CN114163897A - Anticorrosive paint with single methyl ring replacing polyaniline, preparation method thereof and coating layer - Google Patents

Anticorrosive paint with single methyl ring replacing polyaniline, preparation method thereof and coating layer Download PDF

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CN114163897A
CN114163897A CN202111628341.XA CN202111628341A CN114163897A CN 114163897 A CN114163897 A CN 114163897A CN 202111628341 A CN202111628341 A CN 202111628341A CN 114163897 A CN114163897 A CN 114163897A
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coating
solution
substituted polyaniline
anticorrosive paint
polyaniline
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胡传波
李廷真
尹华伟
陈琪雅
唐黎明
白超云
张文欣
周张燕
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Chongqing Three Gorges University
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/65—Additives macromolecular

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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  • Organic Chemistry (AREA)
  • Paints Or Removers (AREA)

Abstract

The invention belongs to the technical field of conductive polymer anticorrosive materials, and discloses an anticorrosive paint with single methyl ring replacing polyaniline, a preparation method thereof and a coating layer. The anticorrosive paint of the single methyl ring substituted polyaniline provided by the invention can improve the solubility of PANI by utilizing the steric hindrance effect of methyl on a benzene ring in the single methyl ring substituted polyaniline, and the generated ortho-position derivative has higher solubility and electrochemical properties, thereby obtaining higher anticorrosive performance. The invention also provides a preparation method of the anticorrosive coating with the single methyl ring replacing polyaniline, which introduces poly-o-toluidine (POT), poly-m-toluidine (PMT) and poly-p-toluidine (PPT) fillers into the water-based epoxy emulsion to form a more compact passive film on a carbon steel substrate, can effectively protect metal from being damaged by the outside, and has important significance for developing anticorrosive coatings with higher solubility and electrochemical properties.

Description

Anticorrosive paint with single methyl ring replacing polyaniline, preparation method thereof and coating layer
Technical Field
The invention relates to the technical field of conductive polymer anticorrosive materials, in particular to an anticorrosive paint with single methyl ring replacing polyaniline, a preparation method thereof and a coating layer.
Background
At present, most of protective layers contain heavy metal elements (cadmium, silver and the like), and the body health and the ecological environment of people are deeply harmed. Polyaniline (PANI) has less pollution and unique electrochemical performance, so that a great deal of experiments and researches on the corrosion resistance of PANI are carried out. Jeyaprabha and other researchers have studied the corrosion resistance of PANI in hydrochloric acid medium, and the result shows that a layer of compact passive film is generated on the metal surface by PANI, and the corrosion resistance efficiency can reach 84% at most. Although PANI is easily available in raw materials, the application range of PANI is narrow due to extremely strong rigidity and low solubility of a molecular main chain, and the PANI is not applied to some fields. Therefore, there is a need in the art to develop an anticorrosive coating having higher solubility and electrochemical properties.
Disclosure of Invention
In view of the above, the invention provides an anticorrosive coating with a single methyl ring replacing polyaniline, a preparation method thereof and a coating layer, and solves the problems that the molecular main chain of the traditional polyaniline has extremely strong rigidity and low solubility, and the application range of the traditional polyaniline is limited.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides an anticorrosive paint with single methyl ring replacing polyaniline, which comprises the following components: epoxy resin adhesive, solvent, plasticizer, defoaming agent and solution of single methyl ring substituted polyaniline;
the mass-volume ratio of the epoxy resin adhesive to the solvent to the plasticizer to the defoaming agent is 3-4 g: 1-2 mL: 0.2-1 mL: 0.5 mL;
the addition amount of the monomethyl ring substituted polyaniline is 4-6% of the mass of the epoxy resin adhesive.
Preferably, the solution of the monomethyl ring substituted polyaniline is an N-methylpyrrolidone solution of the monomethyl ring substituted polyaniline, and the concentration of the solution of the monomethyl ring substituted polyaniline is 0.2-0.3 g/mL.
Preferably, the preparation of the monomethyl ring-substituted polyaniline comprises the following steps:
(1) mixing toluidine with a dodecyl benzene sulfonic acid solution to obtain a mixed solution;
(2) and at the temperature of-5 ℃, mixing the mixed solution with an ammonium persulfate solution and then reacting to generate the monomethyl ring substituted polyaniline.
