Terylene industrial yarn for geogrid and preparation method thereof

Abstract

The invention relates to the technical field of high-performance polyester, and discloses a polyester industrial yarn for geogrids and a preparation method thereof.The preparation method of the polyester industrial yarn for the geogrids comprises the following steps that cyanuric chloride and m-phenylenediamine react to obtain an intermediate product; reacting the intermediate product with 4-hydroxyphthalic anhydride to obtain an imide compound; the preparation method comprises the following steps: polymerizing terephthalic acid, ethylene glycol, 1, 6-hexanediol and a modifier, discharging, and pelletizing to obtain a high-performance PET copolyester master batch; mixing the high-performance PET copolyester master batch, polyester chips and the composite modified graphene oxide, and carrying out melt spinning to obtain the terylene industrial yarn for the geogrid; the polyester industrial yarn for the geogrid not only has the characteristics of high strength and high temperature resistance, but also has good corrosion resistance, and when the polyester industrial yarn is used in the warp-knitted polyester geogrid, the working performance of the warp-knitted polyester geogrid can be improved, and the service life of the warp-knitted polyester geogrid can be prolonged.

Description

Technical Field

[0001] This invention relates to the field of high-performance polyester technology, and in particular to a polyester industrial yarn for geogrids and its preparation method. Background Technology

[0002] With the continuous development of society and economy, the country is paying more and more attention to infrastructure construction. However, the scarcity of land resources and insufficient engineering conditions have brought difficulties to construction. Applying geosynthetics to engineering projects can greatly improve these problems. Geogrids have the characteristics of high tensile strength, low elongation, good tear resistance, and good durability. They are often used in soft soil foundation reinforcement and embankment reinforcement. They can improve the stability of the foundation, increase the bearing capacity, and reduce uneven settlement. They can also be used in roadbed slope reinforcement projects to improve slope stability. When used to reinforce bridge abutments, they improve the strength and integrity of the abutments, thereby preventing bridge approach slab settlement. Therefore, the application scale of geogrids in engineering is constantly expanding.

[0003] Warp-knitted polyester geogrid is a relatively new type of geosynthetic material. It is made from polyester industrial filaments, which are first woven into a mesh fabric using warp and weft directional weaving technology, and then coated with a coating material to create a planar mesh structure. To meet the production requirements of warp-knitted polyester geogrid and its application requirements in various complex environments, the polyester industrial filaments used in warp-knitted polyester geogrid must have high strength and corrosion resistance. In addition, the performance of polyester filaments deteriorates and material aging accelerates under high-temperature environments, which limits its application range and shortens the service life of warp-knitted polyester geogrid. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing polyester industrial yarn for geogrids, comprising the following steps: Step 1: Cyanuronyl chloride reacts with m-phenylenediamine to obtain an intermediate product; the intermediate product then reacts with 4-hydroxyphthalic anhydride to obtain an imide compound. Step 2: Polymerize terephthalic acid, ethylene glycol, 1,6-hexanediol, and modifier, discharge the material, and granulate it to obtain high-performance PET copolyester masterbatch; wherein, the modifier is obtained by reacting a fluorinated compound with an imide compound, and the fluorinated compound is obtained by reacting 2,2,3,3,4,4-hexafluoro-1,5-pentanediol with hexamethylene diisocyanate; Step 3: Mix high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide, and melt spin to obtain polyester industrial yarn for geogrids.

[0005] Preferably, in step one, the method for preparing the imide compound is as follows: In a nitrogen atmosphere, cyanuric chloride was added to tetrahydrofuran and cooled to 0°C. Under stirring, a 7.6 wt% m-phenylenediamine / tetrahydrofuran solution was added dropwise, followed by sodium bicarbonate. The mixture was heated to 50-60°C and stirred for 4-6 hours. After purification, an intermediate product was obtained. The mass ratio of cyanuric chloride, tetrahydrofuran, 7.6 wt% m-phenylenediamine / tetrahydrofuran solution, and sodium bicarbonate was (6-12):(120-150):(46.3-92.6):(8.2-16.4). In a nitrogen atmosphere, the intermediate product was added to N,N-dimethylformamide and stirred. Then, 4-hydroxyphthalic anhydride was added, and the mixture was reacted at 120-130°C for 2-4 hours. After purification, an imide compound was obtained. The mass ratio of the intermediate product, N,N-dimethylformamide, and 4-hydroxyphthalic anhydride was (4-6.4):(100-150):(4.9-7.9). In the above process, the three chlorine atoms in cyanuric chloride react with the amino group at one end of m-phenylenediamine to obtain an intermediate product. The intermediate product contains multiple benzene ring structures and triazine rings, which have excellent mechanical properties and thermal stability. Next, the amino group of the intermediate product reacts with 4-hydroxyphthalic anhydride to generate an imide compound containing an imide ring structure. The imide ring structure has excellent mechanical properties, corrosion resistance, hydrophobic properties, and thermal stability.

