阅读说明：本技术 一种耐腐石墨烯电泳漆及其制备方法 (Corrosion-resistant graphene electrophoretic paint and preparation method thereof ) 是由 王冬 蔡铜祥 韦士富 孙亮 张勇 于 2021-08-25 设计创作，主要内容包括：本发明公开了一种耐腐石墨烯电泳漆及其制备方法,属于电泳漆技术领域。所述耐腐石墨烯电泳漆包括由环氧树脂与氧化石墨烯、表面处理的碳纳米管、表面处理的碳化硅反应生成的改性环氧树脂；所述表面处理的碳纳米管是经环氧树脂包覆处理的碳纳米管,所述表面处理的碳化硅是经环氧树脂包覆处理的碳化硅。本发明的石墨烯电泳漆涂层具有较好的防腐性。(The invention discloses corrosion-resistant graphene electrophoretic paint and a preparation method thereof, and belongs to the technical field of electrophoretic paint. The corrosion-resistant graphene electrophoretic paint comprises modified epoxy resin generated by the reaction of epoxy resin, graphene oxide, a surface-treated carbon nanotube and surface-treated silicon carbide; the surface-treated carbon nanotube is a carbon nanotube coated with epoxy resin, and the surface-treated silicon carbide is silicon carbide coated with epoxy resin. The graphene electrophoretic paint coating disclosed by the invention has better corrosion resistance.)

1. The corrosion-resistant graphene electrophoretic paint is characterized by comprising modified epoxy resin generated by the reaction of epoxy resin, graphene oxide, surface-treated carbon nanotubes and surface-treated silicon carbide;

the surface-treated carbon nanotube is a carbon nanotube coated with epoxy resin, and the surface-treated silicon carbide is silicon carbide coated with epoxy resin.

2. The corrosion-resistant graphene electrophoretic paint according to claim 1, wherein the epoxy resin has an epoxy equivalent of 500 or less;

preferably, the modified epoxy resin has an epoxy equivalent of 4500 to 5500.

3. A method for preparing the corrosion-resistant graphene electrophoretic paint according to claim 1, comprising a preparation step of a modified epoxy resin, the preparation step comprising:

(1) preparing a graphene oxide dispersion liquid;

(2) preparing carbon nano tubes coated by epoxy resin and silicon carbide coated by epoxy resin;

(3) and (2) in the presence of a chain extender, mixing epoxy resin with the graphene oxide dispersion liquid obtained in the step (1), the carbon nano tube coated by the epoxy resin obtained in the step (2) and silicon carbide coated by the epoxy resin, and heating to obtain the modified epoxy resin.

4. The preparation method according to claim 3, wherein in the step (1), the graphene oxide dispersion liquid is prepared by: the raw materials are counted by mass;

adding 60-100 parts of graphene oxide powder into 1000 parts of deionized water, and stirring at the rotating speed of 250-600rpm for 1-4h to prepare the graphene oxide dispersion liquid.

5. The method according to claim 3, wherein in the step (2), the method for preparing the epoxy resin coated carbon nanotubes and the silicon carbide comprises: the dosage of each raw material is calculated by mass portion;

mixing 1000 parts of absolute ethyl alcohol and 400 parts of epoxy resin and 600 parts of epoxy resin, and mechanically stirring and uniformly dispersing to prepare epoxy resin dispersion liquid;

mixing 20-40 parts of carbon nano tube, 10 parts of silicon carbide, 1-5 parts of sodium dodecyl benzene sulfonate and 1-5 parts of initiator AIBN, then adding the epoxy resin dispersion liquid prepared in the step I, and mechanically stirring and dispersing for 0.5-2 hours;

thirdly, heating to 70-100 ℃, reacting for 3-5h by mechanical stirring, after the reaction is finished, centrifugally separating, and repeatedly cleaning with water and ethanol to obtain the carbon nano tube coated by the epoxy resin and the silicon carbide coated by the epoxy resin.

