KR101009024B1 - Paint composition For Coated Steel With Superior Corrosion Resistance and stabilities - Google Patents

Abstract

The present invention relates to a weatherproof steel coating composition for weathering steel and weathering steel to which the coating composition is applied, and more particularly, by using a low-viscosity resin solution and a low volatility solvent, storage performance is short within two months when stored outside. It is easy to use because there is no change of paint even if it is stored for more than 6 months, and it is possible to form a solid anti-rust layer early by coating only one layer even under strict corrosion environment, and provides paint composition with excellent workability and economic efficiency. It can be used for weather resistant steel used in steel bridges, interior and exterior materials, protective fences, etc.

Weather resistant steel, antirust coating, paint, corrosion resistance, storage resistance, low viscosity,

Description

Paint composition For Coated Steel With Superior Corrosion Resistance and stabilities}

The present invention forms a stable oxide film by applying only one time to weathering steel used for various steel bridges, building interior and exterior materials, protective fences, etc. will be.

In general steel structures, weather resistant steels, which do not require anticorrosive techniques, are attracting much attention in order to reduce high maintenance costs required for corrosion prevention such as paint coating and metal plating. Weather-resistant steel is made by adding a small amount of alloying elements such as chromium, copper, and nickel to the general steel composition. Even when exposed to the air without any anticorrosive treatment, a dense amorphous oxide film is formed on the steel surface, and the oxide film layer formed further prevents corrosion. Corrosion-resistant steel designed to act as a protective barrier. Therefore, weather resistant steel is used as a non-painting without corrosion treatment has the advantage of reducing a lot of maintenance costs.

Currently, when using weather resistant steel, anticorrosive techniques are classified into three types: no treatment (no coating without anticorrosive treatment), antirust coating paint for weathering steel, and general paint coating, but most of them are untreated and antirust coating coating. The process of forming a stable oxide film on unpainted weathering steel is a) the initial stage of corrosion progress and the same degree of corrosion as general steel (1-2 years), b) dense stable oxide layer due to the action of chromium, copper, nickel, etc. Intermediate stage (3-5 years), and c) stable, dark brown oxide film layer consisting of elements such as chromium, copper and nickel, with little corrosion progress (5-10 years). It consists of. However, such weather-resistant steel is exposed to the atmosphere as a non-painting to form a stable oxide film layer for a long time, the iron oxide is leaked out to cry out the appearance, there is a problem that it is difficult to form a stable oxide film under certain environmental conditions.

When anti-corrosion coating paint for weathering steel is used, it suppresses the generation of effluent iron oxides such as dark brown green water and powder that occur in the early stage of exposure when using unpainted weathering steel, forms a stable oxide film layer on the surface of weathering steel, and the coating itself is gradually weathered. It is a required function of rust preventive coating material to be separated and to be used permanently without repainting. The requirements of the rust preventive film to form a stable oxide film in weathering steel are as follows.

The stable oxide film is a hard and dense oxide layer in which the surface of weathering steel is oxidized and the alloying elements contained in the steel are concentrated. Therefore, in order to obtain a stable oxide film, the rust-proof coating layer must permeate oxygen and moisture from the surrounding air layer properly. Metal salt components that can promote stable film formation should be able to perform sufficiently to form stable film early. In addition, in order to obtain a stable stable oxide film layer, corrosive ion barriers such as chlorine and sulfurous acid gas should be blocked, and a stable film-forming rust preventive pigment should be added inside the coating film. The color of the stable oxide film of the weathering steel dark brown and the color of the paint should be similar so as not to harm the aesthetic appearance. The present invention relates to a rust preventive coating-forming coating composition that enables stable oxide film formation on the surface of weathering steel and prevents the outflow of iron oxide and secures external design of the weathering steel structure.

Conventional antirust coating film for weathering steel is mainly composed of two- or three-ply coating method in order to paint different kinds of paints in order. For example, after phosphate treatment with sewerage, each of the different middle and top coats is applied. It is known to control the permeability of water and oxygen in the upper coat, and to prevent the flow of rust in the middle and the phosphate treatment to help form a dense stable oxide film layer. However, especially in the sea salt particle scattering environment, there is a problem that a stable oxide film layer is not formed even after a long period of time when the amount of fly salt is large. In addition, if the amount of protective molten arsenate is somewhat high, the function of protecting the steel is deteriorated, and the upper limit of the amount of arsenic acid salt for protecting the steel shows an extremely low value.

