Antibacterial food-grade plate and preparation method thereof
By introducing nano-hydroxyapatite modification into polypropylene sheets, chemical bonding with natural antimicrobial peptides, and synergistic effects of plant active ingredients, the problem of easy loss of antimicrobial agents was solved, achieving the stability and safety of antimicrobial food-grade sheets and improving their applicability in food contact materials.
Patent Information
- Application Number
- CN202512017342.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-24
AI Technical Summary
In existing technologies, antibacterial agents in polypropylene sheets are easily dispersed and lost in a non-polar matrix, resulting in uneven antibacterial efficacy and making it difficult to meet the requirements for long-lasting antibacterial properties and mechanical stability of food-grade sheets.
A composite additive is used, which is chemically bonded to the natural antimicrobial peptide ε-polylysine after surface modification of nano-hydroxyapatite. Combined with natural plant active ingredients such as pepper seed and Cnidium monnieri extract, a stable antimicrobial system is formed. The antimicrobial agent is fixed to the carrier through chemical bonding to avoid loss.
It achieves the stable presence and release of antibacterial components in the board, improves the antibacterial properties and mechanical stability of the board, reduces the environmental impact, and meets food safety standards.
Smart Images
Figure CN121718095A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of functional board technology, specifically to an antibacterial food-grade board and its preparation method. Background Technology
[0002] Food-grade sheets are key materials that come into direct contact with food in the food processing, catering, and packaging industries. They must meet strict hygiene and safety standards. Ideal food-grade sheets not only need to have excellent mechanical strength, but also long-lasting antibacterial properties to inhibit the growth of microorganisms. Polypropylene resin is one of the commonly used matrix resins for food-grade sheets and other contact materials because it is non-toxic, odorless, has low density, good heat resistance, and excellent chemical stability.
[0003] In the prior art, to impart antibacterial function to polypropylene sheets, the method of directly blending antibacterial agents with polypropylene resin and then processing them into shape is usually adopted. However, inorganic antibacterial agents are easily dispersed and lost in the non-polar polypropylene matrix, resulting in uneven antibacterial efficacy. Based on this, the present invention provides an antibacterial food-grade sheet and its preparation method. Summary of the Invention
[0004] The purpose of this invention is to provide an antibacterial food-grade board and its preparation method. The antibacterial food-grade board prepared by this invention not only has good antibacterial properties, but also good mechanical stability and food safety, effectively improving the applicability of the board in the field of food contact materials.
[0005] To achieve the above objectives, the present invention provides the following technical solution: In one aspect, an antibacterial food-grade board comprises the following raw materials in parts by weight: 100 parts polypropylene resin, 5-15 parts composite additives, 8-12 parts functional additives, 0.3-0.8 parts antioxidant 1010 and 0.5-1.5 parts calcium stearate; The raw materials for the composite additive include nano-hydroxyapatite, aminosulfonic acid solution, and reaction solution. The raw materials for the functional additives include Sichuan pepper seeds, anhydrous ethanol, Cnidium monnieri extract, and additives. Further, the composite additive is prepared by the following method: nano-hydroxyapatite and deionized water are mixed at a mass ratio of 1:(7-9) to obtain a first mixture. 0.3-0.5% of the mass of the first mixture is added to the mixture, and it is ultrasonically dispersed for 20-30 min. Then, an 8% (w / w) aminosulfonic acid aqueous solution is added, and the mixture is stirred at 50-60℃ for 25-35 min. After filtration, the filter residue is mixed with the reaction solution at a mass ratio of 1:(2.8-3.2), and the mixture is reacted at 50-60℃ for 1-1.2 h. Finally, it is spray-dried to obtain the composite additive, wherein the volume of the aminosulfonic acid aqueous solution is 6 times the mass of the nano-hydroxyapatite.
[0006] Further, the reaction solution is prepared by the following method: ε-polylysine powder, deionized water and anhydrous ethanol are mixed at a solid-liquid ratio of (1.1-1.3) g:(87-89) mL:10 mL to obtain a second mixture. 2.5-3% of tea saponin by mass of the second mixture is added, followed by 0.17-0.19% of 1,3-dicyclohexylcarbodiimide by mass of the second mixture. The mixture is reacted at 43-47℃ for 30-35 min to obtain the reaction solution.
