An antistatic coating containing single-walled carbon nanotubes and a preparation method thereof

Abstract

The present invention relates to the technical field of antistatic coatings, and specifically relates to an antistatic coating containing single-walled carbon nanotubes and a preparation method thereof. Specifically, it includes the following steps: Step 1: The single-walled carbon nanotubes are sequentially subjected to acidification treatment and acyl chloride treatment to obtain acyl chloride carbon nanotubes; Step 2: (1) 1-allylbenzotriazole, N-tert-butylallyl-1-amine and allyl polyethylene glycol ether are used to initiate polymerization to obtain product A; (2) Product A undergoes a substitution reaction with bromomethyl ether to obtain product B; (3) Product B undergoes a click reaction with 4,6-dihydroxy-2-mercaptopyrimidine to obtain a modifier; Step 3: The acyl chloride carbon nanotubes are modified with the modifier to obtain modified carbon nanotubes; Step 4: Waterborne polyurethane, modified carbon nanotubes, a curing agent, a film-forming aid, a tackifier, an antifoaming agent, a leveling agent and deionized water are mixed evenly to obtain an antistatic coating.

Description

Technical Field

[0001] The present invention relates to the technical field of antistatic coatings, and specifically to an antistatic coating containing single-walled carbon nanotubes and a preparation method thereof. Background Art

[0002] Waterborne polyurethane has properties such as abrasion resistance, oil resistance, corrosion resistance, compatibility, and easy modification, and is widely used in fields such as medical devices and aerospace. However, since resin materials usually have electrical insulation and extremely high resistivity, polyurethane materials are extremely likely to cause electrostatic discharge (ESD), damaging the contacted electronic devices, thus causing electrostatic discharge hazards and even the risk of fire and explosion, which undoubtedly severely limits its application in related fields.

[0003] Carbon nanotubes (CNT), especially single-walled carbon nanotubes (SW-CNT), due to their special structure and excellent mechanical, optical, and electrical properties, many researchers use them as conductive materials to prepare antistatic coatings in antistatic applications. However, single-walled carbon nanotubes have fewer active groups, so the interaction with the polymer materials in the resin solution is extremely weak, and agglomeration usually occurs in the resin solution. In order to obtain excellent antistatic performance, it is necessary to uniformly disperse the carbon nanotubes into the resin solution.

[0004] In summary, the present invention will modify the single-walled carbon nanotubes to improve their dispersibility in polyurethane, and then achieve the modification and enhancement of the polyurethane solution, obtaining a coating with excellent antistatic performance, which can expand the application range of polyurethane coatings and has obvious practical significance. Summary of the Invention

[0005] The purpose of the present invention is to provide an antistatic coating containing single-walled carbon nanotubes and a preparation method thereof to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An antistatic coating containing single-walled carbon nanotubes, comprising the following components: by weight, 40 - 50 parts of waterborne polyurethane, 1 - 6 parts of modified carbon nanotubes, 2 - 5 parts of curing agent, 1 - 3 parts of film-forming aid, 0.1 - 0.5 part of tackifier, 0.1 - 0.5 part of defoamer, 0.1 - 1 part of leveling agent, and 10 - 20 parts of deionized water.

[0008] Further, the preparation method of the antistatic coating comprises the following steps:

[0009] Step 1: The single-walled carbon nanotubes are successively subjected to acidification treatment and acyl chlorination treatment to obtain acyl chlorinated carbon nanotubes;

[0010] Step 2: (1) 1-allylbenzotriazole, N-tert-butylallyl-1-amine and allyl polyethylene glycol ether initiate polymerization to obtain product A; (2) Product A undergoes a substitution reaction with bromomethyl ether to obtain product B; (3) Product B undergoes a click reaction with 4,6-dihydroxy-2-mercaptopyrimidine to obtain a modifier.

[0011] Step 3: The acyl chloride carbon nanotubes are modified with the modifier to obtain modified carbon nanotubes.

[0012] Step 4: Waterborne polyurethane, modified carbon nanotubes, curing agent, film-forming aid, tackifier, defoamer, leveling agent and deionized water are mixed evenly to obtain an antistatic coating.

