Preparation method of double-layer polyethylene film with antibacterial activity

Abstract

The invention provides a double-layer polyethylene film with antibacterial activity. The invention discloses a rare earth / chitin composite material which is prepared from the following materials in parts by mass: 8 to 15 parts of chitosan, 2 to 7 parts of sodium periodate, 2 to 6 parts of polyethylene glycol, 1 to 4 parts of tributyl citrate, 2 to 6 parts of divinyl benzene, 3 to 9 parts of rare earth / chitin mixture, 4 to 9 parts of phthalaldehyde, 2 to 7 parts of bacteriostatic agent, 100 to 140 parts of low-density polyethylene, 3 to 9 parts of carbon fiber and 9 to 14 parts of carbon black. The rare earth substances and the chitin have bacteriostatic effects and can be synergistically matched after being mixed, so that the bacteriostatic effect of the whole polyethylene film is improved, meanwhile, the bacteriostatic agent is added into the polyethylene film, and the bacteriostatic agent contains chitosan and has very good composite bacteriostatic performance, so that the polyethylene film has a good antibacterial effect. The bacteriostatic agent has good compatibility between low-density polyethylene matrixes, the bacteriostatic performance of the finished film can be effectively improved, and the film is good in environmental protection property and excellent in comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of polyethylene film preparation, in particular to a method for preparing a double-layer polyethylene film with antibacterial properties. Background Art

[0002] With the development of science and technology and the improvement of people's living standards, people's health awareness has been continuously enhanced, and they have paid more attention to daily necessities, especially food safety and environmental sustainable development. Plastic products are a type of item that people frequently come into contact with in their daily lives, so the research and development of their antibacterial properties has important significance and practical value;

[0003] Polyethylene is one of the most important resins among polyolefin resins, and is one of the fastest growing and most in-demand materials in the world today. Polyethylene mainly includes low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc., and is widely used in packaging, medical treatment, pipes and other fields. Under specific temperature and humidity conditions such as those for storing food and medicine, the surface of polyethylene film is prone to breed bacteria, fungi and other microorganisms that are harmful to human health, which in turn contaminates food or medicine, causing it to deteriorate, mold or even rot, and easily cause foodborne diseases. Therefore, it is of great practical significance to give polyethylene film better antibacterial properties to meet people's requirements for production and life safety;

[0004] When polyethylene film is used for food packaging, it not only needs to package the food, but also needs to ensure the safety of the food. Currently, during the use of polyethylene film, when the food wrapped in polyethylene film is placed in a damp or dark place for a long time, bacteria are easy to grow on the polyethylene film, affecting the safety of the food. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the shortcomings of the prior art, the present invention provides a method for preparing a double-layer polyethylene film with antibacterial properties, which solves the problem that during the use of the existing polyethylene film, when food packaged in the polyethylene film is placed in a damp or dark place for a long time, bacteria are easily grown on the polyethylene film, affecting the safety of the food.

[0007] (II) Technical solution

[0008] To achieve the above purpose, the present invention is implemented by the following technical scheme: a double-layer polyethylene film with antibacterial properties, the material composition and its mass fraction are: 8-15 parts of chitosan, 2-7 parts of sodium periodate, 2-6 parts of polyethylene glycol, 1-4 parts of tributyl citrate, 2-6 parts of divinylbenzene, 3-9 parts of rare earth chitosan mixture, 4-9 parts of phthalaldehyde, 2-7 parts of antibacterial agent, 100-140 parts of low-density polyethylene, 3-9 parts of carbon fiber, and 9-14 parts of carbon black. Preferably, the polyisophthalamide metaphenylene diamine condensate is prepared by condensation of isophthaloyl chloride and metaphenylene diamine.

[0009] Preferably, the rare earth chitosan composite is prepared by the following method: chitosan is placed in an acetic acid solution, mixed, sulfate is added, mixed, methanol solution is added for reflux, filtered, solid matter is washed, and solid matter is dried to obtain the rare earth chitosan composite.

[0010] Preferably, the antibacterial agent is prepared by the following method: taking chitosan, adding it to deionized water of 20-35 times its weight, stirring evenly to obtain a preliminary mixed solution;

[0011] Add an emulsifier to the preliminary mixed solution, stir at 400-800 rpm for 25-45 minutes, add tetrabutyl titanate, hydrolyze for 2-5 hours, and finally add oleic acid diethanolamide, stir evenly to obtain an antibacterial agent.

