An antibacterial nylon 6 material, its preparation method and application

Abstract

An antibacterial nylon 6 material, its preparation method, and its application are disclosed, relating to the field of nylon material technology, and solving the problem of balancing antibacterial and mechanical properties of nylon. The material has the structure of formula (I), where each R1 and R2 is independently selected from C. 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon group / C 6～18 Aryl / C 7～30 One of the aralkyl groups, or R1 and R2 on the same N forming a 5- to 7-membered saturated / unsaturated heterocycle with the attached N; each E ‑ The functional groups are independently selected from general structural formula (II). Each R3 is independently selected from C. 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon group / C 6～18 Aryl / C 7～30 One of the aryl groups; x is selected from integers from 1 to 18; m = 0.01 to 0.50, m+n = 1. The antibacterial nylon 6 material has a broad-spectrum and highly effective antibacterial effect, long-lasting antibacterial action, and excellent mechanical properties, and can be used to prepare textiles, daily necessities, building materials, packaging materials, or panels.

Description

Technical Field

[0001] This invention relates to the field of functional nylon materials technology, specifically to an antibacterial nylon 6 material, its preparation method, and its application. Background Technology

[0002] Nylon is a synthetic polymer material containing repeating amide groups (-CONH-) in its molecular backbone. Due to its excellent comprehensive properties, it is widely used in various industrial fields. These polymers possess outstanding characteristics such as lightweight, high strength and toughness, and wear resistance. They also exhibit good chemical corrosion resistance, barrier properties, and thermal stability. Combined with excellent processability, this makes them indispensable engineering materials in fields such as automotive manufacturing, textile industry, aerospace, construction, electrical and electronic engineering, and industrial machinery.

[0003] Among the many types of nylon, nylon 6 has long held a dominant market position due to its excellent mechanical properties and relatively low production cost. However, due to the limitations of its molecular backbone structure, nylon 6 typically exhibits high hygroscopicity, easily forming a micro-humid environment on its surface, thus providing favorable conditions for the growth of bacteria, fungi, and other microorganisms. This microbial growth problem not only accelerates material aging and reduces product lifespan, but more seriously, it can lead to microbial contamination, posing a potential threat to the health and safety of users, especially in sensitive applications such as medical and food packaging.

[0004] To address this technical challenge, the development of antibacterial modified nylon 6 has become an important research direction in the field of nylon materials. Currently, most antibacterial nylon products on the market are prepared using a physical blending method, combining small-molecule antibacterial agents (such as silver ions and copper ions) with a nylon matrix. However, these traditional antibacterial materials have significant limitations. On the one hand, metal ions may migrate and leach out, posing safety and environmental risks; on the other hand, antibacterial components are easily lost, resulting in poor antibacterial efficacy. Therefore, developing novel nylon materials that combine high safety, environmental friendliness, and long-lasting antibacterial properties has significant scientific and application value.

[0005] Recent studies have reported innovative chemical modification methods. ACS Macro Lett. 2022, 11, 46-52 first proposed a method involving ring-opening copolymerization of a seven-membered cyclic lysine monomer with caprolactam to introduce a dimethylamino functional group into the side chain of nylon 6, followed by quaternization with bromoethane to generate a quaternary ammonium cationic structure with antibacterial activity. Similarly, Chinese patent document CN115707727A also discloses a technique for preparing antibacterial nylon 6 by ring-opening copolymerization of a seven-membered cyclic lysine monomer with caprolactam followed by quaternization. While these methods have successfully endowed the materials with excellent broad-spectrum antibacterial properties, the introduction of quaternary ammonium cationic side groups often disrupts the regularity of the nylon molecular chain, leading to a decrease in the material's crystallinity and consequently affecting its mechanical properties. This trade-off between antibacterial properties and mechanical properties severely restricts the practical application of antibacterial nylon 6.

[0006] Based on the current technological status quo, developing novel quaternization modification methods has become a key research breakthrough. An ideal solution should achieve two objectives: firstly, ensuring the material acquires efficient and durable antibacterial capabilities; and secondly, maintaining or even enhancing the original mechanical properties of nylon 6. Breakthroughs in this technical challenge will significantly expand the application prospects of antibacterial nylon 6 in high-performance applications. Summary of the Invention

[0007] To address the technical problem of balancing antibacterial and mechanical properties in existing nylon materials, this invention proposes an antibacterial nylon material, its preparation method, and its application.