[0013] Further, the preparation method of the acyl chloride carbon nanotubes is as follows: (1) Single-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid are added to a reaction vessel, stirred and mixed evenly, then heated to 50-100 °C. After soaking for 1-12 h, it is filtered, washed with deionized water until neutral, and dried to obtain acidified carbon nanotubes; (2) The acidified carbon nanotubes and thionyl chloride are added to a reaction vessel, stirred and mixed evenly at room temperature, then heated to 50-70 °C, and stirred continuously for 1-24 h. Stirring is stopped, and finally the excess thionyl chloride is removed by rotary evaporation to obtain acyl chloride carbon nanotubes.

[0014] Further, the ratio of the single-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid is (1-2) g: 30 mL: 10 mL; the concentration of the concentrated sulfuric acid is ≥96%, and the concentration of the concentrated nitric acid is ≥68%.

[0015] Further, the ratio of the acidified carbon nanotubes and thionyl chloride is (1-5) g: 100 mL.

[0016] Further, the preparation method of the modifier is as follows: (1) Add 1-allylbenzotriazole, N-tert-butylallyl-1-amine, allyl polyethylene glycol ether and deionized water into a reaction vessel, introduce nitrogen, and stir and mix for 1-2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution to 50-80 °C, and then dropwise add an initiator to the reaction solution at a uniform speed within 0.5-2 h. After the addition is completed, continue the reaction for 0.5-2 h, end the reaction, and remove deionized water by vacuum distillation to obtain product A; (3) Add product A and bromomethyl ether into absolute ethanol, reflux and react at 70-85 °C for 6-24 h, end the reaction, remove absolute ethanol and excess bromomethyl ether by vacuum distillation, then add an aqueous sodium hydroxide solution to adjust the pH value of the solution to 6.8-7.2, and finally obtain product B through separation and drying; (4) Add product B, 4,6-dihydroxy-2-mercaptopyrimidine, a photoinitiator and absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350-370 nm for 1-20 min, end the reaction, and finally remove absolute ethanol by vacuum distillation to obtain the modifier.

[0017] Further, the mass ratio of the 1-allylbenzotriazole, N-tert-butylallyl-1-amine, allyl polyethylene glycol ether and the initiator is (1-2):(1-2):3:(0.15-0.3).

[0018] Further, the mass ratio of product A and bromomethyl ether is 5:2.

[0019] Further, the mass ratio of product B, 4,6-dihydroxy-2-mercaptopyrimidine and the photoinitiator is 5:(1-2):(0.15-0.3).

[0020] Further, the preparation method of the modified carbon nanotubes is as follows: Add acyl chloride carbon nanotubes, the modifier and ethyl acetate into a reaction vessel, reflux and react at 70-90 °C for 24-72 h, and finally obtain the modified carbon nanotubes through filtration, washing and drying.

[0021] Further, the mass ratio of the acyl chloride carbon nanotubes and the modifier is 1:(0.1-0.5).

[0022] Further, the preparation method of the antistatic coating is as follows: (1) Add waterborne polyurethane, modified carbon nanotubes, a film-forming aid, a tackifier, an antifoaming agent, a leveling agent and deionized water into a reaction vessel, and stir and mix for 1-3 h; (2) Add a curing agent to (1), and stir and mix for 0.5-1 h to obtain the antistatic coating.

[0023] Further, the film-forming aid includes but is not limited to any one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and ethylene glycol.

[0024] Further, the tackifier is a cellulose thickener.

[0025] Further, the curing agent is an amine curing agent.

[0026] In the solution, it is designed to enhance the antistatic performance of the waterborne polyurethane coating by introducing single-walled carbon nanotubes. However, single-walled carbon nanotubes usually show agglomeration phenomena in resin solutions. If single-walled carbon nanotubes are directly added to the waterborne polyurethane, the modification of the waterborne polyurethane cannot be effectively achieved. Therefore, in the present invention, the single-walled carbon nanotubes are designed to be modified to enhance their dispersion performance in the waterborne polyurethane, and at the same time, some other important related properties of the waterborne polyurethane coating can be improved as much as possible, thereby improving the anti-aging property, adhesion strength, etc. of the coated coating.

