CN104650498A - Graphene/polymer composite conductive membrane material and preparation method thereof - Google Patents

Abstract

The invention discloses a graphene/polymer composite conductive membrane material, and belongs to the technical field of anti-electrostatic polymer composite materials. The graphene/polymer composite conductive membrane material comprises graphene and a polymer substrate, wherein the graphene forms a conductive network in the graphene/polymer composite conductive membrane material. The preparation method comprises the following steps: firstly, uniformly dispersing graphene in a solution containing a dispersing agent, thereby obtaining graphene suspension; adding polymer grains into the graphene suspension, uniformly mixing, rapidly filtering and drying, thereby obtaining a powder precursor of the composite material; finally performing hot-pressing by using a press vulcanizer, thereby obtaining the graphene/polymer composite conductive membrane material. As the two-dimensional graphene with a large ratio of thickness to radial dimension can form an electron transmission network in a composite conductive membrane, the conductivity of the composite material can be remarkably improved (the volume resistance can be reduced to be 10<3> omega grade), and a polyvinyl chloride composite membrane can be applicable to anti-electrostatic or electromagnetic shielding places.

Description

A kind of graphene/polymer composite conductive film material and preparation method thereof

technical field

The invention relates to the technical field of antistatic polymer composite materials, in particular to a graphene/polymer composite conductive film material and a preparation method thereof.

background field

With the development of modern electronics industry, information industry and high-tech, conductive polymers as functional polymer new materials have attracted great attention from scientists and entrepreneurs from all over the world. In recent years, theoretical and practical research has progressed rapidly. Polymer-based conductive composites mostly refer to multiphase composites obtained by compounding polymers and conductive materials by physical or chemical methods. Compared with the traditional conductive material metal, the polymer-based conductive composite material has the characteristics of light weight, easy processing, corrosion resistance, and the resistivity can be adjusted in a wide range, and has a wide range of uses. Polyvinyl chloride (PVC), as one of the four major engineering materials, is a widely used general-purpose plastic. Filling conductive materials (especially various carbon-based conductive fillers such as carbon black, graphite, carbon nanotubes and graphene, etc.) into polyvinyl chloride resin is a low-cost method for manufacturing permanent antistatic materials. The prepared conductive polyvinyl chloride can meet the good static dissipative properties required as packaging materials for electronic components and antistatic materials.

It is an urgent problem to develop polyvinyl chloride that meets the antistatic requirements and maintains the excellent mechanical properties of the matrix polymer.

Improving the conductivity of polyvinyl chloride polymers while maintaining their excellent mechanical properties (such as impact resistance, toughness and elongation, etc.) is the focus of research on conductive composites in recent years. Carbon-based conductive fillers currently used in the preparation of conductive polymers are usually carbon black or graphite. According to the morphology and conductive mechanism of these conductive particles, to achieve the desired conductive effect, the amount of conductive agent added is usually greater than 10%. Too much conductive agent will inevitably reduce the mechanical properties of the matrix polymer, and ultimately affect the application of conductive polymers.

Therefore, it is extremely important to study a suitable method for preparing polymer composites so that the prepared polymer composites can meet the requirements of electrical conductivity when used as packaging materials for electronic components and antistatic materials.

Contents of the invention

In order to solve the problem that the graphene existing in the preparation of graphene/polymer composite materials existing in the prior art is difficult to uniformly disperse in the polymer and form an effective conductive network, the present invention proposes a method that can give full play to the advantages of graphene's electrical conductivity. polymer composites and methods for their preparation.

For realizing the above object, technical scheme of the present invention is:

A graphene/polymer composite conductive film material, comprising graphene and a polymer matrix, the weight percentage of graphene in the composite conductive film is 0.5-5% (preferably 1.5-4%), the graphene A conductive network is formed in the composite conductive film material.

The graphene is prepared by an intercalation exfoliation method or a graphite redox method, and the size range of the graphene is 10-50 μm; the polymer matrix is polyvinyl chloride, polystyrene, polyester, polyethylene and polypropylene one or several.

The thickness of the composite conductive film is 0.1-2mm.

The volume resistance and surface resistance of the composite conductive film are at least on the order of 10 ³ Ω, the volume resistivity reaches the order of 10 ⁶ Ω·cm, and the surface resistivity reaches the order of 10 ⁶ Ω/□.

