1. A coated substrate for large scale production of graphene oxide films, characterized by: the coating substrate is made of synthetic fibers, the texture tissue is regular textile texture, and the yarn structure is filament yarn.

2. The coated substrate for large-scale production of graphene oxide films according to claim 1, wherein: the coating base material is made of terylene, polypropylene fiber, chinlon, acrylic fiber, vinylon and polyvinyl chloride fiber, and preferably polypropylene fiber.

3. The coated substrate for large-scale production of graphene oxide films according to claim 1, wherein: the grain weave of the coating base material is plain weave, twill weave, satin weave or the combination weave thereof.

4. The coated substrate for large-scale production of graphene oxide films according to claim 1, wherein: the yarn structure of the coated substrate is monofilament, multifilament, a combination of monofilament and multifilament, preferably monofilament.

5. The coated substrate for large-scale production of graphene oxide films according to claim 1, wherein: the thickness of the coated substrate is (200-800) μm, preferably 500 μm; and/or

The coated substrate has a warp density of (100- & ltwbr & gt 500- & ltwbr & gt/inch, preferably 200- & ltwbr & gt/inch; and/or

The coated substrate has a pick density of 50-500 counts/inch, preferably 100 counts/inch.

6. The coated substrate for large-scale production of graphene oxide films according to claim 1, wherein:

the coated substrate has an air permeability of (50-300) L/m²S, preferably 100L/m²S; and/or

The tensile strength of the coated substrate is more than 2000N; and/or

The surface tension of the coated substrate is (50-500) mN/m, preferably 100 mN/m.

7. The preparation method of the graphene oxide film is characterized by comprising the following steps: uniformly coating the defoamed graphene oxide slurry on the coating substrate of any one of claims 1 to 6, drying the coating substrate, wetting and stripping the substrate to obtain a graphene oxide film; preferably, the wetting mode is double-sided water spray wetting.

8. The method for producing a graphene oxide film according to claim 7, wherein: the solid content of the graphene oxide slurry is (5-10)%, preferably 8%; and/or

The viscosity of the graphene oxide slurry is (10000-50000) mPa & s, preferably 20000mPa & s; and/or

The average sheet diameter of the graphene oxide in the graphene oxide slurry is (1-5) mu m, preferably 2 mu m; and/or

The coating thickness of the graphene oxide slurry is (0.5-5.0) mm, preferably 1.5 mm.

9. The method for producing a graphene oxide film according to claim 7 or 8, wherein: the coating drying temperature is (70-130) DEG C, preferably (100-; and/or

The coating drying air speed is (5-50) m/s, preferably (20-50) m/s, most preferably 20 m/s; and/or

The coating drying speed is (1-10) m/min, preferably (3-10) m/min, most preferably 3 m/min.

10. A graphene oxide film, characterized in that: is prepared by the preparation method of any one of claims 7 to 9.

Background

In the traditional coating industry, the solution or slurry is coated on a substrate, and generally does not need to be peeled off after being dried, or the solution or slurry needs to be peeled off but has higher drying speed and low requirement on the substrate. The coating substrate used is generally a gas-impermeable material such as a PET film or a metal film.

The graphene oxide preparation process is shown in figure 1. In the graphene oxide preparation process, if conventional coating materials such as PET and metal thin films are used, the following main problems exist:

1. the drying speed is slow

Reason analysis:

1) an airtight base material is used, moisture in the graphene oxide slurry can be evaporated only through one side in contact with air, and the single side is dried;

2) the graphene oxide film is prepared by a coating and drying mode, the solvent of the graphene oxide slurry is generally water, and the saturated vapor pressure of the water is relatively lower at the same temperature compared with the common coating and drying solvent;

3) the graphene oxide slurry has high viscosity, the solid content of the graphene oxide slurry is limited to be less than 10%, and the thickness of the slurry to be coated is high in order to obtain a graphene oxide film with a certain thickness;

4) in the process of coating and drying the graphene oxide slurry, the surface layer is firstly assembled, the drying film forming speed is high, the formed film is compact, and the channel for evaporating the water in the slurry is blocked.

