WO2007055498A1

WO2007055498A1 - Organo clay containing anticorrosive coating composition and preparation method thereof

Info

Publication number: WO2007055498A1
Application number: PCT/KR2006/004588
Authority: WO
Inventors: Young Chul Lee; Myeong Jun Kim; Yun Shik Yang; Mee-Young Park
Original assignee: Korea Institute Of Industrial Technology
Priority date: 2005-11-11
Filing date: 2006-11-06
Publication date: 2007-05-18
Also published as: JP5188979B2; KR100872833B1; JP2009516017A; KR20070050709A

Abstract

Disclosed are an anticorrosive composition and a preparation method thereof, in which a general anticorrosive coating composition, composed of a monomer or a polymer having a reactive group, dissolved in an organic solvent, and a curing agent, as main components and an additive, further includes organoclay that is dispersed in the main components using ultrasonic waves. The method of preparing the composition includes uniformly dispersing organoclay in a monomer or a polymer having a reactive group, dissolved in an organic solvent, and/or a curing agent having an amine group, using ultrasonic waves, mixing the monomer or polymer having a reactive group with the curing agent, in which the organoclay is uniformly dispersed, and then adding an additive thereto. The anticorrosive composition can be used in various coatings including a zinc steel plate for automobiles, therefore remarkably increasing corrosion resistance.

Description

ORGiWO CLAY CONTAINING ANTICORROSIVE COATING COMPOSITION AND PREPARATION METHOD THEREOF

Technical Field The present invention relates to an organoclay- containing anticorrosive coating composition and a preparation method thereof. More particularly, the present invention relates to an anticorrosive composition, comprising a curable monomer or polymer, such as epoxy, which is dissolved in an organic solvent, a curing agent, having two or more amine groups, and organoclay, which is uniformly mixed and dispersed in either or both of the monomer or polymer and the curing agent or in the mixture of the two components using ultrasonic waves, and to a method of preparing the same. The coating composition according to the present invention is a coating agent having corrosion resistance for preventing the corrosion of the surface of metal, such as a zinc plated steel plate, but the present invention is not limited thereto.

Background Art

Generally, the surface of a cold rolled steel plate is plated with metal, such as zinc, to impart the steel plate with corrosion resistance, therefore resulting in zinc plated steel plates and other plated steel plates. When such a metal plated steel plate is exposed to moisture or air for a long time period, metal oxide, such as white rust and/or red rust, is formed.

Further, corrosion resistance treatment of a zinc- nickel plated steel plate for use in automobiles is chiefly realized by applying chromate and then coating with organic resin. However, according to the recent trend away from the use of chromium, which is harmful to human bodies, the function of the resin coating layer becomes more important (Park, Chan Seop et al., Polymer Science & Technology, 12(5) , 660, 2001) .

Accordingly, with the goal of increasing corrosion resistance without the use of chromium, a chromium-free anticorrosive coating agent and a preparation method thereof are disclosed in Korean Patent Nos . 443259 and 428562. Specifically, Patent No. 443259 discloses a coating composition prepared by adding alumina sol, serving as a main component, with predetermined amounts of alkylsilane, a specific aqueous polymer, and a molybdenum-containing corrosion inhibitor, and Patent No-. 428562 discloses a coating composition, composed of 80-50 wt% of a resin mixture comprising aqueous organic resin and an inorganic component mixed at a solid content ratio of 70:30-30:70, 10-40 wt% of a phosphate-based rust inhibitor of metal oxide, and 1-20 wt% of an organo-metallic complex. In addition, Korean Examined Patent Publication No. 2005-63979 discloses a resin composition for a pre-sealed steel plate, comprising 100 parts by weight of epoxy resin, having a number average molecular weight of 15,000-60,000, 5-30 parts by weight of polymer-clay nanocomposite, 5-20 parts by weight of melamine resin, 1-5 parts by weight of wax, and 80-300 parts by weight of metal powder.

In the Examined Patent Publication No. 2005-63979, in the case where such a coating composition composed of the polymer-clay nanocomposite is applied on a zinc plated steel plate, the properties of the resin coating are evaluated while the molecular weight and the amount of the epoxy resin, the amount of the curing agent, and the amount of the polymer-clay nanocomposite are varied. Additionally, in the case where a predetermined composition ratio is provided, as in the claims of the above patent publication, a coating composition having good corrosion resistance and electrodeposition applicability is reportedly obtained.

