A high-conductivity adhesion promoter coating material, its preparation method and application

Abstract

The present application relates to a kind of high conductive adhesion promoter paint and its preparation method and application, belong to the field of coating.The paint provided by the present application includes raw material has: conductive primer, chlorinated polypropylene resin, anti-settling slurry, regulator, adhesion promoter and solvent.The conductive primer is added, and the resistance of coating film is significantly reduced, so that the paint can meet the requirements of electrostatic spraying;Chlorinated polypropylene resin and adhesion promoter are used as main body, and the compatibility is good, which significantly improves the adhesion between the paint and substrate, topcoat, and has good compatibility with color paint and topcoat;The addition of anti-settling slurry gives the paint good anti-settling performance and spraying stability.The paint prepared by the above formula is applied to the primer spraying construction of automobile bumper, and has the advantages of good compatibility, high conductivity and long-term adhesion of the formed paint film.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a high-conductivity adhesion promoter coating, its preparation method, and its application. Background Technology

[0002] With the increasing demand for lightweight vehicles, plastic parts have become the preferred choice for automotive interior and exterior components. Polypropylene (PP), due to its light weight, excellent overall performance, wide availability, and low price, has been successfully applied to many automotive parts. The car bumper is one such successful example.

[0003] PP can well meet the requirements of lightweight, heat resistance, weather resistance, and impact resistance for bumpers. However, due to its high crystallinity, strong resistance to solvent corrosion, and low surface energy, ordinary coatings are difficult to adhere to. To solve this problem, methods such as corona discharge, flame treatment, or chemical oxidation have been used to activate the substrate surface to improve the adhesion between the coating and the substrate. However, these methods have problems such as low safety, short application time, and unsatisfactory long-term adhesion.

[0004] Furthermore, the PP coatings currently on the market have the following problems: (1) poor workability, short storage period, and easy roughening; (2) ordinary PP coatings are not conductive and do not support electrostatic rotary cup spraying; (3) ordinary PP coatings have poor water resistance and poor adhesion during rework. Therefore, it is of practical significance to improve and upgrade the formulation of PP coatings, and the development of coatings with high conductivity and strong adhesion has broad market prospects. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a high-conductivity adhesion promoter coating and its preparation method, and to apply it to the primer spraying of automobile bumpers.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A high-conductivity adhesion promoter coating comprises the following raw materials in weight percentages:

[0008] Conductive primer 40-45%

[0009] Chlorinated polypropylene resin A 8-12%

[0010] Anti-settling slurry 10-15%

[0011] Regulator 0.2-0.5%

[0012] Adhesion promoter 6-10%

[0013] Solvent A: 20-30%.

[0014] In this invention, the combined use of chlorinated polypropylene resin and an adhesion promoter significantly improves the adhesion of the coating to the substrate, effectively enhancing the coating's water resistance, heat resistance, and compatibility among the raw materials. The addition of a conductive primer imparts excellent conductivity to the coating, with a dry film resistance value below 0.5 MΩ, meeting the requirements of electrostatic spraying. The addition of an anti-settling agent significantly improves the coating's anti-settling performance and spraying stability. The addition of a regulator eliminates trace amounts of moisture in the system, thus solving problems such as gloss loss, yellowing, and blistering caused by moisture during coating preparation. The high-conductivity adhesion promoter coating obtained by the above formulation of this invention features high conductivity, strong adhesion, water resistance, and good weather resistance.

[0015] Furthermore, the conductive primer comprises the following raw materials in weight percentages:

[0016] Chlorinated polypropylene resin B 20-50%

[0017] Dispersant B 1-6%

[0018] Fumed silica B 0.2-0.6%

[0019] Conductive carbon black 1-4%

[0020] Titanium dioxide 10-30%

[0021] Solvent B 20-56%.

[0022] Furthermore, the preparation method of the conductive primer includes the following steps:

[0023] Step 1: Add chlorinated polypropylene resin B and dispersant B to a mixer and stir for 10-30 minutes;

[0024] Step 2: Add fumed silica B, conductive carbon black and titanium dioxide and continue stirring for 10-30 minutes;

[0025] Step 3: Add solvent B to the slurry obtained in Step 2 to adjust the viscosity, stir for 10-30 minutes, and let it soak for 20-32 hours;

[0026] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the conductive primer.

