A method for preparing antibacterial and degradable spandex

Abstract

The present invention provides a method for preparing antibacterial and degradable spandex, specifically: polyether polyol and 4,4-diphenylmethane diisocyanate are mixed together in a ratio of 1:1.6 to 1.9 in terms of the amount of substance, and a polymerization reaction is performed to obtain a NCO-terminated prepolymer, and then N,N-dimethylacetamide solvent is added to fully dissolve the prepolymer to obtain a prepolymer solution; a quaternary ammonium salt chain extender, an amine chain extender, and a chain terminator are added to the prepolymer solution obtained in step 1 in order to perform a chain extension reaction and a termination reaction to obtain an antibacterial spandex spinning stock solution, and dry spinning is performed in a high-temperature tunnel after aging to obtain antibacterial spandex, and the temperature of the tunnel is set to 180°C to 270°C. The spandex prepared by the present invention not only has antibacterial properties, but also can be degraded in a humid environment. It is suitable for the fields of disposable diapers, bandages, wet wipes, disposable underwear, masks, etc.

Description

Technical Field

[0001] The invention discloses a method for preparing spandex fiber with high ductility and elasticity, in particular to a method for preparing antibacterial and degradable spandex. Background Art

[0002] As an elastic fiber, spandex is widely used in textile fabrics, medical bandages, health care products, automotive interiors, leisure sports equipment, etc. due to its high ductility and high elasticity. Different application fields have different performance requirements for spandex. Among them, spandex with antibacterial properties can inhibit the growth of bacteria on its surface, especially in hot and humid environments, and can effectively keep the fabric clean, making it an indispensable part of many sanitary products. In actual use, most sanitary products, such as diapers, bandages, wet wipes, disposable underwear, and masks, are often discarded after use. Ordinary spandex is basically difficult to degrade in the soil due to its dense hard segment structure and poor hydrophilicity, and becomes part of white garbage. Therefore, it is necessary to make spandex degradable on the basis of antibacterial properties, so as to achieve a balance between the antibacterial and environmental protection properties of spandex.

[0003] Quaternary ammonium salt antibacterial agent has a series of advantages such as remarkable bactericidal effect, safety, low toxicity, and environmental friendliness, and is widely studied for use in antibacterial polyurethane. At present, the antibacterial spandex equipped with quaternary ammonium salt is mainly divided into the following two types: immersion type loading and covalent bond loading. The immersion type loading is generally to blend the solvent containing the quaternary ammonium salt antibacterial agent with the polyurethane stock solution, and then obtain the polyurethane fiber with antibacterial effect through dry spinning or melt spinning. In this way, the antibacterial spandex is prepared, and the quaternary ammonium salt is basically adsorbed on the spandex molecular chain by the mode of electrostatic action and hydrogen bond. For example, in patent CN114892294A, the quaternary ammonium salt and the hydrogen bond donor are dissolved in an organic solvent, and then mixed evenly with the polyurethane stock solution, and finally the polyurethane fiber with antibacterial effect is prepared by dry spinning. The antibacterial spandex prepared in this way is low in cost and has a wide range of quaternary ammonium antibacterial agents. However, the quaternary ammonium salt small molecules in the spandex have poor thermal stability and are easily desorbed, resulting in a short product shelf life and poor heat resistance. During use, they may remain on the surface of the contact object, which has potential safety hazards; the covalent bond type load is usually to connect the quaternary ammonium salt group with the macromolecular segment in the spandex through a covalent bond. For example, in patent CN115652473A, the quaternary ammonium salt group is connected to cellulose through a covalent bond, and then blended with the spandex stock solution to obtain a spandex with a lasting antibacterial effect, safe, low toxicity and good thermal stability. Compared with the immersion type load, the preparation cost of the covalent bond type load is improved. After the quaternary ammonium salt group is connected to the macromolecular segment through a covalent bond, the heat resistance of the quaternary ammonium salt in the antibacterial spandex can be improved, and the connection between the molecular chain is also more solid, so the heat resistance and stability of the covalent bond load product are often better than the immersion type.

