阅读说明：本技术 一种壳聚糖微球负载纳米银抗菌聚丙烯材料、复合抗菌剂及其制备方法 (Chitosan microsphere-loaded nano-silver antibacterial polypropylene material, composite antibacterial agent and preparation method thereof ) 是由 许静 陈继锡 方军 于 2019-11-26 设计创作，主要内容包括：本发明公开了一种壳聚糖微球负载纳米银抗菌聚丙烯材料、复合抗菌剂及其制备方法,属于高分子材料改性领域。所述壳聚糖微球负载纳米银抗菌聚丙烯材料制备方法包括：(1)合成壳聚糖微球/纳米银复合抗菌剂；(2)将复合抗菌剂与聚丙烯树脂基体共混制备抗菌聚丙烯材料。所述复合抗菌剂是以壳聚糖微球为载体,并将纳米银负载在壳聚糖微球上,且该复合抗菌剂具有用量少,绿色环保,价格低廉,抗菌性能优异持久等优点,而由此制得的抗菌聚丙烯材料不仅具有较强的抗菌性能,其力学性能也有所提高。除此之外,该复合抗菌剂及抗菌聚丙烯材料制备工艺简单、易于操作,适用于工业化应用,具有很高的经济和社会价值。(The invention discloses a chitosan microsphere-loaded nano-silver antibacterial polypropylene material, a composite antibacterial agent and a preparation method thereof, and belongs to the field of modification of high polymer materials. The preparation method of the chitosan microsphere-loaded nano-silver antibacterial polypropylene material comprises the following steps: (1) synthesizing a chitosan microsphere/nano-silver composite antibacterial agent; (2) and (3) blending the composite antibacterial agent and the polypropylene resin matrix to prepare the antibacterial polypropylene material. The composite antibacterial agent takes chitosan microspheres as a carrier, and nano silver is loaded on the chitosan microspheres, and the composite antibacterial agent has the advantages of small dosage, environmental protection, low price, excellent and durable antibacterial performance and the like, and the prepared antibacterial polypropylene material has stronger antibacterial performance and improved mechanical performance. In addition, the composite antibacterial agent and the antibacterial polypropylene material have simple preparation process, are easy to operate, are suitable for industrial application, and have high economic and social values.)

1. A preparation method of a chitosan microsphere/nano-silver composite antibacterial agent is characterized by comprising the following steps: which comprises the following steps:

1) preparing chitosan microspheres: dissolving chitosan powder in 1% acetic acid solution, continuously stirring until the chitosan powder is completely dissolved, then adjusting the pH value of a system to be 5-6 by using NaOH solution, keeping a magnetic stirring state, sucking the anion gel solution by using an injector, slowly dripping the anion gel solution into the solution at the speed of 15-30 mL/h, continuously stirring for 12-24 h, separating, washing a solid product by using deionized water, and drying to obtain chitosan microspheres;

2) preparing silver nano particles: mixing AgNO₃Dissolving the silver nanoparticle and an anionic surfactant in deionized water to obtain a mixed solution, adding a sodium borohydride solution into the mixed solution, continuously stirring for 0.5-2 h, separating, washing a solid product with deionized water, and drying to obtain silver nanoparticles;

3) synthesis of the composite antibacterial agent: respectively dispersing the chitosan microspheres and the silver nanoparticles in deionized water to respectively obtain chitosan microsphere suspension and silver nanoparticle suspension, then slowly dropwise adding the silver nanoparticle suspension into the chitosan microsphere suspension, ultrasonically dispersing the obtained mixed solution for 6-12 h, separating, washing a solid product with deionized water, and drying to obtain the chitosan microsphere/nano silver composite antibacterial agent.

2. The preparation method of the chitosan microsphere/nano-silver composite antibacterial agent according to claim 1, which is characterized in that: the anion gel in the step 1) is one or a mixture of more than two of sodium tripolyphosphate, sodium citrate, sodium sulfate, tetrapolyphosphate and molybdate; and 2) the anionic surfactant is one or a mixture of more than two of sodium citrate, sodium dodecyl sulfate, citric acid, sodium di (2-ethylhexyl) succinate sulfonate and perfluoropolyether grease.

3. The preparation method of the chitosan microsphere/nano-silver composite antibacterial agent according to claim 1, which is characterized in that: the drying temperature in the step 1) is 37 ℃, the drying temperature in the step 2) is 60-70 ℃, and the drying temperature in the step 3) is 37 ℃.

