CN113120887B - Graphene oily dispersion liquid for conductive ink, and preparation method and application thereof - Google Patents
Graphene oily dispersion liquid for conductive ink, and preparation method and application thereof Download PDFInfo
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- CN113120887B CN113120887B CN201911403634.0A CN201911403634A CN113120887B CN 113120887 B CN113120887 B CN 113120887B CN 201911403634 A CN201911403634 A CN 201911403634A CN 113120887 B CN113120887 B CN 113120887B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/182—Graphene
- C01B32/184—Preparation
- C01B32/19—Preparation by exfoliation
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/03—Printing inks characterised by features other than the chemical nature of the binder
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/10—Printing inks based on artificial resins
- C09D11/102—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
- C09D11/104—Polyesters
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/52—Electrically conductive inks
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2204/00—Structure or properties of graphene
- C01B2204/20—Graphene characterized by its properties
- C01B2204/32—Size or surface area
Abstract
The invention provides a graphene oily dispersion liquid which comprises the following components in percentage by mass of 0.1-10 parts by weight of expanded graphite, 0.1-5 parts by weight of dispersing agent, 0-8 parts by weight of conductive agent and 80-120 parts by weight of solvent; the solvent includes one or more of an ester solvent, a ketone solvent, and an alcohol solvent. According to the invention, the expanded graphite is used as a graphene raw material, a specific solvent is used as a matrix, and the graphene oily dispersion liquid is obtained through selection of an auxiliary agent and respective specific proportions. In the oily dispersion liquid, graphene can be uniformly dispersed in a specific organic solvent for oily graphite, and the graphene with large sheet diameter is obtained, and the graphene with large sheet diameter is kept in a sheet structure, is free from aggregation and curling, has good stability and dispersibility, better plays the performance of graphene, does not need to replace a solvent, can be directly used for printing ink, and is more beneficial to industrialized large-scale popularization and application.
Description
Technical Field
The invention belongs to the technical field of graphene, relates to graphene oily dispersion liquid and a preparation method and application thereof, and particularly relates to graphene oily dispersion liquid for conductive ink and a preparation method and application thereof.
Background
Conductive ink is used as a key electronic material and is increasingly widely applied to the market of printing electronic technology. Currently, commonly used types of conductive inks include: metal conductive ink, conductive polymer ink, and carbon conductive ink. The conductive performance of the metal conductive ink depends on the conductive phase, such as the common silver nano conductive ink, has excellent electrical conductivity and thermal conductivity, but is expensive, so that the mass production is not facilitated; copper nano conductive ink is lower in cost, but its limited application is caused by higher electron mobility resistance. The high-molecular conductive ink mainly refers to conductive ink taking polyethylene dioxythiophene, polyacetylene, polythiophene, polypyrrole and the like as fillers, but the processability of the conductive polymer is extremely limited due to the characteristics of high rigidity and insolubility of self molecular chains of the conductive polymer, and the conductive polymer is difficult to produce in a large scale. The traditional carbon conductive ink mostly uses graphite, carbon black, carbon fiber and the like as conductive fillers, has stable performance, low price and high cost performance, but has poor conductivity and moisture resistance, and can only be used for circuit printing with low conductivity requirement. Therefore, the search for a conductive filler with excellent processability, high cost performance and good stability is important for the development of conductive ink.
Graphene (Graphene) has excellent electrical, mechanical and thermal properties. The electron mobility of the graphene can reach 2 x 10 4 cm 2 ·V -1 ·S -1 The resistivity of the graphene at room temperature can reach 10 as high as 100 times that of silicon 8 S/m, tolerability 10 8 A/cm 2 Graphene has received much attention as a novel conductive agent. In the prior art, various graphene application modes are disclosed, such as simple graphene is added in a form of filling or dispersing in a solvent and a solvent, the process operation is very simple, but the graphene added in the process is unevenly dispersed in the conductive ink, and due to the fact that the specific surface area of the graphene is large, the surface energy is high, and the transverse dimension of the graphene is far beyond the thickness, the graphene is easy to curl and agglomerate under the shearing dispersion effect of conventional mechanical stirring, the effect is not ideal, irreversible stacking (stacking) or curling and agglomeration are easy to occur in the processing process, and the graphene is difficult to reopen, so that the dispersibility of the graphene is poor, and the theoretical performance advantage of the graphene cannot be exerted. At present, research is carried out on improving the dispersion effect of graphene by modifying graphene, but the dispersion effect is still poor, and meanwhile, the method has the limiting factors of complex process, high cost, inapplicability to large-scale production and the like, so that the popularization and the use of products are influenced. The simple grinding and sanding or ultrasonic modes, meanwhile, the graphene sheets are dispersed, and meanwhile, the sheet diameter of the graphene is damaged, so that the performance of the graphene is greatly influenced, the process is difficult to control, secondary agglomeration is extremely easy, the graphene is difficult to open again, and long-term stability cannot be provided; there have also been studies on the combined use of graphene and conductive carbon black, but the dispersion medium is an aqueous material, and the graphene is more difficult to disperse in an organic phase, which limits its use in conductive ink Is used in the field of applications. Moreover, the difficulty that graphene is difficult to prepare in large quantities and difficult to overcome agglomeration in the use process is always resisted the rapid development of graphene conductive paste. At present, the macro preparation method of graphene mainly comprises the following steps: 1) Graphene Oxide (GO) prepared by using a classical Hummers method is characterized in that a large amount of oxygen-containing groups are introduced into a lamellar layer under the action of strong acid and strong oxidizing agent, so that the problem of poor dispersibility of the graphene oxide is solved to a certain extent, but the conductivity of the graphene oxide is deteriorated after the structure of the graphene oxide is damaged, and environmental pollution exists in the preparation process. 2) The number of the graphene sheets prepared by the method is controllable, the quality is high, but the preparation conditions are harsh, the cost is high, and the industrialization of the graphene conductive ink is not facilitated. 3) The graphene prepared by the liquid phase stripping method has a relatively complete structure and excellent conductivity, but is often stripped by using a high boiling point solvent, so that the graphene is difficult to remove and the processability of the ink is affected.
Therefore, how to realize the preparation and uniform dispersion of graphene with low cost, high quality and easy dispersion is a key point of the trend of graphene conductive ink to industrialization, is a key point of further widening the application field and relieving the bottleneck problem of graphene application, and is one of the problems to be solved urgently for various research and development enterprises and a plurality of first-line researchers in the field.
Disclosure of Invention
In view of the above, the technical problem to be solved by the invention is to provide a graphene oily dispersion liquid and a preparation method thereof, in particular to a graphene oily dispersion liquid for conductive ink.
