Modified carbon nanotube, preparation method thereof and electrogenerated viscosity-reducing pressure-sensitive adhesive

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, and discloses a modified carbon nanotube and a preparation method thereof, and an electrically-induced viscosity-reduced pressure-sensitive adhesive, the preparation method of the modified carbon nanotube provided by the invention comprises the following steps: oxidizing a carbon nanotube, and reacting with silazane to prepare the modified carbon nanotube; trimethylsilyl groups are introduced into the carbon nanotubes, so that the compatibility of the carbon nanotubes and the pressure-sensitive adhesive is increased, the carbon nanotubes are not easy to agglomerate and are better dispersed in the pressure-sensitive adhesive, the addition amount of the carbon nanotubes in the pressure-sensitive adhesive is increased, the shear strength and the conductivity of the electrically induced viscosity-reducing pressure-sensitive adhesive are improved, the viscosity of the electrically induced viscosity-reducing pressure-sensitive adhesive is rapidly reduced when the pressure-sensitive adhesive is electrified, and the viscosity of the pressure-sensitive adhesive is reduced. And the effect of fully reducing the viscosity can be achieved within ten minutes by only needing low voltage, so that the viscosity reducer is safe and energy-saving.

Description

Technical Field

[0001] This invention relates to the field of pressure-sensitive adhesive technology, specifically to a modified carbon nanotube and its preparation method, and an electro-tack-reducing pressure-sensitive adhesive. Background Technology

[0002] In the field of portable smart electronics, more and more electronic devices are bonding batteries to the motherboard. While this secures the battery, it makes disassembly during repair and recycling difficult. Adhesive tape with controllable adhesion allows for easy removal from battery packs or vehicle components without damage, making it highly economical for securing electric vehicle battery packs.

[0003] Electro-adhesive tape, consisting of conductive adhesive, substrate, and release film, is a type of tape that easily loses its tack after being energized. Before energization, it exhibits high adhesive and tensile strength. After energization, it can effectively lose its tack due to heat, offering convenience and speed. However, it suffers from poor tensile strength and adhesion, making it prone to cracking or breaking, and increasing adhesive residue. Existing technologies often add inorganic conductive fillers to the adhesive, which imparts excellent conductivity and facilitates easy and quick loss of tack after energization. However, inorganic conductive fillers tend to agglomerate, affecting the adhesive's conductivity and resulting in incomplete peeling. This leads to adhesive residue between the battery and the device body, impacting the quality and efficiency of battery disassembly.

[0004] The prior art discloses an electrolytic adhesive and a double-sided tape. Specifically, the electrolytic adhesive, by weight, includes the following raw material components: 100 parts of adhesive body, 5-30 parts of solid conductive salt, and 5-50 parts of polar proton inert solvent. Although increasing the conductivity of the adhesive and providing ions that can migrate, thereby reducing the resistance to ion migration, can improve the adhesion of the electrolytic adhesive tape before energization and reduce the residue on the adhered object after electrolytic dissolution, the anions and cations in this electrolytic adhesive are prone to precipitation, which can easily lead to poor electrolytic adhesion and low shear strength of the adhesive, thus affecting the utilization and protection of electronic devices.

[0005] Therefore, how to optimize and adjust electro-adhesive pressure-sensitive adhesives to improve electro-adhesion effect and shear strength is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a method for preparing modified carbon nanotubes to solve the problems of poor electrolytic adhesion and shear strength in the prior art.

[0007] In a first aspect, the present invention provides a method for preparing modified carbon nanotubes, comprising the following steps: Modified carbon nanotubes were prepared by oxidizing carbon nanotubes and then reacting them with silazane.

[0008] In one optional embodiment, the mass ratio of the oxidized carbon nanotubes to the silazane is 100:10-30, optionally 100:15-20.

[0009] It should be noted that the oxidation steps of the carbon nanotubes include: mixing the carbon nanotubes and the oxidant, performing an oxidation reaction, filtering, washing with deionized water until neutral, and drying to obtain the final product.

