TWI691536B - Graphene polymer composite - Google Patents

Abstract

A graphene polymer composite material, including a substrate, a plurality of graphene sheets and a polymer layer, the substrate has two opposite surfaces, the plurality of graphene sheets are parallel and attached to the two surfaces of the substrate, the polymer layer covers the plurality of graphite The second surface of the vinyl sheet and the substrate. The invention further provides a method for preparing graphene polymer composite materials.

Description

Graphene polymer composite

The invention relates to a graphene polymer composite material with high mechanical strength and a preparation method thereof.

In 2004, Andre Geim and Konstantin Novoselov of the University of Manchester in England successfully used a tape to strip graphite to obtain a single layer of graphene (graphene). The graphene is mainly composed of sp ² mixed orbital domains composed of a hexagonal honeycomb arrangement of two-dimensional crystal structure, its thickness is only 0.335nm, that is, the size of only one carbon atom diameter. The specific gravity of graphene is only about a quarter of that of steel, and the mechanical strength can be much higher than that of steel. It is currently the material with the strongest mechanical strength, and graphene with excellent performance in terms of electrical conductivity, thermal conductivity, chemical resistance, etc. It has been applied in different technical fields by industry.

However, the most common problem in practical applications is that graphene sheets are not easy to disperse uniformly, are easily aggregated, stacked and agglomerated, and may even reunite even after a short dispersion. Therefore, how to prevent graphene sheets from being unevenly stacked on each other The phenomenon of obtaining graphene powder with uniform dispersion and few layers has always been the most technical bottleneck in the industry.

Chinese Patent No. 101864098B discloses a preparation method of polymer and graphene composite masterbatch, which is to disperse graphite oxide in polymer latex by graphene powder and solvent by ultrasonic or grinding method, and pass reducing agent into polymer latex In-situ reduction of graphene oxide is carried out, and then solid polymer and graphene composite masterbatch are obtained through steps such as demulsification, coagulation, and drying. However, in addition to studies indicating that the ultrasonic method is less suitable for high viscosity liquids (Rasheed Atif, Fawad Inam, Beilstein Jornal of Nanotechnology. 2016, 7, 1174-1196), polymers containing solvents and reduced graphene During the drying process of latex, the reduced graphene will be re-aggregated due to the volatilization of the solvent.

Chinese Patent No. 106221128A discloses a method for preparing a carbon fiber composite material, in which composite resin and filler (for example: graphene) are pre-heated to between 30 and 150 degrees Celsius, and the modified filler is dispersed in the matrix resin by ultrasound After that, it is milled several times with a roller to obtain a modified resin after cooling. The modified resin and carbon fiber are prepared on a hot-melt prepreg machine to prepare a carbon fiber prepreg, and then the deposited carbon fiber prepreg is hot-pressed to obtain Carbon fiber composite material. However, if graphene is used as the modified filler in this method, the graphene in the matrix resin will agglomerate during the cooling process, resulting in the modified resin not having the expected performance.

US Patent No. 20150333320A1 discloses a method for manufacturing a positive electrode active material and graphene composite particles. The graphene oxide and the positive electrode active material containing functional groups on the surface are compounded in a kneading machine to obtain precursor particles. Or a reducing agent oxidizes graphene to obtain positive electrode active material and graphene composite particles. Studies have pointed out that more surface functional groups on reduced graphene oxide indicate higher oxygen content and lower electrical and thermal conductivity (Naoki Morimoto, Takuya Kubo, Yuta Nishina, Scientific Reports 6, 2016, 21715). Therefore, the aforementioned method must The relative ratio of functional groups and oxygen content of graphene is strictly controlled by temperature and reducing atmosphere. Although graphene with higher oxygen content is less prone to agglomeration, the characteristics of graphene have been lost.

It can be seen from the above-mentioned conventional technology that the current graphene dispersion technology is limited to specific material forms or operating conditions, and the short-time dispersion of graphene mixed with other materials may improve performance, but in practical applications, graphene mixed with other materials must be at least Only by maintaining a decentralized state for a certain period of time will it be industrially usable.

To achieve the above object, the present invention provides a method for preparing graphene dispersion paste, which comprises: mixing and stirring graphene sheets, solvents and polymers to form a pseudoplastic non-Newtonian fluid, wherein the graphene sheets are composed of 2 to 30 graphene stacked on top of each other It is composed of layers with a bulk density of 0.005-0.05 g/cm ³ , a thickness of 0.68-10 nm, and a plane lateral dimension of 1-100 μm; and the application of a pressure of not less than 10 bar makes the pseudoplastic non-Newtonian fluid pass through the gap no more than The 1000 μm slit is formed at least twice to form a graphene dispersion paste, in which the viscosity of the pseudoplastic non-Newtonian fluid passing through the slit is between 10-10000 cps, and the viscosity of the graphene dispersion paste is between 50,000 and 350,000 cps.

In one embodiment, the graphene sheet accounts for 0.05-20 wt% of the pseudoplastic non-Newtonian fluid.

In one embodiment, the surface of the graphene sheet has a functional group of Rx-R'y, R is at least one selected from the group consisting of benzene ring, pyridine and triazine, and R'is selected from amino, At least one of an alkoxy group, a carbonyl group, a carboxyl group, an alkoxy group, an amide group, an alkoxy group, a dimethylamino group, and an alkoxy carboxyl group, 1≦x≦4, 1≦y≦6.

In one embodiment, the pressure is increased to 10-30 bar, and the gap between the slits is reduced to 10-1000 μm.

In one embodiment, the above preparation method further includes: heating to 30-200° C. to reduce the viscosity of the graphene dispersion paste to 10000-50,000 cps, and removing bubbles in the graphene dispersion paste with reduced viscosity by centrifugal force.

