Preparation method and application of high-content graphene phenolic resin dispersion

Abstract

The invention belongs to the technical field of preparation of carbon material dispersoid materials, and particularly relates to a preparation method of a high-content graphene-phenolic resin dispersoid. According to the high-content graphene-phenolic resin dispersion, graphene is graphene powder or a graphene pre-dispersion liquid; the preparation method comprises the following steps: pre-mixing graphene powder or graphene pre-dispersion liquid with phenolic resin for multiple times, and obtaining a premix when the viscosity of a system reaches a preset value; grinding the premix by a three-roller machine for multiple times to obtain a ground material; and further kneading and shearing the ground material to obtain the high-content graphene-phenolic resin dispersion. The uniformly dispersed high-content graphene-phenolic resin dispersoid is prepared by adopting a physical method, so that the stable dispersion of the graphene in the phenolic resin is ensured to the greatest extent, the reaction process is mild and easy to control, and the automation degree is high. By adding the graphene, the electrical conductivity, the thermal conductivity and the corresponding mechanical toughness of the phenolic resin can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon material dispersion material preparation, and specifically relates to a high-content graphene-phenolic dispersion and a preparation method thereof. Background Art

[0002] Phenolic resin is a large class of synthetic resins made by polycondensation of phenolic compounds and aldehyde compounds. Phenolic resin has good acid resistance, mechanical properties, and heat resistance, and is widely used in aerospace, electronic materials, refractory materials, friction materials, thermal insulation materials, impregnation materials, coated abrasives, tire rubber, electrical materials, carbon materials, new energy and other fields. Graphene has the advantages of high conductivity, high thermal conductivity, high strength, ultra-lightness, high flexibility, high chemical stability and high specific surface area, and has important potential application prospects in many fields. With the continuous development of preparation technology, the number of layers of mass-produced graphene is getting smaller and smaller, and the performance is getting better and better. Due to its excellent performance, it is added to various materials as a functional additive to improve material properties, such as adding it to battery electrode materials to enhance conductivity, adding it to thermosetting polymer materials to be used for lightweight plastic-steel materials, and adding it to coatings and inks to enhance anti-corrosion and antistatic properties. Adding graphene to phenolic resin can significantly improve the mechanical properties of phenolic resin, such as poor toughness and low impact strength; at the same time, it can also further help to reduce the weight of the material and further improve the fire resistance and wear resistance of phenolic resin.

[0003] There are two main common methods for introducing graphene into phenolic resin. One is a chemical method, i.e., in-situ polymerization method. Graphene oxide, expanded graphite, etc. are usually added in the early stage of phenolic resin synthesis, and then a graphene phenolic resin composite material is obtained by polycondensation reaction. The preparation process of the graphene phenolic resin composite material is complicated, and graphene oxide needs to consume additional reducing agent during the reaction. CN104403264A discloses a preparation method of a graphene phenolic resin, wherein graphene oxide is dispersed in an aldehyde solution using a suitable dispersant, and a graphene phenolic resin composite material is synthesized in situ. The preparation process involves a multi-step heating reaction, and the pH needs to be regulated throughout the process, and the phenol content is monitored to control the reaction end point, and the operation steps are many and complicated. Another method is a physical method, in which graphene is physically mixed into a phenolic tree. The method is simple and efficient, but due to the low density of graphene powder, it is not easy to feed, and there are great defects in dispersibility, and the ideal mixing effect cannot be achieved.

[0004] In summary, the use of a simple physical method to prepare a graphene phenolic resin dispersion with good dispersion effect not only expands the application field of phenolic resin, but also improves the added value of the product. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a high-content graphene-phenolic resin dispersion. After adding graphene powder or pre-dispersed liquid into phenolic resin, a uniformly dispersed graphene phenolic resin dispersion is prepared by physical mixing. The method is simple and has a good dispersion effect. Graphene is filled into the phenolic resin as a filling material, thereby improving the conductivity and mechanical properties of the phenolic resin.

