Polyethylene master batch with antibacterial property and preparation method thereof

Abstract

The invention provides a polyethylene master batch with antibacterial performance and a preparation method thereof. The preparation method of the polyethylene master batch with the antibacterial property comprises the following steps: depositing inorganic metal ions on the surface of nano calcium carbonate, reducing the inorganic metal ions into nano particles in situ to form modified nano calcium carbonate, and further compounding and processing the modified nano calcium carbonate into polyethylene to prepare the polyethylene master batch with uniform dispersion and excellent antibacterial property. The modified nano calcium carbonate is used as an additive and can be uniformly and stably dispersed in polyethylene, so that the antibacterial property of the polyethylene master batch is further improved.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, and particularly to a polyethylene masterbatch with antibacterial properties and a preparation method thereof. Background Art

[0002] Polyethylene (PE) material is one of the synthetic resins with the largest consumption in the world, and has characteristics such as high strength, corrosion resistance, insulation, and transparency. Polyethylene materials generally do not have antibacterial properties. Adding antibacterial agents to polyethylene polymer materials enables the polyethylene materials to have the function of killing microorganisms or inhibiting the reproduction of microorganisms. Antibacterial agents are generally divided into three categories. The first category is inorganic antibacterial agents such as metals like Ag, Cu, Hg, and inorganic antibacterial agents of metal oxides and non-metal oxides such as ZnO, TiO2, and CeO2; the second category is organic antibacterial agents such as quaternary ammonium salts, guanidines, and halogenated phenols; the third category is natural antibacterial agents, which can be directly extracted from animals and plants, such as natural compounds like chitosans, polypeptides, and phenols. Generally, inorganic material antibacterial agents are selected and added to polyethylene to prepare polyethylene antibacterial materials. Inorganic antibacterial agents have advantages such as broad-spectrum antibacterial properties, strong persistence, high temperature resistance, and good biocompatibility. The disadvantages are that they are prone to agglomeration, and the direct addition results in uneven dispersion, affecting the antibacterial effect. The dispersion of inorganic antibacterial agents in polymer materials affects the overall performance of the materials. The better the dispersion, the better the antibacterial performance. Therefore, how to disperse inorganic antibacterial agents well in polymer materials is particularly important. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to disclose a polyethylene masterbatch with antibacterial properties and a preparation method thereof, so as to overcome the problems that existing inorganic antibacterial agents are prone to agglomeration, uneven distribution, and affect the antibacterial effect when added to polyethylene materials.

[0004] The principle of the present invention is as follows: Metal ions in the inorganic antibacterial agent precursor are adsorbed and deposited on the surface of nano calcium carbonate and in-situ reduced into nanoparticles to form modified nano calcium carbonate, and then further compounded and processed into polyethylene to prepare a polyethylene masterbatch with uniform dispersion and excellent antibacterial properties.

[0005] The technical problem to be solved by the present invention can be achieved through the following technical solutions:

[0006] A preparation method of a polyethylene masterbatch with antibacterial properties includes the following steps:

[0007] S1: Weigh nano calcium carbonate by mass parts, disperse it in a solvent, and stir mechanically at a stirring speed of 1500 - 2000 r / min for 1 - 2 h. Then add the precursor of the inorganic antibacterial agent and continue mechanical stirring at a stirring speed of 500 - 1000 r / min for 4 - 6 h. Stop stirring and let it stand for adsorption for 12 - 14 h. During this process, the nano calcium carbonate adsorbs metal ions in the precursor of the inorganic antibacterial agent.

[0008] S2: Add ammonia water to adjust the pH value of the reaction system to 10 - 12, start heating, and carry out the reaction. The heating temperature is 80 - 140 °C, and the reaction lasts for 12 - 14 h.