[0007] Furthermore, the tea saponin needs to be pretreated before the reaction, including the following steps: tea saponin and anhydrous acetone are mixed at a solid-liquid ratio of 1g:(10-12)mL, maleic anhydride of 20-25% by weight of tea saponin is added, and then p-toluenesulfonic acid is added. The mixture is stirred at 55-60℃ and 180-200rpm for 3.5-4h to obtain a third mixture. The third mixture is added to deionized water and stirred for 1-1.5h. The mixture is filtered to obtain a filter residue. The filter residue is washed twice with sodium bicarbonate aqueous solution and then washed with deionized water until neutral. The washed filter residue is vacuum dried at 60-65℃ to constant weight to obtain pretreated tea saponin.
[0008] Further, the functional additive is prepared by the following method: Sichuan pepper seeds are pulverized and passed through a 60-mesh sieve to obtain Sichuan pepper seed powder, which is then transferred to a supercritical carbon dioxide reactor. 3-5% of the mass of the Sichuan pepper seed powder in anhydrous ethanol is added, and the mixture is reacted at 32-35 MPa and 42-46℃ for 1.2-1.5 h. The reaction product is collected from the separation vessel to obtain intermediate product A. Intermediate product A is mixed with Cnidium monnieri extract at a mass ratio of 1:(0.8-1.0), and 1-2% of the mass of the intermediate product in glycerol is added. The mixture is stirred at 50℃ for 30 min to obtain intermediate product B. Intermediate product B is mixed with additives at a mass ratio of 1:(3.8-4.2), and the mixture is reacted in a water bath at 58-62℃ for 1.5-1.8 h under nitrogen protection to obtain the functional additive.
[0009] Further, the additive is prepared by the following method: Eucommia ulmoides gum precursor and limonene are mixed at a mass ratio of (3.8-4.2):(5.8-6.2) to obtain a mixture. Triethanolamine accounting for 0.3% of the total mass of the mixture is added, and the mixture is stirred at 150-180 rpm at 25-30℃ for 20-25 minutes. After stirring, the mixture is ultrasonically treated for 5-8 minutes to obtain the additive.
[0010] Further, the Eucommia ulmoides gum precursor is prepared by the following method: Eucommia ulmoides gum and anhydrous ethanol are mixed at a solid-liquid ratio of 1g:(8-10)mL, stirred at 50-60℃ for 10min, and then peracetic acid solution accounting for 30-35% of the mass of Eucommia ulmoides gum is added dropwise, while sodium dihydrogen phosphate accounting for 0.5-1.0% of the mass of Eucommia ulmoides gum is added. The mixture is stirred at 30-40℃ at a speed of 150-180rpm for 2.5-3h. After the reaction is completed, sodium bicarbonate solution with a mass concentration of 5% is added to adjust the pH to 6.5-7.0. After standing and separating into layers, the aqueous phase is collected and dried at 60-65℃ to constant weight to obtain the Eucommia ulmoides gum precursor, wherein the mass concentration of peracetic acid is 30%.
[0011] Furthermore, the parameters for the spray drying process are: inlet air temperature 120-130℃ and outlet air temperature 60-70℃.
[0012] Furthermore, the mass of the p-toluenesulfonic acid is 0.8-1.2% of the mass of the tea soap, the volume of the deionized water is 3-4 times the volume of the third mixture, and the mass concentration of the sodium bicarbonate aqueous solution is 5%.
[0013] Secondly, the present invention provides a method for preparing antibacterial food-grade boards, comprising the following steps: Step 1: Add polypropylene resin, composite additives, functional auxiliaries, antioxidant 1010 and calcium stearate to a high-speed mixer and mix at room temperature for 5-10 minutes to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, and after melt extrusion, water cooling, and pelletizing, obtain antibacterial masterbatch. The processing temperature of the twin-screw extruder is: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 175-185℃, Die head 170-180℃, and screw speed 300-400 rpm. Step 3: Transfer the antibacterial masterbatch into a flat vulcanizing machine, hot press at 190℃, hot press at 10MPa, hot press for 8 minutes, and hot press to form antibacterial food-grade boards.
[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the composite additive uses nano-hydroxyapatite as a carrier. It is first modified with aminosulfonic acid to introduce active sites, and then chemically bonded with the natural cationic antimicrobial peptide ε-polylysine in the reaction solution. ε-polylysine can destroy the integrity of the microbial cell membrane structure, causing leakage of cell contents and death. Meanwhile, tea saponin works synergistically on the cell membrane lipid structure to further enhance its permeability changes and structural disintegration. This makes the final additive avoid the problem of easy loss of antimicrobial agents due to simple physical blending, and realizes the stable existence and release of antimicrobial components in the board.