[0008] The specific technical solution of the present invention is as follows:

[0009] An antibacterial nylon 6 material has the structure shown in formula (I):

[0010]

[0011] Each R1 group and R2 group is independently selected from C 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～18 Aryl, substituted / unsubstituted C 7～30 One of the aralkyl groups, or the R1 and R2 groups on the same N atom together with the attached N atom to form a 5- to 7-membered saturated / unsaturated heterocycle;

[0012] Each E - The functional groups are independently selected from one or more of the following anionic structural formulas (II):

[0013]

[0014] in Indicates the bonding site; each R3 group is independently selected from C 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～18 Aryl, substituted / unsubstituted C 7～30 One of the aryl groups;

[0015] x represents the number of CH2 repeating units in expression (I), selected from any integer from 1 to 18; m and n represent the number of repeating units in expression (I) with The molar ratio of repeating units in the structure to the total repeating units and having The molar proportion of repeating units in the structure to the total repeating units is m = 0.01 to 0.50, n = 0.50 to 0.99, and m + n = 1;

[0016] The substitution refers to the group being replaced by one or more substituents, wherein the substituents are C. 1～18 Straight-chain or branched alkyl groups.

[0017] Preferably, each R1 group and R2 group is independently selected from C 1～12 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～6 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～10 Aryl, substituted / unsubstituted C 7～16 One of the aralkyl groups, or the R1 and R2 groups on the same N atom together with the attached N atom to form a 5- to 6-membered saturated / unsaturated heterocycle;

[0018] Each R3 group is independently selected from C 1～12 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～6 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～10 Aryl, substituted / unsubstituted C 7～16 One of the aryl groups.

[0019] Preferably, each R1 group and R2 group is independently selected from one of methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, allyl, phenyl, benzyl, or the R1 and R2 groups on the same N atom together with the adjacent N atom form a tetrahydropyrrole or hexahydropyridyl.

[0020] Each R3 group is independently selected from one of methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl, and benzyl.

[0021] Preferably, the total number of repeating units in formula (I) is between 10 and 2500, more preferably between 20 and 1000, and most preferably between 20 and 500.

[0022] Preferably, the antibacterial nylon 6 material has a number average molecular weight of 1,000 to 500,000, more preferably 5,000 to 200,000, and most preferably 5,000 to 50,000.

[0023] The present invention also provides a method for preparing the above-mentioned antibacterial nylon 6 material, comprising the following steps:

[0024] S1. Reaction of aminocaprolactam with the structure shown in (III) with one or more aldehydes and / or haloalkanes having R1 and / or R2 groups yields a cyclic lysine monomer having the structure shown in (IV):

[0025]

[0026] S2. The cyclic lysine monomer and caprolactam monomer are subjected to ring-opening polymerization in a molar ratio of 1:1 to 99 under the action of a catalyst and an activator to obtain a copolymer having the structure shown in formula (V):

[0027]

[0028] S3. The copolymer is reacted with an electrophilic reagent having a heterocycle as shown in formula (VI). The reaction product is precipitated in ethyl acetate / diethyl ether, centrifuged, and dried to obtain the antibacterial nylon 6 material.

[0029]

[0030] The structure of the heterocyclic electrophilic reagent having the formula (VI) is preferably one or more of proprolactone, 1,3-propanesulfonyl lactone, ethylene carbonate, and ethoxyphosphonate pentanone.

[0031] Preferably, the catalyst in step S2 is selected from one or more of carbene reagents, guanidine reagents, amidine reagents, phosphazene reagents, alkali metals, alkali metal oxides, alkali metal hydroxides, alkali metal hydrides, alkali metal alkoxides, alkaline earth metals, alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth metal hydrides, and alkaline earth metal alkoxides; more preferably, it is selected from one or more of sodium hydride, potassium hydride, t~BuP4, potassium tert-butoxide, sodium methoxide, potassium methoxide, DBU, TBD, sodium, and potassium.

[0032] Preferably, the activator in step S2 has the structure of formula (VII):

[0033]

[0034] R4 is selected from one of methyl, ethyl, phenyl, tert-butylphenyl, and trifluoromethylphenyl.

[0035] Preferably, the total amount of the cyclic lysine monomer and caprolactam monomer, and the molar ratio of catalyst to activator are (10-50):1:1; more preferably (10-30):1:1.

[0036] Preferably, the reaction conditions for the ring-opening polymerization reaction in step S2 are: a reaction temperature of 140–180°C and a reaction time of 3–6 h.

[0037] Preferably, the reaction in step S3 is carried out in one or more of the solvents methanol, ethanol, isopropanol, n-butanol, trifluoroethanol, hexafluoroisopropanol, perfluorotert-butanol, benzyl alcohol, ethylene glycol, and cyclohexanol; the reaction conditions are: a reaction temperature of 40-70°C and a reaction time of 10-12 h.

[0038] The present invention also provides an application of the above-mentioned antibacterial nylon 6 material, specifically for the preparation of textiles, daily necessities, building materials, packaging materials or panels.

