JP4895533B2 - Paint composition - Google Patents

Description

  The present invention relates to a coating composition. More specifically, the present invention relates to a further improvement in corrosion resistance when a zinc-based plated material is used outdoors, and partially embedded outdoors such as lighting columns, sign columns, or net fence poles. The present invention relates to a coating composition that further improves the corrosion resistance of zinc-based plating that improves the corrosion resistance of buried underground parts such as steel columns.

  The method of corrosion protection of steel by galvanization is a technique that has been implemented for a long time. However, there are cases where corrosion resistance is a problem with galvanization alone, and there are many cases where coating is applied on the galvanization to prevent corrosion. At this time, the adhesion between the galvanizing and the coating is not high, which may cause deterioration, and it is an important issue to improve the adhesion between the galvanizing and the painting. For example, Patent Document 1 defines a method for improving corrosion resistance by performing chromate treatment as a base treatment and further adding a metaphosphate compound or the like as an undercoat. Moreover, in patent document 2, after giving a chemical conversion treatment to the galvanized surface, what contains magnesium oxide as an undercoat is prescribed | regulated. Thus, in order to improve the corrosion resistance when coated on galvanizing, it has been considered that the technology of the base treatment and the technology of the undercoat are indispensable.

  In addition, lighting pillars and sign pillars are made of various materials, but those made of zinc-based plating are often used because of the balance between strength and price. These are often buried and used outdoors. Zinc-based plating is intended to shield steel from corrosion factors such as rain and wind or condensation, but it is known that corrosion is likely to occur immediately above the portion buried in the soil (Non-patent Document 1). In this case, as a method for suppressing corrosion, a method of providing anticorrosion layers above and below the buried portion interface is disclosed (Patent Document 3). This anti-corrosion means prevents corrosion caused by the cell effect directly above the part embedded in the concrete.

  Also, steel pillars installed in places where people walk, such as sidewalks and parks, are often marked with dogs, and it has been reported that corrosion due to this is a problem (Non-patent Document 2).

JP-A-7-171495 JP 9-38570 A JP 2002-371372 A JP 2000-144044 A Proceedings of the 47th Materials and Environmental Conference, 195 (2000) Proceedings of the 25th Japan Road Conference, 06011 (2003)

  The present invention improves the corrosion resistance of galvanized materials, which are frequently used, especially corrosion resistance in environments where it is difficult to maintain the corrosion resistance when bare, and prevents corrosion at the buried part when used in steel columns. An object of the present invention is to provide a coating composition capable of improving the corrosion resistance against corrosion caused by dog marking or the like.

  The inventors of the present invention have investigated in detail the relationship between the components of the paint adhered to the galvanizing and the adhesion, and further the relationship between the corrosion resistance. In addition, we investigated the actual corrosion of the galvanized steel columns due to urine components of dogs, especially the corrosion at the buried land, and examined them in detail in the laboratory. The acceleration phenomenon has been examined. As a result of various investigations, by adding a combination of a component that improves water resistance and a component that increases durability in an aqueous solution containing ammonium ions to the coating film, the above problems can be solved by the respective synergistic effects. It came. That is, the gist of the present invention is as follows.

(1) A coating composition applied to a zinc-based plating material, and (a) an epoxy resin having an epoxy equivalent of 180 to 1000 having two or more epoxy groups in one molecule as a main component of the coating; b) 100 parts by mass of the total amount of the amine-based curing agent component, (c) 30 parts by mass or more and less than 100 parts by mass of the oligomer component having a phenol group, and (d) 1 part by mass or more of the phosphoric acid-based rust preventive pigment. Oligomer containing less than 20 parts by weight and (e) 1 part by weight or more and less than 20 parts by weight of a dehydrating agent, wherein the amine-based curing agent component is adduct-modified metaxylenediamine and having the phenol group A coating composition, wherein the hydroxyl value of the component is more than 100 mgKOH / g and less than 200 mgKOH / g.

(2) The coating composition according to (1) above , wherein the total component of the oligomer having a phenol group is an aromatic or alicyclic oligomer having a coumarone structure and having a phenol group .

(3) The zinc-based plated material is a buried plating pole made of zinc-based plated steel, and is applied to the anticorrosion of the zinc-plated steel buried plating pole, (1) or The coating composition according to (2) .

