Preparation method of antibacterial polyester fiber

Abstract

The preparation method of the antibacterial polyester fiber comprises the following steps: firstly, reacting a cationic antibacterial agent with a terminal carboxyl group with 4-sulfobenzoic acid monopotassium salt to obtain a high-temperature-resistant polymerizable cationic antibacterial agent; then taking purified terephthalic acid, a high-temperature-resistant polymerizable cationic antibacterial agent and ethylene glycol as raw materials, adding an auxiliary agent trimethyl phosphate and a catalyst to prepare uniform slurry, and adding the uniform slurry into an esterification reaction kettle; entering a polycondensation stage after esterification is finished, filling nitrogen after reaction is finished, pressurizing, discharging, and performing underwater granulation to obtain antibacterial polyester chips; then, the antibacterial polyester chips are dried until the water content is lower than 30 ppm, and the antibacterial polyester fibers are obtained through the melt extrusion spinning step; the fiber strength of the prepared antibacterial polyester fiber is larger than or equal to 2.8 cN / dtex, the antibacterial rate meets the AAA grade standard, and the antibacterial polyester fiber has good strength and is wide in application range.

Description

Technical Field

[0001] The invention belongs to the technical field of antibacterial fibers, and in particular relates to a method for preparing antibacterial polyester fibers. Background Art

[0002] Antibacterial textile materials are mainly coated, impregnated, sprayed and other methods to make the fabric have antibacterial effect. Patent CN114318856B discloses an antibacterial fiber, preparation method and application, using the outer surface of the fiber for antibacterial coating, the antibacterial coating includes transition metal carbide and bismuth oxyhalide; the bismuth oxyhalide transition metal carbide coating is formed on the surface of the fabric fiber at room temperature. The antibacterial fiber has the defects of low firmness and poor washability.

[0003] There are two main antibacterial treatment methods for chemical fibers and regenerated fibers: preparation of antibacterial slices and addition of antibacterial agents during the spinning process. At present, the mature antibacterial polyester material achieves the antibacterial purpose through the migration of antibacterial agents. For example, patent CN112609260B discloses an antibacterial fiber material and its preparation process, specifically an antibacterial fiber material and its preparation process; in terms of weight, it is composed of the following raw materials: 100-120 parts of PET polyester chips and 3-6 parts of antibacterial masterbatch; the antibacterial masterbatch is composed of an appropriate amount of PET polyester chips and 6-10% of the antibacterial agent, 0.3-0.8% of the ultraviolet absorber, 0.2-0.6% of the antistatic agent, 0.6-1.8% of zinc stearate, 1.5-3.6% of sodium hypophosphite and 2.8-4.2% of 3-hydroxy 1,3,5-pentanetriolic acid; the fiber material prepared by the present invention adopts nano silver as the antibacterial agent, and is mixed into the antibacterial polyester in the fiber processing process by the masterbatch blending method, and the bactericidal effect is achieved by the sustained release of silver to the fiber surface. The antibacterial polyester prepared by this method gradually releases the antibacterial agent over time, and the antibacterial property gradually weakens, and a lasting antibacterial effect cannot be achieved.

[0004] Ordinary organic antimicrobial agents have the advantages of high efficiency, broad-spectrum antimicrobial, and designable structure, but organic antimicrobial agents generally have poor temperature resistance and are difficult to add through polymerization processes. The post-finishing process is to graft the antimicrobial agent to the surface of polyester fibers through chemical reactions. Usually, because polyester fibers have no reactive functional groups, reactive functional groups need to be introduced on the surface of polyester fibers through high-energy radiation and other methods, which will reduce the mechanical properties of the fibers. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing antibacterial polyester fiber.