[0010] Furthermore, the oxidant includes at least one of nitric acid, a mixture of nitric acid and sulfuric acid, potassium permanganate, and hydrogen peroxide.

[0011] Furthermore, the oxidation reaction is carried out at a temperature of 50℃-120℃ for a time of 2h-12h.

[0012] In one optional embodiment, the silazane includes at least one of hexamethyldisilazane, hexaethyldisilazane, tetramethyldihydrodisilazane, and tetramethyldivinyldisilazane.

[0013] In one optional embodiment, the carbon nanotubes have a diameter of 10nm-20nm and an aspect ratio >50.

[0014] In one optional embodiment, the reaction temperature is 110℃-160℃, preferably 120℃-130℃, and the reaction time is 2h-8h.

[0015] In one optional embodiment, the method further includes the step of dispersing the oxidized carbon nanotubes in a first organic solvent to prepare a carbon nanotube dispersion.

[0016] In one optional embodiment, the mass ratio of the oxidized carbon nanotubes to the first organic solvent is 10-30:100, optionally 10-20:100.

[0017] In one alternative embodiment, the first organic solvent includes at least one of xylene, toluene, chloroform, cyclohexane, n-hexane, ethyl acetate, and n-heptane.

[0018] In an optional embodiment, the method further includes the step of dissolving the silazane in a second organic solvent to prepare a silazane solution, and then adding it dropwise to the carbon nanotube dispersion.

[0019] Furthermore, the dropping rate of the silazane solution is 1-2 drops / second.

[0020] Furthermore, before mixing the carbon nanotube dispersion and the silazane solution, the carbon nanotube dispersion is ultrasonically dispersed for 1-3 hours under an inert atmosphere.

[0021] In one optional embodiment, the mass ratio of the silazane to the silazane solution is 1-50:100, optionally 10-30:100.

[0022] In one alternative embodiment, the second organic solvent includes at least one selected from toluene, xylene, chloroform, cyclohexane, n-hexane, ethyl acetate, and n-heptane.

[0023] In a second aspect, the present invention provides a modified carbon nanotube, which is prepared by the preparation method described in the first aspect.

[0024] Thirdly, the present invention provides an application of modified carbon nanotubes prepared by the preparation method described in the first aspect or modified carbon nanotubes described in the second aspect in electro-viscosity reducing pressure-sensitive adhesives.

[0025] Fourthly, an electro-tack reducing pressure-sensitive adhesive, wherein the electro-tack reducing pressure-sensitive adhesive comprises modified carbon nanotubes, ionic liquids, and a pressure-sensitive adhesive matrix material; The total number of carbon atoms in the ionic liquid molecule is C8-C32; The cations of the ionic liquid include at least one of phosphine cations, imidazole cations, and quaternary ammonium cations; The modified carbon nanotubes are either the modified carbon nanotubes prepared by the preparation method described in the first aspect or the modified carbon nanotubes described in the second aspect.

[0026] It should be noted that in this invention, the main chain of the ionic liquid molecule has 8-16 carbon atoms.

[0027] It should be noted that the preparation method of the electro-viscosity reducing pressure-sensitive adhesive includes the following steps: (1) Modified carbon nanotubes are added to a third organic solvent and ultrasonically dispersed for 1-3 hours to form a uniform black suspension; then an ionic liquid is added and ultrasonically dispersed for 1-2 hours, and dried to prepare a mixture; the third organic solvent includes at least one of toluene, xylene, cyclohexane, n-heptane, ethyl acetate, acetone, dichloromethane, and chloroform; the mass ratio of the modified carbon nanotubes to the third organic solvent is 10-30:100, and can be selected as 15-20:100; (2) The electro-tack-reducing pressure-sensitive adhesive is prepared by mixing the mixture and the pressure-sensitive adhesive.

[0028] In one optional embodiment, the mass ratio of the modified carbon nanotubes to the ionic liquid is 10:1-50, and optionally 10:1-10.

[0029] In one optional embodiment, the mass ratio of the total mass of the modified carbon nanotubes and the ionic liquid to the mass of the pressure-sensitive adhesive matrix material is 1-30:100, preferably 1-10:100.