[0027] In the present invention, product A is prepared by polymerizing 1-allylbenzotriazole, N-tert-butylallyl-1-amine, and allyl polyethylene glycol ether. Among them, N-tert-butylallyl-1-amine introduces a secondary amine structure (-NH-) into product A, which can then undergo a substitution reaction with -Br in bromomethyl ether to prepare product B. Finally, 4,6-dihydroxy-2-mercaptopyrimidine is added, and a modifier is prepared through a click reaction. Finally, the treated single-walled carbon nanotubes (acylated carbon nanotubes) are modified with this modifier to obtain modified carbon nanotubes with a quaternary ammonium salt structure. The quaternary ammonium salt structure on the modified carbon nanotubes can further enhance the antistatic property of the waterborne polyurethane coating. In addition, the modified carbon nanotubes also contain a benzotriazole structure, a large number of ether bonds, and hydroxyl groups. The benzotriazole structure can improve the anti-ultraviolet oxidation performance of the waterborne polyurethane coating, enabling the cured waterborne polyurethane coating to maintain stable performance for a long time and improving its service life (the anti-aging performance is enhanced). In addition, the benzotriazole structure also has a dispersion and antistatic effect. The abundant ether bonds can cooperate with the quaternary ammonium salt structure and the benzotriazole structure to further enhance the antistatic property of the waterborne polyurethane coating, and at the same time, can cooperate with the hydroxyl groups and the benzotriazole structure to enhance the dispersion of the modified carbon nanotubes in the waterborne polyurethane, and also make the connection between the modified carbon nanotubes and the waterborne polyurethane closer, playing a certain role in the adhesion firmness of the coating.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. By modifying the single-walled carbon nanotubes, the present invention solves the defects of poor dispersion and easy agglomeration of single-walled carbon nanotubes in the waterborne polyurethane coating, making the coating exhibit excellent antistatic performance.

[0030] 2. Since the benzotriazole structure is introduced onto the single-walled carbon nanotubes, it has an anti-ultraviolet oxidation effect, which improves the anti-ultraviolet oxidation performance of the waterborne polyurethane coating, enhances the anti-aging performance of the coating to a certain extent, and prolongs its service life.

[0031] 3. Since the dispersibility of the single-walled carbon nanotubes is improved and the connection between the modified carbon nanotubes and the waterborne polyurethane is closer, the strength of the finally coated and cured coating and its bonding property with the substrate are also significantly improved. Detailed implementation mode

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0033] It should be noted that there are no special restrictions on the purchasing manufacturers of all raw materials involved in the present invention. Exemplarily, they include: single-walled carbon nanotubes of model SWCNT-005, with a purity of 99.99%, product number: AM-C6-067-1, tube diameter of 5 nm, purchased from Asia-America Nano Technology Co., Ltd.; 1-allylbenzotriazole with a purity of 98%, CAS number: 52298-91-6, bromomethyl ether with a purity of 98%, both purchased from JACS-Zhengzhou Jacks Chemical Products Co., Ltd.; N-tert-butylallyl-1-amine with a purity of 98%, CAS number: 16386-68-3, and the curing agent is ethylenediamine, CAS number: 6780-13-8, both purchased from Shanghai Dingmiao Chemical Technology Co., Ltd.; allyl polyethylene glycol ether with a purity of 95%, product number: 1371135, CAS number: 56641-05-5, purchased from Beijing Tianyi Yongchang Chemical Technology Co., Ltd.; 4,6-dihydroxy-2-mercaptopyrimidine with a purity of 98%, CAS number: 956086-95-6, purchased from Est (Chengdu) Biopharmaceutical Co., Ltd.; waterborne polyurethane of model DB3520, with a solid content of 35±2%, purchased from Wuhan Double Bond Chem Seal Materials Co., Ltd.; photoinitiator of model IHT-PI EMK, with a purity of 99%, and the tackifier is carboxymethyl cellulose, with a purity of 99%, both purchased from Hubei Yongkuo Technology Co., Ltd.; ethylene glycol monomethyl ether with a purity of 99%, purchased from Shanghai Jinjinle Industrial Co., Ltd.; defoamer of model DE-H055, purchased from Yueguan New Materials Co., Ltd.; leveling agent of model PU-202, purchased from Lugong Auxiliaries Co., Ltd.; the following parts are by weight, and each part is 10 g.

