KR20150078679A - Graphite oxide concentrate coating agent manufacturing method ＆ Graphite oxide coatings manufacturing method - Google Patents

Abstract

The present invention relates to a process for producing a graphite oxide coating liquid in which the plate-like structure of graphite oxide is maintained by replacing water molecules on the surface of graphite oxide with a desired solvent without heat treatment, and a process for producing graphite oxide coatings based thereon.
The present invention relates to a process for producing a water-based graphite oxide slurry, comprising the steps of: (a) oxidizing graphite to prepare a water- (b) concentrating said aqueous graphite oxide slurry to produce a concentrated slurry; (c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the concentrated slurry; (d) providing molecular shock waves to said solution; And (e) repeating the steps (c) to (d) two or more times; The present invention provides a method for producing a graphite oxide concentrated slurry coating liquid.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a graphite oxide concentrate slurry coating method, and a graphite oxide concentrate coating agent manufacturing method and a graphite oxide coatings manufacturing method,

The present invention relates to a process for producing a graphite oxide coating liquid in which the plate-like structure of graphite oxide is maintained by replacing water molecules on the surface of graphite oxide with a desired solvent without heat treatment, and a process for producing graphite oxide coatings based thereon.

Graphite oxide has been studied and manufactured in various forms for over 100 years. In literature, Hofman and Frenzel (Ber. 53B, 1248 (1930)), Hamdi (Kolloid Beihefte, 54, 554 (1943)), Carbon 42, 292937, 2004, Chem. Mater. 19, 4396 (2007).

The graphite oxides hold between 1 and 20 layers of the graphite layer, and have many defects and oxidized groups on the surface, so they are very well dispersed in water. In addition, surface reactors of graphite oxides can have various substituents through simple reactions, such as -OH, -COOH, -CONH ₂ , -NH ₂ , -COO-, -SO ₃ -, -NR ^{3 +} , -CH = O, C-OH,> O, and CX all belong to the category of graphite oxide.

These materials can be converted into graphite oxide powder obtained by thermally drying (removing water) or reduced graphite oxide powder formed by removing surface hydrophilic group through high temperature heat treatment. Recently, many industrial application methods for these powders have been researched.

Polyimide (PI) is a heat-resistant polymer synthesized from an aromatic diamine and an aromatic tetracarboxylic acid dianhydride and having an imide group in the main chain. Imide means a compound having a cyclic structure in which two acyl groups formed by reaction with a cyclic anhydride amine or ammonia are bonded to a nitrogen atom. A polyimide precursor, polyamic acid, may be included in the coating fluid to form a polyimide-containing composite coating.

Polycarbosilane is a polymer composed of Si-C-O-H, and is a polymer converted into Si-O-C ceramics or Si-C ceramics through heat treatment.

When nanoparticles or linear nanowires are introduced into the polymer, a strengthening effect is manifested to form nanoparticle-reinforced polymer composites or films, nanowire-reinforced polymer composites or films, respectively, . On the other hand, the effect of the plate-type nanomaterial on the polymer strengthening effect is not known by the effect of the plate-like nanomaterial such as graphite oxide in addition to the effect of the nanoclay.

The nano platy graphite oxide water-based slurry obtained in the form of an aqueous slurry (solid content: 0.01 to 30 wt%) which maintains strong hydrogen bonding with H ₂ O from the time of preparation has excellent coatability. However, there is a problem of dissolving into water in the coating body, and serious problems of being contaminated with sweat and moisture when the coating body is touched by hand. In addition, as a polymer used as a coating liquid additive, a water-soluble polymer such as PVA should be used. The graphite oxide coating liquid containing these polymers has a problem that the strength is increased to some extent but is considerably weak in water.

Ultimately, water-based polymers can not be used as additives for coatings for IT / electronics. Therefore, a non-aqueous polymer which is hardly soluble in water is used as a binder, which is natural because of the stability and reliability of IT / electronic parts.

Therefore, when the conventional graphite oxide is applied to the coating of IT / electronic components or mixed with the non-aqueous polymer, the graphite oxide must be completely dried and used. However, the graphite oxide powder dispersed in water is flattened, whereas the dried graphite oxide powder has a crushed shape. Therefore, in order to prepare a graphite oxide powder as a non-aqueous coating liquid, a considerable coating liquid manufacturing technology such as a spreading process and a dispersion process is separately required.

It is an object of the present invention to provide a method for preparing a coating liquid by converting a water-based graphite oxide slurry into a non-aqueous graphite oxide, and to provide a method for producing a functional graphite oxide coating liquid containing additives soluble in a non-aqueous solvent.

Another object of the present invention is to provide a method for manufacturing a graphite oxide composite (polymer and ceramic) in which heat resistance, durability and acid resistance of an original polymer are enhanced by utilizing a polymer reinforcing effect by a plate type nano material such as graphite oxide.

(A) oxidizing graphite to produce a water-based graphite oxide slurry; (b) concentrating said aqueous graphite oxide slurry to produce a concentrated slurry; (c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the concentrated slurry; (d) providing molecular shock waves to said solution; And (e) repeating the steps (c) to (d) two or more times; The present invention provides a method for producing a graphite oxide-enriched slurry coating liquid.

The present invention also provides a method for producing a mixed solution, comprising the steps of: (f) adding an excess amount of a flowable solvent to the solution to prepare a mixed solution; (f-1) providing a molecular unit shock wave to the mixed solution; And (f-2) repeating the steps (e) to (e-1) at least twice to prepare a coating solution; A method for producing a graphite oxide-enriched slurry coating liquid ".