[0009] S3: Separate the solid and liquid, dry the solid part, and conduct vacuum drying at a drying temperature of 50 °C to obtain modified nano calcium carbonate;

[0010] S4: Weigh polyethylene by weight parts, and successively add modified nano calcium carbonate, calcium carbonate, and additives into a mixer. Conduct high-temperature mixing to make them evenly mixed;

[0011] S5: Then extrude it through a twin-screw extruder by melting, cool and cut it into shape, and conduct drying treatment to obtain a functional polyethylene masterbatch with antibacterial properties.

[0012] In the above technical solution, further, in step S4, the amounts of each reactant in weight parts are respectively: 45 - 55 parts of polyethylene, 1 - 10 parts of modified nano calcium carbonate, 35 - 55 parts of calcium carbonate, and 0.5 - 1 part of additives. The additives are one or several of desiccant calcium chloride, antioxidant 1010, or stearamide dispersant.

[0013] Further, in step S1, in terms of weight parts, the amounts of each component are: 1 - 10 parts of nano calcium carbonate, 0.1 - 5 parts of the precursor of the inorganic antibacterial agent, and 50 - 100 parts of the solvent.

[0014] Further, the size of the nano calcium carbonate described in step S1 is 20 - 200 nm.

[0015] Further, the solvent described in step S1 is one or several of methanol, ethanol, ethylene glycol, and glycerol. The solvent is a reducing solvent, which is used to reduce silver ions to zero-valent silver nanoparticles under heating conditions. Adding ammonia water to adjust the reaction system to alkaline can further improve the reduction efficiency.

[0016] Further, the precursor of the inorganic antibacterial agent described in step S1 is a silver-based antibacterial agent precursor, specifically one or several of silver nitrate, silver chlorate, and silver perchlorate.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention successfully loads the nano-silver antibacterial agent on the surface of nano-calcium carbonate through an in-situ reduction technique (i.e., after silver ions are adsorbed onto nano-calcium carbonate, they are reduced to silver nanoparticles under alkaline conditions by heating), obtaining modified nano-calcium carbonate.

[0019] The present invention can prepare the nano-silver antibacterial agent without the need to additionally add other reducing agents. Conventional methods often require the use of reducing agents such as glucose and sodium citrate, and the prepared nano-particles are often larger in size and have poor antibacterial performance. However, the present invention utilizes the reducibility of the solvent itself to reduce silver ions to silver nanoparticles in the zero-valent state. The reduction process is relatively mild, so the formed silver nanoparticles are smaller in size and have high antibacterial activity. In addition, in the present invention, the reaction system of the reduction process is controlled to be alkaline to further improve the reduction efficiency.

[0020] 2. The solvent of the present invention is a non-aqueous system. After drying, the modified nano-calcium carbonate loaded with the nano-silver antibacterial agent still remains in a loose dispersion state without caking, and there is no need for re-grinding and screening. The nano-silver antibacterial agent is evenly distributed on the surface of the modified nano-calcium carbonate, successfully reducing the accumulation and stacking of the nano-silver antibacterial agent. Using the modified nano-calcium carbonate as an additive, it can be evenly and stably dispersed in polyethylene, further improving the antibacterial performance of the polyethylene masterbatch.

[0021] 3. The present invention adds the modified nano-calcium carbonate as an additive to polyethylene and further processes it to successfully obtain a polyethylene masterbatch with excellent antibacterial performance. Specific Embodiments

[0022] Example 1

[0023] S1: Weigh nano-calcium carbonate by mass parts, disperse it in a solvent, and perform mechanical stirring at a stirring speed of 1500 - 2000 r / min for 2 h. Then add the inorganic antibacterial agent precursor and continue stirring at a stirring speed of 500 - 1000 r / min for 4 h, and let it stand for adsorption for 12 h.

[0024] S2: Add an ammonia water solution to adjust the pH of the reaction system to 12, start heating, and carry out the reaction at a reaction temperature of 80 °C for 12 h.

