Research and effect comparison of antibacterial ag

Research and effect comparison of antibacterial agents for low-temperature and high-temperature powder coatings

research and effect comparison of antibacterial agents for low-temperature and high-temperature powder coatings

September 27, 2020

antibacterial agents can be divided into organic antibacterial agents and inorganic antibacterial agents according to their different materials. Organic antibacterial agents are traditional antibacterial agents, which have been widely used in various industrial fields; Inorganic antibacterial agents are prepared by combining antibacterial components Ag +, Cu2 +, Zn2 + plasma and their compounds with other metals in inorganic materials. In some fields, organic antibacterial agents have developed rapidly because of their good heat resistance, high safety and long antibacterial durability. They can be widely used in coatings, organic plastics, fibers, ceramics, enamel and other fields

powder coatings are often used in the environment with humid climate and moderate temperature. The surface of the coating may be invaded by harmful microorganisms such as bacteria and mold, resulting in the coating fouling, discoloration, chalking and falling off, and losing the protective and decorative function of the substrate. If harmful bacteria come into contact with human body, they will also infect various diseases and threaten human health

since the global pandemic of covid-19, antibacterial materials have made great progress. In the field of powder coating, because powder coating products are closely related to people's lives, antibacterial and antiviral powder coating products will become a new trend of more than 200000 biodegradable recycling boxes in the future, and new antibacterial functional materials will be more and more welcomed by consumers

due to the generally high baking temperature and long baking time of powder coatings, there are relatively few kinds of organic antibacterial agents that can be used for powder coatings. For powder coatings with low baking temperature and short baking time, organic zinc and organic copper antibacterial agents can be used for antibacterial powder coatings in low-temperature process due to their high cost performance. Among inorganic antibacterial agents, silver and zinc inorganic antibacterial agents are typical representatives of inorganic antibacterial agents

as early as the 4th century BC, human beings found that silver has the effect of disinfection and sterilization. Using silver kettles to store and purify drinking water and wine, wound healing is very effective. With the development of modern science and technology, it has been found that pure silver is non-toxic and inert to human cells, viruses and other microorganisms. However, under the action of H2O and O2 in the environment, the silver atoms on the surface of metallic silver or silver carrying materials will release free silver ions that can withstand a pressure of up to 0.25MPa and a high temperature of 260 ℃. These silver ions have extremely high biological activity and have a strong killing effect on microorganisms such as bacteria and viruses. In this paper, the antibacterial properties of some typical organic antibacterial agents and common inorganic antibacterial agents are compared

test part

preparation of antibacterial and mildew proof powder

mix a certain proportion of antibacterial and mildew proof powder materials with pure polyester and pure epoxy resin, and mix them well. Melt and mix through a twin-screw extruder, press, cool and crush, and then put it into a grinder to crush it into a powder coating with appropriate particle size

take an appropriate amount of antibacterial and mildew proof powder coating, spray it on the template with an electrostatic spray gun, place it in an oven at the set temperature, take it out after curing for the specified time, and place it at room temperature for 24h. The antibacterial properties of antibacterial coatings were tested according to the gb/t national standard test method, and the impact resistance, bending resistance and scratch resistance of the samples were tested respectively

antibacterial performance test

strictly follow the microbial detection method required by gb/t, taking 0 5ml of test bacterial solution was added to the negative control sample (a), blank control (b) and antibacterial coating sample (c). Cover the sample plate with sterilized membrane so that the bacteria can evenly contact the surface of the sample plate. Incubate it in a plate at 37 ± 1 ℃ and a relative humidity of> 90% for 24 hours under the condition of enhanced ability to deal with trade protectionism. Then, elute, culture, count and calculate the antibacterial rate

results and discussion

antibacterial properties of organic zinc antibacterial agents in low temperature process antibacterial powder coatings

organic zinc antibacterial agents are antibacterial and mildew proof agents with excellent performance, which are widely used at home and abroad. Organic zinc antibacterial agents have excellent antibacterial, mildew proof and algae resistant properties, and are widely used in antibacterial, mildew proof and algae resistant coatings. The antibacterial properties of organic zinc antibacterial agents are shown in Table 1

it can be seen from table 1 that under the condition of baking time of 20min, organic zinc antibacterial agents show completely different antibacterial properties with different baking temperature. When the baking temperature is 180 ℃ and below, organic zinc antibacterial agents show good antibacterial properties. When the baking temperature is higher than 180 ℃, organic zinc completely loses antibacterial activity. The main reason is the rapid decomposition of organic zinc antibacterial agents under high temperature conditions above 180 ℃, resulting in the complete loss of antibacterial activity of organic zinc antibacterial agents