(E-1) adding a predetermined amount of a flowable solvent to the solution; A method for producing a graphite oxide concentrated slurry coating liquid ".

The present invention is also characterized in that in the step (b), the aqueous graphite oxide slurry is concentrated by any one of a room temperature drying method, a thermal energy application method, a vacuum decompression method, a microwave application method, a centrifugal precipitation method and a freeze drying method A method for producing a graphite oxide concentrated slurry coating solution ".

The present invention further provides a method for producing a flowable solvent-containing graphite oxide coating liquid, wherein the step (c) comprises providing the molecular-weight shock wave by at least one of a physical energy application method, a thermal energy application method and a microwave application method "Together.

Further, the present invention is characterized in that, in the step (c) and the step (f), the molecular unit shock wave is provided by a physical energy application method by at least one of an ultrasonic wave application method, a shear force application method, an ultrafast blading, A method for producing a flowable solvent-containing graphite oxide coating liquid ".

The amphiphilic solvent to be added in the step (b) may be selected from the group consisting of propanol, acetone, isopropanol (IPA), NMP (1-methyl-2-pyrrolidinone), CAN (Ceric Ammonium Nitrate) Glycerol, tetraethylene glycol), MIPA (monoisopropanolamine), EDA (methylbetamethoxypropionate), glycerol, glycerol, MMA (monoethanolamine), Catechol, DETA (diethylenetriamine), DGME (diethylene glycol monoethyl ether), MMA (methyl methacrylate), DMF (dimethyl formamide), CCl4, DCE 1,2-dichlorobenzene, HMPA, DMEU, MC, Dichloromethane, methanol, ethanol, butanol, dioxane, tetrahydrofuran (THF) , Acetone, acetonitrile, 1-propanol, ethylene glycol, pyridine, hydrazine and nitromethane. A method for producing a solvent containing graphite oxide coating liquid ".

The present invention also relates to a method for producing an electrophotographic photosensitive member which comprises the steps of: (a) preparing a binder, a monomer, a polymer, a resin, a ceramic precursor polymer, a polyimide precursor, a metal binder, a ceramic binder, a nanoparticle binder, Characterized in that at least one of a functional material, a solvent, an oil, a dispersant, an acid, a base, a salt, an ionic species, a labeling agent and an adhesive is added as a functional additive. Oxide coating liquid manufacturing method ".

The present invention also provides a "method for producing a graphite oxide coating, characterized in that the graphite oxide coating liquid prepared by the above-mentioned method is coated on a base material followed by heat treatment".

As described in detail above, the water-based graphite oxide slurry can be efficiently replaced with the flowable solvent by using various molecular unit shock wave irradiation methods, and the flowable solvent-containing graphite oxide coating liquid can be obtained. Thus, it has been possible to manufacture a variety of graphite oxide-polymer coatings by making it possible to apply polymers that were only compatible with water-based graphite oxide slurries to almost any industrial polymer. In such a coating solution, the graphite oxide plate structure having good dispersibility in water is retained in the solvent of the oil phase, and the resultant coatings exhibit excellent heat resistance, chemical resistance and acid resistance which have not been seen before.

[Fig. 1] is a schematic view of the solvent replacement process of the present invention.
[Fig. 2] is a photograph of an aqueous, IPA-based, and toluene-based graphite oxide slurry.
[Fig. 3] is a transmission electron micrograph of an IPA-based graphite oxide.
4 is a photograph of a graphite oxide-polyamic acid coating solution.
5 is a photograph of a graphite oxide-polycarbosilane coating solution.
6 is a photograph of heat resistance test of a reduced graphite oxide-PI coating.
7 is a heat resistance test of a reduced graphite oxide-SiOC coating.

Conventional graphite materials are in the form of powder and can be easily dispersed and compounded into non-aqueous solvents which are mostly used in the electronics / IT industry due to the hydrophobic properties of the surface. In addition, conventional graphite materials are thick plate structures (thicknesses ranging from a few hundred nanometers to several micrometers), which are resistant to the coating liquid preparation process and are reflected in the final coating. The graphite oxide to be used in the present invention has a thickness of about 1 to 20 atomic layers (thickness: 7 nm or less) and exhibits quantum mechanical properties and has properties completely different from those of conventional graphite materials. However, since graphite oxide is mostly covered with a hydrophilic group, the moisture can not be removed unless it is completely heat-treated. There is a slight amount of moisture remaining in the graphite oxide and it can not be mixed with the polymer for electronic / IT. Even if mixed only, the two-dimensional plate-like graphite oxide structure is wrinkled and the physical properties of the resultant coating are lowered. The long-term stability of the coating and the deterioration of long-term physical properties can not be used as electronic / IT parts. However, even when the graphite oxide is heat-treated due to the above-mentioned moisture problem, it is inevitable that the plate shape is wrinkled and the inherent properties disappear.

Accordingly, the present invention provides a method for progressively replacing water molecules, which are hydrogen bonded and associated with graphite oxide surfaces (hydrophilic groups), with amphoteric solvents while maintaining the graphite oxide structure well dispersed in water.

Also, the present invention provides the amphiphilic solvent-based graphite oxide coating solution, and based on this, an attempt is made to produce a graphite oxide-nonaqueous polymer coating solution in which a graphite oxide two-dimensional plate structure is well maintained.

