A kind of multifunctional polyester fiber modified by graphene quantum dots and preparation method thereof

Abstract

The present invention relates to a multifunctional polyester fiber modified by graphene quantum dots and a preparation method thereof, and belongs to the technical field of functional fibers. The preparation method of the present invention comprises the following steps: S1, under alkaline conditions and the action of a catalyst, graphene quantum dots and dopamine hydrochloride react in water in the first stage, and then continue to add a benzaldehyde compound alcohol solution for the second stage reaction to obtain modified graphene quantum dots; S2, granulating the modified graphene quantum dots and polyester powder to obtain a multifunctional polyester masterbatch; S3, spinning the multifunctional polyester masterbatch and polyester slices to obtain a multifunctional polyester fiber modified by graphene quantum dots. The far-infrared normal emissivity of the multifunctional polyester fiber modified by the graphene quantum dots is 0.89-0.92, the far-infrared radiation temperature rise is 2.4℃-3.2℃, the breaking strength is 3.3cN / detx-3.5cN / detx, and the antibacterial property is higher than 99.9%.

Description

Technical Field

[0001] The invention belongs to the technical field of functional fibers, and in particular relates to a multifunctional polyester fiber modified by graphene quantum dots and a preparation method thereof. Background Art

[0002] Polyester fiber is the fastest growing, highest-yielding, and most-used fiber among all kinds of synthetic fibers. It is currently the largest variety of synthetic fibers. Polyester fiber has excellent wrinkle resistance and shape retention, high strength and elastic recovery ability, and its excellent properties such as durability, wrinkle resistance, ironing-free, and non-sticky hair are widely used in furniture, car seats, mats, bedding, toys, and other fields. In recent years, multifunctional polyester fibers with far-infrared, magnetic, antistatic, and antibacterial properties have become the main development direction. Modifying polyester fibers is an important method to obtain functional fibers. Graphene is widely used in the modification of polyester fibers because of its good electrical and thermal conductivity, far-infrared, and antibacterial functions. Graphene quantum dots are special graphene fragments with nanometer-level sizes in three dimensions, and they have the dual excellent properties of graphene and quantum dots. However, graphene quantum dots have high surface energy and poor compatibility with polyester fibers. They are easy to agglomerate in polyester fibers, resulting in spinning difficulties and even damage to spinning equipment.

[0003] Chinese invention patent CN103044865A discloses a method for preparing an amino-graphene modified PET material, wherein amino-graphene is first prepared, and then melt-blended with a polyester material to prepare an amino-graphene modified PET material. The amino group of amino-graphene can hydrogen bond with polyester to help disperse graphene in the PET material. Under high-temperature banburying conditions, the amino group can partially exchange with the polyester bond to generate an amide group, thereby linking graphene and PET with isostructural chemical bonds, further improving the compatibility of graphene in the PET material, thereby preparing a graphene-modified PET material in which graphene is uniformly dispersed in PET. However, polyester fibers are rich in aromatic benzene rings and ester bonds, and have limited affinity and compatibility with amino groups. During high-temperature banburying, the amino group reacts to generate a polyamide structure, which easily causes the mechanical properties of the polyester material to be damaged.

[0004] Chinese invention patent CN107164822A discloses a graphene polyester fiber with deodorizing function. First, silica gel and dispersant are used to prepare a silica gel-coated graphene particle dispersion, and then the multifunctional polyester fiber is prepared by melt blending. However, due to the influence of charge, the silica gel-coated graphene particles move to the surface of the spinning solution during the spinning process, resulting in the silica gel-coated graphene particles being distributed on the fiber surface. During the process of water washing and friction, the graphene particles on the surface are easily fallen off the fiber surface.

[0005] Chinese invention patent CN110106576A discloses a method for preparing modified graphene polyester fiber, wherein metallic copper is crushed into copper particles, copper ions are soaked in benzotriazole to obtain modified copper ions, graphene whose surface is functionalized with sulfonic acid groups is stirred and dispersed to prepare graphene particles, and then copper-modified polyester fiber masterbatch and graphene masterbatch are melt-blended to obtain modified graphene polyester fiber. However, the introduction of anionic sulfonic acid groups cannot improve the dispersion and compatibility of graphene in polyester fibers.

