KR100617911B1 - CoAl2O4 pigment containing colar coating agent for corrosion resistance and preparation method of thereof - Google Patents

Abstract

The present invention relates to a color coating agent containing a CoAl ₂ O ₄ pigment, and more particularly to a method for producing a corrosion-resistant color coating with alumina sol as a basic composition.

Cobalt Alumina, Pigment, Alumina Sol, Color Coating, Coating, Corrosion Resistance, Organic / Inorganic Coating

Description

Corrosion-resistant color coating agent containing cobalt alumina pigment and its manufacturing method {CoAl2O4 pigment containing colar coating agent for corrosion resistance and preparation method of             

1 is a diagram showing an XRD pattern of CoAl ₂ O ₄ / AlOOH sol aged at 100 ℃ for 0, 6, 12, 48 hours.

Figure 2 is a graph showing the viscosity over time of the AlOOH / GPS / CoAl ₂ O ₄ hybrid sol of the present invention.

Degree 3 is an atomic force micrograph of AlOOH / GPS hybrid coating and AlOOH / GPS / CoAl ₂ O ₄ hybrid coating from EGI.

FIG. 4 shows 0, 2, 5, and 10% by mass of CoAl ₂ O ₄ , respectively, after a salt spray test (SST) for 120 hours with 5% by mass sodium chloride solution. Containing Optical image of AlOOH / GPS / CoAl ₂ O ₄ coating.

Of Figure 5 is not coated, AlOOH / GPS, a 5 mass% CoAl ₂ O ₄ a AlOOH / GPS / CoAl ₂ O ₄ containing Measured in 3% sodium chloride solution potentiodynamic polarization curve.

The present invention relates to a corrosion-resistant color coating containing CoAl ₂ O ₄ nanoparticles and a method for producing the same. More specifically, by adding CoAl ₂ O ₄ nanoparticles and alkylsilane to the neutral alumina sol as a blue pigment, a very stable blue coating sol is prepared without additional mechanical milling process, and a specific corrosion inhibitor and aqueous solution are added to the sol. By preparing a coating agent by containing a certain amount of the polymer of the phase, the corrosion resistance of the coating agent was greatly improved by the effect of containing the CoAl ₂ O ₄ nanoparticles, the coated surface is homogeneous, no surface defects, and contains no Cr at all. Chromium-free corrosion-resistant color coating and a method for producing the same.

Corrosion caused enormous losses in the metals industry, and the annual loss from corrosion reached 3 to 5% of GNP, so much research has been conducted to prevent corrosion.

The surface coating of metal is performed for the purpose of satisfying various requirements, such as surface oxidation prevention, acid erosion prevention, lubricity, and weldability. In general, chromate treatment, phosphate treatment or zinc phosphate treatment is widely applied as an anti-whitening agent before coating of galvanized steel sheets. In the case of phosphate treatment, the corrosion resistance is weak, so the risk of corrosion is greater when used in applications where only one side is painted, such as automotive steel sheets for all products. Therefore, when the corrosion resistance of a galvanized steel sheet is considered, chromate treatment is mainly performed. However, chromate ions for chromate treatment contain highly toxic chromium ions and induce carcinogenic effects on the human body, and wastewater treatment of chromic acid solutions has a very bad effect on the environment. In addition, chromate-treated galvanized steel sheets also have a problem of eluting chromium ions when in use or discarded. In addition, the use of heavy metals, especially chromium, will be regulated worldwide, and countries around the world are developing so-called 'green steel' development processes with low environmental load.

As a method for preventing the corrosion of metals, a method of forming a corrosion-resistant film that prevents the entry of oxygen, water, various ions, etc., which are corrosion or corrosive substances, or electrochemical corrosion by artificial methods using the principle of a sacrificial electrode The method of preventing this from occurring has been applied. The most widely used anticorrosive coatings to prevent corrosion of metals include chemical plating, electroplating, hot dip coating, vacuum plating, thermal spraying, penetrating plating, and inorganic or organic coatings. Like the treatment, there is a so-called conversion coating method in which a protective film is formed on a metal surface by a chemical reaction.

