Preparation method of degradable antibacterial plastic and application of degradable antibacterial plastic in meal box

Abstract

The invention belongs to the field of biodegradable high polymer materials, and particularly relates to a preparation method of degradable antibacterial plastic and application of the degradable antibacterial plastic in meal boxes. The preparation method comprises the following steps: mixing PLA, PHA, a plasticizer and an antibacterial agent, granulating by an extruder to obtain degradable antibacterial plastic, and then carrying out injection molding to obtain the meal box. The PLA and the PHA are blended, so that the rigidity and the low cost of the PLA are retained, and the flexibility and the rapid degradability of the PHA are fused; pHA has antibacterial activity, and the dosage of extra antibacterial agents is reduced after PHA is blended with PLA; according to the invention, the porous spherical ZnO / TiO2 loaded nano Ag is used as an antibacterial agent, has a relatively high specific surface area and can efficiently sterilize, and the porous material can synchronously adsorb peculiar smell molecules or grease volatilized by food, so that the preservation time is prolonged; the meal box formed by injection molding of the plastic has excellent mechanical properties and food safety, is suitable for the field of disposable environment-friendly tableware, and solves the problems of pollution and microorganism breeding of traditional plastics.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biodegradable polymer materials, and particularly relates to a preparation method of degradable antibacterial plastic and application thereof in meal boxes. BACKGROUND

[0002] Traditional petroleum-based plastics (such as PP and PS) are difficult to degrade, causing serious environmental pollution problems. At the same time, disposable tableware is prone to bacterial growth during use, affecting food safety. At present, degradable plastics such as polylactic acid (PLA) have attracted widespread attention due to their environmental characteristics and degradability. For example, CN114539568A discloses a degradable plastic prepared by blending polylactic acid (PLA), grafted modified silica and a chain extender. However, pure PLA is brittle and has insufficient mechanical properties, and cannot meet the strength requirements of meal boxes when used alone. Moreover, the antibacterial performance is lacking, and bacteria cannot be inhibited from growing. CN119708693A discloses an antibacterial degradable plastic meal box, which is characterized in that it is composed of the following components in parts by mass: T30S polypropylene 45-60 parts, 1080 polypropylene 25-35 parts, ethylene copolymer 7-9 parts, inorganic filler 11-13 parts, antibacterial agent 0.3-10 parts, white oil 0.3-3 parts, and antibacterial powder being nano-silver powder, nano-copper powder, nano-zinc powder, cinnamomum burmanni, sabina vulgaris, camellia oil, cotinus coggygria, rehmannia glutinosa, orange peel, phoebe, berberis and turmeric. However, the antibacterial performance of the above-mentioned antibacterial agent is low, and cannot meet the actual needs.

[0003] Therefore, there is an urgent need to develop a plastic material that has excellent mechanical properties, antibacterial properties and degradability, in order to meet the market demand for environmentally friendly tableware. SUMMARY

[0004] In order to solve at least one of the above technical problems, a degradable antibacterial plastic with good antibacterial effect and preservation effect and excellent mechanical properties is developed.

[0005] A preparation method of a degradable antibacterial plastic, comprising the following steps: (1) weighing polylactic acid (PLA): 50-80 parts; polyhydroxyalkanoate (PHA): 20-30 parts; plasticizer: 1-10 parts; antibacterial agent: 5-15 parts; (2) washing and drying the polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer and antibacterial agent weighed in step (1), and then mixing and feeding into a double-screw extruder for granulation to obtain the degradable antibacterial plastic; wherein the antibacterial agent is selected to be ZnO / TiO2 / Ag, and the preparation method is as follows: A. zinc source, titanium source and triethanolamine are added to water and mixed uniformly; B. the mixed solution of step A is added to a reaction kettle for microwave hydrothermal reaction; C, the product of step B is washed by suction filtration, dried, to obtain porous microspheres ZnO / TiO2; D, the porous microspheres ZnO / TiO2 is dissolved in water, silver nitrate, sodium citrate is added, mixed uniformly, microwave hydrothermal, to obtain the antibacterial agent of porous microspheres ZnO / TiO2 loaded with nano Ag.