[0006] The present invention adopts the following technical solution:

[0007] A method for preparing an antibacterial polyester fiber comprises the following steps:

[0008] Step 1, a cationic antibacterial agent having a terminal carboxyl group is subjected to cation exchange with 4-sulfobenzoic acid monopotassium salt in water to produce a white precipitate, which is then washed with water and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent;

[0009] Step 2, using purified terephthalic acid, a high temperature resistant polymerizable cationic antibacterial agent and ethylene glycol as raw materials, adding an auxiliary agent trimethyl phosphate and a catalyst, preparing a uniform slurry, adding the slurry to an esterification reactor, controlling the reactor pressure at 0.2-0.4 MPa, and the reaction temperature at 240-260° C.;

[0010] Step 3, after the esterification is completed, the condensation stage is entered, the pressure is reduced from normal pressure to an absolute pressure below 1KPa, the reaction temperature is controlled to 260-270°C, and the time is controlled to 40-60min; the vacuum is continued to be drawn to an absolute pressure below 50Pa, the reaction temperature is controlled to 270-285°C, and the end point of the condensation reaction is determined based on when the polymer viscosity reaches the target viscosity value. After the reaction is completed, nitrogen is charged, and the material is pressurized and discharged through underwater granulation to obtain antibacterial polyester chips;

[0011] Step 4, drying the antibacterial polyester chips until the moisture content is less than 30 ppm, and obtaining the antibacterial polyester fibers through a melt extrusion spinning step.

[0012] Furthermore, the preparation steps of the cationic antibacterial agent with a terminal carboxyl group are as follows: dissolving an acid and a compound with a long-chain alkyl group in an organic solvent, heating and refluxing, collecting the generated white precipitate, and then washing and drying to obtain the cationic antibacterial agent with a terminal carboxyl group.

[0013] Furthermore, the acid is p-chloromethylbenzoic acid, p-bromomethylbenzoic acid, chloroacetic acid, chloropropionic acid or bromoacetic acid.

[0014] Furthermore, the compound having a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, N,N-dimethylalkyl tertiary amine, tricyclohexylphosphine, triphenylphosphine, N-alkylimidazole, N,N-dimethylalkyl tertiary amine, alkylpiperazine, alkylmorpholine or alkylpiperidine.

[0015] Furthermore, the acid is p-chloromethylbenzoic acid, and the compound having a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, wherein the molar ratio of p-chloromethylbenzoic acid to N,N-dimethylhexadecyl tertiary amine is 1:1-2.

[0016] Furthermore, the organic solvent includes a mixture of one or more of ethyl acetate, tetrahydrofuran, acetone, petroleum ether and acetonitrile.

[0017] Furthermore, the parameters of the temperature-raising reflux treatment are as follows: reaction temperature 80-120° C., reaction time 4-12 h.

[0018] Furthermore, the catalyst is a composite of one or more of ethylene glycol antimony, antimony oxide, and antimony acetate.

[0019] Furthermore, the molar ratio of the high temperature resistant polymerizable cationic antibacterial agent to purified terephthalic acid is 3%:97%-10%:90%, the content of trimethyl phosphate is 0.03-0.05wt%, and the amount of the catalyst is 150-600ppm.

[0020] Furthermore, in step three, the intrinsic viscosity of the prepared antibacterial polyester chips is 0.65-0.70 dl / g.

[0021] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following beneficial effects:

[0022] First, the thermal decomposition temperature of the high temperature resistant polymerizable cationic antibacterial agent prepared by the present invention is higher than 300°C, and the preparation method is simple to operate, has high yield, and can be prepared on a large scale;

[0023] Second, compared with the polyester prepared by traditional blending, the antibacterial polyester fiber prepared by the present invention has long-lasting antibacterial effect, and the addition of the antibacterial agent will not affect the performance of the material, and the antibacterial agent has no dissolution effect, and has a high safety factor;

[0024] Third, the antibacterial polyester fiber prepared by the present invention has good strength and a wide range of applications;

[0025] Fourthly, the fiber strength of the antibacterial polyester fiber prepared by the present invention is ≥2.8 cN / dtex, and the antibacterial rate meets the AAA standard. DETAILED DESCRIPTION

[0026] The present invention is further described below through specific implementation modes.

