Highly efficient antibacterial modified silica gel and preparation method thereof

Abstract

The application discloses a kind of high-efficiency antibacterial modified silica gel and preparation method thereof, with food-grade liquid silica gel as matrix, using polylactic acid-polylysine block copolymer as degradable biological antibacterial unit, through silane coupling agent in situ covalent graft modification under room temperature ultraviolet light, make antibacterial unit firmly bonded in silica gel molecular chain.The obtained silica gel antibacterial rate is greater than or equal to 99.9%, and there is no precipitation after multiple water boiling disinfection, the antibacterial unit is biodegradable, the process is green, low energy consumption, no harmful substance residue, high safety, suitable for infant nipple, dental cement and other entry products, solve the problems such as easy precipitation, non-degradable and environmental unfriendly of traditional antibacterial silica gel.

Description

Technical Field

[0001] This invention relates to the field of silicone material modification technology, specifically to a highly efficient antibacterial modified silicone and its preparation method. Background Technology

[0002] Infant pacifiers, teething toys, and other ingestible silicone products must simultaneously meet the requirements of antibacterial properties, safety, and environmental friendliness; however, existing products face significant technological bottlenecks. Traditional antibacterial silicones often use antibacterial agents such as silver ions and quaternary ammonium salts. These agents have poor compatibility with the silicone matrix and are prone to precipitation due to phase separation or molecular migration, which not only reduces the long-term effectiveness of antibacterial action but may also pose health risks. Furthermore, most antibacterial agents are non-degradable, creating an environmental burden after disposal. Some biodegradable silicones suffer from insufficient antibacterial efficiency and high-temperature, high-energy-consumption manufacturing processes, making it difficult to balance antibacterial performance with green production requirements. In addition, existing products often face problems such as insufficient cross-linking leading to accelerated diffusion of antibacterial agents or poor compatibility causing a decline in mechanical properties, failing to meet the stringent requirements for migration and safety in food contact materials standards. Therefore, developing a highly efficient antibacterial modified silicone with covalently bonded antibacterial units, no precipitation risk, biodegradability, and a green manufacturing process has become a key need to solve the existing technological challenges. Summary of the Invention

[0003] To address the problems of existing antibacterial agents for infants and young children being prone to leaching and non-degradable, and the difficulty in simultaneously achieving antibacterial properties and ensuring safety and environmental friendliness, as well as the high energy consumption of the preparation process, this invention proposes a highly efficient antibacterial modified silicone and its preparation method. This modified silicone uses polylactic acid-polylysine block copolymers as degradable antibacterial units. Through silane coupling agent-mediated room temperature ultraviolet covalent grafting technology, the antibacterial units are firmly bonded to the silicone matrix, simultaneously achieving high antibacterial rates, no leaching, and degradability. The process is green, low-energy, safe, and compliant, making it suitable for infant and young children's ingestible products.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A highly efficient antibacterial modified silica gel, wherein the silica gel is prepared from the following raw materials in parts by weight: 100 parts of food-grade liquid silicone matrix, 1-3 parts of biodegradable bio-based antibacterial unit, 2-4 parts of grafted bridge and 0.005-0.03 parts of UV initiator; The biodegradable bio-based antibacterial unit is a polylactic acid-polylysine block copolymer (PLA-b-PLL), the grafting bridge is γ-methacryloyloxypropyltrimethoxysilane, and the UV initiator is food-grade 2,2-dimethoxy-2-phenylacetophenone. The biodegradable bio-based antibacterial unit is covalently bonded to the silica matrix through the grafting bridge. The antibacterial modified silica has an antibacterial rate of ≥99.9% against Escherichia coli and Staphylococcus aureus, and no antibacterial unit is precipitated after boiling in water 100 times.

[0005] Optionally, in the polylactic acid-polylysine block copolymer, the molecular weight of the polylactic acid segment is 2000-5000 Da, the molecular weight of the polylysine segment is 1000-3000 Da, and the mass ratio of polylactic acid to polylysine is 3:1-1:1.

[0006] Optionally, the antibacterial modified silica gel has a degradation rate of 60%-90% after being buried in soil for 6 months, and the degradation products are lactic acid and lysine, without any toxic impurities; the degradation conditions are 25-30℃, field soil environment, and moisture content of 15-25%.

[0007] Optionally, the silicone matrix has a Shore 00 hardness of 0-10°.

[0008] Optionally, the polylactic acid-polylysine block copolymer is obtained by ring-opening polymerization of polylactic acid monomers and polylysine monomers, wherein the polylactic acid is a food-grade biodegradable material and the polylysine is ε-polylysine.

