KR20110029291A - Anti-corrosion coating composition - Google Patents

Abstract

PURPOSE: An environment-friendly anti-corrosive coating composition is provided to ensure environment-friendly property since chrome which is a conventional environmental pollutant is not used. CONSTITUTION: An environment-friendly anti-corrosive coating composition comprises aluminum flake, zinc flake, silica-based inorganic binder, organic binder and metallic chelate compound. The added amount of the zinc flake is 30-35 weight% and the added amount of the aluminum flake 3-5 weight%. The added amount of the silica-based inorganic binder is 5-8 weight% and the added amount of the organic binder is 1-2 weight%.

Description

Anti-corrosion coating composition

The present invention relates to a coating composition for preventing rust, and more particularly to a coating composition for preventing rust.

For a long time, the surface of the steel structure was coated using a rust-preventive coating composition for the purpose of suppressing the corrosion of the steel structure, and mainly subjected to chromate (rust) coating treatment. Chromate rust-proof coating treatment is a coating of a thin film by putting a metal in a solution mainly composed of chromic acid or dichromate. This film serves to prevent oxidation.

Dacro® treatment is most commonly used as a chromate antirust coating treatment. In the dark process, a dark water solution composed of chromic acid, zinc and aluminum (Al) Flake phase metal powder, a reducing agent, and deionized water is applied to the surface of the ferrous metal to form a coating film. dried with hot air is a method of forming a coating film chromic anhydride _{(mCr 2 O 3 · nCrO 3} ). The darkening treatment method is described in Japanese Patent Laid-Open Nos. 11-286788, 2001-342575 and 2003-160878, and Domestic Patent No. 10-355173.

The above-mentioned chromate antirust coating treatment method has been used for a long time because of low cost and excellent corrosion resistance. However, since hexavalent chromium (Cr ^{+ 6} ), which is classified as a heavy metal, contains a fatal problem that it is harmful to the human body. Hexavalent chromium is known as a major carcinogen that causes laryngeal cancer, and its use is regulated internationally. Countries around the European Union (EU) regulate the use of Cr (VI) along with lead (Pb), cadmium (Cd) and mercury (Hg). Previously, manufacturing and process emissions were regulated, but recently, final product is also regulated. Therefore, development of the antirust coating composition which does not contain hexavalent chromium has been performed from various angles.

A method using a polymer resin as its representative method and chromium and fellow molybdenum anion (Molybdate, MoO ₄ ^{2 -)} a method using a coating method using silica, are acid salts (MH ₂ PO ₄₎ method using a film, tannic acid (Tannic Research has been conducted on a method of using an organic film such as acid). In recent years, many anti-corrosive agents have been developed for enhancing corrosion resistance by using zirconium and titanium compounds or silane coupling agents.

However, they have a large amount of adhesion compared to chromate coatings, are inferior in barrier property, self-healing, and insufficient in corrosion resistance, and thus are limited in practical use as a substitute for chromate in galvanized steel sheets.

The present invention is to improve the above-described problems, according to the present invention, in the coating composition for rust prevention, characterized in that it comprises aluminum flake (flake), zinc flake, silica-based inorganic binder, organic binder and metal chelate compound An antirust coating composition is provided. At this time, the addition amount of the zinc flake is 30 to 35% by weight, the addition amount of the aluminum flake is 3 to 5% by weight, the addition amount of the silica-based inorganic binder is 5 to 8% by weight, the addition amount of the organic binder is 1 It is preferable that it is to 2 weight%. The metal chelate compound is preferably added in an amount of 0.0001 to 5.0 parts by weight, and more preferably 0.03 to 0.05 parts by weight based on 100 parts by weight of the total amount of aluminum flakes and zinc flakes. In addition, the organic binder is preferably at least one organic binder selected from the group consisting of acrylic, epoxy and urethane organic binders.