4. The preparation method of the chitosan microsphere/nano-silver composite antibacterial agent according to claim 1, which is characterized in that: the mass ratio of the silver nanoparticles to the chitosan microspheres in the step 3) is 1/100-100/100.

5. A chitosan microsphere/nano silver composite antibacterial agent obtained according to any one of the methods of claims 1-4.

6. The application of the chitosan microsphere/nano-silver composite antibacterial agent as claimed in claim 5, wherein: a substrate is added into the chitosan microsphere/nano silver composite antibacterial agent for preparing an antibacterial material, and the substrate is polypropylene resin, ABS resin, polystyrene, polyamide, polyformaldehyde or polyester.

7. A preparation method of a chitosan microsphere loaded nano-silver antibacterial polypropylene material is characterized by comprising the following steps: uniformly mixing the chitosan microsphere/nano-silver composite antibacterial agent as claimed in claim 5 with a polypropylene resin matrix in a high-speed mixer, and then extruding and granulating the obtained mixture by a double-screw extruder, wherein the extrusion process comprises the following steps: the temperature of a first zone is 180 ℃, the temperature of a second zone is 210 ℃, the temperature of a third zone is 210 ℃, the temperature of a fourth zone is 210 ℃, the temperature of a fifth zone is 210 ℃, the temperature of a sixth zone is 180 ℃, the feeding speed is 5 r/min, and the discharging speed is 15 r/min; and then, drying the obtained antibacterial polypropylene particles in vacuum at the temperature of 60-70 ℃ to prepare the chitosan microsphere-loaded nano silver antibacterial polypropylene material.

8. The preparation method of the chitosan microsphere nano-silver-loaded antibacterial polypropylene material according to claim 7, which is characterized by comprising the following steps: the mass ratio of the chitosan microsphere/nano silver composite antibacterial agent to the polypropylene resin is 0.1-30: 100.

9. The preparation method of the chitosan microsphere nano-silver-loaded antibacterial polypropylene material according to claim 8, which is characterized by comprising the following steps: the mass ratio of the chitosan microsphere/nano silver composite antibacterial agent to the polypropylene resin is 0.3-15: 100.

10. The preparation method of the chitosan microsphere nano-silver-loaded antibacterial polypropylene material according to claim 8, which is characterized by comprising the following steps: the polypropylene resin is one of homopolymerized polypropylene and copolymerized polypropylene or a composition of the homopolymerized polypropylene and the copolymerized polypropylene.

Technical Field

The invention belongs to the field of modification of high polymer materials, and particularly relates to a chitosan microsphere-loaded nano-silver antibacterial polypropylene material, a composite antibacterial agent and a preparation method thereof.

Background

The antibacterial material is a novel functional material which can kill harmful bacteria or inhibit the growth and the reproduction of the bacteria. At present, the main objects used as antibacterial materials include textiles, plastics, ceramics, metals, paints, etc., wherein the antibacterial plastics are more and more popular due to wide application fields, household appliances, sanitary wares, children toys made of the antibacterial plastics have become a new development trend, and the antibacterial plastics have not been concerned and developed before along with the improvement of living standard of people. Polypropylene (PP) is one of five general-purpose plastics, and has incomparable advantages of other plastics, such as rich raw material sources, excellent mechanical properties, easy production and processing, wide application, low price and the like, so that the PP plastic is not only most widely applied, but also has the fastest development speed in thermoplastic plastics. Although polypropylene is widely applied to the fields of life and production such as building materials, foods, daily chemical products, sanitary products, packaging and the like, the polypropylene is easily infected by bacteria in the using and storing process, is not beneficial to the health and living environment of people, limits the long-term application of polypropylene, and in order to solve the problem, how to prepare high-efficiency antibacterial polypropylene becomes a problem to be solved urgently.

The core problem in the preparation of antimicrobial polypropylene is the selection of a suitable antimicrobial agent, which in turn depends on the development of the antimicrobial agent. At present, according to the different components of the antibacterial agent, the antibacterial agent can be divided into three categories of inorganic antibacterial agent, organic antibacterial agent and natural antibacterial agent. Among a series of inorganic antibacterial agents, silver antibacterial agents have become the main direction of antibacterial and development due to their characteristics of broad antibacterial spectrum, lasting antibacterial effect, safety, extremely low drug resistance, and the like, but have the defects of easy precipitation from products, discoloration of products, and the like. Chitosan, which is the most commonly used natural antibacterial agent, is widely present in shells of crustaceans such as insects, shrimps and crabs and cell walls of lower plants such as algae and fungi, is an antibacterial agent which is beneficial to the environment, non-toxic and non-irritant to human bodies and high in use safety, but the chitosan natural antibacterial agent has low antibacterial activity and cannot be directly dissolved in water and common organic solvents, so that the application range of the chitosan natural antibacterial agent is greatly limited.

