Preparation process of a composite plastic woven fabric

Abstract

The present invention relates to the technical field of woven fabrics, and discloses a preparation process of a composite plastic woven fabric. In the present invention, polyethylene terephthalate and polyester flame retardant grafted silica are subjected to melt blending, divided into embryo filaments, stretched, shaped and other processes, and then woven by a weaving machine to obtain composite PET flat filaments and their plastic woven fabrics; after the nano-silica is grafted and modified by the polyester flame retardant, its compatibility in the PET flat filaments is better, the dispersion is excellent, the breaking strength and elongation at break of the PET flat filaments are significantly improved, the wear mass loss of the woven fabric is reduced, and higher mechanical properties and wear resistance are shown. The polyester flame retardant contains DOPO phosphate and bisimidazole groups to form a nitrogen-phosphorus flame retardant, which has a good synergistic flame retardant effect with the nano-silica, significantly improves the limiting oxygen index of the PET plastic woven fabric, and has better flame retardant performance.

Description

Technical Field

[0001] The present invention relates to the technical field of woven fabrics, and specifically to a preparation process of a composite plastic woven fabric. Background Art

[0002] Woven fabrics are mainly prepared from flat filaments such as PET (polyethylene terephthalate) and polyethylene through processes such as weaving, and have important applications in civil engineering, water conservancy, construction projects, etc. Developing high-performance PET flat filaments and their plastic woven fabrics and endowing them with properties such as flame retardancy and wear resistance are research hotspots. Flame retardants are a type of functional additive, mainly applied to materials such as plastics, textiles, and rubbers. Additive flame retardants are directly physically blended with the material matrix, and the operation is very simple. However, additive flame retardants will affect the mechanical properties and other properties of the polymer material matrix. Therefore, it is necessary to improve the compatibility between the flame retardant and the material matrix.

[0003] Nano-silica is an inorganic nano material with a high specific surface area, high mechanical strength, strong wear resistance, and easy surface organic modification. Patent CN117431682A discloses mesoporous silica microspheres modified with 2,3,5,5,5-pentachloro-4-oxo-pentenoic acid, then mixed and spun with polyethylene terephthalate, and finally woven with nylon fibers to obtain a tensile mesh yarn with the advantages of good waterproofness, tensile property, and antibacterial property. Compared with the tensile mesh yarn of this invention, the present invention uses a polyester flame retardant grafted on silica to improve the wear resistance, flame retardancy and other properties of PET flat filaments and their woven fabrics. Summary of the Invention

[0004] The present invention solves the problems of poor mechanical properties and flame retardancy of PET flat filaments and their woven fabrics.

[0005] The technical solution of the present invention: A preparation process of a composite plastic woven fabric, the composite plastic woven fabric is woven by a knitting machine from composite PET flat filaments.

[0006] The preparation process of the composite PET flat filaments is as follows:

[0007] Step S1: Add succinic acid-based DOPO, bis-hydroxyethyl imidazole intermediate, and p-toluenesulfonic acid with a molar ratio of 1:(1.05 - 1.1):(0.05 - 0.07) to N,N-dimethylformamide, stir and dissolve, heat to 150 - 155 °C, react for 10 - 15 h, and carry out condensation reflux during the reaction; after cooling, pour the solution into ethanol, filter, and wash successively with ethanol and dichloromethane, and then dry to obtain a polyester flame retardant. The reaction formula is:

[0008] .

[0009] Step S2: Add polyester flame retardant into N,N-dimethylformamide, stir and then add TDI-modified silica and dibutyltin dilaurate, where the mass ratio of polyester flame retardant, TDI-modified silica and dibutyltin dilaurate is (0.3 - 0.8):1:(0.002 - 0.006); Heat to 80 - 90 °C, react for 6 - 10 h, after cooling, pour the solution into ethanol, filter, wash with ethanol, and dry to obtain polyester flame retardant grafted silica.

[0010] Step S3: Add 100 parts by weight of polyethylene terephthalate and 0.5 - 4 parts by weight of polyester flame retardant grafted silica into a twin-screw extruder for melt blending and extrusion; then form a film through a casting film machine; finally, divide it into embryo filaments through a flat yarn machine, stretch and shape to obtain composite PET flat yarn.

