Polyester fiber surface modification method adaptive to environment-friendly system

Abstract

The invention discloses a polyester fiber surface modification method adaptive to an environment-friendly system, and belongs to the field of fiber modification. The polyester fiber surface modification method comprises the following steps: immersing a polyester fiber into a carbon dot precursor solution, and carrying out microwave irradiation treatment to obtain a carbon dot modified fiber; and immersing the carbon dot modified fiber in an impregnation liquid to obtain the modified polyester fiber. The invention provides a green surface treatment strategy based on microwave-assisted carbon dot modification in order to overcome the defect of interface bonding performance of polyester fibers and a rubber matrix and solve the problem of environmental pollution existing in a traditional resorcinol-formaldehyde-latex (RFL) impregnation system. According to the method, rich functional groups on the surfaces of the carbon dots are utilized, in-situ modification of the carbon dots is achieved on the surface of the polyester fiber through a microwave process, and the surface roughness and chemical polarity of the polyester fiber are effectively improved on the premise that the mechanical property of a body of the polyester fiber is not affected.

Description

Technical Field

[0001] This invention relates to the field of fiber modification, and in particular to a method for surface modification of polyester fibers adapted to environmentally friendly systems. Background Technology

[0002] Polyester fibers, due to their advantages such as high modulus, low cost, and low heat shrinkage, have shown broad application prospects in industrial fields such as V-belts, tires, and conveyor belts. However, polyester fibers have a smooth surface and lack active groups, exhibiting surface polarity characteristics. This polarity difference with most non-polar rubber matrices leads to weak interfacial interactions between the two materials, making it difficult to form an effective interfacial bonding layer. This insufficient interfacial compatibility significantly reduces the stress transfer efficiency in the composite system, resulting in poor interfacial adhesion of fiber / rubber composites and limiting the further application of polyester fibers in rubber composites.

[0003] To improve the interfacial adhesion between polyester fibers and rubber, common modification methods include physical and chemical methods. Physical methods include plasma treatment, high-energy irradiation, ultrasonic treatment, and electron beam treatment; chemical methods include acid-base etching and coating treatment. While physical methods can achieve surface activation, they require sophisticated equipment, are costly, and are difficult to scale up for continuous production. Chemical methods, on the other hand, can increase the active groups on polyester fibers by introducing active functional groups such as -OH, -COOH, and -NH2 onto the fiber surface. This not only improves the surface activity of the fibers but also allows these active groups to act as reaction sites, forming chemical bonds between the fiber and the matrix, thus enhancing their interaction. For example, (CN118498079A) proposes using the phenolic hydroxyl groups of polyphenols to complex with heavy metal ions in the form of oxygen anions to deposit a coating on the surface of polyester fibers, thereby improving the interfacial adhesion of fiber / rubber composites. However, this process uses ultraviolet light, posing health risks. (CN115613348B) describes a method for treating polyester fiber fabrics with a co-treatment of the surface with alkali and a coupling agent. The alkali treatment increases the number of hydroxyl groups on the polyester fiber surface, and then the coupling agent is grafted to introduce active functional groups, improving the adhesion to rubber. However, the improvement in adhesion is still relatively limited. Researchers such as Shao et al. enhanced the bonding force between polyester fibers and silicone rubber by in-situ grafting hydrolyzed polyester fibers with the silane coupling agent KH570 (Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2021:127384). However, this method is mainly applicable to silicone rubber systems and lacks versatility. Therefore, developing an efficient, easy-to-operate, and environmentally friendly fiber surface modification method is of significant practical importance. Summary of the Invention

[0004] The purpose of this invention is to provide a surface modification method for polyester fibers that is compatible with environmentally friendly systems, thereby solving the aforementioned problems in the background art. This invention addresses the shortcomings of the interfacial adhesion between polyester fibers and rubber matrices, as well as the environmental pollution problems associated with traditional resorcinol-formaldehyde-latex (RFL) impregnation systems, by proposing a green surface treatment strategy based on microwave-assisted carbon dot modification.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a method for surface modification of polyester fibers, comprising the following steps: Organic precursors and phosphates are dissolved in a solvent to obtain carbon dot precursor solutions; Polyester fibers are immersed in the carbon dot precursor solution and subjected to microwave irradiation treatment to obtain carbon dot modified fibers. Epoxy resin, amine curing agent and rubber latex are mixed to obtain impregnation solution; The carbon dot modified fiber is immersed in the impregnation solution, impregnated, and dried to obtain modified polyester fiber.

