KR100957986B1 - Steel Sheet Having Coating Containing Self Healing Microcapsule Encapsulating Inorganic Compound and Coating Composition Comprising the Micro Capsule - Google Patents

Abstract

The present invention provides a surface-treated steel sheet comprising a composition obtained by dispersing a microcapsule particle having an average particle diameter of 5 μm or less on an organic or organic / inorganic resin film on an iron, zinc, galvanized steel sheet, or zinc alloy plated steel sheet. It relates to a manufacturing method and a surface treated steel sheet. More specifically, in order to give corrosion resistance and self-retaining property to the organic or organic / inorganic composite resin coating composition, a micro-sized self-repairing capsule containing an inorganic compound in a capsule cell using hydrophobicity and hydrophilicity is prepared by a polymerization method and an organic resin. The present invention relates to a technology for providing corrosion resistance and self-maintenance by dispersing the capsules in the air and forming an inorganic compound on the surface of the steel sheet exposed by the impact when the microcapsule bursts during an external impact.

Microcapsulation, Electro Zinc Plating, Corrosion Resistance, Self Repair, Cerium Compound, Magnesium Compound

Description

Steel Sheet Having Coating Containing Self Healing Microcapsule Encapsulating Inorganic Compound and Coating Composition Comprising the Micro Capsule

The present invention relates to a surface treatment composition of a steel sheet, and a steel sheet surface treated therefrom, and more particularly, a microcapsules exhibiting self-retainability at the damage site of the film, the method for producing the microcapsules, and a surface treatment composition comprising the same, and compositions thereof It relates to a steel sheet surface-treated from.

Existing surface treatment compositions are composed of organic resins (epoxy, alkyd) or organic / inorganic composite resins using silane as a coupling agent, and the thickness of the composition is usually 10 μm or less. The surface treatment composition serves to improve the corrosion resistance of the base metal by shielding the base metal from external corrosion factors (humidity, oxygen, pollutant ions) and is also widely used industrially.

These surface treatment compositions are often damaged by external impacts during transportation or operation, and the metal is exposed to corrosion at the site where the composition is damaged. Existing methods have provided a method of improving the corrosion resistance and forming a so-called self-healing effect by depositing exposed base metal parts with chromate compounds by forming a surface treatment composition mainly composed of chromate.

However, the chromate treatment method has become a technology that can no longer be used as environmental regulations are strengthened, and a method of coating organic resins, vanadium, manganese, zirconium compounds, etc., by providing a surface treatment composition to protect the metals. The organic / inorganic composite resin film steel plate manufacturing method etc. which provide the film mixed with and the like are utilized.

These techniques provide a method of securing corrosion resistance by shielding the base metal from external corrosion factors, but when the composition is damaged by external damage, it does not provide a so-called self-repair effect to suppress the corrosion of the exposed base metal. .

 In order to solve this problem, studies have been started to provide self-repair effects by microencapsulation.

The self-repair concept through the release of activating materials enclosed in microcapsules into the material was first proposed in the early nineties by Dry (C. Dry, Comp. Struct., Vol. 35, 263 (1996)). In addition, research on self-repairing composites based on polymer microcapsules encapsulated with an uncured polymer material began with the White Group of the University of Illinois, encapsulating a mixture of styrene, divinylbenzene and polystyrene. Repair study of the used polyester resin was carried out [EP Wang, J. Polym. Sci .: Part B. Vol. 32, 1217 (1994).

Professor White (SR White, NR Sottos, PH Geubelle, JS Moore, MR Kessler, SR Sriram, EN Brown, S. Viswanathan, Nature 2001, 409 , 794-797.) The microencapsulation self-repairing method is disclosed in which the curing agent and the resin component form a new film upon external impact.

In Korean Patent Application No. 2002-0086506, a technology having self-repairing properties has been applied mainly by micro-encapsulating an epoxy resin and a curing agent as a core material in an acrylic-based or PVA-based shell. When the resin and the curing agent are introduced into the microcapsules, when the core materials composed of the liquid resin and the curing agent are used for a long time, the solution or the low molecular weight core material is volatilized out of the shell, and then the liquid resin and the curing agent are removed after a certain period of time. It is pointed out that the fluidity is lost, and that self-maintenance is not expressed or is significantly reduced in case of external impact or film damage.