[0006] Chinese invention patent CN117210967A discloses a method for preparing a skin-core structured modified graphene regenerated polyester fiber, wherein polydopamine and imidazole-based ionic liquid are used to non-covalently modify graphene oxide to obtain modified graphene; then the modified graphene and regenerated polyester are melt-spun to prepare skin-core structured modified graphene regenerated polyester fiber. However, there is no reactive group in the imidazole-based ionic liquid, and the binding performance with polydopamine is poor, which causes the imidazole-based ionic liquid to fall off easily, and the ionic liquid is adsorbed on the surface of the modified graphene, making its surface smooth and making it more difficult to mix with polyester.

[0007] Chinese invention patent CN105177753A discloses a method for preparing a military anti-melting, anti-static, high-strength, flame-retardant polyester, wherein graphene oxide is modified by p-phenylenediamine to obtain modified graphene oxide; then PET slices are mixed with a compound flame retardant, an anti-drip agent masterbatch, a phenolic antioxidant, and modified graphene oxide, and high-temperature shearing is performed to obtain a molten spinning solution; and military anti-melting, anti-static, high-strength, flame-retardant polyester is obtained by spinning. However, there are very few reactive groups on the surface of graphene oxide, and the amino group of p-phenylenediamine cannot react with graphene oxide by covalent bonds, and p-phenylenediamine does not polymerize, but is only physically adsorbed on the surface of graphene oxide, resulting in poor modification effect.

[0008] Based on the above background, it is still necessary to develop multifunctional polyester fibers based on graphene quantum dots. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a multifunctional polyester fiber modified with graphene quantum dots and a preparation method thereof. Firstly, dopamine hydrochloride and benzaldehyde compounds are used to modify graphene quantum dots by in-situ polymerization deposition to obtain modified polydopamine-coated graphene quantum dots, i.e., modified graphene quantum dots; then, the modified graphene quantum dots are used to prepare the multifunctional polyester fiber modified with graphene quantum dots by melt blending.

[0010] The first object of the present invention is to provide a method for preparing a multifunctional polyester fiber modified with graphene quantum dots, comprising the following steps:

[0011] S1. Under alkaline conditions and the action of a catalyst, graphene quantum dots and dopamine hydrochloride are reacted in water in a first stage, and then a benzaldehyde compound alcohol solution is added to carry out a second stage reaction to obtain modified graphene quantum dots; the benzaldehyde compound is selected from one or more of terephthalaldehyde, isophthalaldehyde and 2,5-dihydroxyterephthalaldehyde;

[0012] S2, granulating the modified graphene quantum dots and polyester powder described in S1 to obtain a multifunctional polyester masterbatch;

[0013] S3, spinning the multifunctional polyester masterbatch and polyester chips described in S2 to obtain the multifunctional polyester fiber modified with graphene quantum dots.

[0014] In one embodiment of the present invention, in S1, the mass ratio of the graphene quantum dots to dopamine hydrochloride is (3-4):1, the mass ratio of dopamine hydrochloride to benzaldehyde compounds is 3:(1-2); the molar ratio of the catalyst to dopamine hydrochloride is 1:(1-2); the graphene quantum dots are coated with modified polydopamine, so that the surface of the graphene quantum dots is rich in organic aromatic compounds, thereby improving its compatibility with polyester fibers and its dispersibility in polyester fibers.

[0015] In one embodiment of the present invention, in S1, the catalyst is hydrogen peroxide.

[0016] In one embodiment of the present invention, the pH of the alkaline condition is 8.5-9.5; the alkaline condition and the catalyst help promote the polymerization of dopamine, thereby improving the coating effect on the surface of graphene quantum dots.

[0017] In one embodiment of the present invention, the temperature of the first stage reaction is 55°C-65°C, and the time is 3h-4h; the time of the second stage reaction is 3h-4h; the polymerization time is short during the first stage reaction, most of the dopamine hydrochloride completes polymerization, and part of the dopamine hydrochloride is not polymerized or the degree of polymerization is low; after adding the benzaldehyde compound, the second stage reaction is continued to generate modified polydopamine on the surface of the graphene quantum dots. On the one hand, the catechol structure in dopamine hydrochloride is easily oxidized and polymerized under the action of a catalyst to generate polydopamine, which has high adhesion and can produce good grafting on graphene quantum dots; on the other hand, benzaldehyde compounds can directly polymerize with dopamine hydrochloride, and the benzaldehyde compound molecules are interspersed on the surface and inside of polydopamine to generate modified polydopamine; the aldehyde group of the benzaldehyde compound can react with the amino group of dopamine hydrochloride or polydopamine to produce a Schiff base reaction, and the aromatic structure and Schiff base structure of the benzaldehyde compound are introduced into the polydopamine molecular chain to improve the antibacterial properties, thermal stability and compatibility of the modified polydopamine-coated graphene quantum dots with polyester fibers.

