JPH08100137A - Composition for antifouling coating - Google Patents

Abstract

PURPOSE: To obtain the subject composition, containing tannic acid and a resin having the biodegradability, excellent in antifouling properties, capable of sustaining effects for a long period without adversely affecting the natural environment and useful for preventing ships, fishing nets, etc., from staining with microorganisms, etc., attaching thereto. CONSTITUTION: This composition contains (A) a hydrolyzable type binder resin, containing 70-95mol% lactic acid residues and 5-30mol% caprolactone residues in the resin, having 1-9 molar ratio of the L-lactic acid residues/D-lactic acid residues and 0.5-1.5dl/g reduced viscosity (ηsp /c) and preferably containing 0-5mol% one or more residues selected from hydroxy acids other than the lactic acid, propylene glycol, succinic acid and glycerol and (B) tannic acid as essential components. The component (A) preferably has -10 to +15 deg.C Tg . The solid concentration in the composition is preferably 20-30wt.% when used for fishing nets and 40-60wt.% when used for coating hulls, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a composition for antifouling paint. In particular, for the prevention of contamination by 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 good 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 are 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. It causes dyspnea and death of cultured seafood, and promotes the growth of bacteria and causes damage to fish due to the occurrence of fish diseases such as norcadia disease and bendenia disease.

As described above, the attachment of fouling organisms to structures and the like existing in water causes a great deal of industrial damage. Therefore, in order to prevent attachment of fouling organisms, heavy metal compounds such as cuprous oxide and rhodan copper, DDT, etc. have been conventionally used as components having antifouling properties (the property of preventing the attachment of organisms).
Organochlorine compounds such as, tetramethylthiuram disulfide, carbamic acid compounds such as zinc dimethyldithiocarbamate, arsenic compounds represented by phenalsazine chloride, organotin compounds represented by tributyltin oxide,
Applying anti-fouling paints (paints that prevent fouling organisms from adhering to underwater structures and equipment) that contains one or more organic tin polymers and organic sulfur compounds on underwater structures and fishing nets Also, chlorine, formalin, etc. were directly applied to the cooling water channel.

[0005]

However, the above-mentioned heavy metal compounds, organotin compounds, organochlorine compounds and carbamic acid compounds are persistent compounds having considerably high toxicity and accumulation, and Since the antifouling paint containing is also difficult to decompose, it is hard to say that it is preferable for the underwater environment including the ocean. Therefore, there has been a demand for an antifouling paint that maintains excellent antifouling properties for a long time and does not adversely affect the underwater environment in which it is used.

[0006]

In view of these circumstances, as a result of intensive investigations by the present inventors, an antifouling coating material containing tannic acid and a biodegradable resin achieves the above object. The present invention has been completed and the present invention has been completed.

That is, according to the present invention, the lactic acid residue in the resin is 60
~ 95 mol% and caprolactone residue in the resin 5 to 3
0 mol% and optionally at least one selected from oxyacid residues other than lactic acid, propylene glycol residues, succinic acid residues and glycerin residues, and L lactic acid residue / D in the lactic acid residue Lactic acid residue (molar ratio) is 1
To 9 and the reduced viscosity (η _{SP / C} ) is 0.5 to 1.
The present invention relates to an antifouling coating composition containing a hydrolyzable binder resin of 5 dl / g and tannic acid as essential components. Further, the present invention relates to a composition for antifouling paint, which comprises the above-mentioned hydrolyzable binder resin having Tg in the range of -10 to 20 ° C and tannic acid.

Tannic acid, which is an essential component of the antifouling coating composition of the present invention, has good antifouling properties against fungi, microalgae, macroalgae, barnacles and the like. Moreover, since the compound is a natural product and is also used as a medicine, it is a compound safe to the natural environment.

The antifouling coating composition of the present invention contains a hydrolyzable binder resin as an essential component in addition to the tannic acid. The hydrolyzable binder resin contains 70 to 95 mol% of lactic acid residues in the resin, preferably 70 to 90 mol%, and 5 to 30 mol% of caprolactone residues in the resin, preferably 5 to 20 mol%. . When the contents of the lactic acid residue and the caprolactone are within the above ranges, good coating strength and an appropriate hydrolysis rate can be obtained.

In the lactic acid residue in the hydrolyzable binder resin, the molar ratio (L / D) of L lactic acid residue (L) and D lactic acid residue (D) is 1 to 9, preferably 1 to 3. . L / D
If it is not in the range of 1 to 9, solubility in a solvent cannot be obtained.

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. Oxyacids other than lactic acid include glycolic acid, 2-hydroxyisobutyric acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 16-
Examples thereof include hydroxyhexadecanoic acid, 2-hydroxy-2-methylbutyric acid, 10-hydroxystearic acid, malic acid, citric acid and gluconic acid.