  ADVANTAGE OF THE INVENTION According to this invention, the coating composition which can improve corrosion resistance is provided by combining and adding the component which improves water resistance, and the component which increases durability in the aqueous solution containing an ammonium ion. Therefore, by applying the coating composition according to the present invention on the zinc plating, a corrosion-resistant material having excellent durability can be produced, which is an effective improvement means when corrosion resistance is not ensured by the zinc plating.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  The coating composition according to the present invention comprises (a) an epoxy resin having two or more epoxy groups in one molecule as a main component of a coating material and an epoxy resin having an epoxy equivalent of 180 to 1000 and (b) a total amount of an amine curing agent component. 100 parts by weight, (c) 30 parts by weight or more and less than 100 parts by weight of the oligomer component having a phenol group, (d) 1 part by weight or more and less than 20 parts by weight of phosphoric acid rust preventive pigment, (e) dehydration It contains 1 part by mass or more and less than 20 parts by mass of the agent.

  The curing agent specified in the present invention means a chemical used for forming a film by causing a crosslinking reaction to an epoxy resin in order to give a function as a coating film. Further, the oligomer component defined in the present invention means an organic resin component having an average molecular weight of several hundreds or more, which is not directly involved in the crosslinking reaction between the epoxy resin and the curing agent. In addition to the resin component, the rust preventive pigment means solid inorganic particles that are added to improve the anticorrosion performance of the coating film. Means. The dehydrating agent is a component added for the purpose of preventing the reaction between water molecules in the coating film and the resin or rust-preventing pigment. Water molecules rather than the reaction between epoxy groups or functional groups of additives and water molecules. Means a component having a high affinity. Details of each component are shown below.

  Here, as the (a) epoxy resin, one having an epoxy equivalent of 180 to 1000 having two or more epoxy groups in one molecule capable of forming a crosslinked coating film is preferable. At this time, when the number of epoxy groups in one molecule is less than 2, the coating film does not increase in molecular weight, and it is difficult to obtain a sufficient coating film strength. If the epoxy equivalent is less than 180, it is difficult to make the resin structurally bisphenol-type epoxy resin having two or more functional groups, and if it is more than 1000, the curability at room temperature may be inferior or the strength of the coating film May be difficult.

As the curing agent, an amine compound that has a good cross-linking reaction with an epoxy resin at room temperature is optimal for anticorrosive coatings used throughout the year. However, when an amine compound is used alone, it tends to volatilize and easily cause skin damage. Therefore, it is common to use a modified product. Adduct modification generates hydroxyl groups during the reaction, so the paintability and reactivity are not impaired. As the amine compound, main Takishirenjiami down is excellent in curing properties when low temperature, and since the finished appearance is also good, which those adduct degeneration, Chisai of galvanized steel embedded plated pole It is the most effective curing agent for epoxy resin coatings used throughout the year for anticorrosion applications.

  In addition, the addition amount of the curing agent at the time of use is such that the blending ratio of (b) the NH group (active hydrogen) equivalent in the modified amine curing agent and (a) the epoxy equivalent in the main agent is 1 / 1.2-1. It is preferable to adjust the formulation so that the ratio is /1.8 (molar ratio). When the equivalent ratio is smaller than 1 / 1.2 and the proportion of NH group equivalent in the modified amine curing agent is increased, the crosslinking density is increased, and the coating film becomes brittle and hard. Will be reduced. Moreover, when the equivalent ratio is larger than 1 / 1.8 and the ratio of the epoxy equivalent in the main agent is increased, sufficient crosslinking cannot be obtained, and the adhesion between the coating film and the substrate is reduced. Become.

  Furthermore, there is no problem even if a solvent is added together with the above epoxy resin and curing agent for the workability at the time of painting. The solvent to be added is preferably an aromatic, alcohol or ketone solvent having a relatively low boiling point which hardly remains in the coating film after coating. Examples of the aromatic solvent include toluene and xylene. Examples of the alcohol solvent include ethanol, isopropanol, butanol, and isobutanol. Examples of the ketone solvent include methyl ethyl ketone and methyl isobutyl ketone. These mixed solvents can also be used. In addition, a silicon-based additive can be added to the epoxy resin for the purpose of improving defoaming properties and leveling properties. The addition amount is 0.1% by mass or more and less than 10% by mass with respect to the epoxy resin.