inorganic silver antibacterial agent in high temperature process antibacterial powder coating antibacterial performance

inorganic silver antibacterial agent is an antibacterial agent with good temperature resistance, and its normal temperature resistance can reach more than 500 ℃. In order to meet the requirements of national and regional regulations, two inorganic silver antibacterial agents, glass loaded silver and zirconium phosphate loaded silver, were used to evaluate the antibacterial properties of the two carriers. The antibacterial properties of epoxy and polyester powder coating systems against Escherichia coli and Staphylococcus aureus were evaluated under the test conditions: baking temperature 220 ℃, baking temperature 30 minutes

it can be seen from table 2 that both epoxy formula system and polymer formula system are at 0 0% glass loaded silver antibacterial agents showed good antibacterial properties. The antibacterial rate of both Escherichia coli and Staphylococcus aureus was more than 99.9%, which had good antibacterial properties. The antibacterial effect of inorganic glass containing silver in powder coatings is very outstanding

remarks: ld904 is a glass bead loaded silver powder antibacterial agent; Pr12 is epoxy system, Pr16 is polyester system

Table 3 shows the antibacterial performance test of zirconium phosphate silver loaded antibacterial powder on powder coated boards, and zirconium phosphate silver loaded antibacterial powder is at 0 Under the condition of 0% addition, the antibacterial rate of both Escherichia coli and Staphylococcus aureus exceeded 99.9%. Compared with glass loaded silver, it has the same antibacterial performance, and its antibacterial effect has nothing to do with the carrier, only related to the active ingredients. However, different carriers are used in different national and regional regulatory systems, which is also particularly important

remarks: ld940 is zirconium phosphate silver loaded powder antibacterial agent

inorganic zinc antibacterial agent in high temperature process antibacterial powder coating antibacterial performance

inorganic zinc antibacterial agent is also an antibacterial agent with good temperature resistance, and the normal temperature resistance can also reach more than 500 ℃. The test uses glass loaded nano zinc oxide as antibacterial agent. They are doing a comparative test by flame retardant pc+abs (engineering plastic alloy) bayblond. Under the test conditions, the baking temperature is 220 ℃, Under the baking temperature of 30 minutes, the antibacterial properties of powder coated plates with different color systems were tested, and their antibacterial properties against Escherichia coli and Staphylococcus aureus were tested respectively

in Table 4, 10 groups of samples were tested for antibacterial effect against Staphylococcus aureus and Escherichia coli. The antibacterial activity against Staphylococcus aureus reached 4.9, that is, the antibacterial rate exceeded 99.99%. For Escherichia coli, under the test conditions, the antibacterial activity value reached 3.3, that is, the antibacterial rate exceeded 99.9%. In addition, it can be seen that the addition of various pigments does not affect the antibacterial properties of inorganic zinc antibacterial agents. Inorganic zinc antibacterial agent shows excellent antibacterial properties under the condition of high temperature and long-term baking

comparison of antibacterial results between internal extrusion and external mixing processes

antibacterial agents are added to powder coatings in two ways: internal extrusion and external mixing. The powder coating sample is prepared with glass loaded silver as antibacterial agent. The influence of the addition process on the antibacterial performance is investigated. From the antibacterial performance results in table 5, it can be seen that whether it is external mixing and internal extrusion, the antibacterial rate of silver antibacterial agents on Escherichia coli and Staphylococcus aureus exceeds 99.0%, It has good antibacterial properties

conclusion

there are many kinds of antibacterial agents, but there are few kinds of antibacterial agents suitable for high temperature curing powder coatings. Most organic antibacterial agents and natural antibacterial agents will lose their antibacterial properties in powder under high temperature baking conditions. Organic zinc is one of the few organic antibacterial agents suitable for low-temperature baking powder coatings with obvious cost-effectiveness advantages. Inorganic antibacterial agents have excellent high-temperature resistance. Whether it is glass silver carrying system or zirconium phosphate silver carrying system, the antibacterial rate of silver antibacterial agents can reach more than 99% against Escherichia coli and Staphylococcus aureus with appropriate addition. Silver antibacterial agents have good antibacterial properties in the field of powder coatings. Similarly, among inorganic materials, inorganic zinc antibacterial agents also have excellent antibacterial properties in powder coatings. In terms of antibacterial factors, colorants have no effect on the antibacterial properties of silver zinc antibacterial agents. In terms of processing technology, whether it is external mixing or internal extrusion, it will not affect the antibacterial performance of silver antibacterial agent