Epoxy-based polyaniline and method of making and use thereof

Abstract

The application discloses epoxy-based polyaniline and a preparation method and application thereof. The preparation method of the epoxy-based polyaniline comprises the following steps: (1) preparing epoxy phosphate: after mixing bisphenol A type epoxy resin and phosphoric acid, the phosphoric acid attacks the epoxy ring of the bisphenol A type epoxy resin, and a ring-opening reaction occurs with the epoxy to form the epoxy phosphate; (2) in-situ polymerization of polyaniline: aniline is dispersed in the epoxy phosphate, a peroxidation agent is added dropwise under the condition of-5-5 DEG C, and the in-situ polymerization reaction of the aniline in the epoxy phosphate obtains the epoxy-based polyaniline. The epoxy-based polyaniline can reach nanometer scale and excellent dispersibility, so that the coating has excellent water resistance, salt fog resistance and adhesion.

Description

Technical Field

[0001] This invention belongs to the field of waterborne epoxy resin coating technology, and particularly relates to an epoxy-based polyaniline, its preparation method and application. Background Technology

[0002] Metal corrosion not only causes huge economic losses but also threatens people's lives. Anti-corrosion coatings offer the most economical and effective protection for metals. However, oil-based anti-corrosion coatings contain large amounts of VOCs, posing a significant threat to the human environment. Therefore, the development of water-based epoxy anti-corrosion coatings has been booming in recent years. Due to the film-forming characteristics of water-based epoxy resins, the film density is poor, resulting in lower protective performance compared to solvent-based coatings. To improve the performance of water-based epoxy anti-corrosion coatings, researchers have done a lot of work, with increasing attention paid to nanomaterial modification. Due to the unique characteristics of the nanoscale, adding even small amounts can achieve significant improvements. However, uniform dispersion of nanomaterials in organic coating systems is a prerequisite for obtaining good performance. Recently, researchers have also focused on improving the dispersibility of nanomaterials in water-based coatings through modification.

[0003] Polyaniline (PANI) is a highly attractive conductive polymer due to its advantages such as good protective effect, environmental stability, low cost, and ease of synthesis. Its redox properties and conductivity make it a promising candidate for corrosion protection and a top green alternative to chromium salts. However, its rigid structure makes processing difficult, and its insolubility in common solvents and water results in poor dispersion in coating systems, which can actually accelerate corrosion, hindering its application in the coatings industry. Environmental considerations necessitate improvements to its solubility and dispersibility in water.

[0004] Currently, the dispersion of commonly used polyaniline nanofibers requires homogenizers or high-speed, long-duration dispersion to achieve good dispersion results, which is difficult to achieve in actual industrial production. Generally, after polyaniline polymerization, it needs to be filtered, washed, and dried; before use, it also needs to be ground or dispersed in a solvent using equipment such as ultrasonic homogenizers before being added to the coating system. This method is not only cumbersome, but the mechanical dispersion effect is also not ideal, and the cumbersome process is a challenge for scale-up applications. Therefore, how to improve the dispersion uniformity of polyaniline in polymers is an urgent problem to be solved.

[0005] The known chemical modification methods for improving the solubility of polyaniline mainly include: (1) using proton organic acids and proton inorganic acids to dope PANI, which can improve its solubility and conductivity; however, due to the presence of hydrophilic groups, the corrosion resistance of polyaniline may be impaired. (2) aniline emulsion polymerization is carried out by chemical modification (such as inserting substitutes on benzene rings or nitrogen) or by adding steric stabilizers (such as surfactants, water-soluble polymers). By introducing substituent groups into the PANI structure, the solubility or dispersibility in water can be improved, and its mechanical properties and processability can be improved. Although these methods can improve the solubility of polyaniline, they still require complicated processes when added to coating systems. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing epoxy-based polyaniline, the method comprising the following steps: (1) Preparation of epoxy phosphate: Bisphenol A type epoxy resin and phosphoric acid are mixed and the phosphoric acid attacks the epoxy ring of the bisphenol A type epoxy resin and undergoes a ring-opening reaction with the epoxy to form epoxy phosphate;

[0007] (2) In-situ polymerization of polyaniline: Aniline is dispersed in epoxy phosphate ester, and peroxidant is added dropwise at -5~5℃. Aniline undergoes in-situ polymerization in epoxy phosphate ester to obtain epoxy polyaniline.