[0006] The present invention provides a method for preparing a high-content graphene-phenolic resin dispersion, and the graphene-phenolic resin dispersion comprises graphene and phenolic resin;

[0007] Wherein, the graphene is graphene powder or graphene pre-dispersed liquid;

[0008] The preparation method comprises the following steps:

[0009] Premixing graphene powder or graphene pre-dispersion liquid with phenolic resin in multiple times, and obtaining a premix when the viscosity of the system reaches a preset value;

[0010] Grinding the premixed material several times with a three-roll mill to obtain a grind material;

[0011] The ground material is further kneaded and sheared to obtain a high-content graphene-phenolic resin dispersion.

[0012] Furthermore, in the graphene powder or graphene pre-dispersion liquid, the graphene powder is one or a mixture of graphene prepared by a physical method or graphene prepared by a chemical method.

[0013] Furthermore, in the graphene powder or graphene pre-dispersion liquid, the particle size of graphene is 0.1 to 100 μm.

[0014] Furthermore, in the graphene powder or graphene pre-dispersion liquid, the number of graphene layers is 2 to 10.

[0015] Furthermore, the graphene pre-dispersion liquid is a uniformly dispersed solution obtained by pre-dispersing graphene powder, and includes graphene, a dispersant and a solvent.

[0016] Furthermore, the dispersant is any one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, sodium lignin sulfonate, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polymethacrylic acid or polyacrylamide.

[0017] Furthermore, the amount of the dispersant added is 0.1 to 10% of the graphene.

[0018] Furthermore, the solvent is one or more of ethanol, ethylene glycol, isopropanol, butanol, ethyl acetate, and butanone.

[0019] Furthermore, in the graphene pre-dispersion liquid, the content of graphene is 10 to 60 wt %.

[0020] Furthermore, the phenolic resin is solid phenolic resin or liquid phenolic resin, or a combination of both.

[0021] Furthermore, the liquid phenolic resin is a thermoplastic liquid phenolic resin or a thermosetting liquid phenolic resin.

[0022] Furthermore, the solid content of the liquid phenolic resin is 70-80 wt %.

[0023] Furthermore, the viscosity of the liquid phenolic resin is 1000 to 30000 mPa.s.

[0024] Furthermore, the softening point of the solid phenolic resin is 70-140°C.

[0025] Furthermore, the flow rate of the solid phenolic resin is 20 to 50 mm.

[0026] Furthermore, the premixing method is to add the graphene powder or graphene pre-dispersion liquid into the phenolic resin in 2 to 8 times.

[0027] Furthermore, the premixing method is mechanical stirring, the stirring speed is 300 to 1500 r / min, and the stirring time is 5 to 30 min.

[0028] Furthermore, the premix is ​​one or more of a paste of graphene powder and liquid phenolic resin, a paste of graphene pre-dispersion liquid and liquid phenolic resin, a paste obtained by heating and mixing graphene powder and phenolic resin powder, and a paste of graphene pre-dispersion liquid and phenolic resin powder.

[0029] Further, the content of graphene in the dispersion is 5 to 50%. Further, the content of graphene in the dispersion is 10 to 40%.

[0030] Furthermore, the preset value of the premix viscosity is 1000-50000·mPa . s.

[0031] Furthermore, the grinding material is a premix added to a three-roll mill, and the roller spacing of the three-roll mill is adjusted according to the size of the graphene, and the preferred spacing range is 5 to 100 μm.

[0032] Furthermore, the premix is ​​ground by a three-roll mill 1 to 20 times.

[0033] Furthermore, the processing method is selected according to the content of graphene in the kneaded material.

[0034] Furthermore, a kneader is selected for shear mixing of the grinding material with a graphene addition amount of 5 to 25 wt%, and an internal mixer is selected for shear mixing of the grinding material with a graphene addition amount of 25 to 50 wt% to obtain a high-content graphene-phenolic resin dispersion.

