JPH1129725A - Paint composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which is lowly toxic, has high, sure and persistent antifouling effect, is used for preventing the deposition of underwater life and prevents the frictional resistance of the substrate to which it is applied from increasing with the lapse of time by selecting a composition which can form on a substrate a coating film which shows a specified change in thickness per month when the coated substrate is moved at a specified speed in salt water having a specified temperature, a specified pH and a specified concentration. SOLUTION: There is provided a coating composition which can give a coating film which shows a change in thickness of the coating film of 10-50 μm/month when the coated substrate is moved at a speed of 20 knots in a 5% salt water at 20 deg.C and a pH of 8. These conditions are simulations of those under which the coating material applied to the bottom of a ship moving out a sea elutes into sea water and wears. If the change in thickness of the coating film is below 10 μm per month, the film can not exhibit ant effect of reducing frictional resistance. Desirably, it is 20-40 μm/ month. It is desirable in order to attain sure antifouling effect that the coating composition contains 0.5-25 wt.% antifouling agent. A desirable example of the binder resin as a constituent of the coating material is a metal ester containing an acrylic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition for use in ships, underwater structures, industrial water-based facilities, and the like, for preventing damage caused by the adhesion and propagation of aquatic organisms.

[0002]

2. Description of the Related Art Underwater structures such as ships, marine structures, aquaculture fishing nets, buoys, and industrial water systems are constantly exposed to seawater inhabited by living organisms. Organisms that adhere to and feed on microorganisms such as barnacles, mussels, aosa,
Animals and plants such as diatoms adhere. As a result, when the surface of an underwater structure is covered, corrosion of the part, a decrease in fuel efficiency of the ship due to an increase in the frictional resistance of the seawater to the ship, a mass death of fish and shellfish due to clogging of fishing nets, and sedimentation due to a decrease in buoyancy of the buoy. ,
Damage such as a decrease in work efficiency occurs.

[0003] In an industrial water system such as cooling water using natural water such as river water or lake water, and in a circulating cooling device using medium or tap water, bacteria, diatoms, cyanobacteria, etc., proliferate and water quality is increased. It causes problems such as deterioration of cooling efficiency, lowering of cooling efficiency due to adhesion to the vessel wall, blockage of water pipes, and reduction of flow rate.

[0004] As a method for preventing the adhesion of these pests, a method of applying an antifouling paint has conventionally been adopted. In the antifouling paint, an inorganic copper compound, an organic tin compound or the like is mainly used as an antifouling agent. I have. The antifouling paint contains rosin as a part of the paint vehicle, and the antifouling agent is added to the rosin to prevent the adhesion of underwater organisms.

A hydrolysis-type antifouling paint containing a trialkyltin polymer as an antifouling component is used. This is because a trialkyltin polymer is hydrolyzed in a slightly alkaline atmosphere of water. In addition, the organic tin compound is eluted, the paint vehicle is made water-soluble, and the compounded antifouling agent is eluted.

[0006] The antifouling agent components eluted in this manner are all highly toxic, and the antifouling performance is exhibited by killing or damaging the harmful aquatic organisms attached by the toxicity. . Conventional antifouling paints contain compounds harmful to living organisms as described above, and have a problem in terms of safety and health for workers. It was also a serious problem from the viewpoint of environmental pollution.

[0007] In recent years, many silicone-based antifouling paints have been proposed, which utilize the water repellency and low surface energy of the coated surface. Such silicone-based antifouling paint has low toxicity to human body and environmental pollution,
There are many problems such as poor adhesion to the base material for coating, insufficient coating film strength, difficulty in repainting and repair coating, and the like, which is used only in some special areas such as nuclear power generation.

[0008]

SUMMARY OF THE INVENTION In view of the above, the present invention has a low toxicity, a large antifouling effect, a more reliable antifouling effect for a long time, and a reduction in frictional resistance over time. It is an object of the present invention to provide a coating composition to be applied.

