Preparation method of high-temperature-resistant and high-strength graphene / polyimide composite material

Abstract

The invention relates to the technical field of firefighter uniform fireproof flame-retardant cloth, in particular to a preparation method of a high-temperature-resistant and high-strength graphene / polyimide composite material. The method comprises the following steps: carrying out high-pressure homogenization treatment on a graphene suspension, reacting the graphene suspension with 4, 4 '-diaminodiphenyl ether and 3, 3', 4, 4 '-triphenyl diether tetracarboxylic dianhydride in an organic solvent, carrying out suction filtration, and drying an obtained solid substance to obtain powder; dissolving the powder in N, N-dimethylacetamide, and stirring to obtain a colloid; and carrying out heat preservation treatment on the colloid to obtain the graphene / polyimide composite material. The preparation method is simple and easy for large-scale popularization and application. The graphene / polyimide composite material prepared by the method has the characteristics of high temperature resistance and flame retardance.

Description

Technical Field

[0001] The invention relates to the technical field of fireproof and flame-retardant fabrics for fire-fighting clothing, and in particular to a method for preparing a high-temperature resistant and high-strength graphene / polyimide composite material. Background Art

[0002] Fire-fighting fabrics are required to have good waterproof and heat-insulating properties, which can effectively prevent the spread of flames and protect the original properties of the fabric. Chinese invention patent CN 111850777A discloses a method for preparing a polyimide fire-fighting fabric, which has good tensile strength at break, pilling resistance and flame retardant properties. However, since the fabric is made by blending, the performance of the material will be affected by the degree of fiber mixing. Therefore, this invention patent needs further research and exploration to improve the performance stability and durability of the fabric.

[0003] Chinese invention patent CN 113061286 B discloses that multifunctional flame-retardant polyimide aerogel has excellent mechanical properties and flame-retardant properties, and has sensitive temperature sensing, piezoresistive sensing and other functions. However, the preparation method in this invention patent involves plasma treatment and the preparation of two-dimensional thermoelectric nanomaterial dispersion, which is relatively complicated and will increase the material preparation cost. In addition, this invention patent does not clearly explain the application scenarios of the aerogel and the service life of the material, which requires further research and exploration.

[0004] Therefore, providing a method for preparing a graphene / polyimide composite material with a simple preparation process that can effectively improve the flame retardancy, high temperature resistance and high strength of fire-fighting fabrics is of great significance in the technical field of fire-fighting uniform fire-retardant fabrics. Summary of the invention

[0005] Based on the above content, the present invention provides a method for preparing a high-temperature resistant and high-strength graphene / polyimide composite material. By adopting a precursor in-situ assembly method, graphene is added to the polyimide composite material, thereby improving the mechanical properties of the polyimide material and enhancing its high temperature resistance and flame retardancy.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is a method for preparing a graphene / polyimide composite material, comprising the following steps:

[0008] The graphene suspension is subjected to high-pressure homogenization treatment, and then reacted with diamine and dianhydride in an organic solvent, and then filtered, and the obtained solid matter is dried to obtain a powder;

[0009] dissolving the powder in N,N-dimethylacetamide and stirring to obtain a colloid;

[0010] The colloid is subjected to heat preservation treatment to obtain the graphene / polyimide composite material.

[0011] Furthermore, the pressure of the high-pressure homogenization treatment is 1500-2500 MPa, and the time is 15-45 min.

[0012] If the pressure of the high-pressure homogenization treatment is too small, the particle size of the treated graphene flakes will be too large and difficult to assemble; if the pressure is too large, the particle size of the treated graphene flakes will be too small and the strength will be reduced; if the time is too long, the surface energy of the graphene will increase and the graphene will be easily agglomerated; if the time is too short, the treated graphene flakes will not be uniform enough. Therefore, the present invention preferably limits the pressure of the high-pressure homogenization treatment to 1500-2500MPa and the time to 15-45min.

[0013] Furthermore, the mass concentration of graphene in the graphene suspension is 5%-15%, and the solvent is one of o-xylene, N,N-dimethylacetamide, and hydrazine hydrate.

[0014] If the mass concentration of graphene in the graphene suspension is too high, the suspension will have poor fluidity and uneven composition, which will affect the next step of compounding; if it is too low, the subsequent composite graphene content will be too low, which will affect the performance of the final product. Therefore, the preferred mass concentration of graphene in the graphene suspension of the present invention is 5-15%.

