JP7545208B2 - Anticorrosive coating method for harbor and offshore structures - Google Patents

Description

The present invention relates to a method for anticorrosive coating of harbor and offshore structures using a paint composition.

Because port and offshore structures are difficult to repair and renew, they are designed to be used for 50 to 100 years. In particular, the steel components of port and offshore structures are treated with anti-corrosion agents to maintain their strength even in severe corrosive environments.

Methods of corrosion prevention that are widely used include cathodic protection, paint, lining, and coating with FRP. Of these, cathodic protection is an extremely effective corrosion prevention method in underwater areas where steel members are completely submerged. However, it is said that cathodic protection does not fully exert its corrosion prevention effect in areas where steel members are not completely submerged, such as tidal areas and splash areas.

In contrast, anti-corrosion treatments that use coating compositions to coat the surface effectively provide anti-corrosion protection even in tidal and splash areas, but they have problems with the surface being easily scratched and the coating film deteriorating over time. For this reason, there has been a need to develop an anti-corrosion treatment method that can maintain anti-corrosion properties over the long term even in the severe corrosive environments of tidal and splash areas at sea.

As a paint composition used for the anticorrosion treatment of harbors and marine structures, a two-liquid type paint composition consisting of a base agent containing a liquid epoxy resin and a hardener containing a polyamine is well known (for example, Patent Document 1, etc.). Patent Document 1 describes that the paint composition described contains a solid proton donor, which gradually releases acid in the vicinity of the substrate after the coating is formed, and suppresses the decrease in adhesion of the coating caused by the hydroxides of minerals in seawater.

However, the coating composition described in Patent Document 1 has insufficient curing properties, so it is prone to dripping during application, and when applied in a thick film, it takes a long time to dry.

Patent Document 2 also proposes a corrosion-resistant coating structure in which a primer coating is applied to the boundary between the corrosion-resistant metal coating and zinc-rich coating of an offshore structure, and an epoxy resin coating is applied on top of that. Patent Document 2 describes applying a thick film of epoxy resin coating material so that the dry film thickness is 2 mm, but does not disclose specific coating means.

In general, when applying two-component paint, the painter must mix the base agent and hardener until they are homogenous, and then place the resulting mixture in the hopper tank (container) of the paint application machine (see Figure 1). In addition, when the object to be painted is large-scale, such as a harbor or offshore structure, it is necessary to prepare a large amount of the base agent/hardener mixture. However, if a large amount of the mixture is prepared in advance, the reaction will proceed in the container before painting, resulting in a problem of a deterioration in the physical properties of the paint film obtained by painting. This has created a need to take measures such as preparing the mixture more frequently or applying multiple coats of paint until the desired film thickness is achieved.

That is, the present invention provides:
Item 1.
A method for anticorrosive coating using an anticorrosive coating composition, which comprises coating a harbor or marine structure as a substrate using a coating device so that the dry film thickness after one coat is 0.5 mm or more,
The anticorrosive coating composition is a two-liquid coating composition comprising a first component and a second component, the first component containing an epoxy resin having an epoxy equivalent of 1700 or less, the second component containing an amino group-containing resin , the first component and the second component both containing a pigment component, the first component and/or the second component containing a volatile substance, and the nonvolatile content concentration at the time of application is 80 mass% or more,
a coating apparatus for coating a harbor or marine structure comprising: a plurality of storage sections; a mixing section for mixing the raw materials stored in the plurality of storage sections; and a coating section for coating the mixed paint transported from the mixing section;
Item 2.
Item 2. The corrosion-resistant coating method according to item 1, wherein the object to be coated includes a tidal portion or a splash portion of a harbor or marine structure;
Item 3.
Item 3. The corrosion-resistant coating method according to Item 1 or 2, wherein the epoxy resin contains at least one epoxy resin selected from bisphenol A type epoxy resins, bisphenol F type epoxy resins, and novolac type epoxy resins as a part of its components;
Item 4.
4. The corrosion-resistant coating method according to any one of Items 1 to 3, wherein the epoxy resin is a combination of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin.
Item 5.
Item 5. The corrosion-resistant coating method according to any one of Items 1 to 4, wherein the volatile substance is an organic solvent having a boiling point of 170° C. or less;
Item 6 .
Item 6. The corrosion-resistant coating method according to any one of Items 1 to 5 , wherein the pigment component contains an anti-rust pigment as a part of its components;
Item 7 .
The anticorrosive coating method according to any one of Items 1 to 6 , wherein the anticorrosive coating composition contains glass fibers and/or glass flakes;
Item 8 .
8. The anticorrosive coating method according to any one of items 1 to 7 , wherein the pot life of the anticorrosive coating composition after mixing of two liquids is 20 minutes or more and less than 2 hours.
Item 9 .
The corrosion-resistant coating method according to any one of Items 1 to 8 , in which the first component is accommodated in a storage section and the second component is accommodated in another storage section and then coated;
Item 1 0 .
The anticorrosive coating method according to any one of items 1 to 9 , wherein the anticorrosive coating composition is applied in two or more separate applications;
Regarding.

