JPH10264301A - Method for corrosion-proof coating of steel pipe, and steel pipe provided with corrosion-proof coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make pitting corrosion be hardly brought about, by providing a Zn-Al pseudo-alloy layer of which the Al content is a specified value, a water-based coating film layer of which the water absorption is a specified value and further a solvent coating film on a steel pipe. SOLUTION: By this method for corrosion-proof coating of a steel pipe, a Zn-Al pseudo-alloy layer which is provided as a primer layer showing an effect of cathodic protection and of which the Al content is 15-50 wt.%, then a water-based coating film layer which is provided for improving the effect of the cathodic protection of the primer layer and of which the water absorption is 5-50% and lastly a solvent coating film which is provided for intercepting water in the water-based coating film layer from the water in an environment, lessening the lowering of the effect of the cathodic protection due to the provision of the water-based coating film and also protecting the steel pipe from an impact or the like from outside, are provided on the steel pipe. When the Al content is in the range of 15-50 wt.%, the effect of the cathodic protection being more excellent than that of a Zn layer is shown. In the case when the water absorption of the water-based coating film layer is less than 5%, the effect of the cathodic protection is not seen nearly at all, and when it exceeds 50%, the coating film has a bloating tendency, which is undesirable for durability, though the effect of the cathodic protection is shown.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosion coating method for an iron pipe to be piped underground and an anticorrosion coated iron pipe using the method.

[0002]

2. Description of the Related Art The outer surface of an iron pipe is usually coated with a synthetic resin or a combination of a Zn-based primer coating and a synthetic resin coating.

[0003] As the synthetic resin paint used for the above-mentioned synthetic resin coating, usually, a solvent-based paint such as a tar epoxy resin paint, an epoxy resin paint, a urethane resin paint, an acrylic resin paint, or a phthalic acid resin paint is mainly used. I have.

[0004] Synthetic resin coating forms a coating film which is strong, has low water absorption and good adhesion, and prevents corrosion of the iron tube by preventing moisture and air from coming into contact with the iron tube.

[0005] However, the disadvantage of the iron tube to which this anticorrosion method is applied is that when the coating film is damaged, moisture, oxygen, etc. adhere to the damaged portion of the coating film, and the potential difference between the damaged portion and the sound portion is reduced. And erosion is intensively performed on the damaged part, resulting in pitting. In addition, when moisture and air permeate the coating film due to some influence, the surface of the iron pipe corrodes, the coating film peels off, and the effect of coating is lost.

[0006] A coating system in which a Zn-based primer coating and a synthetic resin coating are combined is a coating system that covers the above-mentioned drawbacks of the synthetic resin coating, and is a method of protecting an iron pipe by utilizing the function of Zn's cathodic protection.

[0007]

However, even in the case of a combination of a Zn-based primer coating and a synthetic resin coating, the above-mentioned disadvantages of the synthetic resin coating have not been completely covered. In other words, Zn-based primer coating exhibits a cathodic protection effect only when it comes in contact with water. However, when a coating with low water absorption is applied to the top coating of Zn-based primer, for example, if a scratch is made, a sound coating portion Has no moisture, so that the cathodic protection effect of Zn is not exhibited, whereas the scratched portion comes into contact with moisture, so that initially the Zn is cathodically protected around the wounded portion, but Zn was consumed. Later, a large potential difference occurs with the healthy part,
Corrosion proceeds in the direction in which pitting occurs in the damaged area.

[0008]