[0006] Preferably, the organic precursor includes a carbon source and a nitrogen source in a molar ratio of 1:0.1-5, more preferably in a molar ratio of 1:0.5-3; The carbon source includes one or more of polycarboxylic acids, sugars and their derivatives, and biomass extracts; the nitrogen source includes one or more of fatty amines, amide compounds, nitrogen-containing heterocyclic compounds, and amino acids.

[0007] More preferably, the carbon source includes one or more of citric acid, malic acid, tartaric acid, butanetetracarboxylic acid, glucose, fructose, sucrose, trehalose, starch, cellulose, and lignin, more preferably citric acid; the nitrogen source includes one or more of ethylenediamine, diethylenetriamine, triethylenetetraamine, ammonia, polyethyleneimine, urea, thiourea, histidine, arginine, tyrosine, lysine, tryptophan, piperazine, and melamine, more preferably ethylenediamine.

[0008] Preferably, the concentration of the organic precursor in the carbon dot precursor solution is 30-300 mg / mL, more preferably 70-200 mg / mL; the concentration of phosphate in the carbon dot precursor solution is 1-300 mmol / L, more preferably 5-50 mmol / L, and even more preferably 8-12 mmol / L; the concentrations of epoxy resin, amine curing agent, and rubber latex in the impregnation solution are 10-80 g / L, 5-30 g / L, and 100-350 g / L, respectively, and even more preferably 20-60 g / L, 6-20 g / L, and 120-300 g / L, respectively. The epoxy resin is polyethylene glycol diglycidyl ether and / or glycerol triglycidyl ether; the amine curing agent is triethylenetetramine and / or tetraethylenepentamine; the rubber latex is styrene-butadiene-pyridine latex. The phosphates include one or more of potassium dihydrogen phosphate, sodium dihydrogen phosphate, trisodium phosphate, tripotassium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium hypophosphite, and calcium dihydrogen phosphate.

[0009] Preferably, the time for immersing the polyester fiber in the carbon dot precursor solution is 1-200 min, more preferably 8-30 min; the microwave power for the microwave irradiation treatment is 100-1000W, more preferably 500-700W, and the treatment time is 1-20 min, more preferably 1-10 min, and even more preferably 3 min.

[0010] Preferably, during the microwave irradiation treatment, the polyester fibers are fixed inside the microwave reactor for treatment to ensure uniform irradiation.

[0011] Preferably, the immersion treatment time is 5-200s, more preferably 10-150s.

[0012] Preferably, the drying process includes the following steps: drying at 80-150°C for 1-10 min, and then heat curing at 130-240°C for 1-10 min.

[0013] The drying process of this invention mainly consists of two stages. The first stage is a low-temperature drying stage; its main purpose is to gently remove most of the water and solvent in the impregnation solution at a relatively low temperature (80-150℃), allowing the active ingredients to initially and stably adhere to the fiber surface. The second stage is a high-temperature thermosetting stage: at a higher temperature (130-250℃), the resin undergoes a full cross-linking reaction (curing), forming a stable three-dimensional network structure, while simultaneously establishing strong chemical bonds with the polyester fiber surface.

[0014] The second technical solution of the present invention provides a modified polyester fiber prepared according to the above-mentioned polyester fiber surface modification method.

[0015] The third technical solution of the present invention provides an application of the above-mentioned modified polyester fiber in the field of fiber / rubber composite materials.

[0016] The fourth technical solution of the present invention provides a method for enhancing the interfacial adhesion performance of fiber / rubber composite materials, which is achieved by using the above-mentioned modified polyester fiber as the fiber component.

[0017] Preferably, the rubber matrix of the fiber / rubber composite material is natural rubber or synthetic rubber.

