JPH10151413A - Coating method of heavy corrosion-proof coating composition and product coated by method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable heavy corrosion-proof coating by low pressure slow speed spray coating of small-sized atomized particles by the electrostatic coating of a low viscosity coating composition consisting of polyol, polythiol, and polyisocyanate in the presence of a vaporized amine catalyst. SOLUTION: A low viscosity coating composition consisting of polyester polyol which is derived from a polyglycol compound of the number of carbon atoms not exceeding 10 such as multivalent hydroxyl compounds, phthalic anhydride, sebacid acid, fatty acid, epoxy resins, etc., polythiol which is a compound having two or more mercapto groups such as thriethylene glycol dimercaptan, dithiocatechol, and polyisocyanate such as hexamethylene diisocyanate, xylylene diisocyanate is used in electostatic coating in the presence of a vaporized amine catalyst. In this way, heavy corrosion-proof coating by low pressure slow speed spray coating of small-sized atomized particles is made possible, improving deposition efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a heavy duty anticorrosion coating composition and a coated product coated by this method so that a coated product having a uniform film thickness can be obtained.

[0002]

BACKGROUND OF THE INVENTION Large steel structures, such as ships, land structures, bridges, etc., are usually subjected to heavy corrosion protection or cathodic protection to prevent corrosion.

[0003] In heavy-duty anti-corrosion coating, a coating film having a thickness of several hundred to several thousand microns is formed on the surface of the steel sheet to shield the steel sheet surface and prevent the penetration of oxygen, chlorine, water vapor, etc. to prevent corrosion of the steel sheet. I do. Conventionally, such a heavy-duty anticorrosion coating uses a tar epoxy coating, a tar urethane coating, a modified epoxy coating, an epoxy coating, or the like.

[0004] Among these paints, tar paints have been pointed out as carcinogenic, and if scattered outside during painting, there is a risk of environmental pollution. In addition, since these paints are usually black, they are aesthetically pleasing. Is not always satisfied.

By the way, when these paints are used for heavy duty anticorrosion coating, the thixotropic properties are appropriately selected by appropriately selecting pigment particles, vehicles and the like so that a thick coating film of several hundred microns or more can be obtained by one coating. (When it is stirred under high shear, it becomes a sol and fluidity and coating properties increase, and after it adheres to an object to be coated, it loses fluidity and becomes a gel, which is capable of forming a thick coating film) However, heavy duty protective coatings with such properties
In the case of atings), the paint viscosity inevitably increases, usually above 2500 cPs.

When such a high-viscosity paint is applied to a thick wall, for example, high-pressure airless (spray) painting is employed, and the paint discharge pressure at this time is 180 kg / c.
also reached m ^2.

In the high-pressure airless (spray) coating performed under such conditions, since the viscosity of the coating is set high as described above, the particle size of the coating when atomized is about 100 microns or more. The particle size of the sprayed paint belongs to a large category.

When high-pressure airless coating, in which such a large-diameter atomized paint is sprayed at a high speed, is applied to an object to be coated such as a hull, an underwater / waterborne structure, or the like, an edge of a steel plate end, a protruding portion, a hole, or the like. And in narrow areas, the glue is bad and easily rusts. Moreover, the edges of the steel plate, the edges such as the holes, and the narrow portions are
If the stress is easily concentrated and the coating is peeled off, the steel plate will be depleted due to rust, which is a serious problem in the structure of the hull and the like.
However, if high-pressure air spray coating is performed and brush-up touch-up (correction coating) is also performed manually, there is a problem in work efficiency.

For this reason, the present inventors have conducted intensive studies to solve the above-mentioned problems, and if a heavy anti-corrosion coating of an object to be coated is performed by electrostatic coating, the edge of the object to be coated is evenly thickened. Based on the idea that a coating film could be formed on the surface, an attempt was made to apply electrostatic coating for heavy corrosion protection using the above-mentioned tar epoxy paint.

That is, using the existing heavy anticorrosion paint,
Moreover, when the coating viscosity is set high to secure a film thickness of several hundred microns or more by one coating, the coating particles become large in particle size, and such coating particles require spray coating at high pressure and high speed. In addition, since the speed of the coating particles was high, even if the coating particles were charged by the electrostatic coating device, the effect of electrostatic attraction with the object to be coated (eg, uniformity of the end face film thickness) was hardly obtained.