[0030] In one alternative embodiment, the ionic liquid comprises at least one of trihexyltetradecylphosphine bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium acetate, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide salt, and 1-hexadecyl-3-methylimidazolium trifluoromethanesulfonate.

[0031] In one optional embodiment, the pressure-sensitive adhesive matrix material includes at least one of silicone pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, and polyurethane pressure-sensitive adhesive.

[0032] It should be noted that the preparation method of the silicone pressure-sensitive adhesive includes the following steps: In the presence of an acid or base catalyst, methyl MQ silicone resin and 107 silicone rubber are subjected to a condensation and dehydration reaction in a fourth organic solvent, followed by neutralization, to prepare an organosilicon pressure-sensitive adhesive.

[0033] Furthermore, the mass ratio of the methyl MQ silicone resin to the 107 silicone rubber is 10:5-8, and can be optionally 10:6-7.

[0034] Furthermore, the hydroxyl content of the methyl MQ silicone resin is 2.0wt%-3.5wt%, preferably 2.8wt%-3.2wt%.

[0035] Furthermore, the molecular weight of the 107 silicone rubber is 600,000 to 1,000,000, preferably 700,000 to 800,000.

[0036] Furthermore, the fourth organic solvent includes at least one of toluene and xylene.

[0037] Fifthly, the present invention provides an application of the electro-adhesive pressure-sensitive adhesive described in the fourth aspect in portable smart electronic appliances.

[0038] The technical solution of this invention has the following advantages: 1. The modified carbon nanotube preparation method provided by the present invention includes the following steps: oxidizing carbon nanotubes and reacting them with silazane to prepare modified carbon nanotubes; the present invention introduces alkylsilane groups into carbon nanotubes to increase their compatibility with pressure-sensitive adhesives, making them less prone to agglomeration in pressure-sensitive adhesives, better dispersed, increasing the amount of carbon nanotubes added to the pressure-sensitive adhesive matrix material, improving the shear strength and conductivity of the electro-tack-reducing pressure-sensitive adhesive, enabling it to rapidly reduce viscosity when energized, requiring only low voltage for less than ten minutes to achieve sufficient viscosity reduction, which is safe and energy-saving.

[0039] 2. The electro-tack reducing pressure-sensitive adhesive provided by the present invention comprises modified carbon nanotubes, ionic liquids, and pressure-sensitive adhesives; the total number of carbon atoms in the ionic liquid molecules is C8-C32; and it contains at least one of phosphine cations, imidazole cations, and ammonium cations, which can prevent the carbon nanotubes from agglomerating after adsorption; after being energized, the carbon nanotubes form a conductive network, and the ionic liquid can oriented the charges, thereby achieving a sufficient viscosity reduction effect. Detailed Implementation

[0040] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0041] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0042] In this invention, unless otherwise specified, all raw materials and reagents used can be obtained through conventional commercial channels. The main raw material information is as follows: Methyl MQ silicone resin: hydroxyl content 3.0 wt%, purchased from Wanhua Chemical Co., Ltd., model SF 6266; 107 silicone rubber: molecular weight 720,000, purchased from Hoshine Silicon Industry Co., Ltd.

[0043] Example 1 This embodiment provides a method for preparing modified carbon nanotubes, including the following steps: (1) Weigh 10g of carbon nanotubes with a diameter of 15nm and an aspect ratio of 80 and add them to 200g of concentrated nitric acid (68wt%). Heat to 120℃ and stir for 6h. After the reaction, cool to room temperature and pour the reaction solution into 500mL of deionized water to dilute. Then adjust the pH to 7 with 5wt% sodium hydroxide solution. Centrifuge to separate and collect the black precipitate. Wash with deionized water until neutral and dry under vacuum at 100℃ and -0.09MPa for 24h to obtain carbon nanotubes. (2) 10g of carbon nanotubes were dispersed in 100g of xylene, and then nitrogen gas was introduced to maintain a slight positive pressure. Ultrasonic oscillation was turned on and the mixture was ultrasonically dispersed for 2h to form a uniform black suspension. The mixture was stirred and heated to 120℃, and 5g of a toluene solution of hexamethyldisilazane (hexamethyldisilazane was 1.5g) was slowly added dropwise at a rate of 1-2 drops / second. After the addition was completed, the mixture was kept at the temperature for 4h. After cooling to room temperature, the reaction solution was transferred to a centrifuge tube, the supernatant was discarded, and the black precipitate at the bottom was collected. The precipitate was washed three times with anhydrous toluene and then transferred to a vacuum drying oven at 80℃ and -0.09MPa for 12h. After drying, the mixture was ground into powder to obtain modified carbon nanotubes.