[0004] As society pays more and more attention to the environmental protection requirements of disposable consumer products, people are also paying more attention to the impact of products containing spandex on the environment after they are discarded. The antibacterial spandex mentioned at present often only focuses on its antibacterial effect, but fails to take into account whether the spandex can be degraded after being discarded. Summary of the invention

[0005] Technical problem: The purpose of the present invention is to provide a method for preparing antibacterial and degradable spandex. The antibacterial and degradable spandex prepared by this method has a higher operating temperature, a longer effective antibacterial time, and no residue during use, making the difficult-to-degrade polyurethane fiber degradable and safer, meeting people's needs for disposable diapers, bandages, wet wipes, disposable underwear, masks, etc. that require both antibacterial and degradable properties.

[0006] Technical solution: The present invention provides a method for preparing antibacterial degradable spandex, which specifically comprises the following steps:

[0007] Step 1: Mixing polyether polyol and 4,4-diphenylmethane diisocyanate at a molar ratio of 1:1.6 to 1.9 to carry out polymerization reaction to obtain a -NCO-terminated prepolymer, and then adding N,N-dimethylacetamide solvent to fully dissolve the prepolymer to obtain a prepolymer solution;

[0008] Step 2: adding a quaternary ammonium salt chain extender, an amine chain extender, and a chain terminator to the prepolymer solution obtained in step 1 in order to perform a chain extension reaction and a termination reaction to obtain an antibacterial spandex spinning stock solution;

[0009] Step 3: After the antibacterial spandex spinning solution obtained in step 2 is matured, dry spinning is performed in a high-temperature tunnel to obtain antibacterial spandex. The temperature of the tunnel is set to 180°C to 270°C, preferably 240°C to 250°C.

[0010] in,

[0011] The polyether polyol described in step 1 includes one or more of polyethylene oxide and polytetrahydrofuran.

[0012] The polymerization reaction in step 1 has a polymerization temperature of 50 to 90° C. and a polymerization time of 60 to 90 min.

[0013] The quaternary ammonium salt chain extender described in step 2 includes the following formula 1:

[0014]

[0015] The amount ratio of the added amount of the quaternary ammonium salt chain extender to the amount of the 4,4-diphenylmethane diisocyanate described in step 1 is 1:5-20.

[0016] The amine chain extender described in step 2 includes one or more of 1,2-ethylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, and 1,5-pentanediamine.

[0017] The amount ratio of the quaternary ammonium salt chain extender and the amine chain extender added in step 2 to the amount of 4,4-diphenylmethane diisocyanate added in step 1 is 1:1.8-3.0, preferably 1:1.8-2.5.

[0018] The chain terminator in step 2 includes one or more of a quaternary ammonium salt terminator, diethylamine, dipropylamine, and cyclohexylamine as shown in Formula 2.

[0019]

[0020] The molar ratio of the chain terminator added in step 2 to the 4,4-diphenylmethane diisocyanate in step 1 is 1:10 to 50, preferably 1:15 to 40.

[0021] In the step 2, the quaternary ammonium salt chain extender, the amine chain extender and the chain terminator are added to the prepolymer solution obtained in the step 1 in sequence, and the feeding time interval is not less than 10 minutes.

[0022] The antibacterial and degradable spandex is used in the field of disposable products with antibacterial requirements, such as disposable diapers, bandages, wet wipes, disposable underwear and masks.

[0023] The principle is to introduce a cyclic chain extender with a quaternary ammonium salt group. The antibacterial effect of the quaternary ammonium salt gives spandex antibacterial properties. At the same time, compared with short-chain chain extenders, long-chain cyclic chain extenders can effectively reduce the crystallinity of the hard segment on the spandex molecular chain, making it easier for the quaternary ammonium salt to migrate to the surface to exert its antibacterial properties. The introduction of charged quaternary ammonium salt chain extenders can change the surface properties of polyurethane and significantly improve the hydrophilicity of the chain segment. The long-chain cyclic chain extender can reduce the crystallinity of the hard segment. The two together promote the hydrolysis of the polyurethane molecular chain. To further improve the antibacterial and degradable properties, a tetrahydropyrrole derivative can be introduced as a capping agent.