[0015] Furthermore, the diamine is 4,4'-diaminodiphenyl ether; and the dianhydride is 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride.

[0016] Furthermore, the content of graphene in the graphene / polyimide composite material is 20-60wt%.

[0017] Too high a content of graphene will lead to graphene segregation in the composite material, affecting the overall performance; too low a content of graphene will hardly have a strengthening effect. Therefore, the present invention preferably limits the content of graphene in the graphene / polyimide composite material to 20-60wt%.

[0018] Furthermore, the molar ratio of the diamine to the dianhydride is 1:1.

[0019] Furthermore, the organic solvent is one of xylene, N,N-dimethylacetamide and hydrazine hydrate.

[0020] Furthermore, the reaction is specifically carried out at 170° C. for 5-6 hours under stirring conditions.

[0021] If the reaction temperature exceeds the above temperature, the desired polyimide polymer chain cannot be synthesized. If the reaction time exceeds the above time, the synthesized polyimide molecular chain will be too short.

[0022] Furthermore, the drying is specifically vacuum drying at 270-290° C. for 20-24 hours.

[0023] If the drying temperature is higher than the above-mentioned temperature, the polyimide will react, and if it is lower than the above-mentioned temperature, the drying will be incomplete; if the drying time is higher than the above-mentioned time, the polyimide will react, and if it is lower than the above-mentioned time, the drying will be incomplete.

[0024] Further, the powder is dissolved in N,N-dimethylacetamide with a solid content of 15% and stirred to obtain a colloid; the heat preservation treatment is specifically to increase the temperature to 350° C. at a speed of 5° C. / min and keep the temperature for 3 hours.

[0025] The purpose of preparing the colloid by dissolving the powder in N,N-dimethylacetamide with a certain solid content is: on the one hand, to further uniformly compound the graphene and the polyimide, and on the other hand, to perform imidization to enhance the strength of the composite material.

[0026] If the heating rate, temperature and time of the heat preservation treatment exceed the above-mentioned range, the graphene and polyimide will be uneven, or the imidization degree will be insufficient, which will affect the strength of the material.

[0027] A second technical solution of the present invention is a graphene / polyimide composite material prepared according to the above-mentioned preparation method.

[0028] The third technical solution of the present invention is the use of the above-mentioned graphene / polyimide composite material in the preparation of fire-fighting fabrics.

[0029] The present invention discloses the following technical effects:

[0030] The preparation method of the invention is simple and easy to be popularized and applied on a large scale.

[0031] The graphene / polyimide composite material prepared by the method of the present invention has the characteristics of high temperature resistance and flame retardancy. Due to the structural similarity between graphene and polyimide, the addition of graphene does not affect the synthesis of polyimide, but improves the crystallinity of polyimide, and transforms from a semi-crystalline structure to a crystalline order, so the addition of graphene can improve the mechanical properties of polyimide materials. And the addition of graphene can improve the conduction efficiency of free electrons inside polyimide and enhance the overall thermal uniformity of polyimide materials. At the same time, the carbon surface of graphene in the graphene / polyimide composite material can act as a free radical scavenger to delay the breakage of the chain and the formation of free radicals during thermal degradation, so that the overall graphene / polyimide composite material has higher thermal stability and flame retardant characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 The diagram is a schematic diagram of the synthesis process of the graphene / polyimide composite material of the present invention and the molecular formulas of various raw materials and polyimide.

[0034] Figure 2 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 1 of the present invention.

[0035] Figure 3 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 2 of the present invention.

[0036] Figure 4 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 3 of the present invention.

[0037] Figure 5 This is the combustion infrared temperature diagram of the polyimide fire-fighting fabric prepared in the application example of the present invention. DETAILED DESCRIPTION

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0040] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0041] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0042] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0043] The "%" described in the present invention, unless otherwise specified, refers to mass percentage.

[0044] Unless otherwise specified, the raw materials used in the embodiments of the present invention can be obtained through commercial sources.

[0045] The graphene sheet used in the embodiments of the present invention has a diameter of 50-500 nm and a thickness of 0.8-1.2 nm.