[0011] Therefore, when a variety of paints having high application efficiency even under spray conditions of low pressure and high atomization rate and capable of using electrostatic spray were searched for, a polythiol-isocyanate-based or polyol-based paint was found. A coating composition containing an isocyanate-based urethane resin can be made to have a low viscosity (eg, 1000 cPs or less). If it is applied in the presence of a vaporous amine-based catalyst, it can be sprayed at a low pressure at a low speed and with a small atomized particle size. It was found that heavy anticorrosion coating by coating is possible, that coating efficiency can be improved by electrostatic coating, and that safety to workers and the environment is high, and the present invention was completed. .

[0012]

An object of the present invention is to provide a heavy-duty anti-corrosion coating film having a uniform thickness easily and excellently in anti-corrosion properties even on ships, on-water / under-water structures, especially on edges of steel plates, edges such as holes, and narrow portions. It is an object of the present invention to provide a method for coating a heavy-duty anticorrosive coating composition that can reduce the number of work steps by employing an automatic coating system such as robot coating.

[0013]

SUMMARY OF THE INVENTION A method for coating a heavy duty anticorrosion coating composition according to the present invention comprises a method for coating a polyol (a) in the presence of a vaporous amine catalyst.
It is characterized in that a low-viscosity coating composition comprising 1) and / or a polythiol (a2) and a polyisocyanate (b) is electrostatically coated, and has excellent uniformity in film thickness.

In the present invention, the viscosity of the low-viscosity coating composition is preferably 500 cPs or less. The painted product for heavy corrosion protection according to the present invention (painted product) is characterized in that a coating film is formed on the surface of various molded products such as hulls, underwater / water structures, and shore structures by the above-described coating method. And

According to the present invention, a heavy-duty anti-corrosion coating film having a uniform thickness and excellent anti-corrosion properties can be easily obtained especially at the edges of steel plates, edges such as holes, and narrow portions. The use of the system provides a method for coating a heavy duty anticorrosion coating composition that can reduce the number of work steps.

[0016]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the method for applying the heavy duty anticorrosion coating composition according to the present invention will be described in detail.

In the present invention, a low-viscosity coating composition comprising a polyol (a1) and / or a polythiol (a2) and a polyisocyanate (b) is electrostatically coated in the presence of a vaporous amine catalyst, By such a method, a heavy-duty anticorrosion coating film having excellent uniformity of film thickness can be obtained.

The low-viscosity coating composition used in the present invention comprises:
A substantially non-solvent type paint, comprising a polyol (a1)
And / or polythiol (a2) and polyisocyanate (b) as a crosslinking agent.

[0019] As the polyol (a1) used in the polyol (a1) The present invention, specifically, ethylene glycol, diethylene glycol,
Triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, dibutylene glycol, tributylene glycol, polybutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6 -Hexanediol, 1,10-decanediol, alkanediol, dihydric alcohols such as cyclohexanedimethanol; glycerol, trimethylolpropane (TMP), 1,2,6-hexanetriol, trimethylolethane, 2,4-dihydroxy Trihydric alcohols such as -3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane and 2,2-bis (hydroxymethyl) butanol-3; 4 such as pentaerythritol and diglycerol Dihydric alcohols; pentahydric alcohols (pentit) such as arabbit, ribitol, xylitol; hexahydric alcohols (hexit) such as sorbitol, mannitol, galactitol, allodulcit; polyhydric hydroxy compounds such as polyglycerol and polytetramethylene glycol Polyglycol compounds having up to about 10 carbon atoms, and polyester polyols, polyether polyols or acrylic polyols derived from phthalic anhydride, sebacic acid, fatty acids, epoxy resins, and the like, polyester polyols, acrylic polyols, and the like can be given.

Among them, glycerol, trimethylolpropane, pentaerythritol, polyester polyol and acrylic polyol are preferred. Polythiol (a2) The polythiol (a2) used in the present invention is a compound having two or more mercapto groups (-SH groups). Specific examples of the polythiol (a2) include 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, 2,3-dimethylcaptopropanol, and toluene-
3,4-dithiol, α, α'-dimethylcapto-p-xylol, dimercaptoethane, diethylene glycol dimercaptan, triethylene glycol dimercaptan,
Dithiocatechol, 3-chlorothiocatechol, dithioresorcin, dimercaptotoluene, xylylenedimercaptan, 1,3,5-trimercaptobenzene, dimercaptonaphthalene, didodecanedithiol, dithiolphenol, 4,4'-dithiophenol, 2 , 2'-Dimethyl-4,4'-
Thiodiphenol, dimercaptobenzothiazole, dithioerythritol and the like.