Based on the above preparation method, the present invention provides a graphene dispersion paste having a viscosity between 50,000 and 350,000 cps and a scraper fineness of less than 20 μm, and includes: a graphene sheet, a solvent, and a first polymer, wherein the graphene sheet The content is between 0.05-20 wt%, and has a bulk density of 0.005-0.05 g/cm ³ , a thickness of 0.68-10 nm, and a planar lateral dimension of 1-100 μm.

Based on the above preparation method, the present invention provides a method for using a graphene dispersion paste, including: preparing the above graphene dispersion paste; diluting the above graphene dispersion paste to form a graphene dispersion liquid having a viscosity not greater than 50,000 cps; applying a graphene dispersion liquid On the substrate, the graphene sheet is dispersed and settled on the surface of the substrate; and the graphene dispersion liquid is cured, so that the first polymer adheres the graphene sheet to the surface of the substrate.

In one embodiment, the graphene dispersion paste is diluted with a solvent or a second polymer compatible with the first polymer to form a graphene dispersion; after curing the graphene dispersion, the first polymer and the second The polymer adheres the graphene sheet to the surface of the substrate.

In one embodiment, when diluting the graphene dispersion paste, a conductive filler is further added to form the graphene dispersion liquid; after curing the graphene dispersion liquid, the graphene sheet is connected to the conductive filler to form a conductive network.

The present invention utilizes the fluid properties of polymers to form graphene sheets mixed with polymers to form pseudoplastic non-Newtonian fluids with a viscosity greater than 50,000 cps. Applying a pressure of 10-30 bar allows the pseudoplastic non-Newtonian fluids to pass through a 10-1000 μm slit for at least two Secondly, under the action of the high shear force formed by the slit, the viscosity of the polymer suddenly drops to evenly disperse the graphene sheet. The polymer restored to the original viscosity through the slit can effectively prevent the graphene sheet from agglomerating and can last for a long time. Maintain the dispersed state of graphene sheets. When using the graphene dispersion paste of the present invention, by adding a solvent or a compatible polymer to adjust the viscosity of the graphene dispersion paste, the flow direction and rate of the graphene sheet can be controlled, so that the graphene sheet is dispersedly attached to the surface of the material, thereby Graphene dispersion paste can be used in the technical fields of fiber, rubber, electrochemistry, etc., and has deep industrial applicability.

The following describes the embodiments of the present invention in more detail with reference to drawings and component symbols, so that those with ordinary knowledge in the technical field can implement them after studying this specification. It is worth noting that in order to clearly show the main features of the present invention, the figures only show the relative relationship or operation mode of the main elements in a schematic way, and are not drawn according to the actual size, so the thickness, size and shape of the main elements in the figures , Arrangement, configuration, etc. are for reference only, and are not intended to limit the scope of the present invention.

The physical properties of polymer materials change due to factors such as molecular weight, molecular structure, additives, processing conditions, etc. When the fluid polymer is forced to flow, it shows the viscosity of liquid and the elasticity of solid, which is different from Newton The property that the viscosity of a fluid is not affected by shear forces. Under the action of high shear force, the viscosity of the polymer will decrease rapidly and show fluidity close to Newtonian fluid; when the shearing force disappears, the polymer will restore the original viscosity and show the viscoelasticity of non-Newtonian fluid. Therefore, the present invention utilizes the fluid characteristics of polymers to disperse and preserve graphene sheets.

Figure 1 is a flow chart of the steps of the graphene dispersion method of the present invention. As shown in FIG. 1, the graphene dispersion method of the present invention includes: mixing step S10, mixing a plurality of graphene sheets and at least one polymer to form a mixture; stirring step S20, stirring the mixture to form a pseudoplastic non-plasticity between the graphene sheets and the polymer Newtonian fluid; dispersing step S30, pressurizing the pseudoplastic non-Newtonian fluid through the slit to form the graphene dispersion paste at least twice; and defoaming step S40, excluding the gas in the graphene dispersion paste.

Figure 2 is a schematic diagram of the mixing steps of the graphene dispersion method of the present invention. As shown in Figure 2, in the mixing step S10, the graphene solution and at least one polymer (not shown) are added to the mixing device in sequence (such as but not limited to: homogenizer, kneading machine, etc.) to form a viscosity between 100,000 -1,000,000 cps non-flowing mixture.

The graphene solution contains graphene flakes and a solvent, where the graphene flakes are composed of 2 to 30 graphene layers stacked on top of each other, with a bulk density of 0.005-0.05 g/cm ³ , a thickness of 0.68-10 nm, and a thickness of 1-100 μm The horizontal dimension of the plane; solvents such as but not limited to: N-methyl pyrrolidinone (N-methyl pyrrolidinone, NMP), isophorone. The polymer is selected from oily, thermoplastic or thermosetting polymers, which is a liquid or a liquid mixture dissolved in a solvent, and has a viscosity of 300-900,000 cps. Due to the high oil absorption characteristics of graphene sheets, the viscosity of the mixture will be rapidly increased. The higher the viscosity of the selected polymer, the lower the proportion of graphene sheets that can be added to the mixture. Therefore, according to the viscosity of the polymer, the graphene sheet The proportion in the mixture is between 0.05-20 wt%.