The preparation method of above-mentioned graphene/polymer composite conductive thin film material is: at first graphene is uniformly dispersed in the aqueous solution containing surfactant, forms the suspension of graphene, then the granular polymer is dispersed in the suspension of graphene In the process, the composite powder of the graphene-coated polymer is obtained by filtering and drying in sequence, and then the composite powder is hot-pressed to obtain the graphene/polymer composite conductive film material. The method specifically includes the following steps:

(1) Preparation of graphene suspension: first, add the surfactant to deionized water according to the weight ratio of surfactant: water = 0.1-3%, to obtain an aqueous solution containing surfactant, and then add it under stirring conditions Graphene, the amount of graphene added per milliliter of surfactant-containing aqueous solution is 1-10 mg, stirred for 1 hour and then ultrasonically treated for 30-60 minutes to obtain a suspension of graphene;

(2) Adding the granular polymer into the graphene suspension obtained in step (1) under stirring conditions according to the required amount, ultrasonication for 1 hour, and then rapid stirring for more than 6 hours to obtain a graphene/polymer suspension;

(3) Vacuum filter the graphene/polymer suspension obtained in step (2), and then dry it at 100°C to obtain a graphene-coated polymer composite powder; Suction filtration and drying can avoid graphene agglomeration and realize graphene coating on polymer particles.

(4) Press the graphene-coated polymer composite powder with a flat vulcanizer at a temperature of 160-200°C and a pressure of 2-4MPa for 6-10 minutes to make a graphene/polymer composite conductive film.

The surfactant is polyvinylpyrrolidone, polyvinyl alcohol, silane coupling agent or titanate coupling agent and the like.

The granular polymer is plasticized before use, and the treatment process is: weigh a certain amount of granular polymer, and add dioctyl phthalate to increase the weight ratio of the polymer to the plasticizer at 100:60. The plasticizer is stirred evenly and treated at 80° C. for 1 hour to obtain a plasticized polymer.

Design principle of the present invention is as follows:

Graphene, a rising star among carbon-based conductive materials, has an extremely high electron mobility of 2×10 ⁵ cm ² v ^-1 s ^-1 at room temperature and a high aspect ratio (about greater than 5000) due to its excellent electrical conductivity, making it When the weight percentage is less than 3% in the matrix polymer, the volume resistivity can be reduced to below the order of 10 ⁶ Ω·cm, which meets the antistatic requirements. Due to the small amount of graphene added and the shape of graphene, there is almost no damage to the mechanical properties of the matrix polymer, and even a certain degree of enhancement. Compared with other conductive agents, graphene has the following significant advantages:

(1) Graphene has excellent electrical conductivity, with an electron mobility as high as 2×10 ⁵ cm ² v ^-1 s ^-1 , which is about two times higher than that of indium antimonide, the material with the highest carrier mobility known so far. At the same time, the resistance value of graphene at room temperature is only two-thirds of that of copper. These properties show that graphene is currently the most excellent conductive material.

(2) Graphene has a very high aspect ratio (up to 5000 or more). The two-dimensional planar structure of graphene makes it easier to form a conductive network in the matrix than zero-dimensional or one-dimensional conductive materials, so the amount of conductive agent can be greatly reduced.

(3) Graphene has a large specific surface area, the theoretical value is as high as 2600m ² /g. Such a high specific surface area of graphene can help improve its interaction with the matrix polymer and enhance the interfacial binding energy.

(4) Graphene has excellent mechanical properties. The ideal tensile strength of graphene is 42N/m, which is about 100 times that of ordinary steel. The Young's modulus is 1100GPa and the fracture strength is 125GPa. When an appropriate amount of graphene is added to the polymer, the graphene will not only improve the electrical conductivity of the polymer, but also improve its mechanical properties to a certain extent.

The present invention proposes a new composite method of graphene and polymer, that is, graphene is first dispersed in an aqueous solution, and then polymer particles are dispersed in the above solution, and a uniform mixture is obtained after sufficient ultrasonication and stirring. The suspension solution is rapidly vacuum filtered and dried to obtain a graphene-coated polymer composite. The composite was observed by a scanning electron microscope and found that the graphene was uniformly coated on the outer surface of the polymer particles, which proved that the graphene was uniformly dispersed in the polymer resin, which laid the foundation for the graphene to form a conductive network in the matrix resin. The above-mentioned graphene-coated polymer composite is hot-pressed to obtain a composite conductive film with a volume resistivity of the order of 10 ⁶ Ω·cm and a surface resistivity of the order of 10 ⁶ Ω/□, which can meet the antistatic requirements. In this method, water is selected as the solvent for dispersing graphene, which can effectively avoid environmental pollution caused by the use of organic solvents, so it can be considered as an environmentally friendly method. The process of the method is simple and easy, and is suitable for industrial scale production.