The invention provides a graphene oily dispersion liquid which comprises the following components in percentage by mass:
the solvent includes one or more of an ester solvent, a ketone solvent, and an alcohol solvent.
Preferably, the graphene oily dispersion liquid is obtained by homogenizing raw materials;
the ester solvent comprises dibasic acid ester and/or butyl acetate;
the ketone solvent comprises cyclohexanone and/or butanone;
the alcohol solvent comprises one or more of ethanol, isopropanol and n-butanol.
Preferably, the dispersant comprises one or more of PVP, SDS, SDBS, PVA, tween 80, polyethylene glycol, carboxylic acid-based cellulose and acetate-based cellulose;
the conductive agent comprises one or more of graphene, carbon nanotubes, conductive carbon black, ketjen black and acetylene black;
the graphene oily dispersion liquid contains graphene;
graphene sheets in the graphene oily dispersion liquid are distributed in a staggered manner;
the dispersing agent is attached to the surface of the graphene sheets and/or between the graphene sheets;
the graphene oily dispersion liquid is a graphene oily dispersion liquid for conductive ink.
Preferably, the graphene in the graphene oily dispersion liquid is few-layer graphene;
the sheet diameter of the graphene sheet layer in the graphene oily dispersion liquid is 1-30 mu m;
the thickness of the graphene sheet layer in the graphene oily dispersion liquid is 1-10 nm;
the conductive agent is attached to the surface of the graphene sheets and/or between the graphene sheets to form a conductive three-dimensional network;
the conductive agent is gathered at edges and/or folds of the graphene sheets.
Preferably, the fineness of the graphene oily dispersion liquid is 10-50 mu m;
the graphene oily dispersion liquid is stably dispersed, does not have sedimentation and does not delaminate for more than 2 years;
The viscosity of the graphene oily dispersion liquid is 50-20000 mpa.s.
The invention provides a preparation method of graphene oily dispersion liquid, which comprises the following steps:
1) Mixing and impregnating expanded graphite, a dispersing agent and a solvent to obtain an expanded graphite mixture;
2) Shearing and stripping the expanded graphite mixture obtained in the steps to obtain a pre-stripping dispersion liquid;
3) Homogenizing the pre-stripping dispersion liquid obtained in the steps to obtain the graphene oily dispersion liquid.
Preferably, the expanded graphite is obtained by expanding graphite by a thermal expansion method or a chemical expansion method;
the expanded graphite comprises vermicular expanded graphite;
the expansion multiplying power of the expanded graphite is 100-400;
the particle size of the expanded graphite is 20-200 meshes.
Preferably, the conductive agent is added before the mixed dipping treatment and/or before homogenization;
the time of the dipping treatment is 0.5-24 h;
the rotation speed of the shearing stripping is 500-5000 r/min;
the shearing stripping time is 0.5-24 h.
Preferably, the homogenizing pressure is 30-80 MPa;
the homogenizing temperature is 25-60 ℃;
the homogenizing time is 0.1-5 h;
the number of homogenizing times is 3-6.
The invention also provides the application of the graphene oily dispersion liquid according to any one of the technical schemes or the graphene oily dispersion liquid prepared by the preparation method according to any one of the technical schemes in the field of conductive ink.
The invention also provides conductive ink, which comprises the following components in percentage by mass:
preferably, the polyester resin carrier comprises a polyester resin solution;
the polyester resin comprises crystalline saturated polyester resin;
the molecular weight of the polyester resin is 5000-40000;
the solvent of the polyester resin solution comprises a lipid solvent;
the solvent of the polyester resin solution comprises one or more of diformate, butyl acetate, cyclohexanone, butanone, ethanol, isopropanol and n-butanol;
the mass ratio of the polyester resin to the solvent in the polyester resin solution is (2-4) 10;
the graphene oily dispersion liquid comprises graphene and a conductive agent;
the dispersant comprises one or more of PVP, PVA, SDS, carboxylic acid-based cellulose, polyethylene glycol, tween 80 and acetate-based cellulose.
Preferably, the leveling agent comprises one or more of diethylene glycol diethyl ether acetate, diethylene glycol butyl ether acetate, isophorone, polydimethylsiloxane, polymethylphenylsiloxane, polyether modified polydimethylsiloxane and diacetone alcohol;
The specific surface area of the fumed silica is 80-150 m 2 /g；
The average particle diameter of primary particles of the fumed silica is 20nm or less.
The invention provides a graphene oily dispersion liquid which comprises the following components in percentage by mass of 0.1-10 parts by weight of expanded graphite, 0.1-5 parts by weight of dispersing agent, 0-8 parts by weight of conductive agent and 80-120 parts by weight of solvent; the solvent includes one or more of an ester solvent, a ketone solvent, and an alcohol solvent. Compared with the prior art, the invention aims at the problems that in the existing graphene application, the structure is damaged, the conductivity is poor, and the preparation process has environmental pollution; the preparation conditions are harsh, the cost is high, industrialization is difficult, and the problems that the high boiling point solvent is difficult to remove, the processing performance of the ink is affected and the like exist. The invention aims at the existing graphene conductive ink, mainly comprises the steps of directly adding graphene powder into an ink system, and then using a three-roller machine to redisperse, but the graphene is difficult to uniformly disperse in the ink because the common three-roller machine is difficult to provide enough shearing force to overcome strong van der Waals force between graphene sheets, so that the electrical property of the graphene cannot be expected. The simple grinding and sanding or ultrasonic modes exist, the graphene sheets are small in diameter and broken, the graphene performance is affected, the process is difficult to control, secondary agglomeration is easy, the secondary agglomeration is difficult to open again, and long-term stability cannot be provided; and in addition, a small part of graphene slurry dispersion liquid is used, but the solvent system of the graphene slurry dispersion liquid is mostly N, N-dimethyl pyrrolidone, so that the graphene slurry dispersion liquid is difficult to remove, and the processing performance of the printing ink is affected.