The present invention aims to provide a corrosion-resistant coating method suitable for easily forming an extremely thick corrosion-resistant coating on objects having a large surface area, such as harbors and offshore structures.

The present invention aims to solve the problems of the prior art. More specifically, the present invention is a two-component coating composition that uses a specific epoxy resin and an amino group-containing resin, adjusts the non-volatile content concentration during coating to a specific range, and applies the coating using a specific coating device, making it possible to easily form a thick coating film that does not sag and can withstand long-term corrosion protection.

That is, the present invention provides:
Item 1.
A method for anticorrosive coating using an anticorrosive coating composition, which comprises coating a harbor or marine structure as a substrate using a coating device so that the dry film thickness after one coat is 0.5 mm or more,
The anticorrosive coating composition is a two-liquid coating composition comprising a first component and a second component, the first component containing an epoxy resin having an epoxy equivalent of 1700 or less, the second component containing an amino group-containing resin, the first component and/or the second component containing a volatile substance, and the nonvolatile content concentration at the time of application is 80 mass% or more,
a coating apparatus for coating a harbor or marine structure comprising: a plurality of storage sections; a mixing section for mixing the raw materials stored in the plurality of storage sections; and a coating section for coating the mixed paint transported from the mixing section;
Item 2.
Item 2. The corrosion-resistant coating method according to item 1, wherein the object to be coated includes a tidal portion or a splash portion of a harbor or marine structure;
Item 3.
Item 3. The corrosion-resistant coating method according to Item 1 or 2, wherein the epoxy resin contains at least one epoxy resin selected from bisphenol A type epoxy resins, bisphenol F type epoxy resins, and novolac type epoxy resins as a part of its components;
Item 4.
4. The corrosion-resistant coating method according to any one of Items 1 to 3, wherein the epoxy resin is a combination of a bisphenol A type epoxy resin and a bisphenol F type epoxy resin.
Item 5.
Item 5. The corrosion-resistant coating method according to any one of Items 1 to 4, wherein the volatile substance is an organic solvent having a boiling point of 170° C. or less;
Item 6.
Item 6. The anticorrosive coating method according to any one of Items 1 to 5, wherein the anticorrosive coating composition contains a pigment component;
Item 7.
Item 7. The anticorrosive coating method according to item 6, wherein the pigment component contains an anticorrosive pigment as a part of its components.
Item 8.
The anticorrosive coating method according to any one of items 1 to 7, wherein the anticorrosive coating composition contains glass fibers and/or glass flakes;
Item 9.
The corrosion-resistant coating method according to any one of Items 6 to 8, wherein the first component and the second component both contain pigment components;
Item 10.
The anticorrosive coating method according to any one of items 1 to 9, wherein the pot life of the anticorrosive coating composition after mixing the two liquids is 20 minutes or more and less than 2 hours;
Item 11.
Item 11. The corrosion-resistant coating method according to any one of Items 1 to 10, wherein the first component is accommodated in a storage section and the second component is accommodated in another storage section and then coated;
Item 12.
The anticorrosive coating method according to any one of items 1 to 11, wherein the anticorrosive coating composition is applied in two or more separate applications;
Regarding.