  Here, the oligomer component having a phenol group is, for example, a product obtained by reacting a C9-based material (styrene, indene, coumarone, etc.) with phenol, or a phenol-modified oligomer obtained by reacting xylene, toluene, etc. with phenol, and having a molecular weight. In which the number average molecular weight is 300 to 1200. If the molecular weight is less than 300, the oligomer component may diffuse from the coating during curing or use, bleed out to the surface, and the effect may not be exhibited. On the other hand, if the molecular weight is more than 1200, the oligomer component cannot move freely when the coating film is cured, and the reaction described later does not proceed well, so that the corrosion resistance may not be improved.

  Regarding the oligomer component, in Patent Document 4 described above, a phenol-modified hydrocarbon resin having a highly reactive phenolic hydroxyl group and having a hydroxyl value of 50 mgKOH / g to 100 mgKOH / g is an important component in the inventive paint. The phenol-modified hydrocarbon resin in the above range is used for the purpose of satisfying the adhesion to the galvanized surface and the compatibility with the epoxy resin.

  One embodiment of the present invention is characterized by containing an oligomer having a hydroxyl value of greater than 100 mgKOH / g, which is said to cause a problem in compatibility in Patent Document 4. The reason why the phenolic hydroxyl group in this range is preferable is that the phenolic hydroxyl group improves the compatibility with the epoxy resin and the amine resin and contributes to a characteristic complex formation reaction with the rust preventive pigment component.

  When the hydroxyl value is 100 mgKOH / g or less, the compatibility with the epoxy resin is lowered, and the amount of addition is limited, so that good coating film performance cannot be obtained. On the other hand, when the hydroxyl value is larger than 200 mgKOH / g, the water resistance tends to decrease, and application to soil environment is not preferable.

  Furthermore, inclusion of a coumarone structure in the oligomer component is more preferable in terms of improving water resistance.

  Involved in the oligomer component having a phenol group forming a complex with a phosphoric acid-based anti-corrosion pigment, improving the anti-rust ability and adhesion to the substrate, and maintaining the adhesion to the zinc surface for a long period of time. Yes. When the amount of the oligomer component having a phenol group is less than 30 parts by mass, the effect of improving rust prevention ability and adhesion to the substrate is not sufficiently exhibited. Performance, such as hardness and chemical resistance, decreases, and the effect decreases.

  Moreover, the phosphoric acid type anticorrosive pigment is a main component that causes a complex formation reaction with the OH component of the phenol group, and when it is contained in an amount of 1 part by mass or more, the effect is exhibited. However, if it is contained in an amount of 20 parts by mass or more, the mechanical strength when it becomes a coating film is lowered, and it becomes easy to peel off. From the viewpoint of adhesion, the phosphate anticorrosive pigment is more preferably 10 parts by mass or less.

  In addition, the dehydrating agent is an essential component for removing water contained in the paint that inhibits the reaction between the phosphoric acid-based anticorrosive pigment and the phenol group. Although it is necessary to change the amount of addition depending on the water content in the paint, if it is an epoxy resin, a curing agent component and an oligomer component prepared by a normal synthesis method, a sufficient dehydration reaction occurs when adding 1 part by mass or more, The effect of removing the contained water that inhibits the reaction between the phosphate group and the phenol group is obtained. On the other hand, if it is contained in an amount of 20 parts by mass or more, the dehydrating agent aggregates, forming a cluster-like lump when forming the coating film and deteriorating the coating film performance. From the viewpoint of coating film performance, the dehydrating agent is more preferably 10 parts by mass or less.

  Furthermore, in one embodiment of the present invention, it is desirable to specify that the curing agent component is an amine compound. As the curing agent component, a modified amine based on meta-xylenediamine is applicable. In order to satisfy the functions of the present invention when used for galvanized steel, general resins such as bisphenol A and bisphenol F can be used as the epoxy resin. In particular, an epoxy resin and an amine compound are mixed. By applying a new resin, the reaction of the amine component of the curing agent is accelerated in combination with a dehydrating agent, and the corrosion resistance on the galvanized surface is further improved. The mechanism of action is not clear, but the present inventors presume that the amide bond obtained by the reaction of the epoxy group and the amino group is more strongly adsorbed on the surface of the galvanizing.