[0027] A method for preparing an antibacterial polyester fiber comprises the following steps:

[0028] Step 1, a cationic antibacterial agent having a terminal carboxyl group is subjected to cation exchange with 4-sulfobenzoic acid monopotassium salt in water to produce a white precipitate, which is then washed with water and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent;

[0029] Step 2, using purified terephthalic acid, a high temperature resistant polymerizable cationic antibacterial agent and ethylene glycol as raw materials, adding an auxiliary agent trimethyl phosphate and a catalyst, preparing a uniform slurry, adding the slurry into an esterification reactor, controlling the pressure of the reactor at 0.2-0.4MPa, and controlling the reaction temperature at 240-260°C, wherein the end point of the esterification reaction is determined based on when the amount of esterification water reaches the theoretical calculation, and the calculation formula of the amount of esterification water is: esterification water (kg) = total molar number of acid components in the reaction system × 36 × 98%;

[0030] Step 3, after the esterification is completed, the condensation stage is entered, the pressure is reduced from normal pressure to an absolute pressure below 1KPa, the reaction temperature is controlled to 260-270°C, and the time is controlled to 40-60min; the vacuum is continued to be evacuated to an absolute pressure below 50Pa, the reaction temperature is controlled to 270-285°C, and the end point of the condensation reaction is determined based on when the polymer viscosity reaches the target viscosity value. After the reaction is completed, nitrogen is charged, and the material is pressurized and discharged through underwater granulation to obtain antibacterial polyester chips with an intrinsic viscosity of 0.65-0.70dl / g;

[0031] Step 4, drying the antibacterial polyester chips until the moisture content is less than 30 ppm, and obtaining the antibacterial polyester fibers through a melt extrusion spinning step.

[0032] In step 1, the preparation step of the cationic antibacterial agent with a terminal carboxyl group is as follows: dissolving an acid and a compound with a long-chain alkyl group in an organic solvent, refluxing for 4-12 hours at a temperature of 80-120° C., collecting the generated white precipitate, and then washing and drying to obtain a cationic antibacterial agent with a terminal carboxyl group, wherein the acid is p-chloromethylbenzoic acid, p-bromomethylbenzoic acid, chloroacetic acid, chloropropionic acid or bromoacetic acid; the compound with a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, N, N-dimethylalkyl tertiary amine, tricyclohexylphosphine, triphenylphosphine, N-alkylimidazole, N,N-dimethylalkyl tertiary amine, alkylpiperazine, alkylmorpholine or alkylpiperidine; the organic solvent includes a mixture of one or more of ethyl acetate, tetrahydrofuran, acetone, petroleum ether and acetonitrile; specifically, the acid is p-chloromethylbenzoic acid, the compound with a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, and the molar ratio of p-chloromethylbenzoic acid to N,N-dimethylhexadecyl tertiary amine is 1:1-2.

[0033] In step 2, the catalyst is a composite of one or more of ethylene glycol antimony, antimony oxide, and antimony acetate, and the molar ratio of the high temperature resistant polymerizable cationic antibacterial agent to purified terephthalic acid is 3%:97%-10%:90%, the content of trimethyl phosphate is 0.03-0.05wt%, and the amount of the catalyst is 150-600ppm.

[0034] Example 1

[0035] A method for preparing antibacterial polyester fiber, characterized in that it comprises the following steps:

[0036] Step 1, preparation of a high temperature resistant polymerizable cationic antibacterial agent: 1.70 kg of p-chloromethylbenzoic acid is dissolved in 20 kg of ethyl acetate, 2.8 kg of N, N-dimethylhexadecylamine is added under stirring, the temperature is raised to 80°C, refluxed and stirred for 12 hours, cooled to room temperature after the reaction is completed, filtered, the filter cake is washed with ethyl acetate for several times, and dried to obtain N-(4-carboxybenzyl)-N, N-dimethyldodecylammonium chloride; then 4.4 kg of N-(4-carboxybenzyl)-N, N-dimethylhexadecylammonium chloride is dissolved in 25 kg of deionized water, 3.1 kg of 4-sulfobenzoic acid monopotassium salt is added under stirring, and stirring is continued for 30 minutes, a large amount of white precipitate is produced, filtered, the filter cake is washed with water for several times, and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent;

