Conductive tpu film for electronic workbench

Abstract

The application discloses a conductive TPU film for an electronic workbench, which comprises, from bottom to top, a conductive layer one, an intermediate layer and a conductive layer two; the conductive layer one and the conductive layer two are both made of the following raw materials in parts by weight: polyether type TPU 80-100 parts, conductive master batch 30-40 parts, silicone lubricant 1-5 parts and antioxidant 0.5-1 part; and the intermediate layer is made of the following raw materials: polyether type TPU 90-100 parts, conductive master batch 5-10 parts and silicone lubricant 0.1-2 parts. The conductive TPU film is hot-pressed and combined with the conductive layer one, the intermediate layer and the conductive layer two, and the prepared TPU conductive film is uniform in overall thickness; the modified carbon black and the carbon nanotube are made into a conductive master batch with TPU, and the conductive master batch is flow-casted with TPU, so that the conductive TPU film has good mechanical properties and conductive properties, and has wide social and economic benefits and strategic value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of polymer film materials, and particularly relates to a conductive TPU film for an electronic workbench. BACKGROUND

[0002] Flexible electronic materials have wide application prospects in the fields of information, energy, medical treatment and national defense due to their unique flexibility, ductility and efficient and low-cost manufacturing process. As one of the key materials for flexible electronics, flexible conductive films have attracted extensive attention of researchers. At present, there are mainly two methods for preparing flexible conductive films: one is to coat conductive materials such as nano-silver wires and carbon nanotubes on the surface of a polymer substrate, and then obtain a conductive film through heat treatment; and the other is to disperse conductive materials in a polymer substrate and prepare a conductive film by using a flow casting method. The first method is the main method currently applied because the conductive film prepared by the method has good conductivity and comprehensive mechanical properties, but the method still has problems to be solved, such as low adhesion of the conductive material and poor repeatability; the second method is simple in process, but in order to ensure that the conductive film has good electrical properties, a large amount of conductive material needs to be filled in the polymer substrate, which leads to problems such as reduced processability and mechanical properties of the conductive film.

[0003] At present, the conductive film for an electronic workbench mainly uses PC and PE thermosetting materials, and the conductive film prepared by multiple compounding has high hardness, belongs to D hardness, has poor ductility, and the elongation at break is often less than 300%, and the conductive film is prone to serious creases and cannot be recovered.

[0004] TPU, thermoplastic polyurethane elastomer rubber, is a new type of organic high molecular synthetic material, which can replace rubber or soft polyvinyl chloride material. The good wear resistance and resilience of TPU are better than those of ordinary polyurethane, and the aging resistance is better than that of rubber. It can be said that TPU is the most ideal material to replace PVC and PU, and it is called a new polymer material in the international community. Its molecular structure is alternately composed of rigid blocks obtained by the reaction of diisocyanate and chain extender and flexible chains obtained by the reaction of diisocyanate and macromolecular polyol. TPU has excellent high tension, high pulling force, toughness and aging resistance, and has been widely used in medical health, electronic appliances and sports equipment.

[0005] In the prior art, the TPU conductive film is made of TPU particles and high-concentration carbon black masterbatch by calendering, and the film has poor fluidity and large thickness error. Generally, the thickness of the conductive film is required to be above 0.3 mm, and the large thickness error causes serious unevenness, affecting the physical properties of TPU, and the tensile strength and tear strength of the conductive film decrease by 40-50% compared with pure TPU. Chinese Patent Application No. 201710492866.2 discloses an electrostrictive composite material and a preparation method and application thereof. The electrostrictive composite material is prepared from 50-60% TPU particles, 10-20% carbon nanotubes, 20-30% nano-barium titanate, 1-5% nano-silver particles, 1-10% nano-cellulose and 5-20% glass fibers. The components cooperate with each other and synergistically act, so that the electrostrictive rate can be as high as 22-24.5%, and the electrostrictive composite material can be applied to the field of functional materials and has good application prospect. However, the balance between the mechanical properties and the conductive properties of the composite material prepared by the invention is not good. Chinese Patent Application No. 201610405332.7 discloses an antiskid and antistatic TPU film and a preparation method thereof. The antiskid and antistatic TPU film is prepared from 70-90 parts by weight of TPU particles, 20-40 parts by weight of epoxy resin, 10-15 parts by weight of polycarbodiimide, 10-20 parts by weight of nylon fiber, 20-30 parts by weight of conductive carbon fiber, 10-20 parts by weight of glass fiber and 1-5 parts by weight of antioxidant. The surface resistivity of the TPU film is 5.2x10 5 -7.5x10 5 Ω, the antistatic performance is good, the antiskid friction coefficient is 0.6-0.8, and the TPU film has good antiskid performance. In addition, the TPU film prepared by the invention has good mechanical properties, with an elastic modulus of 38-42 MPa, an elongation at break of 550.52-628.25%, and a tensile breaking stress of 58.5-65.7 MPa, but the conductive performance needs to be further improved. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a conductive TPU film for an electronic workbench, which has uniform thickness, can maintain the original physical properties of TPU, has good conductivity, and has wide social and economic benefits and strategic value.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] The application discloses a conductive TPU film for an electronic workbench, which comprises, from bottom to top, a conductive layer one, an intermediate layer and a conductive layer two, and is prepared from the following raw materials by weight: 80-100 parts of polyether TPU, 30-40 parts of conductive master batch, 1-5 parts of silicone lubricant and 0.5-1 part of antioxidant; and the intermediate layer is prepared from the following raw materials: 90-100 parts of polyether TPU, 5-10 parts of conductive master batch and 0.1-2 parts of silicone lubricant.