Preferably, the toluidine is one or more of o-toluidine, m-toluidine and p-toluidine, and the concentration ratio of the toluidine to the dodecylbenzene sulfonic acid is 1: 0.5-5; the concentration of the dodecylbenzene sulfonic acid is 0.5-2 mol/L.
Preferably, in the step (2), the ammonium persulfate solution is dropwise added into the mixed solution; the concentration of the ammonium persulfate solution is 0.2-1 mol/L, the dropping speed is 1-2 drops/s, and the dropping time is 2-3.5 h; the reaction time is 9-11 h.
Preferably, the epoxy resin adhesive comprises epoxy resin A glue and epoxy resin B glue; the epoxy resin A glue is bisphenol A type resin, and the epoxy resin B glue is polyamide resin.
Preferably, the solvent is n-butanol, the plasticizer is dibutyl phthalate, and the defoaming agent is ethyl acetate.
The invention also provides a preparation method of the anticorrosive paint with the monomethyl ring replacing polyaniline, which comprises the following steps:
step A: mixing an epoxy resin adhesive, a solvent, a plasticizer and a defoaming agent to obtain a water-based epoxy emulsion;
and B: and (3) mixing the aqueous epoxy emulsion with the solution of the monomethyl ring substituted polyaniline to obtain the anticorrosive paint.
The invention also provides an anticorrosive coating prepared from the monomethyl ring substituted polyaniline anticorrosive paint, which comprises the following steps: and coating the anticorrosive paint on a substrate, and performing post-treatment to obtain the matrix containing the anticorrosive coating.
Preferably, the substrate is pre-treated prior to use, the pre-treatment comprising the steps of: firstly, polishing a substrate, then soaking the substrate in a mixed solution of acetone and ethanol, carrying out ultrasonic treatment for 10-20 min, and finally drying.
According to the technical scheme, compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts a chemical oxidation polymerization method to prepare dodecylbenzene sulfonic acid (DBSA) doped poly-o-toluidine (POT), poly-m-toluidine (PMT) and poly-p-toluidine (PPT), and the POT-EP, PMT-EP and PPT-EP blended coating is prepared by blending with the aqueous epoxy emulsion, and the preparation method has simple operation and is beneficial to popularization and use.
2. The single methyl ring replaces the steric hindrance effect of methyl on a benzene ring in polyaniline, the rigidity of a PANI molecular chain can be reduced, the acting force between chains is reduced, the solubility of PANI is improved to a great extent, and after the methyl is introduced on the PANI benzene ring, the generated ortho-position derivative has higher solubility and electrochemical properties, obtains higher corrosion resistance and can effectively protect metal from being damaged by the outside.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is an infrared spectrum (FTIR) chart of POT, PMT and PPT materials in powder form prepared in examples 1-3 of the present invention;
FIG. 2 is SEM images of POT, PMT and PPT materials prepared in examples 1-3 of the present invention, wherein (a) and (b) are SEM images of the POT materials at different magnifications, (c) and (d) are SEM images of the PMT materials at different magnifications, and (e) and (f) are SEM images of the PPT materials at different magnifications;
FIG. 3 is an SEM picture of the surface of a carbon steel substrate coated with an EP coating, a POT-EP coating, a PMT-EP coating, and a PPT-EP coating obtained in example 4 of the present invention, and an SEM picture of the bare carbon steel substrate, respectively, wherein (a) is an SEM picture of the surface of the bare carbon steel substrate, fig. (b) is an SEM picture of the surface of the carbon steel substrate coated with the EP coating, fig (c) is an SEM picture of the surface of the carbon steel substrate coated with the POT-EP coating, fig (d) is an SEM picture of the surface of the carbon steel substrate coated with the PMT-EP coating, and fig (e) is an SEM picture of the surface of the carbon steel substrate coated with the PPT-EP coating;
FIG. 4 is SEM pictures of an anticorrosive-coated substrate and a bare carbon steel substrate obtained by respectively coating an EP coating, a POT-EP coating, a PMT-EP coating and a PPT-EP coating on a carbon steel substrate in example 4 of the present invention after being soaked in a 3.5% NaCl solution for 90 days and peeled off, wherein (a) is a SEM picture of the bare carbon steel substrate after being treated, (b) is a SEM picture of the carbon steel substrate coated with the EP coating after being treated, (c) is a SEM picture of the carbon steel substrate coated with the POT-EP coating after being treated, (d) is a SEM picture of the carbon steel substrate coated with the PMT-EP coating after being treated, and (e) is a SEM picture of the carbon steel substrate coated with the PPT-EP coating after being treated;
FIG. 5 shows Tafel polarization curve and AC impedance test curve of anti-corrosion coating coated substrate and bare carbon steel substrate soaked in 3.5% NaCl solution for 48h, wherein the EP coating, POT-EP coating, PMT-EP coating and PPT-EP coating obtained in example 4 of the present invention are coated on carbon steel substrate.