[0024] Beneficial effect: The advantages of the present invention are:

[0025] Compared with the immersed antibacterial polyurethane fiber, the antibacterial polyurethane fiber that introduces quaternary ammonium salt cations into the main chain has a higher operating temperature, a longer effective antibacterial time, and no residue during use, making it safer.

[0026] The introduction of a long-chain cyclic structured chain extender reduces the crystallinity of the hard segment of the polyurethane fiber, making it easier for the quaternary ammonium salt to migrate to the surface, thus better exerting the antibacterial effect.

[0027] Introducing a long-chain cyclic quaternary ammonium salt cationic chain extender into the main chain can improve the hydrophilicity of the polyurethane fiber surface, reduce the crystallinity of the polyurethane fiber, and make the difficult-to-degrade polyurethane fiber degradable. DETAILED DESCRIPTION

[0028] The method for preparing spandex with antibacterial and degradable properties provided by the present invention comprises the following specific steps:

[0029] Step 1: Mixing polyether polyol and 4,4-diphenylmethane diisocyanate at a molar ratio of 1:1.6 to 1.9 to carry out polymerization reaction to obtain a -NCO-terminated prepolymer, and then adding N,N-dimethylacetamide solvent to fully dissolve the prepolymer;

[0030] Step 2: adding a quaternary ammonium salt chain extender, an amine chain extender, and a chain terminator to the prepolymer solution obtained in step 1 in this order to perform a chain extension reaction and a termination reaction to obtain an antibacterial spandex spinning stock solution;

[0031] Step 3: After the antibacterial spandex spinning solution obtained in step 2 is matured, dry spinning is performed in a high-temperature tunnel to obtain antibacterial spandex. The temperature of the tunnel is set to 180°C to 270°C, preferably 240°C to 250°C.

[0032] in,

[0033] The chain extender described in step 2 includes a quaternary ammonium salt chain extender, and the amount of the quaternary ammonium salt chain extender added is in a molar ratio of 1:5 to 20 to the amount of 4,4-diphenylmethane diisocyanate described in step 1.

[0034] The invention imparts antibacterial property and degradability to the polyurethane fiber by introducing a cyclic chain extender with a quaternary ammonium salt group. The quaternary ammonium salt group on the chain extender has an antibacterial effect and carries a positive charge, which can improve the surface hydrophilicity of the spandex. The cyclic structure can reduce the hard segment crystallinity, which is conducive to the migration of the quaternary ammonium salt group to the surface, improves the antibacterial property, and also makes the spandex easy to hydrolyze. By introducing a tetrahydropyrrole derivative, the content of the quaternary ammonium salt and the surface hydrophilicity of the spandex can be further improved, the hard segment crystallinity can be reduced, and the antibacterial property and degradability of the polyurethane fiber can be enhanced.

[0035] Furthermore, the polyether polyol in step 1 includes one or more of polyethylene oxide and polytetrahydrofuran.

[0036] Furthermore, the polymerization temperature of step 1 is 50-90° C., and the polymerization time is 60-90 min.

[0037] Furthermore, the chain extender in step 2 further comprises one or more of 1,2-ethylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, and 1,5-pentanediamine.

[0038] Preferably, the quaternary ammonium salt chain extender described in step 2 is a cyclic quaternary ammonium salt chain extender.

[0039] Furthermore, the amount ratio of the chain extender added in step 2 to the amount of 4,4-diphenylmethane diisocyanate in step 1 is 1:1.8-3.0, preferably 1:1.8-2.5.

[0040] Furthermore, the terminator in step 2 further comprises one or more of a quaternary ammonium salt terminator, diethylamine, dipropylamine, and cyclohexylamine.

[0041] Preferably, the quaternary ammonium salt terminator in step 2 can be a cyclic quaternary ammonium salt terminator.