[0009] Preferably, the conductive TPU film for the electronic workbench comprises, from bottom to top, the conductive layer one, the intermediate layer and the conductive layer two, and is prepared from the following raw materials by weight: 90-100 parts of polyether TPU, 35-40 parts of conductive master batch, 2-4 parts of silicone lubricant and 0.8-1 part of antioxidant; and the intermediate layer is prepared from the following raw materials: 95-100 parts of polyether TPU, 8-10 parts of conductive master batch and 0.5-1 part of silicone lubricant.

[0010] Preferably, the polyether TPU has a hardness of 80-90A; the antioxidant is one or more of antioxidant 168, antioxidant 1098 and antioxidant 1010; the conductive layer one has a thickness of 0.05-0.1 mm, the intermediate layer has a thickness of 0.1-0.3 mm, and the conductive layer two has a thickness of 0.05-0.1 mm.

[0011] Preferably, the conductive master batch is prepared in the following manner:

[0012] (a) carbon black is added into an ethanol aqueous solution, then gamma-aminopropyltrimethoxysilane is added, stirring reaction is carried out, after the reaction is completed, filtration and drying are carried out to obtain a solid product, then the solid product is added into deionized water, carboxylated cellulose and p-toluenesulfonic acid are added, heating reaction is carried out, after the reaction is completed, filtration, washing and drying are carried out to obtain pretreated carbon black;

[0013] (b) the pretreated carbon black in step (a) is added into deionized water, stirring is carried out to obtain a carbon black suspension, under stirring, copper sulfate solution is added dropwise into the carbon black suspension, ultrasonic dispersion is carried out for 0.5-1 h, then hydrazine hydrate is slowly added dropwise, constant-temperature reaction is carried out, after the reaction is completed, filtration, washing and drying are carried out to obtain copper-plated carbon black;

[0014] (c) the copper-plated carbon black in step (b) is added into a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole, impregnation treatment is carried out, after the treatment is completed, filtration and drying are carried out to obtain modified carbon black;

[0015] (d) 40-50 parts of the modified carbon black, 10-20 parts of pretreated carbon nanotube and 50 parts of polyether TPU are blended and milled, a granulator is used to form particles, and drying is carried out to obtain the conductive master batch.

[0016] Preferably, in step (a), the mass ratio of the carbon black and the γ-aminopropyltrimethoxysilane is 20:1-2, the volume ratio of ethanol to water in the aqueous ethanol solution is 2:1-2, the temperature of the stirring reaction is 50-60℃, and the time is 2-4h; the mass ratio of the solid product, the carboxylated cellulose, and the p-toluenesulfonic acid is 20:5-8:0.2-0.5, the temperature of the heating reaction is 70-80℃, and the time is 3-5h.

[0017] Preferably, in step (b), the mass fraction of the pretreated carbon black suspension is 2-4%, the mass fraction of the copper sulfate solution is 10-15%, the amount of the copper sulfate solution added is 20-30% of the mass of the pretreated carbon black suspension, the amount of the hydrazine hydrate added is 7-10% of the mass of the copper sulfate solution, the temperature of the constant-temperature reaction is 60-70℃, and the time is 5-8h.

[0018] Preferably, in step (c), the mass fraction of the 2-mercaptobenzimidazole in the mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole is 1-3%, the mass fraction of the 5-carboxybenzotriazole is 1-3%, the temperature of the impregnation is 40-50℃, and the time is 4-5h.