Detailed Description
The invention provides an anticorrosive paint with single methyl ring replacing polyaniline, which comprises the following components: epoxy resin adhesive, solvent, plasticizer, defoaming agent and solution of single methyl ring substituted polyaniline.
In the invention, the mass-volume ratio of the epoxy resin adhesive, the solvent, the plasticizer and the defoaming agent is 3-4 g: 1-2 mL: 0.2-1 mL: 0.5mL, and the preferable ratio is 3.2-3.5 g: 1.2-1.8 mL: 0.3-0.8 mL: 0.5 mL.
In the invention, the addition amount of the monomethyl ring substituted polyaniline is 4-6% of the mass of the epoxy resin adhesive, and the more preferable addition amount is 4.5-5.5%.
In the invention, the solution of the monomethyl ring substituted polyaniline is an N-methylpyrrolidone solution of the monomethyl ring substituted polyaniline, and the concentration of the solution of the monomethyl ring substituted polyaniline is preferably 0.2-0.3 g/mL, and more preferably 0.25-0.28 g/mL.
In the invention, the preparation of the monomethyl ring-substituted polyaniline comprises the following steps:
(1) mixing toluidine with a dodecyl benzene sulfonic acid solution to obtain a mixed solution;
(2) and at the temperature of-5 ℃, mixing the mixed solution with an ammonium persulfate solution and then reacting to generate the monomethyl ring substituted polyaniline.
In the invention, the toluidine is purified before use, and the method comprises the following steps: mixing the monomer with zinc powder, and reducing the boiling point of the monomer by a reduced pressure distillation method to separate and purify the monomer.
In the present invention, the toluidine is one or more of o-toluidine, m-toluidine and p-toluidine.
In the present invention, the concentration ratio of toluidine to dodecylbenzene sulfonic acid is preferably 1: 0.5-5, and further preferably 1: 1-3; the concentration of the dodecylbenzene sulfonic acid is preferably 0.5-2 mol/L, and more preferably 1-1.5 mol/L.
In the present invention, in the step (1), the mixing time is preferably 5 to 10min, and more preferably 6 to 8min.
In the invention, in the step (2), the ammonium persulfate solution is dropwise added into the mixed solution; the concentration of the ammonium persulfate solution is preferably 0.2-1 mol/L, and further preferably 0.3-0.6 mol/L; the dripping speed is preferably 1-2 drops/s, and more preferably 1 drop/s; the dripping time is preferably 2-3.5 h, and more preferably 2.5-3 h.
In the invention, before dropping the ammonium persulfate solution, the mixed solution is stirred for 20-40 min at the temperature of-5 ℃.
In the invention, in the step (2), the reaction time is preferably 9-11 h, and more preferably 9.5-10.5 h.
In the invention, the epoxy resin adhesive comprises epoxy resin A adhesive and epoxy resin B adhesive; the epoxy resin A glue is bisphenol A type resin, and the epoxy resin B glue is polyamide resin.
In the invention, the solvent is n-butyl alcohol, the plasticizer is dibutyl phthalate, and the defoaming agent is ethyl acetate.