[0015] 2. In this invention, the functional additives introduce natural plant active ingredients to give the board antibacterial properties. Among them, the oily active ingredients in pepper seeds have antibacterial and hydrophobic properties, and can work together with the Cnidium monnieri extract, which is rich in antibacterial compounds such as furanocoumarins, to destroy the cell membrane and metabolic processes of microorganisms. The Eucommia ulmoides gum precursor, after oxidative modification, enhances the compatibility and film-forming properties with the matrix resin. While improving the antibacterial properties of the board, it also improves the overall toughness and aging resistance of the board.
[0016] 3. In this invention, the antibacterial functional additive mainly uses natural products ε-polylysine, plant extracts, and biocompatible nanomaterials such as hydroxyapatite, which avoids the environmental and health risks of silver ions and organic halogens in traditional antibacterial agents. In addition, through chemical bonding and carrier fixation, the release and loss of active ingredients during production and use are reduced, the environmental burden is reduced, and the material is more green and environmentally friendly. Attached Figure Description
[0017] Figure 1 The present invention provides a flowchart of an antibacterial food-grade board and its preparation method. Detailed Implementation
[0018] 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.
[0019] It should be noted that the raw materials used in the following embodiments are all commercially available. Example
[0020] Pretreatment of tea saponin: Tea saponin and anhydrous acetone were mixed at a solid-liquid ratio of 1g:10mL. Maleic anhydride of 20% of the mass of tea saponin was added, followed by p-toluenesulfonic acid. The mixture was stirred at 180rpm for 3.5h at 55℃ to obtain a third mixture. The third mixture was added to deionized water and stirred for 1h. The mixture was then filtered to obtain a filter residue. The filter residue was washed twice with sodium bicarbonate aqueous solution and then washed with deionized water until neutral. The washed filter residue was vacuum dried at 60℃ to constant weight to obtain pretreated tea saponin.
[0021] The mass of p-toluenesulfonic acid is 0.8% of the mass of tea soap, the volume of deionized water is 3 times the volume of the third mixture, and the mass concentration of sodium bicarbonate aqueous solution is 5%.
[0022] Preparation of the reaction solution: ε-polylysine powder, deionized water and anhydrous ethanol were mixed at a solid-liquid ratio of 1.1g:87mL:10mL to obtain a second mixture. 2.5% of tea saponin by mass of the second mixture was added, followed by 0.17% of 1,3-dicyclohexylcarbodiimide by mass of the second mixture. The mixture was reacted at 43℃ for 30 min to obtain the reaction solution.
[0023] Preparation of composite additive: Nano-hydroxyapatite and deionized water were mixed at a mass ratio of 1:7 to obtain a first mixture. 0.3% by mass of silane coupling agent KH-550 was added to the first mixture, and the mixture was ultrasonically dispersed for 20 min. Subsequently, an 8% by mass aqueous solution of aminosulfonic acid was added, and the mixture was stirred at 50℃ for 25 min. After filtration, the filter residue was mixed with the reaction solution at a mass ratio of 1:2.8 and reacted at 50℃ for 1 h. After spray drying, the composite additive was obtained. The volume of the aminosulfonic acid aqueous solution was 6 times the mass of the nano-hydroxyapatite.
[0024] The parameters for spray drying are: inlet air temperature 120℃ and outlet air temperature 60℃.
[0025] Preparation of Eucommia ulmoides gum precursor: Eucommia ulmoides gum and anhydrous ethanol were mixed at a solid-liquid ratio of 1 g: 8 mL and stirred at 50 °C for 10 min. Then, a peracetic acid solution accounting for 30% of the mass of Eucommia ulmoides gum was added dropwise, along with 0.5% of the mass of sodium dihydrogen phosphate. The mixture was stirred at 30 °C and 150 rpm for 2.5 h. After the reaction was completed, a 5% sodium bicarbonate solution was added to adjust the pH to 6.5. After standing and separating into layers, the aqueous phase was collected and dried at 60 °C to constant weight to obtain the Eucommia ulmoides gum precursor, wherein the mass concentration of peracetic acid was 30%.