[0018] More preferably, the synthetic rubber is styrene-butadiene rubber.

[0019] The chemical modification method employed in this invention differs from traditional etching methods. Its core lies in using a carbon dot precursor solution to modify the surface of polyester fibers. This method does not require damaging the fiber surface structure; instead, it enhances the surface chemical polarity and reactivity by constructing a nano-coating rich in active functional groups on the fiber surface in situ.

[0020] The beneficial technical effects of the present invention are as follows: This invention addresses the shortcomings of interfacial adhesion between polyester fibers and rubber matrices, as well as the environmental pollution problems associated with traditional resorcinol-formaldehyde-latex (RFL) impregnation systems. It proposes a green surface treatment strategy based on microwave-assisted carbon dot modification. This method utilizes the abundant functional groups on the carbon dot surface to achieve in-situ modification of carbon dots on the polyester fiber surface via microwave technology. While maintaining the fiber's bulk mechanical properties, this effectively improves its surface roughness and chemical polarity. After modification, the increased roughness strengthens the mechanical interlocking effect with the rubber, and the introduced carboxyl and amine groups further enhance interfacial chemical interactions, thus significantly improving the adhesion between the fiber and rubber.

[0021] The present invention has a simple operation process, low cost, mild reaction conditions, and is green and environmentally friendly, reducing environmental pollution and has great application potential in actual production.

[0022] This method modifies the surface chemical properties of polyester fibers and forms carbon dots on their surface by microwave treatment of a carbon dot precursor solution. Finally, a formaldehyde-free, environmentally friendly impregnation solution is used for secondary treatment, achieving modification of the polyester fibers and improving the interfacial adhesion between the fibers and the rubber matrix. The modified polyester fibers prepared by this invention are suitable for industrial applications in composite rubber products such as tire cords, conveyor belts, and V-belts, and have broad application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 Water contact angle diagrams for unmodified polyester fiber and modified polyester fiber prepared in Example 3. Wherein, (a) represents unmodified polyester fiber, and (b) represents modified polyester fiber.

[0025] Figure 2Scanning electron microscope images of unmodified polyester fiber and modified polyester fiber prepared in Example 3. Wherein, (a) is unmodified polyester fiber and (b) is modified polyester fiber. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0027] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. It should be noted that any aspects of this invention not described in detail are conventional practices in the art and are not the focus of this invention.

[0029] The terms “comprising,” “including,” “having,” “containing,” etc., used in this invention are all open-ended terms, meaning that they include but are not limited to.

[0030] In the preparation of fiber / rubber composites, resorcinol-formaldehyde-latex (RFL) impregnation systems, as a traditional interfacial modification method, can provide good interfacial adhesion properties for rubber skeleton materials. However, in recent years, with the increasing awareness of environmental protection and safety, industries have gradually shifted towards environmentally friendly impregnation solutions, creating an urgent need to develop other impregnation systems that can replace RFL impregnation solutions.

[0031] Carbon dots, as a novel nanomaterial, have attracted widespread attention in the field of material modification due to their excellent water solubility, biocompatibility, controllable optical properties, and abundant surface functional groups. The surface of carbon dots is rich in polar groups such as hydroxyl and carboxyl groups, making them a promising new approach to improve the interfacial adhesion of high-performance fiber-rubber composites. On the one hand, carbon dots can bind to polyester fibers through covalent or non-covalent interactions, thereby introducing active sites on the fiber surface and enhancing the interaction between the fiber and the rubber matrix. On the other hand, the nanoscale effect of carbon dots helps fill the gaps between fibers, increasing fiber roughness and further strengthening the interfacial bonding force between fibers and rubber, thus improving the overall performance of fiber / rubber composites. Based on this, the present invention was designed.

[0032] The rubber used in the following embodiments and comparative examples of the present invention is a compound rubber; by weight, the compound rubber used is composed of the following raw materials in parts by weight: 70 parts styrene-butadiene rubber, 30 parts natural rubber, 15 parts aromatic oil, 1.5 parts anti-aging agent 4010NA (N-isopropyl-N-phenyl-p-phenylenediamine), 30 parts carbon black N330, 15 parts silica, 5 parts zinc oxide (ZnO), 4 parts accelerator CZ (N-cyclohexyl-2-benzothiazole sulfenamide), 2 parts stearic acid SA, 10 parts coumarone resin, 1.5 parts adhesive RS, 1.5 parts adhesive RA, and 1 part sulfur.