2. When coated at a high thickness, the appearance is liable to blister

Reason analysis: mainly because of the slow drying speed, at a certain drying temperature, moisture stagnates in the graphene oxide slurry for a long time, and a certain cavity is formed, namely, the appearance bubbling phenomenon.

3. The graphene oxide film after drying is not easy to peel off from the base material, and the uniformity of the surface of the peeled graphene oxide film is poor

Reason analysis: the surface tension of the coated substrate and the graphene oxide slurry are not matched.

4. The residual graphene oxide film on the coating substrate after stripping is more and can not be repeatedly used

Reason analysis: the graphene oxide film is not easily peeled off from the substrate, and further, the surface tension of the substrate is not matched with that of the graphene oxide slurry.

5. The graphene oxide film is brittle and easy to break

Reason analysis: the graphene oxide film needs to be wet after being coated and dried, and if an airtight substrate is used, the graphene oxide film can only be wet from one side contacting air, so that the effect is poor.

Disclosure of Invention

The invention aims to provide a coating substrate for preparing a graphene oxide film on a large scale and the prepared graphene oxide film. The invention uses the synthetic fiber with good air permeability as the coating base material, and effectively solves the technical problems of slow drying speed, bulge and damage of the appearance of the graphene oxide film, poor surface uniformity, unreusable coating base material and the like in the prior art.

In order to realize the technical purpose of the invention, the invention adopts the technical scheme that:

the invention provides a coating substrate for preparing a graphene oxide film on a large scale, which is made of synthetic fibers, the texture tissue is regular textile texture, and the yarn structure is a filament yarn.

Preferably, the material of the coating substrate is terylene, polypropylene, chinlon, acrylon, vinylon, polyvinyl chloride, preferably polypropylene.

Preferably, the texture of the coated substrate is plain, twill, satin, or a combination thereof.

Preferably, the yarn structure of the coated substrate is monofilament, multifilament, a combination of monofilaments and multifilaments, preferably monofilaments.

Preferably, the thickness of the coated substrate is (200-800) μm, preferably 500 μm; and/or

The coated substrate has a warp density of (100- & ltwbr & gt 500- & ltwbr & gt/inch, preferably 200- & ltwbr & gt/inch; and/or

The coated substrate has a pick density of 50-500 counts/inch, preferably 100 counts/inch.

As a preference, the first and second liquid crystal compositions are,

the coated substrate has an air permeability of (50-300) L/m²S, preferably 100L/m²S; and/or

The tensile strength of the coated substrate is more than 2000N; and/or

The surface tension of the coated substrate is (50-500) mN/m, preferably 100 mN/m.

The invention also provides a preparation method of the graphene oxide film, which comprises the steps of uniformly coating the defoamed graphene oxide slurry on the coating base material, drying after coating, wetting and stripping to obtain the graphene oxide film; preferably, the wetting mode is double-sided water spray wetting.

Preferably, the solid content of the graphene oxide slurry is (5-10)%, preferably 8%; and/or

The viscosity of the graphene oxide slurry is (10000-50000) mPa & s, preferably 20000mPa & s; and/or

The average sheet diameter of the graphene oxide in the graphene oxide slurry is (1-5) mu m, preferably 2 mu m; and/or

The coating thickness of the graphene oxide slurry is (0.5-5.0) mm, preferably 1.5 mm.

Preferably, the coating drying temperature is (70-130) deg.C, preferably (100-130) deg.C, most preferably 100 deg.C; and/or

The coating drying air speed is (5-50) m/s, preferably (20-50) m/s, most preferably 20 m/s; and/or

The coating drying speed is (1-10) m/min, preferably (3-10) m/min, most preferably 3 m/min.

The invention also provides a graphene oxide film prepared by the preparation method.

The use of the coated substrate of the invention has the following advantages:

1) the drying speed of the graphene oxide film is increased by (100-;

2) improving the appearance bubbling of the high-thickness graphene oxide film;

3) the graphene oxide film can be easily peeled from the coating substrate, and the appearance uniformity of the surface of the peeled graphene oxide film is improved (the surface tension of the coating substrate and the graphene oxide slurry can be well matched, as shown in fig. 3);

4) the base material is reused, so that the cost is reduced;

5) the wet effect of the graphene oxide film is enhanced, and the appearance damage phenomenon is improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 shows a process for preparing a graphene oxide film.