SUMMARY OF THE INVENTION The present invention develops a coating system which improves the drawbacks of a coating system combining a Zn-based primer coating and a synthetic resin coating and maximizes the effects of the Zn-based primer coating. A Zn-Al pseudo-alloy layer having an Al content of 15 to 50% (% by weight, the same applies hereinafter) on an iron tube, and a water-based paint film layer having a water absorption of 5 to 50%; The method of claim 1, further comprising providing a solvent-based paint film layer, wherein the Zn-Al pseudo alloy layer has an Al content of 20 to 40%. The method (Claim 2), wherein the anticorrosion coating method according to Claim 1 (Claim 3), wherein the water-based paint film layer has a water absorption of 10 to 40%, wherein the water-based paint film layer is formed of an acrylic emulsion paint. 2. A coating film layer. The anticorrosion coating method according to claim 1, wherein the solvent-based coating film layer is a coating layer made of an epoxy resin coating, a urethane resin coating, an acrylic resin coating, or a phthalic acid resin coating. Method (Claim 5), Zn-A having an Al content of 15 to 50% on an iron tube.
(1) a pseudo-alloy layer, a water-based paint film layer having a water absorption of 5 to 50%, and a corrosion-resistant coated iron pipe further provided with a solvent-based paint film layer (Claim 6); 7. The anticorrosion coated iron pipe according to claim 6, wherein the water absorption is 10 to 4%.
The anticorrosion coated iron pipe according to claim 6, which is 0% (claim 8),
7. The anticorrosion-coated iron pipe according to claim 6, wherein the water-based paint film layer is a film layer made of an acrylic emulsion paint, and the solvent-based paint film layer is an epoxy resin paint, a urethane resin paint, The anticorrosion-coated iron pipe according to claim 6, which is a coating layer made of an acrylic resin paint or a phthalic acid resin paint.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The anticorrosion coating method of the present invention comprises a Zn-Al pseudo-alloy layer having an Al content of 15 to 50% provided as a primer layer exhibiting a cathodic protection effect on an iron tube, and a cathode of the primer layer. Anticorrosion effect (throwing power)
The water-based paint film layer having a water absorption of 5 to 50% and finally the water-based paint film layer and the water in the environment are cut off to provide a water-based paint film. This is carried out by providing a solvent-based paint film layer provided to reduce the deterioration of the anticorrosion effect and to protect the iron tube from external impact and the like. An anticorrosion coating method in which a water-based paint film layer having a water absorption of 5 to 50% is provided between the Zn-Al pseudo-alloy layer and the solvent-based paint film layer to improve the throwing power of the Zn-Al pseudo-alloy layer, This is the first method performed by the present inventors.

[0010] The iron pipe before applying the anticorrosion coating is not particularly limited as long as it is used as an iron pipe to be piped underground.

The Zn-Al pseudo-alloy layer provided on the iron tube is one kind of a Zn-based primer applied as a base treatment for the iron tube, and is formed by spraying both of Zn and Al alone by arcing. This layer is completely different from a layer formed by spraying a material in which Zn and Al are dissolved in the first place, such as a Zn-Al alloy layer. In addition, Zn-
Since it is not necessary to dissolve Zn-Al and adjust the components as in the case of an Al alloy, it is economically excellent. Furthermore, Zn-
The Al pseudo alloy layer includes a zinc-rich paint layer and a Zn-Al
When the alloy layer is provided, the anti-corrosion effect on the unpainted portion is better than when the alloy layer is provided, and the durability of the anti-corrosion potential is in the order of Zn-Al pseudo alloy layer> Zn-Al alloy layer> Zinc rich paint layer.

This is attributable to the consumption of Zn and the subsequent formation of a passivation film. In the case of a Zn-Al alloy layer or a zinc-rich paint layer, consumption of Zn starts at the same time as immersion in a saline solution.
This is considered to be because the cathodic protection ability is quickly lost due to precipitation of oxides, carbonates, chlorides, and the like of n without forming an immobile body film and producing a corrosion prevention effect due to the sacrifice of Zn. In the case of a Zn—Al pseudo alloy layer, both Zn and Al are independently arced and sprayed.
n and Al are scaly, Al moderately suppresses the consumption of Zn, and Al forms a passivation film, and maintains the throwing power for a long time by the combined action of Zn and Al. It is considered something.

The Al content in the Zn—Al pseudo alloy layer is 15 to 50%, more preferably 20 to 40%.
When the l content is within this range, a cathodic protection effect superior to that of the Zn layer is exhibited.

The effect of the spraying of the Zn—Al pseudo alloy layer is obtained as long as it is 50 g / m ² or more, and preferably 300 g / m ² or less in consideration of economy.

