Antibacterial material capable of generating negative ions as well as preparation and application of antibacterial material

Abstract

The invention discloses an antibacterial material capable of generating negative ions and preparation and application, and belongs to the technical field of antibacterial material processing, the antibacterial material comprises the following components by weight: 50-60 parts of composite polyester, 45-55 parts of polylactic acid, 15-18 parts of negative ion composite powder and 3-5 parts of an additive; according to the invention, composite polyolefin modified by quaternary ammonium salt and polysiloxane chain segments is used as a toughening elastomer, polyester is reinforced to prepare composite polyester, then the composition of negative ion powder is optimized, the composite polyester is reinforced and compounded by epoxidized soybean oil to obtain negative ion composite powder, polylactic acid is reinforced by the composite polyester and the negative ion composite powder, and the toughness of polylactic acid is improved. The negative ion induction amount and the antibacterial property of the antibacterial material are effectively enhanced, and the stretching and piercing properties of the antibacterial material are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of antibacterial material processing, and particularly relates to an antibacterial material capable of generating negative ions, and its preparation and application. Background Art

[0002] With the improvement of modern living standards, people's requirements for the air quality and sanitary conditions in the living environment are becoming increasingly strict. Traditional antibacterial materials mainly achieve antibacterial effects by adding antibacterial agents, but these materials often have problems such as limited antibacterial effects, easy generation of drug resistance, and potential harm to the environment. At the same time, air purification technologies such as air purifiers and air filters can effectively remove suspended particles and some harmful gases in the air, but have limited bactericidal effects on bacteria and require continuous energy consumption. Negative ions refer to negatively charged particles formed after an atom or molecule obtains one or more electrons, and have the functions of air purification, antibacterial, and food preservation.

[0003] In the prior art, a Chinese invention patent with the publication number CN106626647A discloses an antibacterial fresh-keeping film. The antibacterial fresh-keeping film provided by the patent content includes a multi-layer film structure of a back layer, an intermediate layer, and a surface layer. At least one layer of the multi-layer film structure includes a negative ion material. By adding a negative ion material to the fresh-keeping film, the released negative ions have high activity and strong redox effects, can destroy the cell membrane of bacteria or the activity of cell protoplasmic active enzymes, achieve the purpose of antibacterial and sterilization, and can also eliminate ethylene released by fruits and vegetables, relieve the self-consumption of fruit and vegetable nutrients, and extend the preservation time. The negative ion material can also improve the hydrophilicity of the fresh-keeping film layer and avoid the loss of moisture from fruits and vegetables.

[0004] However, the negative ion release rate of traditional antibacterial fresh-keeping materials is only 10,000 ions / cm²·min, and the negative ion induction amount needs to be further improved. Moreover, their antibacterial performance mainly relies on negative ions, and the antibacterial performance is difficult to meet actual needs. With the continuous enhancement of environmental awareness, biodegradable materials such as polyester and polylactic acid are constantly promoted in production. However, traditional polylactic acid is too brittle and the modulus of polyester is too low, resulting in poor mechanical strength of materials based on polyester and polylactic acid.

[0005] In view of the technical deficiencies in this regard, a solution is now proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide an antibacterial material capable of generating negative ions, and its preparation and application, so as to solve the technical problems of low negative ion induction amount, poor antibacterial performance of antibacterial materials, and the mechanical strength of biodegradable antibacterial materials that need to be further improved in the prior art.

[0007] The object of the present invention can be achieved by the following technical solutions: An antibacterial material capable of generating negative ions, comprising the following components by weight: 50-60 parts of composite polyester, 45-55 parts of polylactic acid, 15-18 parts of negative ion composite powder, and 3-5 parts of additive

[0008] The composite polyester is obtained by the following steps:

[0009] A1. Under an inert gas atmosphere, mix 1,4-butanediol, polyethylene glycol, fumaric acid, succinic acid, and hydroquinone, and while stirring, raise the temperature of the mixed system to 160-180 °C, keep the temperature for reaction for 4-6 h. During the reaction process, remove the by-product water through a water separator, then raise the temperature of the mixed system to 200-220 °C, add a catalyst to the mixed system, evacuate to a negative pressure until the internal negative pressure of the mixed system is reduced to 0.1 MPa, keep the temperature for reaction for 4-5 h, cool down and discharge to obtain unsaturated polyester.

[0010] The synthesis reaction formula of the polyester is:

[0011]

[0012]

[0013] In the formula:

[0014] R 1 :

[0015] R2:

[0016] The synthesis reaction mechanism of the polyester is:

[0017] In a high-temperature environment, 1,4-butanediol, polyethylene glycol 600, fumaric acid, and succinic acid start to undergo an esterification reaction to form low-molecular-weight ester compounds. During the reaction process, the by-product water is continuously removed through a water separator to promote the reaction in the direction of forming esters. Subsequently, by raising the temperature and adding a catalyst, the esterification polycondensation reaction is accelerated, and by controlling the negative pressure of the reaction system, small-molecule by-products can be further removed, promoting the growth of polyester chains and generating high-molecular-weight polyester chains to prepare unsaturated polyester.

[0018] A2. Under an inert gas atmosphere, add the unsaturated polyester and composite polyolefin to N-methylpyrrolidone at a temperature of 85-95 °C, stir until the system is clear, add a catalyst to the mixed system, keep the temperature for reaction for 6-8 h, and perform post-treatment to obtain the composite polyester.

