CN111323417B - Method for rapidly detecting storage stability of graphene material dispersion liquid - Google Patents

Abstract

The invention provides a method for detecting the storage stability of a graphene material dispersion liquid, which comprises the following steps of firstly carrying out metallographic phase detection on the graphene material dispersion liquid to obtain the dispersion state and/or morphology condition of a graphene material in a dispersion liquid system; then centrifuging the graphene material dispersion liquid to obtain a centrifugal liquid; detecting whether the bottom of the centrifugate is caked and/or whether the centrifugate is layered; stirring the centrifugate obtained in the step, and performing metallographic detection on the lower layer of the centrifugate to obtain the dispersion state and/or morphology of the graphene materials on the lower layer of the centrifugate in a dispersion system; and finally comparing the metallographic detection results in the two steps to judge the storage stability of the graphene material dispersion liquid. The rapid detection method can rapidly detect the dispersity of the graphene material dispersion liquid, particularly the dispersity and stability after long-time storage, by a simple centrifugal separation and stirring method.

Description

A rapid detection method for storage stability of graphene-like material dispersion

technical field

The invention belongs to the technical field of graphene, and relates to a detection method and a determination method for the storage stability of a graphene material dispersion, in particular to a rapid detection method and a rapid determination method for the storage stability of a graphene material dispersion.

Background technique

Graphene is a single layer of carbon atoms tightly packed into a two-dimensional hexagonal honeycomb lattice structure, and each carbon atom is connected by sp2 hybridization. Microscopically, the single-layer graphene film is not a two-dimensional flat structure, but has a stable microwave-like single-layer structure "on the nanoscale", and is the only two-dimensional free-state atomic crystal found so far; macroscopically, graphite Alkenes can be warped into zero-dimensional fullerenes, rolled into one-dimensional carbon nanotubes or stacked into three-dimensional graphite. The existence of stable carbon six-membered rings in graphene's unique two-dimensional periodic honeycomb lattice structure endows it with excellent performance: the thickness of single-layer graphene is only 0.35nm, which is the lightest and thinnest material known so far ; The electron mobility at room temperature is 2×10 ⁵ cm ² ·V ^-1 ·s ^-1 , which is 1/300 of the speed of light. The theoretical specific surface area can reach 2630m ² ·g ^-1 . The conductivity is as high as 5000W·m ^-1 ·K ^-1 , the Young's modulus exceeds 1100GPa, the tensile strength exceeds 130GPa, and the toughness is very good. When an external mechanical force is applied, the carbon atoms will adapt to the external force by bending deformation without having to The carbon atoms are rearranged, thus maintaining the stability of the structure. These characteristics make it very suitable for a variety of disciplines and fields. It is widely used in energy storage materials, environmental engineering, and sensitive sensing. It is called "black gold" or "king of new materials", and its potential applications It has broad prospects and has become the focus of attention and research hotspots all over the world.

Although graphene has excellent properties, there are still many problems and constraints in practical applications, the most important of which is that graphene is very easy to agglomerate, which in turn brings about difficulties in dispersibility. Due to the strong van der Waals interaction between graphene, it cannot be stably dispersed in solvents, and it is easy to reunite and difficult to open after dispersion, which greatly restricts the research, application and industrialization of graphene, especially the It solves the storage problems of manufacturers and users in the subsequent actual industrialization.

Moreover, with the further development and application of graphene, people have more and more strict requirements on the quality of graphene products, and naturally the quality requirements for graphene dispersions are also getting higher and higher. It is easy to settle and stratify, and the sedimentation layer is not easy to disperse again, which has a great performance impact on the production of downstream products of its graphene dispersion. Therefore, the storage stability of graphene dispersion has become one of its important indicators.

However, how to detect the dispersion of graphene products and ensure storage stability has become a current technical difficulty, and how to quickly determine the long-term storage performance of graphene product dispersions is a blank in the field.

Therefore, how to find a method for detecting the dispersibility and storage stability of graphene-based materials, as well as perform rapid and effective detection and analysis, has become one of the urgent problems that many graphene manufacturers and downstream customers in the industry need to solve. .

Contents of the invention

In view of this, the technical problem to be solved in the present invention is to provide a detection method and a determination method for the storage stability of a graphene material dispersion, especially a rapid detection method and a rapid detection method for the storage stability of a graphene material dispersion. As for the determination method, the method provided by the present invention can quickly detect the dispersibility and stability of the graphene-based material dispersion, and can also quickly determine the storage stability of the graphene-based material dispersion within 6 months.

The invention provides a method for detecting the storage stability of a graphene material dispersion, comprising the following steps:

1) Carrying out metallographic detection of the graphene-like material dispersion liquid to obtain the dispersion state and/or morphology of the graphene-like material in the dispersion liquid system;

2) After centrifuging the graphene-like material dispersion, obtain the centrifugate;

Check for clumping and/or layering at the bottom of the centrate;

4) After stirring the centrifugate obtained in the above steps, take the lower layer of the centrifuge and carry out metallographic detection to obtain the dispersion state and/or morphology of the graphene material in the lower layer of the centrifuge in the dispersion system;

5) Comparing the metallographic detection results in step 1) and step 4), and judging the storage stability of the graphene material dispersion.

Preferably, the graphene-based material includes one or more of graphene, graphene oxide, reduced graphene oxide and modified graphene;

The solvent of the graphene material dispersion liquid includes water and/or organic solvent;

The mass concentration of the graphene material dispersion liquid is 0.1%-3%.

Preferably, the organic solvent includes one or more of ethanol, xylene, n-butanol, isopropanol, propylene glycol methyl ether, epoxy resin, acrylic resin, polyurethane and alkyd resin;

The rotating speed of the centrifugal treatment is 200～1000r/min;

The time of the centrifugal treatment is 30-240 minutes.

