Preparation process of chemical fiber polyester composite yarn

Abstract

The invention discloses a preparation process of a chemical fiber polyester composite yarn, and belongs to the technical field of chemical fiber material preparation, and the preparation process comprises the following steps: by taking L-glutamic acid-5-tert-butyl ester as a raw material, firstly converting amino into hydroxyl through sodium nitrite to obtain an alpha-hydroxy acid ester product, salifying with dicyclohexylamine, and reacting with trichloromethyl chloroformate as a cyclizing reagent and N, N-dimethylformamide to obtain the chemical fiber polyester composite yarn. The preparation method comprises the following steps: cyclizing by using N, N-diisopropylethylamine as a condensation catalyst to obtain a modified monomer with an anhydride structure in a carboxyl ring, carrying out ring-opening polymerization on the modified monomer and epoxy cyclohexane alkyl acid ester under the action of the catalyst to prepare modified master batches, mixing the modified master batches with polyester chips, carrying out melt spinning, stretching, and shaping to obtain the chemical fiber polyester composite yarn. The master batch is directly blended and modified, so that the hydrophilic property and the dyeability of the master batch are improved, and meanwhile, the mechanical property of the master batch is effectively maintained.

Description

Technical Field

[0001] The invention relates to the technical field of chemical fiber material preparation, and in particular to a preparation process of chemical fiber polyester composite yarn. Background Art

[0002] Polyester fiber is a synthetic fiber made of organic dibasic acid and diol by chemical polycondensation. It is a kind of polymer compound. Since the industrialization of polyester fiber, it has been widely used in sportswear, home textiles and other fields due to its good mechanical properties, high modulus, good wrinkle resistance and shape retention, excellent chemical resistance and many other advantages, becoming the largest variety of chemical synthetic fiber.

[0003] The "ester group" on the macromolecule of polyester fiber has the ability to absorb water. However, due to the steric hindrance effect of the benzene ring, the combination of the group and water is hindered. The molecular chains are arranged regularly, and it is difficult for water molecules to be enriched in the crystallization area, showing hydrophobic properties. The moisture regain of conventional polyester fiber under standard conditions (20℃, 65%RH) is only 0.4%, while the moisture regain of Cotton fiber is as high as 8.0%. When the relative humidity is 100%, the moisture regain of polyester fiber is only 0.6-0.8%. Therefore, in high humidity and high temperature environments, clothing made of this fiber will make people feel stuffy, lack good touch comfort, and have poor skin affinity. In addition, since polyester fiber lacks effective hydrophilic groups and the molecules are tightly stacked, it is difficult for dyes to enter the interior of the fiber, and the dyeability is poor. It is necessary to make the molecular chains of the fiber move violently after being heated under high temperature and high pressure conditions, and form large gaps between the molecular chains, so that the dye molecules can enter the fiber molecules to dye the fiber. Therefore, in response to application requirements, the direction of new polyester fiber product development is to modify polyester fibers through physical and chemical methods so that they can continuously be given new functions on the basis of good mechanical properties.

[0004] The existing modification method mainly improves hydrophilicity and dyeability by introducing comonomers, but conventional polyester chips themselves do not contain trimonomers and tetramonomers, and the chips need to be depolymerized into low molecular weight products and then copolymerized with the third monomer and the fourth monomer. Depolymerizing high molecular weight polyester into small molecules and then polymerizing them is technically difficult and significantly increases the cost. The addition of comonomers destroys the regularity of the molecular chain and increases the distance between macromolecules, reducing the intermolecular forces. Although the dyeability is improved, the mechanical properties are reduced. Summary of the invention

[0005] In view of the above problems, the present invention provides a process for preparing a chemical fiber polyester composite yarn.