[0019] The synthesis reaction formula of the composite polyester is:

[0020]

[0021] The synthesis reaction mechanism of the composite polyester is as follows:

[0022] Under the condition of a catalyst, the silicon-hydrogen position on the polysiloxane chain segment in the composite polyolefin undergoes a hydrosilylation reaction with the unsaturated double bond on the polyester molecule, embedding the composite polyolefin onto the polyester to prepare the composite polyester.

[0023] Further, in step A1, the dosage ratio of 1,4-butanediol, polyethylene glycol, fumaric acid, succinic acid, and hydroquinone is 10 mol: 3 mol: 2 mol: 11 mol: 0.1 mol. The polyethylene glycol is polyethylene glycol 600. The dosage of the catalyst is 0.1 - 0.2 wt% of the total weight of the reaction monomers. The catalyst is p-toluenesulfonic acid. In step A2, the dosage ratio of the unsaturated polyester, composite polyolefin, N-methylpyrrolidone, and catalyst is 5 g: 2 g: 30 mL: 0.01 g. The catalyst is chloroplatinic acid. The post-treatment includes: after the reaction is completed, the temperature of the mixed system is lowered to room temperature. Under stirring, the mixed system is added to purified water and stirred and dispersed for 20 - 30 min, then filtered by suction. The filter cake is washed 3 times with purified water and then dried by suction. The filter cake is transferred to an oven at 70 - 80 °C and vacuum dried to constant weight to obtain the composite polyester.

[0024] Further, the composite polyolefin is prepared by the following steps:

[0025] B1. Methylvinyldiethoxysilane, octamethylcyclotetrasiloxane, and 2,4,6,8-tetramethylcyclotetrasiloxane are added to xylene and stirred. The temperature of the reaction system is raised to 110 - 120 °C. A catalyst is added to the mixed system, and the reaction is carried out under insulation for 4 - 6 h. After post-treatment, polysiloxane is obtained.

[0026] The synthesis reaction formula of polysiloxane is:

[0027]

[0028] The synthesis reaction mechanism of polysiloxane is as follows:

[0029] Under high temperature and in the environment of a catalyst, methylvinyldiethoxysilane, octamethylcyclotetrasiloxane, and 2,4,6,8-tetramethylcyclotetrasiloxane undergo hydrolysis to form siloxane chain segments with silicon hydroxyl activity, and then the siloxane chain segments undergo polycondensation to prepare polysiloxane with an olefin double bond and a long silicon oxygen chain modified with silicon-hydrogen.

[0030] B2. Under an inert gas atmosphere, polydimethylsiloxane, methacryloyloxyethyl trimethyl ammonium chloride, methyl methacrylate, and crotonic acid are added to N,N-dimethylformamide and stirred. The temperature of the reaction system is raised to 80-90 °C. An initiator solution is added dropwise to the mixed system. After the addition is complete, the reaction is carried out under heat preservation for 6-8 h, and then post-treatment is carried out to obtain the composite polyolefin.

[0031] The synthesis reaction formula of the composite polyolefin is:

[0032]

[0033] The synthesis reaction mechanism of the composite polyolefin is:

[0034] Under the action of high temperature and a free radical initiator, the unsaturated double bonds on the molecules of polydimethylsiloxane, methacryloyloxyethyl trimethyl ammonium chloride, methyl methacrylate, and crotonic acid break to form free radicals, and then a free radical polymerization reaction occurs, preparing a polyolefin crosslinked with polydimethylsiloxane as the crosslinking site to obtain the composite polyolefin.

[0035] Further, in step B1, the dosage ratio of methylvinyldiethoxysilane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, xylene, and the catalyst is 1 g:8 g:3 g:40 mL:10 mL. The catalyst is 45-55% sulfuric acid. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, and the mixture is allowed to stand for liquid separation. The organic phase is washed with purified water until neutral and then dried by suction. The organic phase is then transferred to a rotary evaporator with a water bath temperature of 80-90 °C, and the solvent is removed under reduced pressure to obtain polydimethylsiloxane.

[0036] Further, in step B2, the dosage ratio of polydimethylsiloxane, methacryloyloxyethyl trimethyl ammonium chloride, methyl methacrylate, crotonic acid, N,N-dimethylformamide, and the initiator solution is 2 g:3 g:15 g:2 g:40 mL:3 mL. The initiator solution is composed of benzoyl peroxide and N,N-dimethylformamide in a dosage ratio of 1 g:10 mL. The post-treatment includes: after the reaction is completed, the temperature of the mixed system is lowered to room temperature. Under stirring, the mixed system is added dropwise to purified water at a temperature of 5-15 °C, and then suction filtration is carried out. The filter cake is washed 3 times with purified water and then dried by suction. The filter cake is transferred to an oven at a temperature of 70-80 °C and vacuum dried to a constant weight to obtain the composite polyolefin.

[0037] Further, the preparation method of the negative ion composite powder is: adding the modified negative ion powder, epoxy soybean oil, and the catalyst to ethyl acetate, stirring and mixing, raising the temperature of the mixed system to 68-76 °C, and carrying out the reaction under heat preservation for 3-5 h, and then post-treatment is carried out to obtain the negative ion composite powder.

[0038] The synthesis reaction mechanism of the negative ion composite powder is:

[0039] Under the action of high temperature and catalyst, while keeping the epoxy soybean oil in excess, the amino group on the KH-550 molecule coated on the surface of the modified negative ion powder reacts with the epoxy group on the epoxy soybean oil molecule to undergo ring-opening condensation, promoting the compounding of the modified negative ion powder and the epoxy soybean oil, and a composite negative ion powder modified with epoxy soybean oil is prepared.

