Antibacterial and antiviral powder coating is a functional powder coating formulated with specific active ingredients on the coating surface to inhibit or kill bacteria and viruses that come into contact with it.
This article systematically introduces the definition, characteristics, functions, applications, selection considerations, and common problems and solutions related to antibacterial and antiviral powder coatings. It focuses particularly on the functions of antibacterial and antiviral powder coatings to help readers better understand what they are, as well as their characteristics and applications.
What Are Antibacterial and Antiviral Powder Coatings?
They are functional coatings that incorporate specific active ingredients (such as silver ions and quaternary phosphonium salts) into traditional powder coating formulations, enabling the coating surface to continuously inhibit or kill bacteria and viruses. They are not instant disinfectants; instead, they work continuously through daily contact to reduce the microbial load on surfaces.
Characteristics of Antibacterial and Antiviral Powder Coatings
The main performance characteristics of antibacterial and antiviral powder coatings are reflected in the following aspects:
Fast Antibacterial Action: According to ISO 22196. some products can achieve a reduction rate of over 99% against Escherichia coli and Staphylococcus aureus after 2 hours of contact.
Longer Contact Time Required for Antiviral Performance: According to ISO 21702. contact typically needs to last 24 hours. Some products achieve reduction rates of over 95% against human coronavirus OC43 and influenza virus H1N1. and over 99% against SARS-CoV-2.
Effective Against Drug-Resistant Bacteria: Some products are also effective against drug-resistant bacteria such as MRSA.
Long-Lasting Functionality: The active ingredients are designed to provide continuous functionality and withstand routine cleaning and wiping without rapidly losing their effectiveness.
Functions of Antibacterial and Antiviral Powder Coatings
The specific functions of antibacterial and antiviral powder coatings are reflected in the following aspects:
Contact-Based Microorganism Elimination: Active ingredients in the coating, such as polymeric quaternary phosphonium salts, attract bacteria through electrostatic interactions and destroy their cell membranes, thereby killing them. Some products use sustained-release silver ions to inhibit microbial growth.
Fast Antibacterial Action: According to ISO 22196. some products achieve a reduction rate of over 99% against Escherichia coli, Staphylococcus aureus, and drug-resistant bacteria such as MRSA after 2 hours of contact.
Longer Contact Time Required for Antiviral Performance: According to ISO 21702. some products achieve a reduction rate of over 95% against human coronavirus OC43 and influenza virus H1N1. and over 99% against SARS-CoV-2 after 24 hours of contact.
Continuous Reduction of Surface Microbial Load: The coating works continuously between routine cleaning sessions, helping reduce the risk of contact transmission. However, it cannot replace standard cleaning and disinfection procedures.
Wipe Resistance and Long-Lasting Functionality: The antibacterial and antiviral functions are activated after coating application and can withstand routine cleaning and wiping without rapidly losing effectiveness.
Application Fields of Antibacterial and Antiviral Powder Coatings
The specific application fields of antibacterial and antiviral powder coatings include the following:
- Medical and Hygiene-Sensitive Environments
Medical Equipment and Furniture: Including hospital beds, diagnostic equipment, hospital furniture, and pharmaceutical laboratory equipment.
Areas with High Cleanliness and Hygiene Requirements: Such as cleanrooms, food processing equipment, and bathroom accessories.
- Educational and Children’s Facilities
Schools and Kindergartens: Teaching equipment, children’s furniture, and metal playground facilities.
Metal Playground Equipment: Some commercial products explicitly list metal playground equipment among their applications.
- Public Transportation and Public Facilities
High-Frequency Contact Components: Public transportation handrails, door handles, lockers, and control panels for vending machines and ATMs.
Public Furniture and Street Facilities: Airport and railway station furniture, street furniture, and shopping mall fixtures.
- Fitness and Sports Environments
Fitness Equipment: Public or commercial fitness equipment.
Locker Room Facilities: Such as locker room storage cabinets.
- Home Appliances and General Industrial Products
Home Appliances: Some antibacterial powder coatings are suitable for home appliance surfaces.
Electronics, Electrical Appliances, and Building and Home Furnishings: Patent documents also mention protective applications in the fields of electronics, electrical appliances, building materials, and home safety.