According to the invention, the expanded graphite is creatively used as a graphene raw material, a specific solvent is used as a matrix, and the graphene oily dispersion liquid is obtained through selection of the auxiliary agent and specific proportion of each auxiliary agent. According to the invention, by utilizing the intercalation effect of the dispersing agent, the graphene oily dispersion liquid is prepared by the method of infiltration, pre-stripping and homogenization, so that the graphene lamellar can be uniformly dispersed in an oily solvent, the dispersion performance of graphene in an organic phase material is greatly improved, the prepared dispersion liquid has uniform dispersion of graphene, maintains a lamellar structure, is free from aggregation and curling, has better stability and dispersibility, does not need to replace a solvent, and can be directly used for printing ink. Meanwhile, the long-term stable dispersion performance can be maintained, layering and sedimentation are avoided after long-term placement, and the stable storage time of the product is effectively prolonged. According to the graphene oily dispersion liquid, graphene can be uniformly dispersed in an oily solvent in a lamellar structure, and the graphene with a large lamellar diameter is obtained, so that the performance of the graphene is better exerted, and the graphene oily dispersion liquid is excellent in product stability, dispersibility, conductivity and other performances, low in cost and easy to produce in a large scale. The graphene has not been chemically modified, and excellent electric conduction, heat conduction and mechanical properties of the graphene are greatly reserved. The dispersion liquid is obtained by adopting a combination mode of infiltration, pre-stripping and homogenization, and the preparation process flow is simple and efficient, thereby being beneficial to large-scale production. The system adopts esters, ketones and alcohols as stripping solvents to prepare graphene dispersion liquid, avoids the difficulty of removing the solvents in the using process, adopts the solvents commonly used for oily ink, and can be directly added into most oily ink systems.
The invention effectively solves the problems that the graphene oxide is poor in conductivity and is difficult to meet the requirements when the graphene ink is used as a conductive additive in the prior graphene ink; most of the graphene additives are powder, so that the difficult problems of graphene agglomeration and difficult redispersion are difficult to overcome. And the graphene dispersion liquid is prepared by mixing a plurality of solvents with high boiling points which are difficult to remove, so that the influence on the performance of an ink system is large, the preparation process is complex, the preparation process is simple, the conditions are mild and controllable, and the method is favorable for industrialized large-scale popularization and application.
Experimental results show that the graphene oily dispersion liquid prepared by the method has the advantages that graphene sheets are uniformly dispersed, the graphene sheet structure is complete, curling and agglomeration do not occur, and the sheet diameter size is large and can reach more than 25 mu m. Meanwhile, graphene sheets are distributed in the graphene oily dispersion liquid in a staggered mode, and the oily dispersion liquid has good stability.
Drawings
FIG. 1 is a schematic process flow diagram of a graphene oily dispersion provided by the invention;
FIG. 2 is an SEM image of the oily dispersion of graphene prepared in example 1 of the present invention;
FIG. 3 is an external view of a graphene oily dispersion prepared by the present invention;
FIG. 4 is an SEM image of the oily dispersion of graphene prepared in example 2 of the present invention;
FIG. 5 is an SEM image of the oily dispersion of graphene prepared in example 2 of the present invention;
FIG. 6 is an SEM image of an oily dispersion of graphene prepared in example 3 of the present invention;
FIG. 7 is an SEM image of an oily dispersion of graphene prepared in example 3 of the present invention;
FIG. 8 is an SEM image of an oily dispersion of graphene prepared in example 3 of the present invention;
FIG. 9 is an SEM image of an oily dispersion of graphene prepared in example 4 of the present invention;
FIG. 10 is an SEM image of an oily dispersion of graphene prepared in example 4 of the present invention;
FIG. 11 is an SEM image of an oily dispersion of graphene prepared in example 4 of the present invention;
FIG. 12 is an SEM image of a graphene high pressure dispersion prepared according to comparative example 1 of the present invention;
FIG. 13 is an SEM image of a graphene high pressure dispersion prepared according to comparative example 1 of the present invention;
FIG. 14 is an SEM image of a graphene high pressure dispersion prepared according to comparative example 1 of the present invention;
fig. 15 is an SEM electron microscope image of the graphene conductive ink coating film prepared in example 5 of the present invention.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention and are not limiting of the invention claims.
All the raw materials of the present invention are not particularly limited in their sources, and may be purchased on the market or prepared according to conventional methods well known to those skilled in the art.
All raw materials of the invention are not particularly limited in purity, and the invention preferably adopts analytically pure or conventional purity requirements in the field of graphene preparation.
All raw materials of the invention, the brands and abbreviations of which belong to the conventional brands and abbreviations in the field of the related application are clear and definite, and the person skilled in the art can purchase from the market or prepare by the conventional method according to the brands, abbreviations and the corresponding application.
The invention provides a graphene oily dispersion liquid which comprises the following components in percentage by mass:
the solvent includes one or more of an ester solvent, a ketone solvent, and an alcohol solvent.
The parameters of the expanded graphite are not particularly limited in principle, and can be selected and adjusted according to practical application conditions, product requirements and quality requirements by common parameters of the expanded graphite known to those skilled in the art, and the expanded graphite preferably comprises vermicular expanded graphite in order to ensure the dispersibility and stability of the graphene oily dispersion liquid, improve the thinness of graphene sheets and the sheet diameter size, and be more beneficial to conductive ink. The expansion ratio of the expanded graphite is preferably 100 to 400, more preferably 150 to 350, and even more preferably 200 to 300. The S content of the expanded graphite may be 10 to 50ppm, or 15 to 45ppm, or 20 to 40ppm. The graphite content of the expanded graphite is preferably 90 to 99.5%, more preferably 92 to 99%, and still more preferably 95 to 98.5%. The Fe content of the expanded graphite is preferably 50ppm or less, more preferably 40ppm or less, and still more preferably 30ppm or less. The expanded graphite of the present invention is preferably one obtained by expanding graphite by a thermal expansion method or a chemical expansion method. The particle size of the expanded graphite of the present invention is preferably 20 to 200 mesh, more preferably 40 to 180 mesh, still more preferably 60 to 160 mesh, still more preferably 80 to 140 mesh, still more preferably 100 to 120 mesh. The amount of the expanded graphite to be added in the present invention is 0.1 to 10 parts by weight, preferably 0.5 to 9.5 parts by weight, more preferably 1 to 9 parts by weight, still more preferably 3 to 7 parts by weight, and still more preferably 4 to 6 parts by weight.
The specific selection of the dispersing agent is not particularly limited in principle, and the dispersing agent is selected and adjusted according to the parameters of the conventional expanded graphite known to those skilled in the art, and the skilled person can select and adjust the dispersing agent according to the practical application situation, the product requirement and the quality requirement.
The dispersant of the present invention is added in an amount of 0.1 to 5 parts by weight, preferably 0.5 to 4.5 parts by weight, more preferably 1 to 4 parts by weight, still more preferably 1.5 to 3.5 parts by weight, still more preferably 2 to 3 parts by weight.
The specific choice of the conductive agent is not particularly limited in principle, and the conductive agent is selected and adjusted according to the parameters of common expanded graphite known to those skilled in the art, and the skilled person can select and adjust the conductive agent according to practical application conditions, product requirements and quality requirements.