Thus, the result of the present invention is to provide a (2-dimensional-nansheet-reinforcement) composite coating in which the coating provided from the coating solution is reinforced by two-dimensional graphite oxide. Two-dimensional plate-like reinforced composite coatings can be compared to existing nanoclay composite films. Such a coating material can provide new physical properties that could not be provided in the past.

1 is a schematic diagram illustrating the principle of the present invention. Water-based graphite oxide slurries have many hydrophilic groups on the surface and form strong hydrogen bonds with water molecules. In addition, water molecules are strongly bonded to each other through hydrogen bonding (see (I) of FIG. 1). This structure has recently been understood through academic research. In order to remove moisture from such a structure, heat treatment at a high temperature of 300 ° C. or more is required. Due to such heat treatment, the graphite oxide layers adhere to each other and agglomerate deeply, There is a difficulty to go through again.

Therefore, the first technical idea of the present invention is a process for replacing water molecules on the surface of graphite oxide with a desired solvent without heat treatment. When a simple solvent replacement step is carried out, a small water cluster sticking to the hydrophilic group of the graphite oxide is left as shown in (II) of FIG. 1, and when a non-aqueous coating solution containing the same is produced, There is a serious problem in industrial viewpoints such as lowering of stability and lowering of physical properties of coating.

Accordingly, in the present invention, as shown in (III) of [Fig. 1], a method of preferentially producing a graphite oxide slurry in which the water molecule aggregate is completely replaced with a non-aqueous solvent and the dispersibility is maintained as it is, A polymer suitable for aqueous solvent and an additive were mixed to prepare a high quality graphite oxide-polymer coating solution and a graphite oxide-polymer, a reduced graphite oxide-polymer, a reduced graphite oxide-ceramic and the like prepared therefrom.

As a specific method for completely replacing the water molecule aggregate with a non-aqueous solvent as in (III) of FIG. 1, water molecules adhering to the hydrophilic group of the graphite oxide are removed by repeated application of the molecular unit shock wave, So that the amphoteric solvent adheres to the hydrophilic group. The attached amphiphilic solvent is weaker in binding force than water molecule, but the water molecules that fall off are trapped by the surrounding amphiphilic solvent, so that some bonding is maintained. The process for producing a non-aqueous graphite oxide coating liquid in which complete substitution is realized as in (III) of FIG. 1 includes the steps of (i) a method for producing an amphiphilic solvent-containing graphite oxide coating solution (hereinafter referred to as "first process"), (ii) (Hereinafter referred to as "second method"), and (iii) a method for producing a co-solvent-containing graphite oxide coating liquid (hereinafter referred to as "third method"). The steps of the above three methods are as follows.

* First Method

(a) oxidizing graphite to produce a water-based graphite oxide slurry;

(c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the slurry;

(d) providing molecular shock waves to said solution;

(e) repeating the steps (c) to (d) two or more times to prepare a coating solution;

* Second method

(a) oxidizing graphite to produce a water-based graphite oxide slurry;

(c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the slurry;

(d) providing molecular shock waves to said solution;

(e) repeating the steps (c) to (d) two or more times to prepare a coating solution;

(f) adding an excess flow solvent to the solution to prepare a mixed solution;

(f-1) providing a molecular unit shock wave to the mixed solution; And

(f-2) repeating the steps (e) to (e-1) at least twice to prepare a coating solution;

* Third method

(a) oxidizing graphite to produce a water-based graphite oxide slurry;

(c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the slurry;

(d) providing molecular shock waves to said solution;

(e) repeating the steps (c) to (d) two or more times to prepare a coating solution;

(e-1) adding a predetermined amount of a flowable solvent to the solution

The first to third methods above share steps (a) to (d). The present invention provides "a process for producing a graphitized oxide-enriched slurry coating " in which the step " (b) of concentrating the aqueous graphitized oxide slurry to produce a concentrated slurry " is carried out between steps (a) and .

Hereinafter, each step of the present invention will be described in detail with reference to drawings and specific embodiments.

1. Step (a)

The step (a) is a step of oxidizing graphite to prepare a water-based graphite oxide slurry. Examples of the method for producing the graphite oxide include the modified Hummers method, the Hummers method, the Brodie method, the Hofman & Frenzel method, the Hamdi method, and the Staus method. The first photograph on the left side of [Fig. 2] is a photograph of a water-based graphite oxide slurry produced by Modified Hummers method. The graphite oxide is formed in a nano-plate structure having 1 to 10 layers of graphite layers.

In a concrete example, 50 g of micro graphite powder and 40 g of NaNO ₃ are put into a 200 mL H ₂ SO ₄ solution, and 250 g of KMnO ₄ is slowly added over 1 hour while cooling. Then slowly add 5 liters of _4-7 % H ₂ SO ₄ over 1 hour and add H ₂ O ₂ . Thereafter, the supernatant is centrifuged and the precipitate is washed with 3% H ₂ SO ₄ -0.5% H ₂ O ₂ and distilled water to obtain a yellowish brown graphene oxide water-based slurry (FIG. 2 (a)).

2. Step (b)

The step (b) is a step of concentrating the aqueous graphite oxide slurry to prepare a concentrated slurry. As the method of concentrating the aqueous graphite oxide slurry, any one of a room temperature drying method, a thermal energy application method, a vacuum decompression method, a microwave application method, a centrifugal precipitation method and a freeze drying method can be applied.

