A powder rubber conductive material coagulated by electrochemical exfoliation of graphene and a preparation method thereof

Abstract

The application discloses a kind of powder rubber conductive material by electrochemical exfoliation graphene promotes condensation and preparation method thereof, it is related to powder rubber preparation technical field, to solve the problem that existing method is not simple enough, product performance needs to be promoted;The application includes that anode piece is placed in electrolyte, through anodic electrolysis graphite material, while generating graphene, slowly add rubber emulsion, at this time, the graphene that anode is electrolyzed is combined with latex particle, and promotes condensation process in electrolyte, then after separation, washing, drying, obtain powder rubber;The application realizes electrochemical exfoliation graphene promoting condensation effect synchronously in electrolysis process, obtains conductive powder rubber, step is simple and easy to operate, and the powder rubber prepared has small particle size size and high powder rate, and particle is not easy to stick between, and dispersibility is good, and conductive performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of powdered rubber preparation technology, specifically to a conductive powdered rubber material produced by electrochemically exfoliated graphene and its preparation method. Background Technology

[0002] Pure rubber is a material with very low electrical conductivity. Conductivity can be achieved by doping rubber with conductive particles, such as metals and inorganic non-metallic particles. Alternatively, as described in patent application CN103923359A, entitled "A Conductive Graphene / Natural Rubber Nanocomposite Material and its Preparation Method," a composite material is obtained by chemically modifying graphene, mixing it with latex, and then drying it. However, its highest electrical conductivity is only 1.5 × 10⁻⁶. (-6) S / m.

[0003] The invention patents CN104817695B (titled "A Polyaniline Composite Conductive Powder and Its Preparation Method") and CN109181042A (titled "An Epoxy-Modified Conductive Powder and Its Preparation Method") describe the preparation of conductive powder rubber by dispersing waste rubber powder in an organic solvent and then chemically modifying it. The conductivity of the two materials reached 5 S / cm and 0.03 S / cm, respectively. The raw material for this method must be in the form of powder rubber. Due to its unique morphological characteristics, powder rubber can save many rubber cutting processes in rubber processing, or it can be directly injection molded or extruded with compounding agents, which can save equipment investment and reduce energy consumption.

[0004] Currently, common methods for preparing powdered rubber include pulverization, coagulation, and irradiation crosslinking. Pulverization includes cryogenic pulverization and room-temperature pulverization, which uses solid rubber as raw material and cools it below its glass transition temperature using a cooling medium, or uses mechanical force to shear and crush it at room temperature. However, this method is costly and requires specialized equipment. Coagulation uses liquid latex as raw material and adds additives such as release agents and flocculants to coagulate it into rubber particles. However, this method requires a large amount of release agents. Irradiation crosslinking is a method that does not introduce release agents or coagulants. It uses latex as raw material and irradiates it with high-energy rays to completely vulcanize the latex particles, thus producing powdered rubber. However, due to the excessively high degree of crosslinking, it cannot be used in the manufacture of rubber products.

[0005] The invention patent application with publication number CN103319632A, entitled "A Method for Preparing Powdered Rubber," discloses a method of adding a coagulant and a release agent, stirring evenly, and then adding latex to form powder. This method is the coagulation method. In terms of cost and subsequent processability, the coagulation method is undoubtedly the optimal solution among several methods. However, its preparation process requires the cooperation of various organic reagents, involves many steps, and is relatively cumbersome. How to improve the amount of release agent added or improve the dispersibility of the release agent to promote the coagulation process remains an unsolved problem.

[0006] Both the invention patent with announcement number CN104629123B, entitled "A Method for Liquid-Phase Mixing of Carbon Black into Powdered Rubber," and the invention patent application with publication number CN102070729A, entitled "A Low-Temperature Preparation Method of Powdered Rubber," employ a method without adding coagulants or separating agents, and both can also obtain powdered rubber. However, in order to separate the latex particles, the above methods require solution stirring and mixing, and before producing powdered rubber, solution preparation and pretreatment of parameters such as temperature and pH are necessary. The steps are not simple enough, and the improvement of material dispersibility by simply stirring and mixing is relatively limited.