[0006] Preferably, in step two, the preparation method of the high-performance PET copolyester masterbatch is as follows: In a nitrogen atmosphere, terephthalic acid, ethylene glycol, 1,6-hexanediol, tetrabutyl titanate, and modifier are mixed and reacted at a temperature of 230-240℃ and a pressure of 0.25-0.3MPa for 2-3 hours. The pressure is then reduced, and the temperature is raised to 270-280℃ for 20-40 minutes. The temperature is kept constant, and the pressure is adjusted to 160-180Pa. The reaction continues for another 2-3 hours. The material is then discharged, cured, and pelletized to obtain high-performance PET copolyester masterbatch. In the above process, terephthalic acid, ethylene glycol, and 1,6-hexanediol are used as raw materials, and a modifier is used as a functional structure to copolymerize and obtain a high-performance PET copolyester masterbatch. The modifier has excellent mechanical properties and thermal stability. Among them, the hydrophobic high-performance PET copolyester masterbatch with CF bond and imide ring structure can effectively block the erosion of corrosive media. In addition, the presence of polyurethane bonds, CF bonds, benzene rings and triazine rings in the modifier can also form hydrogen bonds and π-π conjugation in the system, thereby increasing the crosslinking density of PET copolyester and improving its comprehensive performance. Furthermore, the introduction of alkyl segments in the modifier and the alkyl chain in 1,6-hexanediol effectively improves the flexibility of the high-performance PET copolyester masterbatch, so that the high-performance PET copolyester masterbatch can simultaneously take into account mechanical strength and flexibility.

[0007] Preferably, the molar ratio of terephthalic acid, ethylene glycol, 1,6-hexanediol, and modifier is (1.68-1.74):2:(7-7.5):(0.5-1); and the amount of tetrabutyl titanate is 0.8-1.2 wt% of the amount of terephthalic acid.

[0008] Preferably, in step two, the method for preparing the modifier is as follows: In a nitrogen atmosphere, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and dibutyltin dilaurate were added to tetrahydrofuran, followed by the addition of hexamethylene diisocyanate. The mixture was heated to 57-63°C and stirred for 3-5 hours. After purification, a fluorine-containing compound was obtained. The mass ratio of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, dibutyltin dilaurate, tetrahydrofuran, and hexamethylene diisocyanate was (4.2-8.4):(0.01-0.03):(100-150):(7-15). In a nitrogen atmosphere, a fluorinated compound, an imide compound, and dibutyltin dilaurate are added to N,N-dimethylformamide and stirred at 70-80°C for 2-4 hours. The mixture is then purified to obtain the modifier. The mass ratio of the fluorinated compound, the imide compound, dibutyltin dilaurate, and N,N-dimethylformamide is (8.2-16.4):(4.2-8.4):(0.02-0.04):(100-200). In the above process, the hydroxyl groups of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol react with the isocyanate groups of hexamethylene diisocyanate to form polyurethane bonds, yielding fluorinated compounds. The CF bonds in the fluorinated compounds of this invention have excellent hydrophobicity and thermal stability, and the alkyl segments introduced by hexamethylene diisocyanate have excellent flexibility. The reaction of the fluorinated compounds with imide compounds produces a modifier that combines the advantages of both fluorinated compounds and imide compounds, exhibiting excellent mechanical properties, thermal stability, and hydrophobicity.

[0009] Preferably, in step three, the mass ratio of the high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide is (20-40):100:(5-15).

[0010] Preferably, in step three, the melt spinning conditions are: spinning speed 600 m / min, melting temperature 282-291℃.