[0037] Step 2, preparation of antibacterial polyester chips: 3.8 kg of purified terephthalic acid, 0.7 kg of the above-mentioned high temperature resistant cationic antibacterial agent and 1.9 kg of ethylene glycol, 0.76 g of trimethyl phosphate and 2.53 g of ethylene glycol antimony are added to form a uniform slurry, which is added to a reactor, and the air in the reaction device is replaced with nitrogen. The pressure of the reactor is controlled between 0.2 and 0.4 MPa, and the reaction temperature is controlled between 240 and 260° C. The reaction is fully reacted until no water is generated, so that the diol and the dibasic acid undergo esterification reaction to generate a low molecular weight polymer;

[0038] Step 3, polycondensation stage: reduce the vacuum degree in the reaction device by program control, from normal pressure to an absolute pressure below 1KPa, the time is controlled to 40min, the reaction temperature is controlled at 260°C, the vacuum is continued to be pumped to an absolute pressure below 100Pa, the reaction temperature is 270°C, the material is discharged under pressure, and underwater granulation is performed to obtain antibacterial polyester chips with an intrinsic viscosity of 0.65dL / g;

[0039] Step 4, spinning experiment: the antibacterial polyester chips are fully dried to a moisture content of less than 30 ppm, and the antibacterial polyester fibers are prepared by melt spinning.

[0040] Example 2

[0041] A method for preparing an antibacterial polyester fiber comprises the following steps:

[0042] Step 1, preparation of a high temperature resistant polymerizable cationic antibacterial agent: 1.70 kg of p-chloromethylbenzoic acid is dissolved in 30 kg of ethyl acetate, 3.5 kg of N-hexadecyl imidazole is added under stirring, the temperature is raised to 120° C., refluxed and stirred for 4 hours, cooled to room temperature after the reaction is completed, filtered, the filter cake is washed with ethyl acetate for several times, and dried to obtain N-(4-carboxybenzyl)-N-hexadecyl imidazole ammonium chloride; then 4.6 kg of N-(4-carboxybenzyl)-N-hexadecyl imidazole ammonium chloride is dissolved in 30 kg of deionized water, 3.1 kg of 4-sulfobenzoic acid monopotassium salt is added under stirring, stirring is continued for 30 minutes, a large amount of white precipitate is produced, filtered, the filter cake is washed with water for several times, and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent;

[0043] Step 2, preparation of antibacterial polyester pellets: 3.8 kg of purified terephthalic acid, 0.75 kg of the above-mentioned high temperature resistant cationic antibacterial agent and 1.9 kg of ethylene glycol, 0.76 g of trimethyl phosphate and 1.83 g of ethylene glycol antimony are added to form a uniform slurry, added to the reactor, the air in the reaction device is replaced with nitrogen, the pressure of the reactor is controlled between 0.2-0.4 MPa, the reaction temperature is controlled at 240-260 ° C, and the reaction is fully reacted until no water is generated, so that the diol and the dibasic acid undergo esterification reaction to generate a low molecular weight polymer;

[0044] Step 3, polycondensation: reducing the vacuum degree in the reaction device by program control, from normal pressure to an absolute pressure below 1 KPa, the time is controlled at 60 min, the reaction temperature is controlled at 270°C, the vacuum is continued to be pumped to an absolute pressure below 100 Pa, the reaction temperature is 285°C, the material is discharged under pressure, and underwater granulation is performed to obtain antibacterial polyester chips with an intrinsic viscosity of 0.70 dL / g;

[0045] Step 4, spinning experiment: the antibacterial polyester chips are fully dried to a moisture content of less than 30 ppm, and the antibacterial polyester fibers are prepared by melt spinning.

[0046] Example 3

[0047] A method for preparing an antibacterial polyester fiber comprises the following steps:

[0048] Step 1, preparation of a high temperature resistant polymerizable cationic antibacterial agent: 1.70 kg of p-chloromethylbenzoic acid is dissolved in 30 kg of ethyl acetate, 2.6 kg of triphenylphosphine is added under stirring, the temperature is raised to 88°C, refluxed and stirred for 9 hours, cooled to room temperature after the reaction is completed, filtered, the filter cake is washed with ethyl acetate for several times, and dried to obtain a quaternary phosphonium salt; then 4.3 kg of the quaternary phosphonium salt is dissolved in 28 kg of deionized water, 3.1 kg of 4-sulfobenzoic acid monopotassium salt is added under stirring, and stirring is continued for 30 minutes, a large amount of white precipitate is produced, filtered, the filter cake is washed with water for several times, and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent;