Specific examples of the polythiol (a2) other than the above include a complete ester or a partial ester composed of an aliphatic polyol and a mercapto lower fatty acid. As the aliphatic polyol, specifically, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, dibutylene glycol, tributylene glycol,
Dihydric alcohols such as polybutylene glycol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,10-decanediol, alkanediol and cyclohexanedimethanol; glycerol, trimethylolpropane (TMP), 1,2,6-hexanetriol, trimethylolethane, 2,4-dihydroxy-3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane, 2,2-bis (hydroxymethyl) butanol- Trihydric alcohol such as 3; pentaerythritol,
Tetrahydric alcohols such as diglycerol; pentahydric alcohols (pentit) such as arabbit, ribitol and xylitol; and hexahydric alcohols (hexit) such as sorbitol, mannitol, galactitol, allozurcit, and the like. Among them, glycerol, trimethylolpropane, and pentaerythritol are preferred.

Glycidyl ethers such as bisphenol A glycidyl ether, hydrogenated bisphenol A glycidyl ether, bisphenol F glycidyl ether, and novolak epoxy can also be used.

Examples of the above mercapto lower fatty acids include mercaptoacetic acid, mercaptopropionic acid, mercaptosalicylic acid, mercaptoglycolic acid, N- (2-hydroxyethyl) thioglycolic acid, mercaptosuccinic acid, and mercaptomalic acid. And the like. Among them, mercaptoacetic acid (HSCH ₂ COOH),
Mercaptopropionic acid is preferred.

The polythiol (a2) particularly preferably used in the present invention is an ester having 2 to 4 mercapto groups consisting of pentaerythritol and mercaptoacetic acid or mercaptopropionic acid, or trimethylolpropane and mercaptoacetic acid or mercaptopropionic acid. It is.

The thiol compound having one mercapto group can be used as a diluent or a plasticizer. In the present invention, it is desirable to use a polythiol (a2) which does not require a solvent and has no or little odor.

Polyisocyanate (b) As the polyisocyanate (b) used in the present invention, specifically, hexamethylene diisocyanate (H
DI), xylylene diisocyanate (XDI), 1,3-
Bis (isocyanatomethyl) cyclohexane (hydrogenated X
DI, H6XDI), tolylene diisocyanate (TD)
I), diphenylmethane diisocyanate (MDI),
4,4-bis (isocyanatocyclohexyl) methane (hydrogenated MDI), naphthylene diisocyanate (NDI),
Isophorone diisocyanate (IPDI), meta-xylylene diisocyanate (MXDI), lysine diisocyanate (2,6-diisocyanatomethyl caproate)
(LDI), methylcyclohexane-2,4 (or2,6) -diisocyanate (hydrogenated TDIor (HTDI)), trimethylhexamethylene diisocyanate (TMDI), dimer acid diisocyanate (DDI), tolidine diisocyanate (TODI), p-phenylene Diisocyanate, transcyclohexane-1,4-diisocyanate,
Tetramethylxylene diisocyanate (TMXDI)
Diisocyanates; triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1,6,
Examples include triisocyanates such as 11-undecane triisocyanate, 1,8-diisocyanate-4-isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, and bicycloheptane triisocyanate.

A nurate derivative or an adduct derived from the isocyanate described above can also be used. In addition, polyisocyanate (b) other than the above
Specific examples include the following carbodiimide-type polyisocyanates. This carbodiimide-type polyisocyanate has at least one -N = C = N- group. Specifically, carbodiimide-type diphenylmethane diisocyanate, carbodiimide-type toluene diisocyanate, carbodiimide-type dimethylbiphenylene diisocyanate, carbodiimide-type xylylene diisocyanate, carbodiimide Naphthalene diisocyanate, carbodiimide hexamethylene diisocyanate, carbodiimide isophorone diisocyanate, carbodiimide hydrogenated xylylene diisocyanate, carbodiimide hydrogenated diphenylmethane diisocyanate, and the like.

The polyisocyanate (b) preferably used in the present invention is carbodiimide-type diphenylmethane diisocyanate, carbodiimide-type toluene diisocyanate, carbodiimide-type dimethylbiphenylene diisocyanate, and carbodiimide-type hexamethylene diisocyanate. Particularly, carbodiimide-type diphenylmethane diisocyanate is preferably used.

