen, the other is a cinnamoyl derivative wherein X" is a carboxyl (cinnamic acid), a hydroxymethyl (cinnamic alcohol), an aldehyde (cinnamic aldehyde) or an amide (cinnamic amide). The aromatic ring of the compound or the carbon atom bonded directly to the aromatic ring may have a substituting group. The aromatic group may have an unsaturated ethylenic substituent, such as vinyl to provide for example divinyl benzene (p=1). It may have another substituent (Y") which may be the same as above. When q is 0, Y" represents hydrogen. The number of substituent Y" is preferably equal to or less than 2. When Y" is a halogen, it may be any one of F, Cl, Br and I, however, Cl or Br is preferable. When Y" is an alkyl, it may be saturated or unsaturated, branched or unbranched an alkyl, a cycloalkyl or an aralkyl having 1-18, preferably 1-12, more preferably 1-10 carbon atoms..Higher number of carbon atoms or substituents is not preferable since molecular weight per styryl or cinnamoyl group (equivalence) is too high. The alkyl group may be substituted by a halogen. Another examples of Y" include nitro, cyano, azomethine, azo, alkoxy and alkoxysilyl. When Y" is an alkoxy or an alkoxysilyl, an alkoxy having 1-2 carbon atoms is preferable. The alkoxysilyl may be an alkoxysilylalkyl, and the alkyl moiety has preferably 1-2 carbon atoms. The substituent Y" may be a reactive group, for example, hydroxyl, carboxyl, amino, ammonium, sulfonate, phosphonium and sulfonium, and in case of carboxyl group, it may be an organic or inorganic salt, or an ester thereof. The onium or carboxyl group is important for controlling characteristics of the bio-jelly producing agent including ion property, compatibility with another additives of the paint into which the agent is incorporated and affinity with the base resin of the paint in order to control the quality of the paint composition to meet the condition of surrounding water and required emission. As well as the onium or carboxyl group, when Y" is an alkyl, an alkoxyl or an ester, the length of the alkyl moiety or the ester residue is important for controlling affinity, lipophilic character and compatibility of the bio-jelly producing agent in order to control emission or releasing character of the paint composition. R is selected from the group consisting of hydrogen, alkyl, phenyl, halogen and the like, and typically, is hydrogen. When R is an alkyl, it may be a cycloalkyl or an aralkyl having 1-18, preferably 1-9, and more preferably 1-3 carbon atoms, and typically is methyl or ethyl. When it is a halogen, it may be chloro or bromo. The number of the substituent(s) is equal to or less than 2, and preferably 0 or 1. P is 0 or 1, especially 0. The molecular weight of the compound having a styryl or cinnamoyl group used in the present invention is 100-800, preferably is 100-600. When the molecular weight is higher than 800, thickness of slime layer is decreased and bio-jelly formation may be insufficiently. In addition, not only molecular weight, but also styryl equivalent or cinnamoyl equivalent is preferably about 100-600. When the bio-jelly producing agent of the present invention is a cinnamic acid derivative, it may be an ester or a salt. Especially, the cinnamic acid ester is efficient for deposition of bio-jelly. The preferable ester is an ester with branched or unbranched alcohol having 1-18, more preferably 1-12, especially 1-10 carbon atoms. The salt may be either organic or inorganic. Examples of inorganic salt include salt of alkaline metal such as Na and K, alkali earth metal such as Ca and Mg, ammonium, Mn, Zr(O), Al, Zn and Fe. Examples of organic salt include salt of amines, alkanol amines, polyamines and N-heterocyclic compounds such as imidazoline. The bio-jelly producing agents are commercially available or may be synthesized according to conventional process. The bio-jelly producing agent may be incorporated into an appropriate paint composition which can be applied to surface of an aquatic structure. Unlike tin compounds, the bio-jelly producing agent does not become 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 bio-jelly producing paint composition may also comprise 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, number-average molecular weight of 1000-50000, more preferably of 5000-30000, and 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 amount of bio-jelly producing agent may be released into the water, and therefore, antifouling activity cannot be kept for enough term. 