Acid-doped polyaniline, preparation method thereof and anticorrosive paint

Abstract

The invention relates to the field of anticorrosive materials, in particular to acid-doped polyaniline, a preparation method thereof and anticorrosive paint. The preparation method of the acid-doped polyaniline provided by the invention comprises the following steps: reacting polyaniline with a specific organic acid in a solvent medium, then carrying out solid-liquid separation, and washing and drying the obtained solid product to obtain the acid-doped polyaniline. The doped polyaniline obtained in the invention has the advantages of small particle size, high doping degree, high dispersion degree when being mixed with resin when being used in the anticorrosive paint, good anticorrosive effect and good adhesive force; moreover, the addition amount of the obtained acid-doped polyaniline is low, the production cost is reduced, and the application range is expanded. In addition, the preparation method is simple and low in preparation cost.

Description

Technical Field

[0001] The present invention relates to the field of anticorrosive materials, and particularly to an acid-doped polyaniline, a preparation method thereof, and an anticorrosive coating. Background Art

[0002] The unit composition of polyaniline is phenylenediamine and quinonediimine, and the proportion of the two in polyaniline under different oxidation states is different. The most deeply studied and widely used is the intermediate state polyaniline, and its repeating unit is three benzene rings and one quinone ring. As one of the most potential conductive polymers, the research on polyaniline has been carried out very early. When Mengoli et al. tried to polymerize aniline on the surface of an iron sheet by electrochemistry to form a polyaniline film, it was found that the synthesized polyaniline film had a certain anticorrosive effect on metallic iron. Since then, people have gradually started to study the use of polyaniline in the field of anticorrosion. Polyaniline is simple to synthesize, has stable properties, and has no problems such as heavy metal pollution. Anticorrosive coatings prepared by mixing an appropriate amount of polyaniline with other additives have a wide range of uses in fields such as bridges, highways, and even aerospace.

[0003] In the early polyaniline anticorrosion experiments, a film was mainly formed on the metal surface uniformly by electrochemistry, and such a film had a good anticorrosive effect. In 1985, Professor Deberry polymerized a layer of polyaniline film on the surface of stainless steel by electrochemistry, and the metal surface could maintain the passivation state from several hours to 1200 hours, demonstrating excellent corrosion prevention ability. However, the adhesion of the pure polyaniline film to the metal is poor and it is extremely easy to fall off, and the formed polyaniline film cannot ensure denseness and cannot physically shield the corrosion of external corrosive elements to the metal. In addition, due to the cost of electrochemically preparing the polyaniline film, large-scale commercialization cannot be achieved. Therefore, although the electrochemistry method can achieve a film with good anticorrosive effect, the chemical synthesis of polyaniline is the most promising way. The polyaniline synthesized by the chemical method, when mixed with matrix materials such as resins or polyurethanes to prepare an anticorrosive coating, can have both the adhesion and shielding properties of the resin and the excellent anticorrosive properties of polyaniline.

[0004] Wesslin coated the chemically synthesized polyaniline dispersion on the surface of low-carbon steel. After coating, its corrosion potential increased significantly. Compared with the low-carbon steel of the same specification without coating, its corrosion potential increased by 800 mV. After the polyaniline film was formed for a period of time and the film was removed, it was found that the metal still had a certain anticorrosive ability. Using sulfonated polyaniline doped with polyvinyl alcohol as a waterborne anticorrosive material, it was immersed in a 3% sodium chloride solution, and its anticorrosive performance was detected by electrochemistry. Compared with the bare metal plate, the corrosion potential of the metal plate coated with the anticorrosive material shifted significantly in the positive direction, and the corrosion efficiency could reach 84.39%.

[0005] The mixed use of multiple materials can significantly enhance the anti-corrosion effect of the materials. Common inorganic materials include silica, graphene, montmorillonite, etc. In-situ polymerization of polyaniline on inorganic materials can achieve nano-scale dispersion of polyaniline relying on the nano-size and mechanical properties of inorganic substances. In-situ polymerization of aniline on graphene oxide (GO) yields GO-Pani nanosheets. Graphene oxide has excellent barrier properties. By modifying graphene oxide, the agglomeration problem of graphene oxide can be reduced. In-situ polymerization of aniline on graphene oxide significantly enhances the barrier properties of the composite coating. Cerium oxide is considered as a substitute for traditional corrosion inhibitor chromate. The GO-Pani-CeO hybrid coating prepared by mixing cerium oxide with GO-Pani nanosheets shows excellent anti-corrosion effect in electrochemical tests.