[0008] According to an embodiment of the present invention, in step (1), the preparation of the epoxy phosphate specifically includes: stirring and mixing the epoxy resin in the mixed solvent of the first part, heating to 40-70℃ (preferably 50-60℃), adding dropwise 50-150g (preferably 80-120g) of phosphoric acid (mass fraction, for example, 25%) and 20-100g (preferably 40-70g) of the mixed solvent of the second part, controlling the dropping speed to complete the dropping within 30-120min (preferably 50-80min), after the dropping is completed, continuing mechanical stirring, maintaining the temperature for 3-8h (preferably 5-7h) to reach the reaction endpoint, and then cooling down.

[0009] Preferably, the ring-opening reaction is carried out in an apparatus known in the art, such as a three-necked flask equipped with a spherical condenser, a constant-pressure separatory funnel, and a mechanical stirrer.

[0010] Preferably, the mixed solvent is selected from acetone and butanone. Further, the volume ratio of acetone to butanone is 1:1.

[0011] Preferably, the mass ratio of epoxy resin to the mixed solvent in the first part is 50-400g:50-200g, more preferably 50-400g:150-250g, 80-150g:50-200g, or 80-150g:150-250g.

[0012] According to an embodiment of the present invention, in step (2), the ratio of epoxy phosphate to aniline is 80-300g:0.1-5g, preferably 80-300g:1-3g or 140-180g:0.1-5g, more preferably 140-180g:1-3g.

[0013] According to an embodiment of the present invention, in step (2), the peroxidant is selected from at least one of ammonium persulfate (APS), hydrogen peroxide (H2O2), and metal salt oxidants (such as ferric chloride and copper chloride), preferably ammonium persulfate.

[0014] According to an embodiment of the present invention, in step (2), the epoxy phosphate ester and aniline are mixed and stirred until transparent before an aqueous solution of the peroxidant is added dropwise. Preferably, the mass concentration of the peroxidant in the aqueous solution is 1%-50%, for example, 10%, 12%, 15%, 20%, 30%, 40%, or any two of the above values.

[0015] According to an embodiment of the present invention, in step (2), the aqueous solution of the peroxidant is preferably added dropwise within 20-40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes or any two of the above values.

[0016] According to an embodiment of the present invention, in step (2), the in-situ polymerization reaction is carried out under ice bath conditions of -5~5℃ (for example, 0℃, or for example, -4℃, -3℃, -2℃, -1℃, 0℃, 1℃, 2℃, 3℃, 4℃, 5℃ or any two of the above values); the time of the in-situ polymerization reaction is 2-10h, preferably 4-7h, for example 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or any two of the above values.

[0017] According to the embodiment of the present invention, in step (2), after the in-situ polymerization reaction is completed, the reaction product is added to a centrifuge tube, centrifuged at high speed, the upper dilute solution is removed, and the lower viscous dark green reaction product is retained, which is epoxy polyaniline.

[0018] The present invention also provides an epoxy-based polyaniline, which is obtained by the above preparation method.

[0019] Preferably, the epoxy-based polyaniline is obtained by in-situ polymerization of aniline in epoxy phosphate ester.

[0020] According to an embodiment of the present invention, the raw materials of the epoxy-based polyaniline include aniline and epoxy phosphate, which have the meanings described above.

[0021] The present invention also provides the application of the above-mentioned epoxy-based polyaniline in the preparation of waterborne epoxy varnishes or waterborne epoxy coatings.