Japanese Patent Application Laid-Open No. 2007-237460 discloses a resin coated steel sheet containing a water-soluble acidic resin having a number average molecular weight of 1000-100000 and a microcapsule containing polyphenol compounds in porous fine particles having an average particle diameter of 5 micrometers or less. . However, in the above document, the organic material of the polyphenol is contained in the microcapsules, which is different from the present invention, and the polyphenol resin in the capsule flows through the wound to show self-retainability, but it may be difficult to secure sufficient fluidity. .

In addition, many attempts have been made to apply an inorganic compound system (molybdenum, titanium, tungsten) having a similar performance as chromate to the surface treatment composition by microencapsulation, but until now, the instability and insufficiency of the inorganic compound have been insufficient. It has not been applied industrially due to self-repair effect. In particular, the method of dispersing and storing inorganic compounds in microcapsules and selecting the most effective inorganic compound remains a technical challenge.

The present invention is to disperse the inorganic compound in the encapsulation method by encapsulation method, so that the encapsulated inorganic compound is eluted when the surface treatment film is broken by external impact, thereby producing an inorganic salt compound on the metal parts exposed to the breakage. An object of the present invention is to provide a surface-treated steel sheet which provides a repair effect and is excellent in corrosion resistance.

In order to achieve the above object,

As a first aspect, it is included in the self-retaining surface treatment composition used for the surface treatment of the steel sheet, and includes an inorganic compound as a core material in the polymer shell, the inorganic compound is cerium, magnesium, vanadium, zirconium, lanthanum, cobalt And microcapsules, characterized in that selected from the group consisting of

In a second aspect, the shell is any one compound selected from the group consisting of acrylic, epoxy, urethane, urea-formaldehyde, polyvinyl alcohol, polystyrene, polyethylene, bio-type polymers, polymer brushes, and mixtures thereof. Characterized by microcapsules,

In a third aspect, the microcapsule has a size of 0.1-50 micrometers,

In a fourth aspect, the method includes dispersing a core component of an inorganic compound into a stable droplet form in a media solution using a dispersion stabilizer having a micellar structure;

Introducing a low molecular weight shell constituent in the liquid phase onto the media solution; And

Growing the low molecular weight shell constituent to form a microcapsule;

Micro capsule manufacturing method comprising a,

As a fifth aspect, the dispersion stabilizer is a method for producing microcapsules, characterized in that the polyvinyl alcohol, acacia powder, hydrophilic-hydrophobic copolymer or a mixture thereof,

As a sixth aspect, the core material is a microcapsule manufacturing method characterized in that the inorganic compound is cerium, magnesium, vanadium, zirconium, lanthanum, cobalt or a mixture thereof,

As a seventh aspect, the media solution is a microcapsule manufacturing method, characterized in that the chloroform or alkyl acetate,

In an eighth aspect, the shell component is an acrylic, epoxy, urethane, urea-formaldehyde, polyvinyl alcohol, polystyrene, polyethylene, biopolymer, polymer brush or a mixture thereof,

In a ninth aspect, the growth of the shell component in the microcapsule forming step uses a curing agent, wherein the curing agent is amine-based, amide-based, isocyanate-based, glycol-based, alcohol-based, or a mixture thereof. Microcapsules manufacturing method,

As a tenth aspect, the microcapsules forming step is a method for producing a microcapsule, characterized in that the stirring with a mechanical stirrer at a temperature of 50-100 ℃ using the curing agent,

As an eleventh aspect, the stirring speed is a microcapsules manufacturing method, characterized in that 200-3500rpm,

As a twelfth aspect, the method of manufacturing a microcapsule further comprises the step of separating the formed microcapsules from the solution phase and refining them into powder capsules.

In a thirteenth aspect, a self-retaining surface treatment resin composition in which the microcapsules are dispersed in an organic resin of an oily or aqueous type of an epoxy resin, a silane resin, an alkyd resin, an acrylic resin, a urethane resin, or a polyethylene-acrylate resin,

In a fourteenth aspect, the self-retaining surface treatment resin composition is coated on a metal surface by a coating method after roll coating, spray coating, or dipping to form a dry film having a thickness of 10-100 micrometers. do.

