Degradable antibacterial sealing bag and preparation method thereof

Abstract

The application relates to a degradable antibacterial sealing bag and a preparation method thereof, and belongs to the technical field of sealing bags, which comprises the following raw materials: PLA 25-30 parts, PHBV 45-55 parts, enhanced antibacterial agent 8-10 parts, compatible agent 2-4 parts, antioxidant 1-2 parts and lubricant 0.5-1 part; in the technical scheme, trifluoromethyl maleic anhydride is combined with silanized nanomaterial to obtain a composite material; the enhanced antibacterial agent is obtained by combining a guanidine compound with the composite material; the PLA, the PHBV, the enhanced antibacterial agent, the compatible agent, the antioxidant and the lubricant are mixed, melt-blended, extruded and blow molded to finally obtain the degradable antibacterial sealing bag; the enhanced antibacterial agent has good interface compatibility with the PLA, high dispersibility, effectively improves the degradable performance, the antibacterial performance, the antioxidant performance and the mechanical performance of the sealing bag, prolongs the service life of the sealing bag and improves the comprehensive performance of the sealing bag.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sealing bags, and particularly relates to a degradable antibacterial sealing bag and a preparation method thereof. BACKGROUND

[0002] Sealing bags are mainly used for preserving food and preventing food oxidation, thereby prolonging the shelf life of food, and are therefore widely used in daily life. Traditional sealing bags are mostly prepared from non-degradable materials such as polyethylene, polyvinyl chloride and polyvinylidene chloride. These materials are difficult to degrade in the natural environment after being discarded, and long-term accumulation will cause serious pollution to the natural environment. With the continuous improvement of people's living standards, people's requirements for food safety and quality are also getting higher and higher, and some food sealing bags with degradable and antibacterial properties have appeared on the market. For these food sealing bags, although their degradable performance has been improved to a certain extent, the antibacterial performance is poor, and the growth of microorganisms on the surface of food cannot be effectively inhibited, which is easy to breed a large number of bacteria and affect people's health.

[0003] In the prior art, degradable antibacterial sealing bags usually rely on metal ions (such as silver ions) to enhance their antibacterial performance, but there is a migration problem, which is easy to release from the sealing material and pollute the food, thereby causing harm to human health; and the traditional sealing bag has a single function, and its antioxidant performance and degradable performance need to be further improved, so it is necessary to prepare a sealing bag which is degradable and has good antibacterial performance and antioxidant performance. SUMMARY

[0004] The purpose of the present application is to provide a degradable antibacterial sealing bag and a preparation method thereof. The composite material is obtained by combining trifluoromethyl maleic anhydride with silanized nanomaterials. The silanized nanomaterials are prepared by grafting silane coupling agents onto the surface of nanomaterials. The nanomaterials are composed of nanometer titanium dioxide and cellulose nanofibers, which have a synergistic effect and can enhance the antibacterial performance, antioxidant performance and mechanical performance of the sealing bag. The combination between trifluoromethyl maleic anhydride and silanized nanomaterials has good binding force, which can enhance the antibacterial performance, hydrophobicity and antioxidant property of the sealing bag. The enhanced antibacterial agent is obtained by combining guanidine compounds with the composite material. The guanidine compounds are composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride, which can effectively inhibit the growth of bacteria and provide long-lasting antibacterial effect. The PLA, PHBV, enhanced antibacterial agent, compatibilizer, antioxidant and lubricant are mixed, melt-extruded, blow molded, and finally the degradable antibacterial sealing bag is obtained, which overall improves the comprehensive performance of the sealing bag.

[0005] The technical problem solved by the present application is that in the prior art, degradable antibacterial sealing bags usually rely on metal ions (such as silver ions) to enhance their antibacterial performance, but there are migration problems, which are easy to release from the sealing material and pollute food, thereby causing harm to human health; and the traditional sealing bag has a single function, and its antioxidant performance and degradability need to be further improved, therefore, it is necessary to prepare a sealing bag which is degradable and has good antibacterial performance and antioxidant performance.

[0006] The object of the present application can be achieved by the following technical solutions:

[0007] A degradable antibacterial sealing bag comprises the following raw materials by weight: PLA 25-30 parts, PHBV 45-55 parts, enhanced antibacterial agent 8-10 parts, compatibility agent 2-4 parts, antioxidant 1-2 parts and lubricant 0.5-1 part.

