Antibacterial materials and their application in packaging

With the development of science and technology and the improvement of people’s living standards, people’s health awareness continues to increase, giving higher priority to the daily use of goods, especially the health of food and the cleanliness of the environment. However, in people's daily life environment, bacteria and other pathogenic microorganisms are everywhere, threatening human health. The development and application of antibacterial materials can effectively reduce or avoid bacterial cross-contamination and disease transmission.

Antibacterial material development status
Antibacterial materials refer to a new type of functional material that has its own function of killing or inhibiting microorganisms. Many substances in nature have a good function of sterilizing or inhibiting microorganisms, such as organic compounds with certain groups, some inorganic metal materials and their compounds, some minerals and natural substances. However, at present, more antibacterial materials refer to a new type of functional materials such as antibacterial plastics, antibacterial fibers and fabrics by adding certain antibacterial substances (called antibacterial agents) so that the materials have the ability to inhibit or kill surface bacteria. Ceramics, antibacterial metal materials, etc.

The large-scale application of modern antibacterial materials started during the Second World War. The Germans used military uniforms that had been processed and processed by antibacterial agents to reduce the bacterial infections and injuries of the wounded. After the 1960s, antibacterial hygiene fabrics began to be promoted in civilian products. The antibacterial agent used for antibacterial finishing is mainly composed of strong antibacterial chemicals such as organic tin and chlorinated phenol. In the 1980s, the successful development of antibacterial fibers ensured the long-term effectiveness of antimicrobial textiles. With the rapid development of petrochemicals, plastic products have become an indispensable necessities in daily life. According to reports, worldwide plastic production in 1997 was as high as 135 million tons, which is an increase of 5% per year. Since the 1980s, the development of antibacterial plastics and its wide application in home appliances, kitchen and bathroom facilities, communications, daily necessities, automobiles, building materials, and toys have made antibacterial materials enter a rapid development stage. Among them, European and American countries are mainly used for daily products and toys and other end products. The most advanced research and application of antibacterial materials is Japan. Currently, it is mainly used in household appliances, household appliances, toys, and other fields. Household products mainly focus on bath supplies, indoor products, etc. Household appliances are one of the most widely used and most widely used antibacterial materials in the industry. Antimicrobial telephones, antibacterial washing machines, antibacterial electric cookers, antibacterial electric fans, antibacterial refrigerators, and antibacterial air conditioners have a considerable share in the Japanese domestic market. .

In China, the development and production of antibacterial materials was relatively late. Until the mid-1990s, antibacterial materials in China were used in a very small number of areas other than paint preservation.

Over the past few years to track and research the development of inorganic inorganic antibacterial agents, China has achieved remarkable results in this field, and an antibacterial material-related industry has begun to take shape. In the late 1990s, antibacterial agents and antibacterial plastics entered a period of rapid development in China. It is estimated that in 1999, the output of antibacterial agents in China reached 150 tons, with sales of 12 million yuan and output value of antibacterial products of 100 billion yuan. Antibacterial agent production is expected to reach 500 tons in 2005, antibacterial product output value of 40 billion yuan. A large number of companies, in close cooperation with universities and colleges and scientific research institutions, have made rapid progress in various fields such as the industrialization and application development of inorganic antibacterial agents, organic antibacterial agents, photocatalytic antibacterial agents and antibacterial materials. The cooperation project of the Chinese Academy of Sciences and the Haier Group, “Research and Application of Antimicrobial Appliances and Antimicrobial Plastics,” won the second prize of the National Science and Technology Progress Award in 2000, marking that China’s antibacterial material research and application technology has entered the international advanced ranks. College of Materials Science and Engineering of Southwest Jiaotong University successfully developed ZnO crystalline composite antibacterial agents and applied them to plastic packaging materials to develop antibacterial bags with an antibacterial rate of over 99%. Due to the unique colorless property of ZnO crystalline composite antibacterial agent, adding the substrate will not change the color of the substrate, so it can be made into a transparent polycarbonate-polyethylene antibacterial material. In addition, due to the multi-functional nature of the ZnO crystalline state itself, the plastic packaging material added with the ZnO crystalline composite antibacterial agent also has features such as high strength, good preservation, and the like. In addition to plastic packaging, it can also be used for surface coating of paper packaging and metal packaging. This kind of antibacterial packaging material has received extensive attention from users.

Classification and Characteristics of Antimicrobial Agents Antimicrobial agents are chemical substances that are highly sensitive to microbes and can impart anti-microbial properties to materials when they are added in small quantities. That is, the antibacterial agent is a substance that can make microorganisms such as bacteria, fungi and the like unable to develop or inhibit the growth of microorganisms.

1. Organic Antibacterial Agents Organic antibacterial agents have reached 500 species, but only a few dozen are commonly used. The main varieties are: quaternary ammonium salts, biguanides, alcohols, phenols, organometallics, pyridines, imidazoles, and thiophenes. Organic antibacterial agents destroy cell membranes through chemical reactions, denature proteins, and block metabolism, thereby acting as a bactericidal, antiseptic, and mildew-proof agent. Organic antibacterial agents are fast acting, have good operability, strong stability, and have certain specificity for the inhibition of microorganisms. Therefore, organic antibacterial agents can be subdivided into antibacterial agents, preservatives, mildewproofing agents, and algaecides.

