Research and effect comparison of low temperature and high temperature powder coating antibacterial agents

Antibacterial agents can be divided into organic antibacterial agents and inorganic antibacterial agents according to their materials. Organic antibacterial agents are traditional antimicrobial agents, which are widely used in various industrial fields, and inorganic antimicrobial agents are made by combining the antibacterial components Ag-plus, Cu2-plus, Zn2-plus plasma and their compounds and other metals with inorganic materials. In some fields, organic antibacterial agents with good heat resistance, high safety, long antibacterial durability advantages have been rapid development, can be widely used in coatings, organic plastics, fibers, ceramics, enamel and other fields

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powder coating is often used in a humid climate, moderate temperature environment, coating surface may be affected by bacteria, mold and other harmful microorganisms, resulting in film staining, color change, powdering, shedding, loss of the substrate protection and decoration function. If harmful bacteria come into contact with the human body can also spread a variety of diseases, threatening human health.
has come a long way since the new coronavirus global pandemic began in 2019. In the field of powder coatings, because powder coating products are closely related to people's lives, antibacterial and antiviral powder coating products will become a new development trend in the future, new antibacterial functional materials will be more and more popular with consumers.
Because powder coating baking temperature is generally higher, baking time is long, can be used for powder coating organic antibacterial agent types are relatively small, for baking temperature is not high, baking time is short powder coating, organic zinc, organic copper antibacterial agent due to high cost-effective, can be used in low-temperature process of powder coating antibacterial. In inorganic antimicrobial agents, silver and zinc inorganic antimicrobial agents are typical of inorganic antimicrobial agents.
as early as the 4th century BC, silver was found to have a disinfection effect, 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 metal silver is non-toxic and inert to human cells and viruses and other microorganisms. However, under the effects of H2O and O2 in the environment, silver atoms located on the surface of metallic silver or silver-carrying materials release free silver ions. These silver ions are highly biologically active and have a strong killing effect on microorganisms such as bacteria and viruses. In this paper, some comparative studies are made on the antibacterial properties of some typical organic antimicrobials and commonly used inorganic antimicrobial agents.
test part
preparation of antibacterial anti-mold powder
a certain proportion of antibacterial anti-mold powder materials and pure polyester, pure epoxy resin mixed together, fully mixed evenly. Melting and mixing through the twin screw extruder, the flakes are cooled, crushed, and then placed in a grinder to crush the powder coating with the right particle size.
the appropriate amount of antibacterial anti-mold powder coating, sprayed with electrostature spray gun on the sample, placed in the oven set temperature, curing the specified time after removal, room temperature placed 24h. According to GB/T21866-2008 antibacterial coating national standard detection method to detect its antibacterial properties, respectively, detection of sample impact resistance, bending resistance and scratch resistance performance.
antibacterial performance testing
in strict accordance with GB/T21866-2008 required microbial testing methods, respectively, 0.4-0.5 ml of test bacteria droplets added to the negative control model (A), blank control (B) and antibacterial coating model (C). Cover the model with sterilized membrane, so that the bacteria evenly contact the surface of the sample plate, in a flat dish, at 37 to 1 degree C, relative humidity of 90% of the conditions of culture for 24 hours. Then, wash, culture, count, calculate the antibacterial rate.
Results and discussion
Organic zinc antibacterial agent in the low-temperature process antibacterial powder coating antibacterial properties
organic zinc antibacterial agent is a good performance antibacterial anti-mold agent, widely used at home and abroad, organic zinc antibacterial agent has excellent antibacterial, anti-mold and anti-algae properties, widely used in the coating antibacterial mold and anti-algae. The antibacterial properties of organic zinc antimicrobial agents are shown in Table 1.