[0040] Furthermore, the dosage ratio of the modified negative ion powder, epoxy soybean oil, catalyst and ethyl acetate is 3g:5g:0.2g:30mL. The catalyst is triethylamine. The post-treatment includes: after the reaction is completed, the temperature of the mixed system is reduced to room temperature, suction filtration is carried out, the filter cake is washed 3 times with ethyl acetate and then dried by suction, the filter cake is transferred to a drying oven at 55-65 °C, and vacuum dried to constant weight to obtain the negative ion composite powder.

[0041] Furthermore, the modified negative ion powder is processed by the following steps:

[0042] C1. Add tourmaline powder, cerium oxide and vermiculite powder into a ball mill, ball mill, and pass through a 600-mesh sieve to obtain the negative ion powder;

[0043] C2. Mix the negative ion powder, KH-550, deionized water and sodium hydroxide solution, ultrasonically disperse for 40-60 min, raise the temperature of the mixed system to 75-80 °C, keep the temperature for reaction for 60-80 min, and perform post-treatment to obtain the modified negative ion powder.

[0044] The synthesis reaction mechanism of the modified negative ion powder is as follows:

[0045] Under alkaline conditions, after the siloxane bond on the KH-550 molecule is broken, silanol groups are formed and undergo condensation with the active sites on the negative ion powder particles, forming KH-550 coating modification on the surface of the negative ion powder, and the modified negative ion powder is prepared.

[0046] Furthermore, in step C1, the weight ratio of the tourmaline powder, cerium oxide and vermiculite powder is 10:3:7-8; in step C2, the dosage ratio of the negative ion powder, KH-550, deionized water and sodium hydroxide solution is 10g:3g:60mL:8mL. The post-treatment includes: after the reaction is completed, the temperature of the reaction system is reduced to room temperature, suction filtration is carried out, the filter cake is washed with purified water until neutral and then dried by suction, the filter cake is transferred to a drying oven at 60-70 °C, and vacuum dried to constant weight to obtain the modified negative ion powder.

[0047] The present invention also provides a preparation method of an antibacterial material capable of generating negative ions, including the following steps:

[0048] S1. Mix 50 - 60 g of composite polyester, 45 - 55 g of polylactic acid, 15 - 18 g of negative ion composite powder and 3 - 5 g of additive agent evenly to obtain a premix.

[0049] S2. Extrude the premix through a twin - screw extruder into a blown - film machine and blow - film to obtain a fresh - keeping film with a thickness of 18 - 22 μm.

[0050] Further, in step S1, the additive agent is composed of a dispersant, a lubricant, a plasticizer, an antioxidant and an anti - aging agent in a weight ratio of 2:1:3:1:1. Among them, the dispersant is stearate, the lubricant is one or more of butyl stearate, oleamide, ethylene bisstearamide, the plasticizer is phthalate, the antioxidant is one or more of butylated hydroxyanisole, dibutylhydroxytoluene, tert - butylhydroquinone; the anti - aging agent is one or more of antioxidant DPPD, antioxidant PPD, antioxidant H. In step S2, the temperatures of the 6 temperature zones of the twin - screw extruder from the feeding end to the discharging end are 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, 220 °C in sequence. The main shaft speed of the twin - screw extruder is 15 r / min, and the blown - film temperature is 255 - 265 °C.

[0051] The present invention also proposes an application of an antibacterial material capable of generating negative ions, applying the antibacterial material capable of generating negative ions to the field of fresh - keeping packaging of materials.

[0052] The present invention has the following beneficial effects:

[0053] 1. The antibacterial material capable of generating negative ions of the present invention is prepared by enhancing polylactic acid with composite polyester and negative ion composite powder. Composite polyester and polylactic acid itself have good biodegradability. By introducing composite polyolefin into the composite polyester and using the composite polyolefin modified with quaternary ammonium salt and polysiloxane chain segments as a toughening elastomer to enhance the composite polyester, not only the mechanical strength of the composite polyester and polylactic acid composite material is effectively improved, but also its antibacterial property is improved. By modifying and compounding the negative ion powder, a large number of epoxy groups are modified on the negative ion composite powder. While promoting the uniform dispersion of the negative ion powder in the antibacterial material, the epoxy groups can undergo ring - opening condensation with active groups such as hydroxyl groups and carboxyl groups under high - temperature action, enhancing the cross - linking degree between the molecules of the antibacterial material and further improving the mechanical strength of the antibacterial material. Moreover, the negative ions released by the negative ion powder can cooperate with the antibacterial material to further improve the antibacterial property of the antibacterial material.

[0054] 2. The antibacterial material capable of generating negative ions according to the present invention is prepared by copolymerizing and crosslinking methyl acryloyloxyethyl trimethyl ammonium chloride, methyl methacrylate, and crotonic acid with a polysiloxane containing an olefin double bond as a crosslinking agent to prepare a highly crosslinked composite polyolefin. The composite polyolefin and unsaturated polyester are compounded by hydrosilylation addition to form a more complex network structure. During the compounding process with polylactic acid, the molecular chains of polylactic acid interpenetrate and entangle with the molecular chains of the composite polyolefin and unsaturated polyester, enhancing the internal interaction force of the material and improving the overall mechanical strength of the material. When methyl acryloyloxyethyl trimethyl ammonium chloride participates in the copolymerization reaction as a monomer, its antibacterial functional group will be introduced into the molecular chain of the composite polyolefin, thereby endowing the material with antibacterial properties. Its own antibacterial properties cooperate with the negative ions generated by the antibacterial material, making the antibacterial material exhibit excellent antibacterial properties.

