JP5446702B2 - Method for producing graphite oxide particle-containing liquid - Google Patents

Description

  The present invention relates to a method for producing a graphite oxide particle-containing liquid.

  In recent years, the search for a material having a high shape anisotropy and its application are rapidly progressing. In the case where a large number of such substances are combined with other substances, it is expected that various properties such as high strength will be exhibited at a low addition rate. Also, if the shape is very thin linear (1D) or very thin planar (2D) and the material is an electrically semiconductor or good conductor, the physical properties can be used in the case of a single or a small number of aggregates. It is also expected to produce a quantum effect.

As such a highly anisotropic substance, graphite oxide, which is a planar substance having a carbon atom as a skeleton, is known. Graphite oxide is a kind of graphite intercalation compound obtained by oxidizing graphite by a specific method. Graphite oxide is a multilayer structure in which two-dimensional basic layers are stacked, and the number of layers is generally very large. The basic layer of graphite oxide consists of a carbon skeleton with a thickness of one or two carbon atoms counted in a zigzag carbon array and a sp ³ bond-dominant carbon skeleton with a slight tendency to sp ² bonds, and both sides of the skeleton. It is thought that it has the structure which has the acidic hydroxyl group couple | bonded with the surface (for example, nonpatent literatures 1-3).

  The thickness of such graphite oxide particles greatly affects the performance, and the thinner the thickness, the higher the effect as a filler. Therefore, it is important to produce very thin graphite oxide particles with a small number of layers. Has been.

  Such very thin graphite oxide particles are disclosed in, for example, Non-Patent Document 4, and the present inventors have previously described such graphite oxide (when the number of layers is one, for example, called graphene oxide) Is desirable (graphene is the name of one layer of graphite)) and finds a method of producing high-yield thin-film particles and reduces it to reduce the number of graphite (when the number of layers is one) (It is desirable to call it graphene) A thin film-like particle of similar graphite oxide has been obtained (Patent Documents 1 to 3).

  As a method for obtaining thin film particles of graphite oxide, a method of repeatedly purifying a graphite oxide particle-containing liquid containing graphite oxide particles using a decantation method, a dialysis method, a filtration method, a centrifugal method, or the like is known. It has been. In the method of repeatedly performing the purification, impurity ions in the graphite oxide particle-containing liquid are removed, interlayer separation due to electrostatic repulsion proceeds in the graphite oxide particles, and the graphite oxide particles are thinned.

  However, in the decantation method, the sedimentation of graphite oxide particles is slow, and in the dialysis method, the concentration gradient of the inside and outside ions needs to reach equilibrium, so that a long time is required for purification. In the filtration method, the filtration membrane is easily clogged and it is difficult to purify it.

  On the other hand, purification using a centrifugal separation method uses the sedimentation rate of graphite oxide particles, and is said to be capable of purification in a short time. Accordingly, purification using a centrifugal separation method is useful for separating graphite oxide particles from impurity ions (for example, Patent Document 1 and Non-Patent Document 5).

  However, as the graphite oxide particles become thinner, more time is required to settle the graphite oxide particles. In particular, the graphite oxide particles having a reduced number of basic layers (graphene oxide) have an extremely low sedimentation rate, so that It took a lot of time. For this reason, when considering mass production and the like, if the graphite oxide particles become thin, purification using a centrifugal separation method cannot be said to be practical, and there is a limit to thinning the graphite oxide particles.

  On the other hand, instead of repeating the purification many times, a method is known in which the graphite oxide particles are thinned using ultrasonic irradiation after some purification. In this method, it was considered that force was applied to the graphite oxide particles by ultrasonic irradiation, whereby the interlayer separation of the graphite oxide particles was physically performed and the layer was thinned.

  However, when the present inventors confirmed the effectiveness of the ultrasonic irradiation method, in the method using ultrasonic irradiation, the processing time for thinning is shortened, but the size (particle size) in the plane direction is reduced at the same time as thinning. It was found that the aspect ratio (particle size / thickness) of the graphite oxide particles was reduced.