In connection with the above problem, Japanese Patent Laid-Open No. 1-124088 proposes to solve by a surface treatment method for forming a phosphate film. However, in the case of the above-described method, the contents of the treatment are complicated, such as the need for appropriate pretreatment before forming the phosphate film, and if the welding of steel is required, the treatment in the weld is not easy. There are problems such as difficulty in application to structures and the like.

Japanese Patent Application No. 53-22530 proposes a method of forming protective rust while suppressing initial corrosion by resin coating. However, this method has a problem that not only the suppression of the initial corrosion is insufficient in a corrosive environment, but also the generation of protective rust is slow.

Japanese Patent Laid-Open No. 56-33911 and Korean Patent Laid-Open No. 1997-0034292 propose a method by two-layer coating. In this method, the initial corrosion can be suppressed, but since the corrosion resistance is too high, it takes too long to form a protective rust, and there is a problem in that the workability is poor because it is composed of two layers.

Korean Patent Laid-Open Publication No. 2002-0038890 discloses a coating material for coating steel having excellent corrosion resistance and a method for manufacturing coated steel using the same, which not only can form a solid corrosion layer at an early stage even under a strict corrosion environment, but also have excellent workability and economical surface treatment. However, due to the high viscosity of the resin and the high volatility of the organic solvent among the paint components, it is usually 6 months, which is the storage period of the paint. Occurs when the paint storage is bad.

Therefore, it is necessary to form an excellent stable oxide film and to exhibit the original characteristics without changing the paint even during long-term external storage, and to use the anti-corrosive coating paint for weatherability steel having excellent storage properties.

The present invention improves the short performance of the existing stable film coating method within 2 months of storage time when stored outside, and there is no change of paint even when stored for 6 months or more, and it is easy to use even in strict corrosion environment. The present invention provides a coating composition for weathering steel having excellent external storage property, which can not only form a solid antirust layer but also perform surface treatment with excellent workability and economic efficiency.

Another object of the present invention is to provide a weatherproof steel coated with an anti-corrosion coating material that is easy to use because there is no change in the paint even during storage, and can form a solid antirust layer by coating only one layer even in a strict corrosion environment. .

The present invention to solve the above problems,

0.1 to 2 parts by weight of calcium nitrate, and 1.8 to 3.6 parts by weight of a metal sulfate, and a stable oxide layer formation accelerator for at least one weathering steel surface selected from the group consisting of

50-70 parts by weight of a butyral resin solution having a viscosity of 10-30 cps,

6-9 parts by weight of xylene, and

It is related with the antirust coating film composition for weathering steel containing 10-15 weight part of high density alcohols.

The weathering steel anti-corrosion coating composition relates to a weatherproof steel anti-corrosion coating composition further comprises one or more additives selected from the group consisting of pigmented pigments, extender pigments, rust preventive pigments, dispersants, and antioxidants.

The present invention also relates to a weathering steel coated on the surface of weathering steel such that the rust-proof coating material for weathering steel becomes 1 µm to 200 µm on a dry film thickness basis.

Hereinafter will be described in detail of the present invention.

Calcium nitrate dissociates calcium nitrate present in the coated film into nitrate ions and calcium ions when moisture is supplied to the coated steel surface in a corrosive environment. The calcium ions thus produced are simultaneously reacted with sulfate ions formed by dissociation of metal sulfates added to the coating film to form calcium sulfate, which is poorly soluble in water. This calcium sulphate provides a densification effect of the rust layer by filling the voids in the rust layer mainly composed of iron oxyhydroxide and iron oxide formed by the corrosion reaction. If the calcium nitrate is less than 0.1 parts by weight, there is no stable rust forming effect. If the calcium nitrate is more than 2 parts by weight, the coating film hardness is high after drying, thereby making the coating film brittle.

The metal sulfate contained in the coating composition of the present invention may be used one or a combination thereof selected from the group consisting of aluminum sulfate, nickel sulfate, cobalt sulfate, chromium sulfate, copper sulfate, and iron sulfate. Metal sulfate dissociates into metal ions and sulfate ions when water is supplied at room temperature. As described above, the dissociated sulfate ions react with the calcium ions to form calcium sulfate, which is poorly soluble in water, to fill the pores of the rust layer mainly composed of iron oxyhydroxide and iron oxide produced by the corrosion reaction of steel. Thereby, the density of a rust layer improves and corrosion resistance improves. If the amount of the metal sulfate is less than 1.8 parts by weight, the amount is less effective. When the amount of the metal sulfate exceeds 3.6 parts by weight, the dry water butyral resin becomes very vulnerable after drying. No effect is obtained.