[0007] Therefore, there is an urgent need for a powdered rubber conductive material and its preparation method that promotes the aggregation of graphene through electrochemical exfoliation to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a powdered rubber conductive material and its preparation method that promotes the aggregation of graphene by electrochemical exfoliation, so as to solve the problems that the existing methods are not simple enough and the product performance needs to be improved.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a conductive powdered rubber material by electrochemically exfoliating graphene to promote coagulation, comprising the following steps: placing cathode and anode sheets in an electrolyte, electrolyzing graphite material at the anode to generate graphene, while slowly adding rubber latex, at which point the graphene electrolyzed at the anode combines with latex particles and promotes the coagulation process in the electrolyte, and then separating, washing, and drying to obtain powdered rubber.

[0010] Preferably, the agglomeration process is carried out simultaneously with the electrolytic exfoliation of graphene.

[0011] Preferably, the cathode and anode plates are made of inert electrode plates.

[0012] Preferably, the cathode and anode plates are made of titanium or platinum.

[0013] Preferably, the graphite material is graphite paper, highly oriented pyrolytic graphite, or isostatic graphite, and is in the form of blocks, plates, or sheets, and is in close contact with the anode sheet.

[0014] Preferably, the electrolyte is a sulfate or persulfate electrolyte.

[0015] Preferably, the weight ratio of dry rubber content in the rubber latex to the portion of graphite material that can be completely electrolyzed into graphene is 100:(5-30); the electrolyte concentration is 0.1mol / L to 1mol / L; and the electrolysis voltage is 10V to 20V.

[0016] Preferably, the latex is nitrile rubber latex or natural rubber latex; before slowly adding the rubber latex to the electrolyte, it is first diluted with water or a plasticizer to facilitate addition, and the addition rate is 2 ml / min.

[0017] Preferably, a 100-300 mesh sieve is added to the electrolyte to separate the anode and cathode. When adding the rubber latex, it is added to the cathode side of the sieve to reduce the formation of flocculation that adheres to the anode electrode sheet.

[0018] The powdered rubber conductive material prepared by the above method has a particle size of less than 0.9 mm, a powder yield of more than 90%, and an electrical conductivity of more than 0.4 S / m.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. This method for preparing conductive powdered rubber by electrochemically exfoliating graphene promotes coagulation. During electrolysis, the electrochemical exfoliation of graphene promotes coagulation, resulting in conductive powdered rubber. The steps are simple and easy to operate. When latex is added to the electrolyte, the latex particles combine with the graphene sheets exfoliated at the anode. Because the low-concentration electrolyte cannot rapidly coagulate the latex, sufficient time is provided for the graphene and rubber to encapsulate and separate, thus promoting coagulation. The preparation process requires no external mechanical stirring or pretreatment, nor the addition of coagulants or isolating agents. This method has a high powder yield, simple equipment, and can be used and stopped immediately with a power switch. Residual electrolyte can be recycled, and no waste gas or wastewater is generated, making it green and environmentally friendly.

[0021] 2. This conductive powder rubber material, which is agglomerated by electrochemically exfoliated graphene, has a small particle size and high powder yield. The particles are not easily stuck together, have good dispersibility, and excellent conductivity. Detailed Implementation

[0022] A method for preparing a conductive powdered rubber material by electrochemically exfoliating graphene to promote agglomeration includes the following steps: placing anode and cathode sheets in an electrolyte, electrolyzing graphite material at the anode to generate graphene, and simultaneously slowly adding a rubber latex (the latex can be nitrile rubber latex or natural rubber latex, etc.). To facilitate addition, the rubber latex should be diluted with water or a plasticizer before being slowly added to the electrolyte. The plasticizer can be dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, etc., and a reference addition rate of 2 ml / min is recommended. At this time, the graphene electrolyzed at the anode combines with the latex particles and promotes the agglomeration process in the electrolyte. After separation, washing, and drying, powdered rubber is obtained.

[0023] The aforementioned condensation process occurs simultaneously with the electrolytic exfoliation of graphene.

[0024] Inert electrode plates, such as titanium or platinum, should be used for the cathode and anode plates.

[0025] The graphite material can be graphite paper, highly oriented pyrolytic graphite, or isostatic graphite, etc., and can be in the form of blocks, plates, or sheets. It should be in close contact with the anode sheet, for example, by clamping it with a fixture.

[0026] In this preparation method, the electrolyte can be a sulfate or a persulfate.