[0006] Three different acids are respectively doped with polyaniline to obtain polyaniline powders in different doping states. These three acids are sulfuric acid, p-toluenesulfonic acid, and sulfosalicylic acid. The three doped polyanilines are immersed in 3.5% sodium chloride solution, and the change of impedance value within 100 days is tested by electrochemical impedance method. Among them, the impedance |Z| of polyaniline doped with sulfuric acid is above 10 10 , that of polyaniline doped with p-toluenesulfonic acid is close to 10 12 and that of polyaniline doped with sulfosalicylic acid is above 10 11 . During the 100-day immersion, the decline rate of sulfosalicylic acid is the lowest, showing the best anti-corrosion performance. However, the production of traditional acid-doped polyaniline does not attach importance to the doping process. Excessive amount of doping acid, too long doping time, and too high doping temperature are required during the doping process, resulting in waste of resources and time, and the doping effect is also poor, with a low doping degree, making it impossible to reduce the particle size of acid-doped polyaniline to the greatest extent. Summary of the Invention

[0007] In view of this, the present invention provides an acid-doped polyaniline, its preparation method, and an anti-corrosion coating. The acid-doped polyaniline provided by the present invention can effectively improve the anti-corrosion effect and adhesion of the anti-corrosion coating.

[0008] The present invention provides a preparation method of acid-doped polyaniline, comprising the following steps:

[0009] Polyaniline reacts with an organic acid in a solvent medium, and then, solid-liquid separation is carried out, and the obtained solid product is washed and dried to obtain acid-doped polyaniline;

[0010] Wherein,

[0011] the organic acid is hydroxyethylidene diphosphonic acid.

[0012] Preferably, the molar ratio of the organic acid to the phenylenediamine unit in polyaniline is (0.3 - 2.5)∶1.

[0013] Preferably, the molar ratio of the organic acid to the phenylenediamine unit in the polyaniline is 1.5:1.

[0014] Preferably, the temperature of the reaction is 10 - 60 °C and the time is 0.5 - 24 h.

[0015] Preferably, the temperature of the reaction is 30 °C and the time is 6 h.

[0016] Preferably, the way of contacting the polyaniline, the organic acid and the solvent medium is any one of the following ways (1) - (3):

[0017] Way (1): Add the polyaniline and the organic acid solution into a container respectively, and then add a solvent for dilution;

[0018] Way (2): Add the polyaniline and the diluted organic acid solution into a container respectively for mixing;

[0019] Way (3): Add the polyaniline, the organic acid and the solvent into a container respectively for mixing;

[0020] In the said way (1): The mass fraction of the organic acid solution is 55% - 65%; The ratio of the amount of the solvent added during dilution to the amount of the polyaniline used is (10 - 20) mL∶1 g.

[0021] Preferably, the solvent is water;

[0022] The degree of washing is to wash until the pH of the washing liquid after washing is 4.5 - 6;

[0023] The drying is freeze-drying.

[0024] The present invention also provides an acid-doped polyaniline prepared by the preparation method described in the above technical solution.

[0025] The present invention also provides an anticorrosive coating, wherein the polyaniline is the acid-doped polyaniline described in the above technical solution.

[0026] Preferably, it includes: polyaniline and epoxy resin.

[0027] For acid-doped polyaniline, improving the doping degree can greatly improve the performance of polyaniline. In the prior art, acid-doped polyaniline often uses too much doping acid, too long doping time, and too high doping temperature, resulting in waste of resources and time, and the doping effect is also poor, with a low doping degree, so that the particle size of acid-doped polyaniline cannot be reduced to the greatest extent. However, the preparation method provided by the present invention reacts polyaniline with a specific organic acid in a solvent medium, and then, solid-liquid separation is carried out, the obtained solid product is washed and dried to obtain acid-doped polyaniline. The above method can be completed under mild conditions. The doped polyaniline obtained by the present invention effectively improves the doping effect, and the obtained doped polyaniline has a high doping degree and a small particle size. In addition, the method of the present invention can be completed under mild conditions, with a low acid consumption and a short reaction time, saving costs.