[0033] The polyester fibers used were cleaned to remove surface oils before use and dried at 80°C to ensure complete drying.

[0034] All raw materials used in the following embodiments and comparative examples of the present invention are commercially available products.

[0035] Example 1 A method for surface modification of polyester fibers, comprising the following steps: Preparation of carbon dot precursor solution: First, prepare a 10 mmol / L potassium dihydrogen phosphate solution, then add a certain amount of citric acid to make its concentration 100 mg / mL. Take 10 mL of the mixture and add 0.156 g of ethylenediamine to make the molar ratio of citric acid to ethylenediamine 1:0.5. Stir well to obtain the carbon dot precursor solution. Immerse polyester fibers in the carbon dot precursor solution for 10 min, remove them and blow off the excess solution from the fiber surface to obtain the impregnated polyester fibers.

[0036] Preparation of carbon dot modified polyester fiber: The impregnated polyester fiber was treated with microwave at 700W for 3 minutes to obtain carbon dot modified fiber.

[0037] Preparation of the impregnation solution: 5g of polyethylene glycol diglycidyl ether and 1.1g of triethylenetetramine were dissolved in 94g of deionized water. The solution was stirred vigorously at 600rpm for 1h at 60℃ using an electric stirrer. Subsequently, the solution was added to 100g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25℃ with vigorous stirring for 1.5h to obtain the impregnation solution.

[0038] Impregnation treatment: The cleaned carbon dot modified fiber is immersed in the above impregnation solution for impregnation treatment for 110 seconds. After removal, it is dried at 120℃ for 120 seconds and then heat-cured at 200℃ for 120 seconds to obtain environmentally friendly impregnation solution treated modified polyester fiber.

[0039] Example 2 A method for surface modification of polyester fibers, comprising the following steps: Preparation of carbon dot precursor solution: First, prepare a 10 mmol / L potassium dihydrogen phosphate solution, then add a certain amount of citric acid to make its concentration 100 mg / mL. Take 10 mL of the mixture and add 0.312 g of ethylenediamine to make the molar ratio of citric acid to ethylenediamine 1:1. Stir well to obtain the carbon dot precursor solution. Immerse polyester fibers in the carbon dot precursor solution for 10 min, remove them and blow off the excess solution from the fiber surface to obtain the impregnated polyester fibers.

[0040] Preparation of carbon dot modified polyester fiber: The impregnated polyester fiber was treated with microwave at 700W for 3 minutes to obtain carbon dot modified fiber.

[0041] Preparation of the impregnation solution: 5g of polyethylene glycol diglycidyl ether and 1g of triethylenetetramine were dissolved in 94g of deionized water. The solution was stirred vigorously at 600rpm for 1 hour at 60°C using an electric stirrer. Subsequently, the solution was added to 100g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25°C with vigorous stirring for 2.5 hours to obtain the impregnation solution.

[0042] Impregnation treatment: The cleaned carbon dot modified fiber is immersed in the above impregnation solution for impregnation treatment for 110 seconds. After removal, it is dried at 120℃ for 120 seconds and then heat-cured at 200℃ for 120 seconds to obtain environmentally friendly impregnation solution treated modified polyester fiber.

[0043] Example 3 A method for surface modification of polyester fibers, comprising the following steps: Preparation of carbon dot precursor solution: First, prepare a 10 mmol / L potassium dihydrogen phosphate solution, then add a certain amount of citric acid to make its concentration 100 mg / mL. Take 10 mL of the mixture and add 0.468 g of ethylenediamine to make the molar ratio of citric acid to ethylenediamine 1:1.5. Stir well to obtain carbon dot precursor solution. Immerse polyester fibers in carbon dot precursor solution for 10 min, remove and blow off excess solution from the fiber surface to obtain impregnated polyester fibers.