Surface treatment of the steel sheet using the surface treatment composition comprising the microcapsules according to the present invention is excellent in corrosion resistance by excellent self-maintenance against external impact.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a steel sheet coated with the self-maintaining surface treatment composition of the present invention, which is a schematic diagram showing the concept of self-repairing, and Fig. 2 is a schematic diagram showing a microcapsule of the present invention. In the drawings, 1 is a microcapsule, 2 is a shell, 3 is a core material of an inorganic compound, 4 is an organic resin, 5 is a steel sheet, 6 is a self-retaining resin film, and 7 is a surface treated steel sheet.

The present invention provides a surface treatment composition comprising a microcapsules excellent in self-maintenance.

The microcapsule is composed of a shell portion and a core material inside the shell, as shown in FIG.

The preparation of the self-conserving microcapsules of the present invention involves dispersing the core material in the form of stable droplets on the media solution using a dispersion stabilizer. The core material consists of a solution containing an inorganic compound. The solution has different properties from the media solution. For example, when the media solution is hydrophilic, the solution of the core portion may be hydrophobic. In addition, the solution of the core portion should be one capable of dissolving the inorganic compound.

The inorganic compound of the core material may be cerium, magnesium, vanadium, zirconium, lanthanum or cobalt, and these may be used alone or in combination thereof.

The inorganic compound is also dispersed in the media solution. Examples of the media solution include cyclohexanone, ethyl acetate, chloroform, chlorobenzene, and the like.

The dispersion stabilizer can be used having a micelle structure of the amphoteric structure having a hydrophilic group and a hydrophobic group. Examples of the dispersion stabilizer having a micelle structure include polyvinyl alcohol, acacia powder (gumarabic), and a hydrophilic hydrophobic copolymer. The hydrophilic hydrophobic copolymer may be polyethylene oxide / polypropylene oxide, Ethylene maleic anhydride etc. are mentioned.

The preparation of the self-maintaining microcapsules of the present invention comprises the step of introducing a low molecular weight shell constituent material in the liquid phase onto the media solution.

The shell constituent preferably has a low molecular weight or fine nanomonostructure. Although the said molecular weight is not limited to this, What is about 500-3000 can be used.

Next, the self-maintaining microcapsule manufacturing method of the present invention includes the step of growing the low molecular weight shell constituent to form a self-maintaining microcapsules containing the core material therein.

The shell may be any one compound selected from the group consisting of acrylic resins, epoxy resins, urethane resins, urea-formaldehyde, polyvinyl alcohol, polystyrene, polyethylene, biopolymers, polymer brushes, and mixtures thereof.

The low molecular weight shell constituents can be grown using a curing agent, and examples of the curing agent that can be used include amine compounds, amide compounds, isocyanate compounds, glycol compounds such as ethylene glycol, and alcohol compounds. These may be used alone or in combination. The hardener may vary the hardener used depending upon the shell constituent. For example, when the shell component is a urethane resin, a glycol compound such as ethylene glycol may be used, and in the case of an epoxy resin, an amine compound, an isocyanite compound, or the like may be used, and in the case of urea, formaldehyde or the like may be used. Can be used as a curing agent.

In addition, the core material included in the shell is a mixed solution containing the inorganic compound and the media solution.

Further, in the microcapsule forming step, it can be stirred with a mechanical stirrer at a temperature of 50-100 ℃ using the curing agent. At this time, the size of the capsule can be adjusted by appropriately controlling the stirring speed. The stirring speed is preferably stirred in the range of 200-35000 rpm. When the stirring speed in the above range can be obtained a microcapsules having a size of 0.1 to 50 micrometers, the size of the capsule is increased at a slower stirring speed, the capsule size becomes fine at a faster stirring speed. If the size of the microcapsules is less than 0.1 micrometer, if there are sharp scratches such as scratches or knives, the microcapsules do not burst and self-repairing effect is not obtained. If the size of the microcapsules exceeds 50 micrometers, the thickness of the film should be increased. It is not desirable to have.

Further, the process comprises the step of separating the formed self-contained microcapsules on the media solution to purify the capsule into a powder form.

Preparation of the microcapsules included in the self-maintaining surface treatment composition of the present invention can be prepared through the steps as described above, but can be obtained by controlling a variety of conditions through any microcapsules manufacturing method, emulsion polymerization method or in the interface It is preferable to manufacture by law.

