Preparation method of long-acting antibacterial material of electron beam irradiation grafted quaternary ammonium salt

Abstract

The application discloses a preparation method of long-acting antibacterial material of electron beam irradiation grafted quaternary ammonium salt, and belongs to the technical field of antibacterial functional material; the method comprises the following steps: cleaning and drying pretreatment of a polymer base material; preparing a grafting solution containing quaternary ammonium salt monomers; immersing the pretreated base material in the grafting solution, so that the grafting solution is uniformly distributed on the surface and inside of the base material; electron beam irradiation of the immersed base material in a wet state, to initiate grafting reaction of the quaternary ammonium salt monomers and the base material; and washing and drying after irradiation, to obtain the antibacterial material. The antibacterial material prepared by the method has an initial antibacterial rate of more than 99% on staphylococcus aureus and escherichia coli, and the antibacterial rate is still maintained at more than 97% after 50 times of standard washing, so that the antibacterial material has broad-spectrum, high-efficiency and long-lasting antibacterial performance, and the process is simple, the base material has a wide application range, and the method is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of antibacterial functional materials technology, specifically a method for preparing a long-lasting antibacterial material grafted with quaternary ammonium salt by electron beam irradiation. Background Technology

[0002] Antimicrobial materials have a wide range of applications in medical and health care, public protection, and other fields. Quaternary ammonium compounds, due to their positive charge, can electrostatically adsorb onto the negatively charged bacterial cell membranes and disrupt the membrane structure. They have advantages such as broad spectrum, high efficiency, and low likelihood of inducing drug resistance, making them one of the most widely researched and applied organic antimicrobial agents.

[0003] Electron beam irradiation is an effective method for grafting quaternary ammonium salts onto polymer substrates to prepare antibacterial functional materials. However, existing technologies still have the following shortcomings: (1) Limited applicability to substrates. The reported electron beam irradiation grafting method for quaternary ammonium salts is mostly designed for cotton fabrics, polyester fiber fabrics or specific nonwoven fabrics (such as 201610166316.7, 202480001629.X). There is no unified method that can be universally applied to various forms of polymer substrates such as textile fabrics, nonwoven fabrics and polymer membrane materials, which limits the application scope of this technology.

[0004] (2) The antibacterial components are not firmly bonded and lack durability. Although the blending spinning method has a certain degree of wash resistance, a large amount of antibacterial agent is encapsulated inside the fiber and cannot exert its effect. In addition, it is costly and difficult to spin. The finishing coating method relies on physical adsorption or weak interaction, and the antibacterial components are easy to fall off during washing or friction. Even if chemical grafting is used, it is often difficult to achieve long-term antibacterial effect due to low grafting efficiency and uneven layer.

[0005] (3) The grafting process is complicated and not conducive to industrialization. Most existing electron beam irradiation schemes adopt a two-step method of "irradiation pretreatment followed by impregnation grafting". The steps are complicated, and the active sites generated by irradiation are easily attenuated or quenched during the transfer process, resulting in low grafting efficiency and poor uniformity, making it difficult to achieve continuous production.

[0006] (4) The function of quaternary ammonium salts was not fully utilized. Some technologies combine quaternary ammonium salts with photocatalytic microparticles, haloamine compounds or silver ions, which increases the complexity of the formulation and potential safety risks, and fails to give full play to the safe, broad-spectrum and efficient antibacterial advantages of quaternary ammonium salts as a single grafted functional monomer. Summary of the Invention

[0007] To address the shortcomings of the existing technology, this invention provides a long-lasting antibacterial material grafted with quaternary ammonium salt by electron beam irradiation and its preparation method, aiming to solve problems such as poor substrate versatility, insufficient antibacterial durability, complex process, and incomplete utilization of quaternary ammonium salt function.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a long-lasting antibacterial material grafted with quaternary ammonium salt by electron beam irradiation includes the following steps: S1 involves cleaning and drying the polymer substrate for pretreatment; S2 is used to prepare a grafting solution containing quaternary ammonium salt monomers; S3 involves immersing the pretreated polymer substrate in the grafting solution prepared in step S2, and then fully wetting it through immersion, rolling, or soaking. S4 involves irradiating the polymer substrate after step S3 with an electron beam to initiate a grafting reaction between the quaternary ammonium salt monomer and the polymer substrate. S5 involves washing and drying the irradiated polymer substrate to remove unreacted monomers and homopolymers, thus obtaining the antibacterial material.

