KR101502843B1 - Eco friendly coating method of steel - Google Patents

Abstract

The present invention relates to a construction method of coating a steel material using an eco-friendly heavy anticorrosion paint, which is eco-friendly and improves working environments and a paint-film performance, comprising a surface treating step of removing pollutant materials like loose coating, corrosive iron, dust, and emulsified powders on the surface of steel materials formed on bridges or structures; and a primer coating step of coating the steel surface treated from the surface treating step with primers. In the present invention, the introduction of a solvent-free epoxy based paint is allowed to improve the formation of films, working environment and a paint-film performance according to the uniform formation of the paint-film.

Description

{Eco friendly coating method of steel}

The present invention relates to a method of coating a steel material using an environmentally-friendly heavy-duty paint capable of improving work environment, improving coating performance, and improving work environment.

Recently, VOCs regulation on air pollution which is strengthened internationally is demanding development of environmentally friendly paint, and the tendency of accepting and pulverizing of oil paint which is conventionally used is rapidly proceeding. In addition, development of environmentally friendly paints is increasingly demanded in the metropolitan area where air quality pollution is a problem. Recently, workers in the workplace are threatening the health of paint painters by unprotected exposure of organic solvents. Especially, painting work in a confined space requires more water - based paint due to scattered smokes and fire hazards caused by organic solvents. When coated with ferrous metal, it has excellent auditory power even in the absence of rust-preventive pigments containing heavy metals such as chromium and lead. It has a certain level of auditory sensation when subjected to a special pretreatment, that is, a zinc phosphate or iron phosphate coating process Is desired. In the case of paints applied to general metal water, it is a prerequisite to improve corrosion resistance of metal products and to improve adhesion to various substrates and various top coatings if system paint is applied.

In general, steel structures including iron are exposed to corrosive environments in a natural environment. Therefore, in order to improve the weatherability of steel structures, it is common to perform corrosion prevention on the surface of steel structures to prevent corrosion.

The corrosion environments of steel structures are divided into dry corrosion and wet corrosion. Dry corrosion is corrosion caused by hot gas. Wet corrosion is caused by atmospheric corrosion, underwater corrosion (fresh water and sea water) Chemical corrosion (acid, alkali, salt) and underground corrosion. This corrosion can be expressed as follows.

The oxidation reaction at the anode: Fe → Fe + 2e-, reduction at the cathode: H ₂ O + 1 / 2O ₂ + 2e- → 2OH-, 2H + 2e → H ₂ , total continuous reaction: Fe + 2OH → Fe ) ₂ , 2Fe (OH) ₂ + 1 / 2O ₂ + H ₂ O → 2Fe (OH) ₃ The corrosion of the iron structure means that rust or red (Fe (OH) ₃ , Fe ₂ O ₃ ) , Which can be seen as oxygen (O ₂ ) and water (H ₂ O) in the air. Such corrosion tends to be accelerated by gas, seawater salinity, and chemical corrosion (acid, alkali, salt) at high temperatures. However, the existing invention uses a corrosion inhibitor, such as chromic acid and nitrite, , Phosphoric acid, etc., or metal plating methods using metal pigments such as Cu, Zn, Cr, and Ni, which have a tendency to ionize more than iron corrosion, such as Zinc Oxide, Oxide (Sacrificial anode) using an anode as an anode.

Korean Patent No. 0503561 discloses a coating composition for improving the corrosion resistance and durability of a steel structure, and a coating method using an aluminum oxide coating using the same, wherein a coating using zinc, chromium, nickel, aluminum oxide or the like is applied to form a metallic coating on a steel structure And by this sacrificial anode method, an aluminum oxide film can be effectively used to prevent corrosion of steel structures and to improve durability.

In addition, currently used inorganic end-of-life paint, chlorinated rubber-based paint, epoxy-based paint and the like are as follows.

1. Inorganic latex paint

The following are known as anti-corrosive paints with the year-end end as main antirust agent. Called zinc rich paint, which is made by putting a high concentration of zinc powder or zinc fine powder into a small amount of resin.

2. Chlorinated rubber-based coating

Chlorinated rubber coatings, which are generally used in heavy-duty coatings, have a high drying speed, good interlayer adhesion, and are resistant to contamination and coastal environments. In particular, chlorinated rubber coatings are superior in transparency and oxygen permeability to other paints due to their excellent coating properties, which is advantageous for coating steel structures such as containers and ships.