[0039] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0040] This invention employs an innovative molecular design strategy, utilizing heterocyclic compounds as electrophiles to specifically react with the amino groups on the side chains of copolyamides, successfully constructing an antibacterial nylon material with a unique quaternary ammonium inner salt structure. Unlike existing technologies that use quaternization of haloalkanes to prevent the release of halogen counterions in the polymer system, the advantages of this invention are mainly reflected in the following aspects:

[0041] 1. This invention, through precise molecular design, enables the counter anions of quaternary ammonium groups to be firmly bonded to the copolyamide backbone via covalent bonds, forming a stable quaternary ammonium inner salt structure. This unique molecular configuration significantly improves the stability of charged groups, preventing the loss of antibacterial components; promotes the orderly aggregation of charged groups in the side chains through electrostatic interactions; and forms a physical cross-linked network structure, producing a synergistic effect with the hydrogen bond network of the main chain amide groups.

[0042] 2. Antibacterial properties: It exhibits broad-spectrum and highly efficient antibacterial activity, with significant inhibitory effects on Gram-positive bacteria, Gram-negative bacteria, and fungi; Long-term stability: The internal salt structure ensures long-lasting and stable antibacterial properties, maintaining excellent antibacterial effects even after multiple washes or long-term use; Mechanical properties: The formation of a physical cross-linked network brings a reinforcing effect to the material, and its key mechanical properties such as tensile strength, modulus, and impact toughness are all superior to those of conventional quaternized nylon materials.

[0043] 3. This invention maintains the excellent processing performance of nylon materials and can be formed using conventional processing methods such as injection molding, blow molding, extrusion, and spinning. It is suitable for preparing various forms of products such as fibers, films, sheets, and pipes, and has broad application prospects in textiles (such as medical protective clothing and antibacterial socks), daily necessities (kitchenware and bathroom products), building materials (antibacterial flooring and wall panels), packaging materials (food packaging and medical packaging), and electronic device panels.

[0044] 4. The raw materials for this invention are readily available and the cost is controllable. The preparation process is simple, has good compatibility with existing nylon production lines, and is easy to scale up for production, resulting in significant economic benefits and market competitiveness.

[0045] This invention successfully solves the technical problem of balancing antibacterial and mechanical properties in traditional antibacterial nylon materials, and provides a new technical route for the development of high-performance antibacterial polymer materials. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the synthesis route of the antibacterial nylon 6 material of the present invention;

[0047] Figure 2 This is a schematic diagram illustrating the antibacterial effect of the nylon 6 materials prepared in Example 1 and Comparative Example 1 against Staphylococcus aureus. Detailed Implementation

[0048] To make the technical solutions of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that the following embodiments are only used to better understand the technical solutions of the present invention and should not be construed as limiting the present invention.

[0049] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0050] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0051] In this document, except where expressly stated otherwise, any matters or issues not mentioned herein shall apply directly to those known in the art without any modification. Furthermore, any implementation described herein may be freely combined with one or more other implementations described herein, and any resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider such combination to be clearly unreasonable.

[0052] Example 1.

[0053] (1) Preparation of dimethyl-protected aminocaprolactam (DMCL)

[0054] 600 g (4.68 mol) of aminocaprolactam was weighed and dissolved in 10 L of methanol. 840 g (10.28 mol) of formaldehyde solution (37% by mass) and 60 g of 10% palladium on carbon were added. The mixture was reacted under a hydrogen atmosphere for 24 h. After filtration, concentration, and recrystallization, dimethyl-protected aminocaprolactam was obtained with a yield of 95%. The purity was greater than 99% according to 1H NMR spectroscopy.

[0055] (2) Preparation of copolyamide

[0056] Weigh 1.0 g (6.4 mmol) of dimethyl-protected aminocaprolactam (DMCL) prepared in step (1), 13.7 g (121.6 mmol) of caprolactam (CL), and 0.74 g (3.4 mmol) of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the gas at 40 °C for 30 min, add 140 mg (3.4 mmol) of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain 14.6 g (approximately 95%) of copolymer.

[0057] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine in the obtained copolymer was calculated to be approximately 4%.

[0058] (3) Preparation of antibacterial nylon 6 materials

[0059] 2.5 g of copolyamide (containing 4% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.24 g of propiolactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-1 with a yield of 90%, a number-average molecular weight of 30.5 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 4%.

[0060] 2.5 g of copolyamide (containing 4% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.40 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-2, with a yield of 91%, a number-average molecular weight of 31.2 kDa, and a molar content of approximately 4% of the quaternary ammonium inner salt side groups.

[0061] 2.5 g of copolyamide (containing 4% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.29 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-3, with a yield of 89%, a number-average molecular weight of 29.2 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 4%.

[0062] 2.5 g of copolyamide (containing 4% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.49 g of ethoxyphosphazenecyclopentanone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-4, with a yield of 90%, a number-average molecular weight of 35.0 kDa, and a molar content of approximately 4% of the quaternary ammonium inner salt side groups.

[0063] Example 2.

[0064] Weigh 10 mmol of the dimethyl-protected aminocaprolactam (DMCL) prepared in step (1) of Example 1, 90 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40°C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180°C for 6 h. Add 100 ml of trifluoroethanol to dissolve the polymer, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 92%.