Preferably, the bottom of the detection centrifugate is specifically:

Place the centrate vertically, and detect the bottom of the centrate through the device;

The device includes one or more of a paint spatula, a medicine spoon and a glass rod.

Preferably, the step 2) is specifically:

centrifuging the graphene material dispersion to obtain a centrifuge;

Check for clumping at the bottom of the centrate and/or observe for stratification;

When there is agglomeration and/or stratification at the bottom of the centrifugate, it indicates that the storage stability of the graphene-based material dispersion is unqualified;

When there is no agglomeration and/or stratification at the bottom of the centrifugate, proceed to step 4).

Preferably, the stirring comprises low-speed stirring;

The stirring speed is 40～70r/min;

The stirring time is 1-5 minutes.

Preferably, the comparison is specifically:

In the metallographic examination results of the step 1) and step 4), the consistency of the dispersion state and/or morphology of the graphene-based material is greater than or equal to 80%;

The storage stability is specifically the storage stability within 12 months.

Preferably, the storage stability is specifically the storage stability within 6 months;

The similarity between the metallographic test results in step 4) and the metallographic test results of the graphene-based material dispersion after conventional storage for 6 months is greater than or equal to 90%.

Preferably, in the step 1) and step 4), the metallographic detection is specifically: selecting different sampling points for multiple metallographic detection and/or selecting different microscopic metallographic fields of view of the same sample for multiple metallographic detection. phase detection;

The number of said multiple times is 2 to 10 times.

The invention provides a method for determining the storage stability of a graphene material dispersion, comprising the following steps:

1) After centrifuging and stirring the graphene-based material dispersion, the centrifugate is obtained;

The rotating speed of the centrifugal treatment is 200～1000r/min;

The time of the centrifugal treatment is 30-240min;

2) taking the lower layer of the centrifuge liquid for metallographic detection, and obtaining the dispersion state and/or morphology of the graphene material in the lower layer of the centrifuge liquid in the dispersion system;

The dispersion state and/or morphology of the graphene material in the lower layer of the centrifugal liquid in the dispersion system, and the dispersion under the metallographic detection of the lower layer of the dispersion liquid after the storage of the graphene material dispersion for 6 months State and/or morphology, the similarity is greater than or equal to 90%.

The invention provides a method for detecting the storage stability of a graphene-based material dispersion, which comprises the following steps: first, the graphene-based material dispersion is subjected to metallographic detection to obtain the dispersion state and the dispersion state of the graphene-based material in the dispersion system /or morphology; then the graphene material dispersion is centrifuged to obtain a centrifuge; detect whether there is agglomeration and/or stratification at the bottom of the centrifuge; then stir the centrifuge obtained in the above steps Finally, take the lower layer of the centrifugal liquid and carry out metallographic detection, obtain the dispersion state and/or appearance of the graphene material in the lower layer of the centrifugal liquid in the dispersion liquid system; finally the metallographic detection results in step 1) and step 4) Compare and judge the storage stability of the graphene material dispersion. Compared with the prior art, the present invention is aimed at in the existing detection method, and seldom relates to the method that is specially used in detecting the dispersibility and the long-term stability of graphene material dispersion liquid effectively, and along with the further development of graphene and applications, the storage stability of graphene dispersions has become an important indicator of the status quo. At the same time, although there is a method for detecting the ash and solid content in the graphene dispersion, it is difficult to judge the dispersion performance through the detection result of the ash, and because the solid content in the graphene dispersion itself is relatively low, there is also an error in the value of the solid content Large and poor parallelism and other issues.

The present invention provides a method capable of quickly detecting the dispersibility and stability of the graphene material dispersion liquid, and creatively through a simple centrifugation and stirring method, which can quickly detect the dispersibility of the graphene material dispersion liquid, especially The dispersibility and stability after long-term storage effectively solve the problem of poor dispersibility of graphene dispersion in practical applications, as well as long-term storage agglomeration, and the phenomenon that the dispersion stability is difficult to determine. Compared with the actual storage under natural conditions Only then can the current status of its stability be detected. The present invention is faster and easier, and it is more convenient for customers to judge the performance of the product index in a short time, and provides technical support for customers to judge the product, thereby greatly improving the stability of subsequent product performance. sex.

Experimental results show that the present invention uses centrifugation to quickly determine the difference in dispersibility and stability of the graphene dispersion after long-term storage for 6 months. The dispersion state and/or morphology of the graphene material dispersion obtained by the method of the present invention is the same as the dispersion state and/or morphology of the metallographic detection of the lower layer of the dispersion after the graphene material dispersion was stored for 6 months. The similarity is greater than or equal to 90%.

Description of drawings

Fig. 1 is the graphene dispersion liquid OBO-MG-1 that the embodiment of the present invention 1 provides and the appearance photo of OBO-MG-2 after placing 6 months;

Fig. 2 is the photograph that the graphene dispersion liquid OBO-MG-1 and OBO-MG-2 provided by the embodiment of the present invention 1 are placed 6 months after the bottom layer is sampled with a spatula;

Fig. 3 is the metallographic micrograph of graphene dispersion liquid OBO-MG-1 and OBO-MG-2 that the embodiment of the present invention 1 provides before placing;

Fig. 4 is the metallographic micrograph of graphene dispersion liquid OBO-MG-1 and OBO-MG-2 that the embodiment of the present invention 1 provides after placing 6 months;

Fig. 5 is the photograph that the graphene dispersion provided by the embodiment of the present invention 2 is placed naturally for 6 months and the bottom of the sample after centrifugation is sampled with a spatula;

Fig. 6 is the graphene dispersion liquid provided by the embodiment of the present invention 2 to place naturally for 6 months and the appearance photograph after the present invention handles;

Fig. 7 is the metallographic micrograph of the graphene dispersion liquid provided by the embodiment of the present invention 2 placed naturally for 6 months and after initial treatment;

Fig. 8 is the photograph that the bottom layer is sampled with a spatula after two kinds of graphene dispersion liquids provided by Example 3 of the present invention are subjected to steps such as centrifugation;

Fig. 9 is the treated metallographic micrographs of two kinds of graphene dispersions provided by Example 3 of the present invention;

Fig. 10 is a photo of the bottom layer sampling with a spatula after two kinds of graphene dispersions provided by Example 4 of the present invention are subjected to centrifugation and other steps;

FIG. 11 is a metallographic microscope photo of two graphene dispersions provided in Example 4 of the present invention after treatment.