On the other hand, many methods have been proposed as a method for developing a corrosion-resistant metal coating containing no chromium. First, a material that is being studied as a material capable of forming a passivation film by reacting with a metal layer on the metal surface by a method similar to chromium preventing metal corrosion on the metal surface is a salt including Ce, Mo, V and P. Or the method of coating the aqueous solution of a compound is mentioned. However, this material alone has a problem that the corrosion resistance is much shorter than that of chromate treatment, the raw material itself is expensive, and there is no effect on the environment when this material is eluted during the washing process after the metal surface treatment. Secondly, the field of much research for the prevention of metal corrosion is related to the manufacture of coating film which effectively blocks the corrosive or oxidizing material which reaches the surface of the known metal. This method can be broadly divided into a method of coating an organic film and a method of coating an inorganic film, and hybrid studies combining these characteristics are also underway. In addition, the United States Navy Research Center mixed zinc molybdate or zinc phosphate with polyurethane to produce corrosion by synergistic effects such as forming oxide layers on metal surfaces and coating layers to prevent corrosion. There was an attempt to develop an inhibitor. In addition, researches using plasma or conductive polymer materials are being conducted mainly in advanced foreign countries, and recently, a number of research papers and patents on siloxane-based ceramic coating (ceramer) coating technology have been published. And at the Technical University of Denmark, there is also reported a corrosion resistant coating combining molybdate and orthophosphoric acid called MolyPhos. The corrosion resistance of passivated galvanized steel sheet is equivalent to that of conventional chromate solution in low pH and outdoor exposure test, but corrosion resistance is poorly observed in salt spray test and is 7 times more economical than chromate solution. It has the disadvantage of being expensive.

Meanwhile, many non-chromic corrosion-resistant coatings using conductive polymers such as polyaniline have been reported, and alkoxysilanes, which can be classified as organic substances, have recently emerged as substitutes for chromates and phosphates. Alkoxysilane is represented by the chemical formula of R-Si (OR '), R is an organofunctional group such as vinyl, amino, epoxy, mercapto, and penetrates into the paint resin to increase adhesion, and OR' Is an alkoxy group, such as -OCH ₃ , -OC ₂ H ₅ , is hydrolyzed by water to form a hydroxyl group, and chemically reacts by condensation polymerization with the hydroxyl group of the metal base layer. The alkoxysilane has a very excellent effect in increasing the corrosion resistance and coating adhesion of the film, but is limited in industrial use because the price is several times higher than the chromate treatment.

On the other hand, the alumina sol as a base composition in the present invention refers to a state in which AlOOH having a boehmite structure is dispersed in water in the form of a colloid, and has a hydroxyl group on its surface, thereby chemically bonding with a compound having other functional groups. This is possible.

Alumina and its hydroxide are one of the typical refractory materials and can be used even at high temperatures of 1,000 ° C. or higher, and are very stable in oxidizing atmospheres, acids, and alkalis. Alumina sol is a form in which very fine alumina hydroxide of several hundred nm or less is simply dispersed in water, but has excellent adhesive ability to form a film as compared to general-purpose silica sol, and has good adhesion and binding property to a matrix. There are a number of known methods for producing such alumina sol. For example, the method of peptizing the precipitate which hydrolyzed aluminum isopropoxide [BE Yoldas, Am. Ceram. Soc. Bull., 54, 289 (1975), Japanese Patent Laid-Open No. 6-64919], a method of peptization of boehmite powder with acid [Japanese Patent Laid-Open No. 59-78925], from bauxite light A method of solvating aluminum hydroxide obtained by reacting NaAlO ₂ , an intermediate raw material produced by a Bayer process with an acid, and a method of hydrating metal aluminum powder to produce a stable sol [Japanese Patent Laid-Open No. 7-89717] However, the coating property is bad or opaque to damage the inherent color of the matrix, or the addition of corrosion inhibitors such as Ce, Mo, Zr or other polyvalent ions, so that the sol becomes unstable and gelling properties.

As described above, chromate treatment for imparting corrosion resistance of galvanized steel sheet is currently limited in use due to environmental problems, and requires a non-toxic alternative in the same manner as chromate-type apparatus, but Mo, W, Ti, Zr, Co Corrosion-resistant coating solutions composed of Ce, etc. are expensive and have poor corrosion protection properties. In addition, the polymer corrosion-resistant coating film has a problem that the surface strength is weak and the film is easily damaged and corroded. The alkoxy silane is effective in increasing the adhesion of the coating film, but the price is high, and when the thin coating is applied, the corrosion resistance is weak. There is a problem of secondary environmental pollution.

The inventors of the prior art related to the corrosion-resistant coating agent of alumina sol / GPS and water-soluble polymer, Korean Patent Application No. 2002-73616 (hereinafter referred to as "prior art 1"), Korean Patent Application No. "No. 2001" -66813 "(hereinafter referred to as" prior art 2 ") and Korean Patent Application No." 2003-75897 "(hereinafter referred to as" prior art 3 "), and the like have been disclosed.