The present invention, carried out by the present inventors aiming to avoid the problems encountered in the related art, resulted in the finding that a coating composition, prepared by uniformly dispersing organoclay in epoxy resin having a molecular weight different from that disclosed in the Examined Patent Publication No. 2005-63979 and/or a melamine curing agent using a predetermined process and then mixing them with other coating components, can have superior corrosion resistance. That is, in the above examined patent publication, the case where the epoxy resin, having the molecular weight disclosed above, is not used is disclosed to make it impossible to assure good effects. However, in the case where an epoxy monomer or oligomer having a molecular weight much lower than that disclosed in the above examined patent publication is used and organoclay is uniformly dispersed using the process of the present invention before the epoxy resin and the curing agent, that is, the main components, are mixed, or in a state in which only the main components are mixed to thus prepare a coating composition, the coating composition thus prepared can exhibit corrosion resistance superior to that disclosed in the above examined patent publication.

Disclosure Technical Problem

Accordingly, an object of the present invention is to provide a novel anticorrosive coating composition, comprising an epoxy monomer or oligomer and a melamine curing agent, in which organoclay is uniformly dispersed through a new process using ultrasonic waves.

Another object of the present invention is to provide a method of preparing an anticorrosive coating composition having improved corrosion resistance, comprising uniformly dispersing organoclay in an epoxy monomer or oligomer and/or a melamine curing agent using ultrasonic waves and then mixing them with an additive. A further object of the present invention is to provide an anticorrosive coating composition, which does not include chromium (Cr) , which is harmful to human bodies, and is thus environmentally friendly for application on the surface of any kind of metal, for example a zinc plated steel plate.

Yet another object of the present invention is to provide a coating composition, which can be applied on various surfaces to thereby increase corrosion resistance.

Best Mode

According to a first preferred aspect of the present invention, the invention provides an anticorrosive coating composition, comprising 100 parts by weight of an epoxy resin monomer or oligomer, 5-80 parts by weight of a curing agent having two or more amine functional groups, and 0.1-20 parts by weight of organic clay, which is uniformly mixed and dispersed in either or both of the epoxy monomer or oligomer and the curing agent. According to a second preferred aspect of the present invention, the invention provides an anticorrosive coating composition, comprising 100 parts by weight of an epoxy monomer or oligomer having a number average molecular weight of 340-2,000 g/mole, 5-80 parts by weight of a curing agent having two or more amine functional groups, and 0.1-20 parts by weight of organoclay, uniformly mixed and dispersed in either or both of the epoxy monomer or oligomer and the curing agent.

In the preferred aspects of the present invention, the organoclay, which is uniformly mixed and dispersed in either or both of the epoxy monomer or oligomer and the curing agent, is characterized in that uniform mixing and dispersion thereof can be realized using ultrasonic waves.

Further, the mixing and dispersion of the organoclay may be conducted in respective components before mixing the above two components, or alternatively, the above two components are mixed and then the organoclay is mixed and dispersed therein.

Thus, according to a third preferred aspect of the present invention, the invention provides a method of preparing the uniformly dispersed organoclay-containing anticorrosive coating composition according to the first and second aspects, comprising

(i) uniformly dispersing 0.1~20 parts by weight of organoclay in either or both of 100 parts by weight of an epoxy resin monomer or oligomer and 5~30 parts by weight of a curing agent having two or more amine functional groups using ultrasonic waves, and then mixing the epoxy resin monomer or oligomer with the curing agent, either or both of which have the organoclay dispersed therein, or (ii) mixing 100 parts by weight of an epoxy resin monomer or oligomer with 5-30 parts by weight of a curing agent having two or more amine functional groups, and then uniformly dispersing 0.1~20 parts by weight of organoclay in the mixture using ultrasonic waves .

Preferably, as well as the main components, such as the epoxy resin, the curing agent, and the organoclay, the anticorrosive composition of the present invention may further comprise additive components, including an inorganic material, such as alumina or silica sol, which does not participate in the curing reaction in the coating composition, metal powders for increasing weldability, wax for increasing lubricating properties, a phosphate-based rust inhibitor, and an organo-metallic complex. In addition, other coating additive components, which are well known to those skilled in the art, may be further included. Optionally, any component may be variously selected from among the above-mentioned additive components, depending on the end use of the coating composition, which will be apparent to those skilled in that art. In the method of preparing the anticorrosive coating composition of the present invention, after mixing the main components of the coating composition according to the procedure of (i) or (ii) , the additive component may be added thereto and thus mixed.

