Principles of Anti-bacterial Yarn
The principle of anti-bacterial yarn is mainly through the physical structure, chemical additives or natural ingredients to destroy the bacterial metabolism and growth environment, specifically can be divided into the following mechanisms:
First. Chemical antibacterial mechanism
Metal ions interfere with metabolism
Silver, copper, zinc and other metal ions combine with bacterial enzymes and proteins through contact reaction to inactivate them, or produce reactive oxygen species through catalytic reaction to destroy bacterial structure. For example, silver ions coagulate bacterial proteins and continue to catalyze sterilization under light.
Bio-based ingredients inhibit physiological activities
Natural ingredients such as citric acid are used to interfere with bacterial metabolism, blocking their energy synthesis and proliferation processes. These technologies are based on renewable bio-based materials and are both environmentally friendly and safe.
Antibacterial Masterbatch Addition
Masterbatches containing inorganic/organic antimicrobial agents are blended during the spinning process and dispersed uniformly in the fiber. The masterbatch binds negatively charged bacteria through cationic immobilization or directly destroys the cell wall resulting in leakage of the contents.
Second, the physical structure of the impact
Fiber structure inhibits bacterial reproduction
Such as hemp fiber hollow structure can improve oxygen content, inhibit the growth of anaerobic bacteria; nanoscale fiber surface through physical adsorption to reduce bacterial adhesion.
Third, natural antibacterial components
Plant-derived antibacterial substances
Hemp fiber containing flavonoids can directly inhibit bacteria, bamboo fiber, seaweed fiber and other natural materials also have antibacterial properties.
Fourth, the technical characteristics and effects
Durability: metal ions, antimicrobial masterbatch and other technologies have excellent washing resistance and can withstand high temperatures and multiple washing.
Compatibility: antimicrobial agents have little effect on the dyeing performance of fibers, and do not affect the mechanical properties of yarn.
The effectiveness of antimicrobial yarn needs to be judged comprehensively through standardized testing methods and performance evaluation system, which can be assessed from the following dimensions:
i. Classification of testing methods
Principle: Preliminary judgment of antimicrobial effect by observing the antibacterial zone or bacterial growth after contacting the sample with bacteria.
Commonly used methods:
Agar Plain Diffusion Method: Apply the sample to the surface of agar inoculated with bacterial solution and observe the extent of the zone of inhibition after incubation.
Parallel scribing method / halo method: Judge the antibacterial property by the growth inhibition of the bacterial liquid after scribing and contacting with the sample.
Applicable scenarios: rapid screening of yarns with solubilizing or non-solubilizing antimicrobial effects.
Principle: To accurately assess the antimicrobial rate by comparing the value of reduction in the number of bacteria in the treated group and the control group.
Commonly used methods:
Shaking method: Applicable to non-solubilized antimicrobial yarns (e.g. chemically modified fibers), the colony reduction rate is calculated after contact by shaking.
Absorption method: Applicable to dissolved antimicrobial agents (e.g. finishing processes), testing the inhibition effect on bacteria after the release of the antimicrobial agent.
Advantage: The results are presented in specific values (e.g. bacterial inhibition rate ≥ 99%), which can quantify the antimicrobial effect.
ii. Selection of test strains
Representative strains:
Bacteria: Staphylococcus aureus (Gram-positive bacteria), Escherichia coli (Gram-negative bacteria).
Fungi: Candida albicans (common pathogenic fungi).
Mixed strain test: simulate the complex environment to verify the broad-spectrum antimicrobial properties.
iii. Performance Standards and Indicators
ISO 20743: Applicable to all kinds of antimicrobial textiles, requiring bacterial inhibition rate ≥70%.
AATCC 100: American standard, emphasizing the calculation of antimicrobial rate and experimental repeatability.
GB/T 20944.3-2008: Chinese national standard, standardizing the operation procedure of oscillation method.
Washability: Detect the decay of antimicrobial rate by simulating multiple washings (e.g. 50 washings) to verify the long-lasting effect.
Stability: Test the ability to maintain antimicrobial performance under extreme environments such as high temperature and chemicals.
iv. Safety and environmental evaluation
Detect the skin irritation, sensitization and toxicity of antimicrobial agents (such as acute oral toxicity test).
Verify the effect of antimicrobial yarn on normal skin flora.
Comply with the requirements of REACH and other regulations on the restriction of chemical additives.
v. Verification by third party testing organizations
Authoritative institutions: such as China Science and Technology Testing (CMA/CNAS certification), through a standardized process to issue test reports to ensure data reliability.
Report content: need to include antimicrobial rate, test methods, strain type and washing resistance and other core indicators.
vi. Practical Application Verification
Scenario testing: long-term use in medical, sports and other high-bacteria environments to observe odor suppression, cross-infection control and other practical effects.