JP 2002-53313 A JP 2003-176116 A JP 2005-63951 A

“Graphite Intercalation Compound”, Chapter 5, Carbon Society of Japan, Realize (1990) T. Nakajima et al. A NEW STRUCTURE MODEL OF GRAPHITE OXIDE, Carbon, 26, 357 (1988) M. Mermoux et al. FTIR AND 13C NMR STUDY OF GRAPHITE OXIDE, Carbon, 29, 469 (1991) N. A. Kotov et al. Ultrathin Graphite Oxide-PolyelectrolyteComposites Prepared by Self-Assembly: Transition Between Conductive and Non-Conductive States, Adv. Mater., 8, 637 (1996) M.Hirata et al. Thin-film particles of graphite oxide 1 :: High-yield synthesis and flexibility of the particles, Carbon 42, 2929-2937 (2004)

  Therefore, establishment of a method capable of promoting the thinning of graphite oxide particles by a method other than purification and ultrasonic irradiation has been demanded.

  The present invention has been made in view of the above circumstances, and it is possible to reduce the thickness of graphite oxide particles without repeating refining for thinning and hardly causing reduction in size (particle size) in the plane direction. It aims at providing the manufacturing method of the graphite oxide particle containing liquid which can accelerate | stimulate layering.

  The inventors of the present invention have made extensive studies in order to solve the above problems. As a result, when the graphite oxide particle-containing liquid obtained in the purification process was distributed along the surface of the tubular or rod-shaped molded body, surprisingly, there was almost no reduction in the size (particle size) in the plane direction. It was found that the thinning of graphite oxide particles was promoted. Thus, the present inventors have completed the following invention.

That is, the present invention is a method for producing a graphite oxide particle-containing liquid comprising a preparation step of preparing a graphite oxide particle-containing liquid containing graphite oxide particles and a dispersion medium, and a purification step of purifying the graphite oxide particle-containing liquid. Te, after the purification step, along the surface of the tubular or rod-shaped molded bodies, saw including a distribution step of distributing graphite oxide particle-containing liquid, the purification step, oxidizing graphite particles containing obtained in the preparation step Production of graphite oxide particle-containing liquid , wherein the liquid ion is a step of separating impurity ions that hinder thinning of the graphite oxide particles from the graphite oxide particles, and the distribution step is a step other than the purification step. Is the method.

  According to this production method, after the purification step, the graphite oxide particle-containing liquid is circulated along the surface of the tubular or rod-shaped molded body, so that the purification for thinning is not repeated, and Thinning of the graphite oxide particles can be promoted with little reduction in the size (particle size) in the surface direction. For this reason, highly oxidized graphite oxide particles can be produced.

  Although it is not yet clear why the thinning of the graphite oxide particles can be promoted with almost no reduction in the size (particle size) in the plane direction as described above, the present inventors have not made it to the surface of the molded body. When the graphite oxide particle-containing liquid is circulated along the surface, a shearing force is applied to each graphite oxide particle by the flow of the graphite oxide particle-containing liquid, and the thinning of the graphite oxide particles is physically accelerated by this shearing force. I guess that it is.

  In the distribution step, it is preferable that the flow rate of the graphite oxide particle-containing liquid with respect to the surface of the compact is 0.20 m / s or more.

  It is preferable that the molded body is tubular and that the graphite oxide particle-containing liquid is circulated along the inner wall surface of the molded body in the distribution step.

  In this case, since the graphite oxide particle-containing liquid is confined inside the tubular molded body, the graphite oxide particle-containing liquid is compared with the case where the graphite oxide particle-containing liquid is circulated along the outer wall surface of the tubular molded body. By this flow, it becomes possible to more effectively apply a shearing force to each graphite oxide particle, and it is possible to further promote the thinning of the graphite oxide particle.