[0008] The preparation method of the modified antibacterial agent comprises the following steps:

[0009] S1: combine trifluoromethyl maleic anhydride with silanized nanomaterials to obtain a composite material;

[0010] S2: combine the composite material with a guanidine compound to obtain an enhanced antibacterial agent.

[0011] Further, step S1 is specifically:

[0012] Mix the silanized nanomaterials and trifluoromethyl maleic anhydride uniformly, then add an initiator and toluene, and stir under a nitrogen atmosphere for 25-35 min, then react at 75-85°C for 22-24 h, cool to room temperature, then filter, wash with toluene, and finally vacuum dry at 55-65°C to obtain the composite material.

[0013] In the above reaction process, the silanized nanomaterials have carbon-carbon double bonds, and the trifluoromethyl maleic anhydride also has carbon-carbon double bonds, and the carbon-carbon double bonds in the silanized nanomaterials can undergo a free radical polymerization reaction with the carbon-carbon double bonds in the trifluoromethyl maleic anhydride, thereby combining the silanized nanomaterials with the trifluoromethyl maleic anhydride, and finally obtaining the composite material.

[0014] Further, the mass ratio of the silanized nanomaterials, trifluoromethyl maleic anhydride, initiator, toluene is 0.8-1.2:1.9-2.1:0.04-0.06:40-50.

[0015] Further, the initiator is azobisisobutyronitrile.

[0016] Further, the preparation method of the silanized nanomaterials comprises the following steps:

[0017] The nanomaterial is added into toluene and ultrasonically treated for 25-35 min, then stirred under nitrogen atmosphere for 15-25 min, then silane coupling agent is added, stirred and refluxed at 70-80℃ for 22-24 h, filtered, washed with toluene, and finally vacuum dried at 55-65℃ to obtain silanized nanomaterial.

[0018] In the above reaction process, the nanomaterial surface has hydroxyl groups, and the silane coupling agent produces silanol groups after hydrolysis, and the silanol groups on the silane coupling agent can combine with the hydroxyl groups on the nanomaterial, grafting the silane coupling agent onto the surface of the nanomaterial, and finally obtaining the silanized nanomaterial.

[0019] Further, the mass ratio of the nanomaterial, toluene, and silane coupling agent is 0.8-1.2:70-80:2.3-2.5.

[0020] Further, the silane coupling agent is 3-(methacryloyloxy)propyl trimethoxysilane.

[0021] Further, the nanomaterial is composed of nanometer titanium dioxide and cellulose nanofiber in a mass ratio of 0.7-0.8:0.4-0.5.

[0022] Further, step S2 is specifically:

[0023] The guanidine compound is added into deionized water, stirred uniformly, then the composite material in step S1 is added, then constant temperature oscillation is carried out in a shaking table at 36-38℃ for 22-24 h, and finally the enhanced antibacterial agent is obtained.

[0024] In the above reaction process, the guanidine compound has an amino group, and the composite material has an acid anhydride group in the trifluoromethyl maleic anhydride, and the amino group in the guanidine compound can react with the acid anhydride group in the composite material, combining the guanidine compound with the composite material together, and finally obtaining the enhanced antibacterial agent.

[0025] Further, the mass ratio of the guanidine compound, deionized water, and composite material is 1.9-2.1:10-15:0.8-1.2.

[0026] Further, the guanidine compound is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride in a mass ratio of 0.8-0.9:0.6-0.7.

[0027] A preparation method of a degradable antibacterial sealing bag, comprising the following steps:

[0028] The raw materials are weighed, PLA, PHBV, antibacterial agent, compatibility agent, antioxidant and lubricant are uniformly mixed, then are added into a double screw extruder, are extruded by melt blending, are cut into particles, are added into a single screw extrusion film blowing machine, are blown into a film, and finally a degradable antibacterial sealing bag is obtained.

[0029] Further, the compatibility agent is a styrene-acrylonitrile-maleic anhydride copolymer.

[0030] Further, the antioxidant is at least one of antioxidant 1010, antioxidant 168 and antioxidant 1076.

[0031] Further, the lubricant is at least one of calcium stearate, polyethylene wax and zinc stearate.

[0032] Further, the temperature of the double screw extruder is 170-180 DEG C, and the main machine rotation speed is 600-800 rpm.