Detailed ways

In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the invention.

All raw materials in the present invention have no particular limitation on their sources, they can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

All the raw materials of the present invention have no particular limitation on their purity, and the present invention preferably adopts analytical purity or conventional purity requirements in the field of graphene preparation.

All raw materials of the present invention, their grades and abbreviations belong to the conventional grades and abbreviations in this field, and each grade and abbreviation are all clear and definite in the field of its related use. Those skilled in the art can according to the grades, abbreviations and corresponding uses, It can be purchased from commercial sources or prepared by conventional methods.

The invention provides a method for detecting the storage stability of a graphene material dispersion, comprising the following steps:

1) Carrying out metallographic detection of the graphene-like material dispersion liquid to obtain the dispersion state and/or morphology of the graphene-like material in the dispersion liquid system;

2) After centrifuging the graphene-like material dispersion, obtain the centrifugate;

Check for clumping and/or layering at the bottom of the centrate;

4) After stirring the centrifugate obtained in the above steps, take the lower layer of the centrifuge and carry out metallographic detection to obtain the dispersion state and/or morphology of the graphene material in the lower layer of the centrifuge in the dispersion system;

5) Comparing the metallographic detection results in step 1) and step 4), and judging the storage stability of the graphene material dispersion.

In the present invention, metallographic detection is firstly carried out on the graphene-like material dispersion liquid to obtain the dispersion state and/or morphology of the graphene-like material in the dispersion liquid system.

The present invention has no special limitation on the definition of metallographic detection, and the definition of metallographic detection well-known to those skilled in the art can be used. Those skilled in the art can select and adjust according to the actual detection situation, product requirements and quality requirements. The metallographic detection described in the invention is preferably detected by a metallographic microscope.

In principle, the present invention has no special limitation on the parameters of the metallographic detection, and the conventional parameters of the metallographic detection of graphene material solutions well known to those skilled in the art can be used. Those skilled in the art can according to the actual detection situation, product requirements and Quality requirements are selected and adjusted. The metallographic detection multiple of the present invention is preferably a multiple that can clearly see the dispersion state and morphology of the graphene material in the graphene material solution, more preferably 5 to 100 times, More preferably 20 to 80 times, more preferably 40 to 60 times, specifically 5 times, 10 times, 20 times, 50 times, 100 times, more preferably 10 times, 20 times, 50 times.

In order to be able to better and accurately detect the dispersion performance and long-term storage stability of the dispersion liquid of graphene-based materials, the present invention refines the detection method to improve usability and parallelism. The metallographic detection method in the above steps is as follows: select different Perform multiple metallographic inspections at sampling points and/or select different microscopic metallographic fields of view for the same sample for multiple metallographic inspections. It is more preferable to select different sampling points for multiple metallographic inspections or to select different microscopic metallographic fields of view of the same sample for multiple metallographic inspections. Therefore, the metallographic detection can more accurately reflect the dispersion state of the graphene-like material in the detected dispersion liquid. The number of times in the present invention is preferably 2 to 10 times, more preferably 3 to 9 times, more preferably 5 to 7 times.

The present invention has no special limitation on the definition of the graphene-based material, and the definition of the graphene-based material well known to those skilled in the art can be selected and adjusted by those skilled in the art according to actual application conditions, product requirements and quality requirements , the graphene material of the present invention is preferably graphene in a broad sense, also known as graphene and its derivatives or graphene, preferably including graphene in a narrow sense, graphene oxide, reduced graphene oxide and modified graphene One or more of, more preferably single-layer graphene, few-layer graphene, multi-layer graphene, graphene oxide, reduced graphene oxide or modified graphene, more preferably graphene, graphene oxide or reduced Graphene oxide.

The present invention does not have special limitation to the parameter of described graphene, can be with the parameter of graphene material well-known to those skilled in the art, and those skilled in the art can select and adjust according to actual application situation, composite situation and product performance, the present invention The number of sheets of the graphene-based material described in the invention is preferably 1 to 5 layers, or 2 to 4 layers, or 1 to 3 layers, etc., and is more preferably the proportion of graphene with sheets less than or equal to 5 layers. 80% or more, more preferably 85% or more, more preferably 90% or more. The thickness of the graphene material sheet in the present invention is preferably 0.7-2 nm, more preferably 1.0-1.8 nm, more preferably 1.2-1.5 nm. The sheet diameter of the graphene-based material sheet is preferably 7-20 μm, more preferably 10-18 μm, and more preferably 12-15 μm. The specific surface area of the graphene-based material is preferably 400-600 m ² /g, more preferably 420-580 m ² /g, more preferably 450-550 ^{m 2} /g.

The present invention has no special restrictions on the selection of solvents in the graphene-based material dispersion liquid, and the conventional solvents of the graphene-based material dispersion liquid well known to those skilled in the art can be used. Those skilled in the art can select according to actual application conditions and product requirements And quality requirements are selected and adjusted, the graphene material dispersion liquid of the present invention is the graphene material solution. The solvent of the graphene-based material dispersion preferably includes water and/or an organic solvent, more preferably water or an organic solvent. Wherein the organic solvent preferably includes one or more of ethanol, xylene, n-butanol, isopropanol, propylene glycol methyl ether, epoxy resin, acrylic resin, polyurethane and alkyd resin, more preferably ethanol, di Toluene, n-Butanol, Isopropanol, Propylene Glycol Methyl Ether, Epoxy, Acrylic, Polyurethane or Alkyd.