[0027] In this invention, the conductive primer is based on chlorinated polypropylene resin, with conductive carbon black added to provide conductivity. The addition of a dispersant and fumed silica effectively improves the dispersibility and stability of the conductive primer system. The conductive primer obtained through the above formulation exhibits good conductivity and stability.

[0028] Furthermore, this invention improves the conductivity of conductive carbon black by surface modification. The specific modification method is as follows: 3,4-ethylenedioxythiophene is added to an aqueous solution of sodium polystyrene sulfonate and mixed evenly. The mixture is then transferred to an ice-water bath, and conductive carbon black is added and dispersed evenly. The pH of the solution mixture is adjusted to 2 by adding dilute hydrochloric acid solution. Then, ammonium persulfate is dissolved in water and slowly added dropwise to the reaction mixture. The mixture is reacted in an ice-water bath for 6 hours, then transferred to room temperature and reacted for another 18 hours. After filtration, centrifugation, and washing, poly(3,4-ethylenedioxythiophene)-coated conductive carbon black is obtained.

[0029] In this invention, poly(3,4-ethylenedioxythiophene) has the characteristics of high conductivity, good film-forming properties and stability. By coating the surface of conductive carbon black with poly(3,4-ethylenedioxythiophene) through the above modification method, the conductivity and stability of conductive carbon black can be significantly improved, and it is also beneficial to improve the dispersibility of conductive carbon black in the resin system.

[0030] Furthermore, the anti-settling slurry comprises the following raw materials in weight percentages:

[0031] Chlorinated polypropylene resin C 20-40%

[0032] Dispersant C 0.2-0.6%

[0033] Fumed silica (C) 5-11%

[0034] Solvent C 50-75%.

[0035] Furthermore, the preparation method of the anti-settling slurry includes the following steps:

[0036] Step 1: Add chlorinated polypropylene resin C and dispersant C to a mixer and stir for 10-30 minutes;

[0037] Step 2: Add fumed silica C and continue stirring for 10-30 minutes;

[0038] Step 3: Add solvent C to the slurry obtained in Step 2 to adjust the viscosity, stir for 10-30 minutes, and let it soak for 20-32 hours;

[0039] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the anti-settling slurry.

[0040] This invention uses chlorinated polypropylene resin as the main component, and adds dispersant C and fumed silica C to stir and grind to prepare an anti-settling slurry. The combined effect of dispersant C and fumed silica C gives the coating good anti-settling properties and spraying stability.

[0041] Furthermore, solvent A, solvent B, and solvent C are each selected from one or more combinations of toluene, xylene, and trimethylbenzene.

[0042] Furthermore, the adhesion promoter is polyphenylene ether resin.

[0043] In this invention, the polyphenylene ether resin is preferably a modified polyphenylene ether resin, and the preparation method of the modified polyphenylene ether resin is as follows:

[0044] S1. Weigh 4-aminobenzoic acid, maleic anhydride and acetic acid and place them in a reactor and stir. Heat and reflux until the reaction system changes from a suspension to a uniform solution, then stop the reaction. Cool to room temperature to precipitate a pale yellow solid. After filtration, washing and drying, extract with chloroform for 24 hours. Remove the solvent by rotary evaporation to obtain a white powder.

[0045] S2. Weigh the white powder obtained in step S1, add thionyl chloride, heat to 80°C under N2 atmosphere and react for 3-4 hours, cool to room temperature to precipitate solid, filter and dry to obtain orange-yellow crystals, and then recrystallize with toluene to obtain light yellow crystals.

[0046] S3. Weigh the light yellow crystals obtained in step S2, add ethylene glycol dimethyl ether to dissolve them to obtain solution A. Then weigh polyphenylene ether, 4-dimethylaminopyridine, and triethylamine, add ethylene glycol dimethyl ether to dissolve them to obtain solution B. Add solution B dropwise to solution A and react for 1-2 hours. Filter to obtain filtrate. Add the filtrate to anhydrous methanol to precipitate and wash. Filter and dry to obtain a white powder, which is the modified polyphenylene ether resin.