[0011] Preferably, the temperatures of each section of the twin-screw extruder in Step S3 are 160 - 280 °C, the screw speed is 100 - 150 r / min; the temperatures of each section of the casting film machine are 265 - 290 °C, the screw speed is 80 - 100 r / min; the temperature during stretching is 95 - 100 °C, and the stretching ratio is 4.5 - 5.5.

[0012] Preferably, the preparation process of the bis(hydroxyethyl)imidazole intermediate is as follows: Add 2-(1H-imidazol-5-yl)ethanol (CAS No. 872-82-2), 1,4-bis(bromomethyl)benzene (CAS No. 623-24-5), and potassium carbonate with a molar ratio of (2 - 2.4):1:(2.2 - 2.8) into an acetonitrile or tetrahydrofuran solvent, heat to 40 - 50 °C, stir and react for 12 - 18 h, perform vacuum distillation, wash with water, dissolve the product in ethanol, heat and volatilize to precipitate, and then cool and recrystallize in an ice-water bath to obtain the bis(hydroxyethyl)imidazole intermediate. The reaction formula is:

[0013] 。

[0014] Preferably, the preparation process of TDI-modified silica is as follows: Add 100 parts by weight of nano-silica into toluene, disperse ultrasonically, add 60 - 100 parts by weight of toluene-2,4-diisocyanate, heat to 80 - 90 °C, react for 2 - 3 h, filter, wash with toluene, and dry to obtain TDI-modified silica.

[0015] Technical effect: The present invention uses 2-(1H-imidazol-5-yl)ethanol and 1,4-bis(bromomethyl)benzene to carry out a substitution reaction, and then carries out an esterification polymerization reaction with succinic acid-based DOPO to obtain a polyester flame retardant, and then uses its terminal hydroxyl group to react with the isocyanate group on the surface of TDI-modified silica, thereby grafting the polyester flame retardant onto the surface of nano-silica, namely polyester flame retardant grafted silica.

[0016] The present invention performs processes such as melt blending of polyethylene terephthalate and polyester flame retardant grafted silica, dividing into embryo filaments, stretching, and shaping, and then weaving with a knitting machine to obtain composite PET flat filaments and their plastic woven fabrics; the polyester flame retardant contains polyester molecular chains and has good compatibility with PET polyester. After the nano-silica is grafted and modified by the polyester flame retardant, its compatibility in the PET flat filaments is better, with excellent dispersibility, significantly improving the breaking strength and elongation at break of the PET flat filaments, reducing the wear mass loss of the woven fabric, and showing higher mechanical properties and wear resistance.

[0017] The polyester flame retardant of the present invention contains DOPO phosphate and bis-imidazole groups to form a nitrogen-phosphorus flame retardant, which has a good synergistic flame retardant effect with nano-silica, significantly improving the limiting oxygen index of the PET plastic woven fabric and having better flame retardant performance. Specific Embodiments

[0018] In order to more clearly understand the above objects, features, and advantages of the present invention, the present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0019] The preparation process of succinic acid-based DOPO is as follows: Add 30 mL of xylene, 30 mL of tetrahydrofuran, and 10 g of DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) to a flask equipped with a condenser reflux tube, introduce nitrogen, heat to 95 °C, stir and then dropwise add 5.37 g of maleic acid, react for 10 h, cool and then filter by suction. The product is washed with a mixed solution of tetrahydrofuran and xylene, and dried to obtain succinic acid-based DOPO. The structural formula is .

[0020] Example 1

[0021] (1). Add 14.4 mmol of 2-(1H-imidazol-5-yl)ethanol, 6 mmol of 1,4-bis(bromomethyl)benzene, and 16.8 mmol of potassium carbonate to 30 mL of acetonitrile solvent, heat to 40 °C, stir and react for 18 h, distill under reduced pressure, wash with water, dissolve the product in ethanol, heat and evaporate to precipitate, and then cool and recrystallize in an ice-water bath to obtain a bis-hydroxyethyl imidazole intermediate.