In the present invention, it is found that the scale of graphene has a great influence on the electrical conductivity of the obtained composite material, so the size range of graphene used in the present invention is 10-50 μm. This kind of graphene is easy to disperse, and it is easy to form a coating layer on the spherical PVC surface, which is conducive to the formation of an effective conductive network. Only when an effective conductive network is formed, can the obtained composite material have good conductivity and meet the graphene /PVC composite film requirements for antistatic or electromagnetic shielding.

The advantages of the present invention are as follows:

1. In the present invention, an appropriate amount of graphene is added to the polymer material by a specific method and uniformly dispersed. Since the two-dimensional graphene with a large thickness-to-diameter ratio can form an electron transport network in a composite conductive film, it can significantly The conductivity of the composite material is improved (volume resistance is reduced to the order of 10 ³ Ω), which meets the conductivity requirements of the polymer composite material used as packaging materials for electronic components, antistatic materials and electromagnetic shielding.

2. The graphene/polymer composite film material prepared by the present invention has good electrical conductivity, the lowest volume (surface) resistance can reach the order of 10 ³ Ω, and the volume resistivity can reach the order of 10 ⁶ Ω·cm; the surface resistivity It can reach the order of 10 ⁶ Ω/□.

3. The selected solvent is water when the graphene dispersion suspension is prepared by the present invention. Water is environmentally friendly and is a cheap raw material, and the water can be recycled, so there is no environmental pollution problem.

4. The process of preparing graphene/polyvinyl chloride composite film by the present invention is simple, the production efficiency is high, and it is easy to realize industrial scale production.

Description of drawings

Fig. 1 is the scanning electron micrograph of embodiment 1 graphene/polyvinyl chloride composite powder.

Fig. 2 is the scanning electron micrograph of embodiment 2 graphene/polyvinyl chloride composite powder.

Fig. 3 is the scanning electron micrograph of the cross section of embodiment 1 graphene/polyvinyl chloride composite film.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1

A graphene/PVC composite conductive film material is prepared, and the content of graphene in the composite conductive film material is 1.0wt%.

First, plasticize granular polyvinyl chloride (PVC): add 30 grams of dioctyl phthalate to 50 grams of PVC resin, stir evenly, and then mature at 80°C for 1 hour to obtain plasticized granular PVC. 0.75 g of graphene (GNS) was added to 100 ml of 2wt% polypyrrolidone (PVP) aqueous solution, followed by stirring for 1 h and ultrasonic treatment for 30 min to obtain a uniformly dispersed suspension of GNS. Add 78.8 g of plasticized PVC to the GNS suspension, ultrasonically disperse for 1 hour, stir for 10 hours, then vacuum filter and dry at 100°C to obtain PVC/GNS composite black gray powder.

Figure 1 is a scanning electron microscope photo of the graphene/polyvinyl chloride composite powder obtained after drying. It can be seen from the figure that graphene is evenly coated on the polyvinyl chloride particles, and the two have achieved a perfect combination. Lays the groundwork for forming the conductive network in the composite film.

Take an appropriate amount of the powder and put it on a hydraulic press at 160°C and 2MPa pressure for 10 minutes to obtain a graphene/PVC composite conductive film material. Figure 3 is a cross-sectional scanning electron microscope photo of the composite film. It can be seen from the photo that the graphene has been Constructing a conductive network in the film can ensure that the composite film has certain conductivity. After testing, the volume resistance of the conductive film is 6700Ω, the volume resistivity is 3.7×10 ⁶ Ω·cm; the surface resistance is 2.9×10 ⁴ Ω, and the surface resistivity is 1.3×10 ⁷ Ω/□.

Example 2

A graphene/PVC composite conductive film material is prepared, and the content of graphene in the composite conductive film material is 1.25wt%.

First, the granular polyvinyl chloride (PVC) is plasticized: the process is the same as in Example 1. 1 gram of graphene (GNS) was added to 100 ml of 2wt% polypyrrolidone (PVP) aqueous solution, followed by stirring for 1 h and ultrasonic treatment for 50 min to obtain a uniformly dispersed suspension of GNS. Add 78.4 g of plasticized PVC to the GNS suspension, ultrasonically disperse for 1 hour, stir for 10 hours, then vacuum filter and dry at 100°C to obtain PVC/GNS composite black gray powder.