[0012] According to any one of claims 1 to 4, a method for preparing a double-layer polyethylene film with antibacterial properties is prepared by the following method:

[0013] S1. Mix low-density polyethylene, carbon fiber and carbon black in a certain proportion to form a mixture;

[0014] S2, adding an organic solvent for dissolving into the mixture of step 1, stirring evenly while heating to obtain a uniform mixture;

[0015] S3, fully mix sodium periodate, polyethylene glycol, tributyl citrate, divinylbenzene, rare earth chitin mixture, phthalaldehyde and antibacterial agent, then add the mixed raw materials to the mixture in the above step 2 and continue stirring for 1.5-2h;

[0016] S4, casting the mixed material prepared in step 3 onto a substrate, and drying it in a constant temperature oven at 50-60° C. to obtain the film.

[0017] (III) Beneficial effects

[0018] The present invention provides a method for preparing a double-layer polyethylene film with antibacterial properties, which has the following beneficial effects:

[0019] 1. The present invention mixes rare earth materials with chitosan. Both rare earth materials and chitosan have antibacterial effects. After mixing, the two can cooperate with each other to improve the antibacterial effect of the entire polyethylene film. At the same time, an antibacterial agent is added to the inside of the polyethylene film. The antibacterial agent contains chitosan and has good composite antibacterial properties. The antibacterial agent has good compatibility with the low-density polyethylene matrix and can effectively improve the antibacterial properties of the finished film. The film of the present invention has good environmental protection and excellent comprehensive performance.

[0020] 2. The present invention uses phthalaldehyde as a cross-linking agent to cause a cross-linking reaction in the macromolecular network structure. Compared with traditional small molecule cross-linking agents such as glutaraldehyde, the use of phthalaldehyde can introduce a rigid structure of benzene rings into the macromolecular cross-linked network structure, thereby further improving the thermal stability and mechanical properties of the product. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Embodiment 1:

[0023] The embodiment of the present invention provides a double-layer polyethylene film with antibacterial properties, the material composition and its mass fraction are: 8 parts of chitosan, 2 parts of sodium periodate, 2 parts of polyethylene glycol, 1 part of tributyl citrate, 2 parts of divinylbenzene, 3 parts of rare earth chitosan mixture, 4 parts of phthalaldehyde, 2 parts of antibacterial agent, 100 parts of low-density polyethylene, 3 parts of carbon fiber, and 9 parts of carbon black

[0024] The rare earth chitosan composite is prepared by the following method: chitosan is placed in an acetic acid solution, mixed, sulfate is added, mixed, methanol solution is added for reflux, filtered, solid matter is washed, and solid matter is dried to obtain a rare earth chitosan composite.

[0025] The antibacterial agent is prepared by the following method: chitosan is taken, added into deionized water of 20-35 times its weight, stirred evenly, and a preliminary mixed solution is obtained.

[0026] Add emulsifier to the preliminary mixed solution, stir at 400-800 rpm for 25-45 minutes, add tetrabutyl titanate, hydrolyze for 2-5 hours, and finally add oleic acid diethanolamide and stir evenly to obtain an antibacterial agent.

[0027] According to any one of claims 1 to 4, a method for preparing a double-layer polyethylene film with antibacterial properties is prepared by the following method:

[0028] S1. Mix low-density polyethylene, carbon fiber and carbon black in a certain proportion to form a mixture;

[0029] S2, adding an organic solvent for dissolving into the mixture of step 1, stirring evenly while heating to obtain a uniform mixture;

[0030] S3, fully mix sodium periodate, polyethylene glycol, tributyl citrate, divinylbenzene, rare earth chitin mixture, phthalaldehyde and antibacterial agent, then add the mixed raw materials to the mixture in the above step 2 and continue stirring for 1.5-2h;

[0031] S4, casting the mixed material prepared in step 3 onto a substrate, and drying it in a constant temperature oven at 50-60° C. to obtain the film.

[0032] The present invention firstly adopts sodium periodate as an oxidant to oxidize part of the hydroxyl groups in the chitosan molecular structure into aldehyde groups, and part of the aldehyde groups in the chitosan molecular structure and the hydroxyl groups in the polyvinyl alcohol molecular structure can undergo an aldol condensation reaction, so that new chemical bonds are formed between the two, the binding force between macromolecular chains is increased, the stability of the molecular structure is greatly improved, and the mechanical properties of the product are improved. During the combustion process, more energy is consumed to destroy the structure, thereby changing the original cracking mode of the macromolecular structure, increasing the cracking temperature, and achieving a good flame retardant effect. The aldol condensation reaction process is a dehydration reaction process, and the generated water can hydrolyze the alcohol aluminum salt to form aluminum hydroxide. Once the aluminum hydroxide crystal nucleus is formed, it can be adsorbed and fixed by the polymer network formed by chitosan and polyvinyl alcohol, so that it is well dispersed in the system, and the aluminum hydroxide crystal nucleus is kept at the nanometer level, which further achieves a good flame retardant effect.