In order to increase the dispersibility of the graphene sheet in the polymer, a dispersant may be further added or a surface-modified graphene sheet may be used. The dispersant may be selected from silicone, polyvinylpyrrolidone, sulfate or ester compounds. The surface-modified graphene sheet can be formed by adsorbing at least one surface modifier on the surface of the graphene sheet in a π-π bond stacking mode. The surface modifier has the chemical formula Rx-R'y, where R is selected from benzene At least one kind of functional group of hexagonal ring structure of ring, pyridine and triazine, R′ is selected from amino group, alkoxy group, carbonyl group, carboxyl group, amide group, amide group, alkoxy group , Dimethylamino (dimethylamino) and at least one functional group of alkoxy carboxyl group, 1≦x≦4, 1≦y≦6. The functional group of the surface modifier can make the graphene sheets repel each other in the polymer to improve the stability of the dispersed state of the graphene sheet, and the functional group formed by the surface modifier on the surface of the graphene sheet can form a chemical bond with the polymer The junction strengthens the interface strength between graphene and the polymer, and increases the mechanical strength of the polymer.

Figure 3 is a schematic diagram of the stirring step of the graphene dispersion method of the present invention. As shown in Figure 3, the stirring device (such as but not limited to: a three-axis planetary mixer) includes at least one rotation homogenization mechanism and at least one revolution homogenization mechanism. The rotation homogenization mechanism has a rotation speed of 100-30,000 rpm. The rotation speed is between 100-30,000 rpm. The rotation and revolution homogenization mechanisms are independently controlled by two sets of control units to produce the maximum shear force. In the stirring step S20, the mixture of the graphene sheet and the polymer is put into the stirring device, and the high shear force generated by the stirring device is used to preliminarily disperse the graphene sheet into the polymer to form a pseudoplastic non-plasticity between the graphene sheet and the polymer Newtonian fluids have a viscosity between 50,000 and 350,000 cps.

Figure 4 is a schematic diagram of the dispersion steps of the graphene dispersion method of the present invention. As shown in Figure 4, a dispersing device (such as, but not limited to: a three-drum machine) can apply a pressure of 10-30 bar to a high-viscosity mixed material, allowing a high-viscosity complex material to pass through at a flow rate of 0.1-10 L/min Slit with a gap between 10-1000 μm to form a uniform mixture. In the dispersing step S30, the pseudoplastic non-Newtonian fluid of graphene and polymer is excavated from the stirring device and placed in the dispersing device, and the pseudoplastic non-Newtonian fluid is subjected to a plurality of dispersion processes using the dispersing device to form a graphene dispersion paste. Due to the high pressure and the shear force generated by the slit, the viscosity of the pseudoplastic non-Newtonian fluid rapidly drops to 10-10000 cps. The pseudoplastic non-Newtonian fluid with reduced viscosity produces fluidity in the slit and is separated by the action of shear force The agglomerated graphene sheet, the separated graphene sheet is further dispersed with the fluid with increased flow rate; after the fluid passes through the slit, the shear force disappears and the pseudo-plastic non-Newtonian fluid that restores the original viscosity can draw the graphene sheet to prevent agglomeration , Thereby forming a stable graphene dispersion paste.

In the dispersion step S30, the pressure and the slit gap can be adjusted one by one to further improve the separation and dispersion effect of the graphene sheets. In one embodiment, the conditions of the first dispersion process: the pressure is set to 10-25 bar, the slit gap is 100-1000 μm, under this condition, the viscosity of the pseudoplastic non-Newtonian fluid passing through the slit is between 100-10000 cps , The flow rate through the slit is 0.1-5 L/min, the slit with larger gap can pass through the larger agglomerated graphene sheet and separated into smaller agglomerated graphene sheet, to avoid clogging; the second dispersion processing Conditions: The pressure is increased to 15-30 bar, and the slit gap is adjusted to 10-200 μm. Under this condition, the viscosity of the pseudoplastic non-Newtonian fluid passing through the slit is between 10-1000 cps, and the flow rate through the slit is 0.5- 10 L/min. The increasing shear force can completely separate the agglomerated graphene sheets from large to small. The acceleration effect of the gradually narrowing slits can evenly disperse the graphene sheets and restore the pseudo-plastic non-Newtonian fluid with high viscosity. To maintain the dispersed state of graphene sheets.

During the mixing and dispersing process of the graphene sheet and the polymer, gas or bubbles may be retained therein. FIG. 5 is a schematic diagram of the defoaming step of the graphene dispersion method of the present invention. As shown in Figure 5, deaeration devices (such as but not limited to: centrifugal deaerators) have a heating mechanism and a rotating mechanism, which can remove the gas in the high viscosity material through heating and centrifugal force. In the degassing step S40, put the graphene dispersion paste into the degassing conditions of the gas or bubbles discharged from the centrifugal degasser: the temperature is between 30-200 degrees Celsius, the rotation speed is between 200-2000 rpm, and the increased temperature will be used The viscosity of the graphene dispersion paste drops to 10000-50000 cps, and the centrifugal force promotes the discharge of gas or bubbles, which can avoid the occurrence of holes in the graphene dispersion paste during application.

It is worth noting that the graphene dispersion paste of the present invention can maintain the dispersed state and characteristics of graphene sheets for a long time, and is easy to store and transport. The scraper fineness meter can be used to test the degree of dispersion of the composite material. The smaller the value, the higher the dispersion. The actual measured value of the graphene dispersion paste of the present invention with a scraper fineness meter is less than 20 μm (for example: 5- 15 μm), and the measured value of the graphene resin dispersed only by the public rotation machine (agglomeration may occur to a certain degree or it is easy to stack graphene sheets into graphite due to uneven dispersion), which is not less than 25 μm. In the graphene dispersion paste of the present invention, the graphene sheets are not severely agglomerated and uniformly dispersed.

The graphene dispersion paste of the present invention can be widely used in technical fields such as fiber composite materials, rubber composite materials, electrochemical element current collection layers, electrochemical element electrode material conductive additives, antistatic coatings and anticorrosion coatings.

