A biodegradable antibacterial fresh-keeping film and its preparation method and application

Abstract

The present invention discloses a biodegradable antibacterial fresh-keeping film and its preparation method and application. The biodegradable antibacterial fresh-keeping film comprises the following components in parts by weight: 10-30 parts of a chemically synthesized biodegradable material, 1-10 parts of a natural biodegradable material, 0.1-2 parts of a chain extender, 0.1-1 part of a surfactant, 0.1-1 part of a leveling agent, and 57-89 parts of a solvent. The tensile strength (TS) and elongation at break of the biodegradable antibacterial fresh-keeping film are significantly improved, the mechanical properties of the biodegradable film material are significantly improved, and it can also inhibit Penicillium italicum, Peronophythora litchi, and Botrytis cinerea by 100%.

Description

Technical Field

[0001] The present invention relates to the technical field of fresh-keeping film materials, and specifically relates to a biodegradable antibacterial fresh-keeping film and its preparation method and application. Background Art

[0002] Most common plastic products are prepared from petroleum as raw materials. These materials are difficult to decompose in nature, causing white pollution and even threatening the biological chain. Therefore, it is extremely important to find an environmentally friendly and widely used biodegradable material.

[0003] Biodegradable polymer materials are materials that ultimately decompose into carbon dioxide and water under specific environmental conditions. They are mainly divided into three categories: one is natural biodegradable polymer materials such as starch and pectin; the second is chemically synthesized biodegradable polymer materials such as polylactic acid and polyvinyl alcohol; the third is microbially synthesized biodegradable polymer materials such as polyhydroxyalkanoates. The films prepared from biodegradable materials have much poorer mechanical properties than petroleum-based plastics. However, modifying the blended biological materials by adding additives is one of the methods to prepare high-performance film materials. For example, Patent CN202210504498 discloses a high-strength bio-based thin film material and its preparation method. Specifically, casein is used as the base raw material of the film material, and a hyperbranched compound such as tetraethyl titanate is added to carry out a blending and cross-linking modification treatment on casein to obtain a protein film with excellent mechanical strength; Patent CN202310114007 discloses a packaging film material for fresh-keeping and its preparation method. Gelatin and chitosan are used as the raw materials of the film material. By adding additives such as titanium dioxide, the film material has good mechanical properties and antibacterial properties and can extend the shelf life of fruits and vegetables. Summary of the Invention

[0004] The purpose of this patent is to prepare a biodegradable fresh-keeping film material with better mechanical properties and biological properties through blending cross-linking and improvement of the preparation process.

[0005] The first purpose of the present invention is to provide a biodegradable antibacterial fresh-keeping film, which comprises the following components in parts by weight: 10-30 parts of chemically synthesized biodegradable materials, 1-10 parts of natural biodegradable materials, 0.1-2 parts of chain extender, 0.1-1 part of surfactant, 0.1-1 part of leveling agent, and 57-89 parts of solvent.

[0006] Preferably, the biodegradable antibacterial fresh-keeping film comprises the following components in parts by weight: calculated on the basis of 100 parts by mass, 10-20 parts of chemically synthesized biodegradable materials, 1-2 parts of natural biodegradable materials, 0.1-0.5 parts of chain extender, 1 part of surfactant, 0.1 part of leveling agent, and the balance is solvent water.

[0007] Preferably, the chain extender is polyaminopropyl biguanide, polyhexamethylene biguanide or polyhexamethylene monoguandine.

[0008] Preferably, the natural degradable material is pectin, starch or microcrystalline cellulose.

[0009] Preferably, the chemically synthesized degradable material is polyvinyl alcohol.

[0010] Preferably, the surfactant is Tween 20, the leveling agent is acrylic resin, and the solvent is water.

[0011] The second object of the present invention is to provide a method for preparing the above-mentioned biodegradable antibacterial fresh-keeping film, and the specific steps are as follows: Weigh each component by weight, mix them and stir and dissolve at 70-90 °C for 1-24 h, stand still at room temperature to defoam to obtain a uniform film-forming solution, coat the film-forming solution, and dry it to obtain the biodegradable antibacterial fresh-keeping film.