The carbodiimide type polyisocyanate having one -N = C = N- group can be represented by the following formula. ^{(OCN-R 1) -N =} C = N- (R 2 -NCO) [ in the formula ^{(OCN-R 1), (} R 2 -NCO) is a polyisocyanate. Further, specific examples of the polyisocyanate (b) other than the above polyisocyanate include:
(1) Trihydric or higher aliphatic polyhydric alcohol (i), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), meta-xylylene diisocyanate (M
XDI), hexamethylene diisocyanate (HDIor
HMDI), isophorone diisocyanate (IPD)
I) or an adduct with bis (isocyanatomethyl) cyclohexane (ii), and (2) hexamethylene diisocyanate (HDI or HMDI), isophorone diisocyanate (IPDI), or bis (isocyanatomethyl) cyclohexane, An isocyanurate structure having a ring represented by the formula [I] (nurate structure) can be given.

[0030]

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Specific examples of the trihydric or higher aliphatic polyhydric alcohol (i) used as a component of the adduct (adduct) include glycerol, trimethylolpropane (TMP), 1,2,6- Trihydric alcohols such as hexanetriol, trimethylolethane, 2,4-dihydroxy-3-hydroxymethylpentane, 1,1,1-tris (bishydroxymethyl) propane, and 2,2-bis (hydroxymethyl) butanol-3 Tetrahydric alcohols such as pentaerythritol and diglycerol; pentahydric alcohols such as arabbit, ribitol and xylitol (pentite); and hexahydric alcohols such as sorbitol, mannitol, galactitol and allozurcit (hexit). Among them, trimethylolpropane and pentaerythritol are particularly preferred.

Further, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), metaxylylene diisocyanate (MXDI), hexamethylene diisocyanate (HDI or HMDI), isophorone diisocyanate (IPDI), bis ( Among (isocyanatomethyl) cyclohexane (hydrogenated XDI, H6XDI) (ii), 1,3-bis (isocyanatomethyl) cyclohexane, tolylene diisocyanate (TDI) and xylylene diisocyanate (XDI) are preferable.

The adduct (1) used in the present invention is obtained by addition polymerization of the above-mentioned trihydric or higher aliphatic polyhydric alcohol (i) with bis (isocyanatomethyl) cyclohexane or the like (ii). can get.

The adduct preferably used in the present invention includes, for example, compounds represented by the following formulas. (1) Adduct between TMP and hydrogenated XDI:

[0035]

Embedded image

[R in the above formula: 1.3-cyclohexylene group] (2) Adduct of pentaerythritol and hydrogenated XDI:

[0037]

Embedded image

[R in the above formula: 1.3-cyclohexylene group] The isocyanurate structure (nurate structure) used as the polyisocyanate (b) in the present invention has, in the molecule, the above-mentioned general formula [I] One or two rings represented by
Have more than one.

The isocyanurate structure used in the present invention is, for example, the above-mentioned bis (isocyanatomethyl)
It can be obtained by performing a trimerization reaction, a pentamerization reaction, or a heptamerization reaction of cyclohexane (hydrogenated XDI, H6XDI).

[0040] In the mixing ratio present invention, the polyol (a1) and / or polythiol (a2) and polyisocyanate (b)
Is a ratio of the equivalent of the isocyanate group contained in the polyisocyanate (b) to the total equivalent of the hydroxyl equivalent contained in the polyol (a1) and the equivalent of the thiol group contained in the polythiol (a2) [NCO group / (OH group +
SH group)] is usually 0.1 to 5, preferably 0.2 to 4,
More preferably from 0.5 to 3, particularly preferably from 0.7 to
It is used in an amount falling within the range of 2.

When the carbodiimide-type polyisocyanate as described above is used in combination with the polyisocyanate other than the carbodiimide-type isocyanate as the polyisocyanate (b), the carbodiimide-type isocyanate is used per 100 parts by weight of the total amount of these polyisocyanates. Usually, it is used in an amount of 1 part by weight to less than 200 parts by weight, preferably 5 parts by weight to less than 150 parts by weight, more preferably 20 parts by weight to less than 100 parts by weight.

When the carbodiimide-type polyisocyanate is used in the above amount, a coating composition which can be rapidly cured to form a coating film can be obtained. The coating composition as described above can form a clear coating film as a clear coating composition, but a conventionally known coating additive such as a coloring pigment or a dispersant is blended within a range that does not impair the object of the present invention. And can be used as a usual coating composition.