[0018] In one embodiment of the present invention, in S1, after the reaction is completed, the steps of centrifugation, washing and drying are further included; the washing is performed by using ethanol and distilled water for 1-3 times respectively.

[0019] In one embodiment of the present invention, before S2, the process further includes a step of drying the modified graphene quantum dots and the polyester powder, wherein the drying temperature of the modified graphene quantum dots is 70°C-80°C, and the time is 7h-9h; the drying temperature of the polyester powder is 120°C-130°C, and the time is 10h-12h.

[0020] In one embodiment of the present invention, in S2, the granulation is performed by melt blending, extrusion molding, cooling and pelletizing through a twin-screw extruder; the granulation temperature is 255°C-270°C; if the processing temperature is too low, the modified graphene quantum dots and polyester powder cannot be mixed evenly, which is not conducive to granulation; if the temperature is too high, it will cause energy waste.

[0021] In one embodiment of the present invention, in S2, the mass fraction of the modified graphene quantum dots in the multifunctional polyester masterbatch is 20%-25%.

[0022] In one embodiment of the present invention, before S3, the multifunctional polyester masterbatch and the polyester chips are further included in the step of drying, wherein the drying is performed by pre-crystallization at 90°C-100°C for 3h-4h, and then drying at 120°C-135°C for 10h-15h to ensure that the final moisture content of the multifunctional polyester masterbatch and the polyester chips is less than 100ppm.

[0023] In one embodiment of the present invention, in S3, the spinning is performed by a melt spinning machine, followed by oiling, pre-stretching, winding, and stretching; the spinning process parameters are: speed of 2600m / min-2800m / min, temperature of 275℃-285℃, and traction ratio of 2-2.5.

[0024] In one embodiment of the present invention, in S3, the mass fraction of the multifunctional polyester masterbatch in the multifunctional polyester fiber modified with graphene quantum dots is 10%-15%.

[0025] The second object of the present invention is to provide a multifunctional polyester fiber modified with graphene quantum dots prepared by the method described above.

[0026] In one embodiment of the present invention, the far-infrared normal emissivity of the multifunctional polyester fiber modified with graphene quantum dots is 0.89-0.92, the far-infrared radiation temperature rise is 2.4°C-3.2°C, the breaking strength is 3.3cN / detx-3.5cN / detx, and the antibacterial property is higher than 99.9%.

[0027] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0028] (1) The preparation method described in the present invention uses dopamine hydrochloride and benzaldehyde compounds to modify graphene quantum dots by in-situ polymerization deposition. Under alkaline conditions and the action of a catalyst, the catechol structure of dopamine hydrochloride is easily oxidized to undergo a polymerization reaction to generate polydopamine, which has high adhesion and can produce good grafting to graphene quantum dots. Benzaldehyde compounds can directly polymerize with dopamine hydrochloride, and the molecules of the benzaldehyde compounds are interspersed on the surface and inside of polydopamine to generate modified polydopamine; the aldehyde group of the benzaldehyde compound can react with the amino group of dopamine hydrochloride or polydopamine to produce a Schiff base reaction, and the aromatic structure and Schiff base structure of the benzaldehyde compound are introduced into the polydopamine molecular chain to improve the antibacterial properties, thermal stability and compatibility of the modified polydopamine-coated graphene quantum dots with polyester fibers.

[0029] (2) The modified graphene quantum dots described in the present invention are evenly dispersed in the polyester fiber, not only having high functionality but also causing little damage to the strength performance of the polyester fiber; polyaniline-modified polydopamine has good conductivity, so the modified graphene quantum dots have excellent far-infrared antibacterial multifunctionality. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. It should be understood that the specific embodiments are only used to explain the present invention, but the embodiments are not intended to limit the present invention.