[0012] Preferably, the method includes the following steps: Weigh each component by weight, mix them and stir and dissolve at 70 °C and 600 rpm for 6-12 h, then stand still at room temperature for 3 h to defoam to obtain a uniform emulsion as the film-forming solution, place 10 ml of the film-forming solution on a coater, coat it with a 150-μm wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable antibacterial fresh-keeping film.

[0013] The third object of the present invention is to provide the application of the above-mentioned biodegradable antibacterial fresh-keeping film in food fresh-keeping packaging or food antibacterial packaging.

[0014] Preferably, the antibacterial is to inhibit one or more of Penicillium digitatum, Peronophythora litchi and Botrytis cinerea.

[0015] Advantages of the present invention:

[0016] The polyaminopropyl biguanide selected in the present invention is an ideal chain extender for biodegradable film materials. In the formulation with an addition ratio of 0.1 part, the tensile strength (TS) and elongation at break of the film material prepared by it are increased by 2 times, significantly improving the mechanical properties of the biodegradable film material, and it can also inhibit 100% of Penicillium digitatum, Peronophythora litchi and Botrytis cinerea.

[0017] The polyhexamethylene biguanide selected in the present invention is an ideal chain extender for biodegradable film materials. In the formulation with an addition ratio of 0.5 part, the tensile strength (TS) of the film material prepared by it is increased by 1.94 times and the elongation at break (EAB) is increased by 1.36 times, significantly improving the mechanical properties of the biodegradable film material, and it can also inhibit 100% of Penicillium digitatum, Peronophythora litchi and Botrytis cinerea.

[0018] The polyhexamethylene monoguanidine selected in the present invention is an ideal chain extender for biodegradable membrane materials. In the formulation with an addition ratio of 0.5 parts, the tensile strength (TS) of the prepared membrane material is increased by 1.86 times and the elongation at break (EAB) is increased by 1.44 times, significantly improving the mechanical properties of the biodegradable membrane material. Description of the Drawings

[0019] Figure 1 : Inhibitory effect of the biodegradable membrane prepared from polyaminopropyl biguanide (chain extender) on fungi.

[0020] Figure 2 : Inhibitory effect of the biodegradable membrane prepared from polyhexamethylene biguanide (chain extender) on fungi. Detailed Embodiments

[0021] The following examples are further illustrations of the present invention, rather than limitations thereof.

[0022] Example 1:

[0023] Experimental group A: By mass, weigh 10 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of pectin (naturally biodegradable material), 0.1 part of polyaminopropyl biguanide (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 87.8 parts of water under magnetic stirring at 70 °C and 600 rpm for 6 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 ml) on a coater, coat it with a 150-micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable membrane material.

[0024] Experimental group B: By mass, weigh 10 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of pectin (naturally biodegradable material), 0.5 part of polyaminopropyl biguanide (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 87.4 parts of water under magnetic stirring at 70 °C and 600 rpm for 6 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 ml) on a coater, coat it with a 150-micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable membrane material.

[0025] Experimental group C: Weigh 10 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of pectin (natural biodegradable material), 1 part of polyaminopropyl biguanide (chain extender), 1 part of Tween 20 (surfactant), and 0.1 part of acrylic resin (flow leveling agent) by mass. Dissolve them in 86.9 parts of water at 70 °C with magnetic stirring at 600 rpm for 6 hours, and let it stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable film material.

[0026] Control group D: Polyaminopropyl biguanide was not added, and other components and preparation methods remained unchanged.

[0027] The tensile strength (TS) and elongation at break (EAB) of the film material were detected according to GB / T 13022-1991, and the test results are as follows:

[0028] Experimental group / Control group TS (MPa) EAB (%) A 44.5±2.5 52.6±3.4 B 32.3±2.1 45.5±3.2 C 21.2±1.7 26.2±2.6 D 21.5±1.5 26.7±2.4

[0029] The test results show that polyaminopropyl biguanide is an ideal chain extender for biodegradable film materials. In the formulation with an addition ratio of 0.1 part, the tensile strength (TS) and elongation at break of the film material prepared are doubled, significantly improving the mechanical properties of the biodegradable film material.