[0065] NMR characterization results: 1¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine in the obtained copolymer was calculated to be approximately 8%.

[0066] 2.5 g of copolyamide (containing 8% DMCL) was weighed and dissolved in 50 mL of trifluoroethanol. 0.48 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-5, with a yield of 90%, a number-average molecular weight of 28.5 kDa, and a molar content of approximately 8% for the quaternary ammonium inner salt side groups.

[0067] 2.5 g of copolyamide (containing 8% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.80 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-6, with a yield of 89%, a number-average molecular weight of 28.8 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 8%.

[0068] 2.5 g of copolyamide (containing 8% DMCL) was dissolved in 50 mL of trifluoroethanol, and 0.60 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-7, with a yield of 91%, a number-average molecular weight of 30.8 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 8%.

[0069] 2.5 g of copolyamide (containing 8% DMCL) was dissolved in 50 mL of trifluoroethanol, and 1.00 g of ethoxyphosphazenecyclopentanone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-8, with a yield of 92%, a number-average molecular weight of 33.4 kDa, and a molar content of approximately 8% of the quaternary ammonium inner salt side groups.

[0070] Example 3.

[0071] Weigh 20 mmol of the dimethyl-protected aminocaprolactam (DMCL) prepared in step (1) of Example 1, 80 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40°C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180°C for 6 h. Add 100 ml of trifluoroethanol to dissolve the polymer, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 92%.

[0072] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts of 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine in the obtained copolymer was calculated to be approximately 18%.

[0073] 2.5 g of copolyamide (containing 18% DMCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.08 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-9, with a yield of 90%, a number-average molecular weight of 25.3 kDa, and a molar content of approximately 18% for the quaternary ammonium inner salt side groups.

[0074] 2.5 g of copolyamide (containing 18% DMCL) was dissolved in 50 mL of trifluoroethanol, and 2.0 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-10, with a yield of 88%, a number-average molecular weight of 27.6 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 18%.

[0075] 2.5 g of copolyamide (containing 18% DMCL) was dissolved in 50 mL of trifluoroethanol, and 1.5 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-11 with a yield of 90%, a number-average molecular weight of 28.2 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 18%.

[0076] 2.5 g of copolyamide (containing 18% DMCL) was weighed and dissolved in 50 mL of trifluoroethanol. 2.5 g of ethoxyphosphazene was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-12, with a yield of 87%, a number-average molecular weight of 27.4 kDa, and a molar content of approximately 18% for the quaternary ammonium inner salt side groups.

[0077] Example 4.

[0078] Weigh 30 mmol of the dimethyl-protected aminocaprolactam (DMCL) prepared in step (1) of Example 1, 70 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40°C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180°C for 6 h. Add 100 ml of trifluoroethanol to dissolve the polymer, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0079] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts of 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine in the obtained copolymer was calculated to be approximately 27%.

[0080] 2.5 g of copolyamide (containing 27% DMCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.50 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-13, with a yield of 89%, a number-average molecular weight of 22.3 kDa, and a molar content of approximately 27% for the quaternary ammonium inner salt side groups.

[0081] 2.5 g of copolyamide (containing 27% DMCL) was dissolved in 50 mL of trifluoroethanol, and 3.0 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-14, with a yield of 90%, a number-average molecular weight of 24.6 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 27%.

[0082] 2.5 g of copolyamide (containing 27% DMCL) was dissolved in 50 mL of trifluoroethanol, and 2.5 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-15, with a yield of 90%, a number-average molecular weight of 23.2 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 27%.

[0083] 2.5 g of copolyamide (containing 27% DMCL) was dissolved in 50 mL of trifluoroethanol, and 4.0 g of ethoxyphosphazenecyclopentanone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-16, with a yield of 92%, a number-average molecular weight of 25.4 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 27%.

[0084] Example 5.

[0085] (1) Preparation of diethyl-protected aminocaprolactam (DECL)

[0086] 300 g (2.34 mol) of aminocaprolactam was weighed and dissolved in 5 L of methanol. 566 g (5.14 mol) of acetaldehyde solution (40% by mass) and 30 g of 10% palladium on carbon were added. The reaction was carried out under a hydrogen atmosphere for 24 h. After filtration, concentration, and recrystallization, diethyl-protected aminocaprolactam was obtained with a yield of 92%. The purity was greater than 99% according to 1H NMR spectroscopy.

[0087] (2) Preparation of copolyamide

[0088] Weigh 5 mmol of diethyl-protected aminocaprolactam (DECL), 95 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator prepared in step (1) into a 25 ml round-bottom flask. After evacuating the flask at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0089] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.80–3.71, 3.23–3.12, 2.86–2.82, 2.21–2.00, 1.81–1.15. By comparing the proton integral area at chemical shifts 3.80–3.71 with that at 2.21–2.00, the molar proportion of diethylaminocyclic lysine in the obtained copolymer was calculated to be approximately 4%.