Fig. 2 shows the appearance of the coated substrate (the side that was in contact with the graphene oxide film when dried) after the 20 th stripping in example 1.

Fig. 3 shows the appearance (reverse side, side in contact with the substrate when dried) of the graphene oxide film after exfoliation in example 1.

Fig. 4 shows the appearance (front side, side in contact with air when dried) of the graphene oxide film after exfoliation in example 1.

Fig. 5 shows the appearance (front side, side in contact with air during drying) of the graphene oxide film after peeling-off when the coated substrate in example 1 was used 150 times.

Fig. 6 shows the appearance of the coated substrate (the side that was in contact with the graphene oxide film when dried) after the 300 th peeling in example 3.

Fig. 7 is the appearance of the coated substrate (the side in contact with the graphene oxide film when dried) after peeling in comparative example 1.

Fig. 8 shows the appearance (reverse side, side in contact with the substrate when dried) of the graphene oxide film after exfoliation in comparative example 1.

Fig. 9 is an appearance view showing bubbling of the graphene oxide film in comparative example 1 (front side, side in contact with air when dried).

Fig. 10 is an appearance view showing a broken graphene oxide film in comparative example 1 (front side, side in contact with air during drying).

Detailed Description

The following examples are given to facilitate a better understanding of the invention, but do not limit the invention. The experimental procedures in the following examples are conventional unless otherwise specified. The test materials used in the following examples were purchased from conventional biochemicals, unless otherwise specified. The quantitative tests in the following examples, all set up three replicates and the results averaged.

The invention provides a coating substrate for preparing a graphene oxide film on a large scale, which comprises the following components in parts by weight:

the material of the coated substrate is a synthetic fiber, such as: terylene, polypropylene, chinlon, acrylic fiber, vinylon and polyvinyl chloride, and preferably polypropylene.

The reason for selecting the above-mentioned material as the coating base material is: light weight, high strength, high antiwear and chemical corrosion resistance, low cost and easy processing. Polypropylene is the most outstanding chemical resistance and moisture conductivity, and is the best substrate for coating.

The texture of the coated substrate is a regular weave, such as a plain weave, twill, satin, or combinations thereof.

The reason for the above requirements on the textile texture is as follows:

the texture is required to be regular, that is, the uniformity is good, so that the graphene oxide film and the graphene heat-conducting film with uniform appearance and roughness can be obtained.

The yarn structure of the coated substrate is a filament yarn, such as monofilament, multifilament, a combination of monofilaments and multifilaments, preferably monofilament.

The reason for selecting filament sand is:

the surface of the filament yarn sand fabric is smooth, the graphene oxide film is easy to strip, and the residue after stripping is reduced;

secondly, the filament sand has higher strength and good wear resistance, and the fabric can be repeatedly used as a coating base material.

The reason for selecting monofilament filament sand is:

compared with multifilament, the monofilament fabric is not easy to block, so that the stripping of the graphene oxide film is easier and the residue after stripping is reduced.

The thickness of the coated substrate is (200- & lt800- & gt) mu m, preferably 500 mu m.

The reason for selecting the above thickness is:

the thickness is too thin, and the support of the coated substrate is insufficient, so that the graphene oxide slurry cannot be molded;

the thickness is too thick, which affects the drying and stripping of the graphene oxide film, and the cost is high and the efficiency is low.

The coating density of the substrate is (100- & lt500- & gt) pieces/inch, preferably 200 pieces/inch; weft density (50-500) counts/inch, preferably 100 counts/inch.

The reason for selecting the warp and weft density is as follows:

the air permeability of the material is ensured to meet the requirement, and meanwhile, the optimal roughness of the graphene oxide film can be obtained under the longitude and latitude density; the warp and weft density is too high, the air permeability is insufficient, the surface roughness of the graphene oxide film is lower, the warp and weft density is too low, the air permeability is too large, and the surface roughness of the graphene oxide film is larger.