6. The process according to claim 5, wherein in step (2), the epoxy resin has an epoxy equivalent of 500 or less.

7. The method as claimed in claim 5, wherein the rotation speed of the mechanical stirring is 250-600 rpm.

8. The preparation method according to claim 3, wherein in the step (3), the specific method is as follows: the dosage of each raw material is calculated by mass portion;

firstly, mixing 120-180 parts of epoxy resin and 1000 parts of solvent, and mechanically stirring and fully mixing for 2-4 hours;

adding 2-5 parts of chain extender and 2-5 parts of triphenylphosphine, and keeping the temperature at 30-60 ℃ for 1-4 h;

and thirdly, heating to 120-160 ℃, adding the epoxy resin coated carbon nano tube prepared in the step (2) and the epoxy resin coated silicon carbide and the graphene oxide dispersion liquid prepared in the step (1), and carrying out chain extension reaction to obtain the modified epoxy resin dispersion liquid.

9. The process according to claim 8, wherein in step (3), the solvent is water; the epoxy equivalent of the epoxy resin is less than or equal to 500.

10. The method according to claim 8, wherein in the step (3), the chain extender is one or more selected from the group consisting of bisphenol A, bismaleimide, 1, 4-butanediol and derivatives thereof.

Technical Field

The invention relates to the technical field of electrophoretic paint, in particular to corrosion-resistant graphene electrophoretic paint and a preparation method thereof.

Background

Graphene is the thinnest anticorrosive material in the world and can be used for protecting metal substrates, and related researches on graphene anticorrosive coatings have been carried out for a while. A large number of research results show that the graphene has properties of an ultra-large radius-thickness ratio, excellent barrier property, good conductivity and the like, has a strong effect of improving the comprehensive performance of the anticorrosive paint, such as enhancing the adhesive force of a coating to a base material, improving the wear resistance and the corrosion resistance of the paint, and has the characteristics of environmental protection, safety, no secondary pollution and the like.

Since the beginning of research on cathode electrophoretic coatings, the cathode electrophoretic coatings have been widely applied to industries such as automobiles, engineering equipment, electronic instruments and the like by virtue of excellent properties of the cathode electrophoretic coatings. With the development of science and technology, some industries with higher precision requirements such as navigation and aviation have higher and higher requirements on the performance of a coating film, such as high corrosion resistance, high strength and the like, and the requirements on the coating process are also stricter and stricter, and the continuous improvement of the performance of the coating film and the optimization of the coating process are research trends of cathode electrophoretic coatings.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a corrosion-resistant graphene electrophoretic paint and a preparation method thereof. The graphene electrophoretic paint coating disclosed by the invention has better corrosion resistance.

The technical scheme of the invention is as follows:

the corrosion-resistant graphene electrophoretic paint comprises modified epoxy resin generated by the reaction of epoxy resin, graphene oxide, surface-treated carbon nanotubes and surface-treated silicon carbide;

the surface-treated carbon nanotube is a carbon nanotube coated with epoxy resin, and the surface-treated silicon carbide is silicon carbide coated with epoxy resin.

Silicon carbide in the present invention refers to nano silicon carbide.

Preferably, the epoxy resin has an epoxy equivalent of 500 or less.

Preferably, the modified epoxy resin has an epoxy equivalent of 4500 to 5500.

The preparation method of the corrosion-resistant graphene electrophoretic paint comprises a preparation step of modified epoxy resin, and the preparation step comprises the following steps:

(1) preparing a graphene oxide dispersion liquid;

preferably, the preparation method of the graphene oxide dispersion liquid comprises the following steps: the raw materials are counted by mass; adding 60-100 parts of graphene oxide powder into 1000 parts of deionized water, and stirring at the rotating speed of 250-600rpm for 1-4h to prepare a dispersion liquid of the graphene oxide;

(2) preparing carbon nano tubes coated by epoxy resin and silicon carbide coated by epoxy resin;

preferably, the preparation method of the graphene oxide dispersion liquid comprises the following steps: the dosage of each raw material is calculated by mass portion;

mixing 1000 parts of absolute ethyl alcohol and 400 parts of epoxy resin and 600 parts of epoxy resin, and mechanically stirring and uniformly dispersing to prepare epoxy resin dispersion liquid; preferably, the epoxy equivalent of the epoxy resin is less than or equal to 500;

mixing 20-40 parts of carbon nano tube, 10 parts of silicon carbide, 1-5 parts of sodium dodecyl benzene sulfonate and 1-5 parts of initiator AIBN, then adding the epoxy resin dispersion liquid prepared in the step I, and mechanically stirring and dispersing for 0.5-2 hours;

thirdly, heating to 70-100 ℃, mechanically stirring for reaction for 3-5h, after the reaction is finished, centrifugally separating, and repeatedly cleaning with water and ethanol to obtain the carbon nano tube coated with the epoxy resin and the silicon carbide coated with the epoxy resin;

preferably, the rotation speed of the mechanical stirring is 250-600 rpm;