6A, 6B and 6C are schematic diagrams of the steps of the method for using the graphene dispersion paste of the present invention. As shown in FIG. 6A, the graphene dispersion paste 1 is prepared according to the above preparation method. The graphene dispersion paste 1 includes a plurality of graphene sheets 11 and a first polymer 12, and the graphene sheets 11 are uniformly dispersed in the first polymer 12, graphite The viscosity of the ene dispersion paste 1 is not less than 50,000 cps.

As shown in Fig. 6B, the graphene dispersion paste 1 is diluted with a solvent or a second polymer compatible with the first polymer to form a graphene dispersion liquid 1'having a viscosity not greater than 5000 cps; a graphene dispersion liquid 1'is applied On the base material 100, the first polymer (or the first polymer and the second polymer) 12' that restores the fluidity of the graphene dispersion liquid 1'spreads along the surface of the base material 100, and the graphene sheet 11 is drawn and dispersed No agglomeration occurs, and the moving distance of each graphene sheet 11 parallel to the surface of the substrate 100 is proportional to its vertical distance from the surface of the substrate 100 (as shown by the dashed arrow), so that the plurality of graphene sheets 11 can be evenly distributed on the base Timber 100 surface.

As shown in FIG. 6C, the graphene dispersion liquid 1'is cured by heating or light irradiation to form a graphene polymer composite structure 10, in which the graphene sheets 11 distributed on the surface of the substrate 100 form a graphene layer 110, and the curing is high The molecular layer 120 adheres the graphene layer 110 to the surface of the substrate 100. The graphene layer 110 can greatly increase the electrical conductivity, heat dissipation, or mechanical strength of the polymer layer 120 and the substrate 100. Therefore, the graphene polymer composite structure 10 combined with the substrate 100 can produce better than the conventional graphene composite material. efficacy.

In order to specifically illustrate the various applications of the graphene dispersion paste of the present invention, those skilled in the art can more clearly understand the efficacy of the present invention, and the following will describe the practical application of the operation method in detail with exemplary embodiments.

The invention provides a graphene resin fiber composite material, comprising: a fiber cloth, a plurality of graphene sheets and a resin layer, each graphene sheet is attached to the opposite two surfaces of the fiber cloth, and the resin layer is coated on the graphene sheet. The fiber cloth may be any one or combination of carbon fiber cloth, glass fiber cloth or kevlar fiber cloth. The resin layer can be formed by heating or irradiating the resin with a polymerization reaction or a cross-linking reaction. The material of the resin layer is, for example, any one or combination of epoxy resin, phenol resin, or polyester resin. Based on the overall weight of the graphene resin fiber composite material, the resin layer accounts for 25-55 wt%, the graphene sheet accounts for 0.01-5 wt%, and the ratio of the plane lateral dimension of each graphene sheet to the diameter of the fiber is between 0.1-10 .

Example 1: Graphene resin fiber composite material

Preparation steps: Add 8 wt% graphene flakes and 92 wt% epoxy resin to a homogenizer, mix for 1 hour to form a mixture with a viscosity greater than 200,000 cps; put the mixture of graphene flakes and epoxy resin into a rotating and rotating mixer, Rotation speed 2000 rpm, revolution speed 500 rpm, continuous operation for 3 hours to form pseudoplastic non-Newtonian fluid; put pseudoplastic non-Newtonian fluid of graphene sheets and epoxy resin into the dispersing device, and set the pressure of 5 bar for the first dispersing process And a slit of 200 μm, a pseudoplastic non-Newtonian fluid flows through the slit at a flow rate of 0.5 L/min. The second dispersion process sets a pressure of 22 bar and a slit of 50 μm, and a pseudoplastic non-Newtonian fluid at 2.0 L/min The flow rate through the slit is to obtain the graphene dispersion paste; put the graphene dispersion paste into the defoaming machine, set the rotation speed to 1000 rpm, and remove the bubbles at a temperature of 60 degrees Celsius.

Pre-impregnation step: dilute the graphene dispersion paste with epoxy resin until the weight ratio of the graphene sheet is 1 wt%; add isophorone solvent to reduce the viscosity of the diluted graphene dispersion paste to about 1000 cps to form Graphene dispersion liquid; take Formosa TC12K36 carbon fiber cloth and immerse in graphene dispersion liquid; take out pre-impregnated carbon fiber cloth and leave to dry at room temperature and stand still, the weight ratio of resin contained is 42%

Molding step: stack 6 pieces of pre-impregnated carbon fiber cloth into the mold, evacuate to 160 degrees Celsius and apply 1000 Kg/cm ² pressure molding to obtain graphene resin carbon fiber composite material.

After dispersing the graphene sheet and the epoxy resin in the same ratio only through the revolution and rotation mixer in the first stage, only the prepreg step is performed to make the graphene prepreg carbon fiber cloth. Samples of resin fiber composite material without graphene, graphene resin fiber composite material made using the graphene dispersion paste of the present invention, and graphene resin pre-impregnated carbon fiber cloth dispersed only by a rotation and rotation mixer were separately cut by CNC, Test the material dispersion of the three fiber composite materials with a scraper fineness meter, and test the tensile strength, tensile modulus and bending modulus of each sample according to the test method of ASTM D3039. The measurement results are shown in Table 1.