That is, microencapsulation by direct polymerization of methylmethacrylate, microencapsulation by PVA crosslinking, microencapsulation with diacids and polyols, microencapsulation with oil / water emulsions, microencapsulation with epoxy surface hardening, interfacial degeneration Microcapsules may be obtained through various techniques, such as a polyurethane manufacturing method using a law.

However, the most effective microencapsulation method is to form microcapsules through the emulsion polymerization method and the interfacial polymerization method.

It is possible to obtain a microcapsule which is included in the surface treatment composition by the above method and exhibits self-maintainability of the present invention. Such microcapsules may be dispersed in an organic resin of an oily or aqueous type of epoxy, silane, alkyd, acrylic, urethane, or polyethylene-acrylate to form a surface treatment composition of an organic or organic / inorganic composite resin.

By coating the surface treatment composition on the surface of the metal by a conventional surface treatment method such as roll coating, spray coating, or immersion coating method, a surface treatment steel sheet having self repairability can be manufactured. The surface treatment film of the metal surface may be coated to have a dry film thickness of 10-100 micrometers.

The steel sheet treated with the surface treatment agent including the self-maintaining microcapsules of the present invention has a self-maintenance effect by forming a new film on the surface of the steel sheet exposed by impact because the inorganic substance, which is a core material, flows to the outside when the microcapsule bursts during an external impact. To provide.

According to the present invention, when the inorganic compounds such as cerium compound and magnesium compound are dissolved in a media solution such as chlorobenzene or alkyl acetates to prepare a self-retaining microcapsule by the method of the present invention, the cerium of the microcapsule core portion is 3 The valent ions and the magnetic ions are present in an ionized state such as divalent ions.

At this time, the trivalent cerium ions easily react with a metal to form a cerium-metal compound, and the outermost surface of the cerium-metal compound has a cerium-based outermost layer and cerium hydroxide as a main component. A metal compound is formed, which forms a self-repairing effect (film formation on the damaged metal surface).

When magnesium is introduced into the cell, divalent magnesium ions have an effect of suppressing the corrosion rate of zinc, especially when the base metal is zinc, and provides a self-repairing effect by forming a magnesium-metal compound.

Hereinafter, an Example is given and this invention is demonstrated more concretely. However, the following examples show one preferred embodiment of the present invention, and therefore are not intended to limit the present invention.

Example

urethane Prepolymer  Produce

To 9 mol of cyclohexane, 0.09 mol of toluene diisocyanate (TDI) was added, stirred and dissolved at 80 ° C., and then 0.04 mol of butanediol was added dropwise to less than 5 ml / min for 24 hours to prepare a polyurethane prepolymer. .

Preparation of Micro Capsules

Example  One

Cerium nitrate was dissolved well in chlorobenzene at 3% concentration and then added to the polyurethane prepolymer solution prepared above.

0.5 mol, 0.03 mol, and 0.01 mol of ethylene glycol, polyglycol, and diamine, which are used as chain extenders in the interfacial polymerization reaction of 1% by weight of polyvinyl alcohol and urethane interfacial polymerization, as a dispersing agent, were added to 1L of distilled water and stirred well. The polyurethane prepolymer was dropwise added thereto to prepare a microcapsule. At this time, the dropping rate was set to 10 ml per minute, and the stirring speed was set to 900 rpm to control the size of the microcapsules to 2-7 micrometers.

Example  2

Magnesium hydroxide salt was dissolved in alkylacetate at 3% concentration and then added to the prepared polyurethane prepolymer solution.

0.5 mol, 0.03 mol, and 0.01 mol of ethylene glycol, polyglycol, and diamine, which are used as chain extenders in the interfacial polymerization reaction of 1% by weight of polyvinyl alcohol and urethane interfacial polymerization, as a dispersing agent, were added to 1L of distilled water and stirred well. The polyurethane prepolymer was dropwise added thereto to prepare a microcapsule. At this time, The volume of the microcapsules was controlled to 2-7 micrometers at 10 ml / min and the stirring speed was 900 rpm.

Fabrication of self-retaining surface treated steel sheet

Comparative example  One

The surface treatment composition of the epoxy resin was coated on a degreasing electrogalvanized steel sheet (0.8 × 80 × 750 mm) to a thickness of 10 micrometers by a roll coating method, and then dried to prepare a surface treated steel sheet.