[0034] Example 1: A preparation method of an antistatic coating containing single-walled carbon nanotubes:

[0035] Step 1: Preparation of acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue to stir for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0036] Step 2: Preparation of modifier: (1) Add 1.5 parts of 1-allylbenzotriazole, 1.5 parts of N-tert-butylallyl-1-amine, 3 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen, stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 70 °C, and then dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate to deionized water) into the reaction solution at a constant speed within 2 h. After the addition is completed, continue to react for 2 h to end the reaction. Finally, remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 18 h to end the reaction. Remove the absolute ethanol and the excess bromomethyl ether by vacuum distillation, then add a 10 wt% aqueous sodium hydroxide solution to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 1.2 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 10 min to end the reaction. Finally, remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0037] Step 3: Preparation of modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 1.2 parts of modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 80 °C for 48 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0038] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0039] Example 2: A preparation method of an antistatic coating containing single-walled carbon nanotubes:

[0040] Step 1: Preparation of acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue stirring for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0041] Step 2: Preparation of modifier: (1) Add 1 part of 1-allylbenzotriazole, 1 part of N-tert-butylallyl-1-amine, 3 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen, stir and mix for 1 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 50 °C, and then dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate to deionized water) into the reaction solution at a constant speed within 0.5 h. After dropping, continue the reaction for 0.5 h, end the reaction, and finally remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 70 °C for 6 h, end the reaction, remove the absolute ethanol and the excess bromomethyl ether by vacuum distillation, then add a 10 wt% aqueous sodium hydroxide solution to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 0.8 part of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 1 min, end the reaction, and finally remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0042] Step 3: Preparation of modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 0.5 part of modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 70 °C for 24 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0043] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0044] Example 3: Preparation method of an antistatic coating containing single-walled carbon nanotubes:

[0045] Step 1: Preparation of acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue stirring for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0046] Step 2: Preparation of modifier: (1) Add 2 parts of 1-allylbenzotriazole, 2 parts of N-tert-butylallyl-1-amine, 3 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen, stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 70 °C, and then dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate to deionized water) into the reaction solution at a constant speed within 2 h. After dropping, continue the reaction for 2 h to end the reaction. Finally, remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 24 h to end the reaction. Remove the absolute ethanol and excess bromomethyl ether by vacuum distillation, then add a 10 wt% sodium hydroxide aqueous solution to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 1.6 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 20 min to end the reaction. Finally, remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0047] Step 3: Preparation of modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 2.5 parts of modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 80 °C for 72 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0048] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0049] Based on Example 1, a control experiment was conducted, specifically Comparative Examples 1-5, as described below:

[0050] Comparative Example 1: Comparative Example 1 was based on Example 1 and adjusted as follows: The single-walled carbon nanotubes were not treated, and other processes remained unchanged. Specifically:

[0051] A method for preparing an antistatic coating containing single-walled carbon nanotubes:

[0052] Step 1: Preparation of a modifier: (1) Add 1.5 parts of 1-allylbenzotriazole, 1.5 parts of N-tert-butylallyl-1-amine, 3 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen gas, stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution to 70 °C, and then uniformly dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate to deionized water) into the reaction solution within 2 h. After the dropping is completed, continue the reaction for 2 h to end the reaction. Finally, remove the deionized water by vacuum distillation to obtain Product A; (3) Add 4 parts of Product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 18 h to end the reaction. Remove the absolute ethanol and excess bromomethyl ether by vacuum distillation, then add a 10 wt% aqueous sodium hydroxide solution thereto, adjust the pH value of the solution to 7.0, and finally separate and dry to obtain Product B; (4) Add 4 parts of Product B, 1.2 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of a photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 10 min to end the reaction. Finally, remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0053] Step 2: Preparation of modified carbon nanotubes: Add 5 parts of single-walled carbon nanotubes, 1.2 parts of the modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 80 °C for 48 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0054] Step 4: Preparation of the antistatic coating: (1) Add 48 parts of aqueous polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0055] Comparative Example 2: Comparative Example 2 was based on Example 1 and adjusted as follows: 1-allylbenzotriazole was not added during the preparation of the modifier, and other processes remained unchanged. Specifically:

[0056] Preparation method of antistatic coating containing single-walled carbon nanotubes:

[0057] Step 1: Prepare acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue to stir for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0058] Step 2: Prepare a modifier: (1) Add 2 parts of N-tert-butylallyl-1-amine, 4 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, introduce nitrogen, and stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 70 °C, and then dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate to deionized water) into the reaction solution at a constant speed within 2 h. After dropping, continue to react for 2 h to end the reaction, and finally remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 18 h to end the reaction. Remove the absolute ethanol and excess bromomethyl ether by vacuum distillation, then add a 10 wt% aqueous sodium hydroxide solution to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 1.2 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 10 min to end the reaction. Finally, remove the absolute ethanol by vacuum distillation to obtain a modifier;

[0059] Step 3: Prepare modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 1.2 parts of modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 80 °C for 48 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0060] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain an antistatic coating.

[0061] Comparative Example 3: Comparative Example 3 was based on Example 1 and was adjusted as follows: N-tert-butylallyl-1-amine was not added during the preparation of the modifier, and other processes remained unchanged. Specifically:

[0062] A method for preparing an antistatic coating containing single-walled carbon nanotubes:

[0063] Step 1: Prepare acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue to stir for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0064] Step 2: Prepare the modifier: (1) Add 2 parts of 1-allylbenzotriazole, 4 parts of allyl polyethylene glycol ether, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen, stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 70 °C, and then uniformly dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 parts of ammonium persulfate into deionized water) into the reaction solution within 2 h. After the addition is complete, continue the reaction for 2 h to end the reaction, and finally remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 18 h to end the reaction, remove the absolute ethanol and the excess bromomethyl ether by vacuum distillation, then add a 10 wt% sodium hydroxide aqueous solution thereto to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 1.2 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 10 min to end the reaction, and finally remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0065] Step 3: Prepare modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 1.2 parts of the modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux and react at 80 °C for 48 h, and finally filter, wash, and dry to obtain modified carbon nanotubes;

[0066] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of defoamer DE-H055, 0.6 part of leveling agent PU-202, and 15 parts of deionized water into a reaction vessel, and stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0067] Comparative Example 4: Comparative Example 4 is based on Example 1, with the following adjustments: Allyl polyethylene glycol ether is not added during the preparation of the modifier, and other processes remain unchanged. Specifically:

[0068] Preparation method of an antistatic coating containing single-walled carbon nanotubes:

[0069] Step 1: Preparation of acyl chloride carbon nanotubes: (1) Add 10 parts of single-walled carbon nanotubes, 2 L of 98 wt% concentrated sulfuric acid, and 0.667 L of 68 wt% concentrated nitric acid into a reaction vessel, stir and mix evenly, then heat up to 80 °C, soak for 6 h, and finally filter, wash, and dry to obtain acidified carbon nanotubes; (2) Add 8 parts of acidified carbon nanotubes and 2 L of thionyl chloride into a reaction vessel, stir and mix evenly at room temperature, then heat up to 55 °C, continue to stir for 12 h, stop stirring, and finally remove the excess thionyl chloride by rotary evaporation to obtain acyl chloride carbon nanotubes;

[0070] Step 2: Preparation of modifier: (1) Add 3 parts of 1-allylbenzotriazole, 3 parts of N-tert-butylallyl-1-amine, and 10 parts of deionized water into a reaction vessel, and introduce nitrogen, stir and mix for 2 h to obtain a reaction solution; (2) Keep stirring, heat the reaction solution up to 70 °C, and then dropwise add an aqueous solution of 10 wt% ammonium persulfate (prepared by adding 0.22 part of ammonium persulfate to deionized water) into the reaction solution at a constant speed within 2 h. After the addition is completed, continue the reaction for 2 h to end the reaction. Finally, remove the deionized water by vacuum distillation to obtain product A; (3) Add 4 parts of product A and 1.6 parts of bromomethyl ether into 15 parts of absolute ethanol, reflux and react at 80 °C for 18 h to end the reaction. Remove the absolute ethanol and excess bromomethyl ether by vacuum distillation, then add a 10 wt% aqueous sodium hydroxide solution to adjust the pH value of the solution to 7.0, and finally separate and dry to obtain product B; (4) Add 4 parts of product B, 1.2 parts of 4,6-dihydroxy-2-mercaptopyrimidine, 0.2 part of photoinitiator, and 10 parts of absolute ethanol into a reaction vessel, stir and mix evenly, and irradiate under ultraviolet light at 350 nm for 10 min to end the reaction. Finally, remove the absolute ethanol by vacuum distillation to obtain the modifier;