[0009] Furthermore, the polymer substrate is any one of pure cotton woven fabric, polyester fabric, polypropylene spunbond nonwoven fabric, polyvinylidene fluoride microfiltration membrane, polyethersulfone membrane or polypropylene membrane.

[0010] Furthermore, the cleaning in step S1 involves ultrasonically cleaning the substrate in deionized water for 10 to 30 minutes, and the drying involves drying in an oven at 50 to 80°C for 1 to 3 hours.

[0011] Furthermore, the quaternary ammonium salt monomer mentioned in step S2 is one or more of the following: methacryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium bromide, acryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium bromide, dimethyl diallyl ammonium chloride, dimethyl diallyl ammonium bromide, allyl trimethylammonium chloride, allyl trimethylammonium bromide, (3-chloro-2-hydroxypropyl)trimethylammonium chloride, and 2,3-epoxypropyltrimethylammonium chloride.

[0012] Furthermore, the mass concentration of the quaternary ammonium salt monomer in the grafting solution in step S2 is 5% to 20%.

[0013] Furthermore, the impregnation described in step S3 involves immersing the substrate in the grafting solution for full wetting, then rolling it with rollers to control the roll residue rate at 70% to 90%, and repeating the impregnation 1 to 3 times. For polymer membrane materials, the impregnation method involves completely immersing the membrane material in the grafting solution for 20 to 60 minutes without rolling.

[0014] Furthermore, the absorbed dose of the electron beam irradiation in step S4 is 5–15 kGy, and the irradiation is carried out under nitrogen protection.

[0015] Furthermore, the washing in step S5 involves repeatedly washing with deionized water 3 to 10 times, each time for 5 to 20 minutes; the drying involves drying in an oven at 50 to 80°C until constant weight.

[0016] Furthermore, the grafting solution in step S2 also contains a crosslinking agent, which is N,N'-methylenebisacrylamide, and its mass is 1% to 5% of the mass of the quaternary ammonium salt monomer.

[0017] Furthermore, when the polymer substrate is a hydrophobic substrate, after the cleaning and drying pretreatment in step S1, the step of plasma pretreatment of the substrate is also included. The plasma treatment is low-temperature plasma treatment, the working gas is air, the treatment power is 100-150 W, and the treatment time is 2-3 minutes.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The invention has a wide range of substrate adaptability. It can be applied to various forms of polymer substrates, such as textile fabrics, non-woven fabrics, and polymer membrane materials. Examples 1 to 7 all achieved an initial antibacterial rate of over 99%, breaking through the limitation of existing technologies that are limited to a single substrate type, and have good universality and versatility.

[0019] Quaternary ammonium salts are firmly grafted onto the surface and interior of the substrate via covalent bonds, forming a non-release antibacterial layer. After 50 standard washes, Examples 1-7 maintained an inhibition rate of over 97% against Escherichia coli and Staphylococcus aureus, while Comparative Example 4 showed a sharp drop in inhibition rate to 25%-30% after 50 washes, fully demonstrating the significantly superior long-lasting antibacterial properties of the product of this invention.

[0020] This invention employs a one-step process involving direct electron beam irradiation after impregnation of the substrate with a quaternary ammonium salt monomer solution. This eliminates the need for pre-irradiation pretreatment, resulting in a simple and convenient process that avoids the attenuation or quenching of active sites during the transfer process. The antibacterial rate of Comparative Example 2 was only 75%–80%, far lower than the approximately 99% of the one-step method embodiment of this invention. This verifies the superiority of the one-step method in improving grafting efficiency and uniformity, and it is also more conducive to continuous production.