[0009]

DISCLOSURE OF THE INVENTION The coating composition of the present invention comprises:
Amount of change in thickness of coating film formed by coating on substrate (change in thickness of coating film when substrate is moved at a speed of 20 knots in a 5% saline solution at a temperature of 20 ° C. and a pH of 8) ) Is 10 to 50 μm / month. Hereinafter, the present invention will be described in detail.

[0010] In the present specification, the "film thickness change amount" refers to the case where a substrate is placed in a 5% saline solution at a temperature of 20 ° C. and a pH of 8.
It is the amount of change in the film thickness of the coating when it is moved at the speed of knots. One knot refers to the speed of moving one nautical mile (about 1.852 km) per hour, and is about 0.5144.
4 m / sec. The change in the film thickness can be measured by a test method described below.

As shown in FIG. 1, the thickness is 1 cm and the diameter is 30.
A rotating rod 2 is provided at the center of an acrylic resin disk 1 cm in diameter and connected to a motor 3 to produce a test device in which the disk 1 rotates at a constant peripheral speed. A test coating composition to be tested is applied to the upper surface 11 of the disk 1 to form a coating film having a constant thickness. The film thickness is
100 μm is sufficient.

After the formation of the coating film, the above-described test apparatus was connected to the test apparatus shown in FIG.
Soak in water up to the point shown in. The water is kept at a constant condition in order to keep the condition of the film thickness change constant. Since the coating composition of the present invention is used for the purpose of exhibiting antifouling properties in seawater, the water is preferably a condition simulating natural seawater. In the present invention, a 5% saline solution at a temperature of 20 ° C. and a pH of 8 is used to approximate natural seawater. Such water is made to contain 3% sodium chloride in water having a low content such as ion-exchanged water, and the pH is adjusted with sodium hydroxide. It can be realized by immersing in a constant temperature bath of ° C.

In the test apparatus shown in FIG.
Causes the disk 1 to rotate. The peripheral speed of the rotation is such that the outermost circumference 111 of the upper surface 11 of the disk shown in FIG. 2 is 25 knots. By doing so, it is possible for the coating film at the position of the circle 112 inside the outermost circumference 111 by a certain distance to continue rotating in the water at a speed of 20 knots. The coating film at the position 112 in FIG. 2 is the test coating film in the test device, and the test device measures the thickness of the coating film at the position 112 in FIG. 2 over time. In this way, the amount of change in film thickness is calculated.

The amount of change in film thickness that can be measured by the above-described test apparatus is to gradually decrease the film thickness by dissolving or dissolving the paint applied to the bottom outer wall of a ship operating in the ocean into seawater. It simulates the course.

The film thickness variation defined above is 10 to 50 μm / month in the coating composition of the present invention. The unit of “μm / month” means a value obtained by measuring, in μm, the amount of decrease in the film thickness per month.

The present inventor has conducted intensive studies and found that this value is 1
When it is less than 0 μm / month, it has been found that sufficient antifouling performance cannot be obtained and that the effect of reducing frictional resistance cannot be exhibited, and the present invention has been achieved. That is, the gist of the present invention is that the relationship between the amount of change in the film thickness and the antifouling performance and the frictional resistance reducing effect is within a certain range.

If the thickness change exceeds 10 μm / month, the antifouling property and the effect of reducing the frictional resistance are exhibited, but more preferably 20 μm / month. The upper limit of the change in the film thickness is not particularly limited in order to exhibit the antifouling performance and the frictional resistance reducing effect. However, a coating composition exceeding 50 μm / month has an excessively large initial coating film thickness. It is not practical, and marine pollution due to dissolution and elution is a concern. A more preferred upper limit is 40 μm
/ Month.

The antifouling performance of the coating composition of the present invention can be further improved by including an antifouling agent. The content of the antifouling agent used for such a purpose is, in terms of a solid content ratio of the entire coating composition, 0.5 to
25% by weight is preferred. If the amount is less than 0.5% by weight, the antifouling effect of the antifouling agent cannot be exhibited, and if it exceeds 25% by weight, the adhesion and leveling properties of the coating composition will be adversely affected.