In the composition, the curing agent having two or more amine functional groups includes primary amines, secondary amines, tertiary amines, quaternary amines, and all amine derivatives, and is preferably exemplified by a melamine curing agent.

The epoxy monomer, having epoxy groups attached to both ends thereof, reacts with an amine group to thus produce a polymer. The epoxy monomer useful in the present invention includes a modified epoxy monomer having a functional group, such as a halogen group or an amine group. Examples of the melamine derivative having two or more amine groups for use in polymerization or curing of the epoxy include methoxymethyl melamine, methoxymethyl butoxymethyl melamine, and hexamethoxymethyl melamine.

The nanocomposite of polymer and clay has good mechanical properties such as tensile strength, heat resistance, and permeation barrier effects to gases, such as oxygen, and moisture, and therefore is under thorough study at present. The clay generally indicates inorganic chemical material composed of silicate having a layered structure, in which the layers are in the form of an irregular disk with a thickness of about 1 nm and a diameter of about 0.1-100 μm.

Examples of the clay include kaolin, serpentine, mica, vermiculite, smectite, and phyllosilicate. Further, examples of the smectite include bentonite, montmorillonite

(MMT) , saponite, armargosite, metabentonite, hectorite, beidellite, stevensite, halloysite, and nontronite.

As the organoclay used in the composition of the present invention, useful is commercial organoclay sold under the trade name of Cloisite 3OB, available from Southern Clay Products, or natural clay, organically modified through various methods known in the art. The coating composition of the present invention may also be used as a solvent-type anticorrosive coating composition, composed mainly of an epoxy resin monomer or oligomer (number average molecular weight of 340~2,000 g/mole) , for use in the surface protection of pre-sealed steel plates and other metals .

A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed as the limit of the present invention.

Mode for Invention

Example 1

As main components of a solvent-type coating solution, an epoxy monomer having an average molecular weight of 380 g/mole and a melamine curing agent were used.

Organoclay was dispersed in each of the main components, and in the mixture of the main components, thus preparing nanocomposite type coating compositions.

As the epoxy monomer, YD-128 (diglycidyl ether of Bisphenol-A, epoxy equivalent weight of 186.4 g/eq, number average molecular weight of 372.8 g/mole), available from Kukdo Chemical Co. Ltd., was used, and as the curing agent, a melamine derivative, available from Cytec Industries Inc., and DDS (4, 4' -diaminodiphenylsulfonate) , available from Tokyo Chemical Industry Co. Ltd., were used. The organoclay Cloisite 3OB, available from Southern Clay Products, was used, and this Cloisite 3OB was organically modified montmorillonite (MMT) comprising organic material, including a methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium ion, intercalated into the layers thereof. In Table 1 below, the sample 1 was a coating solution having no organoclay, obtained by mixing components using a general stirrer. The sample 2 was obtained by dispersing 2.5 parts by weight of Cloisite 3OB to 100 parts by weight of an epoxy monomer for 20 min using ultrasonic waves (max. power of 750 W), separately dispersing 2.5 parts by weight of Cloisite 3OB in 75 parts by weight of a melamine curing agent for 20 min using ultrasonic waves, and mixing the epoxy/organoclay (epoxy monomer having organoclay dispersed therein) and the melamine curing agent/organoclay (melamine curing agent having organoclay dispersed therein) , thus separately prepared, with 10 parts by weight of DDS for 20 min using ultrasonic waves. As the samples 3 and 4, dispersion of 5 parts by weight of organoclay in 100 parts by weight of an epoxy resin and of 5 parts by weight of organoclay in 75 parts by weight of a melamine curing agent, respectively, was conducted for 20 min using ultrasonic waves, and then a mixing process was carried out, thus the corresponding coating compositions were obtained. Further, the sample 5 was prepared by mixing, as main components, 100 parts by weight of epoxy, 75 parts by weight of a melamine curing agent, and 10 parts by weight of DDS using a general stirrer and then dispersing 5 parts by weight of organoclay therein for 20 min using ultrasonic waves .

Moreover, the amount of xylene (about 20~40 parts by weight based on 100 parts by weight of epoxy) was controlled and mixed using a general stirrer, so that the five samples of Table 1 had the same viscosity. In this way, because the five samples had the same viscosity, the thickness of coating films obtained through bar coating were the same, and the change in corrosion resistance depending on the composition difference could be estimated.