[0026] Preparation of additive: Eucommia gum precursor and limonene were mixed at a mass ratio of 3.8:5.8 to obtain a mixture. Triethanolamine accounting for 0.3% of the total mass of the mixture was added, and the mixture was stirred at 150 rpm for 20 min at 25 °C. After stirring, the mixture was ultrasonically treated for 5 min to obtain the additive.
[0027] Preparation of functional additives: Sichuan pepper seeds were crushed and passed through a 60-mesh sieve to obtain Sichuan pepper seed powder. The powder was then transferred to a supercritical carbon dioxide reactor, and 3% anhydrous ethanol (by weight of the Sichuan pepper seed powder) was added. The mixture was reacted at 32 MPa and 42 °C for 1.2 h. The reaction product was collected from the separation vessel to obtain intermediate product A. Intermediate product A was mixed with Cnidium monnieri extract at a mass ratio of 1:0.8, and 1% glycerol (by weight of the intermediate product) was added. The mixture was stirred at 50 °C for 30 min to obtain intermediate product B. Intermediate product B was mixed with additives at a mass ratio of 1:3.8 and reacted in a water bath at 58 °C for 1.5 h under nitrogen protection to obtain the functional additives.
[0028] Raw material preparation: 100 parts polypropylene resin, 5 parts composite additives, 8 parts functional additives, 0.3 parts antioxidant 1010 and 0.5 parts calcium stearate.
[0029] Preparation of antibacterial food-grade boards: Step 1: Add polypropylene resin, composite additives, functional auxiliaries, antioxidant 1010 and calcium stearate to a high-speed mixer and mix for 5 minutes at room temperature to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, and after melt extrusion, water cooling, and pelletizing, obtain antibacterial masterbatch. The processing temperature of the twin-screw extruder is: 160℃ in zone 1, 170℃ in zone 2, 180℃ in zone 3, 175℃ in zone 4, 170℃ at the die head, and the screw speed is 300 rpm. Step 3: Transfer the antibacterial masterbatch into a flat vulcanizing machine, hot press at 190℃, hot press at 10MPa, hot press for 8 minutes, and hot press to form antibacterial food-grade boards. Example
[0030] Pretreatment of tea saponin: Tea saponin and anhydrous acetone were mixed at a solid-liquid ratio of 1g:11mL. Maleic anhydride of 22% of the mass of tea saponin was added, followed by p-toluenesulfonic acid. The mixture was stirred at 190rpm for 4 hours at 57℃ to obtain a third mixture. The third mixture was added to deionized water and stirred for 1.5 hours. The mixture was then filtered to obtain a filter residue. The filter residue was washed twice with sodium bicarbonate aqueous solution and then washed with deionized water until neutral. The washed filter residue was vacuum dried at 62℃ to constant weight to obtain pretreated tea saponin.
[0031] The mass of p-toluenesulfonic acid is 1% of the mass of tea soap, the volume of deionized water is 3.5 times the volume of the third mixture, and the mass concentration of sodium bicarbonate aqueous solution is 5%.
[0032] Preparation of the reaction solution: ε-polylysine powder, deionized water and anhydrous ethanol were mixed at a solid-liquid ratio of 1.2 g: 88 mL: 10 mL to obtain a second mixture. 2.7% of tea saponin by mass of the second mixture was added, followed by 0.18% of 1,3-dicyclohexylcarbodiimide by mass of the second mixture. The mixture was reacted at 45 °C for 35 min to obtain the reaction solution.
[0033] Preparation of composite additive: Nano-hydroxyapatite and deionized water were mixed at a mass ratio of 1:8 to obtain a first mixture. 0.4% by mass of silane coupling agent KH-550 was added to the first mixture, and the mixture was ultrasonically dispersed for 25 min. Subsequently, an 8% by mass aqueous solution of aminosulfonic acid was added, and the mixture was stirred at 55℃ for 30 min. After filtration, the filter residue was mixed with the reaction solution at a mass ratio of 1:3 and reacted at 55℃ for 1.1 h. After spray drying, the composite additive was obtained. The volume of the aminosulfonic acid aqueous solution was 6 times the mass of the nano-hydroxyapatite.
[0034] The parameters for spray drying are: inlet air temperature 125℃ and outlet air temperature 65℃.