[0009] Optionally, the antibacterial modified silicone has an elongation at break of 850-1000%, a tensile strength of 3.5-5.0 MPa, no VOC residue, a total migration of 5-10 mg / dm2, and a heavy metal Pb residue of 0.1-1 mg / kg.

[0010] Optionally, the preparation method of the aforementioned highly efficient antibacterial modified silica gel includes the following specific preparation steps: S1. Mix polylactic acid monomer and polylysine monomer at a mass ratio of 1:1-3:1, add ring-opening polymerization catalyst stannous octoate, the amount of catalyst is 0.1-0.3% of the total mass of monomer, and react under nitrogen protection at 120-140℃ with stirring at 200-400 r / min for 8-12 h. After the reaction is completed, precipitate with 75-95% ethanol for 2-4 h and vacuum dry at 60℃ for 12-16 h to obtain polylactic acid-polylysine block copolymer; S2. Take a food-grade liquid silica matrix with a viscosity of 5000-8000 mPa∙s, place it in a sealed stirring vessel, add γ-methacryloyloxypropyltrimethoxysilane, and stir for 20-30 min at room temperature and a speed of 300-500 r / min to make the grafted bridges uniformly dispersed and activate the hydroxyl groups on the surface of the silica matrix. S3. Add the polylactic acid-polylysine block copolymer and 2,2-dimethoxy-2-phenylacetophenone prepared in S1 to the silica gel system activated in S2. First, ultrasonically disperse the mixture at room temperature (25-30℃) with a power of 200-300W and a frequency of 30-50kHz for 15-20 minutes. Then, place the mixture under 365nm ultraviolet light irradiation, controlling the irradiation power at 250-350W, the irradiation distance at 8-12cm, and the reaction temperature at 25-30℃ for 30-60 minutes to initiate the in-situ covalent grafting reaction. During this period, stir the mixture every 10-15 minutes at a speed of 150-250r / min for 30-60 seconds each time to ensure uniform reaction. S4. Inject the mixture after the grafting reaction in S3 into the mold of infant products and place it in a vulcanizing machine. Vulcanize for 15-25 minutes at a temperature of 90-110℃ and a pressure of 0.2-0.4MPa. After vulcanization, allow it to cool naturally to room temperature. After demolding, deburr, clean, and dry at 60-80℃ for 2-4 hours to obtain high-efficiency antibacterial modified silicone.

[0011] The beneficial effects of this invention are: This invention provides a highly efficient antibacterial modified silicone that achieves a synergistic balance of antibacterial properties, safety, and environmental friendliness in infant and toddler food products. By using a specific ratio of polylactic acid-polylysine block copolymer and silane coupling agent, a stable bond structure is constructed through room temperature ultraviolet light covalent grafting, completely resolving the issue of antibacterial agent precipitation. The antibacterial rate is ≥99.9% and long-lasting. The bio-based antibacterial unit ensures a 60-90% degradation rate after 6 months of soil burial, with non-toxic degradation products. This silicone exhibits excellent compatibility with the matrix, meets mechanical property standards, and its manufacturing process is green and low-consumption, leaving no VOC residue. It complies with food contact safety standards, is suitable for infant and toddler food products, and balances safety and environmental friendliness. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0013] Example 1: A highly efficient antibacterial modified silica gel of Example 1, the silica gel is prepared from the following raw materials in parts by weight: 100 parts of food-grade liquid silica matrix, 2 parts of biodegradable bio-based antibacterial unit (PLA 3000Da / PLL 2000Da, mass ratio 2:1), 3 parts of grafted bridge: γ-methacryloyloxypropyltrimethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone. The specific preparation steps of a high-efficiency antibacterial modified silicone in this embodiment are as follows: S1. Polylactic acid monomer and polylysine monomer are mixed at a mass ratio of 2:1. The ring-opening polymerization catalyst stannous octoate is added, and the amount of catalyst is 0.3% of the total mass of monomers. Under nitrogen protection and at 130°C, the mixture is stirred at 300 r / min for 10 h. After the reaction is completed, the mixture is precipitated with 80% ethanol for 3 h and vacuum dried at 60°C for 14 h to obtain polylactic acid-polylysine block copolymer, which is a biodegradable bio-based antibacterial unit. S2. Take a food-grade liquid silica matrix with a viscosity of 6000 mPa∙s, place it in a sealed stirring vessel, add γ-methacryloyloxypropyltrimethoxysilane, and stir for 25 min at room temperature and a speed of 400 r / min to uniformly disperse the grafted bridges and activate the hydroxyl groups on the surface of the silica matrix, thus obtaining the activated silica system. S3. Add the polylactic acid-polylysine block copolymer and 2,2-dimethoxy-2-phenylacetophenone prepared in S1 to the silica gel system activated in S2. First, ultrasonically disperse the mixture at room temperature (25°C) with a power of 250W and a frequency of 40kHz for 18 minutes. Then, place the mixture under 365nm ultraviolet light irradiation, controlling the irradiation power to be 300W, the irradiation distance to be 10cm, and the reaction temperature to be 25°C. Irradiate for 45 minutes to initiate an in-situ covalent grafting reaction. During this period, stir the mixture at a speed of 200r / min every 12 minutes for 45 seconds each time to ensure uniform reaction. S4. The mixture after the grafting reaction in S3 is injected into the mold of infant products and placed in a vulcanizing machine. It is vulcanized for 20 minutes at a temperature of 100℃ and a pressure of 0.3MPa. After vulcanization, it is naturally cooled to room temperature. After demolding, it is deburred, cleaned, and dried at 60℃ for 3 hours to obtain a high-efficiency antibacterial modified silicone product.