[0047] This invention functionalizes polyphenylene ether through the aforementioned esterification end-capping reaction, introducing end-capping functional groups containing unsaturated carbon-carbon double bonds to obtain modified polyphenylene ether. This significantly improves its heat resistance, water resistance, and weather resistance. Furthermore, the introduced carbon-carbon double bonds enable it to undergo cross-linking reactions, thereby significantly enhancing its compatibility with the coating system. Simultaneously, the blending of modified phenylene ether resin and chlorinated polypropylene resin can significantly improve the adhesion of the coating to the substrate.

[0048] Furthermore, the chlorinated polypropylene resin has acrylate structures grafted onto its molecular chain.

[0049] To meet the coating requirements during application and enhance the adhesion between the coating and the substrate, this invention grafts an acrylate structure onto the molecular chain of chlorinated polypropylene resin using an acrylic polymer. The specific preparation method is as follows:

[0050] (1) Chlorinated polypropylene resin was added to chloroform to prepare a solution with a solid content of 7%, heated to 60°C, initiator AIBN was added, and then hydroxyethyl methacrylate was added to it. After reacting for 16 hours, the reaction was stopped to obtain the grafting reaction solution.

[0051] (2) The grafting reaction solution was slowly added to ethanol at a volume ratio of 1:2 to obtain a flocculent precipitate. The precipitate was filtered and dried to obtain a crude product. The crude product was dissolved in chloroform at a mass ratio of 1:9 to obtain a grafting solution.

[0052] (3) Repeat step (2) multiple times to purify and obtain a semi-finished product. Dissolve the semi-finished product in chloroform at a mass ratio of 1:6, remove the solvent, and dry to obtain chlorinated polypropylene resin grafted with acrylic polymer.

[0053] In this invention, by grafting the acrylate structure onto the molecular chain of chlorinated polypropylene resin using the above preparation method, the polarity of the chlorinated polypropylene resin can be significantly improved, the compatibility between the chlorinated polypropylene resin and other raw material components can be increased, and the adhesion between the coating and the substrate can be effectively improved.

[0054] Furthermore, the preparation method of the high conductivity adhesion promoter coating of the present invention includes the following steps:

[0055] Step S1: Add chlorinated polypropylene resin A and adhesion promoter to the mixing tank and stir for 10-30 minutes;

[0056] Step S2: Take another container, add solvent, and add regulator while stirring. Stir for 10-30 minutes and then let stand for 20-32 hours for later use.

[0057] Step S3: Add anti-settling slurry and conductive primer to the slurry obtained in step S1, and stir for 10-30 minutes;

[0058] Step S4: Add the material obtained in step S2 to the slurry obtained in step S3, and mix and stir for 10-30 minutes to obtain the high conductivity adhesion promoter coating.

[0059] The present invention also includes the application of the aforementioned high conductivity adhesion promoter coating in the manufacture of automobile bumpers.

[0060] The beneficial effects of this invention are as follows: This invention uses conductive primer, chlorinated polypropylene resin, anti-settling agent, regulator, adhesion promoter, and solvent to prepare a high-conductivity adhesion promoter coating. This coating not only adheres tightly to PP substrates but also has good adhesion to color paints and topcoats, while exhibiting high conductivity, good stability, and good rework adhesion. Specifically, the addition of conductive primer significantly reduces the resistance of the coating film, enabling the coating to meet the requirements of electrostatic spraying; the use of chlorinated polypropylene resin and adhesion promoter as the main components results in good compatibility, significantly improving the adhesion between the coating and the substrate and topcoat, and exhibiting good compatibility with color paints and topcoats; the addition of anti-settling agent endows the coating with good anti-settling properties and spraying stability. The coating prepared by the above formula is convenient to apply as a primer for automotive bumpers, has good compatibility, and forms a paint film with high conductivity and long-lasting adhesion. Furthermore, the preparation method of the coating described in this invention is simple, has a short process, is easy to operate, and is suitable for large-scale production. Detailed Implementation

[0061] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0062] All raw materials used in the following embodiments of the present invention are commercially available. The following raw materials are specifically noted: Chlorinated polypropylene resin A, chlorinated polypropylene resin B, and chlorinated polypropylene resin C are all chlorinated polypropylene resins (Zhanxin). XCS1516TS-45); Dispersant B and Dispersant C are both BYK-110 (BYK); Fumed silica B and Fumed silica C are both fumed silica (Degussa AEROSIL R972); The regulator is a monofunctional isocyanate (Bayer).