[0035] Preparation of Eucommia ulmoides gum precursor: Eucommia ulmoides gum and anhydrous ethanol were mixed at a solid-liquid ratio of 1 g: 9 mL and stirred at 55 °C for 10 min. Then, a peracetic acid solution accounting for 33% of the mass of Eucommia ulmoides gum was added dropwise, along with sodium dihydrogen phosphate accounting for 0.7% of the mass of Eucommia ulmoides gum. The mixture was stirred at 170 rpm at 35 °C for 3 h. After the reaction was completed, a sodium bicarbonate solution with a mass concentration of 5% was added to adjust the pH to 7.0. After standing and separating into layers, the aqueous phase was collected and dried at 62 °C to constant weight to obtain the Eucommia ulmoides gum precursor, wherein the mass concentration of peracetic acid was 30%.
[0036] Preparation of additive: Eucommia gum precursor and limonene were mixed at a mass ratio of 4:6 to obtain a mixture. Triethanolamine accounting for 0.3% of the total mass of the mixture was added and stirred at 170 rpm for 22 min at 27℃. After stirring, the mixture was ultrasonically treated for 7 min to obtain the additive.
[0037] Preparation of functional additives: Sichuan pepper seeds were crushed and passed through a 60-mesh sieve to obtain Sichuan pepper seed powder. The powder was then transferred to a supercritical carbon dioxide reactor, and 4% anhydrous ethanol (by weight of the Sichuan pepper seed powder) was added. The mixture was reacted at 33 MPa and 44 °C for 1.3 h. The reaction product was collected from the separation vessel to obtain intermediate product A. Intermediate product A was mixed with Cnidium monnieri extract at a mass ratio of 1:0.9. Glycerin (by weight of the intermediate product) was added, and the mixture was stirred at 50 °C for 30 min to obtain intermediate product B. Intermediate product B was mixed with additives at a mass ratio of 1:4, and the mixture was reacted in a water bath at 60 °C for 1.7 h under nitrogen protection to obtain the functional additives.
[0038] Raw material preparation: 100 parts polypropylene resin, 10 parts composite additives, 10 parts functional additives, 0.6 parts antioxidant 1010 and 1 part calcium stearate.
[0039] Preparation of antibacterial food-grade boards: Step 1: Add polypropylene resin, composite additives, functional auxiliaries, antioxidant 1010 and calcium stearate to a high-speed mixer and mix for 8 minutes at room temperature to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, and after melt extrusion, water cooling, and pelletizing, obtain antibacterial masterbatch. The processing temperature of the twin-screw extruder is: 165℃ in zone 1, 175℃ in zone 2, 185℃ in zone 3, 180℃ in zone 4, 175℃ at the die head, and the screw speed is 350 rpm. Step 3: Transfer the antibacterial masterbatch into a flat vulcanizing machine, hot press at 190℃, hot press at 10MPa, hot press for 8 minutes, and hot press to form antibacterial food-grade boards. Example
[0040] Pretreatment of tea saponin: Tea saponin and anhydrous acetone were mixed at a solid-liquid ratio of 1g:12mL. Maleic anhydride of 25% of the mass of tea saponin was added, followed by p-toluenesulfonic acid. The mixture was stirred at 200rpm for 4 hours at 60℃ to obtain a third mixture. The third mixture was added to deionized water and stirred for 1.5 hours. The mixture was then filtered to obtain a filter residue. The filter residue was washed twice with sodium bicarbonate aqueous solution and then washed with deionized water until neutral. The washed filter residue was vacuum dried at 65℃ to constant weight to obtain pretreated tea saponin.
[0041] The mass of p-toluenesulfonic acid is 1.2% of the mass of tea soap, the volume of deionized water is 4 times the volume of the third mixture, and the mass concentration of sodium bicarbonate aqueous solution is 5%.
[0042] Preparation of the reaction solution: ε-polylysine powder, deionized water and anhydrous ethanol were mixed at a solid-liquid ratio of 1.3g:89mL:10mL to obtain a second mixture. 3% of tea saponin by mass of the second mixture was added, followed by 0.19% of 1,3-dicyclohexylcarbodiimide by mass of the second mixture. The mixture was reacted at 47℃ for 35 min to obtain the reaction solution.