[0014] Example 2: A highly efficient antibacterial modified silica gel of this Example 2, the silica gel is prepared from the following raw materials in parts by weight: 100 parts of food-grade liquid silica matrix, 1 part of biodegradable bio-based antibacterial unit (PLA 3000Da / PLL 2000Da, mass ratio 2:1), 3 parts of grafted bridge: γ-methacryloyloxypropyltrimethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone. The specific preparation method of the high-efficiency antibacterial modified silicone in this embodiment is the same as that in Example 1, except that the biodegradable bio-based antibacterial unit is changed to 1 part.

[0015] Example 3: A highly efficient antibacterial modified silica gel of Example 3, the silica gel is prepared from the following raw materials in parts by weight: 100 parts of food-grade liquid silica matrix, 3 parts of biodegradable bio-based antibacterial unit (PLA 3000Da / PLL2000Da, mass ratio 2:1), 3 parts of grafted bridge: γ-methacryloyloxypropyltrimethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone. The specific preparation method of the high-efficiency antibacterial modified silicone in this embodiment is the same as that in Example 1, except that the biodegradable bio-based antibacterial unit is changed to 3 parts.

[0016] Comparative Example 1: The silicone in Comparative Example 1 was prepared from the following parts by weight of raw materials: 100 parts of food-grade liquid silica matrix, 2 parts of silver ion antibacterial agent, 3 parts of grafted bridge: γ-methacryloyloxypropyltrimethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone; The specific preparation method of the silica gel in this comparative example is the same as that in Example 1.

[0017] Comparative Example 2: The silicone in Comparative Example 2 was prepared from the following parts by weight of raw materials: 100 parts of food-grade liquid silica matrix, 2 parts of biodegradable bio-based antibacterial unit (PLA 3000Da / PLL 2000Da, mass ratio 2:1), 3 parts of grafted bridge: γ-methacryloyloxypropyltrimethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone. In this comparative example, the preparation method of the silica gel is the same as that in Example 1, except that the S2 activation step is omitted, and the S3 step is not subjected to ultraviolet light irradiation, but is directly vulcanized after ultrasonic dispersion.

[0018] Comparative Example 3: The silica gel in Comparative Example 3 was prepared from the following parts by weight of raw materials: 100 parts of food-grade liquid silica matrix, 2 parts of biodegradable bio-based antibacterial unit (PLA 3000Da / PLL2000Da, mass ratio 2:1), 3 parts of grafted bridge: γ-aminopropyltriethoxysilane, and 0.015 parts of UV initiator: 2,2-dimethoxy-2-phenylacetophenone. In this comparative example, the preparation method of the silica gel is the same as in Example 1, except that the graft bridge is replaced with γ-aminopropyltriethoxysilane.