[0006] The purpose of the present invention is achieved by the following technical solutions: A preparation process of chemical fiber polyester composite yarn comprises the following steps: (1) Masterbatch preparation S1, preparation of modified monomer, using L-glutamic acid-5-tert-butyl ester as raw material, converting amino group into hydroxyl group in the presence of sodium nitrite to obtain hydroxylation product; adding the hydroxylation product and dicyclohexylamine to an ether solvent cooled in an ice-water bath, mixing thoroughly, and reacting with stirring for 10-60 minutes, separating the precipitate while it is cold, washing with cold ether, and drying to obtain white dicyclohexylamine salt; weighing trichloromethyl chloroformate and dissolving it in ether solvent, adding N,N-diisopropylethylamine, and then adding the dicyclohexylamine salt, mixing thoroughly to obtain a suspension, stirring and reacting at room temperature for 3-6 hours, separating the precipitate, distilling off the solvent under reduced pressure from the filtrate, and washing with cyclohexane to obtain the modified monomer; S2, polymerization, under a protective atmosphere, dissolving the modified monomer in tetrahydrofuran solvent, adding 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate and 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester, fully mixing, adding a tetrahydrofuran solution of the catalyst, stirring and reacting at room temperature for 10-20 hours, separating the precipitate after the reaction is completed, concentrating the filtrate under reduced pressure, dissolving it in dichloromethane, adding methanol solvent until no precipitate is precipitated, separating the precipitate, washing, and drying to obtain a polymerization product, namely the masterbatch; (2) Pre-treatment The masterbatch and the polyester chips are dried at 100° C.-160° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with an additive, put into a melt spinning device for spinning, and air-cooled to form a composite fiber; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber.

[0007] In some preferred embodiments, the method for preparing the hydroxylated product comprises the following steps: Weigh L-glutamic acid-5-tert-butyl ester and disperse it in an aqueous solution of acetic acid. Slowly add a sodium nitrite solution while stirring in an ice-water bath. Then stir and react at room temperature for 2-4 hours. After the reaction is completed, add water to dilute the reaction system, extract with ethyl acetate, wash and dry the organic phase, concentrate under reduced pressure, and purify to obtain the hydroxylation product.

[0008] In some preferred embodiments, the mass ratio of the L-glutamic acid-5-tert-butyl ester to the sodium nitrite is 10:(6-7).

[0009] In some preferred embodiments, the mass ratio of the hydroxylation product to the dicyclohexylamine in step S1 is 10:(8.4-9.2).

[0010] In some preferred embodiments, the mass ratio of the trichloromethyl chloroformate to the N,N-diisopropylethylamine and the dicyclohexylamine salt in step S1 is 1:(1.8-2.4):(0.6-0.7).

[0011] In some preferred embodiments, the catalyst in step S2 is yttrium, tin or magnesium salt of hexamethyldisilazide.

[0012] In some preferred embodiments, the mass ratio of the modified monomer to the 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, the 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester, and the catalyst in step S2 is 10: (2.5-2.8): (3-4.2): (0.05-0.2).

[0013] In some preferred embodiments, the polyester chips are one or more of polyethylene terephthalate chips, polytrimethylene terephthalate, and polybutylene terephthalate.

[0014] In some preferred embodiments, the auxiliary agent in step (3) is one or more of fillers, matting agents, antistatic agents, antioxidants, antibacterial agents, dispersants, lubricants, and flame retardants; wherein, the addition of fillers can improve hardness and strength, and common oils include barium sulfate, silicon dioxide, titanium dioxide, calcium carbonate, etc.; the addition of matting agents can reduce light reflection and transmission, making the fiber softer and more textured, and common matting agents include PPG and PEG, etc.; antistatic agents reduce the surface charge density of fibers through adsorption and electrical neutralization, thereby eliminating static electricity and improving the feel and appearance of fibers. Common antistatic agents include amino silicone oil, anionic surfactants and metal ions, etc.; the addition of antioxidants can delay the aging process of polyester fibers and improve the stability and long-term durability of fibers. Common antioxidants include 168, 1010, BHT, AO-1 and AO-3, etc.; lubricants play a role in reducing friction and eliminating static electricity in the production process of polyester fibers, thereby improving the feel and appearance of fibers, and common lubricants include silicone oil, wax and esters, etc. ‌‌‌ In some preferred embodiments, the mixing mass ratio of the masterbatch, the polyester chips and the additives in step (3) is (6-18):100:(0-4).