[0033] The application has the following beneficial effects:

[0034] (1) In the technical scheme of the application, the trifluoromethyl maleic anhydride is combined with the silanized nanomaterial to obtain a composite material; the silanized nanomaterial is prepared by grafting a silane coupling agent to the surface of the nanomaterial; wherein the nanomaterial is composed of nanometer titanium dioxide and cellulose nanofiber, and the two have a synergistic effect, which not only can better enhance the antibacterial performance of the sealing bag, but also can enhance the antioxidant performance thereof; the cellulose nanofiber has a large specific surface area, can provide more reaction sites, and can promote the interaction between the nanometer titanium dioxide and the cellulose nanofiber; the hydroxyl groups on the surface of the cellulose nanofiber can also stabilize the nanometer titanium dioxide particles through hydrogen bonding to prevent the agglomeration of the nanometer titanium dioxide particles; the nanometer titanium dioxide has a good inhibitory effect on bacteria and has a certain antioxidant performance; mixing the nanometer titanium dioxide and the cellulose nanofiber can further improve the antibacterial performance, the antioxidant performance and the mechanical performance of the sealing bag; grafting the silane coupling agent can improve the dispersibility of the nanomaterial, prevent the agglomeration of the nanomaterial, and provide reaction sites for subsequent reactions; the trifluoromethyl maleic anhydride not only has good binding force with the silanized nanomaterial, but also can provide reaction sites for subsequent reactions, can further enhance the antibacterial performance of the sealing bag, and the fluorine atoms in the trifluoromethyl maleic anhydride can improve the hydrophobicity and the antioxidant performance of the sealing bag, and can also better improve the interfacial compatibility between the silanized nanomaterial and the PLA, and enhance the dispersibility thereof.

[0035] (2) In the technical scheme of the present application, the enhanced antibacterial agent is obtained by combining guanidine compounds with composite materials; the guanidine compounds are composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride, which have a synergistic antibacterial effect, can effectively inhibit the growth of bacteria, and provide long-lasting antibacterial effect; the combination of guanidine compounds and composite materials can also increase the interfacial compatibility between them and PLA, further improving the antibacterial performance of the sealing bag; the melting blending of PHBV and PLA not only has good degradability, but also can enhance the mechanical properties of the sealing bag, while reducing its oxygen permeability, and better improving the overall performance of the sealing bag; the mixing of PLA, PHBV, enhanced antibacterial agent, compatibilizer, antioxidant and lubricant, followed by melt blending, extrusion and blowing, finally obtains the degradable antibacterial sealing bag.

[0036] (3) In the technical scheme of the present application, the enhanced antibacterial agent is obtained by combining trifluoromethyl maleic anhydride with silanized nanomaterials, and then combining with composite materials; the PLA, PHBV, enhanced antibacterial agent, compatibilizer, antioxidant and lubricant are mixed, followed by melt blending, extrusion and blowing, finally obtains the degradable antibacterial sealing bag; the overall degradability, antibacterial performance, antioxidant performance, stability and mechanical properties of the sealing bag are improved, and the service life is prolonged, and the overall comprehensive performance is good. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] The specific parameters of the raw materials used in the present application are as follows:

[0039] PLA (Polylactic acid), CAS No. 26100-51-6, product No. P742431, provided by Shanghai Melin Biochemical Science and Technology Co., Ltd.; PHBV (Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)), CAS No. 80181-31-3, provided by Shanghai Melin Biochemical Science and Technology Co., Ltd.; Trifluoromethyl maleic anhydride, CAS No. 700-27-6, provided by Shanghai Titan Technology Co., Ltd.; Cellulose nanofiber, product No. YXL0026, particle size 4-10 nm, length 200 nm, provided by Shanghai Yingxin Laboratory Equipment Co., Ltd.; Nano-titanium dioxide, particle size 20-40 nm, No. NM000800, provided by Beijing Solaybao Technology Co., Ltd.; Dodecyl guanidine monohydrochloride, purity 98%, provided by Shanghai Huayuan Century Trading Co., Ltd.; Polyhexamethylene biguanide hydrochloride, CAS No. 32289-58-0, provided by Shanghai Melin Biochemical Science and Technology Co., Ltd.