The above-mentioned normal-temperature drying method uses a phenomenon of evaporation of moisture at room temperature. The thermal energy application method is a method of applying heat energy to assist evaporation of water, and the vacuum decompression method is a method of assisting the evaporation of water under atmospheric pressure and low pressure. The microwave application method is a method for assisting water evaporation by allowing water molecules to directly absorb microwave and to emit vibration-heat energy. The centrifugation method is a method of obtaining a concentrated precipitation slurry by precipitating a graphite oxide slurry through centrifugal separation and then discarding a low concentration portion of the upper layer. In this case, the precipitate can be collected after centrifuging the aqueous graphite oxide slurry at a rpm of 3,000 or more. The freeze-drying method is a method of reducing water content by submerging frozen water below the freezing point.

3. Step (c)

The step (c) is a step of preparing a solution in which an excess amount of an amphoteric solvent is added to the aqueous graphite oxide slurry concentrated by the step (b). Here, the term "excessive amount" means an excessive amount exceeding the amount required to replace the water molecule attached to the hydrophilic group of the graphite oxide. In this step, the ampholytic solvent is used in an amount of 2 to 6 times the volume of the aqueous graphite oxide slurry Can be added.

The amphiphilic solvents used in the present invention are amphoteric solvents such as propanol, acetone, isopropanol (IPA), NMP (1-methyl-2-pyrrolidinone), CAN (Ceric Ammonium Nitrate) (Gamma Butylolactone), Sulfolane, Diethylene Glycol Mnoethyl Ether, Glycol, TEG (Tetraethylene Glycol), MIPA (Monoisopropanolamine), EDA (Methyl Betamethoxypropionate) , MEA (monoethanolamine), Catechol, DETA (diethylenetriamine), DGME (diethylene glycol monoethyl ether), MMA (methyl methacrylate), DMF (dimethyl formamide), CCl4, DCE 1,2-dichloromethane, 1,2-dichlorobenzene, HMPA, DMEU, MC, dichloromethane, methanol, ethanol, butanol, dioxane, tetrahydrofuran ), Acetone, acetonitrile, 1-propanol, ethylene glycol, pyridine, hydrazine, and nitromethane.

Substitution of solvents such as GBL, MAKN and the like, in which the solubility of the amphoteric solvent is relatively low, is first replaced by sufficient solvent substitution of the graphite oxide slurry using IPA having good hydrophilicity and excellent compatibility with these solvents, Or by solvent substitution with MAKN.

4. Step (d)

The step (d) is a step of providing a molecular unit shock wave to the solution.

The method of providing the molecular shock wave can be roughly classified into (i) physical energy application method (including mechanical energy application method), (ii) thermal energy application method, and (iii) microwave application method.

The physical energy application method includes an ultrasonic application method capable of causing a micro cavity explosion, a molecular unit shear force application method (a high pressure ejection method in which a fine nozzle is discharged at a high pressure, a high speed homogenizer, etc.) A sintering method, a beads ball stuttering method (a method of stuttering with a fine bead ball, a pressing / ejecting method using a fine gap, a high-speed homogenizer, etc.).

The thermal energy applying method is a method of literally heating the solution. Due to thermal energy, molecular unit H ₂ O and the solvent molecules to be replaced collide on the atomic group, and this collision energy increases by more than 2 times as the solution temperature increases by 10 ° C. In addition, convection inside the solution actively occurs due to the application of thermal energy, thereby bringing about the effect of uniform stirring. Therefore, when the temperature of the solution goes up to the boiling point, for example, when the temperature is raised from 20 ° C. to 100 ° C., the effective collision reaction speed in the molecular unit radius increases by 30, 40, 50, 60, 70, 80, 2, 4, 8, 16, 32, 64, 128, 256 times. Therefore, when a high-pressure apparatus is used, the reaction rate can be increased from several times to several hundred thousand times.

The microwave application method can generate heat by vibrating water molecules to provide shock waves to water molecules. This is an example of applying a microwave application method to a domestic microwave oven. Plate-like structure of graphite oxide also reacts with microwaves to provide intense shock waves. In this case, the effect of water desorption and surface hydrophilic groups of graphite oxide is eliminated (reduction).

In the present invention, any of the above three methods (physical energy application method (including mechanical method), thermal energy application method, and microwave application method) may be applied as a method of providing molecular unit shock waves, or two or more methods may be mixed have. For example, there may be six methodologies from physical energy application method to thermal energy application method, from physical energy application method to microwave application method, from thermal energy application method to microwave application method and reverse order method. A method of sequentially using the above three methods is also possible.

Also, in the present invention, two or three of the above three methods may be simultaneously applied. Specifically, a method of applying ultrasonic waves while applying thermal energy, a method of applying microwave while applying ultrasonic waves while applying thermal energy, and the like can be exemplified.

5. Step (e)

In the step (e), the coating liquid is prepared by repeating the steps (c) to (d) two or more times. The effects of the repetition of steps (c) to (d) will be described below with reference to the embodiments.

6. Step (e-1)

The step (e-1) is a step of adding a predetermined amount of a flowable solvent to the coating solution. Here, the term "fixed amount " means about 0.5 to 1.5 times the volume of the aqueous graphite oxide slurry before the amphoteric solvent is introduced.

As such, it is possible to first wash the amorphous solvent sufficiently to remove the water contained in the graphite oxide, and then apply the flowable solvent having affinity with the amphoteric solvent. When a flowable solvent is initially introduced into a water-based graphite oxide, a desired dispersion is not obtained and phase separation occurs.