  According to the present invention, graphite oxide particles that can promote the thinning of graphite oxide particles without repeating the purification for thinning and almost without reducing the size (particle size) in the plane direction A method for producing the containing liquid is provided.

4 is a graph showing the particle size distribution of graphite oxide particles in the liquid oxide containing graphite particles of Examples 1 to 5 and Comparative Example 1. FIG. 5 is a graph showing the particle size distribution of graphite oxide particles in the graphite oxide particle-containing liquids of Examples 6 to 10 and Comparative Example 1. FIG. 10 is a view showing an SEM photograph of graphite oxide particles in the graphite oxide particle-containing liquid of Example 10. FIG. 3 is a diagram showing an SEM photograph of graphite oxide particles in a graphite oxide particle-containing liquid of Comparative Example 1. FIG. 5 is a graph showing the particle size distribution of graphite oxide particles in the graphite oxide particle-containing liquid of Comparative Example 2. 6 is a view showing an SEM photograph of graphite oxide particles in a graphite oxide particle-containing liquid of Comparative Example 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail.

[Method for producing graphite oxide particle-containing liquid]
The present invention is a method for producing a graphite oxide particle-containing liquid comprising a preparation step of preparing a graphite oxide particle-containing liquid containing graphite oxide particles and a dispersion medium, and a purification step of purifying the graphite oxide particle-containing liquid. The method for producing a graphite oxide particle-containing liquid comprising a flow step of circulating the graphite oxide particle-containing liquid along the surface of the tubular or rod-shaped formed body after the purification step.

  According to this production method, the graphite oxide particle-containing liquid is circulated along the surface of the tubular or rod-shaped molded body after the purification step, so that the surface can be obtained without repeating purification for thinning. Thinning of graphite oxide particles can be promoted with little reduction in size (particle size) in the direction. For this reason, highly oxidized graphite oxide particles can be produced. That is, according to the above production method, there is provided an efficient method for producing a graphite oxide particle-containing liquid capable of promoting the thinning of the graphite oxide particles without causing a reduction in the size (particle size) in the plane direction. .

  As for the reason why the thinning of the graphite oxide particles can be promoted with little reduction in the size (particle size) in the plane direction as described above, the present inventors include graphite oxide particles along the surface of the molded body. When the liquid is circulated, a shear force is imparted to each graphite oxide particle by the flow of the graphite oxide particle-containing liquid, and the thinning of the graphite oxide particles is not physically promoted by this shear force. I guess.

  Hereinafter, the preparation step and the purification step will be described in detail.

<Preparation process>
The preparation step is a step of preparing a graphite oxide particle-containing liquid containing graphite oxide particles and a dispersion medium in which the particles are dispersed.

  Graphite oxide particles can be obtained by oxidizing graphite.

  As graphite, various types of graphite can be used. Graphite with high crystallinity with a developed layer structure is preferable because the yield of graphite oxide is high and graphite oxide with a small number of basic layers is easily obtained. As such graphite, natural graphite (particularly good quality), quiche graphite (particularly made at high temperature), highly oriented pyrolytic graphite are preferably used, and expanded graphite in which the layers of these graphites are expanded in advance. Are also preferably used. Further, it is desirable that impurities such as metal elements in the graphite have been removed in advance until it becomes about 0.5% by mass or less.

  Since the average particle size of graphite is reflected in the average particle size of graphite oxide particles, it may be appropriately selected according to the average particle size of graphite oxide particles to be synthesized. Specifically, when the average particle diameter of the graphite oxide particles is, for example, 100 nm or more, the average particle diameter of the graphite may be 0.1 μm or more and 100 μm or less. Here, the average particle size of graphite is preferably 0.5 μm or more and 50 μm or less, and more preferably 1 μm or more and 25 μm or less. When the average particle size of the graphite is 0.1 μm or more, the aspect ratio of the obtained graphite oxide particles is increased and the shape anisotropy is increased as compared with the case where the average particle size is less than 0.1 μm. When the average particle size is 100 μm or less, the time required for oxidation can be shortened compared to the case where the average particle size of graphite exceeds 100 μm.