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 may contain the bio-jelly producing agent preferably 15-75 %, more preferably 20-60 % by weight of solid component of the composition. The composition also contains the binder resin preferably 20-70 %, more 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, an amount of known antifoulant, pesticide or herbicide within the range which do not inhibit produce of bio-jelly may be added to the composition. 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 a structure are peeled gradually by mechanical force due to such as wave or cruising of the ship, and new bio-jelly is then produced. To facilitate the reproducing of the bio-jelly, it is preferred that the paint film itself are abraded gradually due to cruising or wave and a new paint surface is revealed successively. On this newly revealed paint surface, deposition of bio-jelly is better than the old one and 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. 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. Initiation paint film thickness (d 0 ) of the dried disk was determined exactly with a roughness meter. The painted disk is rotated in sea at the 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 the d 0 and d 1 (i.e. d 1 -d 0 ) was determined as degree of film consumption. The bio-jelly producing paint showing the degree of film consumption of 2-40 µm is useful for the present invention. To further illustrate this invention, and not by way of limitation, the following examples are given. EXAMPLES Reference - Example 1 (not according to the invention) 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. Reference 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. Examples 1-28 A Bio-jelly producing paint composition was prepared by mixing 20 g of butyral resin, 15 g of methylethyl ketone and 15 g of respective bio-jelly producing agents listed in table 1 homogeneously and determined its properties according to the procedure of reference-example 1. 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 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 1. Comparative example 2 A paint composition similar to example 1 with the exception of using 15 g of cuprous oxide and 2 g of rosin 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 1. Comparative example 3 A paint composition was prepared by dissolving 20 g of butyral resin into 15 g of methylethylketone. The properties of the paint were determined according to the procedure of example 1. The results are shown in table 1. Comparative example 4-7 A paint composition similar to example 1 with the exception of using xylene, ethylbenzene, vinylcyclohexane and ethylcyclohexane instead of the bio-jelly producing cinnamoyl compound was prepared and determined its properties according to the procedure of example 1. The results are shown in table 1. Comparative example 8 A glass plate having same size as the acrylic plates of above examples was soaked as is into sea at the temperature of 12-18 °C. After 2 weeks, 1, 2, 4 and 8 months, thickness of slime layer deposited and amount of fouling organisms settled on the surface of the plate was determined. The results are shown in table 1. Comparative example 9 An acrylic plate same as above examples was soaked as is into sea at the temperature of 12-18 °C. After 2 weeks, 1, 2, 4 and 8 months, thickness of slime layer deposited and amount of fouling organisms settled on the surface of the plate was determined. The results are shown in table 1. Examples 29-46 (antibiotic activity) An antibiotic activity of a compound listed in table 2 was evaluated according to reference-example 2. The results are shown in table 2. Comparative example 10 An antibiotic activity of TBTO was evaluated according to reference-example 2. The result is shown in table 2. Comparative example 11 An antibiotic activity of cuprous oxide was evaluated according to reference-example 2. The result is shown in table 2. Comparative example 12-15 An antibiotic