How to Select Antibacterial and Antiviral Powder Coatings
When selecting antibacterial and antiviral powder coatings, we may face difficulties in determining which products are suitable. Based on our industry experience, we recommend focusing on the following aspects when selecting antibacterial and antiviral powder coatings.
- Identify the Applicable Standards First and Avoid Unsupported Claims
Require the supplier to clearly specify the standards according to which its products are tested and evaluated.
Industry Standards as a Basic Requirement: The T/CNCIA 01014-2020 standard, Antibacterial and Antiviral Coatings, issued by the China National Coatings Industry Association, applies to powder coatings and classifies products into Grade I and Grade II. Grade I is intended for environments with higher requirements, such as hospitals and schools. Its antiviral performance requirements include an antiviral rate of ≥99.9% against H3N2 and ≥95.0% against EV71.
Verify the Appropriateness of Testing Methods: Confirm whether antibacterial and antiviral testing is conducted according to ISO 22196. ISO 21702. or relevant domestic testing standards. Different methods have different contact times and evaluation criteria, and their results must not be used interchangeably.
- Verify Actual Test Data and Pay Attention to “Time and Test Organisms”
Antibacterial and antiviral effectiveness is closely related to contact time. Therefore, it is essential to obtain data that matches your intended application scenario.
Antibacterial Data: Require test reports for the specific bacterial strains of interest, such as Escherichia coli, Staphylococcus aureus, and MRSA. Confirm the reduction rate and corresponding contact time (such as 2 or 24 hours).
Antiviral Data: Confirm the tested viral strains (such as human coronavirus and influenza virus) and contact time. Some products require 24 hours of contact to achieve their claimed antiviral reduction rates. If your application requires rapid effectiveness, confirm feasibility in advance.
Report Sources: Give priority to reports issued by third-party testing organizations with CNAS/CMA accreditation rather than data from the supplier’s internal laboratory.
- Confirm the Type of Antibacterial Agent and Its Durability
Different active ingredients vary considerably in durability and safety. Their suitability should be evaluated according to the application environment.
Silver-Based vs. Organic Antibacterial Agents: Inorganic silver-based antibacterial agents generally offer good heat resistance and durability. For organic agents such as quaternary phosphonium salts, confirm whether they participate in the curing crosslinking process to prevent migration and leaching.
Durability Verification: Ask whether the supplier provides data demonstrating the retention of antibacterial activity after wiping, water exposure, and light exposure. Coatings may wear during routine cleaning, and high initial effectiveness does not necessarily indicate long-term performance.
Common Problems and Solutions for Antibacterial and Antiviral Powder Coatings
The most common problems encountered during the use of antibacterial and antiviral powder coatings are mainly reflected in the following aspects. Based on our industry experience, we have proposed corresponding solutions to help effectively address powder coating problems you may encounter.
- Deterioration or Loss of Antibacterial/Antiviral Functionality (Function-Specific Issue)
Problem Description: The coating initially passes testing, but its antibacterial/antiviral effectiveness decreases significantly after a period of use or after wiping and water washing.
Main Causes:
Excessive Silver Ion Release or Loss During Curing: During high-temperature curing of powder coatings (180–200°C), silver ions in traditional silver-based antibacterial agents can easily be reduced to metallic silver, resulting in the loss of antibacterial activity. Meanwhile, the release rate of silver ions is difficult to control, and routine wiping accelerates their depletion.
Uneven Dispersion or Migration of Antibacterial Agents: Small-molecule antibacterial agents may have poor dispersion in the coating or migrate to the surface over time and subsequently be removed by wiping, resulting in reduced functional durability.
Solutions:
Select Products Designed for Durability: Give priority to silver-based antibacterial agents with synergistic copper/zinc ion protection (copper ions are preferentially reduced during curing, protecting silver ions from reduction), or use non-leaching antibacterial agents such as polymeric quaternary phosphonium salts. The latter have high molecular weights and participate in curing crosslinking, making them less likely to migrate.
Request Durability Data: Require the supplier to provide reports on antibacterial activity retention after wiping (such as hundreds to thousands of wiping cycles) and water washing, rather than evaluating products solely based on initial test results.
Verify Performance After Curing: Confirm that the test reports are based on sample panels tested under actual curing conditions, rather than tests conducted on uncured powder or under ideal laboratory conditions.