  The shape of the graphite oxide particles is not particularly limited, and may be various shapes. For example, the graphite oxide particles may be spherical or flat. Here, it is preferable that the graphite oxide particles have a flat plate shape. When the shape of the graphite oxide particles is flat, the shape anisotropy is further increased, and when the conductive film is produced using the graphite oxide particle-containing liquid, the conductivity becomes lower. It is possible to reduce the content of graphite oxide particles in the conductive film necessary for developing conductivity in the film, to suppress the detachment of graphite oxide particles from the resulting conductive film, and Transparency can be further increased.

  When the shape of the graphite oxide particles is flat, the average particle size of the graphite oxide particles is preferably 100 nm or more. In this case, graphite oxide particles having high shape anisotropy can be produced.

  The “average particle size” of the graphite oxide particles refers to the average value of the particle sizes in the planar direction of the graphite oxide particles when the five graphite oxide particles are observed using an optical microscope or an electron microscope. Here, “particle diameter” refers to the length of the longest diagonal line of graphite oxide particles when the graphite oxide particles are observed using an optical microscope or an electron microscope.

  The graphite oxide particles can be obtained by oxidizing graphite by a known Brodie method, Staudenmaier method, Hummers-Offeman method, methods disclosed in JP-A Nos. 2002-53313 and 2003-176116, and the like. Graphite oxide particles can be used. Here, the Brodie method is a method of oxidizing graphite using nitric acid and potassium chlorate, and the Staudenmeier method is a method of oxidizing graphite using nitric acid, sulfuric acid and potassium chlorate. The Hummers-Offeman method is a method of oxidizing graphite using sulfuric acid, sodium nitrate, and potassium permanganate. Among them, it is preferable to manufacture by the Hummers-Offeman method from the viewpoint of high safety and capable of manufacturing graphite oxide particles in a short time.

  The dispersion medium for dispersing the graphite oxide particles may be any liquid as long as it can disperse the graphite oxide particles. Examples of such a dispersion medium include methanol, ethanol, acetone, 2-butanone, water, and the like. Among these, methanol and water having a relative dielectric constant of 15 or more are preferable from the viewpoint of preventing aggregation of graphite oxide particles. Water is particularly preferable, and it is more preferable to use ion-exchanged water among water.

<Purification process>
The purification step is a step of purifying the graphite oxide particle-containing liquid obtained in the above preparation step. Specifically, in the graphite oxide particle-containing liquid obtained in the above preparation step, a thin layer of graphite oxide particles This is a step performed to separate impurity ions, etc., which hinder the conversion from graphite oxide particles.

  Examples of the purification step include those using a decantation method, a centrifugal separation method, a dialysis method, and an ion exchange method. Among these, a purification process using a centrifugal separation method is preferable because the liquid containing graphite oxide particles can be purified in a relatively short time.

  The purification process using the centrifugal separation method includes, for example, a step of centrifuging the graphite oxide particle-containing liquid, a step of removing a supernatant from the centrifuged graphite oxide particle-containing liquid, and a centrifuged graphite oxide particle-containing liquid. And a dispersion medium addition step of adding a dispersion medium to.

  Here, the same dispersion medium as the original dispersion medium contained in the graphite oxide particle-containing liquid is usually used as the dispersion medium, but depending on the application, the original dispersion medium contained in the graphite oxide particle-containing liquid is used. A dispersion medium different from the medium can also be used. In this case, it is possible to replace the original dispersion medium contained in the graphite oxide particle-containing liquid with another dispersion medium different from this by repeatedly performing the purification step.

  In the purification step using the above centrifugal separation method, it is preferable that the conductivity of the supernatant is kept to 150 μS / cm or more, because the sedimentation of particles is fast, more preferably 200 μS / cm or more, more preferably 300 μS / cm. More preferably, it is up to cm or more.