[0040] Example 1

[0041] The preparation of the enhanced antibacterial agent includes the following specific steps:

[0042] S1: According to the mass ratio of silanized nanomaterial, trifluoromethyl maleic anhydride, azobisisobutyronitrile and toluene is 0.8:1.9:0.04:40, the silanized nanomaterial and the trifluoromethyl maleic anhydride are mixed uniformly, then the azobisisobutyronitrile and the toluene are added, and stirred at a speed of 500 rpm under a nitrogen atmosphere for 35 min, then reacted at 75℃ for 22 h, after cooling to room temperature, filtered, washed with toluene for 3 times (the mass of toluene each time is 30% of the mass of the above toluene), and finally vacuum dried at 55℃ for 24 h to obtain a composite material;

[0043] The preparation method of the silanized nanomaterial includes the following steps:

[0044] According to the mass ratio of nanomaterial, toluene and 3-(methacryloyloxy) propyl trimethoxysilane is 0.8:70:2.3, the nanomaterial is added into toluene and ultrasonically treated for 25 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stirred at a speed of 400 rpm under a nitrogen atmosphere for 25 min, then 3-(methacryloyloxy) propyl trimethoxysilane is added, stirred and refluxed at 70℃ for 22 h, filtered, washed with toluene for 3 times (the mass of toluene each time is 20% of the mass of the above toluene), and finally vacuum dried at 55℃ for 24 h to obtain the silanized nanomaterial, wherein the nanomaterial is composed of nano-titanium dioxide and cellulose nanofiber according to the mass ratio of 0.7:0.4;

[0045] S2: according to the mass ratio of guanidines, deionized water, composite material is 1.9:10:0.8, guanidines is added to deionized water, stirred uniformly, then the composite material in step S1 is added, then constant temperature oscillation in 36℃ shaking table for 22h (oscillation frequency is 200rpm), finally the enhanced antibacterial agent is obtained, wherein the guanidines is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride according to the mass ratio of 0.8:0.6;

[0046] A degradable antibacterial sealing bag, comprising the following raw materials by weight: PLA 25 parts, PHBV 45 parts, enhanced antibacterial agent 8 parts, styrene-acrylonitrile-maleic anhydride copolymer 2 parts, antioxidant 1010 1 part and calcium stearate 0.5 part;

[0047] The preparation method comprises the following steps:

[0048] The raw materials are weighed, PLA, PHBV, enhanced antibacterial agent, styrene-acrylonitrile-maleic anhydride copolymer, antioxidant 1010 and calcium stearate are mixed uniformly, then added into a double screw extruder, the temperature of the double screw extruder is 170℃, the main machine speed is 600rpm, melt blending extrusion, granulation, then added into a single screw extrusion film blowing machine, blown into a film, finally a degradable antibacterial sealing bag is obtained.

[0049] Example 2

[0050] The enhanced antibacterial agent is prepared, and the specific steps are as follows:

[0051] S1: according to the mass ratio of silanized nanomaterial, trifluoromethyl maleic anhydride, azobisisobutyronitrile and toluene is 1:2:0.05:45, silanized nanomaterial and trifluoromethyl maleic anhydride are mixed uniformly, then azobisisobutyronitrile and toluene are added, and stirred at 600rpm under nitrogen atmosphere for 30min, then reacted at 80℃ for 23h, cooled to room temperature, filtered, washed with toluene for 3 times (each time toluene mass is 30% of the above toluene mass), finally vacuum dried at 60℃ for 24h, to obtain a composite material;

[0052] The preparation method of the silanized nanomaterial comprises the following steps:

[0053] According to the mass ratio of the nanomaterial, toluene, 3-(methacryloyloxy) propyl trimethoxysilane is 1:75:2.4, the nanomaterial is added into toluene and ultrasonic treatment for 30min (ultrasonic power is 100W, ultrasonic frequency is 40kHz), then stirring at 500rpm under nitrogen atmosphere for 20min, then adding 3-(methacryloyloxy) propyl trimethoxysilane, stirring and refluxing at 75℃ for 23h, filtering, washing with toluene for 3 times (each time toluene mass is 20% of the above toluene mass), and finally vacuum drying at 60℃ for 24h to obtain silanized nanomaterial, wherein the nanomaterial is composed of nanometer titanium dioxide and cellulose nanofiber according to the mass ratio of 0.75:0.45;

[0054] S2: According to the mass ratio of guanidine compound, deionized water, composite material is 2:12:1, the guanidine compound is added into the deionized water, stirred uniformly, then the composite material in step S1 is added, then constant temperature oscillation in the shaking table at 37℃ for 23h (oscillation frequency is 150rpm), finally the enhanced antibacterial agent is obtained, wherein the guanidine compound is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride according to the mass ratio of 0.85:0.65;