[0042] Furthermore, the molar ratio of the amount of the terminator added in step 2 to the amount of 4,4-diphenylmethane diisocyanate in step 1 is 1:10 to 50, preferably 1:15 to 40.

[0043] Furthermore, when the quaternary ammonium salt terminator is added to the prepolymer solution obtained in step 1, it should be added in the order of quaternary ammonium salt chain extender, amine chain extender, quaternary ammonium salt chain terminator, and amine terminator.

[0044] Preferably, the terminator in step 2 further comprises a quaternary ammonium salt terminator, and the molar ratio of the quaternary ammonium salt terminator to the 4,4-diphenylmethane diisocyanate in step 1 is 1:20-100.

[0045] Furthermore, the time interval for adding the quaternary ammonium salt chain extender, the amine chain extender, the quaternary ammonium salt chain terminator and the amine terminator to the prepolymer solution obtained in step 1 in this order is not less than 10 minutes, preferably 20 minutes.

[0046] The antibacterial and degradable spandex prepared by the present invention can be used in the field of disposable products with antibacterial requirements, such as disposable diapers, bandages, wet wipes, disposable underwear, masks, etc.

[0047] The quaternary ammonium salt chain extender includes the following formula 1:

[0048]

[0049] The chain terminator includes one or more of a quaternary ammonium salt terminator, diethylamine, dipropylamine, and cyclohexylamine as shown in Formula 2 below:

[0050]

[0051] Embodiment 1

[0052] 628 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 453.75 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 60°C for 80 minutes, and the PPS was transferred to the chain extension reactor (RA2). 1000 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10°C, 4.94 kg of piperazine derivatives represented by formula 1 (I), 8.4 kg of ethylenediamine, 1.52 kg of tetrahydropyridine derivatives represented by formula 2 (IX), and 1.24 kg of diethylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction, and each additive was stirred for 20 minutes after being added before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 20 hours and then dry-spun. Then, it is oiled and wound to obtain antibacterial and degradable spandex 1.

[0053] Embodiment 2

[0054] 692 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 417 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 55°C for 80 minutes, and the PPS was transferred to the chain extension reactor (RA2). 800 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10°C, 6.05 kg of piperazine derivatives represented by formula 1 (II), 11.84 kg of 1,2-propylenediamine, 1.212 kg of tetrahydropyridine derivatives represented by formula 2 (IX), and 1.022 kg of diethylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 22 hours and then dry-spun, and then oiled and wound to obtain antibacterial and biodegradable spandex 2.

[0055] Embodiment 3

[0056] 528.5 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 382.1 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 50°C for 90 minutes, and the PPS was transferred to the chain extension reactor (RA2). 600 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 20°C, 11.45 kg of piperazine derivatives represented by formula 1 (III), 11.82 kg of 1,2-ethylenediamine, 1.1 kg of tetrahydropyridine derivatives represented by formula 2 (X), and 1.343 kg of dipropylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 25 hours and then dry-spun. After oiling and winding, the antibacterial and degradable spandex 3 is obtained.

[0057] Embodiment 4

[0058] 641.9 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 427.1 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 65°C for 70 minutes. The PPS was transferred to the chain extension reactor (RA2). 900 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10°C, 10.23 kg of piperazine derivatives represented by formula 1 (IV), 14.06 kg of 1,2-propylenediamine, 2.34 kg of tetrahydropyridine derivatives represented by formula 2 (XI), and 1.35 kg of cyclohexylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 22 hours and then dry-spun. After oiling and winding, the antibacterial and degradable spandex 4 is obtained.

[0059] Embodiment 5

[0060] 549.9 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 399.3 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 55°C for 80 minutes. The PPS was transferred to the chain extension reactor (RA2). 700 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10°C, 16.84 kg of piperazine derivatives represented by formula 1 (V), 7.04 kg of 1,4-butanediamine, 1.084 kg of tetrahydropyridine derivatives represented by formula 2 (XII), and 0.681 kg of diethylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 26 hours and then dry-spun, and then oiled and wound to obtain antibacterial and biodegradable spandex 5.