The antifouling agent is not particularly restricted but includes, for example, manganese ethylenebisdithiocarbamate (maneb, manufactured by Tokyo Organic Chemical Industry Co., Ltd.), zinc dimethyldithiocarbamate (Chemical Products Industry Association, Ziram), 2-methylthio- 4-t-butylamino-6-cyclopropylamino-S-triazine (Ciba Geigy, Irgalol 1051), 2,4,5,6-tetrachloroisophthalonitrile (San Nopco, Marine Side), N, N
-Dimethyldichlorophenylurea (Hodogaya Chemical Industry Co., Ltd.), zinc ethylenebisdithiocarbamate (Tokyo Organic Chemical Industry Co., Ltd., Zineb), rodan copper, 4,5-dichloro-2-n-octyl-3 (2H) -isothiazoline (Seanine, manufactured by Rohm and Haas Japan
211), N- (fluorodichloromethylthio) phthalimide (manufactured by Bayer Japan, Preventol A-
3), N, N'-dimethyl-N'-phenyl- (N-fluorodichloromethylthio) sulfamide (manufactured by Bayer Japan, Priventol A4S), 2-pyridinethiol-1-oxide zinc salt (zinc pyrithione),
2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine (DensilS100), 3-iodo-
2-propynyl butyl carbamate (TROYSAN
POLYPHASE P100), diiodomethyl paratolyl sulfone (AMICAL 48), bisdimethyldithiocarbamoyl zinc ethylenebisdithiocarbamate (TOC-3204), pyridine-triphenylborane (PK) and the like.

When the coating composition of the present invention is used as a coating, it is prepared by blending it in the coating in the range of 0.5 to 80% by weight. The mixing ratio can be determined according to the antifouling performance required within the above range. The above-mentioned paint can be blended with a paint resin which is generally used for the purpose of enhancing the strength of the coating film and the adhesion to the undercoat, if necessary.For example, as an organic solvent, a vinyl chloride resin , Chlorinated rubber resin, chlorinated polyethylene resin, chlorinated polypropylene resin, acrylic resin, styrene-butadiene resin, polyester resin, epoxy resin, polyamide resin, petroleum resin, silicone resin, silicone rubber resin, wax, paraffin, Rosin esters, rosin-based resins, and resins containing a metal element such as tin, copper, zinc, and tellurium in the side chain, and the like.Aqueous systems include acrylic emulsion resins, epoxy emulsion resins, and vinyl acetate resins. Can be mentioned. These can be used alone or in combination of two or more.

The coating composition of the present invention may further include a coloring pigment generally used in the coating composition, depending on the use such as a clear coating which is a transparent top coating, a base coating which is a coloring coating, and the like. An extender pigment or the like can be blended.

The coloring pigment is not particularly limited, and examples thereof include titanium oxide, carbon black, red iron oxide, phthalocyanine blue, phthalocyanine green, and quinacridone. The extender is not particularly limited, and examples thereof include zinc white, talc, clay, precipitated barium sulfate, and calcium carbonate.

The binder resin constituting the coating composition of the present invention is not particularly limited as long as the change in film thickness of the coating composition is from 10 to 50 μm / month. Examples of the binder resin exhibiting the thickness change amount include a hydrolysis type resin, and more preferably, a metal ester-containing acrylic resin.

The above-mentioned metal ester-containing acrylic resin is
It is an acrylic resin having at least one group having a chemical structure represented by the following general formula (1) at the terminal of at least one side chain.

[0025]

Embedded image

In the formula, M represents zinc or copper. R ¹ is
Represents an aliphatic monobasic acid residue. More specifically, R ¹ includes acid residues of saturated or unsaturated fatty acids such as levulinic acid, naphthenic acid and oleic acid.

The acrylic resin constituting the metal ester-containing acrylic resin is not particularly limited, and includes any resin having a main chain formed by an acrylic bond. These include, for example, resins made of (co) polymers of alkyl (meth) acrylates and copolymers of alkyl (meth) acrylates with other polymerizable monomers copolymerizable therewith. be able to. In the above copolymerization,
An ordinary radical polymerization initiator or an appropriate solvent can be used if necessary.