The corrosion-resistant coating method of the present invention achieves high coating workability and easily produces a thick coating film. The coating film formed has excellent drying properties even under room temperature drying conditions, and can provide corrosion protection for a long period of time even in harsh environments such as on the beach. Therefore, this corrosion-resistant coating method is an extremely suitable treatment method for corrosion protection of harbors and marine structures.

The harbor and marine structures that are the objects to be coated in this invention are structures in which a supporting material supports a superstructure built on the sea or in a harbor, and specific examples include piers, dolphins, revetments, breakwaters, quays, artificial islands, submerged tunnels, offshore airports, and offshore oil and gas facilities. The effects of this invention can be maximized especially in structures that have tidal or splash areas.

Next, we will explain the anticorrosive coating composition, which is the first feature of the anticorrosive coating method of the present invention.

Anticorrosive coating composition:
The anticorrosive coating composition is a two-component coating composition in which a first component contains an epoxy resin having an epoxy equivalent of 1700 or less, a second component contains an amino group-containing resin, and the first component and/or the second component contains a volatile substance.

Epoxy resin;
In the present invention, the first component contains an epoxy resin, which is a resin having an average of two or more epoxy groups in one molecule.

In the method of the present invention, from the viewpoints of thick film finish and corrosion resistance, the epoxy resin has an epoxy equivalent of 1700 g/eq or less, preferably in the range of 50 to 1,000 g/eq, and particularly preferably 100 to 800 g/eq.
The epoxy equivalent means the number of grams (g/eq) of a resin containing 1 gram equivalent of epoxy groups, and means a value published by the manufacturer or an epoxy equivalent measured in accordance with JIS K 7236.

In the method of the present invention, any resin can be used as the epoxy resin contained in the first component as long as the epoxy equivalent is within the above range. Specific examples include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol AD type epoxy resin; epoxy ester resins obtained by modifying the above bisphenol type epoxy resins with dibasic acids, etc.; novolac type epoxy resins such as cresol novolac type epoxy resin and phenol novolac type epoxy resin; alicyclic epoxy resin; polyglycol type epoxy resin; hydrogenated bisphenol A type epoxy resin; ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, Examples of the epoxy resins include aliphatic epoxy resins such as glycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane polyglycidyl ether, hexahydrophthalic acid diglycidyl ester, glycerin polyglycidyl ether, diglycerin polyglycidyl ether, and polyglycerin polyglycidyl ether, and epoxy group-containing acrylic resins containing epoxy group-containing acrylic monomers such as glycidyl (meth)acrylate as components. These may be used alone or in combination of two or more. In particular, it is preferable to use at least one selected from bisphenol A type epoxy resins, bisphenol A type epoxy resins, and novolac type epoxy resins, and in particular to use bisphenol A type epoxy resins in combination with bisphenol F type epoxy resins.

The content of the epoxy resin is preferably 30 parts by mass or more, and more preferably in the range of 50 to 90 parts by mass, based on 100 parts by mass of the nonvolatile content of the anticorrosive coating composition.

In this specification, non-volatile matter refers to the residue after removing volatile components, and the residue may be in a solid or liquid form at room temperature. For example, it refers to the residue when a sample is treated at 105°C for 3 hours to remove the volatile components.

Bisphenol A Type Epoxy Resin Among the above-mentioned epoxy resins, examples of the bisphenol A type epoxy resin include condensation products of bisphenol A and an epichlorohydrin adduct of bisphenol A, or condensation products of bisphenol A and a polyhydric alcohol such as a hydrogenated product of bisphenol A. Commercially available products include "jER825", "jER827", and "jER828" (all trade names, manufactured by Mitsubishi Chemical Corporation), "ADEKA RESIN EP-4100" (trade name, manufactured by ADEKA Corporation), and "Epotohto YD-128" (trade name, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.).

