Crystal graphene aqueous slurry as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high polymer materials, and particularly relates to cryptocrystalline graphene water-based slurry as well as a preparation method and application thereof. The preparation method of the cryptocrystalline graphene water-based slurry comprises the following steps: (1) adding a dispersing agent and a wetting agent into water, and uniformly stirring to obtain a mixed solution; (2) adding cryptocrystalline graphene powder into the mixed solution obtained in the step (1), and then dispersing for 0.5-2 hours at the speed of 1000-2000r / min to obtain a pre-dispersion liquid; and (3) adding a thickening agent and a defoaming agent into the pre-dispersion liquid obtained in the step (2), and then dispersing for 10-30 minutes at the speed of 5000-8000r / min, thereby obtaining the water-based paint. The aqueous cryptocrystalline graphene slurry is good in dispersibility, good in electrical conductivity, good in stability and high in viscosity, meets the requirements of application scenes such as electrical conductivity, thermal conductivity and coatings, and improves the economic utilization value of the cryptocrystalline graphene powder.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a cryptocrystalline graphene aqueous slurry and a preparation method and application thereof. Background Art

[0002] Currently, my country's cryptocrystalline graphite resources offer significant advantages for industrialization, particularly due to their high purity. Raw ore from Hunan and other regions can contain carbon contents exceeding 85%. This abundant carbon source provides a foundation for the large-scale development of cryptocrystalline graphene materials. The unique diamond-like crystal structure of this type of microcrystalline graphite imparts excellent electrical and thermal conductivity and chemical stability, demonstrating unique potential for high-end applications such as lithium battery conductive agents and electromagnetic shielding coatings.

[0003] Graphene possesses excellent physical and chemical properties, including high barrier properties, electrical and thermal conductivity, chemical resistance, and high-temperature stability. Adding it to coatings has the potential to enhance their performance. However, due to its extremely large specific surface area, graphene is difficult to wet and disperse in aqueous solutions. Failure to achieve good dispersion of graphene hinders its full potential. Furthermore, due to its low surface energy, graphene tends to accumulate on surfaces. Poor dispersion can also lead to reduced coating adhesion and adversely affect coating performance.

[0004] Currently, graphene aqueous slurries are generally prepared by dispersants or mechanical exfoliation. However, dispersants (such as polyvinyl pyrrolidone) have poor compatibility with graphene, making it impossible to effectively intercalate and exfoliate, resulting in poor dispersion. Mechanical exfoliation consumes a lot of energy and easily destroys the crystal structure, leading to a decrease in conductivity. Due to the small crystallite size (<1μm) and strong interlayer van der Waals forces of cryptocrystalline graphene, it is difficult to obtain a stable slurry using conventional dispersion processes. Therefore, it is necessary to explore a method that has a good dispersion effect on cryptocrystalline graphene, prepare a stable cryptocrystalline graphene slurry, broaden its high-end application scenarios, and make it more economically valuable. Summary of the Invention

[0005] The first object of the present invention is to provide a method for preparing an aqueous cryptocrystalline graphene slurry. The second object of the present invention is to provide an aqueous cryptocrystalline graphene slurry obtained by the preparation method. The third object of the present invention is to provide an application of the aqueous cryptocrystalline graphene slurry.

[0006] According to a first aspect of the present invention, there is provided a method for preparing an aqueous slurry of cryptocrystalline graphene, comprising the following steps:

[0007] (1) adding a dispersant and a wetting agent into water and stirring uniformly to obtain a mixed solution;

[0008] (2) adding cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000-2000 r / min for 0.5-2 h to obtain a pre-dispersion liquid;

[0009] (3) adding a thickener and a defoamer to the pre-dispersion liquid of step (2), and then dispersing the mixture in a dispersion device at a speed of 5000-8000 r / min for 10-30 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0010] In some embodiments, the dispersant is DisuperS28, BESM 9800, at least two of tannic acid and sodium dodecylbenzenesulfonate.