The above polyol (a1) and / or
Alternatively, the coating composition comprising the polythiol (a2) and the polyisocyanate (b) has a long pot life and is easy to handle.

The amine catalyst used in the present invention is a tertiary amine, specifically, trimethylamine, dimethylethylamine, triethylamine, tributylamine,
Dimethylbenzylamine, dimethylcyclohexylamine, dimethylethanolamine, diethylethanolamine, triethanolamine, pyridine, 4-phenylpropylpyridine, 2,4,6-collidine, quinoline, isoquinoline, N-ethylmorpholine, triethylenediamine and the like. Can be Among them, dimethylethanolamine and triethylamine are preferably used.

The amine catalyst as described above is used in the form of a vapor using a spray gun or the like. In the present invention, when a coating composition comprising a polyol (a1) and / or a polythiol (a2) and a polyisocyanate (b) is used as the coating composition, the concentration of the vapor-form amine catalyst in spray coating is as wide as 20 to 4000 ppm. Can be set in a range. The preferred concentration of the vaporous amine catalyst is between 500 and 2000 ppm.

The viscosity of the coating composition used in the present invention is as follows:
It is 500 cPs or less, preferably 300 cPs or less, particularly preferably 100 cPs or less (measured with a B-type viscometer). A coating composition having such a viscosity tends to be finely atomized into fine particles, and is suitable for low-pressure, low-flying-speed electrostatic spray coating, and can improve coating efficiency in electrostatic coating. .

The electric resistance of the coating composition used in the present invention is usually about 30 to 100 MΩ. The heavy duty anticorrosion paint having such an electric resistance value is finely atomized by spraying.

Electrostatic coating method In the electrostatic coating, a high voltage is applied by using a grounded object as an anode (+) and a paint spraying device as a cathode (-) to form an electrostatic field between both electrodes, and the electrostatic field is applied. This is a method in which a paint is scattered inside, negatively charged and sucked by a workpiece to form a coating film on the surface of the workpiece.

When the heavy anticorrosion coating composition is electrostatically applied, for example, a coating film having a sufficient and uniform thickness can be applied to steel plate edges, holes and other narrow edges, and narrow portions of steel structures such as ships. Can be formed. Therefore, according to the present invention, as in the case of simple airless spray coating using a conventional tar-based heavy duty anticorrosive paint, additional coating by hand brushing of an edge portion or a narrow portion becomes unnecessary, and the number of steps is reduced. Can be reduced.

The electrostatic coating method for heavy duty anticorrosion coating according to the present invention has the following aspects. (1) A coating method in which a low-viscosity coating composition (coating composition) is applied to an object to be coated by an electrostatic coating method and rapidly cured to form a coating film in the presence of a vaporous amine catalyst. (2) After applying the coating composition to an object to be coated by an electrostatic coating method to form an uncured coating film, the uncured coating film is brought into contact with a vaporous amine catalyst to rapidly form the coating film. A method of curing and forming a coating film. (3) In the electrostatic coating method, the coating composition is sprayed from one of the paint spraying devices (eg, a spray gun) to adhere to the workpiece, and at the same time, the amine catalyst is sprayed from the other spraying apparatus to the workpiece. A coating method in which a hardened coating film is formed by spraying on the surface.

In the present invention, the coating method (3) is particularly preferred. The electrostatic coating device used for the electrostatic coating, the coating conditions, and the like will be described in further detail.

For such electrostatic coating, any of a fixed (automatic) coating apparatus and a portable (hand-held) coating apparatus can be used. Cup electrode type and rotary disk type are mentioned.

Of these, a portable coating apparatus using a spray gun is preferably used when painting vessels (objects to be coated) such as tankers, fishing boats, and passenger boats because of its excellent workability in a narrow environment.

The distance between the object to be coated and the cathode, the applied DC high voltage value, the feed pressure of the paint, the air pressure of the paint spray, etc., during such electrostatic coating depend on the type of paint to be used, its viscosity, and necessity. It can be appropriately set depending on the film thickness to be performed, the moving speed of the coating apparatus, and the like, and is not particularly limited.