According to the above-described prior arts 1 to 3, the alumina sol is stabilized with an aluminum salt so that the stability of the sol is very excellent even if polyvalent ions having corrosion inhibiting functions such as Ce, Mo, and Zr are added, and Ce is added thereto. Disclosed is a method of mixing an aqueous dispersion of an epoxy acrylate-based aqueous polymer which improves the flexibility of an alkylsilane which adds a certain amount of corrosion inhibitors such as, Mo, and Zr, and hybridizes with alumina sol particles to produce a dense coating film and the coating film. It was. As a result, it is possible to manufacture coating sol with improved corrosion resistance at low price, very low emission of volatile organics in aqueous solution, and reduce the number of processes by eliminating the second cleaning process in the conventional chromate process. It is economical and environmentally friendly because it does not contain any coating chromium. It has many advantages such as improved scratch-resistance and mechanical processability, and strong film formation at low temperatures below 120 ° C. Insufficient property is poor in corrosion resistance due to surface defects, there is a problem in providing color functionality.

Accordingly, the present inventors have tried to solve the above problems, as a result, AlOOH / GPS / CoAl ₂ O ₄ hybrid sol prepared by adding CoAl ₂ O ₄ nanoparticles and alkylsilane to the alumina sol, AlOOH / GPS / CoAl _The present invention was completed by containing a specific aqueous solution polymer and a molybdenum-containing corrosion inhibitor in a ₂ O ₄ hybrid sol.

Accordingly, an object of the present invention is to provide a hybrid sol manufacturing method for coating that can be used for aesthetic purposes because it has a very stable and transparent blue color without additional mechanical milling process, the surface roughness is smooth, surface defect-free CoAl ₂ To provide a homogeneous chromium-free corrosion-resistant color coating containing O ₄ nanoparticles and a method for producing the same.

According to the present invention, by adding CoAl ₂ O ₄ nanoparticles as a blue pigment during the alumina sol manufacturing process, a very stable blue coating sol is prepared without additional mechanical milling process, and a specific corrosion inhibitor and a polymer in aqueous solution are added to the sol. By preparing the coating agent by containing a certain content ratio, the corrosion resistance of the coating agent was greatly improved by the effect of the inclusion of CoAl ₂ O ₄ nanoparticles, the coated surface is homogeneous, no surface defects, and contains no Cr at all Corrosion-resistant color coating and a method for producing the same.

The present invention is a method for producing a corrosion-resistant color coating based on the alumina sol,

The first invention of the present invention,

a) dissolving aluminum chloride solution and CoAl ₂ O ₄ in deionized water, and then titrating the solution with strong sodium hydroxide solution under strong stirring to obtain a slurry of CoAl ₂ O ₄ / Al (OH) ₃ mixture;

b) Stirring, filtration and washing the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature to prepare a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake; And

c) The CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared in step b) was added dropwise to a peptizing agent in a sealed bottle and then aged at high temperature to prepare a CoAl ₂ O ₄ / alumina hybrid sol. It provides a method for producing a corrosion-resistant color coating having a; and to provide a corrosion-resistant color coating prepared by the above production method.

The second invention of the present invention,

a) dissolving aluminum chloride solution and CoAl ₂ O ₄ in deionized water, and then titrating the solution with strong sodium hydroxide solution under strong stirring to obtain a slurry of CoAl ₂ O ₄ / Al (OH) ₃ mixture;

b) Stirring, filtration and washing the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature to prepare a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake;

c) The CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared in step b) was added dropwise to a peptizing agent in a sealed bottle and aged at high temperature to give CoAl ₂ O ₄ / alumina hybrid sol. Manufacturing step;

d) adding an alkylsiloxane to the CoAl ₂ O ₄ / alumina hybrid sol to produce a CoAl ₂ O ₄ / alumina / alkylsiloxane hybrid sol; It is to provide a method for producing a corrosion-resistant color coating, characterized in that it has a corrosion-resistant color coating prepared by the above production method.

The third invention of the present invention,

a) dissolving aluminum chloride solution and CoAl ₂ O ₄ in deionized water, and then titrating the solution with strong sodium hydroxide solution under strong stirring to obtain a slurry of CoAl ₂ O ₄ / Al (OH) ₃ mixture;

b) Stirring, filtration and washing the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature to prepare a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake;

c) The CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared in step b) was added dropwise to a peptizing agent in a sealed bottle and then aged at high temperature to prepare a CoAl ₂ O ₄ / alumina hybrid sol. Doing;

d) adding an alkylsiloxane to the CoAl ₂ O ₄ / alumina hybrid sol to produce a CoAl ₂ O ₄ / alumina / alkylsiloxane hybrid sol;

e) preparing a coating agent by adding a water-soluble polymer and a corrosion inhibitor to the CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol of step d);

It is to provide a method for producing a corrosion-resistant color coating, characterized in that it has a corrosion-resistant color coating prepared by the above production method.

Hereinafter, the present invention will be described in more detail.