[0043] Preparation of composite additive: Nano-hydroxyapatite and deionized water were mixed at a mass ratio of 1:9 to obtain a first mixture. 0.5% by mass of silane coupling agent KH-550 was added to the first mixture, and the mixture was ultrasonically dispersed for 30 min. Subsequently, an 8% by mass aqueous solution of aminosulfonic acid was added, and the mixture was stirred at 60℃ for 35 min. After filtration, the filter residue was mixed with the reaction solution at a mass ratio of 1:3.2 and reacted at 60℃ for 1.2 h. After spray drying, the composite additive was obtained. The volume of the aminosulfonic acid aqueous solution was 6 times the mass of the nano-hydroxyapatite.
[0044] The parameters for spray drying are: inlet air temperature 130℃ and outlet air temperature 70℃.
[0045] Preparation of Eucommia ulmoides gum precursor: Eucommia ulmoides gum and anhydrous ethanol were mixed at a solid-liquid ratio of 1 g: 10 mL and stirred at 60 °C for 10 min. Then, a peracetic acid solution accounting for 35% of the mass of Eucommia ulmoides gum was added dropwise, along with sodium dihydrogen phosphate accounting for 1.0% of the mass of Eucommia ulmoides gum. The mixture was stirred at 180 rpm at 40 °C for 3 h. After the reaction was completed, a sodium bicarbonate solution with a mass concentration of 5% was added to adjust the pH to 7.0. After standing and separating into layers, the aqueous phase was collected and dried at 65 °C to constant weight to obtain the Eucommia ulmoides gum precursor, wherein the mass concentration of peracetic acid was 30%.
[0046] Preparation of additive: Eucommia gum precursor and limonene were mixed at a mass ratio of 4.2:6.2 to obtain a mixture. Triethanolamine accounting for 0.3% of the total mass of the mixture was added, and the mixture was stirred at 180 rpm for 25 min at 30 °C. After stirring, the mixture was ultrasonically treated for 8 min to obtain the additive.
[0047] Preparation of functional additives: Sichuan pepper seeds were pulverized and passed through a 60-mesh sieve to obtain Sichuan pepper seed powder. The powder was then transferred to a supercritical carbon dioxide reactor, and 5% anhydrous ethanol (by weight of the Sichuan pepper seed powder) was added. The mixture was reacted at 35 MPa and 46 °C for 1.5 h. The reaction product was collected from the separation vessel to obtain intermediate product A. Intermediate product A was mixed with Cnidium monnieri extract at a mass ratio of 1:1, and 2% glycerol (by weight of the intermediate product) was added. The mixture was stirred at 50 °C for 30 min to obtain intermediate product B. Intermediate product B was mixed with additives at a mass ratio of 1:4.2 and reacted in a water bath at 62 °C for 1.8 h under nitrogen protection to obtain the functional additives.
[0048] Raw material preparation: 100 parts polypropylene resin, 15 parts composite additives, 12 parts functional additives, 0.8 parts antioxidant 1010 and 1.5 parts calcium stearate.
[0049] Preparation of antibacterial food-grade boards: Step 1: Add polypropylene resin, composite additives, functional auxiliaries, antioxidant 1010 and calcium stearate to a high-speed mixer and mix for 10 minutes at room temperature to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, and after melt extrusion, water cooling, and pelletizing, obtain antibacterial masterbatch. The processing temperature of the twin-screw extruder is: 170℃ in zone 1, 180℃ in zone 2, 190℃ in zone 3, 185℃ in zone 4, 180℃ at the die head, and the screw speed is 400 rpm. Step 3: Transfer the antibacterial masterbatch into a flat vulcanizing machine, hot press at 190℃, hot press at 10MPa, hot press for 8 minutes, and hot press to form antibacterial food-grade boards.
[0050] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain compound additives.
[0051] Comparative Example 2 differs from Example 1 in that it does not contain functional additives.
[0052] Comparative Example 3 differs from Example 1 in that the composite additive is replaced with nano-zirconium phosphate silver-loaded antibacterial agent.
[0053] Performance testing: The antibacterial food-grade boards prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, and the test data are recorded in the table below: Table 1 Antibacterial Rate and Impact Strength Test Table
[0054] In the performance test, the antibacterial rate test was conducted in accordance with GB / T 31402-2023, using Staphylococcus aureus and Escherichia coli as test strains. The antibacterial rate was calculated based on the number of colonies after 24 hours of contact. The impact strength test was conducted in accordance with GB / T 1843-2008.
