JPH08165443A - Antifouling coating composition - Google Patents

Abstract

PURPOSE: To obtain a coating composition having excellent antifouling properties and having no bad influence on a human body and a natural environment at all, containing a compound with a specific structure. CONSTITUTION: This composition contains a compound of the formula (R1 and R2 are each H, acetyl or methyl) (e.g. kojic acid, diacetyl kojic acid kojic acid dimethyl ether). The composition is preferably mixed with a hydrolysis type binder resin containing 70-90mol% of lactic acid residue and 5-20mol% of caprolactone residue, a molar ratio of L-lactic acid residue/D-lactic acid residue in the lactic acid residue of 1-3 and 0.5-0.8 reduced viscosity (ηsp/c). The amount of the compound of the formula used is preferably 50-100 pts.wt. based on 100 pts.wt. of the resin. The solid content concentration of the composition is usually 20-30wt.% in using the composition for a fishing net and 40-60wt.% in applying it to a ship.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a composition for antifouling paint. Especially good for preventing contamination of aquatic organisms such as microorganisms and algae attached to the surface of various structures such as ships, marine structures, seawater introduction pipes and various tools such as fishing nets submerged in the sea or underwater. The present invention relates to an antifouling coating composition that gives various results.

[0002]

2. Description of the Related Art Ship bottoms, submarine communication cables, transportation pipelines, observation buoys, buoys, oil fences, silt protectors, piers, thermal or nuclear power plant cooling channels, industrial cooling channels, wave power buoys, Various equipment related to marine development and marine civil engineering, fishing nets, fishing gear, and other equipment, facilities and structures that are submerged in water for a long time include barnacles, mussels, hydrozoa, serpra, bryophytes, squirts, and sponges. Algae such as adherent animals and sea lettuce, green seaweed, Shiomizuro, Himidoro, Shiogusa, Mill, and adherent microorganisms that form slime such as cyanobacteria, diatoms, and bacteria (hereinafter collectively referred to as "fouling organisms") adhere However, for this reason, the above-mentioned devices, articles, facilities, structures, etc. suffer various losses.

For example, when a fouling organism adheres to a ship,
The frictional resistance between the hull and seawater increases, resulting in a decrease in ship speed and an increase in fuel consumption. Not only that, fouling organisms bring about great economic loss in terms of maintenance and operation, such as operation loss due to fouling of the ship bottom and economic loss such as cleaning costs. Alternatively, in a structure constructed in the ocean such as a pier, the anticorrosion coating film applied to enhance durability is deteriorated or corroded by fouling organisms, and as a result, the service life of the structure is shortened. Buoys and other floating structures lose their buoyancy and become submerged. Also, in cooling water canals such as condensers of power plants and heat exchangers of various factories, fouling organisms adhere to them, which increases resistance at the time of water intake and causes a decrease in heat exchange efficiency. Various types of damage and loss occur, such as the performance of condensers and heat exchangers being reduced due to the biological mass that has fallen off from the water. Furthermore, when a fouling organism adheres to aquaculture nets for seafood, the durability of the net itself is impaired, or the fouling organism covers the mesh and obstructs the inflow and outflow of seawater, resulting in oxygen deficiency. This may cause respiratory distress and death of cultured seafood, and may promote the growth of bacteria and cause damage to fish due to the occurrence of fish diseases such as Norcadia disease and Verdenia disease.

[0004]

As described above, the attachment of fouling organisms to structures and the like existing in water causes extremely great damage in industry. Therefore, in order to prevent the attachment of fouling organisms, conventionally, as components having antifouling properties (the property of preventing the attachment of organisms), heavy metal compounds such as cuprous oxide and rhodan copper, organic chlorine compounds such as DDT, and tetramethyl. One or more carbamic acid compounds such as thiuram disulfide and dimethyldithiocarbamate, arsenic compounds represented by phenalsazine chloride, organotin compounds represented by tributyltin oxide, organotin polymers and organosulfur compounds. An antifouling paint (paint that prevents fouling organisms from adhering to underwater structures and equipment) is applied to underwater structures and fishing nets, and chlorine, formalin, etc. are directly injected into the cooling water channel. It was.

[0005]

In view of these circumstances, the present inventors have made earnest studies. As a result, it was discovered for the first time that the compound having the structure of formula (I) in the present invention has good antifouling properties against fungi, microalgae, macroalgae, barnacles, etc., and the present invention was completed. did.