[0015] The beneficial effects of the present invention are: In view of the problem that the existing polyester fiber modification technology is difficult and it is difficult to take into account its mechanical properties, the present invention provides a preparation process of chemical fiber polyester composite yarn, which improves its hydrophilicity and dyeability while effectively maintaining its mechanical properties by directly blending modified masterbatch; specifically, the present invention uses L-glutamic acid-5-tert-butyl ester as a raw material, first converts the amino group into a hydroxyl group by sodium nitrite to obtain an α-hydroxy acid ester product, and then forms a salt with dicyclohexylamine, and then uses trichloromethyl chloroformate as a cyclization reagent and N,N-diisopropylethylamine as a condensation catalyst to perform cyclization to obtain a hydroxyl group having The modified monomer of the carboxyl ring anhydride structure is then subjected to ring-opening polymerization with 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate and 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester under the action of a catalyst to obtain a polymerization product having a polyester structure, a polycarbonate structure and branched ester exchange cross-linking, which has good affinity with polyester. It is added as a blending masterbatch into polyester chips for spinning, which can effectively improve the hydrophilic hygroscopicity and dyeability of the spun fibers and their products, while maintaining their good mechanical properties. DETAILED DESCRIPTION

[0016] The present invention is further described in conjunction with the following examples. Example 1

[0017] This embodiment relates to a chemical fiber polyester composite yarn, and its preparation process includes the following steps: (1) Masterbatch preparation S1. Preparation of modified monomers Weigh L-glutamic acid-5-tert-butyl ester (CAS No.: 2419-56-9) and disperse it in an aqueous solution of acetic acid. Slowly add a sodium nitrite solution while stirring under an ice-water bath condition, and then stir and react for 3 hours at room temperature. After the reaction is completed, add water to dilute the reaction system, extract with ethyl acetate, wash and dry the organic phase, and concentrate it under reduced pressure. Then, put it into a silica gel column (500 mesh) to remove unreacted reactants, elute with dichloromethane / methanol / acetic acid (v / v / v=95 / 4.5 / 0.5), and evaporate the solvent to obtain the hydroxylation product; wherein the volume ratio of acetic acid to water in the aqueous solution of acetic acid is 1:4; the concentration of the sodium nitrite solution is 2 mol / L; the mass ratio of L-glutamic acid-5-tert-butyl ester to the sodium nitrite is 10:6.8; Add the hydroxylation product and dicyclohexylamine to an ether solvent cooled in an ice-water bath, mix thoroughly, and then stir and react for 30 minutes under heat preservation, separate the precipitate while it is cold, wash it with cold ether, and dry it to obtain a white dicyclohexylamine salt; the mass ratio of the hydroxylation product to the dicyclohexylamine is 10:8.9; Weigh trichloromethyl chloroformate and dissolve it in ether solvent, add N,N-diisopropylethylamine, then add the dicyclohexylamine salt, mix thoroughly to obtain a suspension, stir and react at room temperature for 4 hours, separate the precipitate, evaporate the solvent from the filtrate under reduced pressure, wash with cyclohexane to obtain the modified monomer; the mass ratio of the trichloromethyl chloroformate to the N,N-diisopropylethylamine and the dicyclohexylamine salt is 1:2.1:0.65; S2, Aggregation Under a protective atmosphere, the modified monomer was dissolved in tetrahydrofuran solvent, 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate (CAS No.: 18928-67-1) and 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester (CAS No.: 3775-95-9) were added, and after thorough mixing, a tetrahydrofuran solution of hexamethyldisilazide magnesium salt (50 mg / mL) was added, and the mixture was stirred at room temperature for 14 hours. After the reaction was completed, the precipitate was separated and filtered. The liquid is concentrated under reduced pressure and then dissolved in dichloromethane, methanol solvent is added until no precipitation is precipitated, the precipitate is separated, washed and dried to obtain a polymerization product, the weight average molecular weight Mw of the polymerization product is between 17 and 18 kDa, which is the masterbatch; the mass ratio of the modified monomer to the 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, the 4,5-oxy-bridged cyclohexane-1,2-dicarboxylic acid didecyl ester and the catalyst is 10:2.65:3.55:0.1; (2) Pre-treatment The masterbatch and the polyester chips are dried at 140° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; the polyester chips are polyethylene terephthalate chips; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with the antioxidant 1010, and then put into a melt spinning device for melt spinning at 220° C. The composite fiber is formed by air cooling; the mixing mass ratio of the masterbatch, the polyester chips and the antioxidant 1010 is 11:100:0.4; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber. Example 2