[0019] Preferably, in step (d), the pretreated carbon nanotube is prepared as follows: 1-3g of vinyltrimethoxysilane is added to 200mL of an aqueous ethanol solution with a volume ratio of 1:1, stirred uniformly to obtain a dispersion, 20-30g of carbon nanotubes is added to the dispersion, and stirring reaction is carried out at 50-60℃ for 2-3h; after the reaction is completed, filtration and drying are carried out to obtain the pretreated carbon nanotube.

[0020] The application also protects a preparation method of the conductive TPU film for the electronic workbench, which comprises the following steps:

[0021] S1, preparation of the conductive film layer one: ingredients are weighed according to the formula, polyether TPU, conductive master batch, silicone lubricant, and antioxidant are uniformly mixed, dehumidified, and dried, then added to a TPU casting machine for high-temperature plasticization, extruded and cast on PP release paper through a mold, and then pressed by a middle roller and a front roller to obtain the conductive film layer one;

[0022] S2, preparation of the intermediate layer: ingredients are weighed according to the formula, polyether TPU, conductive master batch, and silicone lubricant are uniformly mixed, dehumidified, and dried, then added to a TPU casting machine for high-temperature plasticization, extruded and cast on the conductive film layer one in step S1 through a mold, and then pressed by a middle roller and a front roller to obtain a double-layer conductive film;

[0023] S3, preparation of the conductive TPU film: the polyether TPU, conductive masterbatch, silicone lubricant, antioxidant are mixed uniformly after dehumidification and drying, then added into the TPU casting machine for high temperature plasticization, extruded and cast on the middle layer in the double-layer conductive film in step S2 through the die, then pressed by the middle roller and the front roller, wound after cooling and forming, then separated and wound by the rewinding machine, and the PP release paper is separated and wound, to obtain the conductive TPU film.

[0024] Preferably, the temperature of high temperature plasticization is 165-180℃, the die temperature is 170-175℃, the front roller is normal temperature, and the middle roller temperature is 40-50℃.

[0025] More preferably, the temperature of high temperature plasticization is 170-180℃, the die temperature is 170-175℃, the front roller is normal temperature, and the middle roller temperature is 45-50℃.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The TPU conductive film for electronic workbench provided by the present application is hot-pressed and combined by the conductive layer one, the middle layer and the conductive layer two, and the prepared TPU conductive film has uniform overall thickness. The modified carbon black and carbon nanotube are made into a conductive masterbatch with TPU, and then the conductive masterbatch is flow-cast with TPU, so that the TPU conductive film has good mechanical properties and conductive properties, and has wide social and economic benefits and strategic value.

[0028] (2) The TPU conductive film for electronic workbenches provided by this invention uses modified carbon black and pretreated carbon nanotubes as conductive fillers in the prepared conductive masterbatch. First, carbon black is reacted with γ-aminopropyltrimethoxysilane to aminate it. Then, the aminated carbon black is reacted with carboxylated cellulose to introduce cellulose onto the carbon black surface, resulting in pretreated carbon black. The introduction of cellulose not only improves the dispersion performance of the carbon black but also introduces a large number of adsorption sites on the carbon black surface, which is beneficial for the subsequent copper plating reaction on the carbon black surface. Next, the pretreated carbon black is added to a copper sulfate solution, and copper is reduced using hydrazine hydrate to coat the carbon black surface with copper nanoparticles, further improving the conductivity of the carbon black. Then, the copper-plated carbon black is immersed in a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole for treatment. The lone pairs of electrons from heteroatoms such as N, O, and S in benzotriazole, as well as the large π bond in the benzene ring, can strongly coordinate with electrons in the copper atomic orbitals, forming coordinate bonds and an organic film on the copper surface. This improves the bonding force between copper-plated carbon black and TPU, avoiding the problem of decreased bonding force between carbon black and TPU caused by copper plating. Simultaneously, the thiol groups introduced from 2-mercaptobenzimidazole can react with the double bonds in pretreated carbon nanotubes during the subsequent preparation of conductive masterbatch, forming a conductive network and improving the conductivity of the TPU conductive film. The conductive masterbatch added in this invention specifically modifies the carbon black, improving its conductivity while ensuring its dispersibility and compatibility in TPU. Furthermore, the added pretreated carbon nanotubes synergistically enhance the conductivity of the TPU conductive film. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] The carboxylated cellulose was prepared according to the literature (Preparation and Strain Response Properties of Nanocellulose-Carbon Nanotube / Thermoplastic Polyurethane Composite Films, Ou Huajie et al., Journal of Composite Materials, November 2020, Vol. 37, No. 11). The specific steps are as follows: 40g of nanocellulose was added to 500g of deionized water and stirred to disperse evenly. Then, 4mL of 1mol / L TEMPO solution and 10mL of 1mol / L NaBr solution were added. After stirring for 30min, 130mL of 2% NaClO solution was added, and deionized water was added to make the concentration of nanocellulose 2wt%. The reaction was carried out at room temperature for 4h. During the reaction, the pH value of the oxidation system was controlled to be maintained between 10.0 and 10.5. After the reaction was completed, 200mL of anhydrous ethanol was added to terminate the reaction. Then, the mixture was centrifuged, filtered, washed, and dried to obtain the carboxylated cellulose.