The amount of the conductive agent of the present invention added is 0 to 8 parts by weight, preferably 1 to 7 parts by weight, more preferably 2 to 6 parts by weight, and still more preferably 3 to 5 parts by weight.
The invention is used for ensuring the dispersibility and stability of the graphene oily dispersion liquid, improving the thinness and the sheet diameter size of graphene sheets, and being more beneficial to conductive ink, wherein the solvent particularly comprises one or more of an ester solvent, a ketone solvent and an alcohol solvent, more preferably an ester solvent, a ketone solvent or an alcohol solvent, and even more preferably an ester solvent. In particular, the ester solvent preferably includes a dibasic ester and/or butyl acetate, more preferably a dibasic ester or butyl acetate, and still more preferably a dibasic ester. The ketone solvent preferably comprises cyclohexanone and/or butanone, more preferably cyclohexanone or butanone. The alcohol solvent preferably includes one or more of ethanol, isopropanol and n-butanol, more preferably ethanol, isopropanol or n-butanol.
The solvent of the present invention is added in an amount of 80 to 120 parts by weight, preferably 85 to 115 parts by weight, more preferably 90 to 110 parts by weight, and still more preferably 95 to 105 parts by weight.
The graphene oily dispersion liquid is preferably obtained by homogenizing a raw material, and more preferably is obtained by soaking, pre-stripping and homogenizing stripping the raw material. The invention simultaneously completes the peeling of the expanded graphite in the raw material and the intercalation of the dispersing agent between the graphite sheets, and obtains the graphene oily dispersion liquid containing graphene.
The parameters of the graphene are not particularly limited in principle, and according to the formula of the graphene, a person skilled in the art can select and adjust the graphene according to practical application conditions, compound conditions and product performances, so as to ensure the dispersibility and stability of the graphene oily dispersion, improve the thinness and the sheet diameter size of graphene sheets, and be more beneficial to conductive ink, the graphene in the graphene oily dispersion preferably comprises single-layer graphene and few-layer graphene, more preferably fewer-layer graphene, and particularly preferably the graphene with the sheet layer being less than or equal to 5 layers has a ratio of preferably greater than or equal to 80%, more preferably greater than or equal to 85%, and more preferably greater than or equal to 90%. The thickness of the graphene sheet layer is preferably 1 to 10nm, more preferably 2 to 8nm, more preferably 3 to 6nm, and more preferably 4 to 5nm. The graphene sheet of the present invention preferably has a sheet diameter of 1 to 30. Mu.m, more preferably 5 to 25. Mu.m, and still more preferably 10 to 20. Mu.m. This is because a very small amount of graphene fragments are inevitably present in the graphene sheets, and the sheet diameter range thereof is in the above-described small range, as expressed strictly. In practice, in the present invention, the graphene is more preferably large-diameter graphene, more preferably 10 to 30 μm, more preferably 12 to 28 μm, more preferably 14 to 26 μm, more preferably 16 to 24 μm, more preferably 18 to 22 μm.
According to the invention, the graphene sheets in the graphene oily dispersion liquid are smaller in thinness, larger in sheet diameter size and good in dispersibility, and the graphene sheets are distributed in the graphene oily dispersion liquid in a staggered manner, and the dispersing agent is attached on the surface of the graphene sheets and/or between the graphene sheets, preferably between the surface of the graphene sheets and the graphene sheets, so that the graphene oily dispersion liquid is more favorable for forming the staggered distribution of graphene, and the overlapping of the sheets is reduced, so that the graphene oily dispersion liquid has better dispersibility and stability and other excellent performances, and is more favorable for serving as the graphene oily dispersion liquid for conductive ink.
The present invention is not particularly limited in principle to the performance parameters of the oily dispersion of graphene, and those skilled in the art can select and adjust the dispersion according to practical application, product requirements and quality requirements, and the fineness of the dispersion after the above formulation is preferably 10 to 50 μm, more preferably 15 to 45 μm, more preferably 20 to 40 μm, more preferably 25 to 35 μm. The time for which the graphene oily dispersion is stably dispersed without sedimentation and delamination is preferably 2 years or longer, more preferably 1.5 years or longer, and still more preferably 1 year or longer. The viscosity of the graphene oily dispersion is preferably 50 to 20000mpa.s (rotor viscometer, rotation speed 30 rpm/min), more preferably 100 to 10000mpa.s, still more preferably 500 to 5000mpa.s, still more preferably 1000 to 3000mpa.s.
According to the invention, the graphene sheets in the graphene oily dispersion liquid are smaller in thinness, larger in sheet diameter size and good in dispersibility, the graphene sheets are distributed in the graphene oily dispersion liquid in a staggered manner, and a conductive agent can be added. And the conductive agent is more preferably gathered at the edges and/or folds of the graphene sheets, and more preferably gathered at the edges and folds of the graphene sheets, so that the framework of the conductive network is further improved.
The invention also provides a preparation method of the graphene oily dispersion liquid according to any one of the technical schemes, which comprises the following steps:
1) Mixing and impregnating expanded graphite, a dispersing agent and a solvent to obtain an expanded graphite mixture;
2) Shearing and stripping the expanded graphite mixture obtained in the steps to obtain a pre-stripping dispersion liquid;
3) Homogenizing the pre-stripping dispersion liquid obtained in the steps to obtain the graphene oily dispersion liquid.
The selection and composition of the raw materials and the corresponding preferred principles in the preparation method of the graphene oily dispersion liquid can be corresponding to the selection and composition of the raw materials corresponding to the graphene oily dispersion liquid and the corresponding preferred principles, and are not described in detail herein.
The invention firstly carries out mixed dipping treatment on the expanded graphite, the dispersing agent and the solvent to obtain an expanded graphite mixture.
The invention is an integral and refined process, improves the dispersibility and stability of the graphene oily dispersion liquid, ensures the integrity of the sheet diameter size to the maximum extent on the premise of improving the thinness of graphene sheets, is more beneficial to conductive ink, and is preferably added with a conductive agent before the mixed dipping treatment. The conductive agent of the present invention may be added before the mixing and impregnating treatment and/or before the homogenizing, more preferably the conductive agent is added before the mixing and impregnating treatment or before the homogenizing, still more preferably the conductive agent is added before the homogenizing.
The method and parameters of the mixed impregnation are not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product requirements and quality requirements. The time of the mixed impregnation treatment is preferably 0.5 to 24 hours, more preferably 2.5 to 22 hours, still more preferably 5.5 to 20 hours, still more preferably 7.5 to 18 hours, still more preferably 10.5 to 15 hours.
In particular, the first step before homogenization is the impregnation treatment, and the key point of the method is that the solvent and the dispersing agent are fully infiltrated between the expanded graphite layers, so that the solvent commonly used in an ink system can be better used as a graphene stripping solvent.