[0021] This invention uses only quaternary ammonium salts as the antibacterial functional component, without adding photocatalytic microparticles, haloamine compounds, or other antibacterial agents such as metal ions, thus avoiding the potential safety risks and environmental pollution problems that may arise from compound antibacterial agents. While Comparative Example 3 achieved an initial antibacterial rate of 99%, it decreased to 52%–65% after 50 washes, and the biosafety of nano-silver is controversial. This invention ensures both high antibacterial efficiency and better safety. Attached Figure Description

[0022] Figure 1Infrared spectra of quaternary ammonium salt monomers, pure cotton woven fabrics, and grafted samples.

[0023] Figure 2 For E. coli, sample a) of Example 1 was diluted 2.8 × 10⁻⁶ with unwashed solution. 3 b) Diluted to 3.2 × 10⁻⁶ compared to pure cotton woven fabric. 4 Optical microscope image after double culture.

[0024] Figure 3 For Staphylococcus aureus, unwashed sample from Example 1: a) diluted 0 times compared to pure cotton woven fabric; b) diluted 3.2 × 10⁻⁶. 4 Optical microscope image after double culture.

[0025] Figure 4 Example 1 sample a) was diluted 1.2 × 10⁻⁶ after being washed 50 times with E. coli. 3 b) Diluted to 3.8 × 10⁻⁶ compared to pure cotton woven fabric. 4 Optical microscope image after double culture.

[0026] Figure 5 For Staphylococcus aureus after 50 washes, Example 1 sample a) diluted 0 times and compared with pure cotton woven fabric; b) diluted 3.8 × 10⁻⁶. 4 Optical microscope image after double culture. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0028] Step 1: Preparation and pretreatment of the substrate. Select commercially available pure cotton woven fabric as the substrate and cut it into 30cm×30cm samples. Place the samples in deionized water at 100W and 25℃ for ultrasonic cleaning for 15 minutes to remove surface impurities and residual additives. After cleaning, dry them in a 60℃ oven for 2 hours for later use.

[0029] Step 2: Preparation of grafting solution. Weigh acryloyloxyethyltrimethylammonium chloride and dissolve it in deionized water to prepare a 10% (w / w) grafting solution. Stir at room temperature until completely dissolved and set aside.

[0030] Step 3: Substrate impregnation treatment. Immerse the cotton fabric sample prepared in Step 1 into the grafting solution prepared in Step 2. After thorough impregnation, press it through rollers. Roller pressure: 0.15 MPa; pressing speed: 3 m / min, control the residual rate to 80%, repeat the impregnation twice to ensure that the grafting solution is evenly distributed and fully penetrates into the fiber. Immediately after impregnation, pack it into a sealed bag.

[0031] Rolling allowance = (weight gain of the sample after rolling / original weight of the dry sample) × 100%.

[0032] Step 4: Electron beam irradiation grafting. The cotton fabric treated in Step 3 was placed in a sealed bag, evacuated to -0.095 MPa, and then filled with nitrogen for protection. Electron beam irradiation was performed using an electron accelerator with an absorbed dose of 10 kGy, accelerating voltage of 2 MeV, beam current of 80 mA, and dose rate of 100 kGy / s. The sample was removed after irradiation.

[0033] Step 5: Post-treatment. Wash the irradiated cotton fabric repeatedly with deionized water five times, 10 minutes each time, to remove unreacted monomers and homopolymers. After washing, dry in a 60°C oven to constant weight to obtain the antibacterial cotton fabric. Example 2

[0034] Step 1: Select commercially available polyester fabric as the substrate and cut it into 30cm×30cm samples. Place the samples in deionized water for ultrasonic cleaning for 15 minutes, then remove and dry in a 60℃ oven for 2 hours. Due to the poor hydrophilicity of polyester fabric, pre-treat the dried fabric with plasma: use a low-temperature plasma treatment device with air as the working gas, a treatment power of 100W, and a treatment time of 3 minutes to enhance the wettability and penetration of the subsequent grafting solution on the fiber surface.