Each of the five samples of Table 1 was applied on a zinc plated steel plate using bar coater and then allowed to react in an oven, in which the temperature of the steel plate was maintained at 250°C, for 60 sec, leading to a zinc plated steel plate coated with about 2.0 g/m² of the coating composition.

Four coated zinc plated steel plates per sample were placed into a saltwater spray tester (SST) , and the surface state thereof was photographed at predetermined time intervals . The time that it took for red rust to be generated was observed with the naked eye and the average value thereof was used to evaluate corrosion resistance. The results are summarized in Table 1 below. As such, the saltwater spray tester was operated at 36°C under conditions of saltwater spray pressure of 1 kg/cm² and relative humidity of 99%.

Compared to the sample 1, all coating compositions having 5 parts by weight of the organoclay exhibited improved corrosion resistance.

TABLE 1

Results of Corrosion Resistance depending on Composition of Resin, Curing Agent and Organoclay

As the results of measurement using an X-ray diffractometer (Pohang Accelerator Laboratory, 4Cl and 5C2, SAXS) , the epoxy monomer and the melamine curing agent were penetrated into the galleries of Cloisite 3OB in the course of the dispersion, such that the d-spacing of layers increased from 1.8 nm to 8.3 nm and 3.8 nm, respectively. In the case where the dispersion was performed using a general stirrer, no increase in the d-spacing of layers was observed.

Example 2

As main components of a solvent-type coating solution, an epoxy monomer having an average molecular weight of 380 g/mole and a melamine curing agent were used. Selectively, as the resin component, polyurethane resin, having an average molecular weight of 5,000-50,000 and dissolved in xylene, could be further included. Organoclay was dispersed in each of the main components, thus preparing nanocomposite type coating compositions.

In Table 2 below, the sample 7 was prepared by dispersing 2.5 parts by weight of Cloisite 3OB to 100 parts by weight of an epoxy monomer for 20 min using ultrasonic waves (max. power of 750 W), separately dispersing 2.5 parts by weight of Cloisite 3OB in 15 parts by weight of a melamine curing agent for 20 min using ultrasonic waves, and mixing the epoxy/organoclay (epoxy monomer having organoclay dispersed therein) and the separately prepared melamine curing agent/organoclay (melamine curing agent having organoclay dispersed therein) with 10 parts by weight of polyurethane and 10 parts by weight of DDS for 20 min using ultrasonic waves.

The sample 6 was obtained by mixing components, not using ultrasonic waves but using a general stirrer, due to the absence of organoclay.

As the results of measurement using an X-ray diffractometer (Pohang Accelerator Laboratory, 4Cl and 5C2, SAXS) , the epoxy monomer and the melamine curing agent were penetrated into the layers of Cloisite 3OB in the course of the dispersion, and thus the d-spacing of layers increased from 1.8 nm to 8.3 nm and 3.8 ran, respectively. In the case where the dispersion was performed using a general stirrer, no increase in the d-spacing of layers was observed.

Further, the amount of xylene was controlled and mixed using a general stirrer, so that the two samples of Table 2 had the same viscosity. Because the two samples had the same viscosity, the thickness of coating films obtained through bar coating were the same, and the change in corrosion resistance depending on the composition difference could be estimated.

Each of the two samples of Table 2 was applied on a zinc plated steel plate using bar coater and then allowed to react in an oven, in which the temperature of the steel plate was maintained at 250⁰C, for 60 sec, therefore obtaining a zinc plated steel plate coated with about 2.0 g/m² of the coating composition.