[0090] (3) Preparation of antibacterial nylon 6 materials

[0091] 2.0 g of copolyamide (containing 4% DECL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.00 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-17, with a yield of 88%, a number-average molecular weight of 24.3 kDa, and a molar content of approximately 4% of the quaternary ammonium inner salt side groups.

[0092] 2.0 g of copolyamide (containing 4% DECL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.20 g of 1,3-propanesulfonyl lactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-18, with a yield of 92%, a number-average molecular weight of 25.6 kDa, and a molar content of approximately 4% for the quaternary ammonium inner salt side groups.

[0093] 2.0 g of copolyamide (containing 4% DECL) was dissolved in 50 mL of trifluoroethanol, and 0.9 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in a mixture of ethyl acetate / ethyl ether, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-19 with a yield of 92%, a number-average molecular weight of 22.2 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 4%.

[0094] 2.0 g of copolyamide (containing 4% DECL) was dissolved in 50 mL of trifluoroethanol, and 1.08 g of ethoxyphosphazenecyclopentanone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-20, with a yield of 91%, a number-average molecular weight of 26.4 kDa, and a molar content of approximately 4% of the quaternary ammonium inner salt side groups.

[0095] Example 6.

[0096] (1) Preparation of dipropyl-protected aminocaprolactam (DPCL)

[0097] 300 g (2.34 mol) of aminocaprolactam was weighed and dissolved in 5 L of methanol. 299 g (5.14 mol) of propionaldehyde and 30 g of 10% palladium on carbon were added, and the mixture was reacted under a hydrogen atmosphere for 24 h. The solution was filtered, concentrated, subjected to column chromatography, and recrystallized to obtain dipropyl-protected aminocaprolactam in 90% yield. The purity was greater than 99% according to 1H NMR spectroscopy.

[0098] (2) Preparation of copolyamide

[0099] Weigh 5 mmol of dipropyl-protected aminocaprolactam (DPCL), 95 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator prepared in step (1) into a 25 ml round-bottom flask. After evacuating the flask at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0100] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.85–3.71, 3.25–3.12, 2.96–2.72, 2.21–2.00, 1.91–1.15. By comparing the proton integral area at chemical shifts of 3.85–3.71 with that at 2.21–2.00, the molar proportion of dipropylamino cyclic lysine inserted into the obtained copolymer was calculated to be approximately 5%.

[0101] (3) Preparation of antibacterial nylon 6 materials

[0102] 2.2 g of copolyamide (containing 5% DPCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.00 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-21, with a yield of 88%, a number-average molecular weight of 21.3 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0103] 2.2 g of copolyamide (containing 5% DPCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.20 g of 1,3-propanesulfonyl lactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-22, with a yield of 92%, a number-average molecular weight of 22.6 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0104] 2.2 g of copolyamide (containing 5% DPCL) was dissolved in 50 mL of trifluoroethanol, and 0.9 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-23, with a yield of 92%, a number-average molecular weight of 23.2 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 5%.

[0105] 2.2 g of copolyamide (containing 5% DPCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.08 g of ethoxyphosphazenecyclopentanone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-24, with a yield of 91%, a number-average molecular weight of 24.4 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0106] Example 7.

[0107] (1) Preparation of dibenzyl-protected aminocaprolactam (DBCL)

[0108] 300 g (2.34 mol) of aminocaprolactam was weighed and dissolved in 5 L of acetonitrile. 560 mL (4.91 mol) of benzyl chloride and 468 g (3.51 mol) of potassium carbonate were added, and the mixture was stirred at 80 °C for 6 h. The solution was washed with 1 M HCl until neutral, extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered, concentrated, subjected to column chromatography, and recrystallized to obtain dibenzyl-protected aminocaprolactam in 85% yield. The purity was 95% according to 1H NMR spectroscopy.

[0109] (2) Preparation of copolyamide

[0110] Weigh 5 mmol of dibenzyl-protected aminocaprolactam (DBCL) prepared in step (1), 95 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0111] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 7.00–7.50, 3.85–2.8, 2.21–2.00, 1.91–1.20. By comparing the proton integral area at chemical shifts of 7.00–7.50 with that at 2.21–2.00, the molar proportion of dibenzylaminocyclic lysine in the obtained copolymer was calculated to be approximately 5%.

[0112] (3) Preparation of antibacterial nylon 6 materials

[0113] 3.0 g of copolyamide (containing 5% DBCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.00 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-25, with a yield of 88%, a number-average molecular weight of 28.3 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0114] 3.0 g of copolyamide (containing 5% DBCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.20 g of 1,3-propanesulfonyl lactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-26, with a yield of 92%, a number-average molecular weight of 29.6 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0115] 3.0 g of copolyamide (containing 5% DBCL) was dissolved in 50 mL of trifluoroethanol, and 0.9 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-27, with a yield of 92%, a number-average molecular weight of 28.2 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0116] 3.0 g of copolyamide (containing 5% DBCL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.08 g of ethoxyphosphazene was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-28, with a yield of 91%, a number-average molecular weight of 34.4 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0117] Example 8.