[0071] Step 3: Preparation of modified carbon nanotubes: Add 5 parts of acyl chloride carbon nanotubes, 1.2 parts of modifier, and 20 parts of ethyl acetate into a reaction vessel, reflux at 80 °C for 48 h, and finally obtain modified carbon nanotubes through filtration, washing, and drying;

[0072] Step 4: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of modified carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, and stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0073] Comparative Example 5: Comparative Example 5 is based on Example 1 and is adjusted as follows: directly add single-walled carbon nanotubes to the coating, and keep the others unchanged. Specifically:

[0074] A preparation method of an antistatic coating containing single-walled carbon nanotubes:

[0075] Step 1: Preparation of antistatic coating: (1) Add 48 parts of waterborne polyurethane, 4 parts of single-walled carbon nanotubes, 2 parts of ethylene glycol monomethyl ether, 0.3 part of carboxymethyl cellulose, 0.3 part of DE-H055 defoamer, 0.6 part of PU-202 leveling agent, and 15 parts of deionized water into a reaction vessel, and stir and mix for 3 h; (2) Add 4 parts of ethylenediamine to (1), stir and mix for 1 h to obtain the antistatic coating.

[0076] Performance test: (1) Place the antistatic coatings prepared in Examples 1 to 3 and Comparative Examples 1 to 5 for 7 days and observe their states; (2) Use a TQC VF1502 beaker coater to uniformly coat each antistatic coating onto a PET film, control the wet coating weight at 6 ± 0.2 g / m 2 , and ensure that no shrinkage holes are formed in the coating film. After coating, dry it at 100 °C to obtain an antistatic coating; conduct relevant performance tests on the antistatic coating. The specific test items and methods are as follows:

[0077] ① Antistatic performance: Use a GM3111 surface resistance meter to detect the surface resistance of the antistatic coating, detect 3 times, and take the average value; use the surface resistance to characterize the antistatic performance of the antistatic coating. The lower the surface resistance, the better the antistatic performance;

[0078] ② Adhesion performance: Paste a 20 cm × 20 cm transparent adhesive tape onto the antistatic coating, pull it, and observe whether it falls off;

[0079] ③ Anti-aging performance: The antistatic coating was irradiated with a UVA340 Lamp ultraviolet aging lamp for 72 hours; then, a 20 cm × 20 cm transparent adhesive tape was continued to be pasted onto the antistatic coating, pulled, and observed whether it peeled off; the specific test results are shown in Table 1 below:

[0080] Table 1

[0081]

[0082] Result analysis: From the test results in Table 1, it can be seen that the present invention prepares modified carbon nanotubes by acidifying and acyl chlorinating single-walled carbon nanotubes and then modifying them with a modifier, which significantly improves the antistatic property and dispersibility of the waterborne polyurethane coating; in addition, from the results of the adhesion fastness, the modified carbon nanotubes also have a certain impact on the adhesion performance of the antistatic coating; in particular, the benzotriazole structure on the modified carbon nanotubes has a significant impact on the aging resistance of the antistatic coating.

[0083] In summary, the present invention prepares an antistatic coating containing highly dispersed single-walled carbon nanotubes, which not only exhibits excellent antistatic performance but also has excellent aging resistance, and the coated coating has a longer service life.

[0084] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A preparation method of an antistatic coating containing single-walled carbon nanotubes, characterized in that: It includes the following steps: Step 1: The single-walled carbon nanotubes are successively subjected to acidification treatment and acyl chlorination treatment to obtain acyl chloride carbon nanotubes; Step 2: (1) 1-allylbenzotriazole, N-tert-butylallyl-1-amine and allyl polyglycol ether are used to initiate polymerization to obtain product A; (2) Product A undergoes a substitution reaction with bromomethyl ether to obtain product B; (3) Product B undergoes a click reaction with 4,6-dihydroxy-2-mercaptopyrimidine to obtain a modifier; Step 3: The acyl chloride carbon nanotubes are modified with the modifier to obtain modified carbon nanotubes; Step 4: Waterborne polyurethane, modified carbon nanotubes, curing agent, film-forming aid, tackifier, defoamer, leveling agent and deionized water are mixed evenly to obtain an antistatic coating.

2. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 1, wherein: The preparation method of the acyl chloride carbon nanotubes is as follows: (1) Single-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid are added into a reaction vessel, stirred and mixed evenly, then heated to 50-100 °C, soaked for 1-12 h, and after filtration, washing and drying, acidified carbon nanotubes are obtained; (2) The acidified carbon nanotubes and thionyl chloride are added into a reaction vessel, stirred and mixed evenly at room temperature, then heated to 50-70 °C, and continuously stirred for 1-24 h, the stirring is stopped, and after rotary evaporation, acyl chloride carbon nanotubes are obtained.

3. The preparation method of an antistatic coating containing single-wall carbon nanotubes according to claim 2, wherein: The ratio of the single-walled carbon nanotubes, concentrated sulfuric acid and concentrated nitric acid is (1-2) g: 30 mL: 10 mL; the ratio of the acidified carbon nanotubes and thionyl chloride is (1-5) g: 100 mL.

4. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 1, characterized in that: The preparation method of the modifier is as follows: (1) 1-allylbenzotriazole, N-tert-butylallyl-1-amine, allyl polyglycol ether and deionized water are added into a reaction vessel, nitrogen is introduced, and stirred and mixed for 1-2 h to obtain a reaction solution; (2) Keeping stirring, the reaction solution is heated to 50-80 °C, and then the initiator is uniformly added dropwise to the reaction solution within 0.5-2 h. After the dropping is completed, the reaction continues for 0.5-2 h, the reaction is ended, and after vacuum distillation, product A is obtained; (3) Product A and bromomethyl ether are added into absolute ethanol, refluxed and reacted at 70-85 °C for 6-24 h, the reaction is ended, absolute ethanol and excess bromomethyl ether are removed by vacuum distillation, and then an aqueous sodium hydroxide solution is added thereto to adjust the pH value of the solution to 6.8-7.2, and after separation and drying, product B is obtained; (4) Product B, 4,6-dihydroxy-2-mercaptopyrimidine, photoinitiator and absolute ethanol are added into a reaction vessel, stirred and mixed evenly, and irradiated under ultraviolet light of 350-370 nm for 1-20 min, the reaction is ended, and after vacuum distillation, the modifier is obtained.

5. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 4, characterized in that: The mass ratio of the 1-allylbenzotriazole, N-tert-butylallyl-1-amine, allyl polyglycol ether and initiator is (1-2):(1-2):3:(0.15-0.3); the mass ratio of product A and bromomethyl ether is 5:2; the mass ratio of product B, 4,6-dihydroxy-2-mercaptopyrimidine and photoinitiator is 5:(1-2):(0.15-0.3).

6. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 1, characterized in that: The preparation method of the modified carbon nanotubes is as follows: Add the acyl chloride carbon nanotubes, modifier and ethyl acetate into a reaction vessel, reflux and react at 70-90 °C for 24-72 h, and finally obtain the modified carbon nanotubes through filtration, washing and drying.

7. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 6, characterized in that: The mass ratio of the acyl chloride carbon nanotubes to the modifier is 1:(0.1-0.5).

8. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 1, characterized in that: The preparation method of the antistatic coating is as follows: (1) Add the waterborne polyurethane, modified carbon nanotubes, film-forming aid, tackifier, defoamer, leveling agent and deionized water into a reaction vessel, and stir and mix for 1-3 h; (2) Add the curing agent into (1), and stir and mix for 0.5-1 h to obtain the antistatic coating.

9. The preparation method of an antistatic coating containing single-walled carbon nanotubes according to claim 1, characterized in that: The film-forming aid includes any one of ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether and ethylene glycol; the tackifier is a cellulose thickener; the curing agent is an amine curing agent.

10. The antistatic coating prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The antistatic coating includes the following components: by weight, 40-50 parts of waterborne polyurethane, 1-6 parts of modified carbon nanotubes, 2-5 parts of curing agent, 1-3 parts of film-forming aid, 0.1-0.5 part of tackifier, 0.1-0.5 part of defoamer, 0.1-1 part of leveling agent, and 10-20 parts of deionized water.

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