[0046] The 5% graphene / o-xylene suspension described in the embodiment of the present invention is prepared by the following steps: adding graphene at a ratio of 5%wt to o-xylene and stirring at a speed of 600r / min for 20min.

[0047] Example 1

[0048] A 5% graphene / o-xylene suspension was sent to a high-pressure homogenizer and the graphene / o-xylene suspension was dispersed at a pressure of 1500MPa for 45 minutes. 60.2g of the dispersed graphene / o-xylene suspension was added to a three-necked flask (500mL) with 4,4'-diaminodiphenyl ether (4g, 0.02mol), 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride (8.04g, 0.02mol) and xylene (300ml) and mechanically stirred at 170°C for 6 hours to react. After the reaction was completed, the reaction solution was filtered with a Buchner funnel, and the obtained solid material was vacuum dried at 280°C in a vacuum drying oven for 24 hours to obtain a black solid powder. The above black solid powder was dissolved in N,N-dimethylacetamide (DMAC) with a solid content of 15%wt, and stirred at a speed of 300r / min for 10 minutes to obtain a black colloid. The black colloid was heated to 350° C. at a rate of 5° C. / min and kept warm for 3 hours to obtain a graphene / polyimide composite material. The content of graphene in the graphene / polyimide composite material was 20 wt %.

[0049] Example 2

[0050] 5% graphene / o-xylene suspension was sent to a high-pressure homogenizer, and the graphene / o-xylene suspension was dispersed for 30 minutes at a pressure of 2000MPa. 120.4g of the dispersed graphene / o-xylene suspension was added to a three-necked flask (500mL) with 4,4'-diaminodiphenyl ether (4g, 0.02mol), 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride (8.04g, 0.02mol) and xylene (300ml) and reacted at 170°C with mechanical stirring for 6 hours. After the reaction was completed, the reaction solution was filtered with a Buchner funnel, and the obtained solid material was vacuum dried at 280°C in a vacuum drying oven for 24 hours to obtain a black solid powder. The above black solid powder was dissolved in N,N-dimethylacetamide (DMAC) with a solid content of 15%wt, and stirred at a speed of 300r / min for 10 minutes to obtain a black colloid. The black colloid was heated to 350° C. at a rate of 5° C. / min and kept at this temperature for 3 hours to obtain a graphene / polyimide composite material, wherein the content of graphene in the graphene / polyimide composite material was 40 wt%.

[0051] Example 3

[0052] A 5% graphene / o-xylene suspension was sent to a high-pressure homogenizer, and the graphene / o-xylene suspension was dispersed for 15 minutes at a pressure of 2500 MPa. 180.6 g of the dispersed graphene / o-xylene suspension was added to a three-necked flask (500 mL) with 4,4'-diaminodiphenyl ether (4 g, 0.02 mol), 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride (8.04 g, 0.02 mol) and xylene (300 ml) and reacted at 170 ° C for 6 hours with mechanical stirring. After the reaction was completed, the reaction solution was filtered with a Buchner funnel, and the obtained solid material was vacuum dried at 280 ° C in a vacuum drying oven for 24 hours to obtain a black solid powder. The above black solid powder was dissolved in N, N-dimethylacetamide (DMAC) with a solid content of 15% wt, and stirred at a speed of 300 r / min for 10 minutes to obtain a black colloid. The black colloid was heated to 350° C. at a rate of 5° C. / min and kept at this temperature for 3 hours to obtain a graphene / polyimide composite material, wherein the content of graphene in the graphene / polyimide composite material was 60 wt%.

[0053] Comparative Example 1

[0054] 4,4'-diaminodiphenyl ether (4g, 0.02mol), 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride (8.04g, 0.02mol) and xylene (300ml) were added to a three-necked flask (500mL) and mechanically stirred at 170°C for 6 hours for reaction. After the reaction was completed, the reaction solution was filtered with a Buchner funnel, and the obtained solid material was vacuum dried in a vacuum drying oven at 280°C for 24 hours to obtain a light yellow solid powder. The above light yellow solid powder was dissolved in N,N-dimethylacetamide (DMAC) with a solid content of 15%wt, and stirred at a speed of 300r / min for 10 minutes to obtain a yellow colloid. The above yellow colloid was heated to 350°C at a speed of 5°C / min and kept warm for 3h. The polyimide material was obtained.