[0118] (1) Preparation of diallyl-protected aminocaprolactam (DACL)

[0119] 300 g (2.34 mol) of aminocaprolactam was weighed and dissolved in 5 L of acetonitrile. 594 g (4.91 mol) of allyl bromide and 468 g (3.51 mol) of potassium carbonate were added, and the mixture was stirred at 80 °C for 6 h. The solution was washed with 1 M HCl until neutral, extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered, concentrated, subjected to column chromatography, and recrystallized to obtain diallyl-protected aminocaprolactam in 88% yield. The purity was 96% according to 1H NMR spectroscopy.

[0120] (2) Preparation of copolyamide

[0121] Weigh 5 mmol of diallyl-protected aminocaprolactam (DACL) prepared in step (1), 95 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0122] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 6.00–5.80, 5.30–5.10, 3.90–2.6, 2.21–2.00, 1.91–1.20. By comparing the proton integral area at chemical shifts 6.00–5.80 with that at 2.21–2.00, the molar proportion of diallylaminocyclic lysine in the obtained copolymer was calculated to be approximately 5%.

[0123] (3) Preparation of antibacterial nylon 6 materials

[0124] 2.0 g of copolyamide (containing 5% DACL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.20 g of propiolactone was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-29, with a yield of 90%, a number-average molecular weight of 22.6 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0125] 2.0 g of copolyamide (containing 5% DACL) was dissolved in 50 mL of trifluoroethanol, and 1.40 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-30, with a yield of 91%, a number-average molecular weight of 24.6 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0126] 2.0 g of copolyamide (containing 5% DACL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.30 g of ethylene carbonate was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-31, with a yield of 93%, a number-average molecular weight of 23.8 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0127] 2.0 g of copolyamide (containing 5% DACL) was weighed and dissolved in 50 mL of trifluoroethanol. 1.50 g of ethoxyphosphazene was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-32, with a yield of 90%, a number-average molecular weight of 24.5 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0128] Example 9.

[0129] (1) Preparation of N,N-hexahydropyridylaminocaprolactam (HPCL)

[0130] 300 g (2.34 mol) of aminocaprolactam was weighed and dissolved in 5 L of acetonitrile. 807 g (3.51 mol) of 1,5-dibromopentane and 468 g (3.51 mol) of potassium carbonate were added, and the mixture was stirred at 80 °C for 6 h. The solution was washed with 1 M HCl until neutral, extracted with dichloromethane, dried over anhydrous sodium sulfate, filtered, concentrated, subjected to column chromatography, and recrystallized to obtain N,N-hexahydropyridylaminocaprolactam in 80% yield. The purity was 96% according to 1H NMR spectroscopy.

[0131] (2) Preparation of copolyamide

[0132] Weigh 5 mmol of diallyl-protected aminocaprolactam (HPCL) prepared in step (1), 95 mmol of caprolactam (CL), and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuating the flask at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate it in an ethyl acetate / ether mixed solvent, centrifuge, and dry to obtain the copolymer product with a yield of approximately 90%.

[0133] NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) 3.90–3.73, 3.60–2.6, 2.21–2.00, 1.91–1.20. By comparing the proton integral area at chemical shifts of 3.90–3.73 with that at 2.21–2.00, the molar proportion of N,N-hexahydropyridylaminocaprolactam in the obtained copolymer was calculated to be approximately 5%.

[0134] (3) Preparation of antibacterial nylon 6 materials

[0135] 2.5 g of copolyamide (containing 5% HPCl) was dissolved in 50 mL of trifluoroethanol, and 1.00 g of propiolactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-33, with a yield of 93%, a number-average molecular weight of 21.7 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0136] 2.5 g of copolyamide (containing 5% HPCl) was dissolved in 50 mL of trifluoroethanol, and 1.20 g of 1,3-propanesulfonyl lactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-34, with a yield of 90%, a number-average molecular weight of 22.1 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0137] 2.5 g of copolyamide (containing 5% HPCl) was dissolved in 50 mL of trifluoroethanol, and 1.00 g of ethylene carbonate was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-35, with a yield of 92%, a number-average molecular weight of 24.9 kDa, and a molar content of approximately 5% of the quaternary ammonium inner salt side groups.

[0138] 2.5 g of copolyamide (containing 5% HPCl) was weighed and dissolved in 50 mL of trifluoroethanol. 1.20 g of ethoxyphosphazene was added, and the mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-36, with a yield of 91%, a number-average molecular weight of 23.7 kDa, and a molar content of approximately 5% for the quaternary ammonium inner salt side groups.

[0139] Comparative Example 1.

[0140] Weigh 40 mmol of caprolactam and 4 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuation at 40 °C for 30 min, add 4 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. This yields CP-37, a conventional nylon 6 material with a number-average molecular weight of 30.0 kDa.