The reduced viscosity of the hydrolyzable binder resin (η
_{SP / C} ) should be between 0.5 and 1.5. When the reduced viscosity of the resin is less than 0.5, problems such as too low strength of the coating film and too fast hydrolysis rate occur. On the other hand, if the reduced viscosity exceeds 1.5, there is a problem in coating suitability. The preferred reduced viscosity is 0.5 to 1.2. Here, the reduced viscosity is measured by adding 125 m of resin to chloroform.
It was dissolved in a concentration of g / 25 ml and measured at a temperature of 25 ° C. using an Ubbelohde viscous 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 15 ° 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 fishnet, and the antifouling property can be maintained for a long period of time. More desirable T
The range of g is −5 ° C. to 10 ° C.

Polymerization of the hydrolyzable binder resin is carried out by using a known ring-opening polymerization catalyst for lactide, caprolactone and other components which are dimers of lactic acid, in 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. The raw materials of 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 blending amount of tannic acid is preferably 10 to 10 relative to 100 parts by weight of the hydrolytic binder resin.
The amount is 0 parts by weight, more preferably 20 to 80 parts by weight.

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 fish net, and when applied to a hull or the like. It is 40 to 60% by weight.

Since the composition for antifouling paint of the present invention comprises a hydrolyzable binder resin having biodegradability and tannic acid, it has a persistent antifouling property and has no adverse effect on the human body or natural environment. A coating film that does not extend can be provided. That is, a coating film formed from a coating material containing a resin having no biodegradability has a component exhibiting antifouling property on its surface immediately after coating, but the component decreases with time. However, since the coating film itself is not decomposed, the coating film which has passed the time can no longer exhibit the antifouling property. On the other hand, the hydrolyzable binder resin having biodegradability used in the present invention, because the resin forming the surface of the coating film is gradually decomposed, tannic acid that constantly exhibits antifouling properties is used. The contained coating film appears on the surface and can continue to exhibit antifouling property for a long period of time. Moreover, the components that dissolve the coating film and dissolve in water are all those that do not adversely affect the environment, such as tannic acid, lactic acid, and caprolactone.

[0020]

EXAMPLES The composition for antifouling paint 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 Examples 1 to 3 Polymerization of Hydrolyzable Binder Resin 100 g of L-lactide, 100 g of DL-lactide, 30 g of caprolactone and 50 mg of aluminum acetylacetonate as a ring-opening polymerization catalyst were added to a flask and heated to 190 ° C. under a nitrogen atmosphere. Polymerization was performed by heating to obtain polyester A. The resin composition and reduced viscosity are shown in Table 1. Polyesters B and C having the compositions shown in Table 1 were obtained in the same manner.

[0022]

[Table 1]

Example 1 60 g of polyester A was dissolved in 140 g of ethyl acetate,
Thereafter, 40 g of tannic acid was added and mixed to obtain a paint (I). The coating composition is shown in Table 2. Evaluation of coating film: A 15 cm × 7 cm acrylic plate was coated with the coating material (I) at a wet thickness of 300 μm, air-dried, and then immersed in 2 m below the surface of water in Yaizu Bay, Shizuoka Prefecture to evaluate the bioadhesiveness. The evaluation was a visual evaluation and a five-level evaluation. The results are shown in Table 3.

Example 2 60 g of polyester B was dissolved in 140 g of ethyl acetate,
Thereafter, 30 g of tannic acid and 10 g of benzyl mustard oil were mixed to obtain a paint (II). The coating composition is shown in Table 2.
The coating film of 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, 30 g of tannic acid and 10 g of benzyl mustard oil were 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 "Byron RV200" which is an aromatic polyester
60 g (manufactured by Toyobo Co., Ltd.) is dissolved in 140 g of ethyl acetate, and 40 g of tannic acid is mixed with this to prepare a paint (I
V) was obtained. 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.

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

EFFECTS OF THE INVENTION A coating film formed from the composition for antifouling paint of the present invention is a film containing tannic acid which constantly exhibits antifouling property because the resin forming the surface thereof is gradually decomposed. Each component that appears on the surface and can continue to exhibit antifouling properties for a long time, and the coating film decomposes and dissolves in water is used for natural substances such as tannic acid, lactic acid, caprolactone, medical products, foods, etc. , Those that do not have a negative effect on the human body and the natural environment. Further, since the obtained coating film is gradually hydrolyzed as described above, there is also an advantage that the work of removing the old coating film can be easily performed when the paint is repainted.

Claims (4)

[Claims] 1. A resin containing lactic acid residues in an amount of 70 to 95 mol% and a caprolactone residue in an amount of 5 to 30 mol%, and the L lactic acid residue / D lactic acid residue (molar ratio) in the lactic acid residue is 1 ~ 9
And the reduced viscosity (η _{SP / C} ) is 0.5 to 1.5 d.
A composition for an antifouling paint, which comprises a hydrolyzable binder resin of 1 / g and tannic acid as essential components. 2. The hydrolyzable binder resin further contains 0 to 5 mol% of at least one selected from an oxy acid residue other than lactic acid, a propylene glycol residue, a succinic acid residue and a glycerin residue in the resin. The composition for antifouling paint according to 1. 3. The Tg of the hydrolyzable binder resin is -1.
The antifouling coating composition according to claim 1, which is in the range of 0 to 15 ° C. 4. The composition for antifouling paint according to claim 1, which is applied to a fish net.