  In addition to the dispersion medium, other components such as a reducing agent and a polymer material may be added to the graphite oxide particle-containing liquid, but no additional components are added to effectively promote thinning. It is desirable.

(Distribution process)
After the purification step, the graphite oxide particle-containing liquid is circulated along the surface of the tubular or rod-shaped molded body.

  When a tubular molded body is used as the molded body, the graphite oxide particle-containing liquid is distributed along the inner wall surface of the molded body as a form for allowing the graphite oxide particle-containing liquid to flow along the surface of the molded body. And a form in which the graphite oxide particle-containing liquid is circulated along the outer wall surface of the molded body.

  Among the above forms, a form in which the graphite oxide particle-containing liquid is circulated along the inner wall surface of the molded body is preferable. In this case, since the graphite oxide particle-containing liquid is confined inside the tubular molded body, the graphite oxide particle-containing liquid flows more than the case where the graphite oxide particle-containing liquid flows outside the tubular molded body. It becomes possible to apply a shear force more effectively to each graphite oxide particle, and it is possible to further promote the thinning of the graphite oxide particle. For this reason, highly anisotropic graphite oxide particles can be obtained.

  The circulation is preferably performed until the average thickness of the graphite oxide particles becomes 0.4 nm to 10 nm. In this case, the number of basic layers in graphite oxide is very small, and the average thickness is thin, so that reduction is facilitated and the shape anisotropy is remarkably increased. When the film is manufactured, it is possible to reduce the content of the graphite oxide particles in the conductive film necessary for the conductive film to exhibit conductivity. For this reason, high transparency is obtained for the conductive film, and detachment of the graphite oxide particles from the conductive film can be remarkably suppressed.

  The “average thickness” of graphite oxide particles refers to the average value of thicknesses measured for five graphite oxide particles using an atomic force microscope.

  The flow rate of the graphite oxide particle-containing liquid with respect to the surface of the molded body is preferably 0.2 m / s or more. In this case, the shearing force applied to each graphite oxide particle is increased, and as a result, the thinning of each graphite oxide particle can be further promoted, and the graphite oxide particle having a larger anisotropy can be obtained.

  The flow rate of the graphite oxide particle-containing liquid with respect to the surface of the molded body is more preferably 0.2 m / s or more, and further preferably 0.5 m / s or more. However, the flow rate is preferably 10 m / s or less from the viewpoint of preventing cutting of the graphite oxide particles.

  When the graphite oxide particle-containing liquid is circulated along the inner wall surface of the molded body, the flow rate of the graphite oxide particle-containing liquid is defined as follows.

  As can be seen from the above equation, the flow rate is determined by the flow rate and the area of the flow path through which the graphite oxide particle-containing liquid flows in a plane orthogonal to the longitudinal direction of the molded body. Here, the “area of the flow path” is obtained by multiplying the area of the region surrounded by the line of intersection between the surface perpendicular to the longitudinal direction of the molded body and the surface that is the inner wall surface of the molded body by the number of molded bodies. means.

  As the molded body, for example, a resin such as polyacrylonitrile, polyvinylidene fluoride, cellulose acetate, polysulfone, or polyimide, a metal such as iron, aluminum, or copper, or a ceramic can be used. Here, as the resin, it is preferable to use a resin that does not pass the dispersion medium in the graphite oxide particle-containing liquid from the viewpoint of preventing the surface adhesion of the graphite oxide particles.

  When the molded body is tubular, the inner diameter (inner diameter) of the tube is usually 0.01 to 500 mm, preferably 0.03 to 100 mm. Thereby, stronger shear can be obtained and the effect of thinning can be further enhanced.

