X-MINING What is Antibacterial Action? Differences and Mechanisms Compared to Disinfection and Sterilization

Managing microbial contamination is significant in various fields. This management is represented by the concept of “antibacterial,” which varies depending on the products in each field. In Japan, only “complete sterilization” has legal criteria for its effectiveness, while other criteria are voluntarily set by manufacturers and related organizations. Microorganisms mentioned here include “bacteria,” “viruses,” and “fungi.” In the medical field, the terms “bacteriostatic,” “disinfection,” “sterilization,” and “complete sterilization” encompass all methods used for pharmaceuticals, their manufacturing environments, and medical devices.

In non-medical fields like home appliances, goods, and detergents, “disinfection” is used with a slightly different meaning.

What is Antibacterial?

“Antibacterial” refers to suppressing the growth and proliferation of microorganisms. According to the Japanese Industrial Standards (JIS), it’s defined as “a state where bacterial growth on the product surface is inhibited.”

This does not mean killing or removing bacteria. Products treated with antibacterial processes can maintain cleanliness, making it difficult for bacteria to proliferate.

What is Disinfection?

“Disinfection” means removing microorganisms like bacteria and viruses, thereby reducing their numbers. This includes reducing microorganisms in products and air.

For example, everyday actions like washing hands or dishes are part of disinfection. Disinfection is essential for preventing infectious diseases and managing hygiene.

What is Sterilization?

“Sterilization” means killing microorganisms such as bacteria, fungi, and viruses. For example, if a label on a chemical or specific product says “sterilization,” it means it can kill at least one type of bacterium.

Sterilization is recognized under the Pharmaceuticals and Medical Devices Law, and is used in medicated soaps and detergents.

What is Complete Sterilization?

“Complete Sterilization” means reducing the presence of microorganisms and bacteria as close to zero as possible. Products that undergo complete sterilization include medical devices like bandages and surgical instruments.

The definition includes reducing the number of bacteria to one in a million from the state before sterilization. Therefore, outside the medical field, the strength of action increases in the order of antibacterial, disinfection, sterilization, and complete sterilization.

Copper and its alloys are known to possess strong antibacterial properties. The mechanism is thought to be as follows:
1. Metal surfaces react with moisture in the air, generating copper ions.
2. These copper ions and the simultaneously produced hydrogen peroxide cause a Fenton reaction, creating highly oxidative active oxygen species.
3. These active oxygen species destroy the chromosomes and cell membranes of microorganisms, promoting sterilization.

For example, using metals directly in products or attaching compounds and ions to product surfaces can suppress the proliferation of microorganisms. Research suggests that not just the copper ions leaching from the surface but the actual contact between copper surfaces and bacteria, leading to a Fenton reaction and resulting active oxygen, damages bacterial DNA and achieves antibacterial effects.

The specific antibacterial mechanisms vary depending on the metal, but each is utilized in our daily lives considering their characteristics.

The Japan Copper Center (JCDA) announced a comparison of antibacterial properties of metal materials used for doorknobs at Kitasato University Hospital. According to their findings, copper alloys such as bronze and brass have higher antibacterial properties than stainless steel.

Furthermore, the Copper Development Association (CDA) in various countries has verified the sterilization effect of copper and copper alloys on surfaces in medical facilities. They found that these materials could kill over 99.9% of pathogens, including Methicillin-resistant Staphylococcus aureus (MRSA), within two hours.

As a result, in 2008, the United States Environmental Protection Agency (EPA) legally recognized that “copper, brass, and bronze can kill harmful, potentially deadly pathogens, contributing to public health.” Copper and its alloys were the first solid materials recognized by the EPA for their antibacterial properties, proving their effectiveness against various pathogenic bacteria.

In Japan, these characteristics are utilized in daily goods such as ” triangle sink strainers made of copper, which are less likely to develop slime, and socks containing copper fibers for deodorization and prevention of athlete’s foot,” which we use in our daily lives.