When the coating composition of the present invention is used as a coating, it is prepared by blending it in the coating in the range of 0.5 to 80% by weight. The mixing ratio can be determined according to the antifouling performance required within the above range. The above-mentioned paint can be blended with a paint resin which is generally used for the purpose of enhancing the strength of the coating film and the adhesion to the undercoat, if necessary.For example, as an organic solvent, a vinyl chloride resin , Chlorinated rubber resin, chlorinated polyethylene resin, chlorinated polypropylene resin, acrylic resin, styrene-butadiene resin, polyester resin, epoxy resin, polyamide resin, petroleum resin, silicone resin, silicone rubber resin, wax, paraffin, Rosin esters, rosin-based resins, and resins containing a metal element such as tin, copper, zinc, and tellurium in the side chain, and the like.Aqueous systems include acrylic emulsion resins, epoxy emulsion resins, and vinyl acetate resins. Can be mentioned. These can be used alone or in combination of two or more.

The coating composition may further contain known additives such as a plasticizer. Examples of the additive include a plasticizer such as dioctyl phthalate; a run-off agent such as organic bentonite and colloidal silica;

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Production Example 1 To a four-necked flask equipped with a stirrer, a reflux condenser and a dropping funnel, 120 parts by weight of xylol and 30 parts by weight of n-butanol were added and kept at 110 to 120 ° C. Into this solution, a mixed solution of 60 parts by weight of ethyl acrylate, 25 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of acrylic acid, and 2 parts by weight of azobisisobutyronitrile was dropped at a constant speed over 3 hours. It was kept warm for 2 hours. The solid content of the obtained varnish was 39.8%, and the viscosity was 2.2 poise (hereinafter referred to as "varnish XI").

100 g of the varnish XI obtained above was placed in a four-necked flask equipped with a stirrer, a reflux condenser and a decanter.
Parts by weight, naphthenic acid (acid value 200 KOHmg / g) 20
Parts by weight, 7 parts by weight of copper hydroxide, and heated to 120 ° C.
It was kept warm for 2 hours. Water generated during this time was removed (2.5 g of dewatered amount). The obtained varnish was used as a varnish A in a subsequent experiment.

Production Example 2 100 parts by weight of varnish XI and zinc stearate 2 were placed in a four-necked flask equipped with a stirrer, a reflux condenser and a decanter.
3 parts by weight were added, and the mixture was stirred at 120 ° C. for 2 hours. Thereafter, 35 parts by weight of xylol was added to obtain Varnish B having a solid content of 39.2% and a viscosity of 1.3 poise. Production Example 3 To a four-necked flask equipped with a stirrer, a reflux condenser, and a dropping funnel, 64 parts by weight of xylol and 16 parts by weight of n-butanol were added and kept at 100 ° C. In this solution, 20.0 parts by weight of isobornyl acrylate and 5 parts of ethyl acrylate were added.
A mixture of 0.9 parts by weight, 14.1 parts by weight of acrylic acid, 15.0 parts by weight of NK ester M-90G, and 3 parts by weight of t-butylperoxy-2-ethylhexanoate was dropped at a constant rate over 4 hours. After completion of the dropping, the temperature was kept for 2 hours. A varnish XII having a solid content of 50.0% and a viscosity of 7.5 poise in the obtained resin solution was obtained. In a four-necked flask equipped with a stirrer, a reflux condenser, and a decanter, 100 parts by weight of the varnish XII obtained above, 15.7 parts by weight of copper oxalate, 27.7 parts by weight of oleic acid, and 120 parts by weight of xylol were placed. In addition, the mixture was heated to 120 ° C. to remove oxalic acid together with the solvent to obtain Varnish C having a solid content of 50.8% and a viscosity of 6.5 poise.

Examples 1 to 7, Comparative Examples 1 and 2 Varnish A, varnish B and varnish C were blended with other components, and the respective coating compositions shown in Table 1 were prepared by high-speed disperser. In addition, in addition to the components described in Table 1, xylene was added to each coating composition in an amount for adjusting the viscosity. The unit of the components in Table 1 is% by weight.