The invention then subjects the expanded graphite mixture obtained in the above step to shearing and stripping to obtain a pre-stripping dispersion.
The specific parameters of the shearing stripping are not particularly limited in principle, and can be selected and adjusted according to actual production conditions, product requirements and quality requirements by a person skilled in the art, so that the dispersibility and stability of the graphene oily dispersion are improved, the integrity of the sheet diameter dimension is ensured to the greatest extent on the premise of improving the thinness of graphene sheets, the shearing stripping is more beneficial to conductive ink, and the rotating speed of the shearing stripping is preferably 500-5000 r/min, more preferably 1500-4000 r/min, and more preferably 2500-3000 r/min. The time for the shear peeling is preferably 0.5 to 24 hours, more preferably 2.5 to 22 hours, more preferably 5.5 to 20 hours, more preferably 7.5 to 18 hours, more preferably 10.5 to 15 hours.
And finally homogenizing the pre-stripping dispersion liquid obtained in the steps to obtain the graphene oily dispersion liquid.
The invention is an integral and refined process, improves the dispersibility and stability of the graphene oily dispersion liquid, ensures the integrity of the sheet diameter size to the maximum extent on the premise of improving the thinness of graphene sheets, is more beneficial to conductive ink, and is preferably added with a conductive agent before homogenization. The conductive agent of the present invention may be added before the mixing and impregnating treatment and/or before the homogenizing, more preferably the conductive agent is added before the mixing and impregnating treatment or before the homogenizing, still more preferably the conductive agent is added before the homogenizing.
The method and the parameters of the homogenization are not particularly limited in principle, and can be selected and adjusted by a person skilled in the art according to actual production conditions, product requirements and quality requirements, and the method is used for improving the dispersibility and the stability of the graphene oily dispersion, ensuring the integrity of the sheet diameter dimension to the greatest extent on the premise of improving the thinness of the graphene sheet layer, and being more beneficial to conductive ink, wherein the homogenization pressure is preferably 30-80 Mpa, more preferably 40-70 Mpa, and even more preferably 50-60 Mpa. The homogenizing time is preferably 0.1 to 5 hours, more preferably 0.5 to 4.5 hours, more preferably 1 to 4 hours, more preferably 1.5 to 3.5 hours, more preferably 2 to 3 hours. The homogenization mode of the invention is preferably multiple homogenization. The number of cycles is preferably 3 to 6, more preferably 4 to 5, and may be 3, 4, 5 or 6.
According to the specific technical scheme for preparing the graphene oily dispersion liquid, the preparation method comprises the steps of soaking, shearing and stripping, and homogenizing and stripping. According to the invention, the ultrasonic preparation process for dispersing the traditional graphene is abandoned, meanwhile, the used raw materials are expanded graphite instead of the finished products of various graphene powder, and the preparation cost of the graphene oily dispersion is greatly reduced in terms of energy consumption and raw materials by homogenizing the expanded graphite, the solvent and the dispersing agent after soaking, shearing and stripping.
According to the graphene oily dispersion liquid, the intercalation effect of the dispersing agent enables the peeled graphene sheets to be uniformly dispersed in a solvent for conductive ink, large-diameter graphene sheets are distributed in a staggered manner, and then a conductive agent is combined to form a conductive three-dimensional network, so that the graphene oily dispersion liquid with excellent comprehensive performance is obtained. The graphene can be uniformly and stably dispersed in the oily solvent, and the graphene can be ensured to exist in a lamellar structure in an organic phase system, so that the unique characteristics of the graphene cannot be lost, and the defect that the graphene is difficult to exert the unique advantages in the subsequent application of the existing graphene composite material is overcome. Compared with the existing grinding methods and the like or the method of adding a large amount of metal or inorganic nonmetal conductive fillers in the grinding process, the graphene oily dispersion liquid prepared by the method has the advantages of large graphene sheet diameter, small damage, no need of grinding medium, low cost and simple process, and is suitable for industrial scale-up production. The graphene oily dispersion liquid provided by the invention can replace some conventional conductive additives for conductive ink, can improve or change certain properties of the conductive ink, such as electric conduction, corrosion resistance, heat conduction, mechanical properties and the like, and has good application prospects in the field of conductive ink.
The invention has the advantages of ensuring the dispersibility and stability of the graphene oily dispersion liquid, improving the thinness and the sheet diameter size of graphene sheets, being more beneficial to conductive ink, along with complete and refined integral preparation process, and the preparation steps can be as follows:
a) Infiltration: mixing the expanded graphite with the dispersing agent and the solvent, and placing and soaking the mixture to enable the solvent and the dispersing agent to be fully soaked between the expanded graphite layers.
B) Pre-stripping: and C), shearing the graphite dispersion liquid in the step A), and peeling the expanded graphite to obtain the preliminary peeled graphene dispersion liquid.
C) Homogenizing and stripping: and B), carrying out high-pressure homogenization treatment on the graphene dispersion liquid subjected to preliminary shearing and stripping in the step B) and the conductive agent to obtain single-layer or less-layer graphene dispersion liquid.
Referring to fig. 1, fig. 1 is a schematic process flow diagram of a graphene oily dispersion liquid provided by the invention.
The invention also provides the application of the graphene oily dispersion liquid according to any one of the technical schemes or the graphene oily dispersion liquid prepared by the preparation method according to any one of the technical schemes in the field of conductive ink.
The invention is not particularly limited in principle for specific classification of the conductive ink, and a person skilled in the art can select and adjust the conductive ink according to actual production conditions, product requirements and quality requirements.
The invention provides a graphene oily dispersion liquid for conductive ink, and a preparation method and application thereof. The graphene oily dispersion liquid for the conductive ink provided by the invention forms a compound with large-diameter graphene stably dispersed in an oil-soluble matrix, so that the graphene oily dispersion liquid has better stability and comprehensive performance, the dispersing agent is more beneficial to preventing the graphene sheet layer from overlapping in a conductive ink system, the conductive agent is added to be more beneficial to the formation of a conductive three-dimensional network, and the dispersion liquid has better dispersibility, stability, conductive performance and other performances. The invention effectively solves the problems that a large amount of superconducting carbon black is added in a similar method for stripping expanded graphite in the prior art, the cost is high, the dispersion medium is an aqueous material, the ink with an organic phase cannot be applied, the long-term stability is poor, and the like. The invention further creates a new direction of a homogenizing process, adopts specific homogenizing process parameters and a specific formula, and solves the problem that graphene obtained by the existing homogenizing process is small in sheet diameter and small in sheet diameter, so that the network formation is not facilitated. In the same way, the defect that most of the prior art adopts a grinding process to prepare dispersion liquid, so that the process is complex, a grinding medium is needed, the graphene sheet diameter is too small, and the performance is influenced is overcome.