[0035] Steps 2 through 5: Same as in Example 1. Example 3

[0036] Step 1: Select commercially available polypropylene spunbond nonwoven fabric as the substrate and cut it into 30cm×30cm samples. Place the samples in deionized water for ultrasonic cleaning for 15 minutes, then remove and dry in a 60℃ oven for 2 hours. Perform plasma pretreatment on the dried nonwoven fabric: use a low-temperature plasma treatment device with air as the working gas, a treatment power of 150W, and a treatment time of 2 minutes to enhance the wettability and penetration of the subsequent grafting solution on the fiber surface.

[0037] Steps 2 through 5: Same as in Example 1. Example 4

[0038] Step 1: Use polyvinylidene fluoride microfiltration membrane as the substrate. Immerse the membrane sample in deionized water for 30 minutes, then remove and air dry at room temperature for later use.

[0039] Step 2: Same as Example 1.

[0040] Step 3: Completely immerse the polyvinylidene fluoride microfiltration membrane sample prepared in Step 1 in the grafting solution prepared in Step 2, and soak at 25°C for 30 minutes. Do not perform rolling.

[0041] Steps four and five: Same as in Example 1. Example 5

[0042] Step 1: Select polyethersulfone membrane as the substrate. Immerse the membrane sample in deionized water for 30 minutes, then remove and air dry at room temperature for later use.

[0043] Steps 2 to 5: Same as in Example 4. Example 6

[0044] Step 1: Select a polypropylene membrane as the substrate. Immerse the membrane sample in deionized water for 30 minutes, then remove it and allow it to air dry at room temperature for later use.

[0045] Steps 2 to 5: Same as in Example 4. Example 7

[0046] Step 1: Same as Example 1.

[0047] Step 2: Weigh acryloyloxyethyltrimethylammonium chloride and N,N'-methylenebisacrylamide (crosslinking agent) and dissolve them in deionized water to prepare a grafting solution with an acryloyloxyethyltrimethylammonium chloride mass concentration of 8% and a crosslinking agent mass concentration of 3% of the acryloyloxyethyltrimethylammonium chloride mass. Stir at room temperature until completely dissolved and set aside.

[0048] Step 3: Immerse the pure cotton woven fabric sample prepared in Step 1 into the grafting solution prepared in Step 2. After full immersion, roll it through a roller, controlling the residual rate to 85%. Repeat the immersion and rolling process 3 times. Roller pressure: 0.12 MPa; Rolling speed: 2.5 m / min, so that the grafting solution is evenly distributed and fully penetrates into the fiber.

[0049] Steps four and five: Same as in Example 1.

[0050] Comparative Example 1 (without added quaternary ammonium salt monomer) Step 1: Same as Example 1.

[0051] Step 2: No quaternary ammonium salt monomers are used; only deionized water is used as a control solution.

[0052] Step 3: Same as Example 1.

[0053] Step 4: Same as Example 1.

[0054] Step 5: Same as Example 1.

[0055] Comparative Example 2 (using a two-step process of irradiation followed by grafting) Step 1: Same as Example 1.

[0056] Step 2: Electron beam pre-irradiation. The cotton fabric is placed in a sealed bag while dry, vacuumed, and then filled with nitrogen for protection. Electron beam pre-irradiation is performed using an electron accelerator, with an absorbed dose of 10 kGy.

[0057] Step 3: Preparation of grafting solution. Prepare a 10% (w / w) acryloyloxyethyltrimethylammonium chloride grafting solution according to the method in Step 2 of Example 1.

[0058] Step 4: Immersion Grafting. The cotton fabric pre-irradiated in Step 2 is immersed in the grafting solution prepared in Step 3 and soaked at 25°C for 2 hours to allow the quaternary ammonium salt monomer to undergo a grafting reaction with the active sites generated by irradiation.

[0059] Step 5: Post-processing. Wash and dry according to the method in Step 5 of Example 1.

[0060] Comparative Example 3 (using non-quaternary ammonium salt antibacterial agents) Step 1: Same as Example 1.