[0031] The carbon black was purchased from Guangzhou Jingyi New Materials Co., Ltd., with the grade Cabot conductive carbon black VULCANXC-72R and a particle size of 30nm; the carbon nanotubes were purchased from Jiaxing Naco New Materials Co., Ltd., with a length of 10μm and a diameter of 40-60nm.

[0032] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0033] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 80-100 parts of polyether-type TPU, 30-40 parts of conductive masterbatch, 1-5 parts of silicone lubricant, and 0.5-1 parts of antioxidant evenly, dehumidify and dry, then add it to a TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through a mold. The high-temperature plasticization temperature is 165-180℃, the mold temperature is 170-175℃, and the thickness is 0.05-0.1mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, and the middle roller temperature is 40-50℃. The conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0034] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 90-100 parts of polyether-type TPU, 5-10 parts of conductive masterbatch, and 0.1-2 parts of silicone lubricant evenly, dehumidify and dry, then add to a TPU casting machine for high-temperature plasticization, and extrude a 0.1-0.3mm intermediate layer onto the conductive film layer 1 in step S1 through a mold. The high-temperature plasticization temperature is 165-180℃, the mold temperature is 170-175℃, and then press it through the middle roller and the front roller. The front roller is at room temperature, and the middle roller temperature is 40-50℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0035] S3. Preparation of conductive TPU film: Mix 80-100 parts of polyether-type TPU, 30-40 parts of conductive masterbatch, 1-5 parts of silicone lubricant, and 0.5-1 parts of antioxidant evenly, then dehumidify and dry. Subsequently, add it to a TPU casting machine for high-temperature plasticization. Extrude and cast a 0.05-0.1mm conductive layer onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 165-180℃, and the die temperature is 170-175℃. Then, press it with a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller temperature is 40-50℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0036] The polyether-type TPU has a hardness of 80-90A; the antioxidant is one or more of antioxidant 168, antioxidant 1098, and antioxidant 1010.

[0037] The preparation method of the conductive masterbatch is as follows:

[0038] (a) Add 40-50g of carbon black to 800mL of ethanol aqueous solution (ethanol to water volume ratio of 2:1-2), then add 2-5g of γ-aminopropyltrimethoxysilane, stir and react at 50-60℃ for 2-4h. After the reaction is completed, filter and dry to obtain a solid product. Then add 40-50g of solid product to 800mL of deionized water, then add 10-15g of carboxylated cellulose and 0.4-1g of p-toluenesulfonic acid, and react at 70-80℃ for 3-5h. After the reaction is completed, filter, wash and dry to obtain pretreated carbon black.

[0039] (b) Add 40-50g of pretreated carbon black from step (a) to 1L of deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring, add a copper sulfate solution with a mass fraction of 10-15% dropwise to the carbon black suspension. The amount of copper sulfate solution added is 20-30% of the mass of the pretreated carbon black suspension. Disperse the suspension by ultrasonication for 0.5-1h. Then slowly add hydrazine hydrate. The amount of hydrazine hydrate added is 7-10% of the mass of the copper sulfate solution. React at a constant temperature of 60-70℃ for 5-8h. After the reaction is complete, filter, wash, and dry to obtain copper-plated carbon black.

[0040] (c) Add 40-50g of copper-plated carbon black from step (b) to 500mL of a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole (2-mercaptobenzimidazole mass fraction is 1-3%, and 5-carboxybenzotriazole mass fraction is 1-3%), and impregnate at 40-50℃ for 4-5h. After treatment, filter and dry to obtain modified carbon black.