In principle, the present invention has no special limitation on the concentration of the graphene-based material dispersion, and the conventional concentration of the graphene-based material dispersion known to those skilled in the art will suffice. And quality requirements are selected and adjusted. The present invention can better quickly detect the dispersion performance and long-term storage stability of the graphene material dispersion, and the mass concentration of the graphene material dispersion is preferably 0.1% to 3%. , more preferably 0.5% to 2.5%, more preferably 1.0% to 2.0%.

In principle, the present invention is not particularly limited to the definition of the dispersed state and/or morphology of the graphene-based material in the dispersion system. It is enough to detect the situation, and those skilled in the art can select and adjust according to the actual application situation, product requirements and quality requirements. The dispersion state and/or morphology of the graphene material in the dispersion system of the present invention preferably include The dispersion state and morphology of graphene-based materials in the dispersion liquid system. Among them, metallographic detection can clearly see whether there is agglomeration of graphene-based materials, and through the depth of color and the distribution of materials, the degree of aggregation of graphene-based materials can be seen, which reflects the dispersion performance of graphene-based materials . At the same time, by analyzing the morphology of the material in the metallographic photograph, the morphology of the graphene-based material in the dispersion system can also be obtained.

In the present invention, the dispersion liquid of the graphene material is then centrifuged to obtain the centrifugal liquid;

Check the bottom of the centrate for clumping and/or for stratification.

In principle, the present invention has no special restrictions on the parameters of the centrifugal treatment, and those skilled in the art can select and adjust according to actual application conditions, product requirements and quality requirements. The present invention is capable of better and rapid detection of graphene material dispersions Dispersion properties and long-term storage stability, the rotational speed of the centrifugation is preferably changed in direct proportion to the concentration of the graphene dispersion, and inversely proportional to the time, the specific rotational speed is preferably 200 to 1000r/min, more preferably 300 to 900r/min, more preferably 400-800r/min, more preferably 500-700r/min. The time of the centrifugal treatment of the present invention is preferably changed in direct proportion to the concentration of the graphene dispersion, and inversely proportional to the rotation speed. The specific time is preferably 30 to 240 minutes, more preferably 60 to 210 minutes, more preferably 90 to 180 minutes, More preferably, it is 120 to 150 minutes.

In principle, the present invention has no special restrictions on the detection method for detecting the bottom of the centrifuged liquid. Those skilled in the art can select and adjust according to actual application conditions, product requirements and quality requirements. The present invention can better and quickly detect graphene The dispersion performance and long-term storage stability of the material dispersion liquid, standardize the detection method, the detection of the bottom of the centrifugate is specifically: place the centrifugation liquid vertically, and detect the bottom of the centrifugation liquid through a device. The device of the present invention preferably includes one or more of a paint spatula, a spatula and a glass rod, more preferably a paint spatula, a spatula or a glass rod.

The present invention is better able to quickly detect the dispersion performance and long-term storage stability of the graphene-based material dispersion, complete and refined detection method, and the step 2) is specifically preferably:

centrifuging the graphene material dispersion to obtain a centrifuge;

Check for clumping at the bottom of the centrate and/or observe for stratification;

When there is agglomeration and/or stratification at the bottom of the centrifugate, it indicates that the storage stability of the graphene-based material dispersion is unqualified;

When there is no agglomeration and/or stratification at the bottom of the centrifugate, proceed to step 4).

Wherein, the detecting whether there is agglomeration at the bottom of the centrifuged liquid, and/or observing whether there is a layering phenomenon is more specifically preferably detecting whether there is agglomeration at the bottom of the centrifuged liquid and observing whether there is a layering phenomenon.

When there is agglomeration and/or layering phenomenon observed at the bottom of the centrifugate, more preferably when there is agglomeration or layering phenomenon observed at the bottom of the centrifuge liquid, it is determined that the storage stability of the graphene material dispersion is poor and cannot meet long-term storage stability. sexual demands. When there is no agglomeration at the bottom of the centrifuge and/or there is stratification in observation, more preferably when there is no agglomeration at the bottom of the centrifugation and there is no stratification in observation, then it is determined that the storage stability of the graphene-based material dispersion is good and meets the requirements. For long-term storage stability requirements, follow-up testing is carried out.

In the present invention, after stirring the centrifugal liquid obtained in the above steps, the lower layer of the centrifugal liquid is taken for metallographic detection to obtain the dispersion state and/or morphology of the graphene material in the lower layer of the centrifugal liquid in the dispersion system.

In principle, the present invention has no special limitation on the parameters of the stirring, and those skilled in the art can select and adjust according to actual application conditions, product requirements and quality requirements. Dispersibility and long-term storage stability, the stirring is preferably low-speed stirring. The rotational speed of the stirring is preferably 40-70 r/min, more preferably 45-65 r/min, more preferably 50-60 r/min. The time of the centrifugal treatment in the present invention is preferably 30-240 min, more preferably 60-210 min, more preferably 90-180 min, more preferably 120-150 min.

In principle, the present invention is not particularly limited to the definition of the dispersion state and/or morphology of the graphene material in the lower layer of the centrifugal liquid in the dispersion system. The detection situation of the detection is enough, and those skilled in the art can select and adjust according to the actual application situation, product requirements and quality requirements, the dispersion state and/or Morphology preferably includes the dispersion state and morphology of the graphene material in the lower layer of the centrifugal liquid in the dispersion system.