[0033] Embodiment 2:

[0034] An embodiment of the present invention provides a double-layer polyethylene film with antibacterial properties, the material composition and its mass fractions are: 10 parts of chitosan, 5 parts of sodium periodate, 4 parts of polyethylene glycol, 2 parts of tributyl citrate, 4 parts of divinylbenzene, 5 parts of rare earth chitosan mixture, 6 parts of phthalaldehyde, 4 parts of antibacterial agent, 120 parts of low-density polyethylene, 7 parts of carbon fiber, and 11 parts of carbon black.

[0035] The rare earth chitosan composite is prepared by the following method: chitosan is put into acetic acid solution, mixed, sulfate is added, mixed, methanol solution is added for reflux, filtered, solid matter is washed, and solid matter is dried to obtain the rare earth chitosan composite.

[0036] The antibacterial agent is prepared by the following method: chitosan is taken, added into deionized water of 20-35 times its weight, and stirred evenly to obtain a preliminary mixed solution;

[0037] Add an emulsifier to the preliminary mixed solution, stir at 400-800 rpm for 25-45 minutes, add tetrabutyl titanate, hydrolyze for 2-5 hours, and finally add oleic acid diethanolamide, stir evenly to obtain an antibacterial agent.

[0038] According to any one of claims 1 to 4, a method for preparing a double-layer polyethylene film with antibacterial properties is prepared by the following method:

[0039] S1. Mix low-density polyethylene, carbon fiber and carbon black in a certain proportion to form a mixture;

[0040] S2, adding an organic solvent for dissolving into the mixture of step 1, stirring evenly while heating to obtain a uniform mixture;

[0041] S3, fully mix sodium periodate, polyethylene glycol, tributyl citrate, divinylbenzene, rare earth chitin mixture, phthalaldehyde and antibacterial agent, then add the mixed raw materials to the mixture in the above step 2 and continue stirring for 1.5-2h;

[0042] S4, casting the mixed material prepared in step 3 onto a substrate, and drying it in a constant temperature oven at 50-60° C. to obtain the film.

[0043] Embodiment 3:

[0044] An embodiment of the present invention provides a double-layer polyethylene film with antibacterial properties, the material composition and its mass fractions are: 15 parts of chitosan, 7 parts of sodium periodate, 6 parts of polyethylene glycol, 4 parts of tributyl citrate, 6 parts of divinylbenzene, 9 parts of rare earth chitosan mixture, 9 parts of phthalaldehyde, 7 parts of antibacterial agent, 140 parts of low-density polyethylene, 9 parts of carbon fiber, and 14 parts of carbon black.

[0045] The rare earth chitosan composite is prepared by the following method: chitosan is put into acetic acid solution, mixed, sulfate is added, mixed, methanol solution is added for reflux, filtered, solid matter is washed, and solid matter is dried to obtain the rare earth chitosan composite.

[0046] The antibacterial agent is prepared by the following method: chitosan is taken, added into deionized water of 20-35 times its weight, and stirred evenly to obtain a preliminary mixed solution;

[0047] Add an emulsifier to the preliminary mixed solution, stir at 400-800 rpm for 25-45 minutes, add tetrabutyl titanate, hydrolyze for 2-5 hours, and finally add oleic acid diethanolamide, stir evenly to obtain an antibacterial agent.

[0048] According to any one of claims 1 to 4, a method for preparing a double-layer polyethylene film with antibacterial properties is prepared by the following method:

[0049] S1. Mix low-density polyethylene, carbon fiber and carbon black in a certain proportion to form a mixture;

[0050] S2, adding an organic solvent for dissolving into the mixture of step 1, stirring evenly while heating to obtain a uniform mixture;

[0051] S3, fully mix sodium periodate, polyethylene glycol, tributyl citrate, divinylbenzene, rare earth chitin mixture, phthalaldehyde and antibacterial agent, then add the mixed raw materials to the mixture in the above step 2 and continue stirring for 1.5-2h;

[0052] S4, casting the mixed material prepared in step 3 onto a substrate, and drying it in a constant temperature oven at 50-60° C. to obtain the film.