[0041] (d) Add 1-3g of vinyltrimethoxysilane to 200mL of ethanol aqueous solution with a volume ratio of 1:1, stir evenly to obtain a dispersion, then add 20-30g of carbon nanotubes to the dispersion, stir and react at 50-60℃ for 2-3h, filter and dry after the reaction is completed to obtain pretreated carbon nanotubes.

[0042] (e) 40-50g of modified carbon black, 10-20g of pretreated carbon nanotubes and 50g of polyether-type TPU are blended and mixed, granulated by a granulation machine and dried to obtain the conductive masterbatch.

[0043] Example 1

[0044] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0045] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 90 parts of 85A polyether type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant 1098 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0046] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 95 parts of 85A polyether type TPU, 7 parts of conductive masterbatch, and 0.5 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller temperature is 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0047] S3. Preparation of conductive TPU film: 90 parts of 85A polyether-type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0048] The method for preparing the conductive masterbatch is as follows:

[0049] (a) 50g of carbon black was added to 800mL of ethanol-water solution (ethanol to water volume ratio of 2:1), followed by 5g of γ-aminopropyltrimethoxysilane. The mixture was stirred at 55℃ for 3h. After the reaction was completed, the mixture was filtered and dried to obtain a solid product. Then, 50g of the solid product was added to 800mL of deionized water, followed by 15g of carboxylated cellulose and 1g of p-toluenesulfonic acid. The mixture was reacted at 75℃ for 4h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated carbon black.

[0050] (b) Add 50g of pretreated carbon black from step (a) to 1L of deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring, add 250g of 10% copper sulfate solution to the carbon black suspension and disperse by ultrasonication for 1h. Then slowly add 20g of hydrazine hydrate and react at 65℃ for 7h. After the reaction is complete, filter, wash and dry to obtain copper-plated carbon black.

[0051] (c) Add 50g of copper-plated carbon black from step (b) to 500mL of a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole (2% by mass of 2-mercaptobenzimidazole and 2% by mass of 5-carboxybenzotriazole), immerse at 45°C for 4.5h, filter and dry after treatment to obtain modified carbon black;

[0052] (d) Add 2g of vinyltrimethoxysilane to 200mL of ethanol aqueous solution with a volume ratio of 1:1, stir evenly to obtain a dispersion, then add 25g of carbon nanotubes to the dispersion, stir and react at 55℃ for 2.5h, filter and dry after the reaction is completed to obtain pretreated carbon nanotubes.

[0053] (e) 50g of modified carbon black, 20g of pretreated carbon nanotubes and 50g of 85A polyether TPU are blended and mixed, granulated by a granulator and dried to obtain the conductive masterbatch.

[0054] Example 2

[0055] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0056] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 80 parts of 85A polyether type TPU, 30 parts of conductive masterbatch, 1 part of silicone lubricant, and 0.5 parts of antioxidant 168 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the winding is to obtain conductive film layer one (retaining conductive film layer one as an integral part of PP release paper).

[0057] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 90 parts of 85A polyether TPU, 5 parts of conductive masterbatch, and 0.1 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller is at 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0058] S3. Preparation of conductive TPU film: 80 parts of 85A polyether-type TPU, 30 parts of conductive masterbatch, 1 part of silicone lubricant, and 0.5 parts of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0059] The method for preparing the conductive masterbatch is as follows:

[0060] (a) 45g of carbon black was added to 800mL of ethanol-water solution (ethanol to water volume ratio of 2:2), followed by 4g of γ-aminopropyltrimethoxysilane. The mixture was stirred at 50℃ for 4h. After the reaction was completed, the mixture was filtered and dried to obtain a solid product. Then, 45g of the solid product was added to 800mL of deionized water, followed by 13g of carboxylated cellulose and 0.6g of p-toluenesulfonic acid. The mixture was reacted at 70℃ for 5h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated carbon black.

[0061] (b) Add 45g of pretreated carbon black from step (a) to 1L of deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring, add 300g of 10% copper sulfate solution dropwise to the carbon black suspension and sonicate for 0.5h. Then slowly add 24g of hydrazine hydrate and react at 60℃ for 8h. After the reaction is complete, filter, wash and dry to obtain copper-plated carbon black.

[0062] (c) Add 45g of copper-plated carbon black from step (b) to 500mL of a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole (2-mercaptobenzimidazole mass fraction is 1% and 5-carboxybenzotriazole mass fraction is 3%), and impregnate at 40℃ for 5h. After the treatment is completed, filter and dry to obtain modified carbon black.