[0022] This invention also provides a polyaniline waterborne epoxy varnish, wherein the raw materials of the polyaniline waterborne epoxy varnish include: Epoxy resin 50-120g; Epoxy-based polyaniline 1-20g; 50-120g of curing agent; 10-100g of deionized water.

[0023] According to an embodiment of the present invention, in the polyaniline waterborne epoxy varnish, the epoxy resin is selected from epoxy resins known in the art, such as epoxy resin HDE3267-WB.

[0024] According to an embodiment of the present invention, the amount of epoxy resin used in the polyaniline waterborne epoxy varnish is preferably 60-90g, for example 80g.

[0025] According to an embodiment of the present invention, in the polyaniline waterborne epoxy varnish, the curing agent is selected from curing agents known in the art, such as curing agent HDH6815-WB.

[0026] According to an embodiment of the present invention, the amount of curing agent used in the polyaniline waterborne epoxy varnish is preferably 60-90g, for example 80g.

[0027] According to an embodiment of the present invention, the amount of epoxy-based polyaniline in the polyaniline waterborne epoxy varnish is preferably 6-9g, for example 8g.

[0028] According to an embodiment of the present invention, the amount of deionized water used in the polyaniline waterborne epoxy varnish is preferably 15-50g, for example 27g.

[0029] According to an embodiment of the present invention, in the polyaniline waterborne epoxy varnish, the mass ratio of epoxy resin to epoxy-based polyaniline is 50-120g:1-20g, preferably 50-120g:6-9g, 60-90g:1-20g, or 60-90g:1-20g.

[0030] According to an embodiment of the present invention, the preparation method of the polyaniline waterborne epoxy varnish includes: mixing the raw materials of the above-mentioned polyaniline waterborne epoxy varnish and then dispersing them at high speed.

[0031] According to an embodiment of the present invention, the polyaniline waterborne epoxy varnish is a homogeneous epoxy emulsion.

[0032] According to an embodiment of the present invention, the epoxy-based polyaniline particles in the polyaniline waterborne epoxy varnish can reach the nanoscale and are uniformly dispersed in the polyaniline waterborne epoxy varnish.

[0033] The present invention also provides a clear varnish film, which is prepared by the above-mentioned polyaniline waterborne epoxy clear varnish.

[0034] According to an embodiment of the present invention, the paint film is smooth and dense, without obvious particles.

[0035] According to an embodiment of the present invention, the varnish film has a salt spray resistance of over 500 hours and excellent adhesion to the substrate, reaching grade 0.

[0036] According to an embodiment of the present invention, when preparing the above-mentioned polyaniline waterborne epoxy varnish, it is not necessary to separately disperse the polyaniline using an ultrasonic or homogenizer; it can be directly mixed with the epoxy resin.

[0037] Beneficial effects 1. In this invention, epoxy phosphate is first synthesized. Due to the properties of phosphoric acid, epoxy phosphate is acidic. Epoxy phosphate is used as the dopant acid in the synthesis of polyaniline. In the epoxy phosphate system, epoxy-based polyaniline is prepared by in-situ polymerization using chemical oxidation polymerization. The method is simple and does not require drying or grinding. The resulting coating film is smooth and dense. 2. The epoxy-based polyaniline obtained by this invention can be directly blended with hydrophilically modified epoxy resin without prior ultrasonic or homogenization to prepare a dispersion. This allows for the immediate acquisition of a uniformly dispersed polyaniline-modified epoxy coating, which is essentially no different from conventional coating preparation methods and is easily industrialized. Because the epoxy-based polyaniline of this invention can reach the nanoscale and exhibits excellent dispersibility, the coating possesses superior water resistance, salt spray resistance, and adhesion. Attached Figure Description

[0038] Figure 1 The results are from the dispersion stability test of the epoxy-based polyaniline in Example 1.

