KR20030014811A - A method for manufacturing paints for preventing corrosion using water-soluble polyanilin salt - Google Patents

Abstract

PURPOSE: Provided is a process for producing a paint for preventing metal corrosion by using a water-soluble polyaniline salt, which can improve work-environment, work-efficiency, and environmental pollution and has excellent metal corrosion preventing effect. CONSTITUTION: The process comprises the steps of: adding 5-90wt% of polyvinyl alcohol to polyaniline water solution obtained by substituting water-soluble conductive polyaniline salt by sulfonic acid; blending the resultant with water-soluble poly(3,4-ethylenedioxy)thiophene in the weight ratio of 50:50 in the presence of a polar solvent such as dimethyl sulfoxide(DMSO), N,N'-dimethylformamide(DMF), N-methyl-2-pyrrolidone(NMP), and ethyleneglycol(EG).

Description

A method for manufacturing paints for preventing corrosion using water-soluble polyanilin salt}

The present invention provides a coating for preventing metal corrosion by blending a water-soluble conductive polymer polyaniline salt or water-soluble polyaniline salt with a water-soluble poly (3,4-ethylenedioxy) thiophene and coating it on the surface of the metal. The present invention relates to the production of water-soluble polyaniline substituted with sulfonic acid in polyaniline salts, without using polyaniline salts doped with soluble proton acids in conventional organic solvents, to prevent corrosion through blends with water-soluble functional polymers. Functional polymers for preparing paints, blends of water-soluble polyaniline and water-soluble poly (3,4-ethylenedioxy) thiophene, blends of water-soluble polyaniline and water-soluble poly (3,4-ethylenedioxy) thiophene added with a polar solvent Can be added to the coating on the metal surface to prevent corrosion of the metal It is to provide a method for producing a paint.

In general, the corrosion of metal is because the metal atoms leave the crystal lattice and cause a wide oxidation reaction. To prevent the corrosion, it is necessary to detect the forces and rate of change in advance and study the factors that control the corrosion. Research should be made on how to prevent change.

Corrosion also occurs slowly in hulls, engines, boilers, offshore structures, underground burials, and chemical equipment, but in general, about 10 to 20% of iron is consumed by corrosion. The loss is as much as 2-3% of GNP in western industrial countries. Corrosion, therefore, is called a natural disaster or a flameless fire and causes great loss to human society. Therefore, it is extremely important to study corrosion protection and prevent corrosion loss in advance.

Corrosion protection of metals can be controlled in a variety of ways, including the use of corrosion inhibitors or changes in the corrosion medium. Corrosion inhibitors include single substances or mixtures that can control or reduce corrosion at certain concentrations, and the most efficient corrosion inhibitors are organic compounds with π-double bonds (conductive polymers). The efficiency of the organic compound acting as a corrosion inhibitor is determined by the degree of adsorption of the organic compound to the metal surface and the ability of the organic compound to remove water from the metal surface. Adsorption of organic compounds is affected by functional groups such as = NH, -N = H-, -CHO, R-OH and -R = R- in the molecular structure.

A study on the adsorption area and molecular weight of corrosion inhibitors was published in 1960. Soluble polyaniline has a great effect on corrosion inhibition by covering the surface of the metal or forming a very thin film on the surface of the metal.

The diffusion coefficient of ions, water, oxygen, etc. must be zero in the polymer material in order to form an ideal protective film against electrochemical corrosion or air resistance.

In 1985, De Berry presented an anode method that reduces the rate of corrosion in aqueous sulfuric acid solutions by studying the electrical deposition of polyaniline on stainless steel.

As such, the conductive polymer has attracted attention as an anti-corrosion coating material.

This is because polyaniline is a material that has electrical and ionic conductivity and can also exhibit insulator properties. Among the conductive polymers that can be used as a corrosion preventing material, polyaniline, especially polyaniline, is easy to make synthesis and derivatives, and has been widely researched worldwide because of its advantages of high electrical conductivity, high thermal stability, low atmospheric stability, and low price.