[0022] (2). Add 0.5 g of nano-silica to 10 mL of toluene, ultrasonically disperse, add 0.3 g of toluene-2,4-diisocyanate, heat to 80 °C, react for 3 h, filter, wash with toluene, and dry to obtain TDI-modified silica.

[0023] (3) Add 10 mmol of succinic acid-based DOPO, 11 mmol of bis(2-hydroxyethyl)imidazole intermediate, and 0.6 mmol of p-toluenesulfonic acid to 50 mL of N,N-dimethylformamide, stir to dissolve, heat to 155 °C, react for 10 h, and carry out condensation reflux during the reaction; after cooling, pour the solution into ethanol, filter, wash successively with ethanol and dichloromethane, and dry to obtain a polyester flame retardant.

[0024] (4) Add 0.15 g of the polyester flame retardant to 40 mL of N,N-dimethylformamide, stir, add 0.5 g of TDI-modified silica (prepared according to the method of Example 1), and 1 mg of dibutyltin dilaurate, heat to 80 °C, react for 8 h, after cooling, pour the solution into ethanol, filter, wash with ethanol, and dry to obtain a polyester flame retardant grafted silica.

[0025] (5) Add 1000 g of polyethylene terephthalate glycol and 5 g of the polyester flame retardant grafted silica to a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, and 280 °C, and the screw speed is 100 r / min; then, use a casting film machine to make a film. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, and 285 °C, and the screw speed is 100 r / min; finally, use a flat yarn machine to cut into embryo filaments, stretch, and shape. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat yarns.

[0026] Example 2

[0027] (1) Add 12 mmol of 2-(1H-imidazol-5-yl)ethanol, 6 mmol of 1,4-bis(bromomethyl)benzene, and 13.2 mmol of potassium carbonate to 25 mL of tetrahydrofuran solvent, heat to 50 °C, stir and react for 12 h, carry out vacuum distillation, wash with water, dissolve the product in ethanol, heat to volatilize and precipitate, and then cool and recrystallize in an ice-water bath to obtain a bis(2-hydroxyethyl)imidazole intermediate.

[0028] (2) Add 0.5 g of nano-silica to 12 mL of toluene, ultrasonically disperse, add 0.5 g of toluene-2,4-diisocyanate, heat to 90 °C, react for 2 h, filter, wash with toluene, and dry to obtain TDI-modified silica.

[0029] (3) Add 10 mmol of succinic acid-based DOPO, 11 mmol of bis(2-hydroxyethyl)imidazole intermediate, and 0.5 mmol of p-toluenesulfonic acid to 60 mL of N,N-dimethylformamide, stir to dissolve, heat to 155 °C, react for 15 h, and carry out condensation reflux during the reaction; after cooling, pour the solution into ethanol, filter, wash successively with ethanol and dichloromethane, and dry to obtain a polyester flame retardant.

[0030] (4) Add 0.4 g of polyester flame retardant to 60 mL of N,N-dimethylformamide. After stirring, add 0.5 g of TDI-modified silica and 3 mg of dibutyltin dilaurate. Heat to 80 °C and react for 10 h. After cooling, pour the solution into ethanol, filter, wash with ethanol, and dry to obtain polyester flame retardant grafted silica.

[0031] (5) Add 1000 g of polyethylene terephthalate and 20 g of polyester flame retardant grafted silica to a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, and 280 °C, and the screw speed is 150 r / min; then form a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, and 285 °C, and the screw speed is 100 r / min; finally, divide into embryo filaments, stretch, and shape through a flat yarn machine. The temperature during stretching is 100 °C, and the stretching ratio is 4.5; obtain composite PET flat yarn.

[0032] Example 3

[0033] (1) Add 10 mmol of succinic acid-based DOPO, 10.5 mmol of bis(hydroxyethyl)imidazole intermediate (prepared according to the method of Example 1), and 0.7 mmol of p-toluenesulfonic acid to 50 mL of N,N-dimethylformamide. Stir to dissolve, heat to 150 °C, and react for 10 h with condensation reflux during the reaction; after cooling, pour the solution into ethanol, filter, wash successively with ethanol and dichloromethane, and dry to obtain polyester flame retardant.