Bisphenol F Type Epoxy Resin Examples of bisphenol F type epoxy resins include condensation products of bisphenol F and an epichlorohydrin adduct of bisphenol F, or condensation products of bisphenol F and a polyhydric alcohol such as a hydrogenated product of bisphenol F. Commercially available products include "jER806", "jER806H", and "jER807" (all trade names, manufactured by Mitsubishi Chemical Corporation), EPICLON 830, and EPICLON 835 (all trade names, manufactured by DIC Corporation), etc.

Novolac-Type Epoxy Resin There are no particular limitations on the novolac-type epoxy resin as long as it has two or more epoxy groups in one molecule and has a novolac structure. Examples of the novolac-type epoxy resin include phenol novolac epoxy resin, which is a polycondensation product of phenol novolac resin and epichlorohydrin, and cresol novolac epoxy resin, which is a polycondensation product of cresol novolac resin and epichlorohydrin. Of these, phenol novolac epoxy resin is preferred.

When the epoxy resin contained in the first component in the anticorrosive coating composition is a combination of bisphenol A type epoxy resin and bisphenol F type epoxy resin, the combined ratio is preferably bisphenol A type epoxy resin/bisphenol F type epoxy resin mass ratio of 5/95 to 95/5, particularly 10/90 to 90/10, from the viewpoints of adhesion to the substrate and thick film finish.

Amino group-containing resin;
On the other hand, the amino group-containing resin contained in the second component is a resin having an average of two or more amino groups in one molecule, and includes aliphatic polyamines, aromatic polyamines, aliphatic polyamidoamines, aromatic polyamidoamines, and amine-based resins of epoxy adduct modifications obtained by reacting these polyamines or polyamidoamines with epoxy resins, etc. Among them, the use of aliphatic polyamidoamines and/or aromatic polyamidoamines is preferred from the viewpoint of finishability in a thick film.

Aliphatic polyamines include ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, pentaethylenehexamine, and modified polyamines thereof. Aromatic polyamines include phenylenediamine, xylylenediamine, and modified polyamines thereof. Polyamidoamines include products such as polyamidoamine obtained by reacting the aliphatic or aromatic polyamines with dimer acid (polymerization product of unsaturated fatty acid) or other polycarboxylic acids, and modified polyamidoamines thereof.

From the viewpoint of thick film finish and corrosion resistance, it is preferable to use an amino group-containing resin with an amine value in the range of 50 to 500 mg KOH/g, particularly 150 to 400 mg KOH/g. In this specification, the amine value is the amount (mg) of potassium hydroxide equivalent to the hydrochloric acid required to neutralize the amine contained in 1 g of sample, and means the manufacturer's published value or the amine value measured in accordance with JIS K 7237.

The amount of the amino group-containing resin can be adjusted as appropriate, but it is appropriate to add at least 3 parts by mass, and more preferably within the range of 5 to 45 parts by mass, based on 100 parts by mass of the nonvolatile content of the anticorrosive coating composition.

Volatile substances;
The anticorrosive coating composition contains a volatile substance. The inclusion of the volatile substance is effective in improving the workability of coating when coating a thick film using a coating device described below. As the volatile substance, organic solvents or water used in the coating field can be used, but from the viewpoint of workability and finish of coating when coating a thick film, it is preferable to use at least one organic solvent selected from the group consisting of hydrocarbon organic solvents, alcohol organic solvents, ester organic solvents, glycol organic solvents, and ketone organic solvents.
Examples of the hydrocarbon organic solvent include mineral spirits, solvent naphtha, turpentine, normal decane, toluene, and xylene.
Examples of the alcohol-based organic solvent include methanol, ethanol, isopropanol, tert-butanol, secondary butanol, isobutanol, n-butanol, and methyl isobutyl carbinol.
Examples of the ester-based organic solvent include ethyl acetate, butyl acetate, and isobutyl acetate.
Examples of glycol organic solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, and ethylene glycol mono-tert-butyl ether.
Examples of the ketone organic solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, ethyl isoamyl ketone, diisobutyl ketone, etc. These can be used alone or in combination of two or more.