[0019] Performance testing 1. Test of antibacterial unit exudation Referring to GB 31604.8-2016 "National Food Safety Standard - Determination of Total Migration of Food Contact Materials and Articles", the experimental steps for testing the amount of antimicrobial unit leaching are as follows: Take the silicone products prepared in the examples and comparative examples, cut a 10cm×10cm sample without damage or stains (ensuring the sample surface area is 0.01m2), ultrasonically clean it 3 times with deionized water (5min each time) and then air dry it; completely immerse the sample in a sealed container containing 200mL of deionized water (simulating the scenario of infant ingestion contact, with a liquid-to-solid ratio of 20mL / cm2), and place it in a 40℃ constant temperature water bath for 24h. After the sample was removed, the soaking solution was filtered through a 0.45 μm organic phase filter membrane. The PLA-b-PLL antibacterial unit in the filtrate was quantitatively analyzed using high performance liquid chromatography (HPLC, C18 column, mobile phase methanol-water = 60:40, flow rate 1.0 mL / min, detection wavelength 220 nm). A blank control group (containing only 200 mL of deionized water, treated under the same conditions) was set up. The amount of antibacterial unit precipitated (unit: mg / dm2) was calculated by subtracting the blank value. If the detection value was lower than the instrument detection limit (0.01 mg / dm2), it was judged as "not detected".

[0020] Table 1. Test data on the amount of antibacterial units precipitated in different samples.

[0021] In Examples 1-3, the amount of antibacterial unit precipitated was <0.01 mg / dm2 (not detected), while in Comparative Examples 1-3, there was significant precipitation (0.42-1.35 mg / dm2), proving that the covalent grafting process of the present invention can effectively avoid the migration of antibacterial units, solve the precipitation risk of traditional products, and meet the safety needs of infants and young children.

[0022] 2. Antibacterial performance test Referring to GB / T 31402-2015 "Test Method for Antibacterial Properties of Plastic Surfaces", the antibacterial performance test procedure is as follows: Take silicone products prepared in the examples and comparative examples, cut 50mm×50mm undamaged samples, sterilize them with high-pressure steam at 121℃ for 20min, and then cool them to room temperature; take Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25922) at a concentration of 1×106 CFU / mL respectively. 0.2 mL of bacterial suspension (6538) was evenly added to the sample surface and covered with a sterile polyethylene film (40 mm × 40 mm) to ensure full contact between the bacterial suspension and the sample. The sample was then incubated in a constant temperature and humidity chamber at 37°C and 90% relative humidity for 24 h. After incubation, 10 mL of sterile physiological saline was added to the sample surface. The sample was repeatedly wiped with a sterile cotton swab and eluted by shaking. The eluent was collected and serially diluted. 0.1 mL of the eluent at an appropriate dilution was evenly spread on nutrient agar medium and incubated at 37°C for 24 h. The colony count was then counted. A blank control group (no sample, only bacterial suspension and film cultured under the same conditions) and a negative control group (food-grade silica gel without antibacterial treatment, operated in the same manner) were set up. The antibacterial rate was calculated using the formula "Antibacterial rate (%) = (colony count in control group - colony count in sample group) / colony count in control group × 100%". Three parallel samples were set up for each group of experiments, and the average value was taken as the final result.

[0023] Table 2. Test data on antibacterial properties of different samples

[0024] Examples 1-3 showed antibacterial rates of ≥99.9% against Escherichia coli and Staphylococcus aureus, with excellent stability, significantly better than Comparative Examples 2-3, and slightly higher than Comparative Example 1 (silver ions), confirming that the bio-based antibacterial unit and covalent grafting process work synergistically to achieve highly efficient and long-lasting antibacterial effects.

[0025] 3. Biodegradability test Based on the national standard GB / T 19277.1-2011 "Determination of Biodegradability of Plastics under Controlled Composting Conditions - Part 1: General Rules" and the characteristics of silica gel materials, the experimental steps for testing biodegradability are as follows: Take silica gel products prepared in the examples and comparative examples, cut 10mm×10mm×2mm bubble-free samples (3 parallel samples per group, accurately weigh the initial mass m0), ultrasonically sterilize with 75% ethanol solution for 10 min, and then vacuum dry to constant weight; select farmland surface soil (pH... 6.5-7.5%, organic matter content 1.5-2.5%, humidity 60-70% field water holding capacity), after passing through a 2mm sieve, was mixed with the sample at a mass ratio of 100:1 and placed into a degradation culture bottle with vents. A blank control group (soil only, no sample) and a positive control group (polylactic acid film of known easily degradable material, same specifications) were also set up. The culture bottles were placed in a constant temperature and humidity incubator at 25±2℃ and 70±5% relative humidity for 6 months in the dark, during which deionized water was added every 15 days to maintain stable soil moisture. After the culture was completed, The mixture was separated into sample residues using a 2mm sieve, and the soil particles were removed by rinsing with deionized water. The mixture was then vacuum dried at 60℃ to constant weight, and the residual mass m1 was accurately weighed. At the same time, the initial total organic carbon content (TOC0) and the residual total organic carbon content (TOC1) of the sample were determined using an elemental analyzer. The degradation rate was calculated according to the formula "biodegradation rate (%) = (1 - (m1 × TOC1) / (m0 × TOC0)) × 100%". The positive control group was deemed valid only if the degradation rate was ≥70% after 6 months. The result was the average of 3 parallel samples.