[0061] Step 2: Preparation of grafting solution. Weigh out the nano silver sol (average silver particle size 20nm, mass concentration 100ppm) as an antibacterial agent and use it directly.

[0062] Step 3: Following the method in Step 3 of Example 1, immerse the cotton fabric in nano silver sol, controlling the pick-up rate to 80%.

[0063] Step 4: Same as Example 1.

[0064] Step 5: Same as Example 1.

[0065] Comparative Example 4: Physically impregnated control sample (unirradiated) Step 1: Use pure cotton woven fabric as the base material, and the rest is the same as in Example 1.

[0066] Step 2: Same as Example 1.

[0067] Step 3: Same as Example 1.

[0068] Step 4: The cotton fabric that has been impregnated in Step 3 is directly subjected to the post-treatment in Step 5 without electron beam irradiation.

[0069] Step 5: Same as Example 1.

[0070] As can be seen from the infrared spectrum, see Figure 1 In the treated pure cotton woven fabric of Example 1, 1730 cm of acryloyloxyethyltrimethylammonium chloride quaternary ammonium salt was found. -1 The vibrational peak of the carbonyl functional group at [location] indicates that acryloyloxyethyltrimethylammonium chloride has been covalently grafted into the pure cotton woven fabric; simultaneously, the 1640 cm⁻¹ of acryloyloxyethyltrimethylammonium chloride quaternary ammonium salt [is also present]. -1 The carbon-carbon double bond peaks at the point of application were almost absent in Example 1, which fully demonstrates that acryloyloxyethyltrimethylammonium chloride quaternary ammonium salt was grafted onto pure cotton fabric in the form of covalent bonds.

[0071] The antimicrobial properties were tested according to GB / T 20944.3-2008 "Evaluation of antimicrobial properties of textiles - Part 3: Shaking method". The test bacteria were Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922).

[0072] The grafted samples were subjected to 50 standard washes according to AATCC 61-2020 2A standard, which further demonstrated their good long-lasting antibacterial properties.

[0073] Table 1: Statistical results of grafting rate and antibacterial rate of different samples (* represents no grafting rate)

[0074] Grafting rate = (weight gain of the sample after grafting and drying / original weight of the sample) × 100%.

[0075] Table 2: Statistical results of antibacterial rate after different washing cycles for different samples

[0076] Based on the antibacterial performance test results of the above embodiments and comparative examples, it can be seen that the long-lasting antibacterial material grafted with quaternary ammonium salt by electron beam irradiation and its preparation method provided by the present invention exhibit excellent antibacterial performance on substrates of different morphologies: In Examples 1 to 7, the initial antibacterial rates of cotton fabrics, polyester fabrics, non-woven fabrics and polyvinylidene fluoride microfiltration membranes treated by the method of the present invention all reached more than 99% against Staphylococcus aureus and Escherichia coli; after 50 standard washes, the antibacterial rate of all sample examples remained above 97%, which fully demonstrates that the quaternary ammonium salt grafted in a covalent manner imparts durable and long-lasting antibacterial properties to the material. In contrast, the sample in Comparative Example 1 without the addition of quaternary ammonium salt monomers showed virtually no antibacterial ability, confirming that quaternary ammonium salt grafting is key to achieving antibacterial function. Comparative Example 2 employed a two-step process of irradiation followed by grafting, and its antibacterial effect (75%–80%) was significantly lower than that of the one-step process of this invention (around 99%), verifying the superiority of the one-step method in protecting irradiation-active sites and improving grafting efficiency. Comparative Example 3 used nano-silver as an antibacterial agent; although the initial inhibition rate reached 99%, after 10 cycles and 50... After several washes, the antibacterial rate gradually decreased, eventually plummeting to 52%–65%. Comparative Example 4, using direct physical impregnation without irradiation, achieved an initial antibacterial rate exceeding 98%. However, with increasing wash cycles, the physically adsorbed antibacterial monomers gradually detached, and after 50 washes, the antibacterial rate dropped sharply to 25%–30%, far below the 97% or higher of the present invention. This clearly demonstrates that quaternary ammonium salts grafted via covalent bonds exhibit significantly superior antibacterial durability compared to physically loaded quaternary ammonium salt monomers and nano-silver. In summary, this invention, through a one-step electron beam irradiation grafting process, successfully and covalently grafts quaternary ammonium salts onto the surface and interior of various substrates. The prepared antibacterial material possesses broad-spectrum, highly efficient, and long-lasting antibacterial properties, and the process is simple with a wide range of applicable substrates, representing a significant advancement over existing technologies.