Polyaniline is an aromatic compound in which the polymer itself is nonpolar, and it has been reported that until about 10 years, it is insoluble in most organic solvents or water regardless of the synthesis method. However, studies on solubility continue to report that polyaniline (emeraldine base) is partially dissolved in 80% aqueous acetic acid solution, 88% aqueous formic acid solution, DMSO. In 1988, M and Angelopoulos reported that polyaniline (emeraldine base) has improved solubility in NMP (N-methyl-2-pyrrolidinone), which is a relatively weak polar solvent. It became possible. In 1989, A. G Macdiarmid et al. Found that derivatives substituted with large substituents (-CH ₃ , -OCH _3, etc.) on the benzene ring weakened the chain-to-chain bonds, resulting in a significant increase in solubility in common organic solvents. But benzene ring under the influence of large substituents

Twisting between them lowered the electrical conductivity.

In 1990, Cao et al. Dissolve polyaniline (emeraldine base) in concentrated sulfuric acid, and processed conductive fibers therefrom to have an electrical conductivity of about 200 S / cm, followed by 1992 camphorsulphonic acid (HCSA) and dodecylbenzenesulfo. Polyaniline doped with functional acids such as nic acid (HDBSA) not only increases the solubility in weak or very nonpolar solvents such as m-cresol, but also increases the crystallinity and electron mobility of the polymer by the action of counterions. It was reported to exhibit high electrical conductivity of ˜400 S / cm. In addition, it has been branded with commercially available polymers to significantly improve the processability. However, industrial applicability (anticorrosion materials) using polyaniline salts soluble in organic solvents places a lot of restrictions on the use of highly carcinogenic organic solvents due to increased regulations on VOCs and growing interest in green rounds. I am getting it.

Therefore, researchers are working to improve the processability of polyaniline for low-toxic polar solvents such as water and alcohol.

The object of the present invention is to solve the problems of the prior art as described above, to prepare a coating for preventing corrosion through blending a water-soluble polyaniline salt with a water-soluble functional polymer, or water-soluble polyaniline and water-soluble poly (3,4-ethylenedioxy) Water-soluble polyaniline with a thiophene blend and a polar solvent and a water-soluble poly (3,4-ethylenedioxy) thiophene blend with a functional polymer added to the coating on the surface of the metal to prevent corrosion of the metal In providing paint.

The present inventors, unlike the conventional anti-corrosive material using a polyaniline salt doped with a proton acid soluble in an organic solvent, using a water-soluble polyaniline as described above, to prepare a coating for preventing corrosion through a blend with a water-soluble functional polymer, A blend of a water-soluble polyaniline and a water-soluble poly (3,4-ethylenedioxy) thiophene and a paint containing a functional polymer added to a blend of a water-soluble polyaniline and a water-soluble poly (3,4-ethylenedioxy) thiophene with a polar solvent. Manufactured and coated on metal to prevent corrosion of metals, thereby making it possible to overcome environmental problems such as work environment, work efficiency, industrial hazards, air, water quality, soil, etc. The invention has been completed.

1 is a UV graph of the near infrared region according to the addition of a water-soluble poly (3,4-ethylenedioxy) thiophene to the water-soluble polyaniline solution used in the present invention.

2 is a paint (c) using a water-soluble polyaniline salt prepared according to the present invention, a water-soluble polyaniline salt and a water-soluble poly (3,4-ethylenedioxy) thiophene by mixing 50:50 weight ratio. It is a graph showing the results of the Tafel plot measurement in 3% NaCl solution of the coated iron (a).

The present invention is to prepare a water-soluble polyaniline substituted with a polyaniline salts sulfonic acid, to prepare a coating for preventing corrosion through blending with a water-soluble functional polymer, or to blend a water-soluble polyaniline with a water-soluble poly (3,4-ethylenedioxy) thiophene. To prepare paints containing functional polymers in blends of water-soluble polyaniline and water-soluble poly (3,4-ethylenedioxy) thiophene with polar solvent and coating them on the surface of metal to prevent corrosion of metal A method is provided.

Corrosion-resistant paints using the water-soluble conductive polymer prepared by the method according to the present invention can improve the work environment, work efficiency, compared to the conventional anti-corrosive paints using soluble polyaniline salt in organic solvents, industrial hazards and air and water quality Not only can improve environmental problems such as soil and soil, but also has great advantages in terms of processability and corrosion effects.