  When the formed body is tubular, the liquid passing time in the formed body is not particularly limited, but it is desirable to pass the liquid until the average thickness of the graphite oxide particles becomes 0.4 nm to 10 nm. In this case, the number of basic layers in graphite oxide is very small, and the average thickness is thin, so that reduction is easy, and the shape anisotropy is remarkably high. In the case of producing a conductive film, it is possible to reduce the content of graphite oxide particles in the conductive film, which is necessary for the conductive film to exhibit conductivity. For this reason, high transparency is obtained for the conductive film, and detachment of the graphite oxide particles from the conductive film can be remarkably suppressed.

  In addition, when using the form which distribute | circulates a graphite oxide particle containing liquid along the outer wall surface of a molded object, a rod-shaped thing is used as a molded object. Even in this case, the flow rate is the same as that in which the graphite oxide particle-containing liquid is circulated inside the compact. However, when using the form in which the graphite oxide particle-containing liquid is circulated along the outer wall surface of the molded body, a cylindrical sealed container for housing the molded body is required. In the above flow velocity definition formula, “the area of the flow path” means the area surrounded by the intersection line between the surface perpendicular to the longitudinal direction of the cylindrical sealed container containing the molded body and the inner wall surface of the sealed container. It means an area obtained by subtracting a value obtained by multiplying the area of the region surrounded by the line of intersection between the surface orthogonal to the longitudinal direction of the sealed container and the outer peripheral surface of the rod-shaped molded product by the number of molded products.

  When the molded body is rod-shaped, the diameter of the molded body is not particularly limited, but may be 1 to 10 mm.

[Conductor manufacturing method]
The graphite oxide particle-containing liquid obtained by the above method for producing a graphite oxide particle-containing liquid can be used for the production of a conductor. Here, the “conductive film” refers to a film having a sheet resistivity of 1.0 × 10 ¹² (Ω / □) or less.

  To produce a conductor, the graphite oxide particle-containing liquid obtained as described above is applied onto the surface of the substrate to form a film, and the graphite oxide particle-containing liquid is dried to remove the dispersion medium. Then, after the coating film is formed, the graphite oxide particles may be reduced.

  The method for applying the graphite oxide particle-containing liquid is not particularly limited as long as it can be applied onto the surface of the substrate. For example, a spin coater method, a bar coater method, a roll coater method, or the like can be used.

  The heating temperature for removing the dispersion medium by drying the graphite oxide particle-containing liquid is preferably 30 ° C to 100 ° C, more preferably 40 ° C to 80 ° C. However, the heating may be performed at a high temperature such as 200 ° C. for the purpose of removing the high boiling point solvent for a short time of about several minutes. The reduction of the graphite oxide particles after the formation of the coat film is achieved, for example, by heat treatment at 200 ° C. for 30 minutes or more.

  In addition, when the reducing agent is contained in the graphite oxide particle containing liquid, the heating temperature for graphite oxide particle reduction can be lowered. Thus, a conductor can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not limited to a following example at all.

Example 1
10 g of natural graphite SNO-3 (purity 99.97% by mass or more) manufactured by ESC Co., Ltd. from 7.5 g of sodium nitrate (purity 99%), 621 g of sulfuric acid (purity 96%), 45 g of potassium permanganate (purity 99%) Into the resulting mixture and left at about 20 ° C. for 7 days with gentle stirring.

The obtained high-viscosity liquid was added to 1000 cm ³ of a 5% by mass sulfuric acid aqueous solution with stirring for about 1 hour, and further stirred for 2 hours.

  Hydrogen peroxide (30 mass% aqueous solution) 30g was added to the obtained liquid, and it stirred for 2 hours. Centrifugation was performed once on this liquid, and after removing the supernatant, water was added to adjust the total liquid volume to 3 L. Hereinafter, this graphite oxide particle dispersion is referred to as “dispersion A”.