[0049] Step 2, preparation of antibacterial polyester pellets: 3.868 kg of purified terephthalic acid, 0.431 kg of the above-mentioned high temperature resistant cationic antibacterial agent and 1.95 kg of ethylene glycol, 0.76 g of trimethyl phosphate and 2.55 g of ethylene glycol antimony are added to form a uniform slurry, and after adding to the reactor, the air in the reaction device is replaced with nitrogen, the pressure of the reactor is controlled between 0.2-0.4 MPa, the reaction temperature is controlled at 240-260°C, and the reaction is fully reacted until no water is generated, so that the diol and the dibasic acid undergo esterification reaction to generate a low molecular weight polymer;

[0050] Step 3, polycondensation stage: reduce the vacuum degree in the reaction device by program control, from normal pressure to an absolute pressure below 1KPa, the time is controlled at 50min, the reaction temperature is controlled at 265°C, the vacuum is continued to be pumped to an absolute pressure below 100Pa, the reaction temperature is 275°C, the material is discharged under pressure, and underwater granulation is performed to obtain antibacterial polyester chips with an intrinsic viscosity of 0.66dL / g;

[0051] Step 4, spinning experiment: the antibacterial polyester chips are fully dried to a moisture content of less than 30 ppm, and the antibacterial polyester fibers are prepared by melt spinning.

[0052] Comparative Example 1

[0053] A method for preparing polyester fiber, characterized in that:

[0054] Step 1, preparation of common polyester: 4.0 kg of purified terephthalic acid and 1.9 kg of ethylene glycol are added with 0.76 g of trimethyl phosphate and 2.53 g of ethylene glycol antimony to form a uniform slurry, which is added to a reactor, and the air in the reaction device is replaced with nitrogen, the pressure of the reactor is controlled between 0.2-0.4 MPa, the reaction temperature is controlled between 240-260° C., and the reaction is fully reacted until no water is generated, so that the diol and the dibasic acid undergo an esterification reaction to generate a low molecular weight polymer;

[0055] Step 2, polycondensation stage, the vacuum degree in the reaction device is reduced by program control from normal pressure to an absolute pressure below 1 KPa, the time is controlled at 50 min, the reaction temperature is controlled at 265°C, the vacuum is continued to be pumped to an absolute pressure below 100 Pa, the reaction temperature is 275°C, the material is discharged under pressure, and underwater granulation is performed to obtain ordinary polyester chips with an intrinsic viscosity of 0.66 dL / g;

[0056] Step 3, spinning experiment: the polyester chips prepared above are fully dried to a moisture content of less than 30 ppm, added to a spinning machine, and melt-spinned to obtain polyester fibers.

[0057] Examples 1 to 3 and Comparative Example 1 were tested, and the specific test results are shown in the following table, wherein the main test methods are as follows:

[0058] (1) Intrinsic viscosity of polyester pellets: GB / T 14190-2017;

[0059] (2) Fiber strength: GB / T 8960-2015;

[0060] (3) Antibacterial properties: FZ / T 73023-2006;

[0061] Main test results:

[0062] Table 1 Fiber strength of antibacterial polyester fibers

[0063]

[0064]

[0065] The results of single fiber strength test show that the addition of antibacterial agent has little effect on the strength of the fiber. The prepared high-temperature resistant polymerizable cationic antibacterial agent contains two carboxyl groups. The carboxyl groups participate in the reaction during the polymerization process and are evenly distributed in the polyester. Therefore, the effect on the strength of the fiber is not obvious.

[0066] Table 2 Antibacterial properties of antibacterial polyester fibers before and after washing

[0067]

[0068] Table 3 Standard indicators of antibacterial rate of antibacterial knitwear

[0069]

[0070] It can be seen from Tables 2 and 3 that the high temperature resistant polymerizable antibacterial agent is introduced into the polyester structure by copolymerization, and a fiber with excellent antibacterial properties can be obtained by melt spinning. The cationic antibacterial agent is typed into the molecular chain by copolymerization, and has excellent washing resistance. After 50 times of washing, its antibacterial rate is close to that before washing, and the antibacterial level is AAA.