黏度降低的環氧樹脂可帶動石墨烯片均勻分散於碳纖維的表面，固化後的環氧樹脂可將石墨烯片黏附於碳纖維表面，如表1所示，相較於對比例1-1不含石墨烯的樹脂纖維複合材料，實施例1石墨烯樹脂纖維複合材料平均可提昇15-20%的機械強度；由於對比例1-2石墨烯樹脂預浸碳纖維布中石墨烯片未均勻分散，其刮板細度明顯上升，在塗佈或預浸過程即會觀察到碳纖布塗佈表面有顯著的不平整，導致無法繼續進行後續的成型步驟。Table 1

The epoxy resin with reduced viscosity can drive the graphene sheet to be evenly dispersed on the surface of the carbon fiber, and the cured epoxy resin can adhere the graphene sheet to the surface of the carbon fiber, as shown in Table 1, compared with Comparative Example 1-1. Graphene resin fiber composite material, the graphene resin fiber composite material in Example 1 can increase the mechanical strength by 15-20% on average; since the graphene sheets in the graphene resin prepreg carbon fiber cloth of Comparative Example 1-2 are not evenly dispersed, The fineness of the squeegee increased significantly. During the coating or prepreg process, significant unevenness of the coated surface of the carbon fiber cloth was observed, which made it impossible to continue the subsequent molding steps.

The present invention provides a graphene antistatic rubber, which includes: rubber, carbon black, zinc oxide, cotton yarn, which accounts for 10-60 wt% of the whole, and graphene sheets, which accounts for 0.001-6 wt% of the whole. The diameter ratio of cotton yarn fiber is between 0.1-10. Rubber can be formed by heating or irradiating raw materials for polymerization or cross-linking reaction, such as: nitrile rubber, hydrogenated nitrile rubber, silicone rubber, fluororubber, EPDM, fluorosilicone rubber, styrene butadiene rubber , Neoprene rubber, acrylic rubber, natural rubber, chlorosulfonated polyethylene rubber, butyl rubber or polyurethane rubber, or any combination thereof.

Example 2: Graphene antistatic rubber

Preparation steps: Add 8 wt% graphene flakes and 92 wt% aromatic oil to a homogenizer, mix for 1 hour to form a mixture with a viscosity greater than 50,000 cps; put the mixture of graphene flakes and aromatic oil into an orbital rotation mixer, and the rotation speed is 2000 rpm , Revolution speed 500 rpm, continuous operation for 3 hours to form pseudoplastic non-Newtonian fluid; put pseudoplastic non-Newtonian fluid of graphene sheet and aromatic oil into the dispersing device, set the pressure of 20 bar and 200 μm narrow for the first dispersion process Slit, pseudoplastic non-Newtonian fluid flows through the slit at a flow rate of 0.5 L/min, the second dispersion process sets a pressure of 24 bar and a 50 μm slit, and pseudoplastic non-Newtonian fluid flows through the slit at a flow rate of 2.0 L/min To obtain graphene dispersion paste; put the graphene dispersion paste into the defoaming machine, set the rotation speed to 1000 rpm, and remove the bubbles at a temperature of 60 degrees Celsius.

Mixing step: dilute the viscosity of the graphene dispersion paste to 10,000 cps with aromatic oil and silicone to form a graphene dispersion; then add 100 parts by weight of neoprene, 60 parts by weight of reinforcing carbon black, and 5 parts by weight of Zinc oxide, put in a revolution and rotation mixer, rotation speed of 2000 rpm, revolution speed of 500 rpm, and continue to operate for 0.5 hours to form a raw material dispersion; dilute the raw material dispersion with aromatic oil and silicone to a viscosity of 3000 cps; finally add 15 parts by weight The cotton yarn forms antistatic rubber raw materials, of which graphene sheets account for 1-6 wt% of the whole.

Curing step: heating the antistatic rubber raw material to produce polymerization or crosslinking reaction to form graphene antistatic rubber. Due to the reduced viscosity of the antistatic rubber material, during the polymerization or cross-linking process, the binding force of the diluted rubber on the graphene sheet is reduced, the graphene sheet will gradually settle on the surface of the cotton yarn, and the electron migration network is formed by reinforcing the carbon black. This improves the conductivity of the cotton yarn, which in turn improves the antistatic properties of the rubber. The resistance test results of graphene-free rubber, graphene antistatic rubber made with different contents made according to the method of the present invention, and graphene rubber made of graphene sheets dispersed only by a homogenizer and a revolution mixer are as follows: Table 2.

如表2所示，相較於對比例2-1不含石墨烯的橡膠，實施例2-1及2-2含有石墨烯片的橡膠具有極佳的抗靜電效果；雖然對比例2-2石墨烯橡膠含有與實施例3-1石墨烯橡膠相同含量的石墨烯片，由於石墨烯片未均勻分散，導致其電阻值高於實施例2-1，而不具有如實施例2-1及2-2的抗靜電效果。Table 2

As shown in Table 2, the rubbers containing graphene sheets in Examples 2-1 and 2-2 have excellent antistatic effects compared to the rubbers containing no graphene in Comparative Example 2-1; although Comparative Example 2-2 The graphene rubber contains graphene sheets with the same content as the graphene rubber of Example 3-1. Since the graphene sheets are not uniformly dispersed, the resistance value is higher than that of Example 2-1, but does not have 2-2 Antistatic effect.

The invention provides a graphene antistatic coating, which comprises: a carrier resin, graphene sheets and additives, and the graphene sheets account for 0.01-5wt% of the whole. The carrier resin is selected from polyvinylidene fluoride, polymethyl methacrylate, polyvinyl terephthalate, polyurethane, polyethylene oxide, polyacrylonitrile, polypropylene amide, polymethyl acrylate, polymethyl methacrylate , Polyvinyl acetate, polyvinylpyrrolidone, polytetraethylene glycol diacrylate, polyimide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, ethyl cellulose, cyanoethyl cellulose, At least one of cyanoethyl polyvinyl alcohol, carboxymethyl cellulose, polyvinyl chloride, polyolefin, and silicone resin. The additive is selected from at least one of a conductive aid, a surfactant, a viscosity modulation aid, a coupling agent, and a thixotropic agent.