According to another aspect of the present invention, the anticorrosive coating composition comprises an aluminum flake, zinc flake, a silica-based inorganic binder, an organic binder, and a chelating agent for forming a metal chelate compound and a chelating agent. An antirust coating composition is provided. The core metal is at least selected from the group consisting of beryllium (Be), boron (B), zinc (Zn), copper (Cu), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni) One metal is preferable, and the chelating agent is acetic acid, acetylacetone, oxalic acid, glycine, salicylic aldehyde, nitro salicylate ( nitro salicyl aldehyde), tannic acid (tannic acid), is preferably at least one species selected from the group consisting of amino acids (amino acid).

The anti-corrosive coating composition of the present invention is an anti-corrosive coating composition made by adding a silica-based inorganic binder, an organic binder, and a metal chelate compound without using chromium, which is a conventional environmental pollutant, and is environmentally friendly and easy to manufacture and work. .

Hereinafter, the present invention will be described in detail.

The present invention is an anticorrosive coating composition comprising aluminum flakes, zinc flakes, silica-based inorganic binders, organic binders and metal chelate compounds. The metal chelate compound may be added directly, but there is also a method of chelation by mixing the chelating agent with the central metal constituting the metal chelate compound.

Looking at the components constituting the anti-corrosion coating composition according to the present invention as described above are as follows.

Zinc flakes and aluminum flakes corrode before ferrous metals to prevent corrosion of ferrous metals. Since zinc flakes and aluminum flakes have a higher ionization tendency than iron, they act as an anode to form a kind of electric circuit, and eventually, the electrical action inhibits and protects iron from corrosion. This is called self-sacrificing protection.

Zinc flakes and aluminum flakes are prepared in the following manner. First, metal powder is produced by gas spraying, chemical reduction or electrolysis. Then, the metal powder is classified to select a powder having a constant particle size. The selected powder is charged into a ball mill with an additive for preventing steel balls and cold rolling, and then rotated at a high speed to draw and crush the powder to obtain flakes of a desired shape. Next, the powder thus obtained is charged again into a ball mill with fine balls so that the surface is polished without changing the particle size and shape.

The zinc flakes and the aluminum flakes preferably have an aspect ratio of 1: 8 to 1:12. This is because the adhesion strength of the coating layer is increased. It is preferable that the average thickness of zinc flake and aluminum flake is 0.1-0.3 micrometer, and average length is 0.6-1.0 micrometer. Zinc flakes and aluminum flakes are used to pass through 100 mesh.

Zinc flakes are preferably added at 30 to 35% by weight and aluminum flakes are added at 3 to 5% by weight. This is to maintain the best coating appearance.

Silica (SiO ₂ ) is an inorganic binder that serves to fix zinc flakes and aluminum flakes on the surface of the iron metal and to bond the metal flake particles to each other. In addition, silica inhibits chemical reactions between metal flakes and iron-based metals, which slows the progress of corrosion. In addition, silica forms a plurality of layers together with zinc flakes and aluminum flakes to protect the iron metal surface, thereby blocking the atmosphere such as moisture in the atmosphere.

Silica is preferably added at 5 to 8% by weight. If it is 5% by weight or less, the formation of the coating film is poor, and voids are formed between the metal flakes, so that moisture in the air can penetrate. If it is 8% by weight or more, the stability of the coating composition may be impaired.

The organic binder uses at least one organic binder selected from the group consisting of acrylic, epoxy and urethane. It is preferable to add 1 to 2 weight% of an organic binder. The organic binder serves to greatly improve the adhesion strength and the corrosion resistance of the coating composition for preventing rust.

The metal chelate compound serves to greatly improve the adhesion strength. The addition of a small amount of the metal chelate compound improves the adhesion strength by 20 to 60%. The metal chelate compound is preferably added 0.0001 to 5.0 parts by weight, more preferably 0.03 to 0.05 parts by weight based on 100 parts by weight of the aluminum flakes and zinc flakes. If the added amount is 0.0001 parts by weight or less, the effect of improving adhesion strength does not appear, and when 5.0 parts by weight or more, a problem occurs that the coating composition for rust prevention is gelled.