[0055] A degradable antibacterial sealing bag, comprising the following raw materials by weight: PLA 28 parts, PHBV 50 parts, enhanced antibacterial agent 9 parts, styrene-acrylonitrile-maleic anhydride copolymer 3 parts, antioxidant 168 1.5 parts and polyethylene wax 0.8 parts;

[0056] The preparation method comprises the following steps:

[0057] The raw materials are weighed, PLA, PHBV, enhanced antibacterial agent, styrene-acrylonitrile-maleic anhydride copolymer, antioxidant 168 and polyethylene wax are mixed uniformly, then added into a double screw extruder, the temperature of the double screw extruder is 175℃, the main machine speed is 700rpm, melt blending extrusion, granulation, then added into a single screw extrusion film blowing machine, blown into a film, and finally a degradable antibacterial sealing bag is obtained.

[0058] Example 3

[0059] The enhanced antibacterial agent is prepared, and the specific steps are as follows:

[0060] S1: according to the mass ratio of silanized nanomaterial, trifluoromethyl maleic anhydride, azobisisobutyronitrile and toluene is 1.2:2.1:0.06:50, the silanized nanomaterial and the trifluoromethyl maleic anhydride are mixed uniformly, then the azobisisobutyronitrile and the toluene are added, and stirring is carried out under the nitrogen atmosphere at the rotating speed of 700 rpm for 25 min, then reaction is carried out at 85℃ for 24 h, after cooling to room temperature, filtration is carried out, washing is carried out with toluene for 3 times (the mass of toluene in each time is 30% of the mass of the above toluene), and finally vacuum drying is carried out at 65℃ for 24 h, to obtain the composite material;

[0061] The preparation method of the silanized nanomaterial comprises the following steps:

[0062] According to the mass ratio of nanomaterial, toluene and 3-(methacryloyloxy) propyl trimethoxysilane is 1.2:80:2.5, the nanomaterial is added into toluene, and ultrasonic treatment is carried out for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stirring is carried out under the nitrogen atmosphere at the rotating speed of 600 rpm for 15 min, then 3-(methacryloyloxy) propyl trimethoxysilane is added, stirring reflux is carried out at 80℃ for 24 h, filtration is carried out, washing is carried out with toluene for 3 times (the mass of toluene in each time is 20% of the mass of the above toluene), and finally vacuum drying is carried out at 65℃ for 24 h, to obtain the silanized nanomaterial, wherein the nanomaterial is composed of nanometer titanium dioxide and cellulose nanofiber according to the mass ratio of 0.8:0.5;

[0063] S2: according to the mass ratio of guanidines compound, deionized water and composite material is 2.1:15:1.2, the guanidines compound is added into the deionized water, stirring is carried out uniformly, then the composite material in step S1 is added, then constant temperature oscillation is carried out in the shaking table at 38℃ for 24 h (oscillation frequency is 100 rpm), and finally the enhanced antibacterial agent is obtained, wherein the guanidines compound is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride according to the mass ratio of 0.9:0.7;

[0064] A degradable antibacterial sealing bag, comprising the following raw materials in parts by weight: PLA 30 parts, PHBV 55 parts, enhanced antibacterial agent 10 parts, styrene-acrylonitrile-maleic anhydride copolymer 4 parts, antioxidant 1076 2 parts and zinc stearate 1 part;

[0065] The preparation method comprises the following steps:

[0066] Take the mass fraction of raw materials, mix PLA, PHBV, enhanced antibacterial agent, styrene-acrylonitrile-maleic anhydride copolymer, antioxidant 1076 and zinc stearate uniformly, then add them into a double-screw extruder, the temperature of the double-screw extruder is 180℃, the main machine speed is 800rpm, melt blend extrusion, granulation, then add them into a single-screw extrusion film blowing machine, blow molding, finally get a degradable antibacterial sealing bag.

[0067] Comparative example 1

[0068] The difference between this comparative example and example 3 is that when preparing the enhanced antibacterial agent, the mass of trifluoromethyl maleic anhydride in step S1 is replaced by maleic anhydride, and the remaining steps and raw materials are implemented synchronously with example 3.