That is, the present invention has the formula (I):

[0007]

Embedded image (However, R ₁ and R ₂ each independently represent a hydrogen atom, an acetyl group or a methyl group.) A composition for antifouling paints, comprising the compound represented by the above formula (I). In addition to the compound
95 mol% and caprolactone residue in the resin 5-30
L-lactic acid residue / D-lactic acid residue (molar ratio) in the lactic acid residue is in the range of 1 to 9 and the reduced viscosity (ηSP / C)
Of 0.4 to 1.2 dl / g
The above antifouling coating composition comprising a resin, further comprising a hydrolyzable binder resin, in addition to a lactic acid residue and a caprolactone residue, an oxyacid residue other than lactic acid, a propylene glycol residue, an amber The composition for antifouling paint, comprising at least one selected from an acid residue and a glycerin residue, wherein the hydrolyzable binder resin further has a Tg in the range of -10 ° C to 20 ° C. The present invention relates to a composition for use.

The formula (I) used in the antifouling coating composition of the present invention:

[0009]

Embedded image (However, R ₁ and R ₂ each independently represents a hydrogen atom, an acetyl group or a methyl group.) Has a good antifouling property against fungi, microalgae, macroalgae, barnacles and the like. Not only that, since it is used as a food additive, it is safe for the human body, and specific examples thereof include kojic acid and its derivatives such as diacetylkojic acid and kojic acid dimethyl ether.

The resin constituting the antifouling paint composition of the present invention is not particularly limited, and an acrylic resin, a polyester resin, or the like, which is blended as a main component of a film-forming material of a commonly used paint, is used. However, the hydrolyzable binder resin described below is preferable because it has biodegradability.

The hydrolyzable binder resin contains lactic acid residues in the resin in an amount of 70 to 95 mol%, preferably 70 to 90 mol%, and caprolactone residues in the resin in an amount of 5 to 30 mol%, preferably 5 to 20 mol%. Those contained are preferable. When the content of the lactic acid residue and the caprolactone is within the above range, good coating strength and an appropriate hydrolysis rate can be obtained.

Among the lactic acid residues in the hydrolyzable binder resin, preferred L-lactic acid residue (L) and D-lactic acid residue (D) are preferred.
Has a molar ratio (L / D) of 1 to 9, more preferably 1 to 3. If the L / D is out of the range of 1 to 9, it is difficult to obtain satisfactory solubility in a general-purpose solvent such as toluene or ethyl acetate.

The hydrolyzable binder resin may contain 0 to 5 mol% of at least one selected from oxyacid residues other than lactic acid, propylene glycol residues, succinic acid residues and glycerin residues in the resin. Examples of oxyacids other than lactic acid include glycolic acid, 2-hydroxyisobutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 1
6-hydroxyhexadecanoic acid, 2-hydroxy-2-
Methyl butyric acid, 10-hydroxystearic acid, malic acid, citric acid, glucuronic acid and the like can be mentioned.

Reduced viscosity of the hydrolyzable binder resin (η
SP / C) is preferably 0.4 to 1.2. If the reduced viscosity of the resin is less than 0.4, problems such as too low coating film strength and too fast hydrolysis rate tend to occur. Further, if the reduced viscosity exceeds 1.2, problems tend to occur in coating suitability. The reduced viscosity is preferably 0.5 to 0.8. Here, the reduced viscosity was measured by adding 125 mg / resin to chloroform.
It was dissolved in a concentration of 25 ml and measured at a temperature of 25 ° C. using an Uberode viscosity tube.

When the antifouling paint composition of the present invention is used as an antifouling paint for fishing nets, it is preferable to adjust the glass transition temperature (Tg) of the hydrolyzable binder resin to -10 ° C to 20 ° C. When the Tg is in this temperature range, the composition of the present invention is less likely to be peeled from the fibers constituting the fishing net, and the antifouling property can be maintained for a long period of time. A more preferable Tg range is −5 ° C. to 15 ° C.

Polymerization of the hydrolyzable binder resin is carried out by using a known ring-opening polymerization catalyst for lactide, which is a dimer of lactic acid, caprolactone and other components under a nitrogen atmosphere.
Examples thereof include a method of obtaining by heating and a method of directly dehydrating and polycondensing by heating and reducing the pressure of the above-mentioned raw material compound. Raw materials for the hydrolyzable binder resin are lactic acid, caprolactone, propylene glycol, succinic acid, glycerin and the like. These monomers have been used as medical polymers, have been used as food additives, and are compounds that have no problem in the human body or natural environment.

The compounding amount of the compound (I) is not particularly limited, but is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the resin. More preferably, it is 50 to 100 parts by weight with respect to 100 parts by weight of the resin.

Organic solvents usable in the antifouling coating composition of the present invention include aromatic solvents such as toluene and xylene, ester solvents such as ethyl acetate and butyl acetate, ether solvents such as tetrahydrofuran, isopropyl alcohol,
Examples thereof include alcohol solvents such as butyl alcohol.

The antifouling paint composition of the present invention may further contain additives usually added to paints, such as pigments, viscosity modifiers and leveling agents.

The solid content concentration in the antifouling coating composition of the present invention is appropriately determined depending on the purpose of use, but normally, it is 20 to 30% by weight when used in a fishing net, and when applied to a hull or the like. It is 40 to 60% by weight.