3. Epoxy coating

Epoxy-based anticorrosive coatings have widely used various polyamine compounds, especially aliphatic polyamine compounds, as curing agents for epoxy resins for room temperature curing.

However, the above paints have the following problems.

1. Inorganic latex paint

In the case of the inorganic end-of-life paint (zinc-rich paint), the ginkgust existing in the zinc oxide paint is corroded by oxygen or moisture, causing so-called white rust, Or defects such as poor adhesion are known. Such inorganic end-of-life paint is widely used as a primer in steel structures such as steel bridges, but it is preferable for a steel bridge specification that maintains high weatherability due to a coating film thickness that is thick and a resin content is small, not.

2. Chlorinated rubber-based coating

The chlorinated rubber coating has a disadvantage in that the appearance of the steel structure is deteriorated after a certain period of time after coating due to its low weather resistance.

3. Epoxy coating

The epoxy paint absorbs carbon dioxide or water vapor in the air to form a carbamate, thereby causing a cured coating to be whitened. When a water droplet comes in contact with the coating layer during curing, . When the coating film is overlaid, there is a problem that the interlayer adhesion of the coating film is lowered.

In order to overcome the above-mentioned problems, various polyamine compounds are used as various denaturing agents. Typical denaturing methods include denaturation by the reaction between the denaturation and the epoxy compound by the Mannich reaction of the phenolic compound and the carbonyl compound, Modification by reaction with a compound having a carboxyl group, modification by a Michael reaction with an acrylic compound, and the like are disclosed in JP-A-8-104738. However, the modified curing agent generally achieves satisfactory physical properties when applied at a temperature ranging from 20 to 40 캜. There is a problem in that the curing property of the coating film is insufficient at the winter season of 10 ° C or lower, particularly at a low temperature of 5 ° C or lower, and the modified product due to the Mannich reaction used in the conventional low temperature curing resin is also insufficient in the curability of the coating film

In order to solve the above problems, the steel coating method using the environmentally-friendly heavy-duty paint of the present invention is an environmentally friendly method of coating a steel material using an environmentally-friendly heavy paint, which can improve the working environment, The purpose is to provide.

The present invention can improve the film forming performance and the working environment by introducing a solvent-free non-solvent epoxy coating, and improve the coating performance due to the formation of a uniform coating film.

Especially, by introducing a water-soluble urethane coating material applied together with a solvent-resistant epoxy coating material, it is possible to improve the working environment and workability while being eco-friendly as well as protecting the solvent-resistant epoxy coating material.

In addition, the water-soluble urethane resin contained in the water-soluble urethane-based coating can be prepared through the urethanization reaction by introducing a tertiary alcohol to improve the water-dispersibility and to improve the working environment in the production of the water-soluble urethane resin have.

In addition, the water-soluble urethane-based paint has a viscosity control part introduced therein, which not only facilitates the water-solubilization but also prevents the surface of the steel from being deformed and stained during coating, It is a useful invention.

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

Generally, corrosion of steels is classified into dry corrosion and wet corrosion.

First of all, in case of dry type, high temperature oxidation and corrosion due to high temperature gas are included in the metal surface due to the corrosion occurring without the action of liquid water.

In the case of wet type, it is corrosion caused by contact with liquid water or electrolyte solution.

Such corrosion of the steel material has a great influence on the strength of the steel material. In particular, even if a new coating material is applied, it must be completely removed when the corrosion is in progress.

Therefore, in the present invention, an operation of removing foreign substances on the surface of a steel material formed on a bridge or a structure is preceded. (Surface Treatment Step)

The surface treatment step is to peel off the existing coating applied to the surface of the steel material and to remove contaminants such as rust and dust oil on the surface of the steel material generated at the position where the existing coating is excited.

In the present invention, since the work is performed by using a hand grinder including a diamond tip containing a diamond tip to which a dust collecting device is connected, after the pollutants on the surface of the steel material are blown and removed using high pressure water, In addition to the removal of pollutants, pollutants that are removed when the pollutants are removed are sucked through the dust collecting device mounted on the hand grinder, thereby improving the environment of the operator and improving the workability.

Next, the primer is applied to the work surface (steel surface) on which the surface treatment is completed as described above. (Primer application step)

Here, when the corrosion inhibitor is included in the primer, the corrosion of the surface of the steel material, which is further generated after the application of the primer, can be suppressed.