activity of xylene, ethylbenzene, vinylcyclohexane or ethylcyclohexane was evaluated according to the procedure of reference example 2. The results are shown in table 2. Comparative example 16 With the exception of immersing the disk into acetone without test compound, example 29 was repeated and evaluated background activity. The result is shown in table 2. bio-jelly producing agent inhibition zone (mm) Ex. 29 cinnamic acid 7 Ex. 30 methylcinnamate 7 Ex. 31 ethylcinnamate 7 Ex. 32 butylcinnamate 7 Ex. 33 n-propylcinnamate 7 Ex. 34 i-propylcinnamate 7 Ex. 35 hexylcinnamate 7 Ex. 36 2-ethylhexylcinnamate 7 Ex. 37 n-octylcinnamate 7 Ex. 38 nonylcinnamate 7 Ex. 39 laurylcinnamate 7 Ex. 40 styrene 7 Ex. 41 divinylbenzene 7 Ex. 42 α-methylstyrene 7 Ex. 43 chlorostyrene 7 Ex. 44 chloroethylstyrene 7 Ex. 45 trimethoxysilylstyrene 7 Ex. 46 triethoxysilylstyrene 7 Comp. Ex. 10 (TBTO) 15 Comp. Ex. 11 (Cu 2 0) 12 Comp. Ex. 12 (xylene) 7 Comp. Ex. 13 (ethylbenzene) 7 Comp. Ex. 14 (vinylcyclohexane) 7 Comp. Ex. 15 (ethylcyclohexane) 7 Comp. Ex. 16 (control (disk)) 7 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 the 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 mgkoh/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 mgkoh/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 3 were synthesized. Examples 47-65 An antifouling paint composition of the present invention were prepared according to the formulations listed in tables 4-7, using above obtained varnishes. Comparative examples 17-24 A paint composition containing no bio-jelly producing agent was prepared with components listed in table 8. Comparative Example 17 18 19 20 21 22 23 24 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 put into 1m 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 9. settlement prevention 2 weeks 1 month 2 months 4 months 6 months Ex. 47 0/1 0/1 0/1 0/2 0/2 Ex. 48 0/2 0/2 0/2 0/2 0/3 Ex. 49 0/1 0/1 0/2 0/2 0/3 Ex. 50 0/2 0/2 0/2 0/2 0/2 Ex. 51 0/1 0/2 0/1 0/2 0/3 Ex. 52 0/1 0/1 0/1 0/2 0/2 Ex. 53 0/2 0/2 0/2 0/2 0/3 Ex. 54 0/2 0/2 0/3 0/2 0/2 Ex. 55 0/2 0/2 0/2 0/3 0/3 Ex. 56 0/1 0/1 0/3 0/3 0/2 Ex. 57 0/2 0/2 0/2 0/2 0/2 Ex. 58 0/1 0/1 0/2 0/2 0/2 Ex. 59 0/2 0/2 0/2 0/3 0/3 Ex. 60 0/2 0/2 0/2 0/2 0/3 Ex. 61 0/2 0/2 0/3 0/2 0/3 Ex. 62 0/2 0/3 0/2 0/2 0/3 Ex. 63 0/1 0/2 0/2 012 0/2 Ex. 64 0/1 0/1 0/2 0/2 0/3 Ex. 65 0/2 0/3 0/2 0/2 0/3 Comp. Ex. 17 5/0.1> 15/0.1> 40/0.1> 100/0.1> 100/0.1> Comp. Ex. 18 5/0.1> 15/0.1> 40/0.1> 100/0.1> 100/0.1> Comp. Ex. 19 5/0.1> 15/0.1> 60/0.1> 100/0.1> 100/0.1> Comp. Ex. 20 10/0.1> 20/0.1> 75/0.1> 100/0.1> 100/0.1> Comp. Ex. 21 5/0.1> 15/0.1> 65/0.1> 100/0.1> 100/0.1> Comp. Ex. 22 10/0.1> 20/0.1> 70/0.1> 100/0.1> 100/0.1> Comp. Ex. 23 0/1 0/2 paint was peeling off. Comp. Ex. 24 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 III: wherein X" is selected from the group consisting of hydrogen, carboxyl, hydroxymethyl, aldehyde, carbonyl and amide, when X" is carboxyl, it may be an ester or a salt thereof; Y" is selected from the group consisting of halogen, alkyl, halogenated alkyl, nitro, alkoxy, carboxyl, ester, cyano, azo, azomethine, amino, alkoxysilyl and alkoxysilylalkyl; R is selected from the group consisting of hydrogen, alkyl and halogen; q is an integer of 0-2 and p is an integer of 0 or 1. The method of claim 1, wherein the compound of the formula III is selected from the group consisting of cinnamic acid, cinnamic acid ester, cinnamate salt, styrene, divinylbenzen and a-substituted styrene. The method of claim 1 or 2, wherein the bio-jelly deposited on the surface of the aquatic structure contains polysaccharides. The method of claim 3, wherein at least 60% of the polysaccharides are composed of neutral monosaccharide unit selected from the group consisting of rhamnose, mannose, arabinose and glucose. The method of any one of claims 1 to 4 wherein the step of applying the bio-jelly producing agent comprises the step of applying a paint composition comprising 20 to 70wt% 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 5, wherein the Tg of the binder resin is 15-120 °C. The method of claim 5 or 6 wherein the paint film of the composition shows a degree of film consumption of 20-40 µm/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