The air permeability of the coated substrate is (50-300) L/m²S, preferably 100L/m²/s。

The reason for selecting the air permeability is:

the air permeability is too high, the water permeability is better, and when the graphene oxide film is dried and water is sprayed on the reverse side, the graphene oxide film is too wet, so that the appearance and the peeling are influenced;

the graphene oxide film has low air permeability, is slow to dry, is insufficient in moisture, is easy to damage and is not easy to peel off from a base material;

when the air permeability is 100L/m²And when the coating is used for coating the graphene oxide film, the graphene oxide film is dried quickly and is high in coating efficiency, and the graphene oxide film is easy to peel from the base material, and the appearance of the peeled graphene oxide film is ensured.

The tensile strength of the coated substrate is above 2000N.

The reason for selecting the tensile strength is:

the strength is too low, and the coating is easily broken or deformed under a certain coating tension and using times.

The surface tension of the coated substrate is (50-500) mN/m, preferably 100 mN/m.

The reason for selecting the surface tension is:

the surface tension is too low, the wettability of the graphene oxide slurry on the surface of the base material is poor, and the graphene oxide slurry cannot be uniformly spread and formed into a film;

the surface tension is too high, the peeling property between the graphene oxide film and the base material is poor, and peeling is difficult or a large amount of residue remains after peeling.

The present invention also provides a method for preparing a graphene oxide film, which comprises:

and (3) uniformly coating the defoamed graphene oxide slurry on the coating base material, drying by using a coating machine, wetting and stripping to obtain the graphene oxide film.

The solid content of the graphene oxide slurry is (5-10)%, preferably 8%.

The viscosity of the graphene oxide slurry is (10000-50000) mPas, preferably 20000 mPas.

The average sheet diameter of the graphene oxide in the graphene oxide slurry is (1-5) μm, preferably 2 μm.

The coating thickness of the graphene oxide slurry is (0.5-5.0) mm, preferably 1.5 mm.

When a coating substrate having good air permeability is used, since the coating efficiency is high, a slurry having a higher thickness can be coated to obtain a graphene oxide film having a higher thickness, as compared with a case where an air-impermeable coating substrate is used.

The coating drying temperature is (70-130) DEG C, preferably (100-130) DEG C, and most preferably 100 ℃; the coating drying air speed is (5-50) m/s, preferably (20-50) m/s, most preferably 20 m/s; the coating drying speed is (1-10) m/min, preferably (3-10) m/min, most preferably 3 m/min.

With a substrate that is air permeable, a higher coating and drying temperature, a higher coating and drying air speed, and thus a faster coating speed, can be used relative to an air impermeable substrate. If the air-impermeable base material is dried at an excessively high temperature and wind speed, the film is difficult to form or the appearance after the film is formed is poor.

The method of rewetting is to spray water mist on both sides of the graphene oxide film, that is, to spray water mist from the side of the graphene oxide film that contacts the air, and to spray water mist from the back of the substrate.

The spraying parameters can be adjusted according to the moisture reducing effect, and no specific requirement exists.

Since both sides of the coated substrate are identical, the coated substrate of the present invention can be used on both sides.

After the graphene oxide film is peeled off from the coated substrate of the present invention, the coated substrate can be reused. The number of uses of the coated substrate is (50 to 300) (determined from the appearance of the substrate after use and the appearance of the graphene oxide film), and preferably 150.

The coating base material can be continuously used when the appearance of the coating base material is deformed and has no more residues, and the graphene oxide film prepared by the coating base material has flat appearance and no defects.

And stripping and rolling the wet graphene oxide film.

The parameters of the obtained graphene oxide film were as follows:

the surface of the graphene oxide film is provided with regular lines, which

The surface roughness Ra of the graphene oxide film is (0.5-8.0) mu m; preferably 2.0 μm;

the graphene oxide film has a thickness of (50-500) μm, preferably 150 μm;

the density of the graphene oxide film is (1.0-2.0) g/cm³(ii) a Preferably 1.5g/cm³；

The use of a gas-impermeable substrate such as PET allows coating to be carried out at a lower thickness and drying to be carried out at a lower temperature and wind speed than the use of the coated substrate of the present invention. If the thickness is high, the graphene oxide slurry cannot be completely dried, that is, a film cannot be formed. If the drying is too fast by using a high temperature and wind speed, the film cannot be formed or the appearance after the film is formed is poor.