Figure 2 is a scanning electron microscope photo of the graphene/polyvinyl chloride composite powder obtained after drying. It can be seen that graphene is evenly coated on the polyvinyl chloride particles, and the two have achieved a perfect combination, which is the next step in the composite film. Form the foundation of the conductive network.

Take an appropriate amount of the powder and put it on a hydraulic press at 160°C and 2MPa pressure for 10 minutes to obtain a composite conductive film. The volume resistance of the conductive film is 4000Ω, and the volume resistivity is 1.7×10 ⁶ Ω·cm; the surface resistance is 3200Ω, and the surface resistivity 1.4×10 ⁶ Ω/□.

Example 3

A graphene/PVC composite conductive film material is prepared, and the content of graphene in the composite conductive film material is 2.5wt%.

The method for preparing DOP plasticized PVC resin is the same as in Example 1. 2 g of graphene (GNS) was added to 200 ml of 2wt% polypyrrolidone (PVP) aqueous solution, followed by stirring for 1 h and ultrasonic treatment for 1 h to obtain a uniformly dispersed suspension of GNS. Add 76.8 g of plasticized PVC to the GNS suspension, ultrasonically disperse for 1 hour, stir for 10 hours, then vacuum filter and dry at 100°C to obtain PVC/GNS composite black gray powder. Take an appropriate amount of the powder and put it on a hydraulic press at 160°C for 10 minutes under a pressure of 2 MPa to obtain a composite conductive film. The volume resistance of the conductive film is 3830Ω, and the volume resistivity is 1.65×10 ⁶ Ω·cm; the surface resistance is 2200Ω, and the surface resistivity 1.15×10 ⁶ Ω/□.

Example 4

A graphene/PE composite conductive film material is prepared, and the content of graphene in the composite conductive film material is 2.5wt%.

2 grams of graphene (GNS) was added to 200 ml of 2wt% polypyrrolidone (PVP) aqueous solution, followed by stirring for 1 h and ultrasonic treatment for 50 min to obtain a uniformly dispersed suspension of GNS. Add 78 grams of PE to the above GNS suspension, ultrasonically disperse for 1 hour, stir for 10 hours, then vacuum filter and dry at 100°C to obtain PE/GNS composite black gray powder.

Take an appropriate amount of the powder and put it on a hydraulic press at 160°C and 2MPa pressure for 10 minutes to obtain a composite conductive film. The volume resistance of the conductive film is 3500Ω, and the volume resistivity is 1.5×10 ⁶ Ω·cm; the surface resistance is 4000Ω, and the surface resistivity 1.75×10 ⁶ Ω/□.

Example 5

A graphene/polypropylene composite conductive film material is prepared, and the content of graphene in the composite conductive film material is 2wt%.

1 gram of graphene (GNS) was added to 100 ml of 2wt% polypyrrolidone (PVP) aqueous solution, followed by stirring for 1 h and ultrasonic treatment for 50 min to obtain a uniformly dispersed suspension of GNS. Add 49 grams of polypropylene to the GNS suspension, ultrasonically disperse for 1 hour, stir for 10 hours, then vacuum filter and dry at 100°C to obtain PVC/GNS composite black gray powder.

Take an appropriate amount of the powder and put it on a hydraulic press at 150°C for 10 minutes under a pressure of 2 MPa to obtain a composite conductive film. The volume resistance of the conductive film is 8000Ω, and the volume resistivity is 3.4×10 ⁶ Ω·cm; the surface resistance is 9000Ω, and the surface resistivity 3.5×10 ⁶ Ω/□.

Comparative example 1

Preparation of graphene-free PVC film. The method for preparing DOP plasticized PVC resin is the same as in Example 1. Take an appropriate amount of DOP plasticized PVC powder and put it on a hydraulic press at 160°C and 2MPa pressure for 10 minutes to obtain a composite conductive film. The volume resistance of the conductive film is 5.8×10 ⁹ Ω, and the volume resistivity is 2.3×10 ¹² Ω·cm ; The surface resistance is 4.2×10 ¹² Ω, and the surface resistivity is 1.8×10 ¹² Ω/□.