[0069] S1: According to the mass ratio of silanized nanomaterial, maleic anhydride, azobisisobutyronitrile and toluene is 1.2:2.1:0.06:50, mix the silanized nanomaterial and maleic anhydride uniformly, then add azobisisobutyronitrile and toluene, stir at 700rpm under nitrogen atmosphere for 25min, then react at 85℃ for 24h, after cooling to room temperature, filter, wash with toluene for 3 times (each time toluene mass is 30% of the above toluene mass), finally vacuum dry at 65℃ for 24h, get the composite material.

[0070] Comparative example 2

[0071] The difference between this comparative example and example 3 is that when preparing the enhanced antibacterial agent, the mass of nanomaterial in step S1 is replaced by nanometer titanium dioxide, and the remaining steps and raw materials are implemented synchronously with example 3.

[0072] The preparation method of silanized nanometer titanium dioxide includes the following steps:

[0073] According to the mass ratio of nanometer titanium dioxide, toluene and 3-(methacryloyloxy) propyl trimethoxysilane is 1.2:80:2.5, add nanometer titanium dioxide into toluene and ultrasonic treatment for 35min (ultrasonic power is 100W, ultrasonic frequency is 40kHz), then stir at 600rpm under nitrogen atmosphere for 15min, add 3-(methacryloyloxy) propyl trimethoxysilane, stir and reflux at 80℃ for 24h, filter, wash with toluene for 3 times (each time toluene mass is 20% of the above toluene mass), finally vacuum dry at 65℃ for 24h, get silanized nanometer titanium dioxide.

[0074] Comparative example 3

[0075] The difference between this comparative example and example 3 is that when preparing the enhanced antibacterial agent, the mass of nanomaterial in step S1 is replaced by cellulose nanofiber, and the remaining steps and raw materials are implemented synchronously with example 3.

[0076] The preparation method of the silanized cellulose nanofiber comprises the following steps:

[0077] According to the mass ratio of cellulose nanofiber, toluene, 3-(methacryloyloxy) propyl trimethoxysilane is 1.2:80:2.5, the cellulose nanofiber is added into toluene and ultrasonic treatment for 35 min (ultrasonic power is 100 W, ultrasonic frequency is 40 kHz), then stirring at 600 rpm for 15 min under nitrogen atmosphere, then adding 3-(methacryloyloxy) propyl trimethoxysilane, stirring and refluxing at 80°C for 24 h, filtering, washing with toluene for 3 times (each time toluene mass is 20% of the above toluene mass), and finally vacuum drying at 65°C for 24 h to obtain the silanized cellulose nanofiber.

[0078] Comparative Example 4

[0079] The difference between this comparative example and Example 3 is that when preparing the enhanced antibacterial agent, the guanidine compound in step S2 is replaced by polyhexamethylene biguanide hydrochloride with the same mass, and the remaining steps and raw materials are implemented synchronously with Example 3.

[0080] S2: According to the mass ratio of polyhexamethylene biguanide hydrochloride, deionized water, composite material is 2.1:15:1.2, polyhexamethylene biguanide hydrochloride is added into deionized water, stirred uniformly, then the composite material in step S1 is added, then constant temperature oscillation in the shaking table at 38°C for 24 h (oscillation frequency is 100 rpm), and finally the enhanced antibacterial agent is obtained.

[0081] Comparative Example 5

[0082] The difference between this comparative example and Example 3 is that when preparing the enhanced antibacterial agent, the guanidine compound in step S2 is replaced by dodecyl guanidine monohydrochloride with the same mass, and the remaining steps and raw materials are implemented synchronously with Example 3.

[0083] S2: According to the mass ratio of dodecyl guanidine monohydrochloride, deionized water, composite material is 2.1:15:1.2, dodecyl guanidine monohydrochloride is added into deionized water, stirred uniformly, then the composite material in step S1 is added, then constant temperature oscillation in the shaking table at 38°C for 24 h (oscillation frequency is 100 rpm), and finally the enhanced antibacterial agent is obtained.

[0084] Comparative Example 6

[0085] The difference between this comparative example and Example 3 is that when preparing the enhanced antibacterial agent, the silanized nanomaterial in step S1 is directly mixed with the guanidine compound in step S2, and the remaining steps and raw materials are implemented synchronously with Example 3.