Polyaniline salts doped with conventional amphoterics have excellent thermal atmospheric stability and have electrical conductivity, but they do not dissolve well in general polar organic solvents due to the strong attraction between chains or chains. Polyaniline was prepared, dissolved and treated in n-methylpyrrolidone (NMP) and then imparted with conductivity. In this way, after the polyaniline base is prepared, in the case of having conductivity, a good quality film can be obtained, but there is a disadvantage in that workability is cumbersome.

In the case of polyaniline salts doped with protonic acids such as camphorsulphonic acid (HCSA) and dodecylbenzenesulphonic acid (HDBSA), the polymer itself is a non-polar aromatic compound, which is dissolved in a small amount in a nonpolar solvent, but in a polar solvent such as alcohol and water. It does not dissolve.

In the present invention, by replacing sulfonic acid with polyaniline salts, water-soluble polymers such as water-soluble polyaniline salts and polyvinyl alcohols are blended to prepare anticorrosion paints, and water-soluble polyaniline and water-soluble poly (3,4-ethylenedioxy) thiophene. Paint

And a small amount of a polar solvent is added to the paint mixed with the water-soluble polyanile and the water-soluble poly (3,4-ethylenedioxy) thiophene to prepare a corrosion preventing paint. .

It is seen that the electrical conductivity increases from 0.02 S / cm to 5 S / cm by adding water-soluble poly (3,4-ethylenedioxy) thiophene in a weight ratio to the anticorrosive paint using the water-soluble polyaniline salt prepared according to the present invention. UV absorbance measurement to the near infrared region can be seen that the absorption in the near infrared region is increased.

In addition, a solution containing a water-soluble polyaniline salt and a water-soluble poly (3,4-ethylenedioxy) thiophene in a 50:50 weight ratio is dimethyl sulfoxide (DMSO), N, N'-dimethylformamide (DMF), With the addition of N-methyl-2-pyrrolidinone (NMP), ethylene glycol (EG), the electrical conductivity increases from 0.02 S / cm to 250 S / cm.

In the present invention, in order to determine the corrosion characteristics of the iron surface coated with the anti-corrosion paint using a water-soluble conductive polymer, the results were compared to the pure iron surface at a concentration similar to that of general seawater. The iron used for the experiment used purity of 99.9% and thickness 1mm. As a solution, 3% NaCl was used, and N ₂ gas was sufficiently supplied before the experiment to inhibit the access of oxygen gas, which may cause corrosion damage on the iron surface.

As a result of the measurement of the Tafel plot, the paint using water-soluble polyaniline salts showed higher corrosion voltage and corrosion current than uncoated iron. In the case of iron coated with a paint using a mixture of (3,4-ethylenedioxy) thiophene in a 50 to 50 weight ratio, the corrosion voltage increases and the corrosion current decreases compared to the paint using a water-soluble polyaniline salt. The prevention effect was found to be more excellent.

Hereinafter, according to the method of the present invention, a method for preparing a corrosion preventing paint using a conductive polyaniline salt soluble in an alcohol which is an environmentally friendly solvent will be described in detail according to an embodiment.

Example 1.

Aniline (C ₆ H ₅ NH ₂ , 99.5% manufactured by Aldrich Co., Ltd.)

Used after purification. As an oxidizing agent, ammonium persulfate [(NH ₄ ) ₂ S ₂ O ₈ : manufactured by Aldrich Co.] was commercially available and used as it is.

First, 500 ml of 1 mol hydrochloric acid solution was prepared, 20 ml of aniline was dissolved in 300 ml of 1 mol hydrochloric acid solution, and then maintained at 0 ° C. (0 ° C. to 60 ° C.). Separately, 1 mol of 11.5 g of ammonium persulfate [(NH ₄ ) ₂ S ₂ O ₈ ] 200 mol was dissolved in a hydrochloric acid solution and kept at 0 ° C. (0 ° C. to 60 ° C.) The solution containing the oxidant was aniline-containing solution. Was added slowly over 2 minutes using a separatory funnel.