In the manufacturing step of the present invention, first, in the process of preparing a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake, the aluminum chloride solution and CoAl ₂ O ₄ dissolved in deionized water, and sodium hydroxide is generally 10 Prepared by dropwise addition under the conditions of vigorous stirring in a weight% solution to obtain a CoAl ₂ O ₄ / Al (OH) ₃ mixture slurry, and the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature for 10 minutes to 5 hours. After stirring, the mixture was filtered and washed with water to prepare a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake. If the concentration of sodium hydroxide is too high, the cake of the mixture slurry is formed early and difficult to distribute evenly, which adversely affects the final product, and if too low, the amount of solution added is difficult to work.

In the above process, especially when the sol is prepared by adding CoAl ₂ O ₄ nanoparticles to the aluminum chloride solution and then preparing a sol by adding a peptizing agent, the sol state becomes very stable for a long time, but the sol is made of an aluminum chloride solution. After CoAl ₂ O ₄ nanoparticles were simply mixed in the alumina sol, even in the case of ball milling by mechanical method, precipitates were generated, resulting in very low storage stability of the sol. Therefore, it can be seen that the preparation after adding the aluminum chloride solution and CoAl ₂ O ₄ nanoparticles together in the preparation of the cake as in the present invention is a very important factor for the stability of the sol.

That is, the sol prepared in step c), which is a process for preparing CoAl ₂ O ₄ / alumina hybrid sol, is prepared by dispersing the sol of step c) by pre-dispersing the inorganic pigment CoAl ₂ O ₄ in the aluminum hydroxide raw material solution. When prepared, the dispersion stability of CoAl ₂ O ₄ nanoparticles is greatly increased. In detail, the CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared after dispersing CoAl ₂ O ₄ nanoparticles in the aluminum chloride solution in step a) and titrating with an alkali solution is preferred at 50 to 150 ° C. Preferably, a homogeneous clear blue sol was prepared without producing precipitate when aged at 80 to 120 ° C. for 6 to 100 hours, preferably 20 to 60 hours, more preferably 30 to 50 hours. CoAl ₂ O ₄ / Al (OH) _3, prepared by dispersing CoAl ₂ O ₄ particles and precipitating them together prior to the manufacture of aluminum hydroxide, was deposited on the surface of the negatively charged CoAl ₂ O ₄ nanoparticles [AlO ₄ Al ₁₂ (OH) ₂₄ (OH ₂ ) ₁₂ ] ⁷⁺ , [Al ₃ (OH) ₄ (OH ₂ ) ₉ ] ⁵⁺ and It is stabilized by adsorption of aluminum polyvalent ions such as [Al ₂ (OH) ₂ (OH ₂ ) ₄ ] ⁴⁺ . I.e. dispersion and stability of CoAl ₂ O ₄ nano-particles in the alumina sol is due to the CoAl ₂ O ₄ electrostatic effect between the alumina particles and the aluminum polyvalent ions adsorbed on the nanoparticle surface (electrostatic effect) and three-dimensional effect (steric effect) . If it is shorter than the above aging time, it is not sufficiently aged, and if it is more than that time, aging is completed and the effect of the aging time is not seen and it is not economically good. However, if the CoAl ₂ O ₄ nanoparticles were mixed with the alumina sol after the alumina sol was prepared, after ball milling for a long time in a plastic jar The dispersion stability of CoAl ₂ O ₄ / alumina hybrid sol was very low. Acetic acid used for the stabilization of the sol in the present invention is preferably used acetic acid.

In step d) of preparing a CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol according to the present invention, an alkylsilane is added to the CoAl ₂ O ₄ / alumina hybrid sol prepared in step c) for 24 to 90 hours, preferably Is prepared by stirring for 40 to 80 hours. At this time, if the stirring time is less than 24 hours, there is a problem that the uniformity with CoAl ₂ O ₄ / alumina hybrid sol is deteriorated, and more than 80 hours does not have any effect of improving physical properties and is not economically suitable.

In addition, the alkylsilane which acts as a chemical coupling between the alumina sol particles and the water-soluble polymer is added in a molar ratio of 0.01 to 1.0, preferably 0.1 to 0.5, per mole of aluminum ions of the CoAl ₂ O ₄ / alumina hybrid sol prepared by the above method. do. If the addition amount of the alkylsilane is out of the range, there is a problem that the corrosion resistance of the coating film is lowered. The alkylsilane is preferably selected from 3-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane and 3-mercaptopropyltrimethoxysilane.