From the viewpoint of thick-film coating workability and finish, it is preferable to use volatile substances with a boiling point of 170°C or less. The content of volatile components is adjusted by the volatile components themselves or by introducing them from raw materials so that the non-volatile content of the anticorrosive coating composition at the time of application falls within the range described below.

Pigment content;
In the present invention, from the viewpoint of thick-film coating workability, the anticorrosive coating composition preferably contains a pigment component. As the pigment component, a coloring pigment, an extender pigment, an anticorrosive pigment, etc. are preferably used.

Examples of coloring pigments include titanium dioxide, red iron oxide, carbon black, iron oxide, zinc oxide, etc., and examples of extender pigments include calcium carbonate, barium sulfate, barium carbonate, magnesium silicate, clay, talc, calcined kaolin, etc. Examples of the rust-preventive pigment include metal phosphate compounds such as zinc phosphate, magnesium phosphate, magnesium ammonium phosphate co-eutectoid, magnesium monohydrogen phosphate, magnesium dihydrogen phosphate, magnesium calcium phosphate co-eutectoid, magnesium phosphate co-eutectoid, magnesium nickel phosphate co-eutectoid, calcium phosphate, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium fluoride phosphate, aluminum phosphate, and aluminum hydrogen phosphate; metal phosphate compounds such as magnesium phosphite, calcium phosphite, magnesium calcium phosphite co-eutectoid, basic zinc phosphite, barium phosphite, manganese phosphite, and calcium hypophosphite; metal phosphate compounds such as calcium silicate, zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, aluminosilicates, borosilicates, beryllosilicates, calcium aluminum silicate, sodium aluminum silicate, beryllium aluminum silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, and calcium silicate. Examples of the pigments include metal silicates such as sodium calcium, zirconium silicate, magnesium orthosilicate, magnesium metasilicate, calcium magnesium silicate, manganese silicate, and barium silicate; metal ion-exchanged silica compounds such as magnesium ion-exchanged silica and calcium ion-exchanged silica; condensed phosphate metal compounds such as aluminum dihydrogen tripolyphosphate, magnesium tripolyphosphate, aluminum tripolyphosphate, and zinc dihydrogen tripolyphosphate; vanadium metal compounds such as vanadium pentoxide, calcium vanadate, magnesium vanadate, and ammonium metavanadate, a calcined product of manganese oxide and vanadium oxide, and a calcined product of calcium phosphate and vanadium oxide; molybdate metal compounds such as aluminum molybdate, calcium molybdate, and aluminum phosphomolybdate; zinc compounds such as zinc and zinc oxide; silica compounds such as silica and colloidal silica; composite metal oxides such as a composite oxide of iron oxide and magnesium oxide, a composite oxide of iron oxide and calcium oxide, and a composite oxide of iron oxide and zinc oxide. The pigments exemplified above may be used alone or in combination of two or more.

The content of the pigment is preferably 0.1 to 50 parts by mass, more preferably 2 to 40 parts by mass, based on 100 parts by mass of the nonvolatile content of the anticorrosive coating composition.
In the present invention, from the viewpoint of long-term corrosion prevention, it is preferable that the pigment component contains an anti-rust pigment as a part of its components. When the anti-rust pigment is contained, the content of the anti-rust pigment is preferably 0.1 to 30 parts by mass, more preferably 1.5 to 20 parts by mass, based on 100 parts by mass of the non-volatile content of the anti-corrosion coating composition.

Glass fibre or glass flakes;
The anticorrosive coating composition may contain glass fibers or glass flakes from the viewpoint of adhesion when the coating is thick. The glass fibers have an aspect ratio of 3.5 or more, preferably in the range of 4 to 25. The aspect ratio is the value of the major axis diameter/minor axis diameter of the glass fibers, and the minor axis diameter and major axis diameter referred to here are determined by averaging the minor axis diameter and major axis diameter of each of 100 primary particles present in a certain area measured by electron microscope observation. When glass fibers are used, the content is suitably in the range of 0.1 to 30 parts by mass, preferably 1.5 to 20 parts by mass, based on 100 parts by mass of the nonvolatile content of the anticorrosive coating composition.