After 90 minutes, the precipitate was filtered in a funnel connected with an aspirator using Whatman filter paper (# 1), and the precipitate was washed with each of the proton acids used. 10 ml again of this filtered sample. After making the turbid solution with 1 mole hydrochloric acid, it was added to 500 ml 1 mole hydrochloric acid solution and stirred with a magnetic paddle and left for 15 hours, followed by filtering in a funnel connected with an aspirator using Wortman manure paper (# 2). . At this time, 2 liters of 1 mol hydrochloric acid was used to wash the filtrate until it was completely colorless. The filtered sample was dried through a vacuum dryer to prepare a polyaniline salt.

9 g of the polyaniline salt powders obtained above were stirred and dispersed in 270 ml of 1,2-dichloroethane and heated to 80 ° C. Separately, 21.8 g of chlorosulfuric acid was dissolved in 15 ml of 1,2-dichloroethane and added slowly for 30 minutes. After the addition was completed, the reaction was performed again at 80 ° C. for 5 hours. After cooling, the reaction product was filtered and the filtered sample was stirred and dispersed in 400 ml of a mixed solution of water and 2-propanol (1/9 wt%), followed by a hydrolysis reaction at 60 ° C for 4 hours. The green solution obtained after cooling was filtered to obtain a green powder. The obtained green powder was dried through a vacuum dryer to prepare a water-soluble polyaniline salt powder of general formula (I). After dissolving the water-soluble polyaniline salt powder of the general formula (I) prepared above in water, 5 to 90% by weight of polyvinyl alcohol which is a water-soluble polymer was added to prepare a coating for preventing corrosion.

Example 2.

The water-soluble poly (3,4-ethylenedioxythiophene) solution was purchased as Bayer "Baytrot1 P".

The polyaniline salt powder obtained in Example 1 was dissolved in water to prepare a 1 wt% aqueous solution. A water-soluble poly (3,4-ethylenedioxythiophene) solution was prepared by mixing 1 wt% of "Baytron P" with an aqueous polyaniline salt solution and a poly (3,4-ethylenedioxythiophene) solution in a weight ratio to prepare a coating for preventing corrosion. It was.

By adding a water-soluble poly (3,4-ethylenedioxythiophene) solution to 1 wt% of a water-soluble polyaniline solution, as shown in Table 1, it was possible to prepare an anti-corrosion paint having improved electrical conductivity.

Table 1. Electrical Conductivity with Addition of Water-Soluble Poly (3,4-ethylenedioxythiophene) Solution

Changing state:

Water Soluble Polyaniline: Water Soluble Poly (3,4-ethylenedioxythiophene) wt / wt% Electrical Conductivity (S / cm) 0: 100 5 20:80 2 40:60 0.8 50:50 0.4 60:40 0.09 80:20 0.06 100: 0 0.02

Example 3.

Polyvinyl alcohol (PVA) (or polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polyvinyl acetate, which is a functional polymer in the mixed aqueous solution of Example 2), Polyacrylonitrile (PAN), Acrylonitrile-butadiene-styrene (ABS), Nylon (Nylon 6 · 66), Polyurethane, Ethoxy, Acrylic Resin, Polyacrylic Acid, Polymethacrylic Acid, Styrene-maleic Anhydride Coalescing, polystyrene sulfonic acid, polyethylene imine, polyvinyl pyridine, polydiethylamino ethylacrylate, polyacrylamide, polyvinylpyrrolidone, alkyds, polyethylene glycol, polyethylene oxide, polyvinyl methyl ether, carboxy methyl cellulose (CMC), methyl cellulose (MC), ethyl cellulose (EC), hydroxy ethyl cellulose (HEC), cellulose acetate phthalate (CAP), stearyl cellulose, water soluble acrylic, right Carbon, and epoxy resin, etc.) 40 wt% (or from the addition of 0.01 50 wt%) to prepare a corrosion-proof coating material.

Example 4.

Bayer "Baytron P" was purchased and used as a water-soluble poly (3,4-ethylenedioxythiophene) solution. As the organic solvent, "TCI" (manufactured by Aldrich) was used as it is.