[0044] Example 2 This embodiment provides a method for preparing modified carbon nanotubes, including the following steps: (1) Weigh 10g of carbon nanotubes with a diameter of 10nm and an aspect ratio of 100 and add 80g of deionized water. Disperse the nanotubes by ultrasonication for 30min to form a suspension. Add 1mol / L dilute sulfuric acid to the suspension and adjust the pH to 2-3. Turn on the stirring and add 20g of potassium permanganate solution (concentration of 10wt%) at a rate of 1-2 drops / s. Heat to 60℃ and stir for 8h. After the reaction, cool to room temperature and slowly add 5wt% oxalic acid solution while stirring until the solution becomes colorless. Quench the excess potassium permanganate completely. Wash with deionized water until neutral. Dry under vacuum at 60℃ and -0.09MPa for 12h. Grind into powder to obtain carbon oxide nanotubes. (2) 15g of carbon nanotubes were dispersed in 100g of cyclohexane. Nitrogen gas was introduced to maintain a slight positive pressure. Ultrasonic oscillation was turned on and the dispersion was ultrasonically carried out for 2 hours to form a uniform black suspension. The suspension was stirred and heated to 125°C. 15g of xylene solution of hexaethyldisilazane (the content of hexaethyldisilazane was 3g) was slowly added dropwise at a rate of 1-2 drops / second. After the addition was completed, the reaction was kept at the temperature for 4 hours. After cooling to room temperature, the reaction solution was transferred to a centrifuge tube, the supernatant was discarded, and the black precipitate at the bottom was collected. The precipitate was washed three times with anhydrous toluene and then transferred to a vacuum drying oven at 80°C and -0.09MPa for 12 hours. After drying, it was ground into powder to obtain modified carbon nanotubes.

[0045] Example 3 This embodiment provides a method for preparing modified carbon nanotubes, including the following steps: (1) Weigh 10g of carbon nanotubes with a diameter of 17nm and an aspect ratio of 60 and add 200g of deionized water. Disperse the nanotubes by ultrasonication for 40min to form a suspension. Add 10ml of 37wt% concentrated hydrochloric acid to the suspension and adjust the pH to 1-2. Turn on the stirring and add 20mL of hydrogen peroxide solution (concentration of 30wt%) at a rate of 1-2 drops / s. Heat to 50℃ and stir the reaction for 10h. After the reaction, cool to room temperature and wash with deionized water until neutral. Transfer to a vacuum drying oven and dry at 60℃ and -0.08MPa for 20h. Grind into powder to obtain carbon nanotubes. (2) 20g of carbon nanotubes were dispersed in 100g of n-hexane. Nitrogen gas was introduced into the medium to maintain a slight positive pressure. Ultrasonic oscillation was turned on and the dispersion was ultrasonically performed for 2 hours to form a uniform black suspension. The suspension was stirred and heated to 130°C. 17.5g of tetramethyldihydrodisilazane in chloroform solution (tetramethyldihydrodisilazane content was 3.5g) was slowly added dropwise at a rate of 1-2 drops / second. After the addition was completed, the reaction was kept at the temperature for 6 hours. After cooling to room temperature, the reaction solution was transferred to a centrifuge tube, the supernatant was discarded, and the black precipitate at the bottom was collected. The precipitate was washed three times with anhydrous toluene and then transferred to a vacuum drying oven at 80°C and -0.09MPa for 12 hours. After drying, the precipitate was ground into powder to obtain modified carbon nanotubes.