In the present invention, glass flakes refer to flat glass, and it is preferable to use glass flakes with an average particle size of 10 to 300 μm.

In this specification, the average particle size of the glass flakes is the median size derived from the volume distribution measured by the laser diffraction scattering method.

As the glass flakes, commercially available products can be used, and specific examples include "RCF-15", "RCF-140", "RCF-160", "RCF-600", "REF-600", and "RCF-2300" (all manufactured by Nippon Sheet Glass Co., Ltd.). When using glass flakes, the content is suitably in the range of 0.1 to 30 parts by mass, preferably 1.5 to 20 parts by mass, based on 100 parts by mass of the nonvolatile content of the anticorrosive coating composition.

The anticorrosive coating composition is a two-liquid coating composition consisting of a first component and a second component, the first component containing an epoxy resin having an epoxy equivalent of 1700 or less, and the second component containing an amino group-containing resin. From the viewpoints of ease of coating work using a coating device described below and ease of coating preparation, a mixing ratio of the first component to the second component of 10:1 to 1:1, particularly 4:1 to 1:1 by mass is suitable.
In the present invention, the first component, the second component, or both may contain modifying resin components such as resins other than the above-mentioned epoxy resins; and paint additives such as pigment dispersants, surface conditioners, defoamers, thickeners, curing catalysts, plasticizers, reactive diluents, antifreeze agents, antiskinning agents, and preservatives.

It is preferable that both the first and second components contain a pigment. By including both the first and second components in a pigment, there is an effect of excellent thick-film finish. In this case, the proportion of the pigment contained in the nonvolatile content of the first component is 0.1 to 50 mass%, particularly about 2 to 30 mass%, and the proportion of the pigment contained in the nonvolatile content of the second component is suitably in the range of 1 to 70 mass%, particularly 10 to 60 mass%.

Next, we will explain the coating equipment, which is the second feature of the corrosion-resistant coating method of the present invention.

Painting equipment;
The coating apparatus used in the corrosion-resistant coating method of the present invention is a coating apparatus comprising a plurality of storage sections, a mixing section for mixing the raw materials stored in the plurality of storage sections, and a coating section for coating the mixed paint transported from the mixing section.

Figure 2 is a schematic diagram illustrating an example of a coating device used in the corrosion-resistant coating method of the present invention.

As shown in FIG. 2, the coating apparatus used in the method of the present invention is equipped with two hopper tanks. The number of hopper tanks can be changed as appropriate depending on the number of raw materials used. The first component is stored in the first hopper tank, and the second component is stored in another hopper tank, so that the first and second components are stored separately. The raw materials stored in these two hopper tanks are controlled so that the required amount is supplied to the transport pipe, and are supplied to the transport pipe at a desired ratio by gravity or a pump. The transport pipe is equipped with a static mixer, which mixes the first and second components uniformly. The mixed liquid is pressure-fed to the coating gun by means of an airless pump or the like. The nozzle of the coating gun may be equipped with a nozzle tip.

When painting, each raw material is placed in a hopper tank, the mixing ratio is set, the static mixer and airless pump are operated, and the mixture is pressurized by the pump. The mixture is then sprayed in a mist form from the nozzle of the paint gun using hydraulic pressure, atomizing it and applying the paint to the object to be painted.

Anticorrosive coating method;
In the anticorrosive coating method of the present invention, the non-volatile content of the anticorrosive coating composition after mixing the first and second components is adjusted to 80% by mass or more, particularly 90% by mass or more, particularly 95% by mass or more, from the viewpoint of thick film finish. The non-volatile content concentration at the time of application is obtained by measuring the non-volatile content concentration of a sample of the coating material extracted from the tip of the coating section of the coating device. The amount of the sample is 1.0 gram, and the drying conditions are 105°C and 3 hours. In addition, the anticorrosive coating composition used in the method of the present invention can have a pot life of 20 minutes or more and less than 2 hours after mixing the first and second components. The pot life is the longest time that the anticorrosive coating composition can be used after mixing the two components. In this specification, the temperature of each component before mixing the two components is adjusted to 20°C and the measurement is performed.