(3) preparing modified epoxy resin; in the presence of a chain extender, mixing epoxy resin with the graphene oxide dispersion liquid obtained in the step (1), the carbon nano tube coated by the epoxy resin obtained in the step (2) and silicon carbide coated by the epoxy resin, and heating to obtain the modified epoxy resin;

preferably, the preparation method of the modified epoxy resin comprises the following steps: the dosage of each raw material is calculated by mass portion;

firstly, mixing 120-180 parts of epoxy resin and 1000 parts of solvent, and mechanically stirring and fully mixing for 2-4 hours; the solvent is water; the epoxy equivalent of the epoxy resin is less than or equal to 500;

adding 2-5 parts of chain extender and 2-5 parts of triphenylphosphine, and keeping the temperature at 30-60 ℃ for 1-4 h;

heating to 120-160 ℃, adding the epoxy resin coated carbon nano tube prepared in the step (2) and the epoxy resin coated silicon carbide and the graphene oxide dispersion prepared in the step (1), performing chain extension reaction, and obtaining a modified epoxy resin dispersion after the reaction;

preferably, the chain extender is selected from one or more of bisphenol a, bismaleimide, 1, 4-butanediol, and derivatives thereof.

In some embodiments, the method of preparing the graphene electrophoretic paint is: heating 100 parts of modified epoxy resin dispersion liquid to 60-90 ℃, stirring until the modified epoxy resin is completely dissolved, dropwise adding 3-15 parts of amine modifier at controlled temperature for amination reaction, heating to 90-140 ℃ after the reaction is finished, adding 3-12 parts of enclosed isocyanate curing agent and 8-16 parts of neutralizer for reaction to obtain main emulsion, and mixing the main emulsion and color paste to prepare the graphene electrophoretic paint.

Preferably, the amine-based modifier is any amine in the art that can be used in an electrophoretic paint, including but not limited to monoethanolamine, diethanolamine, N-dimethylethanolamine, polyamide.

Preferably, the neutralizing agent is any neutralizing agent that may be used in electrophoretic paints in the art, including but not limited to lactic acid, glacial acetic acid, formic acid.

The beneficial technical effects of the invention are as follows:

according to the invention, a combined adding mode of graphene oxide, carbon nano tubes and nano silicon carbide is adopted, and the graphene oxide and the carbon nano tubes are subjected to surface reaction with matrix resin in advance to form a composite structure, so that the dispersion uniformity and stability in the electrophoretic paint are improved, and the corrosion resistance is better improved. The graphene is of a lamellar net structure, the carbon nano tube is of a linear structure, the silicon carbide is of a point structure, and the corrosion resistance of the coating can be improved to a certain extent when the SiC material is added into the coating due to the stability of the SiC material.

The invention adopts the surface line point combination consisting of graphene, carbon nano tubes and nano silicon carbide powder, and has the main functions of: (1) a wide surface + line + point barrier network can be formed, and the composite labyrinth structure can slow down the corrosion of the substrate caused by the water and air passing through the coating; (2) the graphene and the carbon nano tube are both materials with excellent conductivity, and can conduct electrons generated by corrosion reaction on the surface of the base material to the surface of the coating to prevent further corrosion reaction.

Graphene oxide is selected in the invention. The graphene oxide has thin (less than or equal to 20) graphene sheets and rich oxygen-containing groups on the surface, and is convenient to perform chemical grafting reaction with epoxy resin. The carbon nano tube and the nano silicon carbide provided by the invention cannot perform chemical grafting reaction with matrix resin due to less surface groups. Even if the dispersant is added, the modification is only the combination of physical force, so that the final electrophoretic paint has poor dispersion effect and poor stability. According to the invention, the surfaces of the carbon nano tube and the silicon carbide can be coated with the micromolecule epoxy resin through treatment, and the carbon nano tube and the silicon carbide participate in the chain extension reaction of the epoxy resin by utilizing the surface grafting group (epoxy group) through surface treatment, so that the dispersion uniformity and stability in the resin are improved, and the corrosion resistance is better improved.