[0046] Example 4 This embodiment provides a method for preparing modified carbon nanotubes, including the following steps: (1) Weigh 10g of carbon nanotubes with a diameter of 20nm and an aspect ratio of 120, add them to a mixture of 15mL concentrated nitric acid (68wt%) and 45mL concentrated sulfuric acid (98wt%), sonicate for 30min, heat to 80℃, stir for 12h, cool to room temperature after reaction, slowly pour the reaction solution into 500mL of deionized water to dilute, centrifuge, collect the black precipitate, wash with deionized water until neutral, dry under vacuum at 100℃ and -0.09MPa for 24h to obtain carbon nanotubes; (2) 25g of carbon nanotubes were dispersed in 100g of chloroform. Nitrogen gas was introduced into the medium to maintain a slight positive pressure. Ultrasonic oscillation was turned on and the mixture was ultrasonically dispersed for 1h to form a uniform black suspension. The mixture was stirred and heated to 110℃. 23g of a tetramethyldivinyldisilazane n-hexane solution (tetramethyldivinyldisilazane content was 7g) was slowly added dropwise at a rate of 1-2 drops / second. After the addition was completed, the mixture was kept at the temperature for 8h. After cooling to room temperature, the reaction solution was transferred to a centrifuge tube, the supernatant was discarded, and the black precipitate at the bottom was collected. The precipitate was washed three times with anhydrous toluene and then transferred to a vacuum drying oven at 80℃ and -0.09MPa for 12h. After drying, the precipitate was ground into powder to obtain modified carbon nanotubes.

[0047] Example 5 This embodiment provides a method for preparing modified carbon nanotubes, including the following steps: (1) Weigh 10g of carbon nanotubes with a diameter of 13nm and an aspect ratio of 140 and add them to 50mL of nitric acid (concentration of 30wt%). Heat to 110℃ and stir for 10h. After the reaction, cool to room temperature and pour the reaction solution into 500mL of deionized water to dilute. Then adjust the pH to 7 with 5wt% sodium hydroxide solution. Centrifuge to separate and collect the black precipitate. Wash with deionized water until neutral and dry under vacuum at 100℃ and -0.09MPa for 24h to obtain carbon nanotube oxide. (2) 30g of carbon nanotubes were dispersed in 100g of ethyl acetate. Nitrogen gas was introduced into the medium to maintain a slight positive pressure. Ultrasonic oscillation was turned on and the mixture was ultrasonically dispersed for 3h to form a uniform black suspension. The mixture was stirred and heated to 160℃. 18g of ethyl acetate solution of hexamethyldisilazane (containing 9g of hexamethyldisilazane) was slowly added dropwise at a rate of 1-2 drops / second. After the addition was completed, the mixture was kept at the temperature for 2h. After cooling to room temperature, the reaction solution was transferred to a centrifuge tube. The supernatant was discarded, and the black precipitate at the bottom was collected. The precipitate was washed three times with anhydrous toluene and then transferred to a vacuum drying oven at 80℃ and -0.09MPa for 12h. After drying, the precipitate was ground into powder to obtain modified carbon nanotubes.

[0048] Example 6 This embodiment provides a method for preparing an electro-viscosity-reducing pressure-sensitive adhesive, comprising the following steps: (1) Add 100g of methyl MQ silicone resin and 60g of 107 silicone rubber to a flask, add 200g of toluene, add 2g of p-toluenesulfonic acid, heat to 120℃, keep warm for 4h, then add sodium carbonate to neutralize, stir for 2h, filter, and obtain organosilicon pressure-sensitive adhesive. (2) 15g of the modified carbon nanotubes prepared in Example 1 were added to 100g of xylene and ultrasonically dispersed for 2h to form a uniform black suspension. Then 10g of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt was added and ultrasonically dispersed for 1h. Then the mixture was dried at 90℃ and 0.09MPa for 5h and the solvent was evaporated to obtain the mixture. (3) Add 5g of the mixture to 200g of silicone pressure-sensitive adhesive, stir evenly, filter, and prepare electro-tack-reducing pressure-sensitive adhesive.