[0028] The test results show that the diameter of a single particle in the acid-doped polyaniline product obtained by the present invention is reduced to less than 3 μm, and the doping degree reaches more than 14%; under the preferred conditions, the diameter of a single particle in the product is reduced to less than 1.5 μm, and the doping degree reaches more than 20%. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0030] Figure 1 It is the SEM diagram of intrinsic polyaniline;

[0031] Figure 2 It is the SEM diagram of the doped polyaniline obtained in Example 8 of the present invention;

[0032] Figure 3 It is the XPS diagram of intrinsic polyaniline;

[0033] Figure 4 It is the XPS diagram of the doped polyaniline obtained in Example 8 of the present invention. Detailed Embodiments

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application in this specification are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0035] In this article, among the technical features described in an open-ended manner, a closed technical solution composed of the listed features is included, and an open technical solution including the listed features is also included.

[0036] As used herein, the term "and / or" includes any and all combinations of one or more of the related listed items.

[0037] In this text, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are considered continuous and include the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0038] In this text, regarding the units of data ranges, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 10~60℃ means that the units of the left endpoint "10" and the right endpoint "60" are both ℃.

[0039] A preparation method of acid-doped polyaniline includes the following steps:

[0040] Polyaniline reacts with an organic acid in a solvent medium, and then, solid-liquid separation is carried out, the obtained solid product is washed and dried to obtain acid-doped polyaniline;

[0041] Wherein,

[0042] The organic acid is hydroxyethylidene diphosphonic acid.

[0043] In the present invention, the polyaniline is preferably intrinsic polyaniline. In the present invention, the particle size of the intrinsic polyaniline is preferably 4~6μm, more preferably 5μm. In the present invention, the polyaniline is preferably intermediate polyaniline, that is, the molar ratio of the phenylenediamine unit to the quinonediimine unit in the repeating unit is 3:1. The present invention has no special limitation on the source of the intrinsic polyaniline, and it can be a commercially available product or prepared according to the known preparation methods in the art.

[0044] In the present invention, the organic acid is hydroxyethylidene diphosphonic acid. Doping polyaniline with the above specific organic acid can have good anti-corrosion effects on different metals such as steel, iron, aluminum, copper, etc.

[0045] In the present invention, the molar ratio of the organic acid to the phenylenediamine unit in the polyaniline is preferably (0.3~2.5)∶1, specifically it can be 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, and more preferably 1.5:1, 2.5:1.

[0046] In the present invention, the solvent is preferably water. The water is preferably deionized water.

[0047] In the present invention, the preferred manner of bringing the polyaniline, organic acid, and solvent medium into contact is any one of the following manners (1) to (3):

[0048] Manner (1): The polyaniline and the organic acid solution are separately added into a container, and then a solvent is added for dilution.

[0049] Manner (2): The polyaniline and the diluted organic acid solution are separately added into a container for mixing.

[0050] Manner (3): The polyaniline, organic acid, and solvent are separately added into a container for mixing.

[0051] Regarding manner (1): The organic acid solution is a solution formed by dissolving the organic acid in a solvent; wherein, the selection range of the solvent is the same as the range of the solvent types in the previous technical solution and will not be elaborated here. The mass fraction of the organic acid solution is preferably 55% to 65%, specifically 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, and more preferably 60%. The selection range of the solvent used for dilution by adding the solvent is the same as the range of the solvent types in the previous technical solution and will not be elaborated here, and it is preferably the same as the solvent in the organic acid solution (for example, when the solvent in the organic acid solution is water, water is also used for dilution during dilution). The ratio of the amount of the solvent added during dilution by adding the solvent to the amount of the polyaniline used is preferably (10 to 20) mL:1 g, specifically 10 mL:1 g, 11 mL:1 g, 12 mL:1 g, 13 mL:1 g, 14 mL:1 g, 15 mL:1 g, 16 mL:1 g, 17 mL:1 g, 18 mL:1 g, 19 mL:1 g, 20 mL:1 g.

[0052] Regarding manner (2): The main difference between manner (2) and manner (1) is that the organic acid solution is diluted with a solvent in advance to prepare the diluted organic acid solution, and then the polyaniline and the diluted organic acid solution are directly added into a container for mixing; that is, it is equivalent to bringing forward the "adding a solvent for dilution" step in manner (1), and the types of each material, the relationship of the total amounts used, etc. remain unchanged and will not be elaborated here.