Detailed Description

The present invention will be described in detail with reference to examples.

Example 1

A preparation method of the corrosion-resistant graphene electrophoretic paint comprises the following steps: the raw materials are counted by weight;

1. preparation of graphene oxide Dispersion

Taking 70 parts of graphene oxide powder, adding 1000 parts of deionized water, and stirring at 300rpm for 2 hours to prepare a graphene oxide dispersion liquid;

2. preparation of epoxy resin-coated carbon nanotubes and epoxy resin-coated silicon carbide

2.1. Adding 1000 parts of absolute ethyl alcohol and 500 parts of small molecular epoxy resin (epoxy equivalent weight 200) into a stirring reaction kettle, and uniformly stirring and dispersing at 500rpm to obtain epoxy resin dispersion liquid;

2.2. mixing 25 parts of dried carbon nano tube, 10 parts of silicon carbide, 2 parts of sodium dodecyl benzene sulfonate and 3 parts of AIBN, then adding the prepared epoxy resin dispersion liquid, and stirring and dispersing for 1 hour at 500 rpm;

2.3. and finally, heating to 80 ℃, stirring at 500rpm for reaction for 3 hours, centrifugally separating the coated carbon nano tube and silicon carbide after the reaction is finished, and repeatedly cleaning with water and ethanol to obtain the epoxy resin coated carbon nano tube and epoxy resin coated silicon carbide.

3. Preparation of modified epoxy resin Dispersion

3.1. Adding 125 parts of epoxy resin (epoxy equivalent of 300) and 1000 parts of water into a reaction container, and mechanically stirring and fully mixing for 2 hours to obtain an epoxy resin dispersion liquid;

3.2. adding 3 parts of bisphenol A and 5 parts of triphenylphosphine into the epoxy resin dispersion liquid, and keeping the temperature at 40 ℃ for 2 hours for activating the chain extender;

3.3. slowly raising the temperature of the reaction vessel to 150 ℃, adding the graphene oxide dispersion liquid prepared in the step 1, the epoxy resin-coated carbon nano tube prepared in the step 2 and the epoxy resin-coated silicon carbide by using a micro-injection pump, uniformly mixing, and carrying out chain extension reaction to obtain a dispersion liquid of modified epoxy resin (the epoxy equivalent is 4700) after the reaction is finished;

4. preparation of graphene electrophoretic paint

Adding 100 parts of modified epoxy resin dispersion into a three-neck flask, heating to 65 ℃, stirring until the modified epoxy resin is completely dissolved, dropwise adding 4 parts of diethanolamine at controlled temperature for amination reaction, heating to 100 ℃ after the reaction is finished, continuously adding 4 parts of enclosed isocyanate curing agent and 9 parts of formic acid into the container for reaction to prepare main emulsion, and mixing the main emulsion with color paste and water (the ratio is 6:1:8) to prepare the graphene electrophoretic paint.

Example 2

A preparation method of the corrosion-resistant graphene electrophoretic paint comprises the following steps: the raw materials are counted by weight;

1. preparation of graphene oxide Dispersion

Taking 70 parts of graphene oxide powder, adding 1000 parts of deionized water, and stirring at 600rpm for 1h to prepare a graphene oxide dispersion liquid;

2. preparation of epoxy resin-coated carbon nanotubes and epoxy resin-coated silicon carbide

2.1. Adding 1000 parts of absolute ethyl alcohol and 400 parts of small molecular epoxy resin (epoxy equivalent weight 200) into a stirring reaction kettle, and stirring and dispersing uniformly at 600 rpm;

2.2. mixing 30 parts of dried carbon nano tube, 10 parts of silicon carbide, 4 parts of sodium dodecyl benzene sulfonate and 5 parts of AIBN, then adding the prepared epoxy resin dispersion liquid, and stirring and dispersing for 0.5 hour at 600 rpm;

2.3. and finally, heating to 90 ℃, stirring at 600rpm for reaction for 4 hours, centrifugally separating the coated carbon nano tube and silicon carbide after the reaction is finished, and repeatedly cleaning with water and ethanol to obtain the epoxy resin coated carbon nano tube and epoxy resin coated silicon carbide.