[0030] The antibacterial experiment of the film material was carried out according to GB / T 37206-2018, and the specific operations are as follows:

[0031] ① Cut the film of experimental group A into a certain area, weigh it, and calculate the content of polyaminopropyl biguanide.

[0032] ② Pour 10 mL of potato dextrose agar medium (PDA) into a petri dish. After cooling, cut a piece of the medium with the same area as the film of experimental group A and weigh it. Then calculate the content of polyaminopropyl biguanide that needs to be added to the medium (ensure that the content of polyaminopropyl biguanide in the film of experimental group A and the prepared PDA medium is the same).

[0033] ③ Prepare the polyaminopropyl biguanide PDA medium according to the calculation result in ②.

[0034] ④ Cut the film of experimental group A into a circle with a diameter of 2 cm and place it in a laminar flow hood for ultraviolet sterilization on both sides for 20 min.

[0035] ⑤ Prepare the fungal spore solution (2×10 10CFU / mL, Penicillium digitatum, Peronophythora litchii or Botrytis cinerea) were respectively inoculated onto ordinary PDA. After the spore suspension had dried, the experimentally extinct membrane of experimental group A from step ④ was placed above the area inoculated with the spore suspension, and cultured at 28°C to observe the growth status of the fungi (PDA + membrane treatment group).

[0036] ⑥ Inoculate the polyaminopropyl biguanide PDA medium in step ③ (PDA + medicament treatment group) and the PDA medium (blank control group) with the same amount of fungal spore suspension as in step ⑤, and culture under the same conditions as in step ⑤.

[0037] The experimental results showed that the membrane of experimental group A could inhibit Penicillium digitatum, Peronophythora litchii and Botrytis cinerea by 100%, while the polyaminopropyl biguanide PDA medium in step ③ could only inhibit Penicillium digitatum by 100%, and the inhibition rates for Peronophythora litchii and Botrytis cinerea [inhibition growth rate (%) = (control colony diameter - treated colony diameter) / control colony diameter) × 100%, the same below] were only 50% (as Figure 1 shown). Although polyaminopropyl biguanide is a well-known bacteriostatic agent, the membrane of experimental group A may cause more positively charged amino groups (-NH3 + ) to be exposed on the membrane surface and thus have a stronger bactericidal effect.

[0038] Example 2:

[0039] Experimental group E: Weigh 20 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of starch (naturally biodegradable material), 0.5 part of polyhexamethylene biguanide (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 77.4 parts of water under magnetic stirring at 70°C and 600 rpm for 12 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-μm wire bar at a speed of 5 mm / s, and dry at 45°C for 20 minutes to obtain the biodegradable film material.

[0040] Experimental group F: Weigh 20 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of starch (naturally biodegradable material), 1 part of polyhexamethylene biguanide (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 76.9 parts of water under magnetic stirring at 70°C and 600 rpm for 12 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-μm wire bar at a speed of 5 mm / s, and dry at 45°C for 20 minutes to obtain the biodegradable film material.

[0041] Experimental group G: Weigh 20 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of starch (naturally biodegradable material), 2 parts of polyhexamethylene biguanide (chain extender), 1 part of Tween 20 (surfactant), and 0.1 part of acrylic resin (flow agent). Dissolve them in 75.9 parts of water under magnetic stirring at 70 °C and 600 rpm for 12 hours, and then let it stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-μm wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable film material.

[0042] Control group H: Polyhexamethylene biguanide was not added, and 77.9 parts of water was added. The other components and preparation methods were the same as those of experimental groups E, F, and G in Example 2.

[0043] The tensile strength (TS) and elongation at break (EAB) of the film materials were detected according to GB / T 13022-1991, and the test results are as follows:

[0044]

[0045]

[0046] The test results show that polyhexamethylene biguanide is an ideal chain extender for biodegradable film materials. In the formulation with an addition ratio of 0.5 parts, the tensile strength (TS) of the film material prepared is increased by 1.94 times and the elongation at break rate (EAB) is increased by 1.36 times, significantly improving the mechanical properties of the biodegradable film materials.

[0047] The antibacterial experiment of the film materials was carried out according to GB / T 37206-2018, and the specific operations are as follows:

[0048] ① Cut the film of experimental group E according to a certain area, weigh it, and calculate the content of polyhexamethylene biguanide.