[0011] DisuperS28 is a CRP polyamide hyperbranched polymer (branched polymer) with functional end groups in its molecular chain segments. It is produced by Guangdong Core New Materials Co., Ltd.

[0012] BESM 9800 is a non-ionic polymer containing high pigment affinity groups, produced by Guangdong Shierli New Materials Co., Ltd.

[0013] Small molecule dispersants such as tannic acid and sodium dodecylbenzenesulfonate are easily soluble in water. Their polyphenyl ring structures can modify graphene through π-π conjugation. As surfactants, they can be adsorbed on the surface of graphene particles to enhance wetting and reduce agglomeration. Commercial polymer dispersants such as DisuperS28 and BESM 9800 not only acts as an anchoring group but also has a certain coating effect, which can generate strong steric hindrance and thus enhance dispersion. The synergistic effect of small molecule dispersants and high molecular weight dispersants is excellent.

[0014] In some embodiments, the dispersant is BESM 9800 and sodium dodecylbenzenesulfonate, the mass ratio of the two is 1:2.

[0015] In some embodiments, the dispersant is BESM 9800, tannic acid, and sodium dodecylbenzenesulfonate, the mass ratio of the three is 2.5:1:5.

[0016] In some embodiments, the dispersant is DisuperS28, BESM 9800 and sodium dodecylbenzenesulfonate, the mass ratio of the three is 1:2.5:5.

[0017] In some embodiments, the dispersant is DisuperS28, BESM 9800, tannic acid, and sodium dodecylbenzenesulfonate, the mass ratio of the four is 1:2.5:1:5.

[0018] In some embodiments, the wetting agent is one or more of glycerol, polyethylene glycol 400, and ethylene glycol. The addition of the wetting agent can accelerate the dispersion efficiency and shorten the preparation time of the slurry.

[0019] In some embodiments, in step (1), the concentration of the dispersant in the mixed solution is 0.5-5 wt %, and the concentration of the wetting agent is 0.5-3 wt %.

[0020] In some embodiments, in step (2), the concentration of cryptocrystalline graphene powder in the pre-dispersion liquid is 13-17 wt %.

[0021] In some embodiments, the pre-dispersing equipment is a high-speed mixer, a vacuum mixer, or a homogenizer.

[0022] In some embodiments, the thickener is one or more of sodium carboxymethyl cellulose, xanthan gum, and polyacrylamide. Thickeners form a network structure by stretching their molecular chains, increasing frictional resistance between molecules within the slurry, thereby increasing the overall viscosity. By increasing the viscosity of the continuous phase or forming a three-dimensional network, the settling rate of solid particles is slowed, extending the storage stability of the slurry.

[0023] In some embodiments, the thickener is a mixture of sodium carboxymethyl cellulose, xanthan gum, and polyacrylamide in a mass ratio of 2:1:1.

[0024] In some embodiments, the defoaming agent is JT-908, J0416, BESM One or more of 5002. Defoaming agents can inhibit foam generation and aggregation, thereby improving preparation efficiency.

[0025] JT-908 is a modified polydimethylsiloxane defoamer emulsion produced by Shenzhen Jitian Chemical Co., Ltd.

[0026] J0416 is a defoaming agent composed of polyether ester, mineral oil, hydrophobic silica and other ingredients, produced by Shenzhen Jitian Chemical Co., Ltd.

[0027] BESM 5002 is a polyether silicone emulsion produced by Guangdong Shierli New Materials Co., Ltd.

[0028] In some embodiments, the concentration of the thickener in the cryptocrystalline graphene aqueous slurry is 0.3-1 wt %, and the concentration of the defoaming agent is 0.1-1 wt %.

[0029] In some embodiments, the dispersing device is a sand mill, a ball mill, or a high-pressure homogenizer.

[0030] According to a second aspect of the present invention, provided is an aqueous slurry of cryptocrystalline graphene prepared by the above preparation method.