Example 1

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 8%, the viscosity of 20000mPa & s and the average graphene oxide sheet diameter of 2 mu m on a coating substrate by the thickness of 1.5 mm;

2) the coating base material is polypropylene fiber, the weaving method is twill, the yarn structure is monofilament, the thickness of the polypropylene fiber is 500 mu m, the warp density is 200 pieces/inch, the weft density is 100 pieces/inch, and the air permeability is 100L/m²(ii) s, tensile strength of 2000N, surface tension of 100 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 100 ℃, the wind speed is 20m/s, and the drying speed is 3 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film is a regular line with twill on the surface; the appearance is not damaged, and the thickness is 150 mu m; the density was 1.5g/cm³(ii) a The surface roughness Ra was 2.0. mu.m.

The coated substrate of this example was used on both sides, and was tested to be usable 150 times.

Fig. 2 shows the appearance of the coated substrate (the side that was in contact with the graphene oxide film when dried) after the 20 th stripping in example 1.

FIG. 3 shows the appearance of the graphene oxide film after peeling (on the reverse side, the side in contact with the substrate when dried) when the coated substrate of example 1 was used 20 times.

Fig. 4 shows the appearance (front side, side in contact with air during drying) of the graphene oxide film after peeling off when the coated substrate in example 1 was used 20 times.

Fig. 5 shows the appearance (front side, side in contact with air during drying) of the graphene oxide film after peeling-off when the coated substrate in example 1 was used 150 times.

Example 2

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 5%, the viscosity of 10000mPa & s and the average graphene oxide sheet diameter of 3 mu m on a coating substrate by the thickness of 2.5 mm;

2) the coating base material is nylon, the weaving method is plain weave, the yarn structure is multifilament, the thickness of the nylon is 500 mu m, the warp density is 120 pieces/inch, the weft density is 80 pieces/inch, and the air permeability is 60L/m²S, tensile strength 2500N, surface tensionThe force is 60 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 80 ℃, the wind speed is 12m/s, and the drying speed is 1.2 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film has regular lines with plain weaves on the surface; the thickness is 150 μm; the density was 1.5g/cm³(ii) a The surface roughness Ra was 5.0. mu.m.

The coated substrate of this example had two sides and the number of uses was 80.

Example 3

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 10%, the viscosity of 45000mPa & s and the average graphene oxide sheet diameter of 2 mu m on a coating substrate by the thickness of 0.75 mm;

2) the coating base material is terylene, the weaving method is satin, the yarn structure is single multifilament, the thickness of the terylene is 500 mu m, the warp density is 300 pieces/inch, the weft density is 150 pieces/inch, the air permeability is 120L/m²(ii) s, tensile strength of 3000N, surface tension of 130 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 120 ℃, the wind speed is 30m/s, and the drying speed is 8 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film is a regular line with forged lines on the surface; the thickness is 90 μm; the density was 1.5g/cm³(ii) a The surface roughness Ra was 1.5. mu.m.

The application surface of the coated substrate in this example was double-sided, and the number of applications was 300.

Fig. 6 shows the appearance of the coated substrate (the side that was in contact with the graphene oxide film when dried) after the 300 th peeling in example 3.

Example 4

The preparation method of the graphene oxide film comprises the following steps:

1) coating 5.0mm thick graphene oxide slurry with solid content of 5%, viscosity of 10000mPa & s and average graphene oxide sheet diameter of 1 mu m on a coating substrate;

2) the coating base material is acrylic fiber, the weaving method is twill, the yarn structure is monofilament, the thickness of the acrylic fiber is 200 mu m, the warp density is 100 pieces/inch, the weft density is 50 pieces/inch, and the air permeability is 300L/m²(ii) s, tensile strength 4000N, surface tension 50 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 70 ℃, the wind speed is 5m/s, and the speed is 0.5 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film is a regular line with twill on the surface; the thickness is 300 mu m; the density was 1.5g/cm³(ii) a The surface roughness Ra was 8.0. mu.m.

The coated substrate of this example had two sides and the number of uses was 80.