In the step e), the water-soluble polymer and the corrosion inhibitor were added to the CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol prepared in the step d) and stirred. At this time, the water-soluble polymer that serves to increase the flexibility and corrosion resistance of the coating film is 0.5 to 3.0% by weight, preferably 1.0 to 2.0% by weight based on 100% by weight of the CoAl ₂ O ₄ / alumina / alkylsilic acid hybrid sol prepared in step d). A water-soluble epoxy, polyalkylene glycol or acrylate-based water-soluble polymer is added to prepare a coating agent. Within the above range, there is a corrosion resistance of the coating film is the best. As the water-soluble polymer, it is preferable to use polyethylene glycol, polyethylene oxide, or water-soluble epoxy having a weight average molecular weight of 300 to 1000 in view of working effects such as viscosity. In the step d), a corrosion inhibitor is selected from Ce (NO ₃ ) _{3 ·} 6H ₂ O, Na ₂ MoO _{4 ·} 2H ₂ O, and ZrOCl _{2 ·} 8H ₂ O, which are aqueous salts of Ce, Zr, and Mo as CoAl ₂ O ₄ 0.1 to 1.0% by weight relative to 100% by weight of the / alumina / alkylsilic acid hybrid sol. If the content is less than 0.1% by weight, there is a problem that there is no addition effect as a corrosion resistance effect, and if the content is 1.0% by weight or more, there is a problem that the sol stability and price rise.

Aluminum chloride solution (97%), acetic acid (97%) and sodium hydroxide (99.9%) are manufactured by Jnusei, CoAl ₂ O ₄ (98%) is manufactured by Asai Co. Cydoxipropyl trimethoxysilane (GPS, 97%) was used by Aldrich Co., Ltd., respectively.

The viscosity of the hybrid sol was measured by a rotation viscometer (Brookfield, Model DV-II) at room temperature. The cross section of the metal coating was observed by SEM (Quanta 400, FEI). Optical microscopy (IMT, i-70) and AFM (DI, Nanoscope IV) were used to observe the shape of the coated metal surface. The XRD pattern of the hybrid sol was measured by XRD (Rigaku, D / MAX-2200V) of CuKα radiation operating at 50 kV, 150 mA. Salt spray test (SST) was performed using a Salt Spray Tester (Osung, OS-CRT01-SS01) by exposing the coating to a salt mist atmosphere produced by spraying 5 wt% aqueous sodium chloride solution at 120-27 ° C. for 120 hours. Was performed. Corrosion was evaluated by the anodic polarization method (APM) using a conventional electrochemical cell covered with a platinum plate as a saturated calomel electrode (SCE) and a counter electrode as a reference electrode. Potential was adjusted with potentiostat (EG & G Instrument Model 273A) and varied with a scan rate of 0.166 mV / S in the range -1.3 V to 0.5 V.

Hereinafter, the present invention by Examples and Comparative Examples will be described in more detail, but only for understanding the configuration and effects of the present invention, it is not intended to limit the scope of the present invention.

Example 1

CoAl according to the present invention ₂ O ₄ CoAl ₂ O ₄ / AlOOH Preparation of Hybrid Sol

Add 48.82 g of aluminum (III) chloride hexahydrate (AlCl _{3 ·} 6H ₂ O)] and 220.82 g of ion-exchanged water to a 500 ml beaker, and stir for about 10 minutes until it is completely dissolved with a magnetic stirrer. An aqueous solution was prepared. 10 g of CoAl ₂ O ₄ was added to the completely dissolved aqueous aluminum chloride solution and stirred again to prepare a suspension in which CoAl ₂ O ₄ was dispersed. Meanwhile, the base solution was prepared by dissolving 24.52 g of sodium hydroxide (NaOH) in 220.68 g of ion-exchanged water in a 500 ml beaker to prepare a 10% aqueous sodium hydroxide solution. A suspension of CoAl ₂ O ₄ / Al (OH) ₃ mixture was prepared by dropping the CoAl ₂ O ₄ dispersed aqueous aluminum chloride solution and sodium hydroxide solution into a 500 ml beaker at a constant rate. After further stirring for 30 minutes, filtration and washing with ion-exchanged water three times, 0.4 g of acetic acid [Acetic acid (CH ₃ COOH)] was added to 10 g of distilled water as a peptizing agent to the obtained CoAl ₂ O ₄ / Al (OH) ₃ mixture cake. The dissolved aqueous solution was added to a sealed container and aged without stirring at 100 ° C. for 48 hours to prepare an alumina sol (5 wt% with Al ₂ O ₃ ) composite sol containing 5 wt% CoAl ₂ O ₄ .

Comparative Example 1

CoAl after Alumina Sol Preparation ₂ O ₄ Of 5 wt% mixed and ball milled composite sol

In Example 1, a composite sol was prepared by adding CoAl ₂ O ₄ to an alumina sol prepared without dispersing CoAl ₂ O ₄ in aluminum chloride in advance and then performing ball milling. The prepared sol produced a large amount of precipitate of CoAl ₂ O ₄ after a certain time, it was confirmed that the storage stability is very poor.