In a portable (hand-held) coating apparatus, a cathode is set at the tip of a spray gun, and when the trigger is triggered, a negative charge is given to the sprayed paint particles, and an object to be coated separated by several to several tens of cm. Electrostatic painting is possible. The power supply voltage may be a low voltage, and the spray gun is suitable for on-site painting of a hull, for example, because it is easy to carry. In addition,
The spray gun includes, for example, an air atomization type, an airless atomization type, an electrostatic atomization type (rotary cup type) and the like, and any type may be adopted.

In the grid type coating, 30 to 200
kV (preferably 65 to 110 kV) is applied, and the distance between the object to be coated and the grid (cathode grid frame) is set to 10 kV.
１００100 cm (preferably about 30-50 cm), and at the time of air spraying, spray air pressure 0.5-5 kg / cm
² (preferably 1.5 to 2.5 kg / cm ² ), a paint feed pressure of 0.2 to ² kg / cm ² , a secondary pressure (paint pressure) of 50 to 300 kg / cm ² during airless spraying, and a moving speed of 20. ~ 200 cm / sec (preferably 40-90 cm /
Seconds).

In the rotating cup type, the rotation speed is 300 to 3
000 rotations / minute (preferably 750 to 1800 rotations / minute)
Minute), the paint is fed into the rotating cup (cathode) held therein, and the object to be coated can be electrostatically coated with an applied voltage of about 50 to 70 kV. Easy.

In any case, the surrounding wind speed at the time of coating is preferably as small as possible from the viewpoint of paint loss and painted skin, and is preferably 0.3 m / sec or less. When an electrostatic coating of an object to be coated is performed by such a method, the use of an automatic coating system such as a robot coating is particularly effective in reducing the number of work steps.

Heavy anticorrosion coating product The heavy anticorrosion coating (painted product) according to the present invention is prepared by the above-described electrostatic coating method for heavy anticorrosion coating according to the present invention.

In other words, the object to be coated is not particularly limited as long as it can be electrostatically coated with the above heavy anticorrosive paint.
Underwater / overwater structures (eg, gulf roads, submarine tunnels, harbor facilities, sludge diffusion prevention membranes for construction of various marine civil engineering facilities such as canals and waterways, rafts, floating docks, water intake and distribution pipes for power plants, oil and gas Ground structures such as bridges; various molded articles such as ships and fishing gear (eg, ropes and fishing nets).

These coated articles coated by the above method are excellent in anticorrosion properties, hardly destroyed in structure, and excellent in durability.

[0062]

According to the electrostatic coating method for heavy-duty anticorrosion coating according to the present invention, a low-viscosity heavy-duty anticorrosion paint containing a polythiol-isocyanate-based or polyol-isocyanate-based urethane resin which is rapidly cured by amine-like vapor. The composition is electrostatically coated, and the surface of the steel plate, such as the hull, is shielded from seawater, outside air, etc., and is required to have sufficient thickness to prevent corrosion of the steel plate by preventing ingress of oxygen, chlorine, water vapor, etc. The coating film can be easily and quickly formed on the surface of the object to be coated, and since the coating does not contain tar, the safety to workers and the environment is high.

According to the electrostatic coating method for heavy duty anticorrosion coating of the present invention, the coating composition can be rapidly cured on the object to be coated without heating to form a coating film. Therefore, even when applied to a vertical wall surface of a ship or the like, a coating film having a thickness of several hundred microns can be formed without causing dripping or slippage of the paint.

The electrostatic coating method for heavy duty anticorrosion coating according to the present invention can be carried out indoors and outdoors regardless of summer and winter. Examples of the coated product according to the present invention include ships, underwater / overwater structures, and the like.
It is prepared by the electrostatic coating method for heavy-duty anticorrosion coating according to the present invention as described above, is excellent in anticorrosion properties, is hardly destroyed in structure, and is excellent in durability.

[0065]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The methods of measuring the curing time of the paint and the methods of testing the appearance and water resistance of the coating film performed in the examples and comparative examples are as follows. (1) Method of measuring the curing time of paint In the examples and comparative examples, the curing time of paint was determined by JI
It was measured according to SK 5400 (6.5 (5) (b) semi-cured and dried). (2) Appearance of coating film According to JIS K 5400 7.1, gloss, unevenness, dents, repelling, crushing, etc. were observed. (3) Film thickness Electromagnetic film thickness meter LE-21 manufactured by Kett Science Laboratory Co., Ltd.
It was measured at zero.