[0061] Embodiment 6

[0062] 579.7 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 383 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 50°C for 80 minutes, and the PPS was transferred to the chain extension reactor (RA2). 600 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10°C, 15.98 kg of piperazine derivatives represented by formula 1 (VI), 6 kg of 1,2-ethylenediamine, 1.131 kg of tetrahydropyridine derivatives represented by formula 2 (XI), and 1.139 kg of diethylamine were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 26 hours and then dry-spun. After oiling and winding, the antibacterial and biodegradable spandex 6 is obtained.

[0063] Embodiment 7

[0064] 630 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 453.75 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained at 65°C for 90 minutes. The PPS was transferred to the chain extension reactor (RA2). 1000 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 20°C, 12.64 kg of the piperazine derivative shown in formula 1 (VII), 16.32 kg of 1,5-pentanediamine, and 4.112 kg of the tetrahydropyridine derivative shown in formula 2 (XI) were added to RA2 in sequence to carry out chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction is completed, the obtained polymer is transferred into D-FETK for aging for 20 hours and then dry-spun. After oiling and winding, the antibacterial and biodegradable spandex 7 is obtained.

[0065] Embodiment 8

[0066] 592 kg of solvent dimethylacetamide (DMAC) was added to the reactor (RA1), stirring was started, and then 399.3 kg of polytetrahydrofuran ether glycol and 100 kg of diphenylmethane diisocyanate were added to RA1, and the prepolymer PPS was obtained by reacting at 50 ° C for 80 min, and the PPS was transferred to the chain extension reactor (RA2). 750 kg of cleaned DMAC was added to RA1, and the cleaned DMAC was transferred to RA2, stirring was started, and when the temperature of RA2 was cooled to about 10 ° C, 27.52 kg of piperazine derivatives shown in formula 1 (VIII), 8.52 kg of 1,2-ethylenediamine, and 1.46 kg of diethylamine were added to RA2 in sequence for chain extension reaction and chain termination reaction. After each additive was added, it was stirred for 20 minutes before adding the next additive. After the reaction was completed, the obtained polymer was transferred to D-FETK for aging for 28 hours and then dry-spun, and then oiled and wound to obtain antibacterial and degradable spandex 8.

[0067] Comparative Example 1

[0068] Add 677.25kg of solvent dimethylacetamide (DMAC) to the reactor (RA1), start stirring, then add 453.75kg of polytetrahydrofuran ether glycol and 100kg of diphenylmethane diisocyanate to RA1, react at 50°C for 90min to obtain prepolymer PPS, and transfer PPS to the chain extension reactor (RA2). Add 900kg of clean DMAC to RA1, transfer the clean DMAC to RA2, start stirring, and when the temperature of RA2 cools to about 10°C, add 13.33kg of 1,2-ethylenediamine and 0.73kg of diethylamine to RA2 in sequence for chain extension reaction and chain termination reaction. After each additive is added, stir for 20 minutes before adding the next additive. After the reaction is completed, the resulting polymer is transferred to D-FETK for aging for 24h and then dry-spun, and then oiled and wound to obtain ordinary spandex 1.

[0069] Hydrophilicity test: The spandex antibacterial fiber was made into a 5cm×5cm fiber membrane, immersed and washed in distilled water for 24 hours, and then dried and the surface water contact angle of the spandex was measured using a contact angle meter.

[0070]

[0071]

[0072] The contact angle test shows that the hydrophilicity of the polyurethane fiber surface is significantly improved after the introduction of the cyclic quaternary ammonium salt chain extender.

[0073] Degradability test: Water degradation test was conducted in a buffer solution at pH 7 at 37°C. The spandex yarn was first degreased, and then 0.01 g of the sample was weighed and placed in 10 mL of buffer solution and soaked for 15 weeks. The remaining solid was taken out, washed, dried, and the remaining solid mass was weighed. Degradation rate = (initial sample mass - remaining solid mass) / initial sample mass.