[0035] The present invention provides the use of the above-mentioned high-content graphene-phenolic resin dispersion in composite masterbatch and coating agent of lithium battery material. The present invention has no special restrictions on the method of preparing composite masterbatch and coating agent of lithium battery material from high-content graphene-phenolic resin dispersion, and the steps or methods conventionally used by those skilled in the art to achieve the above-mentioned operation can be adopted, and appropriate adjustments can be made to the existing conventional methods according to actual conditions, and no special restrictions are imposed on this.

[0036] The graphene phenolic resin dispersion prepared by physical method can be applied to the fields of negative electrode material coating, plastic lightweighting, refractory materials, coatings, inks, etc. according to the type of graphene content and the type of phenolic resin.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The method of the present invention is to add graphene to phenolic resin in multiple times, reduce the van der Waals force between graphenes by adding a dispersant, improve the compatibility with high molecular polymers, ensure that the phenolic resin is fully infiltrated with graphene by adding multiple times, and ensure the stable dispersion of graphene in phenolic resin to the greatest extent through three-roll grinding, stirring and kneading, and twin-screw extrusion. The reaction process is mild and easy to control, and the degree of automation is high.

[0039] (2) The addition of large-diameter graphene by physical methods can improve the electrical conductivity, thermal conductivity and corresponding mechanical toughness of phenolic resin, which is conducive to the further application of phenolic resin in the field of plastic coatings and increases the added value of phenolic resin.

[0040] (3) The method of the present invention has a simple preparation process, easy-to-control reaction conditions, safe and controllable product composition, is conducive to large-scale production, and has broad application prospects. DETAILED DESCRIPTION

[0041] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0043] This specific embodiment provides a graphene phenolic resin dispersion and a preparation method thereof. The method comprises the following steps: adding graphene powder or solution to phenolic resin, and then adopting a physical mixing method to prepare a uniformly dispersed graphene phenolic resin dispersion. The method is simple and has a good dispersion effect. Graphene is filled into the phenolic resin as a filling material, which improves the conductivity and mechanical properties of the phenolic resin and expands the application field of the phenolic resin material.

[0044] In view of the above problems, an embodiment of the present invention provides a method for preparing a graphene phenolic resin dispersion, wherein the graphene phenolic resin dispersion comprises graphene and phenolic resin;

[0045] Wherein, the graphene is graphene powder or graphene pre-dispersed liquid;

[0046] The preparation method comprises the following steps:

[0047] S1, premixing the graphene powder or graphene pre-dispersion liquid with the phenolic resin in multiple times, and obtaining a premix when the viscosity of the system reaches a preset value;

[0048] S2, grinding the premix several times with a three-roll mill to obtain a grind;

[0049] S3. The ground material is further kneaded and sheared to obtain a high-content graphene-phenolic resin dispersion.

[0050] It can be understood that the method provided in this specific embodiment can ensure the uniform distribution of graphene in the phenolic resin, and the uniform dispersion helps to avoid the agglomeration of graphene, thereby ensuring the consistency of the mechanical properties and conductivity of the material; during the mixing and grinding process, by controlling the viscosity, appropriate shear force can be applied to break larger graphene particles into smaller flakes, which can increase the interfacial interaction between graphene and phenolic resin, thereby enhancing the mechanical strength and other properties of the material; by effectively controlling the viscosity, graphene can be better embedded in the phenolic resin matrix to form a close interface bond, which helps to improve the overall strength and durability of the dispersion.

[0051] In some preferred embodiments, the particle size of graphene in the graphene powder or pre-dispersion is 0.1 to 100 μm, for example, 1, 3, 5, 10, 20, 50, 80 or 100 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] In some preferred embodiments, the number of graphene layers in the graphene powder or pre-dispersion liquid is 2 to 10 layers; for example, 3, 5, 8, 10 layers, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] In some preferred embodiments, the graphene pre-dispersion liquid includes graphene, a dispersant and a solvent.