[0026] Table 3. Test data on biodegradability of different samples

[0027] Examples 1-3 show a degradation rate of 63.1%-88.9% after 6 months, which is much higher than that of Comparative Example 1 (3.8%). The positive control group verification test is effective, indicating that the material of the present invention has excellent degradability, which is in line with the environmental protection trend and solves the pollution problem of traditional products.

[0028] 4. Heavy metal residue test Based on the national standard GB 31604.9-2016 "National Food Safety Standard - Determination of Heavy Metals in Food Contact Materials and Products - Food Simulators" and the specific requirements of GB 4806.16-2025 "Specific Requirements for Silicone Products", the experimental steps for heavy metal residue (migration) testing are as follows: Take the silicone products prepared in the examples and comparative examples, cut 5mm×5mm undamaged samples (3 parallel samples per group, accurately weighed 0.2000g), ultrasonically clean them with 75% ethanol for 5 minutes, and then air dry them; completely immerse the samples in 20mL of... Migration tests were conducted by heating a sealed container of 4% acetic acid food simulant (volume fraction, simulating contact with acidic complementary foods for infants) in a 100℃ boiling water bath for 30 min, followed by immersion in a 25℃ constant temperature environment for 24 h. After migration, the supernatant was filtered through a 0.45 μm filter membrane, and inductively coupled plasma mass spectrometry (ICP-MS) was used to quantitatively analyze 23 heavy metal elements, including lead (Pb), cadmium (Cd), and arsenic (As), in the filtrate. A blank control group (containing only 20 mL of 4% acetic acid, treated under the same conditions) was also set up. By plotting standard curves for each heavy metal (lead standard curve concentration 0-50 μg / L, correlation coefficient R2≥0.999), subtracting blank values, and calculating the heavy metal migration amount (unit: mg / kg), the result was taken as the average of 3 parallel samples, and the determination was based on the limits of GB 4806.16-2025 (lead, cadmium, and arsenic ≤0.01 mg / kg).

[0029] Table 4. Test data on heavy metal residues in different samples

[0030] In Examples 1-3, the migration levels of lead, cadmium, and arsenic all met the requirements of GB 4806.16-2025 (lead < 0.001 mg / kg, cadmium and arsenic not detected), while the migration level of lead in Comparative Example 1 exceeded the standard by 8.5 times, highlighting the safety advantage of the bio-based antibacterial system without heavy metal risk.

[0031] 5. Mechanical property testing Referring to GB / T 528-2009 "Determination of Tensile Stress-Strain Properties of Vulcanized Rubber or Thermoplastic Rubber", the experimental steps for mechanical property testing are as follows: Take silicone products prepared in the examples and comparative examples, and cut type 1 specimens (gauge width 6mm, thickness 2mm, effective gauge length 25mm) using a dumbbell-shaped cutter. Prepare 5 parallel samples for each group, and conditioned them for 24 hours at 23±2℃ and 50±5% relative humidity. Use a universal testing machine, set the tensile speed to 500mm / min, and clamp both ends of the specimen in the upper and lower clamps respectively (clamping distance...). To ensure the gauge length is not under stress, start the equipment to conduct a tensile test, and record the maximum tensile force and the gauge length at which the specimen breaks in real time. Calculate the results using the formulas "Tensile strength (MPa) = Maximum tensile force (N) / Initial cross-sectional area of ​​the specimen (mm²)" and "Elongation at break (%) = (Gazelle length at break - Initial gauge length) / Initial gauge length × 100%". After removing outliers (deviation from the average value ±10%), take the average value of the remaining valid specimens as the final data. The relative standard deviation (RSD) of parallel samples must be ≤3%.

[0032] Table 5. Test data of mechanical properties of different samples

[0033] Examples 1-3 have tensile strengths of 4.0-4.5 MPa and elongation at break of 865%-955%, which meet the requirements for infant products. Moreover, their performance stability is better than that of the comparative examples, indicating that the antibacterial modification process does not damage the silicone structure and achieves a synergistic effect of antibacterial, safety and mechanical properties.