[0141] Comparative Example 2.

[0142] Weigh 1 mmol of dimethyl-protected aminocaprolactam, 99 mmol of caprolactam, and 5 mmol of N-benzoylcaprolactam activator into a 25 mL round-bottom flask. After evacuation at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 mL of trifluoroethanol, precipitate in an ethyl acetate / ether mixture, centrifuge, and dry to obtain the copolymer, with a yield of approximately 90%. NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine inserted into the obtained copolymer was calculated to be approximately 0.5%.

[0143] 2.5 g of copolyamide (containing 0.5% DMCL) was dissolved in 50 mL of trifluoroethanol, and 1.00 g of propiolactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-38 with a yield of 90%, a number-average molecular weight of 21.7 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 0.5%.

[0144] Comparative Example 3.

[0145] Weigh 50 mmol of dimethyl-protected aminocaprolactam, 50 mmol of caprolactam, and 5 mmol of N-benzoylcaprolactam activator into a 25 ml round-bottom flask. After evacuation at 40 °C for 30 min, add 5 mmol of sodium hydride. Under nitrogen protection, react in an oil bath at 180 °C for 6 h. Dissolve the polymer in 100 ml of trifluoroethanol, precipitate in an ethyl acetate / ether mixture, centrifuge, and dry to obtain the copolymer, with a yield of approximately 90%. NMR characterization results: 1 ¹H NMR (500MHz TFA / DMSO-d6, 5:95, v:v) δ 3.70–3.61, 3.13–3.02, 2.76–2.72, 2.21–2.00, 1.81–1.18. By comparing the proton integral area at chemical shifts 3.70–3.61 with that at 2.21–2.00, the molar proportion of dimethylaminocyclic lysine inserted into the obtained copolymer was calculated to be approximately 55%.

[0146] 2.5 g of copolyamide (containing 45% DMCL) was dissolved in 50 mL of trifluoroethanol, and 10.00 g of propiolactone was added. The mixture was heated under reflux for 24 h. After the reaction was complete, the solution was settled in an ethyl acetate / ether mixture, centrifuged, and dried to obtain quaternized antibacterial nylon 6 material CP-39, with a yield of 90%, a number-average molecular weight of 27.9 kDa, and a molar content of quaternary ammonium inner salt side groups of approximately 55%.

[0147] The characteristics of the nylon materials in the above embodiments and comparative examples are summarized in Table 1.

[0148] Table 1

[0149]

[0150]

[0151] Example of an effect 1.

[0152] Antibacterial effect test:

[0153] The antibacterial effect was tested according to the method of Chinese National Standard GB / T 31402-2023, and some conditions were adjusted according to the actual situation. The specific operation is as follows:

[0154] The antibacterial nylon materials obtained in Examples 1-9 and the nylon materials prepared in Comparative Examples 1-3 were pressed into 5cm×5cm square sheets, sprayed with 75% alcohol, air-dried, and sterilized by irradiation under a UV lamp for 30 minutes. Then, a solution of 6×10⁻⁶ alcohol was dropped onto the sheet. 5 0.4 mL of CFU / mL bacterial suspension was covered with a PET film and incubated at 37°C for 24 h. The slides were rinsed with 10 mL of SCDLP liquid medium, and the bacterial suspension was diluted serially and mixed with PCA medium. The solutions were incubated at 37°C for 48 h, and the colonies in the medium were counted using an automated colony counter to estimate the bacterial concentration after incubation. The conventional nylon material obtained in Comparative Example 1 was used as a control group.

[0155] Figure 2 Comparative photographs show the antibacterial effects of nylon materials prepared by CP-2 in Example 1 and CP-37 in Comparative Example 1 against Staphylococcus aureus, with both diluted 100 times. The spots shown represent surviving colonies. It is clearly evident from the figures that the antibacterial nylon material of the present invention exhibits a significant inhibitory effect on Staphylococcus aureus compared to the conventional nylon material prepared in Comparative Example 1.

[0156] The bacteria used for testing were Staphylococcus aureus (S. aureus) ATCC6538 and Escherichia coli (E. coli) ATCC25922.

[0157] The formula for calculating the antibacterial rate is as follows:

[0158]

[0159] The test results are shown in Table 2.

[0160] Example of effect 2.

[0161] Mechanical property testing:

[0162] The antibacterial nylon materials prepared in Examples 1-9 and the nylon materials prepared in Comparative Examples 1-3 were injection molded into 5A type specimens (dimensions refer to Chinese National Standard GB / T 1040.2-2022) and tensile properties were tested. The results are shown in Table 2.

[0163] Table 2

[0164]

[0165]

[0166]

[0167] Test results demonstrate that the antibacterial nylon 6 material provided by this invention has significant antibacterial effects, and its mechanical properties are basically equivalent to or even better than those of conventional nylon materials (Comparative Example 1). In contrast, the antibacterial properties of the nylon material in Comparative Example 2 are insufficient due to the low molar ratio of cyclic lysine insertion; while the mechanical properties of the nylon material in Comparative Example 3 are poor due to the high molar ratio of insertion.

