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Title:
PAINT COMPOSITION FOR PREVENTING CORROSION AND IMPROVING LONG-TERM DUABILITY OF IRON STRUCTURE AND PROCESS FOR FORMING AN ALUMINUM OXIDE COATING LAYER USING THE SAME
Document Type and Number:
WIPO Patent Application WO/2006/059872
Kind Code:
A1
Abstract:
Disclosed are a paint composition for preventing corrosion and improving long-term durability of iron structure; and a process for forming an aluminum oxide coating layer using the same. The process for forming an aluminum oxide coating layer of the present invention includes steps of (a) preparing a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and (b) uniformly dispersing the powder mixture prepared above into adhesive resin and spraying the dispersed mixture on a surface of the iron structure to form a coating layer. The process for forming an aluminum oxide coating layer of the present invention is an economical process capable of being simply constructed even at normal temperature, and therefore may be effectively used for preventing corrosion and improving long-term durability of iron structure by uniformly forming an aluminum oxide coating layer having excellent physical properties such as adhesion strength to surfaces of iron structures, elongation, flexibility, etc.

Inventors:
Han, Kyu-tech (112-401 Doosan Apt, 10 Seokgwan-don, Seongbuk-gu Seoul 136-150, KR)
Application Number:
PCT/KR2005/004073
Publication Date:
June 08, 2006
Filing Date:
November 30, 2005
Export Citation:
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Assignee:
SAMJU SMC CO., LTD. (Seogyo Bldg, Studioville 399-6, Seogyo-don, Mapo-gu Seoul 121-840, KR)
Han, Kyu-tech (112-401 Doosan Apt, 10 Seokgwan-don, Seongbuk-gu Seoul 136-150, KR)
International Classes:
C23C24/00; C09D5/10; C23C24/08; C23C26/00
Attorney, Agent or Firm:
Lee, Kwang-bok (4F. Byukcheon Bldg, 1597-5 Seocho-don, Seocho-gu Seoul 137-876, KR)
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Claims:
Claims
1. A paint composition for preventing corrosion and improving longterm durability of iron structure comprising: a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and an adhesive resin into which the powder mixture is uniformly dispersed.
2. The paint composition for preventing corrosion and improving longterm durab ility of iron structure according to claim 1, wherein the adhesive resin is polyurethane resin or epoxy resin.
3. A process for forming an aluminum oxide coating layer for preventing corrosion and improving longterm durability of iron structure, comprising: (a) preparing a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and (b) uniformly dispersing the powder mixture prepared above into adhesive resin and spraying the dispersed mixture on a surface of the iron structure to form a coating layer.
4. The process for forming an aluminum oxide coating layer for preventing corrosion and improving longterm durability of iron structure according to claim 3, wherein the coating layer has a thickness of 100 D or less on the basis of the layer coated once.
Description:
Description PAINT COMPOSITION FOR PREVENTING CORROSION AND

IMPROVING LONG-TERM DUABILITY OF IRON STRUCTURE AND PROCESS FOR FORMING AN ALUMINUM

OXIDE COATING LAYER USING THE SAME Technical Field

[1] The present invention relates to a paint composition for preventing corrosion and improving long-term durability of iron structure including iron; and a process for forming an aluminum oxide coating layer using the same, and more particularly to a paint composition capable of being simply constructed even at normal temperature and uniformly forming an anti-corrosive aluminum oxide coating layer having excellent physical properties; and a process for forming an aluminum oxide coating layer using the same. Background Art

[2] Generally, most of so-called iron structure including iron is exposed to the corrosive environment such as the air and so on, and therefore methods for anti-corrosively surface-treating the iron structure have been widely used for preventing its corrosion.

[3] For example, there have been developed methods for forming a coating layer on a surface of iron structure using paints such as epoxy -based paints, vinylester-based paints, fluororesin-based paints, acryl rubber-based paints, chlorinated rubber-based paints and so on. However, since the paints are organic paints, they have excellent initial performances, but significantly different deformation properties such as a thermal expansion coefficient, elongation, etc. when compared to iron. Accordingly, the organic paints have a problem that the formed coating layer is detached from iron structure since adhesion strength is decreased with the time. Especially, the epoxy- based paints have a problem that it is difficult to apply to the outdoor iron structure exposed to the light for a long time since resin itself is easily decolored by UV-light exposure, and the fluororesin-based paints have a problem that their durabilities are deteriorated due to their cracks by the reduced elasticities of rubber components.