[0049] ② Pour 10 mL of potato dextrose agar medium (PDA) into a petri dish. After cooling, cut and weigh the medium with the same area as the film of experimental group E, and then calculate the content of polyhexamethylene biguanide that needs to be added to the medium (ensure that the content of polyhexamethylene biguanide in the film of experimental group E and the prepared PDA medium is the same).

[0050] ③ Prepare the polyhexamethylene biguanide PDA medium according to the calculation results in ②.

[0051] ④ Cut the film of experimental group E into a circle with a diameter of 2 cm and place it in a laminar flow bench for ultraviolet sterilization on both sides for 20 min.

[0052] ⑤ The fungal spore solution (2×10 10CFU / mL, Penicillium digitatum, Peronophythora litchii or Botrytis cinerea) were separately inoculated onto ordinary PDA. After the spore suspension had dried, the experimental group E film sterilized in step ④ was placed above the area inoculated with the spore suspension, and cultured at 28 °C to observe the fungal growth condition (PDA + film treatment group).

[0053] ⑥ The polyhexamethylene biguanide PDA medium in step ③ (PDA + medicament treatment group) and the PDA medium (blank control group) were respectively inoculated with the same amount of fungal spore suspension as in step ⑤, and cultured under the same conditions as in step ⑤.

[0054] The experimental results showed that the experimental group E film could inhibit Penicillium digitatum, Peronophythora litchii and Botrytis cinerea by 100%. The inhibitory effect of the polyhexamethylene biguanide PDA medium in step ③ on Penicillium digitatum was 80%, and the inhibition rates on Peronophythora litchii and Botrytis cinerea were only 40% (as Figure 2 shown). Although polyhexamethylene biguanide is a well-known bacteriostatic agent, the experimental group E film may cause more positively charged amino groups (-NH3 + ) to be exposed on the film surface and thus have a stronger bactericidal effect.

[0055] Example 3:

[0056] Experimental group I: Weigh 15 parts of polyvinyl alcohol (chemically synthesized degradable material), 1 part of microcrystalline cellulose (naturally degradable material), 0.5 part of polyhexamethylene monoguandine (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 82.4 parts of water under magnetic stirring at 70 °C and 600 rpm for 12 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the degradable film material.

[0057] Experimental group J: Weigh 15 parts of polyvinyl alcohol (chemically synthesized degradable material), 1 part of microcrystalline cellulose (naturally degradable material), 1 part of polyhexamethylene monoguandine (chain extender), 1 part of Tween 20 (surfactant), 0.1 part of acrylic resin (leveling agent), dissolve in 81.9 parts of water under magnetic stirring at 70 °C and 600 rpm for 12 hours, and let stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the degradable film material.

[0058] Experimental group K: Weigh 15 parts of polyvinyl alcohol (chemically synthesized biodegradable material), 1 part of microcrystalline cellulose (naturally biodegradable material), 2 parts of polyhexamethylene biguanide (chain extender), 1 part of Tween 20 (surfactant), and 0.1 part of acrylic resin (flow leveling agent). Dissolve them in 80.9 parts of water under magnetic stirring at 70 °C and 600 rpm for 12 hours, and then let it stand at room temperature for 3 hours to obtain a uniform emulsion as the film-forming solution. Place the film-forming solution (10 mL) on a coater, coat it with a 150-μm wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable film material.

[0059] Control group L: Polyhexamethylene biguanide was not added, and 82.9 parts of water was added. The other components and preparation methods were the same as those of experimental groups I, J, and K in Example 3.

[0060] The tensile strength (TS) and elongation at break (EAB) of the film material were detected according to GB / T 13022-1991. The test results are as follows:

[0061] Experimental group / Control group TS (MPa) EAB (%) I 85.3±6.5 215.6±57.4 J 63.5±5.4 185.8±48.7 K 52.7±4.7 158.8±47.6 L 34.3±3.2 126.7±33.5

[0062] The test results show that polyhexamethylene biguanide is an ideal chain extender for biodegradable film materials. In the formulation with an addition ratio of 0.5 parts, the tensile strength (TS) of the prepared film material is increased by 1.86 times and the elongation at break (EAB) is increased by 1.44 times, significantly improving the mechanical properties of the biodegradable film material.