[0006] Preferably, the zinc source is one or more of zinc acetate, zinc chloride, zinc acetate, zinc citrate, zinc sulfate; Preferably, the titanium source is one or both of tetrabutyl titanate and isopropyl titanate;

[0007] Preferably, the molar ratio of zinc source, titanium source and triethanolamine is 1: (0.5-2): (1-2); Preferably, the reaction temperature of microwave hydrothermal is 150-180 degrees Celsius, and the reaction time is 0.5-2h; the power of microwave hydrothermal is 200-500w; Preferably, the molar ratio of silver nitrate and sodium citrate is 1: (1-1.5); Preferably, the mixing method in steps A and D is mechanical stirring or ultrasonic mixing; Preferably, the extrusion temperature is 170-200 DEG C; Preferably, the plasticizer is one or more of starch-based plasticizer, glycerol and tributyl citrate.

[0008] Compared with the prior art, the technical effects that can be achieved by the application are as follows: The application utilizes the blending of PLA and PHA to retain the rigidity and low cost of PLA, and to combine the flexibility and rapid degradation characteristics of PHA, so that the degradable plastic exhibits excellent mechanical properties; moreover, PHA itself has antibacterial properties, and after blending with PLA, the amount of additional antibacterial agent is reduced; the prepared ZnO / TiO2 porous material has a high specific surface area, high efficiency of sterilization, and can simultaneously adsorb food volatile odor molecules or grease, thereby prolonging the preservation time; the porous ZnO / TiO2 is beneficial to the dispersion of nano silver, avoids the agglomeration of nano silver, reduces the amount of silver used, and reduces the preparation cost of the antibacterial agent; as inorganic fillers, ZnO / TiO2 / Ag can be mixed and incorporated into degradable plastic, which can significantly improve the mechanical properties thereof; after the material is injection molded into a meal box, the meal box has excellent mechanical properties and food safety, and is suitable for the field of disposable environmentally friendly tableware, thereby solving the problems of traditional plastic pollution and microbial breeding. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0010] Figure 1 SEM image of ZnO / TiO2 / Ag prepared in the embodiments of the present application; Figure 2 Performance test table of the embodiments 1-3 and the comparative example 1 of the present application. DETAILED DESCRIPTION

[0011] In order to more clearly illustrate the technical solutions of the present application, the following will further describe the present application with reference to the embodiments. For those skilled in the art, other equivalent alternative solutions can also be obtained without creative labor, which should all belong to the protection scope of the present application.

[0012] A preparation method of a degradable antibacterial plastic, comprising the following steps: (1) taking polylactic acid (PLA): 50-80 parts; polyhydroxyalkanoate (PHA): 20-30 parts; plasticizer: 1-10 parts; antibacterial agent: 5-15 parts; (2) washing and drying the polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer and antibacterial agent weighed in step (1), and then mixing and feeding into a double-screw extruder for granulation to obtain the degradable antibacterial plastic; The antibacterial agent is selected as ZnO / TiO2 / Ag, and the preparation method is as follows: A. zinc source, titanium source and triethanolamine are added to water and mixed uniformly; B. the mixed solution of step A is added to a reaction kettle for microwave hydrothermal reaction; C. the product of step B is suction filtered and washed, and dried to obtain porous microspheres of ZnO / TiO2; D. the porous microspheres of ZnO / TiO2 are dissolved in water, silver nitrate and sodium citrate are added, and then mixed uniformly and subjected to microwave hydrothermal treatment to obtain the antibacterial agent of nano Ag loaded on the porous microspheres of ZnO / TiO2.