  Furthermore, in one embodiment of the present invention, as described above, the total component of the oligomer having a phenol group is a phenol group having a coumarone structure and a hydroxyl value having a phenol group of more than 100 mgKOH / g and less than 200 mgKOH / g. It is preferably an aromatic or alicyclic oligomer having When such an aromatic or alicyclic oligomer is used as the oligomer component, the corrosion resistance is improved as a result. Although the action is not clear, the present inventors have improved the compatibility with the curing agent resin when the oligomer component is an aromatic or alicyclic oligomer, and the above OH component and phosphoric acid-based rust preventive pigment component It is believed that the complexation reaction of selenium increases and the corrosion resistance increases.

  The phosphoric acid-based anticorrosive pigment used in the present invention is not particularly defined as long as it can react with phenol groups in the paint by liberating phosphate, but it is inexpensive and is also inexpensive in the paint. It is preferable that it is easily dispersible and does not cause interaction with the dehydrating agent. As such pigments, for example, phosphoric acid, phosphorous acid, Mg salts of Ca, Zn, Al, or phosphomolybdate, or those containing two or more of these are used. it can.

  Further, the dehydrating agent used in the present invention is not particularly limited as long as it has good dispersibility in the paint and can sufficiently absorb the water inside the paint. Or it is desirable to contain two or more of these.

  Furthermore, the particle diameters of the phosphoric acid-based anticorrosive pigment and the dehydrating agent are preferably 1 μm or more and 10 μm or less from the viewpoint of dispersibility in the paint and ease of reaction.

  Furthermore, as the zinc-based plating in one embodiment of the present invention, a plating material by flux treatment defined in JIS-H8641 can be generally applied. Moreover, hot dip galvanized steel sheets and steel strips defined by JIS-G3302 and structures manufactured thereby, electrogalvanized steel sheets and steel strips specified by JIS-G3313, and structures manufactured thereby, Further, the same effect can be obtained in the galvanized steel pipe for water piping specified in JIS-G3442 and the structure produced thereby, and also in the alloy plating in which alloy components such as Al and Mg are added to zinc. In addition to zinc-based plating immediately after production, it can be used as it is, and even if the zinc layer on the surface is somewhat corroded, it is applicable when red rust does not occur.

  Furthermore, one embodiment of the present invention exhibits a sufficient effect when applied to the underground corrosion prevention of the buried plating pole. The buried plating pole mentioned here is a columnar structure whose core material is made of steel, and the general shape of the steel pipe is a tapered pole steel pipe, square pipe shape, column, The shape of steel is not particularly specified, and it may have a complicated shape in design.

  When applied to the buried plating pole, the coating composition of the present invention is applied to at least the buried portion of the ground. The range to be painted is not particularly specified, but is preferably 50 mm or more above and below the buried portion interface, and more preferably 300 mm or more. The coating film thickness is preferably 10 μm or more, and more preferably 50 μm or more. As the painting method, spraying, brushing, roller coating, etc. can be applied. In addition, if necessary, this paint can be applied and various top coats can be applied. Epoxy, acrylic, fluorine, urethane, polyester, etc. can be applied to the top coat. When painting, remove after removing dirt and deposits on the surface of the object. In order to further improve the adhesion, it is possible to grind the surface or perform an adhesion improvement treatment.

  Hereinafter, the present invention will be described in detail using examples.

Example 1
As the main agent,
A: Acrylic polyol resin (Dainippon Ink Co., Ltd., trade name ACRICID CU-1206)
B: Epoxy polyol resin (Asahi Denka Kogyo Co., Ltd., trade name Adeka Resin EP-6021, solid content 60%, hydroxyl group equivalent 450 g / equivalent)
C-1: Bisphenol A type epoxy resin having an epoxy equivalent of 184 to 194 (product name Epototo YD-128, manufactured by Toto Kasei Co., Ltd.)
C-2: Bisphenol A type epoxy resin having an epoxy equivalent of 875 to 975 (trade name Epototo YD-014, manufactured by Toto Kasei Co., Ltd.)
Was used.

As a curing agent,
D: Polyisocyanate resin (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Coronate L)
E: Adduct modified product based on meta-xylenediamine (manufactured by Air Products Japan Co., Ltd., trade name Sunmide CX-1170B)
Was used.

  The mixing ratio of the main agent and the curing agent was 1 / 1.6 (mass ratio). The following components were added with the total amount of the main agent and the curing agent being 100 parts by mass. As the solvent, 9 parts by mass, 4 parts by mass, and 5 parts by mass of toluene, xylene, and methyl ethyl ketone were added, respectively.