The resin usable in the present invention has a great influence on the finished paint storage shelf life, and the resin liquid viscosity is preferably 10-30 cps. If the viscosity of the resin solution is less than 10 cps, it is too thin and the paintability and film thickness are not good.If it exceeds 30 cps, it is impossible to use the paint by gelling the paint due to the reaction of moisture, metal salt and resin in the air for a long time storage at room temperature. Become. Examples of the butyral resins usable in the present invention include polyvinyl butyral resins having a molecular weight satisfying the above viscosity conditions.

As the solvent, xylene having a concentration of 60 to 80 and a high density alcohol can be used based on the evaporation rate of 100 butyl acetate. The high density alcohol has a slower evaporation rate than the low density alcohol, and examples thereof include propylene glycol monomethyl ether (PM). If the evaporation rate is too fast, the paint dries too quickly during paint spraying, so there is a risk of peeling the coating. If it is too late, the paint dries too late, resulting in poor workability.

The present invention is to provide a weather-resistant steel, the rust-proof coating material is applied to the weathering steel surface with a dry film thickness of 1 ~ 200㎛.

In the present invention, the coating coating film serves to prevent the outflow of these substances due to rainfall and condensation until the effect is exerted by keeping calcium nitrate and metal sulfate on the steel surface, which are effective for the early formation of a high corrosion protection layer. Has In addition, the barrier effect of appropriately suppressing the permeation of the substance which accelerates the corrosion from the outside to the steel surface until the formation of the anticorrosive rust layer is one of the roles of the coating film.

In the present invention, when the dry film thickness of the coated coating film is thinner than 1 μm, the barrier effect is low, and the outflow of iron ions generated by corrosion of the steel can not be completely prevented, so that the outflow rust from which the rust flows out from the steel surface is generated. This is because the calcium nitrate and the sulfate component of the metal added at the same time are also leaked, and the effect of the active ingredient is not obtained. In addition, permeation of chlorine ions in the sea environment of the sea salt particle causes excessive corrosion and inhibits the solid corrosion protection layer. On the other hand, when the dry film thickness exceeds 200 µm, not only is it economically disadvantageous, but the corrosion barrier effect on the inner metal salt layer is too large, and it takes too long to form a solid antirust layer on the metal surface. Prior to the formation of the solid rust layer, the dry film thickness should be 200 µm or less, since if the film is dropped due to an impact or the like, significant corrosion may proceed from the portion without the effect of the organic resin film.

In the present invention, in addition to butyral resin, calcium nitrate, and sulfate metal, one or more known additives such as coloring pigments such as bengala, extender pigments such as silica, rust preventive pigments such as zinc chromate, dispersant and antioxidant You can include more. The anti-corrosive pigment may be added in the sense of anticorrosive control when used in a highly corrosive environment, but in the case of adding the anti-corrosive pigment, the addition amount is preferably less than 10 parts by weight so that the anticorrosive property is not too good.

In the present invention, the concentrations of calcium nitrate, sulfates of metals, phosphoric acid and other additives in the coating paints indicate the concentrations after dry solidification. Prior to coating, a suitable amount of solvent is adjusted to a viscosity suitable for the painting operation. The solvent or moisture is evaporated by natural drying after coating to form a coating film having a desired dry film thickness.

Coating coating of the present invention can be applied to all conventional coating methods, for example, can be applied regardless of the place because it can be coated by a common method such as air spray, airless spray or roller. In addition, it is economical because the effect is obtained by one painting work. Furthermore, since local painting is possible, it is possible to cope with after machining such as cutting and welding of steel in the field.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following examples are only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention to the following examples.

Examples 1 to 9 and Comparative Example 1: Preparation of Antirust Coating

Antiterra-U 0.5, Hispalon420-20 1.0, Halox SZP391 1.1, RIO S130 0.5, Bayferrox303T 2.6, TiO2 R960, 0.44, BaSO4 2.3 in the antirust coating composition were the same in Example 1-9 and Comparative Example 1 The components are shown in Table 1.

Specifically, a pigment and a dispersant flow inhibitor were mixed in the resin solution, dispersed for 20 minutes, and then prepared by supplementing the thinner by calculating the thinner ratio evaporated when remaining and dispersed. Comparative Example 1 was prepared in the same manner as in Example 1 except that PVB BL-1-20B (Aekyung Industrial Co., Ltd.) and IPA and toluene were used as solvents, and the viscosity of the prepared coating material was 500 cps. .