[0044] Preparation of carbon dot modified polyester fiber: The impregnated polyester fiber was treated with microwave at 700W for 3 minutes to obtain carbon dot modified fiber.

[0045] Preparation of the impregnation solution: 5g of polyethylene glycol diglycidyl ether and 1g of triethylenetetramine were dissolved in 94g of deionized water. The solution was stirred vigorously at 600rpm for 1 hour at 65°C using an electric stirrer. Subsequently, the solution was added to 100g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25°C with vigorous stirring for 2.5 hours to obtain the impregnation solution.

[0046] Impregnation treatment: The cleaned carbon dot modified fiber is immersed in the above impregnation solution for 130 seconds. After immersion, it is dried at 120°C for 120 seconds and then heat-cured at 200°C for 120 seconds to obtain the modified polyester fiber treated with environmentally friendly impregnation solution.

[0047] Example 4 A method for surface modification of polyester fibers, comprising the following steps: Preparation of carbon dot precursor solution: First, prepare a 10 mmol / L potassium dihydrogen phosphate solution, then add a certain amount of citric acid to make its concentration 100 mg / mL. Take 10 mL of the mixture and add 0.624 g of ethylenediamine to make the molar ratio of citric acid to ethylenediamine 1:2. Stir well to obtain the carbon dot precursor solution. Immerse polyester fibers in the carbon dot precursor solution for 10 min, remove them, and blow off the excess solution from the fiber surface to obtain the impregnated polyester fibers.

[0048] Preparation of carbon dot modified polyester fiber: The impregnated polyester fiber was treated with microwave at 700W for 3 minutes to obtain carbon dot modified fiber.

[0049] Preparation of the impregnation solution: 5g of polyethylene glycol diglycidyl ether and 1g of triethylenetetramine were dissolved in 94g of deionized water. The solution was stirred vigorously at 600rpm for 1 hour at 60°C using an electric stirrer. Subsequently, the solution was added to 100g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25°C with vigorous stirring for 2.5 hours to obtain the impregnation solution.

[0050] Impregnation treatment: Immerse the cleaned carbon dot modified fiber in the above impregnation solution for 120 seconds, remove it and dry it at 120°C for 120 seconds, and then heat cure it at 200°C for 120 seconds to obtain the modified polyester fiber after environmentally friendly impregnation solution treatment.

[0051] Example 5 A method for surface modification of polyester fibers, comprising the following steps: Preparation of carbon dot precursor solution: First, prepare a 10 mmol / L potassium dihydrogen phosphate solution, then add a certain amount of citric acid to make its concentration 100 mg / mL. Take 10 mL of the mixture and add 0.78 g of ethylenediamine to make the molar ratio of citric acid to ethylenediamine 1:2.5. Stir well to obtain the carbon dot precursor solution. Immerse polyester fibers in the carbon dot precursor solution for 10 min, remove them and blow off the excess solution from the fiber surface to obtain the impregnated polyester fibers.

[0052] Preparation of carbon dot modified polyester fiber: The impregnated polyester fiber was treated with microwave at 700W for 3 minutes to obtain carbon dot modified fiber.

[0053] Preparation of the impregnation solution: 5.1 g of polyethylene glycol diglycidyl ether and 0.9 g of triethylenetetramine were dissolved in 94 g of deionized water. The solution was stirred vigorously at 600 rpm for 1 h at 60 °C using an electric stirrer. Subsequently, the solution was added to 100 g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25 °C with vigorous stirring for 2.5 h to obtain the impregnation solution.

[0054] Impregnation treatment: Immerse the cleaned carbon dot modified fiber in the above impregnation solution for 120 seconds, remove it and dry it at 120°C for 120 seconds, and then heat cure it at 200°C for 120 seconds to obtain the modified polyester fiber after environmentally friendly impregnation solution treatment.