[4] In order to solve the aforementioned problems of the organic paints, this applicant proposed a process for forming an aluminum oxide coating layer using a paint composition containing powder of a metal mixture mainly composed of aluminum powder (see Korean Patent Application No. 10-2002-21103). The paint composition containing powder of a metal mixture may be used for forming an anti-corrosive aluminum coating layer having excellent properties such as adhesion strength,

elongation and so on. However, there have been demands for paint compositions capable of forming an anti-corrosive aluminum coating layer which is more uniform and offers more durability. Disclosure of Invention

Technical Problem

[5] Accordingly, the present invention is designed to solve the problems of the prior art, and therefore it is an object of the present invention to provide a paint composition capable of being simply constructed even at normal temperature and effective for uniformly forming an anti-corrosive aluminum oxide coating layer having an excellent physical properties such as adhesion strength to a surfaces of iron structure, elongation, flexibility and so on to prevent corrosion of iron structure and improve its durability.

[6] It is another object of the present invention to provide a process for forming an aluminum oxide coating layer using the paint composition. Technical Solution

[7] In order to accomplish the one above object, the present invention provides a paint composition including a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and an adhesive resin into which the powder mixture is uniformly dispersed.

[8] In order to accomplish the other above object, the present invention provides a process for forming an aluminum oxide coating layer, including steps of (a) preparing a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and (b) uniformly dispersing the powder mixture prepared above into adhesive resin and spraying the dispersed mixture on a surface of the iron structure to form a coating layer.

[9] The coating layer of the metal mixture, formed by the process for forming an aluminum oxide coating layer, preferably has a thickness of 100 D or less on the basis of the layer coated once.

Brief Description of the Drawings

[10] Fig. 1 is a graph showing concentration of salt penetrated into a coating layer with the passage of time. Best Mode for Carrying Out the Invention

[11] Hereinafter, a paint composition for preventing corrosion and improving long-term durability of iron structure according to the present invention; and a process for

forming an aluminum oxide coating layer using the same will be described in detail.

[12] The paint composition of the present invention includes a powder mixture consisting of 0.2 to 0.5 % by weight of zinc (Zn) powder, 0.3 to 1.0 % by weight of chromium (Cr) powder, 0.5 to 1 % by weight of nickel (Ni) powder, 0.06 to 0.15 % by weight of phosphorus (P) powder and the balance of aluminum (Al) powder; and an adhesive resin into which the powder mixture is uniformly dispersed.

[13] As known in the art, aluminum, which is a major component of a powder mixture dispersed into adhesive resin, has a more excellent reactivity than iron, and therefore, prior to oxidation of the iron, it is preferentially oxidized to form an aluminum oxide (Al O ) coating layer. The aluminum oxide coating layer prevents iron structure from being in direct contact with outer environments, such as oxygen, capable of corroding the iron structure. If a suitable amount of zinc, chromium and nickel components is mixed with aluminum powder, it contributes to improve wear resistance and weather resistance of a coating layer.

[14] Especially, the powder mixture of the present invention includes 0.06 to 0.15 % by weight of phosphorus (P) powder, and the added phosphorus aids to uniformly disperse the aforementioned metal powder into adhesive resin, and also functions to improve uniformity and hardness of the aluminum oxide coating layer. The above context will be described in detail, as follows.

[15] If a powder mixture including phosphorus powder is dispersed into adhesive resin, the phosphorus is oxidized with moisture remaining in the adhesive resin to become phosphorus pentaoxide (P O ). The resultant phosphorus pentaoxide further absorbs moisture remaining in the adhesive resin to improve durability of the coating layer since it shows high hygroscopicity, and also it aids to uniformly disperse powder mixtures into adhesive resin since it shows a function as a surfactant. If the phosphorus pentaoxide was directly added into the powder mixture, it is undesirable due to a problem that, on the contrary, its physical properties are deteriorated because it absorbs even outside moisture when mixing with the adhesive resin. If content of the phosphorus is less than 0.06 % by weight, it is difficult to give the aforementioned functions, while if content of the phosphorus exceeds 0.15 % by weight, durability of the coating layer may be deteriorated.

[16] If a major component of silicon dioxide, namely quartz or silica powder, is further added, for example, in an amount of 0.1 to 0.5 % by weight into the powder mixture dispersed into the paint composition of the present invention, strengths, etc. of the formed coating layer may be improved.

[17] The powder mixture is mixed with suitable adhesive resin, uniformly dispersed, sprayed, and then coated to fix the above powder mixture to a surface of concrete structure. Such an adhesive resin may be used to adjust viscosity according to its ap-

plication method, but it is preferred to use a polyurethane resin or an epoxy resin having excellent adhesion and elasticity. Especially, the polyurethane resin has an excellent ability to repress penetration of chlorides and carbonic acid gases, as well as good properties such as chemical resistance, penetration resistance against moisture and oxygen, etc. A mixing ratio of the powder mixture and the adhesive resin preferably ranges from about 0.2:10 to 3:10, and the process may be very simply and economically constructed since the coated mixture may be naturally cured at room temperature under the atmosphere to form a coating layer. The formed coating layer of the metal mixture preferably has a thickness of 100 D or less on the basis of the layer coated once. If necessary, a more strengthened coating layer may be formed by laminating such a coating layer several times, or by alternating a coating layer formed by the composition containing a powder mixture according to the present invention; and a coating layer consisting of only an adhesive resin several times.