The core metal and the chelating agent may be added respectively without directly adding the metal chelate compound. The central metal is at least one metal selected from the group consisting of beryllium (Be), boron (B), zinc (Zn), copper (Cu), aluminum (Al), iron (Fe), cobalt (Co) and nickel (Ni). It is preferable that the chelating agent is acetic acid, acetylacetone, oxalic acid, glycine, salicylic aldehyde, nitro sallicyl aldehyde Preferably, at least one species selected from the group consisting of tannic acid and amino acid.

For dispersing zinc flakes, aluminum flakes and silica, 5 to 10 wt% of a dispersant, 1 to 2 wt% of a surfactant, and the like may be added. The remaining amount is a solvent, and deionized water is used as the solvent.

Substantially free of chromium in the coating composition for rust prevention of the present invention. "Substantially free of chromium" generally means that the concentration of chromium is less than about 0.001% by weight, based on the total weight of the composition. The present invention has the advantage of being environmentally friendly because chromium, which is an environmental pollutant, is not substantially present.

Next, a brief look at the method of producing a coating composition for rust prevention according to the present invention using the above components as follows.

First, a metal paste is prepared by mixing zinc flakes, aluminum flakes, metal chelate compounds, and dispersant dipropylene glycol (DPG) with deionized water. Next, a binder paste is prepared by mixing silica, organic binder, surfactant, and deionized water. Finally, the prepared metal paste and binder paste are mixed using a gun drill to prepare a coating composition for rust prevention. At this time, when viscosity control is required, a thickener may be added.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by Examples.

≪ Example 1 >

In the present embodiment, 35 g of zinc flakes, 5 g of aluminum flakes, 1 g of aluminum acetylacetonate, and 10 g of DPG are added to 20 g of deionized water, and the metal paste is prepared by stirring at a rotational speed of 120 RPM using a ball mill for about 3 hours. It was. Then, 8 g of silica, 1 g of epoxy, and 1 g of anionic surfactant (AEROSOL TR-70) were added to 19 g of deionized water, and stirred for about 3 hours at a rotational speed of 120 RPM using a ball mill to prepare a binder paste. Then, the prepared metal paste and the binder paste were mixed using a gun drill to prepare a coating composition for rust prevention.

<Example 2>

This Example was carried out except that 6 g of silica, 2 g of epoxy, and 2 g of nonionic surfactant (SYMPERONIC®) were added to 19 g of deionized water and stirred for about 3 hours at a rotational speed of 120 RPM using a ball mill to prepare a binder paste. Same as Example 1.

Comparative Example 1

This comparative example is the same as Example 1 except that no epoxy was added at the time of binder paste manufacture.

Comparative Example 2

This comparative example is the same as Example 1 except that aluminum acetyl acetonate was not added at the time of metal paste preparation.

Corrosion resistance, adhesion test and chromium content analysis were carried out using the coating compositions for rust prevention according to Examples 1 and 2 and Comparative Examples 1 and 2 in the following manner, and the results are shown in Table 1 below.

[Test sample production]

Samples for testing were prepared in the following order.

① Degreasing

      The oil on the surface of the iron metal was removed. TCE was used as a degreasing agent, and it was immersed at 60 degreeC for 5 minutes.

② Shot Blasting

      The scale or rust of the surface of the iron metal was removed by shot blasting. The shot ball used was 0.2 mm in diameter and the treatment time was 10 minutes.

③ Primary coating (DIP & SPIN)

      The anti-corrosive coating composition was coated in a dip and spin (DIP & SPIN) manner. The iron metal was deposited and then rotated four times while changing the rotational direction to coat a uniform film on the iron metal surface. The rotational speed was 238 RPM and the diameter of the immersion basket used was 1,000 mm.

④ 1st hardening

Drying and curing were performed for 50 minutes using a gas oven. Preheated at 100-200 degreeC for 15 minutes, it hardened for 25 minutes at 320-360 degreeC, and cooled for 10 minutes.

⑤ 2nd coating and hardening

      The secondary coating was carried out in the same manner as the primary coating, and the secondary curing was performed in the same manner as the primary curing to complete the sample preparation.