[0027] In a preferred embodiment, the weight ratio of the dry rubber content in the rubber latex to the portion of the graphite material that can be completely electrolyzed into graphene is 100:(5-30); the electrolyte concentration is 0.1mol / L to 1mol / L; and the electrolysis voltage is 10V to 20V.

[0028] In addition, a 100-300 mesh sieve can be added to the electrolyte to separate the anode and cathode. Its function is to reduce the formation of flocculation that adheres to the electrode sheet. At the same time, the sieve holes can also allow the electrolyzed graphene to pass through. Specifically, latex can be added to the cathode side of the sieve.

[0029] The powdered rubber conductive material prepared according to the above preparation method has a particle size of less than 0.9 mm, the particles are not easily stuck together, the powder formation rate is higher than 90%, and the electrical conductivity is higher than 0.4 S / m, exhibiting excellent performance.

[0030] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention. The raw materials and instruments used in the embodiments are not specifically limited in their source and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0031] Example 1: Take 100g of natural rubber latex with a dry rubber content of 60%, and dilute it with pure water until it is easy to add dropwise (the dry rubber content after dilution is 30%). Prepare 1L of 0.1mol / L ammonium persulfate solution as the electrolyte. Take two titanium sheets as the anode and cathode electrodes, and take 10g of graphite paper of the corresponding size as the electrolytic material, and fix it on the anode electrode sheet with a clamp. Place the titanium sheets into the electrolytic cell containing the electrolyte, and install a sieve in the cell to facilitate the passage of electrolyzed graphene and prevent the formation of flocculation that adheres to the electrode sheet. Set the voltage to 10V and start electrolysis. As the graphite paper is electrolyzed, the graphene is rapidly electrolyzed and diffuses to the other side through the sieve. At the same time, add latex at a rate of 2mL / min. When the latex addition is complete, filter, wash with pure water, and dry in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 5% of the mass remains. Take an appropriate amount of adhesive powder, press it into a thin sheet using a press, and test it using a four-probe conductivity meter. The average conductivity was calculated to be 0.56 S / m.

[0032] Example 2: 133g of nitrile rubber latex with a solid content of 45% was diluted with dioctyl phthalate to a consistency suitable for easy addition (dry rubber content after dilution was 25%). 1L of 1mol / L ammonium persulfate solution was prepared as the electrolyte. Two titanium sheets were used as the anode and cathode electrodes, and 10g of graphite paper of the appropriate size was used as the electrolytic material, fixed to the anode electrode with clamps. The titanium sheets were placed in an electrolytic cell containing the electrolyte, and a sieve was installed in the cell to facilitate the passage of electrolyzed graphene and prevent latex from entering the electrolytic side and agglomerating. The voltage was set to 15V, and electrolysis began. As the graphite paper was electrolyzed, the graphene was rapidly electrolyzed and diffused to the other side through the sieve. Simultaneously, latex was added at a rate of 2mL / min. When the latex addition was complete, the mixture was filtered, washed with pure water, and dried in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 4% of the mass remained. Take an appropriate amount of adhesive powder, press it into a thin sheet using a press, and test it using a four-probe conductivity meter. The average conductivity is calculated to be 0.50 S / m.

[0033] Example 3: Take 100g of natural rubber latex with a dry rubber content of 60%, and dilute it with pure water until it is easy to add dropwise (the dry rubber content after dilution is 30%). Prepare 1L of 0.1mol / L magnesium sulfate solution as the electrolyte. Take two titanium sheets as the anode and cathode electrodes, and take 10g of a correspondingly sized highly oriented pyrolytic graphite sheet as the electrolytic material, and fix it on the anode electrode sheet with a clamp. Place the titanium sheet into the electrolytic cell containing the electrolyte, and install a sieve in the cell to facilitate the passage of electrolyzed graphene and prevent latex from entering the electrolytic side and agglomerating. Set the voltage to 20V and start electrolysis. As the graphite paper is electrolyzed, the graphene is rapidly electrolyzed and diffuses to the other side through the sieve. At the same time, add latex at a rate of 2ml / min. When the latex addition is complete, filter, wash with pure water, and dry in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 4% of the mass remains. Take an appropriate amount of adhesive powder, press it into a thin sheet using a press, and test it using a four-probe conductivity meter. The average conductivity was calculated to be 0.46 S / m.