[0063] Example 1

[0064] A high-conductivity adhesion promoter coating comprises the following raw materials in weight percentages:

[0065] 40% conductive primer

[0066] Chlorinated polypropylene resin A 12.5%

[0067] Anti-sedimentation slurry 14%

[0068] Regulator 0.5%

[0069] 10% polyphenylene ether resin

[0070] Trimethylbenzene 13%

[0071] Xylene 10%.

[0072] In this embodiment, the conductive primer comprises the following raw materials by weight percentage:

[0073] Chlorinated polypropylene resin B 45%

[0074] Dispersant B 3%

[0075] Fumed silica B 0.5%

[0076] 3% conductive carbon black

[0077] Rutile titanium dioxide 15.5%

[0078] 3% trimethylbenzene

[0079] Xylene 30%.

[0080] The preparation method of the conductive primer includes the following steps:

[0081] Step 1: Add chlorinated polypropylene resin B and dispersant B to a mixer and stir for 10 minutes;

[0082] Step 2: Add fumed silica B, conductive carbon black and rutile titanium dioxide and continue stirring for 10 minutes;

[0083] Step 3: Add xylene and trimethylbenzene to the slurry obtained in Step 2 to adjust the viscosity, stir for 10 minutes, and let it soak for 20 hours;

[0084] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the conductive primer.

[0085] In this embodiment, the anti-settling slurry comprises the following raw materials by weight percentage:

[0086] Chlorinated polypropylene resin C 20.5%

[0087] Dispersant C 0.3%

[0088] Fumed silica (C) 6.2%

[0089] Xylene 73%.

[0090] Furthermore, the preparation method of the anti-settling slurry includes the following steps:

[0091] Step 1: Add chlorinated polypropylene resin C and dispersant C to a mixer and stir for 10 minutes;

[0092] Step 2: Add fumed silica C and continue stirring for 10-30 minutes;

[0093] Step 3: Add xylene to the slurry obtained in Step 2 to adjust the viscosity, stir for 10 minutes, and let it soak for 20 hours;

[0094] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the anti-settling slurry.

[0095] In this embodiment, the preparation method of the high conductivity adhesion promoter coating includes the following steps:

[0096] Step S1: Add chlorinated polypropylene resin A and polyphenylene ether resin to the mixing tank and stir for 10 minutes;

[0097] Step S2: In another container, add xylene and trimethylbenzene, and add the regulator while stirring. Stir for 10 minutes and then let it stand for 20 hours for later use.

[0098] Step S3: Add anti-settling slurry and conductive primer to the slurry obtained in step S1, and stir for 10 minutes;

[0099] Step S4: Add the material obtained in step S2 to the slurry obtained in step S3, and mix and stir for 10 minutes to obtain the high conductivity adhesion promoter coating.

[0100] Example 2

[0101] A high-conductivity adhesion promoter coating comprises the following raw materials in weight percentages:

[0102] Conductive primer 45%

[0103] Chlorinated polypropylene resin A 8.5%

[0104] Anti-sedimentation slurry 10%

[0105] Regulator 0.5%

[0106] 10% polyphenylene ether resin

[0107] Trimethylbenzene 14%

[0108] Xylene 12%.

[0109] In this embodiment, the conductive primer comprises the following raw materials by weight percentage:

[0110] Chlorinated polypropylene resin B 50%

[0111] Dispersant B 5%

[0112] Fumed silica B 0.3%

[0113] Conductive carbon black 3.5%

[0114] Rutile titanium dioxide 11.2%

[0115] Trimethylbenzene 4.5%

[0116] Xylene 25%.