[0049] Example 7 This embodiment provides a method for preparing an electro-induced anti-adhesion pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Example 2.

[0050] Example 8 This embodiment provides a method for preparing an electro-induced anti-adhesion pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Example 3.

[0051] Example 9 This embodiment provides a method for preparing an electro-induced anti-tack pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Example 4.

[0052] Example 10 This embodiment provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Example 5.

[0053] Example 11 This embodiment provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the mass of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is 1.5g; and in step (3), the mass of the mixture is 10g.

[0054] Example 12 This embodiment provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that in step (2), the mass of 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is 15g; and in step (3), the mass of the mixture is 20g.

[0055] Example 13 This embodiment provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is replaced with the same mass of 1-octyl-3-methylimidazolium acetate.

[0056] Example 14 This embodiment provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 1, except that 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is replaced with the same mass of trioctylmethylammonium bis(trifluoromethanesulfonyl)imide salt.

[0057] Example 15 This embodiment provides a method for preparing an electro-viscosity-reducing pressure-sensitive adhesive, comprising the following steps: (1) Add 20g of ethyl acetate to a flask, purge with nitrogen, add 0.3g of azobisisobutyronitrile, start stirring, heat to 70°C, and then add a mixed liquid containing 22g of butyl acrylate, 3g of acrylic acid, 5g of methyl methacrylate and 65g of ethyl acetate at a rate of 1-2 drops / second. After the addition is complete, heat to 75°C, keep warm for 5 hours, cool to room temperature, filter, and obtain acrylic pressure-sensitive adhesive. (2) 15g of the modified carbon nanotubes prepared in Example 1 were added to 50g of ethyl acetate and ultrasonically dispersed for 1h to form a uniform black suspension. Then, 30g of trihexyltetradecylphosphine bis(trifluoromethylsulfonyl)imide salt was added and ultrasonically dispersed for 1.5h. Then, the mixture was dried at 90℃ and 0.09MPa for 5h and the solvent was evaporated to obtain the mixture. (3) Add 40g of the mixture to 200g of acrylic pressure-sensitive adhesive, stir evenly, filter, and prepare electro-tack-reducing pressure-sensitive adhesive.

[0058] Example 16 This embodiment provides a method for preparing an electro-viscosity-reducing pressure-sensitive adhesive, comprising the following steps: (1) Add 30g of polyethylene adipate diol (PEA-2000) to a flask, start stirring, evacuate to -0.09MPa, heat to 80℃, dehydrate under vacuum for 2h, cool to 60℃, stop evacuation, introduce nitrogen gas, add 0.02g of dibutyltin dilaurate, stir evenly for 30min, add 8g of methyl diisocyanate dropwise at a rate of 1 drop / second, after the addition is complete, heat to 75℃, keep the reaction at this temperature for 2h, and add 1.2g of... 1,4-Butanediol was dissolved in 10g of a mixed solvent (ethyl acetate and acetone in a volume ratio of 1:1), and then added dropwise to the above reaction solution at 1-2 drops / second. After the addition was complete, the reaction continued for 1 hour. Then, 0.5g of trimethylolpropane was dissolved in 5g of a mixed solvent (ethyl acetate and acetone in a volume ratio of 1:1), and then added dropwise to the above reaction solution at 1-2 drops / second. After the addition was complete, the temperature was raised to 80℃, and the reaction was maintained at this temperature for 1.5 hours. Heating was stopped, nitrogen gas was stopped, and the mixture was cooled to room temperature. The mixture was then filtered to obtain polyurethane pressure-sensitive adhesive. (2) 15g of the modified carbon nanotubes prepared in Example 1 were added to 67g of cyclohexane and ultrasonically dispersed for 3h to form a uniform black suspension. Then 75g of 1-hexadecyl-3-methylimidazolium trifluoromethane sulfonate was added and ultrasonically dispersed for 2h. Then the mixture was dried at 90℃ and 0.09MPa for 5h and the solvent was evaporated to obtain the mixture. (3) Add 60g of the mixture to 200g of polyurethane pressure-sensitive adhesive, stir evenly, filter, and prepare electro-tack-reducing pressure-sensitive adhesive.