[0034] Example 4: 133g of nitrile rubber latex with a solid content of 45% was diluted with dioctyl phthalate to facilitate dripping (dry rubber content after dilution was 20%). 1L of 1mol / L magnesium sulfate solution was prepared as the electrolyte. Two titanium sheets were used as the anode and cathode electrodes, and 10g of graphite paper of the appropriate size was used as the electrolytic material, fixed to the anode electrode with a clamp. The titanium sheets were placed in the electrolytic cell containing the electrolyte. The voltage was set to 15V, and electrolysis began. As the graphite paper electrolyzed, graphene was rapidly electrolyzed and diffused towards the cathode. Simultaneously, latex was added at a rate of 2mL / min. When the latex dripping was complete, the mixture was filtered, washed with pure water, and dried in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 8% of the mass remained. An appropriate amount of the rubber powder was taken, pressed into thin sheets, and tested using a four-probe conductivity meter. The average conductivity was calculated to be 0.43 S / m.

[0035] Example 5: Take 100g of natural rubber latex with a dry rubber content of 60%, and dilute it with pure water until it is easy to add dropwise (the dry rubber content after dilution is 30%). Prepare 1L of 0.1mol / L aluminum sulfate solution as the electrolyte. Take two titanium sheets as the anode and cathode electrodes, and take an isostatic graphite plate (10g) of the corresponding size as the electrolytic material, and fix it on the anode electrode with a clamp. Place the titanium sheets into the electrolytic cell containing the electrolyte. Set the voltage to 20V and start electrolysis. As the graphite paper is electrolyzed, graphene is rapidly electrolyzed and diffuses into the cathode. At the same time, add latex at a rate of 2mL / min. When the latex addition is complete, filter, wash with pure water, and dry in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 9% of the mass remains. Take an appropriate amount of rubber powder, press it into thin sheets, and test it with a four-probe conductivity meter. The average conductivity is calculated to be 0.41S / m.

[0036] Example 6: 133g of nitrile rubber latex with a solid content of 45% was diluted with dioctyl phthalate to facilitate dripping (dry rubber content after dilution was 30%). 1L of 1mol / L aluminum sulfate solution was prepared as the electrolyte. Two titanium sheets were used as the anode and cathode electrodes, and 10g of isostatically pressed graphite plate of the corresponding size was used as the electrolytic material and fixed to the anode electrode using a clamp. The titanium sheets were placed in the electrolytic cell containing the electrolyte. The voltage was set to 20V, and electrolysis began. As the graphite paper was electrolyzed, graphene was rapidly electrolyzed and diffused towards the cathode. Simultaneously, latex was added at a rate of 2mL / min. When the latex dripping was complete, the mixture was filtered, washed with pure water, and dried in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 8% of the mass remained. Take an appropriate amount of adhesive powder, press it into a thin sheet using a press, and test it using a four-probe conductivity meter. The average conductivity was calculated to be 0.42 S / m.

[0037] Comparative Example 1: First, graphene powder was prepared and then added to latex to coagulate. Powdered rubber was not prepared by the simultaneous electrolysis coagulation method in this invention, resulting in a decrease in both powder yield and electrical conductivity.

[0038] Take 100g of natural rubber latex with a dry rubber content of 60%, dilute it with pure water to a dry rubber content of 30%, and set aside. Prepare 1L of 0.1mol / L ammonium persulfate solution as the electrolyte. Take two titanium sheets as the anode and cathode electrodes, and take 10g of graphite paper of the appropriate size as the electrolytic material, and fix it on the anode electrode with a clamp. Place the titanium sheets into the electrolytic cell containing the electrolyte, set the voltage to 10V, and start electrolysis. After electrolysis is completed, remove the graphene solution, filter it, and spray dry it into powder. Add the electrolyte solution and graphene powder to the latex using a general coagulation method, stirring while adding. When the whey and powder of the latex separate, coagulation is considered complete. At this point, filter, wash with pure water, and dry in a vacuum drying oven at 80℃ to obtain powdered rubber. After sieving through a 20-mesh sieve, 15% of the mass remains. Take an appropriate amount of adhesive powder, press it into a thin sheet using a press, and test it using a four-probe conductivity meter. The average conductivity was calculated to be 0.11 S / m.

[0039] Comparative Example 2: Rubber powder is made conductive through chemical modification. The process of preparing conductive rubber powder without the method of this invention is relatively complicated and the conductivity is low.