[0055] Comparative Example 1 The polyester fibers are impregnated using a traditional RFL impregnation system, and the specific steps are as follows: Preparation of impregnation solution: Weigh 11g resorcinol, 16.2g formaldehyde (37wt%), and 3g sodium hydroxide solution (10wt%), add them to 235.8g deionized water, and stir at 25℃ for 6h to obtain RF resin solution. Then add 250g butadiene-pyridine latex (40wt%) and 59.2g deionized water to the RF resin solution, and mature at 25℃ for 20h. Then adjust the pH to 8-9 by adding ammonia solution (28wt%) to obtain RFL impregnation solution.

[0056] Impregnation treatment: The polyester fibers are cleaned to remove surface oils and then dried completely at 60°C. The cleaned polyester fibers are then impregnated in RFL impregnation solution for 120 seconds. After removal, they are dried at 140°C for 120 seconds and then heat-cured at 240°C for 120 seconds to obtain the impregnated modified polyester fibers.

[0057] The formulation of the RFL impregnation solution used in Comparative Example 1 is shown in Table 1.

[0058] Table 1 RFL impregnation solution formulation Comparative Example 2 The polyester fibers are impregnated using an environmentally friendly impregnation solution system. The specific steps are as follows: Preparation of the impregnation solution: 5g of polyethylene glycol diglycidyl ether and 0.7g of triethylenetetramine were dissolved in 94.3g of deionized water. The solution was stirred vigorously at 600rpm for 1 hour at 60℃ using an electric stirrer. Subsequently, this solution was added to 100g of styrene-butadiene vinylpyridine latex, and the apparatus was kept at 25℃ with vigorous stirring for 2.5 hours to obtain the impregnation solution.

[0059] Impregnation treatment: Immerse the cleaned polyester fiber in the above impregnation solution for 120 seconds, remove it and dry it at 140°C for 120 seconds, and then heat cure it at 200°C for 120 seconds to obtain the modified polyester fiber after environmentally friendly impregnation solution treatment.

[0060] Effect verification H-pulsation force test: To verify the H-pull-out force performance of the modified polyester fibers obtained in the various embodiments and comparative examples of this invention, the following tests were conducted: The compounded rubber was cut into strips of 200mm × 10mm × 5mm. The cut strips were embedded into the grooves of the upper and lower molds. Then, the upper ends of the adhesive-modified polyester fiber samples from the various embodiments and comparative examples were knotted and fixed onto the mold. A 50g weight was applied to the lower end to provide tension. The mold plate was then closed, and the sample was transferred to a flat vulcanizing machine. The vulcanization temperature was 150℃, the vulcanization pressure was 15MPa, and the vulcanization time was 50min. Test samples were obtained, and the H-pull-out force was tested according to GB / T 2942-2009. The test results are shown in Table 2.

[0061] Peel strength test: To verify the peel strength of the modified polyester fibers obtained in the various embodiments and comparative examples of this invention, the following tests were conducted: A 235mm × 160mm × 1.7mm experimental film and a 25mm × 160mm × 0.5mm fixing film were cut from the compounded rubber. A 235mm × 160mm × 0.75mm pad and a 60mm × 200mm release paper were also prepared. One end of the modified polyester fiber from each embodiment and comparative example was knotted and fixed in a groove at one end of the mold. Tension was applied to tighten the polyester fiber, and the polyester fiber was repeatedly arranged between the grooves at both ends of the mold, with 7 fibers arranged for each sample. A 50g weight was suspended from the end of the last arranged polyester fiber. The fixing film was placed at one end of the mold, and the release paper was covered on the outer surface of the film. Then, the experimental film was covered, and finally, the pad was placed over the outer surface of the experimental film, and the mold plate was closed. The mold was placed in a flat vulcanizing machine at a vulcanizing temperature of 150℃, a vulcanizing pressure of 15MPa, and a vulcanizing time of 50min. Peel strength tests were conducted according to the national standard GB / T 40725-2021. The test results are shown in Table 2.

[0062] Fiber mechanical strength test: To verify the mechanical properties of the polyester fibers obtained in the various embodiments and comparative examples of this invention, the following tests were conducted: The fiber mechanical properties were tested according to the national standard GB / T19390-2023, with a cord length of 250 mm and a tensile testing machine speed of 300.0 mm / min. The test results are shown in Table 2.