[0035]

[Table 1]

Water resistance test Using the coating compositions obtained in Examples 1 to 7 and Comparative Examples 1 and 2, the inner surface of an iron thin tube having a diameter of 2 cm and a length of 100 cm was dried by an immersion method to give a dry film thickness. The coating was performed so as to be 100 μm. The above thin tube was fixed vertically, a specially prepared dropping funnel was attached to the upper portion of the thin tube, 2000 ml of seawater was allowed to flow from the upper portion of the funnel, and the time required for all the amount of seawater to flow down was measured.

In the “control”, methyl methacrylate / n
-Butyl methacrylate = 60/70 (molar ratio) copolymer (weight average molecular weight = 30000, number average molecular weight = 12
000) was applied in the same manner as in Examples 1 to 7. In the "red rust", an iron thin tube with red rust raised on the entire surface was used as it was. Assuming that the time required for the “control” was “0”, the time taken longer was represented by “+” and the time taken shorter was represented by “−”. The results are shown in Table 2 below.

[0038]

[Table 2]

It is clear that the coating compositions of Examples 1 to 7 reduce the frictional resistance with seawater, and the coating compositions of Comparative Examples 1 and 2 do not reduce the frictional resistance with seawater. Antifouling test Commercially available 300 x 100 x 1.6 m with anticorrosion coating
m was coated with the coating compositions of Examples 1 to 7 and Comparative Examples 1 and 2 so that the dry film thickness became 200 to 300 μm, and dried at room temperature for 7 days. It was immersed in a test raft off the coast of Tamano City, Okayama Prefecture, at a depth of 1 m in the sea, and the degree of contamination by attached organisms was examined. The results are shown in Table 3. The numerical values in Table 3 represent the ratio (%) of the soiled area due to the attached organisms. In Table 3, "-
"-" Means that the coating film flowed out and could not be measured.

[0040]

[Table 3]

Although the coating compositions of Examples 1 to 7 have an antifouling effect, it is clear that the coating compositions of Comparative Examples do not have the antifouling effect or cannot be maintained as a coating film for a long time.

[0042] Using the test device shown in thickness variation Figure 1, Examples 1 to 7 and Comparative Example 1
Each of the coating compositions No. to No. 2 was tested. The difference between the thickness before the test and the thickness after the immersion while rotating the motor for one month is compared with the thickness before the test (μm / month).
showed that. The results are shown in Table 4. In Table 4, “−−” means
It means that all of the applied film thickness of 100 μm was dissolved or eluted and the remaining film thickness was 0.

[0043]

[Table 4]

As described above, the variation in film thickness is 10 to
When the thickness is 50 μm / month, the antifouling performance is good and the effect of reducing water resistance is good, but the change in film thickness is 1%.
Those which did not fall within the range of 0 to 50 μm / month were found to have poor antifouling performance and water resistance reducing effect.

[0045]

Since the coating composition of the present invention has the above-mentioned constitution, it is useful as a coating composition having a high antifouling effect by reducing frictional resistance and preventing underwater organisms from adhering to organisms.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a test apparatus for measuring a film thickness change amount.

FIG. 2 is a top view of a disk constituting a test apparatus for measuring a change in film thickness.

[Explanation of symbols]

 1 disk 2 rotating rod 3 motor

Continuing on the front page (72) Inventor Tomokazu Arai 19-17 Ikedanakamachi, Neyagawa-shi Nippon Paint Marine Co., Ltd.

Claims (3)

[Claims] 1. A film thickness change amount of a coating film formed by applying the coating film on a substrate (in a 5% saline solution at a temperature of 20 ° C. and a pH of 8 when the substrate is moved at a speed of 20 knots). Coating composition, wherein the amount of change in film thickness is 10 to 50 μm / month. 2. The coating composition according to claim 1, wherein the amount of change in film thickness is 20 to 40 μm / month. 3. The coating composition according to claim 1, comprising 0.5 to 25% by weight (solid content ratio) of an antifouling agent.