[0054] It is understood that the dispersant can effectively reduce the interaction between graphene sheets and prevent graphene from agglomerating in the solution. By dispersing in a solvent, graphene can maintain a uniform distribution, thereby ensuring its uniformity in the matrix material during subsequent processing, and the dispersant can form a protective film on the graphene surface to improve the interface compatibility between graphene and matrix materials such as phenolic resin. This can enhance the bonding force between graphene and the matrix and improve the mechanical properties and durability of the composite material.

[0055] In some preferred embodiments, the preset value is 1000-50000 mPa.s; for example, 2500 mPa.s, 5000 mPa.s, 9000 mPa.s, 12000 mPa.s, 15000 mPa.s, 24000 mPa.s or 30000 mPa.s, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] It can be understood that the viscosity in the range of 1000 to 50000 mPa.s is conducive to the full dispersion of graphene and phenolic resin during the pre-mixing process, the lower viscosity is conducive to the initial dispersion of graphene in the matrix, and the higher viscosity is conducive to stabilizing the already dispersed graphene particles and avoiding agglomeration.

[0057] In some preferred embodiments, the dispersant is any one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, sodium lignin sulfonate, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polymethacrylic acid or polyacrylamide.

[0058] It is understandable that the addition of the above dispersant can achieve surface functionalization of graphene, reduce the van der Waals force between molecules, make the dispersion of few-layer graphene easier, and improve the compatibility with the polymer, thereby preparing a uniformly dispersed graphene-polymer composite material.

[0059] In some preferred embodiments, the amount of dispersant added is 0 to 10% of the graphene, such as 0.5wt%, 2wt%, 4.5wt%, 7wt%, 8wt%, 9wt% or 10wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some preferred embodiments, the graphene content in the graphene pre-dispersion liquid is 10-60wt%, such as 10wt%, 12wt%, 15wt%, 20wt%, 40wt% or 60wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable. The high-content graphene pre-dispersion liquid is obtained by partial pressure filtration of the solution.

[0061] In some preferred embodiments, the phenolic resin is a liquid phenolic resin with a viscosity of 1000 to 30000 mPa.s; for example, 2500 mPa.s, 5000 mPa.s, 9000 mPa.s, 12000 mPa.s, 15000 mPa.s, 24000 mPa.s or 30000 mPa.s, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0062] In some preferred embodiments, the phenolic resin is a solid phenolic resin with a softening point of 70 to 140°C; for example, 72°C, 78°C, 80°C, 95°C, 110°C, 115°C or 140°C, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0063] In some preferred embodiments, the thermoplastic solid phenolic resin is in powder form and has a flow rate of 20 to 50 mm, such as 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm or 50 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0064] In some preferred embodiments, graphene powder or graphene pre-dispersion liquid is added to phenolic resin in 2 to 8 times, and mechanical stirring is performed at a stirring speed of 300 to 1500 r / min and a stirring time of 5 to 30 min to obtain a premix.

[0065] In some preferred embodiments, step S2 adds the premix to a three-roll mill, and adjusts the roller spacing of the three-roll mill according to the size of the graphene. The preferred spacing range is 5 to 100 μm, for example 5, 10, 20, 40, 80 or 100 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0066] In some preferred embodiments, the number of times of grinding by the three-roll mill in step S2 is 1 to 20 times, for example 5, 10, 15 or 20 times, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0067] In some preferred embodiments, in step S2, the ground material is added to a kneader or internal mixer and vacuumed to remove bubbles generated during the premixing process, and the kneaded material is obtained after further shear mixing.

[0068] In some preferred embodiments, in step S3, when the graphene addition amount is 0 to 30 wt%, a kneader is selected for shear mixing, and when the graphene addition amount is 30 to 60 wt%, an internal mixer is selected for shear mixing to obtain a high-content graphene-phenolic resin dispersion.