Comparative example 2

Change the pressure to prepare a conductive composite film in which the weight of graphene in PVC is 2wt%. The method for preparing DOP plasticized PVC resin is the same as in Example 1. The method for preparing GNS/PVC composite powder is the same as that in Example 2. Take an appropriate amount of GNS/PVC composite powder and put it on a hydraulic press at 160°C and 20MPa pressure for 10 minutes to obtain a composite conductive film. The volume resistance of the conductive film is 4.79×10 ⁸ Ω, and the volume resistivity is 2.8×10 ¹⁰ Ω·cm; The surface resistance is 5.35×10 ⁸ Ω, and the surface resistivity is 6.78×10 ¹¹ Ω/□.

Claims (10)

1. Graphene/polymkeric substance composite conductive thin film material, it is characterized in that: described composite conductive thin film material comprises Graphene and polymeric matrix, the weight percentage of Graphene in composite conductive thin film is 0.5-5%, and described Graphene forms conductive network in composite conductive thin film material.

2. Graphene according to claim 1/polymkeric substance composite conductive thin film material, is characterized in that: the weight percentage of described Graphene in composite conductive thin film is 1.5-4%.

3. Graphene according to claim 1/polymkeric substance composite conductive thin film material, is characterized in that: described Graphene is by intercalation stripping method or the preparation of graphite oxidation reduction method, and the size range of Graphene is 10-50 μm.

4. Graphene according to claim 1/polymkeric substance composite conductive thin film material, is characterized in that: described polymeric matrix is one or more in polyvinyl chloride, polystyrene, polyester, polyethylene and polypropylene.

5. Graphene according to claim 1/polymkeric substance composite conductive thin film material, is characterized in that: the thickness of described composite conductive thin film is 0.1-2mm.

6. Graphene according to claim 1/polymkeric substance composite conductive thin film material, is characterized in that: the volume resistance of described composite conductive thin film and surface resistivity minimum be 10 ³the Ω order of magnitude, volume specific resistance reaches 10 ⁶the Ω cm order of magnitude, surface resistivity reaches 10 ⁶Ω/ order of magnitude.

7. the preparation method of Graphene according to claim 1/polymkeric substance composite conductive thin film material, it is characterized in that: first graphene uniform is dispersed in the aqueous solution containing tensio-active agent by the method, form the suspension of Graphene, then granulated polymer is distributed in the suspension of Graphene, obtain the composite powder of graphene coated polymkeric substance successively after filtration with drying, then this composite powder is obtained Graphene/polymkeric substance composite conductive thin film material through hot pressing.

8. the preparation method of Graphene according to claim 7/polymkeric substance composite conductive thin film material, is characterized in that: the method specifically comprises the following steps:

(1) preparation of the suspension of Graphene: first by tensio-active agent according to tensio-active agent: the part by weight of water=0.1-3% joins in deionized water, obtain the aqueous solution containing tensio-active agent, then Graphene is added under agitation, every milliliter is 1-10mg containing the add-on of Graphene in the aqueous solution of tensio-active agent, to stir after 1 hour supersound process 30-60 minute again, obtain the suspension of Graphene;

(2) joined under agitation by granulated polymer in the desired amount in the suspension of step (1) gained Graphene, rapid stirring more than 6 hours again after ultrasonic 1 hour, obtains Graphene/polymer slurry;

(3) step (2) gained Graphene/polymer slurry is carried out vacuum filtration, then under 100 DEG C of conditions, after drying, obtain the composite powder of graphene coated polymkeric substance;

(4) adopt vulcanizing press at 160-200 DEG C of temperature and 2-4MPa pressure 6-10 minute the composite powder of graphene coated polymkeric substance, make Graphene/polymkeric substance composite conductive thin film.

9. the preparation method of the Graphene according to claim 7 or 8/polymkeric substance composite conductive thin film material, is characterized in that: described tensio-active agent is polyvinylpyrrolidone, polyvinyl alcohol, silane coupling agent or titanate coupling agent.

10. the preparation method of the Graphene according to claim 7 or 8/polymkeric substance composite conductive thin film material, it is characterized in that: described granulated polymer is before use through plastics processing, treating processes is: weigh a certain amount of granulated polymer, be that 100:60 adds dioctyl phthalate (DOP) softening agent by polymkeric substance and softening agent weight ratio, under 80 DEG C of conditions, process 1 hour after stirring, obtain the polymkeric substance plastified.