Next, a non-solvent epoxy coating material comprising a base and a curing agent is applied to the surface to which the primer is applied as described above. (Solvent-Free Epoxy Coating Step)

The solventless epoxy coating material is any liquid epoxy resin 67 selected from bisphenol A type liquid epoxy resin, bisphenol F type liquid epoxy resin, novolak type liquid epoxy resin, alicyclic liquid epoxy resin and glycidyl amine type liquid epoxy resin To 75% by weight of at least one selected from among glycidyl (meth) acrylate, poly (ethylene glycol), polypropylene glycol, neopentyl glycol, 1,6-hexanediol and trimethyrolpropane 20 to 28% by weight of a filler composed of at least one selected from the group consisting of silica, alumina, calcium carbonate, barium sulfate, magnesium oxide, talc, magnesium hydroxide, boron nitride, zinc oxide, , 30 to 40% by weight of a self-emulsifying amine, 12 to 22% by weight of a non-emulsified emulsion, and 43 to 53% by weight of water Made of a topic, the base resin, the curing agent 1 it is formed by mixing in a weight ratio of 1: 1.

Such solvent-free epoxy-based coatings are solvent-free using solvent-free epoxy resin as a subject, and are environmentally friendly, and workability can be improved.

In particular, the curing agent used in the present invention comprises a self-emulsifying amine and a non-self-emulsifying amine.

The self-emulsifying type amine has a hydrophilic main chain such as polyether introduced into an epoxy resin to react with excess amine, and has good hydrophilicity and excellent film-forming property, so that a uniform film can be obtained when dried.

In addition, the non-magnetic emulsified emulsion has hydrophilicity lower than that of the self-emulsifying type amine, but hydrophobic groups are introduced to improve the hardness of the coating film and prevent discoloration, so that the color can be expressed for a long time.

Here, the liquid epoxy resin of the above-mentioned subject matter is not limited, but the viscosity is preferably 1,000 to 12,000 MPS · S.

In addition to the divalent amine, it is also possible to add a tertiary amine liquid curing agent and an alkyl phenol as an accelerator to adjust the curing rate.

Next, a water-soluble urethane coating material is applied to the surface to which the solvent-resistant epoxy coating material is applied (water-soluble urethane coating material application step)

The water-soluble urethane paint is composed of a main part (A) and a viscosity adjusting part (B).

That is, the water-soluble urethane-based paint comprises (A1) 40 to 50% by weight of a water-soluble urethane resin containing a water-soluble urethane solid component, (A2) 12 to 20% by weight of a polyacrylic acid- (B1) 55 to 65% by weight of a water-soluble resin containing a water-soluble acrylic resin solid component, (B2) 4 to 8% by weight of a urea associative viscosity modifier, B3) 28 to 37% by weight of water, wherein the main component (A) and the viscous adjusting component (B) are mixed in a weight ratio of 1: 1, To 50 wt%, an ionic group forming compound 3 to 9 wt%, a tertiary alcohol 20 to 30 wt%, and an organic polyisocyanate 20 to 28 wt%.

A. Topics

 (A1) Water-soluble urethane-series resin

First, the water-soluble urethane-based resin (A1) contained in the main component (A) of the water-soluble urethane-based paint described above is prepared by applying a tertiary alcohol in the process of urethane-forming an organic polyisocyanate and a polyol to obtain an urethane- And a water-soluble urethane-based resin can be produced in a state in which the working environment is improved as compared with the case of using a conventional MMP.

Here, the organic polyisocyanate may be aromatic, aliphatic or alicyclic.

Examples of the aromatic polyisocyanate include a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, 4,4'-diphenyl-methane, diisocyanate and the like have.

Examples of the aliphatic polyisocyanate include hexamethylene, diisocyanate, trimethyl hexamethylene diisocyanate, and the like.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, hexane-1,4-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated TDI, and the like. have.

In particular, these organic polyisocyanates can be used singly or as a mixture, and if necessary, a small amount of a multifunctional isocyanate, which is a reaction product with a trimer or trimethylolpropane, can be used in parallel.

Next, the polyol which reacts with the above-mentioned polyisocyanate is not particularly limited as long as it is a compound having at least two hydroxyl groups in one molecule.

Examples thereof include polyetherpolyol, polyester polyol, polycarbonate polyol, and poly butadiene polyol.

The average molecular weight of such polyols is usually 500 to 6,000, preferably 500 to 3,000.

When the mixing ratio of the polyol is less than the critical value, the function as a polyol is not exerted. If the mixing ratio of the polyol exceeds the upper limit, the water dispersibility of the urethane prepolymer is lowered, Mechanical properties and durability are deteriorated.

