Plastic antibacterial agent is an additive that can inhibit or kill bacteria, fungi, molds, algae and viruses on the plastic surface. It can inhibit the growth and reproduction of these microorganisms, so as to achieve the purpose of bacteriostasis and antibacterial. Plastic antibacterial agents are generally divided into four categories: inorganic, organic, natural and polymer antibacterial agents.

(1) inorganic antibacterial agent

Inorganic antibacterial agents mainly refer to antibacterial agents formed by attaching silver, copper, zinc and other metals or their ions to porous materials by means of ion exchange, physical adsorption, alloying or combination. Inorganic antibacterial agents use the antibacterial ability of metal ions to achieve long-term antibacterial effect through slow-release.

Inorganic antibacterial agents have good heat resistance (> 600 ℃), wide antibacterial spectrum, long effective antibacterial period, low toxicity, no drug resistance and high safety. The main varieties are: silver zeolite, silver activated carbon, silver silica gel, silver glass beads, silver hydroxyphosphate ash based antibacterial agent, titanium phosphate, silver / zinc composite, etc.

Among many metal ions, mercury, silver, cadmium, copper, zinc, etc. have strong antibacterial ability, but the safe and non-toxic ones are only limited to silver, zinc and copper ions, and the antibacterial ability of silver ions is far stronger than that of other metal ions such as zinc and copper. Therefore, inorganic silver antibacterial agents play a leading role in inorganic antibacterial agents. According to the different carriers, different kinds of inorganic silver antibacterial agents have been developed, such as zeolite loaded silver, activated carbon loaded silver, copper phosphate loaded silver, calcium phosphate loaded silver, silica gel loaded silver, zirconium phosphate loaded silver, hydroxyapatite loaded silver, glass loaded silver, etc.

The preparation and design idea of inorganic antibacterial agent is to make the inorganic ions with bactericidal property attached to the mineral carrier with large specific surface area and porosity through certain physical and chemical methods, and sterilize by slowly releasing antibacterial ions from the carrier or generating active oxygen through photo reaction. For example, the preparation of zeolite silver loaded antibacterial agent is prepared by adding AgNO3 aqueous solution to the aqueous suspension of synthetic zeolite with ion exchange capacity, using ion exchange method to attach silver ions to zeolite, and then drying and sintering; The preparation of silver loaded antibacterial agent on silica gel is to decompose SiCl4 in alkaline aqueous solution, then colloid it under acidic conditions, add AgNO3, and dry it into amorphous powder, which is the antibacterial agent; The silver bearing antibacterial agent for glass is mainly composed of silicate glass with high solubility of B2O3, in which silver ion is added as the main solution to prepare the antibacterial agent; In addition, zirconium phosphate loaded silver and hydroxyapatite loaded silver are prepared by using similar principles.

(2) organic antibacterial agent

Organic antibacterial agents mainly include quaternary ammonium salts, biguanides, alcohols, chlorine containing hydrochloric acid, (isothiazoles), organic halides, organic metal compounds, phenols, pyridines, imidazoles, haloalkanes, iodides, etc.

The main varieties of organic antibacterial agents are ammonium salts, phenol ethers, phenols, biguanides, isothiazoles, pyrrole, organic metals, imidazoles, pyridines, thiazoles, etc.

Organic antibacterial agents have the advantages of fast sterilization speed, strong sterilization ability, non-toxic part of antibacterial agents, convenient processing and good color stability. However, its heat resistance is poor (plastic is easy to decompose and fail at the processing temperature, and the decomposition products may cause secondary pollution), it is easy to precipitate in the solvent environment, easy to produce drug resistance, the decomposition products are toxic, and the safety is not as good as that of inorganic antibacterial agents.

(3) natural antibacterial agent

Natural antibacterial agents mainly come from the refining of natural plants or animals. They are mainly composed of mustard, castor oil, horseradish, Japanese cypress alcohol, mugwort, aloe, chitosan, chitin and other substances with antibacterial activity. They can be used in disposable plastic products such as food packaging bags. Natural antibacterial agents are safe and non-toxic, but there are some defects such as limited antibacterial effect, poor heat resistance, low sterilization rate and difficult processing.

(4) polymer antibacterial agent

The polymer antibacterial agent itself can be used as an antibacterial polymer material, and can also be added to other plastics as an antibacterial agent. It is obtained by introducing antibacterial functional groups. According to different functional groups, it can be divided into quaternary ammonium salt type, quaternary phosphine salt type, guanidine salt type, pyridine type and organometallic copolymer. The antibacterial functional groups can be introduced by homopolymerization or copolymerization of monomers with functional groups or by grafting.

Polymer antimicrobial agents have the advantages of low toxicity, high sterilization efficiency, long sterilization time, and good heat resistance and solvent resistance. It is a new development direction of antimicrobial agents at present.