[0055] 3. The antibacterial material capable of generating negative ions according to the present invention, on the negative ion material, by selecting tourmaline powder with spontaneous polarization effect, cerium oxide with catalytic performance, and vermiculite powder with good adsorption performance and ion exchange ability to cooperate with each other, the amount of negative ions induced by the negative ion powder is increased, so that the negative ion induction amount of the antibacterial material is increased, and then it cooperates with the antibacterial material to further improve the antibacterial performance of the antibacterial material. By compounding it with epoxy soybean oil to prepare negative ion composite powder, the epoxy soybean oil molecule contains a long alkane straight chain with epoxy groups, which can not only effectively improve the dispersibility of the negative ion composite powder in the antibacterial material, but also play a plasticizing role and improve the flexibility of the material. Specific embodiments

[0056] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] Example 1

[0058] This example provides a preparation method of an antibacterial material capable of generating negative ions, including the following steps:

[0059] S1. Prepare negative ion powder

[0060] Weigh: 100 g of tourmaline powder, 30 g of cerium oxide, and 70 g of vermiculite powder and add them to a ball mill, ball mill, and pass through a 600-mesh sieve to obtain negative ion powder.

[0061] S2. Prepare negative ion composite powder

[0062] Weigh: 100 g of negative ion powder, 30 g of KH-550, 600 mL of deionized water, and 280 mL of 0.8 mol / L sodium hydroxide solution are added to a three-necked flask, and ultrasonically dispersed for 40 min. Fix the three-necked flask on a water bath with mechanical stirring. Raise the temperature of the three-necked flask to 75 °C, keep the temperature for reaction for 60 min, then lower the temperature of the three-necked flask to room temperature, carry out suction filtration. Wash the filter cake with purified water until neutral and then drain it. Transfer the filter cake to a drying oven at 60 °C and vacuum dry it to constant weight to obtain modified negative ion powder;

[0063] Weigh: 90 g of modified negative ion powder, 150 g of epoxy soybean oil, 6 g of triethylamine, and 900 mL of ethyl acetate are added to a three-necked flask and stirred. Raise the temperature of the three-necked flask to 68 °C, keep the temperature for reaction for 3 h, then lower the temperature of the three-necked flask to room temperature, carry out suction filtration. Wash the filter cake with ethyl acetate three times and then drain it. Transfer the filter cake to a drying oven at 55 °C and vacuum dry it to constant weight to obtain negative ion composite powder.

[0064] S3. Prepare composite polyolefin

[0065] Weigh: 20 g of methylvinyldiethoxysilane, 160 g of octamethylcyclotetrasiloxane, 60 g of 2,4,6,8-tetramethylcyclotetrasiloxane, and 800 mL of xylene are added to a three-necked flask and stirred. Raise the temperature of the three-necked flask to 110 °C, add 200 mL of 45% sulfuric acid to the three-necked flask, keep the temperature for reaction for 4 h, then lower the temperature of the three-necked flask to room temperature, let it stand for liquid separation. Wash the organic phase with purified water until neutral and then drain it. Transfer the organic phase to a rotary evaporator with a water bath temperature of 80 °C and distill off the solvent under reduced pressure to obtain polysiloxane.

[0066] Mix benzoyl peroxide and N,N-dimethylformamide evenly according to the dosage ratio of 1 g:10 mL to obtain an initiator solution;

[0067] Weigh: 60 g of polysiloxane, 90 g of methacryloyloxyethyltrimethylammonium chloride, 450 g of methyl methacrylate, 60 g of crotonic acid, and 1200 mL of N,N-dimethylformamide are added to a three-necked flask under nitrogen protection and stirred. Raise the temperature of the three-necked flask to 80 °C, add 90 mL of the initiator solution dropwise to the three-necked flask. After the dropping is completed, keep the temperature for reaction for 6 h, then lower the temperature of the three-necked flask to room temperature to obtain a composite polyolefin reaction solution;

[0068] Under stirring, drop the composite polyolefin reaction solution into a three-necked flask containing purified water at 5 °C, keep the temperature and stir for 20 min, carry out suction filtration. Wash the filter cake with purified water three times and then drain it. Transfer the filter cake to a drying oven at 70 °C and vacuum dry it to constant weight to obtain composite polyolefin, where the volume ratio of the composite polyolefin reaction solution to purified water is 1:3.

[0069] S4. Preparation of Composite Polyester

[0070] Weigh: 90.1 g of 1,4 - butanediol, 180 g of polyethylene glycol 600, 23.2 g of fumaric acid, 129.9 g of succinic acid, and 1.1 g of hydroquinone. Add them to a three - necked flask under nitrogen protection and stir. Raise the temperature of the three - necked flask to 160 °C. During the reaction, remove the by - product water through a water separator, keep the reaction at a constant temperature for 4 h. Then raise the temperature of the three - necked flask to 200 °C, add 0.43 g of p - toluenesulfonic acid to the mixed system, stir for 3 min, evacuate the three - necked flask to make the internal negative pressure drop to 0.1 MPa, keep the reaction at a constant temperature for 4 h, cool down and discharge to obtain unsaturated polyester;

[0071] Weigh: 500 g of unsaturated polyester, 200 g of composite polyolefin, and 3000 mL of N - methylpyrrolidone. Add them to a three - necked flask and stir. Raise the temperature of the three - necked flask to 85 °C, stir until the system becomes clear. Add 1 g of chloroplatinic acid to the mixed system, keep the reaction at a constant temperature for 6 h, and then lower the temperature of the three - necked flask to room temperature to obtain a composite polyester reaction solution;

[0072] Under stirring, add the composite polyester reaction solution to a three - necked flask filled with purified water. At room temperature, stir and disperse for 20 min, then filter by suction. Wash the filter cake with purified water 3 times and then drain it by suction. Transfer the filter cake to a drying oven at 70 °C and dry it under vacuum until constant weight to obtain composite polyester, where the volume ratio of the composite polyester reaction solution to purified water is 1:3.