The invention uses expanded graphite as a raw material, particularly dibasic ester and the like as a solvent, polyvinylpyrrolidone and the like as a dispersing agent, and adopts soaking, shearing and high-pressure homogenization methods to obtain graphene dispersion liquid. The solvent particularly adopts a common ink system solvent as a graphene stripping solvent, so that the problems of agglomeration and difficult redispersion of graphene into powder during processing are avoided, the solvent does not influence the performance of the ink system, the raw materials are cheap, the process is extremely simple, the oily graphene dispersion liquid is obtained in one step, the problem of difficult redispersion of graphene can be effectively avoided during the use process, the solvent is not required to be replaced, and the industrial large-scale production is very facilitated.
According to the invention, the dispersing agent is only added into the conventional organic solvent of the conductive ink, and the graphene oily dispersion liquid for the conductive ink, which is intercalated by the dispersing agent and the conductive agent, is obtained through repeated impregnation, pre-stripping and homogenization stripping of specific parameters, so that the dispersion stability of the graphene oily dispersion liquid is greatly improved on the basis that the thermal and electrical properties of graphene are not influenced, and the graphene oily dispersion liquid has better electrochemical properties.
According to the graphene oily dispersion liquid and the preparation method, the graphene oily dispersion liquid is produced by adopting a homogenizing process, the process flow is optimized, the product is safe and environment-friendly, the cost is greatly reduced, the stability of the product meets the requirement, the dispersion performance is superior to that of the existing product in the market, the graphene oily dispersion liquid has a very wide application prospect in the modern industrial field, the defects of complex preparation process, higher cost, unavoidable long-term placement layering problem and the like of the existing graphene oily dispersion liquid in the market are effectively solved, the problems of difficult dispersion and difficult preservation of the existing graphene in downstream application are solved, the large-scale popularization and application of the graphene downstream are facilitated, the process is simple, the cost is low, the condition is mild and controllable, the whole preparation process is safe and pollution-free, and the industrialized large-scale popularization and application are facilitated.
Experimental results show that the graphene oily dispersion liquid prepared by the method has the advantages that graphene sheets are uniformly dispersed, the graphene sheet structure is complete, curling and agglomeration do not occur, and the sheet diameter size is large and can reach more than 25 mu m. Meanwhile, graphene sheets are distributed in the graphene oily dispersion liquid in a staggered mode, and the oily dispersion liquid has good stability.
In order to further illustrate the present invention, the following detailed description is provided with reference to examples, which are provided to illustrate the features and advantages of the present invention, but not to limit the claims of the present invention, and it should be understood that the embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation and specific operation process are given.
Example 1
1) Polyethylene glycol-2000 was dissolved in dibasic ester to give a dispersant solution having a concentration of 1wt%.
2) And (2) adding expanded graphite into the dispersing agent solution obtained in the step (1), and carrying out infiltration for 2 hours to ensure that the expanded graphite sheets are fully infiltrated, wherein the concentration of the expanded graphite in a mixed system of the expanded graphite, the dispersing agent and the solvent is 4wt%.
3) And (3) shearing and pre-stripping the fully-infiltrated expanded graphite dispersion liquid obtained in the step (2), wherein the shearing rate is 500r/min, and the time is 2h, so as to obtain the pre-stripped graphene dispersion liquid.
4) Homogenizing the pre-exfoliated graphene dispersion liquid obtained in the step 3 and 1% of conductive carbon black, wherein the homogenizing pressure is 40Mpa, and the homogenizing time is 10min, so as to obtain graphene oily dispersion liquid.
The graphene oily dispersion prepared in the embodiment 1 of the invention is characterized, and a scanning electron microscope is used for shooting pictures.
Referring to fig. 2, fig. 2 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 1 of the present invention.
As is clear from fig. 2, the graphene sheets are uniformly dispersed in the graphene oily dispersion liquid, and the graphene is present in a sheet-like structure, and is free from curling and aggregation, and has a large sheet diameter size of at least 10 μm. Meanwhile, graphene sheets are distributed in the graphene oily dispersion liquid in a staggered mode, the conductive agent is attached between the surface of the graphene sheets and the graphene sheets, a three-dimensional conductive network composed of graphene sheets and conductive carbon black is formed, and the conductive agent is gathered at the edges and folds of the graphene sheets more, so that the framework of the conductive network is improved.
Stability test was performed on the graphene oily dispersion prepared in example 1 of the present invention.
Referring to fig. 3, fig. 3 is an external view of a graphene oily dispersion prepared according to the present invention.
The test method used in the quick detection method and the quick determination method for the storage stability of the graphene material dispersion liquid is disclosed by the invention, which has no unified test standard and reference application number 201811526717.4, and the result shows that the storage stability of the graphene oily dispersion liquid prepared in the embodiment 1 of the invention is more than 1 year.
Performance detection was performed on the graphene oily dispersion prepared in example 1 of the present invention.
In order to effectively characterize the conductivity of the prepared graphene, the graphene oily dispersion liquid prepared in the embodiment 1 is dried to obtain graphene powder, the graphene powder is pressed into tablets (the pressure is 25Mpa, the time is 150S), and four probes are used for testing the conductivity of the powder, wherein the conductivity of the powder is 400S/cm.
Example 2
1) Polyethylene glycol-200 was dissolved in isopropanol to give a dispersant solution having a concentration of 1wt%.
2) And (2) adding expanded graphite into the dispersing agent solution obtained in the step (1), and carrying out infiltration for 2 hours to ensure that the expanded graphite sheets are fully infiltrated, wherein the concentration of the expanded graphite in a mixed system of the expanded graphite, the dispersing agent and the solvent is 4wt%.
3) And (3) shearing and pre-stripping the fully-infiltrated expanded graphite dispersion liquid obtained in the step (2), wherein the shearing rate is 1000r/min, and the time is 4 hours, so as to obtain the pre-stripped graphene dispersion liquid.
4) Homogenizing the pre-exfoliated graphene dispersion liquid obtained in the step 3 and 1% of carbon nanotubes, wherein the homogenizing pressure is 40Mpa, and the homogenizing time is 15min, so as to obtain the graphene/carbon nanotube composite dispersion liquid.
The graphene oily dispersion prepared in example 2 of the present invention was characterized, and a picture was taken with a scanning electron microscope.
Referring to fig. 4, fig. 4 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 2 of the present invention.
Referring to fig. 5, fig. 5 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 2 of the present invention.