[0025] S3: Perform solid-liquid separation, dry the solid part, and perform vacuum drying at a drying temperature of 50 °C to obtain modified nano-calcium carbonate;

[0026] S4: Weigh polyethylene by weight parts, and sequentially add the modified nano-calcium carbonate, calcium carbonate, and additives into a kneader, and carry out high-temperature kneading to mix evenly;

[0027] S5: Then extrude it through a twin-screw extruder, cool and cut it into shape, and perform drying treatment to obtain a functional polyethylene masterbatch with antibacterial performance.

[0028] In step S1: the size of the nano calcium carbonate is 20 - 200 nm; by weight, the dosage of each component is: 5 parts of nano calcium carbonate, 0.5 part of inorganic antibacterial agent precursor, and 50 parts of solvent. The solvent is ethanol; the inorganic antibacterial agent precursor is a silver-based antibacterial agent precursor, specifically silver nitrate;

[0029] In step S4, by weight, the dosage of each component is: 45 parts of polyethylene, 5 parts of modified nano calcium carbonate, 40 parts of calcium carbonate, and 0.8 part of additive. The additive is specifically 0.5 part of desiccant, 0.1 part of antioxidant, and 0.2 part of dispersant.

[0030] Example 2

[0031] The difference from Example 1 is only that:

[0032] In step S1, the solvent is ethylene glycol.

[0033] In step S2, the reaction temperature is 120 °C.

[0034] Example 3

[0035] The difference from Example 1 is only that:

[0036] In step S1, by weight, the dosage of each component is: 5 parts of nano calcium carbonate, 0.8 part of inorganic antibacterial agent precursor, and 50 parts of solvent; the solvent is ethylene glycol.

[0037] In step S2, the reaction temperature is 120 °C.

[0038] In step S4, the modified nano calcium carbonate is 8 parts.

[0039] Example 4

[0040] The difference from Example 1 is only that:

[0041] In step S1, by weight, the dosage of each component is: 5 parts of nano calcium carbonate, 0.3 part of inorganic antibacterial agent precursor, and 50 parts of solvent; the solvent is glycerol;

[0042] In step S2, the reaction temperature is 140 °C and the reaction time is 14 h.

[0043] In step S4, the modified nano calcium carbonate is 3 parts.

[0044] Example 5

[0045] The difference from Example 1 is only that in step S2, heating reaction is directly carried out without adding ammonia water.

[0046] Comparative Example 1

[0047] It is basically the same as Example 1, and the difference between the two is that nano calcium carbonate is replaced with ordinary calcium carbonate.

[0048] Comparative Example 2

[0049] It is basically the same as Example 1, and the difference between the two is that step S1-3 is omitted, the inorganic antibacterial agent precursor is reduced alone in the solvent, not loaded on the nano calcium carbonate, and is separately added and mixed into the polyethylene.

[0050] Comparative Example 3

[0051] It is basically the same as Example 1, and the difference between the two is that step S1-3 is omitted and no inorganic antibacterial agent is added. The antibacterial properties of the polyethylene prepared in the above examples and comparative examples were detected.

[0052] According to GB / T 31402-2015 "Test Method for Antibacterial Properties of Plastic Surfaces", antibacterial experiments were carried out on the polyethylene masterbatches obtained in Examples 1-5 and Comparative Examples 1-3. The experimental strains were Escherichia coli and Staphylococcus aureus, and the antibacterial experimental results are shown in Table 1.

[0053] It can be seen from Examples 1-5 that under heating and alkaline conditions, a reducing solvent can gently reduce silver ions to silver nanoparticles and load them on the surface of nano calcium carbonate to form modified nano calcium carbonate. When ethylene glycol is used as the solvent, the prepared silver nanoparticles have the best antibacterial performance, because ethylene glycol has the most suitable viscosity, which is conducive to the formation of more ideal nanoparticles. As the boiling point and viscosity of the solvent increase, the reaction temperature and reaction time need to be adjusted accordingly. In addition, adjusting the reaction system to alkaline with ammonia water can more effectively promote the reduction of silver ions to silver nanoparticles and effectively improve the antibacterial performance.