[0031] In the present invention, unless otherwise explained, technical and scientific terms used in the present invention have the same meanings as commonly understood by those skilled in the art to which the present invention belongs.

[0032] In the present invention, unless otherwise stated, the term "and / or" used in the present invention includes any and all combinations of one or more of the associated listed items.

[0033] In the present invention, unless otherwise stated, the experimental methods used in the embodiments of the present invention are conventional methods unless otherwise stated, and the materials, reagents, etc. used are all commercially available unless otherwise stated.

[0034] In the present invention, unless otherwise specified, the graphene quantum dots used in the embodiments of the present invention are purchased from Wuxi Ensource Technology Co., Ltd. Example 1

[0035] The multifunctional polyester fiber modified with graphene quantum dots and the preparation method thereof of this embodiment specifically include the following steps:

[0036] S1. Add graphene quantum dots to an aqueous solution of dopamine hydrochloride, disperse by ultrasonication for 1.5 hours, adjust the pH to 9 with a sodium hydroxide solution, then add hydrogen peroxide to react at 60° C. for 3.5 hours, finally add an ethanol solution of terephthalaldehyde to continue reacting for 3.5 hours, centrifuge, wash twice with ethanol and distilled water in sequence, and dry to obtain a modified graphene quantum dot powder; wherein the mass ratio of graphene quantum dots to dopamine hydrochloride is 3.5:1, the mass ratio of dopamine hydrochloride to terephthalaldehyde is 3:1.5; and the molar ratio of hydrogen peroxide to dopamine hydrochloride is 1:1.5;

[0037] S2, the modified graphene quantum dot powder was vacuum dried at 75°C for 8h; the polyester powder was vacuum dried at 125°C for 11h, and after mixing, it was melt blended, extruded, cooled and pelletized by a twin-screw extruder. The temperature of the twin-screw extruder was 262°C, and a multifunctional polyester masterbatch with a mass fraction of modified graphene quantum dot powder of 23% was obtained;

[0038] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 95°C blast oven for 3.5 hours, and then continued to be dried at 128°C for 13 hours, so that the final moisture content of the multifunctional polyester masterbatch and the polyester chips was less than 100 ppm. After mixing, they were spun through a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2700 m / min, the temperature was 280°C, and the pulling ratio was 2.3, to obtain multifunctional polyester fibers modified with graphene quantum dots with a mass fraction of 13% of the multifunctional polyester masterbatch. Example 2

[0039] The multifunctional polyester fiber modified with graphene quantum dots and the preparation method thereof of this embodiment specifically include the following steps:

[0040] S1. Add graphene quantum dots to an aqueous solution of dopamine hydrochloride, disperse by ultrasonic for 1 hour, adjust the pH to 8.5 with a sodium hydroxide solution, then add hydrogen peroxide to react at 55° C. for 4 hours, finally add an ethanol solution of terephthalaldehyde to continue reacting for 4 hours, centrifuge, wash with ethanol and distilled water twice in sequence, and dry to obtain a modified graphene quantum dot powder; wherein the mass ratio of graphene quantum dots to dopamine hydrochloride is 3:1, the mass ratio of dopamine hydrochloride to terephthalaldehyde is 3:1; and the molar ratio of hydrogen peroxide to dopamine hydrochloride is 1:1;

[0041] S2, the modified graphene quantum dot powder was vacuum dried at 70°C for 9h; the polyester powder was vacuum dried at 120°C for 12h, and after mixing, it was melt blended, extruded, cooled and pelletized by a twin-screw extruder. The temperature of the twin-screw extruder was 255°C, and a multifunctional polyester masterbatch with a mass fraction of 20% of the modified graphene quantum dot powder was obtained;

[0042] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 90°C blast oven for 4 hours, and then continued to be dried at 120°C for 15 hours, so that the final moisture content of the multifunctional polyester masterbatch and the polyester chips was less than 100 ppm. After mixing, they were spun through a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2600 m / min, the temperature was 285°C, and the pulling ratio was 2, so as to obtain a multifunctional polyester fiber modified with graphene quantum dots with a mass fraction of 10% of the multifunctional polyester masterbatch. Example 3

[0043] The multifunctional polyester fiber modified with graphene quantum dots and the preparation method thereof of this embodiment specifically include the following steps:

[0044] S1. Add graphene quantum dots to an aqueous solution of dopamine hydrochloride, disperse by ultrasonication for 2 hours, adjust the pH to 9.5 with a sodium hydroxide solution, then add hydrogen peroxide to react at 65° C. for 3 hours, finally add an ethanol solution of terephthalaldehyde to continue reacting for 3 hours, centrifuge, wash with ethanol and distilled water twice in sequence, and dry to obtain a modified graphene quantum dot powder; wherein the mass ratio of graphene quantum dots to dopamine hydrochloride is 4:1, the mass ratio of dopamine hydrochloride to terephthalaldehyde is 3:2; and the molar ratio of hydrogen peroxide to dopamine hydrochloride is 1:2;

[0045] S2, the modified graphene quantum dot powder was vacuum dried at 80°C for 7h; the polyester powder was vacuum dried at 130°C for 10h, and after mixing, it was melt blended, extruded, cooled and pelletized by a twin-screw extruder. The temperature of the twin-screw extruder was 270°C, and a multifunctional polyester masterbatch with a mass fraction of modified graphene quantum dot powder of 25% was obtained;

[0046] S3, the multifunctional polyester masterbatch and the polyester chips were pre-crystallized in a 100°C blast oven for 3 hours, and then continued to be dried at 135°C for 10 hours, so that the final moisture content of the multifunctional polyester masterbatch and the polyester chips was less than 100 ppm. After mixing, they were spun through a melt spinning machine, cooled and oiled, pre-stretched, wound and stretched. The speed of the melt spinning machine was 2800 m / min, the temperature was 275°C, and the pulling ratio was 2.5, to obtain a multifunctional polyester fiber modified with graphene quantum dots with a mass fraction of 15% of the multifunctional polyester masterbatch. Comparative Example 1

[0047] The method is basically the same as Example 1, except that dopamine hydrochloride is not used to modify the graphene quantum dots. Comparative Example 2

[0048] The method is basically the same as Example 1, except that terephthalaldehyde is replaced by terephthalic acid when modifying the graphene quantum dots. Comparative Example 3

[0049] The method is basically the same as Example 1, except that terephthalaldehyde is not used to modify the graphene quantum dots. Comparative Example 4

[0050] The method is basically the same as Example 1, except that the graphene quantum dots are replaced with nano bamboo charcoal. Comparative Example 5

[0051] The method is basically the same as Example 1, except that graphene quantum dots and polyester powder are directly used for granulation and spinning. Comparative Example 6

[0052] The process is basically the same as Example 1, except that polyester powder is directly used for granulation and spinning (unmodified polyester fiber).

[0053] Test Case

[0054] The far infrared properties of the multifunctional polyester fibers modified with graphene quantum dots (modified polyester fibers) and the unmodified polyester fibers prepared in Examples 1-3 and Comparative Examples 1-6 were tested:

[0055] Far infrared performance: Refer to GB / T 30127-2013 "Testing and evaluation of far infrared performance of textiles" to test the far infrared emissivity and heating performance of unmodified polyester fiber and modified polyester fiber;

[0056] Physical properties: Refer to GB / T 14344-2022 "Test method for tensile properties of chemical fiber filaments" to test the breaking strength of unmodified polyester fiber and modified polyester fiber;

[0057] Antibacterial performance: Refer to GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles Part 3: Oscillation method" to test the antibacterial rate of unmodified polyester fiber and modified polyester fiber;

[0058] Table 1 shows the relevant properties of the unmodified polyester fiber and the modified polyester fiber finally measured:

[0059] Table 1

[0060]

[0061] It can be seen from Table 1 that the modified polyester fiber has excellent far-infrared performance and antibacterial properties, and the strength performance of the modified polyester fiber is not significantly affected.

[0062] By comparing Example 1 and Comparative Example 1, it can be seen that when dopamine hydrochloride is not used to modify the graphene quantum dots, the far-infrared emissivity and heating performance of the modified polyester fiber are reduced, the antibacterial performance is reduced, and the mechanical properties are reduced. This is because there are very few active groups on the surface of the graphene quantum dots, and it is difficult to produce a strong bond with the graphene quantum dots when modified with terephthalaldehyde, resulting in poor modification effect and poor dispersion performance of the modified graphene quantum dots in the polyester fiber.