Raw materials used in Examples and Comparative Examples are as follows. Polythiols (1) PETP Yodo Chemical Co., Ltd., equivalent of pentaerythritol tetrakis thiopropionate SH groups = 136 (2) OTG Yodo Chemical Co., Ltd., equivalent weight = 204 polyol thioglycolic acid octyl SH group (1) XU-K135 Takeda Pharmaceutical Co., Ltd., Takerac XU-K135, Castor oil polyol, 198 equivalents of hydroxyl group plasticizer (1) Necils EPX-L ICI Japan, Nesils E
PX-L (2) DBP manufactured by Dainippon Ink and Chemicals, dibutyl phthalate polyisocyanate (1) MTL manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Millionate MTL carbodiimide-type diphenylmethane diisocyanate NCO content = 28.9% ( 2) D-127N Takeda Pharmaceutical Co., Ltd., trade name Takenate D-12
7N H6XDI-based nurate, trimer of H6XDI NCO content = 13.5% (3) D-170HN Takeda Pharmaceutical Co., Ltd., trade name Takenate D-17
0HN HDI-based nurate, NCO content = 22.7% (4) Coronate HX Nippon Polyurethane Industry Co., Ltd., trade name Coronate
HX HDI-based nurate, NCO content = 21.1% pigments (1) Talc, manufactured by Fuji Talc Kogyo Co., Ltd., trade name Talc NKK Average particle size = 6-8 μm (2) Barium sulfate, manufactured by Sakai Chemical Industry Co., Ltd. (Trade name) Barium sulfate BA (3) Titanium white CR-93 (trade name) manufactured by Ishihara Sangyo Co., Ltd. (4) Polyamide wax (trade name ASA-T350F manufactured by Ito Oil Co., Ltd.)

[0068]

Examples 1 and 2 <Specimen> As shown in FIG. 1, a steel plate (SS-400) having a size of 450 × 450 × 20 mm and a steel plate having a size of 450 × 100 × 20 mm were welded. A T-shaped test piece (1) was prepared (FIG. 1).

FIG. 1B is a perspective view of the test piece (1), and FIG. 1A is a side view thereof. FIG.
In (A), numbers a to g indicate the positions where the paint adheres to the test pieces or the parts of the test pieces.

As shown in FIG. 2, a steel plate (SS-40)
0) Radius 30 on the test piece (450 x 100 x 20 mm)
A notched portion k having a semicircular shape of mm was provided, and the steel plate with the notched portion and another steel plate (450 × 450 × 20 mm) were welded to prepare a test piece (2) (FIG. 2).

FIG. 2 is a perspective view of the test piece (2). In FIG. 2, reference numerals h to k indicate positions where paint is applied on the test piece or portions of the test piece (k: notch). . <Coating> Using a jet techno (GM2000EAC) manufactured by Nippon Wagner Spray Tech Co., Ltd., a coating composition having the composition shown in Table 1 (Example 1: Composition 1, Example 2:
The composition 2) was sprayed at a spray angle of 50 (degrees) and the discharge amount was 570 ml.
/ Min, applied voltage 80 kv, air pressure 0.2 for air coat
The coating was performed at a weight of 30 kg / cm ² and a distance to the substrate. The coating was performed by spraying in the presence of an amine vapor catalyst.
In this test, the amine vapor concentration was 1000 to 2000 pp
m.

The film thickness (micron) of each part of the test piece was measured. The results are shown in Tables 2 and 3. Fig. 1
As shown in (A), upward (向 き) described by arrow “2”
The coating was performed by directing the gun in the horizontal (←) direction indicated by an arrow “1” and dried for one day, and the thickness of the coating film was measured with an electromagnetic film thickness meter. The measurement points are shown in the figure.

In the case of "1" in which the gun was painted sideways, in the electrostatic coating, a generally satisfactory film thickness could be ensured even in the area e parallel to the flight of the paint spray, which is usually inferior in paint application efficiency. In the electrostatic coating of the present invention, "2" with the gun facing upward
Similarly, in the case of (1), almost satisfactory film thickness is secured even on the planes a, b, c, d, and f parallel to the flight direction of the paint spray (the coating efficiency is poor in the conventional ordinary method). did it.

Similarly, in the method of the present invention (electrostatic coating),
Almost satisfactory film thickness could be secured even at the notch (k in FIG. 2) parallel to the paint spray flight direction, where the coating efficiency of the paint would be inferior if the conventional method was used.