[0063] The antibacterial experiment of the film material was carried out according to GB / T 37206-2018. The specific operations are as follows:

[0064] ① Cut the film of experimental group I into a certain area, weigh it, and calculate the content of polyhexamethylene biguanide.

[0065] ② Pour 10 mL of potato dextrose agar medium (PDA) into a petri dish. After cooling, cut out a medium with the same area as the film of experimental group I, weigh it, and then calculate the content of polyhexamethylene biguanide that needs to be added to the medium (ensure that the content of polyhexamethylene biguanide in the film of experimental group I and the prepared PDA medium is the same).

[0066] ③ Prepare the polyhexamethylene biguanide PDA medium according to the calculation results in ②.

[0067] ④ Cut the film of experimental group I into a circle with a diameter of 2 cm and place it in a laminar flow cabinet for 20 min of ultraviolet sterilization on both sides.

[0068] ⑤ The fungal spore solution (2×10 10CFU / mL, Penicillium italicum, Peronophythora litchi, or Botrytis cinerea) were inoculated onto ordinary PDA respectively. After the spore liquid was dried, the experimental group I film sterilized in step ④ was placed above the area inoculated with the spore liquid, and the fungal growth was cultured and observed at 28°C.

[0069] ⑥ Inoculate the polyhexamethylene biguanide PDA medium in step ③ with the same amount of fungal spore liquid as in step ⑤ and culture it under the same conditions as in step ⑤.

[0070] The experimental results showed that the activities of the experimental group I film and the polyhexamethylene biguanide PDA medium in inhibiting Penicillium italicum, Peronophythora litchi, and Botrytis cinerea were similar and there was no significant difference.

Claims

1. A biodegradable antibacterial fresh-keeping film, characterized in that, It comprises the following components in parts by weight: 10 - 30 parts of chemically synthesized biodegradable material, 1 - 10 parts of natural biodegradable material, 0.1 - 2 parts of chain extender, 0.1 - 1 part of surfactant, 0.1 - 1 part of leveling agent, and 57 - 89 parts of solvent. The chain extender is polyaminopropyl biguanide, polyhexamethylene biguanide or polyhexamethylene monoguandine; The preparation method of the biodegradable antibacterial fresh-keeping film comprises the following steps: Weigh each component according to parts by weight, mix them, stir and dissolve at 70 - 90 °C for 1 - 24 h, stand for defoaming at room temperature to obtain a uniform film-forming solution, coat the film-forming solution, and dry it to obtain the biodegradable antibacterial fresh-keeping film; The natural biodegradable material is pectin, starch or microcrystalline cellulose; The chemically synthesized biodegradable material is polyvinyl alcohol.

2. The biodegradable antibacterial fresh-keeping film according to claim 1, wherein It comprises the following components in parts by weight: Based on 100 parts by mass, 10 - 20 parts of chemically synthesized biodegradable material, 1 - 2 parts of natural biodegradable material, 0.1 - 0.5 parts of chain extender, 1 part of surfactant, 0.1 part of leveling agent, and the balance is solvent water.

3. The biodegradable antibacterial fresh-keeping film according to claim 1 or 2, characterized in that, The surfactant is Tween 20, the leveling agent is acrylic resin, and the solvent is water.

4. The biodegradable antibacterial fresh-keeping film according to claim 1 or 2, characterized in that, The specific steps of the preparation method are as follows: Weigh each component according to parts by weight, mix them, stir and dissolve at 70 °C and 600 rpm for 6 - 12 h, then stand for 3 h at room temperature for defoaming to obtain a uniform emulsion as the film-forming solution. Put 10 mL of the film-forming solution on a coater, coat it with a 150 - micron wire bar at a speed of 5 mm / s, and dry it at 45 °C for 20 minutes to obtain the biodegradable antibacterial fresh-keeping film.

5. Application of the biodegradable antibacterial fresh-keeping film according to claim 1 or 2 in food fresh-keeping packaging or food antibacterial packaging.

6. The application according to claim 5, characterized in that The antibacterial action is to inhibit one or more of Penicillium digitatum, Peronophythora litchi and Botrytis cinerea.

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