[0011] Preferably, in step three, the composite modified graphene oxide is prepared by the following method: Step S1: Mix acyl carboroline chloride and tetrahydrofuran at a mass ratio of (2.5-3.5):(40-60), stir to obtain mixture A; mix graphene oxide and tetrahydrofuran at a mass ratio of (3-5):(300-400), sonicate, add mixture A dropwise at 0℃, stir for 1.5-2.5h, then stir at 23-25℃ for 3.5-4.5h, purify to obtain surface-modified graphene oxide; Step S2: Dimethyl terephthalate, ethylene glycol, and zinc acetate are mixed and reacted at 188-192℃ for 1.5-2.5h. Then, antimony trioxide and triphenyl phosphate are added, and stirring is continued for 50-70min. Then, surface-modified graphene oxide is added, and the temperature is raised to 226-234℃ and maintained for 100-150min. After purification, composite modified graphene oxide is obtained. The mass ratio of dimethyl terephthalate, ethylene glycol, zinc acetate, antimony trioxide, triphenyl phosphate, and surface-modified graphene oxide is (11.2-33.6):(7.8-23.4):(0.02-0.04):(0.01-0.03):(0.03-0.07):(0.1-0.5). In the above process, graphene oxide exhibits excellent mechanical properties, thermal stability, and barrier properties. The acyl chloride groups in carborane chloride can react with the active hydroxyl groups in graphene oxide. Grafting carborane chloride onto graphene oxide further enhances its overall performance, resulting in surface-modified graphene oxide. The surface-modified graphene oxide incorporates a large number of acyl chloride groups, exhibiting high reactivity. It can successfully undergo covalent grafting modification with the hydroxyl groups of low molecular weight polyester. By in-situ polymerization grafting of low molecular weight polyethylene terephthalate onto the surface-modified graphene oxide, composite-modified graphene oxide is obtained. The low molecular weight polyethylene terephthalate on the composite-modified graphene oxide improves its interfacial compatibility with the polyester matrix, promotes the dispersion of the composite-modified graphene oxide, and can also act as a nucleation aid to promote polyester crystallization, thereby further improving the overall performance of the polyester.

[0012] Further, the preparation method of the acylcarboborane chloride: In a nitrogen atmosphere, m-carborane was dissolved in tetrahydrofuran and stirred. At 0°C, a 2.4 mol / L n-butyllithium solution in n-hexane was added dropwise while stirring. Then, carbon dioxide gas was introduced and continuously for 50-70 min. The reaction was then quenched with a 1 mol / L hydrochloric acid aqueous solution and purified to obtain carboxylated carborane. The mass ratio of m-carborane, tetrahydrofuran, and the 2.4 mol / L n-butyllithium solution in n-hexane was (4.4-6.6):(100-120):(22.8-34.2). Carboxylated carborane, phosphorus pentachloride, and phosphorus oxychloride were mixed in a mass ratio of (2.2-4.4):(16.8-33.6):(3.3-6.6), stirred at 88-92℃ for 100-150 min, and then chlorine gas was introduced while keeping the temperature constant for 50-70 min to purify the mixture and obtain acylcarborane. In the above process, carborane is considered to be one of the best organic groups for improving the performance of organic polymers (such as polyesters, polysilanes, polysiloxanes and polybenzoxazines). It has a rigid icosahedral structure and has significant thermal and chemical stability. In this invention, carborane is sequentially carboxylated and acylchlorinated to introduce active acyl chloride groups into carborane.

[0013] The polyester industrial yarn for geogrid is prepared by the aforementioned method.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a polyester industrial yarn for geogrids. The polyester industrial yarn for geogrids of this invention not only has the characteristics of high strength and high temperature resistance, but also has good corrosion resistance and can effectively resist the erosion of acid / alkali corrosive media. When used in warp-knitted polyester geogrids, it can improve the working performance of warp-knitted polyester geogrids and extend their service life.

[0015] 2. The polyester industrial yarn for geogrids of the present invention is obtained by melt spinning a mixture of high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide. The high-performance PET copolyester masterbatch and composite modified graphene oxide, as functional components, significantly improve the overall performance of the polyester industrial yarn, specifically in the following ways: (1) The high-performance PET copolyester masterbatch is obtained by copolymerization of terephthalic acid, ethylene glycol, and 1,6-hexanediol as raw materials and modifier as functional structure. The modifier combines the advantages of fluorinated compounds and imide compounds. Due to the presence of CF bond, imide ring structure, polyurethane bond, benzene ring and triazine ring, it has excellent mechanical properties, thermal stability and corrosion resistance. (2) The composite modified graphene oxide is grafted with carborane and low molecular weight polyester. The grafting of carborane further improves the overall performance of graphene oxide, while the grafting of low molecular weight polyester improves the interfacial compatibility between the composite modified graphene oxide and the polyester matrix. The composite modified graphene oxide of the present invention can not only be used as a functional component, but also as a nucleating agent to promote polyester crystallization.