Example 3: Graphene antistatic coating

Preparation steps: Add 30 wt% graphene flakes and 70 wt% phthalate to a homogenizer and mix for 1 hour to form a mixture with a viscosity greater than 50,000 cps; place the mixture of graphene flakes and phthalate Into a revolution and rotation mixer, rotation speed of 2000 rpm, revolution speed of 500 rpm, continuous operation for 3 hours to form pseudoplastic non-Newtonian fluid; put pseudoplastic non-Newtonian fluid of graphene sheet and phthalate into the dispersing device, first The second dispersion process sets a pressure of 15 bar and a slit of 200 μm, and the pseudoplastic non-Newtonian fluid passes through the slit at a flow rate of 0.5 L/min. The second dispersion process sets a pressure of 22 bar and a slit of 50 μm, pseudoplastic A non-Newtonian fluid was passed through the slit at a flow rate of 2.0 L/min to obtain a graphene dispersion paste; the graphene dispersion paste was placed in a defoaming machine, the set speed was 1000 rpm, and the temperature was 60 degrees Celsius to remove air bubbles.

Mixing step: Dilute the viscosity of graphene dispersion paste to 10,000 cps with epoxy resin, phenol resin or phthalate to form a graphene dispersion liquid; mix polyvinyl chloride, epoxy resin, phenol resin, phthalate Formate, barium stearate, triphenyl phosphate, silicon dioxide and graphene dispersions form antistatic coatings, in which polyvinyl chloride, epoxy resin and phenolic resin are used as carrier resins, and phthalate is used as viscosity Regulators, barium stearate, triphenyl phosphate and silicon dioxide as adhesion enhancers.

Curing step: apply the antistatic coating to the surface of the glass substrate with a doctor blade, heat and bake the antistatic coating at 150 degrees Celsius for 30 minutes to form a graphene antistatic coating with a thickness of 30 μm, in which polyvinyl chloride 60 wt%, epoxy resin 10 wt%, phenolic resin 10 wt%, phthalate 10%, barium stearate 2 wt%, triphenyl phosphate 2.5 wt%, calcium carbonate 2wt%, silicon dioxide 2wt%, graphene sheet 1.5wt%. The diluted resin's binding force on the graphene sheet is reduced, and the graphene sheet covers the surface of the glass substrate to form an electron migration network.

Graphene-free antistatic coating, graphene antistatic coating, and graphene sheets with the same content as Example 3 were dispersed only by a homogenizer and a revolution mixer using an electrostatic measuring machine and a surface impedance testing machine The surface resistance of the graphene antistatic coating formed is shown in Table 3.

如表3所示，相較於對比例3-1不含石墨烯的抗靜電塗層，實施例3石墨烯抗靜電塗層具有極佳的抗靜電效果；雖然對比例3-2包含於實施例3相同含量的石墨烯片，由於石墨烯片分散不均，導致其電阻值高於實施例3，且透光度亦略低於實施例3。table 3

As shown in Table 3, compared to Comparative Example 3-1, an antistatic coating containing no graphene, Example 3 graphene antistatic coating has an excellent antistatic effect; although Comparative Example 3-2 is included in the implementation The graphene sheets of the same content in Example 3 have higher resistance value than that of Example 3 due to uneven dispersion of the graphene sheets, and the light transmittance is also slightly lower than that of Example 3.

The present invention provides a graphene conductive coating, comprising: graphene sheet, carrier resin and conductive filler, wherein the graphene sheet is connected to the conductive filler to form a conductive network on the substrate, the carrier resin covers the graphene sheet and the conductive filler, the graphene sheet 0.1-30 wt% of the whole, conductive filler 10-50wt% of the whole, carrier resin 10-50wt% of the whole. The base material can be insulating material or metal foil. The insulating material can be selected from any one of polyethylene terephthalate, polyimide, epoxy resin and phenolic resin. The metal foil is selected from aluminum foil, copper foil and titanium Either foil or nickel foil. The conductive filler is selected from conductive carbon black, carbon nanotubes, or a combination thereof.

Example 4: Graphene current collecting layer

Preparation steps: Add graphene flakes, conductive filler and N-methyl pyrrolidinone (NMP) to the homogenizer to form a mixed liquid of graphene flakes and conductive filler; mix the mixed liquid of graphene flakes and conductive filler and carrier resin Put in a revolution and rotation mixer, rotation speed of 1000 rpm, revolution speed of 400 rpm, and continue to operate for 1 hour to form a pseudoplastic non-Newtonian fluid with a viscosity greater than 200,000 cps; put a pseudoplastic non-Newtonian fluid of graphene sheets, conductive fillers and carrier resin into Dispersing device, the first dispersion process sets a pressure of 20 bar and a slit of 150 μm, the pseudoplastic non-Newtonian fluid passes through the slit at a flow rate of 1 L/min, and the second dispersion process sets a pressure of 24 bar and a slit of 30 μm In the slit, a pseudoplastic non-Newtonian fluid was passed through the slit at a flow rate of 2.0 L/min to obtain a graphene dispersion paste.

Dilution step: Add N-methylpyrrolidone (NMP) and graphene dispersion paste to the centrifuge, and then dilute the graphene dispersion paste to a viscosity not greater than 1000 cps through the centrifuge to form a graphene dispersion. The speed of the centrifuge is between 200 -2000 rpm.