Three coated zinc plated steel plates per sample were placed into a saltwater spray tester (SST) , and the surface state thereof was photographed at predetermined time intervals . The time that it took for red rust to be generated was observed with the naked eye, and the average value thereof was used to evaluate corrosion resistance. The results are summarized in Table 2 below. As is apparent from the results of saltwater spray test for two coating compositions of Table 2, in the case where no organoclay was added, red rust was generated after 792 hours on average. However, the coating solution having the organoclay had no red rust until 1,848 hours. Also, metal powder for assuring weldability after coating and other additives were added to the anticorrosive coating composition to thus yield a coating solution. Accordingly, the two samples of Table 2 respectively were added with the same amounts of metal powder and the additives, applied on the zinc plated steel plate, cured, and then tested for corrosion resistance. The resultant corrosion resistance of the coating composition having the organoclay could be confirmed to be superior. Further, the two samples of Table 2 respectively were added with the same amounts of metal powder and the additives, applied, cured, formed into a cup, and then tested for adhesion. Furthermore, a boiling water adhesion test, in which the formed cup was dipped into boiling water (100⁰C) for 1 hour and then tested for adhesion, was conducted. For the adhesion test, when adhesive tapes of the same size as each other were attached to the steel plate and then immediately removed, whether the coating was peeled off or not was observed. Upon the test of adhesion to the cup produced above, the coating did not peel off in either case of the coating solution having no organoclay and the nanocomposite coating solution having organoclay. However, upon the boiling water adhesion test of the produced cup, in the case of the coating solution having organoclay (sample I)₁ the coating did not peel off, whereas the coating partially peeled off in the case of the coating solution having no organoclay (sample 6) . Even upon an adhesion test after cross-cut under conditions more severe than in the production of the cup, in the case of the coating solution having organoclay, the coating did not peel off, and the coating surface was maintained without degrading. For the cross-cut adhesion test, the coating surface was cross-cut into 100 surfaces each having a size of 1 cm x 1 cm using a blade, after which adhesive tape was attached thereto and then removed to thus evaluate the adhesion.

TABLE 2

Example 3

In the same manner as in Example 1, organoclay (Cloisite 30B) was dispersed in an epoxy oligomer having an average molecular weight of 2,000 g/mole using a sonicator (max. power 750 W) and then mixed with other components using a sonicator, thus preparing a coating composition (sample 9) . The components and weight ratios thereof are summarized in Table 3 below.

Further, in the same manner as in Example 1, the coating composition was applied on a zinc plated steel plate and then cured in an oven. Three coated zinc plated steel plates per sample were placed into a saltwater spray tester (SST) to thus measure corrosion resistance. Unlike Examples 1 and 2, in Example 3, the SST was operated at 42°C, so that red rust was quickly generated. The time periods required for generating red rust on the surface of the coated zinc plated steel plate were averaged. The results are shown in Table 3 below.

The corrosion resistance of the coating composition having organoclay (sample 9) was 744 hours on average, and was thus superior to that of the coating composition having no organoclay (sample 8) .

TABLE 3

Example 4

Compared to Examples 1 and 2, in which the organoclay was used in an amount of 5 parts by weight based on 100 parts by weight of the epoxy monomer to thus prepare the coating composition having organoclay, the coating composition was prepared using the organoclay in different amounts so as to determine the optimal amount of the organoclay. Further, unlike Examples 1,2 and 3 dispersion and mixing using ultrasonic waves were conducted only once. That is, when the samples 11, 12 and 13 of Table 4 were prepared, an epoxy monomer, polyurethane, a melamine curing agent, DDS and organoclay were mixed together as shown in Table 4 below, and then dispersed for 20 min using ultrasonic waves . In the sample having no organoclay, red rust was observed after 288 hours, whereas the sample having organoclay had no red rust even after 288 hours. When the amount of the organoclay was 2.5 parts by weight, red rust was observed after 624 hours, which was above 100% higher than in the coating composition having no organoclay. Furthermore, the use of the organoclay in an amount of 6.5 parts by weight resulted in the generation of red rust after 720 hours, and the use of the organoclay in an amount of 4.5 parts by weight resulted in the generation of red rust after 792 hours. Thereby, the optimal amount of the organoclay, which was added to the organoclay- containing coating solution for application on a steel plate, was determined to be about 4.5 parts by weight.

The coating solution containing 4.5 parts by weight of the organoclay was applied on a steel plate and then cured, after which a coating layer was separated in the form of a film and thus analyzed using an XRD (Pohang Accelerator Laboratory, 5C2, SAXS) . Although the intrinsic d-spacing of Cloisite 3OB was 1.8 nm, the d-spacing after curing was measured to be 4.7 nm. From this, it could be confirmed that the clay was efficiently dispersed. Thanks to the efficient dispersion of the organoclay, the barrier property was improved, leading to superior corrosion resistance. TABLE 4

Results of Corrosion Resistance depending on Amount of

Organoclay

Example 5

The components of a coating composition for application on a zinc plated steel plate, other than the organoclay, were not changed, but the dispersion process was varied when the organoclay was added in an amount of 3 parts by weight or 5 parts by weight based on the amount of resin, thus preparing samples. In the samples 14, 15, and 16 of Table 5, the sample 14 had no organoclay, and the sample 15 was prepared in such a manner that both dispersion of the organoclay in epoxy and a melamine curing agent and mixing into a coating composition were conducted using a general stirrer for 20 min. Further, the sample 16 had the same composition ratio as in the sample 15, with the exception that both dispersion of the organoclay in epoxy and a melamine curing agent and mixing into a coating composition were performed using a sonicator for 20 min. The coating process and the curing process were applied as above, and the corrosion resistance was measured using an SST at 42°C .