  First, 20 parts by mass of flat talc as an extender was added to each.

Next, as an oligomer component,
F: Phenol-modified oligomer (60 parts by weight of phenol, 70 parts by weight of styrene, 70 parts by weight of coumarone and 100 parts by weight of toluene are charged in a glass reactor, and 2 parts by weight of boron trifluoride diethyl ether complex is added as a reaction catalyst. Then, the reaction is carried out at 80 to 85 ° C. for about 2 hours. After completion of the reaction, 6 parts by mass of calcium hydroxide is added for neutralization, and after completion of the neutralization, the precipitate is filtered off, and the resin varnish is further reduced under reduced pressure. (Semi-solid resin having a hydroxyl value of 180 mgKOH / g and a number average molecular weight of 500, obtained by distilling off the solvent at
G: Phenol-modified xylene resin (number average molecular weight 1000, hydroxyl value 115 mgKOH / g, manufactured by Fudou Co., Ltd., trade name Nikanol HP-70)
H: Xylene resin (number average molecular weight 400, manufactured by Fudou Co., Ltd., trade name Nikanol L)
I: Cyclopentadiene resin (manufactured by Nippon Zeon Co., Ltd., trade name Quinton 1500)
J: Toluene resin (PTI Japan Co., Ltd., trade name Epogil L)
It was used.

  Here, F and G contain a phenol group, and H, I and J are oligomers which do not contain a phenol group. The average molecular weights of H, I, and J are each in the range of 400-800. A test paint composition was prepared by blending these resin components, rust preventive pigments and dehydrating agents with the components shown in Table 1. Some coating compositions gelled during mixing or did not proceed with curing, and these were not used in the test.

In addition, as rust prevention pigment,
K: Aluminum phosphomolybdate (manufactured by Kikuchi Color Co., Ltd., trade name: PM-300C)
L: Calcium phosphate (Kikuchi Color Co., Ltd., trade name CP-Z)
M: Aluminum tripolyphosphate (trade name K White G-105, manufactured by Teika Co., Ltd.)
N: Zinc phosphate (product name: ZP-DL, manufactured by Kikuchi Color Co., Ltd.)
It was used.

As a dehydrating agent,
O: Synthetic zeolite (Union Showa Co., Ltd., trade name Molecular Sieve 4A)
P: Anhydrous gypsum (made by Hayashi Kasei Co., Ltd.)
It was used.

These paints were applied to a steel plate plated with a hot rolled steel plate having a length of 150 mm, a width of 75 mm, and a thickness of 6 mm. The plating conditions were in accordance with JIS-H8641, and the average plating thickness was 580 g / m ² . As a pre-treatment for coating, the surface was ground with Magiclon manufactured by Sumitomo 3M Co., Ltd., and then the coating thickness was applied with a brush with a target of 100 μm. Cross-cut the test piece after painting with a cutter knife and immersed in a 3% NaCl aqueous solution at 40 ° C for 3 months, an NaOH immersion test immersed in an aqueous NaOH solution at pH 12.0 at room temperature, pH 12 at room temperature An NH ₄ OH immersion test in which the sample was immersed in 0.00 ammonia water for 1 month was performed, and the average coating film peeling length from the cross-cut portion was measured. The results are also shown in Table 1. In addition, the modifier in Table 1 means the above oligomer component.

  In Table 1 above, numbers 15 to 31 are examples according to an embodiment of the present invention, and numbers 1 to 14 are comparative examples.

  From Table 1 above, the peeling width is sufficiently small in the examples as compared with the comparative example, and the effect of the oligomer component and the effect of the aromatic or alicyclic oligomer clearly appear.

(Example 2)
SS400 steel component hot-rolled steel sheet is cut into length 150mm x width 75mm x thickness 3.2mm, and after hydrochloric acid pickling, nickel sulfate bath (nickel sulfate 30% by mass, boric acid 5% by mass, sodium sulfate 10% by mass bath) , 50 ° C., 20 A / dm ² ) with an adhesion amount of 0.5 g / m ² , and then immersed in the hot-dip Zn plating bath composition shown in Table 2 for 1 minute, then pulled up and 30 seconds later The plate was produced by immersing in warm water at 60 ° C.