In order to be able to better and accurately detect the dispersion performance and long-term storage stability of the dispersion liquid of graphene-based materials, the present invention refines the detection method to improve usability and parallelism. The metallographic detection method in the above steps is as follows: select different Perform multiple metallographic inspections at sampling points and/or select different microscopic metallographic fields of view for the same sample for multiple metallographic inspections. It is more preferable to select different sampling points for multiple metallographic inspections or to select different microscopic metallographic fields of view of the same sample for multiple metallographic inspections. Therefore, the metallographic detection can more accurately reflect the dispersion state of the graphene-like material in the detected dispersion liquid. The number of times in the present invention is preferably 2 to 10 times, more preferably 3 to 9 times, more preferably 5 to 7 times.

Finally, the present invention compares the metallographic detection results in step 1) and step 4) to judge the storage stability of the graphene material dispersion. That is, compare the dispersion state and/or morphology of the graphene-based material in the dispersion system in step 1) and step 4), and judge the storage stability of the graphene-based material dispersion.

The present invention has no particular limitation on the specific method of the comparison, and those skilled in the art can select and adjust according to actual application conditions, product requirements and quality requirements. The present invention is capable of better and rapid detection of graphene material dispersions Dispersibility and long-term storage stability, said comparison is specifically preferably:

In the metallographic examination results of step 1) and step 4), the consistency of the dispersion state and/or morphology of the graphene-based material is greater than or equal to 80%. The consistency is more preferably equal to or greater than 83%, more preferably equal to or greater than 85%, and more preferably equal to or greater than 90%.

That is, when the dispersion state and/or morphology of the graphene material in the lower layer of the centrifugal liquid in step 4) in the dispersion liquid system reaches the dispersion state and/or shape of the graphene material in the dispersion liquid system in step 1), When it is 80% of the appearance situation, then it is considered that the storage stability of the graphene material dispersion meets the requirements.

In principle, the present invention has no special limitation on the specific time of storage stability, and those skilled in the art can select and adjust according to actual application conditions, product requirements and quality requirements. The present invention can better quantify and improve the rapid detection of graphene The dispersibility of the material dispersion and the accuracy of the long-term storage stability, the storage stability is specifically preferably the storage stability within 12 months, more preferably the storage stability within 6 months.

The present invention is not particularly limited to the conditions and methods of storage, and the conditions and methods of conventional storage of the graphene material dispersion well known to those skilled in the art can be used. Quality requirements are selected and adjusted, and the storage in the present invention is preferably normal temperature storage and/or static storage. Among them, normal temperature is preferably 10 to 40°C.

The above steps of the present invention provide a rapid detection method for the storage stability of the graphene material dispersion. Using the rapid detection method provided by the present invention, the dispersion state and/or morphology of the graphene-based material in the lower layer of the finally obtained centrifugal liquid in the dispersion liquid system is the same as that of the graphene-based material dispersion liquid stored for 6 months. For the dispersion state and/or morphology of the lower layer of the dispersion under metallographic examination, the similarity is preferably greater than or equal to 90%, more preferably greater than or equal to 93%, more preferably greater than or equal to 95%.

Therefore, the present invention also provides a method for determining the storage stability of a graphene-based material dispersion, comprising the following steps:

1) After centrifuging and stirring the graphene-based material dispersion, the centrifugate is obtained;

The rotating speed of the centrifugal treatment is 200～1000r/min;

The time of the centrifugal treatment is 30-240min;

2) taking the lower layer of the centrifuge liquid for metallographic detection, and obtaining the dispersion state and/or morphology of the graphene material in the lower layer of the centrifuge liquid in the dispersion system;

The dispersion state and/or morphology of the graphene material in the lower layer of the centrifugal liquid in the dispersion system, and the dispersion under the metallographic detection of the lower layer of the dispersion liquid after the storage of the graphene material dispersion for 6 months State and/or morphology, the similarity is greater than or equal to 90%.

In the present invention, the selection and composition of the steps and parameters in the determination method, as well as the corresponding optimization principles, can correspond to the selection and composition of the corresponding steps in the aforementioned detection method, and the corresponding optimization principles. Let me repeat them one by one.

The judging method provided above in the present invention can be used to judge the storage stability of the graphene material dispersion within 6 months. That is, by observing the dispersion state and/or morphology of the graphene-like material in the lower layer of the centrifuge liquid in the dispersion liquid system, it is possible to quickly understand the graphene-like material dispersion in the dispersion liquid after storage for 6 months. dispersion state and/or morphology in the system. Therefore, it is possible to simply, conveniently and quickly determine whether its dispersion state meets the customer's requirements after storage for 6 months, or conduct subsequent graphene application experiments to detect whether the final application product meets the requirements.

The invention provides a rapid detection method and a rapid judgment method for the storage stability of a graphene-based material dispersion. Through the combination of centrifugal separation with specific parameters and low-speed stirring, especially the low-speed centrifugal technology, the graphene dispersion is prepared at a low speed. Under certain conditions, screening the storage stability of graphene dispersions can quickly detect the dispersibility of graphene material dispersions, especially the dispersibility and stability after long-term storage, effectively solving the problem of graphene dispersions in practice. In the application, there are poor dispersion, long-term storage and agglomeration, and the dispersion stability is difficult to determine. Compared with the current situation that its stability can only be detected after storage under actual natural conditions, the present invention is faster and easier, and is more convenient for customers in a short time. The performance of the product index can be judged within a certain period of time, and technical support can be provided for customers to judge the product, thus greatly improving the performance stability of subsequent products.

The detection method provided by the invention is convenient and fast, simple in operation, low in equipment cost, and has mild, simple and efficient conditions, greatly reduces time cost and detection cost, and is more suitable for industrial promotion and application.

Experimental results show that the present invention uses centrifugation to quickly determine the difference in dispersibility and stability of the graphene dispersion after long-term storage for 6 months. The dispersion state and/or morphology of the graphene material dispersion obtained by the method of the present invention is the same as the dispersion state and/or morphology of the metallographic detection of the lower layer of the dispersion after the graphene material dispersion was stored for 6 months. The similarity is greater than or equal to 90%.