Example 5

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 10%, the viscosity of 50000mPa & s and the average graphene oxide sheet diameter of 5 mu m on a coating substrate by the thickness of 0.5 mm;

2) the coating substrate is made of vinylon, the weaving method is a plain weave and twill weave combined structure, the yarn structure is multifilament, the thickness of the vinylon is 800 mu m, the warp density is 500 threads/inch, the weft density is 500 threads/inch, and the air permeability is realizedThe ratio is 50L/m²(ii) s, tensile strength of 5000N, surface tension of 500 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 130 ℃, the wind speed is 40m/s, and the speed is 15 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film is a regular line with a plain weave and twill weave combined structure on the surface; the thickness is 60 mu m; the density was 1.5g/cm³(ii) a The surface roughness Ra was 0.5. mu.m.

The coated substrate of this example had both sides used, and the number of times of use was 50.

Example 6

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 9%, the viscosity of 35000mPa & s and the average graphene oxide sheet diameter of 1.5 mu m on a coating substrate by the thickness of 3.5 mm;

2) the coating base material is polyvinyl chloride, the weaving method is a satin and twill combined structure, the yarn structure is monofilament, the polyvinyl chloride has the thickness of 600 mu m, the warp density of 300 threads/inch, the weft density of 400 threads/inch and the air permeability of 180L/m²(s), the tensile strength is 4000N, and the surface tension is 380 mN/m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 110 ℃, the wind speed is 35m/s, and the speed is 0.3 m/min;

4) the dried graphene oxide film is subjected to rewetting by double-sided water mist spraying, namely water mist spraying is carried out from one side of the graphene oxide film, which is in contact with air, and water mist spraying is carried out from the back of the substrate;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film is a regular line with a satin and twill combined structure on the surface; is thick and thickThe degree is 380 mu m; the density was 1.5g/cm³(ii) a The surface roughness Ra was 0.8. mu.m.

The coated substrate of this example had two sides and the number of uses was 60.

Comparative example 1 (comparison with example 1)

The preparation method of the graphene oxide film comprises the following steps:

1) coating graphene oxide slurry with the solid content of 8%, the viscosity of 20000mPa & s and the average graphene oxide sheet diameter of 2 mu m on a coating substrate by the thickness of 1.5 mm;

2) the material PET of the coating substrate is in a thin film shape, and the thickness is 500 mu m;

3) the coated slurry moves along with the coated substrate and is dried by an oven of a coating machine, the drying temperature is 80 ℃, the air speed is 10m/s, and the drying speed is 1m/min (if the air speed is more than 10m/s, and the drying speed is more than 1m/min, the drying speed is too high, the appearance damage and the bubbling phenomenon of the graphene oxide film are more serious, and the film cannot be formed more seriously);

4) the dried graphene oxide film is subjected to rewetting, and the rewetting mode is single-side water mist spraying, namely water mist spraying is carried out from one side, which is in contact with air, of the graphene oxide film;

5) stripping and rolling the wet graphene oxide film;

6) the obtained graphene oxide film has more bubbling and breakage phenomena in appearance, the thickness is 150 mu m, and the density is 1.5g/cm³(ii) a The surface roughness Ra was 20.0. mu.m.

The coated substrate was used on one side 1 times (as can be seen in fig. 5, the material remaining on the PET surface was large and could not be reused, and thus, the coating was performed once).

Fig. 7 is the appearance of the coated substrate (the side in contact with the graphene oxide film when dried) after peeling in comparative example 1.

Fig. 8 shows the appearance (reverse side, side in contact with the substrate when dried) of the graphene oxide film after exfoliation in comparative example 1.

Fig. 9 is an appearance view showing bubbling of the graphene oxide film in comparative example 1 (front side, side in contact with air when dried).

Fig. 10 is an appearance view showing a broken graphene oxide film in comparative example 1 (front side, side in contact with air during drying).

It can be seen that the air speed in example 1 is 2 times that in comparative example 1, the drying temperature is increased from 80 c to 100 c, and the drying speed is 3 times that in comparative example 1, compared to comparative example 1. The obtained graphene oxide has the advantages of obviously improved appearance, high surface uniformity, lower surface roughness of graphene, and no damage and bulge on the appearance.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.