[0075]

<Examples 3 and 4><Coating> Using Jet Techno (GM2000EAC) manufactured by Wagner Spray Tech Co., Ltd., a coating composition having the composition shown in Table 1 (Example 3: Composition 3, Example 4) :
Composition 4) was sprayed at a spray angle of 50 (degrees) and a discharge rate of 570 ml
/ Min, applied voltage 80 kv, air pressure 0.2 for air coat
The coating was performed at a weight of 30 kg / cm ² and a distance to the substrate. The coating was performed by spraying in the presence of an amine vapor catalyst.
In this test, the amine vapor concentration was 3000-6000 pp
m.

The film thickness (micron) of each part of the test piece was measured. The results are shown in Tables 2 and 3. Fig. 1
As shown in (A), upward (向 き) described by arrow “2”
The coating was performed by directing the gun in the horizontal (←) direction indicated by an arrow “1” and dried for one day, and the thickness of the coating film was measured with an electromagnetic film thickness meter. The measurement points are shown in the figure.

Similarly, in the method of the present invention (electrostatic coating),
Almost satisfactory film thickness could be secured even at the notch (k in FIG. 2) parallel to the paint spray flight direction, where the coating efficiency of the paint would be inferior if the conventional method was used.

Comparative Example 1 Coating was performed in the same manner as in Example 1, except that no applied voltage for electrostatic coating was applied.

The results are shown in Tables 2 and 3. In this test example, in the case of “1” in which the gun was painted sideways, it was difficult to secure a desired film thickness in the “e part” which is a plane parallel to the flight direction of the paint spray. Similarly, in the case of "2" in which the gun was painted upward, it was similarly difficult to secure the film thickness on the surfaces "a, b, c, d, and f portions" parallel to the flight direction of the paint spray. .

Similarly, it was difficult to secure a desired film thickness even at the notched surface “k” (FIG. 2) parallel to the flight direction of the paint spray.

[0080]

Comparative Example 2 Example 1 was repeated except that a tar epoxy paint was used as the paint and the coating was performed under the following conditions.
In the same manner as described above, coating was performed while applying an applied voltage for electrostatic coating.

The tar epoxy paint is available from China Paint Co., Ltd.
VISCON HB-200 was used. The viscosity of the paint was 25 cPs. <Coating conditions> Using jet techno (GM2000EAC) manufactured by Wagner Spray Tech Co., Ltd., the tar epoxy paint was sprayed at a spray angle of 40 (degrees) and a discharge amount of 1
The coating was performed at 140 ml / min, an applied voltage of 80 kv, an air pressure of 0.2 kg / cm ² for air coating, and a distance of 30 cm from the object to be coated. The coating was performed by spraying without using an amine vapor catalyst.

The film thickness (micron) of each part of the test piece was measured. The results are shown in Tables 2 and 3. In this test example, in the case of “1” in which the gun was painted sideways, “e” was a plane parallel to the paint spray flight direction despite the electrostatic painting.
It was difficult to secure a desired film thickness in the “section”. Similarly, in the case of "2" in which the gun is painted upward, the planes "a, b, c, d, and f portions" parallel to the paint spray flight direction are similarly used.
And it was difficult to secure the film thickness.

Similarly, it was difficult to secure a desired film thickness even at the notched surface “k” (FIG. 2) parallel to the flight direction of the paint spray. MIBK is an abbreviation for methyl isobutyl ketone.

[0084]

[Table 1]

[0085]

[Table 2]

[0086]

[Table 3]

[Brief description of the drawings]

FIG. 1 shows a T-shaped test piece (1) used in Examples and Comparative Examples. FIG. 1B is a perspective view of the test piece (1), and FIG. 1A is a side view thereof.

FIG. 2 shows a test piece (2) used in Examples and Comparative Examples.

[Explanation of symbols]

a, b, c, d, e, f, g, h, i, j, k: paint adhesion positions. k: Notch of test piece.

Claims (3)

[Claims] 1. A low-viscosity coating composition comprising a polyol (a1) and / or a polythiol (a2) and a polyisocyanate (b) is electrostatically coated in the presence of a vaporous amine catalyst. A method for applying a heavy duty anticorrosion coating composition. 2. The coating method according to claim 1, wherein the viscosity of the coating composition is 500 cPs or less. 3. A heavy-duty anticorrosion coated product, wherein a coating film is formed on a ship, an underwater / above-water structure by the coating method according to claim 1.