Indicate other components of antirust coating (unit: wt%) NiSO ₄ ㆍ H ₂ O Ca (NO ₃ ) ₂ ㆍ H ₂ O Al ₂ (SO ₄ ) ₂ PVB BL-1-20A PM Xylene Example 1 3.6 - - 66.5 13.6 8.46 Example 2 1.8 - - 66.5 13.6 8.86 Example 3 - 1.8 - 66.5 13.6 8.86 Example 4 - 0.9 - 66.5 13.6 8.86 Example 5 - 0.9 1.8 66.5 13.6 8.86 Example 6 - - 3.6 66.5 13.6 8.86 Example 7 - - 1.8 66.5 13.6 8.86 Example 8 1.8 0.9 - 66.5 13.6 8.86 Example 9 3.6 1.8 3.6 66.5 13.6 8.86 Comparative Example 1 3.6 1.8 3.6 PVB BL-1-20B IPA 1.36 Toluene 8.86

week)

1) PVB BL-1-20A: Resin liquid (Aekyung Industrial Co., Ltd.) consists of 48 wt% PM, 32 wt% xylene, and 20 wt% PVB BL-1 (polyvinyl butyral resin).

2) Antiterra-U: Dispersant

3) Hispalon420-20: sedimentation inhibitor

4) Halox SZP391: Phosphoric Acid-Al Antirust Pigment

5) RIO S130, Bayferrox303T, TiO ₂ R960: Body Pigment

Experimental Example 1: Paint Storage

The paint compositions prepared in Examples 1 to 9 and Comparative Example 1 were stored at room temperature for 60 days, and then the state of the paints was compared.

Storage Paintability Example 1 O One Example 2 O One Example 3 O One Example 4 O One Example 5 O One Example 6 O One Example 7 O One Example 8 O One Example 9 △ One Comparative Example 1 X 2

<Storability>

O: Excellent storage, no change in paint

(Triangle | delta): Storage stability Normally, a paint viscosity rises slightly

X: Poor storage, paint gel                     

<Paintability>

1: excellent paintability

2: poor paintability (surface cracking)

Experimental Example 2: Stable coating state test of weathering steel coated with paint

The coating compositions prepared in Examples 1 to 9 and Comparative Example 1 were removed by surface rust and coated with an air spray with a thickness of 20 microns on a weather resistant steel plate free of oil or other foreign matter. The test piece was subjected to an atmospheric exposure experiment at 20m of Pohang Wolpo coastal area between January and December 2002 (1 year), and the surface rust state was visually confirmed.

Surface rust condition Example 1  △ Example 2 △ Example 3 O Example 4 O Example 5 O Example 6 O Example 7 △ Example 8 O Example 9 O Comparative Example 1 O

week)

O: Surface dark red stable rust formation

△: forming surface red stable rust

Therefore, the antirust coating film for weatherability steel of the present invention having excellent storage properties is excellent in external storage property as in the above embodiment, and when the surface is coated on weatherable steel, a stable oxide layer is formed, and as a result, repainting and anticorrosion maintenance costs are greatly reduced when using weatherable steel. It can also be seen that it provides a useful effect.

The antirust coating composition for weathering steel according to the present invention is to be applied 2-3 layers by using 2-3 kinds of paints, or to improve the short performance of the storage period within 2 months when stored outside, even when stored for 6 months or more. It is easy to use because there is no change of materials, and even in strict corrosion environment, only one layer can be applied to form a solid antirust layer at an early stage, and it is excellent in workability and economical efficiency. Available to

Claims (5)

0.1 to 2 parts by weight of calcium nitrate, and 1.8 to 3.6 parts by weight of a metal sulfate, and a stable oxide layer formation accelerator on at least one weathering steel surface selected from the group consisting of: 50 to 70 parts by weight of a butyral resin having a viscosity of 10 to 30 cps, 6 to 9 parts by weight of xylene, and The antirust coating film composition for weathering steel containing 10-15 weight part of high density alcohols. The anti-corrosive coating composition for weathering steel according to claim 1, wherein the metal sulfate is at least one selected from the group consisting of aluminum sulfate, nickel sulfate, cobalt sulfate, chromium sulfate, copper sulfate, and iron sulfate. The anti-corrosion coating composition for weathering steel according to claim 1, wherein the high density alcohol is propylene glycol monomethyl ether. The anti-corrosion coating composition for weathering steel according to claim 1, further comprising at least one additive selected from the group consisting of colored pigments, extender pigments, rust preventive pigments, dispersants, and antioxidants. A weather resistant steel comprising a rustproof coating layer coated on the surface of the weathering steel so that the rustproof coating composition for weathering steel according to any one of claims 1 to 4 is 1 µm to 200 µm on a dry film thickness basis.