[0086] The preparation method of the enhanced antibacterial agent comprises the following steps:

[0087] According to the mass ratio of guanidines, deionized water, silanized nanomaterials is 2.1:15:1.2, the guanidines is added to the deionized water, stirred uniformly, then the silanized nanomaterials is added, then constant temperature oscillation in the shaking table at 38℃ for 24h (oscillation frequency is 100rpm), finally the enhanced antibacterial agent is obtained, wherein the guanidines is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride according to the mass ratio of 0.9:0.7;

[0088] The preparation method of the silanized nanomaterials comprises the following steps:

[0089] According to the mass ratio of nanomaterials, toluene, 3-(methacryloyloxy) propyl trimethoxysilane is 1.2:80:2.5, the nanomaterials is added to toluene and ultrasonic treatment for 35min (ultrasonic power is 100W, ultrasonic frequency is 40kHz), then stirring at 600rpm under nitrogen atmosphere for 15min, then 3-(methacryloyloxy) propyl trimethoxysilane is added, stirring reflux at 80℃ for 24h, after filtration, washing with toluene for 3 times (each time toluene mass is 20% of the above toluene mass), finally vacuum drying at 65℃ for 24h, the silanized nanomaterials is obtained, wherein the nanomaterials is composed of nanometer titanium dioxide and cellulose nanofiber according to the mass ratio of 0.8:0.5.

[0090] The degradable antibacterial sealing bags prepared in examples 1-3 and comparative examples 1-6 are tested for degradability, antibacterial property, antioxidant property and mechanical property;

[0091] Degradability test: The degradability test is carried out by burying method, the specific method is: the samples of degradable antibacterial sealing bags prepared in examples 1-3 and comparative examples 1-6 are buried in containers filled with soil, after 120 days of degradation, the soil buried samples are taken out, cleaned and dried to constant weight, the degradation rate is calculated, degradation rate=(weight before burying-weight after burying) / weight before burying×100%;

[0092] Antibacterial property test: The antibacterial rate is detected according to GB / T 31402-2015 "Plastics-Test methods for antibacterial property of plastics surface", and the inhibition effect on escherichia coli and staphylococcus aureus is detected by film sticking method, the specific method is: escherichia coli or staphylococcus aureus bacteria is inoculated in flat plate culture medium, and the film is preserved for 24h, then the viable bacteria culture is carried out, the parallel experimental results of blank samples are compared, and the antibacterial rate of the sample is obtained;

[0093] Antioxidant performance test: the test method is as follows: 1,1-diphenyl-2-trinitrobenzene hydrazine (DPPH) solution with a concentration of 0.02 mg / mL is prepared by using anhydrous ethanol, the degradable antibacterial sealing bag prepared by examples 1-3 and comparative examples 1-6 is cut into a circular piece with a diameter of 10 mm, and is placed in 10 mL of the obtained DPPH solution for 30 min, the absorbance value at 517 nm before and after adding the circular piece is measured, and the DPPH clearance rate is calculated, P = (A0-A1) / A0×100%, P is the DPPH free radical clearance rate, A0 is the absorbance value before adding the circular piece, and A1 is the absorbance value after adding the circular piece;

[0094] Mechanical property test: the tensile strength is determined according to GB / T 1040.3-2006 "Determination of tensile properties of plastics-Part 3: test conditions for films and sheets", and the mechanical property is represented by the tensile strength.

[0095] The test results are shown in Table 1 below:

[0096] Table 1 Performance parameters of the degradable antibacterial sealing bag prepared by examples 1-3 and comparative examples 1-6

[0097]

[0098] From the data in Table 1 above, it can be seen from the comparison between comparative examples 1-3 and example 3 that the degradable antibacterial sealing bag prepared by replacing the trifluoromethyl maleic anhydride in step S1 with maleic anhydride or replacing the nanomaterial in step S1 with nanometer titanium dioxide or cellulose nanofiber has poorer test results compared with example 3, which indicates that the combination of trifluoromethyl maleic anhydride and silanized nanomaterial not only has good binding force, but also the fluorine atom in trifluoromethyl maleic anhydride can better improve the antioxidant performance and hydrophobicity of the sealing bag, and further improve its antibacterial property; the nanomaterial composed of nanometer titanium dioxide and cellulose nanofiber has a synergistic effect, and can effectively improve the antioxidant performance of the sealing bag, and further enhance the mechanical property of the sealing bag;

[0099] It can be seen from Comparative Examples 4-6 and Example 3 that, when the guanidine compound in step S2 is replaced with polyhexamethylene biguanide hydrochloride or dodecyl guanidine monohydrochloride in equal mass, or the silanized nanomaterial in step S1 is directly mixed with the guanidine compound in step S2, the prepared degradable antibacterial sealing bag has a poorer test result than that of Example 3, indicating that the guanidine compound composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride has a synergistic antibacterial effect, and can better improve the antibacterial performance of the sealing bag; when the silanized nanomaterial is first combined with trifluoromethyl maleic anhydride, and then combined with the guanidine compound, the interfacial compatibility between the silanized nanomaterial and PLA can be increased, the dispersibility of the silanized nanomaterial can be improved, and the antibacterial performance, antioxidant performance, mechanical performance and degradability of the sealing bag can be further improved.