  Next, the dispersion A is subjected to centrifugation using a mixed aqueous solution of 3% by mass sulfuric acid / 0.5% by mass hydrogen peroxide, and then the centrifugation is repeated using water, whereby the conductivity of the supernatant is repeated. Dispersion A was purified until the solution reached 300 μS / cm. The purified dispersion thus obtained was diluted with water so that the concentration of the oxidized graphite particles was 0.1% by weight. Then, 1 kg of the obtained diluted dispersion was passed through a tube having an inner diameter of 19 mm and a length of 50 cm using a pump, and the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was set to 0.35 (m / s) for 1 h. Liquid was performed. At this time, a tube made of vinyl chloride was used.

  A graphite oxide particle-containing liquid was obtained as described above.

(Example 2)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the diluted dispersion was passed through the tube for 4 hours.

(Example 3)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the diluted dispersion was passed through the tube for 12 hours.

Example 4
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the diluted dispersion was passed through the tube for 31 h.

(Example 5)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the diluted dispersion was passed through the tube for 107 h.

(Example 6)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was 0.75 (m / s).

(Example 7)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was 0.75 (m / s) and the diluted dispersion was passed through the tube for 8 hours. It was.

(Example 8)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was 0.75 (m / s) and the diluted dispersion was passed through the tube for 23 h. It was.

Example 9
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was 0.75 (m / s) and the diluted dispersion was passed through the tube for 55 h. It was.

(Example 10)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the flow rate of the diluted dispersion with respect to the inner wall surface of the tube was 0.75 (m / s) and the diluted dispersion was passed through the tube for 143 h. It was.

(Comparative Example 1)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1 except that the purified dispersion was not diluted and the liquid was not passed through the tube thereafter.

  For the graphite oxide particle-containing liquids obtained in Examples 1 to 5 and Comparative Example 1, the particle size distribution of the graphite oxide particles was measured. Specifically, the relative comparison of the number of layers of graphite oxide particles was performed by measuring the particle size distribution with a liquid phase sedimentation particle size distribution meter (HORIBA ultracentrifugal automatic particle size distribution analyzer CAPA-700).

A liquid phase sedimentation type particle size distribution analyzer is an apparatus that evaluates the particle size of particles by utilizing the fact that the sedimentation rate of particles in a solvent varies depending on the particle size. It is known that spherical particles having a diameter (D) and a density (ρ) existing in a solvent having a density (ρ ₀ ) and a viscosity coefficient (η ₀ ) settle at a constant speed according to the Stokes settling equation. This theory is applied to the sedimentation type particle size distribution meter (for example, HORIBA ultracentrifugal automatic particle size distribution analyzer CAPA-700 manual). Stokes' settling equation is a formula for spherical particles and does not reflect the exact particle size of particles with high shape anisotropy. However, when the solvent density (ρ ₀ ), viscosity coefficient (η ₀ ), and particle density (ρ) are the same, the particle size value obtained corresponds to the sedimentation rate, and the smaller the particle size value, The sedimentation rate is slow. On the other hand, as the graphite oxide particles with a smaller number of layers have a lower sedimentation rate, a relative comparison of the number of layers can be performed by comparing the particle size distribution based on the same data measured at ρ ₀ , η ₀ , and ρ. It becomes possible. The particle size distribution measurement was performed under the conditions shown in Table 1 below. The results are shown in FIG. The vertical axis represents the ratio of the sum of the areas of the circles of particles having a certain particle diameter to the total area of the circles obtained by determining the particle diameter as the diameter for all particles (the same applies to FIGS. 2 and 5). . As shown in FIG. 1, it can be seen that the distribution peak shifts to the right side, that is, the particle size is smaller as the liquid passing time becomes longer. From this, it turned out that the method of Examples 1-5 can accelerate | stimulate thinning of a graphite oxide particle rather than the comparative example 1 without further refine | purifying about the dispersion liquid after refinement | purification.

  Further, for the graphite oxide particle-containing liquids obtained in Examples 6 to 10, the particle size distribution of the graphite oxide particles was measured in the same manner as described above. The results are shown in FIG. In addition, in FIG. 2, the measurement result of the particle size distribution about the graphite oxide particle containing liquid obtained by the comparative example 1 was also shown.