Curing step: apply the graphene dispersion to the aluminum foil substrate, heat to volatilize N-methylpyrrolidone (NMP), and form a graphene conductive coating with a thickness of 0.1-5 μm. The diluted carrier resin reduces the binding force of the graphene sheet, the graphene sheet restores fluidity, and the conductive filler can prevent the graphene sheet from agglomerating, and can also be connected with the graphene sheet to form a conductive network.

A hundred grid test (adhesion) was performed on the graphene conductive coating with 3M model 600 and 610 tapes. The test result showed that the adhesion strength of the graphene conductive coating to the substrate was ≧4B. A four-point probe was used to measure the resistance of graphene conductive coatings with different compositions and thicknesses. Polyvinylidene fluoride (PVDF) was used as the carrier resin in Examples 4-1 to 4-5. Example 4- 6 and 4-7 use epoxy resin as the carrier resin. Comparative Examples 4-1 and 4-2 use the same ratio of graphene sheets, conductive fillers and N-methyl pyrrolidinone (NMP) as in Examples 4-5 and 4-7, and are mixed only by a homogenizer The graphene conductive coating is formed without subsequent dispersion processing, and the graphene conductive coating is coated and cured on the substrate to form a graphene current collection layer. The test results are shown in Table 4.

如表4所示，實施例4-1至4-7中石墨烯片與導電填料所形成的導電網絡具有極低的電阻，可大幅提高電流收集層的導電度，載體樹脂可增強導電網絡對基材的附著強度，且有效降低電流收集層與電極活性物質間的界面阻抗；塗佈對比例4-1及4-2石墨烯導電塗料所得到的電流收集層電阻明顯較實施例4-5及4-7高2~3倍，可知本發明之石墨烯分散膏用於建構導電網絡之優勢。Table 4

As shown in Table 4, the conductive network formed by the graphene sheets and conductive fillers in Examples 4-1 to 4-7 has extremely low resistance, which can greatly improve the conductivity of the current collecting layer, and the carrier resin can enhance the conductive network pair The adhesion strength of the substrate, and effectively reduce the interface resistance between the current collection layer and the electrode active material; the resistance of the current collection layer obtained by coating the comparative examples 4-1 and 4-2 graphene conductive coating is significantly higher than that of Example 4-5 It is 2~3 times higher than 4-7, which shows the advantages of the graphene dispersion paste of the present invention for constructing a conductive network.

FIG. 7 is a schematic diagram of the structure of a super capacitor applying the current collecting layer of the present invention. As shown in FIG. 7, the supercapacitor 7 includes: a current collecting layer 71 and an active material layer 72, wherein the composition of the current collecting layer 71 is shown in Example 4-3 in Table 4, and the thickness of the aluminum foil 711 is 15-16 μm The thickness of the graphene conductive coating 712 is 1-2 μm; the material of the active material layer 72 is activated carbon. In different current density tests, the capacitance of the current collector layer of the present invention and the conventional supercapacitor using only aluminum foil as the current collector layer was compared to compare the charge and discharge performance of the two.

FIG. 8 is a dotted line diagram of current density versus capacitance of the current collector layer applying the present invention and a conventional supercapacitor using only aluminum foil as the current collector layer. As shown in Figure 8, under the test conditions where the current density is increased from 0.5 A/g to 10 A/g, the capacitance of conventional supercapacitors is severely attenuated. When the current density exceeds 4 A/g, the capacitance is attenuated to zero ; The supercapacitor using the current collecting layer of the present invention, the current density increased from 0.5 A/g to 10 A/g under test conditions, its capacitance can maintain more than 80% of the highest value. Further test the AC impedance of the current collector layer applying the present invention and the conventional supercapacitor using only aluminum foil as the current collector layer to analyze the reason for the difference in charge and discharge performance of the two.

Figure 9 is a dotted line diagram of the capacitive reactance (Z") versus impedance (Z') of the current collector layer applying the present invention and a conventional supercapacitor using only aluminum foil as the current collector layer. As shown in Figure 11, It is known that in supercapacitors, the interface impedance between the active material layer and the current collection layer is too large, and the polarization phenomenon occurs at the interface under high current density operation, which makes it impossible to operate; in contrast, the supercapacitor using the graphene current collection layer of the present invention, graphene The interface impedance between the conductive coating and the active material layer is significantly reduced by approximately 40 times compared to the interface impedance of conventional supercapacitors. From the difference in impedance values between the two, it can be seen that the application of the graphene current collection layer of the present invention can greatly improve the supercapacitor Operating range of current density.

The invention provides a graphene electrode material, which includes graphene sheets, conductive fillers, solvents and resins. Among them, graphene sheets and conductive fillers are dispersed in the solvent, and the graphene sheets and conductive fillers are bonded by resin. %, resin accounts for 0.01-5 wt% of the whole. The conductive filler can be conductive carbon black, carbon nanotube or a combination thereof. The ratio of the particle size of the conductive filler to the thickness of the graphene sheet is between 2-1000.

Example 5: Graphene electrode material

Preparation steps: Add graphene flakes, conductive filler and N-methyl pyrrolidinone (NMP) to the homogenizer to form a mixed liquid of graphene flakes and conductive filler; mix the mixed liquid of graphene flakes and conductive filler Polyvinylidene fluoride (PVDF) is put into a revolution-rotation mixer at a rotation speed of 800 rpm and a revolution speed of 300 rpm. After continuous operation for 1 hour, a pseudoplastic non-Newtonian fluid with a viscosity greater than 200,000 cps is formed. Pseudoplastic non-Newtonian fluid of vinyl fluoride is put into the dispersing device, the pressure of 18 bar and the slit of 200 μm are set in the first dispersion process, the pseudoplastic non-Newtonian fluid passes through the slit at the flow rate of 2 L/min, and the second dispersion Processing set a pressure of 24 bar and a slit of 50 μm, and a pseudoplastic non-Newtonian fluid passed through the slit at a flow rate of 2.5 L/min to obtain a graphene dispersion paste.