[0117] The preparation method of the conductive primer includes the following steps:

[0118] Step 1: Add chlorinated polypropylene resin B and dispersant B to a mixer and stir for 20 minutes;

[0119] Step 2: Add fumed silica B, conductive carbon black and rutile titanium dioxide and continue stirring for 20 minutes;

[0120] Step 3: Add xylene and trimethylbenzene to the slurry obtained in Step 2 to adjust the viscosity, stir for 20 minutes, and let it soak for 24 hours;

[0121] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the conductive primer.

[0122] In this embodiment, the anti-settling slurry comprises the following raw materials by weight percentage:

[0123] Chlorinated polypropylene resin C 40%

[0124] Dispersant C 0.5%

[0125] Fumed silica (C) 10.5%

[0126] Solvent C 49%.

[0127] Furthermore, the preparation method of the anti-settling slurry includes the following steps:

[0128] Step 1: Add chlorinated polypropylene resin C and dispersant C to a mixer and stir for 20 minutes;

[0129] Step 2: Add fumed silica C and continue stirring for 20 minutes;

[0130] Step 3: Add solvent C to the slurry obtained in Step 2 to adjust the viscosity, stir for 20 minutes, and let it soak for 24 hours;

[0131] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the anti-settling slurry.

[0132] In this embodiment, the preparation method of the high conductivity adhesion promoter coating includes the following steps:

[0133] Step S1: Add chlorinated polypropylene resin A and polyphenylene ether resin to the mixing tank and stir for 20 minutes;

[0134] Step S2: Take another container, add solvent, and add regulator while stirring. Stir for 20 minutes and then let stand for 24 hours for later use.

[0135] Step S3: Add anti-settling slurry and conductive primer to the slurry obtained in step S1, and stir for 20 minutes;

[0136] Step S4: Add the material obtained in step S2 to the slurry obtained in step S3, and mix and stir for 20 minutes to obtain the high conductivity adhesion promoter coating.

[0137] Example 3

[0138] A high-conductivity adhesion promoter coating comprises the following raw materials in weight percentages:

[0139] Conductive primer 43.5%

[0140] Chlorinated polypropylene resin A 10.4%

[0141] Anti-sedimentation slurry 13%

[0142] Regulator 0.4%

[0143] Polyphenylene ether resin 8.6%

[0144] Trimethylbenzene 12.2%

[0145] Xylene 11.9%.

[0146] In this embodiment, the conductive primer comprises the following raw materials by weight percentage:

[0147] Chlorinated polypropylene resin B 40%

[0148] Dispersant B 3.2%

[0149] Fumed silica B 0.3%

[0150] 2% conductive carbon black

[0151] Rutile titanium dioxide 18.5%

[0152] 3% trimethylbenzene

[0153] Xylene 33%.

[0154] The preparation method of the conductive primer includes the following steps:

[0155] Step 1: Add chlorinated polypropylene resin B and dispersant B to a mixer and stir for 30 minutes;

[0156] Step 2: Add fumed silica B, conductive carbon black and rutile titanium dioxide and continue stirring for 30 minutes;

[0157] Step 3: Add xylene and trimethylbenzene to the slurry obtained in Step 2 to adjust the viscosity, stir for 30 minutes, and let it soak for 32 hours;

[0158] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the conductive primer.

[0159] In this embodiment, the anti-settling slurry comprises the following raw materials by weight percentage:

[0160] Chlorinated polypropylene resin C 30%

[0161] Dispersant C 0.5%

[0162] Fumed silica C 9%

[0163] Xylene 60.5%.

[0164] Furthermore, the preparation method of the anti-settling slurry includes the following steps:

[0165] Step 1: Add chlorinated polypropylene resin C and dispersant C to a mixer and stir for 30 minutes;

[0166] Step 2: Add fumed silica C and continue stirring for 30 minutes;

[0167] Step 3: Add xylene to the slurry obtained in Step 2 to adjust the viscosity, stir for 30 minutes, and let it soak for 32 hours;

[0168] Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the anti-settling slurry.

[0169] In this embodiment, the preparation method of the high conductivity adhesion promoter coating includes the following steps:

[0170] Step S1: Add chlorinated polypropylene resin A and polyphenylene ether resin to a mixing tank and stir for 30 minutes;

[0171] Step S2: Take another container, add solvent, and add regulator while stirring. Stir for 30 minutes and then let stand for 32 hours for later use.