The amount of the anticorrosive coating composition applied can be varied as appropriate, but from the viewpoint of long-term corrosion protection, the dry film thickness obtained from one coat is 0.5 mm or more, and is preferably in the range of 0.5 to 2.5 mm. The coating may be applied once, but it is preferable to apply the coating in two or more coats. The formed coating film can be dried at room temperature, but forced drying may be used if necessary.

FIG. 1 is a schematic diagram for explaining a coating apparatus that has been used in a conventional anticorrosive coating method. FIG. 2 is a schematic diagram for explaining an example of a coating apparatus used in the corrosion-proof coating method of the present invention.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In the following examples, "parts" and "%" refer to "parts by mass" and "% by mass", respectively.

<Production of Anticorrosive Coating Composition>
Production Examples 1 to 19
The components shown in the main agent part of Table 1 were blended in a container and stirred and mixed to obtain a main agent component (. The components shown in the hardener part of Table 1 were blended in a separate container and stirred and mixed to obtain a hardener component, thereby obtaining two-component anticorrosive coating compositions (A-1) to (A-19).

(Note 1) Liquid bisphenol A type epoxy resin: epoxy equivalent 190
(Note 2) Liquid bisphenol F type epoxy resin: epoxy equivalent 190
(Note 3) Solid bisphenol A type epoxy resin: epoxy equivalent 475
(Note 4) Solid novolac type epoxy resin: solid, epoxy equivalent 170
(Note 5) Solid bisphenol A type epoxy resin: epoxy equivalent 2000
(Note 6) Anti-rust pigment 1: Silomask 22MR-H Magnesium ion-containing silica-based anti-rust pigment (Note 7) Anti-rust pigment 2: NP1055C Ca phosphite/zinc oxide-based anti-rust pigment (Note 8) Glass fiber: aspect ratio 20,
(Note 9) Glass flakes: average particle size 160 μm,
(Note 10) Xylene: boiling point 139°C,
(Note 11) Amine 1: Aromatic polyamidoamine, amine value 360
(Note 12) Amine 2: Aliphatic polyamidoamine, amine value 360
(Note 13) Amine 3: Aliphatic polyamidoamine, amine value 200.

<Painting>
Example 1
Coating machine A (GRACO's two-component mixing airless spray coating machine "XP-50") equipped with two tanks, a compressor, a static mixer, an airless pump and a coating gun was prepared. The base agent was placed in one tank and the hardener in the other tank, and the raw material supply ratio from the base agent tank and the hardener tank was set to 2:1. The coating machine was then operated and, while mixing with the static mixer, a 1 square meter steel plate was coated with a dry film thickness of 1 mm under conditions of a primary pressure of 3 MPa and a gun distance of 45 cm.
After the first coating was completed, the plate was left to cure at room temperature for 48 hours, and then a second coat was applied in the same manner so that the dry film thickness was 1 mm. The plate was then dried at room temperature for 7 days to obtain a test plate having a coating film with a final dry film thickness of 2 mm.

Examples 2 to 15, Comparative Examples 1 and 2
Coating was carried out in the same manner as in Example 1 above, except that the base resin and hardener compositions used were as shown in Table 1.

Example 16 and Comparative Example 3
A test panel was obtained in the same manner as in Example 1, except that the dry film thickness in one run was adjusted to the film thickness shown in Table 1.

Examples 17 and 18
In Example 1, the base resin and hardener compositions used were as shown in Table 1, and test panels were obtained in the same manner as in Example 1, except that the coating was performed in one step instead of in two steps. After coating with coating machine A, the panels were dried at room temperature for 7 days to form a coating film with a dry thickness of 2 mm.