[0039] Figure 2 The results show the dispersion stability of the epoxy phosphate-polyaniline mixture in Comparative Example 3. Detailed Implementation

[0040] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0041] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0042] Example 1 Synthesis of epoxy phosphate: 200g of acetone / butanone (1:1) mixture and 100g of epoxy resin were added to a three-necked flask equipped with a spherical condenser, a constant pressure separatory funnel, and a mechanical stirrer. The mixture was stirred thoroughly and heated to 55℃. 85g of 25% phosphoric acid and 40g of acetone / butanone (1:1) mixture were added dropwise, controlling the dropping rate to complete the addition in 55min. After the addition was completed, the mixture was continuously stirred mechanically and the temperature was maintained for 6h to reach the reaction endpoint. The mixture was then cooled to obtain epoxy phosphate for later use.

[0043] Take 150g of the epoxy phosphate synthesized in the previous step and add 1.5g of aniline to a three-necked flask equipped with a spherical condenser, a constant pressure separatory funnel, and a mechanical stirrer. Stir thoroughly until dissolved and transparent. Set the ice bath temperature to 0℃, and then add 35g of an aqueous solution containing 4.2g of APS dropwise over 25 minutes. After the addition is complete, maintain the ice bath condition and react for 5 hours. After the reaction is complete, add the reaction product to a centrifuge tube and centrifuge at high speed. Remove the upper dilute solution and keep the lower viscous dark green reaction product. This product is epoxy-based polyaniline.

[0044] 70g of HDE3267-WB and 7g of epoxy polyaniline are dispersed and mixed evenly. Then, 75g of HDH6815-WB curing agent with emulsifying properties and 40g of deionized water are added and continuously dispersed at high speed to prepare a uniform epoxy emulsion.

[0045] Take 2g of epoxy-based polyaniline, dilute it with 5g of acetone, and immediately coat it onto a cold-rolled steel plate with a 100μm wire rod to form a dry film with a thickness of 30±3 micrometers. The dry film is dark green, dense and uniform, and has no obvious particles.

[0046] The above-mentioned epoxy polyaniline was combined with waterborne epoxy emulsion and a curing agent to prepare an epoxy varnish dry film, which was then coated onto a cold-rolled steel plate with a 150μm wire rod to obtain a dry film thickness of 40±5μm.

[0047] Example 2 Synthesis of epoxy phosphate: 180g of acetone / butanone (1:1) mixture and 90g of epoxy resin were added to a three-necked flask equipped with a spherical condenser, a constant pressure separatory funnel, and a mechanical stirrer. The mixture was stirred thoroughly and heated to 60℃. 80g of 25% phosphoric acid and 40g of acetone / butanone (1:1) mixture were added dropwise, controlling the dropping rate to complete the addition in 50min. After the addition was completed, the mixture was continuously stirred mechanically and the temperature was maintained for 5h to reach the reaction endpoint. The mixture was then cooled to obtain epoxy phosphate for later use.

[0048] Take 160g of the epoxy phosphate synthesized in the previous step and add 1.86g of aniline to a three-necked flask equipped with a spherical condenser, a constant pressure separatory funnel, and a mechanical stirrer. Stir thoroughly until dissolved and transparent. Set the ice bath temperature to 0℃, and then add 40g of an aqueous solution containing 4.56g of APS dropwise over 30 minutes. After the addition is complete, maintain the ice bath condition and react for 6 hours. After the reaction is complete, add the reaction product to a centrifuge tube and centrifuge at high speed. Remove the upper dilute solution and keep the lower viscous dark green reaction product. This product is epoxy-based polyaniline.

[0049] 80g of HDE3267-WB and 8g of epoxy polyaniline are dispersed and mixed evenly. Then, 80g of HDH6815-WB curing agent with emulsifying properties and 45g of deionized water are added and continuously dispersed at high speed to prepare a uniform epoxy emulsion.