[0069] Example 1

[0070] This embodiment provides a method for preparing a graphene phenolic resin dispersion, comprising the following steps:

[0071] S1, 50g of graphene powder prepared by physical method with a particle size of 3μm and 3 to 5 layers, and 50g of graphene powder prepared by chemical method with a particle size of 8-12μm and 8 to 10 layers, were added to 500g of thermoplastic liquid phenolic resin with a solid content of 75% and a viscosity of 2500mPa.s in 5 times, 20g / time, and stirred at a speed of 1000r / min for 30min to obtain a paste-like premix with a viscosity of 9432mPa.s;

[0072] S2, the obtained premix is ​​passed through a three-roll mill with rollers at 40 μm, 20 μm, 10 μm and 5 μm for 3 times, with a speed of 200 r / min, and the ground material is obtained after multiple grinding;

[0073] S3. Put the obtained 16.7 wt% graphene grinding material into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 70° C. and 40 r / min for 20 min to obtain a 16.7 wt% graphene-phenolic resin dispersion.

[0074] Example 2

[0075] This embodiment provides a graphene phenolic resin dispersion and a preparation method thereof, comprising the following steps:

[0076] S1. 56 g of graphene powder prepared by physical method with a particle size of 6 μm and 8 to 10 layers was added to 500 g of thermoplastic liquid phenolic resin with a solid content of 80% and a viscosity of 8000 mPa.s in 5 times of 10 g / time, and stirred at a speed of 800 r / min for 30 min to obtain a paste-like premix with a viscosity of 12000 mPa.s.

[0077] S2, the obtained premix is ​​passed through a three-roll mill with rollers at 20 μm, 15 μm and 5 μm for 5 times, with a speed of 200 r / min, and the ground material is obtained after multiple grinding;

[0078] S3. Put the obtained 10.1 wt% graphene grind material into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 90° C. and 30 r / min for 30 min to obtain a 10.1 wt% graphene-phenolic resin dispersion.

[0079] Example 3

[0080] This embodiment provides a graphene phenolic resin dispersion and a preparation method thereof, comprising the following steps:

[0081] S1. 100 g of graphene powder prepared by a chemical method with a particle size of 3 to 5 μm and 2 to 5 layers was added to 500 g of a thermoplastic liquid phenolic resin with a solid content of 75% and a viscosity of 2500 mPa.s in 5 times of 20 g / time, and stirred at a speed of 1000 r / min for 30 min to obtain a paste-like premix with a viscosity of 1163 mPa.s.

[0082] S2, the obtained premix is ​​passed through a three-roll mill with rollers at 40 μm, 20 μm, 10 μm and 5 μm for 3 times, with a speed of 200 r / min, and the ground material is obtained after multiple grinding;

[0083] S3. Put the obtained 16.7 wt% graphene grinding material into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 70° C. and 40 r / min for 20 min to obtain a 16.7 wt% graphene-phenolic resin dispersion.

[0084] Example 4

[0085] This embodiment uses graphene pre-dispersion liquid as a raw material. The preparation method of the graphene pre-dispersion liquid used in this embodiment is as follows: 100g of graphene powder prepared by a chemical method with a particle size of 3-5μm and 2-5 layers is dispersed in 500g of ethanol solution added with 3g of sodium dodecylbenzene sulfonate, stirred for 15min and then ultrasonicated for 15min to obtain the graphene pre-dispersion liquid.

[0086] The present embodiment provides a graphene phenolic resin dispersion and a preparation method thereof, comprising the following steps:

[0087] S1, the pre-dispersed liquid is filtered to obtain a pre-dispersed liquid with a content of 40wt%, the pre-dispersed liquid is added to 500g of thermoplastic solid phenolic resin powder with a softening point of 82°C and a flow rate of 30mm in three times, and stirred at a speed of 500r / min for 20min to obtain a paste-like premix with a viscosity of 17348mPa.s;

[0088] S2, the obtained premix is ​​rolled 5 times at a roller distance of 10 μm and 5 μm respectively on a three-roll mill at a speed of 200 r / min, and a grind is obtained after multiple grinding;

[0089] S3. Put the obtained 13.3 wt% graphene grind into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 90° C. and 35 r / min for 10 min to obtain a 10.1 wt% graphene-phenolic resin dispersion.