The layer provided on the Zn-Al pseudo-alloy layer must be one that maximizes the function of the Zn-Al pseudo-alloy layer, which is the above-described anticorrosion underlayer. In other words, as a coating, the cathodic protection of the anticorrosion base layer is expressed in a wider range and is maintained for a long period of time. Even if the coating is damaged, the scratching point is protected by the throwing power, and the coating itself has excellent durability. Is desirable.
If there is no anti-corrosion base layer,
In general, it was considered that the coating film should be strong, have low water absorption, have good adhesion, and do not allow moisture and air to permeate. The present inventors have found that a substance having water absorption, strong and good adhesion has a large effect of preventing pitting corrosion.

The reason that pitting corrosion is reduced when the coating film has water absorption is that corrosion of the iron pipe is caused by a micropotential difference. Therefore, making the potential difference as small as possible prevents pitting corrosion. The above are preferred. In other words, if the coating is water-absorbing, the potential of the entire iron tube tends to be constant, and even if a part of the coating is damaged, the healthy coating also absorbs water, so the potential is easily dispersed and leveled. This is considered to be because the potential difference is reduced and pitting corrosion is reduced. This theory assumes that a Zn-based primer layer (Zn layer, Zn-Al alloy layer, Zn-Al pseudo alloy layer,
By applying even if a zinc-rich paint layer is provided, in the case of a coating film having no water absorption, when a scratch is generated on the coating film, a potential difference is generated between the scratched portion and a healthy portion, and Zn is removed at the scratched portion by water. Eluted and consumed, and the cathodic protection effect of Zn disappears, and eventually pitting occurs. The cause of the potential difference is that the sound-absorbing top coat does not have water absorption
The cathodic protection effect does not occur, and the potential becomes higher than that of the flaw, and pitting occurs at the flaw of a low potential. In the case of a water-absorbing coating film, the cathodic protection of Zn occurs in the same way as around the wound, since the sound area also absorbs moisture, the potential difference becomes uniform, and the scratch is also protected. And exerts throwing power.

As the water-absorbing coating film, there is usually a coating film made of a water-based coating. A coating film formed from a water-based paint has good affinity with water, has a suitable level of water absorption, and has a large molecular weight, so that the coating film strength is large and the adhesion is good. Even a solvent-based coating can form a water-absorbing coating depending on the components constituting the coating, such as a solvent-based coating from a low-molecular-weight synthetic resin containing many hydrophilic groups or a coating from bitumen. . However, although the coating from such materials has water absorption, the strength of the coating is low due to low molecular weight,
Poor adhesion. Any solvent-based paint having the same performance as the coating film from the water-based paint may be used.

The water-absorptivity of the water-based paint film layer provided on the Zn-Al pseudo-alloy layer is preferably 5 to 50% in terms of the effect of the throwing power and the durability of the paint film. preferable. When the water absorption is less than 5%, the effect of the throwing power is hardly recognized, and 50%.
Exceeding the above value has an effect of throwing power, but since the coating film has swelling property, it is not preferable from the viewpoint of durability of the coating film. The water-based paint film layer has a water absorption of 10 to 4;
When it is 0%, and more preferably 12 to 30%, the effect of the throwing power is maintained over a long period of time and the durability is good.

The water-absorptivity of the water-based paint film layer is determined by applying a water-based paint to a glass plate (70 mm × 150 mm × 2 mm thick) to form a film having a thickness of about 60 μm, and drying at 30 ° C. for 6 days. It is the ratio of water absorbed to the water-based paint film when the paint film is peeled off from the glass plate and the weight of the paint film piece is measured and then immersed in water for one month.

The thickness of the water-based paint film layer is 50
３００300 μm, more preferably 60-100 μm. The water-based paint film layer is usually one layer,
It may be a multilayer.

Specific examples of the water-based paint used for forming the above-mentioned water-based paint film layer include synthetic resin emulsion paints such as acrylic emulsion paint, vinyl acetate emulsion paint, styrene-butadiene emulsion paint, and water-soluble paint. Water-soluble alkyd resin paint, water-soluble melamine resin paint, water-soluble urea resin paint, water-soluble phenol resin paint, water-soluble acrylic resin paint, water-soluble epoxy resin paint, water-soluble synthetic resin paint such as polybutadiene resin paint, etc. However, the present invention is not limited to these. These may be used alone or as a mixture of two or more. Of these, acrylic emulsion paints are preferred.