The invention also provides a preparation method of the anticorrosive paint with the monomethyl ring replacing polyaniline, which comprises the following steps:
step A: mixing an epoxy resin adhesive, a solvent, a plasticizer and a defoaming agent to obtain a water-based epoxy emulsion;
and B: and (3) mixing the aqueous epoxy emulsion with the solution of the monomethyl ring substituted polyaniline to obtain the anticorrosive paint.
In the invention, in the step B, after the aqueous epoxy emulsion is mixed with the solution of the monomethyl ring substituted polyaniline, stirring and ultrasonic treatment are sequentially carried out; the stirring time is preferably 4-10 min, and more preferably 5-8 min; the ultrasonic time is preferably 5-20 min, and more preferably 8-12 min.
The invention also provides an anticorrosive coating prepared from the monomethyl ring substituted polyaniline anticorrosive paint, which comprises the following steps: and coating the anticorrosive paint on a substrate, and performing post-treatment to obtain the matrix containing the anticorrosive coating.
In the present invention, the substrate is pretreated before use, the pretreatment comprising the steps of: firstly, polishing a substrate, then soaking the substrate in a mixed solution of acetone and ethanol, carrying out ultrasonic treatment for 10-20 min, and finally drying.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
Preparation of doped poly-o-toluidine (POT) with dodecylbenzenesulfonic acid (DBSA):
methylaniline monomer was first purified by reduced pressure distillation, then 5.31mL o-toluidine monomer was mixed with 50mL 1.0mol/L DBSA solution and mechanically stirred for 5min until the solution became colorless and clear. The mixed solution was introduced into a three-necked flask, and stirred in an ice bath for 30 min. 11.41g of ammonium persulfate is prepared into 100mL of solution, and the solution is dripped into a three-neck flask at the speed of 1 drop/s for 3 hours, so that the color of the solution is changed from colorless to blue, and finally, the solution is changed into greenish black. After the dropwise addition, continuously placing the mixture in an ice bath, stirring the mixture for 10 hours, then filtering the mixture, and washing the obtained filter cake by using ethanol and water until the filtrate is colorless; and drying the filter cake at 60 ℃ for 24h, taking out the filter cake, and grinding the filter cake into powder to obtain the DBSA doped poly-o-toluidine (POT).
Example 2
Preparation of dodecylbenzene sulfonic acid (DBSA) doped poly-m-toluidine (PMT):
methylaniline monomer was first purified by reduced pressure distillation, then 5.31mL m-toluidine monomer was mixed with 50mL 1.0mol/L DBSA solution and mechanically stirred for 7min until the solution became colorless and clear. The mixed solution was introduced into a three-necked flask, and stirred in an ice bath for 25 min. 11.41g of ammonium persulfate is prepared into 100mL of solution, the solution is dripped into a three-neck flask at the speed of 2 drops/s for 3.5 hours, and the color of the solution is changed from colorless to blue and finally to greenish black. After the dropwise addition, continuously placing the mixture in an ice bath, stirring the mixture for 9.5 hours, then filtering the mixture, and washing the obtained filter cake by using ethanol and water until the filtrate is colorless; the filter cake was dried at 60 ℃ for 24h, then the filter cake was taken out and ground to a powder to obtain DBSA-doped poly-m-toluidine (PMT).
Example 3
Preparation of dodecylbenzene sulfonic acid (DBSA) doped polyparatoluidine (PPT):
purifying methylaniline monomers by reduced pressure distillation, dissolving 5.36g of p-toluidine powder in 50mL of deionized water to prepare a p-toluidine solution, mixing with 50mL of 1.0mol/L DBSA solution, and mechanically stirring for 9min until the solution becomes colorless and clear. The mixed solution was introduced into a three-necked flask, and stirred in an ice bath for 35 min. 11.41g of ammonium persulfate is prepared into 100mL of solution, the solution is dripped into a three-neck flask at the speed of 1 drop/s for 2.5 hours, and the color of the solution is changed from colorless to light yellow and finally to purple red. After the dropwise addition, continuously placing the mixture in an ice bath, stirring for 11 hours, then filtering, and washing the obtained filter cake with ethanol and water until the filtrate is colorless; and drying the filter cake at 60 ℃ for 24h, taking out the filter cake, and grinding the filter cake into powder to obtain the DBSA doped polypolyp-toluidine (PPT).