As can be seen from fig. 4 and fig. 5, in the graphene oily dispersion liquid prepared by the method, graphene sheets are thin, have large sheet diameter size and good dispersibility, curling and agglomeration do not occur, meanwhile, the graphene sheets are distributed in the graphene oily dispersion liquid in a staggered manner, and carbon nanotube conductive agents are attached between the surfaces of the graphene sheets and the graphene sheets to form a three-dimensional conductive network composed of graphene sheets and conductive agents, and the conductive agents tend to be gathered at edges and folds of the graphene sheets, so that the framework of the conductive network is improved.
Performance detection was performed on the graphene dispersion prepared in example 2 of the present invention.
In order to effectively characterize the conductivity of the prepared graphene, the graphene dispersion liquid prepared in the embodiment 2 is dried to obtain graphene powder, tabletting (pressure: 25Mpa, time: 150S) is carried out, and four probes are used for testing the conductivity of the powder, wherein the conductivity of the powder is 700S/cm.
Example 3
1) Polyvinylpyrrolidone was dissolved in butanone to obtain a dispersant solution having a concentration of 1wt%.
2) And (2) adding expanded graphite into the dispersing agent solution obtained in the step (1), and carrying out infiltration for 2 hours to ensure that the expanded graphite sheets are fully infiltrated, wherein the concentration of the expanded graphite in a mixed system of the expanded graphite, the dispersing agent and the solvent is 4wt%.
3) And (3) shearing and pre-stripping the fully-infiltrated expanded graphite dispersion liquid obtained in the step (2), wherein the shearing rate is 1000r/min, and the time is 4 hours, so as to obtain the pre-stripped graphene dispersion liquid.
4) And (3) homogenizing the pre-exfoliated graphene dispersion liquid obtained in the step (3), wherein the homogenizing pressure is 70Mpa, and the homogenizing time is 1h, so as to obtain the graphene oily dispersion liquid.
The graphene oily dispersion prepared in example 3 of the present invention was characterized, and a picture was taken with a scanning electron microscope.
Referring to fig. 6, fig. 6 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 3 of the present invention.
Referring to fig. 7, fig. 7 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 3 of the present invention.
As can be seen from fig. 6 and 7, in the graphene oily dispersion liquid prepared by the method, graphene sheets are thin, have large sheet diameter size and good dispersibility, curling and agglomeration do not occur, meanwhile, the graphene sheets are distributed in the graphene oily dispersion liquid in a staggered manner, and the dispersing agent is attached between the surface of the graphene sheets and the graphene sheets, so that the formation of staggered graphene distribution is facilitated, and the overlapping of the sheets is reduced. (the material of the dispersant cannot be shown in SEM and therefore cannot be seen from the figure)
Referring to fig. 8, fig. 8 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 3 of the present invention.
As can be seen from FIG. 8, in the graphene oily dispersion prepared by the invention, graphene sheets are thin, the size of the sheets is large, the sheets are complete, the sheets are about 20-25 μm, curling and agglomeration do not occur, and the dispersion is good.
Example 4
1) Polyvinylpyrrolidone was dissolved in dibasic ester to obtain a dispersant solution having a concentration of 1wt%.
2) And (2) adding expanded graphite into the dispersing agent solution obtained in the step (1), and carrying out infiltration for 2 hours to ensure that the expanded graphite sheets are fully infiltrated, wherein the concentration of the expanded graphite in a mixed system of the expanded graphite, the dispersing agent and the solvent is 2wt%.
3) And (3) shearing and pre-stripping the fully-infiltrated expanded graphite dispersion liquid obtained in the step (2), wherein the shearing rate is 1500r/min, and the time is 4 hours, so as to obtain the pre-stripped graphene dispersion liquid.
4) And (3) homogenizing the pre-exfoliated graphene dispersion liquid obtained in the step (3), wherein the homogenizing pressure is 60Mpa, and the homogenizing time is 1h, so as to obtain the graphene dispersion liquid.
The graphene oily dispersion prepared in example 4 of the present invention was characterized, and a picture was taken with a scanning electron microscope.
Referring to fig. 9, fig. 9 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 4 of the present invention.
Referring to fig. 10, fig. 10 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 4 of the present invention.
As can be seen from fig. 9 and 10, in the graphene oily dispersion liquid prepared by the method, graphene sheets are thin, have large sheet diameter size and good dispersibility, curling and agglomeration do not occur, meanwhile, the graphene sheets are distributed in the graphene oily dispersion liquid in a staggered manner, and the dispersing agent is attached between the surface of the graphene sheets and the graphene sheets, so that the formation of staggered graphene distribution is facilitated, and the overlapping of the sheets is reduced. (the material of the dispersant cannot be shown in SEM and therefore cannot be seen from the figure)
Referring to fig. 11, fig. 11 is an SEM scanning electron microscope image of the graphene oily dispersion prepared in example 4 of the present invention.
As can be seen from FIG. 11, in the graphene oily dispersion prepared by the invention, graphene sheets are thin, the size of the sheets is large, the sheets are complete, the sheets are about 20-25 μm, curling and agglomeration do not occur, and the dispersion is good.
Comparative example 1
1) Polyvinylpyrrolidone was dissolved in N, N-dimethylpyrrolidone to obtain a dispersant solution having a concentration of 1wt%.
2) And (2) adding expanded graphite into the dispersing agent solution obtained in the step (1), and carrying out infiltration for 2 hours to ensure that the expanded graphite sheets are fully infiltrated, wherein the concentration of the expanded graphite in a mixed system of the expanded graphite, the dispersing agent and the solvent is 5wt%.
3) And (3) shearing and pre-stripping the fully-infiltrated expanded graphite dispersion liquid obtained in the step (2), wherein the shearing rate is 1500r/min, and the time is 4 hours, so as to obtain the pre-stripped graphene dispersion liquid.
4) And (3) homogenizing the pre-exfoliated graphene dispersion liquid obtained in the step (3), wherein the homogenizing pressure is 200Mpa, and the homogenizing time is 10min, so as to obtain the graphene high-pressure dispersion liquid.
The graphene dispersion prepared in comparative example 1 of the present invention was characterized, and a picture was taken with a scanning electron microscope.
Referring to fig. 12, fig. 12 is an SEM scanning electron microscope image of the graphene high-pressure dispersion prepared in comparative example 1 of the present invention.
Referring to fig. 13, fig. 13 is an SEM scanning electron microscope image of the graphene high-pressure dispersion prepared in comparative example 1 of the present invention.
Referring to fig. 14, fig. 14 is an SEM scanning electron microscope image of the graphene high-pressure dispersion prepared in comparative example 1 of the present invention.