In order to further illustrate the present invention, the detection method and the judging method of the storage stability of a kind of graphene material dispersion provided by the present invention are described in detail below in conjunction with the examples, but it should be understood that these examples are based on the technical solution of the present invention Carry out under the premise, have provided detailed embodiment and specific operation process, just for further illustrating the feature and advantage of the present invention, rather than restriction to the claims of the present invention, protection scope of the present invention is not limited to the following implementation example.

Example 1

Routine comparison experiments between well-dispersed products and poorly dispersed products

(1) Preparation of dispersion liquid: prepare two kinds of graphene dispersion liquids whose graphene content is 3%.

They are conventional graphene dispersion liquid with poor dispersion performance, number OBO-MG-1; and OBO graphene dispersion liquid with better dispersion performance, number OBO-MG-2;

(2) Comparative experiment under natural conditions: the two kinds of graphene dispersions of step 1) are respectively taken 50g, put it into a glass bottle with a diameter of 30mm and a height of 100mm, under natural conditions (temperature: 23 ± 2°C) , Humidity: 60±10RH) for 6 months.

Characterize the samples of the graphene dispersions OBO-MG-1 and OBO-MG-2 in Example 1 of the present invention after standing for 6 months.

Referring to Fig. 1, Fig. 1 is a photograph of the appearance of the graphene dispersions OBO-MG-1 and OBO-MG-2 provided by Example 1 of the present invention after being placed for 6 months. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

It can be seen from Figure 1 that the graphene dispersion liquid OBO-MG-1 with poor dispersion performance has obvious delamination phenomenon after being placed for 6 months, while the graphene dispersion liquid OBO-MG-2 with good dispersion performance does not There is no delamination.

(3) Observe the sample after step 2) for delamination with the naked eye, and use a spatula (paint knife) to go deep into the bottom to observe whether there is agglomeration, etc. If there is delamination and agglomeration, it proves that the dispersion liquid Poor storage stability.

The sample detection results of the graphene dispersion liquid OBO-MG-1 and OBO-MG-2 in Example 1 of the present invention after being placed for 6 months.

Referring to Fig. 2, Fig. 2 is a photo of the graphene dispersion liquid OBO-MG-1 and OBO-MG-2 provided by Example 1 of the present invention after being placed for 6 months and then sampled with a spatula. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

It can be seen from Figure 2 that after the graphene dispersion liquid OBO-MG-1 with poor dispersion performance was placed for 6 months, there was obvious agglomeration phenomenon in the sampling of the knife, while the graphene dispersion liquid OBO-MG-1 with better dispersion performance 2 After the knife is adjusted and sampled, it can still flow naturally in a fluid state.

(4) Take the lower layer of the two dispersions in step 2) after standing for 6 months, and observe their morphology characteristics under metallography.

The samples in Example 1 of the present invention were characterized by a metallographic microscope before and after 6 months of placement.

Referring to FIG. 3 , FIG. 3 is a metallographic microscope photo of the graphene dispersions OBO-MG-1 and OBO-MG-2 provided in Example 1 of the present invention before placement. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

Referring to Fig. 4, Fig. 4 is a metallographic microscope photo of the graphene dispersions OBO-MG-1 and OBO-MG-2 provided in Example 1 of the present invention after being placed for 6 months. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

It can be seen from Figure 3 and Figure 4 that after the graphene dispersion liquid with poor dispersion performance is placed for 6 months, the graphene sheets in the metallographic photographs have been obviously agglomerated, and the morphology has been completely distorted, while the graphene dispersion liquid with better dispersion performance After the dispersion was placed for 6 months, the graphene sheets in the metallographic photos did not appear to be obviously agglomerated, and only some graphene sheets were stacked in appearance, which increased slightly.

Example 2

Experimental comparison between the dispersed graphene dispersion liquid placed naturally for 6 months and the initial dispersion liquid directly centrifuged

(1) Preparation of the dispersion liquid: the OBO graphene dispersion liquid OBO-MG-2 in Example 1 was used.

Take 50g of the graphene dispersion in step 1), put it into a glass bottle with a diameter of 30mm and a height of 100mm, and place it under natural conditions (temperature: 23±2°C, humidity: 60±10RH) for 6 months.

(2) Take 45g of the graphene dispersion in step 1), put it into a 50ml centrifuge tube, and centrifuge for 4h at a rotating speed of 500r/min.

(3) With the sample after the step 2) experiment, observe with the naked eye whether there is delamination, and use a knife to go deep into the bottom to observe whether there are agglomerations, etc. If there is delamination and agglomeration, it proves that the dispersion liquid has poor storage stability.

Above-mentioned graphene dispersion liquid naturally places 6 months and the detection result of the graphene dispersion liquid sample after centrifugal treatment of the present invention.

Referring to FIG. 5 , FIG. 5 is a photo of the bottom layer of the graphene dispersion provided by Example 2 of the present invention placed naturally for 6 months and centrifuged with a spatula. Wherein, A is the graphene dispersion after being naturally placed for 6 months, and B is the graphene dispersion treated in Example 2 of the present invention.

It can be seen from Figure 5 that the two graphene dispersion liquids can flow naturally in a fluid state after sampling, and the states are basically the same.

(4) After the centrifugate obtained in the above step (2) was stirred for 1 min at a low speed of 60 r/min, a sample was obtained.

The graphene dispersion liquid is naturally placed for 6 months and the graphene dispersion liquid sample after the treatment of the present invention is detected.

Referring to Fig. 6, Fig. 6 is a photo of the appearance of the graphene dispersion liquid provided by Example 2 of the present invention after being placed naturally for 6 months and treated in the present invention. Wherein, A is the graphene dispersion liquid after being placed naturally for 6 months, and B is the graphene dispersion liquid treated in Example 2 of the present invention.