Comparative Example 4
The main component and hardener components shown in Table 1 were placed in a container and mixed with a hand mixer until uniform, to obtain a coating preparation.
A type of applicator B (Anest Iwata airless applicator ALS-653) of Fig. 1, equipped with one tank, compressor, airless pump and airless gun, was prepared, the above preparation was placed in the built-in tank, and a steel plate of 1 square meter in size was painted to a dry film thickness of 2 mm under conditions of a primary pressure of 3 MPa and a gun distance of 45 cm. In this painting, the preparation in the tank thickened over time, and although painting was possible, the atomization of the paint sprayed from the spray hole became poor during painting.

(*) Pot life: After mixing the base resin and the curing agent, the mixture was left at 20° C. and the time (in minutes) until the limit viscosity for spray coating was reached was measured. The higher the value in the table, the better the result.
(*) Finishing Property The appearance of each test plate obtained in the above Examples and Comparative Examples was evaluated visually.
◎: Very good 〇: Good △: The coating surface is slightly rough ×: The coating surface has defects such as pinholes and bumps.
(*) Adhesion: A pull-off adhesion test was performed using an adhesion tester manufactured by Elcometer. The measurement position of each test plate was lightly polished with sandpaper to clean it, and then attached to the tester terminal using adhesive. The coating film around the terminal was cut with a cutter, and the terminal was peeled off with the tester, and the strength (MPa) and coating film condition at that time were observed.
◎: 7 MPa or more and cohesive failure of the coating film ○: 3 MPa to 7 MPa and cohesive failure of the coating film △: Cohesive failure at 2 to 3 MPa, or delamination of the coating film at more than 3 MPa ×: Cohesive failure at less than 2 MPa, or delamination at less than 3 MPa (*) Each test plate obtained in the corrosion prevention examples and comparative examples was immersed in artificial seawater at 40°C for 6 months and the condition of the coating film was observed.
◎: No change at all before and after immersion.
◯: Blisters were observed after immersion, but no rust was observed. Δ: Rust was observed in 1 to 5 places after immersion. ×: Rust was observed in more than 5 places after immersion.

Claims (10)

A method for anticorrosive coating using an anticorrosive coating composition, which comprises coating a harbor or marine structure as a substrate using a coating device so that the dry film thickness after one coat is 0.5 mm or more,
The anticorrosive coating composition is a two-liquid coating composition comprising a first component and a second component, the first component containing an epoxy resin having an epoxy equivalent of 1700 or less, the second component containing an amino group-containing resin, the first component and the second component both containing a pigment component, the first component and/or the second component containing a volatile substance, and the nonvolatile content concentration at the time of application is 80 mass% or more,
The coating device is a two-component mixing type airless spray coating device comprising: a plurality of storage sections; a mixing section for mixing the respective raw materials stored in the plurality of storage sections; and a coating section for coating the mixed paint transported from the mixing section. The corrosion-resistant coating method according to claim 1, characterized in that the object to be coated includes tidal or splash areas of a harbor or marine structure. The corrosion-resistant coating method according to claim 1 or 2, wherein the epoxy resin contains at least one epoxy resin selected from bisphenol A type epoxy resin, bisphenol F type epoxy resin, and novolac type epoxy resin as part of its components. The anticorrosive coating method according to any one of claims 1 to 3, wherein the epoxy resin is a combination of bisphenol A type epoxy resin and bisphenol F type epoxy resin. The anticorrosive coating method according to any one of claims 1 to 4, wherein the volatile substance is an organic solvent having a boiling point of 170°C or less. An anticorrosion coating method according to any one of claims 1 to 5, in which the pigment component contains an anticorrosive pigment as part of its components. The anticorrosive coating method according to any one of claims 1 to 6, wherein the anticorrosive coating composition contains glass fibers and/or glass flakes. The anticorrosive coating method according to any one of claims 1 to 7, wherein the pot life of the anticorrosive coating composition after mixing the two liquid components is 20 minutes or more and less than 2 hours. The corrosion-resistant coating method according to any one of claims 1 to 8, in which the first component is contained in a container and the second component is contained in another container and then coated. The anticorrosive coating method according to any one of claims 1 to 9, in which the anticorrosive coating composition is applied in two or more separate applications.

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