Example 4
Preparing an anticorrosive coating:
weighing bisphenol A resin and polyamide resin in a ratio of 2.5 g: 0.75g to obtain epoxy resin AB glue, mechanically stirring the epoxy resin AB glue with a stainless steel spoon for 5min (placing the AB glue in a small beaker, weighing and stirring with the stainless steel spoon), and then sequentially adding 1.5mL of n-butyl alcohol, 0.5mL of dibutyl phthalate and 0.5mL of ethyl acetate to adjust the AB glue to proper viscosity to obtain water-based epoxy emulsion (EP paint);
respectively dissolving 0.13g of POT, PMT and PPT obtained in examples 1-3 in 0.5mL of N-methylpyrrolidone (NMP) to obtain POT-NMP, PMT-NMP and PPT-NMP solutions;
thirdly, POT-NMP, PMT-NMP and PPT-NMP solution is poured into the EP coating, mechanically stirred for 5min and ultrasonically treated for 10min to respectively obtain the POT-EP, PMT-EP and PPT-EP blended coating. And then coating the blended coating on the carbon steel substrate to obtain the carbon steel substrate coated with the anticorrosive coating.
The invention tests various performances of a bare carbon steel substrate, a carbon steel substrate coated with EP coating and a carbon steel substrate coated with anticorrosive coating.
As can be seen from FIG. 1, the length of the groove is 3415cm-1The peak is N-H stretching vibration peak of amino group at 3130cm-1The peak of C-H stretching vibration of alkane in DBSA is shown, which indicates that DBSA macromolecules are introduced. At 2919cm-1C-H stretching vibration peak of methyl at 1606cm-1And 1488cm-1The absorption vibration peak at 1397cm is the absorption vibration peak of quinoid structure C ═ C and benzene structure-1Is located at 1200cm of C-N telescopic absorption peak-1The C-C skeleton vibration peak of methyl on the benzene ring indicates the benzene ringA methyl group is introduced. At 1110cm-1And 808cm-1The positions are respectively the in-plane and out-of-plane vibration absorption peaks of the benzene ring C-H at 1041cm-1、663cm-1And 579cm-1Stretching vibration peaks at S ═ O, C-S and S-O, respectively, indicating the presence of sulfonic acid group-SO3H, further indicating the introduction of DBSA macromolecules.
As can be seen from FIG. 2, the POT, PMT and PPT materials obtained in the embodiments 1 to 3 of the present invention have compact particle-to-particle distribution and dense structures. Wherein, the compactness of the surfaces of the three materials is optimized by the POT material, and the compactness of the surfaces of the three materials is inferior to that of the PMT and PPT materials.
As can be seen from FIG. 3, the surface of the bare carbon steel substrate without any coating is provided with irregularly arranged stripes, which are the stripes left after polishing and are the inherent surface topography of the smooth carbon steel; the surface of the carbon steel substrate coated with the EP coating has more micropore structures, which shows that the EP coating has more micropore structures after the solvent is volatilized, so that the EP coating can cause corrosion defects and is easy to corrode; the surface of the carbon steel substrate coated with the POT-EP coating does not have obvious microscopic pores and defects, the structure is compact and uniform, and the coating is well combined with the interface of the carbon steel substrate. The surface of the carbon steel substrate coated with the PMT-EP coating and the surface of the carbon steel substrate coated with the PPT-EP coating have a slightly microporous structure, but the pore structure is small relative to the EP coating. This shows that the filler dispersed in the epoxy resin of the present invention can fill the micro-porous structure left after the epoxy resin is cured, and the surface morphology of the POT-EP coating is the best, indicating that the ortho-substituted polymer has higher solubility and dispersibility.
As can be seen from FIG. 4, the surface of the bare carbon steel substrate was free of any coating, and it can be seen that the surface possessed irregularly shaped rust. The surface of the carbon steel substrate coated with the EP coating had a cured structure left after the EP coating was skinned, which was very loose and uneven. A layer of passive film is formed on the surface of the carbon steel substrate coated with the POT-EP coating, the film forming area of the passive film is larger, the structure of the passive film is compact, and no obvious concave-convex structure exists. Passivation films are formed on the surface of the carbon steel substrate coated with the PMT-EP coating and the surface of the carbon steel substrate coated with the PPT-EP coating, the film forming area is large, the arrangement is compact, and the edges of the carbon steel substrate are slightly concave-convex structures and cracks. In conclusion, due to the compact structure and high electrochemical performance of POT, the passive film under the POT-EP coating has the best compact performance and the best corrosion prevention effect, and the PMT-EP coating and the PPT-EP coating are inferior.