[0031] According to a third aspect of the present invention, there is provided the use of the above-mentioned cryptocrystalline graphene aqueous slurry in the preparation of lithium-ion batteries, ceramic substrates, high thermal conductivity composite materials, anti-corrosion coatings, and antistatic epoxy floor paints.

[0032] The beneficial effects of the present invention include:

[0033] (1) The present invention adopts a compound dispersant, tannic acid, sodium dodecylbenzene sulfonate small molecule dispersant benzene ring group on graphene π-π conjugation, itself ionized in aqueous solution to produce charge repulsion to enhance dispersion; DisuperS28, BESM 9800 polymer dispersant anchors graphene through special anchoring groups. Under high-speed dispersion conditions, small molecule dispersants play an intercalation dispersion role, and then the long chains of polymer dispersants are used to coat the graphene particles, which plays a synergistic role and can greatly reduce the amount of dispersant used.

[0034] (2) The cryptocrystalline graphene aqueous slurry of the present invention has good dispersibility, good conductivity, good stability and high viscosity, which meets the requirements of application scenarios such as conductivity, thermal conductivity and coating, and improves the economic utilization value of cryptocrystalline graphene powder.

[0035] (3) The solvent of the present invention is water, which does not contain volatile organic solvents, and the raw materials are widely available, which is green and environmentally friendly, and can greatly reduce pollution to the environment. In addition, the process flow is simple, suitable for large-scale production, and has high practical application value. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with specific examples. It is worth noting that the following examples are only for better explanation of the present invention and are not intended to limit the scope of protection of the present invention. The undisclosed process steps in the examples are prior art. Unless otherwise specified, the following raw materials are commercially available.

[0037] In the following examples and comparative examples, Disuper S28 was purchased from Guangdong Core New Materials Co., Ltd., hereinafter referred to as S28; BESM 9800 was purchased from Guangdong Shierli New Materials Co., Ltd., hereinafter referred to as S9800.

[0038] Cryptocrystalline graphene powder was purchased from Hunan Runzhong New Material Technology Co., Ltd.

[0039] The thickener is a mixture of sodium carboxymethyl cellulose, xanthan gum and polyacrylamide in a mass ratio of 2:1:1.

[0040] The defoaming agent was JT-908, purchased from Shenzhen Jitian Chemical Co., Ltd.

[0041] The pre-dispersing equipment is a high-speed mixer, and the dispersing equipment is a high-pressure homogenizer.

[0042] Example 1

[0043] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0044] (1) Add 5 g of sodium dodecylbenzenesulfonate, 2.5 g of S9800, 2 g of polyethylene glycol 400, and 0.5 g of glycerol into a beaker, add 413 g of deionized water, and stir to obtain a mixed solution;

[0045] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0046] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0047] Example 2

[0048] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0049] (1) 5 g of sodium dodecylbenzenesulfonate, 2.5 g of S9800, 1 g of tannic acid, 2 g of polyethylene glycol 400, and 0.5 g of glycerol were added to a beaker, and 411 g of deionized water was added and stirred to obtain a mixed solution;

[0050] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0051] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0052] Example 3

[0053] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0054] (1) 5 g of sodium dodecylbenzenesulfonate, 2.5 g of S9800, 1 g of S28, 2 g of polyethylene glycol 400, and 0.5 g of glycerol were added to a beaker, and 411 g of deionized water was added and stirred to obtain a mixed solution;

[0055] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0056] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0057] Example 4

[0058] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0059] (1) 5 g of sodium dodecylbenzene sulfonate, 2.5 g of S9800, 1 g of S28, 1 g of tannic acid, 2 g of polyethylene glycol 400, and 0.5 g of glycerol were added to a beaker, and 409 g of deionized water was added and stirred to obtain a mixed solution;

[0060] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0061] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0062] Example 5

[0063] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0064] (1) 5 g of sodium dodecylbenzenesulfonate, 2.5 g of S9800, 1 g of S28, 1 g of tannic acid, 2 g of polyethylene glycol 400, and 0.5 g of ethylene glycol were added to a beaker, and 409 g of deionized water was added and stirred to obtain a mixed solution;