3. Preparation of modified epoxy resin Dispersion

3.1. Adding 130 parts of epoxy resin (epoxy equivalent of 300) and 1000 parts of water into a reaction vessel, and mechanically stirring and fully mixing for 2 hours;

3.2. 3 parts of bisphenol A and 5 parts of triphenylphosphine are added into the solution, and the solution is kept at 40 ℃ for 2 hours.

3.3. Slowly raising the temperature of the reaction vessel to 150 ℃, adding the graphene oxide dispersion liquid prepared in the step 1, the epoxy resin-coated carbon nano tube prepared in the step 2 and the epoxy resin-coated silicon carbide by using a micro-injection pump, uniformly mixing, and carrying out chain extension reaction to obtain a dispersion liquid of modified epoxy resin (the epoxy equivalent is 5000) after the reaction is finished;

4. preparation of graphene electrophoretic paint

Adding 100 parts of modified epoxy resin dispersion into a three-neck flask, heating to 75 ℃, stirring until the modified epoxy resin is completely dissolved, dropwise adding 6 parts of diethanolamine at controlled temperature for amination reaction, heating to 120 ℃ after the reaction is finished, continuously adding 6 parts of enclosed isocyanate curing agent and 12 parts of formic acid into the container for reaction to prepare main emulsion, and mixing the main emulsion with color paste and water (the ratio is 6:1:8) to prepare the graphene electrophoretic paint.

Example 3

A preparation method of the corrosion-resistant graphene electrophoretic paint comprises the following steps: the raw materials are counted by weight;

1. preparation of graphene oxide Dispersion

Taking 100 parts of graphene oxide powder, adding 1000 parts of deionized water, and stirring at 450rpm for 2 hours to prepare a graphene oxide dispersion liquid;

2. preparation of epoxy resin-coated carbon nanotubes and epoxy resin-coated silicon carbide

2.1. Adding 1000 parts of absolute ethyl alcohol and 450 parts of epoxy resin (average molecular weight is 250) into a stirring reaction kettle, and uniformly stirring and dispersing at 450 rpm;

2.2. mixing 28 parts of dried carbon nano tube, 10 parts of silicon carbide, 4 parts of sodium dodecyl benzene sulfonate and 2 parts of AIBN, then adding the prepared epoxy resin dispersion liquid, and stirring and dispersing for 1 hour at 450 rpm;

2.3. and finally, heating to 90 ℃, stirring at 450rpm for 5 hours, centrifugally separating the coated carbon nano tube and silicon carbide after the reaction is finished, and repeatedly cleaning with water and ethanol to obtain the epoxy resin coated carbon nano tube and epoxy resin coated silicon carbide.

3. Preparation of modified epoxy resin Dispersion

3.1. Adding 140 parts of epoxy resin (epoxy equivalent of 300) and 1000 parts of water into a reaction vessel, and mechanically stirring and fully mixing for 2 hours;

3.2. adding 3 parts of bismaleimide and 5 parts of triphenylphosphine into the solution, and keeping the temperature at 40 ℃ for 2 hours;

3.3. slowly raising the temperature of the reaction vessel to 150 ℃, adding the graphene oxide dispersion liquid prepared in the step 1, the epoxy resin-coated carbon nano tube prepared in the step 2 and the epoxy resin-coated silicon carbide by using a micro-injection pump, uniformly mixing, and carrying out chain extension reaction to obtain a dispersion liquid of modified epoxy resin (the epoxy equivalent is 4700) after the reaction is finished;

4. preparation of graphene electrophoretic paint

Adding 100 parts of modified epoxy resin dispersion into a three-neck flask, heating to 90 ℃, stirring until the modified epoxy resin is completely dissolved, dropwise adding 10 parts of diethanolamine at controlled temperature for amination reaction, heating to 110 ℃ after the reaction is finished, continuously adding 9 parts of enclosed isocyanate curing agent and 9 parts of formic acid into the container for reaction to prepare main emulsion, and mixing the main emulsion with color paste and water (the ratio is 6:1:8) to prepare the graphene electrophoretic paint.