The solvent-based paint film layer used as the third layer after the water-based paint film layer is provided is a Zn-Al pseudo alloy layer as an underlayer (first layer) and a second water-based paint film layer. This is for further exhibiting the effect of the film layer. The required performance is a paint that protects the undercoat layer and the water-based paint film layer and creates a durable paint film, that is, it has good adhesion to the water-based paint film, and the paint film is tough and has low water absorption. (Water absorption is 4
% Or less, more preferably 3.5% or less), and the coating film has a high electric resistance. In particular, since the second water-based coating film is water-absorbing, the third solvent-based coating film is water-based. It plays a role in adjusting the water absorption of the paint film. Further, the cathodic protection reaction of the Zn—Al pseudo-alloy layer does not suddenly occur but is caused to react gradually, the cathodic protection effect is maintained for a long time, and the cathodic protection reaction product (reaction product of Zn) is coated with an aqueous paint. It is preferable that the coating film does not affect the film (swelling) and does not elute the cathodic protection reaction product to the outside.

The thickness of the solvent-based paint film layer is 5
It is preferably from 50 to 50 μm, more preferably from 10 to 30 μm. The solvent-based paint film layer is usually one layer, but may be a multilayer.

Specific examples of the solvent-based paint for forming the solvent-based paint film layer include phenolic resin paints (alcohol-soluble phenolic resin paints, oil-soluble phenolic resin paints, etc.), alkyd resin paints, aminoalkyd resin paints, and the like. Vinyl resin paint (vinyl chloride resin paint, styrene-butadiene resin paint, vinyl sol paint, etc.), chloride rubber paint, epoxy resin paint (epoxy / phenol resin paint, epoxy / amino resin paint, epoxy / alkyd / melamine resin paint, epoxy alkyd) Resin paint, epoxy ester paint, amine cured epoxy paint, epoxy coal tar paint, epoxy isocyanate paint, etc., acrylic resin paint (thermoplastic acrylic paint,
Thermosetting acrylic resin paint, etc., unsaturated polyester resin paint, urethane resin paint (oil-modified polyurethane paint, moisture-curable polyurethane resin paint, block-type polyurethane resin paint, polyol-curable polyurethane resin paint, urethane resin UV curable paint Etc.), silicon resin paints, fluororesin paints (solvent-based dispersion paints, modified fluororesin paints, organosol paints, solution paints, etc.), but are not limited to these. These may be used alone or as a mixture of two or more.

As described above, when the Al content is 15% on the iron tube,
A Zn—Al pseudo alloy layer having a thickness of 10 to 100 μm, more preferably 10 to 60 μm, and a water absorption of 5 to 50%, further 10 to 40%. %, In particular, 12 to 30% of a water-based paint film layer having a thickness of 50 to 300 μm, furthermore 60 to 100 μm.
Finally, a solvent-based coating film layer having a water absorption of preferably 4% or less has a thickness of 5 to 50 μm, more preferably 1 to 50 μm.
By providing so as to be 0 to 30 μm, Zn-A
(1) The cathodic protection effect (throwing power) of the pseudo alloy layer can be improved.

Next, an example of a method for producing the anticorrosion-coated iron pipe of the present invention will be described.

After the outer surface of the iron tube is shot blasted, arc spraying of Zn and Al is performed at the same time.
Forming an Al pseudoalloy layer; The conditions at the time of arc spraying may be ordinary conditions.

As a method of forming a water-based paint film layer on the iron tube on which the Zn-Al pseudo-alloy layer is formed, the water-based paint may be applied as it is and dried.
It is heated to about ℃ and water-based paint is applied to it by spray coating, brush coating, roll coating, etc.
This is preferable because the paint dries quickly, the adhesion between the surface of the iron pipe and the paint becomes good, and a uniform coating film that is elastic and sharp is formed.

In applying the water-based paint, various additives may be added in order to impart coating suitability according to the difference in the coating method, if necessary.
For example, viscosity modifiers, pigments, colloid stabilizers, dispersants,
Wetting agent, pigment settling inhibitor, defoamer, disaster prevention agent, film-forming aid,
A leveling agent, an anti-sagging agent and the like may be appropriately compounded.