[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly efficient antibacterial modified silicone, characterized in that, The silicone is prepared from the following raw materials in parts by weight: 100 parts of food-grade liquid silica matrix, 1-3 parts of biodegradable bio-based antibacterial unit, 2-4 parts of grafted bridge and 0.005-0.03 parts of UV initiator; The biodegradable bio-based antibacterial unit is a polylactic acid-polylysine block copolymer, the grafting bridge is γ-methacryloxypropyltrimethoxysilane, and the UV initiator is food-grade 2,2-dimethoxy-2-phenylacetophenone. The biodegradable bio-based antibacterial unit is covalently bonded to the silica matrix through the grafting bridge. The antibacterial modified silica has an antibacterial rate of ≥99.9% against Escherichia coli and Staphylococcus aureus, and no antibacterial unit is precipitated after boiling in water 100 times.

2. The high-efficiency antibacterial modified silica gel according to claim 1, characterized in that, In the polylactic acid-polylysine block copolymer, the molecular weight of the polylactic acid segment is 2000-5000 Da, the molecular weight of the polylysine segment is 1000-3000 Da, and the mass ratio of polylactic acid to polylysine is 3:1-1:

1.

3. The high-efficiency antibacterial modified silica gel according to claim 1, characterized in that, The antibacterial modified silica gel has a degradation rate of 60%-90% after being buried in soil for 6 months. The degradation products are lactic acid and lysine, with no toxic impurities. The degradation conditions are 25-30℃, field soil environment, and moisture content of 15-25%.

4. The high-efficiency antibacterial modified silica gel according to claim 1, characterized in that, The silicone matrix has a Shore 00 hardness of 0-10°.

5. The high-efficiency antibacterial modified silica gel according to claim 1, characterized in that, The polylactic acid-polylysine block copolymer is obtained by ring-opening polymerization of polylactic acid monomers and polylysine monomers. The polylactic acid is a food-grade biodegradable material, and the polylysine is ε-polylysine.

6. The high-efficiency antibacterial modified silica gel according to claim 1, characterized in that, The antibacterial modified silicone has an elongation at break of 850-1000%, a tensile strength of 3.5-5.0 MPa, no VOC residue, a total migration of 5-10 mg / dm2, and a heavy metal Pb residue of 0.1-1 mg / kg.

7. A method for preparing a high-efficiency antibacterial modified silica gel, used to prepare the high-efficiency antibacterial modified silica gel as described in any one of claims 1-6, characterized in that, The specific preparation steps are as follows: S1. Mix polylactic acid monomer and polylysine monomer at a mass ratio of 1:1-3:1, add ring-opening polymerization catalyst stannous octoate, the amount of catalyst is 0.1-0.3% of the total mass of monomer, and react under nitrogen protection at 120-140℃ with stirring at 200-400 r / min for 8-12 h. After the reaction is completed, precipitate with 75-95% ethanol for 2-4 h and vacuum dry at 60℃ for 12-16 h to obtain polylactic acid-polylysine block copolymer, which is a biodegradable bio-based antibacterial unit; S2. Take a food-grade liquid silica matrix with a viscosity of 5000-8000 mPa∙s, place it in a sealed stirring vessel, add γ-methacryloyloxypropyltrimethoxysilane, and stir for 20-30 min at room temperature and a speed of 300-500 r / min to make the grafted bridges uniformly dispersed and activate the hydroxyl groups on the surface of the silica matrix. S3. Add the polylactic acid-polylysine block copolymer and 2,2-dimethoxy-2-phenylacetophenone prepared in S1 to the silica gel system activated in S2. First, ultrasonically disperse the mixture at room temperature (25-30℃) with a power of 200-300W and a frequency of 30-50kHz for 15-20 minutes. Then, place the mixture under 365nm ultraviolet light irradiation, controlling the irradiation power at 250-350W, the irradiation distance at 8-12cm, and the reaction temperature at 25-30℃ for 30-60 minutes to initiate the in-situ covalent grafting reaction. During this period, stir the mixture every 10-15 minutes at a speed of 150-250r / min for 30-60 seconds each time to ensure uniform reaction. S4. Inject the mixture after the grafting reaction in S3 into the mold of infant products and place it in a vulcanizing machine. Vulcanize for 15-25 minutes at a temperature of 90-110℃ and a pressure of 0.2-0.4MPa. After vulcanization, allow it to cool naturally to room temperature. After demolding, deburr, clean, and dry at 60-80℃ for 2-4 hours to obtain high-efficiency antibacterial modified silicone.

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