[0013] Preferably, the zinc source is one or more of zinc acetate, zinc chloride, zinc acetate, zinc citrate and zinc sulfate; Preferably, the titanium source is one or both of tetrabutyl titanate and isopropyl titanate;

[0014] Preferably, the molar ratio of the zinc source, the titanium source and triethanolamine is 1:(0.5-2):(1-2). Preferably, the microwave hydrothermal reaction temperature is 150-180 degrees Celsius, and the reaction time is 0.5-2h; the microwave hydrothermal power is 200-500w; Preferably, the molar ratio of silver nitrate to sodium citrate is 1: (1-1.5); Preferably, the mixing mode in steps A and D is mechanical stirring or ultrasonic mixing. Preferably, the extrusion temperature is 170-200℃. Preferably, the plasticizer is a starch-based plasticizer, glycerol or tributyl citrate.

[0015] The specific exemplary examples of the present application are as follows, in which polylactic acid (PLA) - CAS number is 31852-84-3, purchased from Shanghai Hailai Pharmaceutical Technology Co., Ltd.; polyhydroxyalkanoate: purchased from Shandong Yikeman Technology Co., Ltd.

[0016] Example 1 0.05 mol of zinc nitrate, 0.05 mol of tetrabutyl titanate, and 0.05 mol of triethanolamine were added to 150 mL of deionized water and uniformly mixed by ultrasonic mixing. B. The mixed solution of step A was added to a reaction kettle for microwave hydrothermal reaction; the microwave power was controlled at 300w, the reaction temperature was 180 degrees Celsius, and the reaction time was 1h; C. The product of step B was suction filtered, washed with deionized water and ethanol respectively, and dried to obtain porous microspheres ZnO / TiO2; D. The porous microspheres ZnO / TiO2 product of step C was dissolved in 100 ml of deionized water, 5 mmol of silver nitrate and 5 mmol of sodium citrate were added, and after uniform mixing, microwave hydrothermal reaction was carried out with the microwave power controlled at 300w, the reaction temperature at 180 degrees Celsius, and the reaction time at 1h; thus, the antibacterial agent with nano Ag loaded on the porous microspheres ZnO / TiO2 was obtained; E. According to the weight parts, 80 parts of polylactic acid (PLA), 20 parts of polyhydroxyalkanoate, 2 parts of glycerol plasticizer, and 10 parts of antibacterial agent were weighed; F. The polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer, and antibacterial agent were washed and dried, and then extruded and granulated after mixing at 100 degrees Celsius for 1h, with the extrusion temperature being 190℃, to obtain the degradable antibacterial plastic; G. The degradable antibacterial plastic was formed into the final meal box product by injection molding.

[0017] Example 2 0.05 mol of zinc nitrate, 0.05 mol of tetrabutyl titanate, and 0.1 mol of triethanolamine were added to 150 mL of deionized water and uniformly mixed by ultrasonic mixing. B, the mixed solution of step A is added to a reaction kettle for microwave hydrothermal reaction; the microwave power is controlled to be 300w, the reaction temperature is 180 degrees Celsius, and the reaction time is 1h; C, the product of step B is suction filtered, washed with deionized water and ethanol respectively, and dried to obtain porous microspheres ZnO / TiO2; D, the product porous microspheres ZnO / TiO2 of step C is dissolved in 100ml deionized water, 5mmol silver nitrate and 5mmol sodium citrate are added, mixed uniformly, then microwave hydrothermal reaction is carried out, the microwave power is controlled to be 300w, the reaction temperature is 180 degrees Celsius, and the reaction time is 0.5h; thus the antibacterial agent of nano Ag loaded on porous microspheres ZnO / TiO2 is obtained; E, according to weight parts, 80 parts of polylactic acid (PLA), 25 parts of polyhydroxyalkanoate, 2 parts of glycerol plasticizer and 10 parts of antibacterial agent are weighed; F, the weighed polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer and antibacterial agent of step (1) are cleaned and dried, then mixed at 100 degrees Celsius for 0.5h, extruded and granulated, the extrusion temperature is 190℃, and thus the degradable antibacterial plastic is obtained; G, the biobased degradable antibacterial plastic is formed into a final meal box product by injection molding.