[0021]

EXAMPLES The antifouling coating material of the present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples.

Production Example 1 100 g of L-lactide, 100 g of DL-lactide, 50 g of caprolactone, and 0.1 g of glycolic acid as a polymerization initiator.
4 g, and 50 mg of aluminum acetylacetonate as a ring-opening polymerization catalyst were added to the flask under a nitrogen atmosphere to give 19
Polymerization was carried out by heating at 0 ° C. to obtain polyester A. Table 1 shows the composition, reduced viscosity, and the like.

Production Example 2 200 g of DL-lactide, 50 g of caprolactone, 0.4 g of glycolic acid as a polymerization initiator, and 50 mg of ring-opening polymerization catalyst aluminum acetylacetonate were added to a flask and heated to 190 ° C. under a nitrogen atmosphere to perform ring-opening polymerization. By doing so, polyester B was obtained. Table 1 shows the composition, reduced viscosity, and the like.

Production Example 3 DL-lactide (200 g), caprolactone (30 g), glycolic acid (0.4 g) as a polymerization initiator, and ring-opening polymerization catalyst aluminum acetylacetonate (50 mg) were added to a flask and heated to 190 ° C. under a nitrogen atmosphere to perform ring-opening polymerization. By doing so, polyester C was obtained. Table 1 shows the composition, reduced viscosity, and the like.

Example 1 60 g of Polyester A was dissolved in 140 g of ethyl acetate, and then 40% of kojic acid was used as an antifouling agent of the structural formula (I).
A coating material (I) was obtained by adding g and mixing. The coating composition is shown in Table 2. Evaluation of paint A 20 cm x 10 cm FRP plate was coated with paint (I) at a wet thickness of 300 µm, and after air-drying, it was immersed 2 m below the water surface of a raft fixed off the coast of Iwakuni in the Seto Inland Sea to evaluate biofouling properties. did. The evaluation was carried out by visual evaluation, and was evaluated in five levels. Also, the rate of decrease due to the hydrolysis of the coating film,
The rotor fixed on the raft was rotated in seawater at 15 knots, and one month later, it was measured and evaluated by a surface roughness meter. Biofouling,
Table 3 shows the evaluation results of the coating film reduction rate.

Example 2 60 g of polyester B was dissolved in 140 g of ethyl acetate, and then 30% of kojic acid was used as an antifouling agent of the structural formula (I).
g and 10 g of tannic acid were added and mixed to obtain a paint (II). The coating composition is shown in Table 2. The coating film of the paint (II) was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 3 60 g of Polyester C was dissolved in 140 g of ethyl acetate,
Thereafter, as an antifouling agent of the structural formula (I), 40 g of kojic acid was added and mixed to obtain a paint (III). The coating composition is shown in Table 2. The coating film of paint (III) was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 1 60 g of aromatic copolyester Byron 200 (manufactured by Toyobo Co., Ltd.) was dissolved in 140 g of toluene, and 40 g of tannic acid was mixed to obtain a coating (IV). The coating composition is shown in Table 2. The coating film of paint (IV) was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

[Table 3]

[0032]

The compound of the formula (I), which is a component exhibiting antifouling property of the antifouling coating composition of the present invention, has good antifouling property and has no adverse effect on human body or natural environment. There is no such thing. In particular, by combining it with a hydrolyzable binder resin having biodegradability, a coating film containing the compound (I) exhibiting antifouling properties can always be seen on the surface, and the antifouling properties can be continuously exhibited for a long period of time. In addition, each of the components that the coating film decomposes and dissolves in water is not limited to the compound (I) and lactic acid, caprolactone and the like used in natural products, medical products, foods, etc., and does not adversely affect the human body or the natural environment. .

Claims (4)

[Claims] 1. Formula (I): (However, R ₁ and R ₂ each independently represent a hydrogen atom, an acetyl group or a methyl group.) A composition for antifouling paint, comprising the compound represented by the formula: 2. In addition to the compound (I), a lactic acid residue is further contained in the resin in an amount of 70 to 95 mol% and a caprolactone residue is included in the resin in an amount of 5 to 30 mol%. The hydrolyzable binder resin having a D lactic acid residue (molar ratio) in the range of 1 to 9 and a reduced viscosity (ηsp / c) of 0.4 to 1.2 dl / g. Antifouling paint composition. 3. The hydrolyzable binder resin comprises at least one selected from an oxyacid residue other than lactic acid, a propylene glycol residue, a succinic acid residue and a glycerin residue, in addition to a lactic acid residue and a caprolactone residue. The composition for antifouling paint according to claim 2, comprising. 4. The hydrolyzable binder resin is -10 ° C.
The antifouling coating composition according to claim 2 or 3, which has a Tg in the range of -20 ° C.