[0073] S5. Preparation of Food Wrap

[0074] Mix zinc stearate, butyl stearate, diisobutyl phthalate, antioxidant DPPD, and butylated hydroxyanisole evenly according to the weight ratio of 2:1:3:1:1 to obtain an additive;

[0075] Weigh by weight: 50 parts of composite polyester, 45 parts of polylactic acid, 15 parts of negative - ion composite powder, and 3 parts of additive, and mix them evenly to obtain a premix;

[0076] Add the premix to a twin - screw extruder. The temperatures of the 6 temperature zones of the twin - screw extruder from the feeding end to the discharging end are 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, and 220 °C in sequence. The main shaft speed of the twin - screw extruder is 15 r / min. Extrude and blow - mold it in a blow - molding machine with a temperature of 255 °C to obtain a food wrap with a thickness of 18 - 22 μm.

[0077] Example 2

[0078] This example provides a preparation method of an antibacterial material capable of generating negative ions, including the following steps:

[0079] S1. Preparation of Negative - Ion Powder

[0080] Weigh: 100 g of tourmaline powder, 30 g of cerium oxide and 77 g of vermiculite powder, add them to a ball mill, ball mill, and pass through a 600-mesh sieve to obtain negative ion powder.

[0081] S2. Prepare negative ion composite powder

[0082] Weigh: 100 g of negative ion powder, 30 g of KH-550, 600 mL of deionized water, and 280 mL of 1.0 mol / L sodium hydroxide solution, add them to a three-necked flask, ultrasonically disperse for 50 min, fix the three-necked flask on a water bath with mechanical stirring, raise the temperature of the three-necked flask to 78 °C, keep the temperature for reaction for 70 min, lower the temperature of the three-necked flask to room temperature, filter by suction, wash the filter cake with purified water until neutral and then drain it, transfer the filter cake to a drying oven at 65 °C, and vacuum dry to constant weight to obtain modified negative ion powder;

[0083] Weigh: 90 g of modified negative ion powder, 150 g of epoxy soybean oil, 6 g of triethylamine, and 900 mL of ethyl acetate, add them to a three-necked flask and stir, raise the temperature of the three-necked flask to 72 °C, keep the temperature for reaction for 4 h, lower the temperature of the three-necked flask to room temperature, filter by suction, wash the filter cake with ethyl acetate 3 times and then drain it, transfer the filter cake to a drying oven at 60 °C, and vacuum dry to constant weight to obtain negative ion composite powder.

[0084] S3. Prepare composite polyolefin

[0085] Weigh: 20 g of methylvinyldiethoxysilane, 160 g of octamethylcyclotetrasiloxane, 60 g of 2,4,6,8-tetramethylcyclotetrasiloxane, and 800 mL of xylene, add them to a three-necked flask and stir, raise the temperature of the three-necked flask to 115 °C, add 200 mL of 50% sulfuric acid to the three-necked flask, keep the temperature for reaction for 5 h, lower the temperature of the three-necked flask to room temperature, let it stand for liquid separation, wash the organic phase with purified water until neutral and then drain it, transfer the organic phase to a rotary evaporator with a water bath temperature of 85 °C, and evaporate the solvent under reduced pressure to obtain polysiloxane.

[0086] Mix benzoyl peroxide and N,N-dimethylformamide evenly according to the dosage ratio of 1 g:10 mL to obtain an initiator solution;

[0087] Weigh: 60 g of polysiloxane, 90 g of methacryloyloxyethyltrimethylammonium chloride, 450 g of methyl methacrylate, 60 g of crotonic acid, and 1200 mL of N,N-dimethylformamide, add them to a three-necked flask under nitrogen protection and stir, raise the temperature of the three-necked flask to 85 °C, dropwise add 90 mL of the initiator solution to the three-necked flask, after dropping, keep the temperature for reaction for 7 h, lower the temperature of the three-necked flask to room temperature to obtain a composite polyolefin reaction solution;

[0088] Under stirring conditions, the composite polyolefin reaction solution was added dropwise to a three-necked flask containing purified water at 10 °C, and stirred for 25 min while maintaining the temperature. Then, suction filtration was carried out. The filter cake was washed 3 times with purified water and then dried by suction. The filter cake was transferred to a drying oven at 75 °C and vacuum dried to a constant weight to obtain the composite polyolefin. Among them, the volume ratio of the composite polyolefin reaction solution to purified water was 1:3.