[18] As described above, the coating layer, formed by mixing the powder mixture and adhesive resin, has an improved ductility, and therefore gives durability corresponding to contraction and expansion of iron (it is referred to as including corrosive non-ferrous metal materials) structure. Also, the coating layer shows a superior protection ability on penetration of chloride ions, sulfurous acid gases, moisture, oxygen, etc. which are caused by corrosion of the iron structure. Mode for the Invention

[19] Hereinafter, preferred embodiments of the present invention will be described in detail referring to the accompanying drawing. However, it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention, but not intended to limit the scope of the invention. Preferred embodiments of the present invention will be provided to those skilled in the art from this detailed description for more detailed description of the present invention.

[20] Embodiment 1

[21] A powder mixture consisting of 0.3 % by weight of zinc powder, 0.5 % by weight of chromium powder, 0.7 % by weight of nickel powder, 0.1 % by weight of phosphorus powder and 97.8 % by weight of aluminum powder; and a polyurethane resin were mixed with each other in a mixing ratio of 1:10, sprayed and coated on a surface of a target material using a spraying process, and then kept at room temperature for a predetermined time to form an aluminum oxide coating layer having a thickness of 35 D according to the present invention.

[22] Comparative embodiment 1

[23] The composition, described in Korean Patent Application No. 10-2002-21103 filed by the same applicant as the present invention, was used in Comparative embodiment

1.

[24] A powder of a metal mixture consisting of 4.5 % by weight of manganese powder,

0.3 % by weight of zinc powder, 0.2 % by weight of chromium powder, 0.4 % by weight of lithium powder and 94.6 % by weight of aluminum powder; and a polyurethane resin were mixed with each other in a mixing ratio of 1:10, sprayed and coated on a surface of a target material using a spraying process, and then kept at room temperature for a predetermined time to form an aluminum oxide coating layer having a thickness of 35 D.

[25] Evaluation of ability to prevent damage from salt

[26] In order to confirm a penetration level of salt with the passage of time in the aluminum oxide coating layer formed according to the process of the present invention, a method described in Korean Patent Application No. 10-2002-21103 was used for convenience' sake. Diffusion cells were manufactured with an untreated test specimen made of general Portland cement concrete and test specimens in which the coating layers are formed according to the embodiment and the comparative embodiment so as to conduct salt penetration/diffusion tests on the diffusion cells. 10 V DC voltage was applied to each of the diffusion cells, and then salt concentration in the diffusion cells was measured according to the passage of time using a salt meter, and the results are shown in Fig. 1.

[27] For the untreated concrete, its salt concentration suddenly and linearly increases as the time goes by, as shown in Fig. 1. However, it was seen that the concrete having the coating layer formed according to Embodiment 1 had a very excellent ability to prevent penetration of salt. Meanwhile, it was revealed that the concrete having the coating layer formed according to Comparative embodiment 1 also had an excellent ability to prevent penetration of salt, but did not have the ability as excellent as the coating layer of the present invention.

[28] Measurement of Adhesion Strength of Coating Layer

[29] In order to confirm adhesion strength of the aluminum oxide coating layer formed according to the process of the present invention, a test was carried out, as follows.

[30] An adhesion strength of the aluminum oxide coating layer was measured using a method for applying tension with an adhesion tester according to KS F 4715-01 and JIS A 6910 standards, by forming on iron structure an aluminum oxide coating layer of Embodiment 1 according the above process, and then adhering the aluminum oxide coating layer to a steel material. It was revealed that the adhesion strength of the aluminum oxide coating layer was high at about 35 kgf/cm .

[31] Measurement of Elongation of Coating Layer

[32] In order to measure elongation of the aluminum oxide coating layer formed according to the process of the present invention, a test was conducted according to a

KS M 6518-96 test method. It was revealed that the aluminum oxide coating layer formed according to the process of the present invention had an elongation of 0.7 D, but it was cleaved if its elongation exceeds the said range, indicating that the aluminum oxide coating layer formed according to the process of the present invention had the suitable elongation.

[33] In addition to measurement of the physical properties as described above, flexibility, waterproof property, wear resistance, weather resistance, heat and cold resistance, chemical resistance and impact resistance of the aluminum oxide coating layer formed according to the process of the present invention were measured with a request to Korea Institute of Construction Materials. As a result, it was revealed that the aluminum oxide coating layer had sufficient physical properties. However, their detailed descriptions are omitted herein. Industrial Applicability

[34] As described above, the aluminum oxide coating layer, formed on the surface of iron structure with the paint composition of the present invention, may be effectively used for preventing the iron structure since it has excellent physical properties such as adhesion strength, elongation, flexibility and so on, as well as it is uniformly formed and also has an excellent durability.