[0034] (2) Add 0.28 g of polyester flame retardant to 40 mL of N,N-dimethylformamide. After stirring, add 0.5 g of TDI-modified silica and 2.2 mg of dibutyltin dilaurate. Heat to 90 °C and react for 6 h. After cooling, pour the solution into ethanol, filter, wash with ethanol, and dry to obtain polyester flame retardant grafted silica.

[0035] (3) Add 1000 g of polyethylene terephthalate and 40 g of polyester flame retardant grafted silica to a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, and 280 °C, and the screw speed is 100 r / min; then form a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, and 285 °C, and the screw speed is 80 r / min; finally, divide into embryo filaments, stretch, and shape through a flat yarn machine. The temperature during stretching is 95 °C, and the stretching ratio is 5.5; obtain composite PET flat yarn.

[0036] Comparative Example 1

[0037] (1) Add 1000 g of polyethylene terephthalate into a twin-screw extruder for melting and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min. Then, make a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min. Finally, divide it into embryo filaments through a flat yarn machine, stretch and shape. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat yarn.

[0038] Comparative Example 2

[0039] (1) Stir and mix 10 mmol of succinic acid-based DOPO and 11 mmol of bis-hydroxyethyl imidazole intermediate to obtain a composite flame retardant.

[0040] (2) Add 1000 g of polyethylene terephthalate and 5 g of the composite flame retardant into a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min. Then, make a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min. Finally, divide it into embryo filaments through a flat yarn machine, stretch and shape. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat yarn.

[0041] Comparative Example 3

[0042] (1) Add 1000 g of polyethylene terephthalate and 5 g of polyester flame retardant (prepared according to the method of Example 1) into a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min. Then, make a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min. Finally, divide it into embryo filaments through a flat yarn machine, stretch and shape. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat yarn.

[0043] Comparative Example 4

[0044] (1) Add 1000 g of polyethylene terephthalate and 5 g of TDI-modified silica (prepared according to the method of Example 1) into a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min; then make a film through a casting film machine, and the temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min; finally, divide it into embryo filaments through a flat filament machine, stretch and shape it. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat filaments.

[0045] Comparative Example 5

[0046] (1) Add 0.15 g of polyester flame retardant (prepared according to the method of Example 1) to 40 mL of N,N-dimethylformamide, stir and then add 0.5 g of nano-silica and 1 mg of dibutyltin dilaurate, heat to 80 °C, stir and mix for 8 h, after cooling, pour the solution into ethanol, filter and wash with ethanol, and dry to obtain polyester flame retardant-silica.

[0047] (2) Add 1000 g of polyethylene terephthalate and 5 g of polyester flame retardant-silica into a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min; then make a film through a casting film machine, and the temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min; finally, divide it into embryo filaments through a flat filament machine, stretch and shape it. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat filaments.

[0048] Comparative Example 6

[0049] (1) Add 10 mmol of succinic acid-based DOPO, 11 mmol of ethylene glycol, and 0.6 mmol of p-toluenesulfonic acid to 50 mL of N,N-dimethylformamide, stir to dissolve, heat to 155 °C, react for 10 h, and carry out condensation reflux during the reaction; after cooling, pour the solution into ethanol, filter and wash successively with ethanol and dichloromethane, and dry to obtain polyester flame retardant.

[0050] (2) Add 0.15 g of polyester flame retardant to 40 mL of N,N-dimethylformamide, stir and then add 0.5 g of TDI-modified silica and 1 mg of dibutyltin dilaurate, heat to 80 °C, react for 8 h, after cooling, pour the solution into ethanol, filter and wash with ethanol, and dry to obtain polyester flame retardant grafted silica.

[0051] (3) Add 1000 g of polyethylene terephthalate and 5 g of polyester flame retardant grafted silica into a twin-screw extruder for melt blending and extrusion. The temperatures of each section are 160 °C, 210 °C, 255 °C, 270 °C, 280 °C, 280 °C, and the screw speed is 100 r / min; then form a film through a casting film machine. The temperatures of each section are 265 °C, 275 °C, 295 °C, 290 °C, 285 °C, and the screw speed is 100 r / min; finally, divide it into embryo filaments through a flat yarn machine, stretch and shape it. The temperature during stretching is 100 °C, and the stretching ratio is 5; obtain composite PET flat yarns.