On the other hand, the present invention includes an ion forming compound for imparting the self-emulsifying property to the urethane produced by the urethane formation reaction between the organic polyisocyanate and the polyol.

The ionic grouping compound generally has two or more active hydrogen groups reacting with isocyanate in the molecule, so that the ionic groups are contained in the molecular chain of the urethane prepolymer and are easily emulsified by water.

Such an ion forming compound may be any compound selected from the group consisting of a compound containing a carboxyl group and a compound having a sulfonic acid group, or an anionic ion forming compound of an anion type selected from the group consisting of N-methyldiethanolamine, N-methylethylalcoholamine and triethylalcoholamine An ion-forming compound which is any one of cation-type ion-forming compounds selected is used.

Examples of the compound containing a carboxyl group in the anion type ion forming compound include dimethylol propionic acid, dimethyrol acetic acid, dimethyrol butanoic acid, dimethyrol butanoic acid, dimethyrol alkanoic acid such as dimethyrononanoic acid, 1-carboxy- 1,5-penthylenediamine, dihydroxybenzoic acid, ester compounds of polyoxypropylene triol with maleic anhydride or phthalic anhydride, and polyvalent amino acid compounds such as lysine and arginine.

Here, when a compound containing a carboxyl group is used, amines such as triethylamine, ethyl alcohol amine, diethanolamine, triethyl alcohol amine, triethylenediamine, dimethylaminoethyl alcohol and the like can be used as a neutralizing agent for forming and ionizing a carboxyl group Alkali metal compounds such as ammonia, sodium hydroxide, sodium carbonate, sodium hydrogencarbonate, and potassium hydroxide may be used. In this case, the neutralization ratio with respect to the carboxyl group is usually 50 to 120 mol (mole)%.

Examples of the compound having a sulfonic acid group include N, N-bis (2-hydroxyethyl) aminoethylsulfonate tetramethylammonium salt, N, N-bis (2-hydroxyethyl) amino Tetraethylammonium salt of ethylsulfonic acid, and benzyltriethylammonium salt of NN-bis (2-hydroxyethyl) aminoethylsulfonic acid.

Since the compound containing a sulfonic acid group is hardly dissolved by an organic solvent, it may be difficult to introduce it into a urethane when preparing a prepolymer. In this case, a compound containing a sulfonic acid group at the chain extension may be dissolved in the urethane resin by reacting with an isocyanate group at the end of the prepolymer. At this time, since the sulfonic acid base already contains a base, not.

Examples of cationic ionic compounds include N-methyldiethanolamine, N-ethylethanolamine, and triethanolamine. When these tertiary nitrogen compounds are used, hydrochloric acid, acetic acid, propionic acid, and lactic acid may be used as neutralizing agents, and tertiary nitrogen may be quaternarized with an alkyl halide or the like.

Examples of tertiary alcohols used as solvents in the reaction of the urethane prepolymer include tert-butyl alcohol (having a solidus temperature of 25.5 ° C and boiling point of 82.8 ° C), tert-amyl alcohol (solidification point of -8.4 ° C, boiling point of 102 ° C) (Solidification point -44 占 폚, boiling point 167.9 占 폚),? -Terpineol (solidification point 38-40 占 폚, boiling point 219-221 占 폚).

Among them, diacetone alcohol is most suitable because the solvent has a low freezing point and boiling point and the solubility of the urethane resin raw material and the film-forming property of the aqueous urethane resin are good.

When the tertiary alcohol is mixed below the critical value, the viscosity of the urethane prepolymer is lowered and the effect of imparting the film formability is lowered. On the contrary, when the critical value is exceeded, water stability and film dryness There is a problem that it is deteriorated.

 (A2) Polyacrylic acid-based viscosity adjusting agent

The polyacrylic acid viscoside adjuster is for improving the storage stability by controlling the viscosity of the subject, and it is included so as to form a constant coating film by preventing staining phenomenon due to uniform dispersion of the water-soluble urethane coating material to be produced, As the acrylic acid viscosity adjusting agent, sodium polyacrylate and a polyacrylic acid- (meth) acrylic acid ester copolymer may be used.

Here, when the polyacrylic acid-based viscosity adjusting agent is mixed below the critical value, the storage stability of the subject (A) and the flowability of the continuous coating operation of the water-soluble urethane-based paint are lowered to make it difficult to form a beautiful appearance, The mixing property with the resin is not good, and in particular, there arises a problem such as occurrence of a stain phenomenon when applied to a steel material.