[0016] In summary, the combined effect of high-performance PET copolyester masterbatch and composite modified graphene oxide endows the polyester industrial yarn for geogrids with excellent comprehensive properties. Attached Figure Description

[0017] Figure 1 These are comparative graphs showing the tensile strength tests of polyester industrial yarns for geogrids prepared in Examples 2-4 and Comparative Examples 2-6 of this invention. Figure 2 This is a comparison chart of the breaking strength loss rate (after acid treatment and after alkali treatment) of the polyester industrial yarn for geogrid prepared in Examples 2-4 and Comparative Examples 2-6 of the present invention. Figure 3 This is a schematic diagram illustrating the synthesis of the intermediate products of this invention; Figure 4 This is a schematic diagram illustrating the synthesis of the imide-based compound of the present invention; Figure 5 This is a schematic diagram illustrating the synthesis of the fluorine-containing compound of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] Example 1 This embodiment discloses a method for preparing composite modified graphene oxide, including the following steps: Step S1: Under a nitrogen atmosphere, 5.5 g of m-carborane was dissolved in 110 g of tetrahydrofuran and stirred. At 0 °C, 28.5 g of 2.4 mol / L n-butyllithium in n-hexane was added dropwise and stirred for 30 min. Then, carbon dioxide gas was introduced and continued for 60 min. The reaction was quenched with 1 mol / L hydrochloric acid aqueous solution. After evaporating the tetrahydrofuran, the mixture was extracted with diethyl ether. The extracted organic layer was washed three times with deionized water and saturated sodium chloride aqueous solution, and dried with anhydrous magnesium sulfate. The solvent was evaporated, and the resulting solid residue was recrystallized three times with dichloroethane to obtain carboxylated carborane. 3.3 g of carboxylated carborane, 25.2 g of phosphorus pentachloride and 5 g of phosphorus oxychloride were mixed and stirred at 90 °C for 125 min. Then, chlorine gas was introduced while keeping the temperature constant for 60 min. After the reaction was completed, phosphorus oxychloride was removed by rotary evaporation and the residue was extracted with n-pentane. After filtration, the crude product was sublimated under reduced pressure to obtain carborane oxychloride. Add 3g of acyl carboroline chloride to 50g of tetrahydrofuran and stir for 30min to obtain mixture A; add 4g of graphene oxide to 350g of tetrahydrofuran and sonicate for 50min. Add the mixture A dropwise at 0℃ and stir for 2h. Then stir at 24℃ for 4h. After the reaction is complete, centrifuge, wash and dry to obtain surface-modified graphene oxide. Step S2: Mix 22.4g dimethyl terephthalate, 31.2g ethylene glycol, and 0.03g zinc acetate, and react at 190℃ for 2h. Then add 0.02g antimony trioxide and 0.05g triphenyl phosphate, and continue stirring for 60min. Then add 0.3g surface-modified graphene oxide, heat to 230℃ and maintain for 125min, centrifuge, wash the centrifuged product with a phenol / carbon tetrachloride mixture at a volume ratio of 1:1, and vacuum dry to obtain composite modified graphene oxide.

[0020] Example 2 This embodiment discloses a method for preparing polyester industrial yarn for geogrids, including the following steps: Step 1: Under a nitrogen atmosphere, add 6g of cyanuric chloride to 120g of tetrahydrofuran, cool to 0℃, and add 46.3g of 7.6wt% m-phenylenediamine / tetrahydrofuran solution dropwise over 30min under stirring. Then add 8.2g of sodium bicarbonate, heat to 50℃, and stir for 6h. After the reaction is complete, filter, precipitate the filtrate with n-heptane, filter again, collect the solid product and dry it to obtain the intermediate product. In a nitrogen atmosphere, 4 g of the intermediate product was added to 100 g of N,N-dimethylformamide and stirred for 20 min. Then, 4.9 g of 4-hydroxyphthalic anhydride was added and reacted at 120 °C for 4 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the imide compound. Step 2: Under a nitrogen atmosphere, 4.2 g of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and 0.01 g of dibutyltin dilaurate were added to 100 g of tetrahydrofuran with stirring. Then, 7 g of hexamethylene diisocyanate was added, and the mixture was heated to 57 °C and stirred for 5 h. After the reaction was completed, the solvent was removed by continuous heating. The product was washed with n-hexane and dried to obtain a fluorine-containing compound. In a nitrogen atmosphere, 8.2 g of a fluorine-containing compound, 4.2 g of an imide compound, and 0.02 g of dibutyltin dilaurate were added to 100 g of N,N-dimethylformamide. The mixture was stirred at 70 °C for 4 h. After the reaction was completed, the solvent was removed by rotary evaporation. The crude product was washed with chloroform and dried to obtain the modifier. In a nitrogen atmosphere, terephthalic acid, ethylene glycol, 1,6-hexanediol, tetrabutyl titanate, and a modifier were mixed and added to a reactor. The mixture was reacted at 230°C and 0.25 MPa for 3 hours. The pressure was then reduced, and the temperature was raised to 270°C for 40 minutes. The temperature was maintained constant, and the pressure was adjusted to 160 Pa, continuing the reaction for another 3 hours. After the reaction, the mixture was discharged under nitrogen pressure, cured with cold water, and pelletized to obtain high-performance PET copolyester masterbatch. The molar ratio of terephthalic acid, ethylene glycol, 1,6-hexanediol, and the modifier was 1.68:2:7.5:0.5; the amount of tetrabutyl titanate was 0.8 wt% of the amount of terephthalic acid. Step 3: Mix high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide at a mass ratio of 20:100:5, and melt spin to obtain polyester industrial yarn for geogrid; wherein, the melt spinning conditions are: spinning speed 600m / min, melting temperature: 282℃.