[0018] Example 3 A, 0.05mol of zinc nitrate, 0.05mol of tetrabutyl titanate and 0.1mol of triethanolamine are added to 150ml deionized water, and ultrasonic mixing is carried out until uniform; B, the mixed solution of step A is added to a reaction kettle for microwave hydrothermal reaction; the microwave power is controlled to be 350w, the reaction temperature is 180 degrees Celsius, and the reaction time is 1h; C, the product of step B is suction filtered, washed with deionized water and ethanol respectively, and dried to obtain porous microspheres ZnO / TiO2; D, the product porous microspheres ZnO / TiO2 of step C is dissolved in 100ml deionized water, 5mmol silver nitrate and 5mmol sodium citrate are added, mixed uniformly, then microwave hydrothermal reaction is carried out, the microwave power is controlled to be 350w, the reaction temperature is 180 degrees Celsius, and the reaction time is 0.5h; thus the antibacterial agent of nano Ag loaded on porous microspheres ZnO / TiO2 is obtained; E, according to weight parts, 80 parts of polylactic acid (PLA), 25 parts of polyhydroxyalkanoate, 2 parts of glycerol plasticizer and 10 parts of antibacterial agent are weighed; F, the weighed polylactic acid (PLA), polyhydroxyalkanoate (PHA), glycerol plasticizer and antibacterial agent of step (1) are cleaned and dried, then mixed at 100 degrees Celsius, extruded and granulated, the extrusion temperature is 195℃, and thus the degradable antibacterial plastic is obtained; G, the biobased degradable antibacterial plastic is obtained by injection molding to obtain the final meal box product.

[0019] Comparative Example 1 A, according to the weight part, 80 parts of polylactic acid (PLA), 25 parts of polyhydroxyalkanoate, 2 parts of glycerol plasticizer are weighed; B, the polylactic acid (PLA), polyhydroxyalkanoate (PHA), glycerol plasticizer and cleaning and drying in step (1) are mixed at 100 degrees Celsius and then extruded and granulated, the extrusion temperature is 190℃, and the degradable antibacterial plastic is obtained; C, the biobased degradable antibacterial plastic is obtained by injection molding to obtain the final meal box product.

[0020] Comparative Example 2 A, 0.05 mol of zinc nitrate, 0.05 mol of tetrabutyl titanate are added to 150 mL of deionized water, and ultrasonic mixing is uniform; B, the mixed solution of step A is added to the reaction kettle for microwave hydrothermal reaction; the microwave power is controlled to be 300w, the reaction temperature is 180 degrees Celsius, and the reaction time is 1h; C, the product of step B is suction filtered, washed with deionized water and ethanol respectively, and dried to obtain ZnO / TiO2; D, the product ZnO / TiO2 of step C is dissolved in 100ml deionized water, 5mmol of silver nitrate and 5mmol of sodium citrate are added, mixed uniformly, then microwave hydrothermal, control microwave power is 300w, reaction temperature is 180 degrees Celsius, reaction time is 1h; the antibacterial agent loaded with nano Ag on ZnO / TiO2 can be obtained; E, according to the weight part, 80 parts of polylactic acid (PLA), 20 parts of polyhydroxyalkanoate, 2 parts of glycerol plasticizer, and 10 parts of antibacterial agent are weighed; F, the polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer and antibacterial agent are cleaned and dried, mixed at 100 degrees Celsius for 1h, then extruded and granulated, the extrusion temperature is 190℃, and the degradable antibacterial plastic is obtained; G, the biobased degradable antibacterial plastic is obtained by injection molding to obtain the final meal box product.