At present, the preparation of the antibacterial polypropylene material with excellent performance is mainly limited by the following aspects: (1) antibacterial properties of the antibacterial agent. Because pure polypropylene has no bactericidal effect, the antibacterial performance of the antibacterial material directly depends on the antibacterial agent, and the stronger the antibacterial capability of the antibacterial agent is, the more excellent the antibacterial performance of the antibacterial polypropylene is; (2) compatibility and dispersibility of the antimicrobial agent with the resin matrix. The compatibility and the dispersibility are good, the agglomeration of the antibacterial agent can be avoided, the active area of the antibacterial agent is greatly increased, and the antibacterial performance is improved. In addition, stress concentration caused by agglomeration is avoided, so that the components in the antibacterial polypropylene material can fully exert the advantages of the antibacterial polypropylene material, and the integral mechanical property of the material is enhanced; (3) durability of the antimicrobial agent. The antibacterial agent is stabilized in the resin matrix, and precipitation is reduced, so that the service life of the antibacterial polypropylene material can be prolonged; (4) and (4) cost. The cost of the antibacterial agent is reduced, the preparation process is simplified, and the method is an effective means for reducing the cost of the antibacterial polypropylene.

In combination with the above factors, the invention provides a preparation method of a nano composite antibacterial agent by combining the characteristics of small size, large specific surface area, high surface energy and the like of a nano material, and the antibacterial agent is applied to the field of polymer materials, and related works at home and abroad are not reported yet.

Disclosure of Invention

The invention aims to provide a chitosan microsphere-loaded nano-silver antibacterial polypropylene material and a preparation method thereof aiming at the defects of the prior art, and also provides a chitosan microsphere/nano-silver composite antibacterial agent.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a preparation method of a chitosan microsphere/nano-silver composite antibacterial agent comprises the following steps:

1) preparing chitosan microspheres: dissolving chitosan powder in 1% acetic acid solution, continuously stirring until the chitosan powder is completely dissolved, then adjusting the pH value of a system to be 5-6 by using NaOH solution, keeping a magnetic stirring state, sucking the anion gel solution by using an injector, slowly dripping the anion gel solution into the solution at the speed of 15-30 mL/h, continuously stirring for 12-24 h, separating, washing a solid product by using deionized water, and drying in a constant-temperature drying box at 37 ℃ to obtain chitosan microspheres;

2) preparing silver nano particles: mixing AgNO₃Dissolving an anionic surfactant and the anionic surfactant in deionized water to obtain a mixed solution, adding a freshly prepared sodium borohydride solution into the mixed solution, continuously stirring for 0.5-2 h, separating, washing a solid product with the deionized water, and drying in vacuum at 60-70 ℃ to obtain silver nanoparticles;

3) synthesis of the composite antibacterial agent: respectively dispersing the chitosan microspheres and the silver nanoparticles in deionized water to respectively obtain chitosan microsphere suspension and silver nanoparticle suspension, then slowly dropwise adding the silver nanoparticle suspension into the chitosan microsphere suspension, ultrasonically dispersing the obtained mixed solution for 6-12 h, separating, washing a solid product with the deionized water, and drying in a constant-temperature drying oven at 37 ℃ to obtain the chitosan microsphere/nano silver composite antibacterial agent.

The anion gel in the step 1) is one or a mixture of more than two of sodium tripolyphosphate, sodium citrate, sodium sulfate, tetrapolyphosphate and molybdate; and 2) the anionic surfactant is one or a mixture of more than two of sodium citrate, sodium dodecyl sulfate, citric acid, sodium di (2-ethylhexyl) succinate sulfonate and perfluoropolyether grease.

The mass ratio of the silver nanoparticles to the chitosan microspheres in the step 3) is 1/100-100/100.

Further, the invention also provides a preparation method of the chitosan microsphere-loaded nano-silver antibacterial polypropylene material, which comprises the following steps of uniformly mixing the chitosan microsphere/nano-silver composite antibacterial agent and a polypropylene resin matrix in a high-speed mixer, and then extruding and granulating the obtained mixture through a double-screw extruder, wherein the extrusion process comprises the following steps: the temperature of a first zone is 180 ℃, the temperature of a second zone is 210 ℃, the temperature of a third zone is 210 ℃, the temperature of a fourth zone is 210 ℃, the temperature of a fifth zone is 210 ℃, the temperature of a sixth zone is 180 ℃, the feeding speed is 5 r/min, and the discharging speed is 15 r/min; and then, drying the obtained antibacterial polypropylene particles in vacuum at the temperature of 60-70 ℃ to prepare the chitosan microsphere-loaded nano silver antibacterial polypropylene material.