[0090] Example 5

[0091] This embodiment uses graphene pre-dispersion liquid as a raw material. The preparation method of the graphene pre-dispersion liquid used in this embodiment is as follows: 100g of graphene powder prepared by a physical method with a particle size of 15μm and 8 to 10 layers is dispersed in 300g of ethanol solution added with 2g of polyvinyl pyrrolidone and 2g of polyacrylamide, and the solution is stirred for 15min and then ultrasonicated for 15min to obtain the graphene pre-dispersion liquid.

[0092] The present embodiment provides a graphene phenolic resin dispersion and a preparation method thereof, comprising the following steps:

[0093] S1, the pre-dispersed liquid was filtered to obtain a pre-dispersed liquid with a content of 60wt%, the pre-dispersed liquid was added to 300g of a thermoplastic liquid phenolic resin with a solid content of 80% and a viscosity of 5000mPa.s in 5 times, and stirred at a speed of 1000r / min for 30min to obtain a paste-like premix with a viscosity of 13894mPa.s;

[0094] S2, the obtained premix is ​​passed through a three-roll mill with rollers at 20 μm, 10 μm and 5 μm for 5 times, with a speed of 200 r / min, and the ground material is obtained after multiple grinding;

[0095] S3. Put the obtained 21.4 wt% graphene grinding material into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 100° C. and 40 r / min for 20 min to obtain a 10.1 wt% graphene-phenolic resin dispersion.

[0096] Comparative Example 1

[0097] This comparative example uses 500 g of a thermoplastic liquid phenolic resin with a solid content of 75% and a viscosity of 2500 mPa.s.

[0098] S1, stirring the thermoplastic liquid phenolic resin at a speed of 1000r / min for 30min, and passing through a three-roll mill with rollers at a roller spacing of 40μm, 20μm, 10μm and 5μm for 3 times, and a speed of 200r / min to obtain a grinding material;

[0099] S2. Put the ground material into a kneader, evacuate to remove bubbles in the phenolic resin, and shear at 70° C. and 40 r / min for 20 min to obtain a phenolic resin kneaded material.

[0100] Comparative Example 2

[0101] The preparation method of a graphene phenolic resin dispersion provided in this comparative example comprises the following steps:

[0102] S1. 56 g of physically prepared graphene powder with a particle size of 6 μm and 8 to 10 layers was directly added to 500 g of thermoplastic liquid phenolic resin with a solid content of 80% and a viscosity of 8000 mPa.s, and stirred at a speed of 800 r / min for 30 min to obtain a 10.07 wt% paste of graphene premix with a viscosity of 12000 mPa.s.

[0103] Comparative Example 3

[0104] This comparative example uses graphene pre-dispersion liquid as a raw material. The preparation method of the graphene pre-dispersion liquid used in this comparative example is as follows: 100g of graphene powder prepared by a chemical method with a particle size of 3-5μm and 2-5 layers is dispersed in 150g of ethanol solution, stirred for 15min and then ultrasonicated for 15min to obtain a 40wt% graphene pre-dispersion liquid.

[0105] The preparation method of a graphene phenolic resin dispersion provided in this comparative example comprises the following steps:

[0106] S1, adding the pre-dispersed liquid into 500g of thermoplastic solid phenolic resin powder with a softening point of 82°C and a flow rate of 30mm in three times, stirring at a speed of 500r / min for 20min to obtain a paste-like premix with a viscosity of 17348mPa.s;

[0107] S2. The obtained premix was rolled 5 times at a roller distance of 10 μm and 5 μm on a three-roll mill at a speed of 200 r / min to obtain a grind after multiple grinding. The obtained 13.3 wt% graphene grind was put into a kneader, and the bubbles in the phenolic resin were removed by vacuum. The mixture was sheared at 90° C. and 35 r / min for 20 min to obtain a 13.3 wt% graphene-phenolic resin dispersion.