[0074]

[0075] After the biodegradability test, it can be seen that the antibacterial and biodegradable spandex can be degraded in a humid environment.

[0076] Antibacterial test: The spandex fibers of the examples and comparative examples were made into fiber membranes with a diameter of 1 cm, and then soaked and washed in distilled water for 24 hours; then each fiber membrane was added to the nutrient broth, and 10 6 CFU / mL of bacterial suspension (Escherichia coli and Staphylococcus aureus were tested respectively) were incubated at 37°C for 6h.

[0077] The bacterial suspension after cultivation in each group was applied on the surface of the agar medium and cultured in a constant temperature box at 37°C for 24 hours. The number of colonies was determined after cultivation, and the inhibition rate was calculated. Inhibition rate = (the number of colonies in the comparative example group - the number of colonies in the example group) / the number of colonies in the comparative example group.

[0078]

[0079] It can be seen from the antibacterial test that the antibacterial property of polyurethane fiber with quaternary ammonium salt structure can reach more than 99.7%.

Claims

1. A method for preparing antibacterial degradable spandex, characterized in that: The preparation method specifically comprises the following steps: Step 1: Mixing polyether polyol and 4,4-diphenylmethane diisocyanate at a molar ratio of 1:1.6 to 1.9 to carry out polymerization reaction to obtain a -NCO-terminated prepolymer, and then adding N,N-dimethylacetamide solvent to fully dissolve the prepolymer to obtain a prepolymer solution; Step 2: adding a quaternary ammonium salt chain extender, an amine chain extender, and a chain terminator to the prepolymer solution obtained in step 1 in order to perform a chain extension reaction and a termination reaction to obtain an antibacterial spandex spinning stock solution; Step 3: After the antibacterial spandex spinning solution obtained in step 2 is aged, dry spinning is performed in a high-temperature tunnel to obtain antibacterial spandex, and the temperature of the tunnel is set to 180° C. to 270° C.; in, The polyether polyol described in step 1 includes one or more of polyethylene oxide and polytetrahydrofuran; The polymerization reaction in step 1, the polymerization temperature is 50-90°C, and the polymerization time is 60-90min; The quaternary ammonium salt chain extender described in step 2 includes the following formula 1: The amount ratio of the added amount of the quaternary ammonium salt chain extender to the amount of the 4,4-diphenylmethane diisocyanate described in step 1 is 1:5 to 20.

2. The method for preparing the antibacterial degradable spandex according to claim 1, characterized in that: The amine chain extender described in step 2 includes one or more of 1,2-ethylenediamine, 1,2-propylenediamine, 1,4-butylenediamine, and 1,5-pentanediamine.

3. The method for preparing the antibacterial degradable spandex according to claim 1, characterized in that: The amount ratio of the quaternary ammonium salt chain extender and the amine chain extender added in step 2 to the amount of 4,4-diphenylmethane diisocyanate added in step 1 is 1:1.8-3.

0.

4. The method for preparing the antibacterial degradable spandex according to claim 1, characterized in that: The chain terminator in step 2 includes one or more of a quaternary ammonium salt terminator, diethylamine, dipropylamine, and cyclohexylamine as shown in Formula 2.

5. The method for preparing the antibacterial degradable spandex according to claim 4, characterized in that: The amount ratio of the chain terminator added in step 2 to the 4,4-diphenylmethane diisocyanate in step 1 is 1:10 to 50.

6. The method for preparing the antibacterial degradable spandex according to claim 5, characterized in that: In the step 2, the quaternary ammonium salt chain extender, the amine chain extender and the chain terminator are added to the prepolymer solution obtained in the step 1 in sequence, and the feeding time interval is not less than 10 minutes.

7. An antibacterial degradable spandex prepared by the method of claim 1, characterized in that: The antibacterial and degradable spandex is used in the field of disposable products with antibacterial requirements, such as disposable diapers, bandages, wet wipes, disposable underwear and masks.

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