[0089] S4. Preparation of composite polyester

[0090] Weigh: 90.1 g of 1,4-butanediol, 180 g of polyethylene glycol 600, 23.2 g of fumaric acid, 129.9 g of succinic acid, and 1.1 g of hydroquinone were added to a three-necked flask under nitrogen protection and stirred. The temperature of the three-necked flask was raised to 170 °C. During the reaction, the by-product water was removed through a water separator, and the reaction was carried out for 5 h while maintaining the temperature. Then, the temperature of the three-necked flask was raised to 210 °C, and 0.43 g of p-toluenesulfonic acid was added to the mixed system and stirred for 4 min. The three-necked flask was evacuated to a negative pressure inside the flask until the negative pressure decreased to 0.1 MPa, and the reaction was carried out for 4.5 h while maintaining the temperature. Then, the temperature was lowered and the product was discharged to obtain unsaturated polyester.

[0091] Weigh: 500 g of unsaturated polyester, 200 g of composite polyolefin, and 3000 mL of N-methylpyrrolidone were added to a three-necked flask and stirred. The temperature of the three-necked flask was raised to 90 °C and stirred until the system became clear. 1 g of chloroplatinic acid was added to the mixed system, and the reaction was carried out for 7 h while maintaining the temperature. Then, the temperature of the three-necked flask was lowered to room temperature to obtain the composite polyester reaction solution.

[0092] Under stirring conditions, the composite polyester reaction solution was added to a three-necked flask containing purified water. At room temperature, it was stirred and dispersed for 25 min, then suction filtered. The filter cake was washed 3 times with purified water and then dried by suction. The filter cake was transferred to a drying oven at 75 °C and vacuum dried to a constant weight to obtain the composite polyester. Among them, the volume ratio of the composite polyester reaction solution to purified water was 1:3.

[0093] S5. Preparation of food wrap

[0094] Calcium stearate, oleamide, dimethyl phthalate, antioxidant PPD, and dibutylhydroxytoluene were mixed evenly according to the weight ratio of 2:1:3:1:1 to obtain the added auxiliary agent.

[0095] Weigh by weight: 55 parts of composite polyester, 50 parts of polylactic acid, 17 parts of negative ion composite powder, and 4 parts of added auxiliary agent, and mix evenly to obtain the premix.

[0096] The premix is added into a twin-screw extruder. The temperatures of the 6 temperature zones of the twin-screw extruder from the feeding end to the discharging end are 200°C, 210°C, 210°C, 210°C, 210°C, and 220°C in sequence. The main shaft rotation speed of the twin-screw extruder is 15 r / min. It is melt-extruded into a blown film machine with a temperature of 260°C through the twin-screw extruder for blown film, and a fresh-keeping film with a thickness of 18 - 22 μm is obtained.

[0097] Example 3

[0098] This example provides a preparation method of an antibacterial material capable of generating negative ions, including the following steps:

[0099] S1. Prepare negative ion powder

[0100] Weigh: 100 g of tourmaline powder, 30 g of cerium oxide, and 80 g of vermiculite powder are added to a ball mill, ball-milled, and passed through a 600-mesh sieve to obtain negative ion powder.

[0101] S2. Prepare negative ion composite powder

[0102] Weigh: 100 g of negative ion powder, 30 g of KH-550, 600 mL of deionized water, and 280 mL of 1.2 mol / L sodium hydroxide solution are added to a three-necked flask, ultrasonically dispersed for 60 min. The three-necked flask is fixed on a water bath with mechanical stirring. The temperature of the three-necked flask is raised to 80°C, and kept for reaction for 80 min. The temperature of the three-necked flask is lowered to room temperature, filtered by suction. The filter cake is washed with purified water until neutral and then dried by suction. The filter cake is transferred to a drying oven at 70°C and vacuum dried to constant weight to obtain modified negative ion powder;

[0103] Weigh: 90 g of modified negative ion powder, 150 g of epoxy soybean oil, 6 g of triethylamine, and 900 mL of ethyl acetate are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 76°C, and kept for reaction for 5 h. The temperature of the three-necked flask is lowered to room temperature, filtered by suction. The filter cake is washed 3 times with ethyl acetate and then dried by suction. The filter cake is transferred to a drying oven at 65°C and vacuum dried to constant weight to obtain negative ion composite powder.

[0104] S3. Prepare composite polyolefin

[0105] Weigh: 20 g of methylvinyldiethoxysilane, 160 g of octamethylcyclotetrasiloxane, 60 g of 2,4,6,8-tetramethylcyclotetrasiloxane, and 800 mL of xylene are added to a three-necked flask and stirred. The temperature of the three-necked flask is raised to 120°C, and 200 mL of 55% sulfuric acid is added to the three-necked flask. Keep for reaction for 6 h. The temperature of the three-necked flask is lowered to room temperature, and left to stand for liquid separation. The organic phase is washed with purified water until neutral and then dried by suction. The organic phase is then transferred to a rotary evaporator with a water bath temperature of 90°C to distill off the solvent under reduced pressure to obtain polysiloxane.

[0106] Benzoyl peroxide and N,N-dimethylformamide were mixed evenly at a dosage ratio of 1 g:10 mL to obtain an initiator solution;

[0107] Weigh: 60 g of polysiloxane, 90 g of methacryloyloxyethyl trimethyl ammonium chloride, 450 g of methyl methacrylate, 60 g of crotonic acid and 1200 mL of N,N-dimethylformamide and add them to a three-necked flask under nitrogen protection and stir. The temperature of the three-necked flask is raised to 90 °C. 90 mL of the initiator solution is added dropwise to the three-necked flask. After the addition is complete, keep the temperature for reaction for 8 h. The temperature of the three-necked flask is lowered to room temperature to obtain a composite polyolefin reaction solution;

[0108] Under stirring conditions, the composite polyolefin reaction solution was added dropwise to a three-necked flask containing purified water at 15 °C, stirred at a constant temperature for 30 min, filtered by suction. The filter cake was washed 3 times with purified water and then dried by suction. The filter cake was transferred to an oven at 80 °C and dried under vacuum to constant weight to obtain composite polyolefin. Among them, the volume ratio of the composite polyolefin reaction solution to purified water is 1:3.