[0065] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0066] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0067] Example 6

[0068] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0069] (1) 5 g of sodium dodecylbenzenesulfonate, 2.5 g of S9800, 1 g of S28, 1 g of tannic acid, 2 g of polyethylene glycol 400, and 0.5 g of ethylene glycol were added to a beaker, and 409 g of deionized water was added and stirred to obtain a mixed solution;

[0070] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 2 h to obtain a pre-dispersion liquid;

[0071] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0072] Example 7

[0073] The method for preparing the cryptocrystalline graphene aqueous slurry of this embodiment comprises the following steps:

[0074] (1) 5 g of sodium dodecylphenyl sulfonate, 2.5 g of S9800, 1 g of S28, 1 g of tannic acid, 2 g of polyethylene glycol 400, and 0.5 g of ethylene glycol were added to a beaker, and 409 g of deionized water was added and stirred to obtain a mixed solution;

[0075] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0076] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 30 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0077] Comparative Example 1

[0078] The preparation method of the cryptocrystalline graphene aqueous slurry of this comparative example comprises the following steps:

[0079] (1) Add 7.5 g of sodium dodecylbenzenesulfonate, 2 g of polyethylene glycol 400, and 0.5 g of glycerol into a beaker, add 413 g of deionized water, and stir to obtain a mixed solution;

[0080] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0081] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0082] Comparative Example 2

[0083] The preparation method of the cryptocrystalline graphene aqueous slurry of this comparative example comprises the following steps:

[0084] (1) Add 7.5 g of S9800, 2 g of polyethylene glycol 400, and 0.5 g of glycerol to a beaker, add 413 g of deionized water, and stir to obtain a mixed solution;

[0085] (2) adding 75 g of cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it in a pre-dispersion device at a speed of 1000 r / min for 1 h to obtain a pre-dispersion liquid;

[0086] (3) The pre-dispersion liquid of step (2) was poured into a dispersion device, and then 2 g of thickener and 2 g of defoamer were added, and dispersed at a speed of 5000 r / min for 20 min to obtain an aqueous slurry of cryptocrystalline graphene.

[0087] Next, in order to verify the performance of the cryptocrystalline graphene aqueous slurry prepared by the present invention, the cryptocrystalline graphene aqueous slurries prepared in Examples 1-7 and Comparative Examples 1-2 were subjected to the following performance tests.

[0088] 1. Test method

[0089] (1) Resistance test method: Take an appropriate amount of slurry and coat it on a PET film to obtain a 20 μm thick coating, and then use a four-probe resistance meter to test the resistance.

[0090] (2) Particle size test method: Take the slurry and drop it into the Biacore particle size analyzer. Test three times to get the particle size. 50 Particle size.

[0091] (3) Sedimentation test method: Leave the slurry to stand for 30 days and observe whether there is any sedimentation.

[0092] (4) Viscosity test method refers to GB / T 265-1988: Take an appropriate amount of slurry and measure the slurry viscosity using a rotational viscometer.

[0093] 2. Test results

[0094] The test results are shown in Table 1.

[0095] Table 1 Performance test results of the slurries of Examples 1-7 and Comparative Examples 1-2

[0096] sample Resistance (Ω / sq) Particle size (μm) Settlement (30 days) Viscosity (MPa·s) Example 1 16.50 2.51 none 2078 Example 2 15.76 2.65 none 2115 Example 3 16.44 2.53 none 2098 Example 4 16.12 2.57 none 2040 Example 5 13.41 2.48 none 1988 Example 6 12.36 2.32 none 1907 Example 7 15.31 2.10 none 1854 Comparative Example 1 64.93 5.21 Sedimentation and stratification 2259 Comparative Example 2 66.17 4.77 Sedimentation and stratification 2362

[0097] As can be seen from Table 1, the coating resistance of the slurries of Examples 1-7 is significantly smaller than that of Comparative Example 1-2, the particle size of the slurries of Examples 1-7 is significantly smaller than that of Comparative Example 1-2, and the viscosity is equivalent to that of Comparative Example 1-2. The slurries of Examples 1-7 did not settle after standing for 30 days, while the slurry of Comparative Example 1-2 precipitated and stratified after standing for 30 days.