As is apparent from the results of the test of corrosion resistance, the organoclay could be seen to contribute to increased corrosion resistance. Further, when the organoclay was dispersed and mixed using a sonicator, the resin or curing agent was diffused into the galleries of the organoclay, thus realizing superior corrosion resistance to that of the coating composition prepared through simple mixing using a general stirrer. In the samples 17, 18, 19, and 20 of Table 5, which had the same composition ratio, the sample 17 was prepared by dispersing the organoclay using a general stirrer, and the samples 18, 19 and 20 were prepared in such a manner that the organoclay was dispersed in epoxy, the melamine curing agent, and epoxy/melamine curing agent, respectively, using ultrasonic waves, and then a mixing process was performed using a sonicator.

In the case where the dispersion of the organoclay in the epoxy or the melamine curing agent and the mixing thereof were conducted using ultrasonic waves (samples 18, 19, 20) , corrosion resistance was 408-444 hours, which was superior compared to when no ultrasonic waves was used (sample 17) . TABLE 5

Industrial Applicability

As described above, organoclay is dispersed in each of the main components of a coating composition or in a mixture of the main components using ultrasonic waves, after which these components are mixed with an additive, thus preparing a coating composition. The coating composition thus prepared has corrosion resistance superior to that of conventional coating compositions containing organoclay, and furthermore, has good properties, including weldability and adhesion. Accordingly, the coating composition of the present invention can be efficiently applied not only on a zinc plated steel plate but also on other metals, thereby remarkably increasing corrosion resistance.

Claims

1. An anticorrosive coating composition, comprising 100 parts by weight of an epoxy resin monomer or oligomer, 5-80 parts by weight of a curing agent having two or more amine functional groups, and 0.1-20 parts by weight of organoclay, which is uniformly mixed and dispersed in either or both of the epoxy monomer or oligomer and the curing agent .

2. The composition according to claim 1, wherein the organoclay is mixed and dispersed using ultrasonic waves.

3. The composition according to claim 1, wherein the epoxy monomer or oligomer has a number average molecular weight of 340-2,000 g/mole.

4. The composition according to claim 1, wherein the organoclay is selected from the group consisting of smectite clays having a layered structure, including montmorillonite, hectorite, halloysite, bentonite, nontronite, and beidellite, each of which is natural or synthetic.

5. The composition according to claim 4, wherein the organoclay is organically modified montmorillonite, comprising a methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium ion, intercalated into layers thereof.

6. The composition according to claim 1, wherein the organoclay is contained in an amount of 3~β wt% based on an amount of the epoxy monomer.

7. The composition according to claim 1, further comprising an additive selected from the group consisting of alumina sol, silica sol, metal powder, wax, and a phosphate-based rust inhibitor.

8. The composition according to claim 1, wherein the epoxy monomer is a modified epoxy monomer containing a halogen group or an amine group.

9. A method of preparing a uniformly dispersed organoclay-containing anticorrosive coating composition, comprising: (i) uniformly dispersing 0.1-20 parts by weight of organoclay in either or both of 100 parts by weight of an epoxy resin monomer or oligomer and 5~30 parts by weight of a curing agent having two or more amine functional groups using ultrasonic waves, and then mixing the epoxy resin monomer or oligomer and the curing agent, either or both of which have the organoclay dispersed therein, or (ii) mixing 100 parts by weight of an epoxy resin monomer or oligomer and 5~30 parts by weight of a curing agent having two or more amine functional groups, and then uniformly dispersing 0.1-20 parts by weight of organoclay therein using ultrasonic waves .

10. The method according to claim 9, further comprising adding and mixing an additive, selected from the group consisting of alumina sol, silica sol, metal powder, wax, and a phosphate-based rust inhibitor, to the mixture of the epoxy resin monomer or oligomer and the curing agent, in which the organoclay is dispersed, after (i) or

(ϋ) ■

11. A zinc plated steel plate, coated with the anticorrosive coating composition of claim 1.