[0055] By comparing and analyzing the performance test data of the antibacterial food-grade boards prepared in Examples 1-3 and Comparative Examples 1-3, it can be seen that the boards prepared by the present invention exhibit significant advantages in antibacterial performance, safety performance and mechanical properties.
[0056] The antibacterial rates of Examples 1-3 were all higher than those of Comparative Examples 1-3. This indicates that the synergistic antibacterial system constructed by the composite additive and functional auxiliaries in this invention played an important role. Among them, the composite additive used nano-hydroxyapatite as a carrier and combined with the natural antimicrobial peptide ε-polylysine, effectively destroying the microbial cell membrane through direct contact. The extracts of Sichuan pepper seed and Cnidium monnieri in the functional auxiliaries provided a synergistic antibacterial effect by interfering with cell metabolism and membrane lipid structure. Comparative Example 1, due to the complete lack of this core bonded antibacterial system, had a significantly reduced antibacterial performance. Comparative Example 2, due to the lack of synergistic effect of the natural active ingredients of the functional auxiliaries, had insufficient antibacterial efficacy. Although Comparative Example 3 used a traditional silver-based antibacterial agent, its bactericidal mode dependent on ion release was inefficient in the polypropylene matrix, and the formed antibacterial interface was unstable, so the antibacterial rate was lower than that of the Examples. This shows that this invention effectively improves the problems of easy loss and low efficiency of traditional physically blended antibacterial agents.
[0057] Regarding impact strength, the sample from the examples exhibited good toughness, all higher than that of the comparative examples. This indicates that the functional components introduced in this invention have good interfacial compatibility with the polypropylene matrix. The surface-modified nanocarrier in the composite additive can serve as a stress dispersion point, and the modified Eucommia ulmoides gum component in the functional additive also contributes to the toughness. However, Comparative Example 3 had the lowest impact strength because the added traditional inorganic silver-based antibacterial agent particles had poor interfacial compatibility with the polymer matrix, which easily became stress defects, leading to increased material brittleness. Comparative Examples 1 and 2 also had their mechanical properties weakened due to the absence of some functional components that improve the interface or toughen the material.
[0058] By comparing and analyzing the relevant data in the table, it can be seen that the antibacterial food-grade sheet prepared by the present invention not only has good antibacterial properties, but also good mechanical stability, and meets the safety standards for food contact materials. This indicates that the antibacterial food-grade sheet provided by the present invention has a broader market prospect in the field of food packaging and utensils, and is more suitable for promotion and application.
[0059] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0060] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. An antibacterial food-grade board, characterized in that, It includes the following raw materials by weight: 100 parts polypropylene resin, 5-15 parts composite additives, 8-12 parts functional additives, 0.3-0.8 parts antioxidant 1010 and 0.5-1.5 parts calcium stearate; The raw materials for the composite additive include nano-hydroxyapatite, aminosulfonic acid solution, and reaction solution. The raw materials for the functional additives include Sichuan pepper seeds, anhydrous ethanol, Cnidium monnieri extract, and additives.
2. The antibacterial food-grade board according to claim 1, characterized in that, The composite additive is prepared by the following method: nano-hydroxyapatite and deionized water are mixed at a mass ratio of 1:(7-9) to obtain a first mixture. 0.3-0.5% of the mass of the first mixture is added to the mixture, and the mixture is ultrasonically dispersed for 20-30 min. Subsequently, an 8% (w / w) aqueous solution of aminosulfonic acid is added, and the mixture is stirred at 50-60℃ for 25-35 min. The mixture is filtered, and the filter residue is mixed with the reaction solution at a mass ratio of 1:(2.8-3.2). The mixture is reacted at 50-60℃ for 1-1.2 h, and then spray-dried to obtain the composite additive. The volume of the aqueous solution of aminosulfonic acid is 6 times the mass of the nano-hydroxyapatite.
3. The antibacterial food-grade board according to claim 2, characterized in that, The reaction solution is prepared by the following method: ε-polylysine powder, deionized water and anhydrous ethanol are mixed at a solid-liquid ratio of (1.1-1.3) g:(87-89) mL:10 mL to obtain a second mixture. 2.5-3% of tea saponin is added to the second mixture, and then 0.17-0.19% of 1,3-dicyclohexylcarbodiimide is added. The mixture is reacted at 43-47℃ for 30-35 min to obtain the reaction solution.