[0063] (d) Add 1g of vinyltrimethoxysilane to 200mL of ethanol aqueous solution with a volume ratio of 1:1, stir evenly to obtain a dispersion, then add 20g of carbon nanotubes to the dispersion, stir at 50℃ for 3h, filter and dry after the reaction is completed to obtain pretreated carbon nanotubes.

[0064] (e) 45g of modified carbon black, 20g of pretreated carbon nanotubes and 50g of 85A polyether-type TPU are blended and mixed, granulated by a granulator and dried to obtain the conductive masterbatch.

[0065] Example 3

[0066] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0067] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 100 parts of 85A polyether type TPU, 40 parts of conductive masterbatch, 5 parts of silicone lubricant, and 1 part of antioxidant 1010 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0068] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 100 parts of 85A polyether TPU, 10 parts of conductive masterbatch, and 2 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller is at 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0069] S3. Preparation of conductive TPU film: 100 parts of 85A polyether-type TPU, 40 parts of conductive masterbatch, 5 parts of silicone lubricant, and 1 part of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0070] The method for preparing the conductive masterbatch is as follows:

[0071] (a) 40g of carbon black was added to 800mL of ethanol-water solution (ethanol to water volume ratio of 2:2), followed by 2g of γ-aminopropyltrimethoxysilane. The mixture was stirred at 60℃ for 2 hours. After the reaction was completed, the mixture was filtered and dried to obtain a solid product. Then, 40g of the solid product was added to 800mL of deionized water, followed by 10g of carboxylated cellulose and 0.4g of p-toluenesulfonic acid. The mixture was reacted at 80℃ for 3 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated carbon black.

[0072] (b) Add 40g of pretreated carbon black from step (a) to 1L of deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring, add 25g of 15% copper sulfate solution to the carbon black suspension and sonicate for 0.5-1h. Then slowly add 25g of hydrazine hydrate and react at 70℃ for 5h. After the reaction is complete, filter, wash and dry to obtain copper-plated carbon black.

[0073] (c) Add 40g of copper-plated carbon black from step (b) to 500mL of a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole (2-mercaptobenzimidazole mass fraction is 3% and 5-carboxybenzotriazole mass fraction is 1%), and impregnate at 50℃ for 4h. After the treatment is completed, filter and dry to obtain modified carbon black.

[0074] (d) Add 3g of vinyltrimethoxysilane to 200mL of ethanol aqueous solution with a volume ratio of 1:1, stir evenly to obtain a dispersion, then add 30g of carbon nanotubes to the dispersion, stir and react at 60℃ for 2h, filter and dry after the reaction is completed to obtain pretreated carbon nanotubes.

[0075] (e) 40g of modified carbon black, 20g of pretreated carbon nanotubes and 50g of 85A polyether-type TPU are blended and mixed, granulated by a granulator and dried to obtain the conductive masterbatch.

[0076] Comparative Example 1

[0077] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0078] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 90 parts of 85A polyether type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant 1098 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0079] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 95 parts of 85A polyether type TPU, 7 parts of conductive masterbatch, and 0.5 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller temperature is 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0080] S3. Preparation of conductive TPU film: 90 parts of 85A polyether-type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0081] The method for preparing the conductive masterbatch is as follows:

[0082] 50g of carbon black, 20g of carbon nanotubes, and 50g of 85A polyether-type TPU are blended and mixed, then granulated using a granulator and dried to obtain the conductive masterbatch.

[0083] Comparative Example 2

[0084] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0085] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 90 parts of 85A polyether type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant 1098 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0086] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 95 parts of 85A polyether type TPU, 7 parts of conductive masterbatch, and 0.5 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller temperature is 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0087] S3. Preparation of conductive TPU film: 90 parts of 85A polyether-type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0088] The method for preparing the conductive masterbatch is as follows:

[0089] (a) 50g of carbon black was added to 800mL of ethanol-water solution (ethanol to water volume ratio of 2:1), followed by 5g of γ-aminopropyltrimethoxysilane. The mixture was stirred at 55℃ for 3h. After the reaction was completed, the mixture was filtered and dried to obtain a solid product. Then, 50g of the solid product was added to 800mL of deionized water, followed by 15g of carboxylated cellulose and 1g of p-toluenesulfonic acid. The mixture was reacted at 75℃ for 4h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated carbon black.

[0090] (b) Add 50g of pretreated carbon black from step (a) to 1L of deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring, add 250g of 10% copper sulfate solution to the carbon black suspension and disperse by ultrasonication for 1h. Then slowly add 20g of hydrazine hydrate and react at 65℃ for 7h. After the reaction is complete, filter, wash and dry to obtain copper-plated carbon black.