There are several symbols that indicate antibacterial properties, each with its own features and purposes. Here we introduce three main marks commonly used for this purpose.
– SEK Mark
– SIAA Mark
– CU STAR Mark

SEK Mark

Image source: THE CERTIFICATION STANDARDS OF SEK MARK TEXTILE PRODUCTS｜Product certification mark SEK｜JTETC

The SEK Mark is a symbol that guarantees the functionality and quality of textile products that have undergone functional processing.

The SEK Mark is a mark that certifies functional finished textile products. Textile products that have undergone functional processing can display the SEK Mark only if they meet the standards set by the Japan Textile Evaluation Technology Council.

SIAA Mark

Image source: What are SIAA marks?│SIAA
The SIAA Marks are the symbols for KOHKIN and were established by the Society of Industrial Technology for Antimicrobial Articles

To obtain the SIAA Mark, a product must prove effective against invisible bacteria and viruses.

Various products, including household goods and electronics, can carry this mark, providing consumers with reassurance and the ability to identify antibacterial products. However, textiles are excluded.

CU STAR Mark

Japan Copper Development Association has created the CU STAR Mark, exclusive to Japan, to promote the use of materials and products that utilize copper’s superior antibacterial properties.

Materials and products eligible for the CU STAR Mark include copper and copper alloy materials containing over 60% copper, copper vapor-deposited films, copper fiber products, and composite products that mix copper powder with plastic, all of which possess superior antibacterial properties.

The categories include “super antibacterial copper materials” and “super antibacterial copper products” made from copper and copper alloys, as well as “super antibacterial composite copper materials” and “super antibacterial composite copper products” that combine copper with other materials. As of October 18, 2023, 42 materials and products with superior antibacterial performance have been certified with the CU STAR Mark.

Sumitomo Metal Mining is also considering obtaining the CU STAR Mark for its “fine copper powder.” Please see below for more details on fine copper powder.

Focusing on the antibacterial properties of copper, Sumitomo Metal Mining offers fine copper powder developed in-house. Here, we explain the characteristics and potential applications of fine copper powder.

About Sumitomo Metal Mining’s Fine Copper Powder

Sumitomo Metal Mining’s Fine copper powder is capable of reducing sintering temperatures compared to conventional atomized copper powder, contributing to optimization of manufacturing processes and reduction of energy consumption. Additionally, improved specific surface area enhances antibacterial properties, and increased transparency and reduced brown color of copper enhance aesthetic appeal. These features make our fine copper powder suitable for various high-quality applications.

Our fine copper powder (UCP series) is produced using powder control technology developed by Sumitomo Metal Mining over many years.

With a unique surface treatment, it exhibits oxidation resistance over a wide temperature range from room temperature to 200 degrees, shows high stability in the atmosphere, and offers excellent handling properties.

Adding fine copper powder to other atomized copper powder, which has a higher sintering start temperature, can lower the sintering temperature, optimizing the manufacturing process and saving energy.

For more information, please see the “Fine Copper Powder Product Page” in our website.

Potential Applications of Fine Copper Powder in Antibacterial Applications

By mixing copper powder with resin, it can be used as a film agent or mixed with solvents as a coating agent. Sumitomo Metal Mining’s fine copper powder, due to its “fine” particle size, can improve transparency, potentially enhancing design appeal. These materials can be applied to antibacterial coatings for transparent touch displays and tableware.

Copper exhibits a potent antibacterial effect, disrupting the DNA and cellular structures of microorganisms on copper surfaces, and thus impeding the growth of bacteria and other pathogens.

As a result, copper-based items such as doorknobs and medical devices, and other have become increasingly prevalent in our daily lives.

Sumitomo Metal Mining’s “fine copper powder” aims for application in various fields, including electronics and antibacterial purposes introduced in this article.

Sumitomo Metal Mining has launched the “X-MINING” project to create new technologies and solve challenges. If you’re interested, please feel free to contact us.