  Select the coating composition No. 5 and No. 25 shown in Table 1 for each plated plate, grind the surface with Magiclon, and then apply it with a brush, aiming for a coating thickness of 100 μm. did. A crosscut was put into the test piece after coating with a cutter knife, and various immersion tests of Example 1 were performed in the same manner, and an average coating film peeling length from the crosscut portion was measured. In order to evaluate the corrosion resistance when coating the surface after corrosion, No. 48 test piece was degreased with acetone on the surface of the test piece manufactured under No. 32 plating condition, and the salt spray test equipment It was installed for 24 hours, and after removal, the white rust on the surface was removed by washing with water.

  In Table 2 above, numbers 40 to 48 are examples in one embodiment of the present invention, and numbers 32 to 39 are comparative examples.

Referring to Table 2 above, the coating composition according to one embodiment of the present invention has good corrosion resistance regardless of the components of the zinc-based plating, and particularly excellent corrosion resistance with 3% NaCl and NH ₄ OH. . It is also clear that the surface after corrosion is sufficiently durable.

(Example 3)
The test body shown in FIG. 1 was produced. The size of the test material 1 (steel column) is outer diameter 6.5 mmφ × length 200 mm × thickness 3.8 mm. The test material 1 was plated in the same manner as in Example 1. After selecting the paint No. 5 and No. 25 shown in Table 1 to a length of about 100 mm in the center of this steel pipe, and grinding the surface with Magiclon, the paint thickness was applied to each 100 μm with a brush (Figure 5 in 1). The steel pipe after painting is embedded in concrete 2 having a diameter of 100 mm so that the half of the longitudinal direction of 200 mm, that is, the painted part is half buried in the concrete, and further, a PVC frame 3 having a height of 20 mm is placed on the top of the concrete. This was filled with a filling material 4 for burying, which was a mixture of horticultural soil and humus.

  Two test materials were prepared for each paint, and 1% NaCl aqueous solution was sprayed once a day on one of them. The other specimen was sprayed once a day with an aqueous solution having almost the same components as the average dog urine shown in Table 3. In each of the above test materials, the corrosion state after 6 months was evaluated with the occurrence of corrosion and the presence or absence of pitting corrosion.

  As a result of the evaluation, in the specimen coated with No. 5 paint, the swelling of the coating film was intense in both solutions, and many sites where the galvanizing was corroded were observed, especially in the solution simulating dog urine. It was. On the other hand, in the test body to which the No. 25 coating was applied, no blistering was observed in both the salt water spray and the simulated urine liquid spray, and galvanizing corrosion did not occur. From this, it became clear that the coating composition which concerns on one Embodiment of this invention remarkably improves the durability of the embedding ground part at the time of coating on a zinc-based plated steel pipe column.

  By using the galvanized pillars coated with the paint according to the present invention as described above, the corrosion of the buried underground part and the corrosion caused by the marking of dogs, etc. can be solved, and the obstacle of passersby and traffic can be avoided. It is possible to avoid the falling of the pole. In addition, the life of the material is extended, the replacement period of the lighting pillars and the like can be extended, and the management costs for roads and parks can be reduced.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention is applicable to a coating composition that improves the corrosion resistance of a galvanized material.

Schematic diagram of test specimen for corrosion resistance evaluation at the underground part of galvanized steel pipe column

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zinc plating test material 2 Concrete 3 PVC frame 4 Embedding filler 5 Paint part

Claims (3)

A coating composition applied to a zinc-based plating material,
(A) 100 parts by mass of the total amount of epoxy resin having an epoxy equivalent of 180 to 1000 having two or more epoxy groups in one molecule and (b) an amine curing agent component as a main component of the coating;
(C) 30 parts by mass or more and less than 100 parts by mass of the oligomer component having a phenol group;
(D) 1 part by mass or more and less than 20 parts by mass of the phosphoric acid anticorrosive pigment;
(E) 1 to less than 20 parts by weight of the dehydrating agent;
Containing
The amine-based curing agent component is adduct-modified meta-xylenediamine;
A coating composition, wherein the oligomer component having a phenol group has a hydroxyl value of more than 100 mgKOH / g and less than 200 mgKOH / g.   2. The coating composition according to claim 1, wherein the total component of the oligomer having a phenol group is an aromatic or alicyclic oligomer having a coumarone structure and having a phenol group. The zinc-plated material is a galvanized steel embedded plating pole, characterized in that it is applied to the Chisai portion corrosion of the zinc-based plated steel embedded plating pole according to claim 1 or 2 Paint composition.