[0091] (c) 50g of copper-plated carbon black, 20g of carbon nanotubes and 50g of 85A polyether-type TPU are blended and mixed, granulated by a granulation machine and dried to obtain the conductive masterbatch.

[0092] Comparative Example 3

[0093] A method for preparing a conductive TPU film for an electronic workbench includes the following steps:

[0094] S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix 90 parts of 85A polyether type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant 1098 evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude it onto PP release paper through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and the thickness is 0.05mm. Then, it is pressed by the middle roller (matte steel roller) and the front roller (rubber roller). The front roller is at room temperature, the middle roller temperature is 45℃, and the conductive film layer one is obtained by winding (the conductive film layer one is retained as an integral part of the PP release paper).

[0095] S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix 95 parts of 85A polyether type TPU, 7 parts of conductive masterbatch, and 0.5 parts of silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high-temperature plasticization, and extrude a 0.2mm intermediate layer onto the conductive film layer 1 in step S1 through the mold. The high-temperature plasticization temperature is 175℃, the mold temperature is 170℃, and then it is pressed by the middle roller and the front roller. The front roller is at room temperature, and the middle roller temperature is 45℃, so that the intermediate layer and the conductive film layer 1 are combined into one, to obtain a double-layer conductive film (PP release paper is retained).

[0096] S3. Preparation of conductive TPU film: 90 parts of 85A polyether-type TPU, 35 parts of conductive masterbatch, 3 parts of silicone lubricant, and 0.8 parts of antioxidant are mixed evenly and then dehumidified and dried. Then, the mixture is added to a TPU casting machine for high-temperature plasticization. A 0.05mm conductive layer is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a die. The high-temperature plasticization temperature is 175℃, and the die temperature is 170℃. Then, the film is pressed by a middle roller (matte steel roller) and a front roller (rubber roller). The front roller is at room temperature, and the middle roller is at 45℃. After winding and cooling, the PP release paper is separated and wound up using a rewinding machine to obtain the conductive TPU film.

[0097] The method for preparing the conductive masterbatch is as follows:

[0098] (a) Add 2g of vinyltrimethoxysilane to 200mL of ethanol aqueous solution with a volume ratio of 1:1, stir evenly to obtain a dispersion, then add 25g of carbon nanotubes to the dispersion, stir and react at 55℃ for 2.5h, filter and dry after the reaction is completed to obtain pretreated carbon nanotubes.

[0099] (b) 50g of carbon black, 20g of pretreated carbon nanotubes and 50g of 85A polyether-type TPU are blended and mixed, granulated by a granulator and dried to obtain the conductive masterbatch.

[0100] The conductive TPU films prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, and the test results are shown in Table 1 below:

[0101] Table 1

[0102]

[0103]

[0104] As can be seen from the experimental results in Table 1, the TPU conductive film prepared by this invention exhibits excellent physical properties, retains the inherent properties of thermoplastic polyurethane, and also has low surface resistance and good conductivity.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A conductive TPU film for an electronic workbench, characterized in that, The structure comprises, from bottom to top, a conductive layer one, an intermediate layer, and a conductive layer two. By weight, conductive layer one and conductive layer two are both made from the following raw materials: 80-100 parts polyether-type TPU, 30-40 parts conductive masterbatch, 1-5 parts silicone lubricant, and 0.5-1 part antioxidant; the intermediate layer is made from the following raw materials: 90-100 parts polyether-type TPU, 5-10 parts conductive masterbatch, and 0.1-2 parts silicone lubricant. The preparation method of the conductive masterbatch is as follows: (a) Carbon black was added to an aqueous ethanol solution, followed by the addition of γ-aminopropyltrimethoxysilane. The mixture was stirred and reacted. After the reaction was completed, the mixture was filtered and dried to obtain a solid product. The solid product was then added to deionized water, followed by the addition of carboxylated cellulose and p-toluenesulfonic acid. The mixture was heated and reacted. After the reaction was completed, the mixture was filtered, washed, and dried to obtain pretreated carbon black. (b) Add the pretreated carbon black from step (a) to deionized water and stir until homogeneous to obtain a carbon black suspension. Under stirring conditions, add copper sulfate solution dropwise to the carbon black suspension and ultrasonically disperse for 0.5-1 h. Then slowly add hydrazine hydrate and carry out a constant temperature reaction. After the reaction is completed, filter, wash and dry to obtain copper-plated carbon black. (c) The copper-plated carbon black from step (b) is added to a mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole for impregnation treatment. After the treatment is completed, the mixture is filtered and dried to obtain modified carbon black. (d) 40-50 parts of modified carbon black, 10-20 parts of pretreated carbon nanotubes, and 50 parts of polyether-type TPU are blended and kneaded, then granulated using a granulator and dried to obtain the conductive masterbatch; The pretreated carbon nanotubes prepared in step (d) are prepared as follows: 1-3g of vinyltrimethoxysilane is added to 200mL of ethanol aqueous solution with a volume ratio of 1:1 and stirred evenly to obtain a dispersion. Then, 20-30g of carbon nanotubes are added to the dispersion and stirred at 50-60℃ for 2-3h. After the reaction is completed, the mixture is filtered and dried to obtain the final product.