Specific examples of the viscosity modifier include, for example, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, polyvinylpyrrolidone, ammonia casein, polyvinyl alcohol, alkali-soluble polyacrylate, polyacrylate, polyacrylamide, and the like. Water-soluble polymers such as polyethylene oxide.

Specific examples of the pigment include rust preventive pigments such as zinc chromate and strontium chromate, and extender pigments such as calcium carbonate, talc, clay and aluminum hydroxide.

If necessary, a precondensation of a water-soluble or water-dispersible thermosetting resin such as methylol or an alkoxymethylated polyfunctional amino compound such as urea or melanin with formaldehyde or a formaldehyde-glyoxal mixture. For example, an aminoformalin resin represented by a product, an epoxy resin, a phenol resin, a xylene resin, and the like, and further, a tar emulsion, a pitch emulsion, an asphalt emulsion, and the like may be added for improving the coating film.

When the solvent-based paint is applied to the iron pipe on which the water-based paint film layer is formed, the water content of the water-based paint film layer is adjusted to 5%.
It is preferable to apply the composition after reducing the content to 50%. In this case as well, it is preferable to heat the iron tube to about 60 to 90 ° C. in advance.

In addition, when applying the solvent-based paint,
The types and specific examples of various additives used for giving coating suitability according to the difference in the coating method as required are the same as those in the case of the water-based paint, and therefore the description thereof is omitted. However, since the solvent-based paint film is the uppermost layer, as a pigment,
Coloring pigments such as carbon black and titanium dioxide can be used in addition to water-based paints.

[0035]

Next, the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to these examples.

The water-based paints and solvent-based paints used in the examples and comparative examples, and the water absorption of the coating films formed therefrom are summarized in Table 1.

[0037]

[Table 1]

Production Example 1 To 15 parts of butadiene (parts by weight, the same applies hereinafter), 20 parts of butyl acrylate, 60 parts of styrene and 5 parts of acrylic acid,
Kurimoto Coat WR (sulfosuccinate ester type reactive emulsifier, manufactured by Kurimoto Iron Works Ltd.) 0.5 part, tertiary dodecyl mercaptan 1.0 part, ethylenediaminetetraacetate 0.05 part, potassium persulfate 0. 1 part and 150 parts of ion-exchanged water were charged into a nitrogen-purged autoclave with stirring blades, the monomer mixture was continuously added, and polymerization was carried out at 60 ° C. until the polymerization rate became 98% or more. Unreacted monomers were removed by topping. Next, the pH was adjusted to 7.5 with ammonia to obtain a copolymer emulsion having a solid content of 40%. 2 parts (solid content) of stearyl stearate emulsion were blended with 100 parts (solid content) of the emulsion to prepare an acrylic emulsion paint (I). The water absorption of the coating film obtained from the acrylic emulsion paint (I) was 25%.

Example 1 and Comparative Example 1 Ductile iron pipe (70 mm × 150 mm × 7 mm thick)
Then, as a first underlayer, an acrylic emulsion paint (I) was sprayed with Zn or a pseudo-alloy of Zn-Al (Al content 25%, 130 g / m ² ) so that the dry film thickness became 60 μm. Then, an acrylic emulsion paint (II) or an acrylic resin paint (I) was applied to the third layer so that the dry film thickness became 20 μm, thereby producing an anticorrosion-coated iron pipe.

The properties of the obtained coating film were evaluated by the following methods. Table 2 shows the results.

(Throwing power) A sandblasted steel plate (70 mm x 150 mm x 1.5 mm thick) is masked with a triangle (an isosceles triangle having a base length of 1/2 inch (about 12.7 mm) and a height of 150 mm). After that, a coating film was produced in the same manner as in Examples or Comparative Examples, and test pieces as shown in FIG. 1 were produced. In FIG. 1, reference numeral 1 denotes a coated surface, and 2 denotes a non-coated surface.

The obtained test piece was immersed in a 3% saline solution for 6 months, and it was examined how many mm from the bottom of the uncoated triangle rusted (SS rusting by SSPC method, see FIG. 2). . In addition, 3 in FIG. 2 indicates a rusted portion, and the height of the rusted portion is indicated by X mm. Evaluation was made from the height of the rusted portion according to the following criteria.