[0077] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification.

Claims

1. A method for preparing a long-acting antibacterial material grafted with quaternary ammonium salt by electron beam irradiation, characterized in that, Includes the following steps: S1 involves cleaning and drying the polymer substrate for pretreatment; S2 is used to prepare a grafting solution containing quaternary ammonium salt monomers; S3 involves immersing the pretreated polymer substrate in the grafting solution prepared in step S2, and then fully wetting it through immersion, rolling, or soaking. S4 involves irradiating the polymer substrate after step S3 with an electron beam to initiate a grafting reaction between the quaternary ammonium salt monomer and the polymer substrate. S5 involves washing and drying the irradiated polymer substrate to remove unreacted monomers and homopolymers, thus obtaining the antibacterial material.

2. The preparation method according to claim 1, characterized in that, The polymer substrate is any one of pure cotton woven fabric, polyester fabric, polypropylene spunbond nonwoven fabric, polyvinylidene fluoride microfiltration membrane, polyethersulfone membrane or polypropylene membrane.

3. The preparation method according to claim 1, characterized in that, The cleaning in step S1 involves ultrasonically cleaning the substrate in deionized water for 10 to 30 minutes, and the drying involves drying in an oven at 50 to 80°C for 1 to 3 hours.

4. The preparation method according to claim 1, characterized in that, The quaternary ammonium salt monomer mentioned in step S2 is one or more of the following: methacryloyloxyethyltrimethylammonium chloride, methacryloyloxyethyltrimethylammonium bromide, acryloyloxyethyltrimethylammonium chloride, acryloyloxyethyltrimethylammonium bromide, dimethyl diallyl ammonium chloride, dimethyl diallyl ammonium bromide, allyl trimethylammonium chloride, allyl trimethylammonium bromide, (3-chloro-2-hydroxypropyl)trimethylammonium chloride, and 2,3-epoxypropyltrimethylammonium chloride.

5. The preparation method according to claim 4, characterized in that, The mass concentration of the quaternary ammonium salt monomer in the grafting solution in step S2 is 5% to 20%.

6. The preparation method according to claim 1, characterized in that, The impregnation described in step S3 involves immersing the substrate in the grafting solution until fully wetted, then rolling it with rollers to control the roll residue rate at 70% to 90%, and repeating the impregnation 1 to 3 times. For polymer membrane materials, the impregnation method involves completely immersing the membrane material in the grafting solution for 20 to 60 minutes without rolling.

7. The preparation method according to claim 1, characterized in that, The absorbed dose of electron beam irradiation in step S4 is 5–15 kGy, and the irradiation is carried out under nitrogen protection.

8. The preparation method according to claim 1, characterized in that, The washing in step S5 involves repeatedly washing with deionized water 3 to 10 times, each time for 5 to 20 minutes; the drying involves drying in an oven at 50 to 80°C until constant weight.

9. The preparation method according to claim 1, characterized in that, The grafting solution in step S2 also contains a crosslinking agent, which is N,N'-methylenebisacrylamide, and its mass is 1% to 5% of the mass of the quaternary ammonium salt monomer.

10. The preparation method according to claim 1, characterized in that, When the polymer substrate is a hydrophobic substrate, after the cleaning and drying pretreatment in step S1, the step of plasma pretreatment of the substrate is further included. The plasma treatment is low-temperature plasma treatment, the working gas is air, the treatment power is 100-150 W, and the treatment time is 2-3 minutes.

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