[0168] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0169] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0170] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be considered as the content protected by the present invention.

Claims

1. An antibacterial nylon 6 material, characterized in that, It has the structure shown in equation (I): Each R1 group and R2 group is independently selected from C 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～18 Aryl, substituted / unsubstituted C 7～30 One of the aralkyl groups, or the R1 and R2 groups on the same N atom together with the attached N atom to form a 5- to 7-membered saturated / unsaturated heterocycle; Each E - The functional groups are independently selected from one or more of the following anionic structural formulas (II): in Indicates the bonding site; each R3 group is independently selected from C 1～24 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～12 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～18 Aryl, substituted / unsubstituted C 7～30 One of the aryl groups; x is any integer from 1 to 18; m = 0.01 to 0.50, n = 0.50 to 0.99, and m + n = 1; The substitution refers to the group being replaced by one or more substituents, wherein the substituents are C. 1～18 Straight-chain or branched alkyl groups.

2. The antibacterial nylon 6 material according to claim 1, characterized in that, Each R1 group and R2 group is independently selected from C 1～12 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～6 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～10 Aryl, substituted / unsubstituted C 7～16 One of the aralkyl groups, or the R1 and R2 groups on the same N atom together with the attached N atom to form a 5- to 6-membered saturated / unsaturated heterocycle; Each R3 group is independently selected from C 1～12 Straight-chain / branched aliphatic hydrocarbon groups, substituted / unsubstituted C 3～6 Alicyclic hydrocarbon groups, substituted / unsubstituted C 6～10 Aryl, substituted / unsubstituted C 7～16 One of the aryl groups.

3. The antibacterial nylon 6 material according to claim 1, characterized in that, Each R1 group and R2 group is independently selected from one of methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, allyl, phenyl, benzyl, or the R1 and R2 groups on the same N atom together with the adjacent N atom to form tetrahydropyrrole or hexahydropyridyl. Each R3 group is independently selected from one of methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, cyclohexyl, phenyl, and benzyl.

4. A method for preparing an antibacterial nylon 6 material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Reaction of aminocaprolactam with the structure shown in (III) with one or more aldehydes and / or haloalkanes having R1 and / or R2 groups yields a cyclic lysine monomer having the structure shown in (IV): S2. The cyclic lysine monomer and caprolactam monomer are subjected to ring-opening polymerization in a molar ratio of 1:1 to 99 under the action of a catalyst and an activator to obtain a copolymer having the structure shown in formula (V): S3. The copolymer is reacted with an electrophilic reagent having a heterocycle as shown in formula (VI). The reaction product is precipitated in ethyl acetate / diethyl ether, centrifuged, and dried to obtain the antibacterial nylon 6 material.

5. The method for preparing the antibacterial nylon 6 material according to claim 4, characterized in that, The catalyst mentioned in step S2 is selected from one or more of the following: carbene reagents, guanidine reagents, amidine reagents, phosphazene reagents, alkali metals, alkali metal oxides, alkali metal hydroxides, alkali metal hydrides, alkali metal alkoxides, alkaline earth metals, alkaline earth metal oxides, alkaline earth metal hydroxides, alkaline earth metal hydrides, and alkaline earth metal alkoxides.

6. The method for preparing the antibacterial nylon 6 material according to claim 4, characterized in that, The activator in step S2 has the structure described in formula (VII): R4 is selected from one of methyl, ethyl, phenyl, tert-butylphenyl, and trifluoromethylphenyl.

7. The method for preparing the antibacterial nylon 6 material according to claim 4, characterized in that, The total amount of the cyclic lysine monomer and caprolactam monomer, and the molar ratio of catalyst to activator are (10-50):1:1; the reaction conditions for the ring-opening polymerization reaction in step S2 are: reaction temperature of 140-180℃ and reaction time of 3-6h.

8. The method for preparing the antibacterial nylon 6 material according to claim 4, characterized in that, The electrophilic reagent mentioned in step S3 is selected from one or more of propiolactone, 1,3-propanesulfonyllactone, ethylene carbonate, and ethoxyphosphazenecyclopentanone.

9. The method for preparing the antibacterial nylon 6 material according to claim 4, characterized in that, The reaction described in step S3 is carried out in one or more of the following solvents: methanol, ethanol, isopropanol, n-butanol, trifluoroethanol, hexafluoroisopropanol, perfluorotert-butanol, benzyl alcohol, ethylene glycol, and cyclohexanol; the reaction conditions are: reaction temperature of 40-70℃ and reaction time of 10-12h.

10. The application of an antibacterial nylon 6 material as described in any one of claims 1-3, characterized in that, It is used in the preparation of textiles, daily necessities, building materials, packaging materials or panels.

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