◎: Especially effective when less than 5 mm ○: Effective when 6 to 75 mm ×: Rust on the entire surface

(State of coating film) In the evaluation of the throwing power, the coating film surface was visually observed 2, 3, 5 and 6 months after immersion in 3% saline, and evaluated according to the following criteria.

Good: 8F or more according to ASTM D-714-56 method A. Swelling: 8M to 4M according to ASTM D-714-56 method A. Full swelling: ASTM D-714-56 method A. 6MD ~ 2D

Examples 2 to 5 and Comparative Examples 2 to 7 Ductile iron pipe (70 mm × 150 mm × 7 mm thickness)
First, a Zn-Al pseudo alloy spray (Al
Content of 25%, 130 g / m ² ), and as the second layer, an acrylic emulsion paint (I) and an epoxy resin emulsion paint (I) as water-based paints, an acrylic resin paint (II) as a solvent-based paint, and an epoxy resin The coating material (I) was applied so that the dry film thickness became 60 μm. An acrylic emulsion paint (I) and an epoxy resin emulsion paint (I) as a water-based paint and an acrylic resin paint (II) and an epoxy resin paint (I) as a solvent-based paint in the third layer so that the dry film thickness becomes 20 μm. An anticorrosion-coated iron tube having the anticorrosion coating layer shown in Table 2 was obtained by coating and evaluated in the same manner as in Example 1. Table 2 shows the results.

[0047]

[Table 2]

[0048]

The iron pipe having the anticorrosion coating according to the present invention is provided with a Zn-Al pseudo alloy layer having a good throwing power on the iron pipe, a water-based paint film layer having a moderate water absorption,
In addition, since it has a solvent-based coating film layer with low water absorption and good adhesion of the coating film and good toughness, it works as a strong coating if the anticorrosion coating layer is not damaged, and the anticorrosion coating layer is scratched In such a case, the good throwing power of the Zn-Al pseudo-alloy layer and the potential difference between the damaged part and the healthy part due to the water-based paint film layer that has absorbed water become small, and pitting corrosion hardly occurs. .

[Brief description of the drawings]

FIG. 1 is an explanatory view of a test piece used for an anticorrosion performance test by an SSPC method performed in an example of the present invention.

FIG. 2 is a diagram illustrating a method of examining a rusting state by an SSPC method using the test piece shown in FIG.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 5/08 C09D 5/08 133/06 133/06 163/00 163/00 167/00 167/00 175/04 175/04 C23C 4/08 C23C 4/08

Claims (10)

[Claims] 1. An iron tube having a Zn—Al pseudo alloy layer having an Al content of 15 to 50% by weight, a water-based coating layer having a water absorption of 5 to 50% by weight, and a solvent-based coating layer. An anticorrosion coating method for an iron pipe, which is provided. 2. The anticorrosion coating method according to claim 1, wherein the Zn-Al pseudo alloy layer has an Al content of 20 to 40% by weight. 3. The water-based paint film layer having a water absorption of 10 to 4
The anticorrosion coating method according to claim 1, wherein the amount is 0% by weight. 4. The anticorrosion coating method according to claim 1, wherein the water-based paint film layer is a paint film layer made of an acrylic emulsion paint. 5. The anticorrosion coating method according to claim 1, wherein the solvent-based paint film layer is a paint film layer made of an epoxy resin paint, a urethane resin paint, an acrylic resin paint, or a phthalic acid resin paint. 6. An iron-tube having a Zn—Al pseudo alloy layer having an Al content of 15 to 50% by weight, a water-based coating layer having a water absorption of 5 to 50% by weight, and a solvent-based coating layer. An anticorrosion coated iron tube provided. 7. The anticorrosion coated iron pipe according to claim 6, wherein the Al content in the Zn—Al pseudo alloy layer is 20 to 40% by weight. 8. The water-based paint film layer having a water absorption of 10 to 4
The anticorrosion-coated iron pipe according to claim 6, which is 0% by weight. 9. The anticorrosion coated iron pipe according to claim 6, wherein the water-based paint film layer is a paint film layer made of an acrylic emulsion paint. 10. The anticorrosion coated iron pipe according to claim 6, wherein the solvent-based paint film layer is a paint film layer made of an epoxy resin paint, a urethane resin paint, an acrylic resin paint or a phthalic acid resin paint.