[0021] Example 3 This embodiment discloses a method for preparing polyester industrial yarn for geogrids, including the following steps: Step 1: Under a nitrogen atmosphere, add 12g of cyanuric chloride to 150g of tetrahydrofuran, cool to 0℃, and add 92.6g of 7.6wt% m-phenylenediamine / tetrahydrofuran solution dropwise over 60min with stirring. Then add 16.4g of sodium bicarbonate, heat to 60℃, and stir for 4h. After the reaction is complete, filter, precipitate the filtrate with n-heptane, filter again, collect the solid product and dry it to obtain the intermediate product. In a nitrogen atmosphere, 6.4 g of the intermediate product was added to 150 g of N,N-dimethylformamide and stirred for 40 min. Then, 7.9 g of 4-hydroxyphthalic anhydride was added and reacted at 130 °C for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain the imide compound. Step 2: Under a nitrogen atmosphere, 8.4 g of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and 0.03 g of dibutyltin dilaurate were added to 150 g of tetrahydrofuran with stirring. Then, 15 g of hexamethylene diisocyanate was added, and the mixture was heated to 63 °C and stirred for 3 h. After the reaction was completed, the solvent was removed by continuous heating. The product was washed with n-hexane and dried to obtain a fluorine-containing compound. In a nitrogen atmosphere, 16.4 g of a fluorine-containing compound, 8.4 g of an imide compound, and 0.04 g of dibutyltin dilaurate were added to 200 g of N,N-dimethylformamide. The mixture was stirred at 80 °C for 2 h. After the reaction was completed, the solvent was removed by rotary evaporation. The crude product was washed with chloroform and dried to obtain the modifier. In a nitrogen atmosphere, terephthalic acid, ethylene glycol, 1,6-hexanediol, tetrabutyl titanate, and a modifier were mixed and added to a reactor. The mixture was reacted at 240°C and 0.25 MPa for 2 hours. The pressure was then reduced, and the temperature was raised to 280°C for 20 minutes. The temperature was maintained constant, and the pressure was adjusted to 180 Pa, continuing the reaction for another 2 hours. After the reaction, the mixture was discharged under nitrogen pressure, cured with cold water, and pelletized to obtain high-performance PET copolyester masterbatch. The molar ratio of terephthalic acid, ethylene glycol, 1,6-hexanediol, and the modifier was 1.74:2:7:1; the amount of tetrabutyl titanate was 1.2 wt% of the amount of terephthalic acid. Step 3: Mix high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide at a mass ratio of 40:100:15, and melt spin to obtain polyester industrial yarn for geogrid; wherein, the melt spinning conditions are: spinning speed 600m / min, melting temperature: 291℃.