As the flow-through solvent, any one of benzene ring compound and chlorine-based solvent may be applied. Examples of the benzene ring compound include toluene, benzene, and xylene. Examples of the chlorinated solvent include dichloromethane, methylene chloride, trichloromethane, carbon tetrachloride, and the like.

7. Step (f)

In the step (f), an excess amount of a flow solvent is added to the solution to prepare a mixed solution. Here, the term "excessive amount" means an excessive amount exceeding an amount required to replace the water molecule attached to the hydrophilic group of the graphite oxide. In this step, the flowable solvent is used in an amount of 2 to 6 times the volume of the aqueous graphite oxide slurry Can be input. The matters relating to the flowable solvent are as described in the above step (e-1).

However, in the step (e-1), an excess amount of an amphoteric solvent is added to the graphite oxide slurry, and the process of providing a molecular unit shock wave to the solution is repeated to complete substitution, followed by adding a certain amount of a flowable solvent In step (f), an excessive amount of an amphoteric solvent is added to the graphite oxide slurry, and the process of providing a molecular unit shock wave to the solution is repeated, and then an excess amount of an oil solvent is added. ) And step (f-2) must be additionally performed.

8. (f-1) Step

The step (f-1) is a step of providing a molecular unit shock wave to the mixed solution. The details of the provision of the shock wave are as described in the step (d).

9. The method according to (f-2)

In the step (f-2), the coating liquid is prepared by repeating the steps (f) to (f-1) at least twice.

When the first method is applied, a functional coating liquid can be prepared by adding a polymer dissolving in an amphoteric solvent to the prepared coating liquid. As the polymer soluble in amphoteric solvents, a polyimide precursor can be used, and as the polyimide precursor, a polyamic acid can be applied.

When the second method and the third method are applied, a functional coating solution can be prepared by adding a polymer dissolving in an oil-based solvent to the prepared coating solution. Polycarbosilane can be applied as a polymer soluble in a flowable solvent.

In addition, in the case of the first method to the third method, the step of increasing the concentration of the coating solution by heating or vacuum-depressurizing the coating solution may be additionally carried out.

That is, the non-aqueous graphite oxide coating liquid or the non-aqueous graphite oxide-polymer coating liquid formed by the present invention is heat-treated to form i) reduced graphite oxide, ii) graphite oxide-polymer, iii) reduced graphite oxide- - methods of making ceramic coatings. The reason for this increase in the number of branches is that when the graphite oxide is heat-treated, the graphite oxide can be maintained depending on the temperature and the environment, and can be partially reduced or completely reduced (reduced graphite oxide) And the polymer state can be maintained according to the environment, and ceramicization can proceed, and in the case of the precursor polymer, the reaction can proceed to become the original polymer.

In order to improve the dispersibility of the coating liquid and the physical properties of the coating, it is possible to use a binder, a monomer (thermosetting, UV-curable, chemically curable), a polymer, a resin, a ceramic precursor polymer (siloxane, polycarboxylic acid, etc.), a polyimide precursor ), Metal binders, ceramic binders, nanoparticle binders, surfactants, functional materials (nanoparticles, electromagnetic wave shielding components, electromagnetic interference components, magnetic materials, nanowires, nanorods and carbon nanotubes), solvents A dispersant, an acid, a base, a salt, an ionic species, a labeling agent, a pressure-sensitive adhesive, etc. may be added to the water-soluble polymer.

In the present invention, a polymer is used as an example of the additive. However, at least one of the additives may be used in at least one of the steps of the present invention.

The graphite oxide or the reduced graphite oxide contained in the coating liquid and the coating is characterized in that the graphite layer has 1 to 10 layers in thickness, and the polyamic acid seed added to the coating liquid is a polyimide series through heat treatment. Depending on the degree of heat treatment (temperature, time, atmosphere), some or all of the seeds in the polyamic can be converted to PI-based polymers.

[Example 1] was obtained by centrifuging the graphite oxide slurry ((a) of FIG. 2 (a) of FIG. 2 obtained above by centrifugation at a RPM of 10,000 to 30,000 and discharging the slurry along with the precipitated concentrated graphite oxide slurry After the IPA was added to the solution, ultrasonic shock wave was applied to sufficiently mix water and IPA solvent (dropping water molecules on the surface of graphite oxide) and centrifuged again to discard the supernatant. IPA (isophanolamine ) Was repeated three or more times to prepare an IPA-containing graphite oxide slurry (Fig. 2 (b)).

The photographic images of the dried graphite oxide IPA solution after drying are shown in FIG. [Figure 3] is a very important photograph showing that graphite oxides containing an amphoteric solvent, which is the result of applying the principle of the present invention, as well as graphite oxide is well dispersed in water, maintains a two-dimensional plate structure well.

Also, it was confirmed that the two-dimensional plate structure is well maintained in the transmission electron microscope photograph of graphite oxide dispersed in other solvents NMP, GBL and toluene to which the principle of the present invention is applied.

The moisture content of the IPA graphite oxide slurry obtained through ultrasound shock wave application through Example 1 and the IPA graphite oxide slurry obtained through manual shaking (male adult basis) instead of the ultrasonic shock wave application method was measured by GC-MASS (Peak Intensity Comparisons) are shown in Table 1 (Peak Intensity is a relative value based on a maximum of 1).