[0172] Step S3: Add anti-settling slurry and conductive primer to the slurry obtained in step S1, and stir for 30 minutes;

[0173] Step S4: Add the material obtained in step S2 to the slurry obtained in step S3, and mix and stir for 30 minutes to obtain the high conductivity adhesion promoter coating.

[0174] Example 4

[0175] The difference between this embodiment and Embodiment 2 is as follows:

[0176] A modified polyphenylene ether resin was used to replace the polyphenylene ether resin in Example 2. The preparation method of the modified polyphenylene ether resin is as follows:

[0177] S1. Weigh 21g of 4-aminobenzoic acid, 16.5g of maleic anhydride, and 500mL of acetic acid and place them in a reactor. Stir and heat under reflux until the reaction system changes from a suspension to a uniform solution. Stop the reaction and cool to room temperature to precipitate a pale yellow solid. After filtration, washing, and drying, extract with chloroform for 24 hours. Remove the solvent by rotary evaporation to obtain a white powder.

[0178] S2. Weigh 5g of the white powder obtained in step S1, add 10mL of thionyl chloride, heat to 80℃ under N2 atmosphere and react for 3h, cool to room temperature to precipitate solid, filter and dry to obtain orange-yellow crystals, and then recrystallize with toluene to obtain light yellow crystals.

[0179] S3. Weigh 2g of the light yellow crystals obtained in step S2, add 30mL of ethylene glycol dimethyl ether to dissolve them to obtain solution A. Then weigh 1g of polyphenylene ether, 0.7g of 4-dimethylaminopyridine, and 1mL of triethylamine, add 50mL of ethylene glycol dimethyl ether to dissolve them to obtain solution B. Add solution B dropwise to solution A and react for 2 hours. Filter to obtain filtrate. Add the filtrate to 500mL of anhydrous methanol to precipitate and wash. Filter and dry to obtain a white powder, which is the modified polyphenylene ether resin.

[0180] Example 5

[0181] The difference between this embodiment and Embodiment 2 is as follows:

[0182] The chlorinated polypropylene resin grafted with acrylic polymer was used instead of the chlorinated polypropylene resin in Example 2. The specific grafting method is as follows:

[0183] (1) Chlorinated polypropylene resin was added to chloroform to prepare a solution with a solid content of 7%, heated to 60°C, initiator AIBN was added, and then hydroxyethyl methacrylate was added to it. After reacting for 16 hours, the reaction was stopped to obtain the grafting reaction solution.

[0184] (2) The grafting reaction solution was slowly added to ethanol at a volume ratio of 1:2 to obtain a flocculent precipitate. The precipitate was filtered and dried to obtain a crude product. The crude product was dissolved in chloroform at a mass ratio of 1:9 to obtain a grafting solution.

[0185] (3) Repeat step (2) multiple times to purify and obtain a semi-finished product. Dissolve the semi-finished product in chloroform at a mass ratio of 1:6, remove the solvent, and dry to obtain chlorinated polypropylene resin grafted with acrylic polymer.

[0186] In step (1), the mass ratio of chlorinated polypropylene resin to hydroxyethyl methacrylate is 16:1, and the mass ratio of chlorinated polypropylene resin to initiator is 10:1.

[0187] Example 6

[0188] The difference between this embodiment and Embodiment 2 is as follows:

[0189] The conductive carbon black in Example 2 was replaced with poly(3,4-ethylenedioxythiophene)-coated conductive carbon black. The specific preparation method is as follows:

[0190] 3,4-Ethylenedioxythiophene was added to an aqueous solution of sodium polystyrene sulfonate and mixed thoroughly. The mixture was then placed in an ice-water bath, and conductive carbon black was added. The mixture was dispersed for 30 minutes, and the pH of the solution mixture was adjusted to 2 by adding 2M dilute hydrochloric acid solution. Then, 0.7g of ammonium persulfate was dissolved in 10mL of water and slowly added dropwise to the reaction mixture. The mixture was reacted in an ice-water bath for 6 hours, and then the reaction was continued at room temperature for 18 hours. The mixture was filtered, centrifuged, and washed to obtain poly(3,4-ethylenedioxythiophene)-coated conductive carbon black.