[0050] Comparative Example 1 80g of HDE3267-WB is added to 80g of HDH6815-WB curing agent with emulsifying properties and 45g of deionized water, and continuously dispersed at high speed to prepare a uniform epoxy emulsion.

[0051] Comparative Example 2 Synthesis of polyaniline: 1.86 g of aniline monomer was added to 100 ml of aqueous solution containing 9.8 g of concentrated hydrochloric acid. The mixture was allowed to stand in an ice bath for 30 min. In a separate beaker, 4.56 g of ammonium persulfate was added to 50 ml of aqueous solution containing 4.9 g of concentrated hydrochloric acid. Stirring was started, and the mixture was allowed to stand in an ice bath for 30 min. Then, the APS aqueous solution was added dropwise to the above aniline-HCl solution. Polymerization was carried out for 5 h. The resulting reactants were filtered and washed repeatedly with ethanol and distilled water to remove unreacted acid, monomers, and oligomers. The product was then placed in a forced-air drying oven at 70 degrees Celsius for 24 h. After drying, the product was ground into powder for later use.

[0052] 80g of HDE3267-WB and 0.8g of polyaniline prepared in this comparative example were ultrasonically treated for ten minutes using a cell wall disruptor. 80g of HDH6815-WB curing agent with emulsifying properties and 45g of deionized water were then added and continuously dispersed at high speed to prepare a uniform epoxy emulsion.

[0053] Comparative Example 3 Epoxyphosphate was prepared according to Example 1; polyaniline was prepared according to Comparative Example 2; Epoxy phosphate and polyaniline were mixed in a mass ratio of 150g:4.5g using a high-speed homogenizer to obtain an epoxy phosphate-polyaniline mixture. 80g of HDE3267-WB and 8g of epoxy phosphate-polyaniline mixture are dispersed and mixed evenly. Then, 80g of HDH6815-WB curing agent with emulsifying properties and 45g of deionized water are added and continuously dispersed at high speed to prepare a uniform epoxy emulsion.

[0054] Comparative Example 4 Epoxyphosphate was prepared according to the method in Example 1, except that the polymerization temperature was changed to room temperature. Specifically, 150g of epoxyphosphate was taken, and 1.5g of aniline was added. After thorough stirring until dissolved and transparent, the water bath temperature was set to 25°C (room temperature). Then, 35g of an aqueous solution containing 4.2g of APS was added dropwise over 25 minutes. After the addition was completed, the reaction was maintained at room temperature for 5 hours. After the reaction was completed, the product was centrifuged to obtain a dark green product, which was denoted as epoxy-coated polyaniline-room temperature.

[0055] 70g of HDE3267-WB and 7g of epoxy polyaniline at room temperature were dispersed and mixed evenly. 75g of curing agent HDH6815-WB and 40g of deionized water were added and dispersed continuously at high speed to prepare an epoxy emulsion.

[0056] Comparative Example 5 Epoxyphosphate was prepared according to the method in Example 1, except that the oxidant was added rapidly. Specifically, 150g of epoxyphosphate was taken, and 1.5g of aniline was added. After thorough stirring until dissolved and transparent, the ice bath temperature was set to 0°C. Then, 35g of an aqueous solution containing 4.2g of APS was rapidly added dropwise over 5 minutes. After the addition was completed, the reaction was maintained under ice bath conditions for 5 hours. After the reaction was completed, centrifugation was performed to obtain a dark green product, which was denoted as epoxy-coated polyaniline-rapidly added.

[0057] The epoxy emulsion was prepared using the same method as in Example 1, except that the epoxy-based polyaniline was replaced with the epoxy-based polyaniline of Example 1 by rapid drop-addition.