IPA replacement count Ultrasonic shock wave  Simple Mixing One 0.1 One 2 0.05 0.8 3 --- 0.7 4 --- 0.5

The moisture content of the IPA graphite oxide slurry obtained by applying the ultrasonic shock wave through Example 1 and the IPA graphite oxide slurry obtained through the simple stirling (rpm 800) treatment instead of the ultrasonic shock wave application method was measured by GC-MASS (Peak intensity comparison) is shown in [Table 2] (peak intensity is relative value based on maximum 1).

IPA replacement count Ultrasonic shock wave  Simple Stirling One 0.2 0.8 2 0.05 0.7 3 0.01 0.65 4 --- 0.5

It can be seen that the ultrasonic shock wave application method has a considerable effect in [Embodiment 2] and [Embodiment 3] as compared with the simple mixing method, and it is found that the ultrasonic wave shock effect is already effective when the IPA substitution number is two or more times.

The graphite oxide slurry obtained in the above-described manner ((a) of FIG. 2) was centrifuged at a RPM of 10,000 to 30,000, and the precipitated graphite oxide slurry was poured through the supernatant and IPA was added to the precipitated graphite oxide slurry five times its volume (A process of dropping water molecules adhering to the surface of graphite oxide) by thoroughly mixing water and IPA solvent by applying various ultrasonic shock waves, repeating the process of discarding the supernatant by centrifuging and injecting IPA into the lower sediment, Oxide slurry was prepared. The moisture content of each of the graphite oxide IPA slurries thus prepared is shown in Table 3 (peak strength is maximum 1) by GC-Mass (comparison of the water content (peak strength comparison) by gas chromatography mass spectrometry) Relative value by reference). The ultrasonic treatment conditions were based on the washing machine used in the general laboratory. The homogenizer was stirred for 10 minutes under the same RPM conditions. The fine high-pressure spraying method was tested while increasing the pressure (atmospheric pressure) after fixing the nozzle diameter to 100 mu m.

Ultrasonic application method homogenizer Micro-high pressure ejection method Processing time Water Strength rpm Water Strength pressure Water Strength 5 minutes 0.05 1,000 0.07 100 0.06 10 minutes 0.05 2,000 0.06 500 0.05 15 minutes 0.04 2,500 0.05 1,000 0.04 20 minutes 0.03 3,000 0.04 2,000 0.03

It can be seen from Examples 2, 3 and 4 that a strong micro cavity, a shear force, a rotational force, and an output power provide a considerable shock wave, and this shock wave is indispensable for removing moisture adsorbed on a molecular basis.

The moisture content of each of the graphite oxide IPA slurries prepared using the method of Example 1 but using the thermal energy application method and the microwave treatment method instead of the ultrasonic application method was measured by GC-Mass (gas chromatography mass spectrometry (Comparison of peak intensities) were compared in Table 4 (peak intensity is relative to maximum 1). The ultrasonic treatment conditions were based on the washing machine used in the general laboratory. The homogenizer was stirred for 10 minutes under the same RPM conditions. The micro-high-pressure ejection method was tested by increasing the pressure (atmospheric pressure) after fixing the nozzle diameter at 100 microns.

IPA  Substitution number Thermal energy application method Microwave application method One 0.2 0.15 2 0.07 0.06 3 0.03 0.04 4 0.01 0.02

This result shows that the thermal energy application method or the microwave application method has the same effect as the physical energy application method shown in Examples 2 and 3. In addition, the results show that the moisture is greatly reduced during the treatment of two or more times.

In addition, the results of Table 4 show that the oxygen content of graphite oxide decreases because the surface hydrophilic group of graphite oxide basal plan (double flat plate) is lowered due to molecular energy shock wave by heat energy and microwave application. [Table 5] shows the results of the energy dispersive spectroscopy (EDS) analysis of the oxygen content of carbon as a result of the experiment on [Table 4]. The carbon and oxygen content of the desired graphite oxide were 85% and 15% (weight ratio), respectively.

IPA  Substitution number Thermal energy application method
(Oxygen content%) Microwave treatment
(Oxygen content%) One 13 11 2 10 9 3 9 7 4 7 5

[Table 6] [Table 10] shows the case where the method of Example 1 was used but the solvent was replaced twice with IPA of the present invention by providing ultrasonic shock waves after using various concentration methods. Table 6 shows the results of the heat energy application method, Table 7 shows the microwave application method, Table 8 shows the vacuum decompression method, Table 9 shows the lyophilization method, and Table 10 shows the concentration of the graphite oxide slurry by the centrifugal separation method And water content.

Graphite oxide water condensation rate Moisture content 0% (98% moisture) 0.07 20% 0.06 50% 0.05 80% 0.04 100% (0% moisture) 0.01

Graphite oxide water condensation rate Moisture content 0% (98% moisture) 0.06 20% 0.05 50% 0.04 80% 0.03 100% (0% moisture) 0.01

Graphite oxide water condensation rate Moisture content 0% (98% moisture) 0.06 20% 0.05 50% 0.03 80% 0.03 100% (0% moisture) 0.01

Graphite oxide water condensation rate Moisture content 0% (98% moisture) 0.05 20% 0.04 50% 0.03 80% 0.02 100% (0% moisture) 0.01

Graphite oxide water condensation rate Moisture content 0% (98% moisture) 0.07 10% 0.07 20% 0.06 30% 0.04 40% 0.03

From the above results, it can be seen that the centrifugation method can not completely remove moisture.

When the centrifugation method is applied as the concentration method, it is preferable to collect the precipitate after centrifugation at rpm 3,000 or more. Concentration of the graphite oxide slurry by centrifugation may be followed by other concentration methods to achieve efficient concentration.