[0109] S4. Preparation of composite polyester

[0110] Weigh: 90.1 g of 1,4-butanediol, 180 g of polyethylene glycol 600, 23.2 g of fumaric acid, 129.9 g of succinic acid, 1.1 g of hydroquinone and add them to a three-necked flask under nitrogen protection and stir. The temperature of the three-necked flask is raised to 180 °C. During the reaction, by-products water was removed through a water separator. Keep the temperature for reaction for 6 h. The temperature of the three-necked flask is raised to 220 °C, and 0.43 g of p-toluenesulfonic acid is added to the mixed system, stirred for 5 min. The three-necked flask is evacuated to a negative pressure inside the three-necked flask until the negative pressure is reduced to 0.1 MPa. Keep the temperature for reaction for 5 h, cool down and discharge to obtain unsaturated polyester;

[0111] Weigh: 500 g of unsaturated polyester, 200 g of composite polyolefin, 3000 mL of N-methylpyrrolidone and add them to a three-necked flask and stir. The temperature of the three-necked flask is raised to 95 °C and stirred until the system becomes clear. 1 g of chloroplatinic acid is added to the mixed system. Keep the temperature for reaction for 8 h. The temperature of the three-necked flask is lowered to room temperature to obtain a composite polyester reaction solution;

[0112] Under stirring conditions, the composite polyester reaction solution was added to a three-necked flask containing purified water. At room temperature, stirred and dispersed for 30 min, filtered by suction. The filter cake was washed 3 times with purified water and then dried by suction. The filter cake was transferred to an oven at 80 °C and dried under vacuum to constant weight to obtain composite polyester. Among them, the volume ratio of the composite polyester reaction solution to purified water is 1:3.

[0113] S5. Preparation of food wrap

[0114] Mix magnesium stearate, ethylene bisstearamide, dibutyl phthalate, antioxidant H and tert-butylhydroquinone evenly according to the weight ratio of 2:1:3:1:1 to obtain an additive;

[0115] Weigh by weight: 60 parts of composite polyester, 55 parts of polylactic acid, 18 parts of negative ion composite powder and 5 parts of additive, and mix evenly to obtain a premix;

[0116] Add the premix into a twin-screw extruder. The temperatures of the 6 temperature zones of the twin-screw extruder from the feeding end to the discharging end are 200 °C, 210 °C, 210 °C, 210 °C, 210 °C, and 220 °C in sequence. The main shaft speed of the twin-screw extruder is 15 r / min. Extrude and blow film in a blown film machine with a temperature of 265 °C to obtain a fresh-keeping film with a thickness of 18 - 22 μm.

[0117] Comparative Example 1

[0118] The difference between this comparative example and Example 3 is that in step S1, cerium oxide was not added.

[0119] Comparative Example 2

[0120] The difference between this comparative example and Example 3 is that the modified negative ion powder in step S1 is used to replace the negative ion composite powder in step S5.

[0121] Comparative Example 3

[0122] The difference between this comparative example and Example 3 is that when preparing the composite polyolefin in step S3, polysiloxane was not added.

[0123] Performance test:

[0124] Refer to the standard GB / T 21302-2007 "General Rules for Composite Films and Bags for Packaging" to measure the breaking force, elongation at break and puncture strength of the fresh-keeping film specimens prepared in Examples 1 - 3 and Comparative Examples 1 - 3;

[0125] Refer to the standard GB / T 37206-2018 "Test Method for Antibacterial Properties of Organic Separation Membranes" to measure the antibacterial rates of the fresh-keeping film specimens prepared in Examples 1 - 3 and Comparative Examples 1 - 3 against Staphylococcus aureus and Escherichia coli;

[0126] Refer to the standard GB / T 28628-2012 "Test Method for Measuring the Amount of Air Ions Induced by Materials" to measure the amount of negative air ions induced by the fresh-keeping film specimens prepared in Examples 1 - 3 and Comparative Examples 1 - 3. The specific test results are shown in Table 1 below.

[0127] Table 1 - Performance Detection Data Table of Specimens

[0128]

[0129]

[0130] Data analysis:

[0131] By comparing and analyzing the data in Table 1 above, the tensile strength at break of the fresh-keeping film material prepared by the present invention reaches 54.6 N / 15 mm, the elongation at break reaches 473%, the puncture strength reaches 26.8 N, the antibacterial rate against Staphylococcus aureus reaches 94.7%, the antibacterial rate against Escherichia coli reaches 94.5%, and the negative ion generation amount reaches 7.38×10 7 ions / (s·m 2 ), and all performance parameters are superior to those of the comparative example;

[0132] The present invention uses a composite polyolefin modified with quaternary ammonium salt and polysiloxane chain segments as a toughening elastomer to reinforce polyester to prepare composite polyester, then optimizes the composition of the negative ion powder, and uses epoxy soybean oil to reinforce and compound it to form a negative ion composite powder. By reinforcing polylactic acid with the composite polyester and the negative ion composite powder, it not only effectively enhances the negative ion generation amount and antibacterial performance of the antibacterial material, but also improves the tensile and puncture properties of the antibacterial material.