In the Tafel polarization curve of FIG. 5, the corrosion rate (corr) and corrosion Protection Efficiency (PE) of the coating are calculated as follows:
Figure BDA0003439249340000131
Figure BDA0003439249340000132
wherein M, n and p respectively represent the molecular mass, charge number and density, I'corr、IcorrThe corrosion current density of the bare steel sheet and the coating is shown.
According to the Tafel polarization curve, the corrosion potentials of a bare carbon steel substrate, a carbon steel substrate coated with an EP coating, a carbon steel substrate coated with a PPT-EP coating, a carbon steel substrate coated with a PMT-EP coating and a carbon steel substrate coating coated with a POT-EP coating are sequentially increased, the corrosion current density is sequentially reduced, and the corrosion protection efficiency is better and better. From the fitted parameters, it can also be known that the corrosion protection efficiency of the EP coating is 61.71%, the corrosion protection efficiency of the PPT-EP coating is 75.76%, the corrosion protection efficiency of the PMT-EP coating is 80.03%, the corrosion protection efficiency of the POT-EP coating is 90%, and the corrosion protection efficiency of the bare carbon steel substrate without any coating is 0, indicating that the blended coating can effectively protect the carbon steel surface and the surrounding corrosion medium (OH) by applying the blended coating on the carbon steel substrate-And Cl-Etc.) to obtain better anticorrosion effect. The introduction of methyl groups on the benzene ring makes the best corrosion protection properties of the POT-EP coating. This is because the substitution of the hydrogen atom on the phenyl ring of PANI with a methyl group reduces the rigidity between the PANI molecular chains and increases the solubility of PANI, which is compatible with EP-type compoundsForming a good blending coating. At the same time, a hydrophobic group (-CH)3) The introduction of the carbon steel can effectively prevent moisture from permeating into the surface of the carbon steel, thereby inhibiting the occurrence of metal corrosion. However, the corrosion protection efficiency of PMT-EP coatings and PPT-EP coatings is lower than that of POT-EP coatings, since the corrosion protection properties of the material are not only related to the chemical composition, but also to its microstructure.
In the AC impedance test curve, the impedance calculation formula of the coating is as follows:
Figure BDA0003439249340000141
where Z' is the real part of the impedance and Z "is the imaginary part of the impedance.
From the ac impedance test curves, the EIS curves for the bare carbon steel substrate, the EP-coated carbon steel substrate, the PPT-EP-coated carbon steel substrate, the PMT-EP-coated carbon steel substrate, and the POT-EP-coated carbon steel substrate all exhibited an incomplete semicircle with the PMT-EP and PPT-EP coatings slightly off the semicircle trajectory at the tail, due to the non-uniformity of the electrode surface and the roughness of the coatings. In general, the high frequency region has an intercept of RsThe intercept of the low frequency region is Rs+RctThe diameter of the semicircle is Rct. Therefore, it can be determined that the larger the semi-circle diameter, the higher the impedance and the better the corrosion resistance. As can be seen, the coating semicircle diameters are ordered as: bare carbon steel substrate<Carbon steel substrate coated with EP coating<Carbon steel substrate coated with PPT-EP coating<Carbon steel substrate coated with PMT-EP coating<Carbon steel substrate coated with POT-EP paint. So the corrosion resistance is ranked as: bare carbon steel substrate<Carbon steel substrate coated with EP coating<Carbon steel substrate coated with PPT-EP coating<Carbon steel substrate coated with PMT-EP coating<Carbon steel substrate coated with POT-EP paint. With the bare carbon steel matrix having the worst performance followed by the EP coating. The EP coating is not added with polymer filler, but can play a certain physical shielding role and also has a certain anticorrosion effect because the coating covers the surface of the carbon steel.The POT-EP coating has higher impedance and the best anti-corrosion effect, which shows that the induction effect of the ortho-substituent is stronger, and the POT has better dispersibility and can be well dispersed in the EP coating, so that the pore defects of the epoxy coating are reduced after the solvent is volatilized, the POT has a very compact structure, and a good compact coating is formed with the EP, thereby effectively protecting the carbon steel from being interfered by external corrosive media.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The anticorrosive paint with the single methyl ring replacing polyaniline is characterized by comprising the following components: epoxy resin adhesive, solvent, plasticizer, defoaming agent and solution of single methyl ring substituted polyaniline;
the mass-volume ratio of the epoxy resin adhesive to the solvent to the plasticizer to the defoaming agent is 3-4 g: 1-2 mL: 0.2-1 mL: 0.5 mL;
the addition amount of the monomethyl ring substituted polyaniline is 4-6% of the mass of the epoxy resin adhesive.