In order to obtain graphite oxide dispersed in the oil phase such as toluene, a step of replacing with a solvent of two or more stages is required. Initially, to remove the water contained in the graphite oxide, it can be sufficiently washed with an amphoteric solvent such as IPA and then washed with toluene which is compatible with IPA. In the case of washing with toluene from the beginning, a desired dispersion is not obtained and phase separation occurs. Concretely, toluene was added to the IPA-based graphite oxide slurry obtained in Example 1 at a rate of about 5 times and high-speed blading was performed by sufficiently applying molecular weight unit shear force (molecular unit shock wave) so that IPA and toluene solvent were sufficiently mixed The process of dropping the IPA molecules on the surface of the oxide was repeated, and the upper layer liquid was discarded and the toluene was added to the lower precipitate. The toluene-containing graphite oxide slurry was prepared by repeating this process three times or more (FIG. 2 (c) Reference).

The non-aqueous graphite oxide slurries obtained in [Example 1] and [Example 2] were coated on a glass substrate by spin coating (1,500 rpm) and coated with a graphite oxide slurry having a thickness of 300 to 500 nm, followed by drying at 80 캜 for 1 hour, A coating film could be obtained. The surface-OH and -COOH groups could be confirmed by FT-IR, and no molecules of water adsorbed on the molecule were observed. Through XRD diffraction, it was confirmed that the interplanar spacing of the graphite oxide was 8 ~ 10 Å (angstrom), which means that the coating film exists in the form of graphite oxide.

The reduced graphite oxide coating film was obtained by heat-treating the graphite oxide coating film obtained in [Example 3] above at 400 ° C in a nitrogen atmosphere (at a heating rate of 10 ° C / min). It was confirmed by FT-IR that the surface-OH and -COOH groups disappeared almost completely, and no molecule of water adsorbed on the molecule was observed. The XRD diffraction method confirmed that the interplanar spacing of the reduced graphite oxide was 3.8 Å (angstrom) or less, which means that the coating film exists in reduced graphite oxide form.

10% of an IPA-containing graphite oxide slurry, 40% of a polyamic acid binder, and 40% of an IPA solvent prepared in [Example 1] were mixed to prepare a functional coating solution (see Fig. 4). The coating solution was coated on an aluminum plate and then heat-treated at 300 to 400 ° C to prepare a PI (polyimide) coating film containing graphite oxide.

The coatings were found to have very good acid resistance and very good ability to release heat. In this process, the transparent coating changes to black by heat treatment, and when the film is thick, it becomes completely black. This is because the carboxyl groups (-COOH) and the hydroxyl groups (-OH) on the surface of the graphite oxide are decomposed by heat during the heat treatment process to become nano graphite (reduced graphite oxide). During this heat treatment process, the polyamic acid is changed to polyimide. Therefore, when the polyamic acid-solvent-substituted graphite oxide coating solution is heat-treated at 300 to 400 ° C, it is converted into a completely reduced graphite oxide-PI coating material. It is impossible to disperse the graphite oxide aqueous slurry into the polyamic acid from the beginning.

FIG. 6 is a photograph of the graphite oxide-PI-based coating solution coated on the copper gasket in the above Example 5, followed by heat treatment at a gradually increased temperature. The graphite oxide-PI-based coatings exhibit high heat resistance that can withstand even at 550 DEG C (the left copper portion is observed in the oxidized portion and the right portion remains intact), polyimide is said to withstand not more than 400 DEG C , And graphite oxides can not withstand more than 400 ° C in air and burn out. However, according to the principle of the present invention, a PI-based composite reinforced with graphite oxide (or reduced graphite oxide) exhibits remarkable ultra-high heat resistance that can withstand up to 550 占 폚.

As a result, the two-dimensional plate structure of the graphite oxide in the non-aqueous coating liquid can be maintained without bruising, as described in [Example 1] It is reflected as excellent physical properties. If a two-dimensional graphite oxide (or reduced graphite oxide) structure is wrinkled in the coating liquid, it naturally also wrinkles in the coating, which acts as an impurity and rather lowers the physical properties of the original polymer.

The coated part of [Example 7] was immersed in a hydrochloric acid solution for 24 hours, and the coating part and the lower metal part were examined. As a result, damage of the film and metal corrosion phenomenon were not found. Therefore, the results of Examples 7 and 8 show that coating solutions and coatings containing graphite oxides can provide new physical properties in polymer fields that have not been provided so far, / No strong equipment in a strong atmosphere "is suggested. That is, in the fluoric acid system, glass products can not be used, and glass products can not be made large. In case of large chemical equipment, SUS type reactor is coated with Teflon, and Teflon has a short life span. It is anticipated that the difficulty can be solved by applying the graphite oxide-PI precursor coating solution to such a field, and the actual beaker coating experiment showed the physical properties that can withstand the hydrofluoric acid.

As a result, as described in [Example 1], the principle of the present invention makes it possible to keep the two-dimensional plate structure of the graphite oxide in the non-aqueous coating liquid well unbreakable, and the two- It is reflected as excellent physical properties. If a two-dimensional graphite oxide (or reduced graphite oxide) structure is wrinkled in the coating liquid, it is naturally wrinkled in the coating, which acts as an impurity and deteriorates the physical properties of the original polymer.