[0108] Performance Testing

[0109] The graphene-phenolic resin dispersion obtained in the above examples and comparative examples was added to a twin-screw extruder for blending, extrusion and granulation to obtain the masterbatch of the graphene-phenolic resin dispersion. After freeze-drying into powder, the powder was added to a mold and pre-pressed at 1.5 MPa and 130°C for 20 minutes, and then hot-pressed and cured at 20 MPa and 130°C for 20 minutes. After cooling to room temperature, the phenolic resin film was obtained and the surface resistance was tested. Surface resistance test: The surface resistance of the film was tested using an ST2643 high resistance meter;

[0110] The graphene-phenolic resin dispersion obtained in the above examples and comparative examples was added to a twin-screw extruder for blending, extrusion and granulation to obtain the masterbatch of the graphene-phenolic resin dispersion. After freeze-drying the masterbatch and the phenolic resin into powder at a mass ratio of 1:9, the powder was added to a mold and pre-pressed at 1.5MPa and 130°C for 20min, and then hot-pressed and cured at 20MPa and 130°C for 20min. After cooling to room temperature, a phenolic resin mold was obtained. Toughness test: According to the GB / T1043.1-2008 method, a simply supported beam impact tester PTM7000 was used to perform an impact toughness test. The test results are shown in Table 1.

[0111] Table 1 Performance test results of graphene phenolic resin dispersion

[0112]

[0113]

[0114] From the data in Table 1, it can be seen that the addition of graphene can greatly improve the conductivity of phenolic resin. At the same time, the dispersibility of graphene in phenolic resin determines the quality of its conductivity. From the results in the table, it can be seen that the higher the graphene content and dispersibility, the lower the surface resistance of the die. Similarly, the toughness of the graphene phenolic resin dispersion is also significantly improved with the addition of graphene. From the comparative example, it can be seen that the graphene that is not mechanically dispersed, ground and kneaded will reduce the toughness of the phenolic resin, and its conductive properties and mechanical properties are lower than those of the uniformly dispersed graphene phenolic resin dispersion prepared by the present invention. The resistance and toughness of the phenolic resin dispersion prepared by the pre-dispersed liquid without adding a dispersant are significantly inferior to those of the graphene phenolic resin dispersion with added dispersants.

[0115] After the graphene-phenolic resin dispersion of Example 5 was prepared into a graphene-phenolic resin solution, the graphene-phenolic resin solution and oxidized natural graphite were uniformly mixed in a mass ratio of 9:91, stirred at room temperature for 5 h, slowly evaporated the solution at 70 ° C, and dried. The obtained product was cured at 150 ° C for 1 h under a nitrogen atmosphere, and then 2 ° C min -1The temperature was raised to 900℃ and carbonized for 3h. The product obtained after carbonization was filtered through a 250-mesh sieve to obtain graphene-phenolic resin coated oxidized natural graphite. The coated negative electrode material was assembled into a half-cell for testing. At room temperature, 3C constant current charge and discharge were tested, the voltage range was 0-2V, the first discharge capacity was greater than 360mAh / g, and the first charge and discharge efficiency was greater than 97%, which effectively increased the capacity of the natural graphite negative electrode.

[0116] In summary, the present invention adopts phenolic resin as a matrix, and a large number of linear structures exist in liquid phenolic resin and thermoplastic phenolic resin powder, and there is no formation of a three-dimensional cross-linked network structure, which is conducive to the dispersion of graphene. Under the further action of a dispersant and a solvent, the dispersion of graphene in the phenolic resin is achieved by using intermolecular forces. Graphene with a specific number of layers and size is used as a dispersion material, and the optimal graphene is selected according to different application fields of the phenolic resin. The introduction of graphene can give the phenolic resin certain electrical conductivity, toughness, impact resistance, fire resistance, corrosion resistance, and material weather resistance and stability.