[0022] Example 4 This embodiment discloses a method for preparing polyester industrial yarn for geogrids, including the following steps: Step 1: Under a nitrogen atmosphere, add 9g of cyanuric chloride to 135g of tetrahydrofuran, cool to 0℃, and add 69.5g of 7.6wt% m-phenylenediamine / tetrahydrofuran solution dropwise over 45min while stirring. Then add 12.3g of sodium bicarbonate, heat to 55℃, and stir for 5h. After the reaction is complete, filter the solution. Precipitate the filtrate with n-heptane, filter again, collect the solid product, and dry it to obtain the intermediate product. In a nitrogen atmosphere, 5.2 g of the intermediate product was added to 125 g of N,N-dimethylformamide and stirred for 30 min. Then, 6.4 g of 4-hydroxyphthalic anhydride was added and reacted at 125 °C for 3 h. After the reaction was completed, the solvent was removed by rotary evaporation to obtain an imide compound. Step 2: Under a nitrogen atmosphere, 6.3 g of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and 0.02 g of dibutyltin dilaurate were added to 125 g of tetrahydrofuran with stirring. Then, 11 g of hexamethylene diisocyanate was added, and the mixture was heated to 60 °C and stirred for 4 h. After the reaction was completed, the solvent was removed by continuous heating. The product was washed with n-hexane and dried to obtain a fluorine-containing compound. In a nitrogen atmosphere, 12.3 g of a fluorine-containing compound, 6.3 g of an imide compound, and 0.03 g of dibutyltin dilaurate were added to 150 g of N,N-dimethylformamide. The mixture was stirred at 75 °C for 3 h. After the reaction was completed, the solvent was removed by rotary evaporation. The crude product was washed with chloroform and dried to obtain the modifier. In a nitrogen atmosphere, terephthalic acid, ethylene glycol, 1,6-hexanediol, tetrabutyl titanate, and a modifier were mixed and added to a reactor. The mixture was reacted at 235°C and 0.28 MPa for 2.5 hours. The pressure was then reduced, and the temperature was raised to 275°C for 30 minutes. The temperature was maintained constant, and the pressure was adjusted to 170 Pa for another 2.5 hours. After the reaction, the mixture was discharged under nitrogen pressure, cured with cold water, and pelletized to obtain high-performance PET copolyester masterbatch. The molar ratio of terephthalic acid, ethylene glycol, 1,6-hexanediol, and the modifier was 1.71:2:7.3:0.7. The amount of tetrabutyl titanate was 1 wt% of the amount of terephthalic acid. Step 3: Mix high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide at a mass ratio of 30:100:10, and melt spin to obtain polyester industrial yarn for geogrid; wherein, the melt spinning conditions are: spinning speed 600m / min, melting temperature: 287℃.

[0023] The composite modified graphene oxide in Examples 2-4 above is the composite modified graphene oxide prepared in Example 1.

[0024] Comparative Example 1 Compared with Example 1, Comparative Example 1 used modified graphene oxide instead of surface-modified graphene oxide in the process of preparing composite modified graphene oxide, while other conditions remained unchanged.

[0025] Comparative Example 2 Compared with Example 4, Comparative Example 2 used the composite modified graphene oxide prepared in Comparative Example 1 in the process of preparing polyester industrial yarn for geogrid, while keeping other conditions unchanged.

[0026] Comparative Example 3 Compared with Example 4, Comparative Example 3 used surface-modified graphene oxide prepared in Example 1 instead of composite-modified graphene oxide prepared in Example 1 in the process of preparing polyester industrial yarn for geogrid, while keeping other conditions unchanged.

[0027] Comparative Example 4 Compared with Example 4, Comparative Example 4 did not add composite modified graphene oxide during the preparation of polyester industrial yarn for geogrids, and all other conditions remained unchanged.

[0028] Comparative Example 5 Compared with Example 4, Comparative Example 5 used an imide-based compound instead of a modifier in the preparation of high-performance PET copolyester masterbatch, while keeping other conditions unchanged.

[0029] Comparative Example 6 Compared with Example 4, Comparative Example 6 used a fluorinated compound instead of a modifier in the preparation of high-performance PET copolyester masterbatch, while keeping other conditions unchanged.

[0030] In the above examples and comparative examples, the graphene oxide (GO), with a thickness of 0.55-1.2 nm and a diameter of 0.5-3 μm, was sourced from Zhongke Leiming (Beijing) Technology Co., Ltd.; the polyester chips had a molecular weight of 3 × 10⁻⁶. 4 The intrinsic viscosity is 0.676 dL / g, and it comes from Sinopec Yizheng Chemical Fiber Co., Ltd.