Comparative example 1

A preparation method of electrophoretic paint comprises the following steps: the raw materials are counted by weight;

(1) synthesis of macromolecular epoxy resin

Adding 100 parts of epoxy resin (epoxy equivalent of 300) and 1000 parts of water into a reaction container, mechanically stirring and fully mixing for 2 hours, then adding 3 parts of bisphenol A and 5 parts of triphenylphosphine, and keeping the temperature at 40 ℃ for 2 hours; then slowly raising the temperature of the reaction vessel to 150 ℃, and carrying out chain extension reaction to obtain a solution containing epoxy resin (epoxy equivalent 4000).

(2) Preparation of electrophoretic paints

Adding 100 parts of epoxy resin solution prepared in the step (1) into a three-neck flask, heating to 80 ℃, stirring until the epoxy resin is completely dissolved, controlling the temperature, dropwise adding 8 parts of diethanolamine to carry out amination reaction, heating to 110 ℃ after the reaction is finished, continuously adding 5 parts of closed isocyanate curing agent and 10 parts of formic acid into the container to carry out reaction to prepare main emulsion, and then mixing the main emulsion with color paste and water (the ratio is 6:1:8) to prepare the electrophoretic paint.

Comparative example 2

A preparation method of graphene electrophoretic paint comprises the following steps: the raw materials are counted by weight;

(1) preparation of mixed dispersion liquid of graphene oxide, carbon nano tube and silicon carbide

Adding 20 parts of polyvinylpyrrolidone dispersing agent into 1000 parts of deionized water, uniformly stirring, adding 70 parts of graphene oxide powder, 30 parts of dried carbon nano tube and 10 parts of silicon carbide, and mechanically stirring for 2 hours to prepare a dispersion liquid;

(2) preparation of modified epoxy resin electrophoretic paint coating

Adding 100 parts of epoxy resin (epoxy equivalent of 300) and 1000 parts of water into a reaction vessel, and mechanically stirring and fully mixing for 2 hours; and (2) adding 3 parts of bisphenol A and 5 parts of triphenylphosphine, keeping the temperature at 40 ℃ for 2 hours, heating to 150 ℃, adding the dispersion liquid prepared in the step (1) for chain extension reaction, and finally obtaining the dispersion liquid containing the modified epoxy resin (epoxy equivalent of 4000).

(3) Preparation of graphene electrophoretic paint

Adding 100 parts of the dispersion liquid prepared in the step (2) into a three-neck flask, heating to 80 ℃, stirring until epoxy resin is completely dissolved, dropwise adding 8 parts of diethanolamine at controlled temperature for amination reaction, heating to 110 ℃ after the reaction is finished, continuously adding 5 parts of closed isocyanate curing agent and 10 parts of formic acid into the container for reaction to prepare a main emulsion, and then mixing the main emulsion with color paste and water (the ratio is 6:1:8) to prepare the graphene electrophoretic paint.

Test example:

the electrophoretic paints obtained in examples 1-3 and comparative examples 1-2 were subjected to substrate electrophoresis, respectively; the electrophoresis test piece is made of DC06 stainless steel, and the steel piece is degreased and phosphated before the experiment. Connecting the cleaned and dried steel sheet with a power supply cathode, wherein the power supply anode is a tinned steel sheet, the cathode and the anode are vertically and parallelly arranged on two sides of an electrolytic tank, the distance between the cathode and the anode is 150-200 mm, adding the prepared graphene electrophoretic paint, adjusting the electrophoretic voltage to be 100V, timing for 2min, washing the electrophoresed test piece with deionized water, and then placing the test piece in an oven for curing; the results of the performance tests of the obtained electrophoretic coating are shown in table 1. As can be seen from the data in Table 1, the electrodeposition paint of the present invention has better corrosion resistance than the comparative examples.

TABLE 1

Examples	Coating thickness/. mu.m	Adhesion/grade	Hardness of	Decay-resistant time/h
					Example 1	25	0	HB	1600
Example 2	25	0	HB	1800
					Example 3	25	0	HB	1750
Comparative example 1	25	0	HB	480
					Comparative example 2	25	2	B	600
Standard of merit	GB/T13452.2-2008	GB/T9286-1988	GB/T6739	GB/T10125-2012