[0063] Table 2 Performance Comparison As can be seen from the data in Table 2, the modification method of the present invention effectively improves the interfacial adhesion performance between polyester fiber and rubber matrix, and increases the H-pull-out force and peel strength of polyester fiber / rubber composite material, showing good modification effect.

[0064] Figure 1 Water contact angle diagrams for unmodified polyester fiber and modified polyester fiber prepared in Example 3. Wherein, (a) represents unmodified polyester fiber, and (b) represents modified polyester fiber.

[0065] Depend on Figure 1 It can be seen that the contact angle of the modified polyester fiber is smaller compared with that of the unmodified polyester fiber, which further illustrates the change in the interfacial state of the modified fiber.

[0066] Figure 2 Scanning electron microscope images of unmodified polyester fiber and modified polyester fiber prepared in Example 3. Wherein, (a) is unmodified polyester fiber and (b) is modified polyester fiber.

[0067] Depend on Figure 2 It can be seen that, compared with unmodified polyester fiber, the roughness of the modified polyester fiber of the present invention is significantly increased, and particulate matter appears.

[0068] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for surface modification of polyester fibers, characterized by, The method comprises the following steps: dissolving organic precursors and phosphate in a solvent to obtain a carbon dot precursor solution; immersing polyester fibers in the carbon dot precursor solution and performing microwave irradiation treatment to obtain carbon dot modified fibers; mixing epoxy resin, amine curing agent and rubber latex to obtain an impregnation solution; immersing the carbon dot modified fibers in the impregnation solution, performing impregnation treatment and drying to obtain modified polyester fibers.

2. The method for surface modification of polyester fibers according to claim 1, characterized by, The organic precursors comprise carbon sources and nitrogen sources in a molar ratio of 1:0.1-5; The carbon sources comprise one or more of polycarboxylic acids, saccharides and derivatives thereof, and biomass extracts; and the nitrogen sources comprise one or more of aliphatic amines, amide compounds, nitrogen-containing heterocyclic compounds and amino acids.

3. The method for surface modification of polyester fibers according to claim 2, characterized by, The carbon sources comprise one or more of citric acid, malic acid, tartaric acid, butane tetracarboxylic acid, glucose, fructose, sucrose, trehalose, starch, cellulose and lignin; and the nitrogen sources comprise one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, ammonia, polyethyleneimine, urea, thiourea, histidine, arginine, tyrosine, lysine, tryptophan, piperazine and melamine.

4. The polyester fiber surface modification method according to claim 1, characterized by, The concentrations of the organic precursors and phosphate in the carbon dot precursor solution are 30-300 mg / mL and 1-300 mmol / L, respectively; and the concentrations of the epoxy resin, amine curing agent and rubber latex in the impregnation solution are 10-80 g / L, 5-30 g / L and 100-350 g / L, respectively. The epoxy resin is polyethylene glycol diglycidyl ether and / or glycerol triglycidyl ether; the amine curing agent is triethylenetetramine and / or tetraethylenepentamine; and the rubber latex is butadiene styrene py latex. The phosphate comprises one or more of potassium dihydrogen phosphate, sodium dihydrogen phosphate, trisodium phosphate, tripotassium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, sodium hypophosphite and calcium dihydrogen phosphate.

5. The polyester fiber surface modification method according to claim 1, characterized by, The polyester fibers are immersed in the carbon dot precursor solution for 1-200 min; and the microwave irradiation treatment is performed at a microwave power of 100-1000 W for 1-20 min.

6. The polyester fiber surface modification method according to claim 1, characterized by, The impregnation treatment is performed for 5-200 s.

7. The polyester fiber surface modification method according to claim 1, characterized by, The drying comprises the following steps: drying at 80-150 ℃ for 1-10 min, and then heat curing at 130-240 ℃ for 1-10 min.

8. Modified polyester fibers prepared by the method for modifying the surface of polyester fibers according to any one of claims 1-7.

9. Use of the modified polyester fibers according to claim 8 in the field of fiber / rubber composites.

10. A method for enhancing the interfacial adhesion of a fiber / rubber composite, characterized by, The modified polyester fibers according to claim 8 are used as the fiber component.

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