[0117] The above is only a specific embodiment of the present invention. Obviously, various modifications and combinations can be made to it without departing from the spirit and scope of the present invention. Accordingly, this specification is only an exemplary description of the present invention as defined by the attached claims, and is deemed to have covered any and all modifications, changes, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and variations. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A method for preparing a high-content graphene-phenolic resin dispersion, characterized in that: The high-content graphene-phenolic resin dispersion comprises graphene and phenolic resin; Wherein, the graphene is graphene powder or graphene pre-dispersed liquid; The preparation method comprises the following steps: Premixing graphene powder or graphene pre-dispersion liquid with phenolic resin in multiple times, and obtaining a premix when the viscosity of the system reaches a preset value; The premix is ​​ground multiple times by a three-roll mill to obtain a grind material; the grind material is further kneaded and sheared to obtain a high-content graphene-phenolic resin dispersion.

2. A high-content graphene-phenolic resin dispersion according to claim 1, characterized in that: The graphene powder is one or a mixture of graphene prepared by a physical method or graphene prepared by a chemical method; In the graphene powder or graphene pre-dispersion liquid, the particle size of the graphene is 0.1 to 100 μm; In the graphene powder or graphene pre-dispersion liquid, the number of graphene layers is 2 to 10.

3. A high-content graphene-phenolic resin dispersion according to claim 1, characterized in that: The graphene pre-dispersion liquid is a uniformly dispersed solution obtained by pre-dispersing graphene powder, comprising graphene, a dispersant and a solvent; The dispersant is any one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, sodium lignin sulfonate, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, polymethacrylic acid or polyacrylamide; The amount of the dispersant added is 0.1 to 10% of the graphene content; The solvent is one or more of ethanol, ethylene glycol, isopropanol, butanol, ethyl acetate and butanone.

4. A high-content graphene-phenolic resin dispersion according to claim 1, characterized in that: In the graphene pre-dispersion liquid, the content of graphene is 10-60wt%.

5. A high-content graphene-phenolic resin dispersion according to claim 1, characterized in that: The phenolic resin is one or a combination of solid phenolic resin or liquid phenolic resin; The liquid phenolic resin is a thermoplastic liquid phenolic resin or a thermosetting liquid phenolic resin; The solid content of the liquid phenolic resin is 70wt% to 80wt%; The phenolic resin is a liquid phenolic resin with a viscosity of 1000 to 30000 mPa. . s; The solid phenolic resin has a softening point of 70 to 140° C. and a flow rate of 20 to 50 mm.

6. A high-content graphene-phenolic resin dispersion according to claims 1 to 5, characterized in that: The premix is ​​one or more of a paste of graphene powder and liquid phenolic resin, a paste of graphene pre-dispersed liquid and liquid phenolic resin, a paste of graphene powder and phenolic resin powder mixed by heating, and a paste of graphene pre-dispersed liquid and phenolic resin powder. Preferably, the content of graphene in the dispersion is 5-50%.

7. The method for preparing a graphene-phenolic resin dispersion according to claim 1, characterized in that: The premixing method comprises adding graphene powder or graphene pre-dispersed liquid into phenolic resin in 2 to 8 times, mechanically stirring, with a stirring speed of 300 to 1500 r / min and a stirring time of 5 to 30 min, to obtain a premix with a preset viscosity of 1000 to 50000·mPa.s.

8. The method for preparing a graphene-phenolic resin dispersion according to claim 1, characterized in that: The grinding material is a premixed material added to a three-roll mill, and the roller spacing of the three-roll mill is adjusted according to the size of the graphene, and the spacing range is 5 to 100 μm; The number of times of grinding the premix by the three-roll mill is 1 to 20 times.

9. The method for preparing a graphene-phenolic resin dispersion according to claim 1, characterized in that: The kneading process of the kneading material is selected based on the following: the grinding material with a graphene addition amount of 5 to 25 wt% is selected by a kneading machine for shear mixing, and the grinding material with a graphene addition amount of 25 to 50 wt% is selected by an internal mixer for shear mixing to obtain the kneading material.

10. Use of a high-content graphene-phenolic resin dispersion in composite masterbatch and coating agent for lithium battery materials.

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