[0063] By comparing Example 1 and Comparative Example 2, it can be seen that when terephthalaldehyde is replaced with terephthalic acid when modifying the graphene quantum dots, the far-infrared performance and antibacterial properties of the modified polyester fiber are reduced, and the mechanical properties are reduced. This is because the carboxyl group of terephthalic acid is difficult to react with the amino group of dopamine or polydopamine under the reaction conditions, resulting in poor modification effect and reduced dispersion performance of the modified graphene quantum dots in the polyester fiber.

[0064] By comparing Example 1 and Comparative Example 3, it can be seen that when terephthalaldehyde is not used to modify the graphene quantum dots, the far-infrared performance and antibacterial properties of the modified polyester fiber are reduced, and the mechanical properties are reduced. This is because during the spinning heating process, the polydopamine-modified graphene quantum dots are bonded and aggregated to each other, making it difficult to disperse evenly in the polyester fiber, and the surface polydopamine is easily decomposed under high temperature conditions, resulting in severe damage to the mechanical properties of the polyester fiber.

[0065] By comparing Example 1 and Comparative Example 4, it can be seen that when the modified nano-bamboo charcoal is used to modify the polyester fiber, the far-infrared performance, antibacterial performance and mechanical properties of the modified polyester fiber deteriorate. This is because the far-infrared efficiency and antibacterial performance of the nano-bamboo charcoal are lower than those of graphene quantum dots, and its dispersion performance is weaker than that of graphene quantum dots, resulting in greater damage to the mechanical properties.

[0066] By comparing Example 1 and Comparative Example 5, it can be seen that when graphene quantum dots are directly mixed with polyester for spinning, the far-infrared emissivity, heating performance and antibacterial rate of the modified polyester fiber are significantly reduced. This is because the graphene quantum dots have high surface energy, are easy to agglomerate in polyester fibers, and have poor compatibility, resulting in poor dispersion performance in polyester fibers.

[0067] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and scope of the equivalent elements of the claims be included in the invention. Any marking in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing a multifunctional polyester fiber modified with graphene quantum dots, characterized in that: The following steps are involved: S1. Under alkaline conditions and the action of a catalyst, graphene quantum dots and dopamine hydrochloride are reacted in water in the first stage, and then a benzaldehyde compound alcohol solution is added to carry out a second stage reaction to obtain modified graphene quantum dots; the benzaldehyde compound is selected from one or more of terephthalaldehyde, isophthalaldehyde and 2,5-dihydroxyterephthalaldehyde; the catalyst is hydrogen peroxide; the temperature of the first stage reaction is 55°C-65°C, and the time is 3h-4h; the time of the second stage reaction is 3h-4h; S2, granulating the modified graphene quantum dots and polyester powder described in S1 to obtain a multifunctional polyester masterbatch; S3, spinning the multifunctional polyester masterbatch and polyester chips described in S2 to obtain the multifunctional polyester fiber modified with graphene quantum dots.

2. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: In S1, the mass ratio of the graphene quantum dots to dopamine hydrochloride is (3-4):1, the mass ratio of dopamine hydrochloride to benzaldehyde compounds is 3:(1-2); and the molar ratio of the catalyst to dopamine hydrochloride is 1:(1-2).

3. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: The pH of the alkaline condition is 8.5-9.

5.

4. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: In S2, the granulation is performed by melt blending, extrusion molding, cooling and pelletizing through a twin-screw extruder; the granulation temperature is 255°C-270°C.

5. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: In S2, the mass fraction of the modified graphene quantum dots in the multifunctional polyester masterbatch is 20%-25%.

6. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: In S3, the spinning is carried out by a melt spinning machine, followed by oiling, pre-stretching, winding, and stretching. The spinning process parameters are: a speed of 2600 m / min-2800 m / min, a temperature of 275°C-285°C, and a drawing ratio of 2-2.

5.

7. The method for preparing the multifunctional polyester fiber modified by graphene quantum dots according to claim 1, characterized in that: In S3, the mass fraction of the multifunctional polyester masterbatch in the multifunctional polyester fiber modified with graphene quantum dots is 10%-15%.

8. A multifunctional polyester fiber modified with graphene quantum dots prepared by the method according to any one of claims 1 to 7.

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