Example  3

The microcapsules of which the core material obtained in Example 1 is a cerium compound are added to and dispersed in a surface treatment composition of an epoxy resin on a degreasing electrogalvanized steel sheet (0.8 × 80 × 750 mm) and applied to a thickness of 10 micrometers by a roll coating method. After drying to prepare a surface-treated steel sheet.

Example  4

The microcapsule, which is a magnesium compound, obtained in Example 2 on the degreasing electrogalvanized steel sheet (0.8 × 80 × 750 mm) was added to and dispersed in a surface treatment composition of an epoxy resin, and applied to a thickness of 10 micrometers by a roll coating method. After drying to prepare a surface-treated steel sheet.

Self Conservation and Corrosion Resistance Evaluation

Corrosion resistance and self-repair effect of the surface treated steel sheets prepared in Comparative Examples 1, 3 and 4 were measured.

Corrosion resistance was tested by the salt spraying condition of ASTM B117, and the specimens were cut in 12 hours and then immersed in 0.1 N aqueous sodium chloride solution for 12 hours to observe self-repair effect.

Cerium trivalent (Example 3) or magnesium divalent (Example 4) ions stored in the capsule in the cut part (damage part) flow out as the microcapsule breaks and reacts with the surface of the galvanized steel sheet to form a cerium-metal compound or Formation of magnesium-metal compound will suppress the occurrence of white rust in the damaged part, which proves to have a self-repair effect.

division Corrosion resistance (white rust occurrence time) Self-conservability (white or white) Comparative Example 1 48 Occur Example 3 72 Not Occurred Example 4 60 Not Occurred

As can be seen from Table 1, Example 3 and Example 4 is excellent in corrosion resistance compared to Comparative Example 1. This is because the distributed self-repairing capsules expanded the penetration path of external corrosion factors.

In addition, as a result of immersing the sheathed specimen in 0.1 N sodium chloride solution for 12 hours, Comparative Example 1 produced white blue (zinc plant) in the damaged part, and no self-repairing effect was observed, whereas in Example 3 and Example 4 Not observed. This is because the cerium and magnesium ions in the self-repair capsule were broken by the sheath and flowed out to the damaged part to react with zinc to form a protective film.

BRIEF DESCRIPTION OF THE DRAWINGS The steel plate coated with the self repair surface treatment composition of this invention is a schematic diagram which shows the concept of self repair.

2 is a schematic schematic view of the microcapsules of the present invention.

[Description of Main Parts of Drawing]

One… … Microcapsules 2... … Shell

3 ... … Core material of inorganic compound 4. … Organic resin

5... … Steel sheet 6.. … Self-Retaining Resin Film

7 ... … Surface treatment

Claims (16)

In the surface-treated steel sheet coated with a surface-treated coating, the coating is formed from a resin composition containing a core-shell microcapsules and organic resin, the microcapsules as a core material in the polymer shell as a core material, cerium, magnesium, vanadium, A surface-treated steel sheet coated with a film having self-repair against damage, comprising a media solution and an inorganic compound selected from the group consisting of zirconium, lanthanum, cobalt and mixtures thereof. The method of claim 1, wherein the polymer shell is a compound selected from the group consisting of acrylic resins, epoxy resins, urethane resins, urea-formaldehyde, polyvinyl alcohol, polystyrene, polyethylene, biopolymers, polymer brushes, and mixtures thereof. Surface-treated steel sheet coated with a coating having a self-maintenance against damage. [Claim 2] The surface-treated steel sheet of claim 1, wherein the media solution is chloroform or alkyl acetate. The coated steel sheet of claim 1, wherein the microcapsules have a size of 0.1-50 micrometers. The coating of claim 1, wherein the organic resin is an oily or aqueous organic resin of an epoxy resin, a silane resin, an alkyd resin, an acrylic resin, a urethane resin, or a polyethylene-acrylate resin. Surface treated steel plates. Including a core-shell structured microcapsules and organic resin, the microcapsules are inorganic compounds and media selected from the group consisting of cerium, magnesium, vanadium, zirconium, lanthanum, cobalt and mixtures thereof as core materials in the polymer shell. The resin composition for self-retaining surface treatment film formation of the steel plate containing a solution. delete delete delete delete delete delete delete delete delete delete

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