The partial solvent substitution (co-solvent) concept can be added without completely replacing the solvent to add the polymer PMMA. Namely, as the first step, the water-based graphite oxide is completely replaced with NMP by using the principle of the present invention, and then partly substituted with a solvent with dichloromethane (in the form of a co-solvent) to obtain NMP / dichloromethane / PMMA / graphite oxide To form a coating solution. In this way, a PMMA composite membrane containing about 5% of graphite oxide was obtained by preparing a mixture of NMP 40%, dichloromethane 40%, PMMA 19% and graphite oxide 1% (weight ratio) As the content of graphite oxide is reduced, the transparency of the coating film increases.

Since the polycarbosilane polymer does not dissolve in IPA, the IPA-solubilized graphite oxide slurry obtained in [Example 1] was once again subjected to solvent substitution with NMP using the principle of the present invention. The solid content of the obtained NMP solvent graphite oxide slurries was 9% as a result of thermal analysis. The graphite oxide-polycarbosilane coating solution was prepared by mixing 5% by weight of the NMP-containing slurry, 50% by weight of NMP solvent and 20% by weight of polycarbosilane.

The coating solution obtained in Example 10 was coated on an alumina base material and then heat-treated in a nitrogen atmosphere at 100 to 200 ° C and 300 to 900 ° C stepwise to prepare a nano-sheet reduced graphite oxide-reinforced SiOC-based ceramic composite. Heat treated SiOC films without graphite oxide may crack (crack) or peel off the film even at small impacts. However, the composite film to which the principle of the present invention was applied did not cause such a phenomenon, and showed a physical property that could be heated by a torch above 900 DEG C as shown in FIG. By changing the heat treatment conditions, SiOC can be converted to SiC. Thus, the results shown in [Example 10] and [Example 11] provide a composite ceramic membrane in which graphite oxide or reduced graphite oxide is first reinforced.

This result shows that the principle of the present invention as described in [Example 1] makes it possible to keep the two-dimensional plate structure of the graphite oxide in the non-aqueous coating liquid well and to keep the two-dimensional plate structure well inside the coating resultant It is reflected as excellent physical properties. If a two-dimensional graphite oxide or a reduced graphite oxide structure is wrinkled in the coating liquid, it naturally curls in the coating, which acts as an impurity and deteriorates the physical properties of the original ceramic.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It is therefore intended that the appended claims cover such modifications and variations as fall within the true scope of the invention.

none

Claims (9)

(a) oxidizing graphite to produce a water-based graphite oxide slurry;
(b) concentrating said aqueous graphite oxide slurry to produce a concentrated slurry;
(c) preparing a solution in which an excessive amount of an amphoteric solvent is added to the concentrated slurry;
(d) providing molecular shock waves to said solution; And
(e) repeating the steps (c) to (d) two or more times; ≪ / RTI > wherein the graphite oxide-enriched slurry coating solution comprises at least one graphite oxide.
The method of claim 1,
(f) adding an excess flow solvent to the solution to prepare a mixed solution;
(f-1) providing a molecular unit shock wave to the mixed solution; And
(f-2) repeating the steps (e) to (e-1) at least twice to prepare a coating solution; ≪ / RTI > further comprising the steps of: preparing a slurry of graphite oxide;
The method of claim 1,
(e-1) adding a predetermined amount of a flowable solvent to the solution; ≪ / RTI > wherein the graphite oxide-enriched slurry coating solution comprises at least one graphite oxide.
The method of claim 1,
In the step (b), the aqueous graphite oxide slurry is concentrated by any one of a room temperature drying method, a thermal energy application method, a vacuum decompression method, a microwave application method, a centrifugal precipitation method and a freeze drying method. A method for producing a slurry coating liquid.
The method of claim 1,
The method for producing a graphite oxide coating solution according to any one of claims 1 to 3, wherein the step (c) is performed by a physical energy application method, a thermal energy application method, or a microwave application method.
The method of claim 5,
(C) and (f) are performed by at least one of an ultrasonic application method, a shear force application method, an ultrafast blading, and an ultrafast stiring. A method for producing a graphite oxide coating liquid.
The method of claim 1,
The amphiphilic solvent to be added in step (b) may be at least one selected from the group consisting of propanol, acetone, isopropanol (IPA), NMP (1-methyl-2-pyrrolidinone), CAN (Ceric Ammonium Nitrate), GBL (gammabutylolactone) (Ethylene glycol), glycerol, TEG (tetraethylene glycol), MIPA (monoisopropanolamine), EDA (methylbetamethoxypropionate), MEA (monoethanolamine) Catechol, DETA (diethylenetriamine), DGME (diethylene glycol monoethyl ether), MMA (methyl methacrylate), DMF (dimethyl formamide), CCl4, DCE (1,2- But are not limited to, 1,2-dichlorobenzene, HMPA, DMEU, MC, dichloromethane, methanol, ethanol, butanol, dioxane, tetrahydrofuran (THF), acetone, acetonitrile , 1-propanol, ethylene glycol, pyridine, hydrazine, and nitromethane. Cargo coating method.
The method of claim 1,
The method of any one of the above-described (a) to (e), wherein the binder, monomer, polymer, resin, ceramic precursor polymer, polyimide precursor, metal binder, ceramic binder, A method for producing a flowable solvent-containing graphite oxide coating liquid, wherein at least one of an oil, a dispersant, an acid, a base, a salt, an ionic species, a labeling agent and a pressure-sensitive adhesive is added as a functional additive.
9. A method for producing a graphite oxide coating, comprising coating a base material with a graphite oxide coating liquid prepared by the method of any one of claims 1 to 8, followed by heat treatment.

Images