[0018] This embodiment relates to a chemical fiber polyester composite yarn, and its preparation process includes the following steps: (1) Masterbatch preparation S1. Preparation of modified monomers Weigh L-glutamic acid-5-tert-butyl ester (CAS No.: 2419-56-9) and disperse it in an aqueous solution of acetic acid. Slowly add a sodium nitrite solution while stirring under an ice-water bath condition, and then stir and react for 3 hours at room temperature. After the reaction is completed, add water to dilute the reaction system, extract with ethyl acetate, wash and dry the organic phase, and concentrate it under reduced pressure. Then, put it into a silica gel column (500 mesh) to remove unreacted reactants, elute with dichloromethane / methanol / acetic acid (v / v / v=95 / 4.5 / 0.5), and evaporate the solvent to obtain the hydroxylation product; wherein the volume ratio of acetic acid to water in the aqueous solution of acetic acid is 1:4; the concentration of the sodium nitrite solution is 2 mol / L; the mass ratio of L-glutamic acid-5-tert-butyl ester to the sodium nitrite is 10:6.8; Add the hydroxylation product and dicyclohexylamine to an ether solvent cooled in an ice-water bath, mix thoroughly, and then stir and react for 30 minutes under heat preservation, separate the precipitate while it is cold, wash it with cold ether, and dry it to obtain a white dicyclohexylamine salt; the mass ratio of the hydroxylation product to the dicyclohexylamine is 10:8.9; Weigh trichloromethyl chloroformate and dissolve it in ether solvent, add N,N-diisopropylethylamine, then add the dicyclohexylamine salt, mix thoroughly to obtain a suspension, stir and react at room temperature for 4 hours, separate the precipitate, evaporate the solvent from the filtrate under reduced pressure, wash with cyclohexane to obtain the modified monomer; the mass ratio of the trichloromethyl chloroformate to the N,N-diisopropylethylamine and the dicyclohexylamine salt is 1:2.4:0.6; S2, Aggregation Under a protective atmosphere, the modified monomer was dissolved in tetrahydrofuran solvent, 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate (CAS No.: 18928-67-1) and 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester (CAS No.: 3775-95-9) were added, and after thorough mixing, a tetrahydrofuran solution of hexamethyldisilazide magnesium salt (50 mg / mL) was added, and the mixture was stirred at room temperature for 14 hours. After the reaction was completed, the precipitate was separated. , the filtrate is concentrated under reduced pressure and then dissolved in dichloromethane, methanol solvent is added until no precipitation is precipitated, the precipitate is separated, washed and dried to obtain a polymerization product, the weight average molecular weight Mw of the polymerization product is between 17 and 18 kDa, which is the masterbatch; the mass ratio of the modified monomer to the 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, the 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester and the catalyst is 10:2.5:4:0.1; (2) Pre-treatment The masterbatch and the polyester chips are dried at 140° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; the polyester chips are polyethylene terephthalate chips; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with the antioxidant 1010, and then put into a melt spinning device for melt spinning at 220° C. The composite fiber is formed by air cooling; the mixing mass ratio of the masterbatch, the polyester chips and the antioxidant 1010 is 7:100:0.4; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber. Example 3