[0052] Use an electronic fabric strength tester to test the mechanical properties of PET flat yarns. The clamping distance is 200 mm, the stretching speed is 50 mm / min, each specimen is tested 5 times, and the average value is taken.

[0053] Weave the PET flat yarns into plastic woven fabrics through a weaving machine.

[0054] According to the method of GB T 5454-1997, use an oxygen index tester to test the limiting oxygen index of plastic woven fabrics. The larger the limiting oxygen index, the better the flame retardancy.

[0055] Use a friction and wear testing machine to test the wear resistance of plastic woven fabrics. The counter part is a 45# steel ring, the load is 1 kg, the rotation speed is 200 r / min, and the wear time is 10 min. Test the mass loss before and after wear. The smaller the wear mass loss, the better the wear resistance.

[0056] Table 1

[0057] Tensile breaking force (N) Elongation at break (%) Limiting oxygen index (%) Wear mass loss (mg) Example 1 45.2 63.1 26.4 50.6 Example 2 52.3 76.8 28.5 39.8 Example 3 50.5 62.7 29.8 32.0 Comparative example 1 37.3 52.9 20.8 58.4 Comparative example 2 34.1 48.5 25.3 61.7 Comparative example 3 37.6 52.4 25.5 58.5 Comparative example 4 43.7 61.9 21.3 51.1 Comparative example 5 39.2 56.0 26.3 55.4 Comparative example 6 45.0 63.6 25.2 50.9

[0058] For the PET flat yarns and their plastic woven fabrics in Comparative Example 1, polyester flame retardant grafted silica was not added. The breaking force and elongation at break were relatively low, the wear mass loss was relatively large, the mechanical properties and wear resistance were not good, and the limiting oxygen index was only 20.8%, with poor flame retardancy.

[0059] In Examples 1-3, polyester flame retardant grafted silica was added. The polyester flame retardant contains polyester molecular chains and has good compatibility with PET polyester. After the nano-silica is grafted and modified by the polyester flame retardant, its compatibility in PET flat yarns is better and the dispersion is excellent, which is beneficial to improving the mechanical properties and wear resistance of PET flat yarns and their woven fabrics, showing higher breaking force, elongation at break, and lower wear mass loss. At the same time, the polyester flame retardant contains DOPO phosphate and bis-imidazole groups, forming a nitrogen-phosphorus flame retardant, which has a good synergistic flame retardant effect with nano-silica, significantly improving the limiting oxygen index of PET plastic woven fabrics and having better flame retardant performance.

[0060] Comparative Example 2 added a composite flame retardant composed of a blend of succinic acid-based DOPO and a bis-hydroxyethyl imidazole intermediate. It does not contain a polyester molecular chain and has very poor compatibility with PET, which has a greater impact on the mechanical properties of PET flat filaments. The breaking force and elongation at break decreased significantly, the wear mass loss increased, and the mechanical properties and wear resistance were poor. And nano-silica was not added, resulting in a limiting oxygen index lower than that of each example.

[0061] Comparative Example 3 added a polyester flame retardant, which has very good compatibility with PET polyester and has almost no impact on the mechanical properties of PET flat filaments and woven fabrics. Its breaking force, elongation at break, and wear mass loss are very similar to those of Comparative Example 1, and it still maintains good mechanical properties. However, Comparative Example 3 did not add silica, resulting in lower mechanical properties, wear resistance, and flame retardancy than each example.

[0062] Comparative Example 4 added TDI-modified silica. After the nano-silica was modified with toluene-2,4-diisocyanate, its compatibility with PET polyester was also relatively good, and the mechanical properties and wear resistance of PET flat filaments and woven fabrics were also improved to a certain extent. However, the breaking force and elongation at break were lower than those of each example. It may be that compared with toluene-2,4-diisocyanate, the polyester flame retardant has better compatibility with PET polyester and can better improve the compatibility and dispersion of nano-silica in PET flat filaments. And the surface of the nano-silica in Comparative Example 4 was not grafted with a polyester flame retardant, and the limiting oxygen index of the PET plastic woven fabric was low and the flame retardancy was poor.