It can be seen from Figure 6 that the appearance of OBO-MG-2, a graphene dispersion with better dispersion performance, after being placed for 6 months is basically the same as that of the dispersion after the initial direct centrifugation treatment, and there is no delamination phenomenon.

(5) The samples in step 1) and step 2) were respectively stirred at a low speed of 60 r/min for 1 min, then the lower layer liquid was taken, and the morphology characteristics were observed under a metallographic microscope.

The graphene dispersion liquid OBO-MG-2 in Example 2 of the present invention was placed for 6 months and after being treated by the present invention, the metallographic microscope was used for characterization.

Referring to FIG. 7 , FIG. 7 is a metallographic microscope photo of the graphene dispersion liquid provided by Example 2 of the present invention after being placed naturally for 6 months and after initial treatment. Wherein, A is the graphene dispersion after being naturally placed for 6 months, and B is the graphene dispersion treated in Example 2 of the present invention.

It can be seen from Figure 7 that no obvious agglomeration phenomenon appeared in the metallographic photographs after the graphene dispersion was placed for 6 months and after the initial direct centrifugation treatment, and only some graphene sheets were stacked in appearance, which increased slightly. , and the two are basically the same in the size, shape and distribution of the flakes, and the consistency reaches 95%.

At the same time, for the above steps, the same sample was used to compare the microscopic metallographic fields of view three times, and the results were basically consistent.

Example 3

Centrifuge comparison of well-dispersed and poorly dispersed products.

(1) prepare dispersion liquid: take the poor graphene dispersion liquid of dispersibility among the embodiment 1 equally, numbering OBO-MG-1; .

(2) Take 45g of the graphene dispersion in step 1), put it into a 50ml centrifuge tube, and centrifuge for 4h at a rotating speed of 500r/min.

(3) Take the sample after the experiment in step 2) and use a spatula to go deep into the bottom to observe whether there is agglomeration, etc. If there is agglomeration, it proves that the dispersion liquid has poor storage stability.

The detection results of the above two graphene dispersion samples after centrifugation in Example 3 of the present invention.

Referring to Fig. 8, Fig. 8 is a photograph of sampling the bottom layer with a spatula after the two graphene dispersions provided in Example 3 of the present invention have undergone centrifugation and other steps. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

It can be seen from Figure 8 that after the graphene dispersion liquid OBO-MG-1 with poor dispersion performance is centrifuged, there is obvious agglomeration phenomenon in the sampling of the knife, which is the same as that of the same graphene dispersion liquid in Example 1. The agglomeration phenomenon after 6 months is the same, and the graphene dispersion liquid OBO-MG-2 that dispersion property is better can still be fluid state natural flow after sampling, this and same kind of graphene dispersion liquid in embodiment 1 naturally The fluid state after standing for 6 months was also the same.

(4) The centrifugate obtained in the above step (2) was stirred at a low speed of 60 r/min for 1 min to obtain a sample.

(5) Remove the lower layers of the samples in step 4) respectively, and observe their morphology characteristics under a metallographic microscope.

The two graphene dispersions provided in Example 3 of the present invention were respectively characterized by metallographic microscopy.

Referring to FIG. 9 , FIG. 9 is a metallographic microscope photo of two graphene dispersions provided in Example 3 of the present invention after treatment. Among them, A is the graphene dispersion liquid OBO-MG-1, and B is the graphene dispersion liquid OBO-MG-2.

It can be seen from Figure 9 that after the graphene dispersion liquid OBO-MG-1 with poor dispersion performance is centrifuged, the graphene sheets in the metallographic photographs have been obviously agglomerated, and the morphology has been completely distorted, which is the same as that in Example 1. The morphology of the same graphene dispersion in the metallographic photographs after 6 months of natural storage is basically the same. However, the graphene dispersion liquid OBO-MG-2 with better dispersion performance does not appear obvious agglomeration phenomenon, and only some graphene sheets are stacked in appearance, which increases slightly, which is the same as that of the same graphene dispersion in Example 1. The morphology in the metallographic photographs after the solution was naturally placed for 6 months was basically the same.

It can be seen from the comparison of Fig. 9 and Fig. 4 that the size, shape, color and distribution state of the two graphene dispersions are basically the same in the corresponding comparison after being naturally placed for 6 months and after the treatment of the present invention. , the consistency reached 90%.

At the same time, for the above steps, the two treated graphene dispersions were sampled three times for comparison with metallographic microscope observation, and the results were basically consistent.

Example 4

Experimental comparison of dispersed products under different centrifugation rates

(1) Preparation of dispersion liquid: take OBO graphene dispersion liquid with better dispersion performance in Example 1, numbered OBO-MG-2.

(2) Take 45g of the graphene dispersion in step 1), put it into a 50ml centrifuge tube, and centrifuge at 1000r/min for 1h and 1500r/min for 2h to observe.

(3) Take the sample after the experiment in step 2) and use a spatula to go deep into the bottom to observe whether there is agglomeration, etc. If there is agglomeration, it proves that the dispersion liquid has poor storage stability.

The detection results of the above two graphene dispersion liquid samples after centrifugation in Example 4 of the present invention.

Referring to Fig. 10, Fig. 10 is a photograph of sampling the bottom layer with a spatula after the two graphene dispersions provided in Example 4 of the present invention have undergone centrifugation and other steps. Wherein, A is the graphene dispersion liquid centrifuged for 1 h under the condition of 1000 r/min, and B is the graphene dispersion liquid centrifuged for 2 h under the condition of 1500 r/min.

As can be seen from Figure 10, the graphene dispersion processed by centrifugation for 1 h under the condition of 1000r/min can still flow naturally in a fluid state after the knife is adjusted and sampled, which is the same as that of the same graphene dispersion in Example 1 after being naturally placed for 6 months The fluid state is also the same. However, there is obvious agglomeration phenomenon in the graphene dispersion liquid that is processed by centrifugation for 2h under the condition of 1500r/min. , unable to reflect the true state after 6 months of natural placement.