[0019] This embodiment relates to a chemical fiber polyester composite yarn, and its preparation process includes the following steps: (1) Masterbatch preparation S1, preparation of modified monomer, same as in Example 1; S2, polymerization, under a protective atmosphere, dissolving the modified monomer in tetrahydrofuran solvent, adding 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, adding tetrahydrofuran solution of hexamethyldisilazide magnesium salt (50 mg / mL) after sufficient mixing, stirring and reacting at room temperature for 14 hours, separating the precipitate after the reaction is completed, decompressing and concentrating the filtrate, dissolving it in dichloromethane, adding methanol solvent until no precipitate is precipitated, separating the precipitate, washing and drying to obtain a polymerization product, wherein the weight average molecular weight Mw of the polymerization product is between 16 and 17 kDa, which is the masterbatch; the mass ratio of the modified monomer to the 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate and the catalyst is 10:2.65:0.1; (2) Pre-treatment The masterbatch and the polyester chips are dried at 140° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; the polyester chips are polyethylene terephthalate chips; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with the antioxidant 1010, and then put into a melt spinning device for melt spinning at 220° C. The composite fiber is formed by air cooling; the mixing mass ratio of the masterbatch, the polyester chips and the antioxidant 1010 is 11:100:0.4; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber. Example 4

[0020] This embodiment relates to a chemical fiber polyester composite yarn, and its preparation process includes the following steps: (1) Masterbatch preparation S1, preparation of modified monomer, same as in Example 1; S2, polymerization, under a protective atmosphere, dissolving the modified monomer in tetrahydrofuran solvent, adding 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester, fully mixing, adding tetrahydrofuran solution of hexamethyldisilazide magnesium salt (50 mg / mL), stirring and reacting at room temperature for 14 hours, separating the precipitate after the reaction is completed, decompressing and concentrating the filtrate, dissolving it in dichloromethane, adding methanol solvent until no precipitate is precipitated, separating the precipitate, washing and drying to obtain a polymerization product, wherein the weight average molecular weight Mw of the polymerization product is between 16 and 17 kDa, which is the masterbatch; the mass ratio of the modified monomer to the 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester and the catalyst is 10:3.55:0.1; (2) Pre-treatment The masterbatch and the polyester chips are dried at 140° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; the polyester chips are polyethylene terephthalate chips; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with the antioxidant 1010, and then put into a melt spinning device for melt spinning at 220° C. The composite fiber is formed by air cooling; the mixing mass ratio of the masterbatch, the polyester chips and the antioxidant 1010 is 11:100:0.4; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber.

[0021] Comparison Example A chemical fiber polyester composite yarn, the preparation process of which comprises the following steps: (1) Pretreatment Drying the polyester chips at 140° C. to make the moisture content of the polyester chips less than 0.005%; the polyester chips are polyethylene terephthalate chips; (2) Melt spinning The dried polyester chips are mixed with the antioxidant 1010, put into a melt spinning device, melt-spinned at 220° C., and formed by air cooling to obtain composite fibers; the mixing mass ratio of the polyester chips to the antioxidant 1010 is 100:0.4; (3) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber.

[0022] Experimental example The hydrophilicity, dye uptake and mechanical properties of the composite fibers described in Examples 1-4 and the control example were tested. The process of the liquid water adsorption capacity test was to place the sample in a vacuum drying oven at 105°C for 48 hours for drying, weigh a sample weighing W1 and immerse it in deionized water for 24 hours, wipe the moisture on the surface of the sample with absorbent paper, and weigh the sample weight W2. The water absorption rate (WAC%) = (W2-W1) / W1×100%, and the average value of the three measured data was taken; the process of the gaseous water adsorption capacity test was to place the sample in a vacuum drying oven at 105°C for 48 hours for drying, weigh a sample weighing W1 and place it in a constant temperature and humidity chamber with a temperature of 20°C and a humidity of 65°C. RH%, weigh the sample weight W2 after 48 hours of equilibrium, gaseous moisture adsorption rate (MAC%) = (W2-W1) / W1×100%, and take the average of the three measured data; for the mechanical properties test, use a yarn length measuring instrument to wind the fiber 100 m, weigh the wound fiber, and repeat the test three times to get the average value. The linear density of the fiber is the measured value multiplied by 100, and the unit is decitex. The mechanical properties of the fiber are tested using a strength meter, the clamping distance is controlled to 250 mm, the tensile rate is 200 mm / min, the test pre-tension is 5 cN, and each group of fibers is repeated 20 times for effective testing and the average value is taken; the dyeing performance is expressed as the dyeing percentage, and the cationic pink X-FG dye is used to dye the fiber sample. The absorbance of the residual liquid after dyeing is tested using an ultraviolet spectrometer. The dyeing rate E=(1-A i ×N i / A0×N0)×100%, where A i is the absorbance of the residual solution; A0 is the absorbance of the original dye solution; N i is the dilution multiple of the residual solution; N0 is the dilution multiple of the original solution; the test results are as follows:

[0023] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A process for preparing a chemical fiber polyester composite yarn, characterized in that: The following steps are involved: (1) Masterbatch preparation S1, preparation of modified monomer, using L-glutamic acid-5-tert-butyl ester as raw material, converting amino group into hydroxyl group in the presence of sodium nitrite to obtain hydroxylation product; adding the hydroxylation product and dicyclohexylamine to an ether solvent cooled in an ice-water bath, mixing thoroughly, and reacting with stirring for 10-60 minutes, separating the precipitate while it is cold, washing with cold ether, and drying to obtain white dicyclohexylamine salt; weighing trichloromethyl chloroformate and dissolving it in ether solvent, adding N,N-diisopropylethylamine, and then adding the dicyclohexylamine salt, mixing thoroughly to obtain a suspension, stirring and reacting at room temperature for 3-6 hours, separating the precipitate, distilling off the solvent under reduced pressure from the filtrate, and washing with cyclohexane to obtain the modified monomer; S2, polymerization, under a protective atmosphere, dissolving the modified monomer in tetrahydrofuran solvent, adding 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate and 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester, fully mixing, adding a tetrahydrofuran solution of the catalyst, stirring and reacting at room temperature for 10-20 hours, separating the precipitate after the reaction is completed, concentrating the filtrate under reduced pressure, dissolving it in dichloromethane, adding methanol solvent until no precipitate is precipitated, separating the precipitate, washing, and drying to obtain a polymerization product, namely the masterbatch; (2) Pre-treatment The masterbatch and the polyester chips are dried at 100° C.-160° C. respectively, so that the moisture content of the masterbatch and the polyester chips is less than 0.005%; (3) Melt spinning The dried masterbatch and the polyester chips are mixed with an additive, put into a melt spinning device for spinning, and air-cooled to form a composite fiber; (4) Post-processing The chemical fiber polyester composite yarn is obtained by stretching and shaping the composite fiber.

2. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The preparation method of the hydroxylated product comprises the following steps: Weigh L-glutamic acid-5-tert-butyl ester and disperse it in an aqueous solution of acetic acid. Slowly add a sodium nitrite solution while stirring in an ice-water bath. Then stir and react at room temperature for 2-4 hours. After the reaction is completed, add water to dilute the reaction system, extract with ethyl acetate, wash and dry the organic phase, concentrate under reduced pressure, and purify to obtain the hydroxylation product.

3. The process for preparing a chemical fiber polyester composite yarn according to claim 2, characterized in that: The mass ratio of the L-glutamic acid-5-tert-butyl ester to the sodium nitrite is 10:(6-7).

4. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The mass ratio of the hydroxylation product to the dicyclohexylamine in step S1 is 10:(8.4-9.2).

5. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The mass ratio of the trichloromethyl chloroformate to the N,N-diisopropylethylamine and the dicyclohexylamine salt in step S1 is 1:(1.8-2.4):(0.6-0.7).

6. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The catalyst in step S2 is yttrium, tin or magnesium salt of hexamethyldisilazide.

7. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The mass ratio of the modified monomer to the 3,4-epoxy-6-methylcycloethylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, the 4,5-oxocyclohexane-1,2-dicarboxylic acid didecyl ester and the catalyst in step S2 is 10: (2.5-2.8): (3-4.2): (0.05-0.2).

8. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The polyester chips are one or more of polyethylene terephthalate chips, polypropylene terephthalate, and polybutylene terephthalate.

9. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: The auxiliary agent in step (3) is one or more of a filler, a matting agent, an antistatic agent, an antioxidant, an antibacterial agent, a dispersant, a lubricant, and a flame retardant.

10. The process for preparing a chemical fiber polyester composite yarn according to claim 1, characterized in that: In step (3), the mixing mass ratio of the masterbatch, the polyester chips and the auxiliary agent is (6-18):100:(0-4).

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