[0021] Comparative Example 3 A, 0.05mol of zinc nitrate, 0.05mol of tetrabutyl titanate, 0.05mol of triethanolamine are added to 150mL of deionized water, and ultrasonic mixing is uniform; B, the mixed solution of step A is added to the reaction kettle for hydrothermal reaction; the reaction temperature is controlled to be 180 degrees Celsius, and the reaction time is 10h; C, the product of step B is suction filtered, washed with deionized water and ethanol respectively, and dried to obtain ZnO / TiO2; D, the product of step C ZnO / TiO2 is dissolved in 100 ml deionized water, 5 mmol silver nitrate, 5 mmol sodium citrate, mixed evenly, microwave hydrothermal, control microwave power is 300 w, the reaction temperature is 180 degrees Celsius, the reaction time is 1h;ZnO / TiO2 on the supported nano Ag antibacterial agent can be obtained; E, according to the weight part, the polylactic acid (PLA) 80 parts;Polyhydroxyalkanoate 20 parts;Glycerol plasticizer 2 parts;Antibacterial agent 10 parts; F, the polylactic acid (PLA), polyhydroxyalkanoate (PHA), plasticizer, antibacterial agent is washed and dried, 100 degrees Celsius under the mixed 1h after extrusion granulation, the extrusion temperature is 190 DEG C, obtainable degradable antibacterial plastic; G, the degradable antibacterial plastic is obtained by injection molding to get the final meal box product.

[0022] Staphylococcus aureus ATCC 6538 as a strain, according to the QB / T2591-2003 standard test examples 1-3 and comparative examples 1-3 of antibacterial properties; According to ISO 527 standard test plastic material tensile strength.

[0023] Results see Figure 2 .

[0024] The principle and implementation mode of the present application are described in the specific examples in the present application, and the above examples are only used to help understand the method and core idea of the present application;At the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation mode, and the above description should not be understood as the limitation of the present application.

Claims

1. A method for preparing a degradable antibacterial plastic, characterized in that: The steps include: (1) Weigh 50-80 parts of polylactic acid; 20-30 parts of polyhydroxyalkanoate; 1-10 parts of plasticizer; and 5-15 parts of antibacterial agent; (2) Polylactic acid, polyhydroxyalkanoate, plasticizer, and antibacterial agent are mixed and sent into a twin-screw extruder for granulation to obtain a biodegradable antibacterial plastic; Among them, the antibacterial agent is selected as ZnO / TiO2 / Ag, and its preparation method is as follows: A. Add zinc source, titanium source and triethanolamine to water and mix well to obtain a mixed solution; B. adding the mixed solution of step A into a reactor to carry out microwave hydrothermal reaction to obtain a product; C. Filter and wash the product of step B, and dry it to obtain porous ZnO / TiO2 microspheres; D. Dissolve the porous ZnO / TiO2 microspheres in water, add silver nitrate and sodium citrate, mix well, and then heat with microwave to obtain the antibacterial agent loaded with nano-Ag on the porous ZnO / TiO2 microspheres.

2. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the zinc source is one or more of zinc acetate, zinc chloride, zinc acetate, zinc citrate, and zinc sulfate.

3. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the titanium source is one or both of tetrabutyl titanate and isopropyl titanate.

4. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the molar ratio of the zinc source, the titanium source, and the triethanolamine is 1:(0.5-2):(1-2).

5. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the reaction temperature of the microwave hydrothermal method is 150-180 degrees Celsius, the reaction time is 0.5-3 hours, and the power of the microwave hydrothermal method is 200-500W.

6. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the molar ratio of silver nitrate to sodium citrate is 1:(1-1.5).

7. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the mixing method in steps A and D is mechanical stirring or ultrasonic mixing.

8. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the extrusion temperature is 170-200°C.

9. The method for preparing a degradable antibacterial plastic according to claim 1, wherein the plasticizer is one or more of starch-based plasticizer, glycerol, and tributyl citrate.

10. An application of a degradable antibacterial plastic, characterized in that: The degradable antibacterial plastic according to any one of claims 1 to 9 is injection molded into a lunch box.

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