[0053] Comparative Example 1:

[0054] A double-layer polyethylene film with antibacterial properties, which differs from Example 1 in that an equal amount of sodium sulfate is used to replace the rare earth chitosan complex in the raw material of the antibacterial agent.

[0055] Comparative Example 2:

[0056] A double-layer polyethylene film with antibacterial properties, which differs from Example 1 in that an equal amount of chitosan is used to replace the rare earth chitosan composite in the raw material of the antibacterial agent.

[0057] Comparative Example 3:

[0058] A double-layer polyethylene film with antibacterial properties, which differs from Example 1 in that no rare earth chitosan complex is added to the raw materials of the antibacterial agent.

[0059] Performance Testing:

[0060] The following properties were tested on the polyethylene films of Examples 1-3 and Comparative Ratios 1-3:

[0061] The antibacterial rate of Escherichia coli, Staphylococcus aureus and Streptococcus albus: The antibacterial performance of polyethylene film was tested according to QB / T2591-2003 "Antibacterial Plastics - Test Methods for Antibacterial Performance and Antibacterial Effects". The original total colony count of Escherichia coli was 1.85×10°cFU / g, the original total colony count of Staphylococcus aureus was 1.90×10CFU / g, and the original total colony count of Streptococcus albus was 1.85×10°cFU / g. The test results are shown in the following table;

[0062] Anti-mildew performance: The anti-mildew performance of polyethylene film was tested according to GB / T24128-2009 "Test method for air permeability of plastics". The test results are shown in the following table;

[0063] Tensile strength: The tensile strength of polyethylene film was tested in accordance with GB / T1040.4-2006 "Determination of tensile properties of plastics Part 4: Test conditions for isotropic and orthotropic fiber reinforced composite materials". The test results are shown in the following table;

[0064]

[0065]

[0066] Therefore, in combination with Application Examples 1-3 and Application Comparative Examples 1-3, it can be seen that the double-layer polyethylene film with antibacterial properties of the present application can improve the antibacterial properties of the polyethylene film while maintaining good tensile strength and air permeability of the polyethylene film through the synergistic effect between the raw materials. Among them, the antibacterial rate of Escherichia coli is 92.23-98.84%, the antibacterial rate of Staphylococcus aureus is 90.22-97.79%, and the antibacterial rate of Streptococcus albus is 91.65-98.16%. The air permeability level is level 3 and the tensile strength is 27.1-27.3 N / mm.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-layer polyethylene film with antibacterial properties, characterized in that: The material composition and its mass proportions are: 8-15 parts of chitosan, 2-7 parts of sodium periodate, 2-6 parts of polyethylene glycol, 1-4 parts of tributyl citrate, 2-6 parts of divinylbenzene, 3-9 parts of rare earth chitosan mixture, 4-9 parts of phthalaldehyde, 2-7 parts of antibacterial agent, 100-140 parts of low-density polyethylene, 3-9 parts of carbon fiber, and 9-14 parts of carbon black.

2. A double-layer polyethylene film with antibacterial properties according to claim 1, characterized in that: The rare earth chitosan composite is prepared by the following method: chitosan is put into acetic acid solution, mixed, sulfate is added, mixed, methanol solution is added for reflux, filtered, solid matter is washed, and solid matter is dried to obtain the rare earth chitosan composite.

3. A double-layer polyethylene film with antibacterial properties according to claim 1, characterized in that: The antibacterial agent is prepared by the following method: chitosan is taken, added into deionized water of 20-35 times its weight, and stirred evenly to obtain a preliminary mixed solution; Add an emulsifier to the preliminary mixed solution, stir at 400-800 rpm for 25-45 minutes, add tetrabutyl titanate, hydrolyze for 2-5 hours, and finally add oleic acid diethanolamide, stir evenly to obtain an antibacterial agent.

4. A method for preparing a double-layer polyethylene film with antibacterial properties according to any one of claims 1 to 4, characterized in that: It is prepared by the following method: S1. Mix low-density polyethylene, carbon fiber and carbon black in a certain proportion to form a mixture; S2, adding an organic solvent for dissolving into the mixture of step 1, stirring evenly while heating to obtain a uniform mixture; S3, fully mix sodium periodate, polyethylene glycol, tributyl citrate, divinylbenzene, rare earth chitin mixture, phthalaldehyde and antibacterial agent, then add the mixed raw materials to the mixture in the above step 2 and continue stirring for 1.5-2h; S4, casting the mixed material prepared in step 3 onto a substrate, and drying it in a constant temperature oven at 50-60° C. to obtain the film.

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