Mixing steps: Add N-methylpyrrolidone (NMP) and graphene dispersion paste to the centrifuge, dilute the graphene dispersion paste to a viscosity not greater than 500 cps to form a graphene dispersion, the centrifuge speed is between 200-2000 rpm ; Use a centrifugal defoamer to uniformly mix graphene dispersion and battery active materials (lithium ion compounds, such as: nickel cobalt manganate, NCM) to form graphene electrode materials.

Curing step: coating the graphene electrode material on the substrate and heating under vacuum to evaporate N-methylpyrrolidone (NMP) in the graphene electrode material to form an electrode. Graphene electrode materials and carbon nanotube (CNT) electrode materials were used to make nickel-cobalt-manganese lithium half-cells. The battery capacity of the two was measured against the charge-discharge rate and the cycle life (at 1C rate). The measurement results are as follows Shown in Figures 10 and 11.

In this embodiment, the dispersed graphene sheet is attached to the surface of the electrode active material, and a conductive filler is connected to form a charge and discharge network of the electrode active material. The resin has the functions of dispersing the graphene sheet and bonding the charge and discharge network, as shown in the 10th As shown in FIG. 11, compared with the carbon nanotube electrode material, the graphene electrode material of the present invention can effectively improve the charge and discharge efficiency and cycle life of the electrode.

In summary, the present invention uses the fluid properties of polymers to form graphene flakes mixed with polymers to form pseudoplastic non-Newtonian fluids with a viscosity greater than 200,000 cps. Applying a pressure of 10-30 bar allows the pseudoplastic non-Newtonian fluids to pass through 10-1000 μm At least twice the slit, the viscosity of the polymer suddenly drops under the high shear force formed by the slit to evenly disperse the graphene sheet, and the polymer that restores the original viscosity through the slit can effectively prevent the graphene sheet from agglomerating , And can maintain the dispersed state of graphene sheet for a long time. When using the graphene dispersion paste of the present invention, the viscosity of the graphene dispersion paste is adjusted by adding a solvent or a compatible polymer to control the flow direction and rate of the graphene sheet, so that the graphene sheet is dispersed and attached to the surface of the material, thereby, Graphene dispersion paste can be used in technical fields such as fiber, rubber, and electrochemical, and has deep industrial applicability.

The above-mentioned embodiments merely exemplify the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this profession can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed without departing from the spirit and technical principles disclosed in this technical field should be covered by the patent application scope of this invention.

1‧‧‧Graphene dispersion paste 1'‧‧‧Graphene dispersion 7‧‧‧Supercapacitor 10‧‧‧Graphene polymer composite structure 11‧‧‧Graphene sheet 12‧‧‧The first polymer 12’‧‧‧ diluted first polymer 71‧‧‧current collection layer 72‧‧‧Active material layer 110‧‧‧Graphene layer 120‧‧‧polymer layer 100‧‧‧ Base material 711‧‧‧Aluminum foil 712‧‧‧Graphene conductive coating S10, S20, S30, S40‧‧‧ steps

Figure 1 is a flow chart of the steps of the preparation method of the graphene dispersion paste of the present invention; Figure 2 is a schematic diagram of the mixing steps of the preparation method of the graphene dispersion paste of the present invention; Figure 3 is a schematic diagram of the stirring step of the preparation method of the graphene dispersion paste of the present invention; Figure 4 is a schematic diagram of the dispersion steps of the preparation method of the graphene dispersion paste of the present invention; Figure 5 is a schematic diagram of the defoaming steps of the preparation method of the graphene dispersion paste of the present invention; Figures 6A, 6B and 6C are schematic diagrams of the steps of the method for using the graphene dispersion paste of the present invention; Figure 7 is a schematic diagram of the structure of a super capacitor applying the current collecting layer of the present invention; Figure 8 is a dotted line diagram of current density versus capacitance of the current collector layer applying the present invention and a conventional supercapacitor using only aluminum foil as the current collector layer; Figure 9 is a dotted line diagram of the capacitive reactance (Z") versus impedance (Z') of the current collector layer applying the present invention and a conventional supercapacitor using only aluminum foil as the current collector layer; Fig. 10 is a dotted line diagram of battery capacity versus charge-discharge rate of a half-cell using the graphene electrode material of the present invention and a carbon nanotube (CNT) electrode material; and Figure 11 is a dotted line diagram of battery capacity versus cycle life at 1C rate for a half-cell using the graphene electrode material of the present invention and a carbon nanotube (CNT) electrode material.

10: Graphene polymer composite structure

100: substrate

110: graphene layer

120: polymer layer

Claims (4)

A graphene polymer composite material, including a substrate, selected from any one or a combination of carbon fiber cloth, glass fiber cloth and kevlar fiber cloth, having two opposite surfaces; a plurality of graphene sheets, parallel and attached On the two surfaces of the substrate; and a polymer layer covering the graphene sheets and the two surfaces of the substrate. The graphene polymer composite material as described in item 1 of the patent application range, wherein the ratio of the plane lateral dimension of each graphene sheet to the fiber diameter of the substrate is between 0.1 and 10. The graphene polymer composite material as described in item 1 of the patent application range, wherein the material of the polymer layer is selected from any one or combination of epoxy resin, phenol resin and polyester resin. The graphene polymer composite material as described in item 1 of the patent application scope, wherein the graphene sheet accounts for 0.01 to 5 wt% and the polymer layer accounts for 25 to 55 wt% based on the overall weight of the graphene polymer composite material .

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