[0098] The reason for the above phenomenon is that: Comparative Example 1-2 adopts a single type of dispersant, which cannot form a synergistic effect and has a poor dispersion effect on graphene. Therefore, the slurry in Comparative Example 1-2 has been precipitated and stratified after being left to stand for 30 days. Embodiment 1-7 adopts a composite dispersant, which is conducive to the peeling and dispersion of graphene, can effectively prevent the agglomeration of graphene, and as the type of composite dispersant increases, it is possible to increase the synergistic effect and make the slurry particle size dispersed smaller. In addition, as can be seen from the test results of Example 5 and Example 6, increasing the pre-dispersion time can allow graphene to disperse better, the slurry conductivity increases, and the viscosity decreases slightly. As can be seen from the test results of Example 5 and Example 7, increasing the high-speed dispersion time can cause the resistance to rise slightly. This may be because the dispersion time is too long to destroy the intrinsic structure of graphene, thereby amplifying the defects and making the resistance larger, but still can maintain good conductivity.

[0099] As a result, the cryptocrystalline graphene aqueous slurry prepared by the present invention has a small particle size, high viscosity, good electrical conductivity, and excellent stability. The electrical and thermal conductivity of pristine graphene are positively correlated. The slurry prepared by the present invention uses a small amount of dispersant, which greatly preserves the original characteristics of graphene and can meet the requirements of applications such as electrical and thermal conductivity and coatings.

[0100] The above descriptions are only some specific embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing an aqueous cryptocrystalline graphene slurry, characterized in that: The steps include: (1) adding a dispersant and a wetting agent into water and stirring uniformly to obtain a mixed solution; (2) adding cryptocrystalline graphene powder to the mixed solution of step (1), and then dispersing it at a speed of 1000-2000 r / min for 0.5-2 h to obtain a pre-dispersion solution; (3) adding a thickener and a defoamer to the pre-dispersion liquid of step (2), and then dispersing the mixture at a speed of 5000-8000 r / min for 10-30 min to obtain an aqueous slurry of cryptocrystalline graphene.

2. The preparation method according to claim 1, characterized in that The dispersant is Disuper S28, 9800, at least two of tannic acid and sodium dodecylbenzenesulfonate.

3. The preparation method according to claim 1 or 2, characterized in that The wetting agent is one or more of glycerol, polyethylene glycol 400, and ethylene glycol.

4. The preparation method according to claim 1 or 2, characterized in that In step (1), the concentration of the dispersant in the mixed solution is 0.5-5wt%, and the concentration of the wetting agent is 0.5-3wt%.

5. The preparation method according to claim 1 or 2, characterized in that In step (2), the concentration of cryptocrystalline graphene powder in the pre-dispersion liquid is 13-17 wt %.

6. The preparation method according to claim 1 or 2, characterized in that The thickener is one or more of sodium carboxymethyl cellulose, xanthan gum, and polyacrylamide.

7. The preparation method according to claim 1 or 2, characterized in that The defoaming agent is JT-908, J0416, One or more of 5002.

8. The preparation method according to claim 1 or 2, characterized in that The concentration of the thickener in the cryptocrystalline graphene aqueous slurry is 0.3-1 wt %, and the concentration of the defoaming agent is 0.1-1 wt %.

9. A cryptocrystalline graphene aqueous slurry obtained by the preparation method according to any one of claims 1 to 8.

10. Use of the cryptocrystalline graphene aqueous slurry according to claim 9 in the preparation of lithium-ion batteries, ceramic substrates, high thermal conductivity composite materials, anti-corrosion coatings, and antistatic epoxy floor paints.

Images