  As shown in FIG. 2, it can be seen that the distribution peak shifts to the right side, that is, the particle size is smaller as the liquid passing time becomes longer. From this, it turned out that the method of Examples 6-10 can accelerate | stimulate thinning of a graphite oxide particle rather than the comparative example 1 without further refine | purifying about the dispersion liquid after refinement | purification.

  The graphite oxide particles in the graphite oxide particle-containing liquid obtained in Example 10 and Comparative Example 1 were also subjected to SEM observation at a magnification of 2500 times. The results are shown in FIGS. 3 and 4, respectively. 3 and 4, it means that the darker the oxide graphite particles are, the thicker the particles are.

  From the results shown in FIG. 3 and FIG. 4, the graphite oxide particles of Example 10 have a slightly smaller particle size than the graphite oxide particles of Comparative Example 1, but the color is very light and thin. It can be seen that stratification is promoted.

  Further, when the graphite oxide particles in the graphite oxide particle-containing liquids obtained in Examples 1 to 9 were also subjected to SEM observation in the same manner as in Example 10, both the particle diameter and the color density of the graphite oxide particles were observed. It was almost the same as Example 10.

  As described above, according to the methods of Examples 1 to 9, the graphite oxide particles were thinned without causing further reduction of the size (particle size) in the plane direction without further purification of the purified dispersion. It was found that can be promoted.

(Comparative Example 2)
A graphite oxide particle-containing liquid was obtained in the same manner as in Example 1, except that 100 g of the diluted dispersion was subjected to ultrasonic irradiation with an ultrasonic homogenizer with an output of 600 W for 30 minutes.

  About the graphite oxide particle containing liquid obtained by the comparative example 2, it carried out similarly to Example 1, and measured the particle size distribution of the graphite oxide particle. The results are shown in FIG.

  The graphite oxide particles in the obtained graphite oxide particle-containing liquid were also observed by SEM in the same manner as in Example 10 and Comparative Example 1. The results are shown in FIG. In FIG. 6 as well, the darker the oxide oxide particles are, the thicker it is.

  FIG. 5 shows that the graphite oxide particle-containing liquid obtained in Comparative Example 2 promotes thinning of the graphite oxide particles, but when FIG. 6 is seen, the particle size of the graphite oxide particles is very small. Therefore, the result of FIG. 5 was determined to reflect the extremely small particle size. That is, it was found that the method of Comparative Example 2 has a very high effect of reducing the particle size at the same time as promoting thinning.

As described above, according to the present invention, it is possible to promote the thinning of graphite oxide particles without repeating purification for thinning and almost no reduction in the size (particle size) in the plane direction. Was confirmed.

Claims (3)

A preparation step of preparing a graphite oxide particle-containing liquid containing graphite oxide particles and a dispersion medium;
A method for producing a graphite oxide particle-containing liquid comprising a purification step of refining the graphite oxide particle-containing liquid,
After said purification step, along the surface of the tubular or rod-shaped molded bodies, saw including a distribution step of distributing graphite oxide particle-containing liquid,
In the graphite oxide particle-containing liquid obtained in the preparation step, the purification step is a step of separating impurity ions that hinder thinning of the graphite oxide particles from the graphite oxide particles,
The manufacturing method of the graphite oxide particle containing liquid whose said distribution | circulation process is processes other than the said refinement | purification process .   2. The method for producing a graphite oxide particle-containing liquid according to claim 1, wherein a flow rate of the graphite oxide particle-containing liquid with respect to the surface of the compact is 0.20 m / s or more in the distribution step. The manufacturing method of the graphite oxide particle containing liquid of Claim 1 or 2 which distribute | circulates the said graphite oxide particle containing liquid along the inner wall face of the said molded object in the said distribution process at the said molded object.