[0191] In this embodiment, the mass ratio of conductive carbon black to 3,4-ethylenedioxythiophene is 5:2.

[0192] To examine the performance of the coatings prepared in Examples 1-6 as primers for PP plastic coatings, primer, single-component PP color paint, and two-component polyurethane topcoat were sequentially sprayed. A composite coating was prepared using the 3C1B process, and its adhesion, weather resistance, water resistance, and dry film resistivity were tested. Specific testing requirements and standards are shown in Table 1 below, and the test results are shown in Table 2 below.

[0193] Table 1 Test Items and Reference Standards

[0194]

[0195] Table 2 Performance test results of composite coating

[0196]

[0197]

[0198] As shown in Table 2 above, the composite coating obtained by the test has good adhesion to the PP substrate. The composite coatings prepared in Examples 1-6 all exhibit excellent resistance to damp heat, water, and weathering. Simultaneously, their dry film resistance is less than 0.5 MΩ, demonstrating excellent conductivity. When used as a primer for automotive bumper paint films, they meet the requirements of electrostatic spraying processes, facilitating good application and performance compatibility with subsequent topcoat and color paint layers. Compared to Example 2, Example 4 shows that modification of polyphenylene ether effectively improves the water resistance, weathering resistance, and adhesion of the coating. Compared to Example 2, Example 5 shows that grafting acrylic polymers onto chlorinated polypropylene resin enhances the compatibility between the chlorinated polypropylene resin and the raw materials, thereby effectively improving the adhesion between the coating and the substrate. Compared to Example 2, Example 6 shows that coating the surface of conductive carbon black with poly(3,4-ethylenedioxythiophene) gives the conductive primer better stability and film-forming properties, thus endowing the coating with good conductivity.

[0199] The specific embodiments described above are further illustrations of the technical solution and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A coating with a high electrical conductivity adhesion promoter, characterized in that: The raw materials include the following weight percentages: Conductive primer 40-45%; Chlorinated polypropylene resin A 8-12%; Anti-settling slurry 10-15%; Regulator 0.2-0.5%; Adhesion promoter 6-10%; Solvent A 20-30%; The conductive primer comprises the following raw materials in weight percentage: chlorinated polypropylene resin B 20-50%; Dispersant B 1-6%; Fumed silica B 0.2-0.6%; Conductive carbon black 1-4%; Titanium dioxide 10-30%; Solvent B 20-56%; The conductive carbon black is poly(3,4-ethylenedioxythiophene)-coated conductive carbon black, prepared as follows: 3,4-ethylenedioxythiophene is added to an aqueous solution of sodium polystyrene sulfonate and mixed evenly. The mixture is then placed in an ice-water bath. Conductive carbon black is added and dispersed evenly. The pH of the solution mixture is adjusted to 2 by adding dilute hydrochloric acid solution. Ammonium persulfate is then dissolved in water and slowly added dropwise to the reaction mixture. The mixture is reacted in an ice-water bath for 6 hours, then transferred to room temperature and reacted for another 18 hours. After filtration, centrifugation, and washing, poly(3,4-ethylenedioxythiophene)-coated conductive carbon black is obtained. The mass ratio of conductive carbon black to 3,4-ethylenedioxythiophene is 5:

2. The adhesion promoter is a modified polyphenylene ether resin, and the preparation method of the modified polyphenylene ether resin is as follows: S1. Weigh 4-aminobenzoic acid, maleic anhydride, and acetic acid and place them in a reactor. Stir and heat under reflux until the reaction system changes from a suspension to a uniform solution. Stop the reaction and cool to room temperature to precipitate a pale yellow solid. Filter, wash, and dry the solid, then extract with chloroform for 24 hours. Remove the solvent by rotary evaporation to obtain a white powder. S2. Weigh the white powder obtained in step S1, add thionyl chloride, heat to 80°C under N2 atmosphere and react for 3-4 hours, cool to room temperature to precipitate solid, filter and dry to obtain orange-yellow crystals, and then recrystallize with toluene to obtain light yellow crystals. S3. Weigh the light yellow crystals obtained in step S2, add ethylene glycol dimethyl ether to dissolve them to obtain solution A. Then weigh polyphenylene ether, 4-dimethylaminopyridine, and triethylamine, add ethylene glycol dimethyl ether to dissolve them to obtain solution B. Add solution B dropwise to solution A and react for 1-2 hours. Filter to obtain filtrate. Add the filtrate to anhydrous methanol to precipitate and wash. Filter and dry to obtain a white powder, which is the modified polyphenylene ether resin. The chlorinated polypropylene resin has acrylate structures grafted onto its molecular chain, and the preparation method includes the following: (1) Chlorinated polypropylene resin was added to chloroform to prepare a solution with a solid content of 7%, and then heated to... At 60℃, initiator AIBN was added, followed by the addition of hydroxyethyl methacrylate. The reaction was stopped after 16 hours to obtain the grafting reaction solution. (2) The grafting reaction solution was slowly added to ethanol at a volume ratio of 1:2 to obtain a flocculent precipitate. The precipitate was filtered and dried to obtain a crude product. The crude product was dissolved in chloroform at a mass ratio of 1:9 to obtain a grafting solution. (3) Repeat step (2) multiple times to purify and obtain a semi-finished product. Dissolve the semi-finished product in chloroform at a mass ratio of 1:6, remove the solvent, and dry to obtain chlorinated polypropylene resin grafted with acrylic polymer. In step (1), the mass ratio of chlorinated polypropylene resin to hydroxyethyl methacrylate is 16:1, and the mass ratio of chlorinated polypropylene resin to initiator is 10:

1. Both the chlorinated polypropylene resin A and the chlorinated polypropylene resin B are chlorinated polypropylene resins prepared by the above preparation method.

2. The high conductivity adhesion promoter coating according to claim 1, characterized in that: The preparation method of the conductive primer includes the following steps: Step 1: Add chlorinated polypropylene resin B and dispersant B to a mixer and stir for 10-30 minutes; Step 2: Add fumed silica B, conductive carbon black, and titanium dioxide and continue stirring for 10-30 minutes; Step 3: Add solvent B to the slurry obtained in Step 2 to adjust the viscosity, stir for 10-30 minutes, and let it stand. Soak for 20-32 hours; Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the conductive primer.

3. The high conductivity adhesion promoter coating according to claim 1, characterized in that: The anti-settling slurry comprises the following raw materials by weight percentage: Chlorinated polypropylene resin C 20-40% Dispersant C 0.2-0.6% Fumed silica C 5-11% Solvent C 50-75%.

4. The high conductivity adhesion promoter coating according to claim 3, characterized in that: The anti-sinking The preparation method of the pulp includes the following steps: Step 1: Add chlorinated polypropylene resin C and dispersant C to a mixer and stir for 10-30 minutes; Step 2: Add fumed silica C and continue stirring for 10-30 minutes; Step 3: Add solvent C to the slurry obtained in Step 2 to adjust the viscosity, stir for 10-30 minutes, and let it soak for 20-32 hours; Step 4: Grind the slurry obtained in Step 3 to a fineness of ≤15μm, and finally filter it with a 200-mesh filter to obtain the anti-settling slurry.

5. The high conductivity adhesion promoter coating according to claim 1, characterized in that: Solvent A, solvent B, and solvent C are each selected from one or more combinations of toluene, xylene, and trimethylbenzene.

6. The method for preparing the high conductivity adhesion promoter coating according to any one of claims 1-5, characterized in that: Includes the following steps: Step S1: Add chlorinated polypropylene resin A and adhesion promoter to a mixing tank and stir for 10-30 minutes; Step S2: In a separate tank, add solvent and regulator while stirring, stir for 10-30 minutes, and then let stand for 20-32 hours. spare; Step S3: Add anti-settling slurry and conductive primer to the slurry obtained in Step 1, and stir for 10-30 minutes; Step S4: Add the material obtained in Step S2 to the slurry obtained in Step S3, and mix and stir for 10-30 minutes. The high conductivity adhesion promoter coating is thus obtained.

7. The use of the high conductivity adhesion promoter coating according to any one of claims 1-5 in the manufacture of automobile bumpers.

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