[0031] Experimental Example I. Mechanical property testing: Referring to GB / T 14344-2003 "Test method for tensile properties of synthetic fiber filaments", the tensile properties of the polyester industrial yarns for geogrids prepared in Examples 2-4 and Comparative Examples 2-6 were tested on a YG061 electronic single yarn tensile tester. The sample clamping length was 500 mm, the tensile speed was 500 mm / min, and the pre-tension was 0.05 cN / dtex. The average value was taken after 30 measurements. Before the test, the samples were equilibrated in a constant temperature and humidity chamber [temperature (20±2)℃, relative humidity 65%±2%] for 24 h. II. Durability Test: (1) Take the polyester industrial yarns for geogrids prepared in Examples 2-4 and Comparative Examples 2-6, five yarns per group, each 1m in length, and conduct tests in dilute sulfuric acid and calcium hydroxide reagents of certain concentrations at different temperatures. Place the samples in beakers of different solutions and immerse them in a water bath: The experimental conditions were as follows: In the acid resistance test, the soaking time was controlled at 10 h, the acid concentration was 1 mol / L, and the temperature was 100 °C; in the alkali resistance test, the pH of the alkali solution was controlled at 13 and the temperature was 100 °C, with a treatment time of 10 h; the volume of liquid used in the experiment was at least 30 times the weight of the sample, and the sample was completely submerged in the liquid during the soaking test; the distance between the sample and the container wall, and between the sample and the liquid surface, was greater than 10 mm; the calcium hydroxide solution should be continuously stirred during the alkali soaking test. (2) After soaking the sample, take it out, first wash it in clean water, then wash it with 0.01 mol / L sodium carbonate solution, and finally wash it thoroughly in clean water and dry it at room temperature. (3) Using the method of Test 1, the breaking strength of the industrial yarn after acid and alkali soaking was tested, and the breaking strength loss rate after acid and alkali treatment was calculated according to the following formulas: Fracture strength loss rate = (fracture strength before acid-alkali treatment - fracture strength after acid-alkali treatment) / fracture strength before acid-alkali treatment × 100%.

[0032] The test results are shown in Table 1: Table 1 ; As can be seen from the test results in Table 1, the polyester industrial yarn for geogrids prepared in Examples 2-4 of the present invention has excellent mechanical strength, and the breaking strength loss rate after high temperature acid and alkali treatment does not exceed 1%, indicating that it has excellent high temperature resistance and acid and alkali corrosion resistance. As can be seen from the comparison between Comparative Examples 2-4 and Example 4, graphene oxide possesses excellent mechanical properties, thermal stability, and barrier properties. It can be used not only as a functional filler but also as a nucleating agent to promote polyester crystallization. The composite modified graphene oxide is grafted with carborane and low molecular weight polyester. Among them, carborane has a rigid icosahedral structure and significant thermal and chemical stability. The grafting of carborane further enhances the comprehensive performance of graphene oxide. The grafting of low molecular weight polyester improves the interfacial compatibility between the composite modified graphene oxide and the polyester matrix, thereby improving the comprehensive performance of polyester industrial yarn. As can be seen from the comparison between Comparative Examples 5-6 and Example 4, the combination of fluorinated compounds and imide compounds in the modifier of the present invention introduces CF bonds, imide ring structures, polyurethane bonds, benzene rings and triazine rings into the high-performance PET copolyester masterbatch, giving it excellent mechanical properties, thermal stability and corrosion resistance, thereby giving polyester industrial yarn better performance.

[0033] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing polyester industrial yarn for geogrids, characterized in that, Includes the following steps: Step 1: Cyanuronyl chloride reacts with m-phenylenediamine to obtain an intermediate product; the intermediate product then reacts with 4-hydroxyphthalic anhydride to obtain an imide compound. Step 2: Polymerize terephthalic acid, ethylene glycol, 1,6-hexanediol, and modifier, discharge the material, and granulate it to obtain high-performance PET copolyester masterbatch; wherein, the modifier is obtained by reacting a fluorinated compound with an imide compound, and the fluorinated compound is obtained by reacting 2,2,3,3,4,4-hexafluoro-1,5-pentanediol with hexamethylene diisocyanate; Step 3: Mix high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide, and melt spin to obtain polyester industrial yarn for geogrids.

2. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step one, the method for preparing the imide compound is as follows: In a nitrogen atmosphere, cyanuric chloride was added to tetrahydrofuran and cooled to 0°C. Under stirring, a 7.6 wt% m-phenylenediamine / tetrahydrofuran solution was added dropwise, followed by sodium bicarbonate. The mixture was heated to 50-60°C and stirred for 4-6 hours. After purification, an intermediate product was obtained. The mass ratio of cyanuric chloride, tetrahydrofuran, 7.6 wt% m-phenylenediamine / tetrahydrofuran solution, and sodium bicarbonate was (6-12):(120-150):(46.3-92.6):(8.2-16.4). In a nitrogen atmosphere, the intermediate product was added to N,N-dimethylformamide and stirred. Then, 4-hydroxyphthalic anhydride was added, and the mixture was reacted at 120-130°C for 2-4 hours. After purification, an imide compound was obtained. The mass ratio of the intermediate product, N,N-dimethylformamide, and 4-hydroxyphthalic anhydride was (4-6.4):(100-150):(4.9-7.9).

3. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step two, the preparation method of the high-performance PET copolyester masterbatch is as follows: In a nitrogen atmosphere, terephthalic acid, ethylene glycol, 1,6-hexanediol, tetrabutyl titanate, and modifier are mixed and reacted at 230-240℃ and 0.25-0.3MPa for 2-3 hours. The pressure is then reduced, and the temperature is raised to 270-280℃ for 20-40 minutes. The temperature is kept constant, and the pressure is adjusted to 160-180Pa. The reaction continues for another 2-3 hours. The mixture is then discharged, cured, and pelletized to obtain high-performance PET copolyester masterbatch.

4. The method for preparing polyester industrial yarn for geogrids according to claim 3, characterized in that, The molar ratio of terephthalic acid, ethylene glycol, 1,6-hexanediol, and modifier is (1.68-1.74):2:(7-7.5):(0.5-1); the amount of tetrabutyl titanate is 0.8-1.2 wt% of the amount of terephthalic acid.

5. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step two, the method for preparing the modifier is as follows: In a nitrogen atmosphere, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol and dibutyltin dilaurate were added to tetrahydrofuran, followed by the addition of hexamethylene diisocyanate. The mixture was heated to 57-63°C and stirred for 3-5 hours. After purification, a fluorine-containing compound was obtained. The mass ratio of 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, dibutyltin dilaurate, tetrahydrofuran, and hexamethylene diisocyanate was (4.2-8.4):(0.01-0.03):(100-150):(7-15). In a nitrogen atmosphere, a fluorinated compound, an imide compound, and dibutyltin dilaurate are added to N,N-dimethylformamide and stirred at 70-80°C for 2-4 hours. The mixture is then purified to obtain the modifier. The mass ratio of the fluorinated compound, the imide compound, dibutyltin dilaurate, and N,N-dimethylformamide is (8.2-16.4):(4.2-8.4):(0.02-0.04):(100-200).

6. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step three, the mass ratio of the high-performance PET copolyester masterbatch, polyester chips, and composite modified graphene oxide is (20-40):100:(5-15).

7. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step three, the melt spinning conditions are: spinning speed 600 m / min, melting temperature 282-291℃.

8. The method for preparing polyester industrial yarn for geogrids according to claim 1, characterized in that, In step three, the composite modified graphene oxide is prepared by the following method: Step S1: Mix acyl carboroline chloride and tetrahydrofuran at a mass ratio of (2.5-3.5):(40-60), stir to obtain mixture A; mix graphene oxide and tetrahydrofuran at a mass ratio of (3-5):(300-400), sonicate, add mixture A at 0℃, stir for 1.5-2.5h, then stir at 23-25℃ for 3.5-4.5h, purify to obtain surface-modified graphene oxide; Step S2: Dimethyl terephthalate, ethylene glycol, and zinc acetate are mixed and reacted at 188-192℃ for 1.5-2.5h. Then, antimony trioxide and triphenyl phosphate are added, and stirring is continued for 50-70min. Then, surface-modified graphene oxide is added, and the temperature is raised to 226-234℃ and maintained for 100-150min. After purification, composite modified graphene oxide is obtained. The mass ratio of dimethyl terephthalate, ethylene glycol, zinc acetate, antimony trioxide, triphenyl phosphate, and surface-modified graphene oxide is (11.2-33.6):(7.8-23.4):(0.02-0.04):(0.01-0.03):(0.03-0.07):(0.1-0.5).

9. The method for preparing polyester industrial yarn for geogrids according to claim 8, characterized in that, The preparation method of the acylcarborane chloride: In a nitrogen atmosphere, m-carborane was dissolved in tetrahydrofuran and stirred. At 0°C, a 2.4 mol / L n-butyllithium solution in n-hexane was added and stirred. Then, carbon dioxide gas was introduced and continuously for 50-70 min. The reaction was then quenched with a 1 mol / L hydrochloric acid aqueous solution and purified to obtain carboxylated carborane. The mass ratio of m-carborane, tetrahydrofuran, and the 2.4 mol / L n-butyllithium solution in n-hexane was (4.4-6.6):(100-120):(22.8-34.2). Carboxylated carborane, phosphorus pentachloride, and phosphorus oxychloride were mixed in a mass ratio of (2.2-4.4):(16.8-33.6):(3.3-6.6) and stirred at 88-92℃ for 100-150 min. Then, while keeping the temperature constant, chlorine gas was introduced and continuously passed through for 50-70 min to purify the mixture and obtain acylcarborane.

10. A polyester industrial yarn for geogrid prepared by the method for preparing polyester industrial yarn for geogrid as described in any one of claims 1-9.

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