- Coating Surface Defects (Cratering / Pinholes)
Problem Description: Circular depressions (craters) or small penetrating holes (pinholes) appear on the coating surface. These defects not only affect appearance but may also become starting points for corrosion.
Main Causes:
Contamination Sources: Oil or moisture in compressed air, pretreatment residues, silicone oil in the environment, or contamination from incompatible powder coatings.
Substrate Outgassing: Gas escapes during baking from porous substrates (such as castings) or residual pretreatment liquids.
Excessive Film Thickness: Excessive powder application in a single spraying operation prevents bubbles from escaping.
Solutions:
Purify the Air Supply and Environment: Install oil-water separators to ensure compressed air quality. Prohibit the use of silicone oil-containing products in the spraying area. Thoroughly clean the powder coating system to prevent cross-contamination between different powders.
Strengthen Pretreatment Cleaning: Ensure thorough cleaning after degreasing and phosphating to prevent residual liquids from remaining on the substrate.
Control Film Thickness and Preheating: Keep the film thickness within the recommended range (usually ≤120 μm) for a single application. For porous substrates, preheating or pre-baking can be used to release gas in advance.
- Poor Adhesion (Peeling / Cracking)
Problem Description: The coating peels off the substrate in large sections or isolated spots, or cracks during subsequent bending and impact processing.
Main Causes:
Insufficient Pretreatment: Incomplete degreasing or poor phosphating quality is a fundamental cause. Powder coatings cannot compensate for deficiencies in the pretreatment process.
Insufficient Curing: The actual metal temperature of the workpiece fails to reach the required curing temperature, resulting in incomplete crosslinking.
Insufficient Formulation Flexibility: During customization, excessive emphasis is placed on hardness or decorative properties while insufficient attention is paid to the flexibility required for subsequent processing.
Solutions:
Strictly Control the Pretreatment Process: Regularly test the concentrations of degreasing and phosphating bath solutions and ensure thorough cleaning after each process step.
Use an Oven Temperature Profiling Instrument to Verify Curing: Measure the actual temperature profile of the workpiece surface and confirm that the required workpiece metal temperature and holding time specified by the supplier have been achieved, rather than relying solely on the oven temperature setting.
Specify Processing Requirements During Customization: If the workpiece requires bending or stamping, inform the supplier during the sampling stage and request adjustments to formulation flexibility, along with cupping and bending tests.
- Color/Appearance Does Not Match the Approved Sample
Problem Description: After the delivered powder is applied, the resulting color visibly differs from the approved sample, or the gloss and texture are inconsistent.
Main Causes:
Batch Variations: Variations in pigment dosage or production processes cause color differences between batches.
Deviations in Application Parameters: Spray voltage, air pressure, and spray gun distance differ from those used during sample preparation.
Uncontrolled Recycled Powder Ratio: Changes in the proportions of pigments or additives in recycled powder affect the resulting color.
Solutions:
Agree on Color Difference Standards and Retain Samples: Clearly specify the allowable color difference in the contract (such as ΔE ≤1) and require each batch to be compared with the retained reference sample.
Standardize Application Parameters: Prepare written work instructions specifying the voltage, air pressure, spray gun distance, and conveyor speed used during sample preparation, and strictly follow them during mass production.
Control the Recycled Powder Ratio: For standard powder coatings, the recommended recycled powder addition ratio is ≤1/3; for powder coatings with high metallic content, it is ≤1/5. Color evaluation must also be conducted before adding recycled powder.
Choose Professional Antibacterial and Antiviral Powder Coatings to Create Safer and Cleaner Product Surfaces
Antibacterial and antiviral powder coatings use functional antibacterial technology to effectively inhibit the activity of specific bacteria and viruses on coating surfaces. They also offer corrosion resistance, wear resistance, and decorative properties, making them widely applicable to medical equipment, public facilities, home appliances, metal furniture, and food-related equipment.
With more than 20 years of experience in powder coating research, development, and manufacturing, we can provide customized antibacterial and antiviral powder coating solutions based on different application environments, antibacterial performance requirements, and product standards, meeting customers’ diverse requirements for coating safety, durability, and appearance.
Choose our antibacterial and antiviral powder coatings to enhance your products with professional protective properties and improve surface hygiene protection. Contact us to obtain customized product solutions and technical support!