As can be seen from fig. 12 to 14, the graphene dispersion liquid prepared by homogenization under high pressure has small graphene sheet diameter, the sheets are seriously incomplete, more graphene fragments appear, and the conductivity of the graphene dispersion liquid is seriously affected.
Example 5
1) The graphene oily dispersion liquid was the graphene oily dispersion liquid prepared in example 1.
2) And dissolving the polyester resin in a lipid solvent at the dissolution temperature of 80-100 ℃ for 4-8 hours to obtain the polyester resin carrier.
3) 5 parts of dispersing agent, 1 part of leveling agent and 0.5 part of fumed silica are added into 70 parts of polyester resin carrier, and shearing and dispersing are carried out by a high-speed dispersing machine, so as to obtain mixed solution.
4) And (3) adding 80 parts of the graphene oily dispersion liquid obtained in the step (1) into the mixed solution obtained in the step (three), and grinding by a three-roller machine until the fineness of the slurry is compounded with the standard, thereby obtaining the graphene conductive ink.
Performance testing was performed on the graphene conductive ink prepared in example 5 of the present invention.
The graphene conductive ink prepared in the above example was coated on a PET film, and was heated at 130 ℃ for 10min by a forced air drying oven, and after the coated film was completely dried, performance test was performed.
The results showed that the conductive ink coating film prepared in example 5 of the present invention had a coating film adhesion (cross-cut method) of 0 grade, a coating film thickness of 15 μm and a coating film sheet resistance of 15.2 Ω/≡/mil.
The graphene conductive ink coating film obtained in example 5 of the present invention was characterized.
Referring to fig. 15, fig. 15 is an SEM electron microscope image of the graphene conductive ink coating film prepared in example 5 of the present invention.
As can be seen from fig. 15, in the coating film structure, graphene sheets are alternately distributed to form a three-dimensional conductive network of graphene sheets. The graphene sheets are uniformly distributed throughout the film and embedded in the resin matrix of the conductive ink.
The conductive agent is attached between the surface of the graphene sheet layer and the graphene sheet layer to form a conductive three-dimensional network, and the conductive agent can almost cover the whole graphene surface and between the sheets. And the conductive agent is bonded by resin to form an aggregate (such as a grape-string-like aggregate) which is attached to the surface of the graphene sheet layer and between the sheets.
The present invention provides a graphene oily dispersion for conductive ink, and a preparation method and application thereof, and a detailed description is given above, and specific examples are provided herein to illustrate the principles and embodiments of the present invention, and the description of the examples is only for the purpose of helping understand the method and its core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including making and using any devices or systems, and implementing any combined methods. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims. The scope of the patent protection is defined by the claims and may include other embodiments that occur to those skilled in the art. Such other embodiments 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 (5)
1. The graphene oily dispersion liquid for the conductive ink is characterized by comprising the following components:
0.1-10 parts by weight of expanded graphite;
0.1-5 parts by weight of a dispersing agent;
0-8 parts by weight of a conductive agent;
80-120 parts by weight of a solvent;
the solvent is one or more of an ester solvent, a ketone solvent and an alcohol solvent;
the ester solvent is dibasic acid ester and/or butyl acetate;
the ketone solvent is cyclohexanone and/or butanone;
the alcohol solvent is one or more of ethanol, isopropanol and n-butanol;
the dispersing agent is one or more of PVP, SDS, SDBS, PVA, tween 80, polyethylene glycol and carboxylic acid group cellulose;
the conductive agent is one or more of graphene, carbon nanotubes, conductive carbon black, ketjen black and acetylene black;
the expanded graphite is vermiform expanded graphite;
the expansion multiplying power of the expanded graphite is 100-400;
the graphene oily dispersion liquid contains graphene;
the graphene in the graphene oily dispersion liquid is few-layer graphene;
the thickness of the graphene sheet layer in the graphene oily dispersion liquid is 1-10 nm;
Graphene sheets in the graphene oily dispersion liquid are distributed in a staggered manner;
the dispersing agent is attached between the surface of the graphene sheet and the graphene sheet;
the preparation method of the graphene oily dispersion liquid comprises the following steps:
1) Mixing and impregnating expanded graphite, a dispersing agent and a solvent to obtain an expanded graphite mixture;
the mode of the mixed dipping treatment is placing dipping treatment;
the time of the dipping treatment is 0.5-24 hours;
2) Shearing and stripping the expanded graphite mixture obtained in the steps to obtain a pre-stripping dispersion liquid;
the rotation speed of the shearing stripping is 500-5000 r/min;
the shearing and peeling time is 0.5-24 h;
3) Homogenizing the pre-stripping dispersion liquid obtained in the step to obtain graphene oily dispersion liquid;
the preparation method is characterized in that no conductive agent is added, or the conductive agent is added before mixing and soaking treatment and/or before homogenization;
the homogenizing pressure is 30-80 MPa;
the homogenizing temperature is 25-60 ℃;
the homogenizing time is 0.1-5 h;
the times of homogenization are 3-6 times;
the sheet diameter of the graphene sheet layer in the graphene oily dispersion liquid is 10-30 mu m;
the graphene oily dispersion liquid is stably dispersed for more than or equal to 2 years without sedimentation and delamination.
2. The graphene oily dispersion according to claim 1, wherein the conductive agent is attached on the surface of graphene sheets and/or between graphene sheets, forming a conductive three-dimensional network;
the conductive agent is gathered at edges and/or folds of the graphene sheets.
3. The graphene oily dispersion according to any one of claims 1 to 2, wherein the fineness of the graphene oily dispersion is 10 to 50 μm;
the viscosity of the graphene oily dispersion liquid is 50-20000 mPa.s.
4. The graphene oily dispersion according to claim 1, wherein the expanded graphite is obtained by expanding graphite by a thermal expansion method or a chemical expansion method;
the particle size of the expanded graphite is 20-200 meshes.
5. The application of the graphene oily dispersion liquid according to any one of claims 1-4 in the field of conductive ink.
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| CN107689452A (en) * | 2017-09-04 | 2018-02-13 | 多凌新材料科技股份有限公司 | A kind of graphene composite conductive slurry, its preparation method and application |
| CN113122072A (en) * | 2019-12-30 | 2021-07-16 | 山东欧铂新材料有限公司 | Graphene conductive ink for heating film and preparation method thereof |
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| CN107689452A (en) * | 2017-09-04 | 2018-02-13 | 多凌新材料科技股份有限公司 | A kind of graphene composite conductive slurry, its preparation method and application |
| CN113122072A (en) * | 2019-12-30 | 2021-07-16 | 山东欧铂新材料有限公司 | Graphene conductive ink for heating film and preparation method thereof |
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