[0100] As can be seen from Table 1 above, the degradable antibacterial sealing bags prepared in Examples 1-3 have better degradability, antibacterial performance, antioxidant performance and mechanical performance than the degradable antibacterial sealing bags prepared in Comparative Examples 1-6, the service life of the sealing bags is prolonged, and the overall comprehensive performance is good, which indicates that the degradable antibacterial sealing bags prepared in the present application meet the performance requirements, while the degradable antibacterial sealing bags prepared in Comparative Examples 1-6 do not meet the performance requirements.

[0101] In the description of the specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0102] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which shall be within the protection scope of the present application.

Claims

1. A biodegradable antibacterial sealing bag, characterized in that, It includes the following raw materials in parts by weight: PLA 25-30 parts, PHBV 45-55 parts, enhanced antibacterial agent 8-10 parts, compatibilizer 2-4 parts, antioxidant 1-2 parts and lubricant 0.5-1 parts; The preparation method of the enhanced antibacterial agent includes the following steps: S1: Trifluoromethyl maleic anhydride is combined with silanized nanomaterials to obtain a composite material; S2: By combining guanidine compounds with composite materials, an enhanced antibacterial agent is obtained; The preparation method of the silanized nanomaterial includes the following steps: The nanomaterials were added to toluene and sonicated for 25-35 min. Then, the mixture was stirred for 15-25 min under a nitrogen atmosphere. A silane coupling agent was added, and the mixture was stirred and refluxed at 70-80 °C for 22-24 h. After filtration, the mixture was washed with toluene and finally dried under vacuum at 55-65 °C to obtain silanized nanomaterials. The nanomaterial is composed of nano-titanium dioxide and cellulose nanofibers in a mass ratio of 0.7-0.8:0.4-0.5; The guanidine compound is composed of polyhexamethylene biguanide hydrochloride and dodecyl guanidine monohydrochloride in a mass ratio of 0.8-0.9:0.6-0.

7.

2. The biodegradable antibacterial sealing bag according to claim 1, characterized in that, Step S1 is as follows: The silanized nanomaterials and trifluoromethyl maleic anhydride were mixed evenly, then an initiator and toluene were added, and the mixture was stirred under a nitrogen atmosphere for 25-35 min. The mixture was then reacted at 75-85 °C for 22-24 h. After cooling to room temperature, the mixture was filtered, washed with toluene, and finally dried under vacuum at 55-65 °C to obtain the composite material.

3. The biodegradable antibacterial sealing bag according to claim 1, characterized in that, The silane coupling agent is 3-(methacryloyloxy)propyltrimethoxysilane.

4. The biodegradable antibacterial sealing bag according to claim 1, characterized in that, Step S2 is as follows: Guanidine compounds are added to deionized water and stirred evenly. Then, the composite material from step S1 is added, and the mixture is kept at a constant temperature of 36-38℃ for 22-24 hours to obtain the enhanced antibacterial agent.

5. A biodegradable antibacterial sealing bag according to claim 4, characterized in that, The mass ratio of the guanidine compound, deionized water, and composite material is 1.9-2.1:10-15:0.8-1.

2.

6. A method for preparing a biodegradable antibacterial sealing bag as described in any one of claims 1-5, characterized in that, Includes the following steps: Weigh out the raw materials by weight, mix PLA, PHBV, antibacterial agent, compatibilizer, antioxidant and lubricant evenly, then add to a twin-screw extruder, melt-blend extrusion, pelletize, then add to a single-screw extrusion blown film mill, blow mold to finally obtain a biodegradable antibacterial sealing bag.

7. The method for preparing a biodegradable antibacterial sealing bag according to claim 6, characterized in that, The temperature of the twin-screw extruder is 170-180℃, and the main machine speed is 600-800rpm.

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