[0071] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of implementation of the present invention. That is, equivalent changes and modifications made according to the application scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing an antibacterial polyester fiber, characterized in that: The following steps are involved: Step 1, a cationic antibacterial agent having a terminal carboxyl group is subjected to cation exchange with 4-sulfobenzoic acid monopotassium salt in water to produce a white precipitate, which is then washed with water and dried to obtain a high temperature resistant polymerizable cationic antibacterial agent; Step 2, using purified terephthalic acid, a high temperature resistant polymerizable cationic antibacterial agent and ethylene glycol as raw materials, adding an auxiliary agent trimethyl phosphate and a catalyst, preparing a uniform slurry, adding the slurry to an esterification reactor, controlling the reactor pressure at 0.2-0.4 MPa, and the reaction temperature at 240-260° C.; Step 3, after the esterification is completed, the condensation stage is entered, the pressure is reduced from normal pressure to an absolute pressure below 1KPa, the reaction temperature is controlled to 260-270°C, and the time is controlled to 40-60min; the vacuum is continued to be drawn to an absolute pressure below 50Pa, the reaction temperature is controlled to 270-285°C, and the end point of the condensation reaction is determined based on when the polymer viscosity reaches the target viscosity value. After the reaction is completed, nitrogen is charged, and the material is pressurized and discharged through underwater granulation to obtain antibacterial polyester chips; Step 4, drying the antibacterial polyester chips until the moisture content is less than 30 ppm, and obtaining the antibacterial polyester fibers through a melt extrusion spinning step.

2. The method for preparing an antibacterial polyester fiber according to claim 1, characterized in that: The preparation steps of the cationic antibacterial agent with a terminal carboxyl group are as follows: dissolving an acid and a compound with a long-chain alkyl group in an organic solvent, heating and refluxing the mixture, collecting the generated white precipitate, and then washing and drying the precipitate to obtain the cationic antibacterial agent with a terminal carboxyl group.

3. The method for preparing an antibacterial polyester fiber according to claim 2, characterized in that: The acid is p-chloromethylbenzoic acid, p-bromomethylbenzoic acid, chloroacetic acid, chloropropionic acid or bromoacetic acid.

4. The method for preparing an antibacterial polyester fiber according to claim 3, characterized in that: The compound having a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, N,N-dimethylalkyl tertiary amine, tricyclohexylphosphine, triphenylphosphine, N-alkylimidazole, N,N-dimethylalkyl tertiary amine, alkylpiperazine, alkylmorpholine or alkylpiperidine.

5. The method for preparing an antibacterial polyester fiber according to claim 4, characterized in that: The acid is p-chloromethylbenzoic acid, and the compound having a long-chain alkyl group is N,N-dimethylhexadecyl tertiary amine, wherein the molar ratio of p-chloromethylbenzoic acid to N,N-dimethylhexadecyl tertiary amine is 1:1-2.

6. The method for preparing an antibacterial polyester fiber according to claim 2, characterized in that: The organic solvent comprises a mixture of one or more of ethyl acetate, tetrahydrofuran, acetone, petroleum ether and acetonitrile.

7. The method for preparing an antibacterial polyester fiber according to claim 2, characterized in that: The parameters of the temperature reflux treatment are as follows: reaction temperature 80-120°C, reaction time 4-12h.

8. The method for preparing an antibacterial polyester fiber according to claim 1, characterized in that: The catalyst is a composite of one or more of ethylene glycol antimony, antimony oxide and antimony acetate.

9. The method for preparing an antibacterial polyester fiber according to claim 1, characterized in that: The molar ratio of the high temperature resistant polymerizable cationic antibacterial agent to purified terephthalic acid is 3%:97%-10%:90%, the content of trimethyl phosphate is 0.03-0.05wt%, and the dosage of the catalyst is 150-600ppm.

10. The method for preparing an antibacterial polyester fiber according to claim 1, characterized in that: In step 3, the intrinsic viscosity of the prepared antibacterial polyester chips is 0.65-0.70 dl / g.

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