 (A3) Pigment

The pigments may use pigments that are known to be included for a variety of color expressions.

Examples of the pigment include metal oxide pigments such as titanium oxide and iron oxide, composite oxide pigments such as titanium yellow, carbon black, azo pigments, quinacridone pigments, perylene pigments, perinone pigments, Pigments, aluminum, copper, zinc, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, or the like may be used in combination of one or more depending on the color or coating performance.

B. Viscosity Adjustment

The viscosity adjusting part in the present invention is used in accordance with the coating environment and the flow characteristics by mixing with the subject A immediately before coating on the surface of the steel material so as to maintain the storage stability and prevent the aggregation phenomenon and the stain phenomenon To form a coating film having a uniform thickness and to thereby provide a beautiful appearance.

(B1) a water-soluble resin containing a water-soluble acrylic resin solid component

 The water-soluble resin includes a water-soluble acrylic resin and is constituted so as to prevent the occurrence of unevenness of the coating film of the water-soluble urethane-based paint and to form a good appearance.

Such a water-soluble resin includes a water-soluble acrylic resin, which may further comprise an acrylic resin emulsion.

When such a water-soluble resin is formed below the critical value, the intrinsic purpose for preventing the stain phenomenon can not be achieved, and if it exceeds the critical value, it is difficult to obtain a further increased effect.

(B2) Urethane association type viscosity adjusting agent

The urethane associative viscous modifier in the present invention is included to improve the flowability of the water-soluble urethane-based paint to prevent sagging of the paint. When the viscosity is less than the threshold value, improvement in the sagging property is not achieved. A phenomenon may occur.

On the other hand, after application of the paint as described above, the surface protection agent for protecting the paint can be applied to the upper side of the paint to complete the application. (Step of applying the surface protective agent)

While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (5)

A surface treatment step of removing contaminants such as excavated rust, rust, dust and oil in the surface of a steel material formed on a bridge or a structure;
Applying a primer to the surface of the surface-treated steel material;
67 to 75% by weight of at least one liquid epoxy resin selected from the group consisting of bisphenol A type liquid epoxy resin, bisphenol F type liquid epoxy resin, novolak type liquid epoxy resin, alicyclic liquid epoxy resin and glycidyl amine type liquid epoxy resin, A glycidyl ether reactive diluent 2 - 5 selected from the group consisting of ethylene glycol, polypropylene glycol, neopentyl glycol, 1,6 hexanediol, and trimethyrolpropane; And 20 to 28% by weight of a filler consisting of at least one selected from the group consisting of silica, alumina, calcium carbonate, barium sulfate, magnesium oxide, talc, magnesium hydroxide, boron nitride, zinc oxide,
A solvent-free epoxy coating material comprising a curing agent composed of 30 to 40% by weight of a self-emulsifying amine, 12 to 22% by weight of a non-magnetic emulsion emulsion and 43 to 53% by weight of water, A solvent-free epoxy-based coating material applying step
A main component comprising 40 to 50% by weight of a water-soluble urethane-based resin containing a water-soluble urethane-based resin solid, 12 to 20% by weight of a polyacrylic acid-based viscosity adjusting agent, 1 to 3% by weight of a pigment and 35 to 42%
A water-soluble urethane coating material comprising a water-soluble urethane-based coating material composed of 55 to 65% by weight of a water-soluble resin containing a water-soluble acrylic resin solid component, 4 to 8% by weight of a urea association type viscosity adjusting agent, and 28 to 37% , Which is characterized by being made of environmentally friendly heavy paint coating method.
The water-soluble urethane resin composition according to claim 1, wherein the water-soluble urethane resin comprises 40 to 50% by weight of a polyol, 3 to 9% by weight of an ionic grouping compound, 20 to 30% by weight of a tertiary alcohol, 28% by weight based on the total weight of the steel.
3. The method according to claim 2, wherein the ion forming compound is selected from the group consisting of a compound containing a carboxyl group and a compound having a sulfonic acid group, or an ionic group forming compound of an anion type selected from the group consisting of N-methyldiethanolamine, N-methylethyl alcohol amine, Wherein the ion-forming compound is any one of cation-type ion-forming compounds selected from the group consisting of methyl, ethyl, propyl, isopropyl, and tert-butyl alcohol.
The coating composition according to claim 1, wherein the polyacrylic acid-based viscosity adjusting agent is a polyacrylic acid sodium carbonate or a polyacrylic acid- (meth) acrylic acid ester copolymer. Steel painting method construction method.
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