From Table 1, it can be seen that under the condition of 20min baking time, with the different baking temperature, organic zinc antibacterial agents show completely different antibacterial properties, when the baking temperature is 180 degrees C and below, organic zinc antibacterial agents show good antibacterial properties, when the baking temperature is above 180 degrees C, organic zinc completely lost antibacterial activity. The main reason is that organic zinc antibacterial agents break down rapidly at high temperatures above 180 degrees C, resulting in the complete loss of antibacterial activity of organic zinc antibacterial agents.
inorgic silver antibacterial agent in the high-temperature process antibacterial powder coating antibacterial properties
inorderable silver antibacterial agent is a better temperature resistance antibacterial agent, normal temperature resistance performance can reach more than 500 degrees C. In order to meet the regulatory requirements of countries and regions, the two inorgium silver antimicrobial agents of glass-carrying silver and zirconium phosphate were used to evaluate the antibacterial properties of silver-carrying two carriers. In the test conditions are: baking temperature of 220 degrees C, baking temperature of 30 minutes, the formula system for epoxy and polyester two powder coating systems, respectively, to evaluate its antibacterial properties against E. coli and Staphylococcus acobacteria.
From Table 2, it can be seen that whether it is epoxy formulation system or polypronoxytic formula system, antibacterial agents in 0.4-1.0% glass silver have shown good antibacterial properties, whether for E. coli or Staphylococcus auspicrus, antibacterial rate of more than 99.9%, with good antibacterial properties. The antibacterial effect of inorgic glass silver in powder coating is very prominent.
note: LD904 is a glass microbead silver powder antibacterial agent, PR12 is an epoxy system, PR16 is a polyester system
Table 3 is a silver antibacterial powder of zirconium phosphate on a powder coating board Antibacterial performance test, phosphate silver-carrying antibacterial powder in 0.4-1.0% of the added amount of conditions, whether for E. coli or Staphylococcus aphdotes, antibacterial rate of more than 99.9%. Compared with glass silver, it has the same antibacterial properties, and its antibacterial effect is not related to the carrier, only to the active ingredients. However, it is particularly important that different carriers are used in different countries and regions' regulatory systems.
Note: LD940 is a silver powder antibacterial agent phosphate
inorganic zinc antibacterial agent in high temperature process antibacterial powder coating antibacterial properties
inorganic zinc antibacterial agent is also a better temperature resistance antibacterial agent, normal temperature resistance can also reach 500 degrees C Above, the test uses glass-mounted nano-zinc oxide as an antibacterial agent for comparative testing, in the test conditions, baking temperature of 220 degrees C, baking temperature of 30 minutes, the powder coating plate of different colors to test its antibacterial properties, respectively, to test its antibacterial properties against E. coli and Staphylococcus aureus.
table 4, 10 groups of samples were tested for antibacterial effects on Staphylococcus acobacteria and E. coli, respectively. The antibacterial vitality value of Staphylococcus aelobacter reached 4.9, i.e. the antibacterial rate exceeded 99.99%. For E. coli, under the test conditions, the antibacterial vitality value reached 3.3, i.e. the antibacterial rate exceeded 99.9%. In addition, it can be seen that the addition of various colors does not affect the antibacterial properties of inorganic zinc antibacterial agents. Inorganic zinc antibacterial agents show excellent antibacterial properties under high temperature and long-term baking conditions.
Intro-extrusion and ex-mixing process antibacterial results comparison
antibacterial agent added to the powder coating there are two ways of internal extrusion addition and ex-mixing added to the glass silver as an antibacterial agent, preparation of powder coating model, to investigate the effects of the added process antibacterial properties, from Table 5 antibacterial performance results, whether it is excopolation and extrusion, silver antibacterial agents on E. coli and Staphylococcus acuity resistance rate of more than 99.0%.
theory
there are more types of antimicrobial agents, but fewer types of antimicrobials suitable for high temperature curing powder coatings. Most organic antimicrobials and natural antimicrobials lose their antibacterial properties in powders under high temperature baking conditions. Organic zinc is one of the few organic antimicrobial agents suitable for low temperature baking powder coating cost-effective antibacterial agent. Inorbic antibacterial agent high temperature resistance performance is excellent, whether it is glass silver system, or zirconium phosphate silver system, silver antibacterial agent in the appropriate amount of addition, regardless of E. coli, Staphylococcus aphdolic, antibacterial rate can reach more than 99%, silver antibacterial agent in the field of powder coating has good antibacterial properties. Also in inorganic materials, inorganic zinc antibacterial agents in powder coating antibacterial properties are also excellent. In terms of antibacterial influence factors, colorants had no effect on the antibacterial properties of silver zinc antibacterial agents. In the processing process, whether it is mixed or introsted, will not affect the antibacterial properties of silver antibacterial agents.
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