Example 2

6 hours aged CoAl ₂ O ₄ CoAl ₂ O ₄ / AlOOH Manufacture hybrid sol

Except that aged in Example 1 for 6 hours, it was prepared in the same manner as in Example 1.

Example 3

12 hours aged CoAl ₂ O ₄ CoAl ₂ O ₄ / AlOOH Manufacture hybrid sol

Except for aging for 12 hours in Example 1 was prepared in the same manner as in Example 1.

Example 4

CoAl according to the present invention ₂ O ₄ / AlOOH / GPS Hybrid Sol Preparation

Prepared from Example 1 CoAl ₂ O ₄ / AlOOH 0.7 mol of GPS (3-glycidoxypropyltrimetoxysilane) was added dropwise per mol of AlOOH in the composite sol, and stirred for 1 hour to prepare a CoAl ₂ O ₄ / AlOOH / GPS hybrid sol containing 5 wt% CoAl ₂ O ₄ pigment.

Comparative Example 2

In a 500 ml beaker, a 10% aqueous solution of aluminum chloride dissolved in 48.82 g of aluminum (III) chloride hexahydrate (AlCl _{3 ·} 6H ₂ O)] in 220.82 g of ion-exchanged water and sodium hydroxide (NaOH) in a 500 ml beaker )] An aluminum hydroxide slurry was prepared from a 10% aqueous sodium hydroxide solution in which 24.52 g was dissolved in 220.68 g of ion-exchanged water, filtered, and a small amount of ion-exchanged water was added so that the AlOOH concentration was 6 wt% in terms of Al 2 O 3. Alumina sol containing no CoAl ₂ O ₄ pigment was prepared by adding 0.54 g of acetic acid (CH ₃ COOH) as an agar peptizer and aging for 30 hours in an oven maintained at 100 ° C.

Example 5

In the same manner as in Example 4, a CoAl ₂ O ₄ / AlOOH hybrid sol containing 2 wt% CoAl ₂ O ₄ pigment was prepared.

Example 6

In the same manner as in Example 4, a CoAl ₂ O ₄ / AlOOH hybrid sol containing 10 wt% CoAl ₂ O ₄ pigment was prepared.

Example 7

CoAl according to the present invention ₂ O ₄ Preparation of Coating Film Using / AlOOH / GPS Hybrid Sol

An electrolytic galvanized iron (EGI) substrate was immersed in a mixed solution of acetone xylene and distilled water and sonicated to remove dust or organic matter from the surface, and the substrate was prepared using CoAl ₂ O ₄ / AlOOH / GPS hybrid sol prepared in Example 4. Soak in the sol at a rate of 10 mm / min, soak for 2 minutes and then slowly remove. The coated film was suspended vertically for 30 minutes and dried with hot air at 150 ° C. for 30 minutes.

Comparative Example 3

Preparation of Coating Film Using AlOOH / GPS Hybrid Sol

In the same manner as in Example 7 except for using AlOOH / GPS hybrid sol (prepared in the same manner except that CoAl ₂ O ₄ was not added in Example 4) instead of CoAl ₂ O ₄ / AlOOH / GPS hybrid sol. Prepared.

Example 8

CoAl ₂ O ₄ CoAl according to content ₂ O ₄ Of surface morphology of Al / HOOH / GPS hybrid sol coating Salt-spray test (SST) analysis

120% with 5% by weight of sodium chloride (NaCl) solution in CoAl ₂ O ₄ / AlOOH / GPS hybrid sol coating containing no or 2%, 5% and 10% CoAl ₂ O ₄ , respectively prepared by the method of Example 7. After the salt-spray test for a time, the surface shape was observed.

Example 9

On EGI substrate CoAl ₂ O ₄ / AlOOH / GPS Coating Effect Analysis

An uncoated, AlOOH / GPS coated (Comparative Example 3), AlOOH / GPS / CoAl ₂ O ₄ coated EGI substrate containing 5% by weight of CoAl ₂ O ₄ (Example 7) was heated at 150 ° C. for 30 minutes. Curing for 3 minutes, then in 3% sodium chloride solution for each substrate Potentiodynamic polarization curves were measured.

1 is a diagram showing an XRD pattern measured after drying the sol prepared in Examples 1 to 3 and Comparative Example 1. CoAl ₂ O ₄ and in FIG. AlOOH peaks were observed, and each peak was found to be unaffected by aging time. In addition, it was found that the peak of AlOOH was stronger as the time of aging increased, which means that AlOOH crystals were formed from amorphous Al (OH) ₃ by aging. The boehmite type AlOOH sol prepared from Al (OH) ₃ cake produced by reaction with aluminum salt and base catalyst means that it is stable without pyrolysis up to 300 ° C.