2. The anticorrosive paint of the mono-methyl ring-substituted polyaniline according to claim 1, wherein the solution of the mono-methyl ring-substituted polyaniline is an N-methylpyrrolidone solution of the mono-methyl ring-substituted polyaniline, and the concentration of the solution of the mono-methyl ring-substituted polyaniline is 0.2-0.3 g/mL.
3. The anticorrosive paint of monomethyl-ring-substituted polyaniline according to claim 2, wherein the preparation of the monomethyl-ring-substituted polyaniline comprises the following steps:
(1) mixing toluidine with a dodecyl benzene sulfonic acid solution to obtain a mixed solution;
(2) and at the temperature of-5 ℃, mixing the mixed solution with an ammonium persulfate solution and then reacting to generate the monomethyl ring substituted polyaniline.
4. The anticorrosive paint of mono-methyl ring-substituted polyaniline according to claim 3, wherein the toluidine is one or more of o-toluidine, m-toluidine and p-toluidine, and the concentration ratio of the toluidine to dodecylbenzene sulfonic acid is 1: 0.5-5; the concentration of the dodecylbenzene sulfonic acid is 0.5-2 mol/L.
5. The anticorrosive paint of mono-methyl ring-substituted polyaniline of claim 3, wherein in the step (2), the ammonium persulfate solution is added dropwise into the mixed solution; the concentration of the ammonium persulfate solution is 0.2-1 mol/L, the dropping speed is 1-2 drops/s, and the dropping time is 2-3.5 h; the reaction time is 9-11 h.
6. The anticorrosive paint of monomethyl-ring-substituted polyaniline according to claim 2, wherein the epoxy adhesive comprises epoxy a glue and epoxy B glue; the epoxy resin A glue is bisphenol A type resin, and the epoxy resin B glue is polyamide resin.
7. The anticorrosive paint of mono-methyl ring-substituted polyaniline according to claim 2 or 6, wherein the solvent is n-butanol, the plasticizer is dibutyl phthalate, and the defoaming agent is ethyl acetate.
8. The method for preparing the anticorrosive paint of the monomethyl ring-substituted polyaniline according to any one of claims 1 to 7, which comprises the following steps:
step A: mixing an epoxy resin adhesive, a solvent, a plasticizer and a defoaming agent to obtain a water-based epoxy emulsion;
and B: and (3) mixing the aqueous epoxy emulsion with the solution of the monomethyl ring substituted polyaniline to obtain the anticorrosive paint.
9. An anticorrosive coating prepared from the anticorrosive paint of mono-methyl ring substituted polyaniline according to any one of claims 1 to 7, characterized by comprising the following steps: and coating the anticorrosive paint on a substrate, and performing post-treatment to obtain the matrix containing the anticorrosive coating.
10. The corrosion protective paintcoat according to claim 9, wherein said substrate is pretreated prior to use, the pretreatment comprising the steps of: firstly, polishing a substrate, then soaking the substrate in a mixed solution of acetone and ethanol, carrying out ultrasonic treatment for 10-20 min, and finally drying.
CN202111628341.XA 2021-12-28 2021-12-28 Anticorrosive paint with single methyl ring replacing polyaniline, preparation method thereof and coating layer Pending CN114163897A (en)

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Citations (2)

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