(4) After the centrifugate obtained in the above step (2) was stirred for 1 min at a low speed of 60 r/min, a sample was obtained.

(5) Take the lower layers of 1h and 2h in step 4) respectively, and observe their morphology characteristics under metallography.

The two graphene dispersions provided in Example 4 of the present invention were respectively characterized by metallographic microscopy.

Referring to FIG. 11 , FIG. 11 is a metallographic microscope photo of two graphene dispersions provided in Example 4 of the present invention after treatment. Wherein, A is the graphene dispersion liquid centrifuged for 1 h under the condition of 1000 r/min, and B is the graphene dispersion liquid centrifuged for 2 h under the condition of 1500 r/min.

As can be seen from Figure 11, the graphene dispersion treated by centrifugation for 1 h under the condition of 1000r/min has no obvious agglomeration phenomenon, and only some graphene sheets are stacked in appearance, which increases slightly, which is the same as that in Example 1. The appearance in the metallographic photograph of a kind of graphene dispersion liquid placed naturally after 6 months is basically the same. But through the graphene dispersion that is centrifuged for 2h under the condition of 1500r/min, in the metallographic photograph, the graphene sheets have obviously agglomerated, and the shape has been completely distorted, which is the same as that of the same graphene dispersion in Example 1. The morphology in the metallographic photos after one month has obvious differences, which cannot reflect the true state after 6 months of natural storage.

The rapid detection method and rapid judgment method of the storage stability of a kind of graphene material dispersion provided by the present invention have been described in detail above, and specific examples have been used in this paper to illustrate the principle and implementation of the present invention. The above implementation The description of the example is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables anyone skilled in the art to practice the present invention, including making and using any device or system, and implementing any combination Methods. It should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims (9)

1. A method for detecting storage stability of a graphene material dispersion liquid is characterized by comprising the following steps:

1) Performing metallographic detection on the graphene material dispersion liquid to obtain the dispersion state and/or morphology condition of the graphene material in a dispersion liquid system;

2) Centrifuging the graphene material dispersion liquid to obtain a centrifugal liquid;

the rotation speed of the centrifugal treatment is 200 to 1000r/min;

the time of the centrifugal treatment is 30 to 240min;

detecting whether the bottom of the centrifugate is caked and/or whether the centrifugate is layered;

4) Stirring the centrifugate obtained in the step, and performing metallographic detection on the lower layer of the centrifugate to obtain the dispersion state and/or morphology condition of the graphene materials on the lower layer of the centrifugate in a dispersion system;

the stirring speed is 40 to 70r/min;

the stirring time is 1 to 5min;

5) Comparing the metallographic detection results obtained in the step 1) and the step 4) to judge the storage stability of the graphene material dispersion liquid.

2. The detection method according to claim 1, wherein the graphene-based material includes one or more of graphene, graphene oxide, reduced graphene oxide, and modified graphene;

the solvent of the graphene-based material dispersion liquid comprises water and/or an organic solvent;

the mass concentration of the graphene material dispersion liquid is 0.1% -3%.

3. The detection method according to claim 2, wherein the organic solvent comprises one or more of ethanol, xylene, n-butanol, isopropanol, propylene glycol methyl ether, epoxy resin, acrylic resin, polyurethane, and alkyd resin.

4. The detection method according to claim 1, wherein the detection of the bottom of the centrifugate specifically comprises:

vertically placing the centrifugate, and detecting the bottom of the centrifugate through a device;

the device comprises one or more of a paint mixing knife, a medicine spoon and a glass rod.

5. The detection method according to claim 2, wherein the step 2) is specifically:

centrifuging the graphene material dispersion liquid to obtain a centrifugal liquid;

detecting whether the bottom of the centrifugate is caked or not and/or observing whether the layering phenomenon exists or not;

when the bottom of the centrifugate has caking and/or layering, the storage stability of the graphene material dispersion liquid is unqualified;

step 4) is carried out when there is no caking at the bottom of the centrate and/or stratification is present.

6. The detection method of any one of claims 1~5 wherein the comparison is specifically:

in the metallographic detection results of the step 1) and the step 4), the consistency of the dispersion state and/or the morphology condition of the graphene material is more than or equal to 80%;

the storage stability is in particular a storage stability within 12 months.

7. The assay of any one of claims 1~5 wherein the storage stability is in particular storage stability over 6 months;

the similarity between the metallographic detection result obtained in the step 4) and the metallographic detection result obtained after the graphene material dispersion liquid is conventionally stored for 6 months is more than or equal to 90%.

8. The assay of any one of claims 1~5, wherein in step 1) and step 4), said metallographic assay is specifically: selecting different sampling points to perform multiple metallographic detection and/or selecting different microscopic metallographic fields of the same sample to perform multiple metallographic detection;

the number of the times is 2 to 10.

9. A method for judging storage stability of a graphene material dispersion liquid is characterized by comprising the following steps:

1) Centrifuging and stirring the graphene material dispersion liquid to obtain a centrifugal liquid;

the rotation speed of the centrifugal treatment is 200 to 1000r/min;

the time of the centrifugal treatment is 30 to 240min;

the rotation speed of stirring is 40 to 70r/min;

the stirring time is 1 to 5min;

2) Performing metallographic detection on the lower layer of the centrifugate to obtain the dispersion state and/or morphology of the graphene material on the lower layer of the centrifugate in a dispersion system;

the similarity between the dispersion state and/or morphology of the graphene material at the lower layer of the centrifugate in a dispersion system and the dispersion state and/or morphology of the graphene material at the lower layer of the dispersion after 6 months of storage of the graphene material dispersion under metallographic detection is more than or equal to 90%.

Images