[0040] Montmorillonite powder was calcined at 800℃ for 2 hours, cooled to room temperature, and added to anhydrous ethanol at twice its weight. Epichlorohydrin was added, the temperature was raised to 55℃, and the mixture was stirred for 30 minutes to obtain an epoxy dispersion. Lauryl dimethylamine oxide, water, and zinc borate were mixed and added to deionized water at nine times the weight of the mixture. The mixture was stirred evenly to obtain a zinc borate emulsion. The epoxy dispersion and zinc borate emulsion were mixed, sonicated for 20 minutes, and the ethanol was removed by distillation to obtain the epoxy emulsion.

[0041] Dicumyl peroxide was added to anhydrous ethanol at 13 times its weight and stirred until homogeneous to obtain an initiator solution. Calcium stearate and thiophene were mixed and stirred at 55°C for 20 minutes. This mixture was then added to anhydrous ethanol at 7 times its weight and stirred until homogeneous. Trimethylhydroxyethyl ethylenediamine was added and stirred until room temperature was reached to obtain a modified monomer solution. This modified monomer solution was transferred to a reaction vessel, nitrogen gas was introduced, and the reaction vessel temperature was adjusted to 70°C. The above initiator solution was added, and the mixture was stirred for 5 hours. After cooling, the product was discharged to obtain amination-modified polythiophene. Ammoniated polythiophene solution; Take waste rubber powder and saturated octadecamide, add them to a 75% ethanol solution with twice the weight of the mixture, keep it at 70℃ and stir for 2 hours to obtain a rubber powder solution; Take the rubber powder solution and epoxy emulsion, mix them, stir evenly, send them to a reaction vessel, adjust the reaction vessel temperature to 120℃, add ammoniated polythiophene solution, keep it at 70℃ and stir for 3 hours, discharge the material, add stannous sulfide, stir to room temperature, filter, wash the filter cake with water, dry it at room temperature, and obtain modified conductive rubber powder with a conductivity of 0.03 S / m.

[0042] The data from the example are shown in Table 1 below:

[0043] Table 1: Experimental data for each embodiment

[0044]

[0045] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

[0046] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A method for preparing a powdered rubber conductive material by electrochemically exfoliating graphene to promote aggregation, characterized in that, The process includes the following steps: placing the anode and cathode plates in an electrolyte, electrolyzing graphite material at the anode to produce graphene, and simultaneously slowly adding rubber latex. At this time, the graphene electrolyzed at the anode combines with the latex particles, and the coagulation process is promoted in the electrolyte. After separation, washing, and drying, powdered rubber is obtained. The anode and cathode plates are inert electrode plates. The electrolyte concentration is 0.1 mol / L to 1 mol / L.

2. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The condensation process is carried out simultaneously with the electrolytic exfoliation of graphene.

3. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The cathode and anode plates are made of titanium or platinum.

4. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The graphite material is made of graphite paper, highly oriented pyrolytic graphite, or isostatic graphite, and it is in close contact with the anode sheet.

5. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 4, characterized in that: The graphite material is in block shape.

6. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 4, characterized in that: The graphite material is in the shape of a plate.

7. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 4, characterized in that: The graphite material is in the form of flakes.

8. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The electrolyte is a sulfate or persulfate electrolyte.

9. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The weight ratio of the dry rubber content in the rubber latex to the portion of the graphite material that can be completely electrolyzed into graphene is 100:(5-30); the electrolysis voltage is 10V-20V.

10. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: The latex is nitrile rubber latex or natural rubber latex. Before slowly adding the rubber latex to the electrolyte, it is first diluted with water or plasticizer to facilitate addition. The addition rate is 2 ml / min.

11. The method for preparing a powdered rubber conductive material by electrochemically exfoliated graphene-promoted agglomeration according to claim 1, characterized in that: A 100-300 mesh sieve is added to the electrolyte to separate the anode and cathode. When adding rubber latex, it is added to the cathode side of the sieve to reduce the formation of flocculation that adheres to the anode electrode.

12. A powdered rubber conductive material prepared by the preparation method according to any one of claims 1 to 11, characterized in that: The powdered rubber has a particle size of less than 0.9 mm, a powder formation rate of more than 90%, and an electrical conductivity of more than 0.4 S / m.

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