[0053] Regarding manner (3): The main difference between manner (3) and manner (1) is that the organic acid is not dissolved with a solvent, but the polyaniline, organic acid, and solvent are directly added into a container for mixing separately; wherein, the types of each material, the relationship of the total amounts used, etc. are the same as those in manner (1) and will not be elaborated here.

[0054] In addition to the above manners (1) to (3), other material contact manners that only make formal changes but are essentially the same also fall within the protection scope of the present invention. In the present invention, most preferably, manner (1) is adopted.

[0055] In the present invention, the temperature of the reaction is preferably 10 - 60 °C, specifically it can be 10 °C, 20 °C, 30 °C, 40 °C, 50 °C, 60 °C, and more preferably 30 °C. In the present invention, the time of the reaction is preferably 0.5 - 24 h, specifically it can be 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, 24 h, and more preferably 6 h. In the present invention, the reaction is preferably a constant temperature reaction. In the present invention, the reaction is more preferably a constant temperature stirring reaction, that is, stirring is accompanied during the reaction; wherein, the rate of the stirring is preferably 400 - 1000 rpm, specifically it can be 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm.

[0056] For acid-doped polyaniline, the improvement of the doping degree will greatly improve the performance of polyaniline. In the present invention, the optimal conditions of the reaction are: the molar ratio of the organic acid to the phenylenediamine unit in polyaniline is 1.5:1 or 2.5:1, the temperature of the reaction is 30 °C, and the time of the reaction is 6 h. Under the above doping acid ratio, reaction temperature and time, the highest doping degree can be achieved, and the particle size of the obtained doped polyaniline can be reduced to about 1.5 μm.

[0057] In the present invention, after the above reaction, solid-liquid separation is carried out. The present invention has no special limitation on the method of the solid-liquid separation, and it can be a conventional solid-liquid separation method in the art, and filtration is preferred. The filtration is preferably suction filtration.

[0058] In the present invention, after solid-liquid separation, the obtained solid product is washed. In the present invention, the washing is preferably carried out with water. The water is preferably distilled water. The degree of the washing is preferably that the pH of the washing liquid after washing is 4.5 - 6, specifically it can be 4.5, 5.0, 5.5, 6.0; the washing liquid after washing refers to the washing liquid discharged after washing. In the present invention, after the above washing, suction filtration under reduced pressure is preferably further carried out to further remove the washing liquid.

[0059] In the present invention, after the above washing, the obtained solid product is dried. For suction filtration under reduced pressure, the solid product is the filter cake after suction filtration. In the present invention, the drying is preferably freeze-drying, that is, lyophilization. After the above drying, acid-doped polyaniline is obtained. In the present invention, the particle size of the obtained acid-doped polyaniline is below 2 μm. The particle size of the original intrinsic polyaniline is about 5 μm, and after doping with the specific organic acid of the present invention, the particle size of polyaniline can be effectively reduced to below 2 μm, and among them, it can be reduced to about 1.5 μm under the best doping conditions.

[0060] The present invention also provides an acid-doped polyaniline, which is prepared by the preparation method described in the above technical solution. In the present invention, the particle size of the acid-doped polyaniline is below 2 μm, and can be reduced to about 1.5 μm under the optimal doping conditions.

[0061] The present invention also provides an anticorrosive coating, wherein the polyaniline therein is the acid-doped polyaniline described in the above technical solution.

[0062] In the present invention, the anticorrosive coating preferably comprises: acid-doped polyaniline and epoxy resin. Among them, the type of the epoxy resin is not particularly limited, and a conventional epoxy resin for anticorrosive coatings can be used. In the present invention, the dosage of the acid-doped polyaniline is 0.5% to 2% of the mass of the epoxy resin. The addition amount is relatively low, and excellent anticorrosive effects can be achieved at such a low addition amount, reducing the cost. In the present invention, the preparation method of the anticorrosive coating is not particularly limited, and a conventional preparation method in the art can be used, such as blending the acid-doped polyaniline and the epoxy resin.