[0059] Comparative Example 1 This comparative example provides a method for preparing modified carbon nanotubes, which is basically the same as the steps in Example 1, except that step (1) is replaced by: ultrasonically dispersing 10g of carbon nanotubes with a diameter of 15nm and an aspect ratio of 80 in a mixture of 7000mL ethanol and 1000mL water, and adjusting the pH to 9 with ammonia.

[0060] Comparative Example 2 This comparative example provides a method for preparing modified carbon nanotubes, which is basically the same as the steps in Example 1, except that hexamethyldisilazane is replaced with the same mass of γ-methacryloyloxypropyltrimethoxysilane.

[0061] Comparative Example 3 This comparative example provides a method for preparing an electro-induced anti-tack pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Comparative Example 1.

[0062] Comparative Example 4 This comparative example provides a method for preparing an electro-induced anti-tack pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that the modified carbon nanotubes prepared in Example 1 are replaced with the modified carbon nanotubes prepared in Comparative Example 2.

[0063] Comparative Example 5 This comparative example provides a method for preparing an electro-tack-reducing pressure-sensitive adhesive, which is basically the same as the steps in Example 6, except that 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt is replaced with the same mass of 1-ethyl-3-methylimidazolium hydrogen sulfate.

[0064] Experimental Example The electro-adhesive pressure-sensitive adhesives prepared in Examples 6-16 and Comparative Examples 3-5 were used to prepare PI films, which were then subjected to peel strength testing. Shear strength testing was performed according to GB / T 7124-2022. The peel strength test included the following steps: 100g of the electro-tack-reducing pressure-sensitive adhesive prepared in Examples 6-16 and Comparative Examples 3-5, 80g of xylene, and 2g of benzoyl peroxide were mixed evenly and then coated onto a polyimide (PI) film using a coater. The film was then cured in an oven at 160°C for 2 minutes to obtain a PI film with a dry adhesive weight of 25g / m³. 2 Cut the PI film into 150×25mm pieces and stick it on a steel plate (roll it back and forth twice with a 2kg pressure roller). Let it sit for 20 minutes, and then use a force sensor type peel force tester to conduct a 180° peel test. The tensile speed is 30m / min and the tensile distance is 100mm. This is recorded as the first peel force.

[0065] The PI film was adhered to the steel plate and pressed back and forth three times with a 2kg rubber roller. After 20 minutes, the steel plate was powered on with 9V for 1 minute. Then, the peel force at 180° was tested using a force sensor-type peel force tester. The tensile speed was 30m / min and the tensile distance was 100mm. This was recorded as the second peel force.

[0066] Table 1. Peel strength test results of the anti-adhesion tapes prepared in each embodiment and comparative example.

[0067] Table 1 shows that the anti-adhesion tapes prepared in Examples 6-16 were effective. Comparative Example 3 did not undergo an oxidation step; instead, carbon nanotubes were directly dispersed in a mixed solution of ethanol and water, and the pH was adjusted, resulting in slightly lower shear strength but still relatively high adhesion after energization, with a small amount of residue after peeling. Comparative Example 4 replaced hexamethyldisilazane with the same mass of γ-methacryloxypropyltrimethoxysilane. The reaction between γ-methacryloxypropyltrimethoxysilane and carbon nanotubes was less pronounced, and some of the siloxy groups in γ-methacryloxypropyltrimethoxysilane would partially react with water. The solution is hydroxyl, which leads to poor compatibility with the pressure-sensitive adhesive system. The adhesion is still high after energization, and a small amount of adhesive residue remains after peeling. In addition, when the amount added is large, the adhesive surface will become hazy, and the additive will precipitate during the storage of the adhesive, making it unusable. In Comparative Example 5, trihexyltetradecylphosphine bis(trifluoromethanesulfonyl)imide salt was replaced with the same mass of 1-ethyl-3-methylimidazolium hydrogen sulfate. 1-ethyl-3-methylimidazolium hydrogen sulfate has a poor dispersion effect on carbon nanotubes. After being added to the pressure-sensitive adhesive, the shear strength is slightly lower, the adhesion is still high after energization, and a small amount of adhesive residue remains after peeling.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing modified carbon nanotubes, characterized in that, Includes the following steps: Modified carbon nanotubes were prepared by oxidizing carbon nanotubes and then reacting them with silazane.

