In modern society, with people's emphasis on health and environmental protection, the development of antibacterial coatings in the field of industrial coatings has become one of the development directions of the coatings industry. Antibacterial coatings refer to coatings that have antibacterial properties on the surface of the coating to prevent the growth of bacteria and microorganisms.

Antimicrobial coatings are mainly used on walls, counters, door handles, kitchen utensils and other high-touch areas, industrial products and HVAC vents, etc., and can also be applied to gloves, On masks, carpets and textiles. Among them, antibacterial coatings can reduce cross-infection in hospitals when they are applied in medical facilities and hospital walls. Today, when the new coronavirus is raging, antibacterial coatings can also play a certain role in blocking and killing viruses, which provides important inspiration for the development of antibacterial coatings in the future.

Antibacterial agent of antibacterial coating

agent produced. That is to say, the difference between antibacterial coatings and ordinary coatings mainly lies in the selection and addition of antibacterial agents. The selection of suitable antibacterial agents is the key to the development of efficient antibacterial coatings.

 

Classification of antibacterial agents

There are three main categories of natural antibacterial agents, organic antibacterial agents and inorganic antibacterial agents.

1. Natural antibacterial agents: active substances with antibacterial activity extracted from animals and plants, divided into plant-derived antibacterial agents and animal-derived antibacterial agents. Chitosan and its derivatives are commonly used

2. Organic antibacterial agents: mainly quaternary ammonium salts, biguanides, alcohols, phenols, organic amines, pyridines, isothiazolinones wait.

3. Inorganic antibacterial agent: mainly metal powder or ion, photocatalytic type, etc. Metals mainly include Ag, Cu, Zn, etc., and photocatalytic types include titanium dioxide and zinc oxide.

 

Different antibacterial agents have different antibacterial mechanisms and antibacterial effects. Natural antibacterial agents have poor stability, are difficult to extract, and are rarely used. Organic antibacterial agents have poor temperature resistance and durability, and have certain toxic and side effects on the human body, which limits the promotion and use of organic antibacterial agents. Inorganic fungicides have the characteristics of high efficiency, broad spectrum and stability, and have become the mainstream of research and development of antibacterial agents. Among inorganic antibacterial agents, silver ions and titanium dioxide photocatalytic fungicides have the advantages of high bactericidal efficiency, no drug resistance, and broad-spectrum antibacterial, and they play a major role in the research and application of inorganic antibacterial agents. Inorganic antibacterial agents mainly achieve the effect of bacteriostasis and sterilization by destroying the activity of bacterial cell synthesis enzymes, causing cells to lose their ability to divide and proliferate and die. As shown in Figure 1.

 

Figure 1 Schematic diagram of silver ion antibacterial

 

Research progress of antibacterial agents

Nano antibacterial agent has surface effect, interface effect, small size effect, quantum size effect and macroscopic quantum tunnel effect. This series of excellent properties of nanomaterials makes nano antibacterial agent have better antibacterial effect and high safety. It is a kind of Long-acting, heat-resistant antimicrobial agent. Therefore, it has become a research hotspot in recent years. For example, nano-silver particles have quantum size effect and macroscopic quantum tunneling effect, and have strong penetrating power, and can easily enter the cells of pathogens to destroy cell activity. Its specific surface area is large, and its antibacterial activity is greatly enhanced, which is more than 200 times that of ordinary silver. Titanium dioxide nanotubes (TNTs) have a large specific surface area and special tubular structure, have high adsorption capacity and good selectivity, and can effectively kill bacteria such as Escherichia coli, Staphylococcus aureus and Salmonella.

 

(2) Research and development of composite inorganic antibacterial agents

The development of inorganic composite antibacterial agents (metal ions + photocatalytic metal oxides) is also one of the current research and development hotspots. For example, Ti-Ag composite and Cu-Zn composite antibacterial agents not only improve the comprehensive performance of antibacterial agents, but also avoid some defects of single antibacterial agents.

 

The development direction of antibacterial coatings

The following three aspects may It is the development direction of antibacterial coatings in the future:
1. Develop new composite antibacterial coatings, study the compatibility of composite antibacterial agents and various coatings, combine the advantages of different types of antibacterial agents, and make composite antibacterial coatings green Environmental protection, stable performance and long-lasting antibacterial characteristics.
2. Strengthen the application research of inorganic nano-antibacterial materials in various coatings, focusing on the dispersion, stability and storage methods of nanoparticles in coatings.
3. In-depth research on the antibacterial mechanism of various antibacterial agents, improve the detection methods and related standard systems of antibacterial agents and their product performance.

 

Antibacterial coating analysis technology and antibacterial performance testing technology

Antibacterial Coatings have broad prospects and will inevitably become one of the directions for coatings companies to invest in research and development. With the help of component analysis technology, it can provide assistance for the research and development of new antibacterial coatings. For example, the morphology analysis and characterization of inorganic antibacterial agents, the content test of inorganic antibacterial agents in inorganic antibacterial coatings, and the analysis of resin systems can shorten the research and development path of antibacterial coatings and improve research and development efficiency.

The antibacterial performance test of antibacterial coatings, the national standard for antibacterial coatings testing in China has "Antibacterial Coatings (Paint Film) Antibacterial Test Method and Antibacterial Effect Standard" (GB/T21866- 2008), "Evaluation Standards for Antibacterial Properties of Photocatalytic Antibacterial Materials and Products" (GB/T23763-2009), "Determination of Mold Resistance of Paint Films" (GB/T1741-2007), etc., the industry standard includes "Standards for Antibacterial Coatings" (HG/T3950-2007), these standards have played a role in promoting the inspection of antibacterial and antifungal properties of antibacterial coatings in China and the development of norms in the antibacterial coatings industry.

 

Excerpt from "Paint Market"