[0063] For acid-doped polyaniline, the improvement of the doping degree will greatly improve the performance of polyaniline. In the prior art, acid-doped polyaniline often uses too much doping acid, too long doping time, and too high doping temperature, resulting in waste of resources and time, and the doping effect is also poor, with a low doping degree, so that the particle size of acid-doped polyaniline cannot be reduced to the greatest extent. However, the preparation method provided by the present invention reacts polyaniline with a specific organic acid in a solvent medium, and then, solid-liquid separation is carried out, and the obtained solid product is washed and dried to obtain acid-doped polyaniline. The above method can be completed under mild conditions. The doped polyaniline obtained by the present invention effectively improves the doping effect, and the obtained doped polyaniline has a high doping degree and a small particle size. In addition, the method of the present invention can be completed under mild conditions, with a low acid consumption and a short reaction time, saving costs.

[0064] The acid-doped polyaniline obtained by the present invention has a high dispersion degree when mixed with resin for use in anticorrosive coatings, with good anticorrosive effects and good adhesion; moreover, the addition amount of the acid-doped polyaniline obtained by the present invention is low, that is, the usage amount of acid-doped polyaniline is reduced, thereby reducing the production cost and expanding the application range. In addition, the preparation method of the present invention is simple and the preparation cost is low.

[0065] In order to further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0066] Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products or can be prepared by known methods. Among them, the particle size of the intrinsic polyaniline is about 5 μm, which is synthesized by the solution polymerization method in the article "Research Progress on the Synthesis and Polymerization Mechanism of Polyaniline". The obtained polyaniline product is continuously stirred in 0.5 mol / L ammonia water solution for 24 h, and the product is filtered through a sintered glass funnel G4, washed with a large amount of deionized water until the filtrate is neutral, and the intrinsic polyaniline is obtained. The epoxy resin is a common bisphenol A type epoxy resin E44 provided by Jiangsu Sanmu Group Co., Ltd.

[0067] Example 1

[0068] Weigh 1 g of the intrinsic polyaniline and place it in a reactor. Add an aqueous solution of hydroxyethane diphosphonic acid (mass fraction is 60%) to the reactor, wherein the molar ratio of hydroxyethane diphosphonic acid to the phenylenediamine unit in the polyaniline is 2:1. Then add 15 mL of deionized water for dilution. Then, carry out a constant-temperature stirring reaction at 50 °C for 0.5 h (the stirring rate is 600 rpm). After that, filter, wash the obtained solid product with distilled water until the pH of the filtrate is 5, carry out vacuum filtration, and freeze-dry the filter cake to obtain the doped polyaniline.

[0069] Example 2

[0070] Carry out according to Example 1, except that the reaction time is adjusted to 12 h.

[0071] Example 3

[0072] Carry out according to Example 1, except that the reaction time is adjusted to 24 h.

[0073] Example 4

[0074] Weigh 1 g of the intrinsic polyaniline and place it in a reactor. Add an aqueous solution of hydroxyethane diphosphonic acid (mass fraction is 60%) to the reactor, wherein the molar ratio of hydroxyethane diphosphonic acid to the phenylenediamine unit in the polyaniline is 2:1. Then add 15 mL of deionized water for dilution. Then, carry out a constant-temperature stirring reaction at 10 °C for 6 h (the stirring rate is the same as that in Example 1). After that, filter, wash the obtained solid product with distilled water until the pH of the filtrate is 5, carry out vacuum filtration, and freeze-dry the filter cake to obtain the doped polyaniline.

[0075] Example 5

[0076] Carry out according to Example 4, except that the reaction temperature is adjusted to 60 °C.

[0077] Example 6

[0078] Weigh 1 g of the intrinsic polyaniline and place it in a reactor. Add an aqueous solution of hydroxyethane diphosphonic acid (mass fraction: 60%) to the reactor. Here, the molar ratio of hydroxyethane diphosphonic acid to the phenylenediamine unit in the polyaniline is 0.3:1. Then add 15 mL of deionized water for dilution. Next, carry out a constant-temperature stirring reaction at 30 °C for 6 h (the stirring rate is the same as in Example 1). After that, filter, wash the obtained solid product with distilled water until the pH of the filtrate is 5, carry out vacuum filtration, and freeze-dry the filter cake to obtain the doped polyaniline.