Corrosion Resistance Test

Salt Spray Test The corrosion resistance of the test specimens was tested according to KS D 9502.

Adhesion Test

The adhesion of the test specimens was tested according to KS M ISO 2409. This method evaluates the adhesion by measuring the degree of peeling of the coating film from the substrate when the coating film coated on the specimen was cut into a lattice pattern. The numerical grade for adhesion is from 0 to 5 grades, and the 0 grade has the best adhesion.

[Chrome Content Analysis]

The content of hexavalent chromium was confirmed by ISO 3113 (2002) qualitative analysis, and no hexavalent chromium was detected. In addition, it was determined as a negative result by the IEC 62321 Ed. 1 (UV / Vis) analysis method.

Corrosion resistance (salt spray test) Adhesion Chromium content Example 1 No red rust occurs up to 2000 hours 0: The cutting plane is intact. Nothing has fallen. voice Example 2 No red rust occurs up to 2000 hours 0: The cutting plane is intact. Nothing has fallen. voice Comparative Example 1 Red rust occurs after 648 hours 2: Peeling occurs in the middle or edge of the cut surface. Damage area is within 5 ~ 15%. voice Comparative Example 2 Red rust occurs after 960 hours 1: The middle of the cut surface falls into a small lump. Damage area within 5%. voice

Referring to Table 1, Examples 1 and 2 did not generate red rust until 1500 hours, and the cut surface was intact, but Comparative Examples 1 and 2 had red rust before 1000 hours, and peeling occurred, resulting in adhesion. It could be confirmed that the fall. Chromium was not detected in both Examples 1 and 2 and Comparative Examples 1 and 2.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications can be made by those skilled in the art within the technical idea of the present invention. Is obvious.

Claims (10)

In the coating composition for rust prevention, An rust coating composition comprising aluminum flake, zinc flake, silica-based inorganic binder, organic binder, and metal chelate compound. The method of claim 1, The addition amount of the zinc flake is 30 to 35% by weight, the addition amount of the aluminum flake is 3 to 5% by weight, the addition amount of the silica-based inorganic binder is 5 to 8% by weight, and the addition amount of the organic binder is 1 to 2 Anticorrosive coating composition, characterized in that the weight%. The method according to claim 1 or 2, The metal chelate compound, An anticorrosive coating composition comprising 0.0001 to 5.0 parts by weight based on 100 parts by weight of the aluminum flakes and the zinc flakes. The method according to claim 1 or 2, The metal chelate compound, An anticorrosive coating composition, comprising 0.03 to 0.05 parts by weight based on 100 parts by weight of the aluminum flakes and zinc flakes. The method of claim 1, The organic binder, Anticorrosive coating composition, characterized in that at least one organic binder selected from the group consisting of acrylic, epoxy and urethane organic binders. In the coating composition for rust prevention, An anti-corrosive coating composition comprising an aluminum flake, zinc flake, a silica-based inorganic binder, an organic binder, and a chelating agent for forming a metal chelate compound. The method of claim 6, The addition amount of the zinc flake is 30 to 35% by weight, the addition amount of the aluminum flake is 3 to 5% by weight, the addition amount of the silica-based inorganic binder is 5 to 8% by weight, and the addition amount of the organic binder is 1 to 2 Anticorrosive coating composition, characterized in that the weight%. The method of claim 6, The central metal is, At least one metal selected from the group consisting of beryllium (Be), boron (B), zinc (Zn), copper (Cu), aluminum (Al), iron (Fe), cobalt (Co), nickel (Ni) Anticorrosive coating composition. The method of claim 6, The chelating agent, Acetic acid, acetylacetone, oxalic acid, glycine, salicyl aldehyde, nitro sallicyl aldehyde, tannic acid, amino acid acid) at least one species selected from the group consisting of anti-corrosion coating composition, characterized in that. The method of claim 6, The organic binder, Anticorrosive coating composition, characterized in that at least one organic binder selected from the group consisting of acrylic, epoxy and urethane organic binders.