2. Inorganic antibacterial agents Inorganic antibacterial agents are obtained by physical adsorption, ion exchange and other methods, and silver, copper, zinc and other metals or metal ions are supported on the surface of porous materials such as zeolite, silica gel, titanium dioxide, and zirconium phosphate. Among them, the silver-carrying antibacterial agent has the strongest antibacterial ability, and thus the commercial antibacterial agents are mostly silver-based antibacterial agents. Inorganic antibacterial agents can be classified into silicates, phosphates, oxides, and others (such as activated carbon complexes) depending on the carrier. According to the different active ingredients of the antibacterial agent, it can be divided into silver (including metal ions such as Ag+?Cu2+?Zn2+) and titanium (TiO2 and the like having photocatalysis) antibacterial agents. The advantages of inorganic antibacterial agents are safety, heat resistance, and durability. The disadvantages are the high price and the delay of antibacterial. They can't quickly kill bacteria like organic antibacterial agents. In addition, silver ions tend to generate silver oxide or undergo photocatalytic reduction to metallic silver, which has the disadvantage of discoloring the product. Inorganic antibacterial agents are suitable for plastics processing and are widely used in antibacterial plastics.

3. Natural Antibacterial Agents Natural antibacterial agents are mainly refined from animals and plants, such as extracts of Hawthorn, Mengzongzhu, mint and lemon leaves, and chitosan extracted from crabs and shrimps. Chitosan is a positively charged monomeric substance, has good biological activity, and is compatible with biological energy; it can exhibit antibacterial activity against various bacteria. The use of natural raw materials as antimicrobial agents has not been able to achieve large-scale marketization due to safety and processing conditions, and is currently rarely used in synthetic resins.

4. The macromolecular antibacterial agents Kawabata and Nishiguchi first discovered that the synthesized pyridine-type backbone polymers have the function of killing bacteria, and confirmed that the sterilizing mechanism of pyridine macromolecules also captures bacteria through the function of molecular chains adsorbing microorganisms, and through the molecules The charge carried by the chain acts with the microorganisms, thus inactivating the microorganisms and completing the sterilization process. Li and SHEN et al. synthesized a polyolefin material with a pyridine side group on the basis of this, and it was also found to have a significant bactericidal function. The discovery of synthetic polymer materials with bactericidal function indicates a bright future for the application of high-molecular antibacterial agents for the preparation of antimicrobial plastics. Synthetic polymeric antibacterial agents can overcome the disadvantages of poor heat resistance of natural antibacterial agents and can be obtained directly through synthesis with different mechanical properties. New antibacterial materials for performance and biological performance.

5. Photocatalytic inorganic antibacterial agents Studies have shown that the materials that can be used as photocatalytic antibacterial agents are mainly n-type semiconductor materials, such as TiO2?ZnO?CdS?WO3?SnO2?ZrO2 and so on. Among them, TiO2 is currently the most common photocatalytic antibacterial agent, especially anatase TiO2. The material is low in toxicity, safe to the human body, non-irritating to the skin, strong in antibacterial ability, wide in antibacterial spectrum, and has instant antibacterial effect. Photocatalytic antibacterial agents are non-toxic, non-toxic, non-irritating, non-irritating, white in color, good in color stability, no discoloration under high temperature, no decomposition, low price, and rich in resources. Therefore, photocatalytic antibacterial agents also become antibacterial materials. One of the research hotspots.

Application of Antibacterial Materials in Packaging Packaging materials are often used to directly contact packaging. When packaging cooked foods and nutritious items such as candy, it is easy to cause growth and reproduction of microorganisms on packaging materials. In addition, due to the general accumulation of goods in the process of warehousing, poor air circulation, and high environmental humidity, it is easy to cause the packaging materials to infect microorganisms. Therefore, the antibacterial packaging material is suitable for the application of nutritious goods such as cooked foods, fresh foods, candy, and vegetables.

1. Application of antibacterial plastics in packaging Antimicrobial plastics are widely used in the packaging field. Antibacterial packaging films are one of the important application fields of antibacterial plastics. In China, antibacterial film packaging bags, antibacterial food cling films, and especially antibacterial cling film materials used in fresh vegetable packaging have become commonplace in the market. Antibacterial packaging films for meat products are coated with natural or synthetic antibacterial ingredients on the surface of the packaging film or injected into the packaging film. These ingredients include: enzymes, organic acids, EDTA and other metal chelating agents, lauric acid and others. Chain fatty acids? Ethanol silver and zinc and zeolite synthesis and classification. Packaging different varieties of meat foods, should use different inhibitors added materials. Due to the low concentration of antibacterial ingredients added, it will not affect human health. Hollow containers are also an important part of plastic packaging materials. At present, hollow containers are mainly used for the packaging of foods, cosmetics and medicines. The surface of containers is rich in nutrients and is suitable for microbial growth and reproduction. The antibacterial container prepared after adding an antibacterial agent or an antibacterial masterbatch can effectively inhibit the proliferation of microorganisms and promote the further development of the health and sanitation of hollow packaging containers.

2. Application of antimicrobial glass containers in packaging The new antibacterial glass packaging container is a glass container with its own antibacterial effect. It not only maintains the advantages of glass packaging containers, is clean and hygienic, but also has stable and lasting antibacterial properties. The role of bacteria, is a glass container upgrade product. The special antibacterial glass containing different additives releases appropriate amounts of atoms with antibacterial action under the combined action of water, acid, salt and light.