Example 10

CoAl ₂ O ₄ / AlOOH / GPS hybrid sol was prepared by adding 0.5 wt% of polyethylene glycol and Ce (NO ₃ ) _{3 ·} 6H ₂ O with an average molecular weight of 600 to the CoAl ₂ O ₄ / AlOOH / GPS hybrid sol prepared in Example _4. The corrosion resistance test was performed by the salt spray test under the same conditions, and the corrosion resistance was increased by about 1.2 times.

2 is a graph showing the viscosity of AlOOH / GPS / CoAl ₂ O ₄ hybrid sol different from CoAl ₂ O ₄ of the present invention prepared in Examples 4 to 6 and Comparative Example 2. In FIG. 2, it was found that the viscosity increased as the content of CoAl ₂ O ₄ particles increased, and there was almost no change in viscosity even with increasing time. In addition, there was little change in viscosity with time of AlOOH / GPS / CoAl ₂ O ₄ hybrid sol after adding GPS. From an industrial point of view, this is one of the most important properties that the sol used for coating should have.

Degree 3 is an atomic force micrograph (AMF) of AlOOH / GPS / CoAl ₂ O ₄ hybrid coating and AlOOH / GPS hybrid coating on EGI substrates prepared in Example 7 and Comparative Example 3. As shown in FIG. 3, the surface roughness after AlOOH / GPS / CoAl ₂ O ₄ coating was considerably smoothed.

4 is 0, 2, 5, 10% by mass of CoAl ₂ O ₄ prepared by the method of Example 4 Contained AlOOH / GPS / CoAl ₂ O ₄ is a photomicrograph showing the surface after the hybrid sol was coated on a zinc-plated steel sheet for heat-treating the coating film for 1 hour in 150 ℃, experiments by the eighth embodiment; As shown in FIG. 4, the AlOOH / GPS / CoAl ₂ O ₄ hybrid coating was blue, and the higher the concentration of CoAl ₂ O _4, the higher the intensity of the color. Moreover, the corrosion resistance of AlOOH / GPS / CoAl ₂ O ₄ hybrid coatings increased with increasing CoAl ₂ O ₄ nanoparticle content. On the other hand, addition of an appropriate amount of CoAl ₂ O ₄ nanoparticles to the AlOOH sol did not change the stability of the hybrid sol, but rather harmed the corrosion protection. The difference in corrosion protection with increasing CoAl ₂ O ₄ nanoparticles cannot be simply explained, but the packing density of the coating decreases from the AlOOH / GPS / CoAl ₂ O ₄ titration ratio. Containing CoAl ₂ O ₄ By AlOOH / GPS / CoAl ₂ O ₄ sol Evidence of corrosion protection was observed by the anodic polarization method (AMP).

FIG. 5 shows AlOOH / GPS / CoAl ₂ O ₄ containing AlOOH / GPS, 5% by mass of CoAl ₂ O ₄ , uncoated according to Example 9. Measured in 3% sodium chloride solution potentiodynamic polarization curves on EGI substrates CoAl ₂ O ₄ / AlOOH / GPS coating effect was shown. Current density due to corrosion of AlOOH / GPS / CoAl ₂ O ₄ hybrid coating on EGI substrate It was found to be much lower than the EGI substrate and relatively lower than the current density of the AlOOH / GPS coating.

AlOOH / GPS / CoAl ₂ O ₄ hybrid sol containing CoAl ₂ O ₄ nanoparticles prepared by the method according to the present invention is very stable and transparent blue color without additional mechanical milling process and can be utilized for aesthetic purposes. In addition, the corrosion resistance of the coating due to the inclusion of CoAl ₂ O ₄ nanoparticles in the alumina sol has been greatly improved, the surface roughness is much smoother, and it is possible to prepare a homogeneous chromium-free corrosion-resistant coating without surface defects. It became.

In addition, the AlOOH / GPS / CoAl ₂ O ₄ hybrid sol according to the present invention has almost no viscosity change with time, which is one of the most important characteristics of the sol used for coating, AlOOH / GPS / CoAl ₂ O ₄ hybrid The current density of the coating is lower than that of the conventional coating sol.