[0058] Comparative Example 6 Epoxyphosphate was prepared according to the method in Example 1, with the difference that the polymerization reaction time was changed to 1 hour. Specifically, 150 g of epoxyphosphate was taken, 1.5 g of aniline was added, and after thorough stirring until dissolved and transparent, the ice bath temperature was set to 0°C. 35 g of aqueous solution containing 4.2 g of APS was added dropwise over 25 minutes. After the addition was completed, the reaction was maintained under ice bath conditions for 1 hour. After the reaction was completed, centrifugation was performed to obtain a dark green product, which was denoted as epoxy-based polyaniline-short time.

[0059] The epoxy emulsion was prepared using the same method as in Example 1, except that the epoxy-based polyaniline was temporarily substituted for the epoxy-based polyaniline in Example 1.

[0060] Test Example 1 The epoxy-based polyaniline prepared in Example 1 was designated as Sample A, and the epoxy phosphate-polyaniline mixture prepared in Comparative Example 3 was designated as Sample B. Stability tests were conducted on both samples. Take 10g of sample A and 10g of sample B respectively, add 50g of acetone to each and dilute 5 times, stir thoroughly to disperse evenly. After standing for 2 hours, invert both containers simultaneously and observe the precipitation at the bottom of the bottles.

[0061] See results Figure 1 and 2 After inverting the bottle, a large amount of black polyaniline precipitate was clearly visible at the bottom of sample B (physical mixing), indicating that ordinary polyaniline cannot be stably dispersed in epoxy phosphate ester by physical mixing alone and is prone to sedimentation; while after inverting the bottle, sample A (epoxy polyaniline of the present invention) showed no visible precipitate at the bottom of the bottle and the dispersion was uniform, indicating that in the epoxy polyaniline obtained by in-situ polymerization, polyaniline exists stably in the epoxy phosphate ester matrix at the nanoscale and has excellent anti-settling ability and storage stability.

[0062] Test Example 2 Preparation methods for water resistance, salt spray resistance, and adhesion: Take several cold-rolled steel plates and perform the following pretreatment: first, put the cold-rolled steel plates into acetone reagent for ultrasonic treatment to remove the protective oil on the surface, wipe them dry, and polish them with 240-grit sandpaper to remove the oxide layer on the surface. Then wipe the surface with ethanol, let them dry and set them aside for use. A certain amount of the epoxy emulsions obtained in the above examples and comparative examples were respectively taken and coated onto several pretreated cold-rolled steel plates with a 200-micron wire rod. After curing at room temperature for 7 days, a paint film with a thickness of 40±2 microns was obtained. Since the curing agent is alkaline, the epoxy emulsion system turned blue-black after the curing agent was added. The paint film obtained by the epoxy emulsion in Example 1 had a smooth surface and no particles.

[0063] Cold-rolled steel sheets with different paint films were used as samples for the following tests, and the results are recorded in Table 1: 1) Water resistance: Immerse 2 / 3 of the samples containing different paint films in a room temperature water bath for 48 hours, and observe with the naked eye whether the paint film blisters, rusts, and whitens. 2) Salt spray resistance: Samples with different paint films were back-sealed and edge-sealed, then placed in a neutral salt spray chamber for observation. The time it took for the paint film to show signs of corrosion was recorded. The specific experimental method was as follows: referring to the salt spray test standard ISO 9227; in the neutral salt spray chamber, a 3.5 wt.% NaCl aqueous solution (neutral, pH 6~7) was used as the spray solution, the test chamber temperature was 35 ºC, and the salt spray deposition rate was 1.2~1.3 mL / (80cm). 2 ·h); 3) Adhesion: The adhesion of samples containing different paint films was tested using the cross-cut adhesion test (refer to the national standard GB / T9286-1998).

[0064] Table 1 Performance Test Results

[0065] Compare the test results in the table above: As can be seen from Examples 1-2 and Comparative Examples 1-3, the epoxy-based polyaniline obtained by the preparation method of this application not only has higher adhesion but also better water resistance and salt spray resistance when used to prepare varnish films.