[0055] The mechanical properties and thermal properties (referring to GB / T 36976-2018 standard) of the graphene / polyimide composite materials prepared in Examples 1-3 and the polyimide material prepared in Comparative Example 1 were tested, and the results are shown in Tables 1 and 2.

[0056] Table 1 Mechanical properties of samples

[0057]

[0058] Table 2 Thermal properties of samples

[0059]

[0060] The 5% thermal decomposition temperature of Example 3 in Table 2 is lower than that of Example 1 and Example 2. This is because the 60% graphene content will cause a portion of the graphene to not be coupled with the polyimide, and this portion of the graphene will decompose and fall off at a lower temperature, so the 5% thermal decomposition temperature is lower.

[0061] Through the above tests, it can be found that adding 40% graphene can increase the tensile strength of the polyimide composite material by about 62.2% and the flexural strength by about 21.6%. The mechanical properties of the polyimide composite resin prepared by homogenized graphene are improved in all parameters. The performance is best when the graphene content is 40wt.%, and the tensile strength of the composite resin reaches 78.84±7MPa and the flexural strength is 185.56±7MPa, which are 108.9% and 22.05% higher than those of pure resin, respectively.

[0062] Figure 2 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 1 of the present invention.

[0063] Figure 3 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 2 of the present invention.

[0064] Figure 4 This is a combustion infrared temperature diagram of the graphene / polyimide composite material prepared in Example 3 of the present invention.

[0065] Depend on Figure 2-4 It can be seen that at the temperature shown in the picture, the composite material did not burn, demonstrating its excellent high temperature resistance.

[0066] Application Examples

[0067] The black colloid (graphene / polyimide composite material) prepared in the above-mentioned Example 2 is spun according to the wet spinning process, and the spinneret shape is a trilobal shape with grooves on the surface. The obtained polyimide composite material precursor is heated to 350°C at a rate of 5°C / min and kept warm for 3h, so as to obtain a polyimide composite material fiber filament with a trilobal grooved cross section, with a specification of 100D. The polyimide composite material fiber filament with a trilobal grooved cross section is washed, oiled, and dried, and then two bundles of fibers are twisted to obtain a polyimide filament with a specification of 200D. The polyimide composite material filament is blended with a polyimide yarn with a specification of 40 in a weight ratio of 10%:90%, and the surface density of the fabric is 200gsm; the fabric is waterproofed and padded; and then baked and shaped at a temperature of 160°C for 3min to obtain a high-strength flame-retardant and waterproof polyimide fire-fighting fabric. Its performance is shown in Table 3:

[0068] Table 3 Fire protection fabric performance

[0069]

[0070] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing a graphene / polyimide composite material, characterized in that: The following steps are involved: The graphene suspension is subjected to high-pressure homogenization treatment, and then reacted with diamine and dianhydride in an organic solvent, and then filtered, and the obtained solid matter is dried to obtain a powder; dissolving the powder in N,N-dimethylacetamide and stirring to obtain a colloid; The colloid is subjected to heat preservation treatment to obtain the graphene / polyimide composite material.

2. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The mass concentration of graphene in the graphene suspension is 5%-15%, the solvent is one of o-xylene, N,N-dimethylacetamide and hydrazine hydrate; the diamine is 4,4'-diaminodiphenyl ether; and the dianhydride is 3,3',4,4'-triphenyl diether tetracarboxylic dianhydride.

3. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The content of graphene in the graphene / polyimide composite material is 20-60wt%.

4. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The molar ratio of the diamine to the dianhydride is 1:

1.

5. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The organic solvent is one of xylene, N,N-dimethylacetamide and hydrazine hydrate.

6. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The reaction is specifically carried out at 170° C. for 6 hours under stirring conditions.

7. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: The drying is specifically performed at 270-290° C. under vacuum for 20-24 hours.

8. The method for preparing the graphene / polyimide composite material according to claim 1, characterized in that: dissolving the powder in N,N-dimethylacetamide at a solid content of 15% and stirring to obtain a colloid; The heat preservation treatment specifically includes heating the temperature to 350° C. at a rate of 5° C. / min and keeping the temperature for 3 hours.

9. A graphene / polyimide composite material prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the graphene / polyimide composite material as claimed in claim 9 in the preparation of fire-fighting fabrics.

Images