2. The method for preparing modified carbon nanotubes according to claim 1, characterized in that, The mass ratio of the oxidized carbon nanotubes to the silazane is 100:10-30, and can be selected as 100:15-20.

3. The method for preparing modified carbon nanotubes according to claim 1 or 2, characterized in that, The silazane includes at least one of hexamethyldisilazane, hexaethyldisilazane, tetramethyldihydrodisilazane, and tetramethyldivinyldisilazane; And / or, the carbon nanotubes have a diameter of 10nm-20nm and an aspect ratio >50.

4. The method for preparing modified carbon nanotubes according to claim 1, characterized in that, The reaction temperature is 110℃-160℃, preferably 120℃-130℃, and the reaction time is 2h-8h.

5. The method for preparing modified carbon nanotubes according to claim 1, characterized in that, It also includes the step of dispersing oxidized carbon nanotubes in a first organic solvent to prepare a carbon nanotube dispersion; Optionally, the mass ratio of the oxidized carbon nanotubes to the first organic solvent is 10-30:100, and optionally 10-20:100; Optionally, the first organic solvent includes at least one selected from xylene, toluene, chloroform, cyclohexane, n-hexane, ethyl acetate, and n-heptane. It also includes the step of dissolving the silazane in a second organic solvent to prepare a silazane solution, and then adding it dropwise to the carbon nanotube dispersion; Optionally, the mass ratio of the silazane to the silazane solution is 1-50:100, and optionally 10-30:100; Optionally, the second organic solvent includes at least one of toluene, xylene, chloroform, cyclohexane, n-hexane, ethyl acetate, and n-heptane.

6. A modified carbon nanotube, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the modified carbon nanotubes prepared by the preparation method according to any one of claims 1-5 or the modified carbon nanotubes according to claim 6 in electro-viscosity reducing pressure-sensitive adhesives.

8. An electro-tack-reducing pressure-sensitive adhesive, characterized in that, The electro-tack-reducing pressure-sensitive adhesive comprises modified carbon nanotubes, ionic liquids, and a pressure-sensitive adhesive matrix material; The total number of carbon atoms in the ionic liquid molecule is C8-C32; The cations of the ionic liquid include at least one of phosphine cations, imidazole cations, and quaternary ammonium cations; The modified carbon nanotube is the modified carbon nanotube prepared by the preparation method according to any one of claims 1-5 or the modified carbon nanotube according to claim 6.

9. The electro-tack reducing pressure-sensitive adhesive according to claim 8, characterized in that, The mass ratio of the modified carbon nanotubes to the ionic liquid is 10:1-50, and can be selected as 10:1-10; And / or, the mass ratio of the total mass of the modified carbon nanotubes and the ionic liquid to the mass of the pressure-sensitive adhesive matrix material is 1-30:100, preferably 1-10:100; And / or, the ionic liquid comprises at least one of the following: trihexyltetradecylphosphine bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, 1-octyl-3-methylimidazolium acetate, trioctylmethylammonium bis(trifluoromethanesulfonyl)imide salt, and 1-hexadecyl-3-methylimidazolium trifluoromethanesulfonate. And / or, the pressure-sensitive adhesive matrix material includes at least one of silicone pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, and polyurethane pressure-sensitive adhesive.

10. The application of the electro-tack reducing pressure-sensitive adhesive as described in claim 8 or 9 in portable smart electronic appliances.

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