[0066] In addition, Comparative Example 4, which increased the polymerization temperature to room temperature, showed a significant decrease in the anti-corrosion performance of the resulting epoxy polyaniline (salt spray resistance for only 120h), indicating that low temperature conditions (-5~5℃) are key to obtaining high-performance products. Comparative Example 5, which shortened the oxidant addition time to 5 minutes, resulted in an overly vigorous polymerization reaction, poor product dispersibility, and a decrease in salt spray resistance to 180h. Comparative Example 6, which shortened the polymerization reaction time to 1 hour, resulted in incomplete polymerization, with a large amount of unreacted monomers remaining in the product. The coating's salt spray resistance was only 140h, and the adhesion also decreased to level 2.

[0067] The above test results fully demonstrate that the polymerization conditions (-5~5℃, dropping time 20-40min, reaction time 2-10h) specified in this invention can yield epoxy polyaniline with excellent dispersibility and the best anti-corrosion performance.

[0068] The exemplary embodiments of the present invention have been described above. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing epoxy-based polyaniline, characterized in that, The preparation method includes the following steps: (1) Preparation of epoxy phosphate: Bisphenol A type epoxy resin and phosphoric acid are mixed and the phosphoric acid attacks the epoxy ring of the bisphenol A type epoxy resin and undergoes a ring-opening reaction with the epoxy to form epoxy phosphate; (2) In-situ polymerization of polyaniline: Aniline is dispersed in epoxy phosphate ester, and peroxidant is added dropwise at -5~5℃. Aniline undergoes in-situ polymerization in epoxy phosphate ester to obtain epoxy polyaniline.

2. The preparation method according to claim 1, characterized in that, In step (1), the preparation of the epoxy phosphate specifically includes: stirring and mixing the epoxy resin in the mixed solvent of the first part, heating to 40-70℃, adding 50-150g of phosphoric acid and 20-100g of the mixed solvent of the second part dropwise, controlling the dropping rate to complete the dropping within 30-120min, and after the dropping is completed, continuing mechanical stirring, maintaining the temperature for 3-8h to reach the reaction endpoint, and then cooling down; The mass ratio of epoxy resin to the mixed solvent in the first part is 50-400g:50-200g.

3. The preparation method according to claim 1, characterized in that, In step (2), the ratio of epoxy phosphate to aniline is 80-300g: 0.1-5g; In step (2), the peroxidant is selected from at least one of ammonium persulfate, hydrogen peroxide, and metal salt oxidants; In step (2), epoxy phosphate is mixed and stirred with aniline until transparent before adding an aqueous solution of peroxide; In step (2), the aqueous solution of the peroxidant is added dropwise over 20-40 minutes.

4. The preparation method according to claim 1, characterized in that, In step (2), the in-situ polymerization reaction is carried out under ice bath conditions of -5~5℃.

5. An epoxy-based polyaniline, characterized in that, The epoxy-based polyaniline is obtained by the preparation method according to any one of claims 1-4.

6. The epoxy-based polyaniline according to claim 5, characterized in that, The epoxy-based polyaniline is obtained by in-situ polymerization of aniline in epoxy phosphate.

7. The use of the epoxy-based polyaniline according to claim 5 or 6 in the preparation of waterborne epoxy varnishes or waterborne epoxy coatings.

8. A polyaniline waterborne epoxy varnish, characterized in that, The raw materials for the polyaniline waterborne epoxy varnish include: Epoxy resin 50-120g; Epoxy polyaniline 1-20g; 50-120g of curing agent; 10-100g of deionized water.

9. The polyaniline waterborne epoxy varnish according to claim 8, characterized in that, In the aforementioned polyaniline waterborne epoxy varnish, the mass ratio of epoxy resin to epoxy-based polyaniline is 50-120g:1-20g.

10. A clear varnish film, characterized in that, The coating film is prepared by the polyaniline waterborne epoxy varnish as described in claim 8 or 9.

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