[0133] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can better understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. An antibacterial material capable of generating negative ions, characterized in that: The invention comprises the following components in parts by weight: 50-60 parts of composite polyester, 45-55 parts of polylactic acid, 15-18 parts of negative ion composite powder and 3-5 parts of additives; The composite polyester is obtained by processing the following steps: A1. In an inert gas atmosphere, 1,4-butanediol, polyethylene glycol, fumaric acid, succinic acid and hydroquinone are mixed. Under stirring, the temperature of the mixed system is raised to 160-180°C, and the mixture is kept warm for 4-6 hours. During the reaction, by-product water is removed through a water separator. Then, the temperature of the mixed system is raised to 200-220°C, and a catalyst is added to the mixed system. The negative pressure is reduced to 0.1 MPa in the mixed system, and the mixture is kept warm for 4-5 hours. The mixture is discharged by cooling to obtain an unsaturated polyester. A2. Under an inert gas atmosphere, unsaturated polyester and composite polyolefin are added to N-methylpyrrolidone at a temperature of 85-95°C, stirred until the system is dissolved, a catalyst is added to the mixed system, and the mixture is kept warm for reaction for 6-8 hours, and post-processed to obtain composite polyester.

2. The antibacterial material capable of generating negative ions according to claim 1, characterized in that: In step A1, the amount ratio of 1,4-butanediol, polyethylene glycol, fumaric acid, succinic acid, and hydroquinone is 10 mol: 3 mol: 2 mol: 11 mol: 0.1 mol, the polyethylene glycol is polyethylene glycol 600, the amount of the catalyst is 0.1-02 wt% of the total weight of the reaction monomers, and the catalyst is p-toluenesulfonic acid; in step A2, the amount ratio of the polyester, composite polyolefin, N-methylpyrrolidone and the catalyst is 5 g: 2 g: 30 mL: 0.01 g, and the catalyst is chloroplatinic acid.

3. The antibacterial material capable of generating negative ions according to claim 1, characterized in that: The composite polyolefin is obtained by the following steps: B1, adding methylvinyldiethoxysilane, octamethylcyclotetrasiloxane and 2,4,6,8-tetramethylcyclotetrasiloxane to xylene and stirring, raising the temperature of the reaction system to 110-120° C., adding a catalyst to the mixed system, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain polysiloxane; B2. Under an inert gas atmosphere, polysiloxane, methacryloyloxyethyl trimethylammonium chloride, methyl methacrylate and crotonic acid are added to N,N-dimethylformamide and stirred. The temperature of the reaction system is raised to 80-90°C. The initiator solution is added dropwise to the mixed system. After the addition is completed, the mixture is heated for 6-8 hours and the composite polyolefin is obtained by post-treatment.

4. The antibacterial material capable of generating negative ions according to claim 3, characterized in that: In step B1, the amount ratio of methylvinyldiethoxysilane, octamethylcyclotetrasiloxane, 2,4,6,8-tetramethylcyclotetrasiloxane, xylene and catalyst is 1g:8g:3g:40mL:10mL, and the catalyst is 45-55% sulfuric acid; in step B2, the amount ratio of polysiloxane, methacryloyloxyethyltrimethylammonium chloride, methyl methacrylate, crotonic acid, N,N-dimethylformamide and initiator solution is 2g:3g:15g:2g:40mL:3mL, and the initiator solution is composed of dibenzoyl peroxide and N,N-dimethylformamide in a ratio of 1g:10mL.

5. The antibacterial material capable of generating negative ions according to claim 1, characterized in that: The preparation method of negative ion composite powder is as follows: adding modified negative ion powder, epoxidized soybean oil and catalyst into ethyl acetate, stirring and mixing, raising the temperature of the mixed system to 68-76°C, keeping the temperature for reaction for 3-5h, and post-treating to obtain the negative ion composite powder.

6. The antibacterial material capable of generating negative ions according to claim 5, characterized in that: The usage ratio of the modified anion powder, epoxy soybean oil, catalyst and ethyl acetate is 3g:5g:0.2g:30mL, and the catalyst is triethylamine.

7. The antibacterial material capable of generating negative ions according to claim 5, characterized in that: The modified anion powder is obtained by the following steps: C1. Add tourmaline powder, cerium oxide and vermiculite powder into a ball mill, grind them, and pass them through a 600-mesh sieve to obtain negative ion powder; C2. Mix the negative ion powder, KH-550, deionized water and sodium hydroxide solution, and disperse them by ultrasonic for 40-60 minutes. Raise the temperature of the mixed system to 75-80°C, and keep the mixture warm for 60-80 minutes. Post-treat to obtain the modified negative ion powder.

8. The antibacterial material capable of generating negative ions according to claim 7, characterized in that: In step C1, the weight ratio of the tourmaline powder, cerium oxide and vermiculite powder is 10:3:7-8; in step C2, the amount ratio of the negative ion powder, KH-550, deionized water and sodium hydroxide solution is 10g:3g:60mL:8mL:20mL.

9. A method for preparing an antibacterial material capable of generating negative ions as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mix the composite polyester, polylactic acid, negative ion composite powder and additives in a weight ratio of 50-60g:45-55g:15-18g:3-5g to obtain a premix; S2. The premix is ​​melt-extruded into a film blowing machine through a twin-screw extruder, and film is blown to obtain a fresh-keeping film with a thickness of 18-22 μm.

10. An application of an antibacterial material capable of generating negative ions, characterized in that: The antibacterial material capable of generating negative ions as described in any one of claims 1 to 8 is applied in the field of fresh-keeping packaging materials.

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