[0079] Example 7

[0080] Carry out according to Example 6, except that the molar ratio of hydroxyethane diphosphonic acid to the phenylenediamine unit in the polyaniline is 2.5:1.

[0081] Example 8

[0082] Carry out according to Example 6, except that the molar ratio of hydroxyethane diphosphonic acid to the phenylenediamine unit in the polyaniline is 1.5:1.

[0083] Product Test :

[0084] (1) Scanning electron microscopy (SEM) characterization

[0085] The SEM images of the intrinsic polyaniline and the doped polyaniline obtained in Example 8 are respectively as Figure 1-2 shown. It can be seen that compared with the intrinsic polyaniline, the particle size of the doped polyaniline obtained in Example 8 is significantly reduced, Figure 2 and the diameter of a single particle in the agglomerated particle group has decreased to less than 1.5 μm.

[0086] (2) X-ray photoelectron spectroscopy (XPS) analysis

[0087] The XPS spectra of the intrinsic polyaniline and the doped polyaniline obtained in Example 8 are respectively as Figure 3-4 shown. Figure 3 In [it], the peak position at 399.68 eV in the XPS spectrum of the intrinsic state represents the aniline unit, and the peak position at 398.83 eV represents the quinone imine unit. The ratio of the peak areas of the two is approximately 1:1, proving that the intrinsic polyaniline is not doped; Figure 4 In [it], the peak position at 401.28 eV represents the protonated imine unit, and 399.31 eV represents the aniline unit. The ratio of the peak area at the protonated imine unit to the total peak area represents the doping degree, and this doping degree is 20.63%.

[0088] The doped polyanilines of Examples 1 - 8 and Comparative Example 1 were all subjected to the above tests, and the results are shown in Table 1.

[0089] Table 1: Test effects of the products obtained in each example and comparative example

[0090] Single Particle Diameter in the Product Doping Level Example 1 2-3μm 14.53％ Example 2 1-2μm 18.03％ Example 3 0.8-2μm 19.35％ Example 4 0.8-2μm 19.35％ Example 5 0.8-1.8μm 20.03％ Example 6 1-2μm 17.36％ Example 7 0.6-1.5μm 21.26％ Example 8 Less than 1.5μm 20.63％

[0091] As can be seen from the test results in Table 1, Examples 1-8 of the present invention have a good doping degree and reduced the particle size of polyaniline. Among them, the comprehensive effects of Examples 7-8 are the best.

[0092] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements approximately the same as the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for preparing acid-doped polyaniline, characterized in that: The following steps are involved: The polyaniline reacts with the organic acid in a solvent medium, and then the solid-liquid separation is performed, and the obtained solid product is washed and dried to obtain the acid-doped polyaniline; in, The organic acid is hydroxyethylene diphosphoric acid.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the organic acid to the phenylenediamine unit in the polyaniline is (0.3-2.5):

1.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the organic acid to the phenylenediamine unit in the polyaniline is 1.5:

1.

4. The preparation method according to claim 1, characterized in that: The reaction temperature is 10-60°C and the reaction time is 0.5-24h.

5. The preparation method according to claim 1 or 4, characterized in that: The reaction temperature is 30°C and the reaction time is 6 hours.

6. The preparation method according to claim 1, characterized in that: The polyaniline, organic acid and solvent medium are contacted in any one of the following ways (1) to (3): Method (1): Add polyaniline and organic acid solution into a container respectively, and then add solvent to dilute; Method (2): adding polyaniline and the diluted organic acid solution into a container and mixing them; Method (3): polyaniline, organic acid and solvent are added into a container and mixed respectively; In the method (1), the mass fraction of the organic acid solution is 55% to 65%; when the solvent is added for dilution, the ratio of the amount of the solvent added to the amount of polyaniline is (10 to 20) mL: 1 g.

7. The preparation method according to claim 1, characterized in that: The solvent is water; The degree of washing is to wash until the pH of the washed solution is 4.5 to 6; The drying is freeze-drying.

8. An acid-doped polyaniline, characterized in that: The method is prepared according to any one of claims 1 to 7.

9. An anticorrosive coating, characterized in that: The polyaniline is the acid-doped polyaniline as claimed in claim 8.

10. The anticorrosive coating according to claim 9, characterized in that: include: Polyaniline and epoxy resin.

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