2. The conductive TPU film for electronic workbenches according to claim 1, characterized in that, By weight, both conductive layer one and conductive layer two are made of the following raw materials: 90-100 parts of polyether-type TPU, 35-40 parts of conductive masterbatch, 2-4 parts of silicone lubricant, and 0.8-1 parts of antioxidant; the intermediate layer is made of the following raw materials: 95-100 parts of polyether-type TPU, 8-10 parts of conductive masterbatch, and 0.5-1 parts of silicone lubricant.

3. The conductive TPU film for electronic workbenches according to claim 1, characterized in that, The hardness of the polyether-type TPU is 80-90A; the antioxidant is one or more of antioxidant 168, antioxidant 1098, and antioxidant 1010; the thickness of the first conductive layer is 0.05-0.1mm, the thickness of the intermediate layer is 0.1-0.3mm, and the thickness of the second conductive layer is 0.05-0.1mm.

4. The conductive TPU film for electronic workbenches according to claim 1, characterized in that, In step (a), the mass ratio of carbon black to γ-aminopropyltrimethoxysilane is 40-50:2-5, the volume ratio of ethanol to water in the aqueous ethanol solution is 2:1-2, the stirring reaction temperature is 50-60℃, and the time is 2-4h; the mass ratio of the solid product, carboxylated cellulose, and p-toluenesulfonic acid is 40-50:10-15:0.4-1, the heating reaction temperature is 70-80℃, and the time is 3-5h.

5. The conductive TPU film for electronic workbenches according to claim 1, characterized in that, In step (b), the mass fraction of the carbon black suspension is 2-4%, the mass fraction of the copper sulfate solution is 10-15%, the amount of copper sulfate solution added is 20-30% of the mass of the carbon black suspension, the amount of hydrazine hydrate added is 7-10% of the mass of the copper sulfate solution, the temperature of the isothermal reaction is 60-70℃, and the time is 5-8h.

6. The conductive TPU film for electronic workbenches according to claim 1, characterized in that, In step (c), the mass fraction of 2-mercaptobenzimidazole in the mixed solution of 2-mercaptobenzimidazole and 5-carboxybenzotriazole is 1-3%, and the mass fraction of 5-carboxybenzotriazole is 1-3%. The impregnation temperature is 40-50℃ and the time is 4-5h.

7. A method for preparing a conductive TPU film for an electronic workbench as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Preparation of conductive film layer one: Weigh the raw materials according to the formula, mix polyether TPU, conductive masterbatch, silicone lubricant and antioxidant evenly, dehumidify and dry, then add to TPU casting machine for high temperature plasticization, extrude and cast onto PP release paper through mold, and then press through the middle roller and front roller to obtain conductive film layer one. S2. Preparation of the intermediate layer: Weigh the raw materials according to the formula, mix the polyether TPU, conductive masterbatch and silicone lubricant evenly, dehumidify and dry, then add it to the TPU casting machine for high temperature plasticization, and extrude it through the mold onto the conductive film layer in step S1. Then press it with the middle roller and the front roller to obtain a double-layer conductive film. S3. Preparation of conductive TPU film: Polyether-type TPU, conductive masterbatch, silicone lubricant and antioxidant are mixed evenly and then dehumidified and dried. Then, it is added to a TPU casting machine for high-temperature plasticization. It is extruded and cast onto the middle layer of the double-layer conductive film in step S2 through a mold. Then, it is pressed by the middle roller and the front roller, wound up and cooled to form. Finally, the PP release paper is separated and wound up by a rewinding machine to obtain the conductive TPU film.

8. The preparation method according to claim 7, characterized in that, The high-temperature plasticizing temperature is 165-180℃, the mold temperature is 170-175℃, the front roller is at room temperature, and the middle roller temperature is 40-50℃.

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