The polyaniline salt powder prepared in Example 1 was dissolved in water to prepare a 1 wt% aqueous solution. A water-soluble poly (3,4-ethylenedioxythiophene) solution was mixed with an aqueous solution of "Baytron P" 1 wt% polyaniline salt and a poly (3,4-ethylenedioxythiophene) solution at 50:50, followed by mixing 12 g of the aqueous solution was added to a 50 ml beaker and stirred with a magnetic spoon. 2 g of dimethyl sulfoxide (DMSO) (or organic solvents N, N'-dimethylformamide (DMF), N-methyl-2-pyrrolidinone (NMP), ethylene glycol (EG)) were prepared from polyaniline and poly (3, The mixture is added to a 500 ml beaker containing 12 g of 4-ethylenedioxythiophene) mixed aqueous solution, followed by stirring with a magnetic spoon. The mixed solution is placed in an ultrasonic cleaner for at least 1 hour to prepare a complete mixed solution.

A good film was prepared on a glass plate by a solution casting method using an organic solvent of DMSO, polyaniline, and poly (3,4-ethylenedioxythiophene) mixed solution (mixing ratio of 1 to 6 by weight). The electrical conductivity of the polyaniline and poly (3,4-ethylenedioxythiophene) mixed aqueous solution film with each polar organic solvent added was 253 to 220 S / cm, and the existing water-soluble polyaniline and poly (3,4-ethylenedioxy Thiophene) [Baytron P] film showed electrical conductivity higher than 0.08 S / cm, 0.5 S / cm.

Table 2. Electrical conductivity of polyaniline and poly (3,4-ethylenedioxythiophene) mixed aqueous solution film with polar organic solvent added:

Water Soluble Polyaniline: Water Soluble Poly (3,4-ethylenedioxythiophene) Electrical Conductivity (S / cm) DMSO DMF NMP EG 20:80 253 224 210 220 40:60 210 183 160 175 50:50 163 131 109 117 60:40 121 67 58 66 80:20 65 23 15 21

Example 5

Polyvinyl alcohol (PVA) (or polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), polyvinyl acetate, which is a functional polymer in the mixed aqueous solution of Example 4), Polyacrylonitrile (PAN), Acrylonitrile-butadiene-styrene (ABS), Nylon (Nylon 6 · 66), Polyurethane, Epoxy, Acrylic Resin, Polyacrylic Acid, Polymethacrylic Acid, Styrene-maleic Anhydride Copolymer , Polystyrene sulfonic acid, polyethylene imine, polyvinyl pyridine, polydiethylamino ethylacrylate, polyacrylamide, polyvinylpyrrolidone, alkyds, polyethylene glycol, polyethylene oxide, polyvinyl methyl ether, carboxy methyl cellulose (CMC ), Methyl cellulose (MC), ethyl cellulose (EC), hydroxy ethyl cellulose (HEC), cellulose acetate phthalate (CAP), stearyl cellulose, water soluble acrylic, right Carbon, and epoxy resin, etc.) 40 wt% (or from the addition of 0.01 50 wt%) to prepare a corrosion-proof coating material.

The present invention provides a corrosion preventing paint using a blend of a water-soluble conductive polymer polyaniline salt or a water-soluble polyaniline salt and a water-soluble poly (3,4-ethylenedioxy) thiophene, thereby preventing corrosion using a soluble polyaniline salt in an existing organic solvent. Compared with paint, it can improve working environment and work efficiency, and can improve the environmental pollution problem such as industrial disasters, air, water quality, soil, etc., and after preparing paint through blending with functional polymer, Coating on the surface provides excellent metal corrosion protection.

Claims (2)

To the polyaniline aqueous solution obtained by substituting polyaniline salt of water-soluble and conductive polymer with sulfonic acid, 5-90% by weight of polyvinyl alcohol was added, and 50: water-soluble poly (3,4-ethylenedioxy) thiophene was added in the presence of a polar solvent. Method for producing a metal anti-corrosion paint, characterized in that blending at a weight ratio of 50. The method of claim 1, wherein the polar solvent is dimethyl sulfoxide (DMSO), N, N'- dimethylformamide (DMF), N-methyl-2-pyrrolidinone (NMP), ethylene glycol (EG) and the like Method for producing metal anticorrosion paints