Claims (16)

In the method for producing a corrosion-resistant color coating based on the alumina sol, a) adding a sodium hydroxide solution dropwise to a solution of aluminum chloride solution and CoAl ₂ O ₄ in deionized water to obtain a slurry of CoAl ₂ O ₄ / Al (OH) ₃ mixture; b) Stirring, filtration and washing the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature to prepare a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake; c) step of preparing the CoAl ₂ O ₄ / alumina hybrid sol by dropping the CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared in step b) in a sealed bottle after dropping the peptizing agent Method for producing a corrosion-resistant color coating having a. According to claim 1, CoAl ₂ O ₄ / alumina by the addition of alkyl silane to the hybrid sol CoAl ₂ O ₄ / method of producing a corrosion-resistant color coatings, characterized in that further has a step of producing an alumina / alkylsilane hybrid sol. The method of claim ₂ , further comprising the step of preparing a coating by adding a water-soluble polymer and a corrosion inhibitor to the CoAl ₂ O ₄ / alumina / alkyl silane hybrid sol after preparing the CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol. Method for producing a corrosion-resistant color coating, characterized in that. The method according to any one of claims 1 to 3, wherein the alkyl silane is added to the CoAl ₂ O ₄ / alumina hybrid sol at 0.01 to 1.0 mol per mol of aluminum ions to form a CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol. Method for producing a corrosion-resistant color coating, characterized in that the manufacturing. The corrosion resistance according to claim 4, wherein the alkylsilane is selected from 3-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane methyltriethoxysilane and 3-mercaptopropyltrimethoxysilane. Method for producing a color coating. The method of claim 4, wherein the peptizing agent is acetic acid. The method of claim 3, wherein the coating agent is prepared by adding 0.5 to 3.0 wt% water-soluble polymer and 0.1 to 1.0 wt% corrosion inhibitor based on 100 wt% of the CoAl ₂ O ₄ / alumina / alkylsilic acid hybrid sol. Method of producing corrosive color coatings. The method of claim 7, wherein the water-soluble polymer is a water-dispersible epoxy resin, a polyalkylene oxide or an acrylate polymer. 9. The method of claim 8, wherein the water-soluble polymer has an average molecular weight of 300 to 1000. The corrosion inhibitor according to any one of claims 7 to 9, wherein the corrosion inhibitor is selected from Ce (NO ₃ ) _{3 ·} 6H ₂ O, Na ₂ MoO _{4 ·} 2H ₂ O, and ZrOCl _{2 ·} 8H ₂ O. Method of producing a corrosion-resistant color coating agent. Corrosion-resistant color coating is prepared by the method of any one of claims 1 to 3. In the method for producing a corrosion-resistant color coating based on the alumina sol, a) dissolving aluminum chloride solution and CoAl ₂ O ₄ in deionized water, and then adding 10% by weight of sodium hydroxide solution to the solution to obtain a slurry of CoAl ₂ O ₄ / Al (OH) ₃ mixture; b) Preparing a CoAl ₂ O ₄ / Al (OH) ₃ mixture cake by stirring, filtering and washing the CoAl ₂ O ₄ / Al (OH) ₃ mixture suspension at room temperature for 10 minutes to 5 hours; c) The CoAl ₂ O ₄ / Al (OH) ₃ mixture cake prepared in step b) was added dropwise with acetic acid in a sealed bottle and aged at 50 to 150 ° C. for 4 to 100 hours to form a CoAl ₂ O ₄ / alumina hybrid sol. Preparing a; method for producing a corrosion-resistant color coating having a. 13. The method of claim 12, CoAl ₂ O ₄ / the CoAl the alkylsilane to the alumina hybrid sol ₂ O ₄ / alumina was added to the hybrid sol of aluminum ion per mole of 0.01 to 1.0 molar ratio of CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol Method for producing a corrosion-resistant color coating, characterized in that further undergoing a step of producing a. Of claim 13, CoAl ₂ O ₄ / after the step of producing the alumina / alkylsilane hybrid sols the CoAl ₂ O ₄ / alumina / alkylsilane hybrid sol water-soluble polymer 0.5 to 3.0% and the corrosion inhibitor by weight based on 100% by weight 0.1 Method for producing a corrosion-resistant color coating further comprising the step of preparing a coating by adding to 1.0% by weight. The method according to any one of claims 12 to 14, wherein the alkylsilane is 3-glycidoxypropyltrimethoxysilane, methyltrimethoxysilane methyltriethoxysilane and 3-mercaptopropyltrimethoxy The corrosion inhibitor is selected from Ce (NO ₃ ) _{3 ·} 6H ₂ O, Na ₂ MoO _{4 ·} 2H ₂ O, and ZrOCl _{2 ·} 8H ₂ O, and the water-soluble polymer is an aqueous dispersion having an average molecular weight of 300 to 1000. Method of producing a corrosion-resistant color coating agent characterized in that the epoxy resin, polyalkylene oxide or acrylate polymer. Corrosion-resistant color coating prepared by the manufacturing method of claim 15.

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