[0054] It can be seen from Comparative Examples 1-3 that when nano calcium carbonate is replaced with ordinary calcium carbonate, the antibacterial performance will decrease accordingly, because ordinary calcium carbonate cannot fully disperse silver nanoparticles evenly, and there is some agglomeration, which affects the antibacterial effect. The method of the present invention first uniformly loads silver nanoparticles on nano calcium carbonate to prepare modified nano calcium carbonate, successfully avoiding the agglomeration of silver nanoparticles. Then, the modified nano calcium carbonate is mixed evenly with each material, so that the antibacterial agent will be more evenly distributed and the antibacterial effect will be better. In Comparative Example 2, the inorganic antibacterial agent was reduced alone, not loaded on the nano calcium carbonate, and added separately, so that the silver nanoparticles will agglomerate more seriously and are not evenly dispersed in the polyethylene, greatly affecting the antibacterial effect. In Comparative Example 3, since no inorganic antibacterial agent was added, the prepared sample has no antibacterial effect.

[0055] Table 1. Antibacterial experiment results

[0056]

[0057]

Claims

1. A preparation method of a polyethylene masterbatch with antibacterial properties, characterized in that, It includes the following steps: S1: First, disperse nano calcium carbonate in a solvent and mechanically stir for 1 - 2 h at a stirring speed of 1500 - 2000 r / min; then, add an inorganic antibacterial agent precursor and continue mechanical stirring for 4 - 6 h at a stirring speed of 500 - 1000 r / min; finally, let it stand for adsorption for 12 - 14 h; S2: Add ammonia water to the product obtained in step S1, adjust the pH value to 10 - 12, and heat for reaction; the heating temperature is 80 - 140 °C, and the reaction time is 12 - 14 h; S3: Carry out solid - liquid separation on the product obtained in step S2, and dry the solid to obtain modified nano calcium carbonate; S4: Add polyethylene, modified nano calcium carbonate, calcium carbonate, and additives to an internal mixer in sequence for high - temperature kneading; S5: Extrude the product obtained after high - temperature kneading in step S4 through a twin - screw extruder, cool, cut into shape, and dry to obtain a polyethylene masterbatch with antibacterial properties.

2. The preparation method of the polyethylene masterbatch with antibacterial properties according to claim 1, characterized in that, In step S3, the drying treatment is specifically: vacuum drying at a drying temperature of 50 °C.

3. The preparation method of the polyethylene masterbatch with antibacterial performance according to claim 1, characterized in that, In step 1, by weight, the nano calcium carbonate is 1 - 10 parts, the solvent is 5 - 100 parts; the inorganic antibacterial agent precursor is 0.1 - 5 parts.

4. The preparation method of the polyethylene masterbatch with antibacterial properties according to claim 1, characterized in that, In step 1, the size of the nano calcium carbonate is 20 - 200 nm.

5. The preparation method of the polyethylene masterbatch with antibacterial performance according to claim 1, characterized in that, In step 1, the inorganic antibacterial agent precursor is one or more of silver nitrate, silver chlorate, and silver perchlorate.

6. The preparation method of the polyethylene masterbatch with antibacterial properties according to claim 1, characterized in that, In step S1, the solvent is one or more of methanol, ethanol, ethylene glycol, and glycerol.

7. The preparation method of the polyethylene masterbatch with antibacterial properties according to claim 1, characterized in that, In step S4, each component is by weight: 45 - 55 parts of polyethylene, 1 - 10 parts of modified nano calcium carbonate, 35 - 55 parts of calcium carbonate, and 0.5 - 1 part of additives.

8. The preparation method of the polyethylene masterbatch with antibacterial performance according to claim 1, characterized in that, In step S4, the additives are one or more of desiccant calcium chloride, antioxidant 1010, or dispersant stearamide.

9. A preparation method of a polyethylene masterbatch with antibacterial properties, characterized in that, It is prepared by the method described in any one of claims 1 - 8.

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