[0063] The nano-silica in Comparative Example 5 was not modified with toluene-2,4-diisocyanate and does not contain isocyanate groups on its surface, so it cannot react with the terminal hydroxyl groups of the polyester flame retardant, resulting in no polyester flame retardant grafted on the surface of the nano-silica. Its compatibility with PET polyethylene terephthalate is very poor, and its dispersion in PET flat filaments and woven fabrics is not good, and it does not improve its mechanical properties and wear resistance well.

[0064] Comparative Example 6 used ethylene glycol to replace the bis-hydroxyethyl imidazole intermediate and carried out an esterification polymerization reaction with succinic acid-based DOPO. The obtained polyester flame retardant does not contain an imidazole group and cannot form a nitrogen-phosphorus flame retardant with DOPO, resulting in a limiting oxygen index of the PET plastic woven fabric lower than that of each example and poor flame retardancy.

[0065] The examples are the preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above examples. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A process for preparing a composite plastic woven fabric, characterized in that: The composite plastic woven cloth is woven from composite PET flat yarns through a weaving machine; The preparation process of the composite PET flat yarn is: Step S1, adding succinate-based DOPO to N,N-dimethylformamide, the structural formula is The intermediate of bis(hydroxyethyl)imidazole and p-toluenesulfonic acid are stirred and dissolved, reacted, and after cooling, the solution is poured into ethanol, filtered, washed, and dried to obtain a polyester flame retardant; Step S2, adding polyester flame retardant to N,N-dimethylformamide, stirring, adding TDI modified silica and dibutyltin dilaurate, reacting, cooling, pouring the solution into ethanol, filtering, washing, and drying to obtain polyester flame retardant grafted silica; Step S3, adding 100 parts by weight of polyethylene terephthalate and 0.5-4 parts by weight of polyester flame retardant grafted silica into a twin-screw extruder for melt blending and extrusion; then forming a film sheet through a cast film machine; finally dividing into embryonic yarns through a flat yarn machine, stretching and shaping, and obtaining a composite PET flat yarn; The preparation process of the bishydroxyethyl imidazole intermediate is as follows: adding 2-(1H-imidazole-5-yl)ethanol, 1,4-di(bromomethyl)benzene and potassium carbonate in a molar ratio of (2-2.4):1:(2.2-2.8) to a solvent, heating to 40-50° C., stirring for reaction for 12-18 hours, distilling under reduced pressure, washing and recrystallizing to obtain the bishydroxyethyl imidazole intermediate; the solvent is acetonitrile or tetrahydrofuran.

2. The process for preparing the composite plastic woven fabric according to claim 1, characterized in that: In the step S1, the molar ratio of succinic acid-based DOPO, bis(hydroxyethyl)imidazole intermediate, and p-toluenesulfonic acid is 1:(1.05-1.1):(0.05-0.07).

3. The process for preparing the composite plastic woven fabric according to claim 1, characterized in that: The reaction temperature in step S1 is 150-155° C., and the reaction time is 10-15 hours.

4. The process for preparing the composite plastic woven fabric according to claim 1, characterized in that: In the step S2, the mass ratio of the polyester flame retardant, TDI-modified silica, and dibutyltin dilaurate is (0.3-0.8):1:(0.002-0.006).

5. The process for preparing the composite plastic woven fabric according to claim 1, characterized in that: The reaction temperature in step S2 is 80-90° C., and the reaction time is 6-10 h.

6. The process for preparing the composite plastic woven fabric according to claim 1, characterized in that: In step S3, the temperature of each section of the twin-screw extruder is 160-280°C, and the screw speed is 100-150r / min; the temperature of each section of the cast film machine is 265-290°C, and the screw speed is 80-100r / min; the temperature during stretching is 95-100°C, and the stretching ratio is 4.5-5.

5.

7. The process for preparing the composite plastic woven fabric according to claim 4, characterized in that: The preparation process of the TDI modified silica is as follows: adding 100 parts by weight of nano-silicon dioxide into toluene, ultrasonically dispersing, adding 60-100 parts by weight of toluene-2,4-diisocyanate, heating to 80-90° C., reacting for 2-3 hours, filtering, washing, and drying to obtain the TDI modified silica.

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