4. The antibacterial food-grade board according to claim 3, characterized in that, The tea saponin needs to be pretreated before the reaction, including the following steps: tea saponin and anhydrous acetone are mixed at a solid-liquid ratio of 1g:(10-12)mL, maleic anhydride of 20-25% of the mass of tea saponin is added, and then p-toluenesulfonic acid is added. The mixture is stirred at 55-60℃ and 180-200rpm for 3.5-4h to obtain a third mixture. The third mixture is added to deionized water and stirred for 1-1.5h. The mixture is filtered to obtain a filter residue. The filter residue is washed twice with sodium bicarbonate aqueous solution and then washed with deionized water until neutral. The washed filter residue is vacuum dried at 60-65℃ to constant weight to obtain pretreated tea saponin.
5. The antibacterial food-grade board according to claim 1, characterized in that, The functional additive is prepared by the following method: Sichuan pepper seeds are crushed and passed through a 60-mesh sieve to obtain Sichuan pepper seed powder. The powder is then transferred to a supercritical carbon dioxide reactor, and 3-5% anhydrous ethanol (by weight of the Sichuan pepper seed powder) is added. The mixture is reacted at 32-35 MPa and 42-46 °C for 1.2-1.5 h. The reaction product is collected from the separation vessel to obtain intermediate product A. Intermediate product A is mixed with Cnidium monnieri extract at a mass ratio of 1:(0.8-1.0). Glycerin (by weight of the intermediate product) is added, and the mixture is stirred at 50 °C for 30 min to obtain intermediate product B. Intermediate product B is mixed with additives at a mass ratio of 1:(3.8-4.2), and the mixture is reacted in a water bath at 58-62 °C for 1.5-1.8 h under nitrogen protection to obtain the functional additive.
6. The antibacterial food-grade board according to claim 5, characterized in that, The additive is prepared by the following method: Eucommia ulmoides gum precursor and limonene are mixed at a mass ratio of (3.8-4.2):(5.8-6.2) to obtain a mixture. Triethanolamine accounting for 0.3% of the total mass of the mixture is added, and the mixture is stirred at 150-180 rpm at 25-30℃ for 20-25 minutes. After stirring, the mixture is ultrasonically treated for 5-8 minutes to obtain the additive.
7. The antibacterial food-grade board according to claim 6, characterized in that, The Eucommia ulmoides gum precursor was prepared by the following method: Eucommia ulmoides gum and anhydrous ethanol were mixed at a solid-liquid ratio of 1g:(8-10)mL, stirred at 50-60℃ for 10min, and then peracetic acid solution accounting for 30-35% of the mass of Eucommia ulmoides gum was added dropwise, along with sodium dihydrogen phosphate accounting for 0.5-1.0% of the mass of Eucommia ulmoides gum. The mixture was stirred at 30-40℃ at 150-180rpm for 2.5-3h. After the reaction was completed, sodium bicarbonate solution with a mass concentration of 5% was added to adjust the pH to 6.5-7.
0. After standing and separating into layers, the aqueous phase was collected and dried at 60-65℃ to constant weight to obtain the Eucommia ulmoides gum precursor, wherein the mass concentration of peracetic acid was 30%.
8. The antibacterial food-grade board according to claim 2, characterized in that, The parameters for the spray drying process are: inlet air temperature 120-130℃ and outlet air temperature 60-70℃.
9. The antibacterial food-grade board according to claim 4, characterized in that, The mass of p-toluenesulfonic acid is 0.8-1.2% of the mass of tea soap, the volume of deionized water is 3-4 times the volume of the third mixture, and the mass concentration of sodium bicarbonate aqueous solution is 5%.
10. The method for preparing antibacterial food-grade boards according to any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Add polypropylene resin, composite additives, functional auxiliaries, antioxidant 1010 and calcium stearate to a high-speed mixer and mix at room temperature for 5-10 minutes to obtain a premix. Step 2: Transfer the premixed material into a twin-screw extruder, and after melt extrusion, water cooling, and pelletizing, obtain antibacterial masterbatch. The processing temperature of the twin-screw extruder is: Zone 1 160-170℃, Zone 2 170-180℃, Zone 3 180-190℃, Zone 4 175-185℃, Die head 170-180℃, and screw speed 300-400 rpm. Step 3: Transfer the antibacterial masterbatch into a flat vulcanizing machine, hot press at 190℃, hot press at 10MPa, hot press for 8 minutes, and hot press to form antibacterial food-grade boards.