The mass ratio of the chitosan microsphere/nano silver composite antibacterial agent to the polypropylene resin is 0.1-30: 100, and preferably 0.3-15: 100.

The polypropylene resin is one of homopolymerized polypropylene and copolymerized polypropylene or a composition of the homopolymerized polypropylene and the copolymerized polypropylene.

In addition, the chitosan microsphere/nano silver composite antibacterial agent prepared by the invention is not only suitable for polypropylene materials, but also can be added with ABS resin, polystyrene, polyamide, polyformaldehyde, polyester and other matrixes to prepare other antibacterial materials.

The invention improves the traditional formula, combines the characteristics of small size, large specific surface area, high surface energy and the like of the nano material, takes the natural polymer chitosan microspheres as the carrier and loads the nano silver inorganic antibacterial agent, thereby not only retaining the original performances of the silver, the chitosan and the polymer matrix, but also obtaining the performances which are not possessed by the original components.

Firstly, the chitosan microsphere prepared by the invention has a large amount of positive charges on the surface, and the silver nanoparticles have negative charges on the surface, so the structural characteristics endow the composite antibacterial agent with various advantages: (1) chitosan exhibits excellent antibacterial properties at pH less than 7, mainly due to protonated amino-NH₃ ⁺Can interact with the bacterial negative charge cell membrane and DNA, thereby achieving the bacteriostatic effect. and-NH is generated in the synthesis process of the chitosan microspheres₂Is protonated, so that the chitosan can fully exert the antibacterial performance; (2) the positive charges on the surface of the chitosan microsphere and the negative charges on the surface of the silver nanoparticles generate electrostatic attraction, and the acting force is strong, so that the silver nanoparticles can be firmly fixed on the polymer matrix; (3) the chitosan microsphere has small size and larger surface energy, can improve the compatibility between the chitosan and the polypropylene and ensure the compatibilityThe silver nanoparticles have good dispersibility; (4) because the cell membrane of the bacteria has negative charges, the positive charges on the surface of the chitosan microsphere can attract the bacteria directionally, and the bacteria can be killed quickly and accurately; (5) the chitosan and the silver exist in a small-size form, so that the specific surface area is larger, and the antibacterial effect is better; (6) the addition of the nano silver can overcome the defects of low antibacterial activity of the chitosan, contact bacteriostasis and the like, and expand the application range of the chitosan. And secondly, the addition of the composite antibacterial agent can simplify the preparation process of the antibacterial polypropylene material and improve the mechanical property of the polypropylene material.

The invention has the beneficial effects that:

(1) natural polymer chitosan microspheres are used as a carrier, and the nano-silver inorganic antibacterial agent is loaded, so that the nano-silver is buffered and released, and the antibacterial time is longer;

(2) the chitosan microspheres and the polypropylene have good compatibility, so that good dispersibility of the nano-silver in plastic products is ensured, and meanwhile, the antibacterial stability and durability of the material are improved;

(3) the nano silver and the chitosan microspheres are both antibacterial agents, and the antibacterial activity can be improved and the application range of the antibacterial material can be expanded by compounding the nano silver and the chitosan microspheres;

(4) the chitosan microspheres can attract bacteria directionally, and the chitosan and the silver exist in small-size forms, so that the composite antibacterial agent and the antibacterial polypropylene material have more excellent antibacterial performance;

(5) the chitosan is used as a natural polymer material, is green and environment-friendly, has wide source and low price, so that the use of nano silver can be properly reduced, the cost of the antibacterial polypropylene material is reduced, and the biological safety of the antibacterial polypropylene material is improved;

(6) the chitosan microsphere loaded nano-silver antibacterial agent can be directly added into a polypropylene matrix to prepare the antibacterial material, the preparation of antibacterial master batches is not needed, the preparation process is simple, and the large-scale industrial production is facilitated.

Drawings

FIG. 1 is a schematic view of chitosan structure;

FIG. 2 is a schematic diagram of the structure of chitosan microspheres;

FIG. 3 is a schematic view of the complex structure of chitosan microsphere/